pbuf.c

00001 /**
00002  * @file
00003  * Packet buffer management
00004  *
00005  * Packets are built from the pbuf data structure. It supports dynamic
00006  * memory allocation for packet contents or can reference externally
00007  * managed packet contents both in RAM and ROM. Quick allocation for
00008  * incoming packets is provided through pools with fixed sized pbufs.
00009  *
00010  * A packet may span over multiple pbufs, chained as a singly linked
00011  * list. This is called a "pbuf chain".
00012  *
00013  * Multiple packets may be queued, also using this singly linked list.
00014  * This is called a "packet queue".
00015  * 
00016  * So, a packet queue consists of one or more pbuf chains, each of
00017  * which consist of one or more pbufs. CURRENTLY, PACKET QUEUES ARE
00018  * NOT SUPPORTED!!! Use helper structs to queue multiple packets.
00019  * 
00020  * The differences between a pbuf chain and a packet queue are very
00021  * precise but subtle. 
00022  *
00023  * The last pbuf of a packet has a ->tot_len field that equals the
00024  * ->len field. It can be found by traversing the list. If the last
00025  * pbuf of a packet has a ->next field other than NULL, more packets
00026  * are on the queue.
00027  *
00028  * Therefore, looping through a pbuf of a single packet, has an
00029  * loop end condition (tot_len == p->len), NOT (next == NULL).
00030  */
00031 
00032 /*
00033  * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
00034  * All rights reserved.
00035  *
00036  * Redistribution and use in source and binary forms, with or without modification,
00037  * are permitted provided that the following conditions are met:
00038  *
00039  * 1. Redistributions of source code must retain the above copyright notice,
00040  *    this list of conditions and the following disclaimer.
00041  * 2. Redistributions in binary form must reproduce the above copyright notice,
00042  *    this list of conditions and the following disclaimer in the documentation
00043  *    and/or other materials provided with the distribution.
00044  * 3. The name of the author may not be used to endorse or promote products
00045  *    derived from this software without specific prior written permission.
00046  *
00047  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
00048  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
00049  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
00050  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
00051  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
00052  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
00053  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
00054  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
00055  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
00056  * OF SUCH DAMAGE.
00057  *
00058  * This file is part of the lwIP TCP/IP stack.
00059  *
00060  * Author: Adam Dunkels <adam@sics.se>
00061  *
00062  */
00063 
00064 #include "lwip/opt.h"
00065 
00066 #include "lwip/stats.h"
00067 #include "lwip/def.h"
00068 #include "lwip/mem.h"
00069 #include "lwip/memp.h"
00070 #include "lwip/pbuf.h"
00071 #include "lwip/sys.h"
00072 #include "arch/perf.h"
00073 #if TCP_QUEUE_OOSEQ
00074 #include "lwip/tcp_impl.h"
00075 #endif
00076 #if LWIP_CHECKSUM_ON_COPY
00077 #include "lwip/inet_chksum.h"
00078 #endif
00079 
00080 #include <string.h>
00081 
00082 #define SIZEOF_STRUCT_PBUF        LWIP_MEM_ALIGN_SIZE(sizeof(struct pbuf))
00083 /* Since the pool is created in memp, PBUF_POOL_BUFSIZE will be automatically
00084    aligned there. Therefore, PBUF_POOL_BUFSIZE_ALIGNED can be used here. */
00085 #define PBUF_POOL_BUFSIZE_ALIGNED LWIP_MEM_ALIGN_SIZE(PBUF_POOL_BUFSIZE)
00086 
00087 #if !LWIP_TCP || !TCP_QUEUE_OOSEQ || NO_SYS
00088 #define PBUF_POOL_IS_EMPTY()
00089 #else /* !LWIP_TCP || !TCP_QUEUE_OOSEQ || NO_SYS */
00090 /** Define this to 0 to prevent freeing ooseq pbufs when the PBUF_POOL is empty */
00091 #ifndef PBUF_POOL_FREE_OOSEQ
00092 #define PBUF_POOL_FREE_OOSEQ 1
00093 #endif /* PBUF_POOL_FREE_OOSEQ */
00094 
00095 #if PBUF_POOL_FREE_OOSEQ
00096 #include "lwip/tcpip.h"
00097 #define PBUF_POOL_IS_EMPTY() pbuf_pool_is_empty()
00098 static u8_t pbuf_free_ooseq_queued;
00099 /**
00100  * Attempt to reclaim some memory from queued out-of-sequence TCP segments
00101  * if we run out of pool pbufs. It's better to give priority to new packets
00102  * if we're running out.
00103  *
00104  * This must be done in the correct thread context therefore this function
00105  * can only be used with NO_SYS=0 and through tcpip_callback.
00106  */
00107 static void
00108 pbuf_free_ooseq(void* arg)
00109 {
00110   struct tcp_pcb* pcb;
00111   SYS_ARCH_DECL_PROTECT(old_level);
00112   LWIP_UNUSED_ARG(arg);
00113 
00114   SYS_ARCH_PROTECT(old_level);
00115   pbuf_free_ooseq_queued = 0;
00116   SYS_ARCH_UNPROTECT(old_level);
00117 
00118   for (pcb = tcp_active_pcbs; NULL != pcb; pcb = pcb->next) {
00119     if (NULL != pcb->ooseq) {
00120       /** Free the ooseq pbufs of one PCB only */
00121       LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_free_ooseq: freeing out-of-sequence pbufs\n"));
00122       tcp_segs_free(pcb->ooseq);
00123       pcb->ooseq = NULL;
00124       return;
00125     }
00126   }
00127 }
00128 
00129 /** Queue a call to pbuf_free_ooseq if not already queued. */
00130 static void
00131 pbuf_pool_is_empty(void)
00132 {
00133   u8_t queued;
00134   SYS_ARCH_DECL_PROTECT(old_level);
00135 
00136   SYS_ARCH_PROTECT(old_level);
00137   queued = pbuf_free_ooseq_queued;
00138   pbuf_free_ooseq_queued = 1;
00139   SYS_ARCH_UNPROTECT(old_level);
00140 
00141   if(!queued) {
00142     /* queue a call to pbuf_free_ooseq if not already queued */
00143     if(tcpip_callback_with_block(pbuf_free_ooseq, NULL, 0) != ERR_OK) {
00144       SYS_ARCH_PROTECT(old_level);
00145       pbuf_free_ooseq_queued = 0;
00146       SYS_ARCH_UNPROTECT(old_level);
00147     }
00148   }
00149 }
00150 #endif /* PBUF_POOL_FREE_OOSEQ */
00151 #endif /* !LWIP_TCP || !TCP_QUEUE_OOSEQ || NO_SYS */
00152 
00153 /**
00154  * Allocates a pbuf of the given type (possibly a chain for PBUF_POOL type).
00155  *
00156  * The actual memory allocated for the pbuf is determined by the
00157  * layer at which the pbuf is allocated and the requested size
00158  * (from the size parameter).
00159  *
00160  * @param layer flag to define header size
00161  * @param length size of the pbuf's payload
00162  * @param type this parameter decides how and where the pbuf
00163  * should be allocated as follows:
00164  *
00165  * - PBUF_RAM: buffer memory for pbuf is allocated as one large
00166  *             chunk. This includes protocol headers as well.
00167  * - PBUF_ROM: no buffer memory is allocated for the pbuf, even for
00168  *             protocol headers. Additional headers must be prepended
00169  *             by allocating another pbuf and chain in to the front of
00170  *             the ROM pbuf. It is assumed that the memory used is really
00171  *             similar to ROM in that it is immutable and will not be
00172  *             changed. Memory which is dynamic should generally not
00173  *             be attached to PBUF_ROM pbufs. Use PBUF_REF instead.
00174  * - PBUF_REF: no buffer memory is allocated for the pbuf, even for
00175  *             protocol headers. It is assumed that the pbuf is only
00176  *             being used in a single thread. If the pbuf gets queued,
00177  *             then pbuf_take should be called to copy the buffer.
00178  * - PBUF_POOL: the pbuf is allocated as a pbuf chain, with pbufs from
00179  *              the pbuf pool that is allocated during pbuf_init().
00180  *
00181  * @return the allocated pbuf. If multiple pbufs where allocated, this
00182  * is the first pbuf of a pbuf chain.
00183  */
00184 struct pbuf *
00185 pbuf_alloc(pbuf_layer layer, u16_t length, pbuf_type type)
00186 {
00187   struct pbuf *p, *q, *r;
00188   u16_t offset;
00189   s32_t rem_len; /* remaining length */
00190   LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_alloc(length=%"U16_F")\n", length));
00191 
00192   /* determine header offset */
00193   offset = 0;
00194   switch (layer) {
00195   case PBUF_TRANSPORT:
00196     /* add room for transport (often TCP) layer header */
00197     offset += PBUF_TRANSPORT_HLEN;
00198     /* FALLTHROUGH */
00199   case PBUF_IP:
00200     /* add room for IP layer header */
00201     offset += PBUF_IP_HLEN;
00202     /* FALLTHROUGH */
00203   case PBUF_LINK:
00204     /* add room for link layer header */
00205     offset += PBUF_LINK_HLEN;
00206     break;
00207   case PBUF_RAW:
00208     break;
00209   default:
00210     LWIP_ASSERT("pbuf_alloc: bad pbuf layer", 0);
00211     return NULL;
00212   }
00213 
00214   switch (type) {
00215   case PBUF_POOL:
00216     /* allocate head of pbuf chain into p */
00217     p = (struct pbuf *)memp_malloc(MEMP_PBUF_POOL);
00218     LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_alloc: allocated pbuf %p\n", (void *)p));
00219     if (p == NULL) {
00220       PBUF_POOL_IS_EMPTY();
00221       return NULL;
00222     }
00223     p->type = type;
00224     p->next = NULL;
00225 
00226     /* make the payload pointer point 'offset' bytes into pbuf data memory */
00227     p->payload = LWIP_MEM_ALIGN((void *)((u8_t *)p + (SIZEOF_STRUCT_PBUF + offset)));
00228     LWIP_ASSERT("pbuf_alloc: pbuf p->payload properly aligned",
00229             ((mem_ptr_t)p->payload % MEM_ALIGNMENT) == 0);
00230     /* the total length of the pbuf chain is the requested size */
00231     p->tot_len = length;
00232     /* set the length of the first pbuf in the chain */
00233     p->len = LWIP_MIN(length, PBUF_POOL_BUFSIZE_ALIGNED - LWIP_MEM_ALIGN_SIZE(offset));
00234     LWIP_ASSERT("check p->payload + p->len does not overflow pbuf",
00235                 ((u8_t*)p->payload + p->len <=
00236                  (u8_t*)p + SIZEOF_STRUCT_PBUF + PBUF_POOL_BUFSIZE_ALIGNED));
00237     LWIP_ASSERT("PBUF_POOL_BUFSIZE must be bigger than MEM_ALIGNMENT",
00238       (PBUF_POOL_BUFSIZE_ALIGNED - LWIP_MEM_ALIGN_SIZE(offset)) > 0 );
00239     /* set reference count (needed here in case we fail) */
00240     p->ref = 1;
00241 
00242     /* now allocate the tail of the pbuf chain */
00243 
00244     /* remember first pbuf for linkage in next iteration */
00245     r = p;
00246     /* remaining length to be allocated */
00247     rem_len = length - p->len;
00248     /* any remaining pbufs to be allocated? */
00249     while (rem_len > 0) {
00250       q = (struct pbuf *)memp_malloc(MEMP_PBUF_POOL);
00251       if (q == NULL) {
00252         PBUF_POOL_IS_EMPTY();
00253         /* free chain so far allocated */
00254         pbuf_free(p);
00255         /* bail out unsuccesfully */
00256         return NULL;
00257       }
00258       q->type = type;
00259       q->flags = 0;
00260       q->next = NULL;
00261       /* make previous pbuf point to this pbuf */
00262       r->next = q;
00263       /* set total length of this pbuf and next in chain */
00264       LWIP_ASSERT("rem_len < max_u16_t", rem_len < 0xffff);
00265       q->tot_len = (u16_t)rem_len;
00266       /* this pbuf length is pool size, unless smaller sized tail */
00267       q->len = LWIP_MIN((u16_t)rem_len, PBUF_POOL_BUFSIZE_ALIGNED);
00268       q->payload = (void *)((u8_t *)q + SIZEOF_STRUCT_PBUF);
00269       LWIP_ASSERT("pbuf_alloc: pbuf q->payload properly aligned",
00270               ((mem_ptr_t)q->payload % MEM_ALIGNMENT) == 0);
00271       LWIP_ASSERT("check p->payload + p->len does not overflow pbuf",
00272                   ((u8_t*)p->payload + p->len <=
00273                    (u8_t*)p + SIZEOF_STRUCT_PBUF + PBUF_POOL_BUFSIZE_ALIGNED));
00274       q->ref = 1;
00275       /* calculate remaining length to be allocated */
00276       rem_len -= q->len;
00277       /* remember this pbuf for linkage in next iteration */
00278       r = q;
00279     }
00280     /* end of chain */
00281     /*r->next = NULL;*/
00282 
00283     break;
00284   case PBUF_RAM:
00285     /* If pbuf is to be allocated in RAM, allocate memory for it. */
00286     p = (struct pbuf*)mem_malloc(LWIP_MEM_ALIGN_SIZE(SIZEOF_STRUCT_PBUF + offset) + LWIP_MEM_ALIGN_SIZE(length));
00287     if (p == NULL) {
00288       return NULL;
00289     }
00290     /* Set up internal structure of the pbuf. */
00291     p->payload = LWIP_MEM_ALIGN((void *)((u8_t *)p + SIZEOF_STRUCT_PBUF + offset));
00292     p->len = p->tot_len = length;
00293     p->next = NULL;
00294     p->type = type;
00295 
00296     LWIP_ASSERT("pbuf_alloc: pbuf->payload properly aligned",
00297            ((mem_ptr_t)p->payload % MEM_ALIGNMENT) == 0);
00298     break;
00299   /* pbuf references existing (non-volatile static constant) ROM payload? */
00300   case PBUF_ROM:
00301   /* pbuf references existing (externally allocated) RAM payload? */
00302   case PBUF_REF:
00303     /* only allocate memory for the pbuf structure */
00304     p = (struct pbuf *)memp_malloc(MEMP_PBUF);
00305     if (p == NULL) {
00306       LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
00307                   ("pbuf_alloc: Could not allocate MEMP_PBUF for PBUF_%s.\n",
00308                   (type == PBUF_ROM) ? "ROM" : "REF"));
00309       return NULL;
00310     }
00311     /* caller must set this field properly, afterwards */
00312     p->payload = NULL;
00313     p->len = p->tot_len = length;
00314     p->next = NULL;
00315     p->type = type;
00316     break;
00317   default:
00318     LWIP_ASSERT("pbuf_alloc: erroneous type", 0);
00319     return NULL;
00320   }
00321   /* set reference count */
00322   p->ref = 1;
00323   /* set flags */
00324   p->flags = 0;
00325   LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_alloc(length=%"U16_F") == %p\n", length, (void *)p));
00326   return p;
00327 }
00328 
00329 #if LWIP_SUPPORT_CUSTOM_PBUF
00330 /** Initialize a custom pbuf (already allocated).
00331  *
00332  * @param layer flag to define header size
00333  * @param length size of the pbuf's payload
00334  * @param type type of the pbuf (only used to treat the pbuf accordingly, as
00335  *        this function allocates no memory)
00336  * @param p pointer to the custom pbuf to initialize (already allocated)
00337  * @param payload_mem pointer to the buffer that is used for payload and headers,
00338  *        must be at least big enough to hold 'length' plus the header size,
00339  *        may be NULL if set later
00340  * @param payload_mem_len the size of the 'payload_mem' buffer, must be at least
00341  *        big enough to hold 'length' plus the header size
00342  */
00343 struct pbuf*
00344 pbuf_alloced_custom(pbuf_layer l, u16_t length, pbuf_type type, struct pbuf_custom *p,
00345                     void *payload_mem, u16_t payload_mem_len)
00346 {
00347   u16_t offset;
00348   LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_alloced_custom(length=%"U16_F")\n", length));
00349 
00350   /* determine header offset */
00351   offset = 0;
00352   switch (l) {
00353   case PBUF_TRANSPORT:
00354     /* add room for transport (often TCP) layer header */
00355     offset += PBUF_TRANSPORT_HLEN;
00356     /* FALLTHROUGH */
00357   case PBUF_IP:
00358     /* add room for IP layer header */
00359     offset += PBUF_IP_HLEN;
00360     /* FALLTHROUGH */
00361   case PBUF_LINK:
00362     /* add room for link layer header */
00363     offset += PBUF_LINK_HLEN;
00364     break;
00365   case PBUF_RAW:
00366     break;
00367   default:
00368     LWIP_ASSERT("pbuf_alloced_custom: bad pbuf layer", 0);
00369     return NULL;
00370   }
00371 
00372   if (LWIP_MEM_ALIGN_SIZE(offset) + length < payload_mem_len) {
00373     LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_LEVEL_WARNING, ("pbuf_alloced_custom(length=%"U16_F") buffer too short\n", length));
00374     return NULL;
00375   }
00376 
00377   p->pbuf.next = NULL;
00378   if (payload_mem != NULL) {
00379 //    p->pbuf.payload = LWIP_MEM_ALIGN((void *)((u8_t *)payload_mem + offset));
00380     p->pbuf.payload = (void *)((u8_t *)payload_mem + offset);
00381   } else {
00382     p->pbuf.payload = NULL;
00383   }
00384   p->pbuf.flags = PBUF_FLAG_IS_CUSTOM;
00385   p->pbuf.len = p->pbuf.tot_len = length;
00386   p->pbuf.type = type;
00387   p->pbuf.ref = 1;
00388   return &p->pbuf;
00389 }
00390 #endif /* LWIP_SUPPORT_CUSTOM_PBUF */
00391 
00392 /**
00393  * Shrink a pbuf chain to a desired length.
00394  *
00395  * @param p pbuf to shrink.
00396  * @param new_len desired new length of pbuf chain
00397  *
00398  * Depending on the desired length, the first few pbufs in a chain might
00399  * be skipped and left unchanged. The new last pbuf in the chain will be
00400  * resized, and any remaining pbufs will be freed.
00401  *
00402  * @note If the pbuf is ROM/REF, only the ->tot_len and ->len fields are adjusted.
00403  * @note May not be called on a packet queue.
00404  *
00405  * @note Despite its name, pbuf_realloc cannot grow the size of a pbuf (chain).
00406  */
00407 void
00408 pbuf_realloc(struct pbuf *p, u16_t new_len)
00409 {
00410   struct pbuf *q;
00411   u16_t rem_len; /* remaining length */
00412   s32_t grow;
00413 
00414   LWIP_ASSERT("pbuf_realloc: p != NULL", p != NULL);
00415   LWIP_ASSERT("pbuf_realloc: sane p->type", p->type == PBUF_POOL ||
00416               p->type == PBUF_ROM ||
00417               p->type == PBUF_RAM ||
00418               p->type == PBUF_REF);
00419 
00420   /* desired length larger than current length? */
00421   if (new_len >= p->tot_len) {
00422     /* enlarging not yet supported */
00423     return;
00424   }
00425 
00426   /* the pbuf chain grows by (new_len - p->tot_len) bytes
00427    * (which may be negative in case of shrinking) */
00428   grow = new_len - p->tot_len;
00429 
00430   /* first, step over any pbufs that should remain in the chain */
00431   rem_len = new_len;
00432   q = p;
00433   /* should this pbuf be kept? */
00434   while (rem_len > q->len) {
00435     /* decrease remaining length by pbuf length */
00436     rem_len -= q->len;
00437     /* decrease total length indicator */
00438     LWIP_ASSERT("grow < max_u16_t", grow < 0xffff);
00439     q->tot_len += (u16_t)grow;
00440     /* proceed to next pbuf in chain */
00441     q = q->next;
00442     LWIP_ASSERT("pbuf_realloc: q != NULL", q != NULL);
00443   }
00444   /* we have now reached the new last pbuf (in q) */
00445   /* rem_len == desired length for pbuf q */
00446 
00447   /* shrink allocated memory for PBUF_RAM */
00448   /* (other types merely adjust their length fields */
00449   if ((q->type == PBUF_RAM) && (rem_len != q->len)) {
00450     /* reallocate and adjust the length of the pbuf that will be split */
00451     q = (struct pbuf *)mem_trim(q, (u16_t)((u8_t *)q->payload - (u8_t *)q) + rem_len);
00452     LWIP_ASSERT("mem_trim returned q == NULL", q != NULL);
00453   }
00454   /* adjust length fields for new last pbuf */
00455   q->len = rem_len;
00456   q->tot_len = q->len;
00457 
00458   /* any remaining pbufs in chain? */
00459   if (q->next != NULL) {
00460     /* free remaining pbufs in chain */
00461     pbuf_free(q->next);
00462   }
00463   /* q is last packet in chain */
00464   q->next = NULL;
00465 
00466 }
00467 
00468 /**
00469  * Adjusts the payload pointer to hide or reveal headers in the payload.
00470  *
00471  * Adjusts the ->payload pointer so that space for a header
00472  * (dis)appears in the pbuf payload.
00473  *
00474  * The ->payload, ->tot_len and ->len fields are adjusted.
00475  *
00476  * @param p pbuf to change the header size.
00477  * @param header_size_increment Number of bytes to increment header size which
00478  * increases the size of the pbuf. New space is on the front.
00479  * (Using a negative value decreases the header size.)
00480  * If hdr_size_inc is 0, this function does nothing and returns succesful.
00481  *
00482  * PBUF_ROM and PBUF_REF type buffers cannot have their sizes increased, so
00483  * the call will fail. A check is made that the increase in header size does
00484  * not move the payload pointer in front of the start of the buffer.
00485  * @return non-zero on failure, zero on success.
00486  *
00487  */
00488 u8_t
00489 pbuf_header(struct pbuf *p, s16_t header_size_increment)
00490 {
00491   u16_t type;
00492   void *payload;
00493   u16_t increment_magnitude;
00494 
00495   LWIP_ASSERT("p != NULL", p != NULL);
00496   if ((header_size_increment == 0) || (p == NULL)) {
00497     return 0;
00498   }
00499  
00500   if (header_size_increment < 0){
00501     increment_magnitude = -header_size_increment;
00502     /* Check that we aren't going to move off the end of the pbuf */
00503     LWIP_ERROR("increment_magnitude <= p->len", (increment_magnitude <= p->len), return 1;);
00504   } else {
00505     increment_magnitude = header_size_increment;
00506 #if 0
00507     /* Can't assert these as some callers speculatively call
00508          pbuf_header() to see if it's OK.  Will return 1 below instead. */
00509     /* Check that we've got the correct type of pbuf to work with */
00510     LWIP_ASSERT("p->type == PBUF_RAM || p->type == PBUF_POOL", 
00511                 p->type == PBUF_RAM || p->type == PBUF_POOL);
00512     /* Check that we aren't going to move off the beginning of the pbuf */
00513     LWIP_ASSERT("p->payload - increment_magnitude >= p + SIZEOF_STRUCT_PBUF",
00514                 (u8_t *)p->payload - increment_magnitude >= (u8_t *)p + SIZEOF_STRUCT_PBUF);
00515 #endif
00516   }
00517 
00518   type = p->type;
00519   /* remember current payload pointer */
00520   payload = p->payload;
00521 
00522   /* pbuf types containing payloads? */
00523   if (type == PBUF_RAM || type == PBUF_POOL) {
00524     /* set new payload pointer */
00525     p->payload = (u8_t *)p->payload - header_size_increment;
00526     /* boundary check fails? */
00527     if ((u8_t *)p->payload < (u8_t *)p + SIZEOF_STRUCT_PBUF) {
00528       LWIP_DEBUGF( PBUF_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
00529         ("pbuf_header: failed as %p < %p (not enough space for new header size)\n",
00530         (void *)p->payload, (void *)(p + 1)));
00531       /* restore old payload pointer */
00532       p->payload = payload;
00533       /* bail out unsuccesfully */
00534       return 1;
00535     }
00536   /* pbuf types refering to external payloads? */
00537   } else if (type == PBUF_REF || type == PBUF_ROM) {
00538     /* hide a header in the payload? */
00539     if ((header_size_increment < 0) && (increment_magnitude <= p->len)) {
00540       /* increase payload pointer */
00541       p->payload = (u8_t *)p->payload - header_size_increment;
00542     } else {
00543       /* cannot expand payload to front (yet!)
00544        * bail out unsuccesfully */
00545       return 1;
00546     }
00547   } else {
00548     /* Unknown type */
00549     LWIP_ASSERT("bad pbuf type", 0);
00550     return 1;
00551   }
00552   /* modify pbuf length fields */
00553   p->len += header_size_increment;
00554   p->tot_len += header_size_increment;
00555 
00556   LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_header: old %p new %p (%"S16_F")\n",
00557     (void *)payload, (void *)p->payload, header_size_increment));
00558 
00559   return 0;
00560 }
00561 
00562 /**
00563  * Dereference a pbuf chain or queue and deallocate any no-longer-used
00564  * pbufs at the head of this chain or queue.
00565  *
00566  * Decrements the pbuf reference count. If it reaches zero, the pbuf is
00567  * deallocated.
00568  *
00569  * For a pbuf chain, this is repeated for each pbuf in the chain,
00570  * up to the first pbuf which has a non-zero reference count after
00571  * decrementing. So, when all reference counts are one, the whole
00572  * chain is free'd.
00573  *
00574  * @param p The pbuf (chain) to be dereferenced.
00575  *
00576  * @return the number of pbufs that were de-allocated
00577  * from the head of the chain.
00578  *
00579  * @note MUST NOT be called on a packet queue (Not verified to work yet).
00580  * @note the reference counter of a pbuf equals the number of pointers
00581  * that refer to the pbuf (or into the pbuf).
00582  *
00583  * @internal examples:
00584  *
00585  * Assuming existing chains a->b->c with the following reference
00586  * counts, calling pbuf_free(a) results in:
00587  * 
00588  * 1->2->3 becomes ...1->3
00589  * 3->3->3 becomes 2->3->3
00590  * 1->1->2 becomes ......1
00591  * 2->1->1 becomes 1->1->1
00592  * 1->1->1 becomes .......
00593  *
00594  */
00595 u8_t
00596 pbuf_free(struct pbuf *p)
00597 {
00598   u16_t type;
00599   struct pbuf *q;
00600   u8_t count;
00601 
00602   if (p == NULL) {
00603     LWIP_ASSERT("p != NULL", p != NULL);
00604     /* if assertions are disabled, proceed with debug output */
00605     LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
00606       ("pbuf_free(p == NULL) was called.\n"));
00607     return 0;
00608   }
00609   LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_free(%p)\n", (void *)p));
00610 
00611   PERF_START;
00612 
00613   LWIP_ASSERT("pbuf_free: sane type",
00614     p->type == PBUF_RAM || p->type == PBUF_ROM ||
00615     p->type == PBUF_REF || p->type == PBUF_POOL);
00616 
00617   count = 0;
00618   /* de-allocate all consecutive pbufs from the head of the chain that
00619    * obtain a zero reference count after decrementing*/
00620   while (p != NULL) {
00621     u16_t ref;
00622     SYS_ARCH_DECL_PROTECT(old_level);
00623     /* Since decrementing ref cannot be guaranteed to be a single machine operation
00624      * we must protect it. We put the new ref into a local variable to prevent
00625      * further protection. */
00626     SYS_ARCH_PROTECT(old_level);
00627     /* all pbufs in a chain are referenced at least once */
00628     LWIP_ASSERT("pbuf_free: p->ref > 0", p->ref > 0);
00629     /* decrease reference count (number of pointers to pbuf) */
00630     ref = --(p->ref);
00631     SYS_ARCH_UNPROTECT(old_level);
00632     /* this pbuf is no longer referenced to? */
00633     if (ref == 0) {
00634       /* remember next pbuf in chain for next iteration */
00635       q = p->next;
00636       LWIP_DEBUGF( PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_free: deallocating %p\n", (void *)p));
00637       type = p->type;
00638 #if LWIP_SUPPORT_CUSTOM_PBUF
00639       /* is this a custom pbuf? */
00640       if ((p->flags & PBUF_FLAG_IS_CUSTOM) != 0) {
00641         struct pbuf_custom *pc = (struct pbuf_custom*)p;
00642         LWIP_ASSERT("pc->custom_free_function != NULL", pc->custom_free_function != NULL);
00643         pc->custom_free_function(p);
00644       } else
00645 #endif /* LWIP_SUPPORT_CUSTOM_PBUF */
00646       {
00647         /* is this a pbuf from the pool? */
00648         if (type == PBUF_POOL) {
00649           memp_free(MEMP_PBUF_POOL, p);
00650         /* is this a ROM or RAM referencing pbuf? */
00651         } else if (type == PBUF_ROM || type == PBUF_REF) {
00652           memp_free(MEMP_PBUF, p);
00653         /* type == PBUF_RAM */
00654         } else {
00655           mem_free(p);
00656         }
00657       }
00658       count++;
00659       /* proceed to next pbuf */
00660       p = q;
00661     /* p->ref > 0, this pbuf is still referenced to */
00662     /* (and so the remaining pbufs in chain as well) */
00663     } else {
00664       LWIP_DEBUGF( PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_free: %p has ref %"U16_F", ending here.\n", (void *)p, ref));
00665       /* stop walking through the chain */
00666       p = NULL;
00667     }
00668   }
00669   PERF_STOP("pbuf_free");
00670   /* return number of de-allocated pbufs */
00671   return count;
00672 }
00673 
00674 /**
00675  * Count number of pbufs in a chain
00676  *
00677  * @param p first pbuf of chain
00678  * @return the number of pbufs in a chain
00679  */
00680 
00681 u8_t
00682 pbuf_clen(struct pbuf *p)
00683 {
00684   u8_t len;
00685 
00686   len = 0;
00687   while (p != NULL) {
00688     ++len;
00689     p = p->next;
00690   }
00691   return len;
00692 }
00693 
00694 /**
00695  * Increment the reference count of the pbuf.
00696  *
00697  * @param p pbuf to increase reference counter of
00698  *
00699  */
00700 void
00701 pbuf_ref(struct pbuf *p)
00702 {
00703   SYS_ARCH_DECL_PROTECT(old_level);
00704   /* pbuf given? */
00705   if (p != NULL) {
00706     SYS_ARCH_PROTECT(old_level);
00707     ++(p->ref);
00708     SYS_ARCH_UNPROTECT(old_level);
00709   }
00710 }
00711 
00712 /**
00713  * Concatenate two pbufs (each may be a pbuf chain) and take over
00714  * the caller's reference of the tail pbuf.
00715  * 
00716  * @note The caller MAY NOT reference the tail pbuf afterwards.
00717  * Use pbuf_chain() for that purpose.
00718  * 
00719  * @see pbuf_chain()
00720  */
00721 
00722 void
00723 pbuf_cat(struct pbuf *h, struct pbuf *t)
00724 {
00725   struct pbuf *p;
00726 
00727   LWIP_ERROR("(h != NULL) && (t != NULL) (programmer violates API)",
00728              ((h != NULL) && (t != NULL)), return;);
00729 
00730   /* proceed to last pbuf of chain */
00731   for (p = h; p->next != NULL; p = p->next) {
00732     /* add total length of second chain to all totals of first chain */
00733     p->tot_len += t->tot_len;
00734   }
00735   /* { p is last pbuf of first h chain, p->next == NULL } */
00736   LWIP_ASSERT("p->tot_len == p->len (of last pbuf in chain)", p->tot_len == p->len);
00737   LWIP_ASSERT("p->next == NULL", p->next == NULL);
00738   /* add total length of second chain to last pbuf total of first chain */
00739   p->tot_len += t->tot_len;
00740   /* chain last pbuf of head (p) with first of tail (t) */
00741   p->next = t;
00742   /* p->next now references t, but the caller will drop its reference to t,
00743    * so netto there is no change to the reference count of t.
00744    */
00745 }
00746 
00747 /**
00748  * Chain two pbufs (or pbuf chains) together.
00749  * 
00750  * The caller MUST call pbuf_free(t) once it has stopped
00751  * using it. Use pbuf_cat() instead if you no longer use t.
00752  * 
00753  * @param h head pbuf (chain)
00754  * @param t tail pbuf (chain)
00755  * @note The pbufs MUST belong to the same packet.
00756  * @note MAY NOT be called on a packet queue.
00757  *
00758  * The ->tot_len fields of all pbufs of the head chain are adjusted.
00759  * The ->next field of the last pbuf of the head chain is adjusted.
00760  * The ->ref field of the first pbuf of the tail chain is adjusted.
00761  *
00762  */
00763 void
00764 pbuf_chain(struct pbuf *h, struct pbuf *t)
00765 {
00766   pbuf_cat(h, t);
00767   /* t is now referenced by h */
00768   pbuf_ref(t);
00769   LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_chain: %p references %p\n", (void *)h, (void *)t));
00770 }
00771 
00772 /**
00773  * Dechains the first pbuf from its succeeding pbufs in the chain.
00774  *
00775  * Makes p->tot_len field equal to p->len.
00776  * @param p pbuf to dechain
00777  * @return remainder of the pbuf chain, or NULL if it was de-allocated.
00778  * @note May not be called on a packet queue.
00779  */
00780 struct pbuf *
00781 pbuf_dechain(struct pbuf *p)
00782 {
00783   struct pbuf *q;
00784   u8_t tail_gone = 1;
00785   /* tail */
00786   q = p->next;
00787   /* pbuf has successor in chain? */
00788   if (q != NULL) {
00789     /* assert tot_len invariant: (p->tot_len == p->len + (p->next? p->next->tot_len: 0) */
00790     LWIP_ASSERT("p->tot_len == p->len + q->tot_len", q->tot_len == p->tot_len - p->len);
00791     /* enforce invariant if assertion is disabled */
00792     q->tot_len = p->tot_len - p->len;
00793     /* decouple pbuf from remainder */
00794     p->next = NULL;
00795     /* total length of pbuf p is its own length only */
00796     p->tot_len = p->len;
00797     /* q is no longer referenced by p, free it */
00798     LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_dechain: unreferencing %p\n", (void *)q));
00799     tail_gone = pbuf_free(q);
00800     if (tail_gone > 0) {
00801       LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE,
00802                   ("pbuf_dechain: deallocated %p (as it is no longer referenced)\n", (void *)q));
00803     }
00804     /* return remaining tail or NULL if deallocated */
00805   }
00806   /* assert tot_len invariant: (p->tot_len == p->len + (p->next? p->next->tot_len: 0) */
00807   LWIP_ASSERT("p->tot_len == p->len", p->tot_len == p->len);
00808   return ((tail_gone > 0) ? NULL : q);
00809 }
00810 
00811 /**
00812  *
00813  * Create PBUF_RAM copies of pbufs.
00814  *
00815  * Used to queue packets on behalf of the lwIP stack, such as
00816  * ARP based queueing.
00817  *
00818  * @note You MUST explicitly use p = pbuf_take(p);
00819  *
00820  * @note Only one packet is copied, no packet queue!
00821  *
00822  * @param p_to pbuf destination of the copy
00823  * @param p_from pbuf source of the copy
00824  *
00825  * @return ERR_OK if pbuf was copied
00826  *         ERR_ARG if one of the pbufs is NULL or p_to is not big
00827  *                 enough to hold p_from
00828  */
00829 err_t
00830 pbuf_copy(struct pbuf *p_to, struct pbuf *p_from)
00831 {
00832   u16_t offset_to=0, offset_from=0, len;
00833 
00834   LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_copy(%p, %p)\n",
00835     (void*)p_to, (void*)p_from));
00836 
00837   /* is the target big enough to hold the source? */
00838   LWIP_ERROR("pbuf_copy: target not big enough to hold source", ((p_to != NULL) &&
00839              (p_from != NULL) && (p_to->tot_len >= p_from->tot_len)), return ERR_ARG;);
00840 
00841   /* iterate through pbuf chain */
00842   do
00843   {
00844     LWIP_ASSERT("p_to != NULL", p_to != NULL);
00845     /* copy one part of the original chain */
00846     if ((p_to->len - offset_to) >= (p_from->len - offset_from)) {
00847       /* complete current p_from fits into current p_to */
00848       len = p_from->len - offset_from;
00849     } else {
00850       /* current p_from does not fit into current p_to */
00851       len = p_to->len - offset_to;
00852     }
00853     MEMCPY((u8_t*)p_to->payload + offset_to, (u8_t*)p_from->payload + offset_from, len);
00854     offset_to += len;
00855     offset_from += len;
00856     LWIP_ASSERT("offset_to <= p_to->len", offset_to <= p_to->len);
00857     if (offset_to == p_to->len) {
00858       /* on to next p_to (if any) */
00859       offset_to = 0;
00860       p_to = p_to->next;
00861     }
00862     LWIP_ASSERT("offset_from <= p_from->len", offset_from <= p_from->len);
00863     if (offset_from >= p_from->len) {
00864       /* on to next p_from (if any) */
00865       offset_from = 0;
00866       p_from = p_from->next;
00867     }
00868 
00869     if((p_from != NULL) && (p_from->len == p_from->tot_len)) {
00870       /* don't copy more than one packet! */
00871       LWIP_ERROR("pbuf_copy() does not allow packet queues!\n",
00872                  (p_from->next == NULL), return ERR_VAL;);
00873     }
00874     if((p_to != NULL) && (p_to->len == p_to->tot_len)) {
00875       /* don't copy more than one packet! */
00876       LWIP_ERROR("pbuf_copy() does not allow packet queues!\n",
00877                   (p_to->next == NULL), return ERR_VAL;);
00878     }
00879   } while (p_from);
00880   LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_copy: end of chain reached.\n"));
00881   return ERR_OK;
00882 }
00883 
00884 /**
00885  * Copy (part of) the contents of a packet buffer
00886  * to an application supplied buffer.
00887  *
00888  * @param buf the pbuf from which to copy data
00889  * @param dataptr the application supplied buffer
00890  * @param len length of data to copy (dataptr must be big enough). No more 
00891  * than buf->tot_len will be copied, irrespective of len
00892  * @param offset offset into the packet buffer from where to begin copying len bytes
00893  * @return the number of bytes copied, or 0 on failure
00894  */
00895 u16_t
00896 pbuf_copy_partial(struct pbuf *buf, void *dataptr, u16_t len, u16_t offset)
00897 {
00898   struct pbuf *p;
00899   u16_t left;
00900   u16_t buf_copy_len;
00901   u16_t copied_total = 0;
00902 
00903   LWIP_ERROR("pbuf_copy_partial: invalid buf", (buf != NULL), return 0;);
00904   LWIP_ERROR("pbuf_copy_partial: invalid dataptr", (dataptr != NULL), return 0;);
00905 
00906   left = 0;
00907 
00908   if((buf == NULL) || (dataptr == NULL)) {
00909     return 0;
00910   }
00911 
00912   /* Note some systems use byte copy if dataptr or one of the pbuf payload pointers are unaligned. */
00913   for(p = buf; len != 0 && p != NULL; p = p->next) {
00914     if ((offset != 0) && (offset >= p->len)) {
00915       /* don't copy from this buffer -> on to the next */
00916       offset -= p->len;
00917     } else {
00918       /* copy from this buffer. maybe only partially. */
00919       buf_copy_len = p->len - offset;
00920       if (buf_copy_len > len)
00921           buf_copy_len = len;
00922       /* copy the necessary parts of the buffer */
00923       MEMCPY(&((char*)dataptr)[left], &((char*)p->payload)[offset], buf_copy_len);
00924       copied_total += buf_copy_len;
00925       left += buf_copy_len;
00926       len -= buf_copy_len;
00927       offset = 0;
00928     }
00929   }
00930   return copied_total;
00931 }
00932 
00933 /**
00934  * Copy application supplied data into a pbuf.
00935  * This function can only be used to copy the equivalent of buf->tot_len data.
00936  *
00937  * @param buf pbuf to fill with data
00938  * @param dataptr application supplied data buffer
00939  * @param len length of the application supplied data buffer
00940  *
00941  * @return ERR_OK if successful, ERR_MEM if the pbuf is not big enough
00942  */
00943 err_t
00944 pbuf_take(struct pbuf *buf, const void *dataptr, u16_t len)
00945 {
00946   struct pbuf *p;
00947   u16_t buf_copy_len;
00948   u16_t total_copy_len = len;
00949   u16_t copied_total = 0;
00950 
00951   LWIP_ERROR("pbuf_take: invalid buf", (buf != NULL), return 0;);
00952   LWIP_ERROR("pbuf_take: invalid dataptr", (dataptr != NULL), return 0;);
00953 
00954   if ((buf == NULL) || (dataptr == NULL) || (buf->tot_len < len)) {
00955     return ERR_ARG;
00956   }
00957 
00958   /* Note some systems use byte copy if dataptr or one of the pbuf payload pointers are unaligned. */
00959   for(p = buf; total_copy_len != 0; p = p->next) {
00960     LWIP_ASSERT("pbuf_take: invalid pbuf", p != NULL);
00961     buf_copy_len = total_copy_len;
00962     if (buf_copy_len > p->len) {
00963       /* this pbuf cannot hold all remaining data */
00964       buf_copy_len = p->len;
00965     }
00966     /* copy the necessary parts of the buffer */
00967     MEMCPY(p->payload, &((char*)dataptr)[copied_total], buf_copy_len);
00968     total_copy_len -= buf_copy_len;
00969     copied_total += buf_copy_len;
00970   }
00971   LWIP_ASSERT("did not copy all data", total_copy_len == 0 && copied_total == len);
00972   return ERR_OK;
00973 }
00974 
00975 /**
00976  * Creates a single pbuf out of a queue of pbufs.
00977  *
00978  * @remark: Either the source pbuf 'p' is freed by this function or the original
00979  *          pbuf 'p' is returned, therefore the caller has to check the result!
00980  *
00981  * @param p the source pbuf
00982  * @param layer pbuf_layer of the new pbuf
00983  *
00984  * @return a new, single pbuf (p->next is NULL)
00985  *         or the old pbuf if allocation fails
00986  */
00987 struct pbuf*
00988 pbuf_coalesce(struct pbuf *p, pbuf_layer layer)
00989 {
00990   struct pbuf *q;
00991   err_t err;
00992   if (p->next == NULL) {
00993     return p;
00994   }
00995   q = pbuf_alloc(layer, p->tot_len, PBUF_RAM);
00996   if (q == NULL) {
00997     /* @todo: what do we do now? */
00998     return p;
00999   }
01000   err = pbuf_copy(q, p);
01001   LWIP_ASSERT("pbuf_copy failed", err == ERR_OK);
01002   pbuf_free(p);
01003   return q;
01004 }
01005 
01006 #if LWIP_CHECKSUM_ON_COPY
01007 /**
01008  * Copies data into a single pbuf (*not* into a pbuf queue!) and updates
01009  * the checksum while copying
01010  *
01011  * @param p the pbuf to copy data into
01012  * @param start_offset offset of p->payload where to copy the data to
01013  * @param dataptr data to copy into the pbuf
01014  * @param len length of data to copy into the pbuf
01015  * @param chksum pointer to the checksum which is updated
01016  * @return ERR_OK if successful, another error if the data does not fit
01017  *         within the (first) pbuf (no pbuf queues!)
01018  */
01019 err_t
01020 pbuf_fill_chksum(struct pbuf *p, u16_t start_offset, const void *dataptr,
01021                  u16_t len, u16_t *chksum)
01022 {
01023   u32_t acc;
01024   u16_t copy_chksum;
01025   char *dst_ptr;
01026   LWIP_ASSERT("p != NULL", p != NULL);
01027   LWIP_ASSERT("dataptr != NULL", dataptr != NULL);
01028   LWIP_ASSERT("chksum != NULL", chksum != NULL);
01029   LWIP_ASSERT("len != 0", len != 0);
01030 
01031   if ((start_offset >= p->len) || (start_offset + len > p->len)) {
01032     return ERR_ARG;
01033   }
01034 
01035   dst_ptr = ((char*)p->payload) + start_offset;
01036   copy_chksum = LWIP_CHKSUM_COPY(dst_ptr, dataptr, len);
01037   if ((start_offset & 1) != 0) {
01038     copy_chksum = SWAP_BYTES_IN_WORD(copy_chksum);
01039   }
01040   acc = *chksum;
01041   acc += copy_chksum;
01042   *chksum = FOLD_U32T(acc);
01043   return ERR_OK;
01044 }
01045 #endif /* LWIP_CHECKSUM_ON_COPY */
01046 
01047  /** Get one byte from the specified position in a pbuf
01048  * WARNING: returns zero for offset >= p->tot_len
01049  *
01050  * @param p pbuf to parse
01051  * @param offset offset into p of the byte to return
01052  * @return byte at an offset into p OR ZERO IF 'offset' >= p->tot_len
01053  */
01054 u8_t
01055 pbuf_get_at(struct pbuf* p, u16_t offset)
01056 {
01057   u16_t copy_from = offset;
01058   struct pbuf* q = p;
01059 
01060   /* get the correct pbuf */
01061   while ((q != NULL) && (q->len <= copy_from)) {
01062     copy_from -= q->len;
01063     q = q->next;
01064   }
01065   /* return requested data if pbuf is OK */
01066   if ((q != NULL) && (q->len > copy_from)) {
01067     return ((u8_t*)q->payload)[copy_from];
01068   }
01069   return 0;
01070 }
01071 
01072 /** Compare pbuf contents at specified offset with memory s2, both of length n
01073  *
01074  * @param p pbuf to compare
01075  * @param offset offset into p at wich to start comparing
01076  * @param s2 buffer to compare
01077  * @param n length of buffer to compare
01078  * @return zero if equal, nonzero otherwise
01079  *         (0xffff if p is too short, diffoffset+1 otherwise)
01080  */
01081 u16_t
01082 pbuf_memcmp(struct pbuf* p, u16_t offset, const void* s2, u16_t n)
01083 {
01084   u16_t start = offset;
01085   struct pbuf* q = p;
01086 
01087   /* get the correct pbuf */
01088   while ((q != NULL) && (q->len <= start)) {
01089     start -= q->len;
01090     q = q->next;
01091   }
01092   /* return requested data if pbuf is OK */
01093   if ((q != NULL) && (q->len > start)) {
01094     u16_t i;
01095     for(i = 0; i < n; i++) {
01096       u8_t a = pbuf_get_at(q, start + i);
01097       u8_t b = ((u8_t*)s2)[i];
01098       if (a != b) {
01099         return i+1;
01100       }
01101     }
01102     return 0;
01103   }
01104   return 0xffff;
01105 }
01106 
01107 /** Find occurrence of mem (with length mem_len) in pbuf p, starting at offset
01108  * start_offset.
01109  *
01110  * @param p pbuf to search, maximum length is 0xFFFE since 0xFFFF is used as
01111  *        return value 'not found'
01112  * @param mem search for the contents of this buffer
01113  * @param mem_len length of 'mem'
01114  * @param start_offset offset into p at which to start searching
01115  * @return 0xFFFF if substr was not found in p or the index where it was found
01116  */
01117 u16_t
01118 pbuf_memfind(struct pbuf* p, const void* mem, u16_t mem_len, u16_t start_offset)
01119 {
01120   u16_t i;
01121   u16_t max = p->tot_len - mem_len;
01122   if (p->tot_len >= mem_len + start_offset) {
01123     for(i = start_offset; i <= max; ) {
01124       u16_t plus = pbuf_memcmp(p, i, mem, mem_len);
01125       if (plus == 0) {
01126         return i;
01127       } else {
01128         i += plus;
01129       }
01130     }
01131   }
01132   return 0xFFFF;
01133 }
01134 
01135 /** Find occurrence of substr with length substr_len in pbuf p, start at offset
01136  * start_offset
01137  * WARNING: in contrast to strstr(), this one does not stop at the first \0 in
01138  * the pbuf/source string!
01139  *
01140  * @param p pbuf to search, maximum length is 0xFFFE since 0xFFFF is used as
01141  *        return value 'not found'
01142  * @param substr string to search for in p, maximum length is 0xFFFE
01143  * @return 0xFFFF if substr was not found in p or the index where it was found
01144  */
01145 u16_t
01146 pbuf_strstr(struct pbuf* p, const char* substr)
01147 {
01148   size_t substr_len;
01149   if ((substr == NULL) || (substr[0] == 0) || (p->tot_len == 0xFFFF)) {
01150     return 0xFFFF;
01151   }
01152   substr_len = strlen(substr);
01153   if (substr_len >= 0xFFFF) {
01154     return 0xFFFF;
01155   }
01156   return pbuf_memfind(p, substr, (u16_t)substr_len, 0);
01157 }