Use a separate mutex for cached routes in kernel-netlink plugin
[strongswan.git] / src / libhydra / plugins / kernel_netlink / kernel_netlink_net.c
index 99d750d..4b64a8d 100644 (file)
@@ -53,6 +53,7 @@
 #include <threading/thread.h>
 #include <threading/condvar.h>
 #include <threading/mutex.h>
+#include <threading/spinlock.h>
 #include <utils/hashtable.h>
 #include <utils/linked_list.h>
 #include <processing/jobs/callback_job.h>
 typedef struct addr_entry_t addr_entry_t;
 
 /**
- * IP address in an inface_entry_t
+ * IP address in an iface_entry_t
  */
 struct addr_entry_t {
 
-       /** The ip address */
+       /** the ip address */
        host_t *ip;
 
-       /** virtual IP managed by us */
-       bool virtual;
-
        /** scope of the address */
        u_char scope;
 
-       /** Number of times this IP is used, if virtual */
+       /** number of times this IP is used, if virtual (i.e. managed by us) */
        u_int refcount;
+
+       /** TRUE once it is installed, if virtual */
+       bool installed;
 };
 
 /**
@@ -133,6 +134,14 @@ static bool iface_entry_by_index(iface_entry_t *this, int *ifindex)
 }
 
 /**
+ * find an interface entry by name
+ */
+static bool iface_entry_by_name(iface_entry_t *this, char *ifname)
+{
+       return streq(this->ifname, ifname);
+}
+
+/**
  * check if an interface is up
  */
 static inline bool iface_entry_up(iface_entry_t *iface)
@@ -157,6 +166,9 @@ struct addr_map_entry_t {
        /** The IP address */
        host_t *ip;
 
+       /** The address entry for this IP address */
+       addr_entry_t *addr;
+
        /** The interface this address is installed on */
        iface_entry_t *iface;
 };
@@ -200,6 +212,15 @@ static bool addr_map_entry_match_up(addr_map_entry_t *a, addr_map_entry_t *b)
        return iface_entry_up(b->iface) && a->ip->ip_equals(a->ip, b->ip);
 }
 
+/**
+ * Used with get_match this finds an address entry if it is installed on
+ * any local interface
+ */
+static bool addr_map_entry_match(addr_map_entry_t *a, addr_map_entry_t *b)
+{
+       return a->ip->ip_equals(a->ip, b->ip);
+}
+
 typedef struct route_entry_t route_entry_t;
 
 /**
@@ -338,6 +359,11 @@ struct private_kernel_netlink_net_t {
        hashtable_t *addrs;
 
        /**
+        * Map for virtual IP addresses to iface_entry_t objects (addr_map_entry_t)
+        */
+       hashtable_t *vips;
+
+       /**
         * netlink rt socket (routing)
         */
        netlink_socket_t *socket;
@@ -348,9 +374,14 @@ struct private_kernel_netlink_net_t {
        int socket_events;
 
        /**
-        * time of the last roam event
+        * earliest time of the next roam event
+        */
+       timeval_t next_roam;
+
+       /**
+        * lock to check and update roam event time
         */
-       timeval_t last_roam;
+       spinlock_t *roam_lock;
 
        /**
         * routing table to install routes
@@ -368,6 +399,11 @@ struct private_kernel_netlink_net_t {
        hashtable_t *routes;
 
        /**
+        * mutex for routes
+        */
+       mutex_t *routes_lock;
+
+       /**
         * interface changes which may trigger route reinstallation
         */
        hashtable_t *net_changes;
@@ -393,6 +429,11 @@ struct private_kernel_netlink_net_t {
        bool install_virtual_ip;
 
        /**
+        * the name of the interface virtual IP addresses are installed on
+        */
+       char *install_virtual_ip_on;
+
+       /**
         * whether preferred source addresses can be specified for IPv6 routes
         */
        bool rta_prefsrc_for_ipv6;
@@ -437,7 +478,7 @@ static job_requeue_t reinstall_routes(private_kernel_netlink_net_t *this)
        route_entry_t *route;
 
        this->net_changes_lock->lock(this->net_changes_lock);
-       this->mutex->lock(this->mutex);
+       this->routes_lock->lock(this->routes_lock);
 
        enumerator = this->routes->create_enumerator(this->routes);
        while (enumerator->enumerate(enumerator, NULL, (void**)&route))
@@ -467,7 +508,7 @@ static job_requeue_t reinstall_routes(private_kernel_netlink_net_t *this)
                }
        }
        enumerator->destroy(enumerator);
-       this->mutex->unlock(this->mutex);
+       this->routes_lock->unlock(this->routes_lock);
 
        net_changes_clear(this);
        this->net_changes_lock->unlock(this->net_changes_lock);
@@ -517,78 +558,74 @@ static void queue_route_reinstall(private_kernel_netlink_net_t *this,
 }
 
 /**
- * get the refcount of a virtual ip
+ * check if the given IP is known as virtual IP and currently installed
+ *
+ * this function will also return TRUE if the virtual IP entry disappeared.
+ * in that case the returned entry will be NULL.
+ *
+ * this->mutex must be locked when calling this function
  */
-static int get_vip_refcount(private_kernel_netlink_net_t *this, host_t* ip)
+static bool is_vip_installed_or_gone(private_kernel_netlink_net_t *this,
+                                                                        host_t *ip, addr_map_entry_t **entry)
 {
-       enumerator_t *ifaces, *addrs;
-       iface_entry_t *iface;
-       addr_entry_t *addr;
-       int refcount = 0;
+       addr_map_entry_t lookup = {
+               .ip = ip,
+       };
 
-       ifaces = this->ifaces->create_enumerator(this->ifaces);
-       while (ifaces->enumerate(ifaces, (void**)&iface))
-       {
-               addrs = iface->addrs->create_enumerator(iface->addrs);
-               while (addrs->enumerate(addrs, (void**)&addr))
-               {
-                       if (addr->virtual && (iface->flags & IFF_UP) &&
-                               ip->ip_equals(ip, addr->ip))
-                       {
-                               refcount = addr->refcount;
-                               break;
-                       }
-               }
-               addrs->destroy(addrs);
-               if (refcount)
-               {
-                       break;
-               }
+       *entry = this->vips->get_match(this->vips, &lookup,
+                                                                 (void*)addr_map_entry_match);
+       if (*entry == NULL)
+       {       /* the virtual IP disappeared */
+               return TRUE;
        }
-       ifaces->destroy(ifaces);
+       return (*entry)->addr->installed;
+}
 
-       return refcount;
+/**
+ * check if the given IP is known as virtual IP
+ *
+ * this->mutex must be locked when calling this function
+ */
+static bool is_known_vip(private_kernel_netlink_net_t *this, host_t *ip)
+{
+       addr_map_entry_t lookup = {
+               .ip = ip,
+       };
+
+       return this->vips->get_match(this->vips, &lookup,
+                                                               (void*)addr_map_entry_match) != NULL;
 }
 
 /**
  * Add an address map entry
  */
-static void addr_map_entry_add(private_kernel_netlink_net_t *this,
-                                                          addr_entry_t *addr, iface_entry_t *iface)
+static void addr_map_entry_add(hashtable_t *map, addr_entry_t *addr,
+                                                          iface_entry_t *iface)
 {
        addr_map_entry_t *entry;
 
-       if (addr->virtual)
-       {       /* don't map virtual IPs */
-               return;
-       }
-
        INIT(entry,
                .ip = addr->ip,
+               .addr = addr,
                .iface = iface,
        );
-       entry = this->addrs->put(this->addrs, entry, entry);
+       entry = map->put(map, entry, entry);
        free(entry);
 }
 
 /**
- * Remove an address map entry (the argument order is a bit strange because
- * it is also used with linked_list_t.invoke_function)
+ * Remove an address map entry
  */
-static void addr_map_entry_remove(addr_entry_t *addr, iface_entry_t *iface,
-                                                                 private_kernel_netlink_net_t *this)
+static void addr_map_entry_remove(hashtable_t *map, addr_entry_t *addr,
+                                                                 iface_entry_t *iface)
 {
        addr_map_entry_t *entry, lookup = {
                .ip = addr->ip,
+               .addr = addr,
                .iface = iface,
        };
 
-       if (addr->virtual)
-       {       /* these are never mapped, but this check avoids problems if a
-                * virtual IP equals a regular one */
-               return;
-       }
-       entry = this->addrs->remove(this->addrs, &lookup);
+       entry = map->remove(map, &lookup);
        free(entry);
 }
 
@@ -601,26 +638,22 @@ static void addr_map_entry_remove(addr_entry_t *addr, iface_entry_t *iface,
 static host_t *get_interface_address(private_kernel_netlink_net_t *this,
                                                                         int ifindex, int family, host_t *candidate)
 {
-       enumerator_t *ifaces, *addrs;
        iface_entry_t *iface;
+       enumerator_t *addrs;
        addr_entry_t *addr;
        host_t *ip = NULL;
 
        this->mutex->lock(this->mutex);
-       ifaces = this->ifaces->create_enumerator(this->ifaces);
-       while (ifaces->enumerate(ifaces, &iface))
+       if (this->ifaces->find_first(this->ifaces, (void*)iface_entry_by_index,
+                                                                (void**)&iface, &ifindex) == SUCCESS)
        {
-               if (iface->ifindex == ifindex)
-               {
-                       if (!iface->usable)
-                       {       /* ignore interfaces excluded by config */
-                               break;
-                       }
+               if (iface->usable)
+               {       /* only use interfaces not excluded by config */
                        addrs = iface->addrs->create_enumerator(iface->addrs);
                        while (addrs->enumerate(addrs, &addr))
                        {
-                               if (addr->virtual)
-                               {
+                               if (addr->refcount)
+                               {       /* ignore virtual IP addresses */
                                        continue;
                                }
                                if (addr->ip->get_family(addr->ip) == family)
@@ -639,10 +672,8 @@ static host_t *get_interface_address(private_kernel_netlink_net_t *this,
                                }
                        }
                        addrs->destroy(addrs);
-                       break;
                }
        }
-       ifaces->destroy(ifaces);
        if (ip)
        {
                ip = ip->clone(ip);
@@ -670,25 +701,31 @@ static void fire_roam_event(private_kernel_netlink_net_t *this, bool address)
        job_t *job;
 
        time_monotonic(&now);
-       if (timercmp(&now, &this->last_roam, >))
+       this->roam_lock->lock(this->roam_lock);
+       if (!timercmp(&now, &this->next_roam, >))
        {
-               now.tv_usec += ROAM_DELAY * 1000;
-               while (now.tv_usec > 1000000)
-               {
-                       now.tv_sec++;
-                       now.tv_usec -= 1000000;
-               }
-               this->last_roam = now;
-
-               job = (job_t*)callback_job_create((callback_job_cb_t)roam_event,
-                                                                                 (void*)(uintptr_t)(address ? 1 : 0),
-                                                                                 NULL, NULL);
-               lib->scheduler->schedule_job_ms(lib->scheduler, job, ROAM_DELAY);
+               this->roam_lock->unlock(this->roam_lock);
+               return;
        }
+       now.tv_usec += ROAM_DELAY * 1000;
+       while (now.tv_usec > 1000000)
+       {
+               now.tv_sec++;
+               now.tv_usec -= 1000000;
+       }
+       this->next_roam = now;
+       this->roam_lock->unlock(this->roam_lock);
+
+       job = (job_t*)callback_job_create((callback_job_cb_t)roam_event,
+                                                                         (void*)(uintptr_t)(address ? 1 : 0),
+                                                                          NULL, NULL);
+       lib->scheduler->schedule_job_ms(lib->scheduler, job, ROAM_DELAY);
 }
 
 /**
  * check if an interface with a given index is up and usable
+ *
+ * this->mutex must be locked when calling this function
  */
 static bool is_interface_up_and_usable(private_kernel_netlink_net_t *this,
                                                                           int index)
@@ -704,6 +741,23 @@ static bool is_interface_up_and_usable(private_kernel_netlink_net_t *this,
 }
 
 /**
+ * unregister the current addr_entry_t from the hashtable it is stored in
+ *
+ * this->mutex must be locked when calling this function
+ */
+static void addr_entry_unregister(addr_entry_t *addr, iface_entry_t *iface,
+                                                                 private_kernel_netlink_net_t *this)
+{
+       if (addr->refcount)
+       {
+               addr_map_entry_remove(this->vips, addr, iface);
+               this->condvar->broadcast(this->condvar);
+               return;
+       }
+       addr_map_entry_remove(this->addrs, addr, iface);
+}
+
+/**
  * process RTM_NEWLINK/RTM_DELLINK from kernel
  */
 static void process_link(private_kernel_netlink_net_t *this,
@@ -737,24 +791,16 @@ static void process_link(private_kernel_netlink_net_t *this,
        {
                case RTM_NEWLINK:
                {
-                       enumerator = this->ifaces->create_enumerator(this->ifaces);
-                       while (enumerator->enumerate(enumerator, &current))
+                       if (this->ifaces->find_first(this->ifaces,
+                                                                       (void*)iface_entry_by_index, (void**)&entry,
+                                                                       &msg->ifi_index) != SUCCESS)
                        {
-                               if (current->ifindex == msg->ifi_index)
-                               {
-                                       entry = current;
-                                       break;
-                               }
-                       }
-                       enumerator->destroy(enumerator);
-                       if (!entry)
-                       {
-                               entry = malloc_thing(iface_entry_t);
-                               entry->ifindex = msg->ifi_index;
-                               entry->flags = 0;
-                               entry->usable = hydra->kernel_interface->is_interface_usable(
-                                                                                               hydra->kernel_interface, name);
-                               entry->addrs = linked_list_create();
+                               INIT(entry,
+                                       .ifindex = msg->ifi_index,
+                                       .addrs = linked_list_create(),
+                                       .usable = hydra->kernel_interface->is_interface_usable(
+                                                                                               hydra->kernel_interface, name),
+                               );
                                this->ifaces->insert_last(this->ifaces, entry);
                        }
                        strncpy(entry->ifname, name, IFNAMSIZ);
@@ -787,9 +833,11 @@ static void process_link(private_kernel_netlink_net_t *this,
                                                update = TRUE;
                                                DBG1(DBG_KNL, "interface %s deleted", current->ifname);
                                        }
+                                       /* TODO: move virtual IPs installed on this interface to
+                                        * another interface? */
                                        this->ifaces->remove_at(this->ifaces, enumerator);
                                        current->addrs->invoke_function(current->addrs,
-                                                               (void*)addr_map_entry_remove, current, this);
+                                                               (void*)addr_entry_unregister, current, this);
                                        iface_entry_destroy(current);
                                        break;
                                }
@@ -805,7 +853,6 @@ static void process_link(private_kernel_netlink_net_t *this,
                queue_route_reinstall(this, strdup(name));
        }
 
-       /* send an update to all IKE_SAs */
        if (update && event)
        {
                fire_roam_event(this, TRUE);
@@ -822,9 +869,7 @@ static void process_addr(private_kernel_netlink_net_t *this,
        struct rtattr *rta = IFA_RTA(msg);
        size_t rtasize = IFA_PAYLOAD (hdr);
        host_t *host = NULL;
-       enumerator_t *ifaces, *addrs;
        iface_entry_t *iface;
-       addr_entry_t *addr;
        chunk_t local = chunk_empty, address = chunk_empty;
        char *route_ifname = NULL;
        bool update = FALSE, found = FALSE, changed = FALSE;
@@ -863,70 +908,81 @@ static void process_addr(private_kernel_netlink_net_t *this,
        }
 
        this->mutex->lock(this->mutex);
-       ifaces = this->ifaces->create_enumerator(this->ifaces);
-       while (ifaces->enumerate(ifaces, &iface))
+       if (this->ifaces->find_first(this->ifaces, (void*)iface_entry_by_index,
+                                                                (void**)&iface, &msg->ifa_index) == SUCCESS)
        {
-               if (iface->ifindex == msg->ifa_index)
+               addr_map_entry_t *entry, lookup = {
+                       .ip = host,
+                       .iface = iface,
+               };
+               addr_entry_t *addr;
+
+               entry = this->vips->get(this->vips, &lookup);
+               if (entry)
                {
-                       addrs = iface->addrs->create_enumerator(iface->addrs);
-                       while (addrs->enumerate(addrs, &addr))
+                       if (hdr->nlmsg_type == RTM_NEWADDR)
+                       {       /* mark as installed and signal waiting threads */
+                               entry->addr->installed = TRUE;
+                       }
+                       else
+                       {       /* the address was already marked as uninstalled */
+                               addr = entry->addr;
+                               iface->addrs->remove(iface->addrs, addr, NULL);
+                               addr_map_entry_remove(this->vips, addr, iface);
+                               addr_entry_destroy(addr);
+                       }
+                       /* no roam events etc. for virtual IPs */
+                       this->condvar->broadcast(this->condvar);
+                       this->mutex->unlock(this->mutex);
+                       host->destroy(host);
+                       return;
+               }
+               entry = this->addrs->get(this->addrs, &lookup);
+               if (entry)
+               {
+                       if (hdr->nlmsg_type == RTM_DELADDR)
                        {
-                               if (host->ip_equals(host, addr->ip))
+                               found = TRUE;
+                               addr = entry->addr;
+                               iface->addrs->remove(iface->addrs, addr, NULL);
+                               if (iface->usable)
                                {
-                                       found = TRUE;
-                                       if (hdr->nlmsg_type == RTM_DELADDR)
-                                       {
-                                               iface->addrs->remove_at(iface->addrs, addrs);
-                                               if (!addr->virtual && iface->usable)
-                                               {
-                                                       changed = TRUE;
-                                                       DBG1(DBG_KNL, "%H disappeared from %s",
-                                                                host, iface->ifname);
-                                               }
-                                               addr_map_entry_remove(addr, iface, this);
-                                               addr_entry_destroy(addr);
-                                       }
-                                       else if (hdr->nlmsg_type == RTM_NEWADDR && addr->virtual)
-                                       {
-                                               addr->refcount = 1;
-                                       }
+                                       changed = TRUE;
+                                       DBG1(DBG_KNL, "%H disappeared from %s", host,
+                                                iface->ifname);
                                }
+                               addr_map_entry_remove(this->addrs, addr, iface);
+                               addr_entry_destroy(addr);
                        }
-                       addrs->destroy(addrs);
-
+               }
+               else
+               {
                        if (hdr->nlmsg_type == RTM_NEWADDR)
                        {
-                               if (!found)
+                               found = TRUE;
+                               changed = TRUE;
+                               route_ifname = strdup(iface->ifname);
+                               INIT(addr,
+                                       .ip = host->clone(host),
+                                       .scope = msg->ifa_scope,
+                               );
+                               iface->addrs->insert_last(iface->addrs, addr);
+                               addr_map_entry_add(this->addrs, addr, iface);
+                               if (event && iface->usable)
                                {
-                                       found = TRUE;
-                                       changed = TRUE;
-                                       route_ifname = strdup(iface->ifname);
-                                       addr = malloc_thing(addr_entry_t);
-                                       addr->ip = host->clone(host);
-                                       addr->virtual = FALSE;
-                                       addr->refcount = 1;
-                                       addr->scope = msg->ifa_scope;
-
-                                       iface->addrs->insert_last(iface->addrs, addr);
-                                       addr_map_entry_add(this, addr, iface);
-                                       if (event && iface->usable)
-                                       {
-                                               DBG1(DBG_KNL, "%H appeared on %s", host, iface->ifname);
-                                       }
+                                       DBG1(DBG_KNL, "%H appeared on %s", host, iface->ifname);
                                }
                        }
-                       if (found && (iface->flags & IFF_UP))
-                       {
-                               update = TRUE;
-                       }
-                       if (!iface->usable)
-                       {       /* ignore events for interfaces excluded by config */
-                               update = changed = FALSE;
-                       }
-                       break;
+               }
+               if (found && (iface->flags & IFF_UP))
+               {
+                       update = TRUE;
+               }
+               if (!iface->usable)
+               {       /* ignore events for interfaces excluded by config */
+                       update = changed = FALSE;
                }
        }
-       ifaces->destroy(ifaces);
        this->mutex->unlock(this->mutex);
 
        if (update && event && route_ifname)
@@ -999,7 +1055,7 @@ static void process_route(private_kernel_netlink_net_t *this, struct nlmsghdr *h
        }
        if (host)
        {
-               if (!get_vip_refcount(this, host))
+               if (!is_known_vip(this, host))
                {       /* ignore routes added for virtual IPs */
                        fire_roam_event(this, FALSE);
                }
@@ -1055,12 +1111,10 @@ static job_requeue_t receive_events(private_kernel_netlink_net_t *this)
                        case RTM_NEWADDR:
                        case RTM_DELADDR:
                                process_addr(this, hdr, TRUE);
-                               this->condvar->broadcast(this->condvar);
                                break;
                        case RTM_NEWLINK:
                        case RTM_DELLINK:
                                process_link(this, hdr, TRUE);
-                               this->condvar->broadcast(this->condvar);
                                break;
                        case RTM_NEWROUTE:
                        case RTM_DELROUTE:
@@ -1099,7 +1153,7 @@ static void address_enumerator_destroy(address_enumerator_t *data)
 static bool filter_addresses(address_enumerator_t *data,
                                                         addr_entry_t** in, host_t** out)
 {
-       if (!(data->which & ADDR_TYPE_VIRTUAL) && (*in)->virtual)
+       if (!(data->which & ADDR_TYPE_VIRTUAL) && (*in)->refcount)
        {       /* skip virtual interfaces added by us */
                return FALSE;
        }
@@ -1201,23 +1255,17 @@ METHOD(kernel_net_t, get_interface_name, bool,
  */
 static int get_interface_index(private_kernel_netlink_net_t *this, char* name)
 {
-       enumerator_t *ifaces;
        iface_entry_t *iface;
        int ifindex = 0;
 
        DBG2(DBG_KNL, "getting iface index for %s", name);
 
        this->mutex->lock(this->mutex);
-       ifaces = this->ifaces->create_enumerator(this->ifaces);
-       while (ifaces->enumerate(ifaces, &iface))
+       if (this->ifaces->find_first(this->ifaces, (void*)iface_entry_by_name,
+                                                               (void**)&iface, name) == SUCCESS)
        {
-               if (streq(name, iface->ifname))
-               {
-                       ifindex = iface->ifindex;
-                       break;
-               }
+               ifindex = iface->ifindex;
        }
-       ifaces->destroy(ifaces);
        this->mutex->unlock(this->mutex);
 
        if (ifindex == 0)
@@ -1437,7 +1485,7 @@ static host_t *get_route(private_kernel_netlink_net_t *this, host_t *dest,
                                {       /* verify source address, if any */
                                        host_t *src = host_create_from_chunk(msg->rtm_family,
                                                                                                                 route->src, 0);
-                                       if (src && get_vip_refcount(this, src))
+                                       if (src && is_known_vip(this, src))
                                        {       /* ignore routes installed by us */
                                                src->destroy(src);
                                                continue;
@@ -1618,87 +1666,109 @@ static status_t manage_ipaddr(private_kernel_netlink_net_t *this, int nlmsg_type
 METHOD(kernel_net_t, add_ip, status_t,
        private_kernel_netlink_net_t *this, host_t *virtual_ip, host_t *iface_ip)
 {
-       iface_entry_t *iface;
-       addr_entry_t *addr;
-       enumerator_t *addrs, *ifaces;
-       int ifindex;
+       addr_map_entry_t *entry, lookup = {
+               .ip = virtual_ip,
+       };
+       iface_entry_t *iface = NULL;
 
        if (!this->install_virtual_ip)
        {       /* disabled by config */
                return SUCCESS;
        }
 
-       DBG2(DBG_KNL, "adding virtual IP %H", virtual_ip);
-
        this->mutex->lock(this->mutex);
-       ifaces = this->ifaces->create_enumerator(this->ifaces);
-       while (ifaces->enumerate(ifaces, &iface))
-       {
-               bool iface_found = FALSE;
-
-               addrs = iface->addrs->create_enumerator(iface->addrs);
-               while (addrs->enumerate(addrs, &addr))
-               {
-                       if (iface_ip->ip_equals(iface_ip, addr->ip))
+       /* the virtual IP might actually be installed as regular IP, in which case
+        * we don't track it as virtual IP */
+       entry = this->addrs->get_match(this->addrs, &lookup,
+                                                                 (void*)addr_map_entry_match);
+       if (!entry)
+       {       /* otherwise it might already be installed as virtual IP */
+               entry = this->vips->get_match(this->vips, &lookup,
+                                                                        (void*)addr_map_entry_match);
+               if (entry)
+               {       /* the vip we found can be in one of three states: 1) installed and
+                        * ready, 2) just added by another thread, but not yet confirmed to
+                        * be installed by the kernel, 3) just deleted, but not yet gone.
+                        * Then while we wait below, several things could happen (as we
+                        * release the mutex).  For instance, the interface could disappear,
+                        * or the IP is finally deleted, and it reappears on a different
+                        * interface. All these cases are handled by the call below. */
+                       while (!is_vip_installed_or_gone(this, virtual_ip, &entry))
                        {
-                               iface_found = TRUE;
+                               this->condvar->wait(this->condvar, this->mutex);
                        }
-                       else if (virtual_ip->ip_equals(virtual_ip, addr->ip))
+                       if (entry)
                        {
-                               addr->refcount++;
-                               DBG2(DBG_KNL, "virtual IP %H already installed on %s",
-                                        virtual_ip, iface->ifname);
-                               addrs->destroy(addrs);
-                               ifaces->destroy(ifaces);
-                               this->mutex->unlock(this->mutex);
-                               return SUCCESS;
+                               entry->addr->refcount++;
                        }
                }
-               addrs->destroy(addrs);
+       }
+       if (entry)
+       {
+               DBG2(DBG_KNL, "virtual IP %H is already installed on %s", virtual_ip,
+                        entry->iface->ifname);
+               this->mutex->unlock(this->mutex);
+               return SUCCESS;
+       }
+       /* try to find the target interface, either by config or via src ip */
+       if (!this->install_virtual_ip_on ||
+                this->ifaces->find_first(this->ifaces, (void*)iface_entry_by_name,
+                                               (void**)&iface, this->install_virtual_ip_on) != SUCCESS)
+       {
+               lookup.ip = iface_ip;
+               entry = this->addrs->get_match(this->addrs, &lookup,
+                                                                         (void*)addr_map_entry_match);
+               if (!entry)
+               {       /* if we don't find the requested interface we just use the first */
+                       this->ifaces->get_first(this->ifaces, (void**)&iface);
+               }
+               else
+               {
+                       iface = entry->iface;
+               }
+       }
+       if (iface)
+       {
+               addr_entry_t *addr;
 
-               if (iface_found)
+               INIT(addr,
+                       .ip = virtual_ip->clone(virtual_ip),
+                       .refcount = 1,
+                       .scope = RT_SCOPE_UNIVERSE,
+               );
+               iface->addrs->insert_last(iface->addrs, addr);
+               addr_map_entry_add(this->vips, addr, iface);
+               if (manage_ipaddr(this, RTM_NEWADDR, NLM_F_CREATE | NLM_F_EXCL,
+                                                 iface->ifindex, virtual_ip) == SUCCESS)
                {
-                       ifindex = iface->ifindex;
-                       addr = malloc_thing(addr_entry_t);
-                       addr->ip = virtual_ip->clone(virtual_ip);
-                       addr->refcount = 0;
-                       addr->virtual = TRUE;
-                       addr->scope = RT_SCOPE_UNIVERSE;
-                       iface->addrs->insert_last(iface->addrs, addr);
-
-                       if (manage_ipaddr(this, RTM_NEWADDR, NLM_F_CREATE | NLM_F_EXCL,
-                                                         ifindex, virtual_ip) == SUCCESS)
-                       {
-                               while (get_vip_refcount(this, virtual_ip) == 0)
-                               {       /* wait until address appears */
-                                       this->condvar->wait(this->condvar, this->mutex);
-                               }
-                               ifaces->destroy(ifaces);
+                       while (!is_vip_installed_or_gone(this, virtual_ip, &entry))
+                       {       /* wait until address appears */
+                               this->condvar->wait(this->condvar, this->mutex);
+                       }
+                       if (entry)
+                       {       /* we fail if the interface got deleted in the meantime */
+                               DBG2(DBG_KNL, "virtual IP %H installed on %s", virtual_ip,
+                                        entry->iface->ifname);
                                this->mutex->unlock(this->mutex);
                                return SUCCESS;
                        }
-                       ifaces->destroy(ifaces);
-                       this->mutex->unlock(this->mutex);
-                       DBG1(DBG_KNL, "adding virtual IP %H failed", virtual_ip);
-                       return FAILED;
                }
+               this->mutex->unlock(this->mutex);
+               DBG1(DBG_KNL, "adding virtual IP %H failed", virtual_ip);
+               return FAILED;
        }
-       ifaces->destroy(ifaces);
        this->mutex->unlock(this->mutex);
-
-       DBG1(DBG_KNL, "interface address %H not found, unable to install"
-                "virtual IP %H", iface_ip, virtual_ip);
+       DBG1(DBG_KNL, "no interface available, unable to install virtual IP %H",
+                virtual_ip);
        return FAILED;
 }
 
 METHOD(kernel_net_t, del_ip, status_t,
        private_kernel_netlink_net_t *this, host_t *virtual_ip)
 {
-       iface_entry_t *iface;
-       addr_entry_t *addr;
-       enumerator_t *addrs, *ifaces;
-       status_t status;
-       int ifindex;
+       addr_map_entry_t *entry, lookup = {
+               .ip = virtual_ip,
+       };
 
        if (!this->install_virtual_ip)
        {       /* disabled by config */
@@ -1708,50 +1778,50 @@ METHOD(kernel_net_t, del_ip, status_t,
        DBG2(DBG_KNL, "deleting virtual IP %H", virtual_ip);
 
        this->mutex->lock(this->mutex);
-       ifaces = this->ifaces->create_enumerator(this->ifaces);
-       while (ifaces->enumerate(ifaces, &iface))
-       {
-               addrs = iface->addrs->create_enumerator(iface->addrs);
-               while (addrs->enumerate(addrs, &addr))
+       entry = this->vips->get_match(this->vips, &lookup,
+                                                                (void*)addr_map_entry_match);
+       if (!entry)
+       {       /* we didn't install this IP as virtual IP */
+               entry = this->addrs->get_match(this->addrs, &lookup,
+                                                                         (void*)addr_map_entry_match);
+               if (entry)
                {
-                       if (virtual_ip->ip_equals(virtual_ip, addr->ip))
+                       DBG2(DBG_KNL, "not deleting existing IP %H on %s", virtual_ip,
+                                entry->iface->ifname);
+                       this->mutex->unlock(this->mutex);
+                       return SUCCESS;
+               }
+               DBG2(DBG_KNL, "virtual IP %H not cached, unable to delete", virtual_ip);
+               this->mutex->unlock(this->mutex);
+               return FAILED;
+       }
+       if (entry->addr->refcount == 1)
+       {
+               status_t status;
+
+               /* we set this flag so that threads calling add_ip will block and wait
+                * until the entry is gone, also so we can wait below */
+               entry->addr->installed = FALSE;
+               status = manage_ipaddr(this, RTM_DELADDR, 0, entry->iface->ifindex,
+                                                          virtual_ip);
+               if (status == SUCCESS)
+               {       /* wait until the address is really gone */
+                       while (is_known_vip(this, virtual_ip))
                        {
-                               ifindex = iface->ifindex;
-                               if (addr->refcount == 1)
-                               {
-                                       status = manage_ipaddr(this, RTM_DELADDR, 0,
-                                                                                  ifindex, virtual_ip);
-                                       if (status == SUCCESS)
-                                       {       /* wait until the address is really gone */
-                                               while (get_vip_refcount(this, virtual_ip) > 0)
-                                               {
-                                                       this->condvar->wait(this->condvar, this->mutex);
-                                               }
-                                       }
-                                       addrs->destroy(addrs);
-                                       ifaces->destroy(ifaces);
-                                       this->mutex->unlock(this->mutex);
-                                       return status;
-                               }
-                               else
-                               {
-                                       addr->refcount--;
-                               }
-                               DBG2(DBG_KNL, "virtual IP %H used by other SAs, not deleting",
-                                        virtual_ip);
-                               addrs->destroy(addrs);
-                               ifaces->destroy(ifaces);
-                               this->mutex->unlock(this->mutex);
-                               return SUCCESS;
+                               this->condvar->wait(this->condvar, this->mutex);
                        }
                }
-               addrs->destroy(addrs);
+               this->mutex->unlock(this->mutex);
+               return status;
        }
-       ifaces->destroy(ifaces);
+       else
+       {
+               entry->addr->refcount--;
+       }
+       DBG2(DBG_KNL, "virtual IP %H used by other SAs, not deleting",
+                virtual_ip);
        this->mutex->unlock(this->mutex);
-
-       DBG2(DBG_KNL, "virtual IP %H not cached, unable to delete", virtual_ip);
-       return FAILED;
+       return SUCCESS;
 }
 
 /**
@@ -1834,18 +1904,18 @@ METHOD(kernel_net_t, add_route, status_t,
                .if_name = if_name,
        };
 
-       this->mutex->lock(this->mutex);
+       this->routes_lock->lock(this->routes_lock);
        found = this->routes->get(this->routes, &route);
        if (found)
        {
-               this->mutex->unlock(this->mutex);
+               this->routes_lock->unlock(this->routes_lock);
                return ALREADY_DONE;
        }
        found = route_entry_clone(&route);
        this->routes->put(this->routes, found, found);
        status = manage_srcroute(this, RTM_NEWROUTE, NLM_F_CREATE | NLM_F_EXCL,
                                                         dst_net, prefixlen, gateway, src_ip, if_name);
-       this->mutex->unlock(this->mutex);
+       this->routes_lock->unlock(this->routes_lock);
        return status;
 }
 
@@ -1862,18 +1932,18 @@ METHOD(kernel_net_t, del_route, status_t,
                .if_name = if_name,
        };
 
-       this->mutex->lock(this->mutex);
+       this->routes_lock->lock(this->routes_lock);
        found = this->routes->get(this->routes, &route);
        if (!found)
        {
-               this->mutex->unlock(this->mutex);
+               this->routes_lock->unlock(this->routes_lock);
                return NOT_FOUND;
        }
        this->routes->remove(this->routes, found);
        route_entry_destroy(found);
        status = manage_srcroute(this, RTM_DELROUTE, 0, dst_net, prefixlen,
                                                         gateway, src_ip, if_name);
-       this->mutex->unlock(this->mutex);
+       this->routes_lock->unlock(this->routes_lock);
        return status;
 }
 
@@ -2032,12 +2102,28 @@ static void check_kernel_features(private_kernel_netlink_net_t *this)
        }
 }
 
+/**
+ * Destroy an address to iface map
+ */
+static void addr_map_destroy(hashtable_t *map)
+{
+       enumerator_t *enumerator;
+       addr_map_entry_t *addr;
+
+       enumerator = map->create_enumerator(map);
+       while (enumerator->enumerate(enumerator, NULL, (void**)&addr))
+       {
+               free(addr);
+       }
+       enumerator->destroy(enumerator);
+       map->destroy(map);
+}
+
 METHOD(kernel_net_t, destroy, void,
        private_kernel_netlink_net_t *this)
 {
        enumerator_t *enumerator;
        route_entry_t *route;
-       addr_map_entry_t *addr;
 
        if (this->routing_table)
        {
@@ -2059,22 +2145,19 @@ METHOD(kernel_net_t, destroy, void,
        }
        enumerator->destroy(enumerator);
        this->routes->destroy(this->routes);
+       this->routes_lock->destroy(this->routes_lock);
        DESTROY_IF(this->socket);
 
        net_changes_clear(this);
        this->net_changes->destroy(this->net_changes);
        this->net_changes_lock->destroy(this->net_changes_lock);
 
-       enumerator = this->addrs->create_enumerator(this->addrs);
-       while (enumerator->enumerate(enumerator, NULL, (void**)&addr))
-       {
-               free(addr);
-       }
-       enumerator->destroy(enumerator);
-       this->addrs->destroy(this->addrs);
+       addr_map_destroy(this->addrs);
+       addr_map_destroy(this->vips);
 
        this->ifaces->destroy_function(this->ifaces, (void*)iface_entry_destroy);
        this->rt_exclude->destroy(this->rt_exclude);
+       this->roam_lock->destroy(this->roam_lock);
        this->condvar->destroy(this->condvar);
        this->mutex->destroy(this->mutex);
        free(this);
@@ -2114,10 +2197,14 @@ kernel_netlink_net_t *kernel_netlink_net_create()
                .addrs = hashtable_create(
                                                                (hashtable_hash_t)addr_map_entry_hash,
                                                                (hashtable_equals_t)addr_map_entry_equals, 16),
+               .vips = hashtable_create((hashtable_hash_t)addr_map_entry_hash,
+                                                                (hashtable_equals_t)addr_map_entry_equals, 16),
+               .routes_lock = mutex_create(MUTEX_TYPE_DEFAULT),
                .net_changes_lock = mutex_create(MUTEX_TYPE_DEFAULT),
                .ifaces = linked_list_create(),
                .mutex = mutex_create(MUTEX_TYPE_RECURSIVE),
                .condvar = condvar_create(CONDVAR_TYPE_DEFAULT),
+               .roam_lock = spinlock_create(),
                .routing_table = lib->settings->get_int(lib->settings,
                                "%s.routing_table", ROUTING_TABLE, hydra->daemon),
                .routing_table_prio = lib->settings->get_int(lib->settings,
@@ -2126,9 +2213,11 @@ kernel_netlink_net_t *kernel_netlink_net_create()
                                "%s.process_route", TRUE, hydra->daemon),
                .install_virtual_ip = lib->settings->get_bool(lib->settings,
                                "%s.install_virtual_ip", TRUE, hydra->daemon),
+               .install_virtual_ip_on = lib->settings->get_str(lib->settings,
+                               "%s.install_virtual_ip_on", NULL, hydra->daemon),
        );
        timerclear(&this->last_route_reinstall);
-       timerclear(&this->last_roam);
+       timerclear(&this->next_roam);
 
        check_kernel_features(this);