NAME

       CURLOPT_HSTS - HSTS cache filename

SYNOPSIS

       #include <curl/curl.h>

       CURLcode curl_easy_setopt(CURL *handle, CURLOPT_HSTS, char *filename);

DESCRIPTION

       Make the filename point to a filename to load an existing HSTS cache from, and to store the cache in when
       the easy handle is closed. Setting a file name with this option also enables HSTS for  this  handle  (the
       equivalent of setting CURLHSTS_ENABLE with CURLOPT_HSTS_CTRL(3)).

       If  the  given  file  does not exist or contains no HSTS entries at startup, the HSTS cache simply starts
       empty. Setting the filename to NULL or "" only enables HSTS without reading from or writing to any file.

       If this option is set multiple times, libcurl loads cache entries from each given file  but  only  stores
       the last used name for later writing.

FILE FORMAT

       The HSTS cache is saved to and loaded from a text file with one entry per physical line. Each line in the
       file has the following format:

       [host] [stamp]

       [host] is the domain name for the entry and the name is dot-prefixed if it is  an  entry  valid  for  all
       subdomains to the name as well or only for the exact name.

       [stamp] is the time (in UTC) when the entry expires and it uses the format "YYYYMMDD HH:MM:SS".

       Lines  starting  with  "#"  are treated as comments and are ignored. There is currently no length or size
       limit.

DEFAULT

       NULL, no filename

PROTOCOLS

       This functionality affects http only

EXAMPLE

       int main(void)
       {
         CURL *curl = curl_easy_init();
         if(curl) {
           curl_easy_setopt(curl, CURLOPT_HSTS, "/home/user/.hsts-cache");
           curl_easy_perform(curl);
         }
       }

AVAILABILITY

       Added in curl 7.74.0

RETURN VALUE

       Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.

SEE ALSO

       CURLOPT_ALTSVC(3), CURLOPT_HSTS_CTRL(3), CURLOPT_RESOLVE(3)