Function bpf_mtap2

freebsd/net/bpf.c:2348–2399

* Incoming linkage from device drivers, when packet is in * an mbuf chain and to be prepended by a contiguous header. */

 * an mbuf chain and to be prepended by a contiguous header.
 */
void
bpf_mtap2(struct bpf_if *bp, void *data, u_int dlen, struct mbuf *m)
{
	struct epoch_tracker et;
	struct bintime bt;
	struct mbuf mb;
	struct bpf_d *d;
	u_int pktlen, slen;
	int gottime;

	/* Skip outgoing duplicate packets. */
	if ((m->m_flags & M_PROMISC) != 0 && m->m_pkthdr.rcvif == NULL) {
		m->m_flags &= ~M_PROMISC;
		return;
	}

	pktlen = m_length(m, NULL);
	/*
	 * Craft on-stack mbuf suitable for passing to bpf_filter.
	 * Note that we cut corners here; we only setup what's
	 * absolutely needed--this mbuf should never go anywhere else.
	 */
	mb.m_flags = 0;
	mb.m_next = m;
	mb.m_data = data;
	mb.m_len = dlen;
	pktlen += dlen;

	gottime = BPF_TSTAMP_NONE;

	NET_EPOCH_ENTER(et);
	CK_LIST_FOREACH(d, &bp->bif_dlist, bd_next) {
		if (BPF_CHECK_DIRECTION(d, m->m_pkthdr.rcvif, bp->bif_ifp))
			continue;
		counter_u64_add(d->bd_rcount, 1);
		slen = bpf_filter(d->bd_rfilter, (u_char *)&mb, pktlen, 0);
		if (slen != 0) {
			BPFD_LOCK(d);

			counter_u64_add(d->bd_fcount, 1);
			if (gottime < bpf_ts_quality(d->bd_tstamp))
				gottime = bpf_gettime(&bt, d->bd_tstamp, m);
#ifdef MAC
			if (mac_bpfdesc_check_receive(d, bp->bif_ifp) == 0)
#endif
				catchpacket(d, (u_char *)&mb, pktlen, slen,
				    bpf_append_mbuf, &bt);
			BPFD_UNLOCK(d);
		}
	}
	NET_EPOCH_EXIT(et);
}

#undef	BPF_CHECK_DIRECTION
#undef	BPF_TSTAMP_NONE