nixos/tayga: add log option

This allows configuring logging in tayga, and enables it for the NixOS
test.

nixos/modules/services/networking/tayga.nix

@@ -23,6 +23,10 @@ let
     data-dir ${cfg.dataDir}
 
     ${concatStringsSep "\n" (mapAttrsToList (ipv4: ipv6: "map " + ipv4 + " " + ipv6) cfg.mappings)}
+
+    ${optionalString ((builtins.length cfg.log) > 0) ''
+      log ${concatStringsSep " " cfg.log}
+    ''}
   '';
 
   addrOpts =
@@ -132,6 +136,15 @@ in
           }
         '';
       };
+
+      log = mkOption {
+        type = types.listOf types.str;
+        default = [ ];
+        description = "Packet errors to log (drop, reject, icmp, self)";
+        example = literalExpression ''
+          [ "drop" "reject" "icmp" "self" ]
+        '';
+      };
     };
   };
 

nixos/tests/tayga.nix

@@ -139,6 +139,12 @@
         mappings = {
           "192.0.2.42" = "2001:db8::2";
         };
+        log = [
+          "drop"
+          "reject"
+          "icmp"
+          "self"
+        ];
       };
       environment.systemPackages = [ pkgs.tcpdump ];
     };
@@ -205,6 +211,12 @@
         mappings = {
           "192.0.2.42" = "2001:db8::2";
         };
+        log = [
+          "drop"
+          "reject"
+          "icmp"
+          "self"
+        ];
       };
       environment.systemPackages = [ pkgs.tcpdump ];
     };