Add mDNS Host Candidate support

Relates to pion/webrtc#699

mdns.go

@@ -0,0 +1,32 @@
+package ice
+
+import (
+	"crypto/rand"
+	"fmt"
+)
+
+// MulticastDNSMode represents the different Multicast modes ICE can run in
+type MulticastDNSMode byte
+
+// MulticastDNSMode enum
+const (
+	// MulticastDNSModeDisabled means remote mDNS candidates will be discarded, and local host candidates will use IPs
+	MulticastDNSModeDisabled MulticastDNSMode = iota + 1
+
+	// MulticastDNSModeQueryOnly means remote mDNS candidates will be accepted, and local host candidates will use IPs
+	MulticastDNSModeQueryOnly
+
+	// MulticastDNSModeQueryAndGather means remote mDNS candidates will be accepted, and local host candidates will use mDNS
+	MulticastDNSModeQueryAndGather
+)
+
+func generateMulticastDNSName() (string, error) {
+	b := make([]byte, 16)
+	_, err := rand.Read(b) //nolint
+
+	if err != nil {
+		return "", err
+	}
+
+	return fmt.Sprintf("%X-%X-%X-%X-%X.local", b[0:4], b[4:6], b[6:8], b[8:10], b[10:]), nil
+}