(Xojo Plugin) 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.

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//  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
sshHostname = "www.my-ssh-server.com"
Dim sshPort As Int32
sshPort = 22

//  Connect to an SSH server and establish the SSH tunnel:
Dim success As Boolean
success = tunnel.SshOpenTunnel(sshHostname,sshPort)
If (success <> True) Then
    System.DebugLog(tunnel.LastErrorText)
    Return
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 <> True) Then
    System.DebugLog(tunnel.LastErrorText)
    Return
End If

//   OK, the SSH tunnel is setup.  Now open a channel within the tunnel.
Dim channel As Chilkat.Socket

Dim bTls As Boolean
bTls = True
Dim port As Int32
port = 443
Dim maxWaitMs As Int32
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 <> True) Then
    System.DebugLog(tunnel.LastErrorText)
    Return
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 <> True) Then
    System.DebugLog(rest.LastErrorText)

    Return
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 <> True) Then
    System.DebugLog(ws.LastErrorText)
    Return
End If

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

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

//  Do the open handshake.
Dim responseBody As String
responseBody = rest.FullRequestNoBody("GET","/something")
If (rest.LastMethodSuccess <> True) Then
    System.DebugLog(rest.LastErrorText)
    Return
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 Int32
statusCode = rest.ResponseStatusCode
System.DebugLog("Response status code: " + Str(statusCode))

If (statusCode <> 101) Then
    System.DebugLog(responseBody)
    System.DebugLog("-- Failed because of unexpected response status code.")
    Return
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 <> True) Then
    System.DebugLog(ws.LastErrorText)
    Return
End If

System.DebugLog("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...)