Packet buffers (PBUF)

Collaboration diagram for Packet buffers (PBUF):

Macros
#define	PBUF_NEEDS_COPY(p)   ((p)->type_internal & PBUF_TYPE_FLAG_DATA_VOLATILE)

Enumerations
enum	pbuf_layer {   PBUF_TRANSPORT = PBUF_LINK_ENCAPSULATION_HLEN + PBUF_LINK_HLEN + PBUF_IP_HLEN + PBUF_TRANSPORT_HLEN , PBUF_IP = PBUF_LINK_ENCAPSULATION_HLEN + PBUF_LINK_HLEN + PBUF_IP_HLEN , PBUF_LINK = PBUF_LINK_ENCAPSULATION_HLEN + PBUF_LINK_HLEN , PBUF_RAW_TX = PBUF_LINK_ENCAPSULATION_HLEN ,   PBUF_RAW = 0 }
enum	pbuf_type { PBUF_RAM = (PBUF_ALLOC_FLAG_DATA_CONTIGUOUS | PBUF_TYPE_FLAG_STRUCT_DATA_CONTIGUOUS | PBUF_TYPE_ALLOC_SRC_MASK_STD_HEAP) , PBUF_ROM = PBUF_TYPE_ALLOC_SRC_MASK_STD_MEMP_PBUF , PBUF_REF = (PBUF_TYPE_FLAG_DATA_VOLATILE | PBUF_TYPE_ALLOC_SRC_MASK_STD_MEMP_PBUF) , PBUF_POOL = (PBUF_ALLOC_FLAG_RX | PBUF_TYPE_FLAG_STRUCT_DATA_CONTIGUOUS | PBUF_TYPE_ALLOC_SRC_MASK_STD_MEMP_PBUF_POOL) }

Functions
struct pbuf *	pbuf_alloc (pbuf_layer layer, u16_t length, pbuf_type type)
struct pbuf *	pbuf_alloc_reference (void *payload, u16_t length, pbuf_type type)
void	pbuf_realloc (struct pbuf *p, u16_t new_len)
u8_t	pbuf_free (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)
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 *buf, 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)
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)
struct pbuf *	pbuf_clone (pbuf_layer layer, 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)

Detailed Description

Packets are built from the pbuf data structure. It supports dynamic memory allocation for packet contents or can reference externally managed packet contents both in RAM and ROM. Quick allocation for incoming packets is provided through pools with fixed sized pbufs.

A packet may span over multiple pbufs, chained as a singly linked list. This is called a "pbuf chain".

Multiple packets may be queued, also using this singly linked list. This is called a "packet queue".

So, a packet queue consists of one or more pbuf chains, each of which consist of one or more pbufs. CURRENTLY, PACKET QUEUES ARE NOT SUPPORTED!!! Use helper structs to queue multiple packets.

The differences between a pbuf chain and a packet queue are very precise but subtle.

The last pbuf of a packet has a ->tot_len field that equals the ->len field. It can be found by traversing the list. If the last pbuf of a packet has a ->next field other than NULL, more packets are on the queue.

Therefore, looping through a pbuf of a single packet, has an loop end condition (tot_len == p->len), NOT (next == NULL).

Example of custom pbuf usage: Zero-copy RX

Macro Definition Documentation

PBUF_NEEDS_COPY

#define PBUF_NEEDS_COPY

(

p

)

((p)->type_internal & PBUF_TYPE_FLAG_DATA_VOLATILE)

PBUF_NEEDS_COPY(p): return a boolean value indicating whether the given pbuf needs to be copied in order to be kept around beyond the current call stack without risking being corrupted. The default setting provides safety: it will make a copy iof any pbuf chain that does not consist entirely of PBUF_ROM type pbufs. For setups with zero-copy support, it may be redefined to evaluate to true in all cases, for example. However, doing so also has an effect on the application side: any buffers that are not copied must also not be reused by the application after passing them to lwIP. For example, when setting PBUF_NEEDS_COPY to (0), after using udp_send() with a PBUF_RAM pbuf, the application must free the pbuf immediately, rather than reusing it for other purposes. For more background information on this, see tasks #6735 and #7896, and bugs #11400 and #49914.

Definition at line 72 of file pbuf.h.

Enumeration Type Documentation

pbuf_layer

enum pbuf_layer

Enumeration of pbuf layers

Enumerator
PBUF_TRANSPORT	Includes spare room for transport layer header, e.g. UDP header. Use this if you intend to pass the pbuf to functions like udp_send().
PBUF_IP	Includes spare room for IP header. Use this if you intend to pass the pbuf to functions like raw_send().
PBUF_LINK	Includes spare room for link layer header (ethernet header). Use this if you intend to pass the pbuf to functions like ethernet_output(). See also PBUF_LINK_HLEN
PBUF_RAW_TX	Includes spare room for additional encapsulation header before ethernet headers (e.g. 802.11). Use this if you intend to pass the pbuf to functions like netif->linkoutput(). See also PBUF_LINK_ENCAPSULATION_HLEN
PBUF_RAW	Use this for input packets in a netif driver when calling netif->input() in the most common case - ethernet-layer netif driver.

Definition at line 89 of file pbuf.h.

             {
  PBUF_TRANSPORT = PBUF_LINK_ENCAPSULATION_HLEN + PBUF_LINK_HLEN + PBUF_IP_HLEN + PBUF_TRANSPORT_HLEN,
  PBUF_IP = PBUF_LINK_ENCAPSULATION_HLEN + PBUF_LINK_HLEN + PBUF_IP_HLEN,
  PBUF_LINK = PBUF_LINK_ENCAPSULATION_HLEN + PBUF_LINK_HLEN,
  PBUF_RAW_TX = PBUF_LINK_ENCAPSULATION_HLEN,
  PBUF_RAW = 0
} pbuf_layer;

pbuf_type

enum pbuf_type

Enumeration of pbuf types

Enumerator
PBUF_RAM	pbuf data is stored in RAM, used for TX mostly, struct pbuf and its payload are allocated in one piece of contiguous memory (so the first payload byte can be calculated from struct pbuf). pbuf_alloc() allocates PBUF_RAM pbufs as unchained pbufs (although that might change in future versions). This should be used for all OUTGOING packets (TX).
PBUF_ROM	pbuf data is stored in ROM, i.e. struct pbuf and its payload are located in totally different memory areas. Since it points to ROM, payload does not have to be copied when queued for transmission.
PBUF_REF	pbuf comes from the pbuf pool. Much like PBUF_ROM but payload might change so it has to be duplicated when queued before transmitting, depending on who has a 'ref' to it.
PBUF_POOL	pbuf payload refers to RAM. This one comes from a pool and should be used for RX. Payload can be chained (scatter-gather RX) but like PBUF_RAM, struct pbuf and its payload are allocated in one piece of contiguous memory (so the first payload byte can be calculated from struct pbuf). Don't use this for TX, if the pool becomes empty e.g. because of TCP queuing, you are unable to receive TCP acks!

Definition at line 145 of file pbuf.h.

             {
  PBUF_RAM = (PBUF_ALLOC_FLAG_DATA_CONTIGUOUS | PBUF_TYPE_FLAG_STRUCT_DATA_CONTIGUOUS | PBUF_TYPE_ALLOC_SRC_MASK_STD_HEAP),
  PBUF_ROM = PBUF_TYPE_ALLOC_SRC_MASK_STD_MEMP_PBUF,
  PBUF_REF = (PBUF_TYPE_FLAG_DATA_VOLATILE | PBUF_TYPE_ALLOC_SRC_MASK_STD_MEMP_PBUF),
  PBUF_POOL = (PBUF_ALLOC_FLAG_RX | PBUF_TYPE_FLAG_STRUCT_DATA_CONTIGUOUS | PBUF_TYPE_ALLOC_SRC_MASK_STD_MEMP_PBUF_POOL)
} pbuf_type;

Function Documentation

pbuf_alloc()

struct pbuf * pbuf_alloc	(	pbuf_layer	layer,
		u16_t	length,
		pbuf_type	type
	)

Allocates a pbuf of the given type (possibly a chain for PBUF_POOL type).

The actual memory allocated for the pbuf is determined by the layer at which the pbuf is allocated and the requested size (from the size parameter).

Parameters

layer	header size
length	size of the pbuf's payload
type	this parameter decides how and where the pbuf should be allocated as follows:

• PBUF_RAM: buffer memory for pbuf is allocated as one large chunk. This includes protocol headers as well.
• PBUF_ROM: no buffer memory is allocated for the pbuf, even for protocol headers. Additional headers must be prepended by allocating another pbuf and chain in to the front of the ROM pbuf. It is assumed that the memory used is really similar to ROM in that it is immutable and will not be changed. Memory which is dynamic should generally not be attached to PBUF_ROM pbufs. Use PBUF_REF instead.
• PBUF_REF: no buffer memory is allocated for the pbuf, even for protocol headers. It is assumed that the pbuf is only being used in a single thread. If the pbuf gets queued, then pbuf_take should be called to copy the buffer.
• PBUF_POOL: the pbuf is allocated as a pbuf chain, with pbufs from the pbuf pool that is allocated during pbuf_init().

Returns

the allocated pbuf. If multiple pbufs where allocated, this is the first pbuf of a pbuf chain.

Definition at line 224 of file pbuf.c.

{
  struct pbuf *p;
  u16_t offset = (u16_t)layer;
  LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_alloc(length=%"U16_F")\n", length));
 
  switch (type) {
    case PBUF_REF: /* fall through */
    case PBUF_ROM:
      p = pbuf_alloc_reference(NULL, length, type);
      break;
    case PBUF_POOL: {
      struct pbuf *q, *last;
      u16_t rem_len; /* remaining length */
      p = NULL;
      last = NULL;
      rem_len = length;
      do {
        u16_t qlen;
        q = (struct pbuf *)memp_malloc(MEMP_PBUF_POOL);
        if (q == NULL) {
          PBUF_POOL_IS_EMPTY();
          /* free chain so far allocated */
          if (p) {
            pbuf_free(p);
          }
          /* bail out unsuccessfully */
          return NULL;
        }
        qlen = LWIP_MIN(rem_len, (u16_t)(PBUF_POOL_BUFSIZE_ALIGNED - LWIP_MEM_ALIGN_SIZE(offset)));
        pbuf_init_alloced_pbuf(q, LWIP_MEM_ALIGN((void *)((u8_t *)q + SIZEOF_STRUCT_PBUF + offset)),
                               rem_len, qlen, type, 0);
        LWIP_ASSERT("pbuf_alloc: pbuf q->payload properly aligned",
                    ((mem_ptr_t)q->payload % MEM_ALIGNMENT) == 0);
        LWIP_ASSERT("PBUF_POOL_BUFSIZE must be bigger than MEM_ALIGNMENT",
                    (PBUF_POOL_BUFSIZE_ALIGNED - LWIP_MEM_ALIGN_SIZE(offset)) > 0 );
        if (p == NULL) {
          /* allocated head of pbuf chain (into p) */
          p = q;
        } else {
          /* make previous pbuf point to this pbuf */
          last->next = q;
        }
        last = q;
        rem_len = (u16_t)(rem_len - qlen);
        offset = 0;
      } while (rem_len > 0);
      break;
    }
    case PBUF_RAM: {
      mem_size_t payload_len = (mem_size_t)(LWIP_MEM_ALIGN_SIZE(offset) + LWIP_MEM_ALIGN_SIZE(length));
      mem_size_t alloc_len = (mem_size_t)(LWIP_MEM_ALIGN_SIZE(SIZEOF_STRUCT_PBUF) + payload_len);
 
      /* bug #50040: Check for integer overflow when calculating alloc_len */
      if ((payload_len < LWIP_MEM_ALIGN_SIZE(length)) ||
          (alloc_len < LWIP_MEM_ALIGN_SIZE(length))) {
        return NULL;
      }
 
      /* If pbuf is to be allocated in RAM, allocate memory for it. */
      p = (struct pbuf *)mem_malloc(alloc_len);
      if (p == NULL) {
        return NULL;
      }
      pbuf_init_alloced_pbuf(p, LWIP_MEM_ALIGN((void *)((u8_t *)p + SIZEOF_STRUCT_PBUF + offset)),
                             length, length, type, 0);
      LWIP_ASSERT("pbuf_alloc: pbuf->payload properly aligned",
                  ((mem_ptr_t)p->payload % MEM_ALIGNMENT) == 0);
      break;
    }
    default:
      LWIP_ASSERT("pbuf_alloc: erroneous type", 0);
      return NULL;
  }
  LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_alloc(length=%"U16_F") == %p\n", length, (void *)p));
  return p;
}

Referenced by create_arp_response(), create_ip4_input_fragment(), eth_mac_irq(), input_pkt(), LibIPInsertPacket(), pbuf_clone(), send_pkt(), slipif_rxbyte(), START_TEST(), tcp_create_segment_wnd(), test_tcp_netif_output(), and test_udp_create_test_packet().

pbuf_alloc_reference()

struct pbuf * pbuf_alloc_reference	(	void *	payload,
		u16_t	length,
		pbuf_type	type
	)

Allocates a pbuf for referenced data. Referenced data can be volatile (PBUF_REF) or long-lived (PBUF_ROM).

The actual memory allocated for the pbuf is determined by the layer at which the pbuf is allocated and the requested size (from the size parameter).

Parameters

payload	referenced payload
length	size of the pbuf's payload
type	this parameter decides how and where the pbuf should be allocated as follows:

• PBUF_ROM: It is assumed that the memory used is really similar to ROM in that it is immutable and will not be changed. Memory which is dynamic should generally not be attached to PBUF_ROM pbufs. Use PBUF_REF instead.
• PBUF_REF: It is assumed that the pbuf is only being used in a single thread. If the pbuf gets queued, then pbuf_take should be called to copy the buffer.

Returns

the allocated pbuf.

Definition at line 327 of file pbuf.c.

{
  struct pbuf *p;
  LWIP_ASSERT("invalid pbuf_type", (type == PBUF_REF) || (type == PBUF_ROM));
  /* only allocate memory for the pbuf structure */
  p = (struct pbuf *)memp_malloc(MEMP_PBUF);
  if (p == NULL) {
    LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
                ("pbuf_alloc_reference: Could not allocate MEMP_PBUF for PBUF_%s.\n",
                 (type == PBUF_ROM) ? "ROM" : "REF"));
    return NULL;
  }
  pbuf_init_alloced_pbuf(p, payload, length, length, type, 0);
  return p;
}

Referenced by pbuf_alloc().

pbuf_cat()

void pbuf_cat	(	struct pbuf *	h,
		struct pbuf *	t
	)

Concatenate two pbufs (each may be a pbuf chain) and take over the caller's reference of the tail pbuf.

Note

The caller MAY NOT reference the tail pbuf afterwards. Use pbuf_chain() for that purpose.

This function explicitly does not check for tot_len overflow to prevent failing to queue too long pbufs. This can produce invalid pbufs, so handle with care!

See also

pbuf_chain()

Definition at line 855 of file pbuf.c.

{
  struct pbuf *p;
 
  LWIP_ERROR("(h != NULL) && (t != NULL) (programmer violates API)",
             ((h != NULL) && (t != NULL)), return;);
 
  /* proceed to last pbuf of chain */
  for (p = h; p->next != NULL; p = p->next) {
    /* add total length of second chain to all totals of first chain */
    p->tot_len = (u16_t)(p->tot_len + t->tot_len);
  }
  /* { p is last pbuf of first h chain, p->next == NULL } */
  LWIP_ASSERT("p->tot_len == p->len (of last pbuf in chain)", p->tot_len == p->len);
  LWIP_ASSERT("p->next == NULL", p->next == NULL);
  /* add total length of second chain to last pbuf total of first chain */
  p->tot_len = (u16_t)(p->tot_len + t->tot_len);
  /* chain last pbuf of head (p) with first of tail (t) */
  p->next = t;
  /* p->next now references t, but the caller will drop its reference to t,
   * so netto there is no change to the reference count of t.
   */
}

Referenced by pbuf_chain(), slipif_rxbyte(), START_TEST(), and test_tcp_netif_output().

pbuf_chain()

void pbuf_chain	(	struct pbuf *	h,
		struct pbuf *	t
	)

Chain two pbufs (or pbuf chains) together.

The caller MUST call pbuf_free(t) once it has stopped using it. Use pbuf_cat() instead if you no longer use t.

Parameters

h	head pbuf (chain)
t	tail pbuf (chain)

Note

The pbufs MUST belong to the same packet.

MAY NOT be called on a packet queue.

The ->tot_len fields of all pbufs of the head chain are adjusted. The ->next field of the last pbuf of the head chain is adjusted. The ->ref field of the first pbuf of the tail chain is adjusted.

Definition at line 897 of file pbuf.c.

{
  pbuf_cat(h, t);
  /* t is now referenced by h */
  pbuf_ref(t);
  LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_chain: %p references %p\n", (void *)h, (void *)t));
}

pbuf_clone()

struct pbuf * pbuf_clone	(	pbuf_layer	layer,
		pbuf_type	type,
		struct pbuf *	p
	)

Allocates a new pbuf of same length (via pbuf_alloc()) and copies the source pbuf into this new pbuf (using pbuf_copy()).

Parameters

layer	pbuf_layer of the new pbuf
type	this parameter decides how and where the pbuf should be allocated (

See also

pbuf_alloc())

Parameters

p	the source pbuf

Returns

a new pbuf or NULL if allocation fails

Definition at line 1337 of file pbuf.c.

{
  struct pbuf *q;
  err_t err;
  q = pbuf_alloc(layer, p->tot_len, type);
  if (q == NULL) {
    return NULL;
  }
  err = pbuf_copy(q, p);
  LWIP_UNUSED_ARG(err); /* in case of LWIP_NOASSERT */
  LWIP_ASSERT("pbuf_copy failed", err == ERR_OK);
  return q;
}

Referenced by pbuf_coalesce().

pbuf_coalesce()

struct pbuf * pbuf_coalesce	(	struct pbuf *	p,
		pbuf_layer	layer
	)

Creates a single pbuf out of a queue of pbufs.

Remarks

: Either the source pbuf 'p' is freed by this function or the original pbuf 'p' is returned, therefore the caller has to check the result!

Parameters

p	the source pbuf
layer	pbuf_layer of the new pbuf

Returns

a new, single pbuf (p->next is NULL) or the old pbuf if allocation fails

Definition at line 1309 of file pbuf.c.

{
  struct pbuf *q;
  if (p->next == NULL) {
    return p;
  }
  q = pbuf_clone(layer, PBUF_RAM, p);
  if (q == NULL) {
    /* @todo: what do we do now? */
    return p;
  }
  pbuf_free(p);
  return q;
}

pbuf_copy()

err_t pbuf_copy	(	struct pbuf *	p_to,
		const struct pbuf *	p_from
	)

Copy the contents of one packet buffer into another.

Note

Only one packet is copied, no packet queue!

Parameters

p_to	pbuf destination of the copy
p_from	pbuf source of the copy

Returns

ERR_OK if pbuf was copied ERR_ARG if one of the pbufs is NULL or p_to is not big enough to hold p_from ERR_VAL if any of the pbufs are part of a queue

Definition at line 959 of file pbuf.c.

{
  LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_copy(%p, %p)\n",
              (const void *)p_to, (const void *)p_from));
 
  LWIP_ERROR("pbuf_copy: invalid source", p_from != NULL, return ERR_ARG;);
  return pbuf_copy_partial_pbuf(p_to, p_from, p_from->tot_len, 0);
}

Referenced by pbuf_clone(), START_TEST(), and test_tcp_netif_output().

pbuf_copy_partial()

u16_t pbuf_copy_partial	(	const struct pbuf *	buf,
		void *	dataptr,
		u16_t	len,
		u16_t	offset
	)

Copy (part of) the contents of a packet buffer to an application supplied buffer.

Parameters

buf	the pbuf from which to copy data
dataptr	the application supplied buffer
len	length of data to copy (dataptr must be big enough). No more than buf->tot_len will be copied, irrespective of len
offset	offset into the packet buffer from where to begin copying len bytes

Returns

the number of bytes copied, or 0 on failure

Definition at line 1058 of file pbuf.c.

{
  const struct pbuf *p;
  u16_t left = 0;
  u16_t buf_copy_len;
  u16_t copied_total = 0;
 
  LWIP_ERROR("pbuf_copy_partial: invalid buf", (buf != NULL), return 0;);
  LWIP_ERROR("pbuf_copy_partial: invalid dataptr", (dataptr != NULL), return 0;);
 
  /* Note some systems use byte copy if dataptr or one of the pbuf payload pointers are unaligned. */
  for (p = buf; len != 0 && p != NULL; p = p->next) {
    if ((offset != 0) && (offset >= p->len)) {
      /* don't copy from this buffer -> on to the next */
      offset = (u16_t)(offset - p->len);
    } else {
      /* copy from this buffer. maybe only partially. */
      buf_copy_len = (u16_t)(p->len - offset);
      if (buf_copy_len > len) {
        buf_copy_len = len;
      }
      /* copy the necessary parts of the buffer */
      MEMCPY(&((char *)dataptr)[left], &((char *)p->payload)[offset], buf_copy_len);
      copied_total = (u16_t)(copied_total + buf_copy_len);
      left = (u16_t)(left + buf_copy_len);
      len = (u16_t)(len - buf_copy_len);
      offset = 0;
    }
  }
  return copied_total;
}

Referenced by get_tcp_flags_from_packet(), LibTCPGetDataFromConnectionQueue(), netif_output(), pbuf_get_contiguous(), START_TEST(), test_netif_linkoutput(), and test_tcp_tx_full_window_lost().

pbuf_copy_partial_pbuf()

err_t pbuf_copy_partial_pbuf	(	struct pbuf *	p_to,
		const struct pbuf *	p_from,
		u16_t	copy_len,
		u16_t	offset
	)

Copy part or all of one packet buffer into another, to a specified offset.

Note

Only data in one packet is copied, no packet queue!

Argument order is shared with pbuf_copy, but different than pbuf_copy_partial.

Parameters

p_to	pbuf destination of the copy
p_from	pbuf source of the copy
copy_len	number of bytes to copy
offset	offset in destination pbuf where to copy to

Returns

ERR_OK if copy_len bytes were copied ERR_ARG if one of the pbufs is NULL or p_from is shorter than copy_len or p_to is not big enough to hold copy_len at offset ERR_VAL if any of the pbufs are part of a queue

Definition at line 986 of file pbuf.c.

{
  size_t offset_to = offset, offset_from = 0, len;
 
  LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_copy_partial_pbuf(%p, %p, %"U16_F", %"U16_F")\n",
              (const void *)p_to, (const void *)p_from, copy_len, offset));
 
  /* is the copy_len in range? */
  LWIP_ERROR("pbuf_copy_partial_pbuf: copy_len bigger than source", ((p_from != NULL) &&
             (p_from->tot_len >= copy_len)), return ERR_ARG;);
  /* is the target big enough to hold the source? */
  LWIP_ERROR("pbuf_copy_partial_pbuf: target not big enough", ((p_to != NULL) &&
             (p_to->tot_len >= (offset + copy_len))), return ERR_ARG;);
 
  /* iterate through pbuf chain */
  do {
    /* copy one part of the original chain */
    if ((p_to->len - offset_to) >= (p_from->len - offset_from)) {
      /* complete current p_from fits into current p_to */
      len = p_from->len - offset_from;
    } else {
      /* current p_from does not fit into current p_to */
      len = p_to->len - offset_to;
    }
    len = LWIP_MIN(copy_len, len);
    MEMCPY((u8_t *)p_to->payload + offset_to, (u8_t *)p_from->payload + offset_from, len);
    offset_to += len;
    offset_from += len;
    copy_len = (u16_t)(copy_len - len);
    LWIP_ASSERT("offset_to <= p_to->len", offset_to <= p_to->len);
    LWIP_ASSERT("offset_from <= p_from->len", offset_from <= p_from->len);
    if (offset_from >= p_from->len) {
      /* on to next p_from (if any) */
      offset_from = 0;
      p_from = p_from->next;
      LWIP_ERROR("p_from != NULL", (p_from != NULL) || (copy_len == 0), return ERR_ARG;);
    }
    if (offset_to == p_to->len) {
      /* on to next p_to (if any) */
      offset_to = 0;
      p_to = p_to->next;
      LWIP_ERROR("p_to != NULL", (p_to != NULL) || (copy_len == 0), return ERR_ARG;);
    }
 
    if ((p_from != NULL) && (p_from->len == p_from->tot_len)) {
      /* don't copy more than one packet! */
      LWIP_ERROR("pbuf_copy_partial_pbuf() does not allow packet queues!",
                 (p_from->next == NULL), return ERR_VAL;);
    }
    if ((p_to != NULL) && (p_to->len == p_to->tot_len)) {
      /* don't copy more than one packet! */
      LWIP_ERROR("pbuf_copy_partial_pbuf() does not allow packet queues!",
                 (p_to->next == NULL), return ERR_VAL;);
    }
  } while (copy_len);
  LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_copy_partial_pbuf: copy complete.\n"));
  return ERR_OK;
}

Referenced by pbuf_copy(), and START_TEST().

pbuf_free()

u8_t pbuf_free

(

struct pbuf *

p

)

Dereference a pbuf chain or queue and deallocate any no-longer-used pbufs at the head of this chain or queue.

Decrements the pbuf reference count. If it reaches zero, the pbuf is deallocated.

For a pbuf chain, this is repeated for each pbuf in the chain, up to the first pbuf which has a non-zero reference count after decrementing. So, when all reference counts are one, the whole chain is free'd.

Parameters

p	The pbuf (chain) to be dereferenced.

Returns

the number of pbufs that were de-allocated from the head of the chain.

Note

the reference counter of a pbuf equals the number of pointers that refer to the pbuf (or into the pbuf).

Definition at line 727 of file pbuf.c.

{
  u8_t alloc_src;
  struct pbuf *q;
  u8_t count;
 
  if (p == NULL) {
    LWIP_ASSERT("p != NULL", p != NULL);
    /* if assertions are disabled, proceed with debug output */
    LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
                ("pbuf_free(p == NULL) was called.\n"));
    return 0;
  }
  LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_free(%p)\n", (void *)p));
 
  PERF_START;
 
  count = 0;
  /* de-allocate all consecutive pbufs from the head of the chain that
   * obtain a zero reference count after decrementing*/
  while (p != NULL) {
    LWIP_PBUF_REF_T ref;
    SYS_ARCH_DECL_PROTECT(old_level);
    /* Since decrementing ref cannot be guaranteed to be a single machine operation
     * we must protect it. We put the new ref into a local variable to prevent
     * further protection. */
    SYS_ARCH_PROTECT(old_level);
    /* all pbufs in a chain are referenced at least once */
    LWIP_ASSERT("pbuf_free: p->ref > 0", p->ref > 0);
    /* decrease reference count (number of pointers to pbuf) */
    ref = --(p->ref);
    SYS_ARCH_UNPROTECT(old_level);
    /* this pbuf is no longer referenced to? */
    if (ref == 0) {
      /* remember next pbuf in chain for next iteration */
      q = p->next;
      LWIP_DEBUGF( PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_free: deallocating %p\n", (void *)p));
      alloc_src = pbuf_get_allocsrc(p);
#if LWIP_SUPPORT_CUSTOM_PBUF
      /* is this a custom pbuf? */
      if ((p->flags & PBUF_FLAG_IS_CUSTOM) != 0) {
        struct pbuf_custom *pc = (struct pbuf_custom *)p;
        LWIP_ASSERT("pc->custom_free_function != NULL", pc->custom_free_function != NULL);
        pc->custom_free_function(p);
      } else
#endif /* LWIP_SUPPORT_CUSTOM_PBUF */
      {
        /* is this a pbuf from the pool? */
        if (alloc_src == PBUF_TYPE_ALLOC_SRC_MASK_STD_MEMP_PBUF_POOL) {
          memp_free(MEMP_PBUF_POOL, p);
          /* is this a ROM or RAM referencing pbuf? */
        } else if (alloc_src == PBUF_TYPE_ALLOC_SRC_MASK_STD_MEMP_PBUF) {
          memp_free(MEMP_PBUF, p);
          /* type == PBUF_RAM */
        } else if (alloc_src == PBUF_TYPE_ALLOC_SRC_MASK_STD_HEAP) {
          mem_free(p);
        } else {
          /* @todo: support freeing other types */
          LWIP_ASSERT("invalid pbuf type", 0);
        }
      }
      count++;
      /* proceed to next pbuf */
      p = q;
      /* p->ref > 0, this pbuf is still referenced to */
      /* (and so the remaining pbufs in chain as well) */
    } else {
      LWIP_DEBUGF( PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_free: %p has ref %"U16_F", ending here.\n", (void *)p, (u16_t)ref));
      /* stop walking through the chain */
      p = NULL;
    }
  }
  PERF_STOP("pbuf_free");
  /* return number of de-allocated pbufs */
  return count;
}

Referenced by create_ip4_input_fragment(), eth_mac_irq(), eth_rx_irq(), input_pkt(), InternalRecvEventHandler(), ip4_teardown(), LibTCPEmptyQueue(), main(), pbuf_alloc(), pbuf_coalesce(), pbuf_dechain(), pbuf_free_header(), pbuf_free_int(), pbuf_realloc(), slipif_rxbyte_input(), START_TEST(), tcpip_thread_handle_msg(), test_recv(), test_rst_generation_with_incoming_packet(), test_tcp_counters_recv(), test_tcp_recv_expect1byte(), and test_tcp_tx_full_window_lost().

pbuf_get_at()

u8_t pbuf_get_at	(	const struct pbuf *	p,
		u16_t	offset
	)

Get one byte from the specified position in a pbuf WARNING: returns zero for offset >= p->tot_len

Parameters

p	pbuf to parse
offset	offset into p of the byte to return

Returns

byte at an offset into p OR ZERO IF 'offset' >= p->tot_len

Definition at line 1402 of file pbuf.c.

{
  int ret = pbuf_try_get_at(p, offset);
  if (ret >= 0) {
    return (u8_t)ret;
  }
  return 0;
}

Referenced by pbuf_memcmp(), and START_TEST().

pbuf_get_contiguous()

void * pbuf_get_contiguous	(	const struct pbuf *	p,
		void *	buffer,
		size_t	bufsize,
		u16_t	len,
		u16_t	offset
	)

Get part of a pbuf's payload as contiguous memory. The returned memory is either a pointer into the pbuf's payload or, if split over multiple pbufs, a copy into the user-supplied buffer.

Parameters

p	the pbuf from which to copy data
buffer	the application supplied buffer
bufsize	size of the application supplied buffer
len	length of data to copy (dataptr must be big enough). No more than buf->tot_len will be copied, irrespective of len
offset	offset into the packet buffer from where to begin copying len bytes

Returns

the number of bytes copied, or 0 on failure

Definition at line 1105 of file pbuf.c.

{
  const struct pbuf *q;
  u16_t out_offset;
 
  LWIP_ERROR("pbuf_get_contiguous: invalid buf", (p != NULL), return NULL;);
  LWIP_ERROR("pbuf_get_contiguous: invalid dataptr", (buffer != NULL), return NULL;);
  LWIP_ERROR("pbuf_get_contiguous: invalid dataptr", (bufsize >= len), return NULL;);
 
  q = pbuf_skip_const(p, offset, &out_offset);
  if (q != NULL) {
    if (q->len >= (out_offset + len)) {
      /* all data in this pbuf, return zero-copy */
      return (u8_t *)q->payload + out_offset;
    }
    /* need to copy */
    if (pbuf_copy_partial(q, buffer, len, out_offset) != len) {
      /* copying failed: pbuf is too short */
      return NULL;
    }
    return buffer;
  }
  /* pbuf is too short (offset does not fit in) */
  return NULL;
}

pbuf_memcmp()

u16_t pbuf_memcmp	(	const struct pbuf *	p,
		u16_t	offset,
		const void *	s2,
		u16_t	n
	)

Compare pbuf contents at specified offset with memory s2, both of length n

Parameters

p	pbuf to compare
offset	offset into p at which to start comparing
s2	buffer to compare
n	length of buffer to compare

Returns

zero if equal, nonzero otherwise (0xffff if p is too short, diffoffset+1 otherwise)

Definition at line 1465 of file pbuf.c.

{
  u16_t start = offset;
  const struct pbuf *q = p;
  u16_t i;
 
  /* pbuf long enough to perform check? */
  if (p->tot_len < (offset + n)) {
    return 0xffff;
  }
 
  /* get the correct pbuf from chain. We know it succeeds because of p->tot_len check above. */
  while ((q != NULL) && (q->len <= start)) {
    start = (u16_t)(start - q->len);
    q = q->next;
  }
 
  /* return requested data if pbuf is OK */
  for (i = 0; i < n; i++) {
    /* We know pbuf_get_at() succeeds because of p->tot_len check above. */
    u8_t a = pbuf_get_at(q, (u16_t)(start + i));
    u8_t b = ((const u8_t *)s2)[i];
    if (a != b) {
      return (u16_t)LWIP_MIN(i + 1, 0xFFFF);
    }
  }
  return 0;
}

Referenced by pbuf_memfind().

pbuf_memfind()

u16_t pbuf_memfind	(	const struct pbuf *	p,
		const void *	mem,
		u16_t	mem_len,
		u16_t	start_offset
	)

Find occurrence of mem (with length mem_len) in pbuf p, starting at offset start_offset.

Parameters

p	pbuf to search, maximum length is 0xFFFE since 0xFFFF is used as return value 'not found'
mem	search for the contents of this buffer
mem_len	length of 'mem'
start_offset	offset into p at which to start searching

Returns

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

Definition at line 1507 of file pbuf.c.

{
  u16_t i;
  u16_t max_cmp_start = (u16_t)(p->tot_len - mem_len);
  if (p->tot_len >= mem_len + start_offset) {
    for (i = start_offset; i <= max_cmp_start; i++) {
      u16_t plus = pbuf_memcmp(p, i, mem, mem_len);
      if (plus == 0) {
        return i;
      }
    }
  }
  return 0xFFFF;
}

Referenced by pbuf_strstr().

pbuf_put_at()

void pbuf_put_at	(	struct pbuf *	p,
		u16_t	offset,
		u8_t	data
	)

Put one byte to the specified position in a pbuf WARNING: silently ignores offset >= p->tot_len

Parameters

p	pbuf to fill
offset	offset into p of the byte to write
data	byte to write at an offset into p

Definition at line 1442 of file pbuf.c.

{
  u16_t q_idx;
  struct pbuf *q = pbuf_skip(p, offset, &q_idx);
 
  /* write requested data if pbuf is OK */
  if ((q != NULL) && (q->len > q_idx)) {
    ((u8_t *)q->payload)[q_idx] = data;
  }
}

Referenced by START_TEST().

pbuf_realloc()

void pbuf_realloc	(	struct pbuf *	p,
		u16_t	new_len
	)

Shrink a pbuf chain to a desired length.

Parameters

p	pbuf to shrink.
new_len	desired new length of pbuf chain

Depending on the desired length, the first few pbufs in a chain might be skipped and left unchanged. The new last pbuf in the chain will be resized, and any remaining pbufs will be freed.

Note

If the pbuf is ROM/REF, only the ->tot_len and ->len fields are adjusted.

May not be called on a packet queue.

Despite its name, pbuf_realloc cannot grow the size of a pbuf (chain).

Definition at line 402 of file pbuf.c.

{
  struct pbuf *q;
  u16_t rem_len; /* remaining length */
  u16_t shrink;
 
  LWIP_ASSERT("pbuf_realloc: p != NULL", p != NULL);
 
  /* desired length larger than current length? */
  if (new_len >= p->tot_len) {
    /* enlarging not yet supported */
    return;
  }
 
  /* the pbuf chain grows by (new_len - p->tot_len) bytes
   * (which may be negative in case of shrinking) */
  shrink = (u16_t)(p->tot_len - new_len);
 
  /* first, step over any pbufs that should remain in the chain */
  rem_len = new_len;
  q = p;
  /* should this pbuf be kept? */
  while (rem_len > q->len) {
    /* decrease remaining length by pbuf length */
    rem_len = (u16_t)(rem_len - q->len);
    /* decrease total length indicator */
    q->tot_len = (u16_t)(q->tot_len - shrink);
    /* proceed to next pbuf in chain */
    q = q->next;
    LWIP_ASSERT("pbuf_realloc: q != NULL", q != NULL);
  }
  /* we have now reached the new last pbuf (in q) */
  /* rem_len == desired length for pbuf q */
 
  /* shrink allocated memory for PBUF_RAM */
  /* (other types merely adjust their length fields */
  if (pbuf_match_allocsrc(q, PBUF_TYPE_ALLOC_SRC_MASK_STD_HEAP) && (rem_len != q->len)
#if LWIP_SUPPORT_CUSTOM_PBUF
      && ((q->flags & PBUF_FLAG_IS_CUSTOM) == 0)
#endif /* LWIP_SUPPORT_CUSTOM_PBUF */
     ) {
    /* reallocate and adjust the length of the pbuf that will be split */
    struct pbuf *r = (struct pbuf *)mem_trim(q, (mem_size_t)(((u8_t *)q->payload - (u8_t *)q) + rem_len));
    LWIP_ASSERT("mem_trim returned r == NULL", r != NULL);
    /* help to detect faulty overridden implementation of mem_trim */
    LWIP_ASSERT("mem_trim returned r != q", r == q);
    LWIP_UNUSED_ARG(r);
  }
  /* adjust length fields for new last pbuf */
  q->len = rem_len;
  q->tot_len = q->len;
 
  /* any remaining pbufs in chain? */
  if (q->next != NULL) {
    /* free remaining pbufs in chain */
    pbuf_free(q->next);
  }
  /* q is last packet in chain */
  q->next = NULL;
 
}

Referenced by slipif_rxbyte().

pbuf_ref()

void pbuf_ref

(

struct pbuf *

p

)

Increment the reference count of the pbuf.

Parameters

p	pbuf to increase reference counter of

Definition at line 831 of file pbuf.c.

{
  /* pbuf given? */
  if (p != NULL) {
    SYS_ARCH_SET(p->ref, (LWIP_PBUF_REF_T)(p->ref + 1));
    LWIP_ASSERT("pbuf ref overflow", p->ref > 0);
  }
}

Referenced by pbuf_chain().

pbuf_skip()

struct pbuf * pbuf_skip	(	struct pbuf *	in,
		u16_t	in_offset,
		u16_t *	out_offset
	)

Skip a number of bytes at the start of a pbuf

Parameters

in	input pbuf
in_offset	offset to skip
out_offset	resulting offset in the returned pbuf

Returns

the pbuf in the queue where the offset is or NULL when the offset is too high

Definition at line 1209 of file pbuf.c.

{
  const struct pbuf *out = pbuf_skip_const(in, in_offset, out_offset);
  return LWIP_CONST_CAST(struct pbuf *, out);
}

Referenced by pbuf_put_at(), and pbuf_take_at().

pbuf_take()

err_t pbuf_take	(	struct pbuf *	buf,
		const void *	dataptr,
		u16_t	len
	)

Copy application supplied data into a pbuf. This function can only be used to copy the equivalent of buf->tot_len data.

Parameters

buf	pbuf to fill with data
dataptr	application supplied data buffer
len	length of the application supplied data buffer

Returns

ERR_OK if successful, ERR_MEM if the pbuf is not big enough

Definition at line 1227 of file pbuf.c.

{
  struct pbuf *p;
  size_t buf_copy_len;
  size_t total_copy_len = len;
  size_t copied_total = 0;
 
  LWIP_ERROR("pbuf_take: invalid buf", (buf != NULL), return ERR_ARG;);
  LWIP_ERROR("pbuf_take: invalid dataptr", (dataptr != NULL), return ERR_ARG;);
  LWIP_ERROR("pbuf_take: buf not large enough", (buf->tot_len >= len), return ERR_MEM;);
 
  if ((buf == NULL) || (dataptr == NULL) || (buf->tot_len < len)) {
    return ERR_ARG;
  }
 
  /* Note some systems use byte copy if dataptr or one of the pbuf payload pointers are unaligned. */
  for (p = buf; total_copy_len != 0; p = p->next) {
    LWIP_ASSERT("pbuf_take: invalid pbuf", p != NULL);
    buf_copy_len = total_copy_len;
    if (buf_copy_len > p->len) {
      /* this pbuf cannot hold all remaining data */
      buf_copy_len = p->len;
    }
    /* copy the necessary parts of the buffer */
    MEMCPY(p->payload, &((const char *)dataptr)[copied_total], buf_copy_len);
    total_copy_len -= buf_copy_len;
    copied_total += buf_copy_len;
  }
  LWIP_ASSERT("did not copy all data", total_copy_len == 0 && copied_total == len);
  return ERR_OK;
}

Referenced by eth_mac_irq(), pbuf_take_at(), START_TEST(), tcp_create_segment_wnd(), and test_udp_create_test_packet().

pbuf_take_at()

err_t pbuf_take_at	(	struct pbuf *	buf,
		const void *	dataptr,
		u16_t	len,
		u16_t	offset
	)

Same as pbuf_take() but puts data at an offset

Parameters

buf	pbuf to fill with data
dataptr	application supplied data buffer
len	length of the application supplied data buffer
offset	offset in pbuf where to copy dataptr to

Returns

ERR_OK if successful, ERR_MEM if the pbuf is not big enough

Definition at line 1271 of file pbuf.c.

{
  u16_t target_offset;
  struct pbuf *q = pbuf_skip(buf, offset, &target_offset);
 
  /* return requested data if pbuf is OK */
  if ((q != NULL) && (q->tot_len >= target_offset + len)) {
    u16_t remaining_len = len;
    const u8_t *src_ptr = (const u8_t *)dataptr;
    /* copy the part that goes into the first pbuf */
    u16_t first_copy_len;
    LWIP_ASSERT("check pbuf_skip result", target_offset < q->len);
    first_copy_len = (u16_t)LWIP_MIN(q->len - target_offset, len);
    MEMCPY(((u8_t *)q->payload) + target_offset, dataptr, first_copy_len);
    remaining_len = (u16_t)(remaining_len - first_copy_len);
    src_ptr += first_copy_len;
    if (remaining_len > 0) {
      return pbuf_take(q->next, src_ptr, remaining_len);
    }
    return ERR_OK;
  }
  return ERR_MEM;
}

Referenced by START_TEST().

pbuf_try_get_at()

int pbuf_try_get_at	(	const struct pbuf *	p,
		u16_t	offset
	)

Get one byte from the specified position in a pbuf

Parameters

p	pbuf to parse
offset	offset into p of the byte to return

Returns

byte at an offset into p [0..0xFF] OR negative if 'offset' >= p->tot_len

Definition at line 1420 of file pbuf.c.

{
  u16_t q_idx;
  const struct pbuf *q = pbuf_skip_const(p, offset, &q_idx);
 
  /* return requested data if pbuf is OK */
  if ((q != NULL) && (q->len > q_idx)) {
    return ((u8_t *)q->payload)[q_idx];
  }
  return -1;
}

Referenced by pbuf_get_at().