typedef SilcBool (*SilcLogCb)(SilcLogType type, char *message,
                                  void *context);

    The logging custom callback function.  The `type' is the channel ID
    that triggered the event, which allows you to use the same callback
    function for multiple logging channels.

    The `message' parameter points to a null-terminated buffer containing
    the received message, while `context' is the caller-specified context.
    The message must not be modified or freed by the callback function.
    If the function returns TRUE, SilcLog will assume the message was
    handled and won't run its default handler.

    silc_log_set_callback