lwip_netbuf.c

00001 /**
00002  * @file
00003  * Network buffer management
00004  *
00005  */
00006 
00007 /*
00008  * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
00009  * All rights reserved.
00010  *
00011  * Redistribution and use in source and binary forms, with or without modification,
00012  * are permitted provided that the following conditions are met:
00013  *
00014  * 1. Redistributions of source code must retain the above copyright notice,
00015  *    this list of conditions and the following disclaimer.
00016  * 2. Redistributions in binary form must reproduce the above copyright notice,
00017  *    this list of conditions and the following disclaimer in the documentation
00018  *    and/or other materials provided with the distribution.
00019  * 3. The name of the author may not be used to endorse or promote products
00020  *    derived from this software without specific prior written permission.
00021  *
00022  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
00023  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
00024  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
00025  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
00026  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
00027  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
00028  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
00029  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
00030  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
00031  * OF SUCH DAMAGE.
00032  *
00033  * This file is part of the lwIP TCP/IP stack.
00034  *
00035  * Author: Adam Dunkels <adam@sics.se>
00036  *
00037  */
00038 
00039 /**
00040  * @defgroup netbuf Network buffers
00041  * @ingroup netconn
00042  * Network buffer descriptor for @ref netconn. Based on @ref pbuf internally
00043  * to avoid copying data around.\n
00044  * Buffers must not be shared accross multiple threads, all functions except
00045  * netbuf_new() and netbuf_delete() are not thread-safe.
00046  */
00047 
00048 #include "lwip/opt.h"
00049 
00050 #if LWIP_NETCONN /* don't build if not configured for use in lwipopts.h */
00051 
00052 #include "lwip/netbuf.h"
00053 #include "lwip/memp.h"
00054 
00055 #include <string.h>
00056 
00057 /**
00058  * @ingroup netbuf
00059  * Create (allocate) and initialize a new netbuf.
00060  * The netbuf doesn't yet contain a packet buffer!
00061  *
00062  * @return a pointer to a new netbuf
00063  *         NULL on lack of memory
00064  */
00065 struct
00066 netbuf *netbuf_new(void)
00067 {
00068   struct netbuf *buf;
00069 
00070   buf = (struct netbuf *)memp_malloc(MEMP_NETBUF);
00071   if (buf != NULL) {
00072     buf->p = NULL;
00073     buf->ptr = NULL;
00074     ip_addr_set_zero(&buf->addr);
00075     buf->port = 0;
00076 #if LWIP_NETBUF_RECVINFO || LWIP_CHECKSUM_ON_COPY
00077 #if LWIP_CHECKSUM_ON_COPY
00078     buf->flags = 0;
00079 #endif /* LWIP_CHECKSUM_ON_COPY */
00080     buf->toport_chksum = 0;
00081 #if LWIP_NETBUF_RECVINFO
00082     ip_addr_set_zero(&buf->toaddr);
00083 #endif /* LWIP_NETBUF_RECVINFO */
00084 #endif /* LWIP_NETBUF_RECVINFO || LWIP_CHECKSUM_ON_COPY */
00085     return buf;
00086   } else {
00087     return NULL;
00088   }
00089 }
00090 
00091 /**
00092  * @ingroup netbuf
00093  * Deallocate a netbuf allocated by netbuf_new().
00094  *
00095  * @param buf pointer to a netbuf allocated by netbuf_new()
00096  */
00097 void
00098 netbuf_delete(struct netbuf *buf)
00099 {
00100   if (buf != NULL) {
00101     if (buf->p != NULL) {
00102       pbuf_free(buf->p);
00103       buf->p = buf->ptr = NULL;
00104     }
00105     memp_free(MEMP_NETBUF, buf);
00106   }
00107 }
00108 
00109 /**
00110  * @ingroup netbuf
00111  * Allocate memory for a packet buffer for a given netbuf.
00112  *
00113  * @param buf the netbuf for which to allocate a packet buffer
00114  * @param size the size of the packet buffer to allocate
00115  * @return pointer to the allocated memory
00116  *         NULL if no memory could be allocated
00117  */
00118 void *
00119 netbuf_alloc(struct netbuf *buf, u16_t size)
00120 {
00121   LWIP_ERROR("netbuf_alloc: invalid buf", (buf != NULL), return NULL;);
00122 
00123   /* Deallocate any previously allocated memory. */
00124   if (buf->p != NULL) {
00125     pbuf_free(buf->p);
00126   }
00127   buf->p = pbuf_alloc(PBUF_TRANSPORT, size, PBUF_RAM);
00128   if (buf->p == NULL) {
00129      return NULL;
00130   }
00131   LWIP_ASSERT("check that first pbuf can hold size",
00132              (buf->p->len >= size));
00133   buf->ptr = buf->p;
00134   return buf->p->payload;
00135 }
00136 
00137 /**
00138  * @ingroup netbuf
00139  * Free the packet buffer included in a netbuf
00140  *
00141  * @param buf pointer to the netbuf which contains the packet buffer to free
00142  */
00143 void
00144 netbuf_free(struct netbuf *buf)
00145 {
00146   LWIP_ERROR("netbuf_free: invalid buf", (buf != NULL), return;);
00147   if (buf->p != NULL) {
00148     pbuf_free(buf->p);
00149   }
00150   buf->p = buf->ptr = NULL;
00151 }
00152 
00153 /**
00154  * @ingroup netbuf
00155  * Let a netbuf reference existing (non-volatile) data.
00156  *
00157  * @param buf netbuf which should reference the data
00158  * @param dataptr pointer to the data to reference
00159  * @param size size of the data
00160  * @return ERR_OK if data is referenced
00161  *         ERR_MEM if data couldn't be referenced due to lack of memory
00162  */
00163 err_t
00164 netbuf_ref(struct netbuf *buf, const void *dataptr, u16_t size)
00165 {
00166   LWIP_ERROR("netbuf_ref: invalid buf", (buf != NULL), return ERR_ARG;);
00167   if (buf->p != NULL) {
00168     pbuf_free(buf->p);
00169   }
00170   buf->p = pbuf_alloc(PBUF_TRANSPORT, 0, PBUF_REF);
00171   if (buf->p == NULL) {
00172     buf->ptr = NULL;
00173     return ERR_MEM;
00174   }
00175   ((struct pbuf_rom*)buf->p)->payload = dataptr;
00176   buf->p->len = buf->p->tot_len = size;
00177   buf->ptr = buf->p;
00178   return ERR_OK;
00179 }
00180 
00181 /**
00182  * @ingroup netbuf
00183  * Chain one netbuf to another (@see pbuf_chain)
00184  *
00185  * @param head the first netbuf
00186  * @param tail netbuf to chain after head, freed by this function, may not be reference after returning
00187  */
00188 void
00189 netbuf_chain(struct netbuf *head, struct netbuf *tail)
00190 {
00191   LWIP_ERROR("netbuf_ref: invalid head", (head != NULL), return;);
00192   LWIP_ERROR("netbuf_chain: invalid tail", (tail != NULL), return;);
00193   pbuf_cat(head->p, tail->p);
00194   head->ptr = head->p;
00195   memp_free(MEMP_NETBUF, tail);
00196 }
00197 
00198 /**
00199  * @ingroup netbuf
00200  * Get the data pointer and length of the data inside a netbuf.
00201  *
00202  * @param buf netbuf to get the data from
00203  * @param dataptr pointer to a void pointer where to store the data pointer
00204  * @param len pointer to an u16_t where the length of the data is stored
00205  * @return ERR_OK if the information was retrieved,
00206  *         ERR_BUF on error.
00207  */
00208 err_t
00209 netbuf_data(struct netbuf *buf, void **dataptr, u16_t *len)
00210 {
00211   LWIP_ERROR("netbuf_data: invalid buf", (buf != NULL), return ERR_ARG;);
00212   LWIP_ERROR("netbuf_data: invalid dataptr", (dataptr != NULL), return ERR_ARG;);
00213   LWIP_ERROR("netbuf_data: invalid len", (len != NULL), return ERR_ARG;);
00214 
00215   if (buf->ptr == NULL) {
00216     return ERR_BUF;
00217   }
00218   *dataptr = buf->ptr->payload;
00219   *len = buf->ptr->len;
00220   return ERR_OK;
00221 }
00222 
00223 /**
00224  * @ingroup netbuf
00225  * Move the current data pointer of a packet buffer contained in a netbuf
00226  * to the next part.
00227  * The packet buffer itself is not modified.
00228  *
00229  * @param buf the netbuf to modify
00230  * @return -1 if there is no next part
00231  *         1  if moved to the next part but now there is no next part
00232  *         0  if moved to the next part and there are still more parts
00233  */
00234 s8_t
00235 netbuf_next(struct netbuf *buf)
00236 {
00237   LWIP_ERROR("netbuf_free: invalid buf", (buf != NULL), return -1;);
00238   if (buf->ptr->next == NULL) {
00239     return -1;
00240   }
00241   buf->ptr = buf->ptr->next;
00242   if (buf->ptr->next == NULL) {
00243     return 1;
00244   }
00245   return 0;
00246 }
00247 
00248 /**
00249  * @ingroup netbuf
00250  * Move the current data pointer of a packet buffer contained in a netbuf
00251  * to the beginning of the packet.
00252  * The packet buffer itself is not modified.
00253  *
00254  * @param buf the netbuf to modify
00255  */
00256 void
00257 netbuf_first(struct netbuf *buf)
00258 {
00259   LWIP_ERROR("netbuf_free: invalid buf", (buf != NULL), return;);
00260   buf->ptr = buf->p;
00261 }
00262 
00263 #endif /* LWIP_NETCONN */