CURLcode curl_easy_getinfo(CURL *handle, CURLINFO_PROTOCOL, long *p);
CURLPROTO_DICT, CURLPROTO_FILE, CURLPROTO_FTP, CURLPROTO_FTPS, CURLPROTO_GOPHER, CURLPROTO_HTTP, CURLPROTO_HTTPS, CURLPROTO_IMAP, CURLPROTO_IMAPS, CURLPROTO_LDAP, CURLPROTO_LDAPS, CURLPROTO_POP3, CURLPROTO_POP3S, CURLPROTO_RTMP, CURLPROTO_RTMPE, CURLPROTO_RTMPS, CURLPROTO_RTMPT, CURLPROTO_RTMPTE, CURLPROTO_RTMPTS, CURLPROTO_RTSP, CURLPROTO_SCP, CURLPROTO_SFTP, CURLPROTO_SMB, CURLPROTO_SMBS, CURLPROTO_SMTP, CURLPROTO_SMTPS, CURLPROTO_TELNET, CURLPROTO_TFTP, CURLPROTO_MQTT
CURL *curl = curl_easy_init();
if(curl) {
CURLcode res;
curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
res = curl_easy_perform(curl);
if(res == CURLE_OK) {
long protocol;
curl_easy_getinfo(curl, CURLINFO_PROTOCOL, &protocol);
}
curl_easy_cleanup(curl);
}