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  * Example of custom pbuf usage for zero-copy RX:
00037   @code{.c}
00038 typedef struct my_custom_pbuf
00039 {
00040    struct pbuf_custom p;
00041    void* dma_descriptor;
00042 } my_custom_pbuf_t;
00043 
00044 LWIP_MEMPOOL_DECLARE(RX_POOL, 10, sizeof(my_custom_pbuf_t), "Zero-copy RX PBUF pool");
00045 
00046 void my_pbuf_free_custom(void* p)
00047 {
00048   my_custom_pbuf_t* my_puf = (my_custom_pbuf_t*)p;
00049 
00050   LOCK_INTERRUPTS();
00051   free_rx_dma_descriptor(my_pbuf->dma_descriptor);
00052   LWIP_MEMPOOL_FREE(RX_POOL, my_pbuf);
00053   UNLOCK_INTERRUPTS();
00054 }
00055 
00056 void eth_rx_irq()
00057 {
00058   dma_descriptor*   dma_desc = get_RX_DMA_descriptor_from_ethernet();
00059   my_custom_pbuf_t* my_pbuf  = (my_custom_pbuf_t*)LWIP_MEMPOOL_ALLOC(RX_POOL);
00060 
00061   my_pbuf->p.custom_free_function = my_pbuf_free_custom;
00062   my_pbuf->dma_descriptor         = dma_desc;
00063 
00064   invalidate_cpu_cache(dma_desc->rx_data, dma_desc->rx_length);
00065   
00066   struct pbuf* p = pbuf_alloced_custom(PBUF_RAW,
00067      dma_desc->rx_length,
00068      PBUF_REF,
00069      &my_pbuf->p,
00070      dma_desc->rx_data,
00071      dma_desc->max_buffer_size);
00072 
00073   if(netif->input(p, netif) != ERR_OK) {
00074     pbuf_free(p);
00075   }
00076 }
00077   @endcode
00078  */
00079 
00080 /*
00081  * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
00082  * All rights reserved.
00083  *
00084  * Redistribution and use in source and binary forms, with or without modification,
00085  * are permitted provided that the following conditions are met:
00086  *
00087  * 1. Redistributions of source code must retain the above copyright notice,
00088  *    this list of conditions and the following disclaimer.
00089  * 2. Redistributions in binary form must reproduce the above copyright notice,
00090  *    this list of conditions and the following disclaimer in the documentation
00091  *    and/or other materials provided with the distribution.
00092  * 3. The name of the author may not be used to endorse or promote products
00093  *    derived from this software without specific prior written permission.
00094  *
00095  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
00096  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
00097  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
00098  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
00099  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
00100  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
00101  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
00102  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
00103  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
00104  * OF SUCH DAMAGE.
00105  *
00106  * This file is part of the lwIP TCP/IP stack.
00107  *
00108  * Author: Adam Dunkels <adam@sics.se>
00109  *
00110  */
00111 
00112 #include "lwip/opt.h"
00113 
00114 #include "lwip/stats.h"
00115 #include "lwip/def.h"
00116 #include "lwip/mem.h"
00117 #include "lwip/memp.h"
00118 #include "lwip/pbuf.h"
00119 #include "lwip/sys.h"
00120 #if LWIP_TCP && TCP_QUEUE_OOSEQ
00121 #include "lwip/priv/tcp_priv.h"
00122 #endif
00123 #if LWIP_CHECKSUM_ON_COPY
00124 #include "lwip/inet_chksum.h"
00125 #endif
00126 
00127 #include <string.h>
00128 
00129 #define SIZEOF_STRUCT_PBUF        LWIP_MEM_ALIGN_SIZE(sizeof(struct pbuf))
00130 /* Since the pool is created in memp, PBUF_POOL_BUFSIZE will be automatically
00131    aligned there. Therefore, PBUF_POOL_BUFSIZE_ALIGNED can be used here. */
00132 #define PBUF_POOL_BUFSIZE_ALIGNED LWIP_MEM_ALIGN_SIZE(PBUF_POOL_BUFSIZE)
00133 
00134 #if !LWIP_TCP || !TCP_QUEUE_OOSEQ || !PBUF_POOL_FREE_OOSEQ
00135 #define PBUF_POOL_IS_EMPTY()
00136 #else /* !LWIP_TCP || !TCP_QUEUE_OOSEQ || !PBUF_POOL_FREE_OOSEQ */
00137 
00138 #if !NO_SYS
00139 #ifndef PBUF_POOL_FREE_OOSEQ_QUEUE_CALL
00140 #include "lwip/tcpip.h"
00141 #define PBUF_POOL_FREE_OOSEQ_QUEUE_CALL()  do { \
00142   if (tcpip_callback_with_block(pbuf_free_ooseq_callback, NULL, 0) != ERR_OK) { \
00143       SYS_ARCH_PROTECT(old_level); \
00144       pbuf_free_ooseq_pending = 0; \
00145       SYS_ARCH_UNPROTECT(old_level); \
00146   } } while(0)
00147 #endif /* PBUF_POOL_FREE_OOSEQ_QUEUE_CALL */
00148 #endif /* !NO_SYS */
00149 
00150 volatile u8_t pbuf_free_ooseq_pending;
00151 #define PBUF_POOL_IS_EMPTY() pbuf_pool_is_empty()
00152 
00153 /**
00154  * Attempt to reclaim some memory from queued out-of-sequence TCP segments
00155  * if we run out of pool pbufs. It's better to give priority to new packets
00156  * if we're running out.
00157  *
00158  * This must be done in the correct thread context therefore this function
00159  * can only be used with NO_SYS=0 and through tcpip_callback.
00160  */
00161 #if !NO_SYS
00162 static
00163 #endif /* !NO_SYS */
00164 void
00165 pbuf_free_ooseq(void)
00166 {
00167   struct tcp_pcb* pcb;
00168   SYS_ARCH_SET(pbuf_free_ooseq_pending, 0);
00169 
00170   for (pcb = tcp_active_pcbs; NULL != pcb; pcb = pcb->next) {
00171     if (NULL != pcb->ooseq) {
00172       /** Free the ooseq pbufs of one PCB only */
00173       LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_free_ooseq: freeing out-of-sequence pbufs\n"));
00174       tcp_segs_free(pcb->ooseq);
00175       pcb->ooseq = NULL;
00176       return;
00177     }
00178   }
00179 }
00180 
00181 #if !NO_SYS
00182 /**
00183  * Just a callback function for tcpip_callback() that calls pbuf_free_ooseq().
00184  */
00185 static void
00186 pbuf_free_ooseq_callback(void *arg)
00187 {
00188   LWIP_UNUSED_ARG(arg);
00189   pbuf_free_ooseq();
00190 }
00191 #endif /* !NO_SYS */
00192 
00193 /** Queue a call to pbuf_free_ooseq if not already queued. */
00194 static void
00195 pbuf_pool_is_empty(void)
00196 {
00197 #ifndef PBUF_POOL_FREE_OOSEQ_QUEUE_CALL
00198   SYS_ARCH_SET(pbuf_free_ooseq_pending, 1);
00199 #else /* PBUF_POOL_FREE_OOSEQ_QUEUE_CALL */
00200   u8_t queued;
00201   SYS_ARCH_DECL_PROTECT(old_level);
00202   SYS_ARCH_PROTECT(old_level);
00203   queued = pbuf_free_ooseq_pending;
00204   pbuf_free_ooseq_pending = 1;
00205   SYS_ARCH_UNPROTECT(old_level);
00206 
00207   if (!queued) {
00208     /* queue a call to pbuf_free_ooseq if not already queued */
00209     PBUF_POOL_FREE_OOSEQ_QUEUE_CALL();
00210   }
00211 #endif /* PBUF_POOL_FREE_OOSEQ_QUEUE_CALL */
00212 }
00213 #endif /* !LWIP_TCP || !TCP_QUEUE_OOSEQ || !PBUF_POOL_FREE_OOSEQ */
00214 
00215 /**
00216  * @ingroup pbuf
00217  * Allocates a pbuf of the given type (possibly a chain for PBUF_POOL type).
00218  *
00219  * The actual memory allocated for the pbuf is determined by the
00220  * layer at which the pbuf is allocated and the requested size
00221  * (from the size parameter).
00222  *
00223  * @param layer flag to define header size
00224  * @param length size of the pbuf's payload
00225  * @param type this parameter decides how and where the pbuf
00226  * should be allocated as follows:
00227  *
00228  * - PBUF_RAM: buffer memory for pbuf is allocated as one large
00229  *             chunk. This includes protocol headers as well.
00230  * - PBUF_ROM: no buffer memory is allocated for the pbuf, even for
00231  *             protocol headers. Additional headers must be prepended
00232  *             by allocating another pbuf and chain in to the front of
00233  *             the ROM pbuf. It is assumed that the memory used is really
00234  *             similar to ROM in that it is immutable and will not be
00235  *             changed. Memory which is dynamic should generally not
00236  *             be attached to PBUF_ROM pbufs. Use PBUF_REF instead.
00237  * - PBUF_REF: no buffer memory is allocated for the pbuf, even for
00238  *             protocol headers. It is assumed that the pbuf is only
00239  *             being used in a single thread. If the pbuf gets queued,
00240  *             then pbuf_take should be called to copy the buffer.
00241  * - PBUF_POOL: the pbuf is allocated as a pbuf chain, with pbufs from
00242  *              the pbuf pool that is allocated during pbuf_init().
00243  *
00244  * @return the allocated pbuf. If multiple pbufs where allocated, this
00245  * is the first pbuf of a pbuf chain.
00246  */
00247 struct pbuf *
00248 pbuf_alloc(pbuf_layer layer, u16_t length, pbuf_type type)
00249 {
00250   struct pbuf *p, *q, *r;
00251   u16_t offset;
00252   s32_t rem_len; /* remaining length */
00253   LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_alloc(length=%"U16_F")\n", length));
00254 
00255   /* determine header offset */
00256   switch (layer) {
00257   case PBUF_TRANSPORT:
00258     /* add room for transport (often TCP) layer header */
00259     offset = PBUF_LINK_ENCAPSULATION_HLEN + PBUF_LINK_HLEN + PBUF_IP_HLEN + PBUF_TRANSPORT_HLEN;
00260     break;
00261   case PBUF_IP:
00262     /* add room for IP layer header */
00263     offset = PBUF_LINK_ENCAPSULATION_HLEN + PBUF_LINK_HLEN + PBUF_IP_HLEN;
00264     break;
00265   case PBUF_LINK:
00266     /* add room for link layer header */
00267     offset = PBUF_LINK_ENCAPSULATION_HLEN + PBUF_LINK_HLEN;
00268     break;
00269   case PBUF_RAW_TX:
00270     /* add room for encapsulating link layer headers (e.g. 802.11) */
00271     offset = PBUF_LINK_ENCAPSULATION_HLEN;
00272     break;
00273   case PBUF_RAW:
00274     /* no offset (e.g. RX buffers or chain successors) */
00275     offset = 0;
00276     break;
00277   default:
00278     LWIP_ASSERT("pbuf_alloc: bad pbuf layer", 0);
00279     return NULL;
00280   }
00281 
00282   switch (type) {
00283   case PBUF_POOL:
00284     /* allocate head of pbuf chain into p */
00285     p = (struct pbuf *)memp_malloc(MEMP_PBUF_POOL);
00286     LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_alloc: allocated pbuf %p\n", (void *)p));
00287     if (p == NULL) {
00288       PBUF_POOL_IS_EMPTY();
00289       return NULL;
00290     }
00291     p->type = type;
00292     p->next = NULL;
00293 
00294     /* make the payload pointer point 'offset' bytes into pbuf data memory */
00295     p->payload = LWIP_MEM_ALIGN((void *)((u8_t *)p + (SIZEOF_STRUCT_PBUF + offset)));
00296     LWIP_ASSERT("pbuf_alloc: pbuf p->payload properly aligned",
00297             ((mem_ptr_t)p->payload % MEM_ALIGNMENT) == 0);
00298     /* the total length of the pbuf chain is the requested size */
00299     p->tot_len = length;
00300     /* set the length of the first pbuf in the chain */
00301     p->len = LWIP_MIN(length, PBUF_POOL_BUFSIZE_ALIGNED - LWIP_MEM_ALIGN_SIZE(offset));
00302     LWIP_ASSERT("check p->payload + p->len does not overflow pbuf",
00303                 ((u8_t*)p->payload + p->len <=
00304                  (u8_t*)p + SIZEOF_STRUCT_PBUF + PBUF_POOL_BUFSIZE_ALIGNED));
00305     LWIP_ASSERT("PBUF_POOL_BUFSIZE must be bigger than MEM_ALIGNMENT",
00306       (PBUF_POOL_BUFSIZE_ALIGNED - LWIP_MEM_ALIGN_SIZE(offset)) > 0 );
00307     /* set reference count (needed here in case we fail) */
00308     p->ref = 1;
00309 
00310     /* now allocate the tail of the pbuf chain */
00311 
00312     /* remember first pbuf for linkage in next iteration */
00313     r = p;
00314     /* remaining length to be allocated */
00315     rem_len = length - p->len;
00316     /* any remaining pbufs to be allocated? */
00317     while (rem_len > 0) {
00318       q = (struct pbuf *)memp_malloc(MEMP_PBUF_POOL);
00319       if (q == NULL) {
00320         PBUF_POOL_IS_EMPTY();
00321         /* free chain so far allocated */
00322         pbuf_free(p);
00323         /* bail out unsuccessfully */
00324         return NULL;
00325       }
00326       q->type = type;
00327       q->flags = 0;
00328       q->next = NULL;
00329       /* make previous pbuf point to this pbuf */
00330       r->next = q;
00331       /* set total length of this pbuf and next in chain */
00332       LWIP_ASSERT("rem_len < max_u16_t", rem_len < 0xffff);
00333       q->tot_len = (u16_t)rem_len;
00334       /* this pbuf length is pool size, unless smaller sized tail */
00335       q->len = LWIP_MIN((u16_t)rem_len, PBUF_POOL_BUFSIZE_ALIGNED);
00336       q->payload = (void *)((u8_t *)q + SIZEOF_STRUCT_PBUF);
00337       LWIP_ASSERT("pbuf_alloc: pbuf q->payload properly aligned",
00338               ((mem_ptr_t)q->payload % MEM_ALIGNMENT) == 0);
00339       LWIP_ASSERT("check p->payload + p->len does not overflow pbuf",
00340                   ((u8_t*)p->payload + p->len <=
00341                    (u8_t*)p + SIZEOF_STRUCT_PBUF + PBUF_POOL_BUFSIZE_ALIGNED));
00342       q->ref = 1;
00343       /* calculate remaining length to be allocated */
00344       rem_len -= q->len;
00345       /* remember this pbuf for linkage in next iteration */
00346       r = q;
00347     }
00348     /* end of chain */
00349     /*r->next = NULL;*/
00350 
00351     break;
00352   case PBUF_RAM:
00353     {
00354       mem_size_t alloc_len = LWIP_MEM_ALIGN_SIZE(SIZEOF_STRUCT_PBUF + offset) + LWIP_MEM_ALIGN_SIZE(length);
00355       
00356       /* bug #50040: Check for integer overflow when calculating alloc_len */
00357       if (alloc_len < LWIP_MEM_ALIGN_SIZE(length)) {
00358         return NULL;
00359       }
00360     
00361       /* If pbuf is to be allocated in RAM, allocate memory for it. */
00362       p = (struct pbuf*)mem_malloc(alloc_len);
00363     }
00364 
00365     if (p == NULL) {
00366       return NULL;
00367     }
00368     /* Set up internal structure of the pbuf. */
00369     p->payload = LWIP_MEM_ALIGN((void *)((u8_t *)p + SIZEOF_STRUCT_PBUF + offset));
00370     p->len = p->tot_len = length;
00371     p->next = NULL;
00372     p->type = type;
00373 
00374     LWIP_ASSERT("pbuf_alloc: pbuf->payload properly aligned",
00375            ((mem_ptr_t)p->payload % MEM_ALIGNMENT) == 0);
00376     break;
00377   /* pbuf references existing (non-volatile static constant) ROM payload? */
00378   case PBUF_ROM:
00379   /* pbuf references existing (externally allocated) RAM payload? */
00380   case PBUF_REF:
00381     /* only allocate memory for the pbuf structure */
00382     p = (struct pbuf *)memp_malloc(MEMP_PBUF);
00383     if (p == NULL) {
00384       LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
00385                   ("pbuf_alloc: Could not allocate MEMP_PBUF for PBUF_%s.\n",
00386                   (type == PBUF_ROM) ? "ROM" : "REF"));
00387       return NULL;
00388     }
00389     /* caller must set this field properly, afterwards */
00390     p->payload = NULL;
00391     p->len = p->tot_len = length;
00392     p->next = NULL;
00393     p->type = type;
00394     break;
00395   default:
00396     LWIP_ASSERT("pbuf_alloc: erroneous type", 0);
00397     return NULL;
00398   }
00399   /* set reference count */
00400   p->ref = 1;
00401   /* set flags */
00402   p->flags = 0;
00403   LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_alloc(length=%"U16_F") == %p\n", length, (void *)p));
00404   return p;
00405 }
00406 
00407 #if LWIP_SUPPORT_CUSTOM_PBUF
00408 /**
00409  * @ingroup pbuf
00410  * Initialize a custom pbuf (already allocated).
00411  *
00412  * @param l flag to define header size
00413  * @param length size of the pbuf's payload
00414  * @param type type of the pbuf (only used to treat the pbuf accordingly, as
00415  *        this function allocates no memory)
00416  * @param p pointer to the custom pbuf to initialize (already allocated)
00417  * @param payload_mem pointer to the buffer that is used for payload and headers,
00418  *        must be at least big enough to hold 'length' plus the header size,
00419  *        may be NULL if set later.
00420  *        ATTENTION: The caller is responsible for correct alignment of this buffer!!
00421  * @param payload_mem_len the size of the 'payload_mem' buffer, must be at least
00422  *        big enough to hold 'length' plus the header size
00423  */
00424 struct pbuf*
00425 pbuf_alloced_custom(pbuf_layer l, u16_t length, pbuf_type type, struct pbuf_custom *p,
00426                     void *payload_mem, u16_t payload_mem_len)
00427 {
00428   u16_t offset;
00429   LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_alloced_custom(length=%"U16_F")\n", length));
00430 
00431   /* determine header offset */
00432   switch (l) {
00433   case PBUF_TRANSPORT:
00434     /* add room for transport (often TCP) layer header */
00435     offset = PBUF_LINK_ENCAPSULATION_HLEN + PBUF_LINK_HLEN + PBUF_IP_HLEN + PBUF_TRANSPORT_HLEN;
00436     break;
00437   case PBUF_IP:
00438     /* add room for IP layer header */
00439     offset = PBUF_LINK_ENCAPSULATION_HLEN + PBUF_LINK_HLEN + PBUF_IP_HLEN;
00440     break;
00441   case PBUF_LINK:
00442     /* add room for link layer header */
00443     offset = PBUF_LINK_ENCAPSULATION_HLEN + PBUF_LINK_HLEN;
00444     break;
00445   case PBUF_RAW_TX:
00446     /* add room for encapsulating link layer headers (e.g. 802.11) */
00447     offset = PBUF_LINK_ENCAPSULATION_HLEN;
00448     break;
00449   case PBUF_RAW:
00450     offset = 0;
00451     break;
00452   default:
00453     LWIP_ASSERT("pbuf_alloced_custom: bad pbuf layer", 0);
00454     return NULL;
00455   }
00456 
00457   if (LWIP_MEM_ALIGN_SIZE(offset) + length > payload_mem_len) {
00458     LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_LEVEL_WARNING, ("pbuf_alloced_custom(length=%"U16_F") buffer too short\n", length));
00459     return NULL;
00460   }
00461 
00462   p->pbuf.next = NULL;
00463   if (payload_mem != NULL) {
00464     p->pbuf.payload = (u8_t *)payload_mem + LWIP_MEM_ALIGN_SIZE(offset);
00465   } else {
00466     p->pbuf.payload = NULL;
00467   }
00468   p->pbuf.flags = PBUF_FLAG_IS_CUSTOM;
00469   p->pbuf.len = p->pbuf.tot_len = length;
00470   p->pbuf.type = type;
00471   p->pbuf.ref = 1;
00472   return &p->pbuf;
00473 }
00474 #endif /* LWIP_SUPPORT_CUSTOM_PBUF */
00475 
00476 /**
00477  * @ingroup pbuf
00478  * Shrink a pbuf chain to a desired length.
00479  *
00480  * @param p pbuf to shrink.
00481  * @param new_len desired new length of pbuf chain
00482  *
00483  * Depending on the desired length, the first few pbufs in a chain might
00484  * be skipped and left unchanged. The new last pbuf in the chain will be
00485  * resized, and any remaining pbufs will be freed.
00486  *
00487  * @note If the pbuf is ROM/REF, only the ->tot_len and ->len fields are adjusted.
00488  * @note May not be called on a packet queue.
00489  *
00490  * @note Despite its name, pbuf_realloc cannot grow the size of a pbuf (chain).
00491  */
00492 void
00493 pbuf_realloc(struct pbuf *p, u16_t new_len)
00494 {
00495   struct pbuf *q;
00496   u16_t rem_len; /* remaining length */
00497   s32_t grow;
00498 
00499   LWIP_ASSERT("pbuf_realloc: p != NULL", p != NULL);
00500   LWIP_ASSERT("pbuf_realloc: sane p->type", p->type == PBUF_POOL ||
00501               p->type == PBUF_ROM ||
00502               p->type == PBUF_RAM ||
00503               p->type == PBUF_REF);
00504 
00505   /* desired length larger than current length? */
00506   if (new_len >= p->tot_len) {
00507     /* enlarging not yet supported */
00508     return;
00509   }
00510 
00511   /* the pbuf chain grows by (new_len - p->tot_len) bytes
00512    * (which may be negative in case of shrinking) */
00513   grow = new_len - p->tot_len;
00514 
00515   /* first, step over any pbufs that should remain in the chain */
00516   rem_len = new_len;
00517   q = p;
00518   /* should this pbuf be kept? */
00519   while (rem_len > q->len) {
00520     /* decrease remaining length by pbuf length */
00521     rem_len -= q->len;
00522     /* decrease total length indicator */
00523     LWIP_ASSERT("grow < max_u16_t", grow < 0xffff);
00524     q->tot_len += (u16_t)grow;
00525     /* proceed to next pbuf in chain */
00526     q = q->next;
00527     LWIP_ASSERT("pbuf_realloc: q != NULL", q != NULL);
00528   }
00529   /* we have now reached the new last pbuf (in q) */
00530   /* rem_len == desired length for pbuf q */
00531 
00532   /* shrink allocated memory for PBUF_RAM */
00533   /* (other types merely adjust their length fields */
00534   if ((q->type == PBUF_RAM) && (rem_len != q->len)
00535 #if LWIP_SUPPORT_CUSTOM_PBUF
00536       && ((q->flags & PBUF_FLAG_IS_CUSTOM) == 0)
00537 #endif /* LWIP_SUPPORT_CUSTOM_PBUF */
00538      ) {
00539     /* reallocate and adjust the length of the pbuf that will be split */
00540     q = (struct pbuf *)mem_trim(q, (u16_t)((u8_t *)q->payload - (u8_t *)q) + rem_len);
00541     LWIP_ASSERT("mem_trim returned q == NULL", q != NULL);
00542   }
00543   /* adjust length fields for new last pbuf */
00544   q->len = rem_len;
00545   q->tot_len = q->len;
00546 
00547   /* any remaining pbufs in chain? */
00548   if (q->next != NULL) {
00549     /* free remaining pbufs in chain */
00550     pbuf_free(q->next);
00551   }
00552   /* q is last packet in chain */
00553   q->next = NULL;
00554 
00555 }
00556 
00557 /**
00558  * Adjusts the payload pointer to hide or reveal headers in the payload.
00559  * @see pbuf_header.
00560  *
00561  * @param p pbuf to change the header size.
00562  * @param header_size_increment Number of bytes to increment header size.
00563  * @param force Allow 'header_size_increment > 0' for PBUF_REF/PBUF_ROM types
00564  *
00565  * @return non-zero on failure, zero on success.
00566  *
00567  */
00568 static u8_t
00569 pbuf_header_impl(struct pbuf *p, s16_t header_size_increment, u8_t force)
00570 {
00571   u16_t type;
00572   void *payload;
00573   u16_t increment_magnitude;
00574 
00575   LWIP_ASSERT("p != NULL", p != NULL);
00576   if ((header_size_increment == 0) || (p == NULL)) {
00577     return 0;
00578   }
00579 
00580   if (header_size_increment < 0) {
00581     increment_magnitude = (u16_t)-header_size_increment;
00582     /* Check that we aren't going to move off the end of the pbuf */
00583     LWIP_ERROR("increment_magnitude <= p->len", (increment_magnitude <= p->len), return 1;);
00584   } else {
00585     increment_magnitude = (u16_t)header_size_increment;
00586 #if 0
00587     /* Can't assert these as some callers speculatively call
00588          pbuf_header() to see if it's OK.  Will return 1 below instead. */
00589     /* Check that we've got the correct type of pbuf to work with */
00590     LWIP_ASSERT("p->type == PBUF_RAM || p->type == PBUF_POOL",
00591                 p->type == PBUF_RAM || p->type == PBUF_POOL);
00592     /* Check that we aren't going to move off the beginning of the pbuf */
00593     LWIP_ASSERT("p->payload - increment_magnitude >= p + SIZEOF_STRUCT_PBUF",
00594                 (u8_t *)p->payload - increment_magnitude >= (u8_t *)p + SIZEOF_STRUCT_PBUF);
00595 #endif
00596   }
00597 
00598   type = p->type;
00599   /* remember current payload pointer */
00600   payload = p->payload;
00601 
00602   /* pbuf types containing payloads? */
00603   if (type == PBUF_RAM || type == PBUF_POOL) {
00604     /* set new payload pointer */
00605     p->payload = (u8_t *)p->payload - header_size_increment;
00606     /* boundary check fails? */
00607     if ((u8_t *)p->payload < (u8_t *)p + SIZEOF_STRUCT_PBUF) {
00608       LWIP_DEBUGF( PBUF_DEBUG | LWIP_DBG_TRACE,
00609         ("pbuf_header: failed as %p < %p (not enough space for new header size)\n",
00610         (void *)p->payload, (void *)((u8_t *)p + SIZEOF_STRUCT_PBUF)));
00611       /* restore old payload pointer */
00612       p->payload = payload;
00613       /* bail out unsuccessfully */
00614       return 1;
00615     }
00616   /* pbuf types referring to external payloads? */
00617   } else if (type == PBUF_REF || type == PBUF_ROM) {
00618     /* hide a header in the payload? */
00619     if ((header_size_increment < 0) && (increment_magnitude <= p->len)) {
00620       /* increase payload pointer */
00621       p->payload = (u8_t *)p->payload - header_size_increment;
00622     } else if ((header_size_increment > 0) && force) {
00623       p->payload = (u8_t *)p->payload - header_size_increment;
00624     } else {
00625       /* cannot expand payload to front (yet!)
00626        * bail out unsuccessfully */
00627       return 1;
00628     }
00629   } else {
00630     /* Unknown type */
00631     LWIP_ASSERT("bad pbuf type", 0);
00632     return 1;
00633   }
00634   /* modify pbuf length fields */
00635   p->len += header_size_increment;
00636   p->tot_len += header_size_increment;
00637 
00638   LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_header: old %p new %p (%"S16_F")\n",
00639     (void *)payload, (void *)p->payload, header_size_increment));
00640 
00641   return 0;
00642 }
00643 
00644 /**
00645  * Adjusts the payload pointer to hide or reveal headers in the payload.
00646  *
00647  * Adjusts the ->payload pointer so that space for a header
00648  * (dis)appears in the pbuf payload.
00649  *
00650  * The ->payload, ->tot_len and ->len fields are adjusted.
00651  *
00652  * @param p pbuf to change the header size.
00653  * @param header_size_increment Number of bytes to increment header size which
00654  * increases the size of the pbuf. New space is on the front.
00655  * (Using a negative value decreases the header size.)
00656  * If hdr_size_inc is 0, this function does nothing and returns successful.
00657  *
00658  * PBUF_ROM and PBUF_REF type buffers cannot have their sizes increased, so
00659  * the call will fail. A check is made that the increase in header size does
00660  * not move the payload pointer in front of the start of the buffer.
00661  * @return non-zero on failure, zero on success.
00662  *
00663  */
00664 u8_t
00665 pbuf_header(struct pbuf *p, s16_t header_size_increment)
00666 {
00667    return pbuf_header_impl(p, header_size_increment, 0);
00668 }
00669 
00670 /**
00671  * Same as pbuf_header but does not check if 'header_size > 0' is allowed.
00672  * This is used internally only, to allow PBUF_REF for RX.
00673  */
00674 u8_t
00675 pbuf_header_force(struct pbuf *p, s16_t header_size_increment)
00676 {
00677    return pbuf_header_impl(p, header_size_increment, 1);
00678 }
00679 
00680 /**
00681  * @ingroup pbuf
00682  * Dereference a pbuf chain or queue and deallocate any no-longer-used
00683  * pbufs at the head of this chain or queue.
00684  *
00685  * Decrements the pbuf reference count. If it reaches zero, the pbuf is
00686  * deallocated.
00687  *
00688  * For a pbuf chain, this is repeated for each pbuf in the chain,
00689  * up to the first pbuf which has a non-zero reference count after
00690  * decrementing. So, when all reference counts are one, the whole
00691  * chain is free'd.
00692  *
00693  * @param p The pbuf (chain) to be dereferenced.
00694  *
00695  * @return the number of pbufs that were de-allocated
00696  * from the head of the chain.
00697  *
00698  * @note MUST NOT be called on a packet queue (Not verified to work yet).
00699  * @note the reference counter of a pbuf equals the number of pointers
00700  * that refer to the pbuf (or into the pbuf).
00701  *
00702  * @internal examples:
00703  *
00704  * Assuming existing chains a->b->c with the following reference
00705  * counts, calling pbuf_free(a) results in:
00706  *
00707  * 1->2->3 becomes ...1->3
00708  * 3->3->3 becomes 2->3->3
00709  * 1->1->2 becomes ......1
00710  * 2->1->1 becomes 1->1->1
00711  * 1->1->1 becomes .......
00712  *
00713  */
00714 u8_t
00715 pbuf_free(struct pbuf *p)
00716 {
00717   u16_t type;
00718   struct pbuf *q;
00719   u8_t count;
00720 
00721   if (p == NULL) {
00722     LWIP_ASSERT("p != NULL", p != NULL);
00723     /* if assertions are disabled, proceed with debug output */
00724     LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
00725       ("pbuf_free(p == NULL) was called.\n"));
00726     return 0;
00727   }
00728   LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_free(%p)\n", (void *)p));
00729 
00730   PERF_START;
00731 
00732   LWIP_ASSERT("pbuf_free: sane type",
00733     p->type == PBUF_RAM || p->type == PBUF_ROM ||
00734     p->type == PBUF_REF || p->type == PBUF_POOL);
00735 
00736   count = 0;
00737   /* de-allocate all consecutive pbufs from the head of the chain that
00738    * obtain a zero reference count after decrementing*/
00739   while (p != NULL) {
00740     u16_t ref;
00741     SYS_ARCH_DECL_PROTECT(old_level);
00742     /* Since decrementing ref cannot be guaranteed to be a single machine operation
00743      * we must protect it. We put the new ref into a local variable to prevent
00744      * further protection. */
00745     SYS_ARCH_PROTECT(old_level);
00746     /* all pbufs in a chain are referenced at least once */
00747     LWIP_ASSERT("pbuf_free: p->ref > 0", p->ref > 0);
00748     /* decrease reference count (number of pointers to pbuf) */
00749     ref = --(p->ref);
00750     SYS_ARCH_UNPROTECT(old_level);
00751     /* this pbuf is no longer referenced to? */
00752     if (ref == 0) {
00753       /* remember next pbuf in chain for next iteration */
00754       q = p->next;
00755       LWIP_DEBUGF( PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_free: deallocating %p\n", (void *)p));
00756       type = p->type;
00757 #if LWIP_SUPPORT_CUSTOM_PBUF
00758       /* is this a custom pbuf? */
00759       if ((p->flags & PBUF_FLAG_IS_CUSTOM) != 0) {
00760         struct pbuf_custom *pc = (struct pbuf_custom*)p;
00761         LWIP_ASSERT("pc->custom_free_function != NULL", pc->custom_free_function != NULL);
00762         pc->custom_free_function(p);
00763       } else
00764 #endif /* LWIP_SUPPORT_CUSTOM_PBUF */
00765       {
00766         /* is this a pbuf from the pool? */
00767         if (type == PBUF_POOL) {
00768           memp_free(MEMP_PBUF_POOL, p);
00769         /* is this a ROM or RAM referencing pbuf? */
00770         } else if (type == PBUF_ROM || type == PBUF_REF) {
00771           memp_free(MEMP_PBUF, p);
00772         /* type == PBUF_RAM */
00773         } else {
00774           mem_free(p);
00775         }
00776       }
00777       count++;
00778       /* proceed to next pbuf */
00779       p = q;
00780     /* p->ref > 0, this pbuf is still referenced to */
00781     /* (and so the remaining pbufs in chain as well) */
00782     } else {
00783       LWIP_DEBUGF( PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_free: %p has ref %"U16_F", ending here.\n", (void *)p, ref));
00784       /* stop walking through the chain */
00785       p = NULL;
00786     }
00787   }
00788   PERF_STOP("pbuf_free");
00789   /* return number of de-allocated pbufs */
00790   return count;
00791 }
00792 
00793 /**
00794  * Count number of pbufs in a chain
00795  *
00796  * @param p first pbuf of chain
00797  * @return the number of pbufs in a chain
00798  */
00799 u16_t
00800 pbuf_clen(const struct pbuf *p)
00801 {
00802   u16_t len;
00803 
00804   len = 0;
00805   while (p != NULL) {
00806     ++len;
00807     p = p->next;
00808   }
00809   return len;
00810 }
00811 
00812 /**
00813  * @ingroup pbuf
00814  * Increment the reference count of the pbuf.
00815  *
00816  * @param p pbuf to increase reference counter of
00817  *
00818  */
00819 void
00820 pbuf_ref(struct pbuf *p)
00821 {
00822   /* pbuf given? */
00823   if (p != NULL) {
00824     SYS_ARCH_INC(p->ref, 1);
00825     LWIP_ASSERT("pbuf ref overflow", p->ref > 0);
00826   }
00827 }
00828 
00829 /**
00830  * @ingroup pbuf
00831  * Concatenate two pbufs (each may be a pbuf chain) and take over
00832  * the caller's reference of the tail pbuf.
00833  *
00834  * @note The caller MAY NOT reference the tail pbuf afterwards.
00835  * Use pbuf_chain() for that purpose.
00836  *
00837  * @see pbuf_chain()
00838  */
00839 void
00840 pbuf_cat(struct pbuf *h, struct pbuf *t)
00841 {
00842   struct pbuf *p;
00843 
00844   LWIP_ERROR("(h != NULL) && (t != NULL) (programmer violates API)",
00845              ((h != NULL) && (t != NULL)), return;);
00846 
00847   /* proceed to last pbuf of chain */
00848   for (p = h; p->next != NULL; p = p->next) {
00849     /* add total length of second chain to all totals of first chain */
00850     p->tot_len += t->tot_len;
00851   }
00852   /* { p is last pbuf of first h chain, p->next == NULL } */
00853   LWIP_ASSERT("p->tot_len == p->len (of last pbuf in chain)", p->tot_len == p->len);
00854   LWIP_ASSERT("p->next == NULL", p->next == NULL);
00855   /* add total length of second chain to last pbuf total of first chain */
00856   p->tot_len += t->tot_len;
00857   /* chain last pbuf of head (p) with first of tail (t) */
00858   p->next = t;
00859   /* p->next now references t, but the caller will drop its reference to t,
00860    * so netto there is no change to the reference count of t.
00861    */
00862 }
00863 
00864 /**
00865  * @ingroup pbuf
00866  * Chain two pbufs (or pbuf chains) together.
00867  *
00868  * The caller MUST call pbuf_free(t) once it has stopped
00869  * using it. Use pbuf_cat() instead if you no longer use t.
00870  *
00871  * @param h head pbuf (chain)
00872  * @param t tail pbuf (chain)
00873  * @note The pbufs MUST belong to the same packet.
00874  * @note MAY NOT be called on a packet queue.
00875  *
00876  * The ->tot_len fields of all pbufs of the head chain are adjusted.
00877  * The ->next field of the last pbuf of the head chain is adjusted.
00878  * The ->ref field of the first pbuf of the tail chain is adjusted.
00879  *
00880  */
00881 void
00882 pbuf_chain(struct pbuf *h, struct pbuf *t)
00883 {
00884   pbuf_cat(h, t);
00885   /* t is now referenced by h */
00886   pbuf_ref(t);
00887   LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_chain: %p references %p\n", (void *)h, (void *)t));
00888 }
00889 
00890 /**
00891  * Dechains the first pbuf from its succeeding pbufs in the chain.
00892  *
00893  * Makes p->tot_len field equal to p->len.
00894  * @param p pbuf to dechain
00895  * @return remainder of the pbuf chain, or NULL if it was de-allocated.
00896  * @note May not be called on a packet queue.
00897  */
00898 struct pbuf *
00899 pbuf_dechain(struct pbuf *p)
00900 {
00901   struct pbuf *q;
00902   u8_t tail_gone = 1;
00903   /* tail */
00904   q = p->next;
00905   /* pbuf has successor in chain? */
00906   if (q != NULL) {
00907     /* assert tot_len invariant: (p->tot_len == p->len + (p->next? p->next->tot_len: 0) */
00908     LWIP_ASSERT("p->tot_len == p->len + q->tot_len", q->tot_len == p->tot_len - p->len);
00909     /* enforce invariant if assertion is disabled */
00910     q->tot_len = p->tot_len - p->len;
00911     /* decouple pbuf from remainder */
00912     p->next = NULL;
00913     /* total length of pbuf p is its own length only */
00914     p->tot_len = p->len;
00915     /* q is no longer referenced by p, free it */
00916     LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_dechain: unreferencing %p\n", (void *)q));
00917     tail_gone = pbuf_free(q);
00918     if (tail_gone > 0) {
00919       LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE,
00920                   ("pbuf_dechain: deallocated %p (as it is no longer referenced)\n", (void *)q));
00921     }
00922     /* return remaining tail or NULL if deallocated */
00923   }
00924   /* assert tot_len invariant: (p->tot_len == p->len + (p->next? p->next->tot_len: 0) */
00925   LWIP_ASSERT("p->tot_len == p->len", p->tot_len == p->len);
00926   return ((tail_gone > 0) ? NULL : q);
00927 }
00928 
00929 /**
00930  * @ingroup pbuf
00931  * Create PBUF_RAM copies of pbufs.
00932  *
00933  * Used to queue packets on behalf of the lwIP stack, such as
00934  * ARP based queueing.
00935  *
00936  * @note You MUST explicitly use p = pbuf_take(p);
00937  *
00938  * @note Only one packet is copied, no packet queue!
00939  *
00940  * @param p_to pbuf destination of the copy
00941  * @param p_from pbuf source of the copy
00942  *
00943  * @return ERR_OK if pbuf was copied
00944  *         ERR_ARG if one of the pbufs is NULL or p_to is not big
00945  *                 enough to hold p_from
00946  */
00947 err_t
00948 pbuf_copy(struct pbuf *p_to, const struct pbuf *p_from)
00949 {
00950   u16_t offset_to=0, offset_from=0, len;
00951 
00952   LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_copy(%p, %p)\n",
00953     (const void*)p_to, (const void*)p_from));
00954 
00955   /* is the target big enough to hold the source? */
00956   LWIP_ERROR("pbuf_copy: target not big enough to hold source", ((p_to != NULL) &&
00957              (p_from != NULL) && (p_to->tot_len >= p_from->tot_len)), return ERR_ARG;);
00958 
00959   /* iterate through pbuf chain */
00960   do
00961   {
00962     /* copy one part of the original chain */
00963     if ((p_to->len - offset_to) >= (p_from->len - offset_from)) {
00964       /* complete current p_from fits into current p_to */
00965       len = p_from->len - offset_from;
00966     } else {
00967       /* current p_from does not fit into current p_to */
00968       len = p_to->len - offset_to;
00969     }
00970     MEMCPY((u8_t*)p_to->payload + offset_to, (u8_t*)p_from->payload + offset_from, len);
00971     offset_to += len;
00972     offset_from += len;
00973     LWIP_ASSERT("offset_to <= p_to->len", offset_to <= p_to->len);
00974     LWIP_ASSERT("offset_from <= p_from->len", offset_from <= p_from->len);
00975     if (offset_from >= p_from->len) {
00976       /* on to next p_from (if any) */
00977       offset_from = 0;
00978       p_from = p_from->next;
00979     }
00980     if (offset_to == p_to->len) {
00981       /* on to next p_to (if any) */
00982       offset_to = 0;
00983       p_to = p_to->next;
00984       LWIP_ERROR("p_to != NULL", (p_to != NULL) || (p_from == NULL) , return ERR_ARG;);
00985     }
00986 
00987     if ((p_from != NULL) && (p_from->len == p_from->tot_len)) {
00988       /* don't copy more than one packet! */
00989       LWIP_ERROR("pbuf_copy() does not allow packet queues!",
00990                  (p_from->next == NULL), return ERR_VAL;);
00991     }
00992     if ((p_to != NULL) && (p_to->len == p_to->tot_len)) {
00993       /* don't copy more than one packet! */
00994       LWIP_ERROR("pbuf_copy() does not allow packet queues!",
00995                   (p_to->next == NULL), return ERR_VAL;);
00996     }
00997   } while (p_from);
00998   LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE, ("pbuf_copy: end of chain reached.\n"));
00999   return ERR_OK;
01000 }
01001 
01002 /**
01003  * @ingroup pbuf
01004  * Copy (part of) the contents of a packet buffer
01005  * to an application supplied buffer.
01006  *
01007  * @param buf the pbuf from which to copy data
01008  * @param dataptr the application supplied buffer
01009  * @param len length of data to copy (dataptr must be big enough). No more
01010  * than buf->tot_len will be copied, irrespective of len
01011  * @param offset offset into the packet buffer from where to begin copying len bytes
01012  * @return the number of bytes copied, or 0 on failure
01013  */
01014 u16_t
01015 pbuf_copy_partial(const struct pbuf *buf, void *dataptr, u16_t len, u16_t offset)
01016 {
01017   const struct pbuf *p;
01018   u16_t left;
01019   u16_t buf_copy_len;
01020   u16_t copied_total = 0;
01021 
01022   LWIP_ERROR("pbuf_copy_partial: invalid buf", (buf != NULL), return 0;);
01023   LWIP_ERROR("pbuf_copy_partial: invalid dataptr", (dataptr != NULL), return 0;);
01024 
01025   left = 0;
01026 
01027   if ((buf == NULL) || (dataptr == NULL)) {
01028     return 0;
01029   }
01030 
01031   /* Note some systems use byte copy if dataptr or one of the pbuf payload pointers are unaligned. */
01032   for (p = buf; len != 0 && p != NULL; p = p->next) {
01033     if ((offset != 0) && (offset >= p->len)) {
01034       /* don't copy from this buffer -> on to the next */
01035       offset -= p->len;
01036     } else {
01037       /* copy from this buffer. maybe only partially. */
01038       buf_copy_len = p->len - offset;
01039       if (buf_copy_len > len) {
01040         buf_copy_len = len;
01041       }
01042       /* copy the necessary parts of the buffer */
01043       MEMCPY(&((char*)dataptr)[left], &((char*)p->payload)[offset], buf_copy_len);
01044       copied_total += buf_copy_len;
01045       left += buf_copy_len;
01046       len -= buf_copy_len;
01047       offset = 0;
01048     }
01049   }
01050   return copied_total;
01051 }
01052 
01053 #if LWIP_TCP && TCP_QUEUE_OOSEQ && LWIP_WND_SCALE
01054 /**
01055  * This method modifies a 'pbuf chain', so that its total length is
01056  * smaller than 64K. The remainder of the original pbuf chain is stored
01057  * in *rest.
01058  * This function never creates new pbufs, but splits an existing chain
01059  * in two parts. The tot_len of the modified packet queue will likely be
01060  * smaller than 64K.
01061  * 'packet queues' are not supported by this function.
01062  *
01063  * @param p the pbuf queue to be split
01064  * @param rest pointer to store the remainder (after the first 64K)
01065  */
01066 void pbuf_split_64k(struct pbuf *p, struct pbuf **rest)
01067 {
01068   *rest = NULL;
01069   if ((p != NULL) && (p->next != NULL)) {
01070     u16_t tot_len_front = p->len;
01071     struct pbuf *i = p;
01072     struct pbuf *r = p->next;
01073 
01074     /* continue until the total length (summed up as u16_t) overflows */
01075     while ((r != NULL) && ((u16_t)(tot_len_front + r->len) > tot_len_front)) {
01076       tot_len_front += r->len;
01077       i = r;
01078       r = r->next;
01079     }
01080     /* i now points to last packet of the first segment. Set next
01081        pointer to NULL */
01082     i->next = NULL;
01083 
01084     if (r != NULL) {
01085       /* Update the tot_len field in the first part */
01086       for (i = p; i != NULL; i = i->next) {
01087         i->tot_len -= r->tot_len;
01088         LWIP_ASSERT("tot_len/len mismatch in last pbuf",
01089                     (i->next != NULL) || (i->tot_len == i->len));
01090       }
01091       if (p->flags & PBUF_FLAG_TCP_FIN) {
01092         r->flags |= PBUF_FLAG_TCP_FIN;
01093       }
01094 
01095       /* tot_len field in rest does not need modifications */
01096       /* reference counters do not need modifications */
01097       *rest = r;
01098     }
01099   }
01100 }
01101 #endif /* LWIP_TCP && TCP_QUEUE_OOSEQ && LWIP_WND_SCALE */
01102 
01103 /* Actual implementation of pbuf_skip() but returning const pointer... */
01104 static const struct pbuf*
01105 pbuf_skip_const(const struct pbuf* in, u16_t in_offset, u16_t* out_offset)
01106 {
01107   u16_t offset_left = in_offset;
01108   const struct pbuf* q = in;
01109 
01110   /* get the correct pbuf */
01111   while ((q != NULL) && (q->len <= offset_left)) {
01112     offset_left -= q->len;
01113     q = q->next;
01114   }
01115   if (out_offset != NULL) {
01116     *out_offset = offset_left;
01117   }
01118   return q;
01119 }
01120 
01121 /**
01122  * @ingroup pbuf
01123  * Skip a number of bytes at the start of a pbuf
01124  *
01125  * @param in input pbuf
01126  * @param in_offset offset to skip
01127  * @param out_offset resulting offset in the returned pbuf
01128  * @return the pbuf in the queue where the offset is
01129  */
01130 struct pbuf*
01131 pbuf_skip(struct pbuf* in, u16_t in_offset, u16_t* out_offset)
01132 {
01133   const struct pbuf* out = pbuf_skip_const(in, in_offset, out_offset);
01134   return LWIP_CONST_CAST(struct pbuf*, out);
01135 }
01136 
01137 /**
01138  * @ingroup pbuf
01139  * Copy application supplied data into a pbuf.
01140  * This function can only be used to copy the equivalent of buf->tot_len data.
01141  *
01142  * @param buf pbuf to fill with data
01143  * @param dataptr application supplied data buffer
01144  * @param len length of the application supplied data buffer
01145  *
01146  * @return ERR_OK if successful, ERR_MEM if the pbuf is not big enough
01147  */
01148 err_t
01149 pbuf_take(struct pbuf *buf, const void *dataptr, u16_t len)
01150 {
01151   struct pbuf *p;
01152   u16_t buf_copy_len;
01153   u16_t total_copy_len = len;
01154   u16_t copied_total = 0;
01155 
01156   LWIP_ERROR("pbuf_take: invalid buf", (buf != NULL), return ERR_ARG;);
01157   LWIP_ERROR("pbuf_take: invalid dataptr", (dataptr != NULL), return ERR_ARG;);
01158   LWIP_ERROR("pbuf_take: buf not large enough", (buf->tot_len >= len), return ERR_MEM;);
01159 
01160   if ((buf == NULL) || (dataptr == NULL) || (buf->tot_len < len)) {
01161     return ERR_ARG;
01162   }
01163 
01164   /* Note some systems use byte copy if dataptr or one of the pbuf payload pointers are unaligned. */
01165   for (p = buf; total_copy_len != 0; p = p->next) {
01166     LWIP_ASSERT("pbuf_take: invalid pbuf", p != NULL);
01167     buf_copy_len = total_copy_len;
01168     if (buf_copy_len > p->len) {
01169       /* this pbuf cannot hold all remaining data */
01170       buf_copy_len = p->len;
01171     }
01172     /* copy the necessary parts of the buffer */
01173     MEMCPY(p->payload, &((const char*)dataptr)[copied_total], buf_copy_len);
01174     total_copy_len -= buf_copy_len;
01175     copied_total += buf_copy_len;
01176   }
01177   LWIP_ASSERT("did not copy all data", total_copy_len == 0 && copied_total == len);
01178   return ERR_OK;
01179 }
01180 
01181 /**
01182  * @ingroup pbuf
01183  * Same as pbuf_take() but puts data at an offset
01184  *
01185  * @param buf pbuf to fill with data
01186  * @param dataptr application supplied data buffer
01187  * @param len length of the application supplied data buffer
01188  * @param offset offset in pbuf where to copy dataptr to
01189  *
01190  * @return ERR_OK if successful, ERR_MEM if the pbuf is not big enough
01191  */
01192 err_t
01193 pbuf_take_at(struct pbuf *buf, const void *dataptr, u16_t len, u16_t offset)
01194 {
01195   u16_t target_offset;
01196   struct pbuf* q = pbuf_skip(buf, offset, &target_offset);
01197 
01198   /* return requested data if pbuf is OK */
01199   if ((q != NULL) && (q->tot_len >= target_offset + len)) {
01200     u16_t remaining_len = len;
01201     const u8_t* src_ptr = (const u8_t*)dataptr;
01202     /* copy the part that goes into the first pbuf */
01203     u16_t first_copy_len = LWIP_MIN(q->len - target_offset, len);
01204     MEMCPY(((u8_t*)q->payload) + target_offset, dataptr, first_copy_len);
01205     remaining_len -= first_copy_len;
01206     src_ptr += first_copy_len;
01207     if (remaining_len > 0) {
01208       return pbuf_take(q->next, src_ptr, remaining_len);
01209     }
01210     return ERR_OK;
01211   }
01212   return ERR_MEM;
01213 }
01214 
01215 /**
01216  * @ingroup pbuf
01217  * Creates a single pbuf out of a queue of pbufs.
01218  *
01219  * @remark: Either the source pbuf 'p' is freed by this function or the original
01220  *          pbuf 'p' is returned, therefore the caller has to check the result!
01221  *
01222  * @param p the source pbuf
01223  * @param layer pbuf_layer of the new pbuf
01224  *
01225  * @return a new, single pbuf (p->next is NULL)
01226  *         or the old pbuf if allocation fails
01227  */
01228 struct pbuf*
01229 pbuf_coalesce(struct pbuf *p, pbuf_layer layer)
01230 {
01231   struct pbuf *q;
01232   err_t err;
01233   if (p->next == NULL) {
01234     return p;
01235   }
01236   q = pbuf_alloc(layer, p->tot_len, PBUF_RAM);
01237   if (q == NULL) {
01238     /* @todo: what do we do now? */
01239     return p;
01240   }
01241   err = pbuf_copy(q, p);
01242   LWIP_UNUSED_ARG(err); /* in case of LWIP_NOASSERT */
01243   LWIP_ASSERT("pbuf_copy failed", err == ERR_OK);
01244   pbuf_free(p);
01245   return q;
01246 }
01247 
01248 #if LWIP_CHECKSUM_ON_COPY
01249 /**
01250  * Copies data into a single pbuf (*not* into a pbuf queue!) and updates
01251  * the checksum while copying
01252  *
01253  * @param p the pbuf to copy data into
01254  * @param start_offset offset of p->payload where to copy the data to
01255  * @param dataptr data to copy into the pbuf
01256  * @param len length of data to copy into the pbuf
01257  * @param chksum pointer to the checksum which is updated
01258  * @return ERR_OK if successful, another error if the data does not fit
01259  *         within the (first) pbuf (no pbuf queues!)
01260  */
01261 err_t
01262 pbuf_fill_chksum(struct pbuf *p, u16_t start_offset, const void *dataptr,
01263                  u16_t len, u16_t *chksum)
01264 {
01265   u32_t acc;
01266   u16_t copy_chksum;
01267   char *dst_ptr;
01268   LWIP_ASSERT("p != NULL", p != NULL);
01269   LWIP_ASSERT("dataptr != NULL", dataptr != NULL);
01270   LWIP_ASSERT("chksum != NULL", chksum != NULL);
01271   LWIP_ASSERT("len != 0", len != 0);
01272 
01273   if ((start_offset >= p->len) || (start_offset + len > p->len)) {
01274     return ERR_ARG;
01275   }
01276 
01277   dst_ptr = ((char*)p->payload) + start_offset;
01278   copy_chksum = LWIP_CHKSUM_COPY(dst_ptr, dataptr, len);
01279   if ((start_offset & 1) != 0) {
01280     copy_chksum = SWAP_BYTES_IN_WORD(copy_chksum);
01281   }
01282   acc = *chksum;
01283   acc += copy_chksum;
01284   *chksum = FOLD_U32T(acc);
01285   return ERR_OK;
01286 }
01287 #endif /* LWIP_CHECKSUM_ON_COPY */
01288 
01289 /**
01290  * @ingroup pbuf
01291  * Get one byte from the specified position in a pbuf
01292  * WARNING: returns zero for offset >= p->tot_len
01293  *
01294  * @param p pbuf to parse
01295  * @param offset offset into p of the byte to return
01296  * @return byte at an offset into p OR ZERO IF 'offset' >= p->tot_len
01297  */
01298 u8_t
01299 pbuf_get_at(const struct pbuf* p, u16_t offset)
01300 {
01301   int ret = pbuf_try_get_at(p, offset);
01302   if (ret >= 0) {
01303     return (u8_t)ret;
01304   }
01305   return 0;
01306 }
01307 
01308 /**
01309  * @ingroup pbuf
01310  * Get one byte from the specified position in a pbuf
01311  *
01312  * @param p pbuf to parse
01313  * @param offset offset into p of the byte to return
01314  * @return byte at an offset into p [0..0xFF] OR negative if 'offset' >= p->tot_len
01315  */
01316 int
01317 pbuf_try_get_at(const struct pbuf* p, u16_t offset)
01318 {
01319   u16_t q_idx;
01320   const struct pbuf* q = pbuf_skip_const(p, offset, &q_idx);
01321 
01322   /* return requested data if pbuf is OK */
01323   if ((q != NULL) && (q->len > q_idx)) {
01324     return ((u8_t*)q->payload)[q_idx];
01325   }
01326   return -1;
01327 }
01328 
01329 /**
01330  * @ingroup pbuf
01331  * Put one byte to the specified position in a pbuf
01332  * WARNING: silently ignores offset >= p->tot_len
01333  *
01334  * @param p pbuf to fill
01335  * @param offset offset into p of the byte to write
01336  * @param data byte to write at an offset into p
01337  */
01338 void
01339 pbuf_put_at(struct pbuf* p, u16_t offset, u8_t data)
01340 {
01341   u16_t q_idx;
01342   struct pbuf* q = pbuf_skip(p, offset, &q_idx);
01343 
01344   /* write requested data if pbuf is OK */
01345   if ((q != NULL) && (q->len > q_idx)) {
01346     ((u8_t*)q->payload)[q_idx] = data;
01347   }
01348 }
01349 
01350 /**
01351  * @ingroup pbuf
01352  * Compare pbuf contents at specified offset with memory s2, both of length n
01353  *
01354  * @param p pbuf to compare
01355  * @param offset offset into p at which to start comparing
01356  * @param s2 buffer to compare
01357  * @param n length of buffer to compare
01358  * @return zero if equal, nonzero otherwise
01359  *         (0xffff if p is too short, diffoffset+1 otherwise)
01360  */
01361 u16_t
01362 pbuf_memcmp(const struct pbuf* p, u16_t offset, const void* s2, u16_t n)
01363 {
01364   u16_t start = offset;
01365   const struct pbuf* q = p;
01366   u16_t i;
01367  
01368   /* pbuf long enough to perform check? */
01369   if(p->tot_len < (offset + n)) {
01370     return 0xffff;
01371   }
01372  
01373   /* get the correct pbuf from chain. We know it succeeds because of p->tot_len check above. */
01374   while ((q != NULL) && (q->len <= start)) {
01375     start -= q->len;
01376     q = q->next;
01377   }
01378  
01379   /* return requested data if pbuf is OK */
01380   for (i = 0; i < n; i++) {
01381     /* We know pbuf_get_at() succeeds because of p->tot_len check above. */
01382     u8_t a = pbuf_get_at(q, start + i);
01383     u8_t b = ((const u8_t*)s2)[i];
01384     if (a != b) {
01385       return i+1;
01386     }
01387   }
01388   return 0;
01389 }
01390 
01391 /**
01392  * @ingroup pbuf
01393  * Find occurrence of mem (with length mem_len) in pbuf p, starting at offset
01394  * start_offset.
01395  *
01396  * @param p pbuf to search, maximum length is 0xFFFE since 0xFFFF is used as
01397  *        return value 'not found'
01398  * @param mem search for the contents of this buffer
01399  * @param mem_len length of 'mem'
01400  * @param start_offset offset into p at which to start searching
01401  * @return 0xFFFF if substr was not found in p or the index where it was found
01402  */
01403 u16_t
01404 pbuf_memfind(const struct pbuf* p, const void* mem, u16_t mem_len, u16_t start_offset)
01405 {
01406   u16_t i;
01407   u16_t max = p->tot_len - mem_len;
01408   if (p->tot_len >= mem_len + start_offset) {
01409     for (i = start_offset; i <= max; i++) {
01410       u16_t plus = pbuf_memcmp(p, i, mem, mem_len);
01411       if (plus == 0) {
01412         return i;
01413       }
01414     }
01415   }
01416   return 0xFFFF;
01417 }
01418 
01419 /**
01420  * Find occurrence of substr with length substr_len in pbuf p, start at offset
01421  * start_offset
01422  * WARNING: in contrast to strstr(), this one does not stop at the first \0 in
01423  * the pbuf/source string!
01424  *
01425  * @param p pbuf to search, maximum length is 0xFFFE since 0xFFFF is used as
01426  *        return value 'not found'
01427  * @param substr string to search for in p, maximum length is 0xFFFE
01428  * @return 0xFFFF if substr was not found in p or the index where it was found
01429  */
01430 u16_t
01431 pbuf_strstr(const struct pbuf* p, const char* substr)
01432 {
01433   size_t substr_len;
01434   if ((substr == NULL) || (substr[0] == 0) || (p->tot_len == 0xFFFF)) {
01435     return 0xFFFF;
01436   }
01437   substr_len = strlen(substr);
01438   if (substr_len >= 0xFFFF) {
01439     return 0xFFFF;
01440   }
01441   return pbuf_memfind(p, substr, (u16_t)substr_len, 0);
01442 }