PureBasic

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. PureBasic

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

Procedure ChilkatExample()

    success.i = 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.

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

    sshHostname.s = "sftp.example.com"
    sshPort.i = 22

    ; Connect to an SSH server and establish the SSH tunnel:
    success = CkSocket::ckSshOpenTunnel(tunnel,sshHostname,sshPort)
    If success = 0
        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 = 0
        Debug CkSocket::ckLastErrorText(tunnel)
        CkSocket::ckDispose(tunnel)
        ProcedureReturn
    EndIf

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

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

    success = CkSocket::ckSshNewChannel(tunnel,"some-websocket-server.com",port,bTls,maxWaitMs,channel)
    If success = 0
        Debug CkSocket::ckLastErrorText(tunnel)
        CkSocket::ckDispose(tunnel)
        CkSocket::ckDispose(channel)
        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 = 0
        Debug CkRest::ckLastErrorText(rest)
        CkSocket::ckDispose(tunnel)
        CkSocket::ckDispose(channel)
        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 = 0
        Debug CkWebSocket::ckLastErrorText(ws)
        CkSocket::ckDispose(tunnel)
        CkSocket::ckDispose(channel)
        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) = 0
        Debug CkRest::ckLastErrorText(rest)
        CkSocket::ckDispose(tunnel)
        CkSocket::ckDispose(channel)
        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)
        CkSocket::ckDispose(channel)
        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 = 0
        Debug CkWebSocket::ckLastErrorText(ws)
        CkSocket::ckDispose(tunnel)
        CkSocket::ckDispose(channel)
        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)
    CkSocket::ckDispose(channel)
    CkRest::ckDispose(rest)
    CkWebSocket::ckDispose(ws)


    ProcedureReturn
EndProcedure