From 91a29e52551a1de72cff9c90abc925ce376e72b1 Mon Sep 17 00:00:00 2001
From: Max <max@privatevoid.net>
Date: Sun, 19 Jun 2022 14:04:46 +0200
Subject: [PATCH] services/dns: add DNS-over-TLS resolver

---
 hosts/VEGAS/services/dns/default.nix | 38 +++++++++++++++++++++++-----
 1 file changed, 31 insertions(+), 7 deletions(-)

diff --git a/hosts/VEGAS/services/dns/default.nix b/hosts/VEGAS/services/dns/default.nix
index 48b4a3a..aade8b0 100644
--- a/hosts/VEGAS/services/dns/default.nix
+++ b/hosts/VEGAS/services/dns/default.nix
@@ -1,16 +1,33 @@
-{ config, hosts, inputs, pkgs, ... }:
+{ config, hosts, inputs, pkgs, tools, ... }:
 # TODO: is this secure?
 let
   inherit (hosts.${config.networking.hostName}) interfaces;
+  inherit (tools.meta) domain;
+  dot = config.security.acme.certs."securedns.${domain}";
 in {
   imports = [ ./zones.nix ];
 
   networking.firewall = {
-    allowedTCPPorts = [ 53 ];
-    allowedUDPPorts = [ 53 ];
+    allowedTCPPorts = [ 53 853 ];
+    allowedUDPPorts = [ 53 853 ];
   };
 
-  systemd.services.coredns.after = [ "network-addresses-vstub.service" ];
+  systemd.services.coredns = {
+    after = [ "network-addresses-vstub.service" ];
+    serviceConfig.LoadCredential = [
+      "dot-cert.pem:${dot.directory}/fullchain.pem"
+      "dot-key.pem:${dot.directory}/key.pem"
+    ];
+  };
+  security.acme.certs."securedns.${domain}" = {
+    group = "nginx";
+    webroot = "/var/lib/acme/acme-challenge";
+    # using a different ACME provider because Android Private DNS is fucky
+    server = "https://api.buypass.com/acme/directory";
+    reloadServices = [
+      "coredns.service"
+    ];
+  };
   services.coredns = {
     enable = true;
     config = ''
@@ -22,6 +39,15 @@ in {
         chaos "Private Void DNS" info@privatevoid.net
         forward . 127.0.0.1
       }
+      tls://.:853 {
+        bind ${interfaces.primary.addr}
+        tls {$CREDENTIALS_DIRECTORY}/dot-cert.pem {$CREDENTIALS_DIRECTORY}/dot-key.pem
+        hosts ${inputs.self.packages.${pkgs.system}.stevenblack-hosts} {
+          fallthrough
+        }
+        chaos "Private Void DNS" info@privatevoid.net
+        forward . ${interfaces.primary.addr}
+      }
     '';
   };
 
@@ -36,19 +62,17 @@ in {
       acl "trusted" {
         127.0.0.0/8;
         ::1/128;
-        ${interfaces.primary.addr}/32;
         ${interfaces.vstub.addr}/32;
         10.100.0.0/16;
         10.10.0.0/16;
       };
       acl "publicservers" {
-        ${interfaces.primary.addr}/32;
         116.202.226.86/32;
       };
     '';
     extraOptions = ''
       recursion yes;
-      allow-recursion { trusted; };
+      allow-recursion { trusted; ${interfaces.primary.addr}/32; };
       dnssec-validation no;
     '';
   };