CURLOPT_HSTS_CTRL

Section: curl_easy_setopt options (3)
Updated: November 04, 2020
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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);

EXPERIMENTAL

Warning: this feature is early code and is marked as experimental. It can only be enabled by explicitly telling configure with --enable-hsts. You are advised to not ship this in production before the experimental label is removed.

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 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.

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. HSTS is disabled by default.

PROTOCOLS

HTTPS and HTTP

EXAMPLE

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

AVAILABILITY

Added in 7.74.0

RETURN VALUE

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