policyrouting: Move ip rule magic to a dedicated module

modules/uplink-selector/default.nix

@@ -6,35 +6,6 @@ let
 
   cfg = config.clerie.uplink-selector;
 
-  startScript = pkgs.writeScriptBin "uplink-selector-start" ''
-    #! ${pkgs.runtimeShell} -e
-
-    ip46() {
-      ip "$@"
-      ip -6 "$@"
-    }
-
-    ip46 rule flush || true
-
-    # Route everything except default route first
-    ip46 rule add lookup main suppress_prefixlength 0 prio 10000
-
-    # Decide which uplink to use
-    ${concatStrings (mapAttrsToList (iface: ifacecfg: ''
-      ip46 rule add iif ${iface} lookup ${cfg.uplinks.${ifacecfg.uplink}.table} prio 20000
-    '') cfg.interfaces)}
-
-    # Fallback to the main default table
-    ip46 rule add lookup main prio 32000
-  '';
-
-  stopScript = pkgs.writeScriptBin "uplink-selector-stop" ''
-    #! ${pkgs.runtimeShell} -e
-
-    ip rule flush || true
-    ip -6 rule flush || true
-  '';
-
 in
 
 {
@@ -90,25 +61,14 @@ in
 
   config = mkIf cfg.enable {
 
-    environment.systemPackages = [ pkgs.iproute2 ];
+    clerie.policyrouting.enable = true;
 
-    systemd.services.uplink-selector = {
-      description = "Uplink Selector";
-      before = [ "network.target" ];
-      wantedBy = [ "network.target" ];
-      after = [ "network-pre.target" ];
+    clerie.policyrouting.rules = [
+      { rule = "lookup main suppress_prefixlength 0"; prio = 10000; }
+    ] ++ (mapAttrsToList (iface: ifacecfg: {
+      rule = "iif ${iface} lookup ${cfg.uplinks.${ifacecfg.uplink}.table}"; prio = 20000;
+    }) cfg.interfaces);
 
-      path = [ pkgs.iproute2 ];
-
-      unitConfig.ConditionCapability = "CAP_NET_ADMIN";
-
-      serviceConfig = {
-        Type = "oneshot";
-        RemainAfterExit = true;
-        ExecStart = "@${startScript}/bin/uplink-selector-start uplink-selector-start";
-        ExecStop = "@${stopScript}/bin/uplink-selector-stop uplink-selector-stop";
-      };
-    };
   };
 
 }