Name:

lws_client_reset - retarget a connected wsi to start over with a new connection (ie, redirect) this only works if still in HTTP, ie, not upgraded yet

Synopsis:

struct lws * lws_client_reset (struct lws * wsi,
                               int ssl,
                               const char * address,
                               int port,
                               const char * path,
                               const char * host);

Arguments:

wsi
	-- undescribed --
ssl
	-- undescribed --
address
	-- undescribed --
port
	-- undescribed --
path
	-- undescribed --
host
	-- undescribed --

wsi:

connection to reset
address:

network address of the new server
port:

port to connect to
path:

uri path to connect to on the new server
host:

host header to send to the new server


Name:

lws_client_connect_via_info - Connect to another websocket server

Synopsis:

struct lws * lws_client_connect_via_info (struct lws_client_connect_info * i);

Arguments:

i
	pointer to lws_client_connect_info struct


Description:

This function creates a connection to a remote server


Name:

lws_client_connect_extended - Connect to another websocket server DEPRECATED use lws_client_connect_via_info

Synopsis:

struct lws * lws_client_connect_extended (struct lws_context * context,
                                          const char * address,
                                          int port,
                                          int ssl_connection,
                                          const char * path,
                                          const char * host,
                                          const char * origin,
                                          const char * protocol,
                                          int ietf_version_or_minus_one,
                                          void * userdata);

Arguments:

context
	Websocket context

address
	Remote server address, eg, "myserver.com"

port
	Port to connect to on the remote server, eg, 80

ssl_connection
	0 = ws://, 1 = wss:// encrypted, 2 = wss:// allow self
signed certs

path
	Websocket path on server

host
	Hostname on server

origin
	Socket origin name

protocol
	Comma-separated list of protocols being asked for from
the server, or just one.  The server will pick the one it
likes best.

ietf_version_or_minus_one
	-1 to ask to connect using the default, latest
protocol supported, or the specific protocol ordinal

userdata
	Pre-allocated user data


Description:

This function creates a connection to a remote server


Name:

lws_client_connect - Connect to another websocket server DEPRECATED use lws_client_connect_via_info

Synopsis:

struct lws * lws_client_connect (struct lws_context * context,
                                 const char * address,
                                 int port,
                                 int ssl_connection,
                                 const char * path,
                                 const char * host,
                                 const char * origin,
                                 const char * protocol,
                                 int ietf_version_or_minus_one);

Arguments:

context
	Websocket context

address
	Remote server address, eg, "myserver.com"

port
	Port to connect to on the remote server, eg, 80

ssl_connection
	0 = ws://, 1 = wss:// encrypted, 2 = wss:// allow self
signed certs

path
	Websocket path on server

host
	Hostname on server

origin
	Socket origin name

protocol
	Comma-separated list of protocols being asked for from
the server, or just one.  The server will pick the one it
likes best.  If you don't want to specify a protocol, which is
legal, use NULL here.

ietf_version_or_minus_one
	-1 to ask to connect using the default, latest
protocol supported, or the specific protocol ordinal


Description:

This function creates a connection to a remote server


Name:

lws_http_transaction_completed_client - wait for new http transaction or close

Synopsis:

int LWS_WARN_UNUSED_RESULT lws_http_transaction_completed_client (struct lws * wsi);

Arguments:

wsi
	websocket connection


Description:

Returns 1 if the HTTP connection must close now
Returns 0 and resets connection to wait for new HTTP header /
transaction if possible


Name:

lws_get_library_version - 

Synopsis:

const char * lws_get_library_version ( void);

Arguments:

void
	no arguments

Description:


returns a const char * to a string like "1.1 178d78c"
representing the library version followed by the git head hash it
was built from


Name:

lws_create_context - Create the websocket handler

Synopsis:

struct lws_context * lws_create_context (struct lws_context_creation_info * info);

Arguments:

info
	pointer to struct with parameters


Description:

This function creates the listening socket (if serving) and takes care
of all initialization in one step.

After initialization, it returns a struct lws_context * that
represents this server.  After calling, user code needs to take care
of calling lws_service with the context pointer to get the
server's sockets serviced.  This must be done in the same process
context as the initialization call.

The protocol callback functions are called for a handful of events
including http requests coming in, websocket connections becoming
established, and data arriving; it's also called periodically to allow
async transmission.

HTTP requests are sent always to the FIRST protocol in protocol, since
at that time websocket protocol has not been negotiated.  Other
protocols after the first one never see any HTTP callack activity.

The server created is a simple http server by default; part of the
websocket standard is upgrading this http connection to a websocket one.

This allows the same server to provide files like scripts and favicon /
images or whatever over http and dynamic data over websockets all in
one place; they're all handled in the user callback.


Name:

lws_context_destroy - Destroy the websocket context

Synopsis:

void lws_context_destroy (struct lws_context * context);

Arguments:

context
	Websocket context


Description:

This function closes any active connections and then frees the
context.  After calling this, any further use of the context is
undefined.


Name:

lws_set_extension_option - 

Synopsis:

int lws_set_extension_option (struct lws * wsi,
                              const char * ext_name,
                              const char * opt_name,
                              const char * opt_val);

Arguments:

wsi
	websocket connection

ext_name
	name of ext, like "permessage-deflate"

opt_name
	name of option, like "rx_buf_size"

opt_val
	value to set option to




Name:

lws_return_http_status - Return simple http status

Synopsis:

int lws_return_http_status (struct lws * wsi,
                            unsigned int code,
                            const char * html_body);

Arguments:

wsi
	Websocket instance (available from user callback)

code
	Status index, eg, 404

html_body
	User-readable HTML description < 1KB, or NULL


Description:

Helper to report HTTP errors back to the client cleanly and
consistently


Name:

lws_set_timeout - marks the wsi as subject to a timeout

Synopsis:

void lws_set_timeout (struct lws * wsi,
                      enum pending_timeout reason,
                      int secs);

Arguments:

wsi
	Websocket connection instance

reason
	timeout reason

secs
	how many seconds


Description:


You will not need this unless you are doing something special


Name:

lws_get_peer_addresses - Get client address information

Synopsis:

void lws_get_peer_addresses (struct lws * wsi,
                             lws_sockfd_type fd,
                             char * name,
                             int name_len,
                             char * rip,
                             int rip_len);

Arguments:

wsi
	Local struct lws associated with

fd
	Connection socket descriptor

name
	Buffer to take client address name

name_len
	Length of client address name buffer

rip
	Buffer to take client address IP dotted quad

rip_len
	Length of client address IP buffer


Description:

This function fills in name and rip with the name and IP of
the client connected with socket descriptor fd.  Names may be
truncated if there is not enough room.  If either cannot be
determined, they will be returned as valid zero-length strings.


Name:

lws_context_user - get the user data associated with the context

Synopsis:

LWS_EXTERN void * lws_context_user (struct lws_context * context);

Arguments:

context
	Websocket context


Description:

This returns the optional user allocation that can be attached to
the context the sockets live in at context_create time.  It's a way
to let all sockets serviced in the same context share data without
using globals statics in the user code.


Name:

lws_callback_all_protocol - Callback all connections using the given protocol with the given reason

Synopsis:

int lws_callback_all_protocol (struct lws_context * context,
                               const struct lws_protocols * protocol,
                               int reason);

Arguments:

context
	-- undescribed --
protocol
	Protocol whose connections will get callbacks

reason
	Callback reason index




Name:

lws_callback_all_protocol_vhost - Callback all connections using the given protocol with the given reason

Synopsis:

int lws_callback_all_protocol_vhost (struct lws_vhost * vh,
                                     const struct lws_protocols * protocol,
                                     int reason);

Arguments:

vh
	Vhost whose connections will get callbacks

protocol
	Which protocol to match

reason
	Callback reason index




Name:

lws_get_socket_fd - returns the socket file descriptor

Synopsis:

int lws_get_socket_fd (struct lws * wsi);

Arguments:

wsi
	Websocket connection instance


Description:


You will not need this unless you are doing something special


Name:

lws_rx_flow_control - Enable and disable socket servicing for received packets.

Synopsis:

int lws_rx_flow_control (struct lws * wsi,
                         int enable);

Arguments:

wsi
	Websocket connection instance to get callback for

enable
	0 = disable read servicing for this connection, 1 = enable


Description:


If the output side of a server process becomes choked, this allows flow
control for the input side.


Name:

lws_rx_flow_allow_all_protocol - Allow all connections with this protocol to receive

Synopsis:

void lws_rx_flow_allow_all_protocol (const struct lws_context * context,
                                     const struct lws_protocols * protocol);

Arguments:

context
	-- undescribed --
protocol
	all connections using this protocol will be allowed to receive


Description:


When the user server code realizes it can accept more input, it can
call this to have the RX flow restriction removed from all connections using
the given protocol.


Name:

lws_canonical_hostname - returns this host's hostname

Synopsis:

const char * lws_canonical_hostname (struct lws_context * context);

Arguments:

context
	Websocket context


Description:


This is typically used by client code to fill in the host parameter
when making a client connection.  You can only call it after the context
has been created.


Name:

lws_set_proxy - Setups proxy to lws_context.

Synopsis:

int lws_set_proxy (struct lws_vhost * vhost,
                   const char * proxy);

Arguments:

vhost
	-- undescribed --
proxy
	pointer to c string containing proxy in format address:port


Description:

Returns 0 if proxy string was parsed and proxy was setup.
Returns -1 if proxy is NULL or has incorrect format.

This is only required if your OS does not provide the http_proxy
environment variable (eg, OSX)

IMPORTANT! You should call this function right after creation of the
lws_context and before call to connect. If you call this
function after connect behavior is undefined.
This function will override proxy settings made on lws_context
creation with genenv call.


Name:

lws_get_protocol - Returns a protocol pointer from a websocket connection.

Synopsis:

const struct lws_protocols * lws_get_protocol (struct lws * wsi);

Arguments:

wsi
	pointer to struct websocket you want to know the protocol of


Description:


Some apis can act on all live connections of a given protocol,
this is how you can get a pointer to the active protocol if needed.


Name:

lwsl_timestamp - 

Synopsis:

int lwsl_timestamp (int level,
                    char * p,
                    int len);

Arguments:

level
	logging level

p
	char * buffer to take timestamp

len
	length of p


Description:

returns length written in p


Name:

lws_set_log_level - Set the logging bitfield

Synopsis:

void lws_set_log_level (int level,
                        void (*func) (int level, const char *line);

Arguments:

level
	OR together the LLL_ debug contexts you want output from

func
	-- undescribed --

Description:

log level defaults to "err", "warn" and "notice" contexts enabled and
emission on stderr.


Name:

lws_is_ssl - Find out if connection is using SSL

Synopsis:

int lws_is_ssl (struct lws * wsi);

Arguments:

wsi
	websocket connection to check


Description:

Returns 0 if the connection is not using SSL, 1 if using SSL and
using verified cert, and 2 if using SSL but the cert was not
checked (appears for client wsi told to skip check on connection)


Name:

lws_partial_buffered - find out if lws buffered the last write

Synopsis:

int lws_partial_buffered (struct lws * wsi);

Arguments:

wsi
	websocket connection to check


Description:

Returns 1 if you cannot use lws_write because the last
write on this connection is still buffered, and can't be cleared without
returning to the service loop and waiting for the connection to be
writeable again.

If you will try to do >1 lws_write call inside a single
WRITEABLE callback, you must check this after every write and bail if
set, ask for a new writeable callback and continue writing from there.

This is never set at the start of a writeable callback, but any write
may set it.


Name:

lws_get_context - Allow getting lws_context from a Websocket connection instance

Synopsis:

LWS_EXTERN struct lws_context * lws_get_context (const struct lws * wsi);

Arguments:

wsi
	Websocket connection instance


Description:


With this function, users can access context in the callback function.
Otherwise users may have to declare context as a global variable.


Name:

lws_parse_uri - 

Synopsis:

LWS_EXTERN int lws_parse_uri (char * p,
                              const char ** prot,
                              const char ** ads,
                              int * port,
                              const char ** path);

Arguments:

p
	incoming uri string.. will get written to

prot
	result pointer for protocol part (https://)

ads
	result pointer for address part

port
	result pointer for port part

path
	result pointer for path part


Description:

Notice it does so by dropping '\0' into input string
and the leading / on the path is consequently lost


Name:

lws_cgi - connected cgi process

Synopsis:

LWS_EXTERN int lws_cgi (struct lws * wsi,
                        const char *const * exec_array,
                        int script_uri_path_len,
                        int timeout_secs,
                        const struct lws_protocol_vhost_options * mp_cgienv);

Arguments:

wsi
	connection to own the process

exec_array
	array of "exec-name" "arg1" ... "argn" NULL

script_uri_path_len
	-- undescribed --
timeout_secs
	-- undescribed --
mp_cgienv
	-- undescribed --



Name:

lws_cgi_write_split_stdout_headers - 

Synopsis:

LWS_EXTERN int lws_cgi_write_split_stdout_headers (struct lws * wsi);

Arguments:

wsi
	connection to own the process




Name:

lws_cgi_kill - 

Synopsis:

LWS_EXTERN int lws_cgi_kill (struct lws * wsi);

Arguments:

wsi
	connection to own the process




Name:

lws_cancel_service - Cancel servicing of pending websocket activity

Synopsis:

void lws_cancel_service (struct lws_context * context);

Arguments:

context
	Websocket context


Description:

This function let a call to lws_service waiting for a timeout
immediately return.

There is no poll in MBED3, he will fire callbacks when he feels like
it.


Name:

lws_cancel_service_pt - Cancel servicing of pending socket activity on one thread

Synopsis:

void lws_cancel_service_pt (struct lws * wsi);

Arguments:

wsi
	Cancel service on the thread this wsi is serviced by


Description:

This function let a call to lws_service waiting for a timeout
immediately return.


Name:

lws_cancel_service - Cancel ALL servicing of pending socket activity

Synopsis:

void lws_cancel_service (struct lws_context * context);

Arguments:

context
	Websocket context


Description:

This function let a call to lws_service waiting for a timeout
immediately return.


Name:

lws_cancel_service - Cancel servicing of pending websocket activity

Synopsis:

void lws_cancel_service (struct lws_context * context);

Arguments:

context
	Websocket context


Description:

This function let a call to lws_service waiting for a timeout
immediately return.


Name:

lws_write - Apply protocol then write data to client

Synopsis:

int lws_write (struct lws * wsi,
               unsigned char * buf,
               size_t len,
               enum lws_write_protocol wp);

Arguments:

wsi
	Websocket instance (available from user callback)

buf
	The data to send.  For data being sent on a websocket
connection (ie, not default http), this buffer MUST have
LWS_PRE bytes valid BEFORE the pointer.
This is so the protocol header data can be added in-situ.

len
	Count of the data bytes in the payload starting from buf

wp
	-- undescribed --

Description:

This function provides the way to issue data back to the client
for both http and websocket protocols.

In the case of sending using websocket protocol, be sure to allocate
valid storage before and after buf as explained above.  This scheme
allows maximum efficiency of sending data and protocol in a single
packet while not burdening the user code with any protocol knowledge.

Return may be -1 for a fatal error needing connection close, or a
positive number reflecting the amount of bytes actually sent.  This
can be less than the requested number of bytes due to OS memory
pressure at any given time.


Name:

lws_hdr_fragment_length - 

Synopsis:

int lws_hdr_fragment_length (struct lws * wsi,
                             enum lws_token_indexes h,
                             int frag_idx);

Arguments:

wsi
	websocket connection

h
	which header index we are interested in

frag_idx
	which fragment of @h we want to get the length of


Description:

The returned length does not include the space for a
terminating '\0'


Name:

lws_hdr_total_length - 

Synopsis:

int lws_hdr_total_length (struct lws * wsi,
                          enum lws_token_indexes h);

Arguments:

wsi
	websocket connection

h
	which header index we are interested in


Description:

The returned length does not include the space for a
terminating '\0'


Name:

lws_hdr_copy_fragment - 

Synopsis:

int lws_hdr_copy_fragment (struct lws * wsi,
                           char * dst,
                           int len,
                           enum lws_token_indexes h,
                           int frag_idx);

Arguments:

wsi
	websocket connection

dst
	destination buffer

len
	length of destination buffer

h
	which header index we are interested in

frag_idx
	-- undescribed --

Description:

The buffer length len must include space for an additional
terminating '\0', or it will fail returning -1.
If the requested fragment index is not present, it fails
returning -1.


Name:

lws_hdr_copy - 

Synopsis:

int lws_hdr_copy (struct lws * wsi,
                  char * dst,
                  int len,
                  enum lws_token_indexes h);

Arguments:

wsi
	websocket connection

dst
	destination buffer

len
	length of destination buffer

h
	which header index we are interested in


Description:

The buffer length len must include space for an additional
terminating '\0', or it will fail returning -1.


Name:

lws_frame_is_binary - 

Synopsis:

int lws_frame_is_binary (struct lws * wsi);

Arguments:

wsi
	the connection we are inquiring about


Description:

This is intended to be called from the LWS_CALLBACK_RECEIVE callback if
it's interested to see if the frame it's dealing with was sent in binary
mode.


Name:

lws_remaining_packet_payload - Bytes to come before "overall" rx packet is complete

Synopsis:

size_t lws_remaining_packet_payload (struct lws * wsi);

Arguments:

wsi
	Websocket instance (available from user callback)


Description:

This function is intended to be called from the callback if the
user code is interested in "complete packets" from the client.
libwebsockets just passes through payload as it comes and issues a buffer
additionally when it hits a built-in limit.  The LWS_CALLBACK_RECEIVE
callback handler can use this API to find out if the buffer it has just
been given is the last piece of a "complete packet" from the client --
when that is the case lws_remaining_packet_payload will return
0.

Many protocols won't care becuse their packets are always small.


Name:

lws_callback_on_writable - Request a callback when this socket becomes able to be written to without blocking

Synopsis:

int lws_callback_on_writable (struct lws * wsi);

Arguments:

wsi
	Websocket connection instance to get callback for




Name:

lws_callback_on_writable_all_protocol_vhost - Request a callback for all connections using the given protocol when it becomes possible to write to each socket without blocking in turn.

Synopsis:

int lws_callback_on_writable_all_protocol_vhost (const struct lws_vhost * vhost,
                                                 const struct lws_protocols * protocol);

Arguments:

vhost
	Only consider connections on this lws_vhost

protocol
	Protocol whose connections will get callbacks


Description:


This calls back connections with the same protocol ON THE SAME
VHOST ONLY.


Name:

lws_callback_on_writable_all_protocol - Request a callback for all connections using the given protocol when it becomes possible to write to each socket without blocking in turn.

Synopsis:

int lws_callback_on_writable_all_protocol (const struct lws_context * context,
                                           const struct lws_protocols * protocol);

Arguments:

context
	lws_context

protocol
	Protocol whose connections will get callbacks


Description:


This calls back any connection using the same protocol on ANY
VHOST.


Name:

lws_http_transaction_completed - wait for new http transaction or close

Synopsis:

int LWS_WARN_UNUSED_RESULT lws_http_transaction_completed (struct lws * wsi);

Arguments:

wsi
	websocket connection


Description:

Returns 1 if the HTTP connection must close now
Returns 0 and resets connection to wait for new HTTP header /
transaction if possible


Name:

lws_adopt_socket - adopt foreign socket as if listen socket accepted it

Synopsis:

struct lws * lws_adopt_socket (struct lws_context * context,
                               lws_sockfd_type accept_fd);

Arguments:

context
	lws context

accept_fd
	fd of already-accepted socket to adopt


Description:

Either returns new wsi bound to accept_fd, or closes accept_fd and
returns NULL, having cleaned up any new wsi pieces.

LWS adopts the socket in http serving mode, it's ready to accept an upgrade
to ws or just serve http.


Name:

lws_adopt_socket_readbuf - adopt foreign socket and first rx as if listen socket accepted it

Synopsis:

LWS_EXTERN struct lws * lws_adopt_socket_readbuf (struct lws_context * context,
                                                  lws_sockfd_type accept_fd,
                                                  const char * readbuf,
                                                  size_t len);

Arguments:

context
	lws context

accept_fd
	fd of already-accepted socket to adopt

readbuf
	NULL or pointer to data that must be drained before reading from
accept_fd

len
	The length of the data held at @readbuf


Description:

Either returns new wsi bound to accept_fd, or closes accept_fd and
returns NULL, having cleaned up any new wsi pieces.

LWS adopts the socket in http serving mode, it's ready to accept an upgrade
to ws or just serve http.

If your external code did not already read from the socket, you can use
lws_adopt_socket instead.

This api is guaranteed to use the data at readbuf first, before reading from
the socket.

readbuf is limited to the size of the ah rx buf, currently 2048 bytes.


Name:

lws_serve_http_file - Send a file back to the client using http

Synopsis:

int lws_serve_http_file (struct lws * wsi,
                         const char * file,
                         const char * content_type,
                         const char * other_headers,
                         int other_headers_len);

Arguments:

wsi
	Websocket instance (available from user callback)

file
	The file to issue over http

content_type
	The http content type, eg, text/html

other_headers
	NULL or pointer to header string

other_headers_len
	length of the other headers if non-NULL


Description:

This function is intended to be called from the callback in response
to http requests from the client.  It allows the callback to issue
local files down the http link in a single step.

Returning <0 indicates error and the wsi should be closed.  Returning
>0 indicates the file was completely sent and
lws_http_transaction_completed called on the wsi (and close if != 0)
==0 indicates the file transfer is started and needs more service later,
the wsi should be left alone.


Name:

lws_service_fd_tsi - Service polled socket with something waiting

Synopsis:

int lws_service_fd_tsi (struct lws_context * context,
                        struct lws_pollfd * pollfd,
                        int tsi);

Arguments:

context
	Websocket context

pollfd
	The pollfd entry describing the socket fd and which events
happened.

tsi
	-- undescribed --

Description:

This function takes a pollfd that has POLLIN or POLLOUT activity and
services it according to the state of the associated
struct lws.

The one call deals with all "service" that might happen on a socket
including listen accepts, http files as well as websocket protocol.

If a pollfd says it has something, you can just pass it to
lws_service_fd whether it is a socket handled by lws or not.
If it sees it is a lws socket, the traffic will be handled and
pollfd->revents will be zeroed now.

If the socket is foreign to lws, it leaves revents alone.  So you can
see if you should service yourself by checking the pollfd revents
after letting lws try to service it.


Name:

lws_service - Service any pending websocket activity

Synopsis:

int lws_service (struct lws_context * context,
                 int timeout_ms);

Arguments:

context
	Websocket context

timeout_ms
	Timeout for poll; 0 means return immediately if nothing needed
service otherwise block and service immediately, returning
after the timeout if nothing needed service.


Description:

This function deals with any pending websocket traffic, for three
kinds of event.  It handles these events on both server and client
types of connection the same.

1) Accept new connections to our context's server

2) Call the receive callback for incoming frame data received by
server or client connections.

You need to call this service function periodically to all the above
functions to happen; if your application is single-threaded you can
just call it in your main event loop.

Alternatively you can fork a new process that asynchronously handles
calling this service in a loop.  In that case you are happy if this
call blocks your thread until it needs to take care of something and
would call it with a large nonzero timeout.  Your loop then takes no
CPU while there is nothing happening.

If you are calling it in a single-threaded app, you don't want it to
wait around blocking other things in your loop from happening, so you
would call it with a timeout_ms of 0, so it returns immediately if
nothing is pending, or as soon as it services whatever was pending.


struct lws_plat_file_ops - Platform-specific file operations

struct lws_plat_file_ops {
	lws_filefd_type (* open) (struct lws *wsi, const char *filename,unsigned long *filelen, int flags);
	int (* close) (struct lws *wsi, lws_filefd_type fd);
	unsigned long (* seek_cur) (struct lws *wsi, lws_filefd_type fd,long offset_from_cur_pos);
	int (* read) (struct lws *wsi, lws_filefd_type fd, unsigned long *amount,unsigned char *buf, unsigned long len);
	int (* write) (struct lws *wsi, lws_filefd_type fd, unsigned long *amount,unsigned char *buf, unsigned long len);
};

Members:

open
	Open file (always binary access if plat supports it)
filelen is filled on exit to be the length of the file
flags should be set to O_RDONLY or O_RDWR

close
	Close file

seek_cur
	Seek from current position

read
	Read fron file *amount is set on exit to amount read

write
	Write to file *amount is set on exit as amount written



Description:


These provide platform-agnostic ways to deal with filesystem access in the
library and in the user code.


Name:

lws_callback_function - User server actions

Synopsis:

typedef int lws_callback_function (struct lws * wsi,
                                   enum lws_callback_reasons reason,
                                   void * user,
                                   void * in,
                                   size_t len);

Arguments:

wsi
	Opaque websocket instance pointer

reason
	The reason for the call

user
	Pointer to per-session user data allocated by library

in
	Pointer used for some callback reasons

len
	Length set for some callback reasons


Description:

This callback is the way the user controls what is served.  All the
protocol detail is hidden and handled by the library.

For each connection / session there is user data allocated that is
pointed to by "user".  You set the size of this user data area when
the library is initialized with lws_create_server.

You get an opportunity to initialize user data when called back with
LWS_CALLBACK_ESTABLISHED reason.
LWS_CALLBACK_ESTABLISHED:

after the server completes a handshake with
an incoming client.  If you built the library
with ssl support, in is a pointer to the
ssl struct associated with the connection or
NULL.
LWS_CALLBACK_CLIENT_CONNECTION_ERROR:

the request client connection has
been unable to complete a handshake with the remote server.  If
in is non-NULL, you can find an error string of length len where
it points to.
LWS_CALLBACK_CLIENT_FILTER_PRE_ESTABLISH:

this is the last chance for the
client user code to examine the http headers
and decide to reject the connection.  If the
content in the headers is interesting to the
client (url, etc) it needs to copy it out at
this point since it will be destroyed before
the CLIENT_ESTABLISHED call
LWS_CALLBACK_CLIENT_ESTABLISHED:

after your client connection completed
a handshake with the remote server
LWS_CALLBACK_CLOSED:

when the websocket session ends
LWS_CALLBACK_CLOSED_HTTP:

when a HTTP (non-websocket) session ends
LWS_CALLBACK_RECEIVE:

data has appeared for this server endpoint from a
remote client, it can be found at *in and is
len bytes long
LWS_CALLBACK_CLIENT_RECEIVE_PONG:

if you elected to see PONG packets,
they appear with this callback reason.  PONG
packets only exist in 04+ protocol
LWS_CALLBACK_CLIENT_RECEIVE:

data has appeared from the server for the
client connection, it can be found at *in and
is len bytes long
LWS_CALLBACK_HTTP:

an http request has come from a client that is not
asking to upgrade the connection to a websocket
one.  This is a chance to serve http content,
for example, to send a script to the client
which will then open the websockets connection.
in points to the URI path requested and
lws_serve_http_file makes it very
simple to send back a file to the client.
Normally after sending the file you are done
with the http connection, since the rest of the
activity will come by websockets from the script
that was delivered by http, so you will want to
return 1; to close and free up the connection.
That's important because it uses a slot in the
total number of client connections allowed set
by MAX_CLIENTS.
LWS_CALLBACK_HTTP_BODY:

the next len bytes data from the http
request body HTTP connection is now available in in.
LWS_CALLBACK_HTTP_BODY_COMPLETION:

the expected amount of http request
body has been delivered
LWS_CALLBACK_HTTP_WRITEABLE:

you can write more down the http protocol
link now.
LWS_CALLBACK_HTTP_FILE_COMPLETION:

a file requested to be send down
http link has completed.
LWS_CALLBACK_SERVER_WRITEABLE:

If you call
lws_callback_on_writable on a connection, you will
get one of these callbacks coming when the connection socket
is able to accept another write packet without blocking.
If it already was able to take another packet without blocking,
you'll get this callback at the next call to the service loop
function.  Notice that CLIENTs get LWS_CALLBACK_CLIENT_WRITEABLE
and servers get LWS_CALLBACK_SERVER_WRITEABLE.
LWS_CALLBACK_FILTER_NETWORK_CONNECTION:

called when a client connects to
the server at network level; the connection is accepted but then
passed to this callback to decide whether to hang up immediately
or not, based on the client IP.  in contains the connection
socket's descriptor. Since the client connection information is
not available yet, wsi still pointing to the main server socket.
Return non-zero to terminate the connection before sending or
receiving anything. Because this happens immediately after the
network connection from the client, there's no websocket protocol
selected yet so this callback is issued only to protocol 0.
LWS_CALLBACK_SERVER_NEW_CLIENT_INSTANTIATED:

A new client just had
been connected, accepted, and instantiated into the pool. This
callback allows setting any relevant property to it. Because this
happens immediately after the instantiation of a new client,
there's no websocket protocol selected yet so this callback is
issued only to protocol 0. Only wsi is defined, pointing to the
new client, and the return value is ignored.
LWS_CALLBACK_FILTER_HTTP_CONNECTION:

called when the request has
been received and parsed from the client, but the response is
not sent yet.  Return non-zero to disallow the connection.
user is a pointer to the connection user space allocation,
in is the URI, eg, "/"
In your handler you can use the public APIs
lws_hdr_total_length / lws_hdr_copy to access all of the
headers using the header enums lws_token_indexes from
libwebsockets.h to check for and read the supported header
presence and content before deciding to allow the http
connection to proceed or to kill the connection.
LWS_CALLBACK_FILTER_PROTOCOL_CONNECTION:

called when the handshake has
been received and parsed from the client, but the response is
not sent yet.  Return non-zero to disallow the connection.
user is a pointer to the connection user space allocation,
in is the requested protocol name
In your handler you can use the public APIs
lws_hdr_total_length / lws_hdr_copy to access all of the
headers using the header enums lws_token_indexes from
libwebsockets.h to check for and read the supported header
presence and content before deciding to allow the handshake
to proceed or to kill the connection.
LWS_CALLBACK_OPENSSL_LOAD_EXTRA_CLIENT_VERIFY_CERTS:

if configured for
including OpenSSL support, this callback allows your user code
to perform extra SSL_CTX_load_verify_locations or similar
calls to direct OpenSSL where to find certificates the client
can use to confirm the remote server identity.  user is the
OpenSSL SSL_CTX*
LWS_CALLBACK_OPENSSL_LOAD_EXTRA_SERVER_VERIFY_CERTS:

if configured for
including OpenSSL support, this callback allows your user code
to load extra certificates into the server which allow it to
verify the validity of certificates returned by clients.  user
is the server's OpenSSL SSL_CTX*
LWS_CALLBACK_OPENSSL_CONTEXT_REQUIRES_PRIVATE_KEY:

if configured for
including OpenSSL support but no private key file has been
specified (ssl_private_key_filepath is NULL), this is called to
allow the user to set the private key directly via libopenssl
and perform further operations if required; this might be useful
in situations where the private key is not directly accessible
by the OS, for example if it is stored on a smartcard
user is the server's OpenSSL SSL_CTX*
LWS_CALLBACK_OPENSSL_PERFORM_CLIENT_CERT_VERIFICATION:

if the
libwebsockets context was created with the option
LWS_SERVER_OPTION_REQUIRE_VALID_OPENSSL_CLIENT_CERT, then this
callback is generated during OpenSSL verification of the cert
sent from the client.  It is sent to protocol[0] callback as
no protocol has been negotiated on the connection yet.
Notice that the libwebsockets context and wsi are both NULL
during this callback.  See
http:

//www.openssl.org/docs/ssl/SSL_CTX_set_verify.html
to understand more detail about the OpenSSL callback that
generates this libwebsockets callback and the meanings of the
arguments passed.  In this callback, user is the x509_ctx,
in is the ssl pointer and len is preverify_ok
Notice that this callback maintains libwebsocket return
conventions, return 0 to mean the cert is OK or 1 to fail it.
This also means that if you don't handle this callback then
the default callback action of returning 0 allows the client
certificates.
LWS_CALLBACK_CLIENT_APPEND_HANDSHAKE_HEADER:

this callback happens
when a client handshake is being compiled.  user is NULL,
in is a char **, it's pointing to a char * which holds the
next location in the header buffer where you can add
headers, and len is the remaining space in the header buffer,
which is typically some hundreds of bytes.  So, to add a canned
cookie, your handler code might look similar to:

char **p = (char **)in;

if (len < 100)
return 1;

*p += sprintf(*p, "Cookie: a=b\x0d\x0a");

return 0;

Notice if you add anything, you just have to take care about
the CRLF on the line you added.  Obviously this callback is
optional, if you don't handle it everything is fine.

Notice the callback is coming to protocols[0] all the time,
because there is no specific protocol handshook yet.
LWS_CALLBACK_CONFIRM_EXTENSION_OKAY:

When the server handshake code
sees that it does support a requested extension, before
accepting the extension by additing to the list sent back to
the client it gives this callback just to check that it's okay
to use that extension.  It calls back to the requested protocol
and with in being the extension name, len is 0 and user is
valid.  Note though at this time the ESTABLISHED callback hasn't
happened yet so if you initialize user content there, user
content during this callback might not be useful for anything.
Notice this callback comes to protocols[0].
LWS_CALLBACK_CLIENT_CONFIRM_EXTENSION_SUPPORTED:

When a client
connection is being prepared to start a handshake to a server,
each supported extension is checked with protocols[0] callback
with this reason, giving the user code a chance to suppress the
claim to support that extension by returning non-zero.  If
unhandled, by default 0 will be returned and the extension
support included in the header to the server.  Notice this
callback comes to protocols[0].
LWS_CALLBACK_PROTOCOL_INIT:

One-time call per protocol so it can
do initial setup / allocations etc
LWS_CALLBACK_PROTOCOL_DESTROY:

One-time call per protocol indicating
this protocol won't get used at all after this callback, the
context is getting destroyed.  Take the opportunity to
deallocate everything that was allocated by the protocol.
LWS_CALLBACK_WSI_CREATE:

outermost (earliest) wsi create notification
LWS_CALLBACK_WSI_DESTROY:

outermost (latest) wsi destroy notification

The next five reasons are optional and only need taking care of if you
will be integrating libwebsockets sockets into an external polling
array.

For these calls, in points to a struct lws_pollargs that
contains fd, events and prev_events members
LWS_CALLBACK_ADD_POLL_FD:

libwebsocket deals with its poll loop
internally, but in the case you are integrating with another
server you will need to have libwebsocket sockets share a
polling array with the other server.  This and the other
POLL_FD related callbacks let you put your specialized
poll array interface code in the callback for protocol 0, the
first protocol you support, usually the HTTP protocol in the
serving case.
This callback happens when a socket needs to be
added to the polling loop:

in points to a struct
lws_pollargs; the fd member of the struct is the file
descriptor, and events contains the active events.

If you are using the internal polling loop (the "service"
callback), you can just ignore these callbacks.
LWS_CALLBACK_DEL_POLL_FD:

This callback happens when a socket descriptor
needs to be removed from an external polling array.  in is
again the struct lws_pollargs containing the fd member
to be removed.  If you are using the internal polling
loop, you can just ignore it.
LWS_CALLBACK_CHANGE_MODE_POLL_FD:

This callback happens when
libwebsockets wants to modify the events for a connectiion.
in is the struct lws_pollargs with the fd to change.
The new event mask is in events member and the old mask is in
the prev_events member.
If you are using the internal polling loop, you can just ignore
it.
LWS_CALLBACK_UNLOCK_POLL:

These allow the external poll changes driven
by libwebsockets to participate in an external thread locking
scheme around the changes, so the whole thing is threadsafe.
These are called around three activities in the library,
- inserting a new wsi in the wsi / fd table (len=1)
- deleting a wsi from the wsi / fd table (len=1)
- changing a wsi's POLLIN/OUT state (len=0)
Locking and unlocking external synchronization objects when
len == 1 allows external threads to be synchronized against
wsi lifecycle changes if it acquires the same lock for the
duration of wsi dereference from the other thread context.
LWS_CALLBACK_WS_PEER_INITIATED_CLOSE:

The peer has sent an unsolicited Close WS packet.  in and
len are the optional close code (first 2 bytes, network
order) and the optional additional information which is not
defined in the standard, and may be a string or non-human-
readble data.
If you return 0 lws will echo the close and then close the
connection.  If you return nonzero lws will just close the
connection.


Name:

lws_extension_callback_function - Hooks to allow extensions to operate

Synopsis:

typedef int lws_extension_callback_function (struct lws_context * context,
                                             const struct lws_extension * ext,
                                             struct lws * wsi,
                                             enum lws_extension_callback_reasons reason,
                                             void * user,
                                             void * in,
                                             size_t len);

Arguments:

context
	Websockets context

ext
	This extension

wsi
	Opaque websocket instance pointer

reason
	The reason for the call

user
	Pointer to ptr to per-session user data allocated by library

in
	Pointer used for some callback reasons

len
	Length set for some callback reasons


Description:

Each extension that is active on a particular connection receives
callbacks during the connection lifetime to allow the extension to
operate on websocket data and manage itself.

Libwebsockets takes care of allocating and freeing "user" memory for
each active extension on each connection.  That is what is pointed to
by the user parameter.
LWS_EXT_CB_CONSTRUCT:

called when the server has decided to
select this extension from the list provided by the client,
just before the server will send back the handshake accepting
the connection with this extension active.  This gives the
extension a chance to initialize its connection context found
in user.
LWS_EXT_CB_CLIENT_CONSTRUCT:

same as LWS_EXT_CB_CONSTRUCT
but called when client is instantiating this extension.  Some
extensions will work the same on client and server side and then
you can just merge handlers for both CONSTRUCTS.
LWS_EXT_CB_DESTROY:

called when the connection the extension was
being used on is about to be closed and deallocated.  It's the
last chance for the extension to deallocate anything it has
allocated in the user data (pointed to by user) before the
user data is deleted.  This same callback is used whether you
are in client or server instantiation context.
LWS_EXT_CB_PACKET_RX_PREPARSE:

when this extension was active on
a connection, and a packet of data arrived at the connection,
it is passed to this callback to give the extension a chance to
change the data, eg, decompress it.  user is pointing to the
extension's private connection context data, in is pointing
to an lws_tokens struct, it consists of a char * pointer called
token, and an int called token_len.  At entry, these are
set to point to the received buffer and set to the content
length.  If the extension will grow the content, it should use
a new buffer allocated in its private user context data and
set the pointed-to lws_tokens members to point to its buffer.
LWS_EXT_CB_PACKET_TX_PRESEND:

this works the same way as
LWS_EXT_CB_PACKET_RX_PREPARSE above, except it gives the
extension a chance to change websocket data just before it will
be sent out.  Using the same lws_token pointer scheme in in,
the extension can change the buffer and the length to be
transmitted how it likes.  Again if it wants to grow the
buffer safely, it should copy the data into its own buffer and
set the lws_tokens token pointer to it.


struct lws_protocols - List of protocols and handlers server supports.

struct lws_protocols {
	const char * name;
	lws_callback_function * callback;
	size_t per_session_data_size;
	size_t rx_buffer_size;
	unsigned int id;
	void * user;
};

Members:

name
	Protocol name that must match the one given in the client
Javascript new WebSocket(url, 'protocol') name.

callback
	The service callback used for this protocol.  It allows the
service action for an entire protocol to be encapsulated in
the protocol-specific callback

per_session_data_size
	Each new connection using this protocol gets
this much memory allocated on connection establishment and
freed on connection takedown.  A pointer to this per-connection
allocation is passed into the callback in the 'user' parameter

rx_buffer_size
	if you want atomic frames delivered to the callback, you
should set this to the size of the biggest legal frame that
you support.  If the frame size is exceeded, there is no
error, but the buffer will spill to the user callback when
full, which you can detect by using
lws_remaining_packet_payload().  Notice that you
just talk about frame size here, the LWS_PRE
and post-padding are automatically also allocated on top.

id
	ignored by lws, but useful to contain user information bound
to the selected protocol.  For example if this protocol was
called "myprotocol-v2", you might set id to 2, and the user
code that acts differently according to the version can do so by
switch (wsi->protocol->id), user code might use some bits as
capability flags based on selected protocol version, etc.

user
	User provided context data at the protocol level.
Accessible via lws_get_protocol(wsi)->user
This should not be confused with wsi->user, it is not the same.
The library completely ignores any value in here.



Description:

This structure represents one protocol supported by the server.  An
array of these structures is passed to lws_create_server
allows as many protocols as you like to be handled by one server.

The first protocol given has its callback used for user callbacks when
there is no agreed protocol name, that's true during HTTP part of the
connection and true if the client did not send a Protocol:

header.


struct lws_ext_options - Option arguments to the extension.  These are used in the negotiation at ws upgrade time. The helper function lws_ext_parse_options() uses these to generate callbacks

struct lws_ext_options {
	const char * name;
	enum lws_ext_options_types type;
};

Members:

name
	Option name, eg, "server_no_context_takeover"

type
	What kind of args the option can take





struct lws_extension - An extension we know how to cope with

struct lws_extension {
	const char * name;
	lws_extension_callback_function * callback;
	const char * client_offer;
};

Members:

name
	Formal extension name, eg, "permessage-deflate"

callback
	Service callback

client_offer
	String containing exts and options client offers





struct lws_context_creation_info - parameters to create context with

struct lws_context_creation_info {
	int port;
	const char * iface;
	const struct lws_protocols * protocols;
	const struct lws_extension * extensions;
	const struct lws_token_limits * token_limits;
	const char * ssl_cert_filepath;
	const char * ssl_private_key_filepath;
	const char * ssl_ca_filepath;
	const char * ssl_cipher_list;
	const char * http_proxy_address;
	unsigned int http_proxy_port;
	int gid;
	int uid;
	unsigned int options;
	void * user;
	int ka_time;
	int ka_probes;
	int ka_interval;
#ifdef LWS_OPENSSL_SUPPORT
	void * provided_client_ssl_ctx;
#else
	void * provided_client_ssl_ctx;
#endif
	short max_http_header_data;
	short max_http_header_pool;
	unsigned int count_threads;
	unsigned int fd_limit_per_thread;
	unsigned int timeout_secs;
	const char * ecdh_curve;
	const char * vhost_name;
	const char *const * plugin_dirs;
	const struct lws_protocol_vhost_options * pvo;
	int keepalive_timeout;
	const char * log_filepath;
	const struct lws_http_mount * mounts;
	const char * server_string;
};

Members:

port
	VHOST: Port to listen on... you can use CONTEXT_PORT_NO_LISTEN to
suppress listening on any port, that's what you want if you are
not running a websocket server at all but just using it as a
client

iface
	VHOST: NULL to bind the listen socket to all interfaces, or the
interface name, eg, "eth2"
If options specifies LWS_SERVER_OPTION_UNIX_SOCK, this member is
the pathname of a UNIX domain socket. you can use the UNIX domain
sockets in abstract namespace, by prepending an @ symbole to the
socket name.

protocols
	VHOST: Array of structures listing supported protocols and a protocol-
specific callback for each one.  The list is ended with an
entry that has a NULL callback pointer.
It's not const because we write the owning_server member

extensions
	VHOST: NULL or array of lws_extension structs listing the
extensions this context supports.  If you configured with
--without-extensions, you should give NULL here.

token_limits
	CONTEXT: NULL or struct lws_token_limits pointer which is initialized
with a token length limit for each possible WSI_TOKEN_***

ssl_cert_filepath
	VHOST: If libwebsockets was compiled to use ssl, and you want
to listen using SSL, set to the filepath to fetch the
server cert from, otherwise NULL for unencrypted

ssl_private_key_filepath
	VHOST: filepath to private key if wanting SSL mode;
if this is set to NULL but sll_cert_filepath is set, the
OPENSSL_CONTEXT_REQUIRES_PRIVATE_KEY callback is called
to allow setting of the private key directly via openSSL
library calls

ssl_ca_filepath
	VHOST: CA certificate filepath or NULL

ssl_cipher_list
	VHOST: List of valid ciphers to use (eg,
"RC4-MD5:RC4-SHA:AES128-SHA:AES256-SHA:HIGH:!DSS:!aNULL"
or you can leave it as NULL to get "DEFAULT"

http_proxy_address
	VHOST: If non-NULL, attempts to proxy via the given address.
If proxy auth is required, use format
"username:password@server:port"

http_proxy_port
	VHOST: If http_proxy_address was non-NULL, uses this port at
the address

gid
	CONTEXT: group id to change to after setting listen socket, or -1.

uid
	CONTEXT: user id to change to after setting listen socket, or -1.

options
	VHOST + CONTEXT: 0, or LWS_SERVER_OPTION_... bitfields

user
	CONTEXT: optional user pointer that can be recovered via the context
pointer using lws_context_user

ka_time
	CONTEXT: 0 for no keepalive, otherwise apply this keepalive timeout to
all libwebsocket sockets, client or server

ka_probes
	CONTEXT: if ka_time was nonzero, after the timeout expires how many
times to try to get a response from the peer before giving up
and killing the connection

ka_interval
	CONTEXT: if ka_time was nonzero, how long to wait before each ka_probes
attempt

provided_client_ssl_ctx
	CONTEXT: If non-null, swap out libwebsockets ssl
implementation for the one provided by provided_ssl_ctx.
Libwebsockets no longer is responsible for freeing the context
if this option is selected.

provided_client_ssl_ctx
	CONTEXT: If non-null, swap out libwebsockets ssl
implementation for the one provided by provided_ssl_ctx.
Libwebsockets no longer is responsible for freeing the context
if this option is selected.

max_http_header_data
	CONTEXT: The max amount of header payload that can be handled
in an http request (unrecognized header payload is dropped)

max_http_header_pool
	CONTEXT: The max number of connections with http headers that
can be processed simultaneously (the corresponding memory is
allocated for the lifetime of the context).  If the pool is
busy new incoming connections must wait for accept until one
becomes free.

count_threads
	CONTEXT: how many contexts to create in an array, 0 = 1

fd_limit_per_thread
	CONTEXT: nonzero means restrict each service thread to this
many fds, 0 means the default which is divide the process fd
limit by the number of threads.

timeout_secs
	VHOST: various processes involving network roundtrips in the
library are protected from hanging forever by timeouts.  If
nonzero, this member lets you set the timeout used in seconds.
Otherwise a default timeout is used.

ecdh_curve
	VHOST: if NULL, defaults to initializing server with "prime256v1"

vhost_name
	VHOST: name of vhost, must match external DNS name used to
access the site, like "warmcat.com" as it's used to match

plugin_dirs
	CONTEXT: NULL, or NULL-terminated array of directories to
scan for lws protocol plugins at context creation time

pvo
	VHOST: pointer to optional linked list of per-vhost
options made accessible to protocols

keepalive_timeout
	VHOST: (default = 0 = 60s) seconds to allow remote
client to hold on to an idle HTTP/1.1 connection

log_filepath
	VHOST: filepath to append logs to... this is opened before
any dropping of initial privileges

mounts
	VHOST: optional linked list of mounts for this vhost

server_string
	CONTEXT: string used in HTTP headers to identify server
software, if NULL, "libwebsockets".



Description:


This is also used to create vhosts.... if LWS_SERVER_OPTION_EXPLICIT_VHOSTS
is not given, then for backwards compatibility one vhost is created at
context-creation time using the info from this struct.

If LWS_SERVER_OPTION_EXPLICIT_VHOSTS is given, then no vhosts are created
at the same time as the context, they are expected to be created afterwards.
Host:

header and / or SNI name for SSL.


struct lws_client_connect_info - parameters to connect with when using lws_client_connect_via_info()

struct lws_client_connect_info {
	struct lws_context * context;
	const char * address;
	int port;
	int ssl_connection;
	const char * path;
	const char * host;
	const char * origin;
	const char * protocol;
	int ietf_version_or_minus_one;
	void * userdata;
	const struct lws_extension * client_exts;
	const char * method;
	struct lws * parent_wsi;
	const char * uri_replace_from;
	const char * uri_replace_to;
	struct lws_vhost * vhost;
};

Members:

context
	lws context to create connection in

address
	remote address to connect to

port
	remote port to connect to

ssl_connection
	nonzero for ssl

path
	uri path

host
	content of host header

origin
	content of origin header

protocol
	list of ws protocols

ietf_version_or_minus_one
	currently leave at 0 or -1

userdata
	if non-NULL, use this as wsi user_data instead of malloc it

client_exts
	array of extensions that may be used on connection

method
	if non-NULL, do this http method instead of ws[s] upgrade.
use "GET" to be a simple http client connection

parent_wsi
	if another wsi is responsible for this connection, give it here.
this is used to make sure if the parent closes so do any
child connections first.

uri_replace_from
	if non-NULL, when this string is found in URIs in
text/html content-encoding, it's replaced with @uri_replace_to

uri_replace_to
	see above

vhost
	vhost to bind to (used to determine related SSL_CTX)





Name:

lws_close_reason - Set reason and aux data to send with Close packet If you are going to return nonzero from the callback requesting the connection to close, you can optionally call this to set the reason the peer will be told if possible.

Synopsis:

LWS_EXTERN void lws_close_reason (struct lws * wsi,
                                  enum lws_close_status status,
                                  unsigned char * buf,
                                  size_t len);

Arguments:

wsi
	The websocket connection to set the close reason on

status
	A valid close status from websocket standard

buf
	NULL or buffer containing up to 124 bytes of auxiliary data

len
	Length of data in @buf to send




Name:

lws_snprintf - 

Synopsis:

LWS_EXTERN int lws_snprintf (char * str,
                             size_t size,
                             const char * format,
                              ...);

Arguments:

str
	-- undescribed --
size
	-- undescribed --
format
	-- undescribed --
...
	variable arguments

Description:


\param str: destination buffer
\param size: bytes left in destination buffer
\param format: format string
\param ...: args for format

This lets you correctly truncate buffers by concatenating lengths, if you
reach the limit the reported length doesn't exceed the limit.


