From a20837a7327f617f02374787c41f6dd0c116fb1c Mon Sep 17 00:00:00 2001
From: florian <florian@openbsd.org>
Date: Fri, 9 Jun 2017 13:31:03 +0000
Subject: [PATCH] If we receive a router solicitation with a source link-layer
 address option respond with a unicast advertisement. This improves air time
 on wireless networks and reduces energy consumption on battery powered
 devices. For details see RFC 7772 "Reducing Energy Consumption of Router
 Advertisements" aka BCP 202. Input & OK bluhm@

---
 usr.sbin/rtadvd/rtadvd.c | 42 +++++++++++++++++++++++-----------------
 1 file changed, 24 insertions(+), 18 deletions(-)

diff --git a/usr.sbin/rtadvd/rtadvd.c b/usr.sbin/rtadvd/rtadvd.c
index 1f470a06c31..71419bcf5b9 100644
--- a/usr.sbin/rtadvd/rtadvd.c
+++ b/usr.sbin/rtadvd/rtadvd.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: rtadvd.c,v 1.85 2017/04/05 14:50:05 jca Exp $	*/
+/*	$OpenBSD: rtadvd.c,v 1.86 2017/06/09 13:31:03 florian Exp $	*/
 /*	$KAME: rtadvd.c,v 1.66 2002/05/29 14:18:36 itojun Exp $	*/
 
 /*
@@ -141,7 +141,7 @@ static int prefix_check(struct nd_opt_prefix_info *, struct rainfo *,
 static int nd6_options(struct nd_opt_hdr *, int,
     union nd_opts *, u_int32_t);
 static void free_ndopts(union nd_opts *);
-static void ra_output(struct rainfo *);
+static void ra_output(struct rainfo *, struct sockaddr_in6 *);
 static struct rainfo *if_indextorainfo(int);
 static int rdaemon(int);
 
@@ -293,7 +293,7 @@ die_cb(int sig, short event, void *arg)
 	}
 	for (i = 0; i < retrans; i++) {
 		SLIST_FOREACH(ra, &ralist, entry)
-			ra_output(ra);
+			ra_output(ra, &sin6_allnodes);
 		sleep(MIN_DELAY_BETWEEN_RAS);
 	}
 	exit(0);
@@ -651,11 +651,13 @@ rs_input(int len, struct nd_router_solicit *rs,
 
 	ra->rsinput++;		/* increment statistics */
 
-	/*
-	 * Decide whether to send RA according to the rate-limit
-	 * consideration.
-	 */
-	{
+	if (ndopts.nd_opts_src_lladdr)
+		ra_output(ra, from);
+	else {
+		/*
+		 * Decide whether to send RA according to the rate-limit
+		 * consideration.
+		 */
 		long delay;	/* must not be greater than 1000000 */
 		struct timeval interval, now, min_delay, tm_tmp, next,
 		    computed;
@@ -1038,6 +1040,8 @@ nd6_options(struct nd_opt_hdr *hdr, int limit,
 
 		switch (hdr->nd_opt_type) {
 		case ND_OPT_SOURCE_LINKADDR:
+			ndopts->nd_opt_array[hdr->nd_opt_type] = hdr;
+			break;
 		case ND_OPT_TARGET_LINKADDR:
 		case ND_OPT_REDIRECTED_HEADER:
 		case ND_OPT_ROUTE_INFO:
@@ -1212,7 +1216,7 @@ if_indextorainfo(int index)
 }
 
 static void
-ra_output(struct rainfo *rainfo)
+ra_output(struct rainfo *rainfo, struct sockaddr_in6 *to)
 {
 	struct cmsghdr *cm;
 	struct in6_pktinfo *pi;
@@ -1225,7 +1229,7 @@ ra_output(struct rainfo *rainfo)
 
 	make_packet(rainfo);	/* XXX: inefficient */
 
-	sndmhdr.msg_name = &sin6_allnodes;
+	sndmhdr.msg_name = to;
 	sndmhdr.msg_iov[0].iov_base = rainfo->ra_data;
 	sndmhdr.msg_iov[0].iov_len = rainfo->ra_datalen;
 
@@ -1258,16 +1262,18 @@ ra_output(struct rainfo *rainfo)
 		return;
 	}
 
-	/* update counter */
-	if (rainfo->initcounter < MAX_INITIAL_RTR_ADVERTISEMENTS)
-		rainfo->initcounter++;
 	rainfo->raoutput++;
 
-	/* update timestamp */
-	gettimeofday(&rainfo->lastsent, NULL);
+	if (memcmp(to, &sin6_allnodes, sizeof(sin6_allnodes)) == 0) {
+		/* update counter */
+		if (rainfo->initcounter < MAX_INITIAL_RTR_ADVERTISEMENTS)
+			rainfo->initcounter++;
+		/* update timestamp */
+		gettimeofday(&rainfo->lastsent, NULL);
 
-	/* reset waiting counter */
-	rainfo->waiting = 0;
+		/* reset waiting counter */
+		rainfo->waiting = 0;
+	}
 }
 
 /* process RA timer */
@@ -1278,7 +1284,7 @@ timer_cb(int fd, short event, void *data)
 
 	log_debug("RA timer on %s is expired", rai->ifname);
 
-	ra_output(rai);
+	ra_output(rai, &sin6_allnodes);
 
 	ra_timer_update(rai);
 	evtimer_add(&rai->timer.ev, &rai->timer.tm);
-- 
2.20.1