CURLOPT_HSTS_CTRL(3) Library Functions Manual CURLOPT_HSTS_CTRL(3) NAME CURLOPT_HSTS_CTRL - control HSTS behavior SYNOPSIS #include #define CURLHSTS_ENABLE (1<<0) #define CURLHSTS_READONLYFILE (1<<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) { curl_easy_setopt(curl, CURLOPT_HSTS_CTRL, (long)CURLHSTS_ENABLE); curl_easy_perform(curl); } } AVAILABILITY Added in curl 7.74.0 RETURN VALUE Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not. SEE ALSO CURLOPT_ALTSVC(3), CURLOPT_CONNECT_TO(3), CURLOPT_HSTS(3), CURLOPT_RESOLVE(3) libcurl 2024-11-07 CURLOPT_HSTS_CTRL(3)