typedef SilcBool (*SilcPacketReceiveCb)(SilcPacketEngine engine,
                                            SilcPacketStream stream,
                                            SilcPacket packet,
                                            void *callback_context,
                                            void *stream_context);

    The packet receive callback is called by the packet engine when a new
    SILC Packet has arrived.  The application must free the returned
    SilcPacket with silc_packet_free if it takes the packet in for
    processing.  This callback is set in the SilcPacketCallbacks structure.
    The `callback_context' is the context set as argument in the
    silc_packet_engine_start function.  The `stream_context' is stream
    specific context that was set by calling silc_packet_set_context.

    If the application takes the received packet `packet' into processing
    TRUE must be returned.  If FALSE is returned the packet engine will
    pass the packet to other packet processor, if one has been linked
    to the stream with silc_packet_stream_link function.  If no extra
    processor is linked the packet is dropped.

    SilcBool
    silc_foo_packet_receive_cb(SilcPacketEngine engine,
                               SilcPacketStream stream, SilcPacket packet,
                               void *callback_context, void *stream_context)
    {
      Application ctx = callback_context;

      // If we're not up yet, let's not process the packet
      if (ctx->initialized == FALSE)
        return FALSE;

      // Process the incoming packet...
      ...

      // It's our packet now, no one else will get it
      return TRUE;
    }