Retire struct sockaddr_inarp.

Since ARP and routing are separated, "proxy only" entries
don't have any meaning, thus we don't need additional field
in sockaddr to pass SIN_PROXY flag.

New kernel is binary compatible with old tools, since sizes
of sockaddr_inarp and sockaddr_in match, and sa_family are
filled with same value.

The structure declaration is left for compatibility with
third party software, but in tree code no longer use it.

Reviewed by:	ru, andre, net@

contrib/ipfilter/ipsend/44arp.c

@@ -72,7 +72,7 @@ char	*addr, *eaddr;
 	size_t	needed;
 	char	*lim, *buf, *next;
 	struct	rt_msghdr	*rtm;
-	struct	sockaddr_inarp	*sin;
+	struct	sockaddr_in	*sin;
 	struct	sockaddr_dl	*sdl;
 
 #ifdef	IPSEND
@@ -113,7 +113,7 @@ char	*addr, *eaddr;
 	for (next = buf; next < lim; next += rtm->rtm_msglen)
 	    {
 		rtm = (struct rt_msghdr *)next;
-		sin = (struct sockaddr_inarp *)(rtm + 1);
+		sin = (struct sockaddr_in *)(rtm + 1);
 		sdl = (struct sockaddr_dl *)(sin + 1);
 		if (!bcmp(addr, (char *)&sin->sin_addr,
 			  sizeof(struct in_addr)))

libexec/bootpd/rtmsg.c

@@ -106,9 +106,9 @@ static void getsocket () {
 }
 
 static struct	sockaddr_in so_mask = {8, 0, 0, { 0xffffffff}};
-static struct	sockaddr_inarp blank_sin = {sizeof(blank_sin), AF_INET }, sin_m;
+static struct	sockaddr_in blank_sin = {sizeof(blank_sin), AF_INET }, sin_m;
 static struct	sockaddr_dl blank_sdl = {sizeof(blank_sdl), AF_LINK }, sdl_m;
-static int	expire_time, flags, export_only, doing_proxy;
+static int	expire_time, flags, doing_proxy;
 static struct	{
 	struct	rt_msghdr m_rtm;
 	char	m_space[512];
@@ -122,7 +122,7 @@ int bsd_arp_set(ia, eaddr, len)
 	char *eaddr;
 	int len;
 {
-	register struct sockaddr_inarp *sin = &sin_m;
+	register struct sockaddr_in *sin = &sin_m;
 	register struct sockaddr_dl *sdl;
 	register struct rt_msghdr *rtm = &(m_rtmsg.m_rtm);
 	u_char *ea;
@@ -137,7 +137,7 @@ int bsd_arp_set(ia, eaddr, len)
 	ea = (u_char *)LLADDR(&sdl_m);
 	bcopy(eaddr, ea, len);
 	sdl_m.sdl_alen = len;
-	doing_proxy = flags = export_only = expire_time = 0;
+	doing_proxy = flags = expire_time = 0;
 
 	/* make arp entry temporary */
 	clock_gettime(CLOCK_MONOTONIC, &tp);
@@ -148,7 +148,7 @@ int bsd_arp_set(ia, eaddr, len)
 		report(LOG_WARNING, "rtmget: %s", strerror(errno));
 		return (1);
 	}
-	sin = (struct sockaddr_inarp *)(rtm + 1);
+	sin = (struct sockaddr_in *)(rtm + 1);
 	sdl = (struct sockaddr_dl *)(sin->sin_len + (char *)sin);
 	if (sin->sin_addr.s_addr == sin_m.sin_addr.s_addr) {
 		if (sdl->sdl_family == AF_LINK &&
@@ -163,13 +163,6 @@ int bsd_arp_set(ia, eaddr, len)
 				inet_ntoa(sin->sin_addr));
 			return (1);
 		}
-		if (sin_m.sin_other & SIN_PROXY) {
-			report(LOG_WARNING,
-				"set: proxy entry exists for non 802 device\n");
-			return(1);
-		}
-		sin_m.sin_other = SIN_PROXY;
-		export_only = 1;
 		goto tryagain;
 	}
 overwrite:
@@ -209,15 +202,10 @@ static int rtmsg(cmd)
 		rtm->rtm_rmx.rmx_expire = expire_time;
 		rtm->rtm_inits = RTV_EXPIRE;
 		rtm->rtm_flags |= (RTF_HOST | RTF_STATIC | RTF_LLDATA);
-		sin_m.sin_other = 0;
 		if (doing_proxy) {
-			if (export_only)
-				sin_m.sin_other = SIN_PROXY;
-			else {
 			rtm->rtm_addrs |= RTA_NETMASK;
 			rtm->rtm_flags &= ~RTF_HOST;
 		}
-		}
 		/* FALLTHROUGH */
 	case RTM_GET:
 		rtm->rtm_addrs |= RTA_DST;

sbin/route/route.c

@@ -86,7 +86,6 @@ union	sockunion {
 #endif
 	struct	sockaddr_at sat;
 	struct	sockaddr_dl sdl;
-	struct	sockaddr_inarp sinarp;
 	struct	sockaddr_storage ss; /* added to avoid memory overrun */
 } so_dst, so_gate, so_mask, so_genmask, so_ifa, so_ifp;
 
@@ -923,10 +922,8 @@ newroute(int argc, char **argv)
 		flags |= RTF_HOST;
 	if ((nrflags & F_INTERFACE) == 0)
 		flags |= RTF_GATEWAY;
-	if (nrflags & F_PROXY) {
+	if (nrflags & F_PROXY)
-		so_dst.sinarp.sin_other = SIN_PROXY;
 		flags |= RTF_ANNOUNCE;
-	}
 	if (dest == NULL)
 		dest = "";
 	if (gateway == NULL)

sys/net/if_llatbl.c

@@ -285,28 +285,8 @@ lla_rt_output(struct rt_msghdr *rtm, struct rt_addrinfo *info)
 
 	switch (rtm->rtm_type) {
 	case RTM_ADD:
-		if (rtm->rtm_flags & RTF_ANNOUNCE) {
+		if (rtm->rtm_flags & RTF_ANNOUNCE)
 			flags |= LLE_PUB;
-#ifdef INET
-			if (dst->sa_family == AF_INET &&
-			    ((struct sockaddr_inarp *)dst)->sin_other != 0) {
-				struct rtentry *rt;
-				((struct sockaddr_inarp *)dst)->sin_other = 0;
-				rt = rtalloc1(dst, 0, 0);
-				if (rt == NULL || !(rt->rt_flags & RTF_HOST)) {
-					log(LOG_INFO, "%s: RTM_ADD publish "
-					    "(proxy only) is invalid\n",
-					    __func__);
-					if (rt)
-						RTFREE_LOCKED(rt);
-					return EINVAL;
-				}
-				RTFREE_LOCKED(rt);
-
-				flags |= LLE_PROXY;
-			}
-#endif
-		}
 		flags |= LLE_CREATE;
 		break;
 
@@ -345,7 +325,7 @@ lla_rt_output(struct rt_msghdr *rtm, struct rt_addrinfo *info)
 			 * LLE_DELETED flag, and reset the expiration timer
 			 */
 			bcopy(LLADDR(dl), &lle->ll_addr, ifp->if_addrlen);
-			lle->la_flags |= (flags & (LLE_PUB | LLE_PROXY));
+			lle->la_flags |= (flags & LLE_PUB);
 			lle->la_flags |= LLE_VALID;
 			lle->la_flags &= ~LLE_DELETED;
 #ifdef INET6
@@ -368,14 +348,11 @@ lla_rt_output(struct rt_msghdr *rtm, struct rt_addrinfo *info)
 			LLE_WUNLOCK(lle);
 #ifdef INET
 			/* gratuitous ARP */
-			if ((laflags & LLE_PUB) && dst->sa_family == AF_INET) {
+			if ((laflags & LLE_PUB) && dst->sa_family == AF_INET)
 				arprequest(ifp,
 				    &((struct sockaddr_in *)dst)->sin_addr,
 				    &((struct sockaddr_in *)dst)->sin_addr,
-				    ((laflags & LLE_PROXY) ?
+				    (u_char *)LLADDR(dl));
-					(u_char *)IF_LLADDR(ifp) :
-					(u_char *)LLADDR(dl)));
-			}
 #endif
 		} else {
 			if (flags & LLE_EXCLUSIVE)

sys/net/if_llatbl.h

@@ -172,7 +172,6 @@ MALLOC_DECLARE(M_LLTABLE);
 #define	LLE_STATIC	0x0002	/* entry is static */
 #define	LLE_IFADDR	0x0004	/* entry is interface addr */
 #define	LLE_VALID	0x0008	/* ll_addr is valid */
-#define	LLE_PROXY	0x0010	/* proxy entry ??? */
 #define	LLE_PUB		0x0020	/* publish entry ??? */
 #define	LLE_LINKED	0x0040	/* linked to lookup structure */
 #define	LLE_EXCLUSIVE	0x2000	/* return lle xlocked  */

sys/netinet/if_ether.h

@@ -89,6 +89,7 @@ struct	ether_arp {
 #define	arp_pln	ea_hdr.ar_pln
 #define	arp_op	ea_hdr.ar_op
 
+#ifndef BURN_BRIDGES	/* Can be used by third party software. */
 struct sockaddr_inarp {
 	u_char	sin_len;
 	u_char	sin_family;
@@ -99,6 +100,8 @@ struct sockaddr_inarp {
 	u_short	sin_other;
 #define SIN_PROXY 1
 };
+#endif /* !BURN_BRIDGES  */
+
 /*
  * IP and ethernet specific routing flags
  */

sys/netinet/in.c

@@ -1494,7 +1494,7 @@ in_lltable_dump(struct lltable *llt, struct sysctl_req *wr)
 	/* XXX stack use */
 	struct {
 		struct rt_msghdr	rtm;
-		struct sockaddr_inarp	sin;
+		struct sockaddr_in	sin;
 		struct sockaddr_dl	sdl;
 	} arpc;
 	int error, i;
@@ -1515,7 +1515,7 @@ in_lltable_dump(struct lltable *llt, struct sysctl_req *wr)
 			/*
 			 * produce a msg made of:
 			 *  struct rt_msghdr;
-			 *  struct sockaddr_inarp; (IPv4)
+			 *  struct sockaddr_in; (IPv4)
 			 *  struct sockaddr_dl;
 			 */
 			bzero(&arpc, sizeof(arpc));
@@ -1529,12 +1529,8 @@ in_lltable_dump(struct lltable *llt, struct sysctl_req *wr)
 			arpc.sin.sin_addr.s_addr = SIN(lle)->sin_addr.s_addr;
 
 			/* publish */
-			if (lle->la_flags & LLE_PUB) {
+			if (lle->la_flags & LLE_PUB)
 				arpc.rtm.rtm_flags |= RTF_ANNOUNCE;
-				/* proxy only */
-				if (lle->la_flags & LLE_PROXY)
-					arpc.sin.sin_other = SIN_PROXY;
-			}
 
 			sdl = &arpc.sdl;
 			sdl->sdl_family = AF_LINK;

usr.sbin/arp/arp.8

@@ -28,7 +28,7 @@
 .\"     @(#)arp.8	8.1 (Berkeley) 6/6/93
 .\" $FreeBSD$
 .\"
-.Dd December 25, 2008
+.Dd January 31, 2013
 .Dt ARP 8
 .Os
 .Sh NAME
@@ -54,12 +54,12 @@
 .Fl s Ar hostname ether_addr
 .Op Cm temp
 .Op Cm blackhole No \&| Cm reject
-.Op Cm pub Op Cm only
+.Op Cm pub
 .Nm
 .Fl S Ar hostname ether_addr
 .Op Cm temp
 .Op Cm blackhole No \&| Cm reject
-.Op Cm pub Op Cm only
+.Op Cm pub
 .Nm
 .Fl f Ar filename
 .Sh DESCRIPTION
@@ -140,16 +140,6 @@ can be given as
 in which case the interfaces on this host will be examined,
 and if one of them is found to occupy the same subnet, its
 Ethernet address will be used.
-If the
-.Cm only
-keyword is also specified, this will create a
-.Dq "published (proxy only)"
-entry.
-This type of entry is created automatically if
-.Nm
-detects that a routing table entry for
-.Ar hostname
-already exists.
 .Pp
 If the
 .Cm reject
@@ -181,7 +171,7 @@ in the file should be of the form
 .Ar hostname ether_addr
 .Op Cm temp
 .Op Cm blackhole No \&| Cm reject
-.Op Cm pub Op Cm only
+.Op Cm pub
 .Ed
 .Pp
 with argument meanings as given above.

usr.sbin/arp/arp.c

@@ -81,28 +81,28 @@ __FBSDID("$FreeBSD$");
 #include <unistd.h>
 
 typedef void (action_fn)(struct sockaddr_dl *sdl,
-	struct sockaddr_inarp *s_in, struct rt_msghdr *rtm);
+	struct sockaddr_in *s_in, struct rt_msghdr *rtm);
 
 static int search(u_long addr, action_fn *action);
 static action_fn print_entry;
 static action_fn nuke_entry;
 
-static int delete(char *host, int do_proxy);
+static int delete(char *host);
 static void usage(void);
 static int set(int argc, char **argv);
 static int get(char *host);
 static int file(char *name);
 static struct rt_msghdr *rtmsg(int cmd,
-    struct sockaddr_inarp *dst, struct sockaddr_dl *sdl);
+    struct sockaddr_in *dst, struct sockaddr_dl *sdl);
 static int get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr);
-static struct sockaddr_inarp *getaddr(char *host);
+static struct sockaddr_in *getaddr(char *host);
 static int valid_type(int type);
 
 static int nflag;	/* no reverse dns lookups */
 static char *rifname;
 
 static time_t	expire_time;
-static int	flags, doing_proxy, proxy_only;
+static int	flags, doing_proxy;
 
 /* which function we're supposed to do */
 #define F_GET		1
@@ -179,7 +179,7 @@ main(int argc, char *argv[])
 		if (argc < 2 || argc > 6)
 			usage();
 		if (func == F_REPLACE)
-			(void)delete(argv[0], 0);
+			(void)delete(argv[0]);
 		rtn = set(argc, argv) ? 1 : 0;
 		break;
 	case F_DELETE:
@@ -187,15 +187,8 @@ main(int argc, char *argv[])
 			if (argc != 0)
 				usage();
 			search(0, nuke_entry);
-		} else {
+		} else
-			if (argc == 2 && strncmp(argv[1], "pub", 3) == 0)
+			rtn = delete(argv[0]);
-				ch = SIN_PROXY;
-			else if (argc == 1)
-				ch = 0;
-			else
-				usage();
-			rtn = delete(argv[0], ch);
-		}
 		break;
 	case F_FILESET:
 		if (argc != 1)
@@ -246,15 +239,15 @@ file(char *name)
 }
 
 /*
- * Given a hostname, fills up a (static) struct sockaddr_inarp with
+ * Given a hostname, fills up a (static) struct sockaddr_in with
  * the address of the host and returns a pointer to the
  * structure.
  */
-static struct sockaddr_inarp *
+static struct sockaddr_in *
 getaddr(char *host)
 {
 	struct hostent *hp;
-	static struct sockaddr_inarp reply;
+	static struct sockaddr_in reply;
 
 	bzero(&reply, sizeof(reply));
 	reply.sin_len = sizeof(reply);
@@ -298,8 +291,8 @@ valid_type(int type)
 static int
 set(int argc, char **argv)
 {
-	struct sockaddr_inarp *addr;
+	struct sockaddr_in *addr;
-	struct sockaddr_inarp *dst;	/* what are we looking for */
+	struct sockaddr_in *dst;	/* what are we looking for */
 	struct sockaddr_dl *sdl;
 	struct rt_msghdr *rtm;
 	struct ether_addr *ea;
@@ -316,7 +309,7 @@ set(int argc, char **argv)
 	dst = getaddr(host);
 	if (dst == NULL)
 		return (1);
-	doing_proxy = flags = proxy_only = expire_time = 0;
+	doing_proxy = flags = expire_time = 0;
 	while (argc-- > 0) {
 		if (strncmp(argv[0], "temp", 4) == 0) {
 			struct timespec tp;
@@ -332,7 +325,12 @@ set(int argc, char **argv)
 			flags |= RTF_ANNOUNCE;
 			doing_proxy = 1;
 			if (argc && strncmp(argv[1], "only", 3) == 0) {
-				proxy_only = 1;
+				/*
+				 * Compatibility: in pre FreeBSD 8 times
+				 * the "only" keyword used to mean that
+				 * an ARP entry should be announced, but
+				 * not installed into routing table.
+				 */
 				argc--; argv++;
 			}
 		} else if (strncmp(argv[0], "blackhole", 9) == 0) {
@@ -385,7 +383,7 @@ set(int argc, char **argv)
 		warn("%s", host);
 		return (1);
 	}
-	addr = (struct sockaddr_inarp *)(rtm + 1);
+	addr = (struct sockaddr_in *)(rtm + 1);
 	sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr);
 
 	if ((sdl->sdl_family != AF_LINK) ||
@@ -405,7 +403,7 @@ set(int argc, char **argv)
 static int
 get(char *host)
 {
-	struct sockaddr_inarp *addr;
+	struct sockaddr_in *addr;
 
 	addr = getaddr(host);
 	if (addr == NULL)
@@ -425,9 +423,9 @@ get(char *host)
  * Delete an arp entry
  */
 static int
-delete(char *host, int do_proxy)
+delete(char *host)
 {
-	struct sockaddr_inarp *addr, *dst;
+	struct sockaddr_in *addr, *dst;
 	struct rt_msghdr *rtm;
 	struct sockaddr_dl *sdl;
 	struct sockaddr_dl sdl_m;
@@ -456,7 +454,7 @@ delete(char *host, int do_proxy)
 			warn("%s", host);
 			return (1);
 		}
-		addr = (struct sockaddr_inarp *)(rtm + 1);
+		addr = (struct sockaddr_in *)(rtm + 1);
 		sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr);
 
 		/*
@@ -504,7 +502,7 @@ search(u_long addr, action_fn *action)
 	size_t needed;
 	char *lim, *buf, *next;
 	struct rt_msghdr *rtm;
-	struct sockaddr_inarp *sin2;
+	struct sockaddr_in *sin2;
 	struct sockaddr_dl *sdl;
 	char ifname[IF_NAMESIZE];
 	int st, found_entry = 0;
@@ -538,7 +536,7 @@ search(u_long addr, action_fn *action)
 	lim = buf + needed;
 	for (next = buf; next < lim; next += rtm->rtm_msglen) {
 		rtm = (struct rt_msghdr *)next;
-		sin2 = (struct sockaddr_inarp *)(rtm + 1);
+		sin2 = (struct sockaddr_in *)(rtm + 1);
 		sdl = (struct sockaddr_dl *)((char *)sin2 + SA_SIZE(sin2));
 		if (rifname && if_indextoname(sdl->sdl_index, ifname) &&
 		    strcmp(ifname, rifname))
@@ -562,7 +560,7 @@ static int64_t lifindex = -1;
 
 static void
 print_entry(struct sockaddr_dl *sdl,
-	struct sockaddr_inarp *addr, struct rt_msghdr *rtm)
+	struct sockaddr_in *addr, struct rt_msghdr *rtm)
 {
 	const char *host;
 	struct hostent *hp;
@@ -612,8 +610,6 @@ print_entry(struct sockaddr_dl *sdl,
 		else
 			printf(" expired");
 	}
-	if (addr->sin_other & SIN_PROXY)
-		printf(" published (proxy only)");
 	if (rtm->rtm_flags & RTF_ANNOUNCE)
 		printf(" published");
 	switch(sdl->sdl_type) {
@@ -659,12 +655,12 @@ print_entry(struct sockaddr_dl *sdl,
  */
 static void
 nuke_entry(struct sockaddr_dl *sdl __unused,
-	struct sockaddr_inarp *addr, struct rt_msghdr *rtm __unused)
+	struct sockaddr_in *addr, struct rt_msghdr *rtm __unused)
 {
 	char ip[20];
 
 	snprintf(ip, sizeof(ip), "%s", inet_ntoa(addr->sin_addr));
-	(void)delete(ip, 0);
+	delete(ip);
 }
 
 static void
@@ -682,7 +678,7 @@ usage(void)
 }
 
 static struct rt_msghdr *
-rtmsg(int cmd, struct sockaddr_inarp *dst, struct sockaddr_dl *sdl)
+rtmsg(int cmd, struct sockaddr_in *dst, struct sockaddr_dl *sdl)
 {
 	static int seq;
 	int rlen;
@@ -728,15 +724,10 @@ rtmsg(int cmd, struct sockaddr_inarp *dst, struct sockaddr_dl *sdl)
 		rtm->rtm_rmx.rmx_expire = expire_time;
 		rtm->rtm_inits = RTV_EXPIRE;
 		rtm->rtm_flags |= (RTF_HOST | RTF_STATIC | RTF_LLDATA);
-		dst->sin_other = 0;
 		if (doing_proxy) {
-			if (proxy_only)
-				dst->sin_other = SIN_PROXY;
-			else {
 			rtm->rtm_addrs |= RTA_NETMASK;
 			rtm->rtm_flags &= ~RTF_HOST;
 		}
-		}
 		/* FALLTHROUGH */
 	case RTM_GET:
 		rtm->rtm_addrs |= RTA_DST;

usr.sbin/ndp/ndp.c

@@ -436,9 +436,6 @@ set(argc, argv)
 				goto overwrite;
 			}
 		}
-		/*
-		 * IPv4 arp command retries with sin_other = SIN_PROXY here.
-		 */
 		fprintf(stderr, "set: cannot configure a new entry\n");
 		return 1;
 	}
@@ -523,9 +520,6 @@ delete(host)
 		    !(rtm->rtm_flags & RTF_GATEWAY)) {
 			goto delete;
 		}
-		/*
-		 * IPv4 arp command retries with sin_other = SIN_PROXY here.
-		 */
 		fprintf(stderr, "delete: cannot delete non-NDP entry\n");
 		return 1;
 	}

usr.sbin/ppp/arp.c

@@ -91,7 +91,7 @@
  */
 static struct {
   struct rt_msghdr hdr;
-  struct sockaddr_inarp dst;
+  struct sockaddr_in dst;
   struct sockaddr_dl hwa;
   char extra[128];
 } arpmsg;
@@ -124,10 +124,9 @@ arp_ProxySub(struct bundle *bundle, struct in_addr addr, int add)
   arpmsg.hdr.rtm_seq = ++bundle->routing_seq;
   arpmsg.hdr.rtm_addrs = RTA_DST | RTA_GATEWAY;
   arpmsg.hdr.rtm_inits = RTV_EXPIRE;
-  arpmsg.dst.sin_len = sizeof(struct sockaddr_inarp);
+  arpmsg.dst.sin_len = sizeof(struct sockaddr_in);
   arpmsg.dst.sin_family = AF_INET;
   arpmsg.dst.sin_addr.s_addr = addr.s_addr;
-  arpmsg.dst.sin_other = SIN_PROXY;
 
   arpmsg.hdr.rtm_msglen = (char *) &arpmsg.hwa - (char *) &arpmsg
     + arpmsg.hwa.sdl_len;

usr.sbin/rarpd/rarpd.c

@@ -692,11 +692,10 @@ rarp_process(struct if_info *ii, u_char *pkt, u_int len)
  * host (i.e. the guy running rarpd), won't try to ARP for the hardware
  * address of the guy being booted (he cannot answer the ARP).
  */
-struct sockaddr_inarp sin_inarp = {
+struct sockaddr_in sin_inarp = {
-	sizeof(struct sockaddr_inarp), AF_INET, 0,
+	sizeof(struct sockaddr_in), AF_INET, 0,
 	{0},
 	{0},
-	0, 0
 };
 struct sockaddr_dl sin_dl = {
 	sizeof(struct sockaddr_dl), AF_LINK, 0, IFT_ETHER, 0, 6,
@@ -712,7 +711,7 @@ update_arptab(u_char *ep, in_addr_t ipaddr)
 {
 	struct timespec tp;
 	int cc;
-	struct sockaddr_inarp *ar, *ar2;
+	struct sockaddr_in *ar, *ar2;
 	struct sockaddr_dl *ll, *ll2;
 	struct rt_msghdr *rt;
 	int xtype, xindex;
@@ -740,7 +739,7 @@ update_arptab(u_char *ep, in_addr_t ipaddr)
 	rt->rtm_addrs = RTA_DST;
 	rt->rtm_type = RTM_GET;
 	rt->rtm_seq = ++seq;
-	ar2 = (struct sockaddr_inarp *)rtmsg.rtspace;
+	ar2 = (struct sockaddr_in *)rtmsg.rtspace;
 	bcopy(ar, ar2, sizeof(*ar));
 	rt->rtm_msglen = sizeof(*rt) + sizeof(*ar);
 	errno = 0;