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583 |
jeremybenn |
/**
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* @file
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* Packet buffer management
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*
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* Packets are built from the pbuf data structure. It supports dynamic
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* memory allocation for packet contents or can reference externally
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* managed packet contents both in RAM and ROM. Quick allocation for
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* incoming packets is provided through pools with fixed sized pbufs.
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*
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* A packet may span over multiple pbufs, chained as a singly linked
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* list. This is called a "pbuf chain".
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*
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* Multiple packets may be queued, also using this singly linked list.
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* This is called a "packet queue".
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*
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* So, a packet queue consists of one or more pbuf chains, each of
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* which consist of one or more pbufs. Currently, queues are only
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* supported in a limited section of lwIP, this is the etharp queueing
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* code. Outside of this section no packet queues are supported yet.
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*
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* The differences between a pbuf chain and a packet queue are very
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* precise but subtle.
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*
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* The last pbuf of a packet has a ->tot_len field that equals the
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* ->len field. It can be found by traversing the list. If the last
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* pbuf of a packet has a ->next field other than NULL, more packets
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* are on the queue.
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*
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* Therefore, looping through a pbuf of a single packet, has an
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* loop end condition (tot_len == p->len), NOT (next == NULL).
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*/
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/*
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* Copyright (c) 2001-2004 Swedish Institute of Computer Science.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without modification,
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* are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
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* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
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* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
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* OF SUCH DAMAGE.
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*
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* This file is part of the lwIP TCP/IP stack.
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*
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* Author: Adam Dunkels <adam@sics.se>
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*
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*/
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#include <string.h>
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#include "lwip/opt.h"
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#include "lwip/stats.h"
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#include "lwip/def.h"
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#include "lwip/mem.h"
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#include "lwip/memp.h"
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#include "lwip/pbuf.h"
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#include "lwip/sys.h"
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#include "arch/perf.h"
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static u8_t pbuf_pool_memory[MEM_ALIGNMENT - 1 + PBUF_POOL_SIZE * MEM_ALIGN_SIZE(PBUF_POOL_BUFSIZE + sizeof(struct pbuf))];
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#if !SYS_LIGHTWEIGHT_PROT
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static volatile u8_t pbuf_pool_free_lock, pbuf_pool_alloc_lock;
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static sys_sem_t pbuf_pool_free_sem;
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#endif
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static struct pbuf *pbuf_pool = NULL;
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/**
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* Initializes the pbuf module.
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*
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* A large part of memory is allocated for holding the pool of pbufs.
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* The size of the individual pbufs in the pool is given by the size
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* parameter, and the number of pbufs in the pool by the num parameter.
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*
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* After the memory has been allocated, the pbufs are set up. The
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* ->next pointer in each pbuf is set up to point to the next pbuf in
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* the pool.
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*
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*/
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void
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pbuf_init(void)
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{
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struct pbuf *p, *q = NULL;
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u16_t i;
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pbuf_pool = (struct pbuf *)MEM_ALIGN(pbuf_pool_memory);
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#if PBUF_STATS
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lwip_stats.pbuf.avail = PBUF_POOL_SIZE;
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#endif /* PBUF_STATS */
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/* Set up ->next pointers to link the pbufs of the pool together */
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p = pbuf_pool;
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for(i = 0; i < PBUF_POOL_SIZE; ++i) {
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p->next = (struct pbuf *)((u8_t *)p + PBUF_POOL_BUFSIZE + sizeof(struct pbuf));
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p->len = p->tot_len = PBUF_POOL_BUFSIZE;
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p->payload = MEM_ALIGN((void *)((u8_t *)p + sizeof(struct pbuf)));
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p->flags = PBUF_FLAG_POOL;
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q = p;
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p = p->next;
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}
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/* The ->next pointer of last pbuf is NULL to indicate that there
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are no more pbufs in the pool */
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q->next = NULL;
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#if !SYS_LIGHTWEIGHT_PROT
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pbuf_pool_alloc_lock = 0;
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pbuf_pool_free_lock = 0;
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pbuf_pool_free_sem = sys_sem_new(1);
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#endif
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}
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/**
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* @internal only called from pbuf_alloc()
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*/
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static struct pbuf *
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pbuf_pool_alloc(void)
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{
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struct pbuf *p = NULL;
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SYS_ARCH_DECL_PROTECT(old_level);
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SYS_ARCH_PROTECT(old_level);
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#if !SYS_LIGHTWEIGHT_PROT
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/* Next, check the actual pbuf pool, but if the pool is locked, we
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pretend to be out of buffers and return NULL. */
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if (pbuf_pool_free_lock) {
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#if PBUF_STATS
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++lwip_stats.pbuf.alloc_locked;
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#endif /* PBUF_STATS */
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return NULL;
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}
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pbuf_pool_alloc_lock = 1;
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if (!pbuf_pool_free_lock) {
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#endif /* SYS_LIGHTWEIGHT_PROT */
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p = pbuf_pool;
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if (p) {
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pbuf_pool = p->next;
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}
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#if !SYS_LIGHTWEIGHT_PROT
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#if PBUF_STATS
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} else {
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++lwip_stats.pbuf.alloc_locked;
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#endif /* PBUF_STATS */
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}
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pbuf_pool_alloc_lock = 0;
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#endif /* SYS_LIGHTWEIGHT_PROT */
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#if PBUF_STATS
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if (p != NULL) {
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++lwip_stats.pbuf.used;
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if (lwip_stats.pbuf.used > lwip_stats.pbuf.max) {
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lwip_stats.pbuf.max = lwip_stats.pbuf.used;
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}
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}
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#endif /* PBUF_STATS */
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SYS_ARCH_UNPROTECT(old_level);
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return p;
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}
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/**
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* Allocates a pbuf of the given type (possibly a chain for PBUF_POOL type).
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*
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* The actual memory allocated for the pbuf is determined by the
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* layer at which the pbuf is allocated and the requested size
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* (from the size parameter).
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*
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* @param flag this parameter decides how and where the pbuf
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* should be allocated as follows:
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*
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* - PBUF_RAM: buffer memory for pbuf is allocated as one large
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* chunk. This includes protocol headers as well.
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* - PBUF_ROM: no buffer memory is allocated for the pbuf, even for
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* protocol headers. Additional headers must be prepended
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* by allocating another pbuf and chain in to the front of
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* the ROM pbuf. It is assumed that the memory used is really
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* similar to ROM in that it is immutable and will not be
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* changed. Memory which is dynamic should generally not
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* be attached to PBUF_ROM pbufs. Use PBUF_REF instead.
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* - PBUF_REF: no buffer memory is allocated for the pbuf, even for
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* protocol headers. It is assumed that the pbuf is only
|
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* being used in a single thread. If the pbuf gets queued,
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* then pbuf_take should be called to copy the buffer.
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* - PBUF_POOL: the pbuf is allocated as a pbuf chain, with pbufs from
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* the pbuf pool that is allocated during pbuf_init().
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*
|
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* @return the allocated pbuf. If multiple pbufs where allocated, this
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* is the first pbuf of a pbuf chain.
|
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*/
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struct pbuf *
|
212 |
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pbuf_alloc(pbuf_layer l, u16_t length, pbuf_flag flag)
|
213 |
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{
|
214 |
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struct pbuf *p, *q, *r;
|
215 |
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u16_t offset;
|
216 |
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s32_t rem_len; /* remaining length */
|
217 |
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LWIP_DEBUGF(PBUF_DEBUG | DBG_TRACE | 3, ("pbuf_alloc(length=%"U16_F")\n", length));
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218 |
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219 |
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/* determine header offset */
|
220 |
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offset = 0;
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221 |
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switch (l) {
|
222 |
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case PBUF_TRANSPORT:
|
223 |
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/* add room for transport (often TCP) layer header */
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224 |
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offset += PBUF_TRANSPORT_HLEN;
|
225 |
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/* FALLTHROUGH */
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226 |
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case PBUF_IP:
|
227 |
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/* add room for IP layer header */
|
228 |
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offset += PBUF_IP_HLEN;
|
229 |
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/* FALLTHROUGH */
|
230 |
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case PBUF_LINK:
|
231 |
|
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/* add room for link layer header */
|
232 |
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offset += PBUF_LINK_HLEN;
|
233 |
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break;
|
234 |
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case PBUF_RAW:
|
235 |
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break;
|
236 |
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default:
|
237 |
|
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LWIP_ASSERT("pbuf_alloc: bad pbuf layer", 0);
|
238 |
|
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return NULL;
|
239 |
|
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}
|
240 |
|
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|
241 |
|
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switch (flag) {
|
242 |
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case PBUF_POOL:
|
243 |
|
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/* allocate head of pbuf chain into p */
|
244 |
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p = pbuf_pool_alloc();
|
245 |
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LWIP_DEBUGF(PBUF_DEBUG | DBG_TRACE | 3, ("pbuf_alloc: allocated pbuf %p\n", (void *)p));
|
246 |
|
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if (p == NULL) {
|
247 |
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#if PBUF_STATS
|
248 |
|
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++lwip_stats.pbuf.err;
|
249 |
|
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#endif /* PBUF_STATS */
|
250 |
|
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return NULL;
|
251 |
|
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}
|
252 |
|
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p->next = NULL;
|
253 |
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|
254 |
|
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/* make the payload pointer point 'offset' bytes into pbuf data memory */
|
255 |
|
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p->payload = MEM_ALIGN((void *)((u8_t *)p + (sizeof(struct pbuf) + offset)));
|
256 |
|
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LWIP_ASSERT("pbuf_alloc: pbuf p->payload properly aligned",
|
257 |
|
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((mem_ptr_t)p->payload % MEM_ALIGNMENT) == 0);
|
258 |
|
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/* the total length of the pbuf chain is the requested size */
|
259 |
|
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p->tot_len = length;
|
260 |
|
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/* set the length of the first pbuf in the chain */
|
261 |
|
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p->len = length > PBUF_POOL_BUFSIZE - offset? PBUF_POOL_BUFSIZE - offset: length;
|
262 |
|
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/* set reference count (needed here in case we fail) */
|
263 |
|
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p->ref = 1;
|
264 |
|
|
|
265 |
|
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/* now allocate the tail of the pbuf chain */
|
266 |
|
|
|
267 |
|
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/* remember first pbuf for linkage in next iteration */
|
268 |
|
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r = p;
|
269 |
|
|
/* remaining length to be allocated */
|
270 |
|
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rem_len = length - p->len;
|
271 |
|
|
/* any remaining pbufs to be allocated? */
|
272 |
|
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while (rem_len > 0) {
|
273 |
|
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q = pbuf_pool_alloc();
|
274 |
|
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if (q == NULL) {
|
275 |
|
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LWIP_DEBUGF(PBUF_DEBUG | 2, ("pbuf_alloc: Out of pbufs in pool.\n"));
|
276 |
|
|
#if PBUF_STATS
|
277 |
|
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++lwip_stats.pbuf.err;
|
278 |
|
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#endif /* PBUF_STATS */
|
279 |
|
|
/* free chain so far allocated */
|
280 |
|
|
pbuf_free(p);
|
281 |
|
|
/* bail out unsuccesfully */
|
282 |
|
|
return NULL;
|
283 |
|
|
}
|
284 |
|
|
q->next = NULL;
|
285 |
|
|
/* make previous pbuf point to this pbuf */
|
286 |
|
|
r->next = q;
|
287 |
|
|
/* set total length of this pbuf and next in chain */
|
288 |
|
|
q->tot_len = rem_len;
|
289 |
|
|
/* this pbuf length is pool size, unless smaller sized tail */
|
290 |
|
|
q->len = rem_len > PBUF_POOL_BUFSIZE? PBUF_POOL_BUFSIZE: rem_len;
|
291 |
|
|
q->payload = (void *)((u8_t *)q + sizeof(struct pbuf));
|
292 |
|
|
LWIP_ASSERT("pbuf_alloc: pbuf q->payload properly aligned",
|
293 |
|
|
((mem_ptr_t)q->payload % MEM_ALIGNMENT) == 0);
|
294 |
|
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q->ref = 1;
|
295 |
|
|
/* calculate remaining length to be allocated */
|
296 |
|
|
rem_len -= q->len;
|
297 |
|
|
/* remember this pbuf for linkage in next iteration */
|
298 |
|
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r = q;
|
299 |
|
|
}
|
300 |
|
|
/* end of chain */
|
301 |
|
|
/*r->next = NULL;*/
|
302 |
|
|
|
303 |
|
|
break;
|
304 |
|
|
case PBUF_RAM:
|
305 |
|
|
/* If pbuf is to be allocated in RAM, allocate memory for it. */
|
306 |
|
|
p = mem_malloc(MEM_ALIGN_SIZE(sizeof(struct pbuf) + offset) + MEM_ALIGN_SIZE(length));
|
307 |
|
|
if (p == NULL) {
|
308 |
|
|
return NULL;
|
309 |
|
|
}
|
310 |
|
|
/* Set up internal structure of the pbuf. */
|
311 |
|
|
p->payload = MEM_ALIGN((void *)((u8_t *)p + sizeof(struct pbuf) + offset));
|
312 |
|
|
p->len = p->tot_len = length;
|
313 |
|
|
p->next = NULL;
|
314 |
|
|
p->flags = PBUF_FLAG_RAM;
|
315 |
|
|
|
316 |
|
|
LWIP_ASSERT("pbuf_alloc: pbuf->payload properly aligned",
|
317 |
|
|
((mem_ptr_t)p->payload % MEM_ALIGNMENT) == 0);
|
318 |
|
|
break;
|
319 |
|
|
/* pbuf references existing (non-volatile static constant) ROM payload? */
|
320 |
|
|
case PBUF_ROM:
|
321 |
|
|
/* pbuf references existing (externally allocated) RAM payload? */
|
322 |
|
|
case PBUF_REF:
|
323 |
|
|
/* only allocate memory for the pbuf structure */
|
324 |
|
|
p = memp_malloc(MEMP_PBUF);
|
325 |
|
|
if (p == NULL) {
|
326 |
|
|
LWIP_DEBUGF(PBUF_DEBUG | DBG_TRACE | 2, ("pbuf_alloc: Could not allocate MEMP_PBUF for PBUF_%s.\n", flag == PBUF_ROM?"ROM":"REF"));
|
327 |
|
|
return NULL;
|
328 |
|
|
}
|
329 |
|
|
/* caller must set this field properly, afterwards */
|
330 |
|
|
p->payload = NULL;
|
331 |
|
|
p->len = p->tot_len = length;
|
332 |
|
|
p->next = NULL;
|
333 |
|
|
p->flags = (flag == PBUF_ROM? PBUF_FLAG_ROM: PBUF_FLAG_REF);
|
334 |
|
|
break;
|
335 |
|
|
default:
|
336 |
|
|
LWIP_ASSERT("pbuf_alloc: erroneous flag", 0);
|
337 |
|
|
return NULL;
|
338 |
|
|
}
|
339 |
|
|
/* set reference count */
|
340 |
|
|
p->ref = 1;
|
341 |
|
|
LWIP_DEBUGF(PBUF_DEBUG | DBG_TRACE | 3, ("pbuf_alloc(length=%"U16_F") == %p\n", length, (void *)p));
|
342 |
|
|
return p;
|
343 |
|
|
}
|
344 |
|
|
|
345 |
|
|
|
346 |
|
|
#if PBUF_STATS
|
347 |
|
|
#define DEC_PBUF_STATS do { --lwip_stats.pbuf.used; } while (0)
|
348 |
|
|
#else /* PBUF_STATS */
|
349 |
|
|
#define DEC_PBUF_STATS
|
350 |
|
|
#endif /* PBUF_STATS */
|
351 |
|
|
|
352 |
|
|
#define PBUF_POOL_FAST_FREE(p) do { \
|
353 |
|
|
p->next = pbuf_pool; \
|
354 |
|
|
pbuf_pool = p; \
|
355 |
|
|
DEC_PBUF_STATS; \
|
356 |
|
|
} while (0)
|
357 |
|
|
|
358 |
|
|
#if SYS_LIGHTWEIGHT_PROT
|
359 |
|
|
#define PBUF_POOL_FREE(p) do { \
|
360 |
|
|
SYS_ARCH_DECL_PROTECT(old_level); \
|
361 |
|
|
SYS_ARCH_PROTECT(old_level); \
|
362 |
|
|
PBUF_POOL_FAST_FREE(p); \
|
363 |
|
|
SYS_ARCH_UNPROTECT(old_level); \
|
364 |
|
|
} while (0)
|
365 |
|
|
#else /* SYS_LIGHTWEIGHT_PROT */
|
366 |
|
|
#define PBUF_POOL_FREE(p) do { \
|
367 |
|
|
sys_sem_wait(pbuf_pool_free_sem); \
|
368 |
|
|
PBUF_POOL_FAST_FREE(p); \
|
369 |
|
|
sys_sem_signal(pbuf_pool_free_sem); \
|
370 |
|
|
} while (0)
|
371 |
|
|
#endif /* SYS_LIGHTWEIGHT_PROT */
|
372 |
|
|
|
373 |
|
|
/**
|
374 |
|
|
* Shrink a pbuf chain to a desired length.
|
375 |
|
|
*
|
376 |
|
|
* @param p pbuf to shrink.
|
377 |
|
|
* @param new_len desired new length of pbuf chain
|
378 |
|
|
*
|
379 |
|
|
* Depending on the desired length, the first few pbufs in a chain might
|
380 |
|
|
* be skipped and left unchanged. The new last pbuf in the chain will be
|
381 |
|
|
* resized, and any remaining pbufs will be freed.
|
382 |
|
|
*
|
383 |
|
|
* @note If the pbuf is ROM/REF, only the ->tot_len and ->len fields are adjusted.
|
384 |
|
|
* @note May not be called on a packet queue.
|
385 |
|
|
*
|
386 |
|
|
* @bug Cannot grow the size of a pbuf (chain) (yet).
|
387 |
|
|
*/
|
388 |
|
|
void
|
389 |
|
|
pbuf_realloc(struct pbuf *p, u16_t new_len)
|
390 |
|
|
{
|
391 |
|
|
struct pbuf *q;
|
392 |
|
|
u16_t rem_len; /* remaining length */
|
393 |
|
|
s16_t grow;
|
394 |
|
|
|
395 |
|
|
LWIP_ASSERT("pbuf_realloc: sane p->flags", p->flags == PBUF_FLAG_POOL ||
|
396 |
|
|
p->flags == PBUF_FLAG_ROM ||
|
397 |
|
|
p->flags == PBUF_FLAG_RAM ||
|
398 |
|
|
p->flags == PBUF_FLAG_REF);
|
399 |
|
|
|
400 |
|
|
/* desired length larger than current length? */
|
401 |
|
|
if (new_len >= p->tot_len) {
|
402 |
|
|
/* enlarging not yet supported */
|
403 |
|
|
return;
|
404 |
|
|
}
|
405 |
|
|
|
406 |
|
|
/* the pbuf chain grows by (new_len - p->tot_len) bytes
|
407 |
|
|
* (which may be negative in case of shrinking) */
|
408 |
|
|
grow = new_len - p->tot_len;
|
409 |
|
|
|
410 |
|
|
/* first, step over any pbufs that should remain in the chain */
|
411 |
|
|
rem_len = new_len;
|
412 |
|
|
q = p;
|
413 |
|
|
/* should this pbuf be kept? */
|
414 |
|
|
while (rem_len > q->len) {
|
415 |
|
|
/* decrease remaining length by pbuf length */
|
416 |
|
|
rem_len -= q->len;
|
417 |
|
|
/* decrease total length indicator */
|
418 |
|
|
q->tot_len += grow;
|
419 |
|
|
/* proceed to next pbuf in chain */
|
420 |
|
|
q = q->next;
|
421 |
|
|
}
|
422 |
|
|
/* we have now reached the new last pbuf (in q) */
|
423 |
|
|
/* rem_len == desired length for pbuf q */
|
424 |
|
|
|
425 |
|
|
/* shrink allocated memory for PBUF_RAM */
|
426 |
|
|
/* (other types merely adjust their length fields */
|
427 |
|
|
if ((q->flags == PBUF_FLAG_RAM) && (rem_len != q->len)) {
|
428 |
|
|
/* reallocate and adjust the length of the pbuf that will be split */
|
429 |
|
|
mem_realloc(q, (u8_t *)q->payload - (u8_t *)q + rem_len);
|
430 |
|
|
}
|
431 |
|
|
/* adjust length fields for new last pbuf */
|
432 |
|
|
q->len = rem_len;
|
433 |
|
|
q->tot_len = q->len;
|
434 |
|
|
|
435 |
|
|
/* any remaining pbufs in chain? */
|
436 |
|
|
if (q->next != NULL) {
|
437 |
|
|
/* free remaining pbufs in chain */
|
438 |
|
|
pbuf_free(q->next);
|
439 |
|
|
}
|
440 |
|
|
/* q is last packet in chain */
|
441 |
|
|
q->next = NULL;
|
442 |
|
|
|
443 |
|
|
}
|
444 |
|
|
|
445 |
|
|
/**
|
446 |
|
|
* Adjusts the payload pointer to hide or reveal headers in the payload.
|
447 |
|
|
*
|
448 |
|
|
* Adjusts the ->payload pointer so that space for a header
|
449 |
|
|
* (dis)appears in the pbuf payload.
|
450 |
|
|
*
|
451 |
|
|
* The ->payload, ->tot_len and ->len fields are adjusted.
|
452 |
|
|
*
|
453 |
|
|
* @param hdr_size_inc Number of bytes to increment header size which
|
454 |
|
|
* increases the size of the pbuf. New space is on the front.
|
455 |
|
|
* (Using a negative value decreases the header size.)
|
456 |
|
|
* If hdr_size_inc is 0, this function does nothing and returns succesful.
|
457 |
|
|
*
|
458 |
|
|
* PBUF_ROM and PBUF_REF type buffers cannot have their sizes increased, so
|
459 |
|
|
* the call will fail. A check is made that the increase in header size does
|
460 |
|
|
* not move the payload pointer in front of the start of the buffer.
|
461 |
|
|
* @return non-zero on failure, zero on success.
|
462 |
|
|
*
|
463 |
|
|
*/
|
464 |
|
|
u8_t
|
465 |
|
|
pbuf_header(struct pbuf *p, s16_t header_size_increment)
|
466 |
|
|
{
|
467 |
|
|
void *payload;
|
468 |
|
|
|
469 |
|
|
LWIP_ASSERT("p != NULL", p != NULL);
|
470 |
|
|
if ((header_size_increment == 0) || (p == NULL)) return 0;
|
471 |
|
|
|
472 |
|
|
/* remember current payload pointer */
|
473 |
|
|
payload = p->payload;
|
474 |
|
|
|
475 |
|
|
/* pbuf types containing payloads? */
|
476 |
|
|
if (p->flags == PBUF_FLAG_RAM || p->flags == PBUF_FLAG_POOL) {
|
477 |
|
|
/* set new payload pointer */
|
478 |
|
|
p->payload = (u8_t *)p->payload - header_size_increment;
|
479 |
|
|
/* boundary check fails? */
|
480 |
|
|
if ((u8_t *)p->payload < (u8_t *)p + sizeof(struct pbuf)) {
|
481 |
|
|
LWIP_DEBUGF( PBUF_DEBUG | 2, ("pbuf_header: failed as %p < %p (not enough space for new header size)\n",
|
482 |
|
|
(void *)p->payload,
|
483 |
|
|
(void *)(p + 1)));\
|
484 |
|
|
/* restore old payload pointer */
|
485 |
|
|
p->payload = payload;
|
486 |
|
|
/* bail out unsuccesfully */
|
487 |
|
|
return 1;
|
488 |
|
|
}
|
489 |
|
|
/* pbuf types refering to external payloads? */
|
490 |
|
|
} else if (p->flags == PBUF_FLAG_REF || p->flags == PBUF_FLAG_ROM) {
|
491 |
|
|
/* hide a header in the payload? */
|
492 |
|
|
if ((header_size_increment < 0) && (header_size_increment - p->len <= 0)) {
|
493 |
|
|
/* increase payload pointer */
|
494 |
|
|
p->payload = (u8_t *)p->payload - header_size_increment;
|
495 |
|
|
} else {
|
496 |
|
|
/* cannot expand payload to front (yet!)
|
497 |
|
|
* bail out unsuccesfully */
|
498 |
|
|
return 1;
|
499 |
|
|
}
|
500 |
|
|
}
|
501 |
|
|
/* modify pbuf length fields */
|
502 |
|
|
p->len += header_size_increment;
|
503 |
|
|
p->tot_len += header_size_increment;
|
504 |
|
|
|
505 |
|
|
LWIP_DEBUGF( PBUF_DEBUG, ("pbuf_header: old %p new %p (%"S16_F")\n",
|
506 |
|
|
(void *)payload, (void *)p->payload, header_size_increment));
|
507 |
|
|
|
508 |
|
|
return 0;
|
509 |
|
|
}
|
510 |
|
|
|
511 |
|
|
/**
|
512 |
|
|
* Dereference a pbuf chain or queue and deallocate any no-longer-used
|
513 |
|
|
* pbufs at the head of this chain or queue.
|
514 |
|
|
*
|
515 |
|
|
* Decrements the pbuf reference count. If it reaches zero, the pbuf is
|
516 |
|
|
* deallocated.
|
517 |
|
|
*
|
518 |
|
|
* For a pbuf chain, this is repeated for each pbuf in the chain,
|
519 |
|
|
* up to the first pbuf which has a non-zero reference count after
|
520 |
|
|
* decrementing. So, when all reference counts are one, the whole
|
521 |
|
|
* chain is free'd.
|
522 |
|
|
*
|
523 |
|
|
* @param pbuf The pbuf (chain) to be dereferenced.
|
524 |
|
|
*
|
525 |
|
|
* @return the number of pbufs that were de-allocated
|
526 |
|
|
* from the head of the chain.
|
527 |
|
|
*
|
528 |
|
|
* @note MUST NOT be called on a packet queue (Not verified to work yet).
|
529 |
|
|
* @note the reference counter of a pbuf equals the number of pointers
|
530 |
|
|
* that refer to the pbuf (or into the pbuf).
|
531 |
|
|
*
|
532 |
|
|
* @internal examples:
|
533 |
|
|
*
|
534 |
|
|
* Assuming existing chains a->b->c with the following reference
|
535 |
|
|
* counts, calling pbuf_free(a) results in:
|
536 |
|
|
*
|
537 |
|
|
* 1->2->3 becomes ...1->3
|
538 |
|
|
* 3->3->3 becomes 2->3->3
|
539 |
|
|
* 1->1->2 becomes ......1
|
540 |
|
|
* 2->1->1 becomes 1->1->1
|
541 |
|
|
* 1->1->1 becomes .......
|
542 |
|
|
*
|
543 |
|
|
*/
|
544 |
|
|
u8_t
|
545 |
|
|
pbuf_free(struct pbuf *p)
|
546 |
|
|
{
|
547 |
|
|
struct pbuf *q;
|
548 |
|
|
u8_t count;
|
549 |
|
|
SYS_ARCH_DECL_PROTECT(old_level);
|
550 |
|
|
|
551 |
|
|
LWIP_ASSERT("p != NULL", p != NULL);
|
552 |
|
|
/* if assertions are disabled, proceed with debug output */
|
553 |
|
|
if (p == NULL) {
|
554 |
|
|
LWIP_DEBUGF(PBUF_DEBUG | DBG_TRACE | 2, ("pbuf_free(p == NULL) was called.\n"));
|
555 |
|
|
return 0;
|
556 |
|
|
}
|
557 |
|
|
LWIP_DEBUGF(PBUF_DEBUG | DBG_TRACE | 3, ("pbuf_free(%p)\n", (void *)p));
|
558 |
|
|
|
559 |
|
|
PERF_START;
|
560 |
|
|
|
561 |
|
|
LWIP_ASSERT("pbuf_free: sane flags",
|
562 |
|
|
p->flags == PBUF_FLAG_RAM || p->flags == PBUF_FLAG_ROM ||
|
563 |
|
|
p->flags == PBUF_FLAG_REF || p->flags == PBUF_FLAG_POOL);
|
564 |
|
|
|
565 |
|
|
count = 0;
|
566 |
|
|
/* Since decrementing ref cannot be guaranteed to be a single machine operation
|
567 |
|
|
* we must protect it. Also, the later test of ref must be protected.
|
568 |
|
|
*/
|
569 |
|
|
SYS_ARCH_PROTECT(old_level);
|
570 |
|
|
/* de-allocate all consecutive pbufs from the head of the chain that
|
571 |
|
|
* obtain a zero reference count after decrementing*/
|
572 |
|
|
while (p != NULL) {
|
573 |
|
|
/* all pbufs in a chain are referenced at least once */
|
574 |
|
|
LWIP_ASSERT("pbuf_free: p->ref > 0", p->ref > 0);
|
575 |
|
|
/* decrease reference count (number of pointers to pbuf) */
|
576 |
|
|
p->ref--;
|
577 |
|
|
/* this pbuf is no longer referenced to? */
|
578 |
|
|
if (p->ref == 0) {
|
579 |
|
|
/* remember next pbuf in chain for next iteration */
|
580 |
|
|
q = p->next;
|
581 |
|
|
LWIP_DEBUGF( PBUF_DEBUG | 2, ("pbuf_free: deallocating %p\n", (void *)p));
|
582 |
|
|
/* is this a pbuf from the pool? */
|
583 |
|
|
if (p->flags == PBUF_FLAG_POOL) {
|
584 |
|
|
p->len = p->tot_len = PBUF_POOL_BUFSIZE;
|
585 |
|
|
p->payload = (void *)((u8_t *)p + sizeof(struct pbuf));
|
586 |
|
|
PBUF_POOL_FREE(p);
|
587 |
|
|
/* is this a ROM or RAM referencing pbuf? */
|
588 |
|
|
} else if (p->flags == PBUF_FLAG_ROM || p->flags == PBUF_FLAG_REF) {
|
589 |
|
|
memp_free(MEMP_PBUF, p);
|
590 |
|
|
/* p->flags == PBUF_FLAG_RAM */
|
591 |
|
|
} else {
|
592 |
|
|
mem_free(p);
|
593 |
|
|
}
|
594 |
|
|
count++;
|
595 |
|
|
/* proceed to next pbuf */
|
596 |
|
|
p = q;
|
597 |
|
|
/* p->ref > 0, this pbuf is still referenced to */
|
598 |
|
|
/* (and so the remaining pbufs in chain as well) */
|
599 |
|
|
} else {
|
600 |
|
|
LWIP_DEBUGF( PBUF_DEBUG | 2, ("pbuf_free: %p has ref %"U16_F", ending here.\n", (void *)p, (u16_t)p->ref));
|
601 |
|
|
/* stop walking through the chain */
|
602 |
|
|
p = NULL;
|
603 |
|
|
}
|
604 |
|
|
}
|
605 |
|
|
SYS_ARCH_UNPROTECT(old_level);
|
606 |
|
|
PERF_STOP("pbuf_free");
|
607 |
|
|
/* return number of de-allocated pbufs */
|
608 |
|
|
return count;
|
609 |
|
|
}
|
610 |
|
|
|
611 |
|
|
/**
|
612 |
|
|
* Count number of pbufs in a chain
|
613 |
|
|
*
|
614 |
|
|
* @param p first pbuf of chain
|
615 |
|
|
* @return the number of pbufs in a chain
|
616 |
|
|
*/
|
617 |
|
|
|
618 |
|
|
u8_t
|
619 |
|
|
pbuf_clen(struct pbuf *p)
|
620 |
|
|
{
|
621 |
|
|
u8_t len;
|
622 |
|
|
|
623 |
|
|
len = 0;
|
624 |
|
|
while (p != NULL) {
|
625 |
|
|
++len;
|
626 |
|
|
p = p->next;
|
627 |
|
|
}
|
628 |
|
|
return len;
|
629 |
|
|
}
|
630 |
|
|
|
631 |
|
|
/**
|
632 |
|
|
* Increment the reference count of the pbuf.
|
633 |
|
|
*
|
634 |
|
|
* @param p pbuf to increase reference counter of
|
635 |
|
|
*
|
636 |
|
|
*/
|
637 |
|
|
void
|
638 |
|
|
pbuf_ref(struct pbuf *p)
|
639 |
|
|
{
|
640 |
|
|
SYS_ARCH_DECL_PROTECT(old_level);
|
641 |
|
|
/* pbuf given? */
|
642 |
|
|
if (p != NULL) {
|
643 |
|
|
SYS_ARCH_PROTECT(old_level);
|
644 |
|
|
++(p->ref);
|
645 |
|
|
SYS_ARCH_UNPROTECT(old_level);
|
646 |
|
|
}
|
647 |
|
|
}
|
648 |
|
|
|
649 |
|
|
/**
|
650 |
|
|
* Concatenate two pbufs (each may be a pbuf chain) and take over
|
651 |
|
|
* the caller's reference of the tail pbuf.
|
652 |
|
|
*
|
653 |
|
|
* @note The caller MAY NOT reference the tail pbuf afterwards.
|
654 |
|
|
* Use pbuf_chain() for that purpose.
|
655 |
|
|
*
|
656 |
|
|
* @see pbuf_chain()
|
657 |
|
|
*/
|
658 |
|
|
|
659 |
|
|
void
|
660 |
|
|
pbuf_cat(struct pbuf *h, struct pbuf *t)
|
661 |
|
|
{
|
662 |
|
|
struct pbuf *p;
|
663 |
|
|
|
664 |
|
|
LWIP_ASSERT("h != NULL (programmer violates API)", h != NULL);
|
665 |
|
|
LWIP_ASSERT("t != NULL (programmer violates API)", t != NULL);
|
666 |
|
|
if ((h == NULL) || (t == NULL)) return;
|
667 |
|
|
|
668 |
|
|
/* proceed to last pbuf of chain */
|
669 |
|
|
for (p = h; p->next != NULL; p = p->next) {
|
670 |
|
|
/* add total length of second chain to all totals of first chain */
|
671 |
|
|
p->tot_len += t->tot_len;
|
672 |
|
|
}
|
673 |
|
|
/* { p is last pbuf of first h chain, p->next == NULL } */
|
674 |
|
|
LWIP_ASSERT("p->tot_len == p->len (of last pbuf in chain)", p->tot_len == p->len);
|
675 |
|
|
LWIP_ASSERT("p->next == NULL", p->next == NULL);
|
676 |
|
|
/* add total length of second chain to last pbuf total of first chain */
|
677 |
|
|
p->tot_len += t->tot_len;
|
678 |
|
|
/* chain last pbuf of head (p) with first of tail (t) */
|
679 |
|
|
p->next = t;
|
680 |
|
|
/* p->next now references t, but the caller will drop its reference to t,
|
681 |
|
|
* so netto there is no change to the reference count of t.
|
682 |
|
|
*/
|
683 |
|
|
}
|
684 |
|
|
|
685 |
|
|
/**
|
686 |
|
|
* Chain two pbufs (or pbuf chains) together.
|
687 |
|
|
*
|
688 |
|
|
* The caller MUST call pbuf_free(t) once it has stopped
|
689 |
|
|
* using it. Use pbuf_cat() instead if you no longer use t.
|
690 |
|
|
*
|
691 |
|
|
* @param h head pbuf (chain)
|
692 |
|
|
* @param t tail pbuf (chain)
|
693 |
|
|
* @note The pbufs MUST belong to the same packet.
|
694 |
|
|
* @note MAY NOT be called on a packet queue.
|
695 |
|
|
*
|
696 |
|
|
* The ->tot_len fields of all pbufs of the head chain are adjusted.
|
697 |
|
|
* The ->next field of the last pbuf of the head chain is adjusted.
|
698 |
|
|
* The ->ref field of the first pbuf of the tail chain is adjusted.
|
699 |
|
|
*
|
700 |
|
|
*/
|
701 |
|
|
void
|
702 |
|
|
pbuf_chain(struct pbuf *h, struct pbuf *t)
|
703 |
|
|
{
|
704 |
|
|
pbuf_cat(h, t);
|
705 |
|
|
/* t is now referenced by h */
|
706 |
|
|
pbuf_ref(t);
|
707 |
|
|
LWIP_DEBUGF(PBUF_DEBUG | DBG_FRESH | 2, ("pbuf_chain: %p references %p\n", (void *)h, (void *)t));
|
708 |
|
|
}
|
709 |
|
|
|
710 |
|
|
/* For packet queueing. Note that queued packets MUST be dequeued first
|
711 |
|
|
* using pbuf_dequeue() before calling other pbuf_() functions. */
|
712 |
|
|
#if ARP_QUEUEING
|
713 |
|
|
/**
|
714 |
|
|
* Add a packet to the end of a queue.
|
715 |
|
|
*
|
716 |
|
|
* @param q pointer to first packet on the queue
|
717 |
|
|
* @param n packet to be queued
|
718 |
|
|
*
|
719 |
|
|
* Both packets MUST be given, and must be different.
|
720 |
|
|
*/
|
721 |
|
|
void
|
722 |
|
|
pbuf_queue(struct pbuf *p, struct pbuf *n)
|
723 |
|
|
{
|
724 |
|
|
#if PBUF_DEBUG /* remember head of queue */
|
725 |
|
|
struct pbuf *q = p;
|
726 |
|
|
#endif
|
727 |
|
|
/* programmer stupidity checks */
|
728 |
|
|
LWIP_ASSERT("p == NULL in pbuf_queue: this indicates a programmer error\n", p != NULL);
|
729 |
|
|
LWIP_ASSERT("n == NULL in pbuf_queue: this indicates a programmer error\n", n != NULL);
|
730 |
|
|
LWIP_ASSERT("p == n in pbuf_queue: this indicates a programmer error\n", p != n);
|
731 |
|
|
if ((p == NULL) || (n == NULL) || (p == n)){
|
732 |
|
|
LWIP_DEBUGF(PBUF_DEBUG | DBG_HALT | 3, ("pbuf_queue: programmer argument error\n"));
|
733 |
|
|
return;
|
734 |
|
|
}
|
735 |
|
|
|
736 |
|
|
/* iterate through all packets on queue */
|
737 |
|
|
while (p->next != NULL) {
|
738 |
|
|
/* be very picky about pbuf chain correctness */
|
739 |
|
|
#if PBUF_DEBUG
|
740 |
|
|
/* iterate through all pbufs in packet */
|
741 |
|
|
while (p->tot_len != p->len) {
|
742 |
|
|
/* make sure invariant condition holds */
|
743 |
|
|
LWIP_ASSERT("p->len < p->tot_len", p->len < p->tot_len);
|
744 |
|
|
/* make sure each packet is complete */
|
745 |
|
|
LWIP_ASSERT("p->next != NULL", p->next != NULL);
|
746 |
|
|
p = p->next;
|
747 |
|
|
/* { p->tot_len == p->len => p is last pbuf of a packet } */
|
748 |
|
|
}
|
749 |
|
|
/* { p is last pbuf of a packet } */
|
750 |
|
|
/* proceed to next packet on queue */
|
751 |
|
|
#endif
|
752 |
|
|
/* proceed to next pbuf */
|
753 |
|
|
if (p->next != NULL) p = p->next;
|
754 |
|
|
}
|
755 |
|
|
/* { p->tot_len == p->len and p->next == NULL } ==>
|
756 |
|
|
* { p is last pbuf of last packet on queue } */
|
757 |
|
|
/* chain last pbuf of queue with n */
|
758 |
|
|
p->next = n;
|
759 |
|
|
/* n is now referenced to by the (packet p in the) queue */
|
760 |
|
|
pbuf_ref(n);
|
761 |
|
|
#if PBUF_DEBUG
|
762 |
|
|
LWIP_DEBUGF(PBUF_DEBUG | DBG_FRESH | 2,
|
763 |
|
|
("pbuf_queue: newly queued packet %p sits after packet %p in queue %p\n",
|
764 |
|
|
(void *)n, (void *)p, (void *)q));
|
765 |
|
|
#endif
|
766 |
|
|
}
|
767 |
|
|
|
768 |
|
|
/**
|
769 |
|
|
* Remove a packet from the head of a queue.
|
770 |
|
|
*
|
771 |
|
|
* The caller MUST reference the remainder of the queue (as returned). The
|
772 |
|
|
* caller MUST NOT call pbuf_ref() as it implicitly takes over the reference
|
773 |
|
|
* from p.
|
774 |
|
|
*
|
775 |
|
|
* @param p pointer to first packet on the queue which will be dequeued.
|
776 |
|
|
* @return first packet on the remaining queue (NULL if no further packets).
|
777 |
|
|
*
|
778 |
|
|
*/
|
779 |
|
|
struct pbuf *
|
780 |
|
|
pbuf_dequeue(struct pbuf *p)
|
781 |
|
|
{
|
782 |
|
|
struct pbuf *q;
|
783 |
|
|
LWIP_ASSERT("p != NULL", p != NULL);
|
784 |
|
|
|
785 |
|
|
/* iterate through all pbufs in packet p */
|
786 |
|
|
while (p->tot_len != p->len) {
|
787 |
|
|
/* make sure invariant condition holds */
|
788 |
|
|
LWIP_ASSERT("p->len < p->tot_len", p->len < p->tot_len);
|
789 |
|
|
/* make sure each packet is complete */
|
790 |
|
|
LWIP_ASSERT("p->next != NULL", p->next != NULL);
|
791 |
|
|
p = p->next;
|
792 |
|
|
}
|
793 |
|
|
/* { p->tot_len == p->len } => p is the last pbuf of the first packet */
|
794 |
|
|
/* remember next packet on queue in q */
|
795 |
|
|
q = p->next;
|
796 |
|
|
/* dequeue packet p from queue */
|
797 |
|
|
p->next = NULL;
|
798 |
|
|
/* any next packet on queue? */
|
799 |
|
|
if (q != NULL) {
|
800 |
|
|
/* although q is no longer referenced by p, it MUST be referenced by
|
801 |
|
|
* the caller, who is maintaining this packet queue. So, we do not call
|
802 |
|
|
* pbuf_free(q) here, resulting in an implicit pbuf_ref(q) for the caller. */
|
803 |
|
|
LWIP_DEBUGF(PBUF_DEBUG | DBG_FRESH | 2, ("pbuf_dequeue: first remaining packet on queue is %p\n", (void *)q));
|
804 |
|
|
} else {
|
805 |
|
|
LWIP_DEBUGF(PBUF_DEBUG | DBG_FRESH | 2, ("pbuf_dequeue: no further packets on queue\n"));
|
806 |
|
|
}
|
807 |
|
|
return q;
|
808 |
|
|
}
|
809 |
|
|
#endif
|
810 |
|
|
|
811 |
|
|
/**
|
812 |
|
|
*
|
813 |
|
|
* Create PBUF_POOL (or PBUF_RAM) copies of PBUF_REF pbufs.
|
814 |
|
|
*
|
815 |
|
|
* Used to queue packets on behalf of the lwIP stack, such as
|
816 |
|
|
* ARP based queueing.
|
817 |
|
|
*
|
818 |
|
|
* Go through a pbuf chain and replace any PBUF_REF buffers
|
819 |
|
|
* with PBUF_POOL (or PBUF_RAM) pbufs, each taking a copy of
|
820 |
|
|
* the referenced data.
|
821 |
|
|
*
|
822 |
|
|
* @note You MUST explicitly use p = pbuf_take(p);
|
823 |
|
|
* The pbuf you give as argument, may have been replaced
|
824 |
|
|
* by a (differently located) copy through pbuf_take()!
|
825 |
|
|
*
|
826 |
|
|
* @note Any replaced pbufs will be freed through pbuf_free().
|
827 |
|
|
* This may deallocate them if they become no longer referenced.
|
828 |
|
|
*
|
829 |
|
|
* @param p Head of pbuf chain to process
|
830 |
|
|
*
|
831 |
|
|
* @return Pointer to head of pbuf chain
|
832 |
|
|
*/
|
833 |
|
|
struct pbuf *
|
834 |
|
|
pbuf_take(struct pbuf *p)
|
835 |
|
|
{
|
836 |
|
|
struct pbuf *q , *prev, *head;
|
837 |
|
|
LWIP_ASSERT("pbuf_take: p != NULL\n", p != NULL);
|
838 |
|
|
LWIP_DEBUGF(PBUF_DEBUG | DBG_TRACE | 3, ("pbuf_take(%p)\n", (void*)p));
|
839 |
|
|
|
840 |
|
|
prev = NULL;
|
841 |
|
|
head = p;
|
842 |
|
|
/* iterate through pbuf chain */
|
843 |
|
|
do
|
844 |
|
|
{
|
845 |
|
|
/* pbuf is of type PBUF_REF? */
|
846 |
|
|
if (p->flags == PBUF_FLAG_REF) {
|
847 |
|
|
LWIP_DEBUGF(PBUF_DEBUG | DBG_TRACE, ("pbuf_take: encountered PBUF_REF %p\n", (void *)p));
|
848 |
|
|
/* allocate a pbuf (w/ payload) fully in RAM */
|
849 |
|
|
/* PBUF_POOL buffers are faster if we can use them */
|
850 |
|
|
if (p->len <= PBUF_POOL_BUFSIZE) {
|
851 |
|
|
q = pbuf_alloc(PBUF_RAW, p->len, PBUF_POOL);
|
852 |
|
|
if (q == NULL) {
|
853 |
|
|
LWIP_DEBUGF(PBUF_DEBUG | DBG_TRACE | 2, ("pbuf_take: Could not allocate PBUF_POOL\n"));
|
854 |
|
|
}
|
855 |
|
|
} else {
|
856 |
|
|
/* no replacement pbuf yet */
|
857 |
|
|
q = NULL;
|
858 |
|
|
LWIP_DEBUGF(PBUF_DEBUG | DBG_TRACE | 2, ("pbuf_take: PBUF_POOL too small to replace PBUF_REF\n"));
|
859 |
|
|
}
|
860 |
|
|
/* no (large enough) PBUF_POOL was available? retry with PBUF_RAM */
|
861 |
|
|
if (q == NULL) {
|
862 |
|
|
q = pbuf_alloc(PBUF_RAW, p->len, PBUF_RAM);
|
863 |
|
|
if (q == NULL) {
|
864 |
|
|
LWIP_DEBUGF(PBUF_DEBUG | DBG_TRACE | 2, ("pbuf_take: Could not allocate PBUF_RAM\n"));
|
865 |
|
|
}
|
866 |
|
|
}
|
867 |
|
|
/* replacement pbuf could be allocated? */
|
868 |
|
|
if (q != NULL)
|
869 |
|
|
{
|
870 |
|
|
/* copy p to q */
|
871 |
|
|
/* copy successor */
|
872 |
|
|
q->next = p->next;
|
873 |
|
|
/* remove linkage from original pbuf */
|
874 |
|
|
p->next = NULL;
|
875 |
|
|
/* remove linkage to original pbuf */
|
876 |
|
|
if (prev != NULL) {
|
877 |
|
|
/* prev->next == p at this point */
|
878 |
|
|
LWIP_ASSERT("prev->next == p", prev->next == p);
|
879 |
|
|
/* break chain and insert new pbuf instead */
|
880 |
|
|
prev->next = q;
|
881 |
|
|
/* prev == NULL, so we replaced the head pbuf of the chain */
|
882 |
|
|
} else {
|
883 |
|
|
head = q;
|
884 |
|
|
}
|
885 |
|
|
/* copy pbuf payload */
|
886 |
|
|
memcpy(q->payload, p->payload, p->len);
|
887 |
|
|
q->tot_len = p->tot_len;
|
888 |
|
|
q->len = p->len;
|
889 |
|
|
/* in case p was the first pbuf, it is no longer refered to by
|
890 |
|
|
* our caller, as the caller MUST do p = pbuf_take(p);
|
891 |
|
|
* in case p was not the first pbuf, it is no longer refered to
|
892 |
|
|
* by prev. we can safely free the pbuf here.
|
893 |
|
|
* (note that we have set p->next to NULL already so that
|
894 |
|
|
* we will not free the rest of the chain by accident.)
|
895 |
|
|
*/
|
896 |
|
|
pbuf_free(p);
|
897 |
|
|
/* do not copy ref, since someone else might be using the old buffer */
|
898 |
|
|
LWIP_DEBUGF(PBUF_DEBUG, ("pbuf_take: replaced PBUF_REF %p with %p\n", (void *)p, (void *)q));
|
899 |
|
|
p = q;
|
900 |
|
|
} else {
|
901 |
|
|
/* deallocate chain */
|
902 |
|
|
pbuf_free(head);
|
903 |
|
|
LWIP_DEBUGF(PBUF_DEBUG | 2, ("pbuf_take: failed to allocate replacement pbuf for %p\n", (void *)p));
|
904 |
|
|
return NULL;
|
905 |
|
|
}
|
906 |
|
|
/* p->flags != PBUF_FLAG_REF */
|
907 |
|
|
} else {
|
908 |
|
|
LWIP_DEBUGF(PBUF_DEBUG | DBG_TRACE | 1, ("pbuf_take: skipping pbuf not of type PBUF_REF\n"));
|
909 |
|
|
}
|
910 |
|
|
/* remember this pbuf */
|
911 |
|
|
prev = p;
|
912 |
|
|
/* proceed to next pbuf in original chain */
|
913 |
|
|
p = p->next;
|
914 |
|
|
} while (p);
|
915 |
|
|
LWIP_DEBUGF(PBUF_DEBUG | DBG_TRACE | 1, ("pbuf_take: end of chain reached.\n"));
|
916 |
|
|
|
917 |
|
|
return head;
|
918 |
|
|
}
|
919 |
|
|
|
920 |
|
|
/**
|
921 |
|
|
* Dechains the first pbuf from its succeeding pbufs in the chain.
|
922 |
|
|
*
|
923 |
|
|
* Makes p->tot_len field equal to p->len.
|
924 |
|
|
* @param p pbuf to dechain
|
925 |
|
|
* @return remainder of the pbuf chain, or NULL if it was de-allocated.
|
926 |
|
|
* @note May not be called on a packet queue.
|
927 |
|
|
*/
|
928 |
|
|
struct pbuf *
|
929 |
|
|
pbuf_dechain(struct pbuf *p)
|
930 |
|
|
{
|
931 |
|
|
struct pbuf *q;
|
932 |
|
|
u8_t tail_gone = 1;
|
933 |
|
|
/* tail */
|
934 |
|
|
q = p->next;
|
935 |
|
|
/* pbuf has successor in chain? */
|
936 |
|
|
if (q != NULL) {
|
937 |
|
|
/* assert tot_len invariant: (p->tot_len == p->len + (p->next? p->next->tot_len: 0) */
|
938 |
|
|
LWIP_ASSERT("p->tot_len == p->len + q->tot_len", q->tot_len == p->tot_len - p->len);
|
939 |
|
|
/* enforce invariant if assertion is disabled */
|
940 |
|
|
q->tot_len = p->tot_len - p->len;
|
941 |
|
|
/* decouple pbuf from remainder */
|
942 |
|
|
p->next = NULL;
|
943 |
|
|
/* total length of pbuf p is its own length only */
|
944 |
|
|
p->tot_len = p->len;
|
945 |
|
|
/* q is no longer referenced by p, free it */
|
946 |
|
|
LWIP_DEBUGF(PBUF_DEBUG | DBG_STATE, ("pbuf_dechain: unreferencing %p\n", (void *)q));
|
947 |
|
|
tail_gone = pbuf_free(q);
|
948 |
|
|
if (tail_gone > 0) {
|
949 |
|
|
LWIP_DEBUGF(PBUF_DEBUG | DBG_STATE,
|
950 |
|
|
("pbuf_dechain: deallocated %p (as it is no longer referenced)\n", (void *)q));
|
951 |
|
|
}
|
952 |
|
|
/* return remaining tail or NULL if deallocated */
|
953 |
|
|
}
|
954 |
|
|
/* assert tot_len invariant: (p->tot_len == p->len + (p->next? p->next->tot_len: 0) */
|
955 |
|
|
LWIP_ASSERT("p->tot_len == p->len", p->tot_len == p->len);
|
956 |
|
|
return (tail_gone > 0? NULL: q);
|
957 |
|
|
}
|