CURLOPT_HTTP_VERSION(3)

CURLOPT_HTTP_VERSION(3curl_easy_setopt optionCURLOPT_HTTP_VERSION(3)

NAME

     CURLOPT_HTTP_VERSION - specify HTTP protocol version to use

SYNOPSIS

     #include <curl/curl.h>

     CURLcode           curl_easy_setopt(CURL            *handle,
     CURLOPT_HTTP_VERSION, long version);

DESCRIPTION

     Pass version a long, set to  one  of  the  values  described
     below.  They  ask 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.

     Note that the HTTP version is just a request.  libcurl  will
     still  prioritize  to  re-use  an  existing connection so it
     might then re-use a connection  using  a  HTTP  version  you
     haven't asked for.

     CURL_HTTP_VERSION_NONE
          We don't care about what version the library uses. lib-
          curl will use whatever it thinks fit.

     CURL_HTTP_VERSION_1_0
          Enforce HTTP 1.0 requests.

     CURL_HTTP_VERSION_1_1
          Enforce HTTP 1.1 requests.

     CURL_HTTP_VERSION_2_0
          Attempt HTTP 2 requests. libcurl will fall back to HTTP
          1.1  if  HTTP  2  can't  be negotiated with the server.
          (Added in 7.33.0)

          The alias CURL_HTTP_VERSION_2 was added  in  7.43.0  to
          better reflect the actual protocol name.

     CURL_HTTP_VERSION_2TLS
          Attempt HTTP 2 over TLS (HTTPS) only. libcurl will fall
          back to HTTP 1.1 if HTTP 2 can't be negotiated with the
          HTTPS server. For clear text HTTP servers, libcurl will
          use 1.1. (Added in 7.47.0)

     CURL_HTTP_VERSION_2_PRIOR_KNOWLEDGE
          Issue  non-TLS  HTTP  requests  using  HTTP/2   without
          HTTP/1.1  Upgrade. It requires prior knowledge that the
          server supports HTTP/2 straight  away.  HTTPS  requests
          will  still  do HTTP/2 the standard way with negotiated
          protocol  version  in  the  TLS  handshake.  (Added  in

libcurl 7.58.0      Last change: May 30, 2017                   1

CURLOPT_HTTP_VERSION(3curl_easy_setopt optionCURLOPT_HTTP_VERSION(3)

          7.49.0)

DEFAULT

     CURL_HTTP_VERSION_NONE

PROTOCOLS

     HTTP

EXAMPLE

     CURL *curl = curl_easy_init();
     if(curl) {
       CURLcode ret;
       curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
       curl_easy_setopt(curl, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_2TLS);
       ret = curl_easy_perform(curl);
       if(ret == CURLE_HTTP_RETURNED_ERROR) {
         /* a HTTP response error problem */
       }
     }

AVAILABILITY

     Along with HTTP

RETURN VALUE

     Returns    CURLE_OK    if    HTTP    is    supported,    and
     CURLE_UNKNOWN_OPTION if not.

SEE ALSO

     CURLOPT_SSLVERSION(3), CURLOPT_HTTP200ALIASES(3),

libcurl 7.58.0      Last change: May 30, 2017                   2