gvproxy: add docker.internal dns entries

Some tools hard code the `host.docker.internal` dns name so it is not
possible to run them with podman right now. Adding the entry is simple
so we should support it for better compatibility.

Also remove the comment that podman depends on crc.testing, it does not
for a long time now. But because I do not know if crc needs it I left it
in there.

see containers/podman#19361

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

cmd/gvproxy/main.go

@@ -49,6 +49,9 @@ var (
 const (
 	gatewayIP   = "192.168.127.1"
 	sshHostPort = "192.168.127.2:22"
+	hostIP      = "192.168.127.254"
+	host        = "host"
+	gateway     = "gateway"
 )
 
 func main() {
@@ -187,25 +190,38 @@ func main() {
 				Name: "containers.internal.",
 				Records: []types.Record{
 					{
-						Name: "gateway",
+						Name: gateway,
 						IP:   net.ParseIP(gatewayIP),
 					},
 					{
-						Name: "host",
-						IP:   net.ParseIP("192.168.127.254"),
+						Name: host,
+						IP:   net.ParseIP(hostIP),
 					},
 				},
 			},
 			{
-				Name: "crc.testing.", // still used by current version of podman machine CNI
+				Name: "docker.internal.",
 				Records: []types.Record{
 					{
-						Name: "gateway",
+						Name: gateway,
 						IP:   net.ParseIP(gatewayIP),
 					},
 					{
-						Name: "host",
-						IP:   net.ParseIP("192.168.127.254"),
+						Name: host,
+						IP:   net.ParseIP(hostIP),
+					},
+				},
+			},
+			{
+				Name: "crc.testing.",
+				Records: []types.Record{
+					{
+						Name: gateway,
+						IP:   net.ParseIP(gatewayIP),
+					},
+					{
+						Name: host,
+						IP:   net.ParseIP(hostIP),
 					},
 				},
 			},
@@ -215,9 +231,9 @@ func main() {
 			fmt.Sprintf("127.0.0.1:%d", sshPort): sshHostPort,
 		},
 		NAT: map[string]string{
-			"192.168.127.254": "127.0.0.1",
+			hostIP: "127.0.0.1",
 		},
-		GatewayVirtualIPs: []string{"192.168.127.254"},
+		GatewayVirtualIPs: []string{hostIP},
 		VpnKitUUIDMacAddresses: map[string]string{
 			"c3d68012-0208-11ea-9fd7-f2189899ab08": "5a:94:ef:e4:0c:ee",
 		},