Allow the same IP address to be leased for different interfaces.

The interface with the lowest metric gets the address.
When that interfaces loses the address, the next valid interface with the
lowest metric gets it.

1 files changed, 100 insertions, 25 deletions

diff --git a/ipv6.c b/ipv6.c
index daf30d71..6a8afcda 100644
--- a/ipv6.c
+++ b/ipv6.c
@@ -590,14 +590,55 @@ ipv6_checkaddrflags(void *arg)
 }
 #endif
 
+
+static void
+ipv6_deleteaddr(struct ipv6_addr *addr)
+{
+	struct ipv6_state *state;
+	struct ipv6_addr *ap;
+
+	syslog(LOG_INFO, "%s: deleting address %s",
+	    addr->iface->name, addr->saddr);
+	if (if_deladdress6(addr) == -1 &&
+	    errno != EADDRNOTAVAIL && errno != ENXIO)
+		syslog(LOG_ERR, "if_deladdress6: :%m");
+
+	state = IPV6_STATE(addr->iface);
+	TAILQ_FOREACH(ap, &state->addrs, next) {
+		if (IN6_ARE_ADDR_EQUAL(&ap->addr, &addr->addr)) {
+			TAILQ_REMOVE(&state->addrs, ap, next);
+			free(ap);
+			break;
+		}
+	}
+}
+
 int
 ipv6_addaddr(struct ipv6_addr *ap)
 {
+	struct interface *ifp;
+	struct ipv6_state *state;
+	struct ipv6_addr *nap;
+
+	/* Ensure no other interface has this address */
+	TAILQ_FOREACH(ifp, ap->iface->ctx->ifaces, next) {
+		if (ifp == ap->iface)
+			continue;
+		state = IPV6_STATE(ifp);
+		if (state == NULL)
+			continue;
+		TAILQ_FOREACH(nap, &state->addrs, next) {
+			if (IN6_ARE_ADDR_EQUAL(&nap->addr, &ap->addr)) {
+				ipv6_deleteaddr(nap);
+				break;
+			}
+		}
+	}
 
 	syslog(ap->flags & IPV6_AF_NEW ? LOG_INFO : LOG_DEBUG,
 	    "%s: adding address %s", ap->iface->name, ap->saddr);
 	if (!(ap->flags & IPV6_AF_DADCOMPLETED) &&
-	    ipv6_findaddr(ap->iface, &ap->addr))
+	    ipv6_iffindaddr(ap->iface, &ap->addr))
 		ap->flags |= IPV6_AF_DADCOMPLETED;
 	if (if_addaddress6(ap) == -1) {
 		syslog(LOG_ERR, "if_addaddress6: %m");
@@ -643,23 +684,36 @@ ipv6_addaddr(struct ipv6_addr *ap)
 	return 0;
 }
 
+struct ipv6_addr *
+ipv6_findaddr(struct dhcpcd_ctx *ctx, const struct in6_addr *addr, short flags)
+{
+	struct ipv6_addr *dap, *nap;
+
+	dap = dhcp6_findaddr(ctx, addr, flags);
+	nap = ipv6nd_findaddr(ctx, addr, flags);
+	if (!dap && !nap)
+		return NULL;
+	if (dap && !nap)
+		return dap;
+	if (nap && !dap)
+		return nap;
+	if (nap->iface->metric < dap->iface->metric)
+		return nap;
+	return dap;
+}
+
 ssize_t
 ipv6_addaddrs(struct ipv6_addrhead *addrs)
 {
-	struct ipv6_addr *ap, *apn;
+	struct ipv6_addr *ap, *apn, *apf;
 	ssize_t i;
 
 	i = 0;
 	TAILQ_FOREACH_SAFE(ap, addrs, next, apn) {
 		if (ap->prefix_vltime == 0) {
 			if (ap->flags & IPV6_AF_ADDED) {
-				syslog(LOG_INFO, "%s: deleting address %s",
-				    ap->iface->name, ap->saddr);
+				ipv6_deleteaddr(ap);
 				i++;
-				if (!IN6_IS_ADDR_UNSPECIFIED(&ap->addr) &&
-				    if_deladdress6(ap) == -1 &&
-				    errno != EADDRNOTAVAIL && errno != ENXIO)
-					syslog(LOG_ERR, "if_deladdress6: %m");
 			}
 			eloop_q_timeout_delete(ap->iface->ctx->eloop,
 			    0, NULL, ap);
@@ -670,6 +724,28 @@ ipv6_addaddrs(struct ipv6_addrhead *addrs)
 				free(ap);
 			}
 		} else if (!IN6_IS_ADDR_UNSPECIFIED(&ap->addr)) {
+			apf = ipv6_findaddr(ap->iface->ctx,
+			    &ap->addr, IPV6_AF_ADDED);
+			if (apf && apf->iface != ap->iface) {
+				if (apf->iface->metric <= ap->iface->metric) {
+					syslog(LOG_INFO,
+					    "%s: preferring %s on %s",
+					    ap->iface->name,
+					    ap->saddr,
+					    apf->iface->name);
+					continue;
+				}
+				syslog(LOG_INFO,
+				    "%s: preferring %s on %s",
+				    apf->iface->name,
+				    ap->saddr,
+				    ap->iface->name);
+				if (if_deladdress6(apf) == -1 &&
+				    errno != EADDRNOTAVAIL && errno != ENXIO)
+					syslog(LOG_ERR, "if_deladdress6: %m");
+				apf->flags &= ~IPV6_AF_ADDED;
+			} else if (apf)
+				apf->flags &= ~IPV6_AF_ADDED;
 			if (ap->flags & IPV6_AF_NEW)
 				i++;
 			ipv6_addaddr(ap);
@@ -679,33 +755,29 @@ ipv6_addaddrs(struct ipv6_addrhead *addrs)
 	return i;
 }
 
-
 void
 ipv6_freedrop_addrs(struct ipv6_addrhead *addrs, int drop,
     const struct interface *ifd)
 {
-	struct ipv6_addr *ap, *apn;
+	struct ipv6_addr *ap, *apn, *apf;
 
 	TAILQ_FOREACH_SAFE(ap, addrs, next, apn) {
 		if (ifd && ap->delegating_iface != ifd)
 			continue;
 		TAILQ_REMOVE(addrs, ap, next);
 		eloop_q_timeout_delete(ap->iface->ctx->eloop, 0, NULL, ap);
-		/* Only drop the address if no other RAs have assigned it.
-		 * This is safe because the RA is removed from the list
-		 * before we are called. */
 		if (drop && ap->flags & IPV6_AF_ADDED &&
-		    !ipv6nd_addrexists(ap->iface->ctx, ap) &&
-		    !dhcp6_addrexists(ap->iface->ctx, ap) &&
 		    (ap->iface->options->options &
 		    (DHCPCD_EXITING | DHCPCD_PERSISTENT)) !=
 		    (DHCPCD_EXITING | DHCPCD_PERSISTENT))
 		{
-			syslog(LOG_INFO, "%s: deleting address %s",
-			    ap->iface->name, ap->saddr);
-			if (if_deladdress6(ap) == -1 &&
-			    errno != EADDRNOTAVAIL && errno != ENXIO)
-				syslog(LOG_ERR, "if_deladdress6: :%m");
+			/* Find the same address somewhere else */
+			apf = ipv6_findaddr(ap->iface->ctx, &ap->addr, 0);
+			if (apf == NULL || apf->iface != ap->iface)
+				ipv6_deleteaddr(ap);
+			if (!(ap->iface->options->options &
+			    DHCPCD_EXITING) && apf)
+				ipv6_addaddr(apf);
 		}
 		free(ap);
 	}
@@ -784,6 +856,8 @@ ipv6_handleifa(struct dhcpcd_ctx *ctx,
 				ap = calloc(1, sizeof(*ap));
 				ap->iface = ifp;
 				ap->addr = *addr;
+				inet_ntop(AF_INET6, &addr->s6_addr,
+				    ap->saddr, sizeof(ap->saddr));
 				TAILQ_INSERT_TAIL(&state->addrs,
 				    ap, next);
 			}
@@ -822,7 +896,7 @@ ipv6_handleifa(struct dhcpcd_ctx *ctx,
 }
 
 const struct ipv6_addr *
-ipv6_findaddr(const struct interface *ifp, const struct in6_addr *addr)
+ipv6_iffindaddr(const struct interface *ifp, const struct in6_addr *addr)
 {
 	const struct ipv6_state *state;
 	const struct ipv6_addr *ap;
@@ -1066,10 +1140,11 @@ ipv6_handleifa_addrs(int cmd,
 		}
 		switch (cmd) {
 		case RTM_DELADDR:
-			syslog(LOG_INFO, "%s: deleted address %s",
-			    ap->iface->name, ap->saddr);
-			TAILQ_REMOVE(addrs, ap, next);
-			free(ap);
+			if (ap->flags & IPV6_AF_ADDED) {
+				syslog(LOG_INFO, "%s: deleted address %s",
+				    ap->iface->name, ap->saddr);
+				ap->flags &= ~IPV6_AF_ADDED;
+			}
 			break;
 		case RTM_NEWADDR:
 			/* Safety - ignore tentative announcements */