Function cisco_input

freebsd/netgraph/ng_cisco.c:438–573

* Receive data */

 * Receive data
 */
static int
cisco_input(sc_p sc, item_p item)
{
	const struct cisco_header *h;
	struct cisco_header hdrbuf;
	struct protoent *pep;
	struct mbuf *m;
	int error = 0;

	/* Get data */
	m = NGI_M(item);

	/* Sanity check header length */
	if (m->m_pkthdr.len < sizeof(*h)) {
		error = EINVAL;
		goto drop;
	}

	/* Get cisco header */
	if (m->m_len >= sizeof(*h))			/* the common case */
		h = mtod(m, const struct cisco_header *);
	else {
		m_copydata(m, 0, sizeof(*h), (caddr_t)&hdrbuf);
		h = &hdrbuf;
	}
	m_adj(m, sizeof(*h));

	/* Check header address */
	switch (h->address) {
	default:		/* Invalid Cisco packet. */
		goto drop;
	case CISCO_UNICAST:
	case CISCO_MULTICAST:
		/* Don't check the control field here (RFC 1547). */
		switch (ntohs(h->protocol)) {
		default:
			goto drop;
		case CISCO_KEEPALIVE:
		    {
			const struct cisco_packet *p;
			struct cisco_packet pktbuf;

			/* Sanity check packet length */
			if (m->m_pkthdr.len < sizeof(*p)) {
				error = EINVAL;
				goto drop;
			}

			/* Get cisco packet */
			if (m->m_len >= sizeof(*p))	/* the common case */
				p = mtod(m, const struct cisco_packet *);
			else {
				m_copydata(m, 0, sizeof(*p), (caddr_t)&pktbuf);
				p = &pktbuf;
			}

			/* Check packet type */
			switch (ntohl(p->type)) {