CURLOPT_HTTP_VERSION − 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 requests. libcurl will fall back to HTTP 1.x if HTTP 2 can’t be negotiated with the server. (Added in 7.33.0)
Along with HTTP
Returns CURLE_OK if HTTP is supported, and CURLE_UNKNOWN_OPTION if not.