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rx-spec.h
* LWP_DispatchProcess();
* for (;;)
* {
* /* Wait until there is something in the queue */
* while (empty(q)) LWP_WaitProcess(q);
* /* Process the newly-arrived queue entry */
* LWP_DispatchProcess();
* }
* }
* \endcode
*
* \par
* The next routine, write process(), sits in a loop, putting messages on the
* shared queue and signalling the reader, which is waiting for activity on the
* queue. Signalling a thread is accomplished via the LWP SignalProcess()
* library routine.
*
* \code
* static write_process()
* { ...
* /* Loop, writing data to the shared queue. */
* for (mesg = messages; *mesg != 0; mesg++)
* {
* insert(q, *mesg);
* LWP_SignalProcess(q);
* }
* }
* \endcode
*
* \par
* finally, here is the main routine for this demo pseudocode. It starts by
* calling the LWP initialization routine. Next, it creates some number of
* reader threads with calls to LWP CreateProcess() in addition to the single
* writer thread. When all threads terminate, they will signal the main routine
* on the done variable. Once signalled, the main routine will reap all the
* threads with the help of the LWP DestroyProcess() function.
*
* \code
* main(argc, argv)
* int argc;
* char **argv;
* {
* PROCESS *id; /* Initial thread ID */
* /* Set up the LWP package, create the initial thread ID. */
* LWP_InitializeProcessSupport(0, &id);
* /* Create a set of reader threads. */
* for (i = 0; i < nreaders; i++)
* LWP_CreateProcess(read_process, STACK_SIZE, 0, i, "Reader",
* &readers[i]);
*
* /* Create a single writer thread. */
* LWP_CreateProcess(write_process, STACK_SIZE, 1, 0, "Writer", &writer);
* /* Wait for all the above threads to terminate. */
* for (i = 0; i <= nreaders; i++)
* LWP_WaitProcess(&done);
*
* /* All threads are done. Destroy them all. */
* for (i = nreaders-1; i >= 0; i--)
* LWP_DestroyProcess(readers[i]);
* }
* \endcode
*
* \subsection sec2-2-2 Section 2.2.2: Locking
* \par
* The LWP locking facility exports a number of routines and macros that allow
* a C programmer using LWP threading to place read and write locks on shared
* data structures. This locking facility was also written with simplicity in
* mind.
* \par
* In order to invoke the locking mechanism, an object of type struct Lock must
* be associated with the object. After being initialized with a call to
* LockInit(), the lock object is used in invocations of various macros,
* including ObtainReadLock(), ObtainWriteLock(), ReleaseReadLock(),
* ReleaseWriteLock(), ObtainSharedLock(), ReleaseSharedLock(), and
* BoostSharedLock().
* \par
* Lock semantics specify that any number of readers may hold a lock in the
* absence of a writer. Only a single writer may acquire a lock at any given
* time. The lock package guarantees fairness, legislating that each reader and
* writer will eventually obtain a given lock. However, this fairness is only
* guaranteed if the priorities of the competing processes are identical. Note
* that ordering is not guaranteed by this package.
* \par
* Shared locks are read locks that can be "boosted" into write locks. These
* shared locks have an unusual locking matrix. Unboosted shared locks are
* compatible with read locks, yet incompatible with write locks and other
* shared locks. In essence, a thread holding a shared lock on an object has
* effectively read-locked it, and has the option to promote it to a write lock
* without allowing any other writer to enter the critical region during the
* boost operation itself.
* \par
* It is illegal for a process to request a particular lock more than once
* without first releasing it. Failure to obey this restriction will cause
* deadlock. This restriction is not enforced by the LWP code.
* \par
* Here is a simple pseudocode fragment serving as an example of the available
* locking operations. It defines a struct Vnode object, which contains a lock
* object. The get vnode() routine will look up a struct Vnode object by name,
* and then either read-lock or write-lock it.
* \par
* As with the high-level LWP example above, the locking routines introduced
* here will be fully defined later, in Section 2.3.2.
*
* \code
* #include <afs/lock.h>
*
* struct Vnode {
* ...
* struct Lock lock; Used to lock this vnode
* ... };
*
* #define READ 0
* #define WRITE 1
*
* struct Vnode *get_vnode(name, how) char *name;
* int how;
* {
* struct Vnode *v;
* v = lookup(name);
* if (how == READ)
* ObtainReadLock(&v->lock);
* else
* ObtainWriteLock(&v->lock);
* }
* \endcode
*
*
* \subsection sec2-2-3 Section 2.2.3: IOMGR
*
* \par
* The IOMGR facility associated with the LWP service allows threads to wait on
* various unix events. The exported IOMGR Select() routine allows a thread to
* wait on the same set of events as the unix select() call. The parameters to
* these two routines are identical. IOMGR Select() puts the calling LWP to
* sleep until no threads are active. At this point, the built-in IOMGR thread,
* which runs at the lowest priority, wakes up and coalesces all of the select
* requests together. It then performs a single select() and wakes up all
* threads affected by the result.
* \par
* The IOMGR Signal() routine allows an LWP to wait on the delivery of a unix
* signal. The IOMGR thread installs a signal handler to catch all deliveries
* of the unix signal. This signal handler posts information about the signal
* delivery to a global data structure. The next time that the IOMGR thread
* runs, it delivers the signal to any waiting LWP.
* \par
* Here is a pseudocode example of the use of the IOMGR facility, providing the
* blueprint for an implemention a thread-level socket listener.
*
* \code
* void rpc_SocketListener()
* {
* int ReadfdMask, WritefdMask, ExceptfdMask, rc;
* struct timeval *tvp;
* while(TRUE)
* { ...
* ExceptfdMask = ReadfdMask = (1 << rpc_RequestSocket);
* WritefdMask = 0;
*
* rc = IOMGR_Select(8*sizeof(int), &ReadfdMask, &WritefdMask,
* &ExceptfdMask, tvp);
*
* switch(rc)
* {
* case 0: /* Timeout */ continue;
* /* Main while loop */
*
* case -1: /* Error */
* SystemError("IOMGR_Select");
* exit(-1);
*
* case 1: /* RPC packet arrived! */ ...
* process packet ...
* break;
*
* default: Should never occur
* }
* }
* }
* \endcode
*
* \subsection sec2-2-4 Section 2.2.4: Timer
* \par
* The timer package exports a number of routines that assist in manipulating
* lists of objects of type struct TM Elem. These struct TM Elem timers are
* assigned a timeout value by the user and inserted in a package-maintained
* list. The time remaining to each timer's timeout is kept up to date by the
* package under user control. There are routines to remove a timer from its
* list, to return an expired timer from a list, and to return the next timer
* to expire.
* \par
* A timer is commonly used by inserting a field of type struct TM Elem into a
* structure. After setting the desired timeout value, the structure is
* inserted into a list by means of its timer field.
* \par
* Here is a simple pseudocode example of how the timer package may be used.
* After calling the package initialization function, TM Init(), the pseudocode
* spins in a loop. first, it updates all the timers via TM Rescan() calls.
* Then, it pulls out the first expired timer object with TM GetExpired() (if
* any), and processes it.
*
* \code
* static struct TM_Elem *requests;
* ...
* TM_Init(&requests); /* Initialize timer list */ ...
* for (;;) {
* TM_Rescan(requests); /* Update the timers */
* expired = TM_GetExpired(requests);
* if (expired == 0)
* break;
* . . . process expired element . . .
* }
* \endcode
*
* \subsection sec2-2-5 Section 2.2.5: Fast Time
*
* \par
* The fast time routines allows a caller to determine the current time of day
* without incurring the expense of a kernel call. It works by mapping the page
* of the kernel that holds the time-of-day variable and examining it directly.
* Currently, this package only works on Suns. The routines may be called on
* other architectures, but they will run more slowly.
* \par
* The initialization routine for this package is fairly expensive, since it
* does a lookup of a kernel symbol via nlist(). If the client application
* program only runs for only a short time, it may wish to call FT Init() with
* the notReally parameter set to TRUE in order to prevent the lookup from
* taking place. This is useful if you are using another package that uses the
* fast time facility.
*
* \section sec2-3 Section 2.3: Interface Specifications
*
* \subsection sec2-3-1 Section 2.3.1: LWP
*
* \par
* This section covers the calling interfaces to the LWP package. Please note
* that LWP macros (e.g., ActiveProcess) are also included here, rather than
* being relegated to a different section.
*
* \subsubsection sec2-3-1-1 Section 2.3.1.1: LWP_InitializeProcessSupport
* _ Initialize the LWP package
*
* \par
* int LWP_InitializeProcessSupport(IN int priority; OUT PROCESS *pid)
* \par Description
* This function initializes the LWP package. In addition, it turns the current
* thread of control into the initial process with the specified priority. The
* process ID of this initial thread is returned in the pid parameter. This
* routine must be called before any other routine in the LWP library. The
* scheduler will NOT be invoked as a result of calling
* LWP_InitializeProcessSupport().
* \par Error Codes
* LWP EBADPRI The given priority is invalid, either negative or too large.
*
* \subsubsection sec2-3-1-2 Section 2.3.1.2: LWP_TerminateProcessSupport
* _ End process support, perform cleanup
*
* \par
* int LWP_TerminateProcessSupport()
* \par Description
* This routine terminates the LWP threading support and cleans up after it by
* freeing any auxiliary storage used. This routine must be called from within
* the process that invoked LWP InitializeProcessSupport(). After LWP
* TerminateProcessSupport() has been called, it is acceptable to call LWP
* InitializeProcessSupport() again in order to restart LWP process support.
* \par Error Codes
* ---Always succeeds, or performs an abort().
*
* \subsubsection sec2-3-1-3 Section 2.3.1.3: LWP_CreateProcess _ Create a
* new thread
*
* \par
* int LWP_CreateProcess(IN int (*ep)(); IN int stacksize; IN int priority; IN
* char *parm; IN char *name; OUT PROCESS *pid)
* \par Description
* This function is used to create a new lightweight process with a given
* printable name. The ep argument identifies the function to be used as the
* body of the thread. The argument to be passed to this function is contained
* in parm. The new thread's stack size in bytes is specified in stacksize, and
* its execution priority in priority. The pid parameter is used to return the
* process ID of the new thread.
* \par
* If the thread is successfully created, it will be marked as runnable. The
* scheduler is called before the LWP CreateProcess() call completes, so the
* new thread may indeed begin its execution before the completion. Note that
* the new thread is guaranteed NOT to run before the call completes if the
* specified priority is lower than the caller's. On the other hand, if the new
* thread's priority is higher than the caller's, then it is guaranteed to run
* before the creation call completes.
* \par Error Codes
* LWP EBADPRI The given priority is invalid, either negative or too large.
* \n LWP NOMEM Could not allocate memory to satisfy the creation request.
*
* \subsubsection sec2-3-1-4 Section: 2.3.1.4: LWP_DestroyProcess _ Create
* a new thread
*
* \par
* int LWP_DestroyProcess(IN PROCESS pid)
* \par Description
* This routine destroys the thread identified by pid. It will be terminated
* immediately, and its internal storage will be reclaimed. A thread is allowed
* to destroy itself. In this case, of course, it will only get to see the
* return code if the operation fails. Note that a thread may also destroy
* itself by returning from the parent C routine.
* \par
* The scheduler is called by this operation, which may cause an arbitrary
* number of threads to execute before the caller regains the processor.
* \par Error Codes
* LWP EINIT The LWP package has not been initialized.
*
* \subsubsection sec2-3-1-5 Section 2.3.1.5: WaitProcess _ Wait on an
* event
*
* \par
* int LWP WaitProcess(IN char *event)
* \par Description
* This routine puts the thread making the call to sleep until another LWP
* calls the LWP SignalProcess() or LWP NoYieldSignal() routine with the
* specified event. Note that signalled events are not queued. If a signal
* occurs and no thread is awakened, the signal is lost. The scheduler is
* invoked by the LWP WaitProcess() routine.
* \par Error Codes
* LWP EINIT The LWP package has not been initialized.
* \n LWP EBADEVENT The given event pointer is null.
*
* \subsubsection sec2-3-1-6 Section 2.3.1.6: MwaitProcess _ Wait on a set
* of events
*
* \par
* int LWP MwaitProcess(IN int wcount; IN char *evlist[])
* \par Description
* This function allows a thread to wait for wcount signals on any of the items
* in the given evlist. Any number of signals of a particular event are only
* counted once. The evlist is a null-terminated list of events to wait for.
* The scheduler will be invoked.
* \par Error Codes
* LWP EINIT The LWP package has not been initialized.
* \n LWP EBADCOUNT An illegal number of events has been supplied.
*
* \subsubsection sec2-3-1-7 Section 2.3.1.7: SignalProcess _ Signal an
* event
*
* \par
* int LWP SignalProcess(IN char *event)
* \par Description
* This routine causes the given event to be signalled. All threads waiting for
* this event (exclusively) will be marked as runnable, and the scheduler will
* be invoked. Note that threads waiting on multiple events via LWP
* MwaitProcess() may not be marked as runnable. Signals are not queued.
* Therefore, if no thread is waiting for the signalled event, the signal will
* be lost.
* \par Error Codes
* LWP EINIT The LWP package has not been initialized. LWP EBADEVENT A null
* event pointer has been provided. LWP ENOWAIT No thread was waiting on the
* given event.
*
* \subsubsection sec2-3-1-8 Section 2.3.1.8: NoYieldSignal _ Signal an
* event without invoking scheduler
*
* \par
* int LWP NoYieldSignal(IN char *event)
* \par Description
* This function is identical to LWP SignalProcess() except that the scheduler
* will not be invoked. Thus, control will remain with the signalling process.
* \par Error Codes
* LWP EINIT The LWP package has not been initialized. LWP EBADEVENT A null
* event pointer has been provided. LWP ENOWAIT No thread was waiting on the
* given event.
*
* \subsubsection sec2-3-1-9 Section 2.3.1.9: DispatchProcess _ Yield
* control to the scheduler
*
* \par
* int LWP DispatchProcess()
* \par Description
* This routine causes the calling thread to yield voluntarily to the LWP
* scheduler. If no other thread of appropriate priority is marked as runnable,
* the caller will continue its execution.
* \par Error Codes
* LWP EINIT The LWP package has not been initialized.
*
* \subsubsection sec2-3-1-10 Section 2.3.1.10: CurrentProcess _ Get the
* current thread's ID
*
* \par
* int LWP CurrentProcess(IN PROCESS *pid)
* \par Description
* This call places the current lightweight process ID in the pid parameter.
* \par Error Codes
* LWP EINIT The LWP package has not been initialized.
*
* \subsubsection sec2-3-1-11 Section 2.3.1.11: ActiveProcess _ Get the
* current thread's ID (macro)
*
* \par
* int LWP ActiveProcess()
* \par Description
* This macro's value is the current lightweight process ID. It generates a
* value identical to that acquired by calling the LWP CurrentProcess()
* function described above if the LWP package has been initialized. If no such
* initialization has been done, it will return a value of zero.
*
* \subsubsection sec2-3-1-12 Section: 2.3.1.12: StackUsed _ Calculate
* stack usage
*
* \par
* int LWP StackUsed(IN PROCESS pid; OUT int *max; OUT int *used)
* \par Description
* This function returns the amount of stack space allocated to the thread
* whose identifier is pid, and the amount actually used so far. This is
* possible if the global variable lwp stackUseEnabled was TRUE when the thread
* was created (it is set this way by default). If so, the thread's stack area
* was initialized with a special pattern. The memory still stamped with this
* pattern can be determined, and thus the amount of stack used can be
* calculated. The max parameter is always set to the thread's stack allocation
* value, and used is set to the computed stack usage if lwp stackUseEnabled
* was set when the process was created, or else zero.
* \par Error Codes
* LWP NO STACK Stack usage was not enabled at thread creation time.
*
* \subsubsection sec2-3-1-13 Section 2.3.1.13: NewRock _ Establish
* thread-specific storage
*
* \par
* int LWP NewRock (IN int tag; IN char **value)
* \par Description
* This function establishes a "rock", or thread-specific information,
* associating it with the calling LWP. The tag is intended to be any unique
* integer value, and the value is a pointer to a character array containing
* the given data.
* \par
* Users of the LWP package must coordinate their choice of tag values. Note
* that a tag's value cannot be changed. Thus, to obtain a mutable data
* structure, another level of indirection is required. Up to MAXROCKS (4)
* rocks may be associated with any given thread.
* \par Error Codes
* ENOROCKS A rock with the given tag field already exists. All of the MAXROCKS
* are in use.
*
*
* \subsubsection sec2-3-1-14 Section: 2.3.1.14: GetRock _ Retrieve
* thread-specific storage
*
* \par
* int LWP GetRock(IN int tag; OUT **value)
* \par Description
* This routine recovers the thread-specific information associated with the
* calling process and the given tag, if any. Such a rock had to be established
* through a LWP NewRock() call. The rock's value is deposited into value.
* \par Error Codes
* LWP EBADROCK A rock has not been associated with the given tag for this
* thread.
*
* \subsection sec2-3-2 Section 2.3.2: Locking
*
* \par
* This section covers the calling interfaces to the locking package. Many of
* the user-callable routines are actually implemented as macros.
*
* \subsubsection sec2-3-2-1 Section 2.3.2.1: Lock Init _ Initialize lock
* structure
*
* \par
* void Lock Init(IN struct Lock *lock)
* \par Description
* This function must be called on the given lock object before any other
* operations can be performed on it.
* \par Error Codes
* ---No value is returned.
*
* \subsubsection sec2-3-2-2 Section 2.3.2.2: ObtainReadLock _ Acquire a
* read lock
*
* \par
* void ObtainReadLock(IN struct Lock *lock)
* \par Description
* This macro obtains a read lock on the specified lock object. Since this is a
* macro and not a function call, results are not predictable if the value of
* the lock parameter is a side-effect producing expression, as it will be
* evaluated multiple times in the course of the macro interpretation.
* Read locks are incompatible with write, shared, and boosted shared locks.
* \par Error Codes
* ---No value is returned.
*
* \subsubsection sec2-3-2-3 Section 2.3.2.3: ObtainWriteLock _ Acquire a
* write lock
*
* \par
* void ObtainWriteLock(IN struct Lock *lock)
* \par Description
* This macro obtains a write lock on the specified lock object. Since this is
* a macro and not a function call, results are not predictable if the value of
* the lock parameter is a side-effect producing expression, as it will be
* evaluated multiple times in the course of the macro interpretation.
* \par
* Write locks are incompatible with all other locks.
* \par Error Codes
* ---No value is returned.
*
* \subsubsection sec2-3-2-4 Section 2.3.2.4: ObtainSharedLock _ Acquire a
* shared lock
*
* \par
* void ObtainSharedLock(IN struct Lock *lock)
* \par Description
* This macro obtains a shared lock on the specified lock object. Since this is
* a macro and not a function call, results are not predictable if the value of
* the lock parameter is a side-effect producing expression, as it will be
* evaluated multiple times in the course of the macro interpretation.
* \par
* Shared locks are incompatible with write and boosted shared locks, but are
* compatible with read locks.
* \par Error Codes
* ---No value is returned.
*
* \subsubsection sec2-3-2-5 Section 2.3.2.5: ReleaseReadLock _ Release
* read lock
*
* \par
* void ReleaseReadLock(IN struct Lock *lock)
* \par Description
* This macro releases the specified lock. The lock must have been previously
* read-locked. Since this is a macro and not a function call, results are not
* predictable if the value of the lock parameter is a side-effect producing
* expression, as it will be evaluated multiple times in the course of the
* macro interpretation. The results are also unpredictable if the lock was not
* previously read-locked by the thread calling ReleaseReadLock().
* \par Error Codes
* ---No value is returned.
*
* \subsubsection sec2-3-2-6 Section 2.3.2.6: ReleaseWriteLock _ Release
* write lock
*
* \par
* void ReleaseWriteLock(IN struct Lock *lock)
* \par Description
* This macro releases the specified lock. The lock must have been previously
* write-locked. Since this is a macro and not a function call, results are not
* predictable if the value of the lock parameter is a side-effect producing
* expression, as it will be evaluated multiple times in the course of the
* macro interpretation. The results are also unpredictable if the lock was not
* previously write-locked by the thread calling ReleaseWriteLock().
* \par Error Codes
* ---No value is returned.
*
* \subsubsection sec2-3-2-7 Section 2.3.2.7: ReleaseSharedLock _ Release
* shared lock
*
* \par
* void ReleaseSharedLock(IN struct Lock *lock)
* \par Description
* This macro releases the specified lock. The lock must have been previously
* share-locked. Since this is a macro and not a function call, results are not
* predictalbe if the value of the lock parameter is a side-effect producing
* expression, as it will be evaluated multiple times in the course of the
* macro interpretation. The results are also unpredictable if the lock was not
* previously share-locked by the thread calling ReleaseSharedLock().
* \par Error Codes
* ---No value is returned.
*
* \subsubsection sec2-3-2-8 Section 2.3.2.8: CheckLock _ Determine state
* of a lock
*
* \par
* void CheckLock(IN struct Lock *lock)
* \par Description
* This macro produces an integer that specifies the status of the indicated
* lock. The value will be -1 if the lock is write-locked, 0 if unlocked, or
* otherwise a positive integer that indicates the number of readers (threads
* holding read locks). Since this is a macro and not a function call, results
* are not predictable if the value of the lock parameter is a side-effect
* producing expression, as it will be evaluated multiple times in the course
* of the macro interpretation.
* \par Error Codes
* ---No value is returned.
*
* \subsubsection sec2-3-2-9 Section 2.3.2.9: BoostLock _ Boost a shared
* lock
*
* \par
* void BoostLock(IN struct Lock *lock)
* \par Description
* This macro promotes ("boosts") a shared lock into a write lock. Such a boost
* operation guarantees that no other writer can get into the critical section
* in the process. Since this is a macro and not a function call, results are
* not predictable if the value of the lock parameter is a side-effect
* producing expression, as it will be evaluated multiple times in the course
* of the macro interpretation.
* \par Error Codes
* ---No value is returned.
*
* \subsubsection sec2-3-2-10 Section 2.3.2.10: UnboostLock _ Unboost a
* shared lock
*
* \par
* void UnboostLock(IN struct Lock *lock)
* \par Description
* This macro demotes a boosted shared lock back down into a regular shared
* lock. Such an unboost operation guarantees that no other writer can get into
* the critical section in the process. Since this is a macro and not a
* function call, results are not predictable if the value of the lock
* parameter is a side-effect producing expression, as it will be evaluated
* multiple times in the course of the macro interpretation.
* \par Error Codes
* ---No value is returned.
*
* \subsection sec2-3-3 Section 2.3.3: IOMGR
*
* \par
* This section covers the calling interfaces to the I/O management package.
*
* \subsubsection sec2-3-3-1 Section: 2.3.3.1: IOMGR Initialize _
* Initialize the package
*
* \par
* int IOMGR Initialize()
* \par Description
* This function initializes the IOMGR package. Its main task is to create the
* IOMGR thread itself, which runs at the lowest possible priority (0). The
* remainder of the lightweight processes must be running at priority 1 or
* greater (up to a maximum of LWP MAX PRIORITY (4)) for the IOMGR package to
* function correctly.
* \par Error Codes
* -1 The LWP and/or timer package haven't been initialized.
* \n <misc> Any errors that may be returned by the LWP CreateProcess()
* routine.
*
* \subsubsection sec2-3-3-2 Section 2.3.3.2: IOMGR finalize _ Clean up
* the IOMGR facility
*
* \par
* int IOMGR finalize()
* \par Description
* This routine cleans up after the IOMGR package when it is no longer needed.
* It releases all storage and destroys the IOMGR thread itself.
* \par Error Codes
* <misc> Any errors that may be returned by the LWP DestroyProcess() routine.
*
* \subsubsection sec2-3-3-3 Section 2.3.3.3: IOMGR Select _ Perform a
* thread-level select()
*
* \par
* int IOMGR Select (IN int numfds; IN int *rfds; IN int *wfds; IN int *xfds;
* IN truct timeval *timeout)
* \par Description
* This routine performs an LWP version of unix select() operation. The
* parameters have the same meanings as with the unix call. However, the return
* values will be simplified (see below). If this is a polling select (i.e.,
* the value of timeout is null), it is done and the IOMGR Select() function
* returns to the user with the results. Otherwise, the calling thread is put
* to sleep. If at some point the IOMGR thread is the only runnable process, it
* will awaken and collect all select requests. The IOMGR will then perform a
* single select and awaken the appropriate processes. This will force a return
* from the affected IOMGR Select() calls.
* \par Error Codes
* -1 An error occurred.
* \n 0 A timeout occurred.
* \n 1 Some number of file descriptors are ready.
*
* \subsubsection sec2-3-3-4 Section 2.3.3.4: IOMGR Signal _ Associate
* unix and LWP signals
*
* \par
* int IOMGR Signal(IN int signo; IN char *event)
* \par Description
* This function associates an LWP signal with a unix signal. After this call,
* when the given unix signal signo is delivered to the (heavyweight unix)
* process, the IOMGR thread will deliver an LWP signal to the event via LWP
* NoYieldSignal(). This wakes up any lightweight processes waiting on the
* event. Multiple deliveries of the signal may be coalesced into one LWP
* wakeup. The call to LWP NoYieldSignal() will happen synchronously. It is
* safe for an LWP to check for some condition and then go to sleep waiting for
* a unix signal without having to worry about delivery of the signal happening
* between the check and the call to LWP WaitProcess().
* \par Error Codes
* LWP EBADSIG The signo value is out of range.
* \n LWP EBADEVENT The event pointer is null.
*
* \subsubsection sec2-3-3-5 Section 2.3.3.5: IOMGR CancelSignal _ Cancel
* unix and LWP signal association
*
* \par
* int IOMGR CancelSignal(IN int signo)
* \par Description
* This routine cancels the association between a unix signal and an LWP event.
* After calling this function, the unix signal signo will be handled however
* it was handled before the corresponding call to IOMGR Signal().
* \par Error Codes
* LWP EBADSIG The signo value is out of range.
*
* \subsubsection sec2-3-3-6 Section 2.3.3.6: IOMGR Sleep _ Sleep for a
* given period
*
* \par
* void IOMGR Sleep(IN unsigned seconds)
* \par Description
* This function calls IOMGR Select() with zero file descriptors and a timeout
* structure set up to cause the thread to sleep for the given number of
* seconds.
* \par Error Codes
* ---No value is returned.
*
* \subsection sec2-3-4 Section 2.3.4: Timer
*
* \par
* This section covers the calling interface to the timer package associated
* with the LWP facility.
*
* \subsubsection sec2-3-4-1 Section 2.3.4.1: TM Init _ Initialize a timer
* list
*
* \par
* int TM Init(IN struct TM Elem **list)
* \par Description
* This function causes the specified timer list to be initialized. TM Init()
* must be called before any other timer operations are applied to the list.
* \par Error Codes
* -1 A null timer list could not be produced.
*
* \subsubsection sec2-3-4-2 Section 2.3.4.2: TM final _ Clean up a timer
* list
*
* \par
* int TM final(IN struct TM Elem **list)
* \par Description
* This routine is called when the given empty timer list is no longer needed.
* All storage associated with the list is released.
* \par Error Codes
* -1 The list parameter is invalid.
*
* \subsubsection sec2-3-4-3 Section 2.3.4.3: TM Insert _ Insert an object
* into a timer list
*
* \par
* void TM Insert(IN struct TM Elem **list; IN struct TM Elem *elem)
* \par Description
* This routine enters an new element, elem, into the list denoted by list.
* Before the new element is queued, its TimeLeft field (the amount of time
* before the object comes due) is set to the value stored in its TotalTime
* field. In order to keep TimeLeft fields current, the TM Rescan() function
* may be used.
* \par Error Codes
* ---No return value is generated.
*
* \subsubsection sec2-3-4-4 Section 2.3.4.4: TM Rescan _ Update all
* timers in the list
*
* \par
* int TM Rescan(IN struct TM Elem *list)
* \par Description
* This function updates the TimeLeft fields of all timers on the given list.
* This is done by checking the time-of-day clock. Note: this is the only
* routine other than TM Init() that updates the TimeLeft field in the elements
* on the list.
* \par
* Instead of returning a value indicating success or failure, TM Rescan()
* returns the number of entries that were discovered to have timed out.
* \par Error Codes
* ---Instead of error codes, the number of entries that were discovered to
* have timed out is returned.
*
* \subsubsection sec2-3-4-5 Section 2.3.4.5: TM GetExpired _ Returns an
* expired timer
*
* \par
* struct TM Elem *TM GetExpired(IN struct TM Elem *list)
* \par Description
* This routine searches the specified timer list and returns a pointer to an
* expired timer element from that list. An expired timer is one whose TimeLeft
* field is less than or equal to zero. If there are no expired timers, a null
* element pointer is returned.
* \par Error Codes
* ---Instead of error codes, an expired timer pointer is returned, or a null
* timer pointer if there are no expired timer objects.
*
* \subsubsection sec2-3-4-6 Section 2.3.4.6: TM GetEarliest _ Returns
* earliest unexpired timer
*
* \par
* struct TM Elem *TM GetEarliest(IN struct TM Elem *list)
* \par Description
* This function returns a pointer to the timer element that will be next to
* expire on the given list. This is defined to be the timer element with the
* smallest (positive) TimeLeft field. If there are no timers on the list, or
* if they are all expired, this function will return a null pointer.
* \par Error Codes
* ---Instead of error codes, a pointer to the next timer element to expireis
* returned, or a null timer object pointer if they are all expired.
*
* \subsubsection sec2-3-4-7 Section 2.3.4.7: TM eql _ Test for equality
* of two timestamps
*
* \par
* bool TM eql(IN struct timemval *t1; IN struct timemval *t2)
* \par Description
* This function compares the given timestamps, t1 and t2, for equality. Note
* that the function return value, bool, has been set via typedef to be
* equivalent to unsigned char.
* \par Error Codes
* 0 If the two timestamps differ.
* \n 1 If the two timestamps are identical.
*
* \subsection sec2-3-5 Section 2.3.5: Fast Time
* \par
* This section covers the calling interface to the fast time package
* associated with the LWP facility.
*
* \subsubsection sec2-3-5-1 Section 2.3.5.1: FT Init _ Initialize the
* fast time package
*
* \par
* int FT Init(IN int printErrors; IN int notReally)
* \par Description
* This routine initializes the fast time package, mapping in the kernel page
* containing the time-of-day variable. The printErrors argument, if non-zero,
* will cause any errors in initalization to be printed to stderr. The
* notReally parameter specifies whether initialization is really to be done.
* Other calls in this package will do auto-initialization, and hence the
* option is offered here.
* \par Error Codes
* -1 Indicates that future calls to FT GetTimeOfDay() will still work, but
* will not be able to access the information directly, having to make a
* kernel call every time.
*
* \subsubsection sec2-3-5-2 Section 2.3.5.2: FT GetTimeOfDay _ Initialize
* the fast time package
*
* \par
* int FT GetTimeOfDay(IN struct timeval *tv; IN struct timezone *tz)
* \par Description
* This routine is meant to mimic the parameters and behavior of the unix
* gettimeofday() function. However, as implemented, it simply calls
* gettimeofday() and then does some bound-checking to make sure the value is
* reasonable.
* \par Error Codes
* <misc> Whatever value was returned by gettimeofday() internally.
*
* \subsection sec2-3-6 Section 2.3.6: Preemption
* \par
* This section covers the calling interface to the preemption package
* associated with the LWP facility.
*
* \subsubsection sec2-3-6-1 Section 2.3.6.1: PRE InitPreempt _ Initialize
* the preemption package
*
* \par
* int PRE InitPreempt(IN struct timeval *slice)
* \par Description
* This function must be called to initialize the preemption package. It must
* appear sometime after the call to LWP InitializeProcessSupport() and
* sometime before the first call to any other preemption routine. The slice
* argument specifies the time slice size to use. If the slice pointer is set
* to null in the call, then the default time slice, DEFAULTSLICE (10
* milliseconds), will be used. This routine uses the unix interval timer and
* handling of the unix alarm signal, SIGALRM, to implement this timeslicing.
* \par Error Codes
* LWP EINIT The LWP package hasn't been initialized.
* \n LWP ESYSTEM Operations on the signal vector or the interval timer have
* failed.
*
* \subsubsection sec2-3-6-2 Section 2.3.6.2: PRE EndPreempt _ finalize
* the preemption package
*
* \par
* int PRE EndPreempt()
* \par Description
* This routine finalizes use of the preemption package. No further preemptions
* will be made. Note that it is not necessary to make this call before exit.
* PRE EndPreempt() is provided only for those applications that wish to
* continue after turning off preemption.
* \par Error Codes
* LWP EINIT The LWP package hasn't been initialized.
* \n LWP ESYSTEM Operations on the signal vector or the interval timer have
* failed.
*
* \subsubsection sec2-3-6-3 Section 2.3.6.3: PRE PreemptMe _ Mark thread
* as preemptible
*
* \par
* int PRE PreemptMe()
* \par Description
* This macro is used to signify the current thread as a candidate for
* preemption. The LWP InitializeProcessSupport() routine must have been called
* before PRE PreemptMe().
* \par Error Codes
* ---No return code is generated.
*
* \subsubsection sec2-3-6-4 Section 2.3.6.4: PRE BeginCritical _ Enter
* thread critical section
*
* \par
* int PRE BeginCritical()
* \par Description
* This macro places the current thread in a critical section. Upon return, and
* for as long as the thread is in the critical section, involuntary
* preemptions of this LWP will no longer occur.
* \par Error Codes
* ---No return code is generated.
*
* \subsubsection sec2-3-6-5 Section 2.3.6.5: PRE EndCritical _ Exit
* thread critical section
*
* \par
* int PRE EndCritical()
* \par Description
* This macro causes the executing thread to leave a critical section
* previously entered via PRE BeginCritical(). If involuntary preemptions were
* possible before the matching PRE BeginCritical(), they are once again
* possible.
* \par Error Codes
* ---No return code is generated.
*
* \page chap3 Chapter 3 -- Rxkad
*
*
* \section sec3-1 Section 3.1: Introduction
*
* \par
* The rxkad security module is offered as one of the built-in Rx
* authentication models. It is based on the Kerberos system developed by MIT's
* Project Athena. Readers wishing detailed information regarding Kerberos
* design and implementation are directed to [2]. This chapter is devoted to
* defining how Kerberos authentication services are made available as Rx
* components, and assumes the reader has some familiarity with Kerberos.
* Included are descriptions of how client-side and server-side Rx security
* objects (struct rx securityClass; see Section 5.3.1.1) implementing this
* protocol may be generated by an Rx application. Also, a description appears
* of the set of routines available in the associated struct rx securityOps
* structures, as covered in Section 5.3.1.2. It is strongly recommended that
* the reader become familiar with this section on struct rx securityOps before
* reading on.
*
* \section sec3-2 Section 3.2: Definitions
*
* \par
* An important set of definitions related to the rxkad security package is
* provided by the rxkad.h include file. Determined here are various values for
* ticket lifetimes, along with structures for encryption keys and Kerberos
* principals. Declarations for the two routines required to generate the
* different rxkad security objects also appear here. The two functions are
* named rxkad NewServerSecurityObject() and rxkad NewClientSecurityObject().
* In addition, type field values, encryption levels, security index
* operations, and statistics structures may be found in this file.
* \section sec3-3 Section 3.3: Exported Objects
* \par
* To be usable as an Rx security module, the rxkad facility exports routines
* to create server-side and client-side security objects. The server
* authentication object is incorporated into the server code when calling rx
* NewService(). The client authentication object is incorporated into the
* client code every time a connection is established via rx NewConnection().
* Also, in order to implement these security objects, the rxkad module must
* provide definitions for some subset of the generic security operations as
* defined in the appropriate struct rx securityOps variable.
*
* \subsection sec3-3-1 Section 3.3.1: Server-Side Mechanisms
*
* \subsubsection sec3-3-1-1 Section 3.3.1.1: Security Operations
*
* \par
* The server side of the rxkad module fills in all but two of the possible
* routines associated with an Rx security object, as described in Section
* 5.3.1.2.
*
* \code
* static struct rx_securityOps rxkad_server_ops = {
* rxkad_Close,
* rxkad_NewConnection,
* rxkad_PreparePacket, /* Once per packet creation */
* 0, /* Send packet (once per retrans) */
* rxkad_CheckAuthentication,
* rxkad_CreateChallenge,
* rxkad_GetChallenge,
* 0,
* rxkad_CheckResponse, /* Check data packet */
* rxkad_DestroyConnection,
* rxkad_GetStats,
* };
* \endcode
*
* \par
* The rxkad service does not need to take any special action each time a
* packet belonging to a call in an rxkad Rx connection is physically
* transmitted. Thus, a routine is not supplied for the op SendPacket()
* function slot. Similarly, no preparatory work needs to be done previous to
* the reception of a response packet from a security challenge, so the op
* GetResponse() function slot is also empty.
*
* \subsubsection sec3-3-1-2 Section 3.3.1.2: Security Object
*
* \par
* The exported routine used to generate an rxkad-specific server-side security
* class object is named rxdad NewServerSecurityObject(). It is declared with
* four parameters, as follows:
*
* \code
* struct rx_securityClass *
* rxkad_NewServerSecurityObject(a_level, a_getKeyRockP, a_getKeyP, a_userOKP)
* rxkad_level a_level; /* Minimum level */
* char *a_getKeyRockP; /* Rock for get_key implementor */
* int (*a_getKeyP)(); /* Passed kvno & addr(key) to fill */
* int (*a_userOKP)(); /* Passed name, inst, cell => bool */
* \endcode
*
* \par
* The first argument specifies the desired level of encryption, and may take
* on the following values (as defined in rxkad.h):
* \li rxkad clear: Specifies that packets are to be sent entirely in the
* clear, without any encryption whatsoever.
* \li rxkad auth: Specifies that packet sequence numbers are to be encrypted.
* \li rxkad crypt: Specifies that the entire data packet is to be encrypted.
*
* \par
* The second and third parameters represent, respectively, a pointer to a
* private data area, sometimes called a "rock", and a procedure reference that
* is called with the key version number accompanying the Kerberos ticket and
* returns a pointer to the server's decryption key. The fourth argument, if
* not null, is a pointer to a function that will be called for every new
* connection with the client's name, instance, and cell. This routine should
* return zero if the user is not acceptable to the server.
*
* \subsection sec3-3-2 Section 3.3.2: Client-Side Mechanisms
*
* \subsubsection sec3-3-2-1 Section 3.3.2.1: Security Operations
*
* \par
* The client side of the rxkad module fills in relatively few of the routines
* associated with an Rx security object, as demonstrated below. The general Rx
* security object, of which this is an instance, is described in detail in
* Section 5.3.1.2.
*
* \code
* static struct rx_securityOps rxkad_client_ops = {
* rxkad_Close,
* rxkad_NewConnection, /* Every new connection */
* rxkad_PreparePacket, /* Once per packet creation */
* 0, /* Send packet (once per retrans) */
* 0,
* 0,
* 0,
* rxkad_GetResponse, /* Respond to challenge packet */
* 0,
* rxkad_CheckPacket, /* Check data packet */
* rxkad_DestroyConnection,
* rxkad_GetStats,
* 0,
* 0,
* 0,
* };
* \endcode
*
* \par
* As expected, routines are defined for use when someone destroys a security
* object (rxkad Close()) and when an Rx connection using the rxkad model
* creates a new connection (rxkad NewConnection()) or deletes an existing one
* (rxkad DestroyConnection()). Security-specific operations must also be
* performed in behalf of rxkad when packets are created (rxkad
* PreparePacket()) and received (rxkad CheckPacket()). finally, the client
* side of an rxkad security object must also be capable of constructing
* responses to security challenges from the server (rxkad GetResponse()) and
* be willing to reveal statistics on its own operation (rxkad GetStats()).
*
* \subsubsection sec3-3-2-2 Section 3.3.2.2: Security Object
*
* \par
* The exported routine used to generate an rxkad-specific client-side security
* class object is named rxkad NewClientSecurityObject(). It is declared with
* five parameters, specified below:
*
* \code
* struct rx_securityClass * rxkad_NewClientSecurityObject(
* a_level,
* a_sessionKeyP,
* a_kvno,
* a_ticketLen,
* a_ticketP
* )
* rxkad_level a_level;
* struct ktc_encryptionKey *a_sessionKeyP;
* long a_kvno;
* int a_ticketLen;
* char *a_ticketP;
* \endcode
*
* \par
* The first parameter, a level, specifies the level of encryption desired for
* this security object, with legal choices being identical to those defined
* for the server-side security object described in Section 3.3.1.2. The second
* parameter, a sessionKeyP, provides the session key to use. The ktc
* encryptionKey structure is defined in the rxkad.h include file, and consists
* of an array of 8 characters. The third parameter, a kvno, provides the key
* version number associated with a sessionKeyP. The fourth argument, a
* ticketLen, communicates the length in bytes of the data stored in the fifth
* parameter, a ticketP, which points to the Kerberos ticket to use for the
* principal for which the security object will operate.
*
* \page chap4 Chapter 4 -- Rx Support Packages
*
* \section sec4-1 Section 4.1: Introduction
* \par
* This chapter documents three packages defined directly in support of the Rx
* facility.
* \li rx queue: Doubly-linked queue package.
* \li rx clock: Clock package, using the 4.3BSD interval timer.
* \li rx event: Future events package.
* \par
* References to constants, structures, and functions defined by these support
* packages will appear in the following API chapter.
*
* \section sec4-2 Section 4.2: The rx queue Package
*
* \par
* This package provides a doubly-linked queue structure, along with a full
* suite of related operations. The main concern behind the coding of this
* facility was efficiency. All functions are implemented as macros, and it is
* suggested that only simple expressions be used for all parameters.
* \par
* The rx queue facility is defined by the rx queue.h include file. Some macros
* visible in this file are intended for rx queue internal use only. An
* understanding of these "hidden" macros is important, so they will also be
* described by this document.
*
* \subsection sec4-2-1 Section 4.2.1: struct queue
*
* \par
* The queue structure provides the linkage information required to maintain a
* queue of objects. The queue structure is prepended to any user-defined data
* type which is to be organized in this fashion.
* \n \b fields
* \li struct queue *prev - Pointer to the previous queue header.
* \li struct queue *next - Pointer to the next queue header.
* \par
* Note that a null Rx queue consists of a single struct queue object whose
* next and previous pointers refer to itself.
*
* \subsection sec4-2-2 Section 4.2.2: Internal Operations
*
* \par
* This section describes the internal operations defined for Rx queues. They
* will be referenced by the external operations documented in Section 4.2.3.
*
* \subsection sec4-2-2-1 Section 4.2.2.1: Q(): Coerce type to a queue
* element
*
* \par
* \#define _Q(x) ((struct queue *)(x))
* \par
* This operation coerces the user structure named by x to a queue element. Any
* user structure using the rx queue package must have a struct queue as its
* first field.
*
* \subsubsection sec4-2-2-2 Section 4.2.2.2: QA(): Add a queue element
* before/after another element
*
* \par
* \#define _QA(q,i,a,b) (((i->a=q->a)->b=i)->b=q, q->a=i)
* \par
* This operation adds the queue element referenced by i either before or after
* a queue element represented by q. If the (a, b) argument pair corresponds to
* an element's (next, prev) fields, the new element at i will be linked after
* q. If the (a, b) argument pair corresponds to an element's (prev, next)
* fields, the new element at i will be linked before q.
*
* \subsubsection sec4-2-2-3 QR(): Remove a queue element
*
* \par
* \#define _QR(i) ((_Q(i)->prev->next=_Q(i)->next)->prev=_Q(i)->prev)
* \par
* This operation removes the queue element referenced by i from its queue. The
* prev and next fields within queue element i itself is not updated to reflect
* the fact that it is no longer part of the queue.
*
* \subsubsection sec4-2-2-4 QS(): Splice two queues together
*
* \par
* \#define _QS(q1,q2,a,b) if (queue_IsEmpty(q2)); else
* ((((q2->a->b=q1)->a->b=q2->b)->a=q1->a, q1->a=q2->a), queue_Init(q2))
* \par
* This operation takes the queues identified by q1 and q2 and splices them
* together into a single queue. The order in which the two queues are appended
* is determined by the a and b arguments. If the (a, b) argument pair
* corresponds to q1's (next, prev) fields, then q2 is appended to q1. If the
* (a, b) argument pair corresponds to q1's (prev, next) fields, then q is
* prepended to q2.
* \par
* This internal QS() routine uses two exported queue operations, namely queue
* Init() and queue IsEmpty(), defined in Sections 4.2.3.1 and 4.2.3.16
* respectively below.
*
* \subsection sec4-2-3 Section 4.2.3: External Operations
*
* \subsubsection sec4-2-3-1 Section 4.2.3.1: queue Init(): Initialize a
* queue header
*
* \par
* \#define queue_Init(q) (_Q(q))->prev = (_Q(q))->next = (_Q(q))
* \par
* The queue header referred to by the q argument is initialized so that it
* describes a null (empty) queue. A queue head is simply a queue element.
*
* \subsubsection sec4-2-3-2 Section 4.2.3.2: queue Prepend(): Put element
* at the head of a queue
*
* \par
* \#define queue_Prepend(q,i) _QA(_Q(q),_Q(i),next,prev)
* \par
* Place queue element i at the head of the queue denoted by q. The new queue
* element, i, should not currently be on any queue.
*
* \subsubsection sec4-2-3-3 Section 4.2.3.3: queue Append(): Put an
* element a the tail of a queue
*
* \par
* \#define queue_Append(q,i) _QA(_Q(q),_Q(i),prev,next)
* \par
* Place queue element i at the tail of the queue denoted by q. The new queue
* element, i, should not currently be on any queue.
*
* \subsection sec4-2-3-4 Section 4.2.3.4: queue InsertBefore(): Insert a
* queue element before another element
*
* \par
* \#define queue_InsertBefore(i1,i2) _QA(_Q(i1),_Q(i2),prev,next)
* \par
* Insert queue element i2 before element i1 in i1's queue. The new queue
* element, i2, should not currently be on any queue.
*
* \subsubsection sec4-2-3-5 Section 4.2.3.5: queue InsertAfter(): Insert
* a queue element after another element
*
* \par
* \#define queue_InsertAfter(i1,i2) _QA(_Q(i1),_Q(i2),next,prev)
* \par
* Insert queue element i2 after element i1 in i1's queue. The new queue
* element, i2, should not currently be on any queue.
*
* \subsubsection sec4-2-3-6 Section: 4.2.3.6: queue SplicePrepend():
* Splice one queue before another
*
* \par
* \#define queue_SplicePrepend(q1,q2) _QS(_Q(q1),_Q(q2),next,prev)
* \par
* Splice the members of the queue located at q2 to the beginning of the queue
* located at q1, reinitializing queue q2.
*
* \subsubsection sec4-2-3-7 Section 4.2.3.7: queue SpliceAppend(): Splice
* one queue after another
*
* \par
* \#define queue_SpliceAppend(q1,q2) _QS(_Q(q1),_Q(q2),prev,next)
* \par
* Splice the members of the queue located at q2 to the end of the queue
* located at q1, reinitializing queue q2. Note that the implementation of
* queue SpliceAppend() is identical to that of queue SplicePrepend() except
* for the order of the next and prev arguments to the internal queue splicer,
* QS().
*
* \subsubsection sec4-2-3-8 Section 4.2.3.8: queue Replace(): Replace the
* contents of a queue with that of another
*
* \par
* \#define queue_Replace(q1,q2) (*_Q(q1) = *_Q(q2),
* \n _Q(q1)->next->prev = _Q(q1)->prev->next = _Q(q1),
* \n queue_Init(q2))
* \par
* Replace the contents of the queue located at q1 with the contents of the
* queue located at q2. The prev and next fields from q2 are copied into the
* queue object referenced by q1, and the appropriate element pointers are
* reassigned. After the replacement has occurred, the queue header at q2 is
* reinitialized.
*
* \subsubsection sec4-2-3-9 Section 4.2.3.9: queue Remove(): Remove an
* element from its queue
*
* \par
* \#define queue_Remove(i) (_QR(i), _Q(i)->next = 0)
* \par
* This function removes the queue element located at i from its queue. The
* next field for the removed entry is zeroed. Note that multiple removals of
* the same queue item are not supported.
*
* \subsubsection sec4-2-3-10 Section 4.2.3.10: queue MoveAppend(): Move
* an element from its queue to the end of another queue
*
* \par
* \#define queue_MoveAppend(q,i) (_QR(i), queue_Append(q,i))
* \par
* This macro removes the queue element located at i from its current queue.
* Once removed, the element at i is appended to the end of the queue located
* at q.
*
* \subsubsection sec4-2-3-11 Section 4.2.3.11: queue MovePrepend(): Move
* an element from its queue to the head of another queue
*
* \par
* \#define queue_MovePrepend(q,i) (_QR(i), queue_Prepend(q,i))
* \par
* This macro removes the queue element located at i from its current queue.
* Once removed, the element at i is inserted at the head fo the queue located
* at q.
*
* \subsubsection sec4-2-3-12 Section 4.2.3.12: queue first(): Return the
* first element of a queue, coerced to a particular type
*
* \par
* \#define queue_first(q,s) ((struct s *)_Q(q)->next)
* \par
* Return a pointer to the first element of the queue located at q. The
* returned pointer value is coerced to conform to the given s structure. Note
* that a properly coerced pointer to the queue head is returned if q is empty.
*
* \subsubsection sec4-2-3-13 Section 4.2.3.13: queue Last(): Return the
* last element of a queue, coerced to a particular type
*
* \par
* \#define queue_Last(q,s) ((struct s *)_Q(q)->prev)
* \par
* Return a pointer to the last element of the queue located at q. The returned
* pointer value is coerced to conform to the given s structure. Note that a
* properly coerced pointer to the queue head is returned if q is empty.
*
* \subsubsection sec4-2-3-14 Section 4.2.3.14: queue Next(): Return the
* next element of a queue, coerced to a particular type
*
* \par
* \#define queue_Next(i,s) ((struct s *)_Q(i)->next)
* \par
* Return a pointer to the queue element occuring after the element located at
* i. The returned pointer value is coerced to conform to the given s
* structure. Note that a properly coerced pointer to the queue head is
* returned if item i is the last in its queue.
*
* \subsubsection sec4-2-3-15 Section 4.2.3.15: queue Prev(): Return the
* next element of a queue, coerced to a particular type
*
* \par
* \#define queue_Prev(i,s) ((struct s *)_Q(i)->prev)
* \par
* Return a pointer to the queue element occuring before the element located at
* i. The returned pointer value is coerced to conform to the given s
* structure. Note that a properly coerced pointer to the queue head is
* returned if item i is the first in its queue.
*
* \subsubsection sec4-2-3-16 Section 4.2.3.16: queue IsEmpty(): Is the
* given queue empty?
*
* \par
* \#define queue_IsEmpty(q) (_Q(q)->next == _Q(q))
* \par
* Return a non-zero value if the queue located at q does not have any elements
* in it. In this case, the queue consists solely of the queue header at q
* whose next and prev fields reference itself.
*
* \subsubsection sec4-2-3-17 Section 4.2.3.17: queue IsNotEmpty(): Is the
* given queue not empty?
*
* \par
* \#define queue_IsNotEmpty(q) (_Q(q)->next != _Q(q))
* \par
* Return a non-zero value if the queue located at q has at least one element
* in it other than the queue header itself.
*
* \subsubsection sec4-2-3-18 Section 4.2.3.18: queue IsOnQueue(): Is an
* element currently queued?
*
* \par
* \#define queue_IsOnQueue(i) (_Q(i)->next != 0)
* \par
* This macro returns a non-zero value if the queue item located at i is
* currently a member of a queue. This is determined by examining its next
* field. If it is non-null, the element is considered to be queued. Note that
* any element operated on by queue Remove() (Section 4.2.3.9) will have had
* its next field zeroed. Hence, it would cause a non-zero return from this
* call.
*
* \subsubsection sec4-2-3-19 Section 4.2.3.19: queue Isfirst(): Is an
* element the first on a queue?
*
* \par
* \#define queue_Isfirst(q,i) (_Q(q)->first == _Q(i))
* \par
* This macro returns a non-zero value if the queue item located at i is the
* first element in the queue denoted by q.
*
* \subsubsection sec4-2-3-20 Section 4.2.3.20: queue IsLast(): Is an
* element the last on a queue?
*
* \par
* \#define queue_IsLast(q,i) (_Q(q)->prev == _Q(i))
* \par
* This macro returns a non-zero value if the queue item located at i is the
* last element in the queue denoted by q.
*
* \subsubsection sec4-2-3-21 Section 4.2.3.21: queue IsEnd(): Is an
* element the end of a queue?
*
* \par
* \#define queue_IsEnd(q,i) (_Q(q) == _Q(i))
* \par
* This macro returns a non-zero value if the queue item located at i is the
* end of the queue located at q. Basically, it determines whether a queue
* element in question is also the queue header structure itself, and thus does
* not represent an actual queue element. This function is useful for
* terminating an iterative sweep through a queue, identifying when the search
* has wrapped to the queue header.
*
* \subsubsection sec4-2-3-22 Section 4.2.3.22: queue Scan(): for loop
* test for scanning a queue in a forward direction
*
* \par
* \#define queue_Scan(q, qe, next, s)
* \n (qe) = queue_first(q, s), next = queue_Next(qe, s);
* \n !queue_IsEnd(q, qe);
* \n (qe) = (next), next = queue_Next(qe, s)
* \par
* This macro may be used as the body of a for loop test intended to scan
* through each element in the queue located at q. The qe argument is used as
* the for loop variable. The next argument is used to store the next value for
* qe in the upcoming loop iteration. The s argument provides the name of the
* structure to which each queue element is to be coerced. Thus, the values
* provided for the qe and next arguments must be of type (struct s *).
* \par
* An example of how queue Scan() may be used appears in the code fragment
* below. It declares a structure named mystruct, which is suitable for
* queueing. This queueable structure is composed of the queue pointers
* themselves followed by an integer value. The actual queue header is kept in
* demoQueue, and the currItemP and nextItemP variables are used to step
* through the demoQueue. The queue Scan() macro is used in the for loop to
* generate references in currItemP to each queue element in turn for each
* iteration. The loop is used to increment every queued structure's myval
* field by one.
*
* \code
* struct mystruct {
* struct queue q;
* int myval;
* };
* struct queue demoQueue;
* struct mystruct *currItemP, *nextItemP;
* ...
* for (queue_Scan(&demoQueue, currItemP, nextItemP, mystruct)) {
* currItemP->myval++;
* }
* \endcode
*
* \par
* Note that extra initializers can be added before the body of the queue
* Scan() invocation above, and extra expressions can be added afterwards.
*
* \subsubsection sec4-2-3-23 Section 4.2.3.23: queue ScanBackwards(): for
* loop test for scanning a queue in a reverse direction
*
* \par
* #define queue_ScanBackwards(q, qe, prev, s)
* \n (qe) = queue_Last(q, s), prev = queue_Prev(qe, s);
* \n !queue_IsEnd(q, qe);
* \n (qe) = prev, prev = queue_Prev(qe, s)
* \par
* This macro is identical to the queue Scan() macro described above in Section
* 4.2.3.22 except for the fact that the given queue is scanned backwards,
* starting at the last item in the queue.
*
* \section sec4-3 Section 4.3: The rx clock Package
*
* \par
* This package maintains a clock which is independent of the time of day. It
* uses the unix 4.3BSD interval timer (e.g., getitimer(), setitimer()) in
* TIMER REAL mode. Its definition and interface may be found in the rx clock.h
* include file.
*
* \subsection sec4-3-1 Section 4.3.1: struct clock
*
* \par
* This structure is used to represent a clock value as understood by this
* package. It consists of two fields, storing the number of seconds and
* microseconds that have elapsed since the associated clock Init() routine has
* been called.
* \par
* \b fields
* \n long sec -Seconds since call to clock Init().
* \n long usec -Microseconds since call to clock Init().
*
* \subsection sec4-3-2 Section 4.3.12: clock nUpdates
*
* \par
* The integer-valued clock nUpdates is a variable exported by the rx clock
* facility. It records the number of times the clock value is actually
* updated. It is bumped each time the clock UpdateTime() routine is called, as
* described in Section 4.3.3.2.
*
* \subsection sec4-3-3 Section 4.3.3: Operations
*
* \subsubsection sec4-3-3-1 Section 4.3.3.1: clock Init(): Initialize the
* clock package
*
* \par
* This routine uses the unix setitimer() call to initialize the unix interval
* timer. If the setitimer() call fails, an error message will appear on
* stderr, and an exit(1) will be executed.
*
* \subsubsection sec4-3-3-2 Section 4.3.3.2: clock UpdateTime(): Compute
* the current time
*
* \par
* The clock UpdateTime() function calls the unix getitimer() routine in order
* to update the current time. The exported clock nUpdates variable is
* incremented each time the clock UpdateTime() routine is called.
*
* \subsubsection sec4-3-3-3 Section 4.3.3.3: clock GetTime(): Return the
* current clock time
*
* \par
* This macro updates the current time if necessary, and returns the current
* time into the cv argument, which is declared to be of type (struct clock *).
* 4.3.3.4 clock Sec(): Get the current clock time, truncated to seconds
* This macro returns the long value of the sec field of the current time. The
* recorded time is updated if necessary before the above value is returned.
*
* \subsubsection sec4-3-3-5 Section 4.3.3.5: clock ElapsedTime(): Measure
* milliseconds between two given clock values
*
* \par
* This macro returns the elapsed time in milliseconds between the two clock
* structure pointers provided as arguments, cv1 and cv2.
*
* \subsubsection sec4-3-3-6 Section 4.3.3.6: clock Advance(): Advance the
* recorded clock time by a specified clock value
*
* \par
* This macro takes a single (struct clock *) pointer argument, cv, and adds
* this clock value to the internal clock value maintined by the package.
*
* \subsubsection sec4-3-3-7 Section 4.3.3.7: clock Gt(): Is a clock value
* greater than another?
*
* \par
* This macro takes two parameters of type (struct clock *), a and b. It
* returns a nonzero value if the a parameter points to a clock value which is
* later than the one pointed to by b.
*
* \subsubsection sec4-3-3-8 Section 4.3.3.8: clock Ge(): Is a clock value
* greater than or equal to another?
*
* \par
* This macro takes two parameters of type (struct clock *), a and b. It
* returns a nonzero value if the a parameter points to a clock value which is
* greater than or equal to the one pointed to by b.
*
* \subsubsection sec4-3-3-9 Section 4.3.3.9: clock Gt(): Are two clock
* values equal?
*
* \par
* This macro takes two parameters of type (struct clock *), a and b. It
* returns a non-zero value if the clock values pointed to by a and b are
* equal.
*
* \subsubsection sec4.3.3.10 Section 4.3.3.10: clock Le(): Is a clock
* value less than or equal to another?
*
* \par
* This macro takes two parameters of type (struct clock *), a and b. It
* returns a nonzero value if the a parameter points to a clock value which is
* less than or equal to the one pointed to by b.
*
* \subsubsection sec4-3-3-11 Section 4.3.3.11: clock Lt(): Is a clock
* value less than another?
*
* \par
* This macro takes two parameters of type (struct clock *), a and b. It
* returns a nonzero value if the a parameter points to a clock value which is
* less than the one pointed to by b.
*
* \subsubsection sec4-3-3-12 Section 4.3.3.12: clock IsZero(): Is a clock
* value zero?
*
* \par
* This macro takes a single parameter of type (struct clock *), c. It returns
* a non-zero value if the c parameter points to a clock value which is equal
* to zero.
*
* \subsubsection sec4-3-3-13 Section 4.3.3.13: clock Zero(): Set a clock
* value to zero
*
* \par
* This macro takes a single parameter of type (struct clock *), c. It sets the
* given clock value to zero.
* \subsubsection sec4-3-3-14 Section 4.3.3.14: clock Add(): Add two clock
* values together
* \par
* This macro takes two parameters of type (struct clock *), c1 and c2. It adds
* the value of the time in c2 to c1. Both clock values must be positive.
*
* \subsubsection sec4-3-3-15 Section 4.3.3.15: clock Sub(): Subtract two
* clock values
*
* \par
* This macro takes two parameters of type (struct clock *), c1 and c2. It
* subtracts the value of the time in c2 from c1. The time pointed to by c2
* should be less than the time pointed to by c1.
*
* \subsubsection sec4-3-3-16 Section 4.3.3.16: clock Float(): Convert a
* clock time into floating point
*
* \par
* This macro takes a single parameter of type (struct clock *), c. It
* expresses the given clock value as a floating point number.
*
* \section sec4-4 Section 4.4: The rx event Package
*
* \par
* This package maintains an event facility. An event is defined to be
* something that happens at or after a specified clock time, unless cancelled
* prematurely. The clock times used are those provided by the rx clock
* facility described in Section 4.3 above. A user routine associated with an
* event is called with the appropriate arguments when that event occurs. There
* are some restrictions on user routines associated with such events. first,
* this user-supplied routine should not cause process preemption. Also, the
* event passed to the user routine is still resident on the event queue at the
* time of invocation. The user must not remove this event explicitly (via an
* event Cancel(), see below). Rather, the user routine may remove or schedule
* any other event at this time.
* \par
* The events recorded by this package are kept queued in order of expiration
* time, so that the first entry in the queue corresponds to the event which is
* the first to expire. This interface is defined by the rx event.h include
* file.
*
* \subsection sec4-4-1 Section 4.4.1: struct rxevent
*
* \par
* This structure defines the format of an Rx event record.
* \par
* \b fields
* \n struct queue junk -The queue to which this event belongs.
* \n struct clock eventTime -The clock time recording when this event comes
* due.
* \n int (*func)() -The user-supplied function to call upon expiration.
* \n char *arg -The first argument to the (*func)() function above.
* \n char *arg1 -The second argument to the (*func)() function above.
*
* \subsection sec4-4-2 Section 4.4.2: Operations
*
* \par
* This section covers the interface routines provided for the Rx event
* package.
*
* \subsubsection sec4-4-2-1 Section 4.4.2.1: rxevent Init(): Initialize
* the event package
*
* \par
* The rxevent Init() routine takes two arguments. The first, nEvents, is an
* integer-valued parameter which specifies the number of event structures to
* allocate at one time. This specifies the appropriate granularity of memory
* allocation by the event package. The second parameter, scheduler, is a
* pointer to an integer-valued function. This function is to be called when an
* event is posted (added to the set of events managed by the package) that is
* scheduled to expire before any other existing event.
* \par
* This routine sets up future event allocation block sizes, initializes the
* queues used to manage active and free event structures, and recalls that an
* initialization has occurred. Thus, this function may be safely called
* multiple times.
*
* \subsubsection sec4-4-2-2 Section 4.4.2.2: rxevent Post(): Schedule an
* event
*
* \par
* This function constructs a new event based on the information included in
* its parameters and then schedules it. The rxevent Post() routine takes four
* parameters. The first is named when, and is of type (struct clock *). It
* specifies the clock time at which the event is to occur. The second
* parameter is named func and is a pointer to the integer-valued function to
* associate with the event that will be created. When the event comes due,
* this function will be executed by the event package. The next two arguments
* to rxevent Post() are named arg and arg1, and are both of type (char *).
* They serve as the two arguments thath will be supplied to the func routine
* when the event comes due.
* \par
* If the given event is set to take place before any other event currently
* posted, the scheduler routine established when the rxevent Init() routine
* was called will be executed. This gives the application a chance to react to
* this new event in a reasonable way. One might expect that this scheduler
* routine will alter sleep times used by the application to make sure that it
* executes in time to handle the new event.
*
* \subsubsection sec4-4-2-3 Section 4.4.2.3: rxevent Cancel 1(): Cancel
* an event (internal use)
*
* \par
* This routine removes an event from the set managed by this package. It takes
* a single parameter named ev of type (struct rxevent *). The ev argument
* identifies the pending event to be cancelled.
* \par
* The rxevent Cancel 1() routine should never be called directly. Rather, it
* should be accessed through the rxevent Cancel() macro, described in Section
* 4.4.2.4 below.
*
* \subsubsection sec4-4-2-4 Section 4.4.2.4: rxevent Cancel(): Cancel an
* event (external use)
*
* \par
* This macro is the proper way to call the rxevent Cancel 1() routine
* described in Section 4.4.2.3 above. Like rxevent Cancel 1(), it takes a
* single argument. This event ptr argument is of type (struct rxevent *), and
* identi#es the pending event to be cancelled. This macro #rst checks to see
* if event ptr is null. If not, it calls rxevent Cancel 1() to perform the
* real work. The event ptr argument is zeroed after the cancellation operation
* completes.
*
* \subsubsection sec4-4-2-5 Section 4.4.2.4: rxevent RaiseEvents():
* Initialize the event package
*
* \par
* This function processes all events that have expired relative to the current
* clock time maintained by the event package. Each qualifying event is removed
* from the queue in order, and its user-supplied routine (func()) is executed
* with the associated arguments.
* \par
* The rxevent RaiseEvents() routine takes a single output parameter named
* next, defined to be of type (struct clock *). Upon completion of rxevent
* RaiseEvents(), the relative time to the next event due to expire is placed
* in next. This knowledge may be used to calculate the amount of sleep time
* before more event processing is needed. If there is no recorded event which
* is still pending at this point, rxevent RaiseEvents() returns a zeroed clock
* value into next.
*
* \subsubsection sec4-4-2-6 Section 4.4.2.6: rxevent TimeToNextEvent():
* Get amount of time until the next event expires
*
* \par
* This function returns the time between the current clock value as maintained
* by the event package and the the next event's expiration time. This
* information is placed in the single output argument,interval, defined to be
* of type (struct clock *). The rxevent TimeToNextEvent() function returns
* integer-valued quantities. If there are no scheduled events, a zero is
* returned. If there are one or more scheduled events, a 1 is returned. If
* zero is returned, the interval argument is not updated.
*
* \page chap5 Chapter 5 -- Programming Interface
*
* \section sec5-1 Section 5.1: Introduction
*
* \par
* This chapter documents the API for the Rx facility. Included are
* descriptions of all the constants, structures, exported variables, macros,
* and interface functions available to the application programmer. This
* interface is identical regardless of whether the application lives within
* the unix kernel or above it.
* \par
* This chapter actually provides more information than what may be strictly
* considered the Rx API. Many objects that were intended to be opaque and for
* Rx internal use only are also described here. The reason driving the
* inclusion of this "extra" information is that such exported Rx interface
* files as rx.h make these objects visible to application programmers. It is
* prefereable to describe these objects here than to ignore them and leave
* application programmers wondering as to their meaning.
* \par
* An example application illustrating the use of this interface, showcasing
* code from both server and client sides, appears in the following chapter.
*
* \section sec5-2 Section 5.2: Constants
*
* \par
* This section covers the basic constant definitions of interest to the Rx
* application programmer. Each subsection is devoted to describing the
* constants falling into the following categories:
* \li Configuration quantities
* \li Waiting options
* \li Connection ID operations
* \li Connection flags
* \li Connection types
* \li Call states
* \li Call flags
* \li Call modes
* \li Packet header flags
* \li Packet sizes
* \li Packet types
* \li Packet classes
* \li Conditions prompting ack packets
* \li Ack types
* \li Error codes
* \li Debugging values
* \par
* An attempt has been made to relate these constant definitions to the objects
* or routines that utilize them.
*
* \subsection sec5-2-1 Section 5.2.1: Configuration Quantities
*
* \par
* These definitions provide some basic Rx configuration parameters, including
* the number of simultaneous calls that may be handled on a single connection,
* lightweight thread parameters, and timeouts for various operations.
*
* \par Name
* RX IDLE DEAD TIME
* \par Value
* 60
* \par Description
* Default idle dead time for connections, in seconds.
*
* \par Name
* RX MAX SERVICES
* \par Value
* 20
* \par Description
* The maximum number of Rx services that may be installed within one
* application.
*
* \par Name
* RX PROCESS MAXCALLS
* \par Value
* 4
* \par Description
* The maximum number of asynchronous calls active simultaneously on any given
* Rx connection. This value must be set to a power of two.
*
* \par Name
* RX DEFAULT STACK SIZE
* \par Value
* 16,000
* \par Description
* Default lightweight thread stack size, measured in bytes. This value may be
* overridden by calling the rx_SetStackSize() macro.
*
* \par Name
* RX PROCESS PRIORITY
* \par Value
* LWP NORMAL PRIORITY
* \par Description
* This is the priority under which an Rx thread should run. There should not
* generally be any reason to change this setting.
*
* \par Name
* RX CHALLENGE TIMEOUT
* \par Value
* 2
* \par Description
* The number of seconds before another authentication request packet is
* generated.
*
* \par Name
* RX MAXACKS
* \par Value
* 255
* \par Description
* Maximum number of individual acknowledgements that may be carried in an Rx
* acknowledgement packet.
*
* \subsection sec5-2-2 Section 5.2.2: Waiting Options
*
* \par
* These definitions provide readable values indicating whether an operation
* should block when packet buffer resources are not available.
*
* \par Name
* RX DONTWAIT
* \par Value
* 0
* \par Description
* Wait until the associated operation completes.
*
* \par Name
* RX WAIT
* \par Value
* 1
* \par Description
* Don't wait if the associated operation would block.
*
* \subsection sec5-2-3 Section 5.2.3: Connection ID Operations
*
* \par
* These values assist in extracting the call channel number from a connection
* identifier. A call channel is the index of a particular asynchronous call
* structure within a single Rx connection.
*
* \par Name
* RX CIDSHIFT
* \par Value
* 2
* \par Description
* Number of bits to right-shift to isolate a connection ID. Must be set to
* the log (base two) of RX MAXCALLS.
*
* \par Name
* RX CHANNELMASK
* \par Value
* (RX MAXCALLS-1)
* \par Description
* Mask used to isolate a call channel from a connection ID field.
*
* \par Name
* RX CIDMASK
* \par Value
* (~RX CHANNELMASK)
* \par Description
* Mask used to isolate the connection ID from its field, masking out the call
* channel information.
*
* \subsection sec5-2-4 Section 5.2.4: Connection Flags
*
* \par
* The values defined here appear in the flags field of Rx connections, as
* defined by the rx connection structure described in Section 5.3.2.2.
*
* \par Name
* RX CONN MAKECALL WAITING
* \par Value
* 1
* \par Description
* rx MakeCall() is waiting for a channel.
*
* \par Name
* RX CONN DESTROY ME
* \par Value
* 2
* \par Description
* Destroy this (client) connection after its last call completes.
*
* \par Name
* RX CONN USING PACKET CKSUM
* \par Value
* 4
* \par Description
* This packet is using security-related check-summing (a non-zero header,
* spare field has been seen.)
*
* \subsection sec5-2-5 Section 5.2.5: Connection Types
*
* \par
* Rx stores different information in its connection structures, depending on
* whether the given connection represents the server side (the one providing
* the service) or the client side (the one requesting the service) of the
* protocol. The type field within the connection structure (described in
* Section 5.3.2.2) takes on the following values to differentiate the two
* types of connections, and identifies the fields that are active within the
* connection structure.
*
* \par Name
* RX CLIENT CONNECTION
* \par Value
* 0
* \par Description
* This is a client-side connection.
*
* \par Name
* CONNECTION
* \par Value
* 1
* \par Description
* This is a server-side connection.
*
* \subsection sec5-2-6 Section 5.2.6: Call States
*
* \par
* An Rx call on a particular connection may be in one of several states at any
* instant in time. The following definitions identify the range of states that
* a call may assume.
*
* \par Name
* RX STATE NOTINIT
* \par Value
* 0
* \par Description
* The call structure has never been used, and is thus still completely
* uninitialized.
*
* \par Name
* RX STATE PRECALL
* \par Value
* 1
* \par Description
* A call is not yet in progress, but packets have arrived for it anyway. This
* only applies to calls within server-side connections.
*
* \par Name
* RX STATE ACTIVE
* \par Value
* 2
* \par Description
* This call is fully active, having an attached lightweight thread operating
* on its behalf.
*
* \par Name
* RX STATE DAILY
* \par Value
* 3
* \par Description
* The call structure is "dallying" after its lightweight thread has completed
* its most recent call. This is a "hot-standby" condition, where the call
* structure preserves state from the previous call and thus optimizes the
* arrival of further, related calls.
*
* \subsection sec5-2-7 Section 5.2.7: Call Flags:
*
* \par
* These values are used within the flags field of a variable declared to be of
* type struct rx call, as described in Section 5.3.2.4. They provide
* additional information as to the state of the given Rx call, such as the
* type of event for which it is waiting (if any) and whether or not all
* incoming packets have been received in support of the call.
*
* \par Name
* RX CALL READER WAIT
* \par Value
* 1
* \par Description
* Reader is waiting for next packet.
*
* \par Name
* RX CALL WAIT WINDOW ALLOC
* \par Value
* 2
* \par Description
* Sender is waiting for a window so that it can allocate buffers.
*
* \par Name
* RX CALL WAIT WINDOW SEND
* \par Value
* 4
* \par Description
* Sender is waiting for a window so that it can send buffers.
*
* \par Name
* RX CALL WAIT PACKETS
* \par Value
* 8
* \par Description
* Sender is waiting for packet buffers.
*
* \par Name
* RX CALL RECEIVE DONE
* \par Value
* 16
* \par Description
* The call is waiting for a lightweight thread to be assigned to the operation
* it has just received.
*
* \par Name
* RX CALL RECEIVE DONE
* \par Value
* 32
* \par Description
* All packets have been received on this call.
*
* \par Name
* RX CALL CLEARED
* \par Value
* 64
* \par Description
* The receive queue has been cleared when in precall state.
*
* \subsection sec5-2-8 Section 5.2.8: Call Modes
*
* \par
* These values define the modes of an Rx call when it is in the RX STATE
* ACTIVE state, having a lightweight thread assigned to it.
*
* \par Name
* RX MODE SENDING
* \par Value
* 1
* \par Description
* We are sending or ready to send.
*
* \par Name
* RX MODE RECEIVING
* \par Value
* 2
* \par Description
* We are receiving or ready to receive.
*
* \par Name
* RX MODE ERROR
* \par Value
* 3
* \par Description
* Something went wrong in the current conversation.
*
* \par Name
* RX MODE EOF
* \par Value
* 4
* \par Description
* The server side has flushed (or the client side has read) the last reply
* packet.
*
* \subsection sec5-2-9 Section 5.2.9: Packet Header Flags
*
* \par
* Rx packets carry a flag field in their headers, providing additional
* information regarding the packet's contents. The Rx packet header's flag
* field's bits may take the following values:
*
* \par Name
* RX CLIENT INITIATED
* \par Value
* 1
* \par Description
* Signifies that a packet has been sent/received from the client side of the
* call.
*
* \par Name
* RX REQUEST ACK
* \par Value
* 2
* \par Description
* The Rx calls' peer entity requests an acknowledgement.
*
* \par Name
* RX LAST PACKET
* \par Value
* 4
* \par Description
* This is the final packet from this side of the call.
*
* \par Name
* RX MORE PACKETS
* \par Value
* 8
* \par Description
* There are more packets following this, i.e., the next sequence number seen
* by the receiver should be greater than this one, rather than a
* retransmission of an earlier sequence number.
*
* \par Name
* RX PRESET FLAGS
* \par Value
* (RX CLIENT INITIATED | RX LAST PACKET)
* \par Description
* This flag is preset once per Rx packet. It doesn't change on retransmission
* of the packet.
*
* \subsection sec5-3-10 Section 5.2.10: Packet Sizes
*
* \par
* These values provide sizing information on the various regions within Rx
* packets. These packet sections include the IP/UDP headers and bodies as well
* Rx header and bodies. Also covered are such values as different maximum
* packet sizes depending on whether they are targeted to peers on the same
* local network or a more far-flung network. Note that the MTU term appearing
* below is an abbreviation for Maximum Transmission Unit.
*
* \par Name
* RX IPUDP SIZE
* \par Value
* 28
* \par Description
* The number of bytes taken up by IP/UDP headers.
*
* \par Name
* RX MAX PACKET SIZE
* \par Value
* (1500 - RX IPUDP SIZE)
* \par Description
* This is the Ethernet MTU minus IP and UDP header sizes.
*
* \par Name
* RX HEADER SIZE
* \par Value
* sizeof (struct rx header)
* \par Description
* The number of bytes in an Rx packet header.
*
* \par Name
* RX MAX PACKET DATA SIZE
* \par Value
* (RX MAX PACKET SIZE RX - HEADER SIZE)
* \par Description
* Maximum size in bytes of the user data in a packet.
*
* \par Name
* RX LOCAL PACKET SIZE
* \par Value
* RX MAX PACKET SIZE
* \par Description
* Packet size in bytes to use when being sent to a host on the same net.
*
* \par Name
* RX REMOTE PACKET SIZE
* \par Value
* (576 - RX IPUDP SIZE)
* \par Description
* Packet size in bytes to use when being sent to a host on a different net.
*
* \subsection sec5-2-11 Section 5.2.11: Packet Types
*
* \par
* The following values are used in the packetType field within a struct rx
* packet, and define the different roles assumed by Rx packets. These roles
* include user data packets, different flavors of acknowledgements, busies,
* aborts, authentication challenges and responses, and debugging vehicles.
*
* \par Name
* RX PACKET TYPE DATA
* \par Value
* 1
* \par Description
* A user data packet.
*
* \par Name
* RX PACKET TYPE ACK
* \par Value
* 2
* \par Description
* Acknowledgement packet.
*
* \par Name
* RX PACKET TYPE BUSY
* \par Value
* 3
* \par Description
* Busy packet. The server-side entity cannot accept the call at the moment,
* but the requestor is encouraged to try again later.
*
* \par Name
* RX PACKET TYPE ABORT
* \par Value
* 4
* \par Description
* Abort packet. No response is needed for this packet type.
*
* \par Name
* RX PACKET TYPE ACKALL
* \par Value
* 5
* \par Description
* Acknowledges receipt of all packets on a call.
*
* \par Name
* RX PACKET TYPE CHALLENGE
* \par Value
* 6
* \par Description
* Challenge the client's identity, requesting credentials.
*
* \par Name
* RX PACKET TYPE RESPONSE
* \par Value
* 7
* \par Description
* Response to a RX PACKET TYPE CHALLENGE authentication challenge packet.
*
* \par Name
* RX PACKET TYPE DEBUG
* \par Value
* 8
* \par Description
* Request for debugging information.
*
* \par Name
* RX N PACKET TYPES
* \par Value
* 9
* \par Description
* The number of Rx packet types defined above. Note that it also includes
* packet type 0 (which is unused) in the count.
*
* \par
* The RX PACKET TYPES definition provides a mapping of the above values to
* human-readable string names, and is exported by the rx packetTypes variable
* catalogued in Section 5.4.9.
*
* \code
* {
* "data",
* "ack",
* "busy",
* "abort",
* "ackall",
* "challenge",
* "response",
* "debug"
* }
* \endcode
*
* \subsection sec5-2-12 Section 5.2.12: Packet Classes
*
* \par
* These definitions are used internally to manage alloction of Rx packet
* buffers according to quota classifications. Each packet belongs to one of
* the following classes, and its buffer is derived from the corresponding
* pool.
*
* \par Name
* RX PACKET CLASS RECEIVE
* \par Value
* 0
* \par Description
* Receive packet for user data.
*
* \par Name
* RX PACKET CLASS SEND
* \par Value
* 1
* \par Description
* Send packet for user data.
*
* \par Name
* RX PACKET CLASS SPECIAL
* \par Value
* 2
* \par Description
* A special packet that does not hold user data, such as an acknowledgement or
* authentication challenge.
*
* \par Name
* RX N PACKET CLASSES
* \par Value
* 3
* \par Description
* The number of Rx packet classes defined above.
*
* \subsection sec5-2-13 Section 5.2.13: Conditions Prompting Ack Packets
*
* \par
* Rx acknowledgement packets are constructed and sent by the protocol
* according to the following reasons. These values appear in the Rx packet
* header of the ack packet itself.
*
* \par Name
* RX ACK REQUESTED
* \par Value
* 1
* \par Description
* The peer has explicitly requested an ack on this packet.
*
* \par Name
* RX ACK DUPLICATE
* \par Value
* 2
* \par Description
* A duplicate packet has been received.
*
* \par Name
* RX ACK OUT OF SEQUENCE
* \par Value
* 3
* \par Description
* A packet has arrived out of sequence.
*
* \par Name
* RX ACK EXCEEDS WINDOW
* \par Value
* 4
* \par Description
* A packet sequence number higher than maximum value allowed by the call's
* window has been received.
*
* \par Name
* RX ACK NOSPACE
* \par Value
* 5
* \par Description
* No packet buffer space is available.
*
* \par Name
* RX ACK PING
* \par Value
* 6
* \par Description
* Acknowledgement for keep-alive purposes.
*
* \par Name
* RX ACK PING RESPONSE
* \par Value
* 7
* \par Description
* Response to a RX ACK PING packet.
*
* \par Name
* RX ACK DELAY
* \par Value
* 8
* \par Description
* An ack generated due to a period of inactivity after normal packet
* receptions.
*
* \subsection 5-2-14 Section 5.2.14: Acknowledgement Types
*
* \par
* These are the set of values placed into the acks array in an Rx
* acknowledgement packet, whose data format is defined by struct rx ackPacket.
* These definitions are used to convey positive or negative acknowledgements
* for a given range of packets.
*
* \par Name
* RX ACK TYPE NACK
* \par Value
* 0
* \par Description
* Receiver doesn't currently have the associated packet; it may never hae been
* received, or received and then later dropped before processing.
*
* \par Name
* RX ACK TYPE ACK
* \par Value
* 1
* \par Description
* Receiver has the associated packet queued, although it may later decide to
* discard it.
*
* \subsection sec5-2-15 Section 5.2.15: Error Codes
*
* \par
* Rx employs error codes ranging from -1 to -64. The Rxgen stub generator may
* use other error codes less than -64. User programs calling on Rx, on the
* other hand, are expected to return positive error codes. A return value of
* zero is interpreted as an indication that the given operation completed
* successfully.
*
* \par Name
* RX CALL DEAD
* \par Value
* -1
* \par Description
* A connection has been inactive past Rx's tolerance levels and has been shut
* down.
*
* \par Name
* RX INVALID OPERATION
* \par Value
* -2
* \par Description
* An invalid operation has been attempted, including such protocol errors as
* having a client-side call send data after having received the beginning of a
* reply from its server-side peer.
*
* \par Name
* RX CALL TIMEOUT
* \par Value
* -3
* \par Description
* The (optional) timeout value placed on this call has been exceeded (see
* Sections 5.5.3.4 and 5.6.5).
*
* \par Name
* RX EOF
* \par Value
* -4
* \par Description
* Unexpected end of data on a read operation.
*
* \par Name
* RX PROTOCOL ERROR
* \par Value
* -5
* \par Description
* An unspecified low-level Rx protocol error has occurred.
*
* \par Name
* RX USER ABORT
* \par Value
* -6
* \par Description
* A generic user abort code, used when no more specific error code needs to be
* communicated. For example, Rx clients employing the multicast feature (see
* Section 1.2.8) take advantage of this error code.
*
* \subsection sec5-2-16 Section 5.2.16: Debugging Values
*
* \par
* Rx provides a set of data collections that convey information about its
* internal status and performance. The following values have been defined in
* support of this debugging and statistics-collection feature.
*
* \subsubsection sec5-3-16-1 Section 5.2.16.1: Version Information
*
* \par
* Various versions of the Rx debugging/statistics interface are in existance,
* each defining different data collections and handling certain bugs. Each Rx
* facility is stamped with a version number of its debugging/statistics
* interface, allowing its clients to tailor their requests to the precise data
* collections that are supported by a particular Rx entity, and to properly
* interpret the data formats received through this interface. All existing Rx
* implementations should be at revision M.
*
* \par Name
* RX DEBUGI VERSION MINIMUM
* \par Value
* 'L'
* \par Description
* The earliest version of Rx statistics available.
*
* \par Name
* RX DEBUGI VERSION
* \par Value
* 'M'
* \par Description
* The latest version of Rx statistics available.
*
* \par Name
* RX DEBUGI VERSION W SECSTATS
* \par Value
* 'L'
* \par Description
* Identifies the earliest version in which statistics concerning Rx security
* objects is available.
*
* \par Name
* RX DEBUGI VERSION W GETALLCONN
* \par Value
* 'M'
* \par Description
* The first version that supports getting information about all current Rx
* connections, as specified y the RX DEBUGI GETALLCONN debugging request
* packet opcode described below.
*
* \par Name
* RX DEBUGI VERSION W RXSTATS
* \par Value
* 'M'
* \par Description
* The first version that supports getting all the Rx statistics in one
* operation, as specified by the RX DEBUGI RXSTATS debugging request packet
* opcode described below.
*
* \par Name
* RX DEBUGI VERSION W UNALIGNED CONN
* \par Value
* 'L'
* \par Description
* There was an alignment problem discovered when returning Rx connection
* information in older versions of this debugging/statistics interface. This
* identifies the last version that exhibited this alignment problem.
*
* \subsubsection sec5-2-16-2 Section 5.2.16.2: Opcodes
*
* \par
* When requesting debugging/statistics information, the caller specifies one
* of the following supported data collections:
*
* \par Name
* RX DEBUGI GETSTATS
* \par Value
* 1
* \par Description
* Get basic Rx statistics.
*
* \par Name
* RX DEBUGI GETCONN
* \par Value
* 2
* \par Description
* Get information on all Rx connections considered "interesting" (as defined
* below), and no others.
*
* \par Name
* RX DEBUGI GETALLCONN
* \par Value
* 3
* \par Description
* Get information on all existing Rx connection structures, even
* "uninteresting" ones.
*
* \par Name
* RX DEBUGI RXSTATS
* \par Value
* 4
* \par Description
* Get all available Rx stats.
*
* \par
* An Rx connection is considered "interesting" if it is waiting for a call
* channel to free up or if it has been marked for destruction. If neither is
* true, a connection is still considered interesting if any of its call
* channels is actively handling a call or in its preparatory pre-call state.
* Failing all the above conditions, a connection is still tagged as
* interesting if any of its call channels is in either of the RX MODE SENDING
* or RX MODE RECEIVING modes, which are not allowed when the call is not
* active.
*
* \subsubsection sec5-2-16-3 Section 5.2.16.3: Queuing
*
* \par
* These two queueing-related values indicate whether packets are present on
* the incoming and outgoing packet queues for a given Rx call. These values
* are only used in support of debugging and statistics-gathering operations.
*
* \par Name
* RX OTHER IN
* \par Value
* 1
* \par Description
* Packets available in in queue.
*
* \par Name
* RX OTHER OUT
* \par Value
* 2
* \par Description
* Packets available in out queue.
*
* \section sec5-3 Section 5.3: Structures
*
* \par
* This section describes the major exported Rx data structures of interest to
* application programmers. The following categories are utilized for the
* purpose of organizing the structure descriptions:
* \li Security objects
* \li Protocol objects
* \li Packet formats
* \li Debugging and statistics
* \li Miscellaneous
* \par
* Please note that many fields described in this section are declared to be
* VOID. This is defined to be char, and is used to get around some compiler
* limitations.
* \subsection sec5-3-1 Section 5.3.1: Security Objects
*
* \par
* As explained in Section 1.2.1, Rx provides a modular, extensible security
* model. This allows Rx applications to either use one of the built-in
* security/authentication protocol packages or write and plug in one of their
* own. This section examines the various structural components used by Rx to
* support generic security and authentication modules.
*
* \subsubsection sec5-3-1-1 Section 5.3.1.1: struct rx securityOps
*
* \par
* As previously described, each Rx security object must export a fixed set of
* interface functions, providing the full set of operations defined on the
* object. The rx securityOps structure defines the array of functions
* comprising this interface. The Rx facility calls these routines at the
* appropriate times, without knowing the specifics of how any particular
* security object implements the operation.
* \par
* A complete description of these interface functions, including information
* regarding their exact purpose, parameters, and calling conventions, may be
* found in Section 5.5.7.
* \par
* \b fields
* \li int (*op Close)() - React to the disposal of a security object.
* \li int (*op NewConnection)() - Invoked each time a new Rx connection
* utilizing the associated security object is created.
* \li int (*op PreparePacket)() - Invoked each time an outgoing Rx packet is
* created and sent on a connection using the given security object.
* \li int (*op SendPacket)() - Called each time a packet belonging to a call
* in a connection using the security object is physically transmitted.
* \li int (*op CheckAuthentication)() - This function is executed each time it
* is necessary to check whether authenticated calls are being perfomed on a
* connection using the associated security object.
* \li int (*op CreateChallenge)() - Invoked each time a server-side challenge
* event is created by Rx, namely when the identity of the principal associated
* with the peer process must be determined.
* \li int (*op GetChallenge)() - Called each time a client-side packet is
* constructed in response to an authentication challenge.
* \li int (*op GetResponse)() - Executed each time a response to a challenge
* event must be received on the server side of a connection.
* \li int (*op CheckResponse)() - Invoked each time a response to an
* authentication has been received, validating the response and pulling out
* the required authentication information.
* \li int (*op CheckPacket) () - Invoked each time an Rx packet has been
* received, making sure that the packet is properly formatted and that it
* hasn't been altered.
* \li int (*op DestroyConnection)() - Called each time an Rx connection
* employing the given security object is destroyed.
* \li int (*op GetStats)() - Executed each time a request for statistics on
* the given security object has been received.
* \li int (*op Spare1)()-int (*op Spare3)() - Three spare function slots,
* reserved for future use.
*
* \subsubsection sec5-3-1-2 Section 5.2.1.2: struct rx securityClass
*
* \par
* Variables of type struct rx securityClass are used to represent
* instantiations of a particular security model employed by Rx. It consists of
* a pointer to the set of interface operations implementing the given security
* object, along with a pointer to private storage as necessary to support its
* operations. These security objects are also reference-counted, tracking the
* number of Rx connections in existance that use the given security object. If
* the reference count drops to zero, the security module may garbage-collect
* the space taken by the unused security object.
* \par
* \b fields
* \li struct rx securityOps *ops - Pointer to the array of interface functions
* for the security object.
* \li VOID *privateData - Pointer to a region of storage used by the security
* object to support its operations.
* \li int refCount - A reference count on the security object, tracking the
* number of Rx connections employing this model.
*
* \subsubsection sec5-3-1-3 Section 5.3.1.3: struct rx
* securityObjectStats
*
* \par
* This structure is used to report characteristics for an instantiation of a
* security object on a particular Rx connection, as well as performance
* figures for that object. It is used by the debugging portions of the Rx
* package. Every security object defines and manages fields such as level and
* flags differently.
* \par
* \b fields
* \li char type - The type of security object being implemented. Existing
* values are:
* \li 0: The null security package.
* \li 1: An obsolete Kerberos-like security object.
* \li 2: The rxkad discipline (see Chapter 3).
* \li char level - The level at which encryption is utilized.
* \li char sparec[10] - Used solely for alignment purposes.
* \li long flags - Status flags regarding aspects of the connection relating
* to the security object.
* \li u long expires - Absolute time when the authentication information
* cached by the given connection expires. A value of zero indicates that the
* associated authentication information is valid for all time.
* \li u long packetsReceived - Number of packets received on this particular
* connection, and thus the number of incoming packets handled by the
* associated security object.
* \li u long packetsSent - Number of packets sent on this particular
* connection, and thus the number of outgoing packets handled by the
* associated security object.
* \li u long bytesReceived - Overall number of "payload" bytes received (i.e.,
* packet bytes not associated with IP headers, UDP headers, and the security
* module's own header and trailer regions) on this connection.
* \li u long bytesSent - Overall number of "payload" bytes sent (i.e., packet
* bytes not associated with IP headers, UDP headers, and the security module's
* own header and trailer regions) on this connection.
* \li short spares[4] - Several shortword spares, reserved for future use.
* \li long sparel[8] - Several longword spares, reserved for future use.
*
* \subsection sec5-3-2 Section 5.3.2: Protocol Objects
*
* \par
* The structures describing the main abstractions and entities provided by Rx,
* namely services, peers, connections and calls are covered in this section.
*
* \subsubsection sec5-3-2-1 Section 5.3.2.1: struct rx service
*
* \par
* An Rx-based server exports services, or specific RPC interfaces that
* accomplish certain tasks. Services are identified by (host-address,
* UDP-port, serviceID) triples. An Rx service is installed and initialized on
* a given host through the use of the rx NewService() routine (See Section
* 5.6.3). Incoming calls are stamped with the Rx service type, and must match
* an installed service to be accepted. Internally, Rx services also carry
* string names for purposes of identification. These strings are useful to
* remote debugging and statistics-gathering programs. The use of a service ID
* allows a single server process to export multiple, independently-specified
* Rx RPC services.
* \par
* Each Rx service contains one or more security classes, as implemented by
* individual security objects. These security objects implement end-to-end
* security protocols. Individual peer-to-peer connections established on
* behalf of an Rx service will select exactly one of the supported security
* objects to define the authentication procedures followed by all calls
* associated with the connection. Applications are not limited to using only
* the core set of built-in security objects offered by Rx. They are free to
* define their own security objects in order to execute the specific protocols
* they require.
* \par
* It is possible to specify both the minimum and maximum number of lightweight
* processes available to handle simultaneous calls directed to an Rx service.
* In addition, certain procedures may be registered with the service and
* called at set times in the course of handling an RPC request.
* \par
* \b fields
* \li u short serviceId - The associated service number.
* \li u short servicePort - The chosen UDP port for this service.
* \li char *serviceName - The human-readable service name, expressed as a
* character
* \li string. osi socket socket - The socket structure or file descriptor used
* by this service.
* \li u short nSecurityObjects - The number of entries in the array of
* supported security objects.
* \li struct rx securityClass **securityObjects - The array of pointers to the
* ser
* vice's security class objects.
* \li long (*executeRequestProc)() - A pointer to the routine to call when an
* RPC request is received for this service.
* \li VOID (*destroyConnProc)() - A pointer to the routine to call when one of
* the server-side connections associated with this service is destroyed.
* \li VOID (*newConnProc)() - A pointer to the routine to call when a
* server-side connection associated with this service is created.
* \li VOID (*beforeProc)() - A pointer to the routine to call before an
* individual RPC call on one of this service's connections is executed.
* \li VOID (*afterProc)() - A pointer to the routine to call after an
* individual RPC call on one of this service's connections is executed.
* \li short nRequestsRunning - The number of simultaneous RPC calls currently
* in progress for this service.
* \li short maxProcs - This field has two meanings. first, maxProcs limits the
* total number of requests that may execute in parallel for any one service.
* It also guarantees that this many requests may be handled in parallel if
* there are no active calls for any other service.
* \li short minProcs - The minimum number of lightweight threads (hence
* requests) guaranteed to be simultaneously executable.
* \li short connDeadTime - The number of seconds until a client of this
* service will be declared to be dead, if it is not responding to the RPC
* protocol.
* \li short idleDeadTime - The number of seconds a server-side connection for
* this service will wait for packet I/O to resume after a quiescent period
* before the connection is marked as dead.
*
* \subsubsection sec5-3-2-2 Section 5.3.2.2: struct rx connection
*
* \par
* An Rx connection represents an authenticated communication path, allowing
* multiple asynchronous conversations (calls). Each connection is identified
* by a connection ID. The low-order bits of the connection ID are reserved so
* they may be stamped with the index of a particular call channel. With up to
* RX MAXCALLS concurrent calls (set to 4 in this implementation), the bottom
* two bits are set aside for this purpose. The connection ID is not sufficient
* by itself to uniquely identify an Rx connection. Should a client crash and
* restart, it may reuse a connection ID, causing inconsistent results. In
* addition to the connection ID, the epoch, or start time for the client side
* of the connection, is used to identify a connection. Should the above
* scenario occur, a different epoch value will be chosen by the client,
* differentiating this incarnation from the orphaned connection record on the
* server side.
* \par
* Each connection is associated with a parent service, which defines a set of
* supported security models. At creation time, an Rx connection selects the
* particular security protocol it will implement, referencing the associated
* service. The connection structure maintains state about the individual calls
* being simultaneously handled.
* \par
* \b fields
* \li struct rx connection *next - Used for internal queueing.
* \li struct rx peer *peer - Pointer to the connection's peer information (see
* below).
* \li u long epoch - Process start time of the client side of the connection.
* \li u long cid - Connection identifier. The call channel (i.e., the index
* into the connection's array of call structures) may appear in the bottom
* bits.
* \li VOID *rock - Pointer to an arbitrary region of memory in support of the
* connection's operation. The contents of this area are opaque to the Rx
* facility in general, but are understood by any special routines used by this
* connection.
* \li struct rx call *call[RX MAXCALLS] - Pointer to the call channel
* structures, describing up to RX MAXCALLS concurrent calls on this
* connection.
* \li u long callNumber[RX MAXCALLS] - The set of current call numbers on each
* of the call channels.
* \li int timeout - Obsolete; no longer used.
* \li u char flags - Various states of the connection; see Section 5.2.4 for
* individual bit definitions.
* \li u char type - Whether the connection is a server-side or client-side
* one. See Section 5.2.5 for individual bit definitions.
* \li u short serviceId - The service ID that should be stamped on requests.
* This field is only used by client-side instances of connection structures.
* \li struct rx service *service - A pointer to the service structure
* associated with this connection. This field is only used by server-side
* instances of connection structures.
* \li u long serial - Serial number of the next outgoing packet associated
* with this connection.
* \li u long lastSerial - Serial number of the last packet received in
* association with this connection. This field is used in computing packet
* skew.
* \li u short secondsUntilDead - Maximum numer of seconds of silence that
* should be tolerated from the connection's peer before calls will be
* terminated with an RX CALL DEAD error.
* \li u char secondsUntilPing - The number of seconds between "pings"
* (keep-alive probes) when at least one call is active on this connection.
* \li u char securityIndex - The index of the security object being used by
* this connection. This number selects a slot in the security class array
* maintained by the service associated with the connection.
* \li long error - Records the latest error code for calls occurring on this
* connection.
* \li struct rx securityClass *securityObject - A pointer to the security
* object used by this connection. This should coincide with the slot value
* chosen by the securityIndex field described above.
* \li VOID *securityData - A pointer to a region dedicated to hosting any
* storage required by the security object being used by this connection.
* \li u short securityHeaderSize - The length in bytes of the portion of the
* packet header before the user's data that contains the security module's
* information.
* \li u short securityMaxTrailerSize - The length in bytes of the packet
* trailer, appearing after the user's data, as mandated by the connection's
* security module.
* \li struct rxevent *challengeEvent -Pointer to an event that is scheduled
* when the server side of the connection is challenging the client to
* authenticate itself.
* \li int lastSendTime - The last time a packet was sent on this connection.
* \li long maxSerial - The largest serial number seen on incoming packets.
* \li u short hardDeadTime - The maximum number of seconds that any call on
* this connection may execute. This serves to throttle runaway calls.
*
* \subsubsection sec5-3-2-3 Section 5.3.2.3: struct rx peer
*
* \par
* For each connection, Rx maintains information describing the entity, or
* peer, on the other side of the wire. A peer is identified by a (host,
* UDP-port) pair. Included in the information kept on this remote
* communication endpoint are such network parameters as the maximum packet
* size supported by the host, current readings on round trip time to
* retransmission delays, and packet skew (see Section 1.2.7). There are also
* congestion control fields, ranging from descriptions of the maximum number
* of packets that may be sent to the peer without pausing and retransmission
* statistics. Peer structures are shared between connections whenever
* possible, and hence are reference-counted. A peer object may be
* garbage-collected if it is not actively referenced by any connection
* structure and a sufficient period of time has lapsed since the reference
* count dropped to zero.
* \par
* \b fields
* \li struct rx peer *next - Use to access internal lists.
* \li u long host - Remote IP address, in network byte order
* \li u short port - Remote UDP port, in network byte order
* \li short packetSize - Maximum packet size for this host, if known.
* \li u long idleWhen - When the refCount reference count field (see below)
* went to zero.
* \li short refCount - Reference count for this structure
* \li u char burstSize - Reinitialization size for the burst field (below).
* \li u char burst - Number of packets that can be transmitted immediately
* without pausing.
* \li struct clock burstWait - Time delay until new burst aimed at this peer
* is allowed.
* \li struct queue congestionQueue - Queue of RPC call descriptors that are
* waiting for a non-zero burst value.
* \li int rtt - Round trip time to the peer, measured in milliseconds.
* \li struct clock timeout - Current retransmission delay to the peer.
* \li int nSent - Total number of distinct data packets sent, not including
* retransmissions.
* \li int reSends - Total number of retransmissions for this peer since the
* peer structure instance was created.
* \li u long inPacketSkew - Maximum skew on incoming packets (see Section
* 1.2.7)
* \li u long outPacketSkew - Peer-reported maximum skew on outgoing packets
* (see Section 1.2.7).
*
* \subsubsection sec5-3-2-4 Section 5.3.2.4: struct rx call
*
* \par
* This structure records the state of an active call proceeding on a given Rx
* connection. As described above, each connection may have up to RX MAXCALLS
* calls active at any one instant, and thus each connection maintains an array
* of RX MAXCALLS rx call structures. The information contained here is
* specific to the given call; "permanent" call state, such as the call number,
* is maintained in the connection structure itself.
* \par
* \b fields
* \li struct queue queue item header - Queueing information for this
* structure.
* \li struct queue tq - Queue of outgoing ("transmit") packets.
* \li struct queue rq - Queue of incoming ("receive") packets.
* \li char *bufPtr - Pointer to the next byte to fill or read in the call's
* current packet, depending on whether it is being transmitted or received.
* \li u short nLeft - Number of bytes left to read in the first packet in the
* reception queue (see field rq).
* \li u short nFree - Number of bytes still free in the last packet in the
* transmission queue (see field tq).
* \li struct rx packet *currentPacket - Pointer to the current packet being
* assembled or read.
* \li struct rx connection *conn - Pointer to the parent connection for this
* call.
* \li u long *callNumber - Pointer to call number field within the call's
* current packet.
* \li u char channel - Index within the parent connection's call array that
* describes this call.
* \li u char dummy1, dummy2 - These are spare fields, reserved for future use.
* \li u char state - Current call state. The associated bit definitions appear
* in Section 5.2.7.
* \li u char mode - Current mode of a call that is in RX STATE ACTIVE state.
* The associated bit definitions appear in Section 5.2.8.
* \li u char flags - Flags pertaining to the state of the given call. The
* associated bit definitions appear in Section 5.2.7.
* \li u char localStatus - Local user status information, sent out of band.
* This field is currently not in use, set to zero.
* \li u char remoteStatus - Remote user status information, received out of
* band. This field is currently not in use, set to zero.
* \li long error - Error condition for this call.
* \li u long timeout - High level timeout for this call
* \li u long rnext - Next packet sequence number expected to be received.
* \li u long rprev - Sequence number of the previous packet received. This
* number is used to decide the proper sequence number for the next packet to
* arrive, and may be used to generate a negative acknowledgement.
* \li u long rwind - Width of the packet receive window for this call. The
* peer must not send packets with sequence numbers greater than or equal to
* rnext + rwind.
* \li u long tfirst - Sequence number of the first unacknowledged transmit
* packet for this call.
* \li u long tnext - Next sequence number to use for an outgoing packet.
* \li u long twind - Width of the packet transmit window for this call. Rx
* cannot assign a sequence number to an outgoing packet greater than or equal
* to tfirst + twind.
* \li struct rxevent *resendEvent - Pointer to a pending retransmission event,
* if any.
* \li struct rxevent *timeoutEvent - Pointer to a pending timeout event, if
* any.
* \li struct rxevent *keepAliveEvent - Pointer to a pending keep-alive event,
* if this is an active call.
* \li struct rxevent *delayedAckEvent - Pointer to a pending delayed
* acknowledgement packet event, if any. Transmission of a delayed
* acknowledgement packet is scheduled after all outgoing packets for a call
* have been sent. If neither a reply nor a new call are received by the time
* the delayedAckEvent activates, the ack packet will be sent.
* \li int lastSendTime - Last time a packet was sent for this call.
* \li int lastReceiveTime - Last time a packet was received for this call.
* \li VOID (*arrivalProc)() - Pointer to the procedure to call when reply is
* received.
* \li VOID *arrivalProcHandle - Pointer to the handle to pass to the
* arrivalProc as its first argument.
* \li VOID *arrivalProcArg - Pointer to an additional argument to pass to the
* given arrivalProc.
* \li u long lastAcked - Sequence number of the last packet "hard-acked" by
* the receiver. A packet is considered to be hard-acked if an acknowledgement
* is generated after the reader has processed it. The Rx facility may
* sometimes "soft-ack" a windowfull of packets before they have been picked up
* by the receiver.
* \li u long startTime - The time this call started running.
* \li u long startWait - The time that a server began waiting for input data
* or send quota.
*
* \subsection sec5-3-3 Section 5.3.3: Packet Formats
*
* \par
* The following sections cover the different data formats employed by the
* suite of Rx packet types, as enumerated in Section 5.2.11. A description of
* the most commonly-employed Rx packet header appears first, immediately
* followed by a description of the generic packet container and descriptor.
* The formats for Rx acknowledgement packets and debugging/statistics packets
* are also examined.
*
* \subsubsection sec5-3-3-1 Section 5.3.3.1: struct rx header
*
* \par
* Every Rx packet has its own header region, physically located after the
* leading IP/UDP headers. This header contains connection, call, security, and
* sequencing information. Along with a type identifier, these fields allow the
* receiver to properly interpret the packet. In addition, every client relates
* its "epoch", or Rx incarnation date, in each packet. This assists in
* identifying protocol problems arising from reuse of connection identifiers
* due to a client restart. Also included in the header is a byte of
* user-defined status information, allowing out-of-band channel of
* communication for the higher-level application using Rx as a transport
* mechanism.
* \par
* \b fields
* \li u long epoch - Birth time of the client Rx facility.
* \li u long cid - Connection identifier, as defined by the client. The last
* RX CIDSHIFT bits in the cid field identify which of the server-side RX
* MAXCALLS call channels is to receive the packet.
* \li u long callNumber - The current call number on the chosen call channel.
* \li u long seq - Sequence number of this packet. Sequence numbers start with
* 0 for each new Rx call.
* \li u long serial - This packet's serial number. A new serial number is
* stamped on each packet transmitted (or retransmitted).
* \li u char type - What type of Rx packet this is; see Section 5.2.11 for the
* list of legal definitions.
* \li u char flags - Flags describing this packet; see Section 5.2.9 for the
* list of legal settings.
* \li u char userStatus - User-defined status information, uninterpreted by
* the Rx facility itself. This field may be easily set or retrieved from Rx
* packets via calls to the rx GetLocalStatus(), rx SetLocalStatus(), rx
* GetRemoteStatus(), and rx SetRemoteStatus() macros.
* \li u char securityIndex - Index in the associated server-side service class
* of the security object used by this call.
* \li u short serviceId - The server-provided service ID to which this packet
* is directed.
* \li u short spare - This field was originally a true spare, but is now used
* by the built-in rxkad security module for packet header checksums. See the
* descriptions of the related rx IsUsingPktChecksum(), rx GetPacketCksum(),
* and rx SetPacketCksum() macros.
*
* \subsubsection sec5-3-3-2 Section 5.3.3.2: struct rx packet
*
* \par
* This structure is used to describe an Rx packet, and includes the wire
* version of the packet contents, where all fields exist in network byte
* order. It also includes acknowledgement, length, type, and queueing
* information.
* \par
* \b fields
* \li struct queue queueItemHeader - field used for internal queueing.
* \li u char acked - If non-zero, this field indicates that this packet has
* been tentatively (soft-) acknowledged. Thus, the packet has been accepted by
* the rx peer entity on the other side of the connection, but has not yet
* necessarily been passed to the true reader. The sender is not free to throw
* the packet away, as it might still get dropped by the peer before it is
* delivered to its destination process.
* \li short length - Length in bytes of the user data section.
* \li u char packetType - The type of Rx packet described by this record. The
* set of legal choices is available in Section 5.2.11.
* \li struct clock retryTime - The time when this packet should be
* retransmitted next.
* \li struct clock timeSent - The last time this packet was transmitted.
* \li struct rx header header - A copy of the internal Rx packet header.
* \li wire - The text of the packet as it appears on the wire. This structure
* has the following sub-fields:
* \li u long head[RX HEADER SIZE/sizeof(long)] The wire-level contents of
* IP, UDP, and Rx headers.
* \li u long data[RX MAX PACKET DATA SIZE/sizeof(long)] The wire form of
* the packet's "payload", namely the user data it carries.
*
* \subsubsection sec5-3-3-3 Section 5.3.3.3: struct rx ackPacket
*
* \par
* This is the format for the data portion of an Rx acknowledgement packet,
* used to inform a peer entity performing packet transmissions that a subset
* of its packets has been properly received.
* \par
* \b fields
* \li u short bufferSpace - Number of packet buffers available. Specifically,
* the number of packet buffers that the ack packet's sender is willing to
* provide for data on this or subsequent calls. This number does not have to
* fully accurate; it is acceptable for the sender to provide an estimate.
* \li u short maxSkew - The maximum difference seen between the serial number
* of the packet being acknowledged and highest packet yet received. This is an
* indication of the degree to which packets are arriving out of order at the
* receiver.
* \li u long firstPacket - The serial number of the first packet in the list
* of acknowledged packets, as represented by the acks field below.
* \li u long previousPacket - The previous packet serial number received.
* \li u long serial - The serial number of the packet prompted the
* acknowledgement.
* \li u char reason - The reason given for the acknowledgement; legal values
* for this field are described in Section 5.2.13.
* \li u char nAcks - Number of acknowledgements active in the acks array
* immediately following.
* \li u char acks[RX MAXACKS] - Up to RX MAXACKS packet acknowledgements. The
* legal values for each slot in the acks array are described in Section
* 5.2.14. Basically, these fields indicate either positive or negative
* acknowledgements.
*
* \par
* All packets with serial numbers prior to firstPacket are implicitly
* acknowledged by this packet, indicating that they have been fully processed
* by the receiver. Thus, the sender need no longer be concerned about them,
* and may release all of the resources that they occupy. Packets with serial
* numbers firstPacket + nAcks and higher are not acknowledged by this ack
* packet. Packets with serial numbers in the range [firstPacket, firstPacket +
* nAcks) are explicitly acknowledged, yet their sender-side resources must not
* yet be released, as there is yet no guarantee that the receiver will not
* throw them away before they can be processed there.
* \par
* There are some details of importance to be noted. For one, receiving a
* positive acknowlegement via the acks array does not imply that the
* associated packet is immune from being dropped before it is read and
* processed by the receiving entity. It does, however, imply that the sender
* should stop retransmitting the packet until further notice. Also, arrival of
* an ack packet should prompt the transmitter to immediately retransmit all
* packets it holds that have not been explicitly acknowledged and that were
* last transmitted with a serial number less than the highest serial number
* acknowledged by the acks array.
* Note: The fields in this structure are always kept in wire format, namely in
* network byte order.
*
* \subsection sec5-3-4 Section 5.3.4: Debugging and Statistics
*
* \par
* The following structures are defined in support of the debugging and
* statistics-gathering interfaces provided by Rx.
*
* \subsubsection sec5-3-4-1 Section 5.3.4.1: struct rx stats
*
* \par
* This structure maintains Rx statistics, and is gathered by such tools as the
* rxdebug program. It must be possible for all of the fields placed in this
* structure to be successfully converted from their on-wire network byte
* orderings to the host-specific ordering.
* \par
* \b fields
* \li int packetRequests - Number of packet allocation requests processed.
* \li int noPackets[RX N PACKET CLASSES] - Number of failed packet requests,
* organized per allocation class.
* \li int socketGreedy - Whether the SO GREEDY setting succeeded for the Rx
* socket.
* \li int bogusPacketOnRead - Number of inappropriately short packets
* received.
* \li int bogusHost - Contains the host address from the last bogus packet
* received.
* \li int noPacketOnRead - Number of attempts to read a packet off the wire
* when there was actually no packet there.
* \li int noPacketBuffersOnRead - Number of dropped data packets due to lack
* of packet buffers.
* \li int selects - Number of selects waiting for a packet arrival or a
* timeout.
* \li int sendSelects - Number of selects forced when sending packets.
* \li int packetsRead[RX N PACKET TYPES] - Total number of packets read,
* classified by type.
* \li int dataPacketsRead - Number of unique data packets read off the wire.
* \li int ackPacketsRead - Number of ack packets read.
* \li int dupPacketsRead - Number of duplicate data packets read.
* \li int spuriousPacketsRead - Number of inappropriate data packets.
* \li int packetsSent[RX N PACKET TYPES] - Number of packet transmissions,
* broken down by packet type.
* \li int ackPacketsSent - Number of ack packets sent.
* \li int pingPacketsSent - Number of ping packets sent.
* \li int abortPacketsSent - Number of abort packets sent.
* \li int busyPacketsSent - Number of busy packets sent.
* \li int dataPacketsSent - Number of unique data packets sent.
* \li int dataPacketsReSent - Number of retransmissions.
* \li int dataPacketsPushed - Number of retransmissions pushed early by a
* negative acknowledgement.
* \li int ignoreAckedPacket - Number of packets not retransmitted because they
* have already been acked.
* \li int struct clock totalRtt - Total round trip time measured for packets,
* used to compute average time figure.
* \li struct clock minRtt - Minimum round trip time measured for packets.
* struct clock maxRtt - Maximum round trip time measured for packets.
* \li int nRttSamples - Number of round trip samples.
* \li int nServerConns - Number of server connections.
* \li int nClientConns - Number of client connections.
* \li int nPeerStructs - Number of peer structures.
* \li int nCallStructs - Number of call structures physically allocated (using
* the internal storage allocator routine).
* \li int nFreeCallStructs - Number of call structures which were pulled from
* the free queue, thus avoiding a call to the internal storage allocator
* routine.
* \li int spares[10] - Ten integer spare fields, reserved for future use.
*
* \subsubsection sec5-3-4-2 Section 5.3.4.2: struct rx debugIn
*
* \par
* This structure defines the data format for a packet requesting one of the
* statistics collections maintained by Rx.
* \par
* \b fields
* \li long type - The specific data collection that the caller desires. Legal
* settings for this field are described in Section 5.2.16.2.
* \li long index - This field is only used when gathering information on Rx
* connections. Choose the index of the server-side connection record of which
* we are inquiring. This field may be used as an iterator, stepping through
* all the connection records, one per debugging request, until they have all
* been examined.
*
* \subsubsection sec5-3-4-3 Section 5.3.4.3: struct rx debugStats
*
* \par
* This structure describes the data format for a reply to an RX DEBUGI
* GETSTATS debugging request packet. These fields are given values indicating
* the current state of the Rx facility.
* \par
* \b fields
* \li long nFreePackets - Number of packet buffers currently assigned to the
* free pool.
* \li long packetReclaims - Currently unused.
* \li long callsExecuted - Number of calls executed since the Rx facility was
* initialized.
* \li char waitingForPackets - Is Rx currently blocked waiting for a packet
* buffer to come free?
* \li char usedFDs - If the Rx facility is executing in the kernel, return the
* number of unix file descriptors in use. This number is not directly related
* to the Rx package, but rather describes the state of the machine on which Rx
* is running.
* \li char version - Version number of the debugging package.
* \li char spare1[1] - Byte spare, reserved for future use.
* \li long spare2[10] - Set of 10 longword spares, reserved for future use.
*
* \subsubsection sec5-3-4-4 Section 5.3.4.4: struct rx debugConn
*
* \par
* This structure defines the data format returned when a caller requests
* information concerning an Rx connection. Thus, rx debugConn defines the
* external packaging of interest to external parties. Most of these fields are
* set from the rx connection structure, as defined in Section 5.3.2.2, and
* others are obtained by indirecting through such objects as the connection's
* peer and call structures.
* \par
* \b fields
* \li long host - Address of the host identified by the connection's peer
* structure.
* \li long cid - The connection ID.
* \li long serial - The serial number of the next outgoing packet associated
* with this connection.
* \li long callNumber[RX MAXCALLS] - The current call numbers for the
* individual call channels on this connection.
* \li long error - Records the latest error code for calls occurring on this
* connection.
* \li short port - UDP port associated with the connection's peer.
* \li char flags - State of the connection; see Section 5.2.4 for individual
* bit definitions.
* \li char type - Whether the connection is a server-side or client-side one.
* See Section 5.2.5 for individual bit definitions.
* \li char securityIndex - Index in the associated server-side service class
* of the security object being used by this call.
* \li char sparec[3] - Used to force alignment for later fields.
* \li char callState[RX MAXCALLS] - Current call state on each call channel.
* The associated bit definitions appear in Section 5.2.7.
* \li char callMode[RX MAXCALLS] - Current mode of all call channels that are
* in RX STATE ACTIVE state. The associated bit definitions appear in Section
* 5.2.8.
* \li char callFlags[RX MAXCALLS] - Flags pertaining to the state of each of
* the connection's call channels. The associated bit definitions appear in
* Section 5.2.7.
* \li char callOther[RX MAXCALLS] - Flag field for each call channel, where
* the presence of the RX OTHER IN flag indicates that there are packets
* present on the given call's reception queue, and the RX OTHER OUT flag
* indicates the presence of packets on the transmission queue.
* \li struct rx securityObjectStats secStats - The contents of the statistics
* related to the security object selected by the securityIndex field, if any.
* \li long epoch - The connection's client-side incarnation time.
* \li long sparel[10] - A set of 10 longword fields, reserved for future use.
*
* \subsubsection sec5-3-4-5 Section 5.3.4.5: struct rx debugConn vL
*
* \par
* This structure is identical to rx debugConn defined above, except for the
* fact that it is missing the sparec field. This sparec field is used in rx
* debugConn to fix an alignment problem that was discovered in version L of
* the debugging/statistics interface (hence the trailing "tt vL tag in the
* structure name). This alignment problem is fixed in version M, which
* utilizes and exports the rx debugConn structure exclusively. Information
* regarding the range of version-numbering values for the Rx
* debugging/statistics interface may be found in Section 5.2.16.1.
* \section sec5-4 Section 5.4: Exported Variables
*
* \par
* This section describes the set of variables that the Rx facility exports to
* its applications. Some of these variables have macros defined for the sole
* purpose of providing the caller with a convenient way to manipulate them.
* Note that some of these exported variables are never meant to be altered by
* application code (e.g., rx nPackets).
*
* \subsection sec5-4-1 Section 5.4.1: rx connDeadTime
*
* \par
* This integer-valued variable determines the maximum number of seconds that a
* connection may remain completely inactive, without receiving packets of any
* kind, before it is eligible for garbage collection. Its initial value is 12
* seconds. The rx SetRxDeadTime macro sets the value of this variable.
*
* \subsection sec5-4-2 Section 5.4.2: rx idleConnectionTime
*
* \par
* This integer-valued variable determines the maximum number of seconds that a
* server connection may "idle" (i.e., not have any active calls and otherwise
* not have sent a packet) before becoming eligible for garbage collection. Its
* initial value is 60 seconds.
*
* \subsection sec5-4-3 Section 5.4.3: rx idlePeerTime
*
* \par
* This integer-valued variable determines the maximum number of seconds that
* an Rx peer structure is allowed to exist without any connection structures
* referencing it before becoming eligible for garbage collection. Its initial
* value is 60 seconds.
*
* \subsection sec5-4-4 Section 5.4.4: rx extraQuota
*
* \par
* This integer-valued variable is part of the Rx packet quota system (see
* Section 1.2.6), which is used to avoid system deadlock. This ensures that
* each server-side thread has a minimum number of packets at its disposal,
* allowing it to continue making progress on active calls. This particular
* variable records how many extra data packets a user has requested be
* allocated. Its initial value is 0.
*
* \subsection sec5-4-5 Section 5.4.5: rx extraPackets
*
* \par
* This integer-valued variable records how many additional packet buffers are
* to be created for each Rx server thread. The caller, upon setting this
* variable, is applying some application-specific knowledge of the level of
* network activity expected. The rx extraPackets variable is used to compute
* the overall number of packet buffers to reserve per server thread, namely rx
* nPackets, described below. The initial value is 32 packets.
*
* \subsection sec5-4-6 Section 5.4.6: rx nPackets
*
* \par
* This integer-valued variable records the total number of packet buffers to
* be allocated per Rx server thread. It takes into account the quota packet
* buffers and the extra buffers requested by the caller, if any.
* \note This variable should never be set directly; the Rx facility itself
* computes its value. Setting it incorrectly may result in the service
* becoming deadlocked due to insufficient resources. Callers wishing to
* allocate more packet buffers to their server threads should indicate that
* desire by setting the rx extraPackets variable described above.
*
* \subsection sec5-4-7 Section 5.4.7: rx nFreePackets
*
* \par
* This integer-valued variable records the number of Rx packet buffers not
* currently used by any call. These unused buffers are collected into a free
* pool.
*
* \subsection sec5-4-8 Section 5.4.8: rx stackSize
*
* \par
* This integer-valued variable records the size in bytes for the lightweight
* process stack. The variable is initially set to RX DEFAULT STACK SIZE, and
* is typically manipulated via the rx SetStackSize() macro.
*
* \subsection sec5-4-9 Section 5.4.9: rx packetTypes
*
* \par
* This variable holds an array of string names used to describe the different
* roles for Rx packets. Its value is derived from the RX PACKET TYPES
* definition found in Section 5.2.11.
*
* \subsection sec5-4-10 Section 5.4.10: rx stats
*
* \par
* This variable contains the statistics structure that keeps track of Rx
* statistics. The struct rx stats structure it provides is defined in Section
* 5.3.4.1.
*
* \section sec5-5 Section 5.5: Macros
*
* \par
* Rx uses many macro definitions in preference to calling C functions
* directly. There are two main reasons for doing this:
* \li field selection: Many Rx operations are easily realized by returning the
* value of a particular structure's field. It is wasteful to invoke a C
* routine to simply fetch a structure's field, incurring unnecessary function
* call overhead. Yet, a convenient, procedure-oriented operation is still
* provided to Rx clients for such operations by the use of macros. For
* example, the rx ConnectionOf() macro, described in Section 5.5.1.1, simply
* indirects through the Rx call structure pointer parameter to deliver the
* conn field.
* \li Performance optimization: In some cases, a simple test or operation can
* be performed to accomplish a particular task. When this simple,
* straightforward operation fails, then a true C routine may be called to
* handle to more complex (and rarer) situation. The Rx macro rx Write(),
* described in Section 5.5.6.2, is a perfect example of this type of
* optimization. Invoking rx Write() first checks to determine whether or not
* the outgoing call's internal buffer has enough room to accept the specified
* data bytes. If so, it copies them into the call's buffer, updating counts
* and pointers as appropriate. Otherwise, rx Write() calls the rx WriteProc()
* to do the work, which in this more complicated case involves packet
* manipulations, dispatches, and allocations. The result is that the common,
* simple cases are often handled in-line, with more complex (and rarer) cases
* handled through true function invocations.
* \par
* The set of Rx macros is described according to the following categories.
* \li field selections/assignments
* \li Boolean operations
* \li Service attributes
* \li Security-related operations
* \li Sizing operations
* \li Complex operation
* \li Security operation invocations
*
* \subsection sec5-5-1 Section 5.5.1: field Selections/Assignments
*
* \par
* These macros facilitate the fetching and setting of fields from the
* structures described Chapter 5.3.
*
* \subsubsection sec5-5-1-1 Section 5.5.1.1: rx ConnectionOf()
*
* \par
* \#define rx_ConnectionOf(call) ((call)->conn)
* \par
* Generate a reference to the connection field within the given Rx call
* structure. The value supplied as the call argument must resolve into an
* object of type (struct rx call *). An application of the rx ConnectionOf()
* macro itself yields an object of type rx peer.
*
* \subsubsection sec5-5-1-2 Section 5.5.1.2: rx PeerOf()
*
* \par
* \#define rx_PeerOf(conn) ((conn)->peer)
* \par
* Generate a reference to the peer field within the given Rx call structure.
* The value supplied as the conn argument must resolve into an object of type
* (struct rx connection *). An instance of the rx PeerOf() macro itself
* resolves into an object of type rx peer.
*
* \subsubsection sec5-5-1-3 Section 5.5.1.3: rx HostOf()
*
* \par
* \#define rx_HostOf(peer) ((peer)->host)
* \par
* Generate a reference to the host field within the given Rx peer structure.
* The value supplied as the peer argument must resolve into an object of type
* (struct rx peer *). An instance of the rx HostOf() macro itself resolves
* into an object of type u long.
*
* \subsubsection sec5-5-1-4 Section 5.5.1.4: rx PortOf()
*
* \par
* \#define rx_PortOf(peer) ((peer)->port)
* \par
* Generate a reference to the port field within the given Rx peer structure.
* The value supplied as the peer argument must resolve into an object of type
* (struct rx peer *). An instance of the rx PortOf() macro itself resolves
* into an object of type u short.
*
* \subsubsection sec5-5-1-5 Section 5.5.1.5: rx GetLocalStatus()
*
* \par
* \#define rx_GetLocalStatus(call, status) ((call)->localStatus)
* \par
* Generate a reference to the localStatus field, which specifies the local
* user status sent out of band, within the given Rx call structure. The value
* supplied as the call argument must resolve into an object of type (struct rx
* call *). The second argument, status, is not used. An instance of the rx
* GetLocalStatus() macro itself resolves into an object of type u char.
*
* \subsubsection sec5-5-1-6 Section 5.5.1.6: rx SetLocalStatus()
*
* \par
* \#define rx_SetLocalStatus(call, status) ((call)->localStatus = (status))
* \par
* Assign the contents of the localStatus field, which specifies the local user
* status sent out of band, within the given Rx call structure. The value
* supplied as the call argument must resolve into an object of type (struct rx
* call *). The second argument, status, provides the new value of the
* localStatus field, and must resolve into an object of type u char. An
* instance of the rx GetLocalStatus() macro itself resolves into an object
* resulting from the assignment, namely the u char status parameter.
*
* \subsubsection sec5-5-1-7 Section 5.5.1.7: rx GetRemoteStatus()
*
* \par
* \#define rx_GetRemoteStatus(call) ((call)->remoteStatus)
* \par
* Generate a reference to the remoteStatus field, which specifies the remote
* user status received out of band, within the given Rx call structure. The
* value supplied as the call argument must resolve into an object of type
* (struct rx call *). An instance of the rx GetRemoteStatus() macro itself
* resolves into an object of type u char.
*
* \subsubsection sec5-5-1-8 Section 5.5.1.8: rx Error()
*
* \par
* \#define rx_Error(call) ((call)->error)
* \par
* Generate a reference to the error field, which specifies the current error
* condition, within the given Rx call structure. The value supplied as the
* call argument must resolve into an object of type (struct rx call *). An
* instance of the rx Error() macro itself resolves into an object of type
* long.
*
* \subsubsection sec5-5-1-9 Section 5.5.1.9: rx DataOf()
*
* \par
* \#define rx_DataOf(packet) ((char *) (packet)->wire.data)
* \par
* Generate a reference to the beginning of the data portion within the given
* Rx packet as it appears on the wire. Any encryption headers will be resident
* at this address. For Rx packets of type RX PACKET TYPE DATA, the actual user
* data will appear at the address returned by the rx DataOf macro plus the
* connection's security header size. The value supplied as the packet argument
* must resolve into an object of type (struct rx packet *). An instance of the
* rx DataOf() macro itself resolves into an object of type (u long *).
*
* \subsubsection sec5-5-1-10 Section 5.5.1.10: rx GetDataSize()
*
* \par
* \#define rx_GetDataSize(packet) ((packet)->length)
* \par
* Generate a reference to the length field, which specifies the number of
* bytes of user data contained within the wire form of the packet, within the
* given Rx packet description structure. The value supplied as the packet
* argument must resolve into an object of type (struct rx packet *). An
* instance of the rx GetDataSize() macro itself resolves into an object of
* type short.
*
* \subsubsection sec5-5-1-11 Section 5.5.1.11: rx SetDataSize()
*
* \par
* \#define rx_SetDataSize(packet, size) ((packet)->length = (size))
* \par
* Assign the contents of the length field, which specifies the number of bytes
* of user data contained within the wire form of the packet, within the given
* Rx packet description structure. The value supplied as the packet argument
* must resolve into an object of type (struct rx packet *). The second
* argument, size, provides the new value of the length field, and must resolve
* into an object of type short. An instance of the rx SetDataSize() macro
* itself resolves into an object resulting from the assignment, namely the
* short length parameter.
*
* \subsubsection sec5-5-1-12 Section 5.5.1.12: rx GetPacketCksum()
*
* \par
* \#define rx_GetPacketCksum(packet) ((packet)->header.spare)
* \par
* Generate a reference to the header checksum field, as used by the built-in
* rxkad security module (See Chapter 3), within the given Rx packet
* description structure. The value supplied as the packet argument must
* resolve into an object of type (struct rx packet *). An instance of the rx
* GetPacketCksum() macro itself resolves into an object of type u short.
*
* \subsubsection sec5-5-1-13 Section 5.5.1.13: rx SetPacketCksum()
*
* \par
* \#define rx_SetPacketCksum(packet, cksum) ((packet)->header.spare = (cksum))
* \par
* Assign the contents of the header checksum field, as used by the built-in
* rxkad security module (See Chapter 3), within the given Rx packet
* description structure. The value supplied as the packet argument must
* resolve into an object of type (struct rx packet *). The second argument,
* cksum, provides the new value of the checksum, and must resolve into an
* object of type u short. An instance of the rx SetPacketCksum() macro itself
* resolves into an object resulting from the assignment, namely the u short
* checksum parameter.
*
* \subsubsection sec5-5-1-14 Section 5.5.1.14: rx GetRock()
*
* \par
* \#define rx_GetRock(obj, type) ((type)(obj)->rock)
* \par
* Generate a reference to the field named rock within the object identified by
* the obj pointer. One common Rx structure to which this macro may be applied
* is struct rx connection. The specified rock field is casted to the value of
* the type parameter, which is the overall value of the rx GetRock() macro.
*
* \subsubsection sec5-5-1-15 Section 5.5.1.15: rx SetRock()
*
* \par
* \#define rx_SetRock(obj, newrock) ((obj)->rock = (VOID *)(newrock))
* \par
* Assign the contents of the newrock parameter into the rock field of the
* object pointed to by obj. The given object's rock field must be of type
* (VOID *). An instance of the rx SetRock() macro itself resolves into an
* object resulting from the assignment and is of type (VOID *).
*
* \subsubsection sec5-5-1-16 Section 5.5.1.16: rx SecurityClassOf()
*
* \par
* \#define rx_SecurityClassOf(conn) ((conn)->securityIndex)
* \par
* Generate a reference to the security index field of the given Rx connection
* description structure. This identifies the security class used by the
* connection. The value supplied as the conn argument must resolve into an
* object of type (struct rx connection *). An instance of the rx
* SecurityClassOf() macro itself resolves into an object of type u char.
*
* \subsubsection sec5-5-1-17 Section 5.5.1.17: rx SecurityObjectOf()
*
* \par
* \#define rx_SecurityObjectOf(conn) ((conn)->securityObject)
* \par
* Generate a reference to the security object in use by the given Rx
* connection description structure. The choice of security object determines
* the authentication protocol enforced by the connection. The value supplied
* as the conn argument must resolve into an object of type (struct rx
* connection *). An instance of the rx SecurityObjectOf() macro itself
* resolves into an object of type (struct rx securityClass *).
*
* \subsection sec5-5-2 Section 5.5.2: Boolean Operations
*
* \par
* The macros described in this section all return Boolean values. They are
* used to query such things as the whether a connection is a server-side or
* client-side one and if extra levels of checksumming are being used in Rx
* packet headers.
*
* \subsubsection sec5-5-2-1 Section 5.5.2.1: rx IsServerConn()
*
* \par
* \#define rx_IsServerConn(conn) ((conn)->type == RX_SERVER_CONNECTION)
* \par
* Determine whether or not the Rx connection specified by the conn argument is
* a server-side connection. The value supplied for conn must resolve to an
* object of type struct rx connection. The result is determined by testing
* whether or not the connection's type field is set to RX SERVER CONNECTION.
* \note Another macro, rx ServerConn(), performs the identical operation.
*
* \subsubsection sec5-5-2-2 Section 5.5.2.2: rx IsClientConn()
*
* \par
* \#define rx_IsClientConn(conn) ((conn)->type == RX_CLIENT_CONNECTION)
* \par
* Determine whether or not the Rx connection specified by the conn argument is
* a client-side connection. The value supplied for conn must resolve to an
* object of type struct rx connection. The result is determined by testing
* whether or not the connection's type field is set to RX CLIENT CONNECTION.
* \note Another macro, rx ClientConn(), performs the identical operation.
*
* \subsubsection sec5-5-2-3 Section 5.5.2.2: rx IsUsingPktCksum()
*
* \par
* \#define rx_IsUsingPktCksum(conn) ((conn)->flags &
* RX_CONN_USING_PACKET_CKSUM)
* \par
* Determine whether or not the Rx connection specified by the conn argument is
* checksum-ming the headers of all packets on its calls. The value supplied
* for conn must resolve to an object of type struct rx connection. The result
* is determined by testing whether or not the connection's flags field has the
* RX CONN USING PACKET CKSUM bit enabled.
*
* \subsection sec5-5-3 Section 5.5.3: Service Attributes
*
* \par
* This section describes user-callable macros that manipulate the attributes
* of an Rx service. Note that these macros must be called (and hence their
* operations performed) before the given service is installed via the
* appropriate invocation of the associated rx StartServer() function.
*
* \subsubsection sec5-5-3-1 Section 5.5.3.1: rx SetStackSize()
*
* \par
* rx_stackSize = (((stackSize) stackSize) > rx_stackSize) ? stackSize :
* rx_stackSize)
* \par
* Inform the Rx facility of the stack size in bytes for a class of threads to
* be created in support of Rx services. The exported rx stackSize variable
* tracks the high-water mark for all stack size requests before the call to rx
* StartServer(). If no calls to rx SetStackSize() are made, then rx stackSize
* will retain its default setting of RX DEFAULT STACK SIZE.
* \par
* In this macro, the first argument is not used. It was originally intended
* that thread stack sizes would be settable on a per-service basis. However,
* calls to rx SetStackSize() will ignore the service parameter and set the
* high-water mark for all Rx threads created after the use of rx
* SetStackSize(). The second argument, stackSize, specifies determines the new
* stack size, and should resolve to an object of type int. The value placed in
* the stackSize parameter will not be recorded in the global rx stackSize
* variable unless it is greater than the variable's current setting.
* \par
* An instance of the rx SetStackSize() macro itself resolves into the result
* of the assignment, which is an object of type int.
*
* \subsubsection sec5-5-3-2 Section 5.5.3.2: rx SetMinProcs()
*
* \par
* \#define rx_SetMinProcs(service, min) ((service)->minProcs = (min))
* \par
* Choose min as the minimum number of threads guaranteed to be available for
* parallel execution of the given Rx service. The service parameter should
* resolve to an object of type struct rx service. The min parameter should
* resolve to an object of type short. An instance of the rx SetMinProcs()
* macro itself resolves into the result of the assignment, which is an object
* of type short.
*
* \subsubsection sec5-5-3-3 Section 5.5.3.3: rx SetMaxProcs()
*
* \par
* \#define rx_SetMaxProcs(service, max) ((service)->maxProcs = (max))
* \par
* Limit the maximum number of threads that may be made available to the given
* Rx service for parallel execution to be max. The service parameter should
* resolve to an object of type struct rx service. The max parameter should
* resolve to an object of type short. An instance of the rx SetMaxProcs()
* macro itself resolves into the result of the assignment, which is an object
* of type short.
*
* \subsubsection sec5-5-3-4 Section 5.5.3.4: rx SetIdleDeadTime()
*
* \par
* \#define rx_SetIdleDeadTime(service, time) ((service)->idleDeadTime =
* (time))
* \par
* Every Rx service has a maximum amount of time it is willing to have its
* active calls sit idle (i.e., no new data is read or written for a call
* marked as RX STATE ACTIVE) before unilaterally shutting down the call. The
* expired call will have its error field set to RX CALL TIMEOUT. The operative
* assumption in this situation is that the client code is exhibiting a
* protocol error that prevents progress from being made on this call, and thus
* the call's resources on the server side should be freed. The default value,
* as recorded in the service's idleDeadTime field, is set at service creation
* time to be 60 seconds. The rx SetIdleTime() macro allows a caller to
* dynamically set this idle call timeout value.
* \par
* The service parameter should resolve to an object of type struct rx service.
* Also, the time parameter should resolve to an object of type short. finally,
* an instance of the rx SetIdleDeadTime() macro itself resolves into the
* result of the assignment, which is an object of type short.
*
* \subsubsection sec5-5-3-5 Section 5.5.3.5: rx SetServiceDeadTime()
*
* \par
* \#define rx_SetServiceDeadTime(service, seconds)
* ((service)->secondsUntilDead = (seconds))
* \note This macro definition is obsolete and should NOT be used. Including it
* in application code will generate a compile-time error, since the service
* structure no longer has such a field defined.
* \par
* See the description of the rx SetConnDeadTime() macro below to see how hard
* timeouts may be set for situations of complete call inactivity.
*
* \subsubsection sec5-5-3-6 Section 5.5.3.6: rx SetRxDeadTime()
*
* \par
* \#define rx_SetRxDeadTime(seconds) (rx_connDeadTime = (seconds))
* \par
* Inform the Rx facility of the maximum number of seconds of complete
* inactivity that will be tolerated on an active call. The exported rx
* connDeadTime variable tracks this value, and is initialized to a value of 12
* seconds. The current value of rx connDeadTime will be copied into new Rx
* service and connection records upon their creation.
* \par
* The seconds argument determines the value of rx connDeadTime, and should
* resolve to an object of type int. An instance of the rx SetRxDeadTime()
* macro itself resolves into the result of the assignment, which is an object
* of type int.
*
* \subsubsection sec5-5-3-7 Section 5.5.3.7: rx SetConnDeadTime()
*
* \par
* \#define rx_SetConnDeadTime(conn, seconds) (rxi_SetConnDeadTime(conn,
* seconds))
* \par
* Every Rx connection has a maximum amount of time it is willing to have its
* active calls on a server connection sit without receiving packets of any
* kind from its peer. After such a quiescent time, during which neither data
* packets (regardless of whether they are properly sequenced or duplicates)
* nor keep-alive packets are received, the call's error field is set to RX
* CALL DEAD and the call is terminated. The operative assumption in this
* situation is that the client making the call has perished, and thus the
* call's resources on the server side should be freed. The default value, as
* recorded in the connection's secondsUntilDead field, is set at connection
* creation time to be the same as its parent service. The rx SetConnDeadTime()
* macro allows a caller to dynamically set this timeout value.
* \par
* The conn parameter should resolve to an object of type struct rx connection.
* Also, the seconds parameter should resolve to an object of type int.
* finally, an instance of the rx SetConnDeadTime() macro itself resolves into
* the a call to rxi SetConnDeadTime(), whose return value is void.
*
* \subsubsection sec5-5-3-8 Section 5.5.3.8: rx SetConnHardDeadTime()
*
* \par
* \#define rx_SetConnHardDeadTime(conn, seconds) ((conn)->hardDeadTime =
* (seconds))
* \par
* It is convenient to be able to specify that calls on certain Rx connections
* have a hard absolute timeout. This guards against protocol errors not caught
* by other checks in which one or both of the client and server are looping.
* The rx SetConnHardDeadTime() macro is available for this purpose. It will
* limit calls on the connection identified by the conn parameter to execution
* times of no more than the given number of seconds. By default, active calls
* on an Rx connection may proceed for an unbounded time, as long as they are
* not totally quiescent (see Section 5.5.3.7 for a description of the rx
* SetConnDeadTime()) or idle (see Section 5.5.3.4 for a description of the rx
* SetIdleDeadTime()).
* \par
* The conn parameter should resolve to an object of type (struct rx connection
* *). The seconds parameter should resolve to an object of type u short. An
* instance of the rx SetConnHardDeadTime() macro itself resolves into the
* result of the assignment, which is an object of type u short.
*
* \subsubsection sec5-5-3-9 Section 5.5.3.9: rx GetBeforeProc()
*
* \par
* \#define rx_GetBeforeProc(service) ((service)->beforeProc)
* \par
* Return a pointer of type (VOID *)() to the procedure associated with the
* given Rx service that will be called immediately upon activation of a server
* thread to handle an incoming call. The service parameter should resolve to
* an object of type struct rx service.
* \par
* When an Rx service is first created (via a call to the rx NewService()
* function), its beforeProc field is set to a null pointer. See the
* description of the rx SetBeforeProc() below.
*
* \subsubsection sec5-5-3-10 Section 5.5.3.10: rx SetBeforeProc()
*
* \par
* \#define rx_SetBeforeProc(service, proc) ((service)->beforeProc = (proc))
* \par
* Instruct the Rx facility to call the procedure identified by the proc
* parameter immediately upon activation of a server thread to handle an
* incoming call. The specified procedure will be called with a single
* parameter, a pointer of type struct rx call, identifying the call this
* thread will now be responsible for handling. The value returned by the
* procedure, if any, is discarded.
* \par
* The service parameter should resolve to an object of type struct rx service.
* The proc parameter should resolve to an object of type (VOID *)(). An
* instance of the rx SetBeforeProc() macro itself resolves into the result of
* the assignment, which is an object of type (VOID *)().
*
* \subsubsection sec5-5-3-11 Section 5.5.3.11: rx GetAfterProc()
*
* \par
* \#define rx_GetAfterProc(service) ((service)->afterProc)
* \par
* Return a pointer of type (VOID *)() to the procedure associated with the
* given Rx service that will be called immediately upon completion of the
* particular Rx call for which a server thread was activated. The service
* parameter should resolve to an object of type struct rx service.
* \par
* When an Rx service is first created (via a call to the rx NewService()
* function), its afterProc field is set to a null pointer. See the description
* of the rx SetAfterProc() below.
*
* \subsubsection sec5-5-3-12 Section 5.5.3.12: rx SetAfterProc()
*
* \par
* \#define rx_SetAfterProc(service, proc) ((service)->afterProc = (proc))
* \par
* Instruct the Rx facility to call the procedure identified by the proc
* parameter immediately upon completion of the particular Rx call for which a
* server thread was activated. The specified procedure will be called with a
* single parameter, a pointer of type struct rx call, identifying the call
* this thread just handled. The value returned by the procedure, if any, is
* discarded.
* \par
* The service parameter should resolve to an object of type struct rx service.
* The proc parameter should resolve to an object of type (VOID *)(). An
* instance of the rx SetAfterProc() macro itself resolves into the result of
* the assignment, which is an object of type (VOID *)().
*
* \subsubsection sec5-5-3-13 Section 5.5.3.13: rx SetNewConnProc()
*
* \par
* \#define rx_SetNewConnProc(service, proc) ((service)->newConnProc = (proc))
* \par
* Instruct the Rx facility to call the procedure identified by the proc
* parameter as the last step in the creation of a new Rx server-side
* connection for the given service. The specified procedure will be called
* with a single parameter, a pointer of type (struct rx connection *),
* identifying the connection structure that was just built. The value returned
* by the procedure, if any, is discarded.
* \par
* The service parameter should resolve to an object of type struct rx service.
* The proc parameter should resolve to an object of type (VOID *)(). An
* instance of the rx SetNewConnProc() macro itself resolves into the result of
* the assignment, which is an object of type (VOID *)().
* \note There is no access counterpart defined for this macro, namely one that
* returns the current setting of a service's newConnProc.
*
* \subsubsection sec5-5-3-14 Section 5.5.3.14: rx SetDestroyConnProc()
*
* \par
* \#define rx_SetDestroyConnProc(service, proc) ((service)->destroyConnProc =
* (proc))
* \par
* Instruct the Rx facility to call the procedure identified by the proc
* parameter just before a server connection associated with the given Rx
* service is destroyed. The specified procedure will be called with a single
* parameter, a pointer of type (struct rx connection *), identifying the
* connection about to be destroyed. The value returned by the procedure, if
* any, is discarded.
* \par
* The service parameter should resolve to an object of type struct rx service.
* The proc parameter should resolve to an object of type (VOID *)(). An
* instance of the rx SetDestroyConnProc() macro itself resolves into the
* result of the assignment, which is an object of type (VOID *)().
* \note There is no access counterpart defined for this macro, namely one that
* returns the current setting of a service's destroyConnProc.
*
* \subsection sec5-5-4 Section 5.5.4: Security-Related Operations
*
* \par
* The following macros are callable by Rx security modules, and assist in
* getting and setting header and trailer lengths, setting actual packet size,
* and finding the beginning of the security header (or data).
*
* \subsubsection sec5-5-4-1 Section 5.5.4.1: rx GetSecurityHeaderSize()
*
* \par
* \#define rx_GetSecurityHeaderSize(conn) ((conn)->securityHeaderSize)
* \par
* Generate a reference to the field in an Rx connection structure that records
* the length in bytes of the associated security module's packet header data.
* \par
* The conn parameter should resolve to an object of type struct rx connection.
* An instance of the rx GetSecurityHeaderSize() macro itself resolves into an
* object of type u short.
*
* \subsubsection sec5-5-4-2 Section 5.5.4.2: rx SetSecurityHeaderSize()
*
* \par
* \#define rx_SetSecurityHeaderSize(conn, length) ((conn)->securityHeaderSize
* = (length))
* \par
* Set the field in a connection structure that records the length in bytes of
* the associated security module's packet header data.
* \par
* The conn parameter should resolve to an object of type struct rx connection.
* The length parameter should resolve to an object of type u short. An
* instance of the rx SetSecurityHeaderSize() macro itself resolves into the
* result of the assignment, which is an object of type u short.
*
* \subsubsection sec5-5-4-3 Section 5.5.4.3: rx
* GetSecurityMaxTrailerSize()
*
* \par
* \#define rx_GetSecurityMaxTrailerSize(conn) ((conn)->securityMaxTrailerSize)
* \par
* Generate a reference to the field in an Rx connection structure that records
* the maximum length in bytes of the associated security module's packet
* trailer data.
* \par
* The conn parameter should resolve to an object of type struct rx connection.
* An instance of the rx GetSecurityMaxTrailerSize() macro itself resolves into
* an object of type u short.
*
* \subsubsection sec5-5-4-4 Section 5.5.4.4: rx
* SetSecurityMaxTrailerSize()
*
* \par
* \#define rx_SetSecurityMaxTrailerSize(conn, length)
* ((conn)->securityMaxTrailerSize = (length))
* \par
* Set the field in a connection structure that records the maximum length in
* bytes of the associated security module's packet trailer data.
* \par
* The conn parameter should resolve to an object of type struct rx connection.
* The length parameter should resolve to an object of type u short. An
* instance of the rx SetSecurityHeaderSize() macro itself resolves into the
* result of the assignment, which is an object of type u short.
*
* \subsection sec5-5-5 Section 5.5.5: Sizing Operations
*
* \par
* The macros described in this section assist the application programmer in
* determining the sizes of the various Rx packet regions, as well as their
* placement within a packet buffer.
*
* \subsubsection sec5-5-5-1 Section 5.5.5.1: rx UserDataOf()
*
* \par
* \#define rx_UserDataOf(conn, packet) (((char *) (packet)->wire.data) +
* (conn)->securityHeaderSize)
* \par
* Generate a pointer to the beginning of the actual user data in the given Rx
* packet, that is associated with the connection described by the conn
* pointer. User data appears immediately after the packet's security header
* region, whose length is determined by the security module used by the
* connection. The conn parameter should resolve to an object of type struct rx
* connection. The packet parameter should resolve to an object of type struct
* rx packet. An instance of the rx UserDataOf() macro itself resolves into an
* object of type (char *).
*
* \subsubsection sec5-5-5-2 Section 5.5.5.2: rx MaxUserDataSize()
*
* \par
* \#define rx_MaxUserDataSize(conn)
* \n ((conn)->peer->packetSize
* \n -RX_HEADER_SIZE
* \n -(conn)->securityHeaderSize
* \n -(conn)->securityMaxTrailerSize)
* \par
* Return the maximum number of user data bytes that may be carried by a packet
* on the Rx connection described by the conn pointer. The overall packet size
* is reduced by the IP, UDP, and Rx headers, as well as the header and trailer
* areas required by the connection's security module.
* \par
* The conn parameter should resolve to an object of type struct rx connection.
* An instance of the rx MaxUserDataSize() macro itself resolves into the an
* object of type (u short).
*
* \subsection sec5-5-6 Section 5.5.6: Complex Operations
*
* \par
* Two Rx macros are designed to handle potentially complex operations, namely
* reading data from an active incoming call and writing data to an active
* outgoing call. Each call structure has an internal buffer that is used to
* collect and cache data traveling through the call. This buffer is used in
* conjunction with reading or writing to the actual Rx packets traveling on
* the wire in support of the call. The rx Read() and rx Write() macros allow
* their caller to simply manipulate the internal data buffer associated with
* the Rx call structures whenever possible, thus avoiding the overhead
* associated with a function call. When buffers are either filled or drained
* (depending on the direction of the data flow), these macros will then call
* functions to handle the more complex cases of generating or receiving
* packets in support of the operation.
*
* \subsubsection sec5-5-6-1 Section 5.5.6.1: rx Read()
*
* \par
* \#define rx_Read(call, buf, nbytes)
* \n ((call)->nLeft > (nbytes) ?
* \n memcpy((buf), (call)->bufPtr, (nbytes)),
* \n (call)->nLeft -= (nbytes), (call)->bufPtr += (nbytes), (nbytes)
* \n : rx_ReadProc((call), (buf), (nbytes)))
* \par
* Read nbytes of data from the given Rx call into the buffer to which buf
* points. If the call's internal buffer has at least nbytes bytes already
* filled, then this is done in-line with a copy and some pointer and counter
* updates within the call structure. If the call's internal buffer doesn't
* have enough data to satisfy the request, then the rx ReadProc() function
* will handle this more complex situation.
* \par
* In either case, the rx Read() macro returns the number of bytes actually
* read from the call, resolving to an object of type int. If rx Read() returns
* fewer than nbytes bytes, the call status should be checked via the rx
* Error() macro.
*
* \subsubsection sec5-5-6-2 Section 5.5.6.2: rx Write()
*
* \par
* \#define rx_Write(call, buf, nbytes)
* \n ((call)->nFree > (nbytes) ?
* \n memcpy((call)->bufPtr, (buf), (nbytes)),
* \n (call)->nFree -= (nbytes),
* \n (call)->bufPtr += (nbytes), (nbytes)
* \n : rx_WriteProc((call), (buf), (nbytes)))
* \par
* Write nbytes of data from the buffer pointed to by buf into the given Rx
* call. If the call's internal buffer has at least nbytes bytes free, then
* this is done in-line with a copy and some pointer and counter updates within
* the call structure. If the call's internal buffer doesn't have room, then
* the rx WriteProc() function will handle this more complex situation.
* \par
* In either case, the rx Write() macro returns the number of bytes actually
* written to the call, resolving to an object of type int. If zero is
* returned, the call status should be checked via the rx Error() macro.
*
* \subsection sec5-5-7 Section 5.5.7: Security Operation Invocations
*
* \par
* Every Rx security module is required to implement an identically-named set
* of operations, through which the security mechanism it defines is invoked.
* This characteristic interface is reminiscent of the vnode interface defined
* and popularized for file systems by Sun Microsystems [4]. The structure
* defining this function array is described in Section 5.3.1.1.
* \par
* These security operations are part of the struct rx securityClass, which
* keeps not only the ops array itself but also any private data they require
* and a reference count. Every Rx service contains an array of these security
* class objects, specifying the range of security mechanisms it is capable of
* enforcing. Every Rx connection within a service is associated with exactly
* one of that service's security objects, and every call issued on the
* connection will execute the given security protocol.
* \par
* The macros described below facilitate the execution of the security module
* interface functions. They are covered in the same order they appear in the
* struct rx securityOps declaration.
*
* \subsubsection sec5-5-7-1 Section 5.5.7.1: RXS OP()
*
* \code
* #if defined(__STDC__) && !defined(__HIGHC__)
* #define RXS_OP(obj, op, args)
* ((obj->ops->op_ ## op) ? (*(obj)->ops->op_ ## op)args : 0)
* #else
* #define RXS_OP(obj, op, args)
* ((obj->ops->op_op) ? (*(obj)->ops->op_op)args : 0)
* #endif
* \endcode
*
* \par
* The RXS OP macro represents the workhorse macro in this group, used by all
* the others. It takes three arguments, the first of which is a pointer to the
* security object to be referenced. This obj parameter must resolve to an
* object of type (struct rx securityOps *). The second parameter identifies
* the specific op to be performed on this security object. The actual text of
* this op argument is used to name the desired opcode function. The third and
* final argument, args, specifies the text of the argument list to be fed to
* the chosen security function. Note that this argument must contain the
* bracketing parentheses for the function call's arguments. In fact, note that
* each of the security function access macros defined below provides the
* enclosing parentheses to this third RXS OP() macro.
*
* \subsubsection sec5-5-7-2 Section 5.5.7.1: RXS Close()
*
* \par
* \#define RXS_Close(obj) RXS_OP(obj, Close, (obj))
* \par
* This macro causes the execution of the interface routine occupying the op
* Close() slot in the Rx security object identified by the obj pointer. This
* interface function is invoked by Rx immediately before a security object is
* discarded. Among the responsibilities of such a function might be
* decrementing the object's refCount field, and thus perhaps freeing up any
* space contained within the security object's private storage region,
* referenced by the object's privateData field.
* \par
* The obj parameter must resolve into an object of type (struct rx securityOps
* *). In generating a call to the security object's op Close() routine, the
* obj pointer is used as its single parameter. An invocation of the RXS
* Close() macro results in a return value identical to that of the op Close()
* routine, namely a value of type int.
*
* \subsubsection sec5-5-7-3 Section 5.5.7.3: RXS NewConnection()
*
* \par
* \#define RXS_NewConnection(obj, conn) RXS_OP(obj, NewConnection, (obj,
* conn))
* \par
* This macro causes the execution of the interface routine in the op
* NewConnection() slot in the Rx security object identified by the obj
* pointer. This interface function is invoked by Rx immediately after a
* connection using the given security object is created. Among the
* responsibilities of such a function might be incrementing the object's
* refCount field, and setting any per-connection information based on the
* associated security object's private storage region, as referenced by the
* object's privateData field.
* \par
* The obj parameter must resolve into an object of type (struct rx securityOps
* *). The conn argument contains a pointer to the newly-created connection
* structure, and must resolve into an object of type (struct rx connection *).
* \par
* In generating a call to the routine located at the security object's op
* NewConnection() slot, the obj and conn pointers are used as its two
* parameters. An invocation of the RXS NewConnection() macro results in a
* return value identical to that of the op NewConnection() routine, namely a
* value of type int.
*
* \subsubsection sec5-5-7-4 Section 5.5.7.4: RXS PreparePacket()
*
* \par
* \#define RXS_PreparePacket(obj, call, packet)
* \n RXS_OP(obj, PreparePacket, (obj, call, packet))
* \par
* This macro causes the execution of the interface routine in the op
* PreparePacket() slot in the Rx security object identified by the obj
* pointer. This interface function is invoked by Rx each time it prepares an
* outward-bound packet. Among the responsibilities of such a function might be
* computing information to put into the packet's security header and/or
* trailer.
* \par
* The obj parameter must resolve into an object of type (struct rx securityOps
* *). The call argument contains a pointer to the Rx call to which the given
* packet belongs, and must resolve to an object of type (struct rx call *).
* The final argument, packet, contains a pointer to the packet itself. It
* should resolve to an object of type (struct rx packet *).
* \par
* In generating a call to the routine located at the security object's op
* PreparePacket() slot, the obj, call, and packet pointers are used as its
* three parameters. An invocation of the RXS PreparePacket() macro results in
* a return value identical to that of the op PreparePacket() routine, namely a
* value of type int.
*
* \subsubsection sec5-5-7-5 Section 5.5.7.5: RXS SendPacket()
*
* \par
* \#define RXS_SendPacket(obj, call, packet) RXS_OP(obj, SendPacket, (obj,
* call, packet))
* \par
* This macro causes the execution of the interface routine occupying the op
* SendPacket() slot in the Rx security object identified by the obj pointer.
* This interface function is invoked by Rx each time it physically transmits
* an outward-bound packet. Among the responsibilities of such a function might
* be recomputing information in the packet's security header and/or trailer.
* \par
* The obj parameter must resolve into an object of type (struct rx securityOps
* *). The call argument contains a pointer to the Rx call to which the given
* packet belongs, and must resolve to an object of type (struct rx call *).
* The final argument, packet, contains a pointer to the packet itself. It
* should resolve to an object of type (struct rx packet *).
* \par
* In generating a call to the routine located at the security object's op
* SendPacket() slot, the obj, call, and packet pointers are used as its three
* parameters. An invocation of the RXS SendPacket() macro results in a return
* value identical to that of the op SendPacket() routine, namely a value of
* type int.
*
* \subsubsection sec5-5-7-6 Section 5.5.7.6: RXS CheckAuthentication()
*
* \par
* \#define RXS_CheckAuthentication(obj, conn) RXS_OP(obj, CheckAuthentication,
* (obj, conn))
* \par
* This macro causes the execution of the interface routine in the op
* CheckAuthentication() slot in the Rx security object identified by the obj
* pointer. This interface function is invoked by Rx each time it needs to
* check whether the given connection is one on which authenticated calls are
* being performed. Specifically, a value of 0 is returned if authenticated
* calls are not being executed on this connection, and a value of 1 is
* returned if they are.
* \par
* The obj parameter must resolve into an object of type (struct rx securityOps
* *). The conn argument contains a pointer to the Rx connection checked as to
* whether authentication is being performed, and must resolve to an object of
* type (struct rx connection *).
* \par
* In generating a call to the routine in the security object's op
* CheckAuthentication() slot, the obj and conn pointers are used as its two
* parameters. An invocation of the RXS CheckAuthentication() macro results in
* a return value identical to that of the op CheckAuthentication() routine,
* namely a value of type int.
*
* \subsubsection sec5-5-7-7 Section 5.5.7.7: RXS CreateChallenge()
*
* \par
* \#define RXS_CreateChallenge(obj, conn) RXS_OP(obj, CreateChallenge, (obj,
* conn))
* \par
* This macro causes the execution of the interface routine in the op
* CreateChallenge() slot in the Rx security object identified by the obj
* pointer. This interface function is invoked by Rx each time a challenge
* event is constructed for a given connection. Among the responsibilities of
* such a function might be marking the connection as temporarily
* unauthenticated until the given challenge is successfully met.
* \par
* The obj parameter must resolve into an object of type (struct rx securityOps
* *). The conn argument contains a pointer to the Rx connection for which the
* authentication challenge is being constructed, and must resolve to an object
* of type (struct rx connection *).
* \par
* In generating a call to the routine located at the security object's op
* CreateChallenge() slot, the obj and conn pointers are used as its two
* parameters. An invocation of the RXS CreateChallenge() macro results in a
* return value identical to that of the op CreateChallenge() routine, namely a
* value of type int.
*
* \subsubsection sec5-5-7-8 Section 5.5.7.8: RXS GetChallenge()
*
* \par
* \#define RXS_GetChallenge(obj, conn, packet) RXS_OP(obj, GetChallenge, (obj,
* conn, packet))
* \par
* This macro causes the execution of the interface routine occupying the op
* GetChallenge() slot in the Rx security object identified by the obj pointer.
* This interface function is invoked by Rx each time a challenge packet is
* constructed for a given connection. Among the responsibilities of such a
* function might be constructing the appropriate challenge structures in the
* area of packet dedicated to security matters.
* \par
* The obj parameter must resolve into an object of type (struct rx securityOps
* *). The conn argument contains a pointer to the Rx connection to which the
* given challenge packet belongs, and must resolve to an object of type
* (struct rx connection *). The final argument, packet, contains a pointer to
* the challenge packet itself. It should resolve to an object of type (struct
* rx packet *).
* \par
* In generating a call to the routine located at the security object's op
* GetChallenge() slot, the obj, conn, and packet pointers are used as its
* three parameters. An invocation of the RXS GetChallenge() macro results in a
* return value identical to that of the op GetChallenge() routine, namely a
* value of type int.
*
* \subsubsection sec5-5-7-9 Section 5.5.7.9: RXS GetResponse()
*
* \par
* \#define RXS_GetResponse(obj, conn, packet) RXS_OP(obj, GetResponse, (obj,
* conn, packet))
* \par
* This macro causes the execution of the interface routine occupying the op
* GetResponse() slot in the Rx security object identified by the obj pointer.
* This interface function is invoked by Rx on the server side each time a
* response to a challenge packet must be received.
* \par
* The obj parameter must resolve into an object of type (struct rx securityOps
* *). The conn argument contains a pointer to the Rx client connection that
* must respond to the authentication challenge, and must resolve to a (struct
* rx connection *) object. The final argument, packet, contains a pointer to
* the packet to be built in response to the challenge. It should resolve to an
* object of type (struct rx packet *).
* \par
* In generating a call to the routine located at the security object's op
* GetResponse() slot, the obj, conn, and packet pointers are used as its three
* parameters. An invocation of the RXS GetResponse() macro results in a return
* value identical to that of the op GetResponse() routine, namely a value of
* type int.
*
* \subsubsection sec5-5-7-10 Section 5.5.7.10: RXS CheckResponse()
*
* \par
* \#define RXS_CheckResponse(obj, conn, packet) RXS_OP(obj, CheckResponse,
* (obj, conn, packet))
* \par
* This macro causes the execution of the interface routine in the op
* CheckResponse() slot in the Rx security object identified by the obj
* pointer. This interface function is invoked by Rx on the server side each
* time a response to a challenge packet is received for a given connection.
* The responsibilities of such a function might include verifying the
* integrity of the response, pulling out the necessary security information
* and storing that information within the affected connection, and otherwise
* updating the state of the connection.
* \par
* The obj parameter must resolve into an object of type (struct rx securityOps
* *). The conn argument contains a pointer to the Rx server connection to
* which the given challenge response is directed. This argument must resolve
* to an object of type (struct rx connection *). The final argument, packet,
* contains a pointer to the packet received in response to the challenge
* itself. It should resolve to an object of type (struct rx packet *).
* \par
* In generating a call to the routine located at the security object's op
* CheckResponse() slot, the obj, conn, and packet pointers are ued as its
* three parameters. An invocation of the RXS CheckResponse() macro results in
* a return value identical to that of the op CheckResponse() routine, namely a
* value of type int.
*
* \subsubsection sec5-5-7-11 Section 5.5.7.11: RXS CheckPacket()
*
* \par
* \#define RXS_CheckPacket(obj, call, packet) RXS_OP(obj, CheckPacket, (obj,
* call, packet))
* \par
* This macro causes the execution of the interface routine occupying the op
* CheckPacket() slot in the Rx security object identified by the obj pointer.
* This interface function is invoked by Rx each time a packet is received. The
* responsibilities of such a function might include verifying the integrity of
* given packet, detecting any unauthorized modifications or tampering.
* \par
* The obj parameter must resolve into an object of type (struct rx securityOps
* *). The conn argument contains a pointer to the Rx connection to which the
* given challenge response is directed, and must resolve to an object of type
* (struct rx connection *). The final argument, packet, contains a pointer to
* the packet received in response to the challenge itself. It should resolve
* to an object of type (struct rx packet *).
* \par
* In generating a call to the routine located at the security object's op
* CheckPacket() slot, the obj, conn, and packet pointers are used as its three
* parameters. An invocation of the RXS CheckPacket() macro results in a return
* value identical to that of the op CheckPacket() routine, namely a value of
* type int.
* \par
* Please note that any non-zero return will cause Rx to abort all calls on the
* connection. Furthermore, the connection itself will be marked as being in
* error in such a case, causing it to reject any further incoming packets.
*
* \subsubsection sec5-5-7-12 Section 5.5.7.12: RXS DestroyConnection()
*
* \par
* \#define RXS_DestroyConnection(obj, conn) RXS_OP(obj, DestroyConnection,
* (obj, conn))
* \par
* This macro causes the execution of the interface routine in the op
* DestroyConnection() slot in the Rx security object identified by the obj
* pointer. This interface function is invoked by Rx each time a connection
* employing the given security object is being destroyed. The responsibilities
* of such a function might include deleting any private data maintained by the
* security module for this connection.
* \par
* The obj parameter must resolve into an object of type (struct rx securityOps
* *). The conn argument contains a pointer to the Rx connection being reaped,
* and must resolve to a (struct rx connection *) object.
* \par
* In generating a call to the routine located at the security object's op
* DestroyConnection() slot, the obj and conn pointers are used as its two
* parameters. An invocation of the RXS DestroyConnection() macro results in a
* return value identical to that of the op DestroyConnection() routine, namely
* a value of type int.
*
* \subsubsection sec5-5-7-13 Section 5.5.7.13: RXS GetStats()
*
* \par
* \#define RXS_GetStats(obj, conn, stats) RXS_OP(obj, GetStats, (obj, conn,
* stats))
* \par
* This macro causes the execution of the interface routine in the op
* GetStats() slot in the Rx security object identified by the obj pointer.
* This interface function is invoked by Rx each time current statistics
* concerning the given security object are desired.
* \par
* The obj parameter must resolve into an object of type (struct rx securityOps
* *). The conn argument contains a pointer to the Rx connection using the
* security object to be examined, and must resolve to an object of type
* (struct rx connection *). The final argument, stats, contains a pointer to a
* region to be filled with the desired statistics. It should resolve to an
* object of type (struct rx securityObjectStats *).
* \par
* In generating a call to the routine located at the security object's op
* GetStats() slot, the obj, conn, and stats pointers are used as its three
* parameters. An invocation of the RXS GetStats() macro results in a return
* value identical to that of the op GetStats() routine, namely a value of type
* int.
*
* \section sec5-6 Section 5.6: Functions
*
* \par
* Rx exports a collection of functions that, in conjuction with the macros
* explored in Section 5.5, allows its clients to set up and export services,
* create and tear down connections to these services, and execute remote
* procedure calls along these connections.
* \par
* This paper employs two basic categorizations of these Rx routines. One set
* of functions is meant to be called directly by clients of the facility, and
* are referred to as the exported operations. The individual members of the
* second set of functions are not meant to be called directly by Rx clients,
* but rather are called by the collection of defined macros, so they must
* still be lexically visible. These indirectly-executed routines are referred
* to here as the semi-exported operations.
* \par
* All Rx routines return zero upon success. The range of error codes employed
* by Rx is defined in Section 5.2.15.
*
* \subsection sec5-6-1 Section 5.6.1: Exported Operations
*
* \subsection sec5-6-2 Section 5.6.2: rx Init _ Initialize Rx
*
* \par
* int rx Init(IN int port)
* \par Description
* Initialize the Rx facility. If a non-zero port number is provided, it
* becomes the default port number for any service installed later. If 0 is
* provided for the port, a random port will be chosen by the system. The rx
* Init() function sets up internal tables and timers, along with starting up
* the listener thread.
* \par Error Codes
* RX ADDRINUSE The port provided has already been taken.
*
* \subsection sec5-6-3 Section 5.6.3: rx NewService _ Create and install
* a new service
*
* \par
* struct rx service *rx NewService(IN u short port; IN u short serviceId; IN
* char *serviceName; IN struct rx securityClass **securityObjects; IN int
* nSecurityObjects; IN long (*serviceProc)())
* \par Description
* Create and advertise a new Rx service. A service is uniquely named by a UDP
* port number plus a non-zero 16-bit serviceId on the given host. The port
* argument may be set to zero if rx Init() was called with a non-zero port
* number, in which case that original port will be used. A serviceName must
* also be provided, to be used for identification purposes (e.g., the service
* name might be used for probing for statistics). A pointer to an array of
* nSecurityObjects security objects to be associated with the new service is
* given in . securityObjects. The service's executeRequestProc() pointer is
* set to serviceProc.
* \par
* The function returns a pointer to a descriptor for the requested Rx service.
* A null return value indicates that the new service could not be created.
* Possible reasons include:
* \li The serviceId parameter was found to be zero.
* \li A port value of zero was specified at Rx initialization time (i.e., when
* rx init() was called), requiring a non-zero value for the port parameter
* here.
* \li Another Rx service is already using serviceId.
* \li Rx has already created the maximum RX MAX SERVICES Rx services (see
* Section 5.2.1).
* \par Error Codes
* (struct rx service *) NULL The new Rx service could not be created, due to
* one of the errors listed above.
*
* \subsection sec5-6-4 Section 5.6.4: rx NewConnection _ Create a new
* connection to a given service
*
* \par
* struct rx connection *rx NewConnection( IN u long shost, IN u short sport,
* IN u short sservice, IN struct rx securityClass *securityObject, IN int
* service SecurityIndex)
* \par Description
* Create a new Rx client connection to service sservice on the host whose IP
* address is contained in shost and to that host's sport UDP port. The
* corresponding Rx service identifier is expected in sservice. The caller also
* provides a pointer to the security object to use for the connection in
* securityObject, along with that object's serviceSecurityIndex among the
* security objects associated with service sservice via a previous rx
* NewService() call (see Section 5.6.3).
* \note It is permissible to provide a null value for the securityObject
* parameter if the chosen serviceSecurityIndex is zero. This corresponds to
* the pre-defined null security object, which does not engage in authorization
* checking of any kind.
* \par Error Codes
* --- A pointer to an initialized Rx connection is always returned, unless osi
* Panic() is called due to memory allocation failure.
*
* \subsection sec5-6-5 Section 5.6.5: rx NewCall _ Start a new call on
* the given connection
*
* \par
* struct rx call *rx NewCall( IN struct rx connection *conn)
* \par Description
* Start a new Rx remote procedure call on the connection specified by the conn
* parameter. The existing call structures (up to RX MAXCALLS of them) are
* examined in order. The first non-active call encountered (i.e., either
* unused or whose call->state is RX STATE DALLY) will be appropriated and
* reset if necessary. If all call structures are in active use, the RX CONN
* MAKECALL WAITING flag is set in the conn->flags field, and the thread
* handling this request will sleep until a call structure comes free. Once a
* call structure has been reserved, the keep-alive protocol is enabled for it.
* \par
* The state of the given connection determines the detailed behavior of the
* function. The conn->timeout field specifies the absolute upper limit of the
* number of seconds this particular call may be in operation. After this time
* interval, calls to such routines as rx SendData() or rx ReadData() will fail
* with an RX CALL TIMEOUT indication.
* \par Error Codes
* --- A pointer to an initialized Rx call is always returned, unless osi
* Panic() is called due to memory allocation failure.
*
* \subsection sec5-6-6 Section 5.6.6: rx EndCall _ Terminate the given
* call
*
* \par
* int rx EndCall(
* \param IN struct rx call *call,
* \param IN long rc
* \n )
* \par Description
* Indicate that the Rx call described by the structure located at call is
* finished, possibly prematurely. The value passed in the rc parameter is
* returned to the peer, if appropriate. The final error code from processing
* the call will be returned as rx EndCall()'s value. The given call's state
* will be set to RX STATE DALLY, and threads waiting to establish a new call
* on this connection are signalled (see the description of the rx NewCall() in
* Section 5.6.5).
* \par Error Codes
* -1 Unspecified error has occurred.
*
* \subsection sec5-6-7 Section 5.6.7: rx StartServer _ Activate installed
* rx service(s)
*
* \par
* void rx StartServer( IN int donateMe)
* \par Description
* This function starts server threads in support of the Rx services installed
* via calls to rx NewService() (see Section 5.6.3). This routine first
* computes the number of server threads it must create, governed by the
* minProcs and maxProcs fields in the installed service descriptors. The
* minProcs field specifies the minimum number of threads that are guaranteed
* to be concurrently available to the given service. The maxProcs field
* specifies the maximum number of threads that may ever be concurrently
* assigned to the particular service, if idle threads are available. Using
* this information, rx StartServer() computes the correct overall number of
* threads as follows: For each installed service, minProcs threads will be
* created, enforcing the minimality guarantee. Calculate the maximum
* difference between the maxProcs and minProcs fields for each service, and
* create this many additional server threads, enforcing the maximality
* guarantee.
* \par
* If the value placed in the donateMe argument is zero, then rx StartServer()
* will simply return after performing as described above. Otherwise, the
* thread making the rx StartServer() call will itself begin executing the
* server thread loop. In this case, the rx StartServer() call will never
* return.
* \par Error Codes
* ---None.
*
* \subsection sec5-6-8 Section 5.6.8: rx PrintStats -- Print basic
* statistics to a file
*
* \par
* void rx PrintStats( IN FILE *file)
* \par Description
* Prints Rx statistics (basically the contents of the struct rx stats holding
* the statistics for the Rx facility) to the open file descriptor identified
* by file. The output is ASCII text, and is intended for human consumption.
* \note This function is available only if the Rx package has been compiled
* with the RXDEBUG flag.
* \par Error Codes
* ---None.
*
* \subsection sec5-6-9 Section 5.6.9: rx PrintPeerStats _ Print peer
* statistics to a file
* \par
* void rx PrintPeerStats( IN FILE *file, IN struct rx peer *peer)
* \par Description
* Prints the Rx peer statistics found in peer to the open file descriptor
* identified by file. The output is in normal ASCII text, and is intended for
* human consumption.
* \note This function is available only if the Rx package has been compiled
* with the RXDEBUG flag.
* \par Error Codes
* ---None.
*
* \subsection sec5-6-10 Section 5.6.10: rx finalize _ Shut down Rx
* gracefully
*
* \par
* void rx finalize()
* \par Description
* This routine may be used to shut down the Rx facility for either server or
* client applications. All of the client connections will be gracefully
* garbage-collected after their active calls are cleaned up. The result of
* calling rx finalize() from a client program is that the server-side entity
* will be explicitly advised that the client has terminated. This notification
* frees the server-side application from having to probe the client until its
* records eventually time out, and also allows it to free resources currently
* assigned to that client's support.
* \par Error Codes
* ---None.
*
* \subsection sec5-6-11 Section 5.6.11: Semi-Exported Operations
*
* \par
* As described in the introductory text in Section 5.6, entries in this
* lexically-visible set of Rx functions are not meant to be called directly by
* client applications, but rather are invoked by Rx macros called by users.
*
* \subsection sec5-6-12 Section 5.6.12: rx WriteProc _ Write data to an
* outgoing call
*
* \par
* int rx WriteProc( IN struct rx call *call, IN char *buf, IN int nbytes)
* \par Description
* Write nbytes of data from buffer buf into the Rx call identified by the call
* parameter. The value returned by rx WriteProc() reports the number of bytes
* actually written into the call. If zero is returned, then the rx Error()
* macro may be used to obtain the call status.
* \par
* This routine is called by the rx Write() macro, which is why it must be
* exported by the Rx facility.
* \par Error Codes
* Indicates error in the given Rx call; use the rx Error() macro to determine
* the call status.
*
* \subsection sec5-6-13 Section 5.6.13: rx ReadProc _ Read data from an
* incoming call
*
* \par
* int rx ReadProc( IN struct rx call *call, IN char *buf, IN int nbytes)
* \par Description
* Read up to nbytes of data from the Rx call identified by the call parameter
* into the buf buffer. The value returned by rx ReadProc() reports the number
* of bytes actually read from the call. If zero is returned, then the rx
* Error() macro may be used to obtain the call status.
* \par
* This routine is called by the rx Read() macro, which is why it must be
* exported by the Rx facility.
* \par Error Codes
* Indicates error in the given Rx call; use the rx Error() macro to determine
* the call status.
*
* \subsection sec5-6-1 Section 5.6.1: rx FlushWrite -- Flush buffered
* data on outgoing call
*
* \par
* void rx FlushWrite( IN struct rx call *call)
* \par Description
* Flush any buffered data on the given Rx call to the stream. If the call is
* taking place on a server connection, the call->mode is set to RX MODE EOF.
* If the call is taking place on a client connection, the call->mode is set to
* RX MODE RECEIVING.
* \par Error Codes
* ---None.
*
* \subsection sec5-6-15 Section 5.6.15: rx SetArrivalProc _ Set function
* to invoke upon call packet arrival
*
* \par
* void rx SetArrivalProc( IN struct rx call *call, IN VOID (*proc)(), IN VOID
* *handle, IN VOID *arg)
* \par Description
* Establish a procedure to be called when a packet arrives for a call. This
* routine will be called at most once after each call, and will also be called
* if there is an error condition on the call or the call is complete. The rx
* SetArrivalProc() function is used by multicast Rx routines to build a
* selection function that determines which of several calls is likely to be a
* good one to read from. The implementor's comments in the Rx code state that,
* due to the current implementation, it is probably only reasonable to use rx
* SetArrivalProc() immediately after an rx NewCall(), and to only use it once.
* \par Error Codes
* ---None.
*
* \page chap6 Chapter 6 -- Example Server and Client
*
* \section sec6-1 Section 6.1: Introduction
*
* \par
* This chapter provides a sample program showing the use of Rx. Specifically,
* the rxdemo application, with all its support files, is documented and
* examined. The goal is to provide the reader with a fully-developed and
* operational program illustrating the use of both regular Rx remote procedure
* calls and streamed RPCs. The full text of the rxdemo application is
* reproduced in the sections below, along with additional commentary.
* \par
* Readers wishing to directly experiment with this example Rx application are
* encouraged to examine the on-line version of rxdemo. Since it is a program
* of general interest, it has been installed in the usr/contrib tree in the
* grand.central.org cell. This area contains user-contributed software for the
* entire AFS community. At the top of this tree is the
* /afs/grand.central.org/darpa/usr/contrib directory. Both the server-side and
* client-side rxdemo binaries (rxdemo server and rxdemo client, respectively)
* may be found in the bin subdirectory. The actual sources reside in the
* .site/grand.central.org/rxdemo/src subdirectory.
* \par
* The rxdemo code is composed of two classes of files, namely those written by
* a human programmer and those generated from the human-written code by the
* Rxgen tool. Included in the first group of files are:
* \li rxdemo.xg This is the RPC interface definition file, providing
* high-level definitions of the supported calls.
* \li rxdemo client.c: This is the rxdemo client program, calling upon the
* associated server to perform operations defined by rxdemo.xg.
* \li rxdemo server.c: This is the rxdemo server program, implementing the
* operations promised in rxdemo.xg.
* \li Makefile: This is the file that directs the compilation and
* installation of the rxdemo code.
* \par
* The class of automatically-generated files includes the following items:
* \li rxdemo.h: This header file contains the set of constant definitions
* present in rxdemo.xg, along with information on the RPC opcodes defined for
* this Rx service.
* \li rxdemo.cs.c: This client-side stub file performs all the marshalling and
* unmarshalling of the arguments for the RPC routines defined in rxdemo.xg.
* \li rxdemo.ss.c: This stub file similarly defines all the marshalling and
* unmarshalling of arguments for the server side of the RPCs, invokes the
* routines defined within rxdemo server.c to implement the calls, and also
* provides the dispatcher function.
* \li rxdemo.xdr.c: This module defines the routines required to convert
* complex user-defined data structures appearing as arguments to the Rx RPC
* calls exported by rxdemo.xg into network byte order, so that correct
* communication is guaranteed between clients and server with different memory
* organizations.
* \par
* The chapter concludes with a section containing sample output from running
* the rxdemo server and client programs.
*
* \section sec6-2 Section 6.2: Human-Generated files
*
* \par
* The rxdemo application is based on the four human-authored files described
* in this section. They provide the basis for the construction of the full set
* of modules needed to implement the specified Rx service.
*
* \subsection sec6-2-1 Section 6.2.1: Interface file: rxdemo.xg
*
* \par
* This file serves as the RPC interface definition file for this application.
* It defines various constants, including the Rx service port to use and the
* index of the null security object (no encryption is used by rxdemo). It
* defines the RXDEMO MAX and RXDEMO MIN constants, which will be used by the
* server as the upper and lower bounds on the number of Rx listener threads to
* run. It also defines the set of error codes exported by this facility.
* finally, it provides the RPC function declarations, namely Add() and
* Getfile(). Note that when building the actual function definitions, Rxgen
* will prepend the value of the package line in this file, namely "RXDEMO ",
* to the function declarations. Thus, the generated functions become RXDEMO
* Add() and RXDEMO Getfile(), respectively. Note the use of the split keyword
* in the RXDEMO Getfile() declaration, which specifies that this is a streamed
* call, and actually generates two client-side stub routines (see Section
* 6.3.1).
*
* \code
* /*=======================================================================
* * Interface for an example Rx server/client application, using both * *
* standard and streamed calls. * ** * Edward R. Zayas * * Transarc
* Corporation * ** ** * The United States Government has rights in this
* work pursuant * * to contract no. MDA972-90-C-0036 between the United
* States Defense * * Advanced Research Projects Agency and Transarc
* Corporation. * ** * (C) Copyright 1991 Transarc Corporation * ** *
* Redistribution and use in source and binary forms are permitted *
* provided that: (1) source distributions retain this entire copy- * *
* right notice and comment, and (2) distributions including binaries * *
* display the following acknowledgement: * ** * ''This product includes
* software developed by Transarc * * Corporation and its contributors'' *
* ** * in the documentation or other materials mentioning features or * *
* use of this software. Neither the name of Transarc nor the names * * of
* its contributors may be used to endorse or promote products * * derived
* from this software without specific prior written * * permission. * **
* * THIS SOFTWARE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED *
* * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF *
* * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
* =======================================================================*/
*
* package RXDEMO_
* %#include <rx/rx.h>
* %#include <rx/rx_null.h>
* %#define RXDEMO_SERVER_PORT 8000 /* Service port to advertise */
* %#define RXDEMO_SERVICE_PORT 0 /* User server's port */
* %#define RXDEMO_SERVICE_ID 4 /* Service ID */
* %#define RXDEMO_NULL_SECOBJ_IDX 0 /* Index of null security object */
*
* /* Maximum number of requests that will be handled by this service
* * simultaneously. This number will be guaranteed to execute in
* * parallel if other service's results are being processed. */
*
* %#define RXDEMO_MAX 3
*
* /* Minimum number of requests that are guaranteed to be
* * handled simultaneously. */
*
* %#define RXDEMO_MIN 2
*
* /* Index of the "null" security class in the sample service. */
*
* %#define RXDEMO_NULL 0
*
* /* Maximum number of characters in a file name (for demo purposes). */
*
* %#define RXDEMO_NAME_MAX_CHARS 64
*
* /* Define the max number of bytes to transfer at one shot. */
*
* %#define RXDEMO_BUFF_BYTES 512
*
* /* Values returned by the RXDEMO_Getfile() call.
* * RXDEMO_CODE_SUCCESS : Everything went fine.
* * RXDEMO_CODE_CANT_OPEN : Can't open named file.
* * RXDEMO_CODE_CANT_STAT : Can't stat open file.
* * RXDEMO_CODE_CANT_READ : Error reading the open file.
* * RXDEMO_CODE_WRITE_ERROR : Error writing the open file. */
*
* /* ------------Interface calls defined for this service ----------- */
* %#define RXDEMO_CODE_SUCCESS 0
* %#define RXDEMO_CODE_CANT_OPEN 1
* %#define RXDEMO_CODE_CANT_STAT 2
* %#define RXDEMO_CODE_CANT_READ 3
* %#define RXDEMO_CODE_WRITE_ERROR 4
* /* -------------------------------------------------------------------
* * RXDEMO_Add *
* *
* * Summary:
* * Add the two numbers provided and return the result. *
* * Parameters:
* * int a_first : first operand.
* * int a_second : Second operand.
* * int *a_result : Sum of the above. *
* * Side effects: None.
* *-------------------------------------------------------------------- */
*
* Add(IN int a, int b, OUT int *result) = 1;
* /*-------------------------------------------------------------------
* * RXDEMO_Getfile *
* * Summary:
* * Return the contents of the named file in the server's environment.
* * Parameters:
* * STRING a_nameToRead : Name of the file whose contents are to be
* * fetched.
* * int *a_result : Set to the result of opening and reading the file
* * on the server side. *
* * Side effects: None.
* *-------------------------------------------------------------------- */
*
* Getfile(IN string a_nameToRead<RXDEMO_NAME_MAX_CHARS>, OUT int *a_result)
* split = 2;
* \endcode
*
* \subsection sec6-2-2 Section 6.2.2: Client Program: rxdemo client.c
*
* \par
* The rxdemo client program, rxdemo client, calls upon the associated server
* to perform operations defined by rxdemo.xg. After its header, it defines a
* private GetIPAddress() utility routine, which given a character string host
* name will return its IP address.
*
* \code
* /*=======================================================================
* % Client side of an example Rx application, using both standard and % %
* streamed calls. % %% % Edward R. Zayas % % Transarc Corporation % %%
* %% % The United States Government has rights in this work pursuant % %
* to contract no. MDA972-90-C-0036 between the United States Defense % %
* Advanced Research Projects Agency and Transarc Corporation. % %% % (C)
* Copyright 1991 Transarc Corporation % %% % Redistribution and use in source
* and binary forms are permitted % % provided that: (1) source distributions
* retain this entire copy- % % right notice and comment, and (2) distributions
* including binaries % % display the following acknowledgement: % %% %
* ''This product includes software developed by Transarc % % Corporation and
* its contributors'' % %% % in the documentation or other materials mentioning
* features or % % use of this software. Neither the name of Transarc nor the
* names % % of its contributors may be used to endorse or promote products % %
* derived from this software without specific prior written % % permission.
* % %% % THIS SOFTWARE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED
* % % WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF % %
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
* % %=======================================================================
* */
*
* #include <sys/types.h>
* #include <netdb.h>
* #include <stdio.h>
* #include "rxdemo.h"
* static char pn[] = "rxdemo"; /* Program name */
* static u_long GetIpAddress(a_hostName) char *a_hostName;
* { /* GetIPAddress */
* static char rn[] = "GetIPAddress"; /* Routine name */
* struct hostent *hostEntP; /* Ptr to host descriptor */
* u_long hostIPAddr; /* Host IP address */
* hostEntP = gethostbyname(a_hostName);
* if (hostEntP == (struct hostent *)0) {
* printf("[%s:%s] Host '%s' not found\n",
* pn, rn, a_hostName);
* exit(1);
* }
* if (hostEntP->h_length != sizeof(u_long)) {
* printf("[%s:%s] Wrong host address length (%d bytes instead of
* %d)",
* pn, rn, hostEntP->h_length, sizeof(u_long));
* exit(1);
* }
* memcpy(&hostIPAddr, hostEntP->h_addr, sizeof(hostIPAddr));
* return(hostIPAddr);
* } /* GetIpAddress */
* \endcode
*
* \par
* The main program section of the client code, after handling its command line
* arguments, starts off by initializing the Rx facility.
*
* \code
* main(argc, argv)
* int argc;
* char **argv;
* { /* Main */
* struct rx_connection *rxConnP; /* Ptr to server connection */
* struct rx_call *rxCallP; /* Ptr to Rx call descriptor */
* u_long hostIPAddr; /* IP address of chosen host */
* int demoUDPPort; /* UDP port of Rx service */
* struct rx_securityClass *nullSecObjP; /* Ptr to null security object */
* int operand1, operand2; /* Numbers to add int sum; Their sum */
* int code; /* Return code */
* char fileName[64]; /* Buffer for desired file's name */
* long fileDataBytes; /* Num bytes in file to get */
* char buff[RXDEMO_BUFF_BYTES+1]; /* Read buffer */
* int currBytesToRead; /* Num bytes to read in one iteration */
* int maxBytesToRead; /* Max bytes to read in one iteration */
* int bytesReallyRead; /* Num bytes read off Rx stream */
* int getResults; /* Results of the file fetch */
* printf("\n%s: Example Rx client process\n\n", pn);
* if ((argc < 2) || (argc > 3)) {
* printf("Usage: rxdemo <HostName> [PortToUse]");
* exit(1);
* }
* hostIPAddr = GetIpAddress(argv[1]);
* if (argc > 2)
* demoUDPPort = atoi(argv[2]);
* else
* demoUDPPort = RXDEMO_SERVER_PORT;
* /* Initialize the Rx facility. */
* code = rx_Init(htons(demoUDPPort));
* if (code) {
* printf("** Error calling rx_Init(); code is %d\n", code);
* exit(1);
* }
* /* Create a client-side null security object. */
* nullSecObjP = rxnull_NewClientSecurityObject();
* if (nullSecObjP == (struct rx_securityClass *)0) {
* printf("%s: Can't create a null client-side security
* object!\n", pn);
* exit(1);
* }
* /* Set up a connection to the desired Rx service, telling it to use
* * the null security object we just created. */
* printf("Connecting to Rx server on '%s', IP address 0x%x, UDP port
* %d\n", argv[1], hostIPAddr, demoUDPPort);
* rxConnP = rx_NewConnection(hostIPAddr, RXDEMO_SERVER_PORT,
* RXDEMO_SERVICE_ID, nullSecObjP, RXDEMO_NULL_SECOBJ_IDX);
* if (rxConnP == (struct rx_connection *)0) {
* printf("rxdemo: Can't create connection to server!\n");
* exit(1);
* } else
* printf(" ---> Connected.\n");
* \endcode
*
* \par
* The rx Init() invocation initializes the Rx library and defines the desired
* service UDP port (in network byte order). The rxnull
* NewClientSecurityObject() call creates a client-side Rx security object that
* does not perform any authentication on Rx calls. Once a client
* authentication object is in hand, the program calls rx NewConnection(),
* specifying the host, UDP port, Rx service ID, and security information
* needed to establish contact with the rxdemo server entity that will be
* providing the service.
* \par
* With the Rx connection in place, the program may perform RPCs. The first one
* to be invoked is RXDEMO Add():
*
* \code
* /* Perform our first, simple remote procedure call. */
* operand1 = 1;
* operand2 = 2;
* printf("Asking server to add %d and %d: ", operand1, operand2);
* code = RXDEMO_Add(rxConnP, operand1, operand2, &sum);
* if (code) {
* printf(" // ** Error in the RXDEMO_Add RPC: code is %d\n", code);
* exit(1);
* }
* printf("Reported sum is %d\n", sum);
* \endcode
*
* \par
* The first argument to RXDEMO Add() is a pointer to the Rx connection
* established above. The client-side body of the RXDEMO Add() function was
* generated from the rxdemo.xg interface file, and resides in the rxdemo.cs.c
* file (see Section 6.3.1). It gives the appearance of being a normal C
* procedure call.
* \par
* The second RPC invocation involves the more complex, streamed RXDEMO
* Getfile() function. More of the internal Rx workings are exposed in this
* type of call. The first additional detail to consider is that we must
* manually create a new Rx call on the connection.
*
* \code
* /* Set up for our second, streamed procedure call. */
* printf("Name of file to read from server: ");
* scanf("%s", fileName);
* maxBytesToRead = RXDEMO_BUFF_BYTES;
* printf("Setting up an Rx call for RXDEMO_Getfile...");
* rxCallP = rx_NewCall(rxConnP);
* if (rxCallP == (struct rx_call *)0) {
* printf("** Can't create call\n");
* exit(1);
* }
* printf("done\n");
* \endcode
*
* \par
* Once the Rx call structure has been created, we may begin executing the call
* itself. Having been declared to be split in the interface file, Rxgen
* creates two function bodies for rxdemo Getfile() and places them in
* rxdemo.cs.c. The first, StartRXDEMO Getfile(), is responsible for
* marshalling the outgoing arguments and issuing the RPC. The second,
* EndRXDEMO Getfile(), takes care of unmarshalling the non-streamed OUT
* function parameters. The following code fragment illustrates how the RPC is
* started, using the StartRXDEMO Getfile() routine to pass the call parameters
* to the server.
*
* \code
* /* Sending IN parameters for the streamed call. */
* code = StartRXDEMO_Getfile(rxCallP, fileName);
* if (code) {
* printf("** Error calling StartRXDEMO_Getfile(); code is %d\n",
* code);
* exit(1);
* }
* \endcode
*
* \par
* Once the call parameters have been shipped, the server will commence
* delivering the "stream" data bytes back to the client on the given Rx call
* structure. The first longword to come back on the stream specifies the
* number of bytes to follow.
*
* \par
* Begin reading the data being shipped from the server in response to * our
* setup call. The first longword coming back on the Rx call is
* the number of bytes to follow. It appears in network byte order,
* so we have to fix it up before referring to it.
*
* \code
* bytesReallyRead = rx_Read(rxCallP, &fileDataBytes, sizeof(long));
* if (bytesReallyRead != sizeof(long)) {
* printf("** Only %d bytes read for file length; should have been %d\n",
* bytesReallyRead, sizeof(long));
* exit(1);
* }
* fileDataBytes = ntohl(fileDataBytes);
* \endcode
*
* \par
* Once the client knows how many bytes will be sent, it runs a loop in which
* it reads a buffer at a time from the Rx call stream, using rx Read() to
* accomplish this. In this application, all that is done with each
* newly-acquired buffer of information is printing it out.
*
* \code
* /* Read the file bytes via the Rx call, a buffer at a time. */
* printf("[file contents (%d bytes) fetched over the Rx call appear
* below]\n\n", fileDataBytes);
* while (fileDataBytes > 0)
* {
* currBytesToRead = (fileDataBytes > maxBytesToRead ? maxBytesToRead :
* fileDataBytes);
* bytesReallyRead = rx_Read(rxCallP, buff, currBytesToRead);
* if (bytesReallyRead != currBytesToRead)
* {
* printf("\nExpecting %d bytes on this read, got %d instead\n",
* currBytesToRead, bytesReallyRead);
* exit(1);
* }
* /* Null-terminate the chunk before printing it. */
* buff[currBytesToRead] = 0;
* printf("%s", buff);
* /* Adjust the number of bytes left to read. */
* fileDataBytes -= currBytesToRead;
* } /* Read one bufferful of the file */
* \endcode
*
* \par
* After this loop terminates, the Rx stream has been drained of all data. The
* Rx call is concluded by invoking the second of the two
* automatically-generated functions, EndRXDEMO Getfile(), which retrieves the
* call's OUT parameter from the server.
*
* \code
* /* finish off the Rx call, getting the OUT parameters. */
* printf("\n\n[End of file data]\n");
* code = EndRXDEMO_Getfile(rxCallP, &getResults);
* if (code)
* {
* printf("** Error getting file transfer results; code is %d\n",
* code);
* exit(1);
* }
* \endcode
*
* \par
* With both normal and streamed Rx calls accomplished, the client demo code
* concludes by terminating the Rx call it set up earlier. With that done, the
* client exits.
*
* \code
* /* finish off the Rx call. */
* code = rx_EndCall(rxCallP, code);
* if (code)
* printf("Error in calling rx_EndCall(); code is %d\n", code);
*
* printf("\n\nrxdemo complete.\n");
* \endcode
*
* \subsection sec6-2-3 Server Program: rxdemo server.c
*
* \par
* The rxdemo server program, rxdemo server, implements the operations promised
* in the rxdemo.xg interface file.
* \par
* After the initial header, the external function RXDEMO ExecuteRequest() is
* declared. The RXDEMO ExecuteRequest() function is generated automatically by
* rxgen from the interface file and deposited in rxdemo.ss.c. The main program
* listed below will associate this RXDEMO ExecuteRequest() routine with the Rx
* service to be instantiated.
*
* \code
* /*======================================================================
* % % Advanced Research Projects Agency and Transarc Corporation. % %% %
* (C) Copyright 1991 Transarc Corporation % %% % Redistribution and use in
* source and binary forms are permitted % % provided that: (1) source
* distributions retain this entire copy- % % right notice and comment, and
* (2) distributions including binaries % % display the following
* acknowledgement: % %% % ''This product includes software developed by
* Transarc % % Corporation and its contributors'' % %% % in the documentation
* or other materials mentioning features or % % use of this software. Neither
* the name of Transarc nor the names % % of its contributors may be used to
* endorse or promote products % % derived from this software without specific
* prior written % % permission. % %% % THIS SOFTWARE IS PROVIDED "AS IS" AND
* WITHOUT ANY EXPRESS OR IMPLIED % % WARRANTIES, INCLUDING, WITHOUT
* LIMITATION,
* THE IMPLIED WARRANTIES OF % % MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE. % %
* ====================================================================== */
*
* /* Server portion of the example RXDEMO application, using both %
* standard and streamed calls. % % Edward R. Zayas % Transarc Corporation %
* % % The United States Government has rights in this work pursuant %
* to contract no. MDA972-90-C-0036 between the United States Defense % */
*
* #include <sys/types.h>
* #include <sys/stat.h>
* #include <sys/file.h>
* #include <netdb.h>
* #include <stdio.h>
* #include "rxdemo.h"
* #define N_SECURITY_OBJECTS 1
* extern RXDEMO_ExecuteRequest();
* \endcode
*
* \par
* After choosing either the default or user-specified UDP port on which the Rx
* service will be established, rx Init() is called to set up the library.
*
* \code
* main(argc, argv)
* int argc;
* char **argv;
* { /* Main */
* static char pn[] = "rxdemo_server"; /* Program name */
* struct rx_securityClass
* (securityObjects[1]); /* Security objs */
* struct rx_service *rxServiceP; /* Ptr to Rx service descriptor */
* struct rx_call *rxCallP; /* Ptr to Rx call descriptor */
* int demoUDPPort; /* UDP port of Rx service */
* int fd; /* file descriptor */
* int code; /* Return code */
* printf("\n%s: Example Rx server process\n\n", pn);
* if (argc >2) {
* printf("Usage: rxdemo [PortToUse]");
* exit(1);
* }
* if (argc > 1)
* demoUDPPort = atoi(argv[1]);
* else
* demoUDPPort = RXDEMO_SERVER_PORT;
*
* /* Initialize the Rx facility, telling it the UDP port number this
* * server will use for its single service. */
*
* printf("Listening on UDP port %d\n", demoUDPPort);
* code = rx_Init(demoUDPPort);
* if (code) {
* printf("** Error calling rx_Init(); code is %d\n", code);
* exit(1);
* }
* \endcode
*
* \par
* A security object specific to the server side of an Rx conversation is
* created in the next code fragment. As with the client side of the code, a
* "null" server security object, namely one that does not perform any
* authentication at all, is constructed with the rxnull
* NewServerSecurityObject() function.
*
* \code
* /* Create a single server-side security object. In this case, the
* * null security object (for unauthenticated connections) will be used
* * to control security on connections made to this server. */
*
* securityObjects[RXDEMO_NULL_SECOBJ_IDX] =
* rxnull_NewServerSecurityObject();
* if (securityObjects[RXDEMO_NULL_SECOBJ_IDX] == (struct rx_securityClass
* *) 0) {
* printf("** Can't create server-side security object\n");
* exit(1);
* }
* \endcode
*
* \par
* The rxdemo server program is now in a position to create the desired Rx
* service, primed to recognize exactly those interface calls defined in
* rxdemo.xg. This is accomplished by calling the rx NewService() library
* routine, passing it the security object created above and the generated Rx
* dispatcher routine.
*
* \code
* /* Instantiate a single sample service. The rxgen-generated procedure
* * called to dispatch requests is passed in (RXDEMO_ExecuteRequest). */
*
* rxServiceP = rx_NewService( 0,
* RXDEMO_SERVICE_ID,
* "rxdemo",
* securityObjects,
* 1,
* RXDEMO_ExecuteRequest
* );
* if (rxServiceP == (struct rx_service *) 0) {
* printf("** Can't create Rx service\n");
* exit(1);
* }
* \endcode
*
* \par
* The final step in this main routine is to activate servicing of calls to the
* exported Rx interface. Specifically, the proper number of threads are
* created to handle incoming interface calls. Since we are passing a non-zero
* argument to the rx StartServer() call, the main program will itself begin
* executing the server thread loop, never returning from the rx StartServer()
* call. The print statement afterwards should never be executed, and its
* presence represents some level of paranoia, useful for debugging
* malfunctioning thread packages.
*
* \code
* /* Start up Rx services, donating this thread to the server pool. */
* rx_StartServer(1);
* /* We should never return from the previous call. */
* printf("** rx_StartServer() returned!!\n"); exit(1);
* } /* Main */
* \endcode
*
* \par
* Following the main procedure are the functions called by the
* automatically-generated routines in the rxdemo.ss.c module to implement the
* specific routines defined in the Rx interface.
* \par
* The first to be defined is the RXDEMO Add() function. The arguments for this
* routine are exactly as they appear in the interface definition, with the
* exception of the very first. The a rxCallP parameter is a pointer to the Rx
* structure describing the call on which this function was activated. All
* user-supplied routines implementing an interface function are required to
* have a pointer to this structure as their first parameter. Other than
* printing out the fact that it has been called and which operands it
* received, all that RXDEMO Add() does is compute the sum and place it in the
* output parameter.
* \par
* Since RXDEMO Add() is a non-streamed function, with all data travelling
* through the set of parameters, this is all that needs to be done. To mark a
* successful completion, RXDEMO Add() returns zero, which is passed all the
* way through to the RPC's client.
*
* \code
* int RXDEMO_Add(a_rxCallP, a_operand1, a_operand2, a_resultP)
* struct rx_call *a_rxCallP;
* int a_operand1, a_operand2;
* int *a_resultP;
* { /* RXDEMO_Add */
* printf("\t[Handling call to RXDEMO_Add(%d, %d)]\n",
* a_operand1, a_operand2);
* *a_resultP = a_operand1 + a_operand2;
* return(0);
* } /* RXDEMO_Add */
* \endcode
*
* \par
* The next and final interface routine defined in this file is RXDEMO
* Getfile(). Declared as a split function in the interface file, RXDEMO
* Getfile() is an example of a streamed Rx call. As with RXDEMO Add(), the
* initial parameter is required to be a pointer to the Rx call structure with
* which this routine is associated, Similarly, the other parameters appear
* exactly as in the interface definition, and are handled identically.
* \par
* The difference between RXDEMO Add() and RXDEMO Getfile() is in the use of
* the rx Write() library routine by RXDEMO Getfile() to feed the desired
* file's data directly into the Rx call stream. This is an example of the use
* of the a rxCallP argument, providing all the information necessary to
* support the rx Write() activity.
* \par
* The RXDEMO Getfile() function begins by printing out the fact that it's been
* called and the name of the requested file. It will then attempt to open the
* requested file and stat it to determine its size.
*
* \code
* int RXDEMO_Getfile(a_rxCallP, a_nameToRead, a_resultP)
* struct rx_call *a_rxCallP;
* char *a_nameToRead;
* int *a_resultP;
* { /* RXDEMO_Getfile */
* struct stat fileStat; /* Stat structure for file */
* long fileBytes; /* Size of file in bytes */
* long nbofileBytes; /* file bytes in network byte order */
* int code; /* Return code */
* int bytesReallyWritten; /* Bytes written on Rx channel */
* int bytesToSend; /* Num bytes to read & send this time */
* int maxBytesToSend; /* Max num bytes to read & send ever */
* int bytesRead; /* Num bytes read from file */
* char buff[RXDEMO_BUFF_BYTES+1]; /* Read buffer */
* int fd; /* file descriptor */
* maxBytesToSend = RXDEMO_BUFF_BYTES;
* printf("\t[Handling call to RXDEMO_Getfile(%s)]\n", a_nameToRead);
* fd = open(a_nameToRead, O_RDONLY, 0444);
* if (fd <0) {
* printf("\t\t[**Can't open file '%s']\n", a_nameToRead);
* *a_resultP = RXDEMO_CODE_CANT_OPEN;
* return(1);
* } else
* printf("\t\t[file opened]\n");
* /* Stat the file to find out how big it is. */
* code = fstat(fd, &fileStat);
* if (code) {
* a_resultP = RXDEMO_CODE_CANT_STAT;
* printf("\t\t[file closed]\n");
* close(fd);
* return(1);
* }
* fileBytes = fileStat.st_size;
* printf("\t\t[file has %d bytes]\n", fileBytes);
* \endcode
*
* \par
* Only standard unix operations have been used so far. Now that the file is
* open, we must first feed the size of the file, in bytes, to the Rx call
* stream. With this information, the client code can then determine how many
* bytes will follow on the stream. As with all data that flows through an Rx
* stream, the longword containing the file size, in bytes, must be converted
* to network byte order before being sent. This insures that the recipient may
* properly interpret the streamed information, regardless of its memory
* architecture.
*
* \code
* nbofileBytes = htonl(fileBytes);
* /* Write out the size of the file to the Rx call. */
* bytesReallyWritten = rx_Write(a_rxCallP, &nbofileBytes, sizeof(long));
* if (bytesReallyWritten != sizeof(long)) {
* printf("** %d bytes written instead of %d for file length\n",
* bytesReallyWritten, sizeof(long));
* *a_resultP = RXDEMO_CODE_WRITE_ERROR;
* printf("\t\t[file closed]\n");
* close(fd);
* return(1);
* }
* \endcode
*
* \par
* Once the number of file bytes has been placed in the stream, the RXDEMO
* Getfile() routine runs a loop, reading a buffer's worth of the file and then
* inserting that buffer of file data into the Rx stream at each iteration.
* This loop executes until all of the file's bytes have been shipped. Notice
* there is no special end-of-file character or marker inserted into the
* stream.
* \par
* The body of the loop checks for both unix read() and rx Write errors. If
* there is a problem reading from the unix file into the transfer buffer, it
* is reflected back to the client by setting the error return parameter
* appropriately. Specifically, an individual unix read() operation could fail
* to return the desired number of bytes. Problems with rx Write() are handled
* similarly. All errors discovered in the loop result in the file being
* closed, and RXDEMO Getfile() exiting with a non-zero return value.
*
* \code
* /* Write out the contents of the file, one buffer at a time. */
* while (fileBytes > 0) {
* /* figure out the number of bytes to
* * read (and send) this time. */
* bytesToSend = (fileBytes > maxBytesToSend ?
* maxBytesToSend : fileBytes);
* bytesRead = read(fd, buff, bytesToSend);
* if (bytesRead != bytesToSend) {
* printf("Read %d instead of %d bytes from the file\n",
* bytesRead, bytesToSend);
* *a_resultP = RXDEMO_CODE_WRITE_ERROR;
* printf("\t\t[file closed]\n");
* close(fd);
* return(1);
* }
* /* Go ahead and send them. */
* bytesReallyWritten = rx_Write(a_rxCallP, buff, bytesToSend);
* if (bytesReallyWritten != bytesToSend) {
* printf("%d file bytes written instead of %d\n",
* bytesReallyWritten, bytesToSend);
* *a_resultP = RXDEMO_CODE_WRITE_ERROR;
* printf("\t\t[file closed]\n");
* close(fd);
* return(1);
* }
* /* Update the number of bytes left to go. */
* fileBytes -= bytesToSend;
* } /* Write out the file to our caller */
* \endcode
*
* \par
* Once all of the file's bytes have been shipped to the remote client, all
* that remains to be done is to close the file and return successfully.
*
* \code
* /* Close the file, then return happily. */
* *a_resultP = RXDEMO_CODE_SUCCESS;
* printf("\t\t[file closed]\n");
* close(fd);
* return(0);
* } /* RXDEMO_Getfile */
* \endcode
*
* \subsection sec6-2-4 Section 6.2.4: Makefile
*
* \par
* This file directs the compilation and installation of the rxdemo code. It
* specifies the locations of libraries, include files, sources, and such tools
* as Rxgen and install, which strips symbol tables from executables and places
* them in their target directories. This Makefile demostrates cross-cell
* software development, with the rxdemo sources residing in the
* grand.central.org cell and the AFS include files and libraries accessed from
* their locations in the transarc.com cell.
* \par
* In order to produce and install the rxdemo server and rxdemo client
* binaries, the system target should be specified on the command line when
* invoking make:
* \code
* make system
* \endcode
* \par
* A note of caution is in order concerning generation of the rxdemo binaries.
* While tools exist that deposit the results of all compilations to other
* (architecture-specific) directories, and thus facilitate multiple
* simultaneous builds across a variety of machine architectures (e.g.,
* Transarc's washtool), the assumption is made here that compilations will
* take place directly in the directory containing all the rxdemo sources.
* Thus, a user will have to execute a make clean command to remove all
* machine-specific object, library, and executable files before compiling for
* a different architecture. Note, though, that the binaries are installed into
* a directory specifically reserved for the current machine type.
* Specifically, the final pathname component of the ${PROJ DIR}bin
* installation target is really a symbolic link to ${PROJ DIR}.bin/@sys.
* \par
* Two libraries are needed to support the rxdemo code. The first is obvious,
* namely the Rx librx.a library. The second is the lightweight thread package
* library, liblwp.a, which implements all the threading operations that must
* be performed. The include files are taken from the unix /usr/include
* directory, along with various AFS-specific directories. Note that for
* portability reasons, this Makefile only contains fully-qualified AFS
* pathnames and "standard" unix pathnames (such as /usr/include).
*
* \code
* /*#=======================================================================#
* # The United States Government has rights in this work pursuant # # to
* contract no. MDA972-90-C-0036 between the United States Defense # # Advanced
* Research Projects Agency and Transarc Corporation. # # # # (C) Copyright
* 1991
* Transarc Corporation # # # # Redistribution and use in source and binary
* forms
* are permitted # # provided that: (1) source distributions retain this entire
* copy-# # right notice and comment, and (2) distributions including binaries
* #
* # display the following acknowledgement: # # # # ''This product includes
* software developed by Transarc # # Corporation and its contributors'' # # #
* #
* in the documentation or other materials mentioning features or # # use of
* this
* software. Neither the name of Transarc nor the names # # of its contributors
* may be used to endorse or promote products # # derived from this software
* without specific prior written # # permission. # # # # THIS SOFTWARE IS
* PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED # # WARRANTIES,
* INCLUDING,
* WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF # # MERCHANTABILITY AND
* FITNESS
* FOR A PARTICULAR PURPOSE. #
* #=======================================================================# */
*
* SHELL = /bin/sh
* TOOL_CELL = grand.central.org
* AFS_INCLIB_CELL = transarc.com
* USR_CONTRIB = /afs/${TOOL_CELL}/darpa/usr/contrib/
* PROJ_DIR = ${USR_CONTRIB}.site/grand.central.org/rxdemo/
* AFS_INCLIB_DIR = /afs/${AFS_INCLIB_CELL}/afs/dest/
* RXGEN = ${AFS_INCLIB_DIR}bin/rxgen
* INSTALL = ${AFS_INCLIB_DIR}bin/install
* LIBS = ${AFS_INCLIB_DIR}lib/librx.a \ ${AFS_INCLIB_DIR}lib/liblwp.a
* CFLAGS = -g \
* -I. \
* -I${AFS_INCLIB_DIR}include \
* -I${AFS_INCLIB_DIR}include/afs \
* -I${AFS_INCLIB_DIR} \
* -I/usr/include
*
* system: install
*
* install: all
* ${INSTALL} rxdemo_client
* ${PROJ_DIR}bin
* ${INSTALL} rxdemo_server
* ${PROJ_DIR}bin
*
* all: rxdemo_client rxdemo_server
*
* rxdemo_client: rxdemo_client.o ${LIBS} rxdemo.cs.o ${CC} ${CFLAGS}
* -o rxdemo_client rxdemo_client.o rxdemo.cs.o ${LIBS}
*
* rxdemo_server: rxdemo_server.o rxdemo.ss.o ${LIBS} ${CC} ${CFLAGS}
* -o rxdemo_server rxdemo_server.o rxdemo.ss.o ${LIBS}
*
* rxdemo_client.o: rxdemo.h
*
* rxdemo_server.o: rxdemo.h
*
* rxdemo.cs.c rxdemo.ss.c rxdemo.er.c rxdemo.h: rxdemo.xg rxgen rxdemo.xg
*
* clean: rm -f *.o rxdemo.cs.c rxdemo.ss.c rxdemo.xdr.c rxdemo.h \
* rxdemo_client rxdemo_server core
* \endcode
*
* \section sec6-3 Section 6.3: Computer-Generated files
*
* \par
* The four human-generated files described above provide all the information
* necessary to construct the full set of modules to support the rxdemo example
* application. This section describes those routines that are generated from
* the base set by Rxgen, filling out the code required to implement an Rx
* service.
*
* \subsection sec6-3-1 Client-Side Routines: rxdemo.cs.c
*
* \par
* The rxdemo client.c program, described in Section 6.2.2, calls the
* client-side stub routines contained in this module in order to make rxdemo
* RPCs. Basically, these client-side stubs are responsible for creating new Rx
* calls on the given connection parameter and then marshalling and
* unmarshalling the rest of the interface call parameters. The IN and INOUT
* arguments, namely those that are to be delivered to the server-side code
* implementing the call, must be packaged in network byte order and shipped
* along the given Rx call. The return parameters, namely those objects
* declared as INOUT and OUT, must be fetched from the server side of the
* associated Rx call, put back in host byte order, and inserted into the
* appropriate parameter variables.
* \par
* The first part of rxdemo.cs.c echoes the definitions appearing in the
* rxdemo.xg interface file, and also #includes another Rxgen-generated file,
* rxdemo.h.
*
* \code
* /*======================================================================%
* * % THIS SOFTWARE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED %
* * % WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF %
* * % MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. %
* * %====================================================================== */
* /* Machine generated file --Do NOT edit */
*
* #include "rxdemo.h"
* #define RXDEMO_CODE_WRITE_ERROR 4
*
* #include <rx/rx.h>
* #include <rx/rx_null.h>
* #define RXDEMO_SERVER_PORT 8000 /* Service port to advertise */
* #define RXDEMO_SERVICE_PORT 0 /* User server's port */
* #define RXDEMO_SERVICE_ID 4 /* Service ID */
* #define RXDEMO_NULL_SECOBJ_IDX 0 /* Index of null security object */
* #define RXDEMO_MAX 3
* #define RXDEMO_MIN 2
* #define RXDEMO_NULL 0
* #define RXDEMO_NAME_MAX_CHARS 64
* #define RXDEMO_BUFF_BYTES 512
* #define RXDEMO_CODE_SUCCESS 0
* #define RXDEMO_CODE_CANT_OPEN 1
* #define RXDEMO_CODE_CANT_STAT 2
* #define RXDEMO_CODE_CANT_READ 3
* #define RXDEMO_CODE_WRITE_ERROR 4
* \endcode
*
* \par
* The next code fragment defines the client-side stub for the RXDEMO Add()
* routine, called by the rxdemo client program to execute the associated RPC.
*
* \code
* int RXDEMO_Add(z_conn, a, b, result) register struct rx_connection *z_conn;
* int a, b;
* int * result;
* {
* struct rx_call *z_call = rx_NewCall(z_conn);
* static int z_op = 1;
* int z_result;
* XDR z_xdrs;
* xdrrx_create(&z_xdrs, z_call, XDR_ENCODE);
* /* Marshal the arguments */
* if ((!xdr_int(&z_xdrs, &z_op))
* || (!xdr_int(&z_xdrs, &a))
* || (!xdr_int(&z_xdrs, &b))) {
* z_result = RXGEN_CC_MARSHAL;
* goto fail;
* }
* /* Un-marshal the reply arguments */
* z_xdrs.x_op = XDR_DECODE;
* if ((!xdr_int(&z_xdrs, result))) {
* z_result = RXGEN_CC_UNMARSHAL;
* goto fail;
* }
* z_result = RXGEN_SUCCESS;
* fail: return rx_EndCall(z_call, z_result);
* }
* \endcode
*
* \par
* The very first operation performed by RXDEMO Add() occurs in the local
* variable declarations, where z call is set to point to the structure
* describing a newly-created Rx call on the given connection. An XDR
* structure, z xdrs, is then created for the given Rx call with xdrrx
* create(). This XDR object is used to deliver the proper arguments, in
* network byte order, to the matching server stub code. Three calls to xdr
* int() follow, which insert the appropriate Rx opcode and the two operands
* into the Rx call. With the IN arguments thus transmitted, RXDEMO Add()
* prepares to pull the value of the single OUT parameter. The z xdrs XDR
* structure, originally set to XDR ENCODE objects, is now reset to XDR DECODE
* to convert further items received into host byte order. Once the return
* parameter promised by the function is retrieved, RXDEMO Add() returns
* successfully.
* \par
* Should any failure occur in passing the parameters to and from the server
* side of the call, the branch to fail will invoke Rx EndCall(), which advises
* the server that the call has come to a premature end (see Section 5.6.6 for
* full details on rx EndCall() and the meaning of its return value).
* \par
* The next client-side stub appearing in this generated file handles the
* delivery of the IN parameters for StartRXDEMO Getfile(). It operates
* identically as the RXDEMO Add() stub routine in this respect, except that it
* does not attempt to retrieve the OUT parameter. Since this is a streamed
* call, the number of bytes that will be placed on the Rx stream cannot be
* determined at compile time, and must be handled explicitly by rxdemo
* client.c.
*
* \code
* int StartRXDEMO_Getfile(z_call, a_nameToRead)
* register struct rx_call *z_call;
* char * a_nameToRead;
* {
* static int z_op = 2;
* int z_result;
* XDR z_xdrs;
* xdrrx_create(&z_xdrs, z_call, XDR_ENCODE);
* /* Marshal the arguments */
* if ((!xdr_int(&z_xdrs, &z_op)) || (!xdr_string(&z_xdrs, &a_nameToRead,
* RXDEMO_NAME_MAX_CHARS))) {
* z_result = RXGEN_CC_MARSHAL;
* goto fail;
* }
* z_result = RXGEN_SUCCESS;
* fail: return z_result;
* }
* \endcode
*
* \par
* The final stub routine appearing in this generated file, EndRXDEMO
* Getfile(), handles the case where rxdemo client.c has already successfully
* recovered the unbounded streamed data appearing on the call, and then simply
* has to fetch the OUT parameter. This routine behaves identially to the
* latter portion of RXDEMO Getfile().
*
* \code
* int EndRXDEMO_Getfile(z_call, a_result)
* register struct rx_call *z_call;
* int * a_result;
* {
* int z_result;
* XDR z_xdrs;
* /* Un-marshal the reply arguments */
* xdrrx_create(&z_xdrs, z_call, XDR_DECODE);
* if ((!xdr_int(&z_xdrs, a_result))) {
* z_result = RXGEN_CC_UNMARSHAL;
* goto fail;
* }
* z_result = RXGEN_SUCCESS; fail:
* return z_result;
* }
* \endcode
*
* \subsection sec6-3-2 Server-Side Routines: rxdemo.ss.c
*
* \par
* This generated file provides the core components required to implement the
* server side of the rxdemo RPC service. Included in this file is the
* generated dispatcher routine, RXDEMO ExecuteRequest(), which the rx
* NewService() invocation in rxdemo server.c uses to construct the body of
* each listener thread's loop. Also included are the server-side stubs to
* handle marshalling and unmarshalling of parameters for each defined RPC call
* (i.e., RXDEMO Add() and RXDEMO Getfile()). These stubs are called by RXDEMO
* ExecuteRequest(). The routine to be called by RXDEMO ExecuteRequest()
* depends on the opcode received, which appears as the very first longword in
* the call data.
* \par
* As usual, the first fragment is copyright information followed by the body
* of the definitions from the interface file.
*
* \code
* /*======================================================================%
* % Edward R. Zayas % % Transarc Corporation % % % % % % The United States
* Government has rights in this work pursuant % % to contract no.
* MDA972-90-C-0036 between the United States Defense % % Advanced Research
* Projects Agency and Transarc Corporation. % % % % (C) Copyright 1991
* Transarc Corporation % % % % Redistribution and use in source and binary
* forms are permitted % % provided that: (1) source distributions retain
* this entire copy¬% % right notice and comment, and (2) distributions
* including binaries %
* %====================================================================== */
* /* Machine generated file --Do NOT edit */
*
* #include "rxdemo.h"
* #include <rx/rx.h>
* #include <rx/rx_null.h>
* #define RXDEMO_SERVER_PORT 8000 /* Service port to advertise */
* #define RXDEMO_SERVICE_PORT 0 /* User server's port */
* #define RXDEMO_SERVICE_ID 4 /* Service ID */
* #define RXDEMO_NULL_SECOBJ_IDX 0 /* Index of null security object */
* #define RXDEMO_MAX 3
* #define RXDEMO_MIN 2
* #define RXDEMO_NULL 0
* #define RXDEMO_NAME_MAX_CHARS 64
* #define RXDEMO_BUFF_BYTES 512
* #define RXDEMO_CODE_SUCCESS 0
* #define RXDEMO_CODE_CANT_OPEN 1
* #define RXDEMO_CODE_CANT_STAT 2
* #define RXDEMO_CODE_CANT_READ 3
* #define RXDEMO_CODE_WRITE_ERROR 4
* \endcode
*
* \par
* After this preamble, the first server-side stub appears. This RXDEMO Add()
* routine is basically the inverse of the RXDEMO Add() client-side stub
* defined in rxdemo.cs.c. Its job is to unmarshall the IN parameters for the
* call, invoke the "true" server-side RXDEMO Add() routine (defined in rxdemo
* server.c), and then package and ship the OUT parameter. Being so similar to
* the client-side RXDEMO Add(), no further discussion is offered here.
*
* \code
* long _RXDEMO_Add(z_call, z_xdrs)
* struct rx_call *z_call;
* XDR *z_xdrs;
* {
* long z_result;
* int a, b;
* int result;
* if ((!xdr_int(z_xdrs, &a)) || (!xdr_int(z_xdrs, &b)))
* {
* z_result = RXGEN_SS_UNMARSHAL;
* goto fail;
* }
* z_result = RXDEMO_Add(z_call, a, b, &result);
* z_xdrs->x_op = XDR_ENCODE;
* if ((!xdr_int(z_xdrs, &result)))
* z_result = RXGEN_SS_MARSHAL;
* fail: return z_result;
* }
* \endcode
*
* \par
* The second server-side stub, RXDEMO Getfile(), appears next. It operates
* identically to RXDEMO Add(), first unmarshalling the IN arguments, then
* invoking the routine that actually performs the server-side work for the
* call, then finishing up by returning the OUT parameters.
*
* \code
* long _RXDEMO_Getfile(z_call, z_xdrs)
* struct rx_call *z_call;
* XDR *z_xdrs;
* {
* long z_result;
* char * a_nameToRead=(char *)0;
* int a_result;
* if ((!xdr_string(z_xdrs, &a_nameToRead, RXDEMO_NAME_MAX_CHARS))) {
* z_result = RXGEN_SS_UNMARSHAL;
* goto fail;
* }
* z_result = RXDEMO_Getfile(z_call, a_nameToRead, &a_result);
* z_xdrs->x_op = XDR_ENCODE;
* if ((!xdr_int(z_xdrs, &a_result)))
* z_result = RXGEN_SS_MARSHAL;
* fail: z_xdrs->x_op = XDR_FREE;
* if (!xdr_string(z_xdrs, &a_nameToRead, RXDEMO_NAME_MAX_CHARS))
* goto fail1;
* return z_result;
* fail1: return RXGEN_SS_XDRFREE;
* }
* \endcode
*
* \par
* The next portion of the automatically generated server-side module sets up
* the dispatcher routine for incoming Rx calls. The above stub routines are
* placed into an array in opcode order.
*
* \code
* long _RXDEMO_Add();
* long _RXDEMO_Getfile();
* static long (*StubProcsArray0[])() = {_RXDEMO_Add, _RXDEMO_Getfile};
* \endcode
*
* \par
* The dispatcher routine itself, RXDEMO ExecuteRequest, appears next. This is
* the function provided to the rx NewService() call in rxdemo server.c, and it
* is used as the body of each listener thread's service loop. When activated,
* it decodes the first longword in the given Rx call, which contains the
* opcode. It then dispatches the call based on this opcode, invoking the
* appropriate server-side stub as organized in the StubProcsArray.
*
* \code
* RXDEMO_ExecuteRequest(z_call)
* register struct rx_call *z_call;
* {
* int op;
* XDR z_xdrs;
* long z_result;
* xdrrx_create(&z_xdrs, z_call, XDR_DECODE);
* if (!xdr_int(&z_xdrs, &op))
* z_result = RXGEN_DECODE;
* else if (op < RXDEMO_LOWEST_OPCODE || op > RXDEMO_HIGHEST_OPCODE)
* z_result = RXGEN_OPCODE;
* else
* z_result = (*StubProcsArray0[op -RXDEMO_LOWEST_OPCODE])(z_call,
* &z_xdrs);
* return z_result;
* }
* \endcode
*
* \subsection sec6-3-3 External Data Rep file: rxdemo.xdr.c
*
* \par
* This file is created to provide the special routines needed to map any
* user-defined structures appearing as Rx arguments into and out of network
* byte order. Again, all on-thewire data appears in network byte order,
* insuring proper communication between servers and clients with different
* memory organizations.
* \par
* Since the rxdemo example application does not define any special structures
* to pass as arguments in its calls, this generated file contains only the set
* of definitions appearing in the interface file. In general, though, should
* the user define a struct xyz and use it as a parameter to an RPC function,
* this file would contain a routine named xdr xyz(), which converted the
* structure field-by-field to and from network byte order.
*
* \code
* /*======================================================================%
* %% % in the documentation or other materials mentioning features or % %
* use of this software. Neither the name of Transarc nor the names % % of
* its contributors may be used to endorse or promote products % % derived
* from this software without specific prior written % % permission. % % %
* % THIS SOFTWARE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED %
* % WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF %
* % MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. %
* % Edward R. Zayas % Transarc Corporation % % % The United States
* Government has rights in this work pursuant to contract no.
* MDA972-90-C-0036 between the United States Defense % Advanced Research
* Projects Agency and Transarc Corporation. % % (C) Copyright 1991 Transarc
* Corporation % % Redistribution and use in source and binary forms are
* permitted % % provided that: (1) source distributions retain this entire
* copy¬ % right notice and comment, and (2) distributions including binaries
* % % display the following acknowledgement: % % % % ``This product includes
* software developed by Transarc % % Corporation and its contributors'' %
* %====================================================================== */
* /* Machine generated file --Do NOT edit */
*
* #include "rxdemo.h"
* #include <rx/rx.h>
* #include <rx/rx_null.h>
* #define RXDEMO_SERVER_PORT 8000 /* Service port to advertise */
* #define RXDEMO_SERVICE_PORT 0 /* User server's port */
* #define RXDEMO_SERVICE_ID 4 /* Service ID */
* #define RXDEMO_NULL_SECOBJ_IDX 0 /* Index of null security object */
* #define RXDEMO_MAX 3
* #define RXDEMO_MIN 2
* #define RXDEMO_NULL 0
* #define RXDEMO_NAME_MAX_CHARS 64
* #define RXDEMO_BUFF_BYTES 512
* #define RXDEMO_CODE_SUCCESS 0
* #define RXDEMO_CODE_CANT_OPEN 1
* #define RXDEMO_CODE_CANT_STAT 2
* #define RXDEMO_CODE_CANT_READ 3
* #define RXDEMO_CODE_WRITE_ERROR 4
* \endcode
*
* \section sec6-4 Section 6.4: Sample Output
*
* \par
* This section contains the output generated by running the example rxdemo
* server and rxdemo client programs described above. The server end was run on
* a machine named Apollo, and the client program was run on a machine named
* Bigtime.
* \par
* The server program on Apollo was started as follows:
* \li apollo: rxdemo_server
* \li rxdemo_server: Example Rx server process
* \li Listening on UDP port 8000
* \par
* At this point, rxdemo server has initialized its Rx module and started up
* its listener LWPs, which are sleeping on the arrival of an RPC from any
* rxdemo client.
* \par
* The client portion was then started on Bigtime:
* \n bigtime: rxdemo_client apollo
* \n rxdemo: Example Rx client process
* \n Connecting to Rx server on 'apollo', IP address 0x1acf37c0, UDP port 8000
* \n ---> Connected. Asking server to add 1 and 2: Reported sum is 3
* \par
* The command line instructs rxdemo client to connect to the rxdemo server on
* host apollo and to use the standard port defined for this service. It
* reports on the successful Rx connection establishment, and immediately
* executes an rxdemo Add(1, 2) RPC. It reports that the sum was successfully
* received. When the RPC request arrived at the server and was dispatched by
* the rxdemo server code, it printed out the following line:
* \n [Handling call to RXDEMO_Add(1, 2)]
* \par
* Next, rxdemo client prompts for the name of the file to read from the rxdemo
* server. It is told to fetch the Makefile for the Rx demo directory. The
* server is executing in the same directory in which it was compiled, so an
* absolute name for the Makefile is not required. The client echoes the
* following:
* \n Name of file to read from server: Makefile Setting up an Rx call for
* RXDEMO_Getfile...done
* \par
* As with the rxdemo Add() call, rxdemo server receives this RPC, and prints
* out the following information:
* \li [Handling call to RXDEMO_Getfile(Makefile)]
* \li [file opened]
* \li [file has 2450 bytes]
* \li [file closed]
* \par
* It successfully opens the named file, and reports on its size in bytes. The
* rxdemo server program then executes the streamed portion of the rxdemo
* Getfile call, and when complete, indicates that the file has been closed.
* Meanwhile, rxdemo client prints out the reported size of the file, follows
* it with the file's contents, then advises that the test run has completed:
*
* \code
* [file contents (2450 bytes) fetched over the Rx call appear below]
*
* /*#=======================================================================#
* # The United States Government has rights in this work pursuant # # to
* contract no. MDA972-90-C-0036 between the United States Defense # # Advanced
* Research Projects Agency and Transarc Corporation. # # # # (C) Copyright
* 1991 Transarc Corporation # # # # Redistribution and use in source and
* binary forms are permitted # # provided that: (1) source distributions
* retain this entire copy-# # right notice and comment, and (2) distributions
* including binaries # # display the following acknowledgement: # # # # ''This
* product includes software developed by Transarc # # Corporation and its
* contributors'' # # # # in the documentation or other materials mentioning
* features or # # use of this software. Neither the name of Transarc nor the
* names # # of its contributors may be used to endorse or promote products #
* # derived from this software without specific prior written # # permission.
* # # # # THIS SOFTWARE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED
* # # WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF # #
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. #
* #=======================================================================# */
*
* SHELL = /bin/sh
* TOOL_CELL = grand.central.org
* AFS_INCLIB_CELL = transarc.com
* USR_CONTRIB = /afs/${TOOL_CELL}/darpa/usr/contrib/
* PROJ_DIR = ${USR_CONTRIB}.site/grand.central.org/rxdemo/
* AFS_INCLIB_DIR = /afs/${AFS_INCLIB_CELL}/afs/dest/
* RXGEN = ${AFS_INCLIB_DIR}bin/rxgen
* INSTALL = ${AFS_INCLIB_DIR}bin/install
* LIBS = ${AFS_INCLIB_DIR}lib/librx.a \ ${AFS_INCLIB_DIR}lib/liblwp.a
* CFLAGS = -g \
* -I. \
* -I${AFS_INCLIB_DIR}include \
* -I${AFS_INCLIB_DIR}include/afs \
* -I${AFS_INCLIB_DIR} \
* -I/usr/include
*
* system: install
*
* install: all
* ${INSTALL} rxdemo_client ${PROJ_DIR}bin
* ${INSTALL} rxdemo_server ${PROJ_DIR}bin
*
* all: rxdemo_client rxdemo_server
*
* rxdemo_client: rxdemo_client.o ${LIBS} rxdemo.cs.o ${CC} ${CFLAGS}
* -o rxdemo_client rxdemo_client.o rxdemo.cs.o ${LIBS}
*
* rxdemo_server: rxdemo_server.o rxdemo.ss.o ${LIBS} ${CC} ${CFLAGS}
* -o rxdemo_server rxdemo_server.o rxdemo.ss.o ${LIBS}
*
* rxdemo_client.o: rxdemo.h
*
* rxdemo_server.o: rxdemo.h
*
* rxdemo.cs.c rxdemo.ss.c rxdemo.er.c rxdemo.h: rxdemo.xg rxgen rxdemo.xg
*
* clean: rm -f *.o rxdemo.cs.c rxdemo.ss.c rxdemo.xdr.c rxdemo.h \
* rxdemo_client rxdemo_server core
*
* [End of file data]
* rxdemo complete.
* \endcode
*
* \par
* The rxdemo server program continues to run after handling these calls,
* offering its services to any other callers. It can be killed by sending it
* an interrupt signal using Control-C (or whatever mapping has been set up for
* the shell's interrupt character).
*
* \section Bibliography Bibliography
*
* \li [1] Transarc Corporation. AFS 3.0 System Administrator's Guide,
* F-30-0-D102, Pittsburgh, PA, April 1990.
* \li [2] S.P. Miller, B.C. Neuman, J.I. Schiller, J.H. Saltzer. Kerberos
* Authentication and Authorization System, Project Athena Technical Plan,
* Section E.2.1, M.I.T., December 1987.
* \li [3] Bill Bryant. Designing an Authentication System: a Dialogue
* in Four Scenes, Project Athena internal document, M.I.T, draft of 8 February
* 1988.
* \li [4] S. R. Kleinman. Vnodes: An Architecture for Multiple file
* System Types in Sun UNIX, Conference Proceedings, 1986 Summer Usenix
* Technical Conference, pp. 238-247, El Toro, CA, 1986.
*
* @}
*/