Introduce an interface announcement message for the routing

socket so that routing daemons and other interested parties
know when an interface is attached/detached.

PR:		kern/33747
Obtained from:	NetBSD
MFC after:	2 weeks

sbin/route/route.c

@@ -1335,6 +1335,7 @@ char *msgtypes[] = {
 	"RTM_IFINFO: iface status change",
 	"RTM_NEWMADDR: new multicast group membership on iface",
 	"RTM_DELMADDR: multicast group membership removed from iface",
+	"RTM_IFANNOUNCE: interface arrival/departure",
 	0,
 };
 
@@ -1363,6 +1364,7 @@ print_rtmsg(rtm, msglen)
 #ifdef RTM_NEWMADDR
 	struct ifma_msghdr *ifmam;
 #endif
+	struct if_announcemsghdr *ifan;
 
 	if (verbose == 0)
 		return;
@@ -1371,7 +1373,11 @@ print_rtmsg(rtm, msglen)
 		    rtm->rtm_version);
 		return;
 	}
-	(void)printf("%s: len %d, ", msgtypes[rtm->rtm_type], rtm->rtm_msglen);
+	if (msgtypes[rtm->rtm_type] != NULL)
+		(void)printf("%s: ", msgtypes[rtm->rtm_type]);
+	else
+		(void)printf("#%d: ", rtm->rtm_type);
+	(void)printf("len %d, ", rtm->rtm_msglen);
 	switch (rtm->rtm_type) {
 	case RTM_IFINFO:
 		ifm = (struct if_msghdr *)rtm;
@@ -1393,6 +1399,23 @@ print_rtmsg(rtm, msglen)
 		pmsg_addrs((char *)(ifmam + 1), ifmam->ifmam_addrs);
 		break;
 #endif
+	case RTM_IFANNOUNCE:
+		ifan = (struct if_announcemsghdr *)rtm;
+		(void) printf("if# %d, what: ", ifan->ifan_index);
+		switch (ifan->ifan_what) {
+		case IFAN_ARRIVAL:
+			printf("arrival");
+			break;
+		case IFAN_DEPARTURE:
+			printf("departure");
+			break;
+		default:
+			printf("#%d", ifan->ifan_what);
+			break;
+		}
+		printf("\n");
+		break;
+
 	default:
 		(void) printf("pid: %ld, seq %d, errno %d, flags:",
 			(long)rtm->rtm_pid, rtm->rtm_seq, rtm->rtm_errno);

share/man/man4/route.4

@@ -32,7 +32,7 @@
 .\"     From: @(#)route.4	8.6 (Berkeley) 4/19/94
 .\" $FreeBSD$
 .\"
-.Dd October 8, 1996
+.Dd January 18, 2002
 .Dt ROUTE 4
 .Os
 .Sh NAME
@@ -198,6 +198,7 @@ Messages include:
 #define	RTM_IFINFO	0xe    /* iface going up/down etc. */
 #define	RTM_NEWMADDR	0xf    /* mcast group membership being added to if */
 #define	RTM_DELMADDR	0x10   /* mcast group membership being deleted */
+#define	RTM_IFANNOUNCE	0x11   /* iface arrival/departure */
 .Ed
 .Pp
 A message header consists of one of the following:
@@ -245,6 +246,15 @@ struct ifma_msghdr {
     int     ifmam_flags;        /* value of ifa_flags */
     u_short ifmam_index;        /* index for associated ifp */
 };
+
+struct if_announcemsghdr {
+	u_short	ifan_msglen;	/* to skip over non-understood messages */
+	u_char	ifan_version;	/* future binary compatibility */
+	u_char	ifan_type;	/* message type */
+	u_short	ifan_index;	/* index for associated ifp */
+	char	ifan_name[IFNAMSIZ]; /* if name, e.g. "en0" */
+	u_short	ifan_what;	/* what type of announcement */
+};
 .Ed
 .Pp
 The
@@ -262,7 +272,12 @@ header, the
 and
 .Dv RTM_DELMADDR
 messages use a
-.Ar ifma_msghdr ,
+.Vt ifma_msghdr
+header, the
+.Dv RTM_IFANNOUNCE
+message uses a
+.Vt if_announcemsghdr
+header,
 and all other messages use the
 .Ar rt_msghdr
 header.

sys/net/if.c

@@ -430,6 +430,9 @@ if_attach(ifp)
 		TAILQ_INSERT_HEAD(&ifp->if_addrhead, ifa, ifa_link);
 	}
 	ifp->if_broadcastaddr = 0; /* reliably crash if used uninitialized */
+
+	/* Announce the interface. */
+	rt_ifannouncemsg(ifp, IFAN_ARRIVAL);
 }
 
 /*
@@ -511,6 +514,9 @@ if_detach(ifp)
 		(void) rnh->rnh_walktree(rnh, if_rtdel, ifp);
 	}
 
+	/* Announce that the interface is gone. */
+	rt_ifannouncemsg(ifp, IFAN_DEPARTURE);
+
 	KNOTE(&ifp->if_klist, NOTE_EXIT);
 	TAILQ_REMOVE(&ifnet, ifp, if_link);
 	mtx_destroy(&ifp->if_snd.ifq_mtx);

sys/net/if.h

@@ -196,6 +196,21 @@ struct ifma_msghdr {
 	u_short	ifmam_index;	/* index for associated ifp */
 };
 
+/*
+ * Message format announcing the arrival or departure of a network interface.
+ */
+struct if_announcemsghdr {
+	u_short	ifan_msglen;	/* to skip over non-understood messages */
+	u_char	ifan_version;	/* future binary compatibility */
+	u_char	ifan_type;	/* message type */
+	u_short	ifan_index;	/* index for associated ifp */
+	char	ifan_name[IFNAMSIZ]; /* if name, e.g. "en0" */
+	u_short	ifan_what;	/* what type of announcement */
+};
+
+#define	IFAN_ARRIVAL	0	/* interface arrival */
+#define	IFAN_DEPARTURE	1	/* interface departure */
+
 /*
  * Interface request structure used for socket
  * ioctl's.  All interface ioctl's must have parameter

sys/net/route.h

@@ -207,6 +207,7 @@ struct rt_msghdr {
 #define RTM_IFINFO	0xe	/* iface going up/down etc. */
 #define	RTM_NEWMADDR	0xf	/* mcast group membership being added to if */
 #define	RTM_DELMADDR	0x10	/* mcast group membership being deleted */
+#define	RTM_IFANNOUNCE	0x11	/* iface arrival/departure */
 
 /*
  * Bitmask values for rtm_inits and rmx_locks.
@@ -277,6 +278,7 @@ struct ifmultiaddr;
 
 void	 route_init __P((void));
 int	 rt_getifa __P((struct rt_addrinfo *));
+void	 rt_ifannouncemsg __P((struct ifnet *, int));
 void	 rt_ifmsg __P((struct ifnet *));
 void	 rt_missmsg __P((int, struct rt_addrinfo *, int, int));
 void	 rt_newaddrmsg __P((int, struct ifaddr *, int, struct rtentry *));

sys/net/rtsock.c

@@ -595,6 +595,10 @@ rt_msg1(type, rtinfo)
 		len = sizeof(struct if_msghdr);
 		break;
 
+	case RTM_IFANNOUNCE:
+		len = sizeof(struct if_announcemsghdr);
+		break;
+
 	default:
 		len = sizeof(struct rt_msghdr);
 	}
@@ -860,6 +864,34 @@ rt_newmaddrmsg(cmd, ifma)
 	raw_input(m, &route_proto, &route_src, &route_dst);
 }
 
+/*
+ * This is called to generate routing socket messages indicating
+ * network interface arrival and departure.
+ */
+void
+rt_ifannouncemsg(ifp, what)
+	struct ifnet *ifp;
+	int what;
+{
+	struct if_announcemsghdr *ifan;
+	struct mbuf *m;
+	struct rt_addrinfo info;
+
+	if (route_cb.any_count == 0)
+		return;
+	bzero((caddr_t)&info, sizeof(info));
+	m = rt_msg1(RTM_IFANNOUNCE, &info);
+	if (m == NULL)
+		return;
+	ifan = mtod(m, struct if_announcemsghdr *);
+	ifan->ifan_index = ifp->if_index;
+	snprintf(ifan->ifan_name, sizeof(ifan->ifan_name),
+	    "%s%d", ifp->if_name, ifp->if_unit);
+	ifan->ifan_what = what;
+	route_proto.sp_protocol = 0;
+	raw_input(m, &route_proto, &route_src, &route_dst);
+ }
+
 /*
  * This is used in dumping the kernel table via sysctl().
  */