CURLOPT_DOH_URL

Section: curl_easy_setopt options (3)
Updated: March 04, 2021
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NAME

CURLOPT_DOH_URL - provide the DNS-over-HTTPS URL

SYNOPSIS

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 * 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 doesn't 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.

Advanced: The DOH lookups use SSL so some SSL settings from your transfer are inherited. The hostname and peer certificate verification settings are not inherited and can be controlled separately via CURLOPT_DOH_SSL_VERIFYHOST(3) and CURLOPT_DOH_SSL_VERIFYPEER(3). Note CURLOPT_SSL_CTX_FUNCTION(3) is inherited.

DEFAULT

NULL - there is no default DOH URL. If this option isn't set, libcurl will use the default name resolver.

PROTOCOLS

All

EXAMPLE

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

Added in 7.62.0

RETURN VALUE

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

Note that curl_easy_setopt(3) won't 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.