246 lines
6.9 KiB
C
246 lines
6.9 KiB
C
/**
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* @file
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* Network buffer management
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*
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*/
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/*
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* Copyright (c) 2001-2004 Swedish Institute of Computer Science.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without modification,
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* are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
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* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
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* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
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* OF SUCH DAMAGE.
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*
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* This file is part of the lwIP TCP/IP stack.
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*
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* Author: Adam Dunkels <adam@sics.se>
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*
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*/
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#include "lwip/opt.h"
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#if LWIP_NETCONN /* don't build if not configured for use in lwipopts.h */
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#include "lwip/netbuf.h"
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#include "lwip/memp.h"
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#include <string.h>
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/**
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* Create (allocate) and initialize a new netbuf.
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* The netbuf doesn't yet contain a packet buffer!
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* 申请一个新的netbuf空间，但不分配任何数据空间
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* @return a pointer to a new netbuf
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* NULL on lack of memory
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*/
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struct
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netbuf *netbuf_new(void)
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{
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struct netbuf *buf;
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buf = (struct netbuf *)memp_malloc(MEMP_NETBUF);
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if (buf != NULL) {
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buf->p = NULL;
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buf->ptr = NULL;
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ip_addr_set_any(&buf->addr);
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buf->port = 0;
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#if LWIP_NETBUF_RECVINFO || LWIP_CHECKSUM_ON_COPY
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#if LWIP_CHECKSUM_ON_COPY
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buf->flags = 0;
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#endif /* LWIP_CHECKSUM_ON_COPY */
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buf->toport_chksum = 0;
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#if LWIP_NETBUF_RECVINFO
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ip_addr_set_any(&buf->toaddr);
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#endif /* LWIP_NETBUF_RECVINFO */
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#endif /* LWIP_NETBUF_RECVINFO || LWIP_CHECKSUM_ON_COPY */
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return buf;
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} else {
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return NULL;
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}
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}
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/**
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* Deallocate a netbuf allocated by netbuf_new().
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* 释放一个netbuf空间
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* @param buf pointer to a netbuf allocated by netbuf_new()
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*/
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void
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netbuf_delete(struct netbuf *buf)
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{
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if (buf != NULL) {
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if (buf->p != NULL) {
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pbuf_free(buf->p);
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buf->p = buf->ptr = NULL;
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}
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memp_free(MEMP_NETBUF, buf);
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}
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}
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/**
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* Allocate memory for a packet buffer for a given netbuf.
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*为netbuf结构分配size大小的数据空间
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* @param buf the netbuf for which to allocate a packet buffer
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* @param size the size of the packet buffer to allocate
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* @return pointer to the allocated memory
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* NULL if no memory could be allocated
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*/
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void *
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netbuf_alloc(struct netbuf *buf, u16_t size)
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{
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LWIP_ERROR("netbuf_alloc: invalid buf", (buf != NULL), return NULL;);
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/* Deallocate any previously allocated memory. */
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if (buf->p != NULL) {
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pbuf_free(buf->p);
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}
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buf->p = pbuf_alloc(PBUF_TRANSPORT, size, PBUF_RAM);
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if (buf->p == NULL) {
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return NULL;
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}
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LWIP_ASSERT("check that first pbuf can hold size",
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(buf->p->len >= size));
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buf->ptr = buf->p;
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return buf->p->payload;
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}
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/**
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* Free the packet buffer included in a netbuf
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*释放netbuf结构指向的数据pbuf
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* @param buf pointer to the netbuf which contains the packet buffer to free
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*/
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void
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netbuf_free(struct netbuf *buf)
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{
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LWIP_ERROR("netbuf_free: invalid buf", (buf != NULL), return;);
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if (buf->p != NULL) {
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pbuf_free(buf->p);
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}
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buf->p = buf->ptr = NULL;
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}
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/**
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* Let a netbuf reference existing (non-volatile) data.
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*
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* @param buf netbuf which should reference the data
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* @param dataptr pointer to the data to reference
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* @param size size of the data
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* @return ERR_OK if data is referenced
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* ERR_MEM if data couldn't be referenced due to lack of memory
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*/
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err_t
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netbuf_ref(struct netbuf *buf, const void *dataptr, u16_t size)
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{
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LWIP_ERROR("netbuf_ref: invalid buf", (buf != NULL), return ERR_ARG;);
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if (buf->p != NULL) {
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pbuf_free(buf->p);
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}
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buf->p = pbuf_alloc(PBUF_TRANSPORT, 0, PBUF_REF);
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if (buf->p == NULL) {
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buf->ptr = NULL;
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return ERR_MEM;
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}
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buf->p->payload = (void*)dataptr;
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buf->p->len = buf->p->tot_len = size;
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buf->ptr = buf->p;
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return ERR_OK;
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}
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/**
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* Chain one netbuf to another (@see pbuf_chain)
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*
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* @param head the first netbuf
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* @param tail netbuf to chain after head, freed by this function, may not be reference after returning
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*/
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void
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netbuf_chain(struct netbuf *head, struct netbuf *tail)
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{
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LWIP_ERROR("netbuf_ref: invalid head", (head != NULL), return;);
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LWIP_ERROR("netbuf_chain: invalid tail", (tail != NULL), return;);
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pbuf_cat(head->p, tail->p);
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head->ptr = head->p;
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memp_free(MEMP_NETBUF, tail);
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}
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/**
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* Get the data pointer and length of the data inside a netbuf.
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*
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* @param buf netbuf to get the data from
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* @param dataptr pointer to a void pointer where to store the data pointer
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* @param len pointer to an u16_t where the length of the data is stored
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* @return ERR_OK if the information was retreived,
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* ERR_BUF on error.
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*/
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err_t
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netbuf_data(struct netbuf *buf, void **dataptr, u16_t *len)
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{
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LWIP_ERROR("netbuf_data: invalid buf", (buf != NULL), return ERR_ARG;);
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LWIP_ERROR("netbuf_data: invalid dataptr", (dataptr != NULL), return ERR_ARG;);
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LWIP_ERROR("netbuf_data: invalid len", (len != NULL), return ERR_ARG;);
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if (buf->ptr == NULL) {
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return ERR_BUF;
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}
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*dataptr = buf->ptr->payload;
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*len = buf->ptr->len;
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return ERR_OK;
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}
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/**
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* Move the current data pointer of a packet buffer contained in a netbuf
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* to the next part.
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* The packet buffer itself is not modified.
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*
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* @param buf the netbuf to modify
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* @return -1 if there is no next part
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* 1 if moved to the next part but now there is no next part
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* 0 if moved to the next part and there are still more parts
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*/
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s8_t
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netbuf_next(struct netbuf *buf)
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{
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LWIP_ERROR("netbuf_free: invalid buf", (buf != NULL), return -1;);
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if (buf->ptr->next == NULL) {
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return -1;
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}
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buf->ptr = buf->ptr->next;
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if (buf->ptr->next == NULL) {
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return 1;
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}
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return 0;
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}
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/**
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* Move the current data pointer of a packet buffer contained in a netbuf
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* to the beginning of the packet.
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* The packet buffer itself is not modified.
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*
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* @param buf the netbuf to modify
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*/
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void
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netbuf_first(struct netbuf *buf)
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{
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LWIP_ERROR("netbuf_free: invalid buf", (buf != NULL), return;);
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buf->ptr = buf->p;
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}
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#endif /* LWIP_NETCONN */
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