First Try to SMPP Protocol (Bind Command) - delphi

Question

i have a try to implement SMPP client , a first test is do bind after i have live socket connection.
but server show HEX Error message when receive the stream.
SMPP Unit
interface
uses Classes;
Type
// c octet strings
TSystemID = string[16];
TPassword = string[9];
TSystemType = string[13];
TAddr = string[21];
TAddr_Range = string[41];
TSvc_Type = string[6];
TDate_time = string[17];
TMsgID = string[65];
pPDU_HDR = ^TPDU_HDR;
TPDU_HDR = packed record
command_len : LongWord ;
command_id : LongWord ;
command_status :LongWord ;
command_number:LongWord ;
end;
pSMPP_BIND = ^TSMPP_BIND ;
TSMPP_BIND = packed record
SystemID : TSystemID ;
Password : TPassword ;
SystemType : TSystemType ;
Ver : Byte;
Addr_TON : Byte ;
Addr_NPI : Byte ;
Addr_Range : TAddr_Range ;
end;
const
{ max short message length }
DCS7_MAX_LEN = 160;
DCS8_MAX_LEN = 140;
DCSUCS2_MAX_LEN = DCS8_MAX_LEN div 2;
{ command ids }
cmdNull = $00000000;
cmdBindReceiver = $00000001;
cmdBindTransmitter = $00000002;
cmdQuery = $00000003;
cmdReplace = $00000007;
cmdCancel = $00000008;
cmdBindTransceiver = $00000009;
cmdOutbind = $0000000B;
cmdUnbind = $00000006;
cmdSubmitSM = $00000004;
cmdDeliverSM = $00000005;
cmdEnquireLink = $00000015;
cmdSubmitMultiply = $00000021;
cmdAlertNotification = $00000102;
cmdData = $00000103;
cmdGenericNack = $80000000;
cmdResponseBase = $80000000;
cmdBindReceiverResponse = $80000001;
cmdBindTransmitterResponse = $80000002;
cmdQueryResponse = $80000003;
cmdReplaceResponse = $80000007;
cmdCancelResponse = $80000008;
cmdBindTransceiverResponse = $80000009;
cmdUnbindResponse = $80000006;
cmdSubmitSMResponse = $80000004;
cmdDeliverSMResponse = $80000005;
cmdEnquireLinkResponse = $80000015;
cmdSubmitMultiplyResponse = $80000021;
cmdDataResponse = $80000103;
{ ESM_CLASS }
ESM_CLASS_DELIVERY_RECEIPT = $04;
ESM_CLASS_UDHI = $40;
implementation
end.
ON My Form btnSendBindClick
procedure TFrmMain.btnSendBindClick(Sender: TObject);
var hdr : TPDU_HDR ;
bind_pkt : TSMPP_BIND ;
mm : TMemoryStream ;
HdrPtr : pPDU_HDR ;
BindPtr : pSMPP_BIND ;
sysid : AnsiString ;
pass : AnsiString ;
systype : AnsiString ;
add_rn : AnsiString ;
begin
sysid := 'sysid';
pass := 'pass';
systype := 'sys_type';
add_rn := '';
hdr.command_id := htonl(cmdBindTransceiver) ;
hdr.command_status := htonl(cmdNull) ;
hdr.command_number := htonl(cmdBindTransmitter) ;
hdr.command_len := htonl(SizeOf(hdr)+SizeOf(bind_pkt));
bind_pkt.SystemID := pansiChar(sysid);
bind_pkt.Password := pansiChar(pass);
bind_pkt.SystemType := pansiChar(systype);
bind_pkt.Ver := 0 ;
bind_pkt.Addr_TON := 1 ;
bind_pkt.Addr_NPI := 1 ;
bind_pkt.Addr_Range := pansiChar(add_rn);
HdrPtr := #HdrPtr ;
BindPtr := #bind_pkt ;
mm := TMemoryStream.Create ;
mm.Write(HdrPtr^,SizeOf(hdr));
mm.Position := mm.Size;
mm.Write(BindPtr^,SizeOf(bind_pkt));
mm.Position := 0 ;
clnt.Socket.SendStream(mm);
end;
I think i need to encode data stream to something, but i am not sure .

Answer 1

I worked with SMPP in 1999/2000 last time, but at that time, specs. 3.4 said that fields like SystemID, Password etc..., i.e. declared as Var. Max nn, are of type C-OctetString.
So if the spec did not change, you completelly missed it: you cannot use records and similiar data structures, but you have to create an octet stream containing sequence of ASCIIZ strings with no padding, e.g. (using Delphi syntax): ...'SystemId'#0'Password'#0'SystemType'#0.... And if I remember it correctly, you should change endians for integer fields as well.