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[/] [openrisc/] [trunk/] [rtos/] [freertos-6.1.1/] [Demo/] [Common/] [ethernet/] [lwIP_130/] [src/] [core/] [pbuf.c] - Blame information for rev 606

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Line No. Rev Author Line
1 606 jeremybenn
/**
2
 * @file
3
 * Packet buffer management
4
 *
5
 * Packets are built from the pbuf data structure. It supports dynamic
6
 * memory allocation for packet contents or can reference externally
7
 * managed packet contents both in RAM and ROM. Quick allocation for
8
 * incoming packets is provided through pools with fixed sized pbufs.
9
 *
10
 * A packet may span over multiple pbufs, chained as a singly linked
11
 * list. This is called a "pbuf chain".
12
 *
13
 * Multiple packets may be queued, also using this singly linked list.
14
 * This is called a "packet queue".
15
 *
16
 * So, a packet queue consists of one or more pbuf chains, each of
17
 * which consist of one or more pbufs. CURRENTLY, PACKET QUEUES ARE
18
 * NOT SUPPORTED!!! Use helper structs to queue multiple packets.
19
 *
20
 * The differences between a pbuf chain and a packet queue are very
21
 * precise but subtle.
22
 *
23
 * The last pbuf of a packet has a ->tot_len field that equals the
24
 * ->len field. It can be found by traversing the list. If the last
25
 * pbuf of a packet has a ->next field other than NULL, more packets
26
 * are on the queue.
27
 *
28
 * Therefore, looping through a pbuf of a single packet, has an
29
 * loop end condition (tot_len == p->len), NOT (next == NULL).
30
 */
31
 
32
/*
33
 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
34
 * All rights reserved.
35
 *
36
 * Redistribution and use in source and binary forms, with or without modification,
37
 * are permitted provided that the following conditions are met:
38
 *
39
 * 1. Redistributions of source code must retain the above copyright notice,
40
 *    this list of conditions and the following disclaimer.
41
 * 2. Redistributions in binary form must reproduce the above copyright notice,
42
 *    this list of conditions and the following disclaimer in the documentation
43
 *    and/or other materials provided with the distribution.
44
 * 3. The name of the author may not be used to endorse or promote products
45
 *    derived from this software without specific prior written permission.
46
 *
47
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
48
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
49
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
50
 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
51
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
52
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
53
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
54
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
55
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
56
 * OF SUCH DAMAGE.
57
 *
58
 * This file is part of the lwIP TCP/IP stack.
59
 *
60
 * Author: Adam Dunkels <adam@sics.se>
61
 *
62
 */
63
 
64
#include "lwip/opt.h"
65
 
66
#include "lwip/stats.h"
67
#include "lwip/def.h"
68
#include "lwip/mem.h"
69
#include "lwip/memp.h"
70
#include "lwip/pbuf.h"
71
#include "lwip/sys.h"
72
#include "arch/perf.h"
73
 
74
#include <string.h>
75
 
76
#define SIZEOF_STRUCT_PBUF        LWIP_MEM_ALIGN_SIZE(sizeof(struct pbuf))
77
/* Since the pool is created in memp, PBUF_POOL_BUFSIZE will be automatically
78
   aligned there. Therefore, PBUF_POOL_BUFSIZE_ALIGNED can be used here. */
79
#define PBUF_POOL_BUFSIZE_ALIGNED LWIP_MEM_ALIGN_SIZE(PBUF_POOL_BUFSIZE)
80
 
81
/**
82
 * Allocates a pbuf of the given type (possibly a chain for PBUF_POOL type).
83
 *
84
 * The actual memory allocated for the pbuf is determined by the
85
 * layer at which the pbuf is allocated and the requested size
86
 * (from the size parameter).
87
 *
88
 * @param layer flag to define header size
89
 * @param length size of the pbuf's payload
90
 * @param type this parameter decides how and where the pbuf
91
 * should be allocated as follows:
92
 *
93
 * - PBUF_RAM: buffer memory for pbuf is allocated as one large
94
 *             chunk. This includes protocol headers as well.
95
 * - PBUF_ROM: no buffer memory is allocated for the pbuf, even for
96
 *             protocol headers. Additional headers must be prepended
97
 *             by allocating another pbuf and chain in to the front of
98
 *             the ROM pbuf. It is assumed that the memory used is really
99
 *             similar to ROM in that it is immutable and will not be
100
 *             changed. Memory which is dynamic should generally not
101
 *             be attached to PBUF_ROM pbufs. Use PBUF_REF instead.
102
 * - PBUF_REF: no buffer memory is allocated for the pbuf, even for
103
 *             protocol headers. It is assumed that the pbuf is only
104
 *             being used in a single thread. If the pbuf gets queued,
105
 *             then pbuf_take should be called to copy the buffer.
106
 * - PBUF_POOL: the pbuf is allocated as a pbuf chain, with pbufs from
107
 *              the pbuf pool that is allocated during pbuf_init().
108
 *
109
 * @return the allocated pbuf. If multiple pbufs where allocated, this
110
 * is the first pbuf of a pbuf chain.
111
 */
112
struct pbuf *
113
pbuf_alloc(pbuf_layer layer, u16_t length, pbuf_type type)
114
{
115
  struct pbuf *p, *q, *r;
116
  u16_t offset;
117
  s32_t rem_len; /* remaining length */
118
  LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE | 3, ("pbuf_alloc(length=%"U16_F")\n", length));
119
 
120
  /* determine header offset */
121
  offset = 0;
122
  switch (layer) {
123
  case PBUF_TRANSPORT:
124
    /* add room for transport (often TCP) layer header */
125
    offset += PBUF_TRANSPORT_HLEN;
126
    /* FALLTHROUGH */
127
  case PBUF_IP:
128
    /* add room for IP layer header */
129
    offset += PBUF_IP_HLEN;
130
    /* FALLTHROUGH */
131
  case PBUF_LINK:
132
    /* add room for link layer header */
133
    offset += PBUF_LINK_HLEN;
134
    break;
135
  case PBUF_RAW:
136
    break;
137
  default:
138
    LWIP_ASSERT("pbuf_alloc: bad pbuf layer", 0);
139
    return NULL;
140
  }
141
 
142
  switch (type) {
143
  case PBUF_POOL:
144
    /* allocate head of pbuf chain into p */
145
      p = memp_malloc(MEMP_PBUF_POOL);
146
    LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE | 3, ("pbuf_alloc: allocated pbuf %p\n", (void *)p));
147
    if (p == NULL) {
148
      return NULL;
149
    }
150
    p->type = type;
151
    p->next = NULL;
152
 
153
    /* make the payload pointer point 'offset' bytes into pbuf data memory */
154
    p->payload = LWIP_MEM_ALIGN((void *)((u8_t *)p + (SIZEOF_STRUCT_PBUF + offset)));
155
    LWIP_ASSERT("pbuf_alloc: pbuf p->payload properly aligned",
156
            ((mem_ptr_t)p->payload % MEM_ALIGNMENT) == 0);
157
    /* the total length of the pbuf chain is the requested size */
158
    p->tot_len = length;
159
    /* set the length of the first pbuf in the chain */
160
    p->len = LWIP_MIN(length, PBUF_POOL_BUFSIZE_ALIGNED - LWIP_MEM_ALIGN_SIZE(offset));
161
    LWIP_ASSERT("check p->payload + p->len does not overflow pbuf",
162
                ((u8_t*)p->payload + p->len <=
163
                 (u8_t*)p + SIZEOF_STRUCT_PBUF + PBUF_POOL_BUFSIZE_ALIGNED));
164
    /* set reference count (needed here in case we fail) */
165
    p->ref = 1;
166
 
167
    /* now allocate the tail of the pbuf chain */
168
 
169
    /* remember first pbuf for linkage in next iteration */
170
    r = p;
171
    /* remaining length to be allocated */
172
    rem_len = length - p->len;
173
    /* any remaining pbufs to be allocated? */
174
    while (rem_len > 0) {
175
      q = memp_malloc(MEMP_PBUF_POOL);
176
      if (q == NULL) {
177
        /* free chain so far allocated */
178
        pbuf_free(p);
179
        /* bail out unsuccesfully */
180
        return NULL;
181
      }
182
      q->type = type;
183
      q->flags = 0;
184
      q->next = NULL;
185
      /* make previous pbuf point to this pbuf */
186
      r->next = q;
187
      /* set total length of this pbuf and next in chain */
188
      LWIP_ASSERT("rem_len < max_u16_t", rem_len < 0xffff);
189
      q->tot_len = (u16_t)rem_len;
190
      /* this pbuf length is pool size, unless smaller sized tail */
191
      q->len = LWIP_MIN((u16_t)rem_len, PBUF_POOL_BUFSIZE_ALIGNED);
192
      q->payload = (void *)((u8_t *)q + SIZEOF_STRUCT_PBUF);
193
      LWIP_ASSERT("pbuf_alloc: pbuf q->payload properly aligned",
194
              ((mem_ptr_t)q->payload % MEM_ALIGNMENT) == 0);
195
      LWIP_ASSERT("check p->payload + p->len does not overflow pbuf",
196
                  ((u8_t*)p->payload + p->len <=
197
                   (u8_t*)p + SIZEOF_STRUCT_PBUF + PBUF_POOL_BUFSIZE_ALIGNED));
198
      q->ref = 1;
199
      /* calculate remaining length to be allocated */
200
      rem_len -= q->len;
201
      /* remember this pbuf for linkage in next iteration */
202
      r = q;
203
    }
204
    /* end of chain */
205
    /*r->next = NULL;*/
206
 
207
    break;
208
  case PBUF_RAM:
209
    /* If pbuf is to be allocated in RAM, allocate memory for it. */
210
    p = (struct pbuf*)mem_malloc(LWIP_MEM_ALIGN_SIZE(SIZEOF_STRUCT_PBUF + offset) + LWIP_MEM_ALIGN_SIZE(length));
211
    if (p == NULL) {
212
      return NULL;
213
    }
214
    /* Set up internal structure of the pbuf. */
215
    p->payload = LWIP_MEM_ALIGN((void *)((u8_t *)p + SIZEOF_STRUCT_PBUF + offset));
216
    p->len = p->tot_len = length;
217
    p->next = NULL;
218
    p->type = type;
219
 
220
    LWIP_ASSERT("pbuf_alloc: pbuf->payload properly aligned",
221
           ((mem_ptr_t)p->payload % MEM_ALIGNMENT) == 0);
222
    break;
223
  /* pbuf references existing (non-volatile static constant) ROM payload? */
224
  case PBUF_ROM:
225
  /* pbuf references existing (externally allocated) RAM payload? */
226
  case PBUF_REF:
227
    /* only allocate memory for the pbuf structure */
228
    p = memp_malloc(MEMP_PBUF);
229
    if (p == NULL) {
230
      LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE | 2, ("pbuf_alloc: Could not allocate MEMP_PBUF for PBUF_%s.\n",
231
                  (type == PBUF_ROM) ? "ROM" : "REF"));
232
      return NULL;
233
    }
234
    /* caller must set this field properly, afterwards */
235
    p->payload = NULL;
236
    p->len = p->tot_len = length;
237
    p->next = NULL;
238
    p->type = type;
239
    break;
240
  default:
241
    LWIP_ASSERT("pbuf_alloc: erroneous type", 0);
242
    return NULL;
243
  }
244
  /* set reference count */
245
  p->ref = 1;
246
  /* set flags */
247
  p->flags = 0;
248
  LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE | 3, ("pbuf_alloc(length=%"U16_F") == %p\n", length, (void *)p));
249
  return p;
250
}
251
 
252
 
253
/**
254
 * Shrink a pbuf chain to a desired length.
255
 *
256
 * @param p pbuf to shrink.
257
 * @param new_len desired new length of pbuf chain
258
 *
259
 * Depending on the desired length, the first few pbufs in a chain might
260
 * be skipped and left unchanged. The new last pbuf in the chain will be
261
 * resized, and any remaining pbufs will be freed.
262
 *
263
 * @note If the pbuf is ROM/REF, only the ->tot_len and ->len fields are adjusted.
264
 * @note May not be called on a packet queue.
265
 *
266
 * @note Despite its name, pbuf_realloc cannot grow the size of a pbuf (chain).
267
 */
268
void
269
pbuf_realloc(struct pbuf *p, u16_t new_len)
270
{
271
  struct pbuf *q;
272
  u16_t rem_len; /* remaining length */
273
  s32_t grow;
274
 
275
  LWIP_ASSERT("pbuf_realloc: sane p->type", p->type == PBUF_POOL ||
276
              p->type == PBUF_ROM ||
277
              p->type == PBUF_RAM ||
278
              p->type == PBUF_REF);
279
 
280
  /* desired length larger than current length? */
281
  if (new_len >= p->tot_len) {
282
    /* enlarging not yet supported */
283
    return;
284
  }
285
 
286
  /* the pbuf chain grows by (new_len - p->tot_len) bytes
287
   * (which may be negative in case of shrinking) */
288
  grow = new_len - p->tot_len;
289
 
290
  /* first, step over any pbufs that should remain in the chain */
291
  rem_len = new_len;
292
  q = p;
293
  /* should this pbuf be kept? */
294
  while (rem_len > q->len) {
295
    /* decrease remaining length by pbuf length */
296
    rem_len -= q->len;
297
    /* decrease total length indicator */
298
    LWIP_ASSERT("grow < max_u16_t", grow < 0xffff);
299
    q->tot_len += (u16_t)grow;
300
    /* proceed to next pbuf in chain */
301
    q = q->next;
302
  }
303
  /* we have now reached the new last pbuf (in q) */
304
  /* rem_len == desired length for pbuf q */
305
 
306
  /* shrink allocated memory for PBUF_RAM */
307
  /* (other types merely adjust their length fields */
308
  if ((q->type == PBUF_RAM) && (rem_len != q->len)) {
309
    /* reallocate and adjust the length of the pbuf that will be split */
310
    q = mem_realloc(q, (u8_t *)q->payload - (u8_t *)q + rem_len);
311
    LWIP_ASSERT("mem_realloc give q == NULL", q != NULL);
312
  }
313
  /* adjust length fields for new last pbuf */
314
  q->len = rem_len;
315
  q->tot_len = q->len;
316
 
317
  /* any remaining pbufs in chain? */
318
  if (q->next != NULL) {
319
    /* free remaining pbufs in chain */
320
    pbuf_free(q->next);
321
  }
322
  /* q is last packet in chain */
323
  q->next = NULL;
324
 
325
}
326
 
327
/**
328
 * Adjusts the payload pointer to hide or reveal headers in the payload.
329
 *
330
 * Adjusts the ->payload pointer so that space for a header
331
 * (dis)appears in the pbuf payload.
332
 *
333
 * The ->payload, ->tot_len and ->len fields are adjusted.
334
 *
335
 * @param p pbuf to change the header size.
336
 * @param header_size_increment Number of bytes to increment header size which
337
 * increases the size of the pbuf. New space is on the front.
338
 * (Using a negative value decreases the header size.)
339
 * If hdr_size_inc is 0, this function does nothing and returns succesful.
340
 *
341
 * PBUF_ROM and PBUF_REF type buffers cannot have their sizes increased, so
342
 * the call will fail. A check is made that the increase in header size does
343
 * not move the payload pointer in front of the start of the buffer.
344
 * @return non-zero on failure, zero on success.
345
 *
346
 */
347
u8_t
348
pbuf_header(struct pbuf *p, s16_t header_size_increment)
349
{
350
  u16_t type;
351
  void *payload;
352
  u16_t increment_magnitude;
353
 
354
  LWIP_ASSERT("p != NULL", p != NULL);
355
  if ((header_size_increment == 0) || (p == NULL))
356
    return 0;
357
 
358
  if (header_size_increment < 0){
359
    increment_magnitude = -header_size_increment;
360
    /* Check that we aren't going to move off the end of the pbuf */
361
    LWIP_ERROR("increment_magnitude <= p->len", (increment_magnitude <= p->len), return 1;);
362
  } else {
363
    increment_magnitude = header_size_increment;
364
#if 0
365
    /* Can't assert these as some callers speculatively call
366
         pbuf_header() to see if it's OK.  Will return 1 below instead. */
367
    /* Check that we've got the correct type of pbuf to work with */
368
    LWIP_ASSERT("p->type == PBUF_RAM || p->type == PBUF_POOL",
369
                p->type == PBUF_RAM || p->type == PBUF_POOL);
370
    /* Check that we aren't going to move off the beginning of the pbuf */
371
    LWIP_ASSERT("p->payload - increment_magnitude >= p + SIZEOF_STRUCT_PBUF",
372
                (u8_t *)p->payload - increment_magnitude >= (u8_t *)p + SIZEOF_STRUCT_PBUF);
373
#endif
374
  }
375
 
376
  type = p->type;
377
  /* remember current payload pointer */
378
  payload = p->payload;
379
 
380
  /* pbuf types containing payloads? */
381
  if (type == PBUF_RAM || type == PBUF_POOL) {
382
    /* set new payload pointer */
383
    p->payload = (u8_t *)p->payload - header_size_increment;
384
    /* boundary check fails? */
385
    if ((u8_t *)p->payload < (u8_t *)p + SIZEOF_STRUCT_PBUF) {
386
      LWIP_DEBUGF( PBUF_DEBUG | 2, ("pbuf_header: failed as %p < %p (not enough space for new header size)\n",
387
        (void *)p->payload,
388
        (void *)(p + 1)));\
389
      /* restore old payload pointer */
390
      p->payload = payload;
391
      /* bail out unsuccesfully */
392
      return 1;
393
    }
394
  /* pbuf types refering to external payloads? */
395
  } else if (type == PBUF_REF || type == PBUF_ROM) {
396
    /* hide a header in the payload? */
397
    if ((header_size_increment < 0) && (increment_magnitude <= p->len)) {
398
      /* increase payload pointer */
399
      p->payload = (u8_t *)p->payload - header_size_increment;
400
    } else {
401
      /* cannot expand payload to front (yet!)
402
       * bail out unsuccesfully */
403
      return 1;
404
    }
405
  }
406
  else {
407
    /* Unknown type */
408
    LWIP_ASSERT("bad pbuf type", 0);
409
    return 1;
410
  }
411
  /* modify pbuf length fields */
412
  p->len += header_size_increment;
413
  p->tot_len += header_size_increment;
414
 
415
  LWIP_DEBUGF(PBUF_DEBUG, ("pbuf_header: old %p new %p (%"S16_F")\n",
416
    (void *)payload, (void *)p->payload, header_size_increment));
417
 
418
  return 0;
419
}
420
 
421
/**
422
 * Dereference a pbuf chain or queue and deallocate any no-longer-used
423
 * pbufs at the head of this chain or queue.
424
 *
425
 * Decrements the pbuf reference count. If it reaches zero, the pbuf is
426
 * deallocated.
427
 *
428
 * For a pbuf chain, this is repeated for each pbuf in the chain,
429
 * up to the first pbuf which has a non-zero reference count after
430
 * decrementing. So, when all reference counts are one, the whole
431
 * chain is free'd.
432
 *
433
 * @param p The pbuf (chain) to be dereferenced.
434
 *
435
 * @return the number of pbufs that were de-allocated
436
 * from the head of the chain.
437
 *
438
 * @note MUST NOT be called on a packet queue (Not verified to work yet).
439
 * @note the reference counter of a pbuf equals the number of pointers
440
 * that refer to the pbuf (or into the pbuf).
441
 *
442
 * @internal examples:
443
 *
444
 * Assuming existing chains a->b->c with the following reference
445
 * counts, calling pbuf_free(a) results in:
446
 *
447
 * 1->2->3 becomes ...1->3
448
 * 3->3->3 becomes 2->3->3
449
 * 1->1->2 becomes ......1
450
 * 2->1->1 becomes 1->1->1
451
 * 1->1->1 becomes .......
452
 *
453
 */
454
u8_t
455
pbuf_free(struct pbuf *p)
456
{
457
  u16_t type;
458
  struct pbuf *q;
459
  u8_t count;
460
 
461
  if (p == NULL) {
462
    LWIP_ASSERT("p != NULL", p != NULL);
463
    /* if assertions are disabled, proceed with debug output */
464
    LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE | 2, ("pbuf_free(p == NULL) was called.\n"));
465
    return 0;
466
  }
467
  LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE | 3, ("pbuf_free(%p)\n", (void *)p));
468
 
469
  PERF_START;
470
 
471
  LWIP_ASSERT("pbuf_free: sane type",
472
    p->type == PBUF_RAM || p->type == PBUF_ROM ||
473
    p->type == PBUF_REF || p->type == PBUF_POOL);
474
 
475
  count = 0;
476
  /* de-allocate all consecutive pbufs from the head of the chain that
477
   * obtain a zero reference count after decrementing*/
478
  while (p != NULL) {
479
    u16_t ref;
480
    SYS_ARCH_DECL_PROTECT(old_level);
481
    /* Since decrementing ref cannot be guaranteed to be a single machine operation
482
     * we must protect it. We put the new ref into a local variable to prevent
483
     * further protection. */
484
    SYS_ARCH_PROTECT(old_level);
485
    /* all pbufs in a chain are referenced at least once */
486
    LWIP_ASSERT("pbuf_free: p->ref > 0", p->ref > 0);
487
    /* decrease reference count (number of pointers to pbuf) */
488
    ref = --(p->ref);
489
    SYS_ARCH_UNPROTECT(old_level);
490
    /* this pbuf is no longer referenced to? */
491
    if (ref == 0) {
492
      /* remember next pbuf in chain for next iteration */
493
      q = p->next;
494
      LWIP_DEBUGF( PBUF_DEBUG | 2, ("pbuf_free: deallocating %p\n", (void *)p));
495
      type = p->type;
496
      /* is this a pbuf from the pool? */
497
      if (type == PBUF_POOL) {
498
        memp_free(MEMP_PBUF_POOL, p);
499
      /* is this a ROM or RAM referencing pbuf? */
500
      } else if (type == PBUF_ROM || type == PBUF_REF) {
501
        memp_free(MEMP_PBUF, p);
502
      /* type == PBUF_RAM */
503
      } else {
504
        mem_free(p);
505
      }
506
      count++;
507
      /* proceed to next pbuf */
508
      p = q;
509
    /* p->ref > 0, this pbuf is still referenced to */
510
    /* (and so the remaining pbufs in chain as well) */
511
    } else {
512
      LWIP_DEBUGF( PBUF_DEBUG | 2, ("pbuf_free: %p has ref %"U16_F", ending here.\n", (void *)p, ref));
513
      /* stop walking through the chain */
514
      p = NULL;
515
    }
516
  }
517
  PERF_STOP("pbuf_free");
518
  /* return number of de-allocated pbufs */
519
  return count;
520
}
521
 
522
/**
523
 * Count number of pbufs in a chain
524
 *
525
 * @param p first pbuf of chain
526
 * @return the number of pbufs in a chain
527
 */
528
 
529
u8_t
530
pbuf_clen(struct pbuf *p)
531
{
532
  u8_t len;
533
 
534
  len = 0;
535
  while (p != NULL) {
536
    ++len;
537
    p = p->next;
538
  }
539
  return len;
540
}
541
 
542
/**
543
 * Increment the reference count of the pbuf.
544
 *
545
 * @param p pbuf to increase reference counter of
546
 *
547
 */
548
void
549
pbuf_ref(struct pbuf *p)
550
{
551
  SYS_ARCH_DECL_PROTECT(old_level);
552
  /* pbuf given? */
553
  if (p != NULL) {
554
    SYS_ARCH_PROTECT(old_level);
555
    ++(p->ref);
556
    SYS_ARCH_UNPROTECT(old_level);
557
  }
558
}
559
 
560
/**
561
 * Concatenate two pbufs (each may be a pbuf chain) and take over
562
 * the caller's reference of the tail pbuf.
563
 *
564
 * @note The caller MAY NOT reference the tail pbuf afterwards.
565
 * Use pbuf_chain() for that purpose.
566
 *
567
 * @see pbuf_chain()
568
 */
569
 
570
void
571
pbuf_cat(struct pbuf *h, struct pbuf *t)
572
{
573
  struct pbuf *p;
574
 
575
  LWIP_ERROR("(h != NULL) && (t != NULL) (programmer violates API)",
576
             ((h != NULL) && (t != NULL)), return;);
577
 
578
  /* proceed to last pbuf of chain */
579
  for (p = h; p->next != NULL; p = p->next) {
580
    /* add total length of second chain to all totals of first chain */
581
    p->tot_len += t->tot_len;
582
  }
583
  /* { p is last pbuf of first h chain, p->next == NULL } */
584
  LWIP_ASSERT("p->tot_len == p->len (of last pbuf in chain)", p->tot_len == p->len);
585
  LWIP_ASSERT("p->next == NULL", p->next == NULL);
586
  /* add total length of second chain to last pbuf total of first chain */
587
  p->tot_len += t->tot_len;
588
  /* chain last pbuf of head (p) with first of tail (t) */
589
  p->next = t;
590
  /* p->next now references t, but the caller will drop its reference to t,
591
   * so netto there is no change to the reference count of t.
592
   */
593
}
594
 
595
/**
596
 * Chain two pbufs (or pbuf chains) together.
597
 *
598
 * The caller MUST call pbuf_free(t) once it has stopped
599
 * using it. Use pbuf_cat() instead if you no longer use t.
600
 *
601
 * @param h head pbuf (chain)
602
 * @param t tail pbuf (chain)
603
 * @note The pbufs MUST belong to the same packet.
604
 * @note MAY NOT be called on a packet queue.
605
 *
606
 * The ->tot_len fields of all pbufs of the head chain are adjusted.
607
 * The ->next field of the last pbuf of the head chain is adjusted.
608
 * The ->ref field of the first pbuf of the tail chain is adjusted.
609
 *
610
 */
611
void
612
pbuf_chain(struct pbuf *h, struct pbuf *t)
613
{
614
  pbuf_cat(h, t);
615
  /* t is now referenced by h */
616
  pbuf_ref(t);
617
  LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_FRESH | 2, ("pbuf_chain: %p references %p\n", (void *)h, (void *)t));
618
}
619
 
620
/**
621
 * Dechains the first pbuf from its succeeding pbufs in the chain.
622
 *
623
 * Makes p->tot_len field equal to p->len.
624
 * @param p pbuf to dechain
625
 * @return remainder of the pbuf chain, or NULL if it was de-allocated.
626
 * @note May not be called on a packet queue.
627
 */
628
struct pbuf *
629
pbuf_dechain(struct pbuf *p)
630
{
631
  struct pbuf *q;
632
  u8_t tail_gone = 1;
633
  /* tail */
634
  q = p->next;
635
  /* pbuf has successor in chain? */
636
  if (q != NULL) {
637
    /* assert tot_len invariant: (p->tot_len == p->len + (p->next? p->next->tot_len: 0) */
638
    LWIP_ASSERT("p->tot_len == p->len + q->tot_len", q->tot_len == p->tot_len - p->len);
639
    /* enforce invariant if assertion is disabled */
640
    q->tot_len = p->tot_len - p->len;
641
    /* decouple pbuf from remainder */
642
    p->next = NULL;
643
    /* total length of pbuf p is its own length only */
644
    p->tot_len = p->len;
645
    /* q is no longer referenced by p, free it */
646
    LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_STATE, ("pbuf_dechain: unreferencing %p\n", (void *)q));
647
    tail_gone = pbuf_free(q);
648
    if (tail_gone > 0) {
649
      LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_STATE,
650
                  ("pbuf_dechain: deallocated %p (as it is no longer referenced)\n", (void *)q));
651
    }
652
    /* return remaining tail or NULL if deallocated */
653
  }
654
  /* assert tot_len invariant: (p->tot_len == p->len + (p->next? p->next->tot_len: 0) */
655
  LWIP_ASSERT("p->tot_len == p->len", p->tot_len == p->len);
656
  return ((tail_gone > 0) ? NULL : q);
657
}
658
 
659
/**
660
 *
661
 * Create PBUF_RAM copies of pbufs.
662
 *
663
 * Used to queue packets on behalf of the lwIP stack, such as
664
 * ARP based queueing.
665
 *
666
 * @note You MUST explicitly use p = pbuf_take(p);
667
 *
668
 * @note Only one packet is copied, no packet queue!
669
 *
670
 * @param p_to pbuf source of the copy
671
 * @param p_from pbuf destination of the copy
672
 *
673
 * @return ERR_OK if pbuf was copied
674
 *         ERR_ARG if one of the pbufs is NULL or p_to is not big
675
 *                 enough to hold p_from
676
 */
677
err_t
678
pbuf_copy(struct pbuf *p_to, struct pbuf *p_from)
679
{
680
  u16_t offset_to=0, offset_from=0, len;
681
 
682
  LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE | 3, ("pbuf_copy(%p, %p)\n",
683
    (void*)p_to, (void*)p_from));
684
 
685
  /* is the target big enough to hold the source? */
686
  LWIP_ERROR("pbuf_copy: target not big enough to hold source", ((p_to != NULL) &&
687
             (p_from != NULL) && (p_to->tot_len >= p_from->tot_len)), return ERR_ARG;);
688
 
689
  /* iterate through pbuf chain */
690
  do
691
  {
692
    LWIP_ASSERT("p_to != NULL", p_to != NULL);
693
    /* copy one part of the original chain */
694
    if ((p_to->len - offset_to) >= (p_from->len - offset_from)) {
695
      /* complete current p_from fits into current p_to */
696
      len = p_from->len - offset_from;
697
    } else {
698
      /* current p_from does not fit into current p_to */
699
      len = p_to->len - offset_to;
700
    }
701
    MEMCPY((u8_t*)p_to->payload + offset_to, (u8_t*)p_from->payload + offset_from, len);
702
    offset_to += len;
703
    offset_from += len;
704
    LWIP_ASSERT("offset_to <= p_to->len", offset_to <= p_to->len);
705
    if (offset_to == p_to->len) {
706
      /* on to next p_to (if any) */
707
      offset_to = 0;
708
      p_to = p_to->next;
709
    }
710
    LWIP_ASSERT("offset_from <= p_from->len", offset_from <= p_from->len);
711
    if (offset_from >= p_from->len) {
712
      /* on to next p_from (if any) */
713
      offset_from = 0;
714
      p_from = p_from->next;
715
    }
716
 
717
    if((p_from != NULL) && (p_from->len == p_from->tot_len)) {
718
      /* don't copy more than one packet! */
719
      LWIP_ERROR("pbuf_copy() does not allow packet queues!\n",
720
                 (p_from->next == NULL), return ERR_VAL;);
721
    }
722
    if((p_to != NULL) && (p_to->len == p_to->tot_len)) {
723
      /* don't copy more than one packet! */
724
      LWIP_ERROR("pbuf_copy() does not allow packet queues!\n",
725
                  (p_to->next == NULL), return ERR_VAL;);
726
    }
727
  } while (p_from);
728
  LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE | 1, ("pbuf_copy: end of chain reached.\n"));
729
  return ERR_OK;
730
}
731
 
732
/**
733
 * Copy (part of) the contents of a packet buffer
734
 * to an application supplied buffer.
735
 *
736
 * @param buf the pbuf from which to copy data
737
 * @param dataptr the application supplied buffer
738
 * @param len length of data to copy (dataptr must be big enough)
739
 * @param offset offset into the packet buffer from where to begin copying len bytes
740
 */
741
u16_t
742
pbuf_copy_partial(struct pbuf *buf, void *dataptr, u16_t len, u16_t offset)
743
{
744
  struct pbuf *p;
745
  u16_t left;
746
  u16_t buf_copy_len;
747
  u16_t copied_total = 0;
748
 
749
  LWIP_ERROR("netbuf_copy_partial: invalid buf", (buf != NULL), return 0;);
750
  LWIP_ERROR("netbuf_copy_partial: invalid dataptr", (dataptr != NULL), return 0;);
751
 
752
  left = 0;
753
 
754
  if((buf == NULL) || (dataptr == NULL)) {
755
    return 0;
756
  }
757
 
758
  /* Note some systems use byte copy if dataptr or one of the pbuf payload pointers are unaligned. */
759
  for(p = buf; len != 0 && p != NULL; p = p->next) {
760
    if ((offset != 0) && (offset >= p->len)) {
761
      /* don't copy from this buffer -> on to the next */
762
      offset -= p->len;
763
    } else {
764
      /* copy from this buffer. maybe only partially. */
765
      buf_copy_len = p->len - offset;
766
      if (buf_copy_len > len)
767
          buf_copy_len = len;
768
      /* copy the necessary parts of the buffer */
769
      MEMCPY(&((char*)dataptr)[left], &((char*)p->payload)[offset], buf_copy_len);
770
      copied_total += buf_copy_len;
771
      left += buf_copy_len;
772
      len -= buf_copy_len;
773
      offset = 0;
774
    }
775
  }
776
  return copied_total;
777
}

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