Method asyncReceive

src/remote/server/server.cpp:7087–7169

SSHORT rem_port::asyncReceive(PACKET* asyncPacket, const UCHAR* buffer, SSHORT dataSize)
{
/**************************************
 *
 *	a s y n c R e c e i v e
 *
 **************************************
 *
 * Functional description
 *	If possible, accept incoming data asynchronously
 *
 **************************************/
	if (! port_async_receive)
	{
		return 0;
	}
	if (haveRecvData())
	{
		// We have no reliable way to distinguish network packet that start
		// from the beginning of XDR packet or in the middle of it.
		// Therefore try to process asynchronously only if there is no data
		// waiting in port queue. This can lead to fallback to synchronous
		// processing of async command (i.e. with some delay), but reliably
		// protects from spurious protocol breakage.
		return 0;
	}

	SLONG original_op = xdr_peek_long(port_async_receive->port_receive, buffer, dataSize);

	switch (original_op)
	{
	case op_cancel:
	case op_abort_aux_connection:
	case op_crypt_key_callback:
		break;
	default:
		return 0;
	}

	{ // scope for guard
		static GlobalPtr<Mutex> mutex;
		MutexLockGuard guard(mutex, FB_FUNCTION);

		port_async_receive->clearRecvQue();
		port_async_receive->port_receive->x_handy = 0;
		port_async_receive->port_protocol = port_protocol;
		memcpy(port_async_receive->port_queue.add().getBuffer(dataSize), buffer, dataSize);

		// It's required, that async packets follow simple rule:
		// xdr packet fits into network packet.
		port_async_receive->receive(asyncPacket);
	}

	const SSHORT asyncSize = dataSize - port_async_receive->port_receive->x_handy;
	fb_assert(asyncSize >= 0);

	switch (asyncPacket->p_operation)
	{