Manpages - CURLOPT_HSTS_CTRL.3

CURLOPT_HSTS_CTRL - control HSTS behavior

  #include <curl/curl.h>

  #define CURLHSTS_ENABLE       (1<<0)
  #define CURLHSTS_READONLYFILE (1<<1)

  CURLcode curl_easy_setopt(CURL *handle, CURLOPT_HSTS_CTRL, long bitmask);

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 will then automatically redirect 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.

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.

1. HSTS is disabled by default.

HTTPS and HTTP

  CURL *curl = curl_easy_init();
  if(curl) {
    curl_easy_setopt(curl, CURLOPT_HSTS_CTRL, CURLHSTS_ENABLE);
    curl_easy_perform(curl);
  }

Added in 7.74.0

Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.

*CURLOPT_HSTS*(3), *CURLOPT_CONNECT_TO*(3), *CURLOPT_RESOLVE*(3), *CURLOPT_ALTSVC*(3),