Pascal (Lazarus/Delphi)

WebSocket through SSH Tunnel

See more WebSocket Examples

This example shows how to establish a WebSocket connection through an SSH tunnel. The WebSocket protocol communications will be encapsulated within an SSH tunnel. 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.Rest,
  Chilkat.WebSocket,
  Chilkat.Socket;

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

procedure RunDemo;
var
  success: Boolean;
  tunnel: TSocket;
  sshHostname: string;
  sshPort: Integer;
  bTls: Boolean;
  port: Integer;
  maxWaitMs: Integer;
  channel: TSocket;
  rest: TRest;
  ws: TWebSocket;
  responseBody: string;
  statusCode: Integer;

begin
  success := False;

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

  //  --------------------------------------------------
  //  This example borrows the code from the REST through SSH Tunnel example.
  //  We first use the Chilkat Socket object to establish a connection to the WebSocket server through an SSH Tunnel.
  //  Next, the Rest object uses the Socket object for its connection.
  //  Finally, the WebSocket object uses the Rest object for its connection.  
  //  
  //  Hopefully the flexibility of this architecture is easy to see.  All of the HTTP functionality of the Rest object,
  //  such as HTTP authentication, custom headers, etc. is available to the WebSocket.  Likewise, all of the advanced functionality
  //  of the Socket object is in turn available to the Rest object.  

  //  The high-level steps for accomplishing the task of running the WebSocket protocol through an SSH accomplished as follows:
  //  1) Create the SSH tunnel using Chilkat Socket.
  //  2) Open a port-forwarding channel (to the WebSocket server) within the tunnel.
  //  2) Tell Rest to use the Socket object.
  //  3) Tell WebSocket to use the Rest object.

  tunnel := TSocket.Create;

  sshHostname := 'sftp.example.com';
  sshPort := 22;

  //  Connect to an SSH server and establish the SSH tunnel:
  success := tunnel.SshOpenTunnel(sshHostname,sshPort);
  if (success = False) then
    begin
      WriteLn(tunnel.LastErrorText);
      Exit;
    end;

  //  Authenticate with the SSH server via a login/password
  //  or with a public key.
  //  This example demonstrates SSH password authentication.
  success := tunnel.SshAuthenticatePw('mySshLogin','mySshPassword');
  if (success = False) then
    begin
      WriteLn(tunnel.LastErrorText);
      Exit;
    end;

  //   OK, the SSH tunnel is setup.  Now open a channel within the tunnel.

  bTls := True;
  port := 443;
  maxWaitMs := 5000;

  //  This returns a socket object that is a single channel within the SSH tunnel.
  //  The SSH channel is our logical port-forwarded connection through the SSH tunnel.
  //  Note: This example establishes a TLS connection to the target WebSocket server.
  //  (The TLS protocol will run on the logical channel within the SSH tunnel.)
  //  Your application can just as easily make a non-TLS connection by changing the arguments
  //  passed to SshNewChannel.
  channel := TSocket.Create;
  success := tunnel.SshNewChannel('some-websocket-server.com',port,bTls,maxWaitMs,channel);
  if (success = False) then
    begin
      WriteLn(tunnel.LastErrorText);
      Exit;
    end;

  //  Create a REST object and tell it to use the SSH channel.
  //  This connection is a TLS running on an SSH channel through an SSH tunnel.
  //  In other words, TLS is wrapped within the SSH tunnel.
  rest := TRest.Create;
  success := rest.UseConnection(channel,False);
  if (success = False) then
    begin
      WriteLn(rest.LastErrorText);
      Exit;
    end;

  //  Finally, tell our WebSocket object to use the Rest object..
  ws := TWebSocket.Create;

  //  Tell the WebSocket to use this connection.
  success := ws.UseConnection(rest);
  if (success = False) then
    begin
      WriteLn(ws.LastErrorText);
      Exit;
    end;

  //  Add the standard WebSocket open handshake headers that will be needed.
  //  (This adds the required HTTP request headers to the rest object.)
  ws.AddClientHeaders();

  //  Add any additional headers that might be desired.
  //  Two common WebSocketSpecific headers are "Sec-WebSocket-Protocol" and "Origin".
  rest.AddHeader('Sec-WebSocket-Protocol','x-some-websocket-subprotocol');
  rest.AddHeader('Origin','http://some-websocket-server.com');

  //  Do the open handshake.
  responseBody := rest.FullRequestNoBody('GET','/something');
  if (rest.LastMethodSuccess = False) then
    begin
      WriteLn(rest.LastErrorText);
      Exit;
    end;

  //  If successful, the HTTP response status code should be 101,
  //  and the response body will be empty. (If it failed, we'll have a look
  //  at the response body..)
  statusCode := rest.ResponseStatusCode;
  WriteLn('Response status code: ' + statusCode);

  if (statusCode <> 101) then
    begin
      WriteLn(responseBody);
      WriteLn('-- Failed because of unexpected response status code.');
      Exit;
    end;

  //  We have the expected 101 response, so let's now validate the 
  //  contents of the response, such as the value sent by the server in the
  //  Sec-WebSocket-Accept header. 
  success := ws.ValidateServerHandshake();
  if (success = False) then
    begin
      WriteLn(ws.LastErrorText);
      Exit;
    end;

  WriteLn('WebSocket connection successful.');

  //  The application may now begin sending and receiving frames on the WebSocket connection.
  //  (At this point, we're done with the rest object...)


  tunnel.Free;
  channel.Free;
  rest.Free;
  ws.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.