cmd/vnet: add wsproxy mode

For hooking up websocket VM clients to natlab.

Updates #13038

Change-Id: Iaf728b9146042f3d0c2d3a5e25f178646dd10951
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

tstest/natlab/vnet/conf.go

@@ -121,6 +121,8 @@ func (c *Config) AddNode(opts ...any) *Node {
 					n.err = fmt.Errorf("unknown NodeOption %q", o)
 				}
 			}
+		case MAC:
+			n.mac = o
 		default:
 			if n.err == nil {
 				n.err = fmt.Errorf("unknown AddNode option type %T", o)

tstest/natlab/vnet/vnet.go

@@ -88,6 +88,9 @@ func (s *Server) PopulateDERPMapIPs() error {
 			if n.IPv4 != "" {
 				s.derpIPs.Add(netip.MustParseAddr(n.IPv4))
 			}
+			if n.IPv6 != "" {
+				s.derpIPs.Add(netip.MustParseAddr(n.IPv6))
+			}
 		}
 	}
 	return nil