Function firewire_output

freebsd/net/if_fwsubr.c:80–332

};

static int
firewire_output(struct ifnet *ifp, struct mbuf *m, const struct sockaddr *dst,
    struct route *ro)
{
	struct fw_com *fc = IFP2FWC(ifp);
	int error, type;
	struct m_tag *mtag;
	union fw_encap *enc;
	struct fw_hwaddr *destfw;
	uint8_t speed;
	uint16_t psize, fsize, dsize;
	struct mbuf *mtail;
	int unicast, dgl, foff;
	static int next_dgl;
#if defined(INET) || defined(INET6)
	int is_gw = 0;
#endif

#ifdef MAC
	error = mac_ifnet_check_transmit(ifp, m);
	if (error)
		goto bad;
#endif

	if (!((ifp->if_flags & IFF_UP) &&
	   (ifp->if_drv_flags & IFF_DRV_RUNNING))) {
		error = ENETDOWN;
		goto bad;
	}

#if defined(INET) || defined(INET6)
	if (ro != NULL)
		is_gw = (ro->ro_flags & RT_HAS_GW) != 0;
#endif
	/*
	 * For unicast, we make a tag to store the lladdr of the
	 * destination. This might not be the first time we have seen
	 * the packet (for instance, the arp code might be trying to
	 * re-send it after receiving an arp reply) so we only
	 * allocate a tag if there isn't one there already. For
	 * multicast, we will eventually use a different tag to store
	 * the channel number.
	 */
	unicast = !(m->m_flags & (M_BCAST | M_MCAST));
	if (unicast) {
		mtag = m_tag_locate(m, MTAG_FIREWIRE, MTAG_FIREWIRE_HWADDR, NULL);
		if (!mtag) {
			mtag = m_tag_alloc(MTAG_FIREWIRE, MTAG_FIREWIRE_HWADDR,
			    sizeof (struct fw_hwaddr), M_NOWAIT);
			if (!mtag) {
				error = ENOMEM;
				goto bad;
			}
			m_tag_prepend(m, mtag);
		}
		destfw = (struct fw_hwaddr *)(mtag + 1);
	} else {
		destfw = NULL;