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23 .TH CURLOPT_HTTP_VERSION 3 "May 30, 2017" "libcurl 7.59.0" "curl_easy_setopt options"
26 CURLOPT_HTTP_VERSION \- specify HTTP protocol version to use
28 #include <curl/curl.h>
30 CURLcode curl_easy_setopt(CURL *handle, CURLOPT_HTTP_VERSION, long version);
32 Pass \fIversion\fP a long, set to one of the values described below. They ask
33 libcurl to use the specific HTTP versions. This is not sensible to do unless
34 you have a good reason. You have to set this option if you want to use
35 libcurl's HTTP/2 support.
37 Note that the HTTP version is just a request. libcurl will still prioritize to
38 re-use an existing connection so it might then re-use a connection using a
39 HTTP version you haven't asked for.
41 .IP CURL_HTTP_VERSION_NONE
42 We don't care about what version the library uses. libcurl will use whatever
44 .IP CURL_HTTP_VERSION_1_0
45 Enforce HTTP 1.0 requests.
46 .IP CURL_HTTP_VERSION_1_1
47 Enforce HTTP 1.1 requests.
48 .IP CURL_HTTP_VERSION_2_0
49 Attempt HTTP 2 requests. libcurl will fall back to HTTP 1.1 if HTTP 2 can't be
50 negotiated with the server. (Added in 7.33.0)
52 The alias \fICURL_HTTP_VERSION_2\fP was added in 7.43.0 to better reflect the
54 .IP CURL_HTTP_VERSION_2TLS
55 Attempt HTTP 2 over TLS (HTTPS) only. libcurl will fall back to HTTP 1.1 if
56 HTTP 2 can't be negotiated with the HTTPS server. For clear text HTTP servers,
57 libcurl will use 1.1. (Added in 7.47.0)
58 .IP CURL_HTTP_VERSION_2_PRIOR_KNOWLEDGE
59 Issue non-TLS HTTP requests using HTTP/2 without HTTP/1.1 Upgrade. It requires
60 prior knowledge that the server supports HTTP/2 straight away. HTTPS requests
61 will still do HTTP/2 the standard way with negotiated protocol version in the
62 TLS handshake. (Added in 7.49.0)
64 CURL_HTTP_VERSION_NONE
69 CURL *curl = curl_easy_init();
72 curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
73 curl_easy_setopt(curl, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_2TLS);
74 ret = curl_easy_perform(curl);
75 if(ret == CURLE_HTTP_RETURNED_ERROR) {
76 /* a HTTP response error problem */
83 Returns CURLE_OK if HTTP is supported, and CURLE_UNKNOWN_OPTION if not.
85 .BR CURLOPT_SSLVERSION "(3), " CURLOPT_HTTP200ALIASES "(3), "