(Delphi ActiveX) 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.

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

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

...

procedure TForm1.Button1Click(Sender: TObject);
var
tunnel: TChilkatSocket;
sshHostname: WideString;
sshPort: Integer;
success: Integer;
channel: IChilkatSocket;
bTls: Integer;
port: Integer;
maxWaitMs: Integer;
rest: TChilkatRest;
ws: TChilkatWebSocket;
responseBody: WideString;
statusCode: Integer;

begin
// 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 := TChilkatSocket.Create(Self);

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

// Connect to an SSH server and establish the SSH tunnel:
success := tunnel.SshOpenTunnel(sshHostname,sshPort);
if (success <> 1) then
  begin
    Memo1.Lines.Add(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 <> 1) then
  begin
    Memo1.Lines.Add(tunnel.LastErrorText);
    Exit;
  end;

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

bTls := 1;
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 SshOpenChannel.
channel := tunnel.SshOpenChannel('some-websocket-server.com',port,bTls,maxWaitMs);
if (tunnel.LastMethodSuccess <> 1) then
  begin
    Memo1.Lines.Add(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 := TChilkatRest.Create(Self);
success := rest.UseConnection(channel,0);
if (success <> 1) then
  begin
    Memo1.Lines.Add(rest.LastErrorText);

    Exit;
  end;

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

// Tell the WebSocket to use this connection.
success := ws.UseConnection(rest.ControlInterface);
if (success <> 1) then
  begin
    Memo1.Lines.Add(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 <> 1) then
  begin
    Memo1.Lines.Add(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;
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 := ws.ValidateServerHandshake();
if (success <> 1) then
  begin
    Memo1.Lines.Add(ws.LastErrorText);
    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...)
end;