Function ng_l2tp_seq_rack_timeout

freebsd/netgraph/ng_l2tp.c:1448–1499

* Handle a transmit timeout. The peer has failed to respond * with an ack for our packet, so retransmit it. */

 * with an ack for our packet, so retransmit it.
 */
static void
ng_l2tp_seq_rack_timeout(node_p node, hook_p hook, void *arg1, int arg2)
{
	const priv_p priv = NG_NODE_PRIVATE(node);
	struct l2tp_seq *const seq = &priv->seq;
	struct mbuf *m;
	u_int delay;

	/* Sanity check */
	L2TP_SEQ_CHECK(seq);

	mtx_lock(&seq->mtx);
	/* Make sure callout is still active before doing anything */
	if (callout_pending(&seq->rack_timer) ||
	    !callout_active(&seq->rack_timer)) {
		mtx_unlock(&seq->mtx);
		return;
	}

	priv->stats.xmitRetransmits++;

	/* Have we reached the retransmit limit? If so, notify owner. */
	if (seq->rexmits++ >= priv->conf.rexmit_max)
		ng_l2tp_seq_failure(priv);

	/* Restart timer, this time with an increased delay */
	delay = (seq->rexmits > 12) ? (1 << 12) : (1 << seq->rexmits);
	if (delay > priv->conf.rexmit_max_to)
		delay = priv->conf.rexmit_max_to;
	ng_callout(&seq->rack_timer, node, NULL,
	    hz * delay, ng_l2tp_seq_rack_timeout, NULL, 0);

	/* Do slow-start/congestion algorithm windowing algorithm */
	seq->ns = seq->rack;
	seq->ssth = (seq->cwnd + 1) / 2;
	seq->cwnd = 1;
	seq->acks = 0;

	/* Retransmit oldest unack'd packet */
	m = L2TP_COPY_MBUF(seq->xwin[0], M_NOWAIT);
	mtx_unlock(&seq->mtx);
	if (m == NULL)
		priv->stats.memoryFailures++;
	else
		ng_l2tp_xmit_ctrl(priv, m, seq->ns++);

	/* callout_deactivate() is not needed here 
	    as ng_callout() is getting called each time */

	/* Sanity check */
	L2TP_SEQ_CHECK(seq);
}

/*
 * Transmit a control stream packet, payload optional.