Manpages - CURLOPT_DOH_URL.3

CURLOPT_DOH_URL - provide the DNS-over-HTTPS URL

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_DOH_URL, char *URL);

Pass in a pointer to a URL for the DoH server to use for name resolving. The parameter should be a char * to a null-terminated string which must be URL-encoded in the following format: “https://host:port/path”. It MUST specify a 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) will still return 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 will use 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.

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.

NULL - there is no default DoH URL. If this option is not set, libcurl will use the default name resolver.

All

  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);
  }

Added in 7.62.0

Returns CURLE_OK on success or CURLE_OUT_OF_MEMORY if there was insufficient heap space.

Note that curl_easy_setopt(3) will not actually parse the given string so given a bad DoH URL, curl will not detect a problem until it tries to resolve a name with it.

*CURLOPT_VERBOSE*(3), *CURLOPT_RESOLVE*(3),