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pbuf.h File Reference
`#include "lwip/opt.h"`
`#include "lwip/err.h"`

## Data Structures

struct | pbuf
struct | pbuf_rom
struct | pbuf_custom

## Macros

#define | LWIP_SUPPORT_CUSTOM_PBUF ((IP_FRAG && !LWIP_NETIF_TX_SINGLE_PBUF) || (LWIP_IPV6 && LWIP_IPV6_FRAG))
#define | PBUF_NEEDS_COPY(p)
#define | PBUF_TYPE_FLAG_STRUCT_DATA_CONTIGUOUS 0x80
#define | PBUF_TYPE_FLAG_DATA_VOLATILE 0x40
#define | PBUF_TYPE_ALLOC_SRC_MASK 0x0F
#define | PBUF_ALLOC_FLAG_RX 0x0100
#define | PBUF_ALLOC_FLAG_DATA_CONTIGUOUS 0x0200
#define | PBUF_TYPE_ALLOC_SRC_MASK_APP_MIN 0x03
#define | PBUF_TYPE_ALLOC_SRC_MASK_APP_MAX PBUF_TYPE_ALLOC_SRC_MASK
#define | PBUF_FLAG_PUSH 0x01U
#define | PBUF_FLAG_IS_CUSTOM 0x02U
#define | PBUF_FLAG_MCASTLOOP 0x04U
#define | PBUF_FLAG_LLBCAST 0x08U
#define | PBUF_FLAG_LLMCAST 0x10U
#define | PBUF_FLAG_TCP_FIN 0x20U
#define | PBUF_POOL_FREE_OOSEQ 1

## Typedefs

typedef void(* | pbuf_free_custom_fn) (struct pbuf *p)

## Enumerations

enum | pbuf_layer { PBUF_TRANSPORT = 0 + (14 + 0 )+ 40 + 20 , PBUF_IP = 0 + (14 + 0 )+ 40 , PBUF_LINK = 0 + (14 + 0 ) , PBUF_RAW_TX = 0 , PBUF_RAW = 0 }
enum | pbuf_type { PBUF_RAM = ( 0x0200 | 0x80 | 0x00 ) , PBUF_ROM = 0x01 , PBUF_REF = ( 0x40 | 0x01 ) , PBUF_POOL = ( 0x0100 | 0x80 | 0x02 ) }

## Functions

struct pbuf * | pbuf_alloc (pbuf_layer l, u16_t length, pbuf_type type)
struct pbuf * | pbuf_alloc_reference (void *payload, u16_t length, pbuf_type type)
struct pbuf * | pbuf_alloced_custom (pbuf_layer l, u16_t length, pbuf_type type, struct pbuf_custom *p, void *payload_mem, u16_t payload_mem_len)
void | pbuf_realloc (struct pbuf *p, u16_t size)
u8_t | pbuf_header (struct pbuf *p, s16_t header_size)
u8_t | pbuf_header_force (struct pbuf *p, s16_t header_size)
u8_t | pbuf_add_header (struct pbuf *p, size_t header_size_increment)
u8_t | pbuf_add_header_force (struct pbuf *p, size_t header_size_increment)
u8_t | pbuf_remove_header (struct pbuf *p, size_t header_size)
struct pbuf * | pbuf_free_header (struct pbuf *q, u16_t size)
void | pbuf_ref (struct pbuf *p)
u8_t | pbuf_free (struct pbuf *p)
u16_t | pbuf_clen (const struct pbuf *p)
void | pbuf_cat (struct pbuf *head, struct pbuf *tail)
void | pbuf_chain (struct pbuf *head, struct pbuf *tail)
struct pbuf * | pbuf_dechain (struct pbuf *p)
err_t | pbuf_copy (struct pbuf *p_to, const struct pbuf *p_from)
err_t | pbuf_copy_partial_pbuf (struct pbuf *p_to, const struct pbuf *p_from, u16_t copy_len, u16_t offset)
u16_t | pbuf_copy_partial (const struct pbuf *p, void *dataptr, u16_t len, u16_t offset)
void * | pbuf_get_contiguous (const struct pbuf *p, void *buffer, size_t bufsize, u16_t len, u16_t offset)
err_t | pbuf_take (struct pbuf *buf, const void *dataptr, u16_t len)
err_t | pbuf_take_at (struct pbuf *buf, const void *dataptr, u16_t len, u16_t offset)
struct pbuf * | pbuf_skip (struct pbuf *in, u16_t in_offset, u16_t *out_offset)
struct pbuf * | pbuf_coalesce (struct pbuf *p, pbuf_layer layer)
struct pbuf * | pbuf_clone (pbuf_layer l, pbuf_type type, struct pbuf *p)
u8_t | pbuf_get_at (const struct pbuf *p, u16_t offset)
int | pbuf_try_get_at (const struct pbuf *p, u16_t offset)
void | pbuf_put_at (struct pbuf *p, u16_t offset, u8_t data)
u16_t | pbuf_memcmp (const struct pbuf *p, u16_t offset, const void *s2, u16_t n)
u16_t | pbuf_memfind (const struct pbuf *p, const void *mem, u16_t mem_len, u16_t start_offset)
u16_t | pbuf_strstr (const struct pbuf *p, const char *substr)

## Detailed Description

pbuf API

## Macro Definition Documentation

## LWIP_SUPPORT_CUSTOM_PBUF

#define LWIP_SUPPORT_CUSTOM_PBUF ((IP_FRAG && !LWIP_NETIF_TX_SINGLE_PBUF) || (LWIP_IPV6 && LWIP_IPV6_FRAG))

LWIP_SUPPORT_CUSTOM_PBUF==1: Custom pbufs behave much like their pbuf type but they are allocated by external code (initialised by calling pbuf_alloced_custom()) and when pbuf_free gives up their last reference, they are freed by calling pbuf_custom->custom_free_function(). Currently, the pbuf_custom code is only needed for one specific configuration of IP_FRAG, unless required by external driver/application code.

## PBUF_ALLOC_FLAG_DATA_CONTIGUOUS

#define PBUF_ALLOC_FLAG_DATA_CONTIGUOUS 0x0200

Indicates the application needs the pbuf payload to be in one piece

## PBUF_ALLOC_FLAG_RX

#define PBUF_ALLOC_FLAG_RX 0x0100

Indicates this pbuf is used for RX (if not set, indicates use for TX). This information can be used to keep some spare RX buffers e.g. for receiving TCP ACKs to unblock a connection)

## PBUF_FLAG_IS_CUSTOM

#define PBUF_FLAG_IS_CUSTOM 0x02U

indicates this is a custom pbuf: pbuf_free calls pbuf_custom->custom_free_function() when the last reference is released (plus custom PBUF_RAM cannot be trimmed)

## PBUF_FLAG_LLBCAST

#define PBUF_FLAG_LLBCAST 0x08U

indicates this pbuf was received as link-level broadcast

## PBUF_FLAG_LLMCAST

#define PBUF_FLAG_LLMCAST 0x10U

indicates this pbuf was received as link-level multicast

## PBUF_FLAG_MCASTLOOP

#define PBUF_FLAG_MCASTLOOP 0x04U

indicates this pbuf is UDP multicast to be looped back

## PBUF_FLAG_PUSH

#define PBUF_FLAG_PUSH 0x01U

indicates this packet's data should be immediately passed to the application

## PBUF_FLAG_TCP_FIN

#define PBUF_FLAG_TCP_FIN 0x20U

indicates this pbuf includes a TCP FIN flag

## PBUF_POOL_FREE_OOSEQ

#define PBUF_POOL_FREE_OOSEQ 1

Define this to 0 to prevent freeing ooseq pbufs when the PBUF_POOL is empty

## PBUF_TYPE_ALLOC_SRC_MASK

#define PBUF_TYPE_ALLOC_SRC_MASK 0x0F

4 bits are reserved for 16 allocation sources (e.g. heap, pool1, pool2, etc) Internally, we use: 0=heap, 1=MEMP_PBUF, 2=MEMP_PBUF_POOL -> 13 types free

## PBUF_TYPE_ALLOC_SRC_MASK_APP_MAX

#define PBUF_TYPE_ALLOC_SRC_MASK_APP_MAX PBUF_TYPE_ALLOC_SRC_MASK

Last pbuf allocation type for applications

## PBUF_TYPE_ALLOC_SRC_MASK_APP_MIN

#define PBUF_TYPE_ALLOC_SRC_MASK_APP_MIN 0x03

First pbuf allocation type for applications

## PBUF_TYPE_FLAG_DATA_VOLATILE

#define PBUF_TYPE_FLAG_DATA_VOLATILE 0x40

Indicates the data stored in this pbuf can change. If this pbuf needs to be queued, it must be copied/duplicated.

## PBUF_TYPE_FLAG_STRUCT_DATA_CONTIGUOUS

#define PBUF_TYPE_FLAG_STRUCT_DATA_CONTIGUOUS 0x80

Indicates that the payload directly follows the struct pbuf. This makes pbuf_header work in both directions.

## Typedef Documentation

## pbuf_free_custom_fn

typedef void(* pbuf_free_custom_fn) (struct pbuf *p)

Prototype for a function to free a custom pbuf

## Function Documentation

## pbuf_add_header()

u8_t pbuf_add_header | ( | struct pbuf * | p,
|  | size_t | header_size_increment )

Adjusts the payload pointer to reveal headers in the payload.

Adjusts the ->payload pointer so that space for a header appears in the pbuf payload.

The ->payload, ->tot_len and ->len fields are adjusted.

Parameters

  p | pbuf to change the header size.
  header_size_increment | Number of bytes to increment header size which increases the size of the pbuf. New space is on the front. If header_size_increment is 0, this function does nothing and returns successful.

PBUF_ROM and PBUF_REF type buffers cannot have their sizes increased, so the call will fail. A check is made that the increase in header size does not move the payload pointer in front of the start of the buffer.

Returns
  non-zero on failure, zero on success.

## pbuf_add_header_force()

u8_t pbuf_add_header_force | ( | struct pbuf * | p,
|  | size_t | header_size_increment )

Same as pbuf_add_header but does not check if 'header_size > 0' is allowed. This is used internally only, to allow PBUF_REF for RX.

## pbuf_clen()

u16_t pbuf_clen | ( | const struct pbuf * | p | ) |

Count number of pbufs in a chain

Parameters

  p | first pbuf of chain

Returns
  the number of pbufs in a chain

## pbuf_dechain()

struct pbuf * pbuf_dechain | ( | struct pbuf * | p | ) |

Dechains the first pbuf from its succeeding pbufs in the chain.

Makes p->tot_len field equal to p->len.

Parameters

  p | pbuf to dechain

Returns
  remainder of the pbuf chain, or NULL if it was de-allocated.

Note
  May not be called on a packet queue.

## pbuf_free_header()

struct pbuf * pbuf_free_header | ( | struct pbuf * | q,
|  | u16_t | size )

Similar to pbuf_header(-size) but de-refs header pbufs for (size >= p->len)

Parameters

  q | pbufs to operate on
  size | The number of bytes to remove from the beginning of the pbuf list. While size >= p->len, pbufs are freed. ATTENTION: this is the opposite direction as pbuf_header, but takes an u16_t not s16_t!

Returns
  the new head pbuf

## pbuf_header()

u8_t pbuf_header | ( | struct pbuf * | p,
|  | s16_t | header_size_increment )

Adjusts the payload pointer to hide or reveal headers in the payload.

Adjusts the ->payload pointer so that space for a header (dis)appears in the pbuf payload.

The ->payload, ->tot_len and ->len fields are adjusted.

Parameters

  p | pbuf to change the header size.
  header_size_increment | Number of bytes to increment header size which increases the size of the pbuf. New space is on the front. (Using a negative value decreases the header size.) If header_size_increment is 0, this function does nothing and returns successful.

PBUF_ROM and PBUF_REF type buffers cannot have their sizes increased, so the call will fail. A check is made that the increase in header size does not move the payload pointer in front of the start of the buffer.

Returns
  non-zero on failure, zero on success.

## pbuf_header_force()

u8_t pbuf_header_force | ( | struct pbuf * | p,
|  | s16_t | header_size_increment )

Same as pbuf_header but does not check if 'header_size > 0' is allowed. This is used internally only, to allow PBUF_REF for RX.

## pbuf_remove_header()

u8_t pbuf_remove_header | ( | struct pbuf * | p,
|  | size_t | header_size_decrement )

Adjusts the payload pointer to hide headers in the payload.

Adjusts the ->payload pointer so that space for a header disappears in the pbuf payload.

The ->payload, ->tot_len and ->len fields are adjusted.

Parameters

  p | pbuf to change the header size.
  header_size_decrement | Number of bytes to decrement header size which decreases the size of the pbuf. If header_size_decrement is 0, this function does nothing and returns successful.

Returns
  non-zero on failure, zero on success.

## pbuf_strstr()

u16_t pbuf_strstr | ( | const struct pbuf * | p,
|  | const char * | substr )

Find occurrence of substr with length substr_len in pbuf p, start at offset start_offset WARNING: in contrast to strstr(), this one does not stop at the first \0 in the pbuf/source string!

Parameters

  p | pbuf to search, maximum length is 0xFFFE since 0xFFFF is used as return value 'not found'
  substr | string to search for in p, maximum length is 0xFFFE

Returns
  0xFFFF if substr was not found in p or the index where it was found