Manpages - CURLOPT_HSTSWRITEFUNCTION.3

CURLOPT_HSTSWRITEFUNCTION - write callback for HSTS hosts

#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);

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 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.

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

NULL - no callback.

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

  {
    /* 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);
  }

Added in 7.74.0

This will return CURLE_OK.

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