Pascal (Lazarus/Delphi)

Transfer a File using Sockets (TLS or non-TLS)

See more Socket/SSL/TLS Examples

Demonstrates how to two programs, one a socket writer and the other a socket reader, can transfer a file. The connection can be TLS or a regular non-encrypted TCP connection. Pascal (Lazarus/Delphi)

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.BinData,
  Chilkat.Socket;

// ---------------------------------------------------------------------------

procedure RunDemo;
var
  success: Boolean;
  bdToSend: TBinData;
  sndSock: TSocket;
  bUseTls: Boolean;
  port: Integer;
  maxWaitMs: Integer;
  numBytes: Integer;
  bBigEndian: Boolean;
  listenSock: TSocket;
  rcvSock: TSocket;
  numBytesComing: Integer;
  bdReceived: TBinData;
  maxWaitMs: Integer;

begin
  success := False;

  //  This example requires the Chilkat API to have been previously unlocked.
  //  See Global Unlock Sample for sample code.

  //  On the sending side, we'll load the file into a BinData object and send.
  //  On the receiving side, we'll read from the socket connection into a BinData, and save to a file.
  //  This example assumes the file is not crazy-large, and that the entire contents
  //  can fit into memory.  
  //  (If the file is too large for memory, there are other ways to send. It just involves streaming or 
  //  sending the file chunk-by-chunk..)

  //  This section of code is for the sender.
  bdToSend := TBinData.Create;
  success := bdToSend.LoadFile('somePath/someFile.dat');
  //  Assume success for the example...

  sndSock := TSocket.Create;
  bUseTls := True;
  port := 5555;
  maxWaitMs := 5000;
  success := sndSock.Connect('some_domain_or_ip.com',port,bUseTls,maxWaitMs);
  //  Assume success for the example...

  //  Tell the receiver how many bytes are coming.
  numBytes := bdToSend.NumBytes;
  bBigEndian := True;
  success := sndSock.SendInt32(numBytes,bBigEndian);

  //  Send the file data (sends the entire contents of bdToSend).
  success := sndSock.SendBd(bdToSend,0,0);

  //  Get an acknowledgement.
  success := sndSock.ReceiveInt32(bBigEndian);
  if (success = False) then
    begin
      WriteLn(sndSock.LastErrorText);
      Exit;
    end;

  //  Did the receiver get the correct number of bytes?
  if (sndSock.ReceivedInt <> numBytes) then
    begin
      WriteLn('The receiver did not acknowledge with the correct number of bytes.');
      Exit;
    end;

  WriteLn('File sent!');

  //  ------------------------------------------------------------------------------------
  //  The code below is for the receiving side (running on some other computer..)

  listenSock := TSocket.Create;

  success := listenSock.BindAndListen(5555,25);
  if (success = False) then
    begin
      WriteLn(listenSock.LastErrorText);
      Exit;
    end;

  //  Get the next incoming connection
  //  Wait a maximum of 20 seconds (20000 millisec)
  rcvSock := TSocket.Create;
  success := listenSock.AcceptNext(20000,rcvSock);
  if (success = False) then
    begin
      WriteLn(listenSock.LastErrorText);
      Exit;
    end;

  //  The sender will first send the big-endian integer for the number of bytes
  //  that are forthcoming..
  success := rcvSock.ReceiveInt32(bBigEndian);
  if (success <> True) then
    begin
      WriteLn(rcvSock.LastErrorText);
      Exit;
    end;

  numBytesComing := rcvSock.ReceivedInt;

  //  Receive that many bytes..
  bdReceived := TBinData.Create;
  success := rcvSock.ReceiveBdN(numBytesComing,bdReceived);
  if (success <> True) then
    begin
      WriteLn(rcvSock.LastErrorText);
      Exit;
    end;

  //  Acknowledge the sender by sending back the number of bytes we received.
  success := rcvSock.SendInt32(bdReceived.NumBytes,bBigEndian);

  //  Close the connection.
  maxWaitMs := 20;
  rcvSock.Close(maxWaitMs);

  //  Save the received data to a file.
  success := bdReceived.WriteFile('somePath/someFile.dat');
  //  Assume success for the example...

  WriteLn('File received!');


  bdToSend.Free;
  sndSock.Free;
  listenSock.Free;
  rcvSock.Free;
  bdReceived.Free;

end;

// ---------------------------------------------------------------------------

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.