Send a source link-layer address option with our solicitations.

Servers following RFC 7772 may then send us unicast router
advertisments and thus reduce multicast traffic which might
increase the battery life of other devices using the same shared
media.

1 files changed, 17 insertions, 4 deletions

diff --git a/usr.sbin/slaacd/frontend.c b/usr.sbin/slaacd/frontend.c
index 03ebe29bc44..173c95635ce 100644
--- a/usr.sbin/slaacd/frontend.c
+++ b/usr.sbin/slaacd/frontend.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: frontend.c,v 1.14 2017/05/30 18:18:08 deraadt Exp $	*/
+/*	$OpenBSD: frontend.c,v 1.15 2017/05/30 19:27:16 florian Exp $	*/
 
 /*
  * Copyright (c) 2017 Florian Obser <florian@openbsd.org>
@@ -74,8 +74,10 @@ struct imsgev			*iev_main;
 struct imsgev			*iev_engine;
 struct event			 ev_route;
 struct msghdr			 sndmhdr;
-struct iovec			 sndiov[2];
+struct iovec			 sndiov[4];
 struct nd_router_solicit	 rs;
+struct nd_opt_hdr		 nd_opt_hdr;
+struct ether_addr		 nd_opt_source_link_addr;
 struct sockaddr_in6		 dst;
 int		 icmp6sock, routesock, xflagssock;
 
@@ -228,6 +230,9 @@ frontend(int debug, int verbose, char *sockname)
 	rs.nd_rs_cksum = 0;
 	rs.nd_rs_reserved = 0;
 
+	nd_opt_hdr.nd_opt_type = ND_OPT_SOURCE_LINKADDR;
+	nd_opt_hdr.nd_opt_len = 1;
+
 	memset(&dst, 0, sizeof(dst));
 	dst.sin6_family = AF_INET6;
 	if (inet_pton(AF_INET6, ALLROUTER, &dst.sin6_addr.s6_addr) != 1)
@@ -235,13 +240,17 @@ frontend(int debug, int verbose, char *sockname)
 
 	sndmhdr.msg_namelen = sizeof(struct sockaddr_in6);
 	sndmhdr.msg_iov = sndiov;
-	sndmhdr.msg_iovlen = 1;
+	sndmhdr.msg_iovlen = 3;
 	sndmhdr.msg_control = (caddr_t)sndcmsgbuf;
 	sndmhdr.msg_controllen = sndcmsglen;
 
 	sndmhdr.msg_name = (caddr_t)&dst;
 	sndmhdr.msg_iov[0].iov_base = (caddr_t)&rs;
 	sndmhdr.msg_iov[0].iov_len = sizeof(rs);
+	sndmhdr.msg_iov[1].iov_base = (caddr_t)&nd_opt_hdr;
+	sndmhdr.msg_iov[1].iov_len = sizeof(nd_opt_hdr);
+	sndmhdr.msg_iov[2].iov_base = (caddr_t)&nd_opt_source_link_addr;
+	sndmhdr.msg_iov[2].iov_len = sizeof(nd_opt_source_link_addr);
 
 	cm = CMSG_FIRSTHDR(&sndmhdr);
 
@@ -501,6 +510,9 @@ update_iface(uint32_t if_index, char* if_name)
 	imsg_ifinfo.autoconfprivacy = !(xflags & IFXF_INET6_NOPRIVACY);
 	get_lladdr(if_name, &imsg_ifinfo.hw_address, &imsg_ifinfo.ll_address);
 
+	memcpy(&nd_opt_source_link_addr, &imsg_ifinfo.hw_address,
+	    sizeof(nd_opt_source_link_addr));
+
 	frontend_imsg_compose_engine(IMSG_UPDATE_IF, 0, 0, &imsg_ifinfo,
 	    sizeof(imsg_ifinfo));
 }
@@ -820,6 +832,7 @@ send_solicitation(uint32_t if_index)
 	pi = (struct in6_pktinfo *)CMSG_DATA(cm);
 	pi->ipi6_ifindex = if_index;
 
-	if (sendmsg(icmp6sock, &sndmhdr, 0) != sizeof(rs))
+	if (sendmsg(icmp6sock, &sndmhdr, 0) != sizeof(rs) +
+	    sizeof(nd_opt_hdr) + sizeof(nd_opt_source_link_addr))
 		log_warn("sendmsg");
 }