CURLOPT_HSTS_CTRL(3)

NAME
CURLOPT_HSTS_CTRL - control HSTS behavior

SYNOPSIS
#include <curl/curl.h>
#define CURLHSTS_ENABLE       (1L << 0)
#define CURLHSTS_READONLYFILE (1L << 1)
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_HSTS_CTRL, long bitmask);

DESCRIPTION
HSTS (HTTP Strict Transport Security) means that an HTTPS server can instruct the client to not contact it again over clear-text HTTP for a certain period into the future. libcurl then automatically redirects HTTP attempts to such hosts to instead use HTTPS. This is done by libcurl retaining this knowledge in an in-memory cache. Populate the long bitmask with the correct set of features to instruct libcurl how to handle HSTS for the transfers using this handle.

BITS

CURLHSTS_ENABLE
    Enable the in-memory HSTS cache for this handle.

CURLHSTS_READONLYFILE
    Make the HSTS file (if specified) read-only - makes libcurl not save the cache to the file when closing the handle.

DEFAULT
0

PROTOCOLS
This functionality affects http only

EXAMPLE
int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode result;
    /* enable HSTS */
    curl_easy_setopt(curl, CURLOPT_HSTS_CTRL, CURLHSTS_ENABLE);
    /* specify where to store the HSTS cache */
    curl_easy_setopt(curl, CURLOPT_HSTS, "/home/user/.hsts-cache");
    result = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}

AVAILABILITY
Added in curl 7.74.0

RETURN VALUE
curl_easy_setopt(3) returns a CURLcode indicating success or error. CURLE_OK (0) means everything was OK, non-zero means an error occurred, see libcurl-errors(3).

SEE ALSO
CURLOPT_ALTSVC(3), CURLOPT_CONNECT_TO(3), CURLOPT_HSTS(3), CURLOPT_RESOLVE(3)