pbuf.c File Reference

#include "lwip/opt.h"
#include "lwip/stats.h"
#include "lwip/def.h"
#include "lwip/mem.h"
#include "lwip/memp.h"
#include "lwip/pbuf.h"
#include "lwip/sys.h"
#include <string.h>

Macros
#define	SIZEOF_STRUCT_PBUF   LWIP_MEM_ALIGN_SIZE(sizeof(struct pbuf))
#define	PBUF_POOL_BUFSIZE_ALIGNED   LWIP_MEM_ALIGN_SIZE(PBUF_POOL_BUFSIZE)
#define	PBUF_POOL_IS_EMPTY()

Functions
struct pbuf *	pbuf_alloc (pbuf_layer layer, u16_t length, pbuf_type type)
void	pbuf_realloc (struct pbuf *p, u16_t new_len)
static u8_t	pbuf_header_impl (struct pbuf *p, s16_t header_size_increment, u8_t force)
u8_t	pbuf_header (struct pbuf *p, s16_t header_size_increment)
u8_t	pbuf_header_force (struct pbuf *p, s16_t header_size_increment)
u8_t	pbuf_free (struct pbuf *p)
u16_t	pbuf_clen (const struct pbuf *p)
void	pbuf_ref (struct pbuf *p)
void	pbuf_cat (struct pbuf *h, struct pbuf *t)
void	pbuf_chain (struct pbuf *h, struct pbuf *t)
struct pbuf *	pbuf_dechain (struct pbuf *p)
err_t	pbuf_copy (struct pbuf *p_to, const struct pbuf *p_from)
u16_t	pbuf_copy_partial (const struct pbuf *buf, void *dataptr, u16_t len, u16_t offset)
static const struct pbuf *	pbuf_skip_const (const struct pbuf *in, u16_t in_offset, u16_t *out_offset)
struct pbuf *	pbuf_skip (struct pbuf *in, u16_t in_offset, u16_t *out_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_coalesce (struct pbuf *p, pbuf_layer layer)
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

Packet buffer management

Macro Definition Documentation

SIZEOF_STRUCT_PBUF

#define SIZEOF_STRUCT_PBUF   LWIP_MEM_ALIGN_SIZE(sizeof(struct pbuf))

PBUF_POOL_BUFSIZE_ALIGNED

#define PBUF_POOL_BUFSIZE_ALIGNED   LWIP_MEM_ALIGN_SIZE(PBUF_POOL_BUFSIZE)

PBUF_POOL_IS_EMPTY

#define PBUF_POOL_IS_EMPTY

(

)

Function Documentation

pbuf_header_impl()

static u8_t pbuf_header_impl ( struct pbuf *  p, s16_t  header_size_increment, u8_t  force  )

static

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

See also

pbuf_header.

Parameters

p	pbuf to change the header size.
header_size_increment	Number of bytes to increment header size.
force	Allow 'header_size_increment > 0' for PBUF_REF/PBUF_ROM types

Returns

non-zero on failure, zero on success.

{
  u16_t type;
  void *payload;
  u16_t increment_magnitude;
 
  LWIP_ASSERT("p != NULL", p != NULL);
  if ((header_size_increment == 0) || (p == NULL)) {
    return 0;
  }
 
  if (header_size_increment < 0) {
    increment_magnitude = (u16_t)-header_size_increment;
    /* Check that we aren't going to move off the end of the pbuf */
    LWIP_ERROR("increment_magnitude <= p->len", (increment_magnitude <= p->len), return 1;);
  } else {
    increment_magnitude = (u16_t)header_size_increment;
#if 0
    /* Can't assert these as some callers speculatively call
         pbuf_header() to see if it's OK.  Will return 1 below instead. */
    /* Check that we've got the correct type of pbuf to work with */
    LWIP_ASSERT("p->type == PBUF_RAM || p->type == PBUF_POOL",
                p->type == PBUF_RAM || p->type == PBUF_POOL);
    /* Check that we aren't going to move off the beginning of the pbuf */
    LWIP_ASSERT("p->payload - increment_magnitude >= p + SIZEOF_STRUCT_PBUF",
                (u8_t *)p->payload - increment_magnitude >= (u8_t *)p + SIZEOF_STRUCT_PBUF);
#endif
  }
 
  type = p->type;
  /* remember current payload pointer */
  payload = p->payload;
 
  /* pbuf types containing payloads? */
  if (type == PBUF_RAM || type == PBUF_POOL) {
    /* set new payload pointer */
    p->payload = (u8_t *)p->payload - header_size_increment;
    /* boundary check fails? */
    if ((u8_t *)p->payload < (u8_t *)p + SIZEOF_STRUCT_PBUF) {
      LWIP_DEBUGF( PBUF_DEBUG | LWIP_DBG_TRACE,
        ("pbuf_header: failed as %p < %p (not enough space for new header size)\n",
        (void *)p->payload, (void *)((u8_t *)p + SIZEOF_STRUCT_PBUF)));
      /* restore old payload pointer */
      p->payload = payload;
      /* bail out unsuccessfully */
      return 1;
    }
  /* pbuf types referring to external payloads? */
  } else if (type == PBUF_REF || type == PBUF_ROM) {
    /* hide a header in the payload? */
    if ((header_size_increment < 0) && (increment_magnitude <= p->len)) {
      /* increase payload pointer */
      p->payload = (u8_t *)p->payload - header_size_increment;
    } else if ((header_size_increment > 0) && force) {
      p->payload = (u8_t *)p->payload - header_size_increment;
    } else {
      /* cannot expand payload to front (yet!)
       * bail out unsuccessfully */
      return 1;
    }
  } else {
    /* Unknown type */
    LWIP_ASSERT("bad pbuf type", 0);
    return 1;
  }
  /* modify pbuf length fields */
  p->len += header_size_increment;
  p->tot_len += header_size_increment;
 
  LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_header: old %p new %p (%"S16_F")\n",
    (void *)payload, (void *)p->payload, header_size_increment));
 
  return 0;
}

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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 hdr_size_inc 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.

{
   return pbuf_header_impl(p, header_size_increment, 0);
}

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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.

{
   return pbuf_header_impl(p, header_size_increment, 1);
}

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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

{
  u16_t len;
 
  len = 0;
  while (p != NULL) {
    ++len;
    p = p->next;
  }
  return len;
}

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.

{
  struct pbuf *q;
  u8_t tail_gone = 1;
  /* tail */
  q = p->next;
  /* pbuf has successor in chain? */
  if (q != NULL) {
    /* assert tot_len invariant: (p->tot_len == p->len + (p->next? p->next->tot_len: 0) */
    LWIP_ASSERT("p->tot_len == p->len + q->tot_len", q->tot_len == p->tot_len - p->len);
    /* enforce invariant if assertion is disabled */
    q->tot_len = p->tot_len - p->len;
    /* decouple pbuf from remainder */
    p->next = NULL;
    /* total length of pbuf p is its own length only */
    p->tot_len = p->len;
    /* q is no longer referenced by p, free it */
    LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_dechain: unreferencing %p\n", (void *)q));
    tail_gone = pbuf_free(q);
    if (tail_gone > 0) {
      LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE,
                  ("pbuf_dechain: deallocated %p (as it is no longer referenced)\n", (void *)q));
    }
    /* return remaining tail or NULL if deallocated */
  }
  /* assert tot_len invariant: (p->tot_len == p->len + (p->next? p->next->tot_len: 0) */
  LWIP_ASSERT("p->tot_len == p->len", p->tot_len == p->len);
  return ((tail_gone > 0) ? NULL : q);
}

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pbuf_skip_const()

static const struct pbuf* pbuf_skip_const ( const struct pbuf *  in, u16_t  in_offset, u16_t *  out_offset  )

static

{
  u16_t offset_left = in_offset;
  const struct pbuf* q = in;
 
  /* get the correct pbuf */
  while ((q != NULL) && (q->len <= offset_left)) {
    offset_left -= q->len;
    q = q->next;
  }
  if (out_offset != NULL) {
    *out_offset = offset_left;
  }
  return q;
}

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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

{
  size_t substr_len;
  if ((substr == NULL) || (substr[0] == 0) || (p->tot_len == 0xFFFF)) {
    return 0xFFFF;
  }
  substr_len = strlen(substr);
  if (substr_len >= 0xFFFF) {
    return 0xFFFF;
  }
  return pbuf_memfind(p, substr, (u16_t)substr_len, 0);
}

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