CURLOPT_HSTS_CTRL(3) Introduction to Library Functions CURLOPT_HSTS_CTRL(3)

NAME

CURLOPT_HSTS_CTRL - control HSTS behavior

SYNOPSIS

#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);

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

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)

libcurl 2025-02-25 CURLOPT_HSTS_CTRL(3)