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 allows HSTS without reading from or
       writing to any file. NULL also makes libcurl clear the list of files  to  read  HSTS  data
       from, if any such were previously set.

       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)