DHCPv6: listen on all IPv6 addresses for active interface

Simplify the process of selecting addresses to listen for DHCPv6
replies on by listening on all addresses for active interfaces
when not in master mode.

Always send from a socket not bound to an address to ensure
unicast in non master mode works fine. The downside of this approach
is that we no longer send from the DHCPv6 client port, but this
seems to work fine, at least with ISC DHCPd.

3 files changed, 30 insertions, 84 deletions

diff --git a/src/dhcp6.c b/src/dhcp6.c
index 7505ce0c..206d2fa3 100644
--- a/src/dhcp6.c
+++ b/src/dhcp6.c
@@ -1358,11 +1358,6 @@ dhcp6_dadcallback(void *arg)
 	if (!wascompleted) {
 		ifp = ia->iface;
 
-		/* If not in master mode, we need to listen on each address
-		 * so we can receive unicast a message. */
-		if (ia->dhcp6_fd == -1 && !(ifp->ctx->options & DHCPCD_MASTER))
-			dhcp6_listen(ifp->ctx, ia);
-
 		state = D6_STATE(ifp);
 		if (state->state == DH6S_BOUND ||
 		    state->state == DH6S_DELEGATED)
@@ -1711,35 +1706,6 @@ dhcp6_leaseextend(struct interface *ifp)
 }
 
 static void
-dhcp6_addaddrs(struct interface *ifp)
-{
-	struct dhcp6_state *state = D6_STATE(ifp);
-	struct ipv6_addr *ia;
-
-	ipv6_addaddrs(&state->addrs);
-
-	/* If not in master mode, we need to listen on each address
-	 * so we can receive unicast a message. */
-	if (ifp->ctx->options & DHCPCD_MASTER)
-		return;
-
-	state = D6_STATE(ifp);
-	TAILQ_FOREACH(ia, &state->addrs, next) {
-		if (ia->prefix_vltime == 0 ||
-		    ia->flags & IPV6_AF_STALE ||
-		    ia->addr_flags & IN6_IFF_NOTUSEABLE)
-			continue;
-		if (ia->dhcp6_fd != -1)
-			continue;
-		ia->dhcp6_fd = dhcp6_listen(ifp->ctx, ia);
-		if (ia->dhcp6_fd == -1)
-			continue;
-		eloop_event_add(ifp->ctx->eloop,
-		    ia->dhcp6_fd, dhcp6_recvaddr, ia);
-	}
-}
-
-static void
 dhcp6_startexpire(void *arg)
 {
 	struct interface *ifp;
@@ -2736,7 +2702,10 @@ dhcp6_delegate_prefix(struct interface *ifp)
 				break;
 		}
 		if (k && !carrier_warned) {
-			dhcp6_addaddrs(ifd);
+			struct dhcp6_state *s = D6_STATE(ifd);
+
+			ipv6_addaddrs(&s->addrs);
+
 			/*
 			 * Can't add routes here because that will trigger
 			 * interface sorting which may break the current
@@ -3040,7 +3009,7 @@ dhcp6_bind(struct interface *ifp, const char *op)
 			eloop_timeout_add_sec(ifp->ctx->eloop,
 			    (time_t)state->expire, dhcp6_startdiscover, ifp);
 
-		dhcp6_addaddrs(ifp);
+		ipv6_addaddrs(&state->addrs);
 		dhcp6_deprecateaddrs(&state->addrs);
 
 		if (state->state == DH6S_INFORMED)
@@ -3481,10 +3450,13 @@ dhcp6_listen(struct dhcpcd_ctx *ctx, struct ipv6_addr *ia)
 #ifdef BSD
 	sa.sin6_len = sizeof(sa);
 #endif
+
 	if (ia != NULL) {
 		memcpy(&sa.sin6_addr, &ia->addr, sizeof(sa.sin6_addr));
 		sa.sin6_scope_id = ia->iface->index;
-	}
+	} else if (!(ctx->options & DHCPCD_MASTER))
+		/* This socket is only used for sending. */
+		return s;
 
 	if (bind(s, (struct sockaddr *)&sa, sizeof(sa)) == -1)
 		goto errexit;
@@ -3494,12 +3466,11 @@ dhcp6_listen(struct dhcpcd_ctx *ctx, struct ipv6_addr *ia)
 		if (setsockopt(s, IPPROTO_IPV6, IPV6_RECVPKTINFO,
 		    &n, sizeof(n)) == -1)
 			goto errexit;
-	}
-
-	if (ia != NULL) {
+	} else {
 		ia->dhcp6_fd = s;
 		eloop_event_add(ctx->eloop, s, dhcp6_recvaddr, ia);
 	}
+
 	return s;
 
 errexit:
@@ -3512,28 +3483,13 @@ errexit:
 static int
 dhcp6_open(struct dhcpcd_ctx *ctx)
 {
-	struct ipv6_addr *ia = NULL;
-	int s;
 
-	if (!(ctx->options & DHCPCD_MASTER)) {
-		/* Bind to the link-local address to allow more than one
-		 * DHCPv6 client to work. */
-		struct interface *ifp;
+	/* Open an unbound socket to send from. */
+	ctx->dhcp6_fd = dhcp6_listen(ctx, NULL);
+	if (ctx->dhcp6_fd != -1 && (ctx->options & DHCPCD_MASTER))
+		eloop_event_add(ctx->eloop, ctx->dhcp6_fd, dhcp6_recvctx, ctx);
 
-		TAILQ_FOREACH(ifp, ctx->ifaces, next) {
-			if (!ifp->active)
-				continue;
-			ia = ipv6_linklocal(ifp);
-			if (ia != NULL)
-				break;
-		}
-	}
-	s = dhcp6_listen(ctx, ia);
-	ctx->dhcp6_fd = s;
-	if (s != -1 && ia == NULL)
-		eloop_event_add(ctx->eloop, s, dhcp6_recvctx, ctx);
-
-	return s;
+	return ctx->dhcp6_fd;
 }
 
 #ifndef SMALL
@@ -3809,6 +3765,14 @@ dhcp6_handleifa(int cmd, struct ipv6_addr *ia)
 {
 	struct dhcp6_state *state;
 
+	/* If not running in master mode, listen to this address */
+	if (cmd == RTM_NEWADDR &&
+	    !(ia->addr_flags & IN6_IFF_NOTUSEABLE) &&
+	    ia->iface->active == IF_ACTIVE_USER &&
+	    !(ia->iface->ctx->options & DHCPCD_MASTER) &&
+	    ia->dhcp6_fd == -1)
+		dhcp6_listen(ia->iface->ctx, ia);
+
 	if ((state = D6_STATE(ia->iface)) != NULL)
 		ipv6_handleifa_addrs(cmd, &state->addrs, ia);
 }
diff --git a/src/ipv6.c b/src/ipv6.c
index c98a8f34..b05f1d67 100644
--- a/src/ipv6.c
+++ b/src/ipv6.c
@@ -1103,26 +1103,10 @@ ipv6_handleifa(struct dhcpcd_ctx *ctx,
 		break;
 	case RTM_NEWADDR:
 		if (ia == NULL) {
-			char buf[INET6_ADDRSTRLEN];
-			const char *cbp;
-
-			if ((ia = calloc(1, sizeof(*ia))) == NULL) {
-				logerr(__func__);
-				break;
-			}
+			ia = ipv6_newaddr(ifp, addr, prefix_len, 0);
 #ifdef ALIAS_ADDR
 			strlcpy(ia->alias, ifname, sizeof(ia->alias));
 #endif
-			ia->iface = ifp;
-			ia->addr = *addr;
-			ia->prefix_len = prefix_len;
-			ipv6_makeprefix(&ia->prefix, &ia->addr,
-			    ia->prefix_len);
-			cbp = inet_ntop(AF_INET6, &addr->s6_addr,
-			    buf, sizeof(buf));
-			if (cbp)
-				snprintf(ia->saddr, sizeof(ia->saddr),
-				    "%s/%d", cbp, prefix_len);
 			if (if_getlifetime6(ia) == -1) {
 				/* No support or address vanished.
 				 * Either way, just set a deprecated
@@ -1190,10 +1174,8 @@ ipv6_handleifa(struct dhcpcd_ctx *ctx,
 	}
 
 	if (ia != NULL) {
-		if (!IN6_IS_ADDR_LINKLOCAL(&ia->addr)) {
-			ipv6nd_handleifa(cmd, ia);
-			dhcp6_handleifa(cmd, ia);
-		}
+		ipv6nd_handleifa(cmd, ia);
+		dhcp6_handleifa(cmd, ia);
 
 		/* Done with the ia now, so free it. */
 		if (cmd == RTM_DELADDR)
@@ -1453,8 +1435,8 @@ ipv6_tryaddlinklocal(struct interface *ifp)
 }
 
 struct ipv6_addr *
-ipv6_newaddr(struct interface *ifp, struct in6_addr *addr, uint8_t prefix_len,
-    unsigned int flags)
+ipv6_newaddr(struct interface *ifp, const struct in6_addr *addr,
+    uint8_t prefix_len, unsigned int flags)
 {
 	struct ipv6_addr *ia;
 	char buf[INET6_ADDRSTRLEN];
diff --git a/src/ipv6.h b/src/ipv6.h
index 8fca8a71..156691b5 100644
--- a/src/ipv6.h
+++ b/src/ipv6.h
@@ -250,7 +250,7 @@ struct ipv6_addr *ipv6_findmaskaddr(struct dhcpcd_ctx *,
     const struct in6_addr *);
 #define ipv6_linklocal(ifp) ipv6_iffindaddr((ifp), NULL, IN6_IFF_NOTUSEABLE)
 int ipv6_addlinklocalcallback(struct interface *, void (*)(void *), void *);
-struct ipv6_addr *ipv6_newaddr(struct interface *, struct in6_addr *, uint8_t,
+struct ipv6_addr *ipv6_newaddr(struct interface *, const struct in6_addr *, uint8_t,
     unsigned int);
 void ipv6_freeaddr(struct ipv6_addr *);
 void ipv6_freedrop(struct interface *, int);