DataFlex

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. DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoTunnel
    String sSshHostname
    Integer iSshPort
    Boolean iBTls
    Integer iPort
    Integer iMaxWaitMs
    Variant vChannel
    Handle hoChannel
    Variant vRest
    Handle hoRest
    Handle hoWs
    String sResponseBody
    Integer iStatusCode
    String sTemp1
    Boolean bTemp1

    Move False To iSuccess

    // 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.

    Get Create (RefClass(cComChilkatSocket)) To hoTunnel
    If (Not(IsComObjectCreated(hoTunnel))) Begin
        Send CreateComObject of hoTunnel
    End

    Move "sftp.example.com" To sSshHostname
    Move 22 To iSshPort

    // Connect to an SSH server and establish the SSH tunnel:
    Get ComSshOpenTunnel Of hoTunnel sSshHostname iSshPort To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoTunnel To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Authenticate with the SSH server via a login/password
    // or with a public key.
    // This example demonstrates SSH password authentication.
    Get ComSshAuthenticatePw Of hoTunnel "mySshLogin" "mySshPassword" To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoTunnel To sTemp1
        Showln sTemp1
        Procedure_Return
    End

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

    Move True To iBTls
    Move 443 To iPort
    Move 5000 To iMaxWaitMs

    // 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.
    Get Create (RefClass(cComChilkatSocket)) To hoChannel
    If (Not(IsComObjectCreated(hoChannel))) Begin
        Send CreateComObject of hoChannel
    End
    Get pvComObject of hoChannel to vChannel
    Get ComSshNewChannel Of hoTunnel "some-websocket-server.com" iPort iBTls iMaxWaitMs vChannel To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoTunnel To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // 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.
    Get Create (RefClass(cComChilkatRest)) To hoRest
    If (Not(IsComObjectCreated(hoRest))) Begin
        Send CreateComObject of hoRest
    End
    Get pvComObject of hoChannel to vChannel
    Get ComUseConnection Of hoRest vChannel False To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoRest To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Finally, tell our WebSocket object to use the Rest object..
    Get Create (RefClass(cComChilkatWebSocket)) To hoWs
    If (Not(IsComObjectCreated(hoWs))) Begin
        Send CreateComObject of hoWs
    End

    // Tell the WebSocket to use this connection.
    Get pvComObject of hoRest to vRest
    Get ComUseConnection Of hoWs vRest To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoWs To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Add the standard WebSocket open handshake headers that will be needed.
    // (This adds the required HTTP request headers to the rest object.)
    Get ComAddClientHeaders Of hoWs To iSuccess

    // Add any additional headers that might be desired.
    // Two common WebSocketSpecific headers are "Sec-WebSocket-Protocol" and "Origin".
    Get ComAddHeader Of hoRest "Sec-WebSocket-Protocol" "x-some-websocket-subprotocol" To iSuccess
    Get ComAddHeader Of hoRest "Origin" "http://some-websocket-server.com" To iSuccess

    // Do the open handshake.
    Get ComFullRequestNoBody Of hoRest "GET" "/something" To sResponseBody
    Get ComLastMethodSuccess Of hoRest To bTemp1
    If (bTemp1 = False) Begin
        Get ComLastErrorText Of hoRest To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // 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..)
    Get ComResponseStatusCode Of hoRest To iStatusCode
    Showln "Response status code: " iStatusCode

    If (iStatusCode <> 101) Begin
        Showln sResponseBody
        Showln "-- Failed because of unexpected response status code."
        Procedure_Return
    End

    // 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. 
    Get ComValidateServerHandshake Of hoWs To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoWs To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Showln "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...)


End_Procedure