[master] Fixed inconsistencies in setting hop count limit in dhcrelay

Merges in rt37426.

RELNOTES

@@ -246,6 +246,15 @@ by Eric Young (eay@cryptsoft.com).
   [ISC-Bugs #36780]
   [ISC-Bugs #32228]
 
+- Corrected inconsistencies in dhcrelay's setting the upper interface hop count
+  limit such that it now sets it to 32 when the upstream address is a multicast
+  address per RFC 3315 Section 20. Prior to this if the -u argument preceded
+  the -l argument on the command line or if the same interface was specified
+  for both; the logic to set the hop limit count for the upper interface was
+  skipped.  This caused the hop count limit to be set to the default value
+  (typically 1) in the outbound upstream packets.
+  [ISC-Bugs #37426]
+
 			Changes since 4.3.1b1
 
 - Modify the linux and openwrt dhclient scripts to process information

common/socket.c

@@ -3,7 +3,7 @@
    BSD socket interface code... */
 
 /*
- * Copyright (c) 2004-2014 by Internet Systems Consortium, Inc. ("ISC")
+ * Copyright (c) 2004-2015 by Internet Systems Consortium, Inc. ("ISC")
  * Copyright (c) 1995-2003 by Internet Software Consortium
  *
  * Permission to use, copy, modify, and distribute this software for any
@@ -300,18 +300,24 @@ if_register_socket(struct interface_info *info, int family,
 #endif
 	}
 
-	if ((family == AF_INET6) &&
-	    ((info->flags & INTERFACE_UPSTREAM) != 0)) {
-		int hop_limit = 32;
-		if (setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_HOPS,
-			       &hop_limit, sizeof(int)) < 0) {
-			log_fatal("setsockopt: IPV6_MULTICAST_HOPS: %m");
-		}
-	}
 #endif /* DHCPv6 */
 
 	return sock;
 }
+
+#ifdef DHCPv6
+void set_multicast_hop_limit(struct interface_info* info, int hop_limit) {
+	if (setsockopt(info->wfdesc, IPPROTO_IPV6, IPV6_MULTICAST_HOPS,
+		       &hop_limit, sizeof(int)) < 0) {
+		log_fatal("setMulticaseHopLimit: IPV6_MULTICAST_HOPS: %m");
+	}
+
+	log_debug("Setting hop count limit to %d for interface %s",
+		  hop_limit, info->name);
+
+}
+#endif /* DHCPv6 */
+
 #endif /* USE_SOCKET_SEND || USE_SOCKET_RECEIVE || USE_SOCKET_FALLBACK */
 
 #if defined (USE_SOCKET_SEND) || defined (USE_SOCKET_FALLBACK)

includes/dhcpd.h

@@ -2477,6 +2477,8 @@ void get_hw_addr(const char *name, struct hardware *hw);
 #if defined (USE_SOCKET_SEND) || defined (USE_SOCKET_RECEIVE) \
 	|| defined (USE_SOCKET_FALLBACK)
 int if_register_socket(struct interface_info *, int, int *, struct in6_addr *);
+
+void set_multicast_hop_limit(struct interface_info* info, int hop_limit);
 #endif
 
 #if defined (USE_SOCKET_FALLBACK) && !defined (USE_SOCKET_SEND)

relay/dhcrelay.c

@@ -1192,8 +1192,8 @@ parse_downstream(char *arg) {
 	/* Share with up side? */
 	for (up = upstreams; up; up = up->next) {
 		if (strcmp(ifname, up->ifp->name) == 0) {
-			log_info("Interface '%s' is both down and up.",
+			log_info("parse_downstream: Interface '%s' is "
-				 ifname);
+				 "both down and up.", ifname);
 			ifp = up->ifp;
 			break;
 		}
@@ -1211,8 +1211,8 @@ parse_downstream(char *arg) {
 			interface_dereference(&interfaces, MDL);
 		}
 		interface_reference(&interfaces, ifp, MDL);
-		ifp->flags |= INTERFACE_REQUESTED | INTERFACE_DOWNSTREAM;
 	}
+	ifp->flags |= INTERFACE_REQUESTED | INTERFACE_DOWNSTREAM;
 
 	/* New downstream. */
 	dp = (struct stream_list *) dmalloc(sizeof(*dp), MDL);
@@ -1263,6 +1263,8 @@ parse_upstream(char *arg) {
 	}
 	for (dp = downstreams; dp; dp = dp->next) {
 		if (strcmp(ifname, dp->ifp->name) == 0) {
+			log_info("parse_upstream: Interface '%s' is "
+				 "both down and up.", ifname);
 			ifp = dp->ifp;
 			break;
 		}
@@ -1280,8 +1282,8 @@ parse_upstream(char *arg) {
 			interface_dereference(&interfaces, MDL);
 		}
 		interface_reference(&interfaces, ifp, MDL);
-		ifp->flags |= INTERFACE_REQUESTED | INTERFACE_UPSTREAM;
 	}
+	ifp->flags |= INTERFACE_REQUESTED | INTERFACE_UPSTREAM;
 
 	/* New upstream. */
 	up = (struct stream_list *) dmalloc(sizeof(*up), MDL);
@@ -1349,6 +1351,13 @@ setup_streams(void) {
 		if (up->ifp->v6address_count == 0)
 			log_fatal("Interface '%s' has no IPv6 addresses.",
 				  up->ifp->name);
+
+		/* RFC 3315 Sec 20 - "If the relay agent relays messages to
+		 * the All_DHCP_Servers address or other multicast addresses,
+		 * it sets the Hop Limit field to 32." */
+		if (IN6_IS_ADDR_MULTICAST(&up->link.sin6_addr)) {
+			set_multicast_hop_limit(up->ifp, HOP_COUNT_LIMIT);
+		}
 	}
 }