Function ngp_rcvdata

freebsd/netgraph/ng_pipe.c:588–716

* Receive data on a hook - both in upstream and downstream direction. * We put the frame on the inbound queue, and try to initiate dequeuing * sequence immediately. If inbound queue is full, discard one frame * depending on dropping policy (from the head or from the tail of the * queue). */

 * queue).
 */
static int
ngp_rcvdata(hook_p hook, item_p item)
{
	struct hookinfo *const hinfo = NG_HOOK_PRIVATE(hook);
	const priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
	struct timeval uuptime;
	struct timeval *now = &uuptime;
	struct ngp_fifo *ngp_f = NULL, *ngp_f1;
	struct ngp_hdr *ngp_h = NULL;
	struct mbuf *m;
	int hash, plen;
	int error = 0;

	/*
	 * Shortcut from inbound to outbound hook when neither of
	 * bandwidth, delay, BER or duplication probability is
	 * configured, nor we have queued frames to drain.
	 */
	if (hinfo->run.qin_frames == 0 && hinfo->run.qout_frames == 0 &&
	    hinfo->noqueue) {
		struct hookinfo *dest;
		if (hinfo == &priv->lower)
			dest = &priv->upper;
		else
			dest = &priv->lower;

		/* Send the frame. */
		plen = NGI_M(item)->m_pkthdr.len;
		NG_FWD_ITEM_HOOK(error, item, dest->hook);

		/* Update stats. */
		if (error) {
			hinfo->stats.out_disc_frames++;
			hinfo->stats.out_disc_octets += plen;
		} else {
			hinfo->stats.fwd_frames++;
			hinfo->stats.fwd_octets += plen;
		}

		return (error);
	}

	microuptime(now);

	/*
	 * If this was an empty queue, update service deadline time.
	 */
	if (hinfo->run.qin_frames == 0) {
		struct timeval *when = &hinfo->qin_utime;
		if (when->tv_sec < now->tv_sec || (when->tv_sec == now->tv_sec
		    && when->tv_usec < now->tv_usec)) {
			when->tv_sec = now->tv_sec;
			when->tv_usec = now->tv_usec;
		}
	}

	/* Populate the packet header */
	ngp_h = uma_zalloc(ngp_zone, M_NOWAIT);