typedef bool (*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.

    silc_log_set_callback