tv dnsmasq service: init

tv/3modules/default.nix

@@ -1,6 +1,7 @@
 {
   imports = [
     ./charybdis
+    ./dnsmasq.nix
     ./ejabberd
     ./hosts.nix
     ./iptables.nix

tv/3modules/dnsmasq.nix

@@ -0,0 +1,57 @@
+with import <stockholm/lib>;
+{ config, ... }: let
+  cfg = config.tv.dnsmasq;
+in {
+
+  options.tv.dnsmasq = {
+    enable = mkEnableOption "tv.dnsmasq";
+    dhcp-range = mkOption {
+      type = types.str;
+    };
+    interface = mkOption {
+      type = types.str;
+    };
+    address = mkOption {
+      type = types.str;
+    };
+    prefixLength = mkOption {
+      type = types.addCheck types.int (x: x >= 0 && x <= 32);
+    };
+  };
+
+  config = mkIf cfg.enable (mkMerge [
+    {
+      networking.dhcpcd.denyInterfaces = [ cfg.interface ];
+      services.dnsmasq.resolveLocalQueries = false;
+      networking.interfaces.${cfg.interface} = {
+        ipv4.addresses = singleton {
+          address = cfg.address;
+          prefixLength = cfg.prefixLength;
+        };
+      };
+      services.dnsmasq.enable = true;
+      services.dnsmasq.extraConfig = ''
+        dhcp-range=${cfg.dhcp-range}
+        interface=${cfg.interface}
+      '';
+      tv.iptables.extra.filter.INPUT = [
+        "-i ${cfg.interface} -p tcp -m tcp --dport bootps -j ACCEPT"
+        "-i ${cfg.interface} -p udp -m udp --dport bootps -j ACCEPT"
+        "-i ${cfg.interface} -p tcp -m tcp --dport domain -j ACCEPT"
+        "-i ${cfg.interface} -p udp -m udp --dport domain -j ACCEPT"
+      ];
+    }
+    {
+      # enable forwarding
+      boot.kernel.sysctl."net.ipv4.ip_forward" = true;
+      tv.iptables.extra.filter.FORWARD = [
+        "-m state --state RELATED,ESTABLISHED -j ACCEPT"
+        "-i ${cfg.interface} -j ACCEPT"
+      ];
+      tv.iptables.extra.nat.POSTROUTING = [
+        "-j MASQUERADE"
+      ];
+    }
+  ]);
+
+}