// Encode converts the query string into bytes according to the
// specified encoding.
func (u *Ussd) Encode(enc Encoding) ([]byte, error) {
switch enc {
case Encodings.Gsm7Bit:
return pdu.Encode7Bit(u.String()), nil
case Encodings.UCS2:
return pdu.EncodeUcs2(u.String()), nil
default:
return nil, ErrUnknownEncoding
}
}
// PDU serializes the message into octets ready to be transferred.
// Returns the number of TPDU bytes in the produced PDU.
// Complies with 3GPP TS 23.040.
func (s *Message) PDU() (int, []byte, error) {
var buf bytes.Buffer
if len(s.ServiceCenterAddress) < 1 {
buf.WriteByte(0x00) // SMSC info length
} else {
_, octets, err := s.ServiceCenterAddress.PDU()
if err != nil {
return 0, nil, err
}
buf.WriteByte(byte(len(octets)))
buf.Write(octets)
}
switch s.Type {
case MessageTypes.Deliver:
var sms smsDeliver
sms.MessageTypeIndicator = byte(s.Type)
sms.MoreMessagesToSend = s.MoreMessagesToSend
sms.LoopPrevention = s.LoopPrevention
sms.ReplyPath = s.ReplyPathExists
sms.UserDataHeaderIndicator = s.UserDataStartsWithHeader
sms.StatusReportIndication = s.StatusReportIndication
addrLen, addr, err := s.Address.PDU()
if err != nil {
return 0, nil, err
}
var addrBuf bytes.Buffer
addrBuf.WriteByte(byte(addrLen))
addrBuf.Write(addr)
sms.OriginatingAddress = addrBuf.Bytes()
sms.ProtocolIdentifier = 0x00 // Short Message Type 0
sms.DataCodingScheme = byte(s.Encoding)
sms.ServiceCentreTimestamp = s.ServiceCenterTime.PDU()
var userData []byte
if s.Encoding == Encodings.Gsm7Bit {
userData = pdu.Encode7Bit(s.Text)
sms.UserDataLength = byte(len(s.Text))
} else if s.Encoding == Encodings.UCS2 {
userData = pdu.EncodeUcs2(s.Text)
sms.UserDataLength = byte(len(userData))
} else {
return 0, nil, ErrUnknownEncoding
}
sms.UserDataLength = byte(len(userData))
sms.UserData = userData
n, err := buf.Write(sms.Bytes())
if err != nil {
return 0, nil, err
}
return n, buf.Bytes(), nil
case MessageTypes.Submit:
var sms smsSubmit
sms.MessageTypeIndicator = byte(s.Type)
sms.RejectDuplicates = s.RejectDuplicates
sms.ValidityPeriodFormat = byte(s.VPFormat)
sms.ReplyPath = s.ReplyPathExists
sms.UserDataHeaderIndicator = s.UserDataStartsWithHeader
sms.StatusReportRequest = s.StatusReportRequest
sms.MessageReference = s.MessageReference
addrLen, addr, err := s.Address.PDU()
if err != nil {
return 0, nil, err
}
var addrBuf bytes.Buffer
addrBuf.WriteByte(byte(addrLen))
addrBuf.Write(addr)
sms.DestinationAddress = addrBuf.Bytes()
sms.ProtocolIdentifier = 0x00 // Short Message Type 0
sms.DataCodingScheme = byte(s.Encoding)
switch s.VPFormat {
case ValidityPeriodFormats.Relative:
sms.ValidityPeriod = byte(s.VP.Octet())
case ValidityPeriodFormats.Absolute, ValidityPeriodFormats.Enhanced:
return 0, nil, ErrNonRelative
}
var userData []byte
if s.Encoding == Encodings.Gsm7Bit {
userData = pdu.Encode7Bit(s.Text)
sms.UserDataLength = byte(len(s.Text))
} else if s.Encoding == Encodings.UCS2 {
userData = pdu.EncodeUcs2(s.Text)
sms.UserDataLength = byte(len(userData))
} else {
return 0, nil, ErrUnknownEncoding
}
sms.UserData = userData
n, err := buf.Write(sms.Bytes())
if err != nil {
return 0, nil, err
}
return n, buf.Bytes(), nil
default:
return 0, nil, ErrUnknownMessageType
}
}