151 lines
3.9 KiB
Plaintext
151 lines
3.9 KiB
Plaintext
{
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$Project$
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$Workfile$
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$Revision$
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$DateUTC$
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$Id$
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This file is part of the Indy (Internet Direct) project, and is offered
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under the dual-licensing agreement described on the Indy website.
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(http://www.indyproject.org/)
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Copyright:
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(c) 1993-2005, Chad Z. Hower and the Indy Pit Crew. All rights reserved.
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}
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{
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$Log$
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}
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{
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Rev 1.5 10/26/2004 10:49:20 PM JPMugaas
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Updated ref.
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Rev 1.4 2004.02.03 5:44:30 PM czhower
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Name changes
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Rev 1.3 1/21/2004 4:04:08 PM JPMugaas
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InitComponent
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Rev 1.2 10/24/2003 02:54:58 PM JPMugaas
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These should now work with the new code.
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Rev 1.1 2003.10.24 10:38:30 AM czhower
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UDP Server todos
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Rev 1.0 11/13/2002 08:02:44 AM JPMugaas
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}
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unit IdSystatUDPServer;
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{
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Indy Systat Client TIdSystatUDPServer
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Copyright (C) 2002 Winshoes Working Group
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Original author J. Peter Mugaas
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2002-August-13
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Based on RFC 866
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Note that this protocol is officially called Active User.
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}
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interface
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{$i IdCompilerDefines.inc}
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uses
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Classes,
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IdAssignedNumbers, IdGlobal, IdSocketHandle, IdUDPBase, IdUDPServer;
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type
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TIdUDPSystatEvent = procedure (ABinding: TIdSocketHandle; AResults : TStrings) of object;
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type
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TIdSystatUDPServer = class(TIdUDPServer)
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protected
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FOnSystat : TIdUDPSystatEvent;
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procedure DoUDPRead(AThread: TIdUDPListenerThread; const AData: TIdBytes; ABinding: TIdSocketHandle); override;
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procedure InitComponent; override;
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published
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property OnSystat : TIdUDPSystatEvent read FOnSystat write FOnSystat;
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property DefaultPort default IdPORT_SYSTAT;
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end;
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implementation
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uses
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SysUtils;
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{
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According to the "Programming UNIX Sockets in C - Frequently Asked Questions"
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This has to do with the maximum size of a datagram on the two machines involved.
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This depends on the sytems involved, and the MTU (Maximum Transmission Unit).
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According to "UNIX Network Programming", all TCP/IP implementations must support
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a minimum IP datagram size of 576 bytes, regardless of the MTU. Assuming a 20
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byte IP header and 8 byte UDP header, this leaves 548 bytes as a safe maximum
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size for UDP messages. The maximum size is 65516 bytes. Some platforms support
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IP fragmentation which will allow datagrams to be broken up (because of MTU
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values) and then re-assembled on the other end, but not all implementations
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support this.
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URL:
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http://www.manualy.sk/sock-faq/unix-socket-faq-5.html
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}
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const Max_UDPPacket = 548;
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Max_Line_Len = Max_UDPPacket - 2; //EOL deliniator
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{ TIdSystatUDPServer }
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procedure TIdSystatUDPServer.InitComponent;
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begin
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inherited;
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DefaultPort := IdPORT_SYSTAT;
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end;
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procedure TIdSystatUDPServer.DoUDPRead(AThread: TIdUDPListenerThread;
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const AData: TIdBytes; ABinding: TIdSocketHandle);
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var
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s, s2 : String;
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LResults : TStrings;
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i : Integer;
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function MaxLenStr(const AStr : String): String;
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begin
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Result := AStr;
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if Length(Result)>Max_Line_Len then
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begin
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SetLength(Result, Max_Line_Len);
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end;
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end;
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begin
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inherited DoUDPRead(AThread, AData, ABinding);
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if Assigned(FOnSystat) then
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begin
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LResults := TStringList.Create;
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try
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FOnSystat(ABinding, LResults);
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s := '';
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for i := 0 to LResults.Count - 1 do
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begin
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{enure that one line will never exceed the maximum packet size }
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s2 := s + EOL + MaxLenStr(LResults[i]);
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if Length(s2) > Max_UDPPacket then
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begin
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s := TrimLeft(s);
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ABinding.SendTo(ABinding.PeerIP, ABinding.PeerPort, ToBytes(s), ABinding.IPVersion);
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s := MaxLenStr(LResults[i]);
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end else
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begin
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s := s2;
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end;
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end;
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if s <> '' then
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begin
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s := TrimLeft(s);
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ABinding.SendTo(ABinding.PeerIP, ABinding.PeerPort, ToBytes(s), ABinding.IPVersion);
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end;
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finally
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FreeAndNil(LResults);
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end;
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end;
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end;
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end.
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