CURLOPT_HTTP_VERSION(3) Library Functions Manual 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 still prioritizes
to reuse existing connections so it might then reuse a connection using
an HTTP version you have not asked for.
CURL_HTTP_VERSION_NONE
We do not care about what version the library uses. libcurl uses
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 falls 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
specification. A user can add this version requirement with
CURLOPT_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 falls back to HTTP
1.1 if HTTP 2 cannot be negotiated with the HTTPS server. For
clear text HTTP servers, libcurl uses 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 still do HTTP/2 the
standard way with negotiated protocol version in the TLS
handshake. (Added in 7.49.0)
CURL_HTTP_VERSION_3
(Added in 7.66.0) This option makes libcurl attempt to use
HTTP/3 to the host given in the URL, with fallback to earlier
HTTP versions if needed.
CURL_HTTP_VERSION_3ONLY
(Added in 7.88.0) Setting this makes libcurl attempt to use
HTTP/3 directly to server given in the URL and does not
downgrade to earlier HTTP version if the server does not support
HTTP/3.
DEFAULT
Since curl 7.62.0: CURL_HTTP_VERSION_2TLS
Before that: CURL_HTTP_VERSION_1_1
PROTOCOLS
This functionality affects http only
EXAMPLE
int main(void)
{
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,
(long)CURL_HTTP_VERSION_2TLS);
ret = curl_easy_perform(curl);
if(ret == CURLE_HTTP_RETURNED_ERROR) {
/* an HTTP response error problem */
}
}
}
AVAILABILITY
Added in curl 7.9.1
RETURN VALUE
Returns CURLE_OK if HTTP is supported, and CURLE_UNKNOWN_OPTION if not.
SEE ALSO
CURLOPT_ALTSVC(3), CURLOPT_HTTP09_ALLOWED(3),
CURLOPT_HTTP200ALIASES(3), CURLOPT_SSLVERSION(3)
libcurl 2024-08-05 CURLOPT_HTTP_VERSION(3)
curl 8.9.1 - Generated Wed Aug 7 11:11:58 CDT 2024