Function ng_l2tp_rcvdata_ctrl

freebsd/netgraph/ng_l2tp.c:1008–1085

* Handle an outgoing control frame. */

 * Handle an outgoing control frame.
 */
static int
ng_l2tp_rcvdata_ctrl(hook_p hook, item_p item)
{
	const node_p node = NG_HOOK_NODE(hook);
	const priv_p priv = NG_NODE_PRIVATE(node);
	struct l2tp_seq *const seq = &priv->seq;
	struct mbuf *m;
	int error;
	int i;
	u_int16_t	ns;

	/* Sanity check */
	L2TP_SEQ_CHECK(&priv->seq);

	/* If not configured, reject */
	if (!priv->conf.enabled) {
		NG_FREE_ITEM(item);
		ERROUT(ENXIO);
	}

	/* Grab mbuf and discard other stuff XXX */
	NGI_GET_M(item, m);
	NG_FREE_ITEM(item);

	/* Packet should have session ID prepended */
	if (m->m_pkthdr.len < 2) {
		priv->stats.xmitInvalid++;
		m_freem(m);
		ERROUT(EINVAL);
	}

	/* Check max length */
	if (m->m_pkthdr.len >= 0x10000 - 14) {
		priv->stats.xmitTooBig++;
		m_freem(m);
		ERROUT(EOVERFLOW);
	}

	mtx_lock(&seq->mtx);

	/* Find next empty slot in transmit queue */
	for (i = 0; i < L2TP_MAX_XWIN && seq->xwin[i] != NULL; i++);
	if (i == L2TP_MAX_XWIN) {
		mtx_unlock(&seq->mtx);
		priv->stats.xmitDrops++;
		m_freem(m);
		ERROUT(ENOBUFS);
	}
	seq->xwin[i] = m;

	/* If peer's receive window is already full, nothing else to do */
	if (i >= seq->cwnd) {
		mtx_unlock(&seq->mtx);
		ERROUT(0);
	}

	/* Start retransmit timer if not already running */
	if (!callout_active(&seq->rack_timer))