libcurl curl_easy_setopt "Unknown error" - c++

Question

I'm trying to use C++ cURL library for sending Json data via PUT method and my code looks something like this
CURL* m_curlHandle;
CURLcode m_returnValue;
//function1 start
curl_global_init(CURL_GLOBAL_ALL);
struct curl_slist* headers = NULL;
std::ostringstream oss;
struct curl_slist* slist = NULL;
slist = curl_slist_append(headers, "Accept: application/json");
slist = curl_slist_append(headers, "Content-Type: application/json");
slist = curl_slist_append(headers, "charsets: utf-8");
m_curlHandle = curl_easy_init();
if (!m_curlHandle)
// throw exception
curl_easy_setopt(m_curlHandle, CURLOPT_HTTPHEADER, headers);
//function1 end
//function2 start
std::string url = "some URL"; // my url
curl_easy_setopt(m_curlHandle, CURLOPT_URL, url.c_str());
unsigned int timeout = 5;
curl_easy_setopt(m_curlHandle, CURLOPT_TIMEOUT, timeout);
std::string localIp = "some IP"; // my IP address
curl_easy_setopt(m_curlHandle, CURLOPT_INTERFACE, localIp.c_str());
curl_easy_setopt(m_curlHandle, CURLOPT_CUSTOMREQUEST, "PUT");
std::string json = "some json struct"; //my json struct
curl_easy_setopt(m_curlHandle, CURLOPT_POSTFIELDS, json.c_str());
curl_easy_setopt(m_curlHandle, CURLOPT_WRITEFUNCTION, callbackWriter); //static size_t callbackWriter(char* buffer, size_t size, size_t nmemb, void* userp);
m_returnValue = curl_easy_perform(m_curlHandle);
//function2 end
I call function1 then function2 and the problem is that for all curl_easy_setopt calls I get error code 1685083487 and error description "Unknown error". So what may cause to a such result and how to fix this?
Thank you in advance!

Answer 1

I would use CURLOPT_POSTFIELDS instead, my func was something like this
void poolStr(const std::vector<unsigned char> &data, const std::string &url)
{
curl_global_init(CURL_GLOBAL_DEFAULT);
mCurl = curl_easy_init();
if(mCurl)
{
curl_easy_setopt(mCurl, CURLOPT_URL, url.c_str());
curl_easy_setopt(mCurl, CURLOPT_POST, 1L);
curl_easy_setopt(mCurl, CURLOPT_POSTFIELDSIZE, data.size());
curl_easy_setopt(mCurl, CURLOPT_POSTFIELDS, &data[0]);
mChunk = curl_slist_append(mChunk, "Content-Type: application/binary");
mChunk = curl_slist_append(mChunk, "Expect:");
curl_easy_setopt(mCurl, CURLOPT_HTTPHEADER, mChunk);
CURLcode res = curl_easy_perform(mCurl);
if(res != CURLE_OK)
{
LOGERROR << "curl_easy_perform() failed: " << curl_easy_strerror(res) << "\n Attepmt number: " << attempt;
}
else
{
LOGINFO << "Data being sent.";
}
}
}
}
and calling like poolStr(data, mHost);