Upgrade a Plain TCP Connection to TLS

See more Socket/SSL/TLS Examples

Demonstrates Socket.ConvertToSsl, which upgrades an already-connected plain TCP socket to TLS by performing a client-side TLS handshake over the existing connection.

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.Socket;

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

procedure RunDemo;
var
  success: Boolean;
  socket: TSocket;
  bTls: Boolean;
  maxWaitMs: Integer;

begin
  success := False;

  socket := TSocket.Create;

  //  Connect as plain TCP (no TLS yet).
  bTls := False;
  maxWaitMs := 5000;
  success := socket.Connect('example.com',5000,bTls,maxWaitMs);
  if (success = False) then
    begin
      WriteLn(socket.LastErrorText);
      Exit;
    end;

  //  At the point where the application protocol permits a STARTTLS-style upgrade, perform any required
  //  negotiation, then upgrade the existing connection to TLS with a client-side handshake.
  success := socket.ConvertToSsl();
  if (success = False) then
    begin
      WriteLn(socket.LastErrorText);
      Exit;
    end;
  WriteLn('Connection upgraded to TLS.');


  socket.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.