Nest: Neighbor cache cleanups

Simplify neighbor cache code, fix several minor bugs, and improve
handling of ONLINK flag.

filter/filter.c

@@ -974,7 +974,7 @@ interpret(struct f_inst *what)
       case SA_GW:
 	{
 	  ip_addr ip = v1.val.ip;
-	  neighbor *n = neigh_find(rta->src->proto, &ip, 0);
+	  neighbor *n = neigh_find(rta->src->proto, ip, NULL, 0);
 	  if (!n || (n->scope == SCOPE_HOST))
 	    runtime( "Invalid gw address" );
 

lib/hash.h

@@ -230,4 +230,11 @@ mem_hash(void *p, uint s)
   return mem_hash_value(&h);
 }
 
+static inline uint
+ptr_hash(void *ptr)
+{
+  uintptr_t p = (uintptr_t) ptr;
+  return p ^ (p << 8) ^ (p >> 16);
+}
+
 #endif

nest/iface.h

@@ -124,29 +124,21 @@ typedef struct neighbor {
   ip_addr addr;				/* Address of the neighbor */
   struct ifa *ifa;			/* Ifa on related iface */
   struct iface *iface;			/* Interface it's connected to */
+  struct iface *ifreq;			/* Requested iface, NULL for any */
   struct proto *proto;			/* Protocol this belongs to */
   void *data;				/* Protocol-specific data */
-  unsigned aux;				/* Protocol-specific data */
+  uint aux;				/* Protocol-specific data */
-  unsigned flags;
+  u16 flags;				/* NEF_* flags */
-  int scope;				/* Address scope, -1 for unreachable sticky neighbors,
+  s16 scope;				/* Address scope, -1 for unreachable neighbors,
 					   SCOPE_HOST when it's our own address */
 } neighbor;
 
 #define NEF_STICKY	1
 #define NEF_ONLINK	2
-#define NEF_BIND	4		/* Used internally for neighbors bound to an iface */
+#define NEF_IFACE	4		/* Entry for whole iface */
-#define NEF_IFACE	8		/* Neighbors bound to iface */
 
 
-neighbor *neigh_find(struct proto *, ip_addr *, unsigned flags);
+neighbor *neigh_find(struct proto *p, ip_addr a, struct iface *ifa, uint flags);
-neighbor *neigh_find2(struct proto *p, ip_addr *a, struct iface *ifa, unsigned flags);
-neighbor *neigh_find_iface(struct proto *p, struct iface *ifa);
-
-static inline int neigh_connected_to(struct proto *p, ip_addr *a, struct iface *i)
-{
-  neighbor *n = neigh_find(p, a, 0);
-  return n && n->iface == i;
-}
 
 void neigh_dump(neighbor *);
 void neigh_dump_all(void);

nest/neighbor.c

@@ -2,6 +2,8 @@
  *	BIRD -- Neighbor Cache
  *
  *	(c) 1998--2000 Martin Mares <mj@ucw.cz>
+ *	(c) 2008--2018 Ondrej Zajicek <santiago@crfreenet.org>
+ *	(c) 2008--2018 CZ.NIC z.s.p.o.
  *
  *	Can be freely distributed and used under the terms of the GNU GPL.
  */
@@ -10,32 +12,38 @@
  * DOC: Neighbor cache
  *
  * Most routing protocols need to associate their internal state data with
- * neighboring routers, check whether an address given as the next hop
+ * neighboring routers, check whether an address given as the next hop attribute
- * attribute of a route is really an address of a directly connected host
+ * of a route is really an address of a directly connected host and which
- * and which interface is it connected through. Also, they often need to
+ * interface is it connected through. Also, they often need to be notified when
- * be notified when a neighbor ceases to exist or when their long awaited
+ * a neighbor ceases to exist or when their long awaited neighbor becomes
- * neighbor becomes connected. The neighbor cache is there to solve all
+ * connected. The neighbor cache is there to solve all these problems.
- * these problems.
  *
- * The neighbor cache maintains a collection of neighbor entries. Each
+ * The neighbor cache maintains a collection of neighbor entries. Each entry
- * entry represents one IP address corresponding to either our directly
+ * represents one IP address corresponding to either our directly connected
- * connected neighbor or our own end of the link (when the scope of the
+ * neighbor or our own end of the link (when the scope of the address is set to
- * address is set to %SCOPE_HOST) together with per-neighbor data belonging to a
+ * %SCOPE_HOST) together with per-neighbor data belonging to a single protocol.
- * single protocol.
+ * A neighbor entry may be bound to a specific interface, which is required for
+ * link-local IP addresses and optional for global IP addresses.
  *
- * Active entries represent known neighbors and are stored in a hash
+ * Neighbor cache entries are stored in a hash table, which is indexed by triple
- * table (to allow fast retrieval based on the IP address of the node) and
+ * (protocol, IP, requested-iface), so if both regular and iface-bound neighbors
- * two linked lists: one global and one per-interface (allowing quick
+ * are requested, they are represented by two neighbor cache entries. Active
- * processing of interface change events). Inactive entries exist only
+ * entries are also linked in per-interface list (allowing quick processing of
- * when the protocol has explicitly requested it via the %NEF_STICKY
+ * interface change events). Inactive entries exist only when the protocol has
- * flag because it wishes to be notified when the node will again become
+ * explicitly requested it via the %NEF_STICKY flag because it wishes to be
- * a neighbor. Such entries are enqueued in a special list which is walked
+ * notified when the node will again become a neighbor. Such entries are instead
- * whenever an interface changes its state to up. Neighbor entry VRF
+ * linked in a special list, which is walked whenever an interface changes its
- * association is implied by respective protocol.
+ * state to up. Neighbor entry VRF association is implied by respective
+ * protocol.
+ *
+ * Besides the already mentioned %NEF_STICKY flag, there is also %NEF_ONLINK,
+ * which specifies that neighbor should be considered reachable on given iface
+ * regardless of associated address ranges, and %NEF_IFACE, which represents
+ * pseudo-neighbor entry for whole interface (and uses %IPA_NONE IP address).
  *
  * When a neighbor event occurs (a neighbor gets disconnected or a sticky
- * inactive neighbor becomes connected), the protocol hook neigh_notify()
+ * inactive neighbor becomes connected), the protocol hook neigh_notify() is
- * is called to advertise the change.
+ * called to advertise the change.
  */
 
 #undef LOCAL_DEBUG
@@ -43,126 +51,151 @@
 #include "nest/bird.h"
 #include "nest/iface.h"
 #include "nest/protocol.h"
+#include "lib/hash.h"
 #include "lib/resource.h"
 
 #define NEIGH_HASH_SIZE 256
 #define NEIGH_HASH_OFFSET 24
 
 static slab *neigh_slab;
-static list sticky_neigh_list, iface_neigh_list, neigh_hash_table[NEIGH_HASH_SIZE];
+static list neigh_hash_table[NEIGH_HASH_SIZE], sticky_neigh_list;
 
 static inline uint
-neigh_hash(struct proto *p, ip_addr *a)
+neigh_hash(struct proto *p, ip_addr a, struct iface *i)
 {
-  return (p->hash_key ^ ipa_hash(*a)) >> NEIGH_HASH_OFFSET;
+  return (p->hash_key ^ ipa_hash(a) ^ ptr_hash(i)) >> NEIGH_HASH_OFFSET;
 }
 
 static int
-if_connected(ip_addr *a, struct iface *i, struct ifa **ap)
+if_connected(ip_addr a, struct iface *i, struct ifa **ap, uint flags)
 {
   struct ifa *b;
 
+  /* Handle iface pseudo-neighbors */
+  if (flags & NEF_IFACE)
+    return *ap = NULL, (i->flags & IF_UP) ? SCOPE_HOST : -1;
+
+  /* Host addresses match even if iface is down */
+  WALK_LIST(b, i->addrs)
+    if (ipa_equal(a, b->ip))
+      return *ap = b, SCOPE_HOST;
+
+  /* Rest do not match if iface is down */
   if (!(i->flags & IF_UP))
+    return *ap = NULL, -1;
+
+  /* Regular neighbors */
+  WALK_LIST(b, i->addrs)
   {
-    *ap = NULL;
+    if (b->flags & IA_PEER)
-    return -1;
+    {
+      if (ipa_equal(a, b->opposite))
+	return *ap = b, b->scope;
+    }
+    else
+    {
+      if (ipa_in_netX(a, &b->prefix))
+      {
+	/* Do not allow IPv4 network and broadcast addresses */
+	if (ipa_is_ip4(a) &&
+	    (net_pxlen(&b->prefix) < (IP4_MAX_PREFIX_LENGTH - 1)) &&
+	    (ipa_equal(a, net_prefix(&b->prefix)) ||	/* Network address */
+	     ipa_equal(a, b->brd)))			/* Broadcast */
+	  return *ap = NULL, -1;
+
+	return *ap = b, b->scope;
+      }
+    }
   }
 
-  WALK_LIST(b, i->addrs)
+  /* Handle ONLINK flag */
-    {
+  if (flags & NEF_ONLINK)
-      *ap = b;
+    return *ap = NULL, ipa_classify(a) & IADDR_SCOPE_MASK;
 
-      if (ipa_equal(*a, b->ip))
+  return *ap = NULL, -1;
-	return SCOPE_HOST;
+}
-      if (b->flags & IA_PEER)
-	{
-	  if (ipa_equal(*a, b->opposite))
-	    return b->scope;
-	}
-      else
-	{
-	  if (ipa_in_netX(*a, &b->prefix))
-	    {
-	      /* Do not allow IPv4 network and broadcast addresses */
-	      if (ipa_is_ip4(*a) &&
-		  (net_pxlen(&b->prefix) < (IP4_MAX_PREFIX_LENGTH - 1)) &&
-		  (ipa_equal(*a, net_prefix(&b->prefix)) ||	/* Network address */
-		   ipa_equal(*a, b->brd)))	/* Broadcast */
-	      {
-		*ap = NULL;
-		return -1;
-	      }
 
-	      return b->scope;
+static inline int
-	    }
+if_connected_any(ip_addr a, struct iface *vrf, struct iface **iface, struct ifa **addr, uint flags)
-	}
+{
+  struct iface *i;
+  struct ifa *b;
+  int s, scope = -1;
+
+  *iface = NULL;
+  *addr = NULL;
+
+  /* Get first match, but prefer SCOPE_HOST to other matches */
+  WALK_LIST(i, iface_list)
+    if ((!vrf || vrf == i->master) && ((s = if_connected(a, i, &b, flags)) >= 0))
+      if ((scope < 0) || ((scope > SCOPE_HOST) && (s == SCOPE_HOST)))
+      {
+	*iface = i;
+	*addr = b;
+	scope = s;
       }
 
-  *ap = NULL;
+  return scope;
-  return -1;
 }
 
 /**
- * neigh_find - find or create a neighbor entry.
+ * neigh_find - find or create a neighbor entry
- * @p: protocol which asks for the entry.
+ * @p: protocol which asks for the entry
- * @a: pointer to IP address of the node to be searched for.
+ * @a: IP address of the node to be searched for
- * @flags: 0 or %NEF_STICKY if you want to create a sticky entry.
+ * @iface: optionally bound neighbor to this iface (may be NULL)
+ * @flags: %NEF_STICKY for sticky entry, %NEF_ONLINK for onlink entry
  *
- * Search the neighbor cache for a node with given IP address. If
+ * Search the neighbor cache for a node with given IP address. Iface can be
- * it's found, a pointer to the neighbor entry is returned. If no
+ * specified for link-local addresses or for cases, where neighbor is expected
- * such entry exists and the node is directly connected on
+ * on given interface. If it is found, a pointer to the neighbor entry is
- * one of our active interfaces, a new entry is created and returned
+ * returned. If no such entry exists and the node is directly connected on one
- * to the caller with protocol-dependent fields initialized to zero.
+ * of our active interfaces, a new entry is created and returned to the caller
- * If the node is not connected directly or *@a is not a valid unicast
+ * with protocol-dependent fields initialized to zero.  If the node is not
- * IP address, neigh_find() returns %NULL.
+ * connected directly or *@a is not a valid unicast IP address, neigh_find()
+ * returns %NULL.
  */
 neighbor *
-neigh_find(struct proto *p, ip_addr *a, unsigned flags)
+neigh_find(struct proto *p, ip_addr a, struct iface *iface, uint flags)
-{
-  return neigh_find2(p, a, NULL, flags);
-}
-
-
-neighbor *
-neigh_find2(struct proto *p, ip_addr *a, struct iface *ifa, unsigned flags)
 {
   neighbor *n;
   int class, scope = -1;
-  uint h = neigh_hash(p, a);
+  uint h = neigh_hash(p, a, iface);
-  struct iface *i;
+  struct iface *ifreq = iface;
-  struct ifa *addr;
+  struct ifa *addr = NULL;
 
   WALK_LIST(n, neigh_hash_table[h])	/* Search the cache */
-    if (n->proto == p && ipa_equal(*a, n->addr) && (!ifa || (ifa == n->iface)))
+    if ((n->proto == p) && ipa_equal(n->addr, a) && (n->ifreq == iface))
       return n;
 
-  class = ipa_classify(*a);
+  if (flags & NEF_IFACE)
-  if (class < 0)			/* Invalid address */
+  {
-    return NULL;
+    if (ipa_nonzero(a) || !iface)
-  if (((class & IADDR_SCOPE_MASK) == SCOPE_HOST) ||
+      return NULL;
-      (((class & IADDR_SCOPE_MASK) == SCOPE_LINK) && (ifa == NULL)) ||
+  }
-      !(class & IADDR_HOST))
-    return NULL;			/* Bad scope or a somecast */
-
-  if (ifa)
-    {
-      scope = if_connected(a, ifa, &addr);
-      flags |= NEF_BIND;
-
-      if ((scope < 0) && (flags & NEF_ONLINK))
-	scope = class & IADDR_SCOPE_MASK;
-    }
   else
-    WALK_LIST(i, iface_list)
+  {
-      if ((!p->vrf || p->vrf == i->master) &&
+    class = ipa_classify(a);
-	  ((scope = if_connected(a, i, &addr)) >= 0))
+    if (class < 0)			/* Invalid address */
-	{
+      return NULL;
-	  ifa = i;
+    if (((class & IADDR_SCOPE_MASK) == SCOPE_HOST) ||
-	  break;
+	(((class & IADDR_SCOPE_MASK) == SCOPE_LINK) && !iface) ||
-	}
+	!(class & IADDR_HOST))
+      return NULL;			/* Bad scope or a somecast */
+  }
+
+  if ((flags & NEF_ONLINK) && !iface)
+      return NULL;
+
+  if (iface)
+  {
+    scope = if_connected(a, iface, &addr, flags);
+    iface = (scope < 0) ? NULL : iface;
+  }
+  else
+    scope = if_connected_any(a, p->vrf, &iface, &addr, flags);
 
   /* scope < 0 means i don't know neighbor */
-  /* scope >= 0 implies ifa != NULL */
+  /* scope >= 0  <=>  iface != NULL */
 
   if ((scope < 0) && !(flags & NEF_STICKY))
     return NULL;
@@ -170,52 +203,15 @@ neigh_find2(struct proto *p, ip_addr *a, struct iface *ifa, unsigned flags)
   n = sl_alloc(neigh_slab);
   memset(n, 0, sizeof(neighbor));
 
-  n->addr = *a;
+  add_tail(&neigh_hash_table[h], &n->n);
-  if (scope >= 0)
+  add_tail((scope >= 0) ? &iface->neighbors : &sticky_neigh_list, &n->if_n);
-    {
+  n->addr = a;
-      add_tail(&neigh_hash_table[h], &n->n);
-      add_tail(&ifa->neighbors, &n->if_n);
-    }
-  else
-    {
-      add_tail(&sticky_neigh_list, &n->n);
-      scope = -1;
-    }
-  n->iface = ifa;
   n->ifa = addr;
+  n->iface = iface;
+  n->ifreq = ifreq;
   n->proto = p;
-  n->data = NULL;
-  n->aux = 0;
   n->flags = flags;
   n->scope = scope;
-  return n;
-}
-
-neighbor *
-neigh_find_iface(struct proto *p, struct iface *ifa)
-{
-  neighbor *n;
-  node *nn;
-
-  /* We keep neighbors with NEF_IFACE foremost in ifa->neighbors list */
-  WALK_LIST2(n, nn, ifa->neighbors, if_n)
-  {
-    if (! (n->flags & NEF_IFACE))
-      break;
-
-    if (n->proto == p)
-      return n;
-  }
-
-  n = sl_alloc(neigh_slab);
-  memset(n, 0, sizeof(neighbor));
-
-  add_tail(&iface_neigh_list, &n->n);
-  add_head(&ifa->neighbors, &n->if_n);
-  n->iface = ifa;
-  n->proto = p;
-  n->flags = NEF_IFACE;
-  n->scope = (ifa->flags & IF_UP) ? SCOPE_HOST : -1;
 
   return n;
 }
@@ -224,30 +220,26 @@ neigh_find_iface(struct proto *p, struct iface *ifa)
  * neigh_dump - dump specified neighbor entry.
  * @n: the entry to dump
  *
- * This functions dumps the contents of a given neighbor entry
+ * This functions dumps the contents of a given neighbor entry to debug output.
- * to debug output.
  */
 void
 neigh_dump(neighbor *n)
 {
-  debug("%p %I ", n, n->addr);
+  debug("%p %I %s %s ", n, n->addr,
-  if (n->iface)
+	n->iface ? n->iface->name : "[]",
-    debug("%s ", n->iface->name);
+	n->ifreq ? n->ifreq->name : "[]");
-  else
-    debug("[] ");
   debug("%s %p %08x scope %s", n->proto->name, n->data, n->aux, ip_scope_text(n->scope));
   if (n->flags & NEF_STICKY)
     debug(" STICKY");
-  if (n->flags & NEF_IFACE)
+  if (n->flags & NEF_ONLINK)
-    debug(" IFACE");
+    debug(" ONLINK");
   debug("\n");
 }
 
 /**
  * neigh_dump_all - dump all neighbor entries.
  *
- * This function dumps the contents of the neighbor cache to
+ * This function dumps the contents of the neighbor cache to debug output.
- * debug output.
  */
 void
 neigh_dump_all(void)
@@ -256,73 +248,109 @@ neigh_dump_all(void)
   int i;
 
   debug("Known neighbors:\n");
-  WALK_LIST(n, sticky_neigh_list)
-    neigh_dump(n);
-  WALK_LIST(n, iface_neigh_list)
-    neigh_dump(n);
   for(i=0; i<NEIGH_HASH_SIZE; i++)
     WALK_LIST(n, neigh_hash_table[i])
       neigh_dump(n);
   debug("\n");
 }
 
+static inline void
+neigh_notify(neighbor *n)
+{
+  if (n->proto->neigh_notify && (n->proto->proto_state != PS_STOP))
+    n->proto->neigh_notify(n);
+}
+
 static void
-neigh_up(neighbor *n, struct iface *i, int scope, struct ifa *a)
+neigh_up(neighbor *n, struct iface *i, struct ifa *a, int scope)
 {
   DBG("Waking up sticky neighbor %I\n", n->addr);
   n->iface = i;
   n->ifa = a;
   n->scope = scope;
 
-  if (! (n->flags & NEF_IFACE))
+  rem_node(&n->if_n);
-  {
+  add_tail(&i->neighbors, &n->if_n);
-    add_tail(&i->neighbors, &n->if_n);
-    rem_node(&n->n);
-    add_tail(&neigh_hash_table[neigh_hash(n->proto, &n->addr)], &n->n);
-  }
 
-  if (n->proto->neigh_notify && (n->proto->proto_state != PS_STOP))
+  neigh_notify(n);
-    n->proto->neigh_notify(n);
 }
 
 static void
 neigh_down(neighbor *n)
 {
   DBG("Flushing neighbor %I on %s\n", n->addr, n->iface->name);
-  if (! (n->flags & (NEF_BIND | NEF_IFACE)))
+  n->iface = NULL;
-    n->iface = NULL;
   n->ifa = NULL;
   n->scope = -1;
 
-  if (! (n->flags & NEF_IFACE))
+  rem_node(&n->if_n);
+  add_tail(&sticky_neigh_list, &n->if_n);
+
+  neigh_notify(n);
+}
+
+static inline void
+neigh_free(neighbor *n)
+{
+  rem_node(&n->n);
+  rem_node(&n->if_n);
+  sl_free(neigh_slab, n);
+}
+
+/**
+ * neigh_update: update neighbor entry w.r.t. change on specific iface
+ * @n: neighbor to update
+ * @iface: changed iface
+ *
+ * The function recalculates state of the neighbor entry @n assuming that only
+ * the interface @iface may changed its state or addresses. Then, appropriate
+ * actions are executed (the neighbor goes up, down, up-down, or just notified).
+ */
+void
+neigh_update(neighbor *n, struct iface *iface)
+{
+  struct ifa *ifa = NULL;
+  int scope = -1;
+
+  /* Iface-bound neighbors ignore other ifaces */
+  if (n->ifreq && (n->ifreq != iface))
+    return;
+
+  /* VRF-bound neighbors ignore changes in other VRFs */
+  if (n->proto->vrf && (n->proto->vrf != iface->master))
+    return;
+
+  scope = if_connected(n->addr, iface, &ifa, n->flags);
+
+  /* When neighbor is going down, try to respawn it on other ifaces */
+  if ((scope < 0) && (n->scope >= 0) && !n->ifreq && (n->flags & NEF_STICKY))
+    scope = if_connected_any(n->addr, n->proto->vrf, &iface, &ifa, n->flags);
+
+  /* No change or minor change - ignore or notify */
+  if ((scope == n->scope) && (iface == n->iface))
+  {
+    if (ifa != n->ifa)
     {
-      rem_node(&n->if_n);
+      n->ifa = ifa;
-      rem_node(&n->n);
+      neigh_notify(n);
     }
 
-  if (n->proto->neigh_notify && (n->proto->proto_state != PS_STOP))
+    return;
-    n->proto->neigh_notify(n);
+  }
 
-  if (n->flags & NEF_STICKY)
+  /* Major change - going down and/or going up */
-    {
-      add_tail(&sticky_neigh_list, &n->n);
 
-      /* Respawn neighbor if there is another matching prefix */
+  if (n->scope >= 0)
-      struct iface *i;
+    neigh_down(n);
-      struct ifa *a;
-      int scope;
 
-      if (!n->iface)
+  if ((n->scope < 0) && !(n->flags & NEF_STICKY))
-	WALK_LIST(i, iface_list)
+  {
-	  if ((scope = if_connected(&n->addr, i, &a)) >= 0)
+    neigh_free(n);
-	    {
+    return;
-	      neigh_up(n, i, scope, a);
+  }
-	      return;
-	    }
-    }
 
-  if (! (n->flags & (NEF_STICKY | NEF_IFACE)))
+  if (scope >= 0)
-    sl_free(neigh_slab, n);
+    neigh_up(n, iface, ifa, scope);
 }
 
 
@@ -338,21 +366,11 @@ neigh_down(neighbor *n)
 void
 neigh_if_up(struct iface *i)
 {
-  struct ifa *a;
   neighbor *n;
   node *x, *y;
-  int scope;
 
-  /* Wake up all iface neighbors */
+  WALK_LIST2_DELSAFE(n, x, y, sticky_neigh_list, if_n)
-  WALK_LIST2_DELSAFE(n, x, y, i->neighbors, if_n)
+    neigh_update(n, i);
-    if ((n->scope < 0) && (n->flags & NEF_IFACE))
-      neigh_up(n, i, SCOPE_HOST, NULL);
-
-  /* Wake up appropriate sticky neighbors */
-  WALK_LIST_DELSAFE(n, x, sticky_neigh_list)
-    if ((!n->iface || n->iface == i) &&
-	((scope = if_connected(&n->addr, i, &a)) >= 0))
-      neigh_up(n, i, scope, a);
 }
 
 /**
@@ -361,8 +379,7 @@ neigh_if_up(struct iface *i)
  *
  * Notify the neighbor cache that an interface has ceased to exist.
  *
- * It causes all entries belonging to neighbors connected to this interface
+ * It causes all neighbors connected to this interface to be updated or removed.
- * to be flushed.
  */
 void
 neigh_if_down(struct iface *i)
@@ -371,16 +388,15 @@ neigh_if_down(struct iface *i)
   node *x, *y;
 
   WALK_LIST2_DELSAFE(n, x, y, i->neighbors, if_n)
-    neigh_down(n);
+    neigh_update(n, i);
 }
 
 /**
  * neigh_if_link - notify neighbor cache about interface link change
  * @i: the interface in question
  *
- * Notify the neighbor cache that an interface changed link state.
+ * Notify the neighbor cache that an interface changed link state. All owners of
- * All owners of neighbor entries connected to this interface are
+ * neighbor entries connected to this interface are notified.
- * notified.
  */
 void
 neigh_if_link(struct iface *i)
@@ -389,8 +405,7 @@ neigh_if_link(struct iface *i)
   node *x, *y;
 
   WALK_LIST2_DELSAFE(n, x, y, i->neighbors, if_n)
-    if (n->proto->neigh_notify && (n->proto->proto_state != PS_STOP))
+    neigh_notify(n);
-      n->proto->neigh_notify(n);
 }
 
 /**
@@ -407,21 +422,16 @@ void
 neigh_ifa_update(struct ifa *a)
 {
   struct iface *i = a->iface;
-  struct ifa *aa;
-  node *x, *y;
   neighbor *n;
-  int scope;
+  node *x, *y;
 
-  /* Remove all neighbors whose scope has changed */
+  /* Update all neighbors whose scope has changed */
   WALK_LIST2_DELSAFE(n, x, y, i->neighbors, if_n)
-    if (n->ifa && (if_connected(&n->addr, i, &aa) != n->scope))
+    neigh_update(n, i);
-      neigh_down(n);
 
   /* Wake up all sticky neighbors that are reachable now */
-  WALK_LIST_DELSAFE(n, x, sticky_neigh_list)
+  WALK_LIST2_DELSAFE(n, x, y, sticky_neigh_list, if_n)
-    if ((!n->iface || n->iface == i) &&
+    neigh_update(n, i);
-	((scope = if_connected(&n->addr, i, &aa)) >= 0))
-      neigh_up(n, i, scope, aa);
 }
 
 static inline void
@@ -429,10 +439,8 @@ neigh_prune_one(neighbor *n)
 {
   if (n->proto->proto_state != PS_DOWN)
     return;
-  rem_node(&n->n);
+
-  if (n->if_n.next)
+  neigh_free(n);
-    rem_node(&n->if_n);
-  sl_free(neigh_slab, n);
 }
 
 /**
@@ -453,10 +461,6 @@ neigh_prune(void)
   for(i=0; i<NEIGH_HASH_SIZE; i++)
     WALK_LIST_DELSAFE(n, m, neigh_hash_table[i])
       neigh_prune_one(n);
-  WALK_LIST_DELSAFE(n, m, sticky_neigh_list)
-    neigh_prune_one(n);
-  WALK_LIST_DELSAFE(n, m, iface_neigh_list)
-    neigh_prune_one(n);
 }
 
 /**
@@ -471,9 +475,8 @@ neigh_init(pool *if_pool)
 {
   neigh_slab = sl_new(if_pool, sizeof(neighbor));
 
-  init_list(&sticky_neigh_list);
-  init_list(&iface_neigh_list);
-
   for(int i = 0; i < NEIGH_HASH_SIZE; i++)
     init_list(&neigh_hash_table[i]);
+
+  init_list(&sticky_neigh_list);
 }

nest/rt-table.c

@@ -39,6 +39,7 @@
 #include "lib/string.h"
 #include "conf/conf.h"
 #include "filter/filter.h"
+#include "lib/hash.h"
 #include "lib/string.h"
 #include "lib/alloca.h"
 
@@ -2220,13 +2221,6 @@ rt_feed_channel_abort(struct channel *c)
     }
 }
 
-static inline unsigned
-ptr_hash(void *ptr)
-{
-  uintptr_t p = (uintptr_t) ptr;
-  return p ^ (p << 8) ^ (p >> 16);
-}
-
 static inline u32
 hc_hash(ip_addr a, rtable *dep)
 {

proto/bfd/bfd.c

@@ -775,7 +775,7 @@ bfd_start_neighbor(struct bfd_proto *p, struct bfd_neighbor *n)
     return;
   }
 
-  struct neighbor *nb = neigh_find2(&p->p, &n->addr, n->iface, NEF_STICKY);
+  struct neighbor *nb = neigh_find(&p->p, n->addr, n->iface, NEF_STICKY);
   if (!nb)
   {
     log(L_ERR "%s: Invalid remote address %I%J", p->p.name, n->addr, n->iface);

proto/bgp/bgp.c

@@ -1277,7 +1277,7 @@ bgp_start_locked(struct object_lock *lock)
     return;
   }
 
-  neighbor *n = neigh_find2(&p->p, &cf->remote_ip, cf->iface, NEF_STICKY);
+  neighbor *n = neigh_find(&p->p, cf->remote_ip, cf->iface, NEF_STICKY);
   if (!n)
   {
     log(L_ERR "%s: Invalid remote address %I%J", p->p.name, cf->remote_ip, cf->iface);
@@ -1521,7 +1521,7 @@ bgp_channel_start(struct channel *C)
   if (ipa_zero(c->next_hop_addr))
   {
     /* We know the iface for single-hop, we make lookup for multihop */
-    struct neighbor *nbr = p->neigh ?: neigh_find2(&p->p, &src, NULL, 0);
+    struct neighbor *nbr = p->neigh ?: neigh_find(&p->p, src, NULL, 0);
     struct iface *iface = nbr ? nbr->iface : NULL;
 
     if (bgp_channel_is_ipv4(c) && iface && iface->addr4)

proto/bgp/packets.c

@@ -744,9 +744,9 @@ bgp_apply_next_hop(struct bgp_parse_state *s, rta *a, ip_addr gw, ip_addr ll)
 
     /* GW_DIRECT -> single_hop -> p->neigh != NULL */
     if (ipa_nonzero(gw))
-      nbr = neigh_find2(&p->p, &gw, NULL, 0);
+      nbr = neigh_find(&p->p, gw, NULL, 0);
     else if (ipa_nonzero(ll))
-      nbr = neigh_find2(&p->p, &ll, p->neigh->iface, 0);
+      nbr = neigh_find(&p->p, ll, p->neigh->iface, 0);
 
     if (!nbr || (nbr->scope == SCOPE_HOST))
       WITHDRAW(BAD_NEXT_HOP);

proto/ospf/rt.c

@@ -1987,7 +1987,7 @@ again1:
       for (nh = nf->n.nhs; nh; nh = nh->next)
 	if (ipa_nonzero(nh->gw))
 	{
-	  neighbor *ng = neigh_find2(&p->p, &nh->gw, nh->iface, 0);
+	  neighbor *ng = neigh_find(&p->p, nh->gw, nh->iface, 0);
 	  if (!ng || (ng->scope == SCOPE_HOST))
 	    { reset_ri(nf); break; }
 	}

proto/rip/packets.c

@@ -627,7 +627,7 @@ rip_receive_response(struct rip_proto *p, struct rip_iface *ifa, struct rip_pack
 
     if (ipa_nonzero(rte.next_hop))
     {
-      neighbor *nbr = neigh_find2(&p->p, &rte.next_hop, ifa->iface, 0);
+      neighbor *nbr = neigh_find(&p->p, rte.next_hop, ifa->iface, 0);
       if (!nbr || (nbr->scope <= 0))
 	rte.next_hop = IPA_NONE;
     }

proto/rip/rip.c

@@ -377,7 +377,7 @@ rip_rt_notify(struct proto *P, struct channel *ch UNUSED, struct network *net, s
 struct rip_neighbor *
 rip_get_neighbor(struct rip_proto *p, ip_addr *a, struct rip_iface *ifa)
 {
-  neighbor *nbr = neigh_find2(&p->p, a, ifa->iface, 0);
+  neighbor *nbr = neigh_find(&p->p, *a, ifa->iface, 0);
 
   if (!nbr || (nbr->scope == SCOPE_HOST) || !rip_iface_link_up(ifa))
     return NULL;

proto/static/static.c

@@ -205,10 +205,9 @@ static_add_rte(struct static_proto *p, struct static_route *r)
 
     for (r2 = r; r2; r2 = r2->mp_next)
     {
-      n = ipa_nonzero(r2->via) ?
+      n = neigh_find(&p->p, r2->via, r2->iface, NEF_STICKY |
-	neigh_find2(&p->p, &r2->via, r2->iface,
+		     (r2->onlink ? NEF_ONLINK : 0) |
-		    NEF_STICKY | (r2->onlink ? NEF_ONLINK : 0)) :
+		     (ipa_zero(r2->via) ? NEF_IFACE : 0));
-	neigh_find_iface(&p->p, r2->iface);
 
       if (!n)
       {

sysdep/linux/netlink.c

@@ -696,8 +696,8 @@ nl_parse_multipath(struct nl_parse_state *s, struct krt_proto *p, struct rtattr
 	    rv->flags |= RNF_ONLINK;
 
 	  neighbor *nbr;
-	  nbr = neigh_find2(&p->p, &rv->gw, rv->iface,
+	  nbr = neigh_find(&p->p, rv->gw, rv->iface,
-			    (rv->flags & RNF_ONLINK) ? NEF_ONLINK : 0);
+			   (rv->flags & RNF_ONLINK) ? NEF_ONLINK : 0);
 	  if (!nbr || (nbr->scope == SCOPE_HOST))
 	    return NULL;
 	}
@@ -1636,8 +1636,8 @@ nl_parse_route(struct nl_parse_state *s, struct nlmsghdr *h)
 	    ra->nh.flags |= RNF_ONLINK;
 
 	  neighbor *nbr;
-	  nbr = neigh_find2(&p->p, &(ra->nh.gw), ra->nh.iface,
+	  nbr = neigh_find(&p->p, ra->nh.gw, ra->nh.iface,
-			    (ra->nh.flags & RNF_ONLINK) ? NEF_ONLINK : 0);
+			   (ra->nh.flags & RNF_ONLINK) ? NEF_ONLINK : 0);
 	  if (!nbr || (nbr->scope == SCOPE_HOST))
 	    {
 	      log(L_ERR "KRT: Received route %N with strange next-hop %I", net->n.addr,