tv im: add mosh support

tv/3modules/im.nix

@@ -29,6 +29,9 @@ in {
       default = config.krebs.hosts.nomic;
       type = lib.types.host;
     };
+    tv.im.server.mosh.enable = lib.mkEnableOption "tv.im.server.mosh" // {
+      default = true;
+    };
     tv.im.server.user = lib.mkOption {
       default = config.krebs.users.tv;
       type = lib.types.user;
@@ -38,11 +41,18 @@ in {
     (lib.mkIf im.client.enable {
       users.users.${im.client.user.name}.packages = [
         (pkgs.writeDashBin "im" ''
-          exec ${pkgs.openssh}/bin/ssh \
+          ${if im.server.mosh.enable then /* sh */ ''
-              ${lib.optionalString im.client.useIPv6 "-6"} \
+            exec ${pkgs.mosh}/bin/mosh \
-              ${im.server.user.name}@${lib.head im.server.host.nets.retiolum.aliases} \
+                ${lib.optionalString im.client.useIPv6 "-6"} \
-              -t \
+                ${im.server.user.name}@${lib.head im.server.host.nets.retiolum.aliases} \
-              im
+                env TERM=${im.client.term} im
+          '' else /* sh */ ''
+            exec ${pkgs.openssh}/bin/ssh \
+                ${lib.optionalString im.client.useIPv6 "-6"} \
+                ${im.server.user.name}@${lib.head im.server.host.nets.retiolum.aliases} \
+                -t \
+                im
+          ''}
         '')
       ];
     })
@@ -54,6 +64,7 @@ in {
         ];
       };
       users.users.${im.server.user.name}.packages = [
+        pkgs.mosh
         (pkgs.writeDashBin "im" ''
           export PATH=${lib.makeSearchPath "bin" [
             pkgs.tmux
@@ -68,5 +79,19 @@ in {
         '')
       ];
     })
+    (lib.mkIf im.server.mosh.enable {
+      krebs.setuid.utempter = {
+        filename = "${pkgs.libutempter}/lib/utempter/utempter";
+        owner = "nobody";
+        group = "utmp";
+        mode = "2111";
+      };
+      tv.iptables.extra4.filter.Retiolum = [
+        "-s ${im.client.host.nets.retiolum.ip4.addr} -p udp --dport 60000:61000 -j ACCEPT"
+      ];
+      tv.iptables.extra6.filter.Retiolum = [
+        "-s ${im.client.host.nets.retiolum.ip6.addr} -p udp --dport 60000:61000 -j ACCEPT"
+      ];
+    })
   ];
 }