/** * @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 */structnetbuf *netbuf_new(void){  struct netbuf *buf;  buf = memp_malloc(MEMP_NETBUF);  if (buf != NULL) {    buf->p = NULL;    buf->ptr = NULL;    buf->addr = NULL;    return buf;  } else {    return NULL;  }}/** * Deallocate a netbuf allocated by netbuf_new(). * * @param buf pointer to a netbuf allocated by netbuf_new() */voidnetbuf_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 */voidnetbuf_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_tnetbuf_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 */voidnetbuf_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_chain(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_tnetbuf_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_tnetbuf_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 */voidnetbuf_first(struct netbuf *buf){  LWIP_ERROR("netbuf_free: invalid buf", (buf != NULL), return;);  buf->ptr = buf->p;}#endif /* LWIP_NETCONN */