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 /**
  * @file
  * Network buffer management
  *
  */
  
 /*
  * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
  * All rights reserved. 
  * 
  * Redistribution and use in source and binary forms, with or without modification, 
  * are permitted provided that the following conditions are met:
  *
  * 1. Redistributions of source code must retain the above copyright notice,
  *    this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright notice,
  *    this list of conditions and the following disclaimer in the documentation
  *    and/or other materials provided with the distribution.
  * 3. The name of the author may not be used to endorse or promote products
  *    derived from this software without specific prior written permission. 
  *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED 
  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 
  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT 
  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 
  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT 
  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 
  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY 
  * OF SUCH DAMAGE.
  *
  * This file is part of the lwIP TCP/IP stack.
  * 
  * Author: Adam Dunkels <adam@sics.se>
  *
  */
 
 #include "lwip/opt.h"
 
 #if LWIP_NETCONN /* don't build if not configured for use in lwipopts.h */
 
 #include "lwip/netbuf.h"
 #include "lwip/memp.h"
 
 #include <string.h>
 
 /**
  * Create (allocate) and initialize a new netbuf.
  * The netbuf doesn't yet contain a packet buffer!
  *
  * @return a pointer to a new netbuf
  *         NULL on lack of memory
  */
 struct
 netbuf *netbuf_new(void)
 {
   struct netbuf *buf;
 
   buf = memp_malloc(MEMP_NETBUF);
   if (buf != NULL) {
     buf->p = NULL;
     buf->ptr = NULL;
     buf->addr = NULL;
     buf->port = 0;
 #if LWIP_NETBUF_RECVINFO
     buf->toaddr = NULL;
     buf->toport = 0;
 #endif /* LWIP_NETBUF_RECVINFO */
     return buf;
   } else {
     return NULL;
   }
 }
 
 /**
  * Deallocate a netbuf allocated by netbuf_new().
  *
  * @param buf pointer to a netbuf allocated by netbuf_new()
  */
 void
 netbuf_delete(struct netbuf *buf)
 {
   if (buf != NULL) {
     if (buf->p != NULL) {
       pbuf_free(buf->p);
       buf->p = buf->ptr = NULL;
     }
     memp_free(MEMP_NETBUF, buf);
   }
 }
 
 /**
  * Allocate memory for a packet buffer for a given netbuf.
  *
  * @param buf the netbuf for which to allocate a packet buffer
  * @param size the size of the packet buffer to allocate
  * @return pointer to the allocated memory
  *         NULL if no memory could be allocated
  */
 void *
 netbuf_alloc(struct netbuf *buf, u16_t size)
 {
   LWIP_ERROR("netbuf_alloc: invalid buf", (buf != NULL), return NULL;);
 
   /* Deallocate any previously allocated memory. */
   if (buf->p != NULL) {
     pbuf_free(buf->p);
   }
   buf->p = pbuf_alloc(PBUF_TRANSPORT, size, PBUF_RAM);
   if (buf->p == NULL) {
      return NULL;
   }
   LWIP_ASSERT("check that first pbuf can hold size",
              (buf->p->len >= size));
   buf->ptr = buf->p;
   return buf->p->payload;
 }
 
 /**
  * Free the packet buffer included in a netbuf
  *
  * @param buf pointer to the netbuf which contains the packet buffer to free
  */
 void
 netbuf_free(struct netbuf *buf)
 {
   LWIP_ERROR("netbuf_free: invalid buf", (buf != NULL), return;);
   if (buf->p != NULL) {
     pbuf_free(buf->p);
   }
   buf->p = buf->ptr = NULL;
 }
 
 /**
  * Let a netbuf reference existing (non-volatile) data.
  *
  * @param buf netbuf which should reference the data
  * @param dataptr pointer to the data to reference
  * @param size size of the data
  * @return ERR_OK if data is referenced
  *         ERR_MEM if data couldn't be referenced due to lack of memory
  */
 err_t
 netbuf_ref(struct netbuf *buf, const void *dataptr, u16_t size)
 {
   LWIP_ERROR("netbuf_ref: invalid buf", (buf != NULL), return ERR_ARG;);
   if (buf->p != NULL) {
     pbuf_free(buf->p);
   }
   buf->p = pbuf_alloc(PBUF_TRANSPORT, 0, PBUF_REF);
   if (buf->p == NULL) {
     buf->ptr = NULL;
     return ERR_MEM;
   }
   buf->p->payload = (void*)dataptr;
   buf->p->len = buf->p->tot_len = size;
   buf->ptr = buf->p;
   return ERR_OK;
 }
 
 /**
  * Chain one netbuf to another (@see pbuf_chain)
  *
  * @param head the first netbuf
  * @param tail netbuf to chain after head, freed by this function, may not be reference after returning
  */
 void
 netbuf_chain(struct netbuf *head, struct netbuf *tail)
 {
   LWIP_ERROR("netbuf_ref: invalid head", (head != NULL), return;);
   LWIP_ERROR("netbuf_chain: invalid tail", (tail != NULL), return;);
   pbuf_cat(head->p, tail->p);
   head->ptr = head->p;
   memp_free(MEMP_NETBUF, tail);
 }
 
 /**
  * Get the data pointer and length of the data inside a netbuf.
  *
  * @param buf netbuf to get the data from
  * @param dataptr pointer to a void pointer where to store the data pointer
  * @param len pointer to an u16_t where the length of the data is stored
  * @return ERR_OK if the information was retreived,
  *         ERR_BUF on error.
  */
 err_t
 netbuf_data(struct netbuf *buf, void **dataptr, u16_t *len)
 {
   LWIP_ERROR("netbuf_data: invalid buf", (buf != NULL), return ERR_ARG;);
   LWIP_ERROR("netbuf_data: invalid dataptr", (dataptr != NULL), return ERR_ARG;);
   LWIP_ERROR("netbuf_data: invalid len", (len != NULL), return ERR_ARG;);
 
   if (buf->ptr == NULL) {
     return ERR_BUF;
   }
   *dataptr = buf->ptr->payload;
   *len = buf->ptr->len;
   return ERR_OK;
 }
 
 /**
  * Move the current data pointer of a packet buffer contained in a netbuf
  * to the next part.
  * The packet buffer itself is not modified.
  *
  * @param buf the netbuf to modify
  * @return -1 if there is no next part
  *         1  if moved to the next part but now there is no next part
  *         0  if moved to the next part and there are still more parts
  */
 s8_t
 netbuf_next(struct netbuf *buf)
 {
   LWIP_ERROR("netbuf_free: invalid buf", (buf != NULL), return -1;);
   if (buf->ptr->next == NULL) {
     return -1;
   }
   buf->ptr = buf->ptr->next;
   if (buf->ptr->next == NULL) {
     return 1;
   }
   return 0;
 }
 
 /**
  * Move the current data pointer of a packet buffer contained in a netbuf
  * to the beginning of the packet.
  * The packet buffer itself is not modified.
  *
  * @param buf the netbuf to modify
  */
 void
 netbuf_first(struct netbuf *buf)
 {
   LWIP_ERROR("netbuf_free: invalid buf", (buf != NULL), return;);
   buf->ptr = buf->p;
 }
 
 #endif /* LWIP_NETCONN */