feat: write dnscrypt configuration

modules/security/dnscrypt.nix

@@ -0,0 +1,56 @@
+{
+  config,
+  lib,
+  pkgs,
+  inputs,
+  host,
+  ...
+}:
+let
+  ipv6 = false; # We don't have IPv6 yet sadly
+  blocklist_base = builtins.readFile inputs.oisd;
+  extraBlocklist = '''';
+  blocklist_txt = pkgs.writeText "blocklist.txt" ''
+    ${extraBlocklist}
+    ${blocklist_base}
+  '';
+in
+{
+  services.dnscrypt-proxy = {
+    enable = true;
+    # See https://github.com/DNSCrypt/dnscrypt-proxy/blob/master/dnscrypt-proxy/example-dnscrypt-proxy.toml
+    settings = {
+      sources.public-resolvers = {
+        urls = [
+          "https://raw.githubusercontent.com/DNSCrypt/dnscrypt-resolvers/master/v3/public-resolvers.md"
+          "https://download.dnscrypt.info/resolvers-list/v3/public-resolvers.md"
+        ];
+        minisign_key = "sha256-6MVFxJJF/mwjWtCJ77s0YUYWm2rMTvnycHGya2JNGEE="; # See https://github.com/DNSCrypt/dnscrypt-resolvers/blob/master/v3/public-resolvers.md
+        cache_file = "/var/lib/dnscrypt/public-resolvers.md";
+      };
+
+      # Use servers reachable over IPv6 -- Do not enable if you don't have IPv6 connectivity
+      ipv6_servers = ipv6;
+      block_ipv6 = !(ipv6);
+
+      require_dnssec = true;
+      require_nolog = true;
+      require_nofilter = true;
+
+      # If you want, choose a specific set of servers that come from your sources.
+      # Here it's from https://github.com/DNSCrypt/dnscrypt-resolvers/blob/master/v3/public-resolvers.md
+      # If you don't specify any, dnscrypt-proxy will automatically rank servers
+      # that match your criteria and choose the best one.
+      # server_names = [ ... ];
+      blocked_names.blocked_names_file = blocklist_txt;
+    };
+  };
+
+  systemd.services.dnscrypt-proxy.serviceConfig.StateDirectory = "dnscrypt-proxy";
+
+  networking.networkmanager.dns = "none"; # set system DNS to not get random records from DHCP
+  programs.captive-browser = {
+    enable = true; # enable dedicated Chromium instance to deal with captive portals without messing with system DNS settings
+    interface = if (host == "sakura") then "wlp1s0" else "null"; # TODO: add hostnames for more devices
+  };
+}