Delphi DLL

Socket Convert Existing TCP Connection to SSL/TLS

Demonstrates the Chilkat Socket ConvertToSsl method. Delphi DLL

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Socket;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
sock: HCkSocket;
useTls: Boolean;
port: Integer;
maxWaitMs: Integer;

begin
success := False;

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

sock := CkSocket_Create();

// --------------------------------------------------------------------
// This example uses the public TCP/TLS echo service at https://tcpbin.com/
// --------------------------------------------------------------------

// The echo server at tcpbin.com expects to receive TCP connections on port 4242, and TLS connections on port 4243.
// We could simply connect to port 4243 using TLS like this.
// However, further below, this example shows how to initially make a TCP connection, and then convert the connection to TLS.
useTls := True;
port := 4243;
maxWaitMs := 5000;
success := CkSocket_Connect(sock,'tcpbin.com',port,useTls,maxWaitMs);
if (success = False) then
  begin
    Memo1.Lines.Add(CkSocket__lastErrorText(sock));
    Exit;
  end;

// OK, we have a TLS connection.
// Note: The server chooses the TLS protocol version. 
// We can see the version of the TLS connection that was established:
Memo1.Lines.Add('TLS version: ' + CkSocket__tlsVersion(sock));

CkSocket_Close(sock,maxWaitMs);

// ---------------------------------------------------------------------
// Now we'll do the same, except first we connect to port 4243 using TCP,
// and then convert the connection to TLS.
// 
// This may seem pointless, and it is for the case w/ this server.  However, there could be situations
// where you're interacting with a server of some kind where there is a need to convert to/from TLS.
// (This is common internal to many protocols, such as SMTP, IMAP, FTP, etc., and it is often called "explicit" SSL/TLS)

// Connect again, except this time useTls is False, so we only have a simple TCP connection after this call.
useTls := False;
success := CkSocket_Connect(sock,'tcpbin.com',port,useTls,maxWaitMs);
if (success = False) then
  begin
    Memo1.Lines.Add(CkSocket__lastErrorText(sock));
    Exit;
  end;

// Convert the existing TCP connection to TLS.
// (The method name uses "SSL" because long ago, at the time of initial development, TLS 1.0 did not yet exist.)
success := CkSocket_ConvertToSsl(sock);
if (success = False) then
  begin
    Memo1.Lines.Add(CkSocket__lastErrorText(sock));
    Exit;
  end;

// OK, we now have a TLS connection.
// Again, we can see the TLS version:
Memo1.Lines.Add('TLS version: ' + CkSocket__tlsVersion(sock));

CkSocket_Close(sock,maxWaitMs);

CkSocket_Dispose(sock);

end;