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CURLOPT_ALTSVC(3) curl_easy_setopt options CURLOPT_ALTSVC(3)
CURLOPT_ALTSVC - alt-svc cache file name
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_ALTSVC, char *filename);
Pass in a pointer to a filename to instruct libcurl to use that file as
the Alt-Svc cache to read existing cache contents from and possibly
also write it back to a after a transfer, unless
CURLALTSVC_READONLYFILE is set in CURLOPT_ALTSVC_CTRL(3).
Specify a blank file name ("") to make libcurl not load from a file at
NULL. The alt-svc cache is not read nor written to file.
CURL *curl = curl_easy_init();
curl_easy_setopt(curl, CURLOPT_ALTSVC_CTRL, CURLALTSVC_H1);
curl_easy_setopt(curl, CURLOPT_ALTSVC, "altsvc-cache.txt");
A text based file with one line per alt-svc entry and each line
consists of nine space-separated fields.
An example line could look like
h2 www.example 8443 h3 second.example 443 "20190808 06:18:37" 1 0
The fields of that line are:
h2 ALPN id for the source origin
Host name for the source origin
8443 Port number for the source origin
h3 ALPN id for the destination host
Host name for the destination host
443 Port number for the destination host
2019* Expiration date and time of this entry within double quotes. The
date format is "YYYYMMDD HH:MM:SS" and the time zone is GMT.
1 Boolean (1 or 0) if "persist" was set for this entry
0 Integer priority value (not currently used)
Added in 7.64.1
Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION
CURLOPT_ALTSVC_CTRL(3), CURLOPT_CONNECT_TO(3), CURLOPT_RESOLVE(3),
libcurl 7.87.0 September 20, 2022 CURLOPT_ALTSVC(3)