fix ipv4 via ipv6 route

fix #230

nix/kexec-installer/restore_routes.py

@@ -63,6 +63,12 @@ def generate_networkd_units(
                 # can be skipped for default routes
                 route_section += f"Destination = {route['dst']}\n"
             gateway = route.get("gateway")
+            # route v4 via v6
+            route_via = route.get("via")
+            if route_via and route_via.get("family") == "inet6":
+                gateway = route_via.get("host")
+                if route.get("dst") == "default":
+                    route_section += "Destination = 0.0.0.0/0\n"
             if gateway:
                 route_section += f"Gateway = {gateway}\n"
 

nix/kexec-installer/test.nix

@@ -58,6 +58,7 @@ makeTest' {
               # Some static routes that we want to see in the kexeced image
               { routeConfig = { Destination = "192.168.43.0/24"; }; }
               { routeConfig = { Destination = "192.168.44.0/24"; Gateway = "192.168.43.1"; }; }
+              { routeConfig = { Destination = "192.168.45.0/24"; Gateway = "43::1"; }; }
               { routeConfig = { Destination = "43::0/64"; }; }
               { routeConfig = { Destination = "44::1/64"; Gateway = "43::1"; }; }
             ];
@@ -68,7 +69,7 @@ makeTest' {
     };
   };
 
-  testScript = ''
+  testScript = /*python*/ ''
     import time
     import subprocess
     import socket
@@ -185,6 +186,10 @@ makeTest' {
     print(out)
     assert "192.168.44.2 via 192.168.43.1" in out, f"route to `192.168.44.2 via 192.168.43.1` not found: {out}"
 
+    out = ssh(["ip", "route", "get", "192.168.45.2"], stdout=subprocess.PIPE).stdout
+    print(out)
+    assert "192.168.45.2 via inet6 43::1" in out, f"route to `192.168.45.2 via inet6 43::1` not found: {out}"
+
     out = ssh(["ip", "route", "get", "43::2"], stdout=subprocess.PIPE).stdout
     print(out)
     assert "43::2 from :: dev" in out, f"route `43::2 from dev` not found: {out}"