router: unicast RAs to RS senders by default

1 files changed, 44 insertions, 36 deletions

diff --git a/src/router.c b/src/router.c
index a45a8cb..77972ab 100644
--- a/src/router.c
+++ b/src/router.c
@@ -31,7 +31,7 @@ static void forward_router_advertisement(uint8_t *data, size_t len);
 
 static void handle_icmpv6(void *addr, void *data, size_t len,
 		struct interface *iface, void *dest);
-static void send_router_advert(struct uloop_timeout *event);
+static void trigger_router_advert(struct uloop_timeout *event);
 static void sigusr1_refresh(int signal);
 
 static struct odhcpd_event router_event = {{.fd = -1}, handle_icmpv6};
@@ -104,7 +104,7 @@ int setup_router_interface(struct interface *iface, bool enable)
 
 	if (!enable) {
 		if (iface->ra)
-			send_router_advert(&iface->timer_rs);
+			trigger_router_advert(&iface->timer_rs);
 	} else {
 		void *mreq = &all_routers;
 
@@ -112,8 +112,8 @@ int setup_router_interface(struct interface *iface, bool enable)
 			mreq = &all_nodes;
 			forward_router_solicitation(iface);
 		} else if (iface->ra == RELAYD_SERVER && !iface->master) {
-			iface->timer_rs.cb = send_router_advert;
-			send_router_advert(&iface->timer_rs);
+			iface->timer_rs.cb = trigger_router_advert;
+			trigger_router_advert(&iface->timer_rs);
 		}
 
 		if (iface->ra == RELAYD_RELAY || (iface->ra == RELAYD_SERVER && !iface->master))
@@ -168,26 +168,6 @@ static bool router_icmpv6_valid(struct sockaddr_in6 *source, uint8_t *data, size
 	return opt == end;
 }
 
-// Event handler for incoming ICMPv6 packets
-static void handle_icmpv6(void *addr, void *data, size_t len,
-		struct interface *iface, _unused void *dest)
-{
-	struct icmp6_hdr *hdr = data;
-
-	if (!router_icmpv6_valid(addr, data, len))
-		return;
-
-	if ((iface->ra == RELAYD_SERVER && !iface->master)) { // Server mode
-		if (hdr->icmp6_type == ND_ROUTER_SOLICIT)
-			send_router_advert(&iface->timer_rs);
-	} else if (iface->ra == RELAYD_RELAY) { // Relay mode
-		if (hdr->icmp6_type == ND_ROUTER_ADVERT && iface->master)
-			forward_router_advertisement(data, len);
-		else if (hdr->icmp6_type == ND_ROUTER_SOLICIT && !iface->master)
-			forward_router_solicitation(odhcpd_get_master_interface());
-	}
-}
-
 
 // Detect whether a default route exists, also find the source prefixes
 static bool parse_routes(struct odhcpd_ipaddr *n, ssize_t len)
@@ -227,11 +207,8 @@ static bool parse_routes(struct odhcpd_ipaddr *n, ssize_t len)
 
 
 // Router Advert server mode
-static void send_router_advert(struct uloop_timeout *event)
+static uint64_t send_router_advert(struct interface *iface, const struct in6_addr *from)
 {
-	struct interface *iface =
-			container_of(event, struct interface, timer_rs);
-
 	int mtu = odhcpd_get_interface_mtu(iface->ifname);
 	if (mtu < 0)
 		mtu = 1500;
@@ -265,7 +242,7 @@ static void send_router_advert(struct uloop_timeout *event)
 	uint64_t maxpreferred = 0;
 
 	// If not shutdown
-	if (event->cb) {
+	if (iface->timer_rs.cb) {
 		ipcnt = odhcpd_get_interface_addresses(iface->ifindex,
 				addrs, ARRAY_SIZE(addrs));
 
@@ -385,10 +362,6 @@ static void send_router_advert(struct uloop_timeout *event)
 		uint8_t name[];
 	} *search = alloca(sizeof(*search) + search_padded);
 
-	if (!search) {
-		syslog(LOG_ERR, "Alloca failed for dns search on interface %s", iface->ifname);
-		return;
-	}
 	search->type = ND_OPT_DNS_SEARCH;
 	search->len = search_len ? ((sizeof(*search) + search_padded) / 8) : 0;
 	search->pad = 0;
@@ -443,9 +416,22 @@ static void send_router_advert(struct uloop_timeout *event)
 			{&dns, (dns_cnt) ? sizeof(dns) : 0},
 			{dns_addr, dns_cnt * sizeof(*dns_addr)},
 			{search, search->len * 8}};
-	struct sockaddr_in6 all_nodes = {AF_INET6, 0, 0, ALL_IPV6_NODES, 0};
+	struct sockaddr_in6 dest = {AF_INET6, 0, 0, ALL_IPV6_NODES, 0};
+
+	if (from && !IN6_IS_ADDR_UNSPECIFIED(from))
+		dest.sin6_addr = *from;
+
 	odhcpd_send(router_event.uloop.fd,
-			&all_nodes, iov, ARRAY_SIZE(iov), iface);
+			&dest, iov, ARRAY_SIZE(iov), iface);
+
+	return maxpreferred;
+}
+
+
+static void trigger_router_advert(struct uloop_timeout *event)
+{
+	struct interface *iface = container_of(event, struct interface, timer_rs);
+	uint64_t maxpreferred = send_router_advert(iface, NULL);
 
 	// Rearm timer if not shut down
 	if (event->cb) {
@@ -466,7 +452,29 @@ static void send_router_advert(struct uloop_timeout *event)
 		int msecs;
 		odhcpd_urandom(&msecs, sizeof(msecs));
 		msecs = (labs(msecs) % (maxinterval - mininterval)) + mininterval;
-		uloop_timeout_set(&iface->timer_rs, msecs);
+		uloop_timeout_set(event, msecs);
+	}
+}
+
+
+// Event handler for incoming ICMPv6 packets
+static void handle_icmpv6(void *addr, void *data, size_t len,
+		struct interface *iface, _unused void *dest)
+{
+	struct icmp6_hdr *hdr = data;
+	struct sockaddr_in6 *from = addr;
+
+	if (!router_icmpv6_valid(addr, data, len))
+		return;
+
+	if ((iface->ra == RELAYD_SERVER && !iface->master)) { // Server mode
+		if (hdr->icmp6_type == ND_ROUTER_SOLICIT)
+			send_router_advert(iface, &from->sin6_addr);
+	} else if (iface->ra == RELAYD_RELAY) { // Relay mode
+		if (hdr->icmp6_type == ND_ROUTER_ADVERT && iface->master)
+			forward_router_advertisement(data, len);
+		else if (hdr->icmp6_type == ND_ROUTER_SOLICIT && !iface->master)
+			forward_router_solicitation(odhcpd_get_master_interface());
 	}
 }