Handling of 0-length messages

[danon]

SmppSms $sms;
$sms->parseSms(); // goes nuts when MessageLength byte is equals to 0

It's also against specification, which states:

The maximum message length which can be specified in sm_length field (see section 5.2.21) is 254 octets. If an ESME wishes to submit a message of length greater than 254 octets, the sm_length field must be set to NULL and the message_payload optional parameter must be populated with the message length value and user data.