Mark connections as bad on MariaDB shutdown

AUTHORS

@@ -42,6 +42,7 @@ Runrioter Wung <runrioter at gmail.com>
 Soroush Pour <me at soroushjp.com>
 Stan Putrya <root.vagner at gmail.com>
 Stanley Gunawan <gunawan.stanley at gmail.com>
+Thomas Parrott <tomp at tomp.uk>
 Xiaobing Jiang <s7v7nislands at gmail.com>
 Xiuming Chen <cc at cxm.cc>
 

packets.go

@@ -49,8 +49,15 @@ func (mc *mysqlConn) readPacket() ([]byte, error) {
 			if data[3] > mc.sequence {
 				return nil, ErrPktSyncMul
 			}
-			return nil, ErrPktSync
+
+			//When MariaDB server is shutdown connection killed packet is sent
+			//with a zero sequence number.
+			//Continue to process it so the specific error can be detected.
+			if data[3] != 0 {
+				return nil, ErrPktSync
+			}
 		}
+
 		mc.sequence++
 
 		// Read packet body [pktLen bytes]
@@ -525,6 +532,13 @@ func (mc *mysqlConn) handleErrorPacket(data []byte) error {
 		pos = 9
 	}
 
+	//If error code is for Connection was killed, then return bad connection.
+	//https://mariadb.com/kb/en/mariadb/mariadb-error-codes/
+	if errno == 1927 {
+		errLog.Print("Error ", errno, ": ", string(data[pos:]))
+		return driver.ErrBadConn
+	}
+
 	// Error Message [string]
 	return &MySQLError{
 		Number:  errno,