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| .TH CURLOPT_ALTSVC_CTRL 3 "5 Feb 2019" "libcurl 7.64.1" "curl_easy_setopt options" |
| .SH NAME |
| CURLOPT_ALTSVC_CTRL \- control alt-svc behavior |
| .SH SYNOPSIS |
| .nf |
| #include <curl/curl.h> |
| |
| #define CURLALTSVC_IMMEDIATELY (1<<0) |
| #define CURLALTSVC_READONLYFILE (1<<2) |
| #define CURLALTSVC_H1 (1<<3) |
| #define CURLALTSVC_H2 (1<<4) |
| #define CURLALTSVC_H3 (1<<5) |
| |
| CURLcode curl_easy_setopt(CURL *handle, CURLOPT_ALTSVC_CTRL, long bitmask); |
| .fi |
| .SH EXPERIMENTAL |
| Warning: this feature is early code and is marked as experimental. It can only |
| be enabled by explicitly telling configure with \fB--enable-alt-svc\fP. You are |
| advised to not ship this in production before the experimental label is |
| removed. |
| .SH DESCRIPTION |
| Populate the long \fIbitmask\fP with the correct set of features to instruct |
| libcurl how to handle Alt-Svc for the transfers using this handle. |
| |
| libcurl will only accept Alt-Svc headers over a secure transport, meaning |
| HTTPS. It will also only complete a request to an alternative origin if that |
| origin is properly hosted over HTTPS. These requirements are there to make |
| sure both the source and the destination are legitimate. |
| |
| Setting any bit will enable the alt-svc engine. |
| .IP "CURLALTSVC_IMMEDIATELY" |
| If an Alt-Svc: header is received, this instructs libcurl to switch to one of |
| those alternatives asap rather than to save it and use for the next |
| request. (Not currently supported). |
| .IP "CURLALTSVC_READONLYFILE" |
| Do not write the alt-svc cache back to the file specified with |
| \fICURLOPT_ALTSVC(3)\fP even if it gets updated. By default a file specified |
| with that option will be read and written to as deemed necessary. |
| .IP "CURLALTSVC_H1" |
| Accept alternative services offered over HTTP/1.1. |
| .IP "CURLALTSVC_H2" |
| Accept alternative services offered over HTTP/2. This will only be used if |
| libcurl was also built to actually support HTTP/2, otherwise this bit will be |
| ignored. |
| .IP "CURLALTSVC_H3" |
| Accept alternative services offered over HTTP/3. This will only be used if |
| libcurl was also built to actually support HTTP/3, otherwise this bit will be |
| ignored. |
| .SH DEFAULT |
| Alt-Svc handling is disabled by default. If \fICURLOPT_ALTSVC(3)\fP is set, |
| \fICURLOPT_ALTSVC_CTRL(3)\fP has a default value corresponding to |
| CURLALTSVC_H1 | CURLALTSVC_H2 | CURLALTSVC_H3 - the HTTP/2 and HTTP/3 bits are |
| only set if libcurl was built with support for those versions. |
| .SH PROTOCOLS |
| HTTPS |
| .SH EXAMPLE |
| .nf |
| CURL *curl = curl_easy_init(); |
| if(curl) { |
| curl_easy_setopt(curl, CURLOPT_ALTSVC_CTRL, CURLALTSVC_H1); |
| curl_easy_setopt(curl, CURLOPT_ALTSVC, "altsvc-cache.txt"); |
| curl_easy_perform(curl); |
| } |
| .fi |
| .SH AVAILABILITY |
| Added in 7.64.1 |
| .SH RETURN VALUE |
| Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not. |
| .SH "SEE ALSO" |
| .BR CURLOPT_ALTSVC "(3), " CURLOPT_CONNECT_TO "(3), " CURLOPT_RESOLVE "(3), " |
