Add webrtc (#179)

* Add x-webrtc

* update webrtc protocol

* address review comments

* fix fmt

* update code to 0x118

protocols.go

@@ -36,6 +36,7 @@ const (
 	P_WS                = 0x01DD
 	P_WSS               = 0x01DE // deprecated alias for /tls/ws
 	P_PLAINTEXTV2       = 0x706c61
+	P_WEBRTC            = 0x118
 )
 
 var (
@@ -247,6 +248,11 @@ var (
 		Code:  P_WSS,
 		VCode: CodeToVarint(P_WSS),
 	}
+	protoWebRTC = Protocol{
+		Name:  "webrtc",
+		Code:  P_WEBRTC,
+		VCode: CodeToVarint(P_WEBRTC),
+	}
 )
 
 func init() {
@@ -283,6 +289,7 @@ func init() {
 		protoWS,
 		protoWSS,
 		protoPlaintextV2,
+		protoWebRTC,
 	} {
 		if err := AddProtocol(p); err != nil {
 			panic(err)