Specify http protocol version to use
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_HTTP_VERSION, long version);
Pass version a long, set to one of the values described below. They force libcurl to use the specific HTTP versions. This is not sensible to do unless you have a good reason. You have to set this option if you want to use libcurl's HTTP/2 support.
We don't care about what version the library uses. libcurl will use whatever it thinks fit.
Enforce HTTP 1.0 requests.
Enforce HTTP 1.1 requests.
Attempt HTTP 2.0 requests. libcurl will fall back to HTTP 1.x if HTTP 2.0 can't be negotiated with the server.
Along with HTTP
Returns CURLE_OK if HTTP is supported, and CURLE_UNKNOWN_OPTION if not.