CURLOPT_HSTSWRITEFUNCTION(3)                          curl_easy_setopt options

NAME
       CURLOPT_HSTSWRITEFUNCTION - write callback for HSTS hosts

SYNOPSIS
       #include <curl/curl.h>

       CURLSTScode hstswrite(CURL *easy, struct curl_hstsentry *sts,
                             struct curl_index *count, void *userp);

       CURLcode curl_easy_setopt(CURL *handle, CURLOPT_HSTSWRITEFUNCTION,
       hstswrite);

EXPERIMENTAL
       Warning: this feature is early code and is marked as experimental. It
       can only be enabled by explicitly telling configure with --enable-hsts.
       You are advised to not ship this in production before the experimental
       label is removed.

DESCRIPTION
       Pass a pointer to your callback function, as the prototype shows above.

       This callback function gets called by libcurl repeatedly to allow the
       application to store the in-memory HSTS cache when libcurl is about to
       discard it.

       Set the userp argument with the _HSTSWRITEDATA&section=3">CURLOPT_HSTSWRITEDATA(3) option or it
       will be NULL.

       When the callback is invoked, the sts pointer points to a populated
       struct: Read the host name to 'name' (it is 'namelen' bytes long and
       null terminated. The 'includeSubDomains' field is non-zero if the entry
       matches subdomains. The 'expire' string is a date stamp null-terminated
       string using the syntax YYYYMMDD HH:MM:SS.

       The callback should return CURLSTS_OK if it succeeded and is prepared
       to be called again (for another host) or CURLSTS_DONE if there's
       nothing more to do. It can also return CURLSTS_FAIL to signal error.

DEFAULT
       NULL - no callback.

PROTOCOLS
       This feature is only used for HTTP(S) transfer.

EXAMPLE
       {
         /* set HSTS read callback */
         curl_easy_setopt(curl, CURLOPT_HSTSWRITEFUNCTION, hstswrite);

         /* pass in suitable argument to the callback */
         curl_easy_setopt(curl, CURLOPT_HSTSWRITEDATA, &hstspreload[0]);

         result = curl_easy_perform(curl);
       }

AVAILABILITY
       Added in 7.74.0

RETURN VALUE
       This will return CURLE_OK.

SEE ALSO
       CURLOPT_HSTSWRITEDATA(3), CURLOPT_HSTSWRITEFUNCTION(3),
       CURLOPT_HSTS(3), CURLOPT_HSTS_CTRL(3),

libcurl 7.77.0                 November 4, 2020   CURLOPT_HSTSWRITEFUNCTION(3)