Function rtsock_msg_mbuf

freebsd/net/rtsock.c:1551–1628

* Writes information related to @rtinfo object to newly-allocated mbuf. * Assumes MCLBYTES is enough to construct any message. * Used for OS notifications of vaious events (if/ifa announces,etc) * * Returns allocated mbuf or NULL on failure. */

 * Returns allocated mbuf or NULL on failure.
 */
static struct mbuf *
rtsock_msg_mbuf(int type, struct rt_addrinfo *rtinfo)
{
	struct sockaddr_storage ss;
	struct rt_msghdr *rtm;
	struct mbuf *m;
	int i;
	struct sockaddr *sa;
#ifdef INET6
	struct sockaddr_in6 *sin6;
#endif
	int len, dlen;

	switch (type) {
	case RTM_DELADDR:
	case RTM_NEWADDR:
		len = sizeof(struct ifa_msghdr);
		break;

	case RTM_DELMADDR:
	case RTM_NEWMADDR:
		len = sizeof(struct ifma_msghdr);
		break;

	case RTM_IFINFO:
		len = sizeof(struct if_msghdr);
		break;

	case RTM_IFANNOUNCE:
	case RTM_IEEE80211:
		len = sizeof(struct if_announcemsghdr);
		break;

	default:
		len = sizeof(struct rt_msghdr);
	}

	/* XXXGL: can we use MJUMPAGESIZE cluster here? */
	KASSERT(len <= MCLBYTES, ("%s: message too big", __func__));
	if (len > MHLEN)
		m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR);
	else
		m = m_gethdr(M_NOWAIT, MT_DATA);
	if (m == NULL)
		return (m);

	m->m_pkthdr.len = m->m_len = len;
	rtm = mtod(m, struct rt_msghdr *);
	bzero((caddr_t)rtm, len);
	for (i = 0; i < RTAX_MAX; i++) {
		if ((sa = rtinfo->rti_info[i]) == NULL)
			continue;
		rtinfo->rti_addrs |= (1 << i);

		dlen = SA_SIZE(sa);
		KASSERT(dlen <= sizeof(ss),
		    ("%s: sockaddr size overflow", __func__));
		bzero(&ss, sizeof(ss));