Pascal (Lazarus/Delphi)

Accept TLS Connection with Client Authentication

See more Socket/SSL/TLS Examples

Demonstrates how to accept a TLS connection requiring client authentication. This is the case where the TLS client sends a certificate. It is also known as "Two-Way SSL". 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.Cert,
  Chilkat.Socket;

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

procedure RunDemo;
var
  success: Boolean;
  listenSslSocket: TSocket;
  cert: TCert;
  myPort: Integer;
  backLog: Integer;
  maxWaitMillisec: Integer;
  clientSock: TSocket;
  receivedMsg: string;

begin
  success := False;

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

  listenSslSocket := TSocket.Create;

  //  An SSL/TLS server needs a digital certificate.  This example loads it from a PFX file.
  //  Note: This is the server's certificate.

  cert := TCert.Create;
  //  The 1st argument is the file path, the 2nd arg is the 
  //  PFX file's password:
  success := cert.LoadPfxFile('chilkat.pfx','test');
  if (success = False) then
    begin
      WriteLn(cert.LastErrorText);
      Exit;
    end;

  //  To accept client client certificates in the TLS handshake,
  //  we must indicate a list of acceptable client certificate root CA DN's
  //  that are allowed.  (DN is an acronym for Distinguished Name.)
  //  Call AddSslAcceptableClientCaDn once for each acceptable CA DN.
  //  Here are a few examples so you can see the general format of a DN.
  listenSslSocket.AddSslAcceptableClientCaDn('C=SE, O=AddTrust AB, OU=AddTrust External TTP Network, CN=AddTrust External CA Root');
  listenSslSocket.AddSslAcceptableClientCaDn('O=Digital Signature Trust Co., CN=DST Root CA X3');

  //  Use the certificate:
  success := listenSslSocket.InitSslServer(cert);
  if (success = False) then
    begin
      WriteLn(listenSslSocket.LastErrorText);
      Exit;
    end;

  //  Bind and listen on a port:
  myPort := 8123;
  //  Allow for a max of 5 queued connect requests.
  backLog := 5;
  success := listenSslSocket.BindAndListen(myPort,backLog);
  if (success = False) then
    begin
      WriteLn(listenSslSocket.LastErrorText);
      Exit;
    end;

  //  If accepting an SSL/TLS connection, the SSL handshake is part of the connection
  //  establishment process. This involves a few back-and-forth messages between the 
  //  client and server to establish algorithms and a shared key to create the secure 
  //  channel. The sending and receiving of these messages are governed by the 
  //  MaxReadIdleMs and MaxSendIdleMs properties. If these properties are set to 0 
  //  (and this is the default unless changed by your application), then the 
  //  AcceptNext can hang indefinitely during the SSL handshake process. 
  //  Make sure these properties are set to appropriate values before calling AcceptNext.

  //  Set a 10 second max for waiting to read/write.  This is for the SSL/TLS handshake establishment.
  listenSslSocket.MaxReadIdleMs := 10000;
  listenSslSocket.MaxSendIdleMs := 10000;

  //  Accept a single client connection and establish the secure SSL/TLS channel:
  maxWaitMillisec := 20000;
  clientSock := TSocket.Create;
  success := listenSslSocket.AcceptNext(maxWaitMillisec,clientSock);
  if (success = False) then
    begin
      WriteLn(listenSslSocket.LastErrorText);
      Exit;
    end;

  //  The client (in this example) is going to send a "Hello Server! -EOM-" 
  //  message.  Read it:
  receivedMsg := clientSock.ReceiveUntilMatch('-EOM-');
  if (clientSock.LastMethodSuccess = False) then
    begin
      WriteLn(clientSock.LastErrorText);
      Exit;
    end;

  WriteLn(receivedMsg);

  //  Send a "Hello Client! -EOM-" message:
  success := clientSock.SendString('Hello Client! -EOM-');
  if (success = False) then
    begin
      WriteLn(clientSock.LastErrorText);
      Exit;
    end;

  //  Close the connection with the client
  //  Wait a max of 20 seconds (20000 millsec)
  success := clientSock.Close(20000);


  listenSslSocket.Free;
  cert.Free;
  clientSock.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.