Function divert_packet

freebsd/netinet/ip_divert.c:190–301

* Divert a packet by passing it up to the divert socket at port 'port'. * * Setup generic address and protocol structures for div_input routine, * then pass them along with mbuf chain. */

 * then pass them along with mbuf chain.
 */
static void
divert_packet(struct mbuf *m, bool incoming)
{
	struct ip *ip;
	struct inpcb *inp;
	struct socket *sa;
	u_int16_t nport;
	struct sockaddr_in divsrc;
	struct m_tag *mtag;

	NET_EPOCH_ASSERT();

	mtag = m_tag_locate(m, MTAG_IPFW_RULE, 0, NULL);
	if (mtag == NULL) {
		m_freem(m);
		return;
	}
	/* Assure header */
	if (m->m_len < sizeof(struct ip) &&
	    (m = m_pullup(m, sizeof(struct ip))) == NULL)
		return;
	ip = mtod(m, struct ip *);

	/* Delayed checksums are currently not compatible with divert. */
	if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
		in_delayed_cksum(m);
		m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
	}
#if defined(SCTP) || defined(SCTP_SUPPORT)
	if (m->m_pkthdr.csum_flags & CSUM_SCTP) {
		sctp_delayed_cksum(m, (uint32_t)(ip->ip_hl << 2));
		m->m_pkthdr.csum_flags &= ~CSUM_SCTP;
	}
#endif
	bzero(&divsrc, sizeof(divsrc));
	divsrc.sin_len = sizeof(divsrc);
	divsrc.sin_family = AF_INET;
	/* record matching rule, in host format */
	divsrc.sin_port = ((struct ipfw_rule_ref *)(mtag+1))->rulenum;
	/*
	 * Record receive interface address, if any.
	 * But only for incoming packets.
	 */
	if (incoming) {
		struct ifaddr *ifa;
		struct ifnet *ifp;

		/* Sanity check */
		M_ASSERTPKTHDR(m);

		/* Find IP address for receive interface */
		ifp = m->m_pkthdr.rcvif;
		CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
			if (ifa->ifa_addr->sa_family != AF_INET)
				continue;
			divsrc.sin_addr =
			    ((struct sockaddr_in *) ifa->ifa_addr)->sin_addr;
			break;