udp-server.pas

procedure TForm1.UDPUDPRead(Sender: TObject; AData: TStream;
  ABinding: TIdSocketHandle);
  var
    iType: Integer;
    pBuf: Pointer;
    str: String;
    buf: array[0..8191] of char;
begin
  pBuf := AllocMem(AData.Size);
  try
    AData.ReadBuffer(pBuf^, AData.Size);
    iType := 0;
    CopyMemory(@iType, pBuf, 4);
    if iType <> 1001 then Exit;
    SetLength(str, AData.Size-4);
    CopyMemory(@str[1], Pointer(DWORD(pBuf)+4), AData.Size-4);
    Memo1.Lines.Add(ABinding.PeerIP+' '+ IntToStr(ABinding.PeerPort)+':'+str);
    UDP.Send(ABinding.PeerIP, ABinding.PeerPort, '接收消息成功!');
  finally
    FreeMem(pBuf);
  end;
end;