curl/docs/libcurl/opts/CURLOPT_DOH_URL.md
Daniel Stenberg 5a488251f7
curldown: fixups
- make DEFAULT sections less repetitive

- make historic mentions use HISTORY

- generate the protocols section on `# %PROTOCOLS%` instead of guessing
  where to put it

- generate the availability section on `# %AVAILABILITY%` instead of
  guessing where to put it

- make the protocols section more verbose

Closes #14227
2024-07-19 17:03:25 +02:00

95 lines
2.4 KiB
Markdown

---
c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
SPDX-License-Identifier: curl
Title: CURLOPT_DOH_URL
Section: 3
Source: libcurl
See-also:
- CURLOPT_DNS_CACHE_TIMEOUT (3)
- CURLOPT_RESOLVE (3)
- CURLOPT_VERBOSE (3)
Protocol:
- All
Added-in: 7.62.0
---
# NAME
CURLOPT_DOH_URL - provide the DNS-over-HTTPS URL
# SYNOPSIS
~~~c
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_DOH_URL, char *URL);
~~~
# DESCRIPTION
Pass in a pointer to a *URL* for the DoH server to use for name resolving. The
parameter should be a char pointer to a null-terminated string which must be a
valid and correct HTTPS URL.
libcurl does not validate the syntax or use this variable until the transfer
is issued. Even if you set a crazy value here, curl_easy_setopt(3) still
returns *CURLE_OK*.
curl sends POST requests to the given DNS-over-HTTPS URL.
To find the DoH server itself, which might be specified using a name, libcurl
uses the default name lookup function. You can bootstrap that by providing the
address for the DoH server with CURLOPT_RESOLVE(3).
Disable DoH use again by setting this option to NULL.
# INHERIT OPTIONS
DoH lookups use SSL and some SSL settings from your transfer are inherited,
like CURLOPT_SSL_CTX_FUNCTION(3).
The hostname and peer certificate verification settings are not inherited but
can be controlled separately via CURLOPT_DOH_SSL_VERIFYHOST(3) and
CURLOPT_DOH_SSL_VERIFYPEER(3).
A set CURLOPT_OPENSOCKETFUNCTION(3) callback is not inherited.
# KNOWN BUGS
Even when DoH is set to be used with this option, there are still some name
resolves that are performed without it, using the default name resolver
mechanism. This includes name resolves done for CURLOPT_INTERFACE(3),
CURLOPT_FTPPORT(3), a proxy type set to **CURLPROXY_SOCKS4** or
**CURLPROXY_SOCKS5** and probably some more.
# DEFAULT
NULL
# %PROTOCOLS%
# EXAMPLE
~~~c
int main(void)
{
CURL *curl = curl_easy_init();
if(curl) {
curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
curl_easy_setopt(curl, CURLOPT_DOH_URL, "https://dns.example.com");
curl_easy_perform(curl);
}
}
~~~
# %AVAILABILITY%
# RETURN VALUE
Returns CURLE_OK on success or CURLE_OUT_OF_MEMORY if there was insufficient
heap space.
Note that curl_easy_setopt(3) does immediately parse the given string so
when given a bad DoH URL, libcurl might not detect the problem until it later
tries to resolve a name with it.