GNURLOPT_DOH_URL(3)

💖 GNURLOPT_DOH_URL(3) — the DNS-over-HTTPS URL one 💖

okay so bestie, this page is GNURLOPT_DOH_URL(3) from the curl_easy_setopt options manual family, and it's literally all about giving your DNS queries a ✨glow-up✨ by routing them through a DNS-over-HTTPS server. ngl, it's giving secure, it's giving private, it's giving main character energy for your resolver.

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🌸 NAME 🌸

CURLOPT_DOH_URL — provide the DNS-over-HTTPS URL 🦋

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✨ SYNOPSIS ✨

#include <gnurl/curl.h>

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

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💅 DESCRIPTION 💅

so you pass in a pointer to a URL for the DOH server to use for name resolving, and that's the whole vibe. the parameter should be a char * to a null-terminated string, and it must be URL-encoded in literally this exact format: "https://host:port/path". like, it MUST specify a HTTPS URL — no exceptions, no shortcuts, periodt. 🔥

here's the tea though: libcurl doesn't validate the syntax or even use this variable until the transfer is issued. so even if you set a crazy value here (and bestie, you could set the most unhinged string imaginable), curl_easy_setopt(3) will still return CURLE_OK. it's not being shady, it's just not checking yet. 😭

curl sends POST requests to the given DNS-over-HTTPS URL.

now, 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). iykyk, that's the little chicken-and-egg moment and this is how you solve it. 🐣

disable DOH use again by setting this option to NULL. bye bye, DOH era. 👋

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🎀 DEFAULT 🎀

NULL — there is no default DOH URL. if this option isn't set, libcurl will use the default name resolver. no DOH, no drama, just the classic. 💜

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🌈 PROTOCOLS 🌈

All 🫶

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🍓 EXAMPLE 🍓

CURL *curl = curl_easy_init();
if(curl) {
  curl_easy_setopt(curl, CURLOPT_URL, "http://example.com");
  curl_easy_setopt(curl, CURLOPT_DOH_URL, "https://dns.example.com");
  curl_easy_perform(curl);
}

look at that. iconic. CURLOPT_URL for the actual destination, CURLOPT_DOH_URL for the fancy DNS-over-HTTPS server, and then curl_easy_perform(curl) to make it all happen. chef's kiss. 👑

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⭐ AVAILABILITY ⭐

Added in 7.62.0 — she's not ancient, she's not brand new, she's just right. 💫

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💀 RETURN VALUE 💀

Returns CURLE_OK on success, or CURLE_OUT_OF_MEMORY if there was insufficient heap space. like, your memory said "i simply cannot" and honestly? relatable. 🙈

⚠️ also note (and this is lowkey important): curl_easy_setopt(3) won't actually parse the given string, so if you hand it a bad DOH URL, curl will not detect a problem until it tries to resolve a name with it. so the error shows up fashionably late. 😭

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🔥 SEE ALSO 🔥

• CURLOPT_VERBOSE(3)
• CURLOPT_RESOLVE(3)

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and that's the whole page bestie, go forth and resolve responsibly 💖✨

sign-off tea: this beauty is from libcurl 7.62.0, dated 18 Jun 2018, and the page itself is GNURLOPT_DOH_URL(3). slay. 🎀🦋