(Delphi DLL) WebSocket through SSH Tunnel

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

Note: This example requires Chilkat v11.0.0 or greater.

Chilkat for Delphi Downloads Chilkat non-ActiveX DLL for Delphi Chilkat ActiveX DLL for Delphi * The examples here use the non-ActiveX DLL.

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

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
tunnel: HCkSocket;
sshHostname: PWideChar;
sshPort: Integer;
bTls: Boolean;
port: Integer;
maxWaitMs: Integer;
channel: HCkSocket;
rest: HCkRest;
ws: HCkWebSocket;
responseBody: PWideChar;
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 := CkSocket_Create();

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

// Connect to an SSH server and establish the SSH tunnel:
success := CkSocket_SshOpenTunnel(tunnel,sshHostname,sshPort);
if (success = False) then
  begin
    Memo1.Lines.Add(CkSocket__lastErrorText(tunnel));
    Exit;
  end;

// Authenticate with the SSH server via a login/password
// or with a public key.
// This example demonstrates SSH password authentication.
success := CkSocket_SshAuthenticatePw(tunnel,'mySshLogin','mySshPassword');
if (success = False) then
  begin
    Memo1.Lines.Add(CkSocket__lastErrorText(tunnel));
    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 := CkSocket_Create();
success := CkSocket_SshNewChannel(tunnel,'some-websocket-server.com',port,bTls,maxWaitMs,channel);
if (success = False) then
  begin
    Memo1.Lines.Add(CkSocket__lastErrorText(tunnel));
    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 := CkRest_Create();
success := CkRest_UseConnection(rest,channel,False);
if (success = False) then
  begin
    Memo1.Lines.Add(CkRest__lastErrorText(rest));
    Exit;
  end;

// Finally, tell our WebSocket object to use the Rest object..
ws := CkWebSocket_Create();

// Tell the WebSocket to use this connection.
success := CkWebSocket_UseConnection(ws,rest);
if (success = False) then
  begin
    Memo1.Lines.Add(CkWebSocket__lastErrorText(ws));
    Exit;
  end;

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

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

// Do the open handshake.
responseBody := CkRest__fullRequestNoBody(rest,'GET','/something');
if (CkRest_getLastMethodSuccess(rest) = False) then
  begin
    Memo1.Lines.Add(CkRest__lastErrorText(rest));
    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 := CkRest_getResponseStatusCode(rest);
Memo1.Lines.Add('Response status code: ' + IntToStr(statusCode));

if (statusCode <> 101) then
  begin
    Memo1.Lines.Add(responseBody);
    Memo1.Lines.Add('-- 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 := CkWebSocket_ValidateServerHandshake(ws);
if (success = False) then
  begin
    Memo1.Lines.Add(CkWebSocket__lastErrorText(ws));
    Exit;
  end;

Memo1.Lines.Add('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...)

CkSocket_Dispose(tunnel);
CkSocket_Dispose(channel);
CkRest_Dispose(rest);
CkWebSocket_Dispose(ws);

end;