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.

diff --git a/usr.sbin/slaacd/frontend.c b/usr.sbin/slaacd/frontend.c
index 03ebe29..173c956 100644 (file)
--- 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");
 }