Propagate connection protocol

mtproto/connection_options.go

@@ -10,11 +10,14 @@ import (
 // by the user.
 type ConnectionType uint8
 
+type ConnectionProtocol uint8
+
 // ConnectionOpts presents an options, metadata on connection requested
 // by the user on handshake.
 type ConnectionOpts struct {
-	DC             int16
-	ConnectionType ConnectionType
+	DC              int16
+	ConnectionType  ConnectionType
+	ConnectionProto ConnectionProtocol
 }
 
 // Different connection types which user requests from Telegram.
@@ -24,6 +27,12 @@ const (
 	ConnectionTypeIntermediate
 )
 
+const (
+	ConnectionProtocolIPv4 ConnectionProtocol = 1
+	ConnectionProtocolIPv6                    = ConnectionProtocolIPv4 << 1
+	ConnectionProtocolAny                     = ConnectionProtocolIPv4 | ConnectionProtocolIPv6
+)
+
 // Connection tags for mtproto handshakes.
 var (
 	ConnectionTagAbridged     = []byte{0xef, 0xef, 0xef, 0xef}