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In OSPFv3-IPv4 there is no requirement that link-local next hop announced in Link-LSA must be in interface address range. Therefore, for interfaces that do not have IPv4 address we can use some loopback IP address and announce it as a next hop. Also we should accept such address.
569 lines
15 KiB
C
569 lines
15 KiB
C
/*
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* BIRD -- Neighbor Cache
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*
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* (c) 1998--2000 Martin Mares <mj@ucw.cz>
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* (c) 2008--2018 Ondrej Zajicek <santiago@crfreenet.org>
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* (c) 2008--2018 CZ.NIC z.s.p.o.
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*
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* Can be freely distributed and used under the terms of the GNU GPL.
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*/
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/**
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* DOC: Neighbor cache
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*
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* Most routing protocols need to associate their internal state data with
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* neighboring routers, check whether an address given as the next hop attribute
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* of a route is really an address of a directly connected host and which
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* interface is it connected through. Also, they often need to be notified when
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* a neighbor ceases to exist or when their long awaited neighbor becomes
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* connected. The neighbor cache is there to solve all these problems.
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*
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* The neighbor cache maintains a collection of neighbor entries. Each entry
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* represents one IP address corresponding to either our directly connected
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* neighbor or our own end of the link (when the scope of the address is set to
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* %SCOPE_HOST) together with per-neighbor data belonging to a single protocol.
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* A neighbor entry may be bound to a specific interface, which is required for
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* link-local IP addresses and optional for global IP addresses.
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*
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* Neighbor cache entries are stored in a hash table, which is indexed by triple
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* (protocol, IP, requested-iface), so if both regular and iface-bound neighbors
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* are requested, they are represented by two neighbor cache entries. Active
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* entries are also linked in per-interface list (allowing quick processing of
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* interface change events). Inactive entries exist only when the protocol has
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* explicitly requested it via the %NEF_STICKY flag because it wishes to be
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* notified when the node will again become a neighbor. Such entries are instead
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* linked in a special list, which is walked whenever an interface changes its
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* state to up. Neighbor entry VRF association is implied by respective
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* protocol.
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*
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* Besides the already mentioned %NEF_STICKY flag, there is also %NEF_ONLINK,
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* which specifies that neighbor should be considered reachable on given iface
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* regardless of associated address ranges, and %NEF_IFACE, which represents
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* pseudo-neighbor entry for whole interface (and uses %IPA_NONE IP address).
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*
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* When a neighbor event occurs (a neighbor gets disconnected or a sticky
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* inactive neighbor becomes connected), the protocol hook neigh_notify() is
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* called to advertise the change.
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*/
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#undef LOCAL_DEBUG
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#include "nest/bird.h"
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#include "nest/iface.h"
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#include "nest/protocol.h"
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#include "lib/hash.h"
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#include "lib/resource.h"
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#define NEIGH_HASH_SIZE 256
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#define NEIGH_HASH_OFFSET 24
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static slab *neigh_slab;
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static list neigh_hash_table[NEIGH_HASH_SIZE], sticky_neigh_list;
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static inline uint
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neigh_hash(struct proto *p, ip_addr a, struct iface *i)
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{
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return (p->hash_key ^ ipa_hash(a) ^ ptr_hash(i)) >> NEIGH_HASH_OFFSET;
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}
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static inline int
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ifa_better(struct ifa *a, struct ifa *b)
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{
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return a && (!b || (a->prefix.pxlen > b->prefix.pxlen));
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}
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static inline int
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scope_better(int sa, int sb)
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{
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/* Order per preference: -1 unknown, 0 for remote, 1 for local */
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sa = (sa < 0) ? sa : !sa;
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sb = (sb < 0) ? sb : !sb;
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return sa > sb;
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}
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static inline int
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scope_remote(int sa, int sb)
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{
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return (sa > SCOPE_HOST) && (sb > SCOPE_HOST);
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}
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static int
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if_connected(ip_addr a, struct iface *i, struct ifa **ap, uint flags)
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{
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struct ifa *b, *addr = NULL;
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/* Handle iface pseudo-neighbors */
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if (flags & NEF_IFACE)
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return *ap = NULL, (i->flags & IF_UP) ? SCOPE_HOST : -1;
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/* Host addresses match even if iface is down */
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WALK_LIST(b, i->addrs)
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if (ipa_equal(a, b->ip))
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return *ap = b, SCOPE_HOST;
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/* Rest do not match if iface is down */
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if (!(i->flags & IF_UP))
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return *ap = NULL, -1;
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/* Regular neighbors */
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WALK_LIST(b, i->addrs)
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{
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if (b->flags & IA_PEER)
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{
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if (ipa_equal(a, b->opposite) && ifa_better(b, addr))
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addr = b;
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}
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else
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{
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if (ipa_in_netX(a, &b->prefix) && ifa_better(b, addr))
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{
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/* Do not allow IPv4 network and broadcast addresses */
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if (ipa_is_ip4(a) &&
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(net_pxlen(&b->prefix) < (IP4_MAX_PREFIX_LENGTH - 1)) &&
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(ipa_equal(a, net_prefix(&b->prefix)) || /* Network address */
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ipa_equal(a, b->brd))) /* Broadcast */
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return *ap = NULL, -1;
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addr = b;
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}
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}
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}
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/* Return found address */
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if (addr)
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return *ap = addr, addr->scope;
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/* Handle ONLINK flag */
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if (flags & NEF_ONLINK)
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return *ap = NULL, ipa_classify(a) & IADDR_SCOPE_MASK;
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return *ap = NULL, -1;
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}
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static inline int
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if_connected_any(ip_addr a, struct iface *vrf, uint vrf_set, struct iface **iface, struct ifa **addr, uint flags)
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{
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struct iface *i;
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struct ifa *b;
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int s, scope = -1;
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*iface = NULL;
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*addr = NULL;
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/* Prefer SCOPE_HOST or longer prefix */
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WALK_LIST(i, iface_list)
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if ((!vrf_set || if_in_vrf(i, vrf)) && ((s = if_connected(a, i, &b, flags)) >= 0))
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if (scope_better(s, scope) || (scope_remote(s, scope) && ifa_better(b, *addr)))
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{
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*iface = i;
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*addr = b;
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scope = s;
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}
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return scope;
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}
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/* Is ifa @a subnet of any ifa on iface @ib ? */
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static inline int
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ifa_intersect(struct ifa *a, struct iface *ib)
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{
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struct ifa *b;
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WALK_LIST(b, ib->addrs)
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if (net_in_netX(&a->prefix, &b->prefix))
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return 1;
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return 0;
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}
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/* Is any ifa of iface @ia subnet of any ifa on iface @ib ? */
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static inline int
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if_intersect(struct iface *ia, struct iface *ib)
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{
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struct ifa *a, *b;
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WALK_LIST(a, ia->addrs)
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WALK_LIST(b, ib->addrs)
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if (net_in_netX(&a->prefix, &b->prefix))
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return 1;
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return 0;
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}
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/**
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* neigh_find - find or create a neighbor entry
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* @p: protocol which asks for the entry
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* @a: IP address of the node to be searched for
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* @iface: optionally bound neighbor to this iface (may be NULL)
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* @flags: %NEF_STICKY for sticky entry, %NEF_ONLINK for onlink entry
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*
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* Search the neighbor cache for a node with given IP address. Iface can be
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* specified for link-local addresses or for cases, where neighbor is expected
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* on given interface. If it is found, a pointer to the neighbor entry is
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* returned. If no such entry exists and the node is directly connected on one
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* of our active interfaces, a new entry is created and returned to the caller
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* with protocol-dependent fields initialized to zero. If the node is not
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* connected directly or *@a is not a valid unicast IP address, neigh_find()
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* returns %NULL.
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*/
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neighbor *
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neigh_find(struct proto *p, ip_addr a, struct iface *iface, uint flags)
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{
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neighbor *n;
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int class, scope = -1;
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uint h = neigh_hash(p, a, iface);
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struct iface *ifreq = iface;
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struct ifa *addr = NULL;
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WALK_LIST(n, neigh_hash_table[h]) /* Search the cache */
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if ((n->proto == p) && ipa_equal(n->addr, a) && (n->ifreq == iface) &&
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((n->flags & NEF_ONLINK) == (flags & NEF_ONLINK)))
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return n;
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if (flags & NEF_IFACE)
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{
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if (ipa_nonzero(a) || !iface)
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return NULL;
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}
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else
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{
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class = ipa_classify(a);
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if (class < 0) /* Invalid address */
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return NULL;
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if (((class & IADDR_SCOPE_MASK) == SCOPE_HOST) ||
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(((class & IADDR_SCOPE_MASK) == SCOPE_LINK) && !iface) ||
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!(class & IADDR_HOST))
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return NULL; /* Bad scope or a somecast */
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}
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if ((flags & NEF_ONLINK) && !iface)
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return NULL;
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if (iface)
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{
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scope = if_connected(a, iface, &addr, flags);
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iface = (scope < 0) ? NULL : iface;
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}
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else
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scope = if_connected_any(a, p->vrf, p->vrf_set, &iface, &addr, flags);
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/* scope < 0 means i don't know neighbor */
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/* scope >= 0 <=> iface != NULL */
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if ((scope < 0) && !(flags & NEF_STICKY))
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return NULL;
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n = sl_allocz(neigh_slab);
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add_tail(&neigh_hash_table[h], &n->n);
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add_tail((scope >= 0) ? &iface->neighbors : &sticky_neigh_list, &n->if_n);
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n->addr = a;
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n->ifa = addr;
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n->iface = iface;
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n->ifreq = ifreq;
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n->proto = p;
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n->flags = flags;
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n->scope = scope;
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return n;
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}
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/**
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* neigh_dump - dump specified neighbor entry.
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* @n: the entry to dump
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*
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* This functions dumps the contents of a given neighbor entry to debug output.
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*/
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void
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neigh_dump(neighbor *n)
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{
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debug("%p %I %s %s ", n, n->addr,
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n->iface ? n->iface->name : "[]",
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n->ifreq ? n->ifreq->name : "[]");
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debug("%s %p %08x scope %s", n->proto->name, n->data, n->aux, ip_scope_text(n->scope));
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if (n->flags & NEF_STICKY)
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debug(" STICKY");
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if (n->flags & NEF_ONLINK)
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debug(" ONLINK");
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debug("\n");
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}
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/**
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* neigh_dump_all - dump all neighbor entries.
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*
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* This function dumps the contents of the neighbor cache to debug output.
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*/
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void
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neigh_dump_all(void)
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{
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neighbor *n;
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int i;
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debug("Known neighbors:\n");
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for(i=0; i<NEIGH_HASH_SIZE; i++)
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WALK_LIST(n, neigh_hash_table[i])
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neigh_dump(n);
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debug("\n");
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}
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static inline void
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neigh_notify(neighbor *n)
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{
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if (n->proto->neigh_notify && (n->proto->proto_state != PS_STOP))
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n->proto->neigh_notify(n);
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}
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static void
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neigh_up(neighbor *n, struct iface *i, struct ifa *a, int scope)
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{
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DBG("Waking up sticky neighbor %I\n", n->addr);
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n->iface = i;
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n->ifa = a;
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n->scope = scope;
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rem_node(&n->if_n);
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add_tail(&i->neighbors, &n->if_n);
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neigh_notify(n);
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}
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static void
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neigh_down(neighbor *n)
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{
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DBG("Flushing neighbor %I on %s\n", n->addr, n->iface->name);
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n->iface = NULL;
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n->ifa = NULL;
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n->scope = -1;
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rem_node(&n->if_n);
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add_tail(&sticky_neigh_list, &n->if_n);
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neigh_notify(n);
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}
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static inline void
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neigh_free(neighbor *n)
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{
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rem_node(&n->n);
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rem_node(&n->if_n);
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sl_free(n);
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}
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/**
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* neigh_update: update neighbor entry w.r.t. change on specific iface
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* @n: neighbor to update
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* @iface: changed iface
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*
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* The function recalculates state of the neighbor entry @n assuming that only
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* the interface @iface may changed its state or addresses. Then, appropriate
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* actions are executed (the neighbor goes up, down, up-down, or just notified).
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*/
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void
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neigh_update(neighbor *n, struct iface *iface)
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{
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struct proto *p = n->proto;
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struct ifa *ifa = NULL;
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int scope = -1;
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/* Iface-bound neighbors ignore other ifaces */
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if (n->ifreq && (n->ifreq != iface))
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return;
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/* VRF-bound neighbors ignore changes in other VRFs */
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if (p->vrf_set && !if_in_vrf(iface, p->vrf))
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return;
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scope = if_connected(n->addr, iface, &ifa, n->flags);
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/* Update about already assigned iface, or some other iface */
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if (iface == n->iface)
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{
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/* When neighbor is going down, try to respawn it on other ifaces */
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if ((scope < 0) && (n->scope >= 0) && !n->ifreq && (n->flags & NEF_STICKY))
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scope = if_connected_any(n->addr, p->vrf, p->vrf_set, &iface, &ifa, n->flags);
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}
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else
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{
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/* Continue only if the new variant is better than the existing one */
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if (! (scope_better(scope, n->scope) ||
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(scope_remote(scope, n->scope) && ifa_better(ifa, n->ifa))))
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return;
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}
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/* No change or minor change - ignore or notify */
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if ((scope == n->scope) && (iface == n->iface))
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{
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if (ifa != n->ifa)
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{
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n->ifa = ifa;
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neigh_notify(n);
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}
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return;
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}
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/* Major change - going down and/or going up */
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if (n->scope >= 0)
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neigh_down(n);
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if ((n->scope < 0) && !(n->flags & NEF_STICKY))
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{
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neigh_free(n);
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return;
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}
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if (scope >= 0)
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neigh_up(n, iface, ifa, scope);
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}
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/**
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* neigh_if_up: notify neighbor cache about interface up event
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* @i: interface in question
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*
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* Tell the neighbor cache that a new interface became up.
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*
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* The neighbor cache wakes up all inactive sticky neighbors with
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* addresses belonging to prefixes of the interface @i.
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*/
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void
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neigh_if_up(struct iface *i)
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{
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struct iface *ii;
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neighbor *n;
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node *x, *y;
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/* Update neighbors that might be better off with the new iface */
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WALK_LIST(ii, iface_list)
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if (!EMPTY_LIST(ii->neighbors) && (ii != i) && if_intersect(i, ii))
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WALK_LIST2_DELSAFE(n, x, y, ii->neighbors, if_n)
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neigh_update(n, i);
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WALK_LIST2_DELSAFE(n, x, y, sticky_neigh_list, if_n)
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neigh_update(n, i);
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}
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/**
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* neigh_if_down - notify neighbor cache about interface down event
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* @i: the interface in question
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*
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* Notify the neighbor cache that an interface has ceased to exist.
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*
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* It causes all neighbors connected to this interface to be updated or removed.
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*/
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void
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neigh_if_down(struct iface *i)
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{
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neighbor *n;
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node *x, *y;
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WALK_LIST2_DELSAFE(n, x, y, i->neighbors, if_n)
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neigh_update(n, i);
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}
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/**
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* neigh_if_link - notify neighbor cache about interface link change
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* @i: the interface in question
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*
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* Notify the neighbor cache that an interface changed link state. All owners of
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* neighbor entries connected to this interface are notified.
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*/
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void
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neigh_if_link(struct iface *i)
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{
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neighbor *n;
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node *x, *y;
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WALK_LIST2_DELSAFE(n, x, y, i->neighbors, if_n)
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neigh_notify(n);
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}
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/**
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* neigh_ifa_update: notify neighbor cache about interface address add or remove event
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* @a: interface address in question
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*
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* Tell the neighbor cache that an address was added or removed.
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*
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* The neighbor cache wakes up all inactive sticky neighbors with
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* addresses belonging to prefixes of the interface belonging to @ifa
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* and causes all unreachable neighbors to be flushed.
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*/
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void
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neigh_ifa_up(struct ifa *a)
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{
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struct iface *i = a->iface, *ii;
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neighbor *n;
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node *x, *y;
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/* Update neighbors that might be better off with the new ifa */
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WALK_LIST(ii, iface_list)
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if (!EMPTY_LIST(ii->neighbors) && ifa_intersect(a, ii))
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WALK_LIST2_DELSAFE(n, x, y, ii->neighbors, if_n)
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neigh_update(n, i);
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/* Wake up all sticky neighbors that are reachable now */
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WALK_LIST2_DELSAFE(n, x, y, sticky_neigh_list, if_n)
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neigh_update(n, i);
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}
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|
|
void
|
|
neigh_ifa_down(struct ifa *a)
|
|
{
|
|
struct iface *i = a->iface;
|
|
neighbor *n;
|
|
node *x, *y;
|
|
|
|
/* Update all neighbors whose scope has changed */
|
|
WALK_LIST2_DELSAFE(n, x, y, i->neighbors, if_n)
|
|
if (n->ifa == a)
|
|
neigh_update(n, i);
|
|
}
|
|
|
|
static inline void
|
|
neigh_prune_one(neighbor *n)
|
|
{
|
|
if (n->proto->proto_state != PS_DOWN)
|
|
return;
|
|
|
|
neigh_free(n);
|
|
}
|
|
|
|
/**
|
|
* neigh_prune - prune neighbor cache
|
|
*
|
|
* neigh_prune() examines all neighbor entries cached and removes those
|
|
* corresponding to inactive protocols. It's called whenever a protocol
|
|
* is shut down to get rid of all its heritage.
|
|
*/
|
|
void
|
|
neigh_prune(void)
|
|
{
|
|
neighbor *n;
|
|
node *m;
|
|
int i;
|
|
|
|
DBG("Pruning neighbors\n");
|
|
for(i=0; i<NEIGH_HASH_SIZE; i++)
|
|
WALK_LIST_DELSAFE(n, m, neigh_hash_table[i])
|
|
neigh_prune_one(n);
|
|
}
|
|
|
|
/**
|
|
* neigh_init - initialize the neighbor cache.
|
|
* @if_pool: resource pool to be used for neighbor entries.
|
|
*
|
|
* This function is called during BIRD startup to initialize
|
|
* the neighbor cache module.
|
|
*/
|
|
void
|
|
neigh_init(pool *if_pool)
|
|
{
|
|
neigh_slab = sl_new(if_pool, sizeof(neighbor));
|
|
|
|
for(int i = 0; i < NEIGH_HASH_SIZE; i++)
|
|
init_list(&neigh_hash_table[i]);
|
|
|
|
init_list(&sticky_neigh_list);
|
|
}
|