SSL connection using libcurl

Question

I need to establish a connection via ssl socket at the following address : stream-api-integration.betfair.com (port 443), and read messages that come from the server using libcurl. I'm new to using this library. I tried to search for information on this issue, but I didn't find what I needed.

If the connection is established successfully, the following response should come from the server: {"op": "connection", "connection Id": "100-040320153715-29795"}.

How do I do this?

P.S. Meanwhile, I have no problems sending post requests to https using libcurl. If this helps in any way, I provide the code that successfully executes the post request. The problem is only with ssl sockets.

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

size_t writeToStream(char* buffer, size_t size, size_t nitems, std::ostream* stream)
{
    size_t realwrote = size * nitems;
    stream->write(buffer, static_cast<std::streamsize>(realwrote));
    if (!(*stream)){
        realwrote = 0;
    }

    return realwrote;
}

int main(int argc, char *argv[])
{
std::string url = "https://identitysso-cert.betfair.com/api/certlogin";

std::string acceptHeader = "Accept: application/json");
std::string appHeader = "X-Application: myappkey");
std::string contentTypeHeader = "Content-Type: application/x-www-form-urlencoded";

curl_slist* slist = nullptr;

slist = curl_slist_append(slist, acceptHeader.c_str());
slist = curl_slist_append(slist, appHeader.c_str());
slist = curl_slist_append(slist, contentTypeHeader.c_str());

std::stringstream result;
char errorBuffer[CURL_ERROR_SIZE];

CURL *curl = curl_easy_init();

if(curl != nullptr){
    curl_easy_setopt(curl, CURLOPT_CAINFO, "../cacert.pem");

    curl_easy_setopt(curl, CURLOPT_ERRORBUFFER, errorBuffer);

    curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
    curl_easy_setopt(curl, CURLOPT_USE_SSL, CURLUSESSL_ALL);
    curl_easy_setopt(curl, CURLOPT_HTTPHEADER, slist);

    std::string certFilePath = "../client-2048.crt";
    std::string keyFilePath = "../client-2048.key";

    curl_easy_setopt(curl, CURLOPT_SSLCERT, certFilePath.c_str());
    curl_easy_setopt(curl, CURLOPT_SSLKEY, keyFilePath.c_str());

    std::string payload = "username=myusername&password=mypassword";

    curl_easy_setopt(curl, CURLOPT_POSTFIELDS, postFields.c_str());

    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, writeToStream);
    curl_easy_setopt(curl, CURLOPT_WRITEDATA, &result);

    curl_easy_setopt(curl, CURLOPT_NOSIGNAL, 1);
    curl_easy_setopt(curl, CURLOPT_ERRORBUFFER, errorBuffer);

    errorBuffer[0] = 0;

    int responseCode = -1;

    CURLcode curlResult = curl_easy_perform(curl);

    if (curlResult == CURLE_OK){
        curl_easy_getinfo(curl, CURLINFO_RESPONSE_CODE, &responseCode);

        std::cout<<"response code: "<<responseCode<<std::endl;
        std::cout<<result.str()<<std::endl;

    }

    else{
        std::cout<<"Failed:("<<std::endl;
        throw std::runtime_error(errorBuffer);
    }
}

return 0;
}