fix server exception when using "tiancity" client

packet diffrent

{
Op: 0FD12002, Id: 0000000000000000
001 [..............17] Byte   : 23
002 [................] String : admin
003 [0000000000000000] Long   : 0
004 [................] String : /tNR4w2HIClIQXzjyiTuGJDAJDKu3/WXydlucUc0z1NZNOt311kvS/diPjGq/lBP5bWsePTTyUabtCNYeHHx/g==
005 [................] Bin    : mac
006 [........00000000] Int    : 0
007 [........00000000] Int    : 0
008 [................] String : local ip
}
    _bodyLen: 154
    _bodyStart: 22
    _buffer: {byte[176]}
    _elements: 8
    _ptr: 33
    Id: 0
    Op: 265363458