CURLOPT_HTTP_VERSION - HTTP protocol version to use
#include <curl/curl.h> CURLcode curl_easy_setopt(CURL *handle, CURLOPT_HTTP_VERSION, long version);
CURLOPT_HTTP_VERSION(3) curl_easy_setopt options CURLOPT_HTTP_VERSION(3) NAME CURLOPT_HTTP_VERSION - 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. Note that the HTTP version is just a request. libcurl will still prior- itize to re-use an existing connection so it might then re-use a con- nection using a HTTP version you have not asked for. CURL_HTTP_VERSION_NONE We do not care about what version the library uses. libcurl 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 cannot be negotiated with the server. (Added in 7.33.0) When libcurl uses HTTP/2 over HTTPS, it does not itself insist on TLS 1.2 or higher even though that is required by the speci- fication. A user can add this version requirement with CUR- LOPT_SSLVERSION(3). 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 cannot 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 hand- shake. (Added in 7.49.0) CURL_HTTP_VERSION_3 (Added in 7.66.0) Setting this value will make libcurl attempt to use HTTP/3 directly to server given in the URL. Note that this cannot gracefully downgrade to earlier HTTP version if the server does not support HTTP/3. For more reliably upgrading to HTTP/3, set the preferred version to something lower and let the server announce its HTTP/3 sup- port via Alt-Svc:. See CURLOPT_ALTSVC(3). DEFAULT Since curl 7.62.0: CURL_HTTP_VERSION_2TLS Before that: CURL_HTTP_VERSION_1_1 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) { /* an HTTP response error problem */ } } AVAILABILITY Along with HTTP RETURN VALUE Returns CURLE_OK if HTTP is supported, and CURLE_UNKNOWN_OPTION if not. ATTRIBUTES See attributes(7) for descriptions of the following attributes: +---------------+------------------+ |ATTRIBUTE TYPE | ATTRIBUTE VALUE | +---------------+------------------+ |Availability | web/curl | +---------------+------------------+ |Stability | Uncommitted | +---------------+------------------+ SEE ALSO CURLOPT_SSLVERSION(3), CURLOPT_HTTP200ALIASES(3), CUR- LOPT_HTTP09_ALLOWED(3), CURLOPT_ALTSVC(3) NOTES Source code for open source software components in Oracle Solaris can be found at https://www.oracle.com/downloads/opensource/solaris-source- code-downloads.html. This software was built from source available at https://github.com/oracle/solaris-userland. The original community source was downloaded from https://curl.se/down- load/curl-7.83.1.tar.bz2. Further information about this software can be found on the open source community website at http://curl.haxx.se/. libcurl 7.83.1 January 19, 2022 CURLOPT_HTTP_VERSION(3)