network.interfaces: Add option to configure WakeOnLan policy

Adds an option to configure a custom WakeOnLan policy instead of the
hard-coded "magic" policy. To ensure compatibility with current
behavior, "magic" is kept as default.

nixos/modules/tasks/network-interfaces.nix

@@ -327,6 +327,24 @@ let
           default = false;
           description = lib.mdDoc "Whether to enable wol on this interface.";
         };
+        policy = mkOption {
+          type = with types; listOf (
+            enum ["phy" "unicast" "multicast" "broadcast" "arp" "magic" "secureon"]
+          );
+          default = ["magic"];
+          description = lib.mdDoc ''
+            The [Wake-on-LAN policy](https://www.freedesktop.org/software/systemd/man/systemd.link.html#WakeOnLan=)
+            to set for the device.
+
+            The options are
+            - `phy`: Wake on PHY activity
+            - `unicast`: Wake on unicast messages
+            - `multicast`: Wake on multicast messages
+            - `broadcast`: Wake on broadcast messages
+            - `arp`: Wake on ARP
+            - `magic`: Wake on receipt of a magic packet
+          '';
+        };
       };
     };