利用curl来做http访问(支持session,cookie)

/* curl_httpget.h */
#ifndef CURL_HTTPGET_H
#define CURL_HTTPGET_H
struct MemoryStruct {
char *memory;
size_t size;
};
int curl_httpget(const char* URLbuf,struct MemoryStruct *chunk,const char* cookiefile);
#endif

/* curl_httpget.cpp */
#include <curl/curl.h>
#include <curl/types.h>
#include <curl/easy.h>
#include "curl_httpget.h"
#include <alloc.h>
void *myrealloc(void *ptr, size_t size)
{
/* There might be a realloc() out there that doesn't like reallocing
NULL pointers, so we take care of it here */
if(ptr)
return realloc(ptr, size);
else
return malloc(size);
}
size_t
WriteMemoryCallback(void *ptr, size_t size, size_t nmemb, void *data)
{
size_t realsize = size * nmemb;
struct MemoryStruct *mem = (struct MemoryStruct *)data;
mem->memory = (char *)myrealloc(mem->memory, mem->size + realsize + 1);
if (mem->memory) {
memcpy(&(mem->memory[mem->size]), ptr, realsize);
mem->size += realsize;
mem->memory[mem->size] = 0;
}
return realsize;
}
int curl_httpget(const char* URLbuf,struct MemoryStruct *chunk,const char* cookiefile)
{
CURL *curl_handle;
int errcode=0;
chunk->memory=NULL; /* we expect realloc(NULL, size) to work */
chunk->size = 0; /* no data at this point */
curl_global_init(CURL_GLOBAL_ALL);
/* init the curl session */
curl_handle = curl_easy_init();
curl_easy_setopt(curl_handle, CURLOPT_URL, URLbuf);
curl_easy_setopt(curl_handle, CURLOPT_COOKIEFILE,cookiefile);
/* 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);
curl_easy_setopt(curl_handle, CURLOPT_USERAGENT, "libcurl-agent/1.0");
curl_easy_setopt(curl_handle, CURLOPT_COOKIEJAR,cookiefile);
/* get it! */
errcode=curl_easy_perform(curl_handle);
/* cleanup curl stuff */
curl_easy_cleanup(curl_handle);
return errcode;
}

用法：
errcode= curl_httpget(URLbuf,&chunk,cookiefile);
if(!errcode){
int min=sizeof(content)>chunk.size?chunk.size:sizeof(content);
strncpy(content,chunk.memory,min);
}else{
strcpy(content,"");
}
if(chunk.memory) free(chunk.memory);