curl通过post向服务器请求数据，服务器返回的数据量超过1024个字节。客户端接收不完整。

[piouswolf]

客户端通过post向服务器请求数据，服务器返回的数据达到3K， 客户端接收不完整。
请问有什么办法解决吗？

服务器返回的是一个json文件内容，不完整的话就没法解析了。

memset( curl_buffer, 0, 2048 );
curl_easy_setopt(m_curl, CURLOPT_HTTPPOST, 1);
curl_easy_setopt(m_curl, CURLOPT_URL, url);
curl_easy_setopt( m_curl, CURLOPT_POSTFIELDS, post_data );//data to server
curl_easy_setopt(m_curl, CURLOPT_WRITEFUNCTION, write_callback);//callback func, write data
curl_easy_setopt(m_curl, CURLOPT_WRITEDATA, curl_buffer);//recv buffer

[piouswolf]

curl_easy_setopt(m_curl, CURLOPT_WRITEFUNCTION, write_callback);//callback func, write data 我在这个write_callback函数查看返回的数据是不完整的。但是通过抓包工具可以看到，返回的是一个完整的包。 这是为什么呢？ 难道是没有从系统缓冲区里面读到所有数据吗？

[piouswolf]

Linux平台是OK的，但是在VS2012下编写的程序就会有问题。

[mymtom]

如果你的 curl_buffer 只是一个 char *的话，当然不行啦，你的回调函数会被多次调用的。 如果要直接保存到文件，直接用fwrite和FILE *fp设置CURLOPT_WRITEFUNCTION和CURLOPT_WRITEDATA 如果要保存到内存，请参考这段代码 http://curl.haxx.se/libcurl/c/getinmemory.html

/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 1998 - 2013, Daniel Stenberg, <[e-mail]>, et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
 * are also available at http://curl.haxx.se/docs/copyright.html.
 *
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
 * copies of the Software, and permit persons to whom the Software is
 * furnished to do so, under the terms of the COPYING file.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ***************************************************************************/ 
/* Example source code to show how the callback function can be used to
 * download data into a chunk of memory instead of storing it in a file.
 */ 
 
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
#include <curl/curl.h>
 
struct MemoryStruct {
  char *memory;
  size_t size;
};
 
 
static size_t
WriteMemoryCallback(void *contents, size_t size, size_t nmemb, void *userp)
{
  size_t realsize = size * nmemb;
  struct MemoryStruct *mem = (struct MemoryStruct *)userp;
 
  mem->memory = realloc(mem->memory, mem->size + realsize + 1);
  if(mem->memory == NULL) {
    /* out of memory! */ 
    printf("not enough memory (realloc returned NULL)\n");
    return 0;
  }
 
  memcpy(&(mem->memory[mem->size]), contents, realsize);
  mem->size += realsize;
  mem->memory[mem->size] = 0;
 
  return realsize;
}
 
 
int main(void)
{
  CURL *curl_handle;
  CURLcode res;
 
  struct MemoryStruct chunk;
 
  chunk.memory = malloc(1);  /* will be grown as needed by the realloc above */ 
  chunk.size = 0;    /* no data at this point */ 
 
  curl_global_init(CURL_GLOBAL_ALL);
 
  /* init the curl session */ 
  curl_handle = curl_easy_init();
 
  /* specify URL to get */ 
  curl_easy_setopt(curl_handle, CURLOPT_URL, "http://www.example.com/");
 
  /* send all data to this function  */ 
  curl_easy_setopt(curl_handle, CURLOPT_WRITEFUNCTION, WriteMemoryCallback);
 
  /* we pass our 'chunk' struct to the callback function */ 
  curl_easy_setopt(curl_handle, CURLOPT_WRITEDATA, (void *)&chunk);
 
  /* some servers don't like requests that are made without a user-agent
     field, so we provide one */ 
  curl_easy_setopt(curl_handle, CURLOPT_USERAGENT, "libcurl-agent/1.0");
 
  /* get it! */ 
  res = curl_easy_perform(curl_handle);
 
  /* check for errors */ 
  if(res != CURLE_OK) {
    fprintf(stderr, "curl_easy_perform() failed: %s\n",
            curl_easy_strerror(res));
  }
  else {
    /*
     * Now, our chunk.memory points to a memory block that is chunk.size
     * bytes big and contains the remote file.
     *
     * Do something nice with it!
     */ 
 
    printf("%lu bytes retrieved\n", (long)chunk.size);
  }
 
  /* cleanup curl stuff */ 
  curl_easy_cleanup(curl_handle);
 
  if(chunk.memory)
    free(chunk.memory);
 
  /* we're done with libcurl, so clean it up */ 
  curl_global_cleanup();
 
  return 0;
}

[wch18956441322]

引用 3 楼 mymtom 的回复:

如果你的 curl_buffer 只是一个 char *的话，当然不行啦，你的回调函数会被多次调用的。 如果要直接保存到文件，直接用fwrite和FILE *fp设置CURLOPT_WRITEFUNCTION和CURLOPT_WRITEDATA 如果要保存到内存，请参考这段代码 http://curl.haxx.se/libcurl/c/getinmemory.html

/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 1998 - 2013, Daniel Stenberg, <[e-mail]>, et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
 * are also available at http://curl.haxx.se/docs/copyright.html.
 *
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
 * copies of the Software, and permit persons to whom the Software is
 * furnished to do so, under the terms of the COPYING file.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ***************************************************************************/ 
/* Example source code to show how the callback function can be used to
 * download data into a chunk of memory instead of storing it in a file.
 */ 
 
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
#include <curl/curl.h>
 
struct MemoryStruct {
  char *memory;
  size_t size;
};
 
 
static size_t
WriteMemoryCallback(void *contents, size_t size, size_t nmemb, void *userp)
{
  size_t realsize = size * nmemb;
  struct MemoryStruct *mem = (struct MemoryStruct *)userp;
 
  mem->memory = realloc(mem->memory, mem->size + realsize + 1);
  if(mem->memory == NULL) {
    /* out of memory! */ 
    printf("not enough memory (realloc returned NULL)\n");
    return 0;
  }
 
  memcpy(&(mem->memory[mem->size]), contents, realsize);
  mem->size += realsize;
  mem->memory[mem->size] = 0;
 
  return realsize;
}
 
 
int main(void)
{
  CURL *curl_handle;
  CURLcode res;
 
  struct MemoryStruct chunk;
 
  chunk.memory = malloc(1);  /* will be grown as needed by the realloc above */ 
  chunk.size = 0;    /* no data at this point */ 
 
  curl_global_init(CURL_GLOBAL_ALL);
 
  /* init the curl session */ 
  curl_handle = curl_easy_init();
 
  /* specify URL to get */ 
  curl_easy_setopt(curl_handle, CURLOPT_URL, "http://www.example.com/");
 
  /* send all data to this function  */ 
  curl_easy_setopt(curl_handle, CURLOPT_WRITEFUNCTION, WriteMemoryCallback);
 
  /* we pass our 'chunk' struct to the callback function */ 
  curl_easy_setopt(curl_handle, CURLOPT_WRITEDATA, (void *)&chunk);
 
  /* some servers don't like requests that are made without a user-agent
     field, so we provide one */ 
  curl_easy_setopt(curl_handle, CURLOPT_USERAGENT, "libcurl-agent/1.0");
 
  /* get it! */ 
  res = curl_easy_perform(curl_handle);
 
  /* check for errors */ 
  if(res != CURLE_OK) {
    fprintf(stderr, "curl_easy_perform() failed: %s\n",
            curl_easy_strerror(res));
  }
  else {
    /*
     * Now, our chunk.memory points to a memory block that is chunk.size
     * bytes big and contains the remote file.
     *
     * Do something nice with it!
     */ 
 
    printf("%lu bytes retrieved\n", (long)chunk.size);
  }
 
  /* cleanup curl stuff */ 
  curl_easy_cleanup(curl_handle);
 
  if(chunk.memory)
    free(chunk.memory);
 
  /* we're done with libcurl, so clean it up */ 
  curl_global_cleanup();
 
  return 0;
}

我访问百度首页，奇怪的是为什么我拿到的chunk.size大小是5000多，但是我把chunk.memory打印出来只是一个问号；