lwip_pbuf.c

00001 /**
00002  * @file
00003  * Packet buffer management
00004  */
00005 
00006 /**
00007  * @defgroup pbuf Packet buffers (PBUF)
00008  * @ingroup infrastructure
00009  *
00010  * Packets are built from the pbuf data structure. It supports dynamic
00011  * memory allocation for packet contents or can reference externally
00012  * managed packet contents both in RAM and ROM. Quick allocation for
00013  * incoming packets is provided through pools with fixed sized pbufs.
00014  *
00015  * A packet may span over multiple pbufs, chained as a singly linked
00016  * list. This is called a "pbuf chain".
00017  *
00018  * Multiple packets may be queued, also using this singly linked list.
00019  * This is called a "packet queue".
00020  *
00021  * So, a packet queue consists of one or more pbuf chains, each of
00022  * which consist of one or more pbufs. CURRENTLY, PACKET QUEUES ARE
00023  * NOT SUPPORTED!!! Use helper structs to queue multiple packets.
00024  *
00025  * The differences between a pbuf chain and a packet queue are very
00026  * precise but subtle.
00027  *
00028  * The last pbuf of a packet has a ->tot_len field that equals the
00029  * ->len field. It can be found by traversing the list. If the last
00030  * pbuf of a packet has a ->next field other than NULL, more packets
00031  * are on the queue.
00032  *
00033  * Therefore, looping through a pbuf of a single packet, has an
00034  * loop end condition (tot_len == p->len), NOT (next == NULL).
00035  */
00036 
00037 /*
00038  * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
00039  * All rights reserved.
00040  *
00041  * Redistribution and use in source and binary forms, with or without modification,
00042  * are permitted provided that the following conditions are met:
00043  *
00044  * 1. Redistributions of source code must retain the above copyright notice,
00045  *    this list of conditions and the following disclaimer.
00046  * 2. Redistributions in binary form must reproduce the above copyright notice,
00047  *    this list of conditions and the following disclaimer in the documentation
00048  *    and/or other materials provided with the distribution.
00049  * 3. The name of the author may not be used to endorse or promote products
00050  *    derived from this software without specific prior written permission.
00051  *
00052  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
00053  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
00054  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
00055  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
00056  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
00057  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
00058  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
00059  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
00060  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
00061  * OF SUCH DAMAGE.
00062  *
00063  * This file is part of the lwIP TCP/IP stack.
00064  *
00065  * Author: Adam Dunkels <adam@sics.se>
00066  *
00067  */
00068 
00069 #include "lwip/opt.h"
00070 
00071 #include "lwip/stats.h"
00072 #include "lwip/def.h"
00073 #include "lwip/mem.h"
00074 #include "lwip/memp.h"
00075 #include "lwip/pbuf.h"
00076 #include "lwip/sys.h"
00077 #if LWIP_TCP && TCP_QUEUE_OOSEQ
00078 #include "lwip/priv/tcp_priv.h"
00079 #endif
00080 #if LWIP_CHECKSUM_ON_COPY
00081 #include "lwip/inet_chksum.h"
00082 #endif
00083 
00084 #include <string.h>
00085 
00086 #define SIZEOF_STRUCT_PBUF        LWIP_MEM_ALIGN_SIZE(sizeof(struct pbuf))
00087 /* Since the pool is created in memp, PBUF_POOL_BUFSIZE will be automatically
00088    aligned there. Therefore, PBUF_POOL_BUFSIZE_ALIGNED can be used here. */
00089 #define PBUF_POOL_BUFSIZE_ALIGNED LWIP_MEM_ALIGN_SIZE(PBUF_POOL_BUFSIZE)
00090 
00091 #if !LWIP_TCP || !TCP_QUEUE_OOSEQ || !PBUF_POOL_FREE_OOSEQ
00092 #define PBUF_POOL_IS_EMPTY()
00093 #else /* !LWIP_TCP || !TCP_QUEUE_OOSEQ || !PBUF_POOL_FREE_OOSEQ */
00094 
00095 #if !NO_SYS
00096 #ifndef PBUF_POOL_FREE_OOSEQ_QUEUE_CALL
00097 #include "lwip/tcpip.h"
00098 #define PBUF_POOL_FREE_OOSEQ_QUEUE_CALL()  do { \
00099   if (tcpip_callback_with_block(pbuf_free_ooseq_callback, NULL, 0) != ERR_OK) { \
00100       SYS_ARCH_PROTECT(old_level); \
00101       pbuf_free_ooseq_pending = 0; \
00102       SYS_ARCH_UNPROTECT(old_level); \
00103   } } while(0)
00104 #endif /* PBUF_POOL_FREE_OOSEQ_QUEUE_CALL */
00105 #endif /* !NO_SYS */
00106 
00107 volatile u8_t pbuf_free_ooseq_pending;
00108 #define PBUF_POOL_IS_EMPTY() pbuf_pool_is_empty()
00109 
00110 /**
00111  * Attempt to reclaim some memory from queued out-of-sequence TCP segments
00112  * if we run out of pool pbufs. It's better to give priority to new packets
00113  * if we're running out.
00114  *
00115  * This must be done in the correct thread context therefore this function
00116  * can only be used with NO_SYS=0 and through tcpip_callback.
00117  */
00118 #if !NO_SYS
00119 static
00120 #endif /* !NO_SYS */
00121 void
00122 pbuf_free_ooseq(void)
00123 {
00124   struct tcp_pcb* pcb;
00125   SYS_ARCH_SET(pbuf_free_ooseq_pending, 0);
00126 
00127   for (pcb = tcp_active_pcbs; NULL != pcb; pcb = pcb->next) {
00128     if (NULL != pcb->ooseq) {
00129       /** Free the ooseq pbufs of one PCB only */
00130       LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_free_ooseq: freeing out-of-sequence pbufs\n"));
00131       tcp_segs_free(pcb->ooseq);
00132       pcb->ooseq = NULL;
00133       return;
00134     }
00135   }
00136 }
00137 
00138 #if !NO_SYS
00139 /**
00140  * Just a callback function for tcpip_callback() that calls pbuf_free_ooseq().
00141  */
00142 static void
00143 pbuf_free_ooseq_callback(void *arg)
00144 {
00145   LWIP_UNUSED_ARG(arg);
00146   pbuf_free_ooseq();
00147 }
00148 #endif /* !NO_SYS */
00149 
00150 /** Queue a call to pbuf_free_ooseq if not already queued. */
00151 static void
00152 pbuf_pool_is_empty(void)
00153 {
00154 #ifndef PBUF_POOL_FREE_OOSEQ_QUEUE_CALL
00155   SYS_ARCH_SET(pbuf_free_ooseq_pending, 1);
00156 #else /* PBUF_POOL_FREE_OOSEQ_QUEUE_CALL */
00157   u8_t queued;
00158   SYS_ARCH_DECL_PROTECT(old_level);
00159   SYS_ARCH_PROTECT(old_level);
00160   queued = pbuf_free_ooseq_pending;
00161   pbuf_free_ooseq_pending = 1;
00162   SYS_ARCH_UNPROTECT(old_level);
00163 
00164   if (!queued) {
00165     /* queue a call to pbuf_free_ooseq if not already queued */
00166     PBUF_POOL_FREE_OOSEQ_QUEUE_CALL();
00167   }
00168 #endif /* PBUF_POOL_FREE_OOSEQ_QUEUE_CALL */
00169 }
00170 #endif /* !LWIP_TCP || !TCP_QUEUE_OOSEQ || !PBUF_POOL_FREE_OOSEQ */
00171 
00172 /**
00173  * @ingroup pbuf
00174  * Allocates a pbuf of the given type (possibly a chain for PBUF_POOL type).
00175  *
00176  * The actual memory allocated for the pbuf is determined by the
00177  * layer at which the pbuf is allocated and the requested size
00178  * (from the size parameter).
00179  *
00180  * @param layer flag to define header size
00181  * @param length size of the pbuf's payload
00182  * @param type this parameter decides how and where the pbuf
00183  * should be allocated as follows:
00184  *
00185  * - PBUF_RAM: buffer memory for pbuf is allocated as one large
00186  *             chunk. This includes protocol headers as well.
00187  * - PBUF_ROM: no buffer memory is allocated for the pbuf, even for
00188  *             protocol headers. Additional headers must be prepended
00189  *             by allocating another pbuf and chain in to the front of
00190  *             the ROM pbuf. It is assumed that the memory used is really
00191  *             similar to ROM in that it is immutable and will not be
00192  *             changed. Memory which is dynamic should generally not
00193  *             be attached to PBUF_ROM pbufs. Use PBUF_REF instead.
00194  * - PBUF_REF: no buffer memory is allocated for the pbuf, even for
00195  *             protocol headers. It is assumed that the pbuf is only
00196  *             being used in a single thread. If the pbuf gets queued,
00197  *             then pbuf_take should be called to copy the buffer.
00198  * - PBUF_POOL: the pbuf is allocated as a pbuf chain, with pbufs from
00199  *              the pbuf pool that is allocated during pbuf_init().
00200  *
00201  * @return the allocated pbuf. If multiple pbufs where allocated, this
00202  * is the first pbuf of a pbuf chain.
00203  */
00204 struct pbuf *
00205 pbuf_alloc(pbuf_layer layer, u16_t length, pbuf_type type)
00206 {
00207   struct pbuf *p, *q, *r;
00208   u16_t offset;
00209   s32_t rem_len; /* remaining length */
00210   LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_alloc(length=%"U16_F")\n", length));
00211 
00212   /* determine header offset */
00213   switch (layer) {
00214   case PBUF_TRANSPORT:
00215     /* add room for transport (often TCP) layer header */
00216     offset = PBUF_LINK_ENCAPSULATION_HLEN + PBUF_LINK_HLEN + PBUF_IP_HLEN + PBUF_TRANSPORT_HLEN;
00217     break;
00218   case PBUF_IP:
00219     /* add room for IP layer header */
00220     offset = PBUF_LINK_ENCAPSULATION_HLEN + PBUF_LINK_HLEN + PBUF_IP_HLEN;
00221     break;
00222   case PBUF_LINK:
00223     /* add room for link layer header */
00224     offset = PBUF_LINK_ENCAPSULATION_HLEN + PBUF_LINK_HLEN;
00225     break;
00226   case PBUF_RAW_TX:
00227     /* add room for encapsulating link layer headers (e.g. 802.11) */
00228     offset = PBUF_LINK_ENCAPSULATION_HLEN;
00229     break;
00230   case PBUF_RAW:
00231     /* no offset (e.g. RX buffers or chain successors) */
00232     offset = 0;
00233     break;
00234   default:
00235     LWIP_ASSERT("pbuf_alloc: bad pbuf layer", 0);
00236     return NULL;
00237   }
00238 
00239   switch (type) {
00240   case PBUF_POOL:
00241     /* allocate head of pbuf chain into p */
00242     p = (struct pbuf *)memp_malloc(MEMP_PBUF_POOL);
00243     LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_alloc: allocated pbuf %p\n", (void *)p));
00244     if (p == NULL) {
00245       PBUF_POOL_IS_EMPTY();
00246       return NULL;
00247     }
00248     p->type = type;
00249     p->next = NULL;
00250 
00251     /* make the payload pointer point 'offset' bytes into pbuf data memory */
00252     p->payload = LWIP_MEM_ALIGN((void *)((u8_t *)p + (SIZEOF_STRUCT_PBUF + offset)));
00253     LWIP_ASSERT("pbuf_alloc: pbuf p->payload properly aligned",
00254             ((mem_ptr_t)p->payload % MEM_ALIGNMENT) == 0);
00255     /* the total length of the pbuf chain is the requested size */
00256     p->tot_len = length;
00257     /* set the length of the first pbuf in the chain */
00258     p->len = LWIP_MIN(length, PBUF_POOL_BUFSIZE_ALIGNED - LWIP_MEM_ALIGN_SIZE(offset));
00259     LWIP_ASSERT("check p->payload + p->len does not overflow pbuf",
00260                 ((u8_t*)p->payload + p->len <=
00261                  (u8_t*)p + SIZEOF_STRUCT_PBUF + PBUF_POOL_BUFSIZE_ALIGNED));
00262     LWIP_ASSERT("PBUF_POOL_BUFSIZE must be bigger than MEM_ALIGNMENT",
00263       (PBUF_POOL_BUFSIZE_ALIGNED - LWIP_MEM_ALIGN_SIZE(offset)) > 0 );
00264     /* set reference count (needed here in case we fail) */
00265     p->ref = 1;
00266 
00267     /* now allocate the tail of the pbuf chain */
00268 
00269     /* remember first pbuf for linkage in next iteration */
00270     r = p;
00271     /* remaining length to be allocated */
00272     rem_len = length - p->len;
00273     /* any remaining pbufs to be allocated? */
00274     while (rem_len > 0) {
00275       q = (struct pbuf *)memp_malloc(MEMP_PBUF_POOL);
00276       if (q == NULL) {
00277         PBUF_POOL_IS_EMPTY();
00278         /* free chain so far allocated */
00279         pbuf_free(p);
00280         /* bail out unsuccessfully */
00281         return NULL;
00282       }
00283       q->type = type;
00284       q->flags = 0;
00285       q->next = NULL;
00286       /* make previous pbuf point to this pbuf */
00287       r->next = q;
00288       /* set total length of this pbuf and next in chain */
00289       LWIP_ASSERT("rem_len < max_u16_t", rem_len < 0xffff);
00290       q->tot_len = (u16_t)rem_len;
00291       /* this pbuf length is pool size, unless smaller sized tail */
00292       q->len = LWIP_MIN((u16_t)rem_len, PBUF_POOL_BUFSIZE_ALIGNED);
00293       q->payload = (void *)((u8_t *)q + SIZEOF_STRUCT_PBUF);
00294       LWIP_ASSERT("pbuf_alloc: pbuf q->payload properly aligned",
00295               ((mem_ptr_t)q->payload % MEM_ALIGNMENT) == 0);
00296       LWIP_ASSERT("check p->payload + p->len does not overflow pbuf",
00297                   ((u8_t*)p->payload + p->len <=
00298                    (u8_t*)p + SIZEOF_STRUCT_PBUF + PBUF_POOL_BUFSIZE_ALIGNED));
00299       q->ref = 1;
00300       /* calculate remaining length to be allocated */
00301       rem_len -= q->len;
00302       /* remember this pbuf for linkage in next iteration */
00303       r = q;
00304     }
00305     /* end of chain */
00306     /*r->next = NULL;*/
00307 
00308     break;
00309   case PBUF_RAM:
00310     /* If pbuf is to be allocated in RAM, allocate memory for it. */
00311     p = (struct pbuf*)mem_malloc(LWIP_MEM_ALIGN_SIZE(SIZEOF_STRUCT_PBUF + offset) + LWIP_MEM_ALIGN_SIZE(length));
00312     if (p == NULL) {
00313       return NULL;
00314     }
00315     /* Set up internal structure of the pbuf. */
00316     p->payload = LWIP_MEM_ALIGN((void *)((u8_t *)p + SIZEOF_STRUCT_PBUF + offset));
00317     p->len = p->tot_len = length;
00318     p->next = NULL;
00319     p->type = type;
00320 
00321     LWIP_ASSERT("pbuf_alloc: pbuf->payload properly aligned",
00322            ((mem_ptr_t)p->payload % MEM_ALIGNMENT) == 0);
00323     break;
00324   /* pbuf references existing (non-volatile static constant) ROM payload? */
00325   case PBUF_ROM:
00326   /* pbuf references existing (externally allocated) RAM payload? */
00327   case PBUF_REF:
00328     /* only allocate memory for the pbuf structure */
00329     p = (struct pbuf *)memp_malloc(MEMP_PBUF);
00330     if (p == NULL) {
00331       LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
00332                   ("pbuf_alloc: Could not allocate MEMP_PBUF for PBUF_%s.\n",
00333                   (type == PBUF_ROM) ? "ROM" : "REF"));
00334       return NULL;
00335     }
00336     /* caller must set this field properly, afterwards */
00337     p->payload = NULL;
00338     p->len = p->tot_len = length;
00339     p->next = NULL;
00340     p->type = type;
00341     break;
00342   default:
00343     LWIP_ASSERT("pbuf_alloc: erroneous type", 0);
00344     return NULL;
00345   }
00346   /* set reference count */
00347   p->ref = 1;
00348   /* set flags */
00349   p->flags = 0;
00350   LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_alloc(length=%"U16_F") == %p\n", length, (void *)p));
00351   return p;
00352 }
00353 
00354 #if LWIP_SUPPORT_CUSTOM_PBUF
00355 /**
00356  * @ingroup pbuf
00357  * Initialize a custom pbuf (already allocated).
00358  *
00359  * @param l flag to define header size
00360  * @param length size of the pbuf's payload
00361  * @param type type of the pbuf (only used to treat the pbuf accordingly, as
00362  *        this function allocates no memory)
00363  * @param p pointer to the custom pbuf to initialize (already allocated)
00364  * @param payload_mem pointer to the buffer that is used for payload and headers,
00365  *        must be at least big enough to hold 'length' plus the header size,
00366  *        may be NULL if set later.
00367  *        ATTENTION: The caller is responsible for correct alignment of this buffer!!
00368  * @param payload_mem_len the size of the 'payload_mem' buffer, must be at least
00369  *        big enough to hold 'length' plus the header size
00370  */
00371 struct pbuf*
00372 pbuf_alloced_custom(pbuf_layer l, u16_t length, pbuf_type type, struct pbuf_custom *p,
00373                     void *payload_mem, u16_t payload_mem_len)
00374 {
00375   u16_t offset;
00376   LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_alloced_custom(length=%"U16_F")\n", length));
00377 
00378   /* determine header offset */
00379   switch (l) {
00380   case PBUF_TRANSPORT:
00381     /* add room for transport (often TCP) layer header */
00382     offset = PBUF_LINK_ENCAPSULATION_HLEN + PBUF_LINK_HLEN + PBUF_IP_HLEN + PBUF_TRANSPORT_HLEN;
00383     break;
00384   case PBUF_IP:
00385     /* add room for IP layer header */
00386     offset = PBUF_LINK_ENCAPSULATION_HLEN + PBUF_LINK_HLEN + PBUF_IP_HLEN;
00387     break;
00388   case PBUF_LINK:
00389     /* add room for link layer header */
00390     offset = PBUF_LINK_ENCAPSULATION_HLEN + PBUF_LINK_HLEN;
00391     break;
00392   case PBUF_RAW_TX:
00393     /* add room for encapsulating link layer headers (e.g. 802.11) */
00394     offset = PBUF_LINK_ENCAPSULATION_HLEN;
00395     break;
00396   case PBUF_RAW:
00397     offset = 0;
00398     break;
00399   default:
00400     LWIP_ASSERT("pbuf_alloced_custom: bad pbuf layer", 0);
00401     return NULL;
00402   }
00403 
00404   if (LWIP_MEM_ALIGN_SIZE(offset) + length > payload_mem_len) {
00405     LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_LEVEL_WARNING, ("pbuf_alloced_custom(length=%"U16_F") buffer too short\n", length));
00406     return NULL;
00407   }
00408 
00409   p->pbuf.next = NULL;
00410   if (payload_mem != NULL) {
00411     p->pbuf.payload = (u8_t *)payload_mem + LWIP_MEM_ALIGN_SIZE(offset);
00412   } else {
00413     p->pbuf.payload = NULL;
00414   }
00415   p->pbuf.flags = PBUF_FLAG_IS_CUSTOM;
00416   p->pbuf.len = p->pbuf.tot_len = length;
00417   p->pbuf.type = type;
00418   p->pbuf.ref = 1;
00419   return &p->pbuf;
00420 }
00421 #endif /* LWIP_SUPPORT_CUSTOM_PBUF */
00422 
00423 /**
00424  * @ingroup pbuf
00425  * Shrink a pbuf chain to a desired length.
00426  *
00427  * @param p pbuf to shrink.
00428  * @param new_len desired new length of pbuf chain
00429  *
00430  * Depending on the desired length, the first few pbufs in a chain might
00431  * be skipped and left unchanged. The new last pbuf in the chain will be
00432  * resized, and any remaining pbufs will be freed.
00433  *
00434  * @note If the pbuf is ROM/REF, only the ->tot_len and ->len fields are adjusted.
00435  * @note May not be called on a packet queue.
00436  *
00437  * @note Despite its name, pbuf_realloc cannot grow the size of a pbuf (chain).
00438  */
00439 void
00440 pbuf_realloc(struct pbuf *p, u16_t new_len)
00441 {
00442   struct pbuf *q;
00443   u16_t rem_len; /* remaining length */
00444   s32_t grow;
00445 
00446   LWIP_ASSERT("pbuf_realloc: p != NULL", p != NULL);
00447   LWIP_ASSERT("pbuf_realloc: sane p->type", p->type == PBUF_POOL ||
00448               p->type == PBUF_ROM ||
00449               p->type == PBUF_RAM ||
00450               p->type == PBUF_REF);
00451 
00452   /* desired length larger than current length? */
00453   if (new_len >= p->tot_len) {
00454     /* enlarging not yet supported */
00455     return;
00456   }
00457 
00458   /* the pbuf chain grows by (new_len - p->tot_len) bytes
00459    * (which may be negative in case of shrinking) */
00460   grow = new_len - p->tot_len;
00461 
00462   /* first, step over any pbufs that should remain in the chain */
00463   rem_len = new_len;
00464   q = p;
00465   /* should this pbuf be kept? */
00466   while (rem_len > q->len) {
00467     /* decrease remaining length by pbuf length */
00468     rem_len -= q->len;
00469     /* decrease total length indicator */
00470     LWIP_ASSERT("grow < max_u16_t", grow < 0xffff);
00471     q->tot_len += (u16_t)grow;
00472     /* proceed to next pbuf in chain */
00473     q = q->next;
00474     LWIP_ASSERT("pbuf_realloc: q != NULL", q != NULL);
00475   }
00476   /* we have now reached the new last pbuf (in q) */
00477   /* rem_len == desired length for pbuf q */
00478 
00479   /* shrink allocated memory for PBUF_RAM */
00480   /* (other types merely adjust their length fields */
00481   if ((q->type == PBUF_RAM) && (rem_len != q->len)
00482 #if LWIP_SUPPORT_CUSTOM_PBUF
00483       && ((q->flags & PBUF_FLAG_IS_CUSTOM) == 0)
00484 #endif /* LWIP_SUPPORT_CUSTOM_PBUF */
00485      ) {
00486     /* reallocate and adjust the length of the pbuf that will be split */
00487     q = (struct pbuf *)mem_trim(q, (u16_t)((u8_t *)q->payload - (u8_t *)q) + rem_len);
00488     LWIP_ASSERT("mem_trim returned q == NULL", q != NULL);
00489   }
00490   /* adjust length fields for new last pbuf */
00491   q->len = rem_len;
00492   q->tot_len = q->len;
00493 
00494   /* any remaining pbufs in chain? */
00495   if (q->next != NULL) {
00496     /* free remaining pbufs in chain */
00497     pbuf_free(q->next);
00498   }
00499   /* q is last packet in chain */
00500   q->next = NULL;
00501 
00502 }
00503 
00504 /**
00505  * Adjusts the payload pointer to hide or reveal headers in the payload.
00506  * @see pbuf_header.
00507  *
00508  * @param p pbuf to change the header size.
00509  * @param header_size_increment Number of bytes to increment header size.
00510  * @param force Allow 'header_size_increment > 0' for PBUF_REF/PBUF_ROM types
00511  *
00512  * @return non-zero on failure, zero on success.
00513  *
00514  */
00515 static u8_t
00516 pbuf_header_impl(struct pbuf *p, s16_t header_size_increment, u8_t force)
00517 {
00518   u16_t type;
00519   void *payload;
00520   u16_t increment_magnitude;
00521 
00522   LWIP_ASSERT("p != NULL", p != NULL);
00523   if ((header_size_increment == 0) || (p == NULL)) {
00524     return 0;
00525   }
00526 
00527   if (header_size_increment < 0) {
00528     increment_magnitude = -header_size_increment;
00529     /* Check that we aren't going to move off the end of the pbuf */
00530     LWIP_ERROR("increment_magnitude <= p->len", (increment_magnitude <= p->len), return 1;);
00531   } else {
00532     increment_magnitude = header_size_increment;
00533 #if 0
00534     /* Can't assert these as some callers speculatively call
00535          pbuf_header() to see if it's OK.  Will return 1 below instead. */
00536     /* Check that we've got the correct type of pbuf to work with */
00537     LWIP_ASSERT("p->type == PBUF_RAM || p->type == PBUF_POOL",
00538                 p->type == PBUF_RAM || p->type == PBUF_POOL);
00539     /* Check that we aren't going to move off the beginning of the pbuf */
00540     LWIP_ASSERT("p->payload - increment_magnitude >= p + SIZEOF_STRUCT_PBUF",
00541                 (u8_t *)p->payload - increment_magnitude >= (u8_t *)p + SIZEOF_STRUCT_PBUF);
00542 #endif
00543   }
00544 
00545   type = p->type;
00546   /* remember current payload pointer */
00547   payload = p->payload;
00548 
00549   /* pbuf types containing payloads? */
00550   if (type == PBUF_RAM || type == PBUF_POOL) {
00551     /* set new payload pointer */
00552     p->payload = (u8_t *)p->payload - header_size_increment;
00553     /* boundary check fails? */
00554     if ((u8_t *)p->payload < (u8_t *)p + SIZEOF_STRUCT_PBUF) {
00555       LWIP_DEBUGF( PBUF_DEBUG | LWIP_DBG_TRACE,
00556         ("pbuf_header: failed as %p < %p (not enough space for new header size)\n",
00557         (void *)p->payload, (void *)((u8_t *)p + SIZEOF_STRUCT_PBUF)));
00558       /* restore old payload pointer */
00559       p->payload = payload;
00560       /* bail out unsuccessfully */
00561       return 1;
00562     }
00563   /* pbuf types referring to external payloads? */
00564   } else if (type == PBUF_REF || type == PBUF_ROM) {
00565     /* hide a header in the payload? */
00566     if ((header_size_increment < 0) && (increment_magnitude <= p->len)) {
00567       /* increase payload pointer */
00568       p->payload = (u8_t *)p->payload - header_size_increment;
00569     } else if ((header_size_increment > 0) && force) {
00570       p->payload = (u8_t *)p->payload - header_size_increment;
00571     } else {
00572       /* cannot expand payload to front (yet!)
00573        * bail out unsuccessfully */
00574       return 1;
00575     }
00576   } else {
00577     /* Unknown type */
00578     LWIP_ASSERT("bad pbuf type", 0);
00579     return 1;
00580   }
00581   /* modify pbuf length fields */
00582   p->len += header_size_increment;
00583   p->tot_len += header_size_increment;
00584 
00585   LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_header: old %p new %p (%"S16_F")\n",
00586     (void *)payload, (void *)p->payload, header_size_increment));
00587 
00588   return 0;
00589 }
00590 
00591 /**
00592  * Adjusts the payload pointer to hide or reveal headers in the payload.
00593  *
00594  * Adjusts the ->payload pointer so that space for a header
00595  * (dis)appears in the pbuf payload.
00596  *
00597  * The ->payload, ->tot_len and ->len fields are adjusted.
00598  *
00599  * @param p pbuf to change the header size.
00600  * @param header_size_increment Number of bytes to increment header size which
00601  * increases the size of the pbuf. New space is on the front.
00602  * (Using a negative value decreases the header size.)
00603  * If hdr_size_inc is 0, this function does nothing and returns successful.
00604  *
00605  * PBUF_ROM and PBUF_REF type buffers cannot have their sizes increased, so
00606  * the call will fail. A check is made that the increase in header size does
00607  * not move the payload pointer in front of the start of the buffer.
00608  * @return non-zero on failure, zero on success.
00609  *
00610  */
00611 u8_t
00612 pbuf_header(struct pbuf *p, s16_t header_size_increment)
00613 {
00614    return pbuf_header_impl(p, header_size_increment, 0);
00615 }
00616 
00617 /**
00618  * Same as pbuf_header but does not check if 'header_size > 0' is allowed.
00619  * This is used internally only, to allow PBUF_REF for RX.
00620  */
00621 u8_t
00622 pbuf_header_force(struct pbuf *p, s16_t header_size_increment)
00623 {
00624    return pbuf_header_impl(p, header_size_increment, 1);
00625 }
00626 
00627 /**
00628  * @ingroup pbuf
00629  * Dereference a pbuf chain or queue and deallocate any no-longer-used
00630  * pbufs at the head of this chain or queue.
00631  *
00632  * Decrements the pbuf reference count. If it reaches zero, the pbuf is
00633  * deallocated.
00634  *
00635  * For a pbuf chain, this is repeated for each pbuf in the chain,
00636  * up to the first pbuf which has a non-zero reference count after
00637  * decrementing. So, when all reference counts are one, the whole
00638  * chain is free'd.
00639  *
00640  * @param p The pbuf (chain) to be dereferenced.
00641  *
00642  * @return the number of pbufs that were de-allocated
00643  * from the head of the chain.
00644  *
00645  * @note MUST NOT be called on a packet queue (Not verified to work yet).
00646  * @note the reference counter of a pbuf equals the number of pointers
00647  * that refer to the pbuf (or into the pbuf).
00648  *
00649  * @internal examples:
00650  *
00651  * Assuming existing chains a->b->c with the following reference
00652  * counts, calling pbuf_free(a) results in:
00653  *
00654  * 1->2->3 becomes ...1->3
00655  * 3->3->3 becomes 2->3->3
00656  * 1->1->2 becomes ......1
00657  * 2->1->1 becomes 1->1->1
00658  * 1->1->1 becomes .......
00659  *
00660  */
00661 u8_t
00662 pbuf_free(struct pbuf *p)
00663 {
00664   u16_t type;
00665   struct pbuf *q;
00666   u8_t count;
00667 
00668   if (p == NULL) {
00669     LWIP_ASSERT("p != NULL", p != NULL);
00670     /* if assertions are disabled, proceed with debug output */
00671     LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
00672       ("pbuf_free(p == NULL) was called.\n"));
00673     return 0;
00674   }
00675   LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_free(%p)\n", (void *)p));
00676 
00677   PERF_START;
00678 
00679   LWIP_ASSERT("pbuf_free: sane type",
00680     p->type == PBUF_RAM || p->type == PBUF_ROM ||
00681     p->type == PBUF_REF || p->type == PBUF_POOL);
00682 
00683   count = 0;
00684   /* de-allocate all consecutive pbufs from the head of the chain that
00685    * obtain a zero reference count after decrementing*/
00686   while (p != NULL) {
00687     u16_t ref;
00688     SYS_ARCH_DECL_PROTECT(old_level);
00689     /* Since decrementing ref cannot be guaranteed to be a single machine operation
00690      * we must protect it. We put the new ref into a local variable to prevent
00691      * further protection. */
00692     SYS_ARCH_PROTECT(old_level);
00693     /* all pbufs in a chain are referenced at least once */
00694     LWIP_ASSERT("pbuf_free: p->ref > 0", p->ref > 0);
00695     /* decrease reference count (number of pointers to pbuf) */
00696     ref = --(p->ref);
00697     SYS_ARCH_UNPROTECT(old_level);
00698     /* this pbuf is no longer referenced to? */
00699     if (ref == 0) {
00700       /* remember next pbuf in chain for next iteration */
00701       q = p->next;
00702       LWIP_DEBUGF( PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_free: deallocating %p\n", (void *)p));
00703       type = p->type;
00704 #if LWIP_SUPPORT_CUSTOM_PBUF
00705       /* is this a custom pbuf? */
00706       if ((p->flags & PBUF_FLAG_IS_CUSTOM) != 0) {
00707         struct pbuf_custom *pc = (struct pbuf_custom*)p;
00708         LWIP_ASSERT("pc->custom_free_function != NULL", pc->custom_free_function != NULL);
00709         pc->custom_free_function(p);
00710       } else
00711 #endif /* LWIP_SUPPORT_CUSTOM_PBUF */
00712       {
00713         /* is this a pbuf from the pool? */
00714         if (type == PBUF_POOL) {
00715           memp_free(MEMP_PBUF_POOL, p);
00716         /* is this a ROM or RAM referencing pbuf? */
00717         } else if (type == PBUF_ROM || type == PBUF_REF) {
00718           memp_free(MEMP_PBUF, p);
00719         /* type == PBUF_RAM */
00720         } else {
00721           mem_free(p);
00722         }
00723       }
00724       count++;
00725       /* proceed to next pbuf */
00726       p = q;
00727     /* p->ref > 0, this pbuf is still referenced to */
00728     /* (and so the remaining pbufs in chain as well) */
00729     } else {
00730       LWIP_DEBUGF( PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_free: %p has ref %"U16_F", ending here.\n", (void *)p, ref));
00731       /* stop walking through the chain */
00732       p = NULL;
00733     }
00734   }
00735   PERF_STOP("pbuf_free");
00736   /* return number of de-allocated pbufs */
00737   return count;
00738 }
00739 
00740 /**
00741  * Count number of pbufs in a chain
00742  *
00743  * @param p first pbuf of chain
00744  * @return the number of pbufs in a chain
00745  */
00746 u8_t
00747 pbuf_clen(struct pbuf *p)
00748 {
00749   u8_t len;
00750 
00751   len = 0;
00752   while (p != NULL) {
00753     ++len;
00754     p = p->next;
00755   }
00756   return len;
00757 }
00758 
00759 /**
00760  * @ingroup pbuf
00761  * Increment the reference count of the pbuf.
00762  *
00763  * @param p pbuf to increase reference counter of
00764  *
00765  */
00766 void
00767 pbuf_ref(struct pbuf *p)
00768 {
00769   SYS_ARCH_DECL_PROTECT(old_level);
00770   /* pbuf given? */
00771   if (p != NULL) {
00772     SYS_ARCH_PROTECT(old_level);
00773     ++(p->ref);
00774     SYS_ARCH_UNPROTECT(old_level);
00775   }
00776 }
00777 
00778 /**
00779  * @ingroup pbuf
00780  * Concatenate two pbufs (each may be a pbuf chain) and take over
00781  * the caller's reference of the tail pbuf.
00782  *
00783  * @note The caller MAY NOT reference the tail pbuf afterwards.
00784  * Use pbuf_chain() for that purpose.
00785  *
00786  * @see pbuf_chain()
00787  */
00788 void
00789 pbuf_cat(struct pbuf *h, struct pbuf *t)
00790 {
00791   struct pbuf *p;
00792 
00793   LWIP_ERROR("(h != NULL) && (t != NULL) (programmer violates API)",
00794              ((h != NULL) && (t != NULL)), return;);
00795 
00796   /* proceed to last pbuf of chain */
00797   for (p = h; p->next != NULL; p = p->next) {
00798     /* add total length of second chain to all totals of first chain */
00799     p->tot_len += t->tot_len;
00800   }
00801   /* { p is last pbuf of first h chain, p->next == NULL } */
00802   LWIP_ASSERT("p->tot_len == p->len (of last pbuf in chain)", p->tot_len == p->len);
00803   LWIP_ASSERT("p->next == NULL", p->next == NULL);
00804   /* add total length of second chain to last pbuf total of first chain */
00805   p->tot_len += t->tot_len;
00806   /* chain last pbuf of head (p) with first of tail (t) */
00807   p->next = t;
00808   /* p->next now references t, but the caller will drop its reference to t,
00809    * so netto there is no change to the reference count of t.
00810    */
00811 }
00812 
00813 /**
00814  * @ingroup pbuf
00815  * Chain two pbufs (or pbuf chains) together.
00816  *
00817  * The caller MUST call pbuf_free(t) once it has stopped
00818  * using it. Use pbuf_cat() instead if you no longer use t.
00819  *
00820  * @param h head pbuf (chain)
00821  * @param t tail pbuf (chain)
00822  * @note The pbufs MUST belong to the same packet.
00823  * @note MAY NOT be called on a packet queue.
00824  *
00825  * The ->tot_len fields of all pbufs of the head chain are adjusted.
00826  * The ->next field of the last pbuf of the head chain is adjusted.
00827  * The ->ref field of the first pbuf of the tail chain is adjusted.
00828  *
00829  */
00830 void
00831 pbuf_chain(struct pbuf *h, struct pbuf *t)
00832 {
00833   pbuf_cat(h, t);
00834   /* t is now referenced by h */
00835   pbuf_ref(t);
00836   LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_chain: %p references %p\n", (void *)h, (void *)t));
00837 }
00838 
00839 /**
00840  * Dechains the first pbuf from its succeeding pbufs in the chain.
00841  *
00842  * Makes p->tot_len field equal to p->len.
00843  * @param p pbuf to dechain
00844  * @return remainder of the pbuf chain, or NULL if it was de-allocated.
00845  * @note May not be called on a packet queue.
00846  */
00847 struct pbuf *
00848 pbuf_dechain(struct pbuf *p)
00849 {
00850   struct pbuf *q;
00851   u8_t tail_gone = 1;
00852   /* tail */
00853   q = p->next;
00854   /* pbuf has successor in chain? */
00855   if (q != NULL) {
00856     /* assert tot_len invariant: (p->tot_len == p->len + (p->next? p->next->tot_len: 0) */
00857     LWIP_ASSERT("p->tot_len == p->len + q->tot_len", q->tot_len == p->tot_len - p->len);
00858     /* enforce invariant if assertion is disabled */
00859     q->tot_len = p->tot_len - p->len;
00860     /* decouple pbuf from remainder */
00861     p->next = NULL;
00862     /* total length of pbuf p is its own length only */
00863     p->tot_len = p->len;
00864     /* q is no longer referenced by p, free it */
00865     LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_dechain: unreferencing %p\n", (void *)q));
00866     tail_gone = pbuf_free(q);
00867     if (tail_gone > 0) {
00868       LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE,
00869                   ("pbuf_dechain: deallocated %p (as it is no longer referenced)\n", (void *)q));
00870     }
00871     /* return remaining tail or NULL if deallocated */
00872   }
00873   /* assert tot_len invariant: (p->tot_len == p->len + (p->next? p->next->tot_len: 0) */
00874   LWIP_ASSERT("p->tot_len == p->len", p->tot_len == p->len);
00875   return ((tail_gone > 0) ? NULL : q);
00876 }
00877 
00878 /**
00879  * @ingroup pbuf
00880  * Create PBUF_RAM copies of pbufs.
00881  *
00882  * Used to queue packets on behalf of the lwIP stack, such as
00883  * ARP based queueing.
00884  *
00885  * @note You MUST explicitly use p = pbuf_take(p);
00886  *
00887  * @note Only one packet is copied, no packet queue!
00888  *
00889  * @param p_to pbuf destination of the copy
00890  * @param p_from pbuf source of the copy
00891  *
00892  * @return ERR_OK if pbuf was copied
00893  *         ERR_ARG if one of the pbufs is NULL or p_to is not big
00894  *                 enough to hold p_from
00895  */
00896 err_t
00897 pbuf_copy(struct pbuf *p_to, struct pbuf *p_from)
00898 {
00899   u16_t offset_to=0, offset_from=0, len;
00900 
00901   LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_copy(%p, %p)\n",
00902     (void*)p_to, (void*)p_from));
00903 
00904   /* is the target big enough to hold the source? */
00905   LWIP_ERROR("pbuf_copy: target not big enough to hold source", ((p_to != NULL) &&
00906              (p_from != NULL) && (p_to->tot_len >= p_from->tot_len)), return ERR_ARG;);
00907 
00908   /* iterate through pbuf chain */
00909   do
00910   {
00911     /* copy one part of the original chain */
00912     if ((p_to->len - offset_to) >= (p_from->len - offset_from)) {
00913       /* complete current p_from fits into current p_to */
00914       len = p_from->len - offset_from;
00915     } else {
00916       /* current p_from does not fit into current p_to */
00917       len = p_to->len - offset_to;
00918     }
00919     MEMCPY((u8_t*)p_to->payload + offset_to, (u8_t*)p_from->payload + offset_from, len);
00920     offset_to += len;
00921     offset_from += len;
00922     LWIP_ASSERT("offset_to <= p_to->len", offset_to <= p_to->len);
00923     LWIP_ASSERT("offset_from <= p_from->len", offset_from <= p_from->len);
00924     if (offset_from >= p_from->len) {
00925       /* on to next p_from (if any) */
00926       offset_from = 0;
00927       p_from = p_from->next;
00928     }
00929     if (offset_to == p_to->len) {
00930       /* on to next p_to (if any) */
00931       offset_to = 0;
00932       p_to = p_to->next;
00933       LWIP_ERROR("p_to != NULL", (p_to != NULL) || (p_from == NULL) , return ERR_ARG;);
00934     }
00935 
00936     if ((p_from != NULL) && (p_from->len == p_from->tot_len)) {
00937       /* don't copy more than one packet! */
00938       LWIP_ERROR("pbuf_copy() does not allow packet queues!",
00939                  (p_from->next == NULL), return ERR_VAL;);
00940     }
00941     if ((p_to != NULL) && (p_to->len == p_to->tot_len)) {
00942       /* don't copy more than one packet! */
00943       LWIP_ERROR("pbuf_copy() does not allow packet queues!",
00944                   (p_to->next == NULL), return ERR_VAL;);
00945     }
00946   } while (p_from);
00947   LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_copy: end of chain reached.\n"));
00948   return ERR_OK;
00949 }
00950 
00951 /**
00952  * @ingroup pbuf
00953  * Copy (part of) the contents of a packet buffer
00954  * to an application supplied buffer.
00955  *
00956  * @param buf the pbuf from which to copy data
00957  * @param dataptr the application supplied buffer
00958  * @param len length of data to copy (dataptr must be big enough). No more
00959  * than buf->tot_len will be copied, irrespective of len
00960  * @param offset offset into the packet buffer from where to begin copying len bytes
00961  * @return the number of bytes copied, or 0 on failure
00962  */
00963 u16_t
00964 pbuf_copy_partial(struct pbuf *buf, void *dataptr, u16_t len, u16_t offset)
00965 {
00966   struct pbuf *p;
00967   u16_t left;
00968   u16_t buf_copy_len;
00969   u16_t copied_total = 0;
00970 
00971   LWIP_ERROR("pbuf_copy_partial: invalid buf", (buf != NULL), return 0;);
00972   LWIP_ERROR("pbuf_copy_partial: invalid dataptr", (dataptr != NULL), return 0;);
00973 
00974   left = 0;
00975 
00976   if ((buf == NULL) || (dataptr == NULL)) {
00977     return 0;
00978   }
00979 
00980   /* Note some systems use byte copy if dataptr or one of the pbuf payload pointers are unaligned. */
00981   for (p = buf; len != 0 && p != NULL; p = p->next) {
00982     if ((offset != 0) && (offset >= p->len)) {
00983       /* don't copy from this buffer -> on to the next */
00984       offset -= p->len;
00985     } else {
00986       /* copy from this buffer. maybe only partially. */
00987       buf_copy_len = p->len - offset;
00988       if (buf_copy_len > len)
00989           buf_copy_len = len;
00990       /* copy the necessary parts of the buffer */
00991       MEMCPY(&((char*)dataptr)[left], &((char*)p->payload)[offset], buf_copy_len);
00992       copied_total += buf_copy_len;
00993       left += buf_copy_len;
00994       len -= buf_copy_len;
00995       offset = 0;
00996     }
00997   }
00998   return copied_total;
00999 }
01000 
01001 #if LWIP_TCP && TCP_QUEUE_OOSEQ && LWIP_WND_SCALE
01002 /**
01003  * This method modifies a 'pbuf chain', so that its total length is
01004  * smaller than 64K. The remainder of the original pbuf chain is stored
01005  * in *rest.
01006  * This function never creates new pbufs, but splits an existing chain
01007  * in two parts. The tot_len of the modified packet queue will likely be
01008  * smaller than 64K.
01009  * 'packet queues' are not supported by this function.
01010  *
01011  * @param p the pbuf queue to be split
01012  * @param rest pointer to store the remainder (after the first 64K)
01013  */
01014 void pbuf_split_64k(struct pbuf *p, struct pbuf **rest)
01015 {
01016   *rest = NULL;
01017   if ((p != NULL) && (p->next != NULL)) {
01018     u16_t tot_len_front = p->len;
01019     struct pbuf *i = p;
01020     struct pbuf *r = p->next;
01021 
01022     /* continue until the total length (summed up as u16_t) overflows */
01023     while ((r != NULL) && ((u16_t)(tot_len_front + r->len) > tot_len_front)) {
01024       tot_len_front += r->len;
01025       i = r;
01026       r = r->next;
01027     }
01028     /* i now points to last packet of the first segment. Set next
01029        pointer to NULL */
01030     i->next = NULL;
01031 
01032     if (r != NULL) {
01033       /* Update the tot_len field in the first part */
01034       for (i = p; i != NULL; i = i->next) {
01035         i->tot_len -= r->tot_len;
01036         LWIP_ASSERT("tot_len/len mismatch in last pbuf",
01037                     (i->next != NULL) || (i->tot_len == i->len));
01038       }
01039       if (p->flags & PBUF_FLAG_TCP_FIN) {
01040         r->flags |= PBUF_FLAG_TCP_FIN;
01041       }
01042 
01043       /* tot_len field in rest does not need modifications */
01044       /* reference counters do not need modifications */
01045       *rest = r;
01046     }
01047   }
01048 }
01049 #endif /* LWIP_TCP && TCP_QUEUE_OOSEQ && LWIP_WND_SCALE */
01050 
01051 /**
01052  * @ingroup pbuf
01053  * Skip a number of bytes at the start of a pbuf
01054  *
01055  * @param in input pbuf
01056  * @param in_offset offset to skip
01057  * @param out_offset resulting offset in the returned pbuf
01058  * @return the pbuf in the queue where the offset is
01059  */
01060 struct pbuf*
01061 pbuf_skip(struct pbuf* in, u16_t in_offset, u16_t* out_offset)
01062 {
01063   u16_t offset_left = in_offset;
01064   struct pbuf* q = in;
01065 
01066   /* get the correct pbuf */
01067   while ((q != NULL) && (q->len <= offset_left)) {
01068     offset_left -= q->len;
01069     q = q->next;
01070   }
01071   if (out_offset != NULL) {
01072     *out_offset = offset_left;
01073   }
01074   return q;
01075 }
01076 
01077 /**
01078  * @ingroup pbuf
01079  * Copy application supplied data into a pbuf.
01080  * This function can only be used to copy the equivalent of buf->tot_len data.
01081  *
01082  * @param buf pbuf to fill with data
01083  * @param dataptr application supplied data buffer
01084  * @param len length of the application supplied data buffer
01085  *
01086  * @return ERR_OK if successful, ERR_MEM if the pbuf is not big enough
01087  */
01088 err_t
01089 pbuf_take(struct pbuf *buf, const void *dataptr, u16_t len)
01090 {
01091   struct pbuf *p;
01092   u16_t buf_copy_len;
01093   u16_t total_copy_len = len;
01094   u16_t copied_total = 0;
01095 
01096   LWIP_ERROR("pbuf_take: invalid buf", (buf != NULL), return ERR_ARG;);
01097   LWIP_ERROR("pbuf_take: invalid dataptr", (dataptr != NULL), return ERR_ARG;);
01098   LWIP_ERROR("pbuf_take: buf not large enough", (buf->tot_len >= len), return ERR_MEM;);
01099 
01100   if ((buf == NULL) || (dataptr == NULL) || (buf->tot_len < len)) {
01101     return ERR_ARG;
01102   }
01103 
01104   /* Note some systems use byte copy if dataptr or one of the pbuf payload pointers are unaligned. */
01105   for (p = buf; total_copy_len != 0; p = p->next) {
01106     LWIP_ASSERT("pbuf_take: invalid pbuf", p != NULL);
01107     buf_copy_len = total_copy_len;
01108     if (buf_copy_len > p->len) {
01109       /* this pbuf cannot hold all remaining data */
01110       buf_copy_len = p->len;
01111     }
01112     /* copy the necessary parts of the buffer */
01113     MEMCPY(p->payload, &((const char*)dataptr)[copied_total], buf_copy_len);
01114     total_copy_len -= buf_copy_len;
01115     copied_total += buf_copy_len;
01116   }
01117   LWIP_ASSERT("did not copy all data", total_copy_len == 0 && copied_total == len);
01118   return ERR_OK;
01119 }
01120 
01121 /**
01122  * @ingroup pbuf
01123  * Same as pbuf_take() but puts data at an offset
01124  *
01125  * @param buf pbuf to fill with data
01126  * @param dataptr application supplied data buffer
01127  * @param len length of the application supplied data buffer
01128  * @param offset offset in pbuf where to copy dataptr to
01129  *
01130  * @return ERR_OK if successful, ERR_MEM if the pbuf is not big enough
01131  */
01132 err_t
01133 pbuf_take_at(struct pbuf *buf, const void *dataptr, u16_t len, u16_t offset)
01134 {
01135   u16_t target_offset;
01136   struct pbuf* q = pbuf_skip(buf, offset, &target_offset);
01137 
01138   /* return requested data if pbuf is OK */
01139   if ((q != NULL) && (q->tot_len >= target_offset + len)) {
01140     u16_t remaining_len = len;
01141     const u8_t* src_ptr = (const u8_t*)dataptr;
01142     /* copy the part that goes into the first pbuf */
01143     u16_t first_copy_len = LWIP_MIN(q->len - target_offset, len);
01144     MEMCPY(((u8_t*)q->payload) + target_offset, dataptr, first_copy_len);
01145     remaining_len -= first_copy_len;
01146     src_ptr += first_copy_len;
01147     if (remaining_len > 0) {
01148       return pbuf_take(q->next, src_ptr, remaining_len);
01149     }
01150     return ERR_OK;
01151   }
01152   return ERR_MEM;
01153 }
01154 
01155 /**
01156  * @ingroup pbuf
01157  * Creates a single pbuf out of a queue of pbufs.
01158  *
01159  * @remark: Either the source pbuf 'p' is freed by this function or the original
01160  *          pbuf 'p' is returned, therefore the caller has to check the result!
01161  *
01162  * @param p the source pbuf
01163  * @param layer pbuf_layer of the new pbuf
01164  *
01165  * @return a new, single pbuf (p->next is NULL)
01166  *         or the old pbuf if allocation fails
01167  */
01168 struct pbuf*
01169 pbuf_coalesce(struct pbuf *p, pbuf_layer layer)
01170 {
01171   struct pbuf *q;
01172   err_t err;
01173   if (p->next == NULL) {
01174     return p;
01175   }
01176   q = pbuf_alloc(layer, p->tot_len, PBUF_RAM);
01177   if (q == NULL) {
01178     /* @todo: what do we do now? */
01179     return p;
01180   }
01181   err = pbuf_copy(q, p);
01182   LWIP_ASSERT("pbuf_copy failed", err == ERR_OK);
01183   pbuf_free(p);
01184   return q;
01185 }
01186 
01187 #if LWIP_CHECKSUM_ON_COPY
01188 /**
01189  * Copies data into a single pbuf (*not* into a pbuf queue!) and updates
01190  * the checksum while copying
01191  *
01192  * @param p the pbuf to copy data into
01193  * @param start_offset offset of p->payload where to copy the data to
01194  * @param dataptr data to copy into the pbuf
01195  * @param len length of data to copy into the pbuf
01196  * @param chksum pointer to the checksum which is updated
01197  * @return ERR_OK if successful, another error if the data does not fit
01198  *         within the (first) pbuf (no pbuf queues!)
01199  */
01200 err_t
01201 pbuf_fill_chksum(struct pbuf *p, u16_t start_offset, const void *dataptr,
01202                  u16_t len, u16_t *chksum)
01203 {
01204   u32_t acc;
01205   u16_t copy_chksum;
01206   char *dst_ptr;
01207   LWIP_ASSERT("p != NULL", p != NULL);
01208   LWIP_ASSERT("dataptr != NULL", dataptr != NULL);
01209   LWIP_ASSERT("chksum != NULL", chksum != NULL);
01210   LWIP_ASSERT("len != 0", len != 0);
01211 
01212   if ((start_offset >= p->len) || (start_offset + len > p->len)) {
01213     return ERR_ARG;
01214   }
01215 
01216   dst_ptr = ((char*)p->payload) + start_offset;
01217   copy_chksum = LWIP_CHKSUM_COPY(dst_ptr, dataptr, len);
01218   if ((start_offset & 1) != 0) {
01219     copy_chksum = SWAP_BYTES_IN_WORD(copy_chksum);
01220   }
01221   acc = *chksum;
01222   acc += copy_chksum;
01223   *chksum = FOLD_U32T(acc);
01224   return ERR_OK;
01225 }
01226 #endif /* LWIP_CHECKSUM_ON_COPY */
01227 
01228 /** 
01229  * @ingroup pbuf
01230  * Get one byte from the specified position in a pbuf
01231  * WARNING: returns zero for offset >= p->tot_len
01232  *
01233  * @param p pbuf to parse
01234  * @param offset offset into p of the byte to return
01235  * @return byte at an offset into p OR ZERO IF 'offset' >= p->tot_len
01236  */
01237 u8_t
01238 pbuf_get_at(struct pbuf* p, u16_t offset)
01239 {
01240   u16_t q_idx;
01241   struct pbuf* q = pbuf_skip(p, offset, &q_idx);
01242 
01243   /* return requested data if pbuf is OK */
01244   if ((q != NULL) && (q->len > q_idx)) {
01245     return ((u8_t*)q->payload)[q_idx];
01246   }
01247   return 0;
01248 }
01249 
01250 /**
01251  * @ingroup pbuf
01252  * Put one byte to the specified position in a pbuf
01253  * WARNING: silently ignores offset >= p->tot_len
01254  *
01255  * @param p pbuf to fill
01256  * @param offset offset into p of the byte to write
01257  * @param data byte to write at an offset into p
01258  */
01259 void
01260 pbuf_put_at(struct pbuf* p, u16_t offset, u8_t data)
01261 {
01262   u16_t q_idx;
01263   struct pbuf* q = pbuf_skip(p, offset, &q_idx);
01264 
01265   /* write requested data if pbuf is OK */
01266   if ((q != NULL) && (q->len > q_idx)) {
01267     ((u8_t*)q->payload)[q_idx] = data;
01268   }
01269 }
01270 
01271 /**
01272  * @ingroup pbuf
01273  * Compare pbuf contents at specified offset with memory s2, both of length n
01274  *
01275  * @param p pbuf to compare
01276  * @param offset offset into p at which to start comparing
01277  * @param s2 buffer to compare
01278  * @param n length of buffer to compare
01279  * @return zero if equal, nonzero otherwise
01280  *         (0xffff if p is too short, diffoffset+1 otherwise)
01281  */
01282 u16_t
01283 pbuf_memcmp(struct pbuf* p, u16_t offset, const void* s2, u16_t n)
01284 {
01285   u16_t start = offset;
01286   struct pbuf* q = p;
01287 
01288   /* get the correct pbuf */
01289   while ((q != NULL) && (q->len <= start)) {
01290     start -= q->len;
01291     q = q->next;
01292   }
01293   /* return requested data if pbuf is OK */
01294   if ((q != NULL) && (q->len > start)) {
01295     u16_t i;
01296     for (i = 0; i < n; i++) {
01297       u8_t a = pbuf_get_at(q, start + i);
01298       u8_t b = ((const u8_t*)s2)[i];
01299       if (a != b) {
01300         return i+1;
01301       }
01302     }
01303     return 0;
01304   }
01305   return 0xffff;
01306 }
01307 
01308 /**
01309  * @ingroup pbuf
01310  * Find occurrence of mem (with length mem_len) in pbuf p, starting at offset
01311  * start_offset.
01312  *
01313  * @param p pbuf to search, maximum length is 0xFFFE since 0xFFFF is used as
01314  *        return value 'not found'
01315  * @param mem search for the contents of this buffer
01316  * @param mem_len length of 'mem'
01317  * @param start_offset offset into p at which to start searching
01318  * @return 0xFFFF if substr was not found in p or the index where it was found
01319  */
01320 u16_t
01321 pbuf_memfind(struct pbuf* p, const void* mem, u16_t mem_len, u16_t start_offset)
01322 {
01323   u16_t i;
01324   u16_t max = p->tot_len - mem_len;
01325   if (p->tot_len >= mem_len + start_offset) {
01326     for (i = start_offset; i <= max; i++) {
01327       u16_t plus = pbuf_memcmp(p, i, mem, mem_len);
01328       if (plus == 0) {
01329         return i;
01330       }
01331     }
01332   }
01333   return 0xFFFF;
01334 }
01335 
01336 /**
01337  * Find occurrence of substr with length substr_len in pbuf p, start at offset
01338  * start_offset
01339  * WARNING: in contrast to strstr(), this one does not stop at the first \0 in
01340  * the pbuf/source string!
01341  *
01342  * @param p pbuf to search, maximum length is 0xFFFE since 0xFFFF is used as
01343  *        return value 'not found'
01344  * @param substr string to search for in p, maximum length is 0xFFFE
01345  * @return 0xFFFF if substr was not found in p or the index where it was found
01346  */
01347 u16_t
01348 pbuf_strstr(struct pbuf* p, const char* substr)
01349 {
01350   size_t substr_len;
01351   if ((substr == NULL) || (substr[0] == 0) || (p->tot_len == 0xFFFF)) {
01352     return 0xFFFF;
01353   }
01354   substr_len = strlen(substr);
01355   if (substr_len >= 0xFFFF) {
01356     return 0xFFFF;
01357   }
01358   return pbuf_memfind(p, substr, (u16_t)substr_len, 0);
01359 }