(Go) 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.

Note: This example requires Chilkat v11.0.0 or greater.

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    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_Ref.html">Socket object to establish a connection to the WebSocket_Ref.html">WebSocket server through an SSH Tunnel.
    // Next, the Rest_Ref.html">Rest object uses the Socket_Ref.html">Socket object for its connection.
    // Finally, the WebSocket_Ref.html">WebSocket object uses the Rest_Ref.html">Rest object for its connection.  
    // 
    // Hopefully the flexibility of this architecture is easy to see.  All of the HTTP functionality of the Rest_Ref.html">Rest object,
    // such as HTTP authentication, custom headers, etc. is available to the WebSocket_Ref.html">WebSocket.  Likewise, all of the advanced functionality
    // of the Socket_Ref.html">Socket object is in turn available to the Rest_Ref.html">Rest object.  

    // The high-level steps for accomplishing the task of running the WebSocket_Ref.html">WebSocket protocol through an SSH accomplished as follows:
    // 1) Create the SSH tunnel using Chilkat Socket_Ref.html">Socket.
    // 2) Open a port-forwarding channel (to the WebSocket_Ref.html">WebSocket server) within the tunnel.
    // 2) Tell Rest_Ref.html">Rest to use the Socket_Ref.html">Socket object.
    // 3) Tell WebSocket_Ref.html">WebSocket to use the Rest_Ref.html">Rest object.

    tunnel := Socket_Ref.html">chilkat.NewSocket()

    sshHostname := "sftp.example.com"
    sshPort := 22

    // Connect to an SSH server and establish the SSH tunnel:
    success = tunnel.SshOpenTunnel(sshHostname,sshPort)
    if success == false {
        fmt.Println(tunnel.LastErrorText())
        tunnel.DisposeSocket()
        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 {
        fmt.Println(tunnel.LastErrorText())
        tunnel.DisposeSocket()
        return
    }

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

    bTls := true
    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_Ref.html">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.
    channel := Socket_Ref.html">chilkat.NewSocket()
    success = tunnel.SshNewChannel("some-websocket-server.com",port,bTls,maxWaitMs,channel)
    if success == false {
        fmt.Println(tunnel.LastErrorText())
        tunnel.DisposeSocket()
        channel.DisposeSocket()
        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.
    rest := Rest_Ref.html">chilkat.NewRest()
    success = rest.UseConnection(channel,false)
    if success == false {
        fmt.Println(rest.LastErrorText())
        tunnel.DisposeSocket()
        channel.DisposeSocket()
        rest.DisposeRest()
        return
    }

    // Finally, tell our WebSocket_Ref.html">WebSocket object to use the Rest_Ref.html">Rest object..
    ws := WebSocket_Ref.html">chilkat.NewWebSocket()

    // Tell the WebSocket_Ref.html">WebSocket to use this connection.
    success = ws.UseConnection(rest)
    if success == false {
        fmt.Println(ws.LastErrorText())
        tunnel.DisposeSocket()
        channel.DisposeSocket()
        rest.DisposeRest()
        ws.DisposeWebSocket()
        return
    }

    // Add the standard WebSocket_Ref.html">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_Ref.html">WebSocket-Protocol" and "Origin".
    rest.AddHeader("Sec-WebSocket_Ref.html">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() == false {
        fmt.Println(rest.LastErrorText())
        tunnel.DisposeSocket()
        channel.DisposeSocket()
        rest.DisposeRest()
        ws.DisposeWebSocket()
        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..)
    statusCode := rest.ResponseStatusCode()
    fmt.Println("Response status code: ", statusCode)

    if statusCode != 101 {
        fmt.Println(*responseBody)
        fmt.Println("-- Failed because of unexpected response status code.")
        tunnel.DisposeSocket()
        channel.DisposeSocket()
        rest.DisposeRest()
        ws.DisposeWebSocket()
        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_Ref.html">WebSocket-Accept header. 
    success = ws.ValidateServerHandshake()
    if success == false {
        fmt.Println(ws.LastErrorText())
        tunnel.DisposeSocket()
        channel.DisposeSocket()
        rest.DisposeRest()
        ws.DisposeWebSocket()
        return
    }

    fmt.Println("WebSocket_Ref.html">WebSocket connection successful.")

    // The application may now begin sending and receiving frames on the WebSocket_Ref.html">WebSocket connection.
    // (At this point, we're done with the rest object...)

    tunnel.DisposeSocket()
    channel.DisposeSocket()
    rest.DisposeRest()
    ws.DisposeWebSocket()