PowerBuilder

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. PowerBuilder

integer li_rc
integer li_Success
oleobject loo_Tunnel
string ls_SshHostname
integer li_SshPort
integer li_BTls
integer li_Port
integer li_MaxWaitMs
oleobject loo_Channel
oleobject loo_Rest
oleobject loo_Ws
string ls_ResponseBody
integer li_StatusCode

li_Success = 0

// 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.

loo_Tunnel = create oleobject
li_rc = loo_Tunnel.ConnectToNewObject("Chilkat.Socket")
if li_rc < 0 then
    destroy loo_Tunnel
    MessageBox("Error","Connecting to COM object failed")
    return
end if

ls_SshHostname = "sftp.example.com"
li_SshPort = 22

// Connect to an SSH server and establish the SSH tunnel:
li_Success = loo_Tunnel.SshOpenTunnel(ls_SshHostname,li_SshPort)
if li_Success = 0 then
    Write-Debug loo_Tunnel.LastErrorText
    destroy loo_Tunnel
    return
end if

// Authenticate with the SSH server via a login/password
// or with a public key.
// This example demonstrates SSH password authentication.
li_Success = loo_Tunnel.SshAuthenticatePw("mySshLogin","mySshPassword")
if li_Success = 0 then
    Write-Debug loo_Tunnel.LastErrorText
    destroy loo_Tunnel
    return
end if

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

li_BTls = 1
li_Port = 443
li_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.
loo_Channel = create oleobject
li_rc = loo_Channel.ConnectToNewObject("Chilkat.Socket")

li_Success = loo_Tunnel.SshNewChannel("some-websocket-server.com",li_Port,li_BTls,li_MaxWaitMs,loo_Channel)
if li_Success = 0 then
    Write-Debug loo_Tunnel.LastErrorText
    destroy loo_Tunnel
    destroy loo_Channel
    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.
loo_Rest = create oleobject
li_rc = loo_Rest.ConnectToNewObject("Chilkat.Rest")

li_Success = loo_Rest.UseConnection(loo_Channel,0)
if li_Success = 0 then
    Write-Debug loo_Rest.LastErrorText
    destroy loo_Tunnel
    destroy loo_Channel
    destroy loo_Rest
    return
end if

// Finally, tell our WebSocket object to use the Rest object..
loo_Ws = create oleobject
li_rc = loo_Ws.ConnectToNewObject("Chilkat.WebSocket")

// Tell the WebSocket to use this connection.
li_Success = loo_Ws.UseConnection(loo_Rest)
if li_Success = 0 then
    Write-Debug loo_Ws.LastErrorText
    destroy loo_Tunnel
    destroy loo_Channel
    destroy loo_Rest
    destroy loo_Ws
    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.)
loo_Ws.AddClientHeaders()

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

// Do the open handshake.
ls_ResponseBody = loo_Rest.FullRequestNoBody("GET","/something")
if loo_Rest.LastMethodSuccess = 0 then
    Write-Debug loo_Rest.LastErrorText
    destroy loo_Tunnel
    destroy loo_Channel
    destroy loo_Rest
    destroy loo_Ws
    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..)
li_StatusCode = loo_Rest.ResponseStatusCode
Write-Debug "Response status code: " + string(li_StatusCode)

if li_StatusCode <> 101 then
    Write-Debug ls_ResponseBody
    Write-Debug "-- Failed because of unexpected response status code."
    destroy loo_Tunnel
    destroy loo_Channel
    destroy loo_Rest
    destroy loo_Ws
    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. 
li_Success = loo_Ws.ValidateServerHandshake()
if li_Success = 0 then
    Write-Debug loo_Ws.LastErrorText
    destroy loo_Tunnel
    destroy loo_Channel
    destroy loo_Rest
    destroy loo_Ws
    return
end if

Write-Debug "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...)


destroy loo_Tunnel
destroy loo_Channel
destroy loo_Rest
destroy loo_Ws