C++Socket编程—Libcurl库

一、LibCurl基本编程框架
libcurl是一个跨平台的网络协议库，支持http, https, ftp, gopher, telnet, dict, file, 和ldap 协议。libcurl同样支持HTTPS证书授权，HTTP POST, HTTP PUT, FTP 上传, HTTP基本表单上传，代理，cookies,和用户认证.

 

win32版的libcurl下载地址:http://curl.freeby.pctools.cl/download/libcurl-7.18.0-win32-msvc.zip

代码示例：调用libcurl模拟发送http包，并获取位置

#include <iostream>
#include "curl/curl.h"
#include <string>

#pragma comment(lib, "libcurl.lib")

using namespace std;

const char* UTF8_To_GBK(const char* source, char* pcDes);
string strUtf8;

size_t WriteCallback(char* ptr, size_t size, size_t nmemb, void* userdata)
{
	//printf(ptr);
	strUtf8 += ptr;
	return size * nmemb; //处理了所有的数据
}

 //初始化库，进程生命周期只调用一次
	curl_global_init(CURL_GLOBAL_ALL);
	/*
	发送请求
	*/
	//创建请求的句柄
	CURL* handle = curl_easy_init();

	//设置url
	CURLcode nRetCode=curl_easy_setopt(handle, CURLOPT_URL, "http://ip.tool.chinaz.com/");

	//设置代理，是fidder可以抓到包
	nRetCode = curl_easy_setopt(handle, CURLOPT_PROXYTYPE, CURLPROXY_HTTP);

	//设置处理响应包的回调函数
	nRetCode=curl_easy_setopt(handle, CURLOPT_WRITEFUNCTION, WriteCallback);
	//设置为fidder的代理地址
	nRetCode = curl_easy_setopt(handle, CURLOPT_PROXY, "127.0.0.1:8888");
	
	//为请求添加头部
	curl_slist* chunk = NULL;
	chunk = curl_slist_append(chunk, "Host: ip.tool.chinaz.com");
	chunk = curl_slist_append(chunk, "User-Agent: Mozilla / 5.0 (Windows NT 10.0; Win64; x64; rv:75.0) Gecko / 20100101 Firefox / 75.0");
	chunk = curl_slist_append(chunk, "Accept : text / html, application / xhtml + xml, application / xml; q = 0.9, image / webp, */*;q=0.8");
	chunk = curl_slist_append(chunk, "Accept-Language: zh-CN,zh;q=0.8,zh-TW;q=0.7,zh-HK;q=0.5,en-US;q=0.3,en;q=0.2");
	//chunk = curl_slist_append(chunk, "Accept-Encoding: gzip, deflate");//免解压缩
	chunk = curl_slist_append(chunk, "Connection: keep-alive");
	chunk = curl_slist_append(chunk, "Upgrade-Insecure-Requests: 1");
	curl_easy_setopt(handle, CURLOPT_HTTPHEADER, chunk);


	//发送请求
	nRetCode = curl_easy_perform(handle);

	//处理数据

	char* pBuff = new char[strUtf8.size()];
	UTF8_To_GBK(strUtf8.c_str(), pBuff);
	//printf(pBuff);

	string strGbk = pBuff;
	delete[] pBuff;

	//正则查找位置
	size_t nOff = strGbk.find("来自");
	size_t nOffBegin = strGbk.find("<dd>", nOff);
	size_t nOffEnd = strGbk.find("<a href", nOffBegin + 4);
	string strLocation = strGbk.substr(nOffBegin + 4, nOffEnd - (nOffBegin + 4));
	printf(strLocation.c_str());

	//反初始化，进程生命周期只调用一次
	curl_global_cleanup;

	return 0;
}

const char* UTF8_To_GBK(const char* source, char* pcDes)
{
	enum { GB2312 = 936 };
	//unsigned long len;
	int len = -1;
	len = ::MultiByteToWideChar(CP_UTF8, NULL, source, -1, NULL, NULL);
	if (len == 0)
		return NULL;
	wchar_t* wide_char_buffer = new wchar_t[len];
	::MultiByteToWideChar(CP_UTF8, NULL, source, -1, wide_char_buffer, len);
	len = ::WideCharToMultiByte(GB2312, NULL, wide_char_buffer, -1, NULL, NULL, NULL, NULL);
	if (len == 0)
	{
		delete[] wide_char_buffer;
		return NULL;
	}
	char* multi_byte_buffer = new char[len];
	::WideCharToMultiByte(GB2312, NULL, wide_char_buffer, -1, multi_byte_buffer, len, NULL, NULL);
	strcpy(pcDes, multi_byte_buffer);
	//std::string dest(multi_byte_buffer);
	delete[] multi_byte_buffer;
	delete[] wide_char_buffer;
	return pcDes;
}