Function ng_l2tp_rcvdata_lower

freebsd/netgraph/ng_l2tp.c:741–1003

* Handle an incoming frame from below. */

 * Handle an incoming frame from below.
 */
static int
ng_l2tp_rcvdata_lower(hook_p h, item_p item)
{
	static const u_int16_t req_bits[2][2] = {
		{ L2TP_DATA_0BITS, L2TP_DATA_1BITS },
		{ L2TP_CTRL_0BITS, L2TP_CTRL_1BITS },
	};
	const node_p node = NG_HOOK_NODE(h);
	const priv_p priv = NG_NODE_PRIVATE(node);
	hookpriv_p hpriv = NULL;
	hook_p hook = NULL;
	struct mbuf *m;
	u_int16_t tid, sid;
	u_int16_t hdr;
	u_int16_t ns, nr;
	int is_ctrl;
	int error;
	int len, plen;

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

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

	/* Grab mbuf */
	NGI_GET_M(item, m);

	/* Remember full packet length; needed for per session accounting. */
	plen = m->m_pkthdr.len;

	/* Update stats */
	priv->stats.recvPackets++;
	priv->stats.recvOctets += plen;

	/* Get initial header */
	if (m->m_pkthdr.len < 6) {
		priv->stats.recvRunts++;
		NG_FREE_ITEM(item);
		NG_FREE_M(m);
		ERROUT(EINVAL);
	}
	if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
		priv->stats.memoryFailures++;
		NG_FREE_ITEM(item);
		ERROUT(EINVAL);
	}
	hdr = (mtod(m, uint8_t *)[0] << 8) + mtod(m, uint8_t *)[1];
	m_adj(m, 2);

	/* Check required header bits and minimum length */
	is_ctrl = (hdr & L2TP_HDR_CTRL) != 0;
	if ((hdr & req_bits[is_ctrl][0]) != 0
	    || (~hdr & req_bits[is_ctrl][1]) != 0) {
		priv->stats.recvInvalid++;