NAME

       CURLOPT_HSTSWRITEFUNCTION - write callback for HSTS hosts

SYNOPSIS

       #include <curl/curl.h>

       struct curl_hstsentry {
         char *name;
         size_t namelen;
         unsigned int includeSubDomains:1;
         char expire[18]; /* YYYYMMDD HH:MM:SS [null-terminated] */
       };

       struct curl_index {
         size_t index; /* the provided entry's "index" or count */
         size_t total; /* total number of entries to save */
       };

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

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

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 clientp argument with the CURLOPT_HSTSWRITEDATA(3) option or it is 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 is nothing more to do. It can also return
       CURLSTS_FAIL to signal error.

       This option does not enable HSTS, you need to use CURLOPT_HSTS_CTRL(3) to do that.

DEFAULT

       NULL - no callback.

PROTOCOLS

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

EXAMPLE

       struct priv {
         void *custom;
       };

       static CURLSTScode hswr_cb(CURL *easy, struct curl_hstsentry *sts,
                                  struct curl_index *count, void *clientp)
       {
         /* save the passed in HSTS data somewhere */
         return CURLSTS_OK;
       }

       int main(void)
       {
         CURL *curl = curl_easy_init();
         if(curl) {
           struct priv my_stuff;
           CURLcode res;

           /* set HSTS read callback */
           curl_easy_setopt(curl, CURLOPT_HSTSWRITEFUNCTION, hswr_cb);

           /* pass in suitable argument to the callback */
           curl_easy_setopt(curl, CURLOPT_HSTSWRITEDATA, &my_stuff);

           res = curl_easy_perform(curl);
         }
       }

AVAILABILITY

       Added in 7.74.0

RETURN VALUE

       This returns CURLE_OK.

SEE ALSO

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