(PureBasic) 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.

Chilkat PureBasic Module Download Chilkat PureBasic Module

IncludeFile "CkSocket.pb"
IncludeFile "CkRest.pb"
IncludeFile "CkWebSocket.pb"

Procedure ChilkatExample()

    ;  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.

    tunnel.i = CkSocket::ckCreate()
    If tunnel.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    sshHostname.s = "www.my-ssh-server.com"
    sshPort.i = 22

    ;  Connect to an SSH server and establish the SSH tunnel:
    success.i = CkSocket::ckSshOpenTunnel(tunnel,sshHostname,sshPort)
    If success <> 1
        Debug CkSocket::ckLastErrorText(tunnel)
        CkSocket::ckDispose(tunnel)
        ProcedureReturn
    EndIf

    ;  Authenticate with the SSH server via a login/password
    ;  or with a public key.
    ;  This example demonstrates SSH password authentication.
    success = CkSocket::ckSshAuthenticatePw(tunnel,"mySshLogin","mySshPassword")
    If success <> 1
        Debug CkSocket::ckLastErrorText(tunnel)
        CkSocket::ckDispose(tunnel)
        ProcedureReturn
    EndIf

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

    bTls.i = 1
    port.i = 443
    maxWaitMs.i = 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 = CkSocket::ckSshOpenChannel(tunnel,"some-websocket-server.com",port,bTls,maxWaitMs)
    If CkSocket::ckLastMethodSuccess(tunnel) <> 1
        Debug CkSocket::ckLastErrorText(tunnel)
        CkSocket::ckDispose(tunnel)
        ProcedureReturn
    EndIf

    ;  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.i = CkRest::ckCreate()
    If rest.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkRest::ckUseConnection(rest,channel,0)
    If success <> 1
        Debug CkRest::ckLastErrorText(rest)
        CkSocket::ckDispose(channel)

        CkSocket::ckDispose(tunnel)
        CkRest::ckDispose(rest)
        ProcedureReturn
    EndIf

    ;  Finally, tell our WebSocket object to use the Rest object..
    ws.i = CkWebSocket::ckCreate()
    If ws.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ;  Tell the WebSocket to use this connection.
    success = CkWebSocket::ckUseConnection(ws,rest)
    If success <> 1
        Debug CkWebSocket::ckLastErrorText(ws)
        CkSocket::ckDispose(tunnel)
        CkRest::ckDispose(rest)
        CkWebSocket::ckDispose(ws)
        ProcedureReturn
    EndIf

    ;  Add the standard WebSocket open handshake headers that will be needed.
    ;  (This adds the required HTTP request headers to the rest object.)
    CkWebSocket::ckAddClientHeaders(ws)

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

    ;  Do the open handshake.
    responseBody.s = CkRest::ckFullRequestNoBody(rest,"GET","/something")
    If CkRest::ckLastMethodSuccess(rest) <> 1
        Debug CkRest::ckLastErrorText(rest)
        CkSocket::ckDispose(tunnel)
        CkRest::ckDispose(rest)
        CkWebSocket::ckDispose(ws)
        ProcedureReturn
    EndIf

    ;  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.i = CkRest::ckResponseStatusCode(rest)
    Debug "Response status code: " + Str(statusCode)

    If statusCode <> 101
        Debug responseBody
        Debug "-- Failed because of unexpected response status code."
        CkSocket::ckDispose(tunnel)
        CkRest::ckDispose(rest)
        CkWebSocket::ckDispose(ws)
        ProcedureReturn
    EndIf

    ;  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 = CkWebSocket::ckValidateServerHandshake(ws)
    If success <> 1
        Debug CkWebSocket::ckLastErrorText(ws)
        CkSocket::ckDispose(tunnel)
        CkRest::ckDispose(rest)
        CkWebSocket::ckDispose(ws)
        ProcedureReturn
    EndIf

    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...)


    CkSocket::ckDispose(tunnel)
    CkRest::ckDispose(rest)
    CkWebSocket::ckDispose(ws)


    ProcedureReturn
EndProcedure