add onlink network config support

Author: Plopmenz

os/flake.nix

@@ -232,6 +232,7 @@
                       (route: {
                         destination = if (route.dst == "default") then "0.0.0.0/0" else route.dst;
                         gateway = route.gateway;
+                        onlink = builtins.elem "onlink" route.flags;
                       })
                       (
                         builtins.filter (
@@ -251,6 +252,7 @@
                     routes = builtins.map (route: {
                       Destination = route.destination;
                       Gateway = route.gateway;
+                      GatewayOnLink = if (route.onlink) then "yes" else "no";
                     }) interface.value.route;
                   };
                 }) network-config

os/installer/kexec.nix

@@ -123,7 +123,13 @@
                 continue
             fi
 
-            config="$(echo $route | jq -r '.dst') via $(echo $route | jq -r '.gateway')"
+            args=""
+            flags=$(echo "$route" | jq -r '.flags')
+            if [[ $flags == *"onlink"* ]]; then
+              args="$args onlink"
+            fi
+
+            config="$(echo $route | jq -r '.dst') via $(echo $route | jq -r '.gateway') $args"
             ip route add $config dev $name
           done
         done