Authenticates the request against the service.

        @param request: The AMF request
        @type request: L{Request<pyamf.remoting.Request>}

def authenticateRequest(self, request, service_request, *args, **kwargs):
        """
        Authenticates the request against the service.

        @param request: The AMF request
        @type request: L{Request<pyamf.remoting.Request>}
        """
        username = password = None

        if 'Credentials' in request.headers:
            cred = request.headers['Credentials']

            username = cred['userid']
            password = cred['password']

        return self.gateway.authenticateRequest(service_request, username,
            password, *args, **kwargs)