C++使用libcurl做HttpClient 和 curl_easy_setopt

curl_easy_setopt 参数设置

https://curl.haxx.se/libcurl/c/curl_easy_setopt.html

 使用libcurl做HttpClient

#ifndef __HTTP_CURL_H__
#define __HTTP_CURL_H__

#include <string>

class CHttpClient
{
public:
    CHttpClient(void);
    ~CHttpClient(void);

public:
    /**
    * @brief HTTP POST请求
    * @param strUrl 输入参数,请求的Url地址,如:http://www.baidu.com
    * @param strPost 输入参数,使用如下格式para1=val1¶2=val2&…
    * @param strResponse 输出参数,返回的内容
    * @return 返回是否Post成功
    */
    int Post(const std::string & strUrl, const std::string & strPost, std::string & strResponse);

    /**
    * @brief HTTP GET请求
    * @param strUrl 输入参数,请求的Url地址,如:http://www.baidu.com
    * @param strResponse 输出参数,返回的内容
    * @return 返回是否Post成功
    */
    int Get(const std::string & strUrl, std::string & strResponse);

    /**
    * @brief HTTPS POST请求,无证书版本
    * @param strUrl 输入参数,请求的Url地址,如:https://www.alipay.com
    * @param strPost 输入参数,使用如下格式para1=val1¶2=val2&…
    * @param strResponse 输出参数,返回的内容
    * @param pCaPath 输入参数,为CA证书的路径.如果输入为NULL,则不验证服务器端证书的有效性.
    * @return 返回是否Post成功
    */
    int Posts(const std::string & strUrl, const std::string & strPost, std::string & strResponse, const char * pCaPath = NULL);

    /**
    * @brief HTTPS GET请求,无证书版本
    * @param strUrl 输入参数,请求的Url地址,如:https://www.alipay.com
    * @param strResponse 输出参数,返回的内容
    * @param pCaPath 输入参数,为CA证书的路径.如果输入为NULL,则不验证服务器端证书的有效性.
    * @return 返回是否Post成功
    */
    int Gets(const std::string & strUrl, std::string & strResponse, const char * pCaPath = NULL);

public:
    void SetDebug(bool bDebug);

private:
    bool m_bDebug;
};

#endif

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

CHttpClient::CHttpClient(void) :
m_bDebug(false)
{

}

CHttpClient::~CHttpClient(void)
{

}

static int OnDebug(CURL *, curl_infotype itype, char * pData, size_t size, void *)
{
    if(itype == CURLINFO_TEXT)
    {
        //printf("[TEXT]%s\n", pData);
    }
    else if(itype == CURLINFO_HEADER_IN)
    {
        printf("[HEADER_IN]%s\n", pData);
    }
    else if(itype == CURLINFO_HEADER_OUT)
    {
        printf("[HEADER_OUT]%s\n", pData);
    }
    else if(itype == CURLINFO_DATA_IN)
    {
        printf("[DATA_IN]%s\n", pData);
    }
    else if(itype == CURLINFO_DATA_OUT)
    {
        printf("[DATA_OUT]%s\n", pData);
    }
    return ;
}

static size_t OnWriteData(void* buffer, size_t size, size_t nmemb, void* lpVoid)
{
    std::string* str = dynamic_cast<std::string*>((std::string *)lpVoid);
    if( NULL == str || NULL == buffer )
    {
        return -;
    }

    char* pData = (char*)buffer;
    str->append(pData, size * nmemb);
    return nmemb;
}

int CHttpClient::Post(const std::string & strUrl, const std::string & strPost, std::string & strResponse)
{
    CURLcode res;
    CURL* curl = curl_easy_init();
    if(NULL == curl)
    {
        return CURLE_FAILED_INIT;
    }
    if(m_bDebug)
    {
        curl_easy_setopt(curl, CURLOPT_VERBOSE, );
        curl_easy_setopt(curl, CURLOPT_DEBUGFUNCTION, OnDebug);
    }
    curl_easy_setopt(curl, CURLOPT_URL, strUrl.c_str());
    curl_easy_setopt(curl, CURLOPT_POST, );
    curl_easy_setopt(curl, CURLOPT_POSTFIELDS, strPost.c_str());
    curl_easy_setopt(curl, CURLOPT_READFUNCTION, NULL);
    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, OnWriteData);
    curl_easy_setopt(curl, CURLOPT_WRITEDATA, (void *)&strResponse);
    curl_easy_setopt(curl, CURLOPT_NOSIGNAL, );
    curl_easy_setopt(curl, CURLOPT_CONNECTTIMEOUT, );
    curl_easy_setopt(curl, CURLOPT_TIMEOUT, );
    res = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
    return res;
}

int CHttpClient::Get(const std::string & strUrl, std::string & strResponse)
{
    CURLcode res;
    CURL* curl = curl_easy_init();
    if(NULL == curl)
    {
        return CURLE_FAILED_INIT;
    }
    if(m_bDebug)
    {
        curl_easy_setopt(curl, CURLOPT_VERBOSE, );
        curl_easy_setopt(curl, CURLOPT_DEBUGFUNCTION, OnDebug);
    }
<pre name="code" class="cpp">    curl_easy_setopt(curl, CURLOPT_URL, strUrl.c_str());
    curl_easy_setopt(curl, CURLOPT_READFUNCTION, NULL);
    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, OnWriteData);
    curl_easy_setopt(curl, CURLOPT_WRITEDATA, (void *)&strResponse);
    /**
    * 当多个线程都使用超时处理的时候，同时主线程中有sleep或是wait等操作。
    * 如果不设置这个选项，libcurl将会发信号打断这个wait从而导致程序退出。
    */
    curl_easy_setopt(curl, CURLOPT_NOSIGNAL, );
    curl_easy_setopt(curl, CURLOPT_CONNECTTIMEOUT, );
    curl_easy_setopt(curl, CURLOPT_TIMEOUT, );
    res = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
    return res;
}

int CHttpClient::Posts(const std::string & strUrl, const std::string & strPost, std::string & strResponse, const char * pCaPath)
{
    CURLcode res;
    CURL* curl = curl_easy_init();
    if(NULL == curl)
    {
        return CURLE_FAILED_INIT;
    }
    if(m_bDebug)
    {
        curl_easy_setopt(curl, CURLOPT_VERBOSE, );
        curl_easy_setopt(curl, CURLOPT_DEBUGFUNCTION, OnDebug);
    }
    curl_easy_setopt(curl, CURLOPT_URL, strUrl.c_str());
    curl_easy_setopt(curl, CURLOPT_POST, );
    curl_easy_setopt(curl, CURLOPT_POSTFIELDS, strPost.c_str());
    curl_easy_setopt(curl, CURLOPT_READFUNCTION, NULL);
    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, OnWriteData);
    curl_easy_setopt(curl, CURLOPT_WRITEDATA, (void *)&strResponse);
    curl_easy_setopt(curl, CURLOPT_NOSIGNAL, );
    if(NULL == pCaPath)
    {
        curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, false);
        curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, false);
    }
    else
    {
        //缺省情况就是PEM，所以无需设置，另外支持DER
        //curl_easy_setopt(curl,CURLOPT_SSLCERTTYPE,"PEM");
        curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, true);
        curl_easy_setopt(curl, CURLOPT_CAINFO, pCaPath);
    }
    curl_easy_setopt(curl, CURLOPT_CONNECTTIMEOUT, );
    curl_easy_setopt(curl, CURLOPT_TIMEOUT, );
    res = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
    return res;
}

int CHttpClient::Gets(const std::string & strUrl, std::string & strResponse, const char * pCaPath)
{
    CURLcode res;
    CURL* curl = curl_easy_init();
    if(NULL == curl)
    {
        return CURLE_FAILED_INIT;
    }
    if(m_bDebug)
    {
        curl_easy_setopt(curl, CURLOPT_VERBOSE, );
        curl_easy_setopt(curl, CURLOPT_DEBUGFUNCTION, OnDebug);
    }
    curl_easy_setopt(curl, CURLOPT_URL, strUrl.c_str());
    curl_easy_setopt(curl, CURLOPT_READFUNCTION, NULL);
    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, OnWriteData);
    curl_easy_setopt(curl, CURLOPT_WRITEDATA, (void *)&strResponse);
    curl_easy_setopt(curl, CURLOPT_NOSIGNAL, );
    if(NULL == pCaPath)
    {
        curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, false);
        curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, false);
    }
    else
    {
        curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, true);
        curl_easy_setopt(curl, CURLOPT_CAINFO, pCaPath);
    }
    curl_easy_setopt(curl, CURLOPT_CONNECTTIMEOUT, );
    curl_easy_setopt(curl, CURLOPT_TIMEOUT, );
    res = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
    return res;
}

///////////////////////////////////////////////////////////////////////////////////////////////

void CHttpClient::SetDebug(bool bDebug)
{
    m_bDebug = bDebug;
}
   

http headers

        struct curl_slist *headers = NULL;

        //增加HTTP header
        headers = curl_slist_append(headers, "Accept:application/json");
        headers = curl_slist_append(headers, "Content-Type:application/json");
        headers = curl_slist_append(headers, "charset:utf-8");

        curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);

CURLOPT_NOSIGNAL

Pass a long. If it is 1, libcurl will not use any functions that install signal handlers or any functions that cause signals to be sent to the process. This option is mainly here to allow multi-threaded unix applications to still set/use all timeout options etc, without risking getting signals. (Added in 7.10)

If this option is set and libcurl has been built with the standard name resolver, timeouts will not occur while the name resolve takes place. Consider building libcurl with c-ares support to enable asynchronous DNS lookups, which enables nice timeouts for name resolves without signals.

Setting CURLOPT_NOSIGNAL to 1 makes libcurl NOT ask the system to ignore SIGPIPE signals, which otherwise are sent by the system when trying to send data to a socket which is closed in the other end. libcurl makes an effort to never cause such SIGPIPEs to trigger, but some operating systems have no way to avoid them and even on those that have there are some corner cases when they may still happen, contrary to our desire.

就是当多个线程都使用超时处理的时候，同时主线程中有sleep或是wait等操作。如果不设置这个选项，libcurl将会发信号打断这个wait从而导致程序退出。

所以，在使用的时候把这个选项设置成1就可以了.

curl_setopt(curl, CURLOPT_NOSIGNAL, 1L);

关于libcurl库的初始化和关闭：curl_global_init()和curl_global_cleanup()

这两个函数并不是线程安全的。所以只能在主线程中进行一次的初始化和清除。

虽然这个不是一定就会有问题，但是如果不这样处理还是有概率发生的