Make protocol version check more strict (#878)

Author: dveeden

client/auth.go

@@ -42,8 +42,14 @@ func (c *Conn) readInitialHandshake() error {
 		return errors.Annotate(c.handleErrorPacket(data), "read initial handshake error")
 	}
 
-	if data[0] < MinProtocolVersion {
-		return errors.Errorf("invalid protocol version %d, must >= 10", data[0])
+	if data[0] != ClassicProtocolVersion {
+		if data[0] == XProtocolVersion {
+			return errors.Errorf(
+				"invalid protocol version %d, expected 10. "+
+					"This might be X Protocol, make sure to connect to the right port",
+				data[0])
+		}
+		return errors.Errorf("invalid protocol version %d, expected 10", data[0])
 	}
 	pos := 1
 

mysql/const.go

@@ -1,9 +1,10 @@
 package mysql
 
 const (
-	MinProtocolVersion byte   = 10
-	MaxPayloadLen      int    = 1<<24 - 1
-	TimeFormat         string = "2006-01-02 15:04:05"
+	ClassicProtocolVersion byte   = 10
+	XProtocolVersion       byte   = 11
+	MaxPayloadLen          int    = 1<<24 - 1
+	TimeFormat             string = "2006-01-02 15:04:05"
 )
 
 const (