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help with BlockRead BlockWrite ScktComp

Posted on 2009-07-07
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Last Modified: 2013-11-23
I finally finish my demo of transfer files over a network but the code dont work, someone can tell me what im doing wrong?
Client
 
unit UntMain;
 
interface
 
uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, ScktComp, StdCtrls, Menus;
 
type
  TForm1 = class(TForm)
    Open: TOpenDialog;
    Client: TClientSocket;
    PopupMenu1: TPopupMenu;
    SendData1: TMenuItem;
    procedure FormCreate(Sender: TObject);
    procedure SendData1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
 
var
  Form1: TForm1;
 
implementation
 
{$R *.dfm}
 
procedure TForm1.FormCreate(Sender: TObject);
begin
 Client.Open;
end;
 
procedure SendFile(FilePath: String; Socket: TCustomWinSocket);
var
 F: File;
 NumRead: Integer;
 Buffer: array [1..4096] of Char;
begin
 AssignFile(F, FilePath);
 Reset(F, 1) ;
 repeat
   BlockRead(F, Buffer, SizeOf(Buffer), NumRead);
   Socket.SendBuf(Buffer, NumRead);
  until (NumRead = 0);
  CloseFile(F) ;
end;
 
 
procedure TForm1.SendData1Click(Sender: TObject);
begin
 Client.Socket.SendText('FILE');
 SendFile('C:\PortScan.exe', Client.Socket);
end;
 
end.
 
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Server
 
unit UntMain;
 
interface
 
uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, ScktComp;
 
type
  TForm1 = class(TForm)
    Server: TServerSocket;
    procedure FormCreate(Sender: TObject);
    procedure ServerClientRead(Sender: TObject; Socket: TCustomWinSocket);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
 
var
  Form1: TForm1;
 
implementation
 
{$R *.dfm}
 
procedure TForm1.FormCreate(Sender: TObject);
begin
  Server.Open;
end;
 
procedure GetFile(FilePath: string; Socket: TCustomWinSocket);
var
  F: file;
  NumRead, NumWritten: Integer;
  Buffer: array[1..4096] of Char;
begin
  AssignFile(F, FilePath);
  ReWrite(F, 1);
  repeat
    Socket.RecvBuf(Buffer, NumRead);
    BlockWrite(F, Buffer, NumRead, NumWritten);
  until (NumWritten <> NumRead);
  CloseFile(F);
end;
 
procedure TForm1.ServerClientRead(Sender: TObject;
  Socket: TCustomWinSocket);
var
  Data: string;
begin
  Data := Socket.RecvText;
  if Data = 'FILE' then
  begin
    GetFile('File.exe', Socket);
  end;
end;
 
end.

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Comment
Question by:CtrlShft
3 Comments
 
LVL 22

Expert Comment

by:8080_Diver
ID: 24800382
In what way does the code not work?  Are there error messages?  Have you stepped through it in debug mode?
0
 
LVL 4

Accepted Solution

by:
JonasMalmsten earned 125 total points
ID: 24801640
In procedure TForm1.ServerClientRead(Sender: TObject; Socket: TCustomWinSocket);

Data will contain more than simply 'FILE', it will also contain the beginning of the file you are transfering, something like 'FILEMZ' + garbage, so Data = 'FILE' may never become true.

Also, ServerClientRead will be executed multiple times, each time new data is available unless the whole file can be transmitted in one block of data which is not usually the case.

GetFile is attempting to read the whole file, but the socket will not provide more data unless you call Application.ProcessMessages somewhere. You can probably get away with doing this in the loop there, but doing so will cause ServerClientRead to execute again, so you will then need to prevent this function to be re-entrant.

A better solution can be found here:
http://www.experts-exchange.com/Programming/Languages/Pascal/Delphi/Q_24530418.html
0
 

Author Comment

by:CtrlShft
ID: 24805470
OK JonasMalmsten, i modified a lite bit, here is the new code:

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
begin
 Client.Host:= 'localhost';
 Client.Port:= 1;
 Client.Open;
end;

procedure SendFile(FilePath: String);
var
 F: File;
 NumRead: Integer;
 Buffer: array [1..4096] of Char;
begin
 AssignFile(F, FilePath);
 Reset(F, 1) ;
 repeat
   Application.ProcessMessages;
   BlockRead(F, Buffer, SizeOf(Buffer), NumRead);
   Form1.Client.Socket.SendBuf(Buffer, NumRead);
  until (NumRead = 0);
  CloseFile(F) ;
end;


procedure TForm1.SendData1Click(Sender: TObject);
begin
 SendFile('C:\PortScan.exe');
end;

Server

{$R *.dfm}

procedure GetFile(FilePath: string);
var
  F: file;
  NumRead, NumWritten: Integer;
  Buffer: array[1..4096] of Char;
begin
  AssignFile(F, FilePath);
  ReWrite(F, 1);
  repeat
    Application.ProcessMessages;
    Form1.Server.Socket.RecvBuf(Buffer, NumRead);
    BlockWrite(F, Buffer, NumRead, NumWritten);
  until (NumWritten <> NumRead);
  CloseFile(F);
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  Server.Port:= 1;
  Server.Open;
end;

procedure TForm1.ServerClientRead(Sender: TObject;
  Socket: TCustomWinSocket);
begin
 GetFile('File.exe');
end;

pls tell me what you think, when i send the data from the client to the server i get error "Asynchronous Socket Error 10053 "
so where i can place the GetFile procedure, because i try it on a timmer:
if Server.Socket.Connected the GetFile('File.exe');
and dont work.
0

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