dhcpv4: use an AVL to store leases

An AVL has O(log n) complexity vs O(n) for a linked list in all the
operations we care about (insertion and search).

Also, it makes the code simpler by not having to care about details like
how to sort the leases.

Signed-off-by: David Härdeman <[email protected]>
Link: https://github.com/openwrt/odhcpd/pull/306
Signed-off-by: Álvaro Fernández Rojas <[email protected]>

diff --git a/src/config.c b/src/config.c
index 055cd5d81a514cf65d546e827af9695f49f64ba2..056dd4768a215f4866a84cbd5f9b16e4e7591cb5 100644 (file)
--- a/src/config.c
+++ b/src/config.c
@@ -1069,6 +1069,11 @@ err:
        return -1;
 }
 
+static int avl_ipv4_cmp(const void *k1, const void *k2, _unused void *ptr)
+{
+       return memcmp(k1, k2, sizeof(struct in_addr));
+}
+
 int config_parse_interface(void *data, size_t len, const char *name, bool overwrite)
 {
        struct odhcpd_ipaddr *addrs = NULL;
@@ -1103,7 +1108,7 @@ int config_parse_interface(void *data, size_t len, const char *name, bool overwr
                iface->ndp_ping_fd = -1;
                iface->dhcpv4_event.uloop.fd = -1;
                INIT_LIST_HEAD(&iface->ia_assignments);
-               INIT_LIST_HEAD(&iface->dhcpv4_leases);
+               avl_init(&iface->dhcpv4_leases, avl_ipv4_cmp, false, iface);
                INIT_LIST_HEAD(&iface->dhcpv4_fr_ips);
 
                set_interface_defaults(iface);

diff --git a/src/dhcpv4.c b/src/dhcpv4.c
index 4c574af64716f6dad5acbaf611ebe5f2899ce2ca..f5db4283fe23cc4fe5f1aedf8cc7fbc84d03ad36 100644 (file)
--- a/src/dhcpv4.c
+++ b/src/dhcpv4.c
@@ -84,7 +84,7 @@ static bool leases_require_fr(struct interface *iface, struct odhcpd_ipaddr *add
        struct dhcpv4_lease *lease = NULL;
        struct odhcpd_ref_ip *fr_ip = NULL;
 
-       list_for_each_entry(lease, &iface->dhcpv4_leases, head) {
+       avl_for_each_element(&iface->dhcpv4_leases, lease, iface_avl) {
                if ((lease->accept_fr_nonce || iface->dhcpv4_forcereconf) &&
                    !lease->fr_ip &&
                    ((lease->addr & mask) == (addr->addr.in.s_addr & mask))) {
@@ -333,13 +333,17 @@ static void dhcpv4_fr_rand_delay(struct dhcpv4_lease *lease)
 
 void dhcpv4_free_lease(struct dhcpv4_lease *lease)
 {
+       if (!lease)
+               return;
+
        if (lease->fr_ip)
                dhcpv4_fr_stop(lease);
 
-       if (lease->iface)
+       if (lease->iface) {
                lease->iface->update_statefile = true;
+               avl_delete(&lease->iface->dhcpv4_leases, &lease->iface_avl);
+       }
 
-       list_del(&lease->head);
        if (lease->lease_cfg)
                lease->lease_cfg->dhcpv4_lease = NULL;
 
@@ -361,8 +365,7 @@ dhcpv4_alloc_lease(struct interface *iface, const uint8_t *hwaddr,
        if (!lease)
                return NULL;
 
-       INIT_LIST_HEAD(&lease->head);
-
+       lease->iface_avl.key = &lease->addr;
        lease->hwaddr_len = hwaddr_len;
        memcpy(lease->hwaddr, hwaddr, hwaddr_len);
        if (duid_len > 0) {
@@ -375,27 +378,14 @@ dhcpv4_alloc_lease(struct interface *iface, const uint8_t *hwaddr,
        return lease;
 }
 
-static bool dhcpv4_insert_lease(struct list_head *list, struct dhcpv4_lease *lease,
+static bool dhcpv4_insert_lease(struct avl_tree *avl, struct dhcpv4_lease *lease,
                                uint32_t addr)
 {
-       uint32_t h_addr = ntohl(addr);
-       struct dhcpv4_lease *c;
-
-       list_for_each_entry(c, list, head) {
-               uint32_t c_addr = ntohl(c->addr);
-
-               if (c_addr == h_addr)
-                       return false;
-
-               if (c_addr > h_addr)
-                       break;
-       }
-
-       /* Insert new node before c (might match list head) */
        lease->addr = addr;
-       list_add_tail(&lease->head, &c->head);
-
-       return true;
+       if (!avl_insert(avl, &lease->iface_avl))
+               return true;
+       else
+               return false;
 }
 
 static bool dhcpv4_assign(struct interface *iface, struct dhcpv4_lease *lease,
@@ -476,7 +466,7 @@ static struct dhcpv4_lease *find_lease_by_hwaddr(struct interface *iface, const
 {
        struct dhcpv4_lease *lease;
 
-       list_for_each_entry(lease, &iface->dhcpv4_leases, head)
+       avl_for_each_element(&iface->dhcpv4_leases, lease, iface_avl)
                if (!memcmp(lease->hwaddr, hwaddr, 6))
                        return lease;
 
@@ -489,7 +479,7 @@ find_lease_by_duid_iaid(struct interface *iface, const uint8_t *duid,
 {
        struct dhcpv4_lease *lease;
 
-       list_for_each_entry(lease, &iface->dhcpv4_leases, head) {
+       avl_for_each_element(&iface->dhcpv4_leases, lease, iface_avl) {
                if (lease->duid_len != duid_len || lease->iaid != iaid)
                        continue;
                if (!memcmp(lease->duid, duid, duid_len))
@@ -594,7 +584,7 @@ dhcpv4_lease(struct interface *iface, enum dhcpv4_msg req_msg, const uint8_t *re
                     (iface->dhcpv4_start_ip.s_addr & iface->dhcpv4_mask.s_addr)) &&
                    !(lease->flags & OAF_STATIC)) {
                        /* Try to reassign to an address that is in-scope */
-                       list_del_init(&lease->head);
+                       avl_delete(&iface->dhcpv4_leases, &lease->iface_avl);
                        lease->addr = INADDR_ANY;
                        if (!dhcpv4_assign(iface, lease, req_addr)) {
                                dhcpv4_free_lease(lease);
@@ -1428,9 +1418,10 @@ int dhcpv4_setup_interface(struct interface *iface, bool enable)
        }
 
        if (!enable || iface->dhcpv4 == MODE_DISABLED) {
-               while (!list_empty(&iface->dhcpv4_leases))
-                       dhcpv4_free_lease(list_first_entry(&iface->dhcpv4_leases,
-                                                          struct dhcpv4_lease, head));
+               struct dhcpv4_lease *lease, *tmp;
+
+               avl_remove_all_elements(&iface->dhcpv4_leases, lease, iface_avl, tmp)
+                       dhcpv4_free_lease(lease);
                return 0;
        }
 
@@ -1541,7 +1532,7 @@ static void dhcpv4_addrlist_change(struct interface *iface)
                return;
        }
 
-       list_for_each_entry(lease, &iface->dhcpv4_leases, head) {
+       avl_for_each_element(&iface->dhcpv4_leases, lease, iface_avl) {
                if ((lease->flags & OAF_BOUND) && lease->fr_ip && !lease->fr_cnt) {
                        if (lease->accept_fr_nonce || iface->dhcpv4_forcereconf)
                                dhcpv4_fr_rand_delay(lease);
@@ -1582,7 +1573,7 @@ static void dhcpv4_valid_until_cb(struct uloop_timeout *event)
                if (iface->dhcpv4 != MODE_SERVER)
                        continue;
 
-               list_for_each_entry_safe(lease, tmp, &iface->dhcpv4_leases, head) {
+               avl_for_each_element_safe(&iface->dhcpv4_leases, lease, iface_avl, tmp) {
                        if (!INFINITE_VALID(lease->valid_until) && lease->valid_until < now) {
                                ubus_bcast_dhcp_event("dhcp.expire", lease->hwaddr,
                                                      (struct in_addr *)&lease->addr,

diff --git a/src/odhcpd.h b/src/odhcpd.h
index 520c27f87d66b585280f10822c87d7a0fa8238db..924fbe20b74127f464efd24b934c8e443a427352 100644 (file)
--- a/src/odhcpd.h
+++ b/src/odhcpd.h
@@ -232,7 +232,7 @@ struct duid {
 struct odhcpd_ref_ip;
 
 struct dhcpv4_lease {
-       struct list_head head;                  // struct interface->dhcpv4_assignments
+       struct avl_node iface_avl;              // struct interface->dhcpv4_leases
 
        struct interface *iface;                // assignment interface, non-null
        struct lease_cfg *lease_cfg;            // host lease cfg, nullable
@@ -367,7 +367,7 @@ struct interface {
 
        // DHCPv4 runtime data
        struct odhcpd_event dhcpv4_event;
-       struct list_head dhcpv4_leases;
+       struct avl_tree dhcpv4_leases;
        struct list_head dhcpv4_fr_ips;
 
        // Services

diff --git a/src/statefiles.c b/src/statefiles.c
index c5f2b57eb15735444261617df0aa1d0363e6b79d..e27a92c872360934dbc06df43332c80e522bdba4 100644 (file)
--- a/src/statefiles.c
+++ b/src/statefiles.c
@@ -139,7 +139,7 @@ static void statefiles_write_hosts(time_t now)
                if (ctxt.iface->dhcpv4 == MODE_SERVER) {
                        struct dhcpv4_lease *lease;
 
-                       list_for_each_entry(lease, &ctxt.iface->dhcpv4_leases, head) {
+                       avl_for_each_element(&ctxt.iface->dhcpv4_leases, lease, iface_avl) {
                                if (!(lease->flags & OAF_BOUND))
                                        continue;
 
@@ -297,7 +297,7 @@ static bool statefiles_write_state(time_t now)
                if (ctxt.iface->dhcpv4 == MODE_SERVER) {
                        struct dhcpv4_lease *lease;
 
-                       list_for_each_entry(lease, &ctxt.iface->dhcpv4_leases, head) {
+                       avl_for_each_element(&ctxt.iface->dhcpv4_leases, lease, iface_avl) {
                                if (!(lease->flags & OAF_BOUND))
                                        continue;
 

diff --git a/src/ubus.c b/src/ubus.c
index 7378f0a9fd673c6e8fb2c2af3d1bd97f29e6ef2c..1301291608d09b9437b3a5e798c0e46cddf12d36 100644 (file)
--- a/src/ubus.c
+++ b/src/ubus.c
@@ -36,9 +36,9 @@ static int handle_dhcpv4_leases(struct ubus_context *ctx, _unused struct ubus_ob
 
                void *i = blobmsg_open_table(&b, iface->ifname);
                void *j = blobmsg_open_array(&b, "leases");
-
                struct dhcpv4_lease *c;
-               list_for_each_entry(c, &iface->dhcpv4_leases, head) {
+
+               avl_for_each_element(&iface->dhcpv4_leases, c, iface_avl) {
                        if (!INFINITE_VALID(c->valid_until) && c->valid_until < now)
                                continue;