dhcpd service: add DHCPv6 support

nixos/modules/rename.nix

@@ -164,6 +164,9 @@ with lib;
         else { addr = value inetAddr; port = value inetPort; }
     ))
 
+    # dhcpd
+    (mkRenamedOptionModule [ "services" "dhcpd" ] [ "services" "dhcpd4" ])
+
     # Options that are obsolete and have no replacement.
     (mkRemovedOptionModule [ "boot" "initrd" "luks" "enable" ] "")
     (mkRemovedOptionModule [ "programs" "bash" "enable" ] "")

nixos/modules/services/networking/dhcpd.nix

@@ -4,11 +4,10 @@ with lib;
 
 let
 
-  cfg = config.services.dhcpd;
+  cfg4 = config.services.dhcpd4;
+  cfg6 = config.services.dhcpd6;
 
-  stateDir = "/var/lib/dhcp"; # Don't use /var/state/dhcp; not FHS-compliant.
+  writeConfig = cfg: pkgs.writeText "dhcpd.conf"
-
-  configFile = if cfg.configFile != null then cfg.configFile else pkgs.writeText "dhcpd.conf"
     ''
       default-lease-time 600;
       max-lease-time 7200;
@@ -29,21 +28,85 @@ let
       }
     '';
 
-in
+  dhcpdService = postfix: cfg: optionalAttrs cfg.enable {
+    "dhcpd${postfix}" = {
+      description = "DHCPv${postfix} server";
+      wantedBy = [ "multi-user.target" ];
+      after = [ "network.target" ];
 
-{
+      preStart = ''
+        mkdir -m 755 -p ${cfg.stateDir}
+        touch ${cfg.stateDir}/dhcpd.leases
+      '';
 
-  ###### interface
+      serviceConfig =
+        let
+          configFile = if cfg.configFile != null then cfg.configFile else writeConfig cfg;
+          args = [ "@${pkgs.dhcp}/sbin/dhcpd" "dhcpd${postfix}" "-${postfix}"
+                   "-pf" "/run/dhcpd${postfix}/dhcpd.pid"
+                   "-cf" "${configFile}"
+                   "-lf" "${cfg.stateDir}/dhcpd.leases"
+                   "-user" "dhcpd" "-group" "nogroup"
+                 ] ++ cfg.extraFlags
+                   ++ cfg.interfaces;
 
-  options = {
+        in {
+          ExecStart = concatMapStringsSep " " escapeShellArg args;
+          Type = "forking";
+          Restart = "always";
+          RuntimeDirectory = [ "dhcpd${postfix}" ];
+          PIDFile = "/run/dhcpd${postfix}/dhcpd.pid";
+        };
+    };
+  };
 
-    services.dhcpd = {
+  machineOpts = {...}: {
+    config = {
+
+      hostName = mkOption {
+        type = types.str;
+        example = "foo";
+        description = ''
+          Hostname which is assigned statically to the machine.
+        '';
+      };
+
+      ethernetAddress = mkOption {
+        type = types.str;
+        example = "00:16:76:9a:32:1d";
+        description = ''
+          MAC address of the machine.
+        '';
+      };
+
+      ipAddress = mkOption {
+        type = types.str;
+        example = "192.168.1.10";
+        description = ''
+          IP address of the machine.
+        '';
+      };
+
+    };
+  };
+
+  dhcpConfig = postfix: {
 
     enable = mkOption {
+      type = types.bool;
       default = false;
-        description = "
+      description = ''
-          Whether to enable the DHCP server.
+        Whether to enable the DHCPv${postfix} server.
-        ";
+      '';
+    };
+
+    stateDir = mkOption {
+      type = types.path;
+      # We use /var/lib/dhcp for DHCPv4 to save backwards compatibility.
+      default = "/var/lib/dhcp${if postfix == "4" then "" else postfix}";
+      description = ''
+        State directory for the DHCP server.
+      '';
     };
 
     extraConfig = mkOption {
@@ -59,38 +122,41 @@ in
           range 192.168.1.100 192.168.1.200;
         }
       '';
-        description = "
+      description = ''
         Extra text to be appended to the DHCP server configuration
-          file.  Currently, you almost certainly need to specify
+        file. Currently, you almost certainly need to specify something
-          something here, such as the options specifying the subnet
+        there, such as the options specifying the subnet mask, DNS servers,
-          mask, DNS servers, etc.
+        etc.
-        ";
+      '';
     };
 
     extraFlags = mkOption {
-        default = "";
+      type = types.listOf types.str;
-        example = "-6";
+      default = [];
-        description = "
+      description = ''
         Additional command line flags to be passed to the dhcpd daemon.
-        ";
+      '';
     };
 
     configFile = mkOption {
+      type = types.nullOr types.path;
       default = null;
-        description = "
+      description = ''
         The path of the DHCP server configuration file.  If no file
         is specified, a file is generated using the other options.
-        ";
+      '';
     };
 
     interfaces = mkOption {
+      type = types.listOf types.str;
       default = ["eth0"];
-        description = "
+      description = ''
         The interfaces on which the DHCP server should listen.
-        ";
+      '';
     };
 
     machines = mkOption {
+      type = types.listOf (types.submodule machineOpts);
       default = [];
       example = [
         { hostName = "foo";
@@ -102,20 +168,31 @@ in
           ipAddress = "192.168.1.11";
         }
       ];
-        description = "
+      description = ''
-          A list mapping ethernet addresses to IP addresses for the
+        A list mapping Ethernet addresses to IPv${postfix} addresses for the
         DHCP server.
-        ";
+      '';
     };
 
   };
 
+in
+
+{
+
+  ###### interface
+
+  options = {
+
+    services.dhcpd4 = dhcpConfig "4";
+    services.dhcpd6 = dhcpConfig "6";
+
   };
 
 
   ###### implementation
 
-  config = mkIf config.services.dhcpd.enable {
+  config = mkIf (cfg4.enable || cfg6.enable) {
 
     users = {
       extraUsers.dhcpd = {
@@ -124,36 +201,7 @@ in
       };
     };
 
-    systemd.services.dhcpd =
+    systemd.services = dhcpdService "4" cfg4 // dhcpdService "6" cfg6;
-      { description = "DHCP server";
-
-        wantedBy = [ "multi-user.target" ];
-
-        after = [ "network.target" ];
-
-        path = [ pkgs.dhcp ];
-
-        preStart =
-          ''
-            mkdir -m 755 -p ${stateDir}
-
-            touch ${stateDir}/dhcpd.leases
-
-            mkdir -m 755 -p /run/dhcpd
-            chown dhcpd /run/dhcpd
-          '';
-
-        serviceConfig =
-          { ExecStart = "@${pkgs.dhcp}/sbin/dhcpd dhcpd"
-              + " -pf /run/dhcpd/dhcpd.pid -cf ${configFile}"
-              + " -lf ${stateDir}/dhcpd.leases -user dhcpd -group nogroup"
-              + " ${cfg.extraFlags}"
-              + " ${toString cfg.interfaces}";
-            Restart = "always";
-            Type = "forking";
-            PIDFile = "/run/dhcpd/dhcpd.pid";
-          };
-      };
 
   };