Rewrite IPv6 prefix assignment

8 files changed, 215 insertions, 165 deletions

diff --git a/config.c b/config.c
index 556daf8..3b44bce 100644
--- a/config.c
+++ b/config.c
@@ -474,5 +474,6 @@ config_init_all(void)
 	device_init_pending();
 	vlist_flush(&interfaces);
 	device_free_unused(NULL);
+	interface_refresh_assignments(false);
 	interface_start_pending();
 }
diff --git a/interface-ip.c b/interface-ip.c
index 21c603d..ed95b2e 100644
--- a/interface-ip.c
+++ b/interface-ip.c
@@ -449,10 +449,10 @@ interface_update_host_route(struct vlist_tree *tree,
 
 
 static void
-interface_set_prefix_address(struct interface *iface, bool add,
-		struct device_prefix_assignment *assignment)
+interface_set_prefix_address(struct device_prefix_assignment *assignment,
+		const struct device_prefix *prefix, struct interface *iface, bool add)
 {
-	struct interface *uplink = assignment->prefix->iface;
+	const struct interface *uplink = prefix->iface;
 	if (!iface->l3_dev.dev)
 		return;
 
@@ -460,113 +460,146 @@ interface_set_prefix_address(struct interface *iface, bool add,
 
 	struct device_addr addr;
 	memset(&addr, 0, sizeof(addr));
-	addr.addr.in6 = assignment->addr;
+	addr.addr.in6 = prefix->addr;
+	addr.addr.in6.s6_addr32[1] |= htonl(assignment->assigned);
+	addr.addr.in6.s6_addr[15] += 1;
 	addr.mask = assignment->length;
 	addr.flags = DEVADDR_INET6;
-	addr.preferred_until = assignment->prefix->preferred_until;
-	addr.valid_until = assignment->prefix->valid_until;
-
-	if (!add) {
-		if (assignment->enabled) {
-			time_t now = system_get_rtime();
-			addr.preferred_until = now;
-			if (!addr.valid_until || addr.valid_until - now > 7200)
-				addr.valid_until = now + 7200;
-			system_add_address(l3_downlink, &addr);
-		}
-	} else {
+	addr.preferred_until = prefix->preferred_until;
+	addr.valid_until = prefix->valid_until;
+
+	if (!add && assignment->enabled) {
+		time_t now = system_get_rtime();
+		addr.preferred_until = now;
+		if (!addr.valid_until || addr.valid_until - now > 7200)
+			addr.valid_until = now + 7200;
+		system_add_address(l3_downlink, &addr);
+		assignment->enabled = false;
+	} else if (add && (iface->state == IFS_UP || iface->state == IFS_SETUP)) {
 		system_add_address(l3_downlink, &addr);
-
 		if (uplink && uplink->l3_dev.dev) {
 			int mtu = system_update_ipv6_mtu(
 					uplink->l3_dev.dev, 0);
 			if (mtu > 0)
 				system_update_ipv6_mtu(l3_downlink, mtu);
 		}
+		assignment->enabled = true;
+	}
+}
+
+static bool interface_prefix_assign(struct list_head *list,
+		struct device_prefix_assignment *assign)
+{
+	int32_t current = 0, asize = (1 << (64 - assign->length)) - 1;
+	struct device_prefix_assignment *c;
+	list_for_each_entry(c, list, head) {
+		if (assign->assigned != -1) {
+			if (assign->assigned > current && assign->assigned + asize < c->assigned) {
+				list_add_tail(&assign->head, &c->head);
+				return true;
+			}
+		} else if (assign->assigned == -1) {
+			current = (current + asize) & (~asize);
+			if (current + asize < c->assigned) {
+				assign->assigned = current;
+				list_add_tail(&assign->head, &c->head);
+				return true;
+			}
+		}
+		current = (c->assigned + (1 << (64 - c->length)));
 	}
-	assignment->enabled = add;
+	return false;
 }
 
-
-static void
-interface_update_prefix_assignments(struct vlist_tree *tree,
-			     struct vlist_node *node_new,
-			     struct vlist_node *node_old)
+static void interface_update_prefix_assignments(struct device_prefix *prefix, bool setup)
 {
-	struct device_prefix_assignment *old, *new;
-	old = container_of(node_old, struct device_prefix_assignment, node);
-	new = container_of(node_new, struct device_prefix_assignment, node);
-
-	// Assignments persist across interface reloads etc.
-	// so use indirection to avoid dangling pointers
-	struct interface *iface = vlist_find(&interfaces,
-			(node_new) ? new->name : old->name, iface, node);
-
-	if (node_old && node_new) {
-		new->addr = old->addr;
-		new->length = old->length;
-	} else if (node_old) {
-		if (iface)
-			interface_set_prefix_address(iface, false, old);
-		free(old);
-	} else if (node_new) {
-		struct device_prefix *prefix = new->prefix;
-		uint64_t want = 1ULL << (64 - new->length);
-		prefix->avail &= ~(want - 1);
-		prefix->avail -= want;
-
-		// Invert assignment
-		uint64_t assigned = ~prefix->avail;
-		assigned &= (1ULL << (64 - prefix->length)) - 1;
-		assigned &= ~(want - 1);
+	struct device_prefix_assignment *c;
+	struct interface *iface;
 
-		// Assignment
-		new->addr = prefix->addr;
-		new->addr.s6_addr32[0] |=
-				htonl(assigned >> 32);
-		new->addr.s6_addr32[1] |=
-				htonl(assigned & 0xffffffffU);
-		new->addr.s6_addr[15] += 1;
+	// Delete all assignments
+	while (!list_empty(&prefix->assignments)) {
+		c = list_first_entry(&prefix->assignments,
+				struct device_prefix_assignment, head);
+		if ((iface = vlist_find(&interfaces, c->name, iface, node)))
+			interface_set_prefix_address(c, prefix, iface, false);
+		list_del(&c->head);
+		free(c);
 	}
 
-	if (node_new && (iface->state == IFS_UP || iface->state == IFS_SETUP))
-		interface_set_prefix_address(iface, true, new);
-}
-
+	if (!setup)
+		return;
 
-void
-interface_ip_set_prefix_assignment(struct device_prefix *prefix,
-		struct interface *iface, uint8_t length)
-{
-	struct device_prefix_assignment *assignment;
+	// End-of-assignment sentinel
+	c = malloc(sizeof(*c) + 1);
+	c->assigned = 1 << (64 - prefix->length);
+	c->length = 64;
+	c->name[0] = 0;
+	list_add(&c->head, &prefix->assignments);
+
+	// Excluded prefix
+	if (prefix->excl_length > 0) {
+		const char name[] = "!excluded";
+		c = malloc(sizeof(*c) + sizeof(name));
+		c->assigned = ntohl(prefix->excl_addr.s6_addr32[1]) &
+				((1 << (64 - prefix->length)) - 1);
+		c->length = prefix->excl_length;
+		memcpy(c->name, name, sizeof(name));
+		list_add(&c->head, &prefix->assignments);
+	}
+
+	struct list_head assign_later = LIST_HEAD_INIT(assign_later);
+	vlist_for_each_element(&interfaces, iface, node) {
+		if (iface->config_ip.assignment_length < 48 ||
+				iface->config_ip.assignment_length > 64)
+			continue;
 
-	if (!length || length > 64) {
-		assignment = vlist_find(prefix->assignments, iface->name, assignment, node);
-		if (assignment)
-			interface_set_prefix_address(iface, false, assignment);
-	} else {
-		uint64_t want = 1ULL << (64 - length);
-		char *name;
+		size_t namelen = strlen(iface->name) + 1;
+		c = malloc(sizeof(*c) + namelen);
+		c->length = iface->config_ip.assignment_length;
+		c->assigned = iface->config_ip.assignment_hint;
+		c->enabled = false;
+		memcpy(c->name, iface->name, namelen);
+
+		// First process all custom assignments, put all others in later-list
+		if (c->assigned == -1 || !interface_prefix_assign(&prefix->assignments, c)) {
+			if (c->assigned != -1) {
+				c->assigned = -1;
+				netifd_log_message(L_WARNING, "Failed to assign requested subprefix "
+						"of size %hhu for %s, trying other\n", c->length, c->name);
+			}
+			list_add_tail(&c->head, &assign_later);
+		}
+	}
 
-		if (prefix->avail < want && prefix->avail > 0) {
-			do {
-				want = 1ULL << (64 - ++length);
-			} while (want > prefix->avail);
+	// Then try to assign all other + failed custom assignments
+	while (!list_empty(&assign_later)) {
+		c = list_first_entry(&assign_later, struct device_prefix_assignment, head);
+		list_del(&c->head);
+		if (!interface_prefix_assign(&prefix->assignments, c)) {
+			netifd_log_message(L_WARNING, "Failed to assign subprefix "
+					"of size %hhu for %s\n", c->length, c->name);
+			free(c);
 		}
+	}
 
-		if (prefix->avail < want)
-			return;
+	list_for_each_entry(c, &prefix->assignments, head)
+		if ((iface = vlist_find(&interfaces, c->name, iface, node)))
+			interface_set_prefix_address(c, prefix, iface, true);
+}
 
-		assignment = calloc_a(sizeof(*assignment),
-			&name, strlen(iface->name) + 1);
-		assignment->prefix = prefix;
-		assignment->length = length;
-		assignment->name = strcpy(name, iface->name);
 
-		vlist_add(prefix->assignments, &assignment->node, assignment->name);
+void interface_refresh_assignments(bool hint)
+{
+	static bool refresh = false;
+	if (!hint && refresh) {
+		struct device_prefix *p;
+		list_for_each_entry(p, &prefixes, head)
+			interface_update_prefix_assignments(p, true);
 	}
+	refresh = hint;
 }
 
+
 static void
 interface_update_prefix(struct vlist_tree *tree,
 			     struct vlist_node *node_new,
@@ -583,55 +616,43 @@ interface_update_prefix(struct vlist_tree *tree,
 	route.mask = (node_new) ? prefix_new->length : prefix_old->length;
 	route.addr.in6 = (node_new) ? prefix_new->addr : prefix_old->addr;
 
-	if (node_old && node_new) {
-		prefix_new->avail = prefix_old->avail;
-		prefix_new->assignments = prefix_old->assignments;
-		prefix_old->assignments = NULL;
-
-		// Update all assignments
-		struct device_prefix_assignment *assignment;
-		struct vlist_tree *assignments = prefix_new->assignments;
-		vlist_for_each_element(assignments, assignment, node) {
-			assignment->prefix = prefix_new;
-			assignments->update(assignments,
-					&assignment->node, &assignment->node);
-		}
-	} else if (node_new) {
-		prefix_new->avail = 1ULL << (64 - prefix_new->length);
-		prefix_new->assignments = calloc(1, sizeof(*prefix_new->assignments));
-		vlist_init(prefix_new->assignments, avl_strcmp,
-				interface_update_prefix_assignments);
+	struct device_prefix_assignment *c;
+	struct interface *iface;
 
-		// Create initial assignments for interfaces
-		struct interface *iface;
-		vlist_for_each_element(&interfaces, iface, node)
-			interface_ip_set_prefix_assignment(prefix_new, iface,
-					iface->proto_ip.assignment_length);
+	if (node_old && node_new) {
+		// Move assignments and refresh addresses to update valid times
+		list_splice_init(&prefix_old->assignments, &prefix_new->assignments);
 
+		list_for_each_entry(c, &prefix_new->assignments, head)
+			if ((iface = vlist_find(&interfaces, c->name, iface, node)))
+				interface_set_prefix_address(c, prefix_new, iface, true);
+	} else if (node_new) {
 		// Set null-route to avoid routing loops
 		system_add_route(NULL, &route);
-	}
 
-	if (node_old) {
+		INIT_LIST_HEAD(&prefix_new->assignments);
+		interface_update_prefix_assignments(prefix_new, true);
+	} else if (node_old) {
+		interface_update_prefix_assignments(prefix_old, false);
+
 		// Remove null-route
 		system_del_route(NULL, &route);
+	}
 
+	if (node_old) {
 		list_del(&prefix_old->head);
-
-		if (prefix_old->assignments) {
-			vlist_flush_all(prefix_old->assignments);
-			free(prefix_old->assignments);
-		}
 		free(prefix_old);
 	}
 
 	if (node_new)
 		list_add(&prefix_new->head, &prefixes);
+
 }
 
 struct device_prefix*
 interface_ip_add_device_prefix(struct interface *iface, struct in6_addr *addr,
-		uint8_t length, time_t valid_until, time_t preferred_until)
+		uint8_t length, time_t valid_until, time_t preferred_until,
+		struct in6_addr *excl_addr, uint8_t excl_length)
 {
 	struct device_prefix *prefix = calloc(1, sizeof(*prefix));
 	prefix->length = length;
@@ -640,6 +661,11 @@ interface_ip_add_device_prefix(struct interface *iface, struct in6_addr *addr,
 	prefix->valid_until = valid_until;
 	prefix->iface = iface;
 
+	if (excl_addr) {
+		prefix->excl_addr = *excl_addr;
+		prefix->excl_length = excl_length;
+	}
+
 	if (iface)
 		vlist_add(&iface->proto_ip.prefix, &prefix->node, &prefix->addr);
 	else
@@ -675,7 +701,8 @@ interface_ip_set_ula_prefix(const char *prefix)
 		if (ula_prefix)
 			interface_update_prefix(NULL, NULL, &ula_prefix->node);
 
-		ula_prefix = interface_ip_add_device_prefix(NULL, &addr, length, 0, 0);
+		ula_prefix = interface_ip_add_device_prefix(NULL, &addr, length,
+				0, 0, NULL, 0);
 	}
 }
 
@@ -866,6 +893,13 @@ void interface_ip_set_enabled(struct interface_ip_settings *ip, bool enabled)
 			system_del_route(dev, route);
 		route->enabled = _enabled;
 	}
+
+	struct device_prefix *c;
+	struct device_prefix_assignment *a;
+	list_for_each_entry(c, &prefixes, head)
+		list_for_each_entry(a, &c->assignments, head)
+			if (!strcmp(a->name, ip->iface->name))
+				interface_set_prefix_address(a, c, ip->iface, enabled);
 }
 
 void
diff --git a/interface-ip.h b/interface-ip.h
index 9b4f0a1..91358b8 100644
--- a/interface-ip.h
+++ b/interface-ip.h
@@ -43,26 +43,27 @@ union if_addr {
 	struct in6_addr in6;
 };
 
+struct device_prefix_assignment {
+	struct list_head head;
+	int32_t assigned;
+	uint8_t length;
+	bool enabled;
+	char name[];
+};
+
 struct device_prefix {
 	struct vlist_node node;
 	struct list_head head;
-	struct vlist_tree *assignments;
+	struct list_head assignments;
 	struct interface *iface;
-	uint64_t avail;
 	time_t valid_until;
 	time_t preferred_until;
 
 	struct in6_addr addr;
-	uint8_t length;
-};
+	struct in6_addr excl_addr;
 
-struct device_prefix_assignment {
-	struct vlist_node node;
-	struct device_prefix *prefix;
-	struct in6_addr addr;
-	bool enabled;
 	uint8_t length;
-	char *name;
+	uint8_t excl_length;
 };
 
 struct device_addr {
@@ -131,10 +132,10 @@ void interface_ip_update_metric(struct interface_ip_settings *ip, int metric);
 
 struct interface *interface_ip_add_target_route(union if_addr *addr, bool v6);
 
-void interface_ip_set_prefix_assignment(struct device_prefix *prefix,
-		struct interface *iface, uint8_t length);
 struct device_prefix* interface_ip_add_device_prefix(struct interface *iface,
-		struct in6_addr *addr, uint8_t length, time_t valid_until, time_t preferred_until);
+		struct in6_addr *addr, uint8_t length, time_t valid_until, time_t preferred_until,
+		struct in6_addr *excl_addr, uint8_t excl_length);
 void interface_ip_set_ula_prefix(const char *prefix);
+void interface_refresh_assignments(bool hint);
 
 #endif
diff --git a/interface.c b/interface.c
index b304e00..335e0be 100644
--- a/interface.c
+++ b/interface.c
@@ -37,6 +37,8 @@ enum {
 	IFACE_ATTR_DNS_SEARCH,
 	IFACE_ATTR_METRIC,
 	IFACE_ATTR_INTERFACE,
+	IFACE_ATTR_IP6ASSIGN,
+	IFACE_ATTR_IP6HINT,
 	IFACE_ATTR_MAX
 };
 
@@ -50,6 +52,8 @@ static const struct blobmsg_policy iface_attrs[IFACE_ATTR_MAX] = {
 	[IFACE_ATTR_DNS] = { .name = "dns", .type = BLOBMSG_TYPE_ARRAY },
 	[IFACE_ATTR_DNS_SEARCH] = { .name = "dns_search", .type = BLOBMSG_TYPE_ARRAY },
 	[IFACE_ATTR_INTERFACE] = { .name = "interface", .type = BLOBMSG_TYPE_STRING },
+	[IFACE_ATTR_IP6ASSIGN] = { .name = "ip6assign", .type = BLOBMSG_TYPE_INT32 },
+	[IFACE_ATTR_IP6HINT] = { .name = "ip6hint", .type = BLOBMSG_TYPE_STRING },
 };
 
 static const union config_param_info iface_attr_info[IFACE_ATTR_MAX] = {
@@ -483,6 +487,14 @@ interface_init(struct interface *iface, const char *name,
 	if ((cur = tb[IFACE_ATTR_METRIC]))
 		iface->metric = blobmsg_get_u32(cur);
 
+	if ((cur = tb[IFACE_ATTR_IP6ASSIGN]))
+		iface->config_ip.assignment_length = blobmsg_get_u32(cur);
+
+	iface->config_ip.assignment_hint = -1;
+	if ((cur = tb[IFACE_ATTR_IP6HINT]))
+		iface->config_ip.assignment_hint = strtol(blobmsg_get_string(cur), NULL, 16) &
+				~((1 << (64 - iface->config_ip.assignment_length)) - 1);
+
 	iface->config_autostart = iface->autostart;
 }
 
@@ -755,6 +767,9 @@ interface_change_config(struct interface *if_old, struct interface *if_new)
 		interface_ip_set_enabled(&if_old->proto_ip, if_new->proto_ip.enabled);
 	}
 
+	if (UPDATE(config_ip.assignment_length) || UPDATE(config_ip.assignment_hint))
+		interface_refresh_assignments(true);
+
 	interface_write_resolv_conf();
 
 #undef UPDATE
diff --git a/interface.h b/interface.h
index b8c9cad..0c56b36 100644
--- a/interface.h
+++ b/interface.h
@@ -59,7 +59,9 @@ struct interface_ip_settings {
 	bool enabled;
 	bool no_defaultroute;
 	bool no_dns;
+
 	uint8_t assignment_length;
+	int32_t assignment_hint;
 
 	struct vlist_tree addr;
 	struct vlist_tree route;
diff --git a/proto-static.c b/proto-static.c
index 833b6b8..77a536a 100644
--- a/proto-static.c
+++ b/proto-static.c
@@ -54,6 +54,7 @@ static_handler(struct interface_proto_state *proto,
 	case PROTO_CMD_TEARDOWN:
 		break;
 	}
+
 	return ret;
 }
 
diff --git a/proto.c b/proto.c
index 3d611a2..31b3648 100644
--- a/proto.c
+++ b/proto.c
@@ -34,7 +34,6 @@ enum {
 	OPT_GATEWAY,
 	OPT_IP6GW,
 	OPT_IP6PREFIX,
-	OPT_IP6ASSIGN,
 	__OPT_MAX,
 };
 
@@ -46,7 +45,6 @@ static const struct blobmsg_policy proto_ip_attributes[__OPT_MAX] = {
 	[OPT_GATEWAY] = { .name = "gateway", .type = BLOBMSG_TYPE_STRING },
 	[OPT_IP6GW] = { .name = "ip6gw", .type = BLOBMSG_TYPE_STRING },
 	[OPT_IP6PREFIX] = { .name = "ip6prefix", .type = BLOBMSG_TYPE_ARRAY },
-	[OPT_IP6ASSIGN] = { .name = "ip6assign", .type = BLOBMSG_TYPE_INT32 },
 };
 
 static const union config_param_info proto_ip_attr_info[__OPT_MAX] = {
@@ -258,25 +256,6 @@ parse_gateway_option(struct interface *iface, struct blob_attr *attr, bool v6)
 }
 
 static bool
-parse_ip6assign_option(struct interface *iface, struct blob_attr *attr)
-{
-	uint8_t oldval = iface->proto_ip.assignment_length;
-	uint8_t newval = blobmsg_get_u32(attr);
-
-	struct device_prefix *prefix;
-	list_for_each_entry(prefix, &prefixes, head) {
-		if (oldval && oldval != newval)
-			interface_ip_set_prefix_assignment(prefix, iface, 0);
-
-		if (newval && newval <= 64)
-			interface_ip_set_prefix_assignment(prefix, iface, newval);
-	}
-
-	iface->proto_ip.assignment_length = newval;
-	return true;
-}
-
-static bool
 parse_prefix_option(struct interface *iface, const char *str, size_t len)
 {
 	char buf[128] = {0}, *saveptr;
@@ -294,18 +273,33 @@ parse_prefix_option(struct interface *iface, const char *str, size_t len)
 
 	char *prefstr = strtok_r(NULL, ",", &saveptr);
 	char *validstr = (!prefstr) ? NULL : strtok_r(NULL, ",", &saveptr);
+	char *excludestr = (!validstr) ? NULL : strtok_r(NULL, ",", &saveptr);
 
 	uint32_t pref = (!prefstr) ? 0 : strtoul(prefstr, NULL, 10);
 	uint32_t valid = (!validstr) ? 0 : strtoul(validstr, NULL, 10);
 
-	uint8_t length = strtoul(lengthstr, NULL, 10);
+	uint8_t length = strtoul(lengthstr, NULL, 10), excl_length = 0;
 	if (length < 1 || length > 64)
 		return false;
 
-	struct in6_addr addr;
+	struct in6_addr addr, excluded, *excludedp = NULL;
 	if (inet_pton(AF_INET6, addrstr, &addr) < 1)
 		return false;
 
+	if (excludestr) {
+		char *sep = strchr(excludestr, '/');
+		if (!sep)
+			return false;
+
+		*sep = 0;
+		excl_length = atoi(sep + 1);
+
+		if (inet_pton(AF_INET6, excludestr, &excluded) < 1)
+			return false;
+
+		excludedp = &excluded;
+	}
+
 	time_t now = system_get_rtime();
 	time_t preferred_until = 0;
 	if (prefstr && pref != 0xffffffffU)
@@ -316,7 +310,8 @@ parse_prefix_option(struct interface *iface, const char *str, size_t len)
 		valid_until = valid + now;
 
 	interface_ip_add_device_prefix(iface, &addr, length,
-			valid_until, preferred_until);
+			valid_until, preferred_until,
+			excludedp, excl_length);
 	return true;
 }
 
@@ -392,10 +387,6 @@ proto_apply_static_ip_settings(struct interface *iface, struct blob_attr *attr)
 			goto out;
 	}
 
-	if ((cur = tb[OPT_IP6ASSIGN]))
-		if (!parse_ip6assign_option(iface, cur))
-			goto out;
-
 	return 0;
 
 error:
@@ -436,10 +427,6 @@ proto_apply_ip_settings(struct interface *iface, struct blob_attr *attr, bool ex
 			goto out;
 	}
 
-	if ((cur = tb[OPT_IP6ASSIGN]))
-		if (!parse_ip6assign_option(iface, cur))
-			goto out;
-
 	return 0;
 
 out:
diff --git a/ubus.c b/ubus.c
index f2421cc..1036899 100644
--- a/ubus.c
+++ b/ubus.c
@@ -457,11 +457,17 @@ interface_ip_dump_prefix_list(struct interface_ip_settings *ip)
 
 		c = blobmsg_open_table(&b, "assigned");
 		struct device_prefix_assignment *assign;
-		vlist_for_each_element(prefix->assignments, assign, node) {
+		list_for_each_entry(assign, &prefix->assignments, head) {
+			if (!assign->name[0])
+				continue;
+
+			struct in6_addr addr = prefix->addr;
+			addr.s6_addr32[1] |= htonl(assign->assigned);
+
 			void *d = blobmsg_open_table(&b, assign->name);
 
 			buf = blobmsg_alloc_string_buffer(&b, "address", buflen);
-			inet_ntop(AF_INET6, &assign->addr, buf, buflen);
+			inet_ntop(AF_INET6, &addr, buf, buflen);
 			blobmsg_add_string_buffer(&b);
 
 			blobmsg_add_u32(&b, "mask", assign->length);
@@ -486,14 +492,17 @@ interface_ip_dump_prefix_assignment_list(struct interface *iface)
 	struct device_prefix *prefix;
 	list_for_each_entry(prefix, &prefixes, head) {
 		struct device_prefix_assignment *assign;
-		vlist_for_each_element(prefix->assignments, assign, node) {
+		list_for_each_entry(assign, &prefix->assignments, head) {
 			if (strcmp(assign->name, iface->name))
 				continue;
 
+			struct in6_addr addr = prefix->addr;
+			addr.s6_addr32[1] |= htonl(assign->assigned);
+
 			a = blobmsg_open_table(&b, NULL);
 
 			buf = blobmsg_alloc_string_buffer(&b, "address", buflen);
-			inet_ntop(AF_INET6, &assign->addr, buf, buflen);
+			inet_ntop(AF_INET6, &addr, buf, buflen);
 			blobmsg_add_string_buffer(&b);
 
 			blobmsg_add_u32(&b, "mask", assign->length);