libcurl实现http及https方式下载和访问

准备条件：

编译好的libcurl库，如果要支持https，需要和openssl一起编译，网上教程较多

示例代码：（使用loadlibrary的方式只是为了测试方便）

// libcurtest.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include <iostream>
#include <windows.h>
#include "curl.h"
using namespace std;

size_t my_write_func( void *ptr, size_t size, size_t nmemb, FILE *stream )
{
if( stream != NULL )
return fwrite( ptr, size, nmemb, stream );
else
return 0;
}

//by zhaocl
int main()
{
HMODULE hdll = LoadLibrary( L"libcurl.dll" );

if( !hdll )
{
return -1;
}

typedef CURL * ( *PCURL_EASY_INIT )();
typedef CURLcode( *PCURL_EASY_SETOPT )( CURL*, CURLoption, ... );
typedef CURLcode( *PCURL_EASY_PERFORM )( CURL* );
typedef void( *PCURL_EASY_CLEANUP )( CURL * );

PCURL_EASY_SETOPT pFunction = NULL;
PCURL_EASY_PERFORM pFunction2 = NULL;
PCURL_EASY_INIT pFunction3 = NULL;
PCURL_EASY_CLEANUP pFunction4 = NULL;

pFunction3 = ( PCURL_EASY_INIT )GetProcAddress( hdll, "curl_easy_init" );
pFunction = ( PCURL_EASY_SETOPT )GetProcAddress( hdll, "curl_easy_setopt" );
pFunction2 = ( PCURL_EASY_PERFORM )GetProcAddress( hdll, "curl_easy_perform" );
pFunction4 = ( PCURL_EASY_CLEANUP )GetProcAddress( hdll, "curl_easy_cleanup" );

PCURL_EASY_INIT url_ini = ( PCURL_EASY_INIT )( PCURL_EASY_INIT )GetProcAddress( hdll, "curl_easy_init" );

if( !url_ini )
{
return -1;
}

CURL *curl;
CURLcode res;
//const char* strUrl = "Https://www.baidu.com";
const char* strUrl = "https://slproweb.com/download/Win64OpenSSL-1_0_2o.exe";
curl = url_ini(); //初始化

if( curl && strUrl )
{
//下载
FILE *outfile;
fopen_s( &outfile, "AxTools.exe", "wb" );

pFunction( curl, CURLOPT_URL, strUrl );
pFunction( curl, CURLOPT_WRITEDATA, outfile );
pFunction( curl, CURLOPT_SSL_VERIFYPEER, false ); //设定为不验证证书和HOST
pFunction( curl, CURLOPT_SSL_VERIFYHOST, false );
pFunction( curl, CURLOPT_WRITEFUNCTION, my_write_func );
pFunction( curl, CURLOPT_NOPROGRESS, FALSE );
pFunction( curl, CURLOPT_PROGRESSFUNCTION, NULL );
pFunction( curl, CURLOPT_PROGRESSDATA, NULL );

res = pFunction2( curl );

fclose( outfile );
/* always cleanup */
pFunction4( curl );

//访问
pFunction( curl, CURLOPT_URL, strUrl ); //设置url地址

pFunction( curl, CURLOPT_WRITEFUNCTION, my_write_func ); //设置回调函数

FILE *fp;
_wfopen_s( &fp, L"c:\\test.txt", _T( "wb+" ) );
pFunction( curl, CURLOPT_WRITEDATA, fp ); //设置写数据

pFunction( curl, CURLOPT_SSL_VERIFYPEER, false ); //设定为不验证证书和HOST
pFunction( curl, CURLOPT_SSL_VERIFYHOST, false );

res = pFunction2( curl ); //执行

if( res == CURLE_OK )
{
//ok 处理数据
pFunction4( curl );
return 1;
}

return -1;
}

return -1;
}

补充https示例：

实际项目中，还是用lib+头文件的方式居多

bool PostData(const char* pUrl, const char* pData, char** pOut, uint32_t* pBufLen)
{

   try
   {
       CURL* pCurl = nullptr;
       CURLcode res;

       pCurl = curl_easy_init(); //curl_global_init不主动调用，会自动调用
       if (nullptr != pCurl)
       {
           // 设置超时时间为8秒
           curl_easy_setopt(pCurl, CURLOPT_TIMEOUT, 8);
           curl_easy_setopt(pCurl, CURLOPT_POSTFIELDS, pData);
           curl_easy_setopt(pCurl, CURLOPT_URL, pUrl);

           // 下面两个为验证对方和验证主机名，若为0，则跳过验证，我这个服务器必须验证才能得到请求数据
           //curl_easy_setopt(pCurl, CURLOPT_SSL_VERIFYPEER, 1L);
           //curl_easy_setopt(pCurl, CURLOPT_SSL_VERIFYHOST, 1L);

           // 配置 https 请求所需证书
           curl_easy_setopt(pCurl, CURLOPT_CAINFO, "/etc/msc/ca_info.pem");
           curl_easy_setopt(pCurl, CURLOPT_SSLCERT, "/etc/msc/client.pem");
           curl_easy_setopt(pCurl, CURLOPT_SSLKEY, "/etc/msc/client_key.pem");
           curl_easy_setopt(pCurl, CURLOPT_KEYPASSWD, "your_key_password");

           curl_easy_setopt(pCurl, CURLOPT_WRITEFUNCTION, writer);
           std::string strOut;
           curl_easy_setopt(pCurl, CURLOPT_WRITEDATA, (void*)&strOut);

           // Perform the request, res will get the return code
           res = m_pCurl->easy_perform(pCurl);

           uint32_t uSize = strOut.length() + 1;
           *pOut = new char[uSize];
           if (pOut)
           {
               memset(*pOut, 0x0, uSize);
               memcpy(*pOut, strOut.c_str(), uSize);
               *pBufLen = uSize;
               cout<< L"recv data=" << strOut.c_str() << endl;
           }

           if (res != CURLE_OK)
           {
               cout<< L"curl_easy_perform() failed code=" << static_cast<uint32_t>(res) << endl;
           }
           curl_easy_cleanup(pCurl);
       }
       //curl_global_cleanup();
   }
   catch (std::exception& ex)
   {
       cout<< L"curl exception:" << ex.what() << endl;
   }

   return true;
}
————————————————
版权声明：本文为CSDN博主「半雨微凉丶」的原创文章，遵循CC 4.0 BY-SA版权协议，转载请附上原文出处链接及本声明。
原文链接：https://blog.csdn.net/myruo/article/details/80591372

libcurl实现http及https方式下载和访问

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