Android™

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. Android™

// Important: Don't forget to include the call to System.loadLibrary
// as shown at the bottom of this code sample.
package com.test;

import android.app.Activity;
import com.chilkatsoft.*;

import android.widget.TextView;
import android.os.Bundle;

public class SimpleActivity extends Activity {

  private static final String TAG = "Chilkat";

  // Called when the activity is first created.
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    boolean 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.

    CkSocket tunnel = new CkSocket();

    String sshHostname = "sftp.example.com";
    int sshPort = 22;

    //  Connect to an SSH server and establish the SSH tunnel:
    success = tunnel.SshOpenTunnel(sshHostname,sshPort);
    if (success == false) {
        Log.i(TAG, tunnel.lastErrorText());
        return;
        }

    //  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) {
        Log.i(TAG, tunnel.lastErrorText());
        return;
        }

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

    boolean bTls = true;
    int port = 443;
    int 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.
    CkSocket channel = new CkSocket();
    success = tunnel.SshNewChannel("some-websocket-server.com",port,bTls,maxWaitMs,channel);
    if (success == false) {
        Log.i(TAG, tunnel.lastErrorText());
        return;
        }

    //  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.
    CkRest rest = new CkRest();
    success = rest.UseConnection(channel,false);
    if (success == false) {
        Log.i(TAG, rest.lastErrorText());
        return;
        }

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

    //  Tell the WebSocket to use this connection.
    success = ws.UseConnection(rest);
    if (success == false) {
        Log.i(TAG, ws.lastErrorText());
        return;
        }

    //  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.
    String responseBody = rest.fullRequestNoBody("GET","/something");
    if (rest.get_LastMethodSuccess() == false) {
        Log.i(TAG, rest.lastErrorText());
        return;
        }

    //  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..)
    int statusCode = rest.get_ResponseStatusCode();
    Log.i(TAG, "Response status code: " + String.valueOf(statusCode));

    if (statusCode != 101) {
        Log.i(TAG, responseBody);
        Log.i(TAG, "-- Failed because of unexpected response status code.");
        return;
        }

    //  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) {
        Log.i(TAG, ws.lastErrorText());
        return;
        }

    Log.i(TAG, "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...)

  }

  static {
      System.loadLibrary("chilkat");

      // Note: If the incorrect library name is passed to System.loadLibrary,
      // then you will see the following error message at application startup:
      //"The application <your-application-name> has stopped unexpectedly. Please try again."
  }
}