VB.NET Requires Chilkat v11.0.0+

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. VB.NET

Dim success As Boolean = 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.

Dim tunnel As New Chilkat.Socket

Dim sshHostname As String = "sftp.example.com"
Dim sshPort As Integer = 22

'  Connect to an SSH server and establish the SSH tunnel:
success = tunnel.SshOpenTunnel(sshHostname,sshPort)
If (success = False) Then
    Debug.WriteLine(tunnel.LastErrorText)
    Exit Sub
End If


'  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
    Debug.WriteLine(tunnel.LastErrorText)
    Exit Sub
End If


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

Dim bTls As Boolean = True
Dim port As Integer = 443
Dim maxWaitMs As Integer = 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.
Dim channel As New Chilkat.Socket
success = tunnel.SshNewChannel("some-websocket-server.com",port,bTls,maxWaitMs,channel)
If (success = False) Then
    Debug.WriteLine(tunnel.LastErrorText)
    Exit Sub
End If


'  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.
Dim rest As New Chilkat.Rest
success = rest.UseConnection(channel,False)
If (success = False) Then
    Debug.WriteLine(rest.LastErrorText)
    Exit Sub
End If


'  Finally, tell our WebSocket object to use the Rest object..
Dim ws As New Chilkat.WebSocket

'  Tell the WebSocket to use this connection.
success = ws.UseConnection(rest)
If (success = False) Then
    Debug.WriteLine(ws.LastErrorText)
    Exit Sub
End If


'  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.
Dim responseBody As String = rest.FullRequestNoBody("GET","/something")
If (rest.LastMethodSuccess = False) Then
    Debug.WriteLine(rest.LastErrorText)
    Exit Sub
End If


'  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..)
Dim statusCode As Integer = rest.ResponseStatusCode
Debug.WriteLine("Response status code: " & statusCode)

If (statusCode <> 101) Then
    Debug.WriteLine(responseBody)
    Debug.WriteLine("-- Failed because of unexpected response status code.")
    Exit Sub
End If


'  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
    Debug.WriteLine(ws.LastErrorText)
    Exit Sub
End If


Debug.WriteLine("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...)