curl/docs/libcurl/opts/CURLOPT_HSTS_CTRL.md
Daniel Stenberg eefcc1bda4
docs: introduce "curldown" for libcurl man page format
curldown is this new file format for libcurl man pages. It is markdown
inspired with differences:

- Each file has a set of leading headers with meta-data
- Supports a small subset of markdown
- Uses .md file extensions for editors/IDE/GitHub to treat them nicely
- Generates man pages very similar to the previous ones
- Generates man pages that still convert nicely to HTML on the website
- Detects and highlights mentions of curl symbols automatically (when
  their man page section is specified)

tools:

- cd2nroff: converts from curldown to nroff man page
- nroff2cd: convert an (old) nroff man page to curldown
- cdall: convert many nroff pages to curldown versions
- cd2cd: verifies and updates a curldown to latest curldown

This setup generates .3 versions of all the curldown versions at build time.

CI:

Since the documentation is now technically markdown in the eyes of many
things, the CI runs many more tests and checks on this documentation,
including proselint, link checkers and tests that make sure we capitalize the
first letter after a period...

Closes #12730
2024-01-23 00:29:02 +01:00

79 lines
1.6 KiB
Markdown

---
c: Copyright (C) Daniel Stenberg, <daniel.se>, et al.
SPDX-License-Identifier: curl
Title: CURLOPT_HSTS_CTRL
Section: 3
Source: libcurl
See-also:
- CURLOPT_ALTSVC (3)
- CURLOPT_CONNECT_TO (3)
- CURLOPT_HSTS (3)
- CURLOPT_RESOLVE (3)
---
# NAME
CURLOPT_HSTS_CTRL - control HSTS behavior
# SYNOPSIS
~~~c
#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. HSTS is disabled by default.
# PROTOCOLS
HTTPS and HTTP
# EXAMPLE
~~~c
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 7.74.0
# RETURN VALUE
Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.