Assume mDNS candidates are UDPv4 until parsed

Otherwise we are unable to handle remote candidates

candidate_test.go

@@ -274,6 +274,16 @@ func TestCandidateMarshal(t *testing.T) {
 			"1052353102 1 tcp 2128609279 192.168.0.196 0 typ host tcptype active",
 			false,
 		},
+		{&CandidateHost{
+			candidateBase{
+				networkType:   NetworkTypeUDP4,
+				candidateType: CandidateTypeHost,
+				address:       "e2494022-4d9a-4c1e-a750-cc48d4f8d6ee.local",
+				port:          60542,
+			},
+			"",
+		},
+			"1380287402 1 udp 2130706431 e2494022-4d9a-4c1e-a750-cc48d4f8d6ee.local 60542 typ host", false},
 
 		// Invalid candidates
 		{nil, "", true},