.\" ************************************************************************** .\" * _ _ ____ _ .\" * Project ___| | | | _ \| | .\" * / __| | | | |_) | | .\" * | (__| |_| | _ <| |___ .\" * \___|\___/|_| \_\_____| .\" * .\" * Copyright (C) 1998 - 2016, Daniel Stenberg, <daniel@haxx.se>, et al. .\" * .\" * This software is licensed as described in the file COPYING, which .\" * you should have received as part of this distribution. The terms .\" * are also available at https://curl.haxx.se/docs/copyright.html. .\" * .\" * You may opt to use, copy, modify, merge, publish, distribute and/or sell .\" * copies of the Software, and permit persons to whom the Software is .\" * furnished to do so, under the terms of the COPYING file. .\" * .\" * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY .\" * KIND, either express or implied. .\" * .\" ************************************************************************** .\" .TH CURLOPT_HTTP_VERSION 3 "17 Jun 2014" "libcurl 7.37.0" "curl_easy_setopt options" .SH NAME CURLOPT_HTTP_VERSION \- specify HTTP protocol version to use .SH SYNOPSIS #include <curl/curl.h> CURLcode curl_easy_setopt(CURL *handle, CURLOPT_HTTP_VERSION, long version); .SH DESCRIPTION Pass \fIversion\fP 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. .IP CURL_HTTP_VERSION_NONE We don't care about what version the library uses. libcurl will use whatever it thinks fit. .IP CURL_HTTP_VERSION_1_0 Enforce HTTP 1.0 requests. .IP CURL_HTTP_VERSION_1_1 Enforce HTTP 1.1 requests. .IP 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 \fICURL_HTTP_VERSION_2\fP was added in 7.43.0 to better reflect the actual protocol name. .IP 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) .IP 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 7.49.0) .SH DEFAULT CURL_HTTP_VERSION_NONE .SH PROTOCOLS HTTP .SH EXAMPLE TODO .SH AVAILABILITY Along with HTTP .SH RETURN VALUE Returns CURLE_OK if HTTP is supported, and CURLE_UNKNOWN_OPTION if not. .SH "SEE ALSO" .BR CURLOPT_SSLVERSION "(3), " CURLOPT_HTTP200ALIASES "(3), "