The proxy arp entries could not be added into the system over the

IFF_POINTOPOINT link types. The reason was due to the routing
entry returned from the kernel covering the remote end is of an
interface type that does not support ARP. This patch fixes this
problem by providing a hint to the kernel routing code, which
indicates the prefix route instead of the PPP host route should
be returned to the caller. Since a host route to the local end
point is also added into the routing table, and there could be
multiple such instantiations due to multiple PPP links can be
created with the same local end IP address, this patch also fixes
the loopback route installation failure problem observed prior to
this patch. The reference count of loopback route to local end would
be either incremented or decremented. The first instantiation would
create the entry and the last removal would delete the route entry.

MFC after:	5 days

1 files changed, 35 insertions, 29 deletions

diff --git a/usr.sbin/arp/arp.c b/usr.sbin/arp/arp.c
index 2982f48bec41..61427d34c81f 100644
--- a/usr.sbin/arp/arp.c
+++ b/usr.sbin/arp/arp.c
@@ -326,7 +326,6 @@ set(int argc, char **argv)
 			doing_proxy = 1;
 			if (argc && strncmp(argv[1], "only", 3) == 0) {
 				proxy_only = 1;
-				dst->sin_other = SIN_PROXY;
 				argc--; argv++;
 			}
 		} else if (strncmp(argv[0], "blackhole", 9) == 0) {
@@ -365,33 +364,30 @@ set(int argc, char **argv)
 			sdl_m.sdl_alen = ETHER_ADDR_LEN;
 		}
 	}
-	for (;;) {	/* try at most twice */
-		rtm = rtmsg(RTM_GET, dst, &sdl_m);
-		if (rtm == NULL) {
-			warn("%s", host);
-			return (1);
-		}
-		addr = (struct sockaddr_inarp *)(rtm + 1);
-		sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr);
-		if (addr->sin_addr.s_addr != dst->sin_addr.s_addr)	
-			break;
-		if (sdl->sdl_family == AF_LINK &&
-		    !(rtm->rtm_flags & RTF_GATEWAY) &&
-		    valid_type(sdl->sdl_type) )
-			break;
-		if (doing_proxy == 0) {
-			printf("set: can only proxy for %s\n", host);
-			return (1);
-		}
-		if (dst->sin_other & SIN_PROXY) {
-			printf("set: proxy entry exists for non 802 device\n");
-			return (1);
-		}
-		dst->sin_other = SIN_PROXY;
-		proxy_only = 1;
+
+	/*
+	 * In the case a proxy-arp entry is being added for
+	 * a remote end point, the RTF_ANNOUNCE flag in the 
+	 * RTM_GET command is an indication to the kernel
+	 * routing code that the interface associated with
+	 * the prefix route covering the local end of the
+	 * PPP link should be returned, on which ARP applies.
+	 */
+	rtm = rtmsg(RTM_GET, dst, &sdl_m);
+	if (rtm == NULL) {
+		warn("%s", host);
+		return (1);
+	}
+	addr = (struct sockaddr_inarp *)(rtm + 1);
+	sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr);
+	if (addr->sin_addr.s_addr == dst->sin_addr.s_addr) {
+		printf("set: proxy entry exists for non 802 device\n");
+		return (1);
 	}
 
-	if (sdl->sdl_family != AF_LINK) {
+	if ((sdl->sdl_family != AF_LINK) ||
+	    (rtm->rtm_flags & RTF_GATEWAY) ||
+	    !valid_type(sdl->sdl_type)) {
 		printf("cannot intuit interface index and type for %s\n", host);
 		return (1);
 	}
@@ -436,7 +432,11 @@ delete(char *host, int do_proxy)
 	dst = getaddr(host);
 	if (dst == NULL)
 		return (1);
-	dst->sin_other = do_proxy;
+
+	/*
+	 * Perform a regular entry delete first.
+	 */
+	flags &= ~RTF_ANNOUNCE;
 
 	/*
 	 * setup the data structure to notify the kernel
@@ -471,11 +471,16 @@ delete(char *host, int do_proxy)
 			break;
 		}
 
-		if (dst->sin_other & SIN_PROXY) {
+		/*
+		 * Regualar entry delete failed, now check if there
+		 * is a proxy-arp entry to remove.
+		 */
+		if (flags & RTF_ANNOUNCE) {
 			fprintf(stderr, "delete: cannot locate %s\n",host);
 			return (1);
 		}
-		dst->sin_other = SIN_PROXY;
+
+		flags |= RTF_ANNOUNCE;
 	}
 	rtm->rtm_flags |= RTF_LLDATA;
 	if (rtmsg(RTM_DELETE, dst, NULL) != NULL) {
@@ -485,6 +490,7 @@ delete(char *host, int do_proxy)
 	return (1);
 }
 
+
 /*
  * Search the arp table and do some action on matching entries
  */