dhcp: rework static lease logic

Rework the static lease logic as the existing logic had different issues.
Static leases are now added in a vlist tree which makes it easier to handle
static lease config changes.
For both DHCPv4 and DHCPv6 static assignments are now created upon the
receival of DHCPv4/DHCPv6 messages as before the static assignment was
created even if the client was not physically present.
In case a hostname is specified in a static lease it won't be overriden
anymore by the hostname received from the client.

Signed-off-by: Hans Dedecker <dedeckeh@gmail.com>

4 files changed, 465 insertions, 332 deletions

diff --git a/src/config.c b/src/config.c
index f4a0dcf..d857f24 100644
--- a/src/config.c
+++ b/src/config.c
@@ -14,12 +14,19 @@
 #include <libubox/utils.h>
 #include <libubox/avl.h>
 #include <libubox/avl-cmp.h>
+#include <libubox/list.h>
+#include <libubox/vlist.h>
 
 #include "odhcpd.h"
 
 static struct blob_buf b;
 static int reload_pipe[2];
-struct list_head leases = LIST_HEAD_INIT(leases);
+
+static int lease_cmp(const void *k1, const void *k2, void *ptr);
+static void lease_update(struct vlist_tree *tree, struct vlist_node *node_new,
+			 struct vlist_node *node_old);
+
+struct vlist_tree leases = VLIST_TREE_INIT(leases, lease_cmp, lease_update, true, false);
 AVL_TREE(interfaces, avl_strcmp, false, NULL);
 struct config config = {.legacy = false, .main_dhcpv4 = false,
 			.dhcp_cb = NULL, .dhcp_statefile = NULL,
@@ -199,15 +206,6 @@ static int mkdir_p(char *dir, mode_t mask)
 	return ret;
 }
 
-static void free_lease(struct lease *l)
-{
-	if (l->head.next)
-		list_del(&l->head);
-
-	free(l->duid);
-	free(l);
-}
-
 static void set_interface_defaults(struct interface *iface)
 {
 	iface->learn_routes = 1;
@@ -329,56 +327,64 @@ err:
 	return -1;
 }
 
+static void free_lease(struct lease *l)
+{
+	free(l->hostname);
+	free(l);
+}
+
 static int set_lease(struct uci_section *s)
 {
 	struct blob_attr *tb[LEASE_ATTR_MAX], *c;
+	struct lease *l;
+	size_t duidlen = 0;
+	uint8_t *duid;
 
 	blob_buf_init(&b, 0);
 	uci_to_blob(&b, s, &lease_attr_list);
 	blobmsg_parse(lease_attrs, LEASE_ATTR_MAX, tb, blob_data(b.head), blob_len(b.head));
 
-	size_t hostlen = 1;
-	if ((c = tb[LEASE_ATTR_NAME]))
-		hostlen = blobmsg_data_len(c);
+	if ((c = tb[LEASE_ATTR_DUID]))
+		duidlen = (blobmsg_data_len(c) - 1) / 2;
 
-	struct lease *lease = calloc(1, sizeof(*lease) + hostlen);
-	if (!lease)
+	l = calloc_a(sizeof(*l), &duid, duidlen);
+	if (!l)
 		goto err;
 
-	if (hostlen > 1) {
-		memcpy(lease->hostname, blobmsg_get_string(c), hostlen);
-		if (!odhcpd_valid_hostname(lease->hostname))
-			goto err;
-	}
-
-	if ((c = tb[LEASE_ATTR_IP]))
-		if (inet_pton(AF_INET, blobmsg_get_string(c), &lease->ipaddr) < 0)
-			goto err;
-
 	if ((c = tb[LEASE_ATTR_MAC]))
-		if (!ether_aton_r(blobmsg_get_string(c), &lease->mac))
+		if (!ether_aton_r(blobmsg_get_string(c), &l->mac))
 			goto err;
 
 	if ((c = tb[LEASE_ATTR_DUID])) {
-		size_t duidlen = (blobmsg_data_len(c) - 1) / 2;
-		lease->duid = malloc(duidlen);
-		if (!lease->duid)
-			goto err;
+		ssize_t len;
 
-		ssize_t len = odhcpd_unhexlify(lease->duid,
-				duidlen, blobmsg_get_string(c));
+		l->duid = duid;
+		len = odhcpd_unhexlify(l->duid, duidlen, blobmsg_get_string(c));
 
 		if (len < 0)
 			goto err;
 
-		lease->duid_len = len;
+		l->duid_len = len;
+	}
+
+	if ((c = tb[LEASE_ATTR_NAME])) {
+		l->hostname = strdup(blobmsg_get_string(c));
+		if (!l->hostname || !odhcpd_valid_hostname(l->hostname))
+			goto err;
 	}
 
+	if ((c = tb[LEASE_ATTR_IP]))
+		if (inet_pton(AF_INET, blobmsg_get_string(c), &l->ipaddr) < 0)
+			goto err;
+
 	if ((c = tb[LEASE_ATTR_HOSTID])) {
 		errno = 0;
-		lease->hostid = strtoul(blobmsg_get_string(c), NULL, 16);
+		l->hostid = strtoul(blobmsg_get_string(c), NULL, 16);
 		if (errno)
 			goto err;
+	} else {
+		uint32_t i4a = ntohl(l->ipaddr) & 0xff;
+		l->hostid = ((i4a / 100) << 8) | (((i4a % 100) / 10) << 4) | (i4a % 10);
 	}
 
 	if ((c = tb[LEASE_ATTR_LEASETIME])) {
@@ -386,15 +392,16 @@ static int set_lease(struct uci_section *s)
 		if (time < 0)
 			goto err;
 
-		lease->dhcpv4_leasetime = time;
+		l->leasetime = time;
 	}
 
-	list_add(&lease->head, &leases);
+	INIT_LIST_HEAD(&l->assignments);
+	vlist_add(&leases, &l->node, l);
 	return 0;
 
 err:
-	if (lease)
-		free_lease(lease);
+	if (l)
+		free_lease(l);
 
 	return -1;
 }
@@ -775,17 +782,171 @@ static int set_interface(struct uci_section *s)
 	return config_parse_interface(blob_data(b.head), blob_len(b.head), s->e.name, true);
 }
 
+static void lease_delete_assignments(struct lease *l, bool v6)
+{
+	struct dhcp_assignment *a, *tmp;
+	unsigned int flag = v6 ? OAF_DHCPV6 : OAF_DHCPV4;
+
+	list_for_each_entry_safe(a, tmp, &l->assignments, lease_list) {
+		if (a->flags & flag)
+			v6 ? dhcpv6_ia_free_assignment(a) : dhcpv4_free_assignment(a);
+	}
+}
+
+static void lease_update_assignments(struct lease *l)
+{
+	struct dhcp_assignment *a;
+
+	list_for_each_entry(a, &l->assignments, lease_list) {
+		if (a->hostname)
+			free(a->hostname);
+		a->hostname = NULL;
+
+		if (l->hostname)
+			a->hostname = strdup(l->hostname);
+
+		a->leasetime = l->leasetime;
+	}
+}
+
+static int lease_cmp(const void *k1, const void *k2, _unused void *ptr)
+{
+	const struct lease *l1 = k1, *l2 = k2;
+	int cmp = 0;
+
+	if (l1->duid_len != l2->duid_len)
+		return l1->duid_len - l2->duid_len;
+
+	if (l1->duid_len && l2->duid_len)
+		cmp = memcmp(l1->duid, l2->duid, l1->duid_len);
+
+	if (cmp)
+		return cmp;
+
+	return memcmp(l1->mac.ether_addr_octet, l2->mac.ether_addr_octet,
+		      sizeof(l1->mac.ether_addr_octet));
+}
+
+static void lease_change_config(struct lease *l_old, struct lease *l_new)
+{
+	bool update = false;
+
+	if ((!!l_new->hostname != !!l_old->hostname) ||
+	    (l_new->hostname && strcmp(l_new->hostname, l_old->hostname))) {
+		free(l_old->hostname);
+		l_old->hostname = NULL;
+
+		if (l_new->hostname)
+			l_old->hostname = strdup(l_new->hostname);
+
+		update = true;
+	}
+
+	if (l_old->leasetime != l_new->leasetime) {
+		l_old->leasetime = l_new->leasetime;
+		update = true;
+	}
+
+	if (l_old->ipaddr != l_new->ipaddr) {
+		l_old->ipaddr = l_new->ipaddr;
+		lease_delete_assignments(l_old, false);
+	}
+
+	if (l_old->hostid != l_new->hostid) {
+		l_old->hostid = l_new->hostid;
+		lease_delete_assignments(l_old, true);
+	}
+
+	if (update)
+		lease_update_assignments(l_old);
+
+	free_lease(l_new);
+}
+
+static void lease_delete(struct lease *l)
+{
+	struct dhcp_assignment *a;
+
+	list_for_each_entry(a, &l->assignments, lease_list) {
+		if (a->flags & OAF_DHCPV6)
+			dhcpv6_ia_free_assignment(a);
+		else if (a->flags & OAF_DHCPV4)
+			dhcpv4_free_assignment(a);
+	}
+
+	free_lease(l);
+}
+
+static void lease_update(_unused struct vlist_tree *tree, struct vlist_node *node_new,
+			 struct vlist_node *node_old)
+{
+	struct lease *lease_new = container_of(node_new, struct lease, node);
+	struct lease *lease_old = container_of(node_old, struct lease, node);
+
+	if (node_old && node_new)
+		lease_change_config(lease_old, lease_new);
+	else if (node_old)
+		lease_delete(lease_old);
+}
+
+struct lease *config_find_lease_by_duid(const uint8_t *duid, const uint16_t len)
+{
+	struct lease *l;
+
+	vlist_for_each_element(&leases, l, node) {
+		if (l->duid_len == len && !memcmp(l->duid, duid, len))
+			return l;
+	}
+
+	return NULL;
+}
+
+struct lease *config_find_lease_by_mac(const uint8_t *mac)
+{
+	struct lease *l;
+
+	vlist_for_each_element(&leases, l, node) {
+		if (!memcmp(l->mac.ether_addr_octet, mac,
+			    sizeof(l->mac.ether_addr_octet)))
+			return l;
+	}
+
+	return NULL;
+}
+
+struct lease *config_find_lease_by_hostid(const uint32_t hostid)
+{
+	struct lease *l;
+
+	vlist_for_each_element(&leases, l, node) {
+		if (l->hostid == hostid)
+			return l;
+	}
+
+	return NULL;
+}
+
+struct lease *config_find_lease_by_ipaddr(const uint32_t ipaddr)
+{
+	struct lease *l;
+
+	vlist_for_each_element(&leases, l, node) {
+		if (l->ipaddr == ipaddr)
+			return l;
+	}
+
+	return NULL;
+}
+
 void odhcpd_reload(void)
 {
 	struct uci_context *uci = uci_alloc_context();
 	struct interface *master = NULL, *i, *tmp;
 
-	while (!list_empty(&leases))
-		free_lease(list_first_entry(&leases, struct lease, head));
-
 	if (!uci)
 		return;
 
+	vlist_update(&leases);
 	avl_for_each_element(&interfaces, i, avl)
 		clean_interface(i);
 
@@ -814,6 +975,8 @@ void odhcpd_reload(void)
 		free(path);
 	}
 
+	vlist_flush(&leases);
+
 #ifdef WITH_UBUS
 	ubus_apply_network();
 #endif
@@ -937,4 +1100,3 @@ void odhcpd_run(void)
 	odhcpd_reload();
 	uloop_run();
 }
-
diff --git a/src/dhcpv4.c b/src/dhcpv4.c
index 00e4c3f..da2c051 100644
--- a/src/dhcpv4.c
+++ b/src/dhcpv4.c
@@ -37,11 +37,9 @@
 
 static void dhcpv4_netevent_cb(unsigned long event, struct netevent_handler_info *info);
 static int setup_dhcpv4_addresses(struct interface *iface);
-static void update_static_assignments(struct interface *iface);
 static bool addr_is_fr_ip(struct interface *iface, struct in_addr *addr);
 static void valid_until_cb(struct uloop_timeout *event);
 static void handle_addrlist_change(struct interface *iface);
-static void free_dhcpv4_assignment(struct dhcp_assignment *a);
 static void dhcpv4_fr_start(struct dhcp_assignment *a);
 static void dhcpv4_fr_rand_delay(struct dhcp_assignment *a);
 static void dhcpv4_fr_stop(struct dhcp_assignment *a);
@@ -158,11 +156,9 @@ int dhcpv4_setup_interface(struct interface *iface, bool enable)
 
 		iface->dhcpv4_event.handle_dgram = handle_dhcpv4;
 		odhcpd_register(&iface->dhcpv4_event);
-
-		update_static_assignments(iface);
 	} else if (iface->dhcpv4_assignments.next) {
 		while (!list_empty(&iface->dhcpv4_assignments))
-			free_dhcpv4_assignment(list_first_entry(&iface->dhcpv4_assignments,
+			dhcpv4_free_assignment(list_first_entry(&iface->dhcpv4_assignments,
 							struct dhcp_assignment, head));
 	}
 
@@ -206,17 +202,6 @@ static struct dhcp_assignment *find_assignment_by_hwaddr(struct interface *iface
 	return NULL;
 }
 
-static struct dhcp_assignment *find_assignment_by_addr(struct interface *iface, const uint32_t addr)
-{
-	struct dhcp_assignment *a;
-
-	list_for_each_entry(a, &iface->dhcpv4_assignments, head)
-		if (a->addr == addr)
-			return a;
-
-	return NULL;
-}
-
 static int setup_dhcpv4_addresses(struct interface *iface)
 {
 	iface->dhcpv4_start_ip.s_addr = INADDR_ANY;
@@ -291,68 +276,6 @@ static int setup_dhcpv4_addresses(struct interface *iface)
 	return 0;
 }
 
-static void update_static_assignments(struct interface *iface)
-{
-	struct dhcp_assignment *a, *c;
-
-	/* Cleanup static entries not belonging to the network */
-	list_for_each_entry_safe(a, c, &iface->dhcpv4_assignments, head) {
-		if ((a->flags & OAF_STATIC) &&
-				((a->addr & iface->dhcpv4_mask.s_addr) !=
-				 (iface->dhcpv4_start.s_addr & iface->dhcpv4_mask.s_addr)))
-			free_dhcpv4_assignment(a);
-	}
-
-	/* Parse static entries */
-	struct lease *lease;
-	list_for_each_entry(lease, &leases, head) {
-		if ((iface->dhcpv4_start_ip.s_addr & iface->dhcpv4_mask.s_addr) !=
-				(lease->ipaddr.s_addr & iface->dhcpv4_mask.s_addr)) {
-			continue;
-		}
-
-		a = find_assignment_by_hwaddr(iface, lease->mac.ether_addr_octet);
-
-		if (!a) {
-			/* Check if there's an assignment with the specified IP address */
-			if (find_assignment_by_addr(iface, lease->ipaddr.s_addr))
-				continue;
-
-			/* Construct entry */
-			a = calloc(1, sizeof(*a));
-			if (!a) {
-				syslog(LOG_ERR, "Calloc failed for static lease on %s", iface->name);
-				continue;
-			}
-			memcpy(a->hwaddr, lease->mac.ether_addr_octet, sizeof(a->hwaddr));
-		}
-
-		a->leasetime = lease->dhcpv4_leasetime;
-
-		a->addr = lease->ipaddr.s_addr;
-		/* Static assignment */
-		a->flags |= OAF_STATIC;
-		/* Infinite valid */
-		a->valid_until = 0;
-		a->iface = iface;
-		if (lease->hostname[0]) {
-			free(a->hostname);
-			a->hostname = strdup(lease->hostname);
-		}
-
-		/* Assign to all interfaces */
-		list_for_each_entry(c, &iface->dhcpv4_assignments, head) {
-			if (ntohl(c->addr) > ntohl(a->addr)) {
-				list_add_tail(&a->head, &c->head);
-				break;
-			}
-		}
-
-		if (&c->head == &iface->dhcpv4_assignments)
-			list_add(&a->head, &iface->dhcpv4_assignments);
-	}
-}
-
 static void inc_ref_cnt_ip(struct odhcpd_ref_ip **ptr, struct odhcpd_ref_ip *ip)
 {
 	*ptr = ip;
@@ -422,7 +345,7 @@ static void valid_until_cb(struct uloop_timeout *event)
 		struct dhcp_assignment *a, *n;
 		list_for_each_entry_safe(a, n, &iface->dhcpv4_assignments, head) {
 			if (!INFINITE_VALID(a->valid_until) && a->valid_until < now)
-				free_dhcpv4_assignment(a);
+				dhcpv4_free_assignment(a);
 		}
 	}
 	uloop_timeout_set(event, 1000);
@@ -495,11 +418,14 @@ static char *dhcpv4_msg_to_string(uint8_t reqmsg)
 	}
 }
 
-static void free_dhcpv4_assignment(struct dhcp_assignment *a)
+void dhcpv4_free_assignment(struct dhcp_assignment *a)
 {
 	if (a->head.next)
 		list_del(&a->head);
 
+	if (a->lease_list.next)
+		list_del(&a->lease_list);
+
 	if (a->fr_ip)
 		dhcpv4_fr_stop(a);
 
@@ -665,15 +591,15 @@ static void dhcpv4_fr_stop(struct dhcp_assignment *a)
 static void handle_dhcpv4(void *addr, void *data, size_t len,
 		struct interface *iface, _unused void *dest_addr)
 {
+	struct dhcpv4_message *req = data;
+
 	if (!iface->dhcpv4)
 		return;
 
-	struct dhcpv4_message *req = data;
 	if (len < offsetof(struct dhcpv4_message, options) + 4 ||
 			req->op != DHCPV4_BOOTREQUEST || req->hlen != 6)
 		return;
 
-
 	syslog(LOG_NOTICE, "Got DHCPv4 request on %s", iface->name);
 
 	if (!iface->dhcpv4_start_ip.s_addr && !iface->dhcpv4_end_ip.s_addr) {
@@ -749,20 +675,20 @@ static void handle_dhcpv4(void *addr, void *data, size_t len,
 	}
 
 	if (reqmsg != DHCPV4_MSG_DISCOVER && reqmsg != DHCPV4_MSG_REQUEST &&
-			reqmsg != DHCPV4_MSG_INFORM && reqmsg != DHCPV4_MSG_DECLINE &&
-			reqmsg != DHCPV4_MSG_RELEASE)
+	    reqmsg != DHCPV4_MSG_INFORM && reqmsg != DHCPV4_MSG_DECLINE &&
+	    reqmsg != DHCPV4_MSG_RELEASE)
 		return;
 
-	struct dhcp_assignment *lease = NULL;
+	struct dhcp_assignment *a = NULL;
 	uint32_t serverid = iface->dhcpv4_local.s_addr;
 	uint32_t fr_serverid = INADDR_ANY;
 
 	if (reqmsg != DHCPV4_MSG_INFORM)
-		lease = dhcpv4_lease(iface, reqmsg, req->chaddr, reqaddr,
-					&leasetime, hostname, hostname_len,
-					accept_fr_nonce, &incl_fr_opt, &fr_serverid);
+		a = dhcpv4_lease(iface, reqmsg, req->chaddr, reqaddr,
+				 &leasetime, hostname, hostname_len,
+				 accept_fr_nonce, &incl_fr_opt, &fr_serverid);
 
-	if (!lease) {
+	if (!a) {
 		if (reqmsg == DHCPV4_MSG_REQUEST)
 			msg = DHCPV4_MSG_NAK;
 		else if (reqmsg == DHCPV4_MSG_DISCOVER)
@@ -770,8 +696,8 @@ static void handle_dhcpv4(void *addr, void *data, size_t len,
 	} else if (reqmsg == DHCPV4_MSG_DISCOVER)
 		msg = DHCPV4_MSG_OFFER;
 	else if (reqmsg == DHCPV4_MSG_REQUEST &&
-			((reqaddr && reqaddr != lease->addr) ||
-			 (req->ciaddr.s_addr && req->ciaddr.s_addr != lease->addr))) {
+			((reqaddr && reqaddr != a->addr) ||
+			 (req->ciaddr.s_addr && req->ciaddr.s_addr != a->addr))) {
 		msg = DHCPV4_MSG_NAK;
 		/*
 		 * DHCP client requested an IP which we can't offer to him. Probably the
@@ -814,10 +740,10 @@ static void handle_dhcpv4(void *addr, void *data, size_t len,
 	dhcpv4_put(&reply, &cookie, DHCPV4_OPT_MESSAGE, 1, &msg);
 	dhcpv4_put(&reply, &cookie, DHCPV4_OPT_SERVERID, 4, &serverid);
 
-	if (lease) {
+	if (a) {
 		uint32_t val;
 
-		reply.yiaddr.s_addr = lease->addr;
+		reply.yiaddr.s_addr = a->addr;
 
 		val = htonl(leasetime);
 		dhcpv4_put(&reply, &cookie, DHCPV4_OPT_LEASETIME, 4, &val);
@@ -833,9 +759,9 @@ static void handle_dhcpv4(void *addr, void *data, size_t len,
 		dhcpv4_put(&reply, &cookie, DHCPV4_OPT_NETMASK, 4,
 				&iface->dhcpv4_mask.s_addr);
 
-		if (lease->hostname)
+		if (a->hostname)
 			dhcpv4_put(&reply, &cookie, DHCPV4_OPT_HOSTNAME,
-					strlen(lease->hostname), lease->hostname);
+					strlen(a->hostname), a->hostname);
 
 		if (iface->dhcpv4_bcast.s_addr != INADDR_ANY)
 			dhcpv4_put(&reply, &cookie, DHCPV4_OPT_BROADCAST, 4, &iface->dhcpv4_bcast);
@@ -851,7 +777,7 @@ static void handle_dhcpv4(void *addr, void *data, size_t len,
 					.key = {0},
 				};
 
-				memcpy(auth.key, lease->key, sizeof(auth.key));
+				memcpy(auth.key, a->key, sizeof(auth.key));
 				dhcpv4_put(&reply, &cookie, DHCPV4_OPT_AUTHENTICATION, sizeof(auth), &auth);
 			} else {
 				uint8_t one = 1;
@@ -966,60 +892,89 @@ static void handle_dhcpv4(void *addr, void *data, size_t len,
 #endif
 }
 
-static bool dhcpv4_assign(struct interface *iface,
-		struct dhcp_assignment *assign, uint32_t raddr)
+static bool dhcpv4_assign(struct interface *iface, struct dhcp_assignment *a,
+			  uint32_t raddr)
 {
+	struct dhcp_assignment *c;
 	uint32_t start = ntohl(iface->dhcpv4_start_ip.s_addr);
 	uint32_t end = ntohl(iface->dhcpv4_end_ip.s_addr);
 	uint32_t count = end - start + 1;
+	uint32_t seed = 0;
+
+	/* Preconfigured IP address by static lease */
+	if (a->addr) {
+		if (list_empty(&iface->dhcpv4_assignments)) {
+			list_add(&a->head, &iface->dhcpv4_assignments);
+			return true;
+		}
+
+		list_for_each_entry(c, &iface->dhcpv4_assignments, head) {
+			if (ntohl(c->addr) > ntohl(a->addr)) {
+				list_add_tail(&a->head, &c->head);
+				return true;
+			} else if (ntohl(a->addr) == ntohl(c->addr))
+				return false;
+		}
+	}
 
 	/* try to assign the IP the client asked for */
 	if (start <= ntohl(raddr) && ntohl(raddr) <= end &&
-			!find_assignment_by_addr(iface, raddr)) {
-		assign->addr = raddr;
-		syslog(LOG_INFO, "Assigning the IP the client asked for: %u.%u.%u.%u",
-				((uint8_t *)&assign->addr)[0],
-				((uint8_t *)&assign->addr)[1],
-				((uint8_t *)&assign->addr)[2],
-				((uint8_t *)&assign->addr)[3]);
-		return true;
+	    !config_find_lease_by_ipaddr(raddr)) {
+		list_for_each_entry(c, &iface->dhcpv4_assignments, head) {
+			if (ntohl(c->addr) > ntohl(raddr)) {
+				list_add_tail(&a->head, &c->head);
+				a->addr = raddr;
+
+				syslog(LOG_INFO, "Assigning the IP the client asked for: %u.%u.%u.%u",
+				       ((uint8_t *)&a->addr)[0], ((uint8_t *)&a->addr)[1],
+				       ((uint8_t *)&a->addr)[2], ((uint8_t *)&a->addr)[3]);
+
+				return true;
+			} else if (ntohl(raddr) == ntohl(c->addr))
+				break;
+		}
 	}
 
 	/* Seed RNG with checksum of hwaddress */
-	uint32_t seed = 0;
-	for (size_t i = 0; i < sizeof(assign->hwaddr); ++i) {
+	for (size_t i = 0; i < sizeof(a->hwaddr); ++i) {
 		/* Knuth's multiplicative method */
-		uint8_t o = assign->hwaddr[i];
+		uint8_t o = a->hwaddr[i];
 		seed += (o*2654435761) % UINT32_MAX;
 	}
 
 	srand(seed);
 
-	uint32_t try = (((uint32_t)rand()) % count) + start;
+	for (uint32_t i = 0, try = (((uint32_t)rand()) % count) + start; i < count;
+	     ++i, try = (((try - start) + 1) % count) + start) {
 
-	if (list_empty(&iface->dhcpv4_assignments)) {
-		assign->addr = htonl(try);
-		syslog(LOG_INFO, "Assigning mapped IP (empty list): %u.%u.%u.%u",
-				((uint8_t *)&assign->addr)[0],
-				((uint8_t *)&assign->addr)[1],
-				((uint8_t *)&assign->addr)[2],
-				((uint8_t *)&assign->addr)[3]);
-		return true;
-	}
+		if (config_find_lease_by_ipaddr(try))
+			continue;
+
+		if (list_empty(&iface->dhcpv4_assignments)) {
+			list_add(&a->head, &iface->dhcpv4_assignments);
+			a->addr = htonl(try);
+
+			syslog(LOG_INFO, "Assigning mapped IP (empty list): %u.%u.%u.%u",
+			       ((uint8_t *)&a->addr)[0], ((uint8_t *)&a->addr)[1],
+			       ((uint8_t *)&a->addr)[2], ((uint8_t *)&a->addr)[3]);
 
-	for (uint32_t i = 0; i < count; ++i) {
-		if (!find_assignment_by_addr(iface, htonl(try))) {
-			/* test was successful: IP address is not assigned, assign it */
-			assign->addr = htonl(try);
-			syslog(LOG_DEBUG, "Assigning mapped IP: %u.%u.%u.%u (try %u of %u)",
-					((uint8_t *)&assign->addr)[0],
-					((uint8_t *)&assign->addr)[1],
-					((uint8_t *)&assign->addr)[2],
-					((uint8_t *)&assign->addr)[3],
-					i, count);
 			return true;
 		}
-		try = (((try - start) + 1) % count) + start;
+
+		list_for_each_entry(c, &iface->dhcpv4_assignments, head) {
+			if (ntohl(c->addr) > try) {
+				list_add_tail(&a->head, &c->head);
+				a->addr = htonl(try);
+
+				syslog(LOG_DEBUG, "Assigning mapped IP: %u.%u.%u.%u (try %u of %u)",
+					((uint8_t *)&a->addr)[0], ((uint8_t *)&a->addr)[1],
+					((uint8_t *)&a->addr)[2], ((uint8_t *)&a->addr)[3],
+					i, count);
+
+				return true;
+			} else if (try == ntohl(c->addr))
+				break;
+		}
 	}
 
 	syslog(LOG_WARNING, "Can't assign any IP address -> address space is full");
@@ -1027,15 +982,21 @@ static bool dhcpv4_assign(struct interface *iface,
 }
 
 
-static struct dhcp_assignment* dhcpv4_lease(struct interface *iface,
-		enum dhcpv4_msg msg, const uint8_t *mac, const uint32_t reqaddr,
-		uint32_t *leasetime, const char *hostname, const size_t hostname_len,
-		const bool accept_fr_nonce, bool *incl_fr_opt, uint32_t *fr_serverid)
+static struct dhcp_assignment*
+dhcpv4_lease(struct interface *iface, enum dhcpv4_msg msg, const uint8_t *mac,
+	     const uint32_t reqaddr, uint32_t *leasetime, const char *hostname,
+	     const size_t hostname_len, const bool accept_fr_nonce, bool *incl_fr_opt,
+	     uint32_t *fr_serverid)
 {
 	struct dhcp_assignment *a = find_assignment_by_hwaddr(iface, mac);
-	struct dhcp_assignment *lease = NULL;
+	struct lease *l = config_find_lease_by_mac(mac);
 	time_t now = odhcpd_time();
 
+	if (l && a && a->lease != l) {
+		dhcpv4_free_assignment(a);
+		a = NULL;
+	}
+
 	if (a && (a->flags & OAF_BOUND) && a->fr_ip) {
 		*fr_serverid = a->fr_ip->addr.addr.in.s_addr;
 		dhcpv4_fr_stop(a);
@@ -1045,7 +1006,7 @@ static struct dhcp_assignment* dhcpv4_lease(struct interface *iface,
 		bool assigned = !!a;
 
 		if (!a) {
-			if (!iface->no_dynamic_dhcp) {
+			if (!iface->no_dynamic_dhcp || l) {
 				/* Create new binding */
 				a = calloc(1, sizeof(*a));
 				if (!a) {
@@ -1054,22 +1015,35 @@ static struct dhcp_assignment* dhcpv4_lease(struct interface *iface,
 					return NULL;
 				}
 				memcpy(a->hwaddr, mac, sizeof(a->hwaddr));
-				/* Don't consider new assignment as infinite */
-				a->valid_until = now;
+				/* Set valid time to 0 for static lease indicating */
+				/* infinite lifetime otherwise current time        */
+				a->valid_until = l ? 0 : now;
+				a->iface = iface;
+				a->flags = OAF_DHCPV4;
+				a->addr = l ? l->ipaddr : INADDR_ANY;
 
 				assigned = dhcpv4_assign(iface, a, reqaddr);
-				if (assigned) {
-					a->iface = iface;
-					list_add(&a->head, &iface->dhcpv4_assignments);
+
+				if (l) {
+					a->flags |= OAF_STATIC;
+
+					if (l->hostname)
+						a->hostname = strdup(l->hostname);
+
+					if (l->leasetime)
+						a->leasetime = l->leasetime;
+
+					list_add(&a->lease_list, &l->assignments);
+					a->lease = l;
 				}
 			}
-		} else if ((a->addr & iface->dhcpv4_mask.s_addr) !=
-				(iface->dhcpv4_start_ip.s_addr & iface->dhcpv4_mask.s_addr)) {
+		} else if (((a->addr & iface->dhcpv4_mask.s_addr) !=
+			    (iface->dhcpv4_start_ip.s_addr & iface->dhcpv4_mask.s_addr)) &&
+			    !(a->flags & OAF_STATIC)) {
 			list_del(&a->head);
+			a->addr = INADDR_ANY;
 
 			assigned = dhcpv4_assign(iface, a, reqaddr);
-			if (assigned)
-				list_add(&a->head, &iface->dhcpv4_assignments);
 		}
 
 		if (assigned) {
@@ -1090,7 +1064,7 @@ static struct dhcp_assignment* dhcpv4_lease(struct interface *iface,
 				if (!(a->flags & OAF_STATIC))
 					a->valid_until = now;
 			} else {
-				if (hostname_len > 0) {
+				if ((!(a->flags & OAF_STATIC) || !a->hostname) && hostname_len > 0) {
 					a->hostname = realloc(a->hostname, hostname_len + 1);
 					if (a->hostname) {
 						memcpy(a->hostname, hostname, hostname_len);
@@ -1116,12 +1090,10 @@ static struct dhcp_assignment* dhcpv4_lease(struct interface *iface,
 			}
 		} else if (!assigned && a) {
 			/* Cleanup failed assignment */
-			free_dhcpv4_assignment(a);
+			dhcpv4_free_assignment(a);
 			a = NULL;
 		}
 
-		if (assigned && a)
-			lease = a;
 	} else if (msg == DHCPV4_MSG_RELEASE && a) {
 		a->flags &= ~OAF_BOUND;
 
@@ -1139,5 +1111,5 @@ static struct dhcp_assignment* dhcpv4_lease(struct interface *iface,
 
 	dhcpv6_ia_write_statefile();
 
-	return lease;
+	return a;
 }
diff --git a/src/dhcpv6-ia.c b/src/dhcpv6-ia.c
index 7c3ccad..4cc6fab 100644
--- a/src/dhcpv6-ia.c
+++ b/src/dhcpv6-ia.c
@@ -40,7 +40,6 @@
      (addrs)[(i)].prefix > 64)
 
 static void dhcpv6_netevent_cb(unsigned long event, struct netevent_handler_info *info);
-static void free_dhcpv6_assignment(struct dhcp_assignment *c);
 static void set_border_assignment_size(struct interface *iface, struct dhcp_assignment *b);
 static void handle_addrlist_change(struct netevent_handler_info *info);
 static void start_reconf(struct dhcp_assignment *a);
@@ -68,13 +67,12 @@ int dhcpv6_ia_setup_interface(struct interface *iface, bool enable)
 
 		while (!list_empty(&iface->ia_assignments)) {
 			c = list_first_entry(&iface->ia_assignments, struct dhcp_assignment, head);
-			free_dhcpv6_assignment(c);
+			dhcpv6_ia_free_assignment(c);
 		}
 	}
 
 	if (enable && iface->dhcpv6 == MODE_SERVER) {
 		struct dhcp_assignment *border;
-		struct lease *lease;
 
 		if (!iface->ia_assignments.next)
 			INIT_LIST_HEAD(&iface->ia_assignments);
@@ -93,57 +91,6 @@ int dhcpv6_ia_setup_interface(struct interface *iface, bool enable)
 			border = list_last_entry(&iface->ia_assignments, struct dhcp_assignment, head);
 
 		set_border_assignment_size(iface, border);
-
-		/* Parse static entries */
-		list_for_each_entry(lease, &leases, head) {
-			/* Construct entry */
-			size_t duid_len = lease->duid_len ? lease->duid_len : 14;
-			struct dhcp_assignment *a = calloc(1, sizeof(*a) + duid_len);
-			if (!a) {
-				syslog(LOG_ERR, "Calloc failed for static lease assignment on %s",
-					iface->name);
-				return -1;
-			}
-
-			a->leasetime = lease->dhcpv4_leasetime;
-
-			a->clid_len = duid_len;
-			a->length = 128;
-			if (lease->hostid) {
-				a->assigned = lease->hostid;
-			} else {
-				uint32_t i4a = ntohl(lease->ipaddr.s_addr) & 0xff;
-				a->assigned = ((i4a / 100) << 8) | (((i4a % 100) / 10) << 4) | (i4a % 10);
-			}
-
-			odhcpd_urandom(a->key, sizeof(a->key));
-			memcpy(a->clid_data, lease->duid, lease->duid_len);
-			memcpy(a->mac, lease->mac.ether_addr_octet, sizeof(a->mac));
-			/* Static assignment */
-			a->flags |= OAF_STATIC;
-			/* Infinite valid */
-			a->valid_until = 0;
-
-			/* Assign to all interfaces */
-			struct dhcp_assignment *c;
-			list_for_each_entry(c, &iface->ia_assignments, head) {
-				if (c->length != 128 || c->assigned > a->assigned) {
-					list_add_tail(&a->head, &c->head);
-					break;
-				} else if (c->assigned == a->assigned)
-					/* Already an assignment with that number */
-					break;
-			}
-
-			if (a->head.next) {
-				a->iface = iface;
-				if (lease->hostname[0]) {
-					free(a->hostname);
-					a->hostname = strdup(lease->hostname);
-				}
-			} else
-				free_dhcpv6_assignment(a);
-		}
 	}
 	return 0;
 }
@@ -166,24 +113,6 @@ static void dhcpv6_netevent_cb(unsigned long event, struct netevent_handler_info
 }
 
 
-static void free_dhcpv6_assignment(struct dhcp_assignment *c)
-{
-	if (c->managed_sock.fd.registered) {
-		ustream_free(&c->managed_sock.stream);
-		close(c->managed_sock.fd.fd);
-	}
-
-	if (c->head.next)
-		list_del(&c->head);
-
-	if (c->reconf_cnt)
-		stop_reconf(c);
-
-	free(c->managed);
-	free(c->hostname);
-	free(c);
-}
-
 static inline bool valid_prefix_length(const struct dhcp_assignment *a, const uint8_t prefix_length)
 {
 	return (a->managed_size || a->length > prefix_length);
@@ -272,8 +201,29 @@ static int send_reconf(struct dhcp_assignment *assign)
 	return odhcpd_send(iface->dhcpv6_event.uloop.fd, &assign->peer, &iov, 1, iface);
 }
 
+void dhcpv6_ia_free_assignment(struct dhcp_assignment *a)
+{
+	if (a->managed_sock.fd.registered) {
+		ustream_free(&a->managed_sock.stream);
+		close(a->managed_sock.fd.fd);
+	}
+
+	if (a->head.next)
+		list_del(&a->head);
+
+	if (a->lease_list.next)
+		list_del(&a->lease_list);
+
+	if (a->reconf_cnt)
+		stop_reconf(a);
+
+	free(a->managed);
+	free(a->hostname);
+	free(a);
+}
+
 void dhcpv6_ia_enum_addrs(struct interface *iface, struct dhcp_assignment *c,
-				time_t now, dhcpv6_binding_cb_handler_t func, void *arg)
+			  time_t now, dhcpv6_binding_cb_handler_t func, void *arg)
 {
 	struct odhcpd_ipaddr *addrs = (c->managed) ? c->managed : iface->addr6;
 	size_t addrlen = (c->managed) ? (size_t)c->managed_size : iface->addr6_len;
@@ -584,7 +534,7 @@ static void managed_handle_pd_data(struct ustream *s, _unused int bytes_new)
 	}
 
 	if (first && c->managed_size == 0)
-		free_dhcpv6_assignment(c);
+		dhcpv6_ia_free_assignment(c);
 	else if (first && !(c->flags & OAF_STATIC))
 		c->valid_until = now + 150;
 }
@@ -691,12 +641,28 @@ static bool assign_pd(struct interface *iface, struct dhcp_assignment *assign)
 	return false;
 }
 
-static bool assign_na(struct interface *iface, struct dhcp_assignment *assign)
+static bool assign_na(struct interface *iface, struct dhcp_assignment *a)
 {
-	/* Seed RNG with checksum of DUID */
+	struct dhcp_assignment *c;
 	uint32_t seed = 0;
-	for (size_t i = 0; i < assign->clid_len; ++i)
-		seed += assign->clid_data[i];
+
+	/* Preconfigured assignment by static lease */
+	if (a->assigned) {
+		list_for_each_entry(c, &iface->ia_assignments, head) {
+			if (c->length == 0)
+				continue;
+
+			if (c->assigned > a->assigned || c->length != 128) {
+				list_add_tail(&a->head, &c->head);
+				return true;
+			} else if (c->assigned == a->assigned)
+				return false;
+		}
+	}
+
+	/* Seed RNG with checksum of DUID */
+	for (size_t i = 0; i < a->clid_len; ++i)
+		seed += a->clid_data[i];
 	srand(seed);
 
 	/* Try to assign up to 100x */
@@ -704,14 +670,16 @@ static bool assign_na(struct interface *iface, struct dhcp_assignment *assign)
 		uint32_t try;
 		do try = ((uint32_t)rand()) % 0x0fff; while (try < 0x100);
 
-		struct dhcp_assignment *c;
+		if (config_find_lease_by_hostid(try))
+			continue;
+
 		list_for_each_entry(c, &iface->ia_assignments, head) {
 			if (c->length == 0)
 				continue;
 
 			if (c->assigned > try || c->length != 128) {
-				assign->assigned = try;
-				list_add_tail(&assign->head, &c->head);
+				a->assigned = try;
+				list_add_tail(&a->head, &c->head);
 				return true;
 			} else if (c->assigned == try)
 				break;
@@ -818,7 +786,7 @@ static void valid_until_cb(struct uloop_timeout *event)
 			if (!INFINITE_VALID(a->valid_until) && a->valid_until < now) {
 				if ((a->length < 128 && a->clid_len > 0) ||
 						(a->length == 128 && a->clid_len == 0))
-					free_dhcpv6_assignment(a);
+					dhcpv6_ia_free_assignment(a);
 
 			}
 		}
@@ -1160,18 +1128,16 @@ static bool dhcpv6_ia_on_link(const struct dhcpv6_ia_hdr *ia, struct dhcp_assign
 ssize_t dhcpv6_ia_handle_IAs(uint8_t *buf, size_t buflen, struct interface *iface,
 		const struct sockaddr_in6 *addr, const void *data, const uint8_t *end)
 {
-	time_t now = odhcpd_time();
-	size_t response_len = 0;
+	struct lease *l;
+	struct dhcp_assignment *first = NULL;
 	const struct dhcpv6_client_header *hdr = data;
-	uint8_t *start = (uint8_t*)&hdr[1], *odata;
-	uint16_t otype, olen;
-	/* Find and parse client-id and hostname */
-	bool accept_reconf = false;
-	uint8_t *clid_data = NULL, clid_len = 0, mac[6] = {0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
-	char hostname[256];
-	size_t hostname_len = 0;
-	bool notonlink = false, rapid_commit = false;
-	char duidbuf[261];
+	time_t now = odhcpd_time();
+	uint16_t otype, olen, clid_len = 0;
+	uint8_t *start = (uint8_t *)&hdr[1], *odata;
+	uint8_t *clid_data = NULL, mac[6] = {0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
+	size_t hostname_len = 0, response_len = 0;
+	bool notonlink = false, rapid_commit = false, accept_reconf = false;
+	char duidbuf[261], hostname[256];
 
 	dhcpv6_for_each_option(start, end, otype, olen, odata) {
 		if (otype == DHCPV6_OPT_CLIENTID) {
@@ -1201,7 +1167,10 @@ ssize_t dhcpv6_ia_handle_IAs(uint8_t *buf, size_t buflen, struct interface *ifac
 	if (!clid_data || !clid_len || clid_len > 130)
 		goto out;
 
-	struct dhcp_assignment *first = NULL;
+	l = config_find_lease_by_duid(clid_data, clid_len);
+	if (!l)
+		l = config_find_lease_by_mac(mac);
+
 	dhcpv6_for_each_option(start, end, otype, olen, odata) {
 		bool is_pd = (otype == DHCPV6_OPT_IA_PD);
 		bool is_na = (otype == DHCPV6_OPT_IA_NA);
@@ -1247,27 +1216,25 @@ ssize_t dhcpv6_ia_handle_IAs(uint8_t *buf, size_t buflen, struct interface *ifac
 		/* Find assignment */
 		struct dhcp_assignment *c, *a = NULL;
 		list_for_each_entry(c, &iface->ia_assignments, head) {
-			if (((c->clid_len == clid_len && !memcmp(c->clid_data, clid_data, clid_len)) ||
-					(c->clid_len >= clid_len && !c->clid_data[0] && !c->clid_data[1]
-						&& !memcmp(c->mac, mac, sizeof(mac)))) &&
-					(!(c->flags & (OAF_BOUND|OAF_TENTATIVE)) || c->iaid == ia->iaid) &&
-					(INFINITE_VALID(c->valid_until) || now < c->valid_until) &&
-					((is_pd && c->length <= 64) || (is_na && c->length == 128))) {
+			if ((c->clid_len == clid_len && !memcmp(c->clid_data, clid_data, clid_len)) &&
+			    c->iaid == ia->iaid && (INFINITE_VALID(c->valid_until) || now < c->valid_until) &&
+			    ((is_pd && c->length <= 64) || (is_na && c->length == 128))) {
 				a = c;
 
 				/* Reset state */
 				if (a->flags & OAF_BOUND)
 					apply_lease(iface, a, false);
 
-				memcpy(a->clid_data, clid_data, clid_len);
-				a->clid_len = clid_len;
-				a->iaid = ia->iaid;
-				a->peer = *addr;
 				stop_reconf(a);
 				break;
 			}
 		}
 
+		if (l && a && a->lease != l) {
+			dhcpv6_ia_free_assignment(a);
+			a = NULL;
+		}
+
 		/* Generic message handling */
 		uint16_t status = DHCPV6_STATUS_OK;
 		if (a && a->managed_size < 0)
@@ -1278,34 +1245,52 @@ ssize_t dhcpv6_ia_handle_IAs(uint8_t *buf, size_t buflen, struct interface *ifac
 				(hdr->msg_type == DHCPV6_MSG_REBIND && !a)) {
 			bool assigned = !!a;
 
-			if (!a && !iface->no_dynamic_dhcp && (iface->dhcpv6_pd || iface->dhcpv6_na)) {
-				/* Create new binding */
-				a = calloc(1, sizeof(*a) + clid_len);
-				if (a) {
-					a->clid_len = clid_len;
-					a->iaid = ia->iaid;
-					a->length = reqlen;
-					a->peer = *addr;
-					a->assigned = reqhint;
-					/* Set valid time to current time indicating  */
-					/* assignment is not having infinite lifetime */
-					a->valid_until = now;
-					a->iface = iface;
-
-					if (first)
-						memcpy(a->key, first->key, sizeof(a->key));
-					else
-						odhcpd_urandom(a->key, sizeof(a->key));
-					memcpy(a->clid_data, clid_data, clid_len);
-
-					if (is_pd && iface->dhcpv6_pd)
-						while (!(assigned = assign_pd(iface, a)) &&
-								!a->managed_size && ++a->length <= 64);
-					else if (is_na && iface->dhcpv6_na)
-						assigned = assign_na(iface, a);
-
-					if (a->managed_size && !assigned)
-						return -1;
+			if (!a) {
+				if ((!iface->no_dynamic_dhcp || (l && is_na)) &&
+				    (iface->dhcpv6_pd || iface->dhcpv6_na)) {
+					/* Create new binding */
+					a = calloc(1, sizeof(*a) + clid_len);
+
+					if (a) {
+						a->clid_len = clid_len;
+						memcpy(a->clid_data, clid_data, clid_len);
+						a->iaid = ia->iaid;
+						a->length = reqlen;
+						a->peer = *addr;
+						a->assigned = is_na && l ? l->hostid : reqhint;
+						/* Set valid time to 0 for static lease indicating */
+						/* infinite lifetime otherwise current time        */
+						a->valid_until = l ? 0 : now;
+						a->iface = iface;
+						a->flags = OAF_DHCPV6;
+
+						if (first)
+							memcpy(a->key, first->key, sizeof(a->key));
+						else
+							odhcpd_urandom(a->key, sizeof(a->key));
+
+						if (is_pd && iface->dhcpv6_pd)
+							while (!(assigned = assign_pd(iface, a)) &&
+							       !a->managed_size && ++a->length <= 64);
+						else if (is_na && iface->dhcpv6_na)
+							assigned = assign_na(iface, a);
+
+						if (l && assigned) {
+							a->flags |= OAF_STATIC;
+
+							if (l->hostname)
+								a->hostname = strdup(l->hostname);
+
+							if (l->leasetime)
+								a->leasetime = l->leasetime;
+
+							list_add(&a->lease_list, &l->assignments);
+							a->lease = l;
+						}
+
+						if (a->managed_size && !assigned)
+							return -1;
+					}
 				}
 			}
 
@@ -1362,7 +1347,7 @@ ssize_t dhcpv6_ia_handle_IAs(uint8_t *buf, size_t buflen, struct interface *ifac
 				   ((hdr->msg_type == DHCPV6_MSG_SOLICIT && rapid_commit) ||
 				    hdr->msg_type == DHCPV6_MSG_REQUEST ||
 				    hdr->msg_type == DHCPV6_MSG_REBIND)) {
-				if (hostname_len > 0) {
+				if ((!(a->flags & OAF_STATIC) || !a->hostname) && hostname_len > 0) {
 					a->hostname = realloc(a->hostname, hostname_len + 1);
 					if (a->hostname) {
 						memcpy(a->hostname, hostname, hostname_len);
@@ -1380,7 +1365,7 @@ ssize_t dhcpv6_ia_handle_IAs(uint8_t *buf, size_t buflen, struct interface *ifac
 				apply_lease(iface, a, true);
 			} else if (!assigned && a && a->managed_size == 0) {
 				/* Cleanup failed assignment */
-				free_dhcpv6_assignment(a);
+				dhcpv6_ia_free_assignment(a);
 				a = NULL;
 			}
 		} else if (hdr->msg_type == DHCPV6_MSG_RENEW ||
diff --git a/src/odhcpd.h b/src/odhcpd.h
index 8165f76..6524e84 100644
--- a/src/odhcpd.h
+++ b/src/odhcpd.h
@@ -24,6 +24,7 @@
 #include <libubox/uloop.h>
 #include <libubox/avl.h>
 #include <libubox/ustream.h>
+#include <libubox/vlist.h>
 
 // RFC 6106 defines this router advertisement option
 #define ND_OPT_ROUTE_INFO 24
@@ -42,7 +43,7 @@
 
 struct interface;
 struct nl_sock;
-extern struct list_head leases;
+extern struct vlist_tree leases;
 
 struct odhcpd_event {
 	struct uloop_fd uloop;
@@ -127,6 +128,8 @@ enum odhcpd_assignment_flags {
 	OAF_BOUND		= (1 << 1),
 	OAF_STATIC		= (1 << 2),
 	OAF_BROKEN_HOSTNAME	= (1 << 3),
+	OAF_DHCPV4		= (1 << 4),
+	OAF_DHCPV6		= (1 << 5),
 };
 
 struct config {
@@ -139,14 +142,15 @@ struct config {
 
 
 struct lease {
-	struct list_head head;
-	struct in_addr ipaddr;
+	struct vlist_node node;
+	struct list_head assignments;
+	uint32_t ipaddr;
 	uint32_t hostid;
 	struct ether_addr mac;
 	uint16_t duid_len;
 	uint8_t *duid;
-	uint32_t dhcpv4_leasetime;
-	char hostname[];
+	uint32_t leasetime;
+	char *hostname;
 };
 
 
@@ -154,7 +158,10 @@ struct odhcpd_ref_ip;
 
 struct dhcp_assignment {
 	struct list_head head;
+	struct list_head lease_list;
+
 	struct interface *iface;
+	struct lease *lease;
 
 	struct sockaddr_in6 peer;
 	time_t valid_until;
@@ -183,7 +190,7 @@ struct dhcp_assignment {
 #define hwaddr		mac
 	uint8_t mac[6];
 
-	uint8_t clid_len;
+	uint16_t clid_len;
 	uint8_t clid_data[];
 };
 
@@ -326,6 +333,10 @@ bool odhcpd_bitlen2netmask(bool v6, unsigned int bits, void *mask);
 bool odhcpd_valid_hostname(const char *name);
 
 int config_parse_interface(void *data, size_t len, const char *iname, bool overwrite);
+struct lease *config_find_lease_by_duid(const uint8_t *duid, const uint16_t len);
+struct lease *config_find_lease_by_mac(const uint8_t *mac);
+struct lease *config_find_lease_by_hostid(const uint32_t hostid);
+struct lease *config_find_lease_by_ipaddr(const uint32_t ipaddr);
 
 #ifdef WITH_UBUS
 int ubus_init(void);
@@ -336,6 +347,8 @@ void ubus_bcast_dhcp_event(const char *type, const uint8_t *mac, const size_t ma
 		const struct in_addr *addr, const char *name, const char *interface);
 #endif
 
+void dhcpv4_free_assignment(struct dhcp_assignment *a);
+
 ssize_t dhcpv6_ia_handle_IAs(uint8_t *buf, size_t buflen, struct interface *iface,
 		const struct sockaddr_in6 *addr, const void *data, const uint8_t *end);
 int dhcpv6_ia_init(void);
@@ -343,6 +356,7 @@ int dhcpv6_ia_setup_interface(struct interface *iface, bool enable);
 void dhcpv6_ia_enum_addrs(struct interface *iface, struct dhcp_assignment *c, time_t now,
 				dhcpv6_binding_cb_handler_t func, void *arg);
 void dhcpv6_ia_write_statefile(void);
+void dhcpv6_ia_free_assignment(struct dhcp_assignment *c);
 
 int netlink_add_netevent_handler(struct netevent_handler *hdlr);
 ssize_t netlink_get_interface_addrs(const int ifindex, bool v6,