minix/lib/liblwip/dist/src/api/netbuf.c

   1 /**
   2  * @file
   3  * Network buffer management
   4  *
   5  * @defgroup netbuf Network buffers
   6  * @ingroup netconn
   7  * Network buffer descriptor for @ref netconn. Based on @ref pbuf internally
   8  * to avoid copying data around.\n
   9  * Buffers must not be shared accross multiple threads, all functions except
  10  * netbuf_new() and netbuf_delete() are not thread-safe.
  11  */
  12
  13 /*
  14  * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
  15  * All rights reserved.
  16  *
  17  * Redistribution and use in source and binary forms, with or without modification,
  18  * are permitted provided that the following conditions are met:
  19  *
  20  * 1. Redistributions of source code must retain the above copyright notice,
  21  *    this list of conditions and the following disclaimer.
  22  * 2. Redistributions in binary form must reproduce the above copyright notice,
  23  *    this list of conditions and the following disclaimer in the documentation
  24  *    and/or other materials provided with the distribution.
  25  * 3. The name of the author may not be used to endorse or promote products
  26  *    derived from this software without specific prior written permission.
  27  *
  28  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
  29  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
  30  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
  31  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  32  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
  33  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  34  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  35  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
  36  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
  37  * OF SUCH DAMAGE.
  38  *
  39  * This file is part of the lwIP TCP/IP stack.
  40  *
  41  * Author: Adam Dunkels <adam@sics.se>
  42  *
  43  */
  44
  45 #include "lwip/opt.h"
  46
  47 #if LWIP_NETCONN /* don't build if not configured for use in lwipopts.h */
  48
  49 #include "lwip/netbuf.h"
  50 #include "lwip/memp.h"
  51
  52 #include <string.h>
  53
  54 /**
  55  * @ingroup netbuf
  56  * Create (allocate) and initialize a new netbuf.
  57  * The netbuf doesn't yet contain a packet buffer!
  58  *
  59  * @return a pointer to a new netbuf
  60  *         NULL on lack of memory
  61  */
  62 struct
  63 netbuf *netbuf_new(void)
  64 {
  65   struct netbuf *buf;
  66
  67   buf = (struct netbuf *)memp_malloc(MEMP_NETBUF);
  68   if (buf != NULL) {
  69     memset(buf, 0, sizeof(struct netbuf));
  70   }
  71   return buf;
  72 }
  73
  74 /**
  75  * @ingroup netbuf
  76  * Deallocate a netbuf allocated by netbuf_new().
  77  *
  78  * @param buf pointer to a netbuf allocated by netbuf_new()
  79  */
  80 void
  81 netbuf_delete(struct netbuf *buf)
  82 {
  83   if (buf != NULL) {
  84     if (buf->p != NULL) {
  85       pbuf_free(buf->p);
  86       buf->p = buf->ptr = NULL;
  87     }
  88     memp_free(MEMP_NETBUF, buf);
  89   }
  90 }
  91
  92 /**
  93  * @ingroup netbuf
  94  * Allocate memory for a packet buffer for a given netbuf.
  95  *
  96  * @param buf the netbuf for which to allocate a packet buffer
  97  * @param size the size of the packet buffer to allocate
  98  * @return pointer to the allocated memory
  99  *         NULL if no memory could be allocated
 100  */
 101 void *
 102 netbuf_alloc(struct netbuf *buf, u16_t size)
 103 {
 104   LWIP_ERROR("netbuf_alloc: invalid buf", (buf != NULL), return NULL;);
 105
 106   /* Deallocate any previously allocated memory. */
 107   if (buf->p != NULL) {
 108     pbuf_free(buf->p);
 109   }
 110   buf->p = pbuf_alloc(PBUF_TRANSPORT, size, PBUF_RAM);
 111   if (buf->p == NULL) {
 112      return NULL;
 113   }
 114   LWIP_ASSERT("check that first pbuf can hold size",
 115              (buf->p->len >= size));
 116   buf->ptr = buf->p;
 117   return buf->p->payload;
 118 }
 119
 120 /**
 121  * @ingroup netbuf
 122  * Free the packet buffer included in a netbuf
 123  *
 124  * @param buf pointer to the netbuf which contains the packet buffer to free
 125  */
 126 void
 127 netbuf_free(struct netbuf *buf)
 128 {
 129   LWIP_ERROR("netbuf_free: invalid buf", (buf != NULL), return;);
 130   if (buf->p != NULL) {
 131     pbuf_free(buf->p);
 132   }
 133   buf->p = buf->ptr = NULL;
 134 #if LWIP_CHECKSUM_ON_COPY
 135   buf->flags = 0;
 136   buf->toport_chksum = 0;
 137 #endif /* LWIP_CHECKSUM_ON_COPY */
 138 }
 139
 140 /**
 141  * @ingroup netbuf
 142  * Let a netbuf reference existing (non-volatile) data.
 143  *
 144  * @param buf netbuf which should reference the data
 145  * @param dataptr pointer to the data to reference
 146  * @param size size of the data
 147  * @return ERR_OK if data is referenced
 148  *         ERR_MEM if data couldn't be referenced due to lack of memory
 149  */
 150 err_t
 151 netbuf_ref(struct netbuf *buf, const void *dataptr, u16_t size)
 152 {
 153   LWIP_ERROR("netbuf_ref: invalid buf", (buf != NULL), return ERR_ARG;);
 154   if (buf->p != NULL) {
 155     pbuf_free(buf->p);
 156   }
 157   buf->p = pbuf_alloc(PBUF_TRANSPORT, 0, PBUF_REF);
 158   if (buf->p == NULL) {
 159     buf->ptr = NULL;
 160     return ERR_MEM;
 161   }
 162   ((struct pbuf_rom*)buf->p)->payload = dataptr;
 163   buf->p->len = buf->p->tot_len = size;
 164   buf->ptr = buf->p;
 165   return ERR_OK;
 166 }
 167
 168 /**
 169  * @ingroup netbuf
 170  * Chain one netbuf to another (@see pbuf_chain)
 171  *
 172  * @param head the first netbuf
 173  * @param tail netbuf to chain after head, freed by this function, may not be reference after returning
 174  */
 175 void
 176 netbuf_chain(struct netbuf *head, struct netbuf *tail)
 177 {
 178   LWIP_ERROR("netbuf_chain: invalid head", (head != NULL), return;);
 179   LWIP_ERROR("netbuf_chain: invalid tail", (tail != NULL), return;);
 180   pbuf_cat(head->p, tail->p);
 181   head->ptr = head->p;
 182   memp_free(MEMP_NETBUF, tail);
 183 }
 184
 185 /**
 186  * @ingroup netbuf
 187  * Get the data pointer and length of the data inside a netbuf.
 188  *
 189  * @param buf netbuf to get the data from
 190  * @param dataptr pointer to a void pointer where to store the data pointer
 191  * @param len pointer to an u16_t where the length of the data is stored
 192  * @return ERR_OK if the information was retrieved,
 193  *         ERR_BUF on error.
 194  */
 195 err_t
 196 netbuf_data(struct netbuf *buf, void **dataptr, u16_t *len)
 197 {
 198   LWIP_ERROR("netbuf_data: invalid buf", (buf != NULL), return ERR_ARG;);
 199   LWIP_ERROR("netbuf_data: invalid dataptr", (dataptr != NULL), return ERR_ARG;);
 200   LWIP_ERROR("netbuf_data: invalid len", (len != NULL), return ERR_ARG;);
 201
 202   if (buf->ptr == NULL) {
 203     return ERR_BUF;
 204   }
 205   *dataptr = buf->ptr->payload;
 206   *len = buf->ptr->len;
 207   return ERR_OK;
 208 }
 209
 210 /**
 211  * @ingroup netbuf
 212  * Move the current data pointer of a packet buffer contained in a netbuf
 213  * to the next part.
 214  * The packet buffer itself is not modified.
 215  *
 216  * @param buf the netbuf to modify
 217  * @return -1 if there is no next part
 218  *         1  if moved to the next part but now there is no next part
 219  *         0  if moved to the next part and there are still more parts
 220  */
 221 s8_t
 222 netbuf_next(struct netbuf *buf)
 223 {
 224   LWIP_ERROR("netbuf_next: invalid buf", (buf != NULL), return -1;);
 225   if (buf->ptr->next == NULL) {
 226     return -1;
 227   }
 228   buf->ptr = buf->ptr->next;
 229   if (buf->ptr->next == NULL) {
 230     return 1;
 231   }
 232   return 0;
 233 }
 234
 235 /**
 236  * @ingroup netbuf
 237  * Move the current data pointer of a packet buffer contained in a netbuf
 238  * to the beginning of the packet.
 239  * The packet buffer itself is not modified.
 240  *
 241  * @param buf the netbuf to modify
 242  */
 243 void
 244 netbuf_first(struct netbuf *buf)
 245 {
 246   LWIP_ERROR("netbuf_first: invalid buf", (buf != NULL), return;);
 247   buf->ptr = buf->p;
 248 }
 249
 250 #endif /* LWIP_NETCONN */