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bird/nest/rt-attr.c
Ondrej Zajicek 42a0c05408 BGP Extended communities.
2011-08-14 13:55:02 +02:00

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/*
* BIRD -- Route Attribute Cache
*
* (c) 1998--2000 Martin Mares <mj@ucw.cz>
*
* Can be freely distributed and used under the terms of the GNU GPL.
*/
/**
* DOC: Route attribute cache
*
* Each route entry carries a set of route attributes. Several of them
* vary from route to route, but most attributes are usually common
* for a large number of routes. To conserve memory, we've decided to
* store only the varying ones directly in the &rte and hold the rest
* in a special structure called &rta which is shared among all the
* &rte's with these attributes.
*
* Each &rta contains all the static attributes of the route (i.e.,
* those which are always present) as structure members and a list of
* dynamic attributes represented by a linked list of &ea_list
* structures, each of them consisting of an array of &eattr's containing
* the individual attributes. An attribute can be specified more than once
* in the &ea_list chain and in such case the first occurrence overrides
* the others. This semantics is used especially when someone (for example
* a filter) wishes to alter values of several dynamic attributes, but
* it wants to preserve the original attribute lists maintained by
* another module.
*
* Each &eattr contains an attribute identifier (split to protocol ID and
* per-protocol attribute ID), protocol dependent flags, a type code (consisting
* of several bit fields describing attribute characteristics) and either an
* embedded 32-bit value or a pointer to a &adata structure holding attribute
* contents.
*
* There exist two variants of &rta's -- cached and un-cached ones. Un-cached
* &rta's can have arbitrarily complex structure of &ea_list's and they
* can be modified by any module in the route processing chain. Cached
* &rta's have their attribute lists normalized (that means at most one
* &ea_list is present and its values are sorted in order to speed up
* searching), they are stored in a hash table to make fast lookup possible
* and they are provided with a use count to allow sharing.
*
* Routing tables always contain only cached &rta's.
*/
#include "nest/bird.h"
#include "nest/route.h"
#include "nest/protocol.h"
#include "nest/iface.h"
#include "nest/cli.h"
#include "nest/attrs.h"
#include "lib/alloca.h"
#include "lib/resource.h"
#include "lib/string.h"
pool *rta_pool;
static slab *rta_slab;
static slab *mpnh_slab;
struct protocol *attr_class_to_protocol[EAP_MAX];
static inline unsigned int
mpnh_hash(struct mpnh *x)
{
unsigned int h = 0;
for (; x; x = x->next)
h ^= ipa_hash(x->gw);
return h;
}
int
mpnh__same(struct mpnh *x, struct mpnh *y)
{
for (; x && y; x = x->next, y = y->next)
if (!ipa_equal(x->gw, y->gw) || (x->iface != y->iface) || (x->weight != y->weight))
return 0;
return x == y;
}
static struct mpnh *
mpnh_copy(struct mpnh *o)
{
struct mpnh *first = NULL;
struct mpnh **last = &first;
for (; o; o = o->next)
{
struct mpnh *n = sl_alloc(mpnh_slab);
n->gw = o->gw;
n->iface = o->iface;
n->next = NULL;
n->weight = o->weight;
*last = n;
last = &(n->next);
}
return first;
}
static void
mpnh_free(struct mpnh *o)
{
struct mpnh *n;
while (o)
{
n = o->next;
sl_free(mpnh_slab, o);
o = n;
}
}
/*
* Extended Attributes
*/
static inline eattr *
ea__find(ea_list *e, unsigned id)
{
eattr *a;
int l, r, m;
while (e)
{
if (e->flags & EALF_BISECT)
{
l = 0;
r = e->count - 1;
while (l <= r)
{
m = (l+r) / 2;
a = &e->attrs[m];
if (a->id == id)
return a;
else if (a->id < id)
l = m+1;
else
r = m-1;
}
}
else
for(m=0; m<e->count; m++)
if (e->attrs[m].id == id)
return &e->attrs[m];
e = e->next;
}
return NULL;
}
/**
* ea_find - find an extended attribute
* @e: attribute list to search in
* @id: attribute ID to search for
*
* Given an extended attribute list, ea_find() searches for a first
* occurrence of an attribute with specified ID, returning either a pointer
* to its &eattr structure or %NULL if no such attribute exists.
*/
eattr *
ea_find(ea_list *e, unsigned id)
{
eattr *a = ea__find(e, id & EA_CODE_MASK);
if (a && (a->type & EAF_TYPE_MASK) == EAF_TYPE_UNDEF &&
!(id & EA_ALLOW_UNDEF))
return NULL;
return a;
}
/**
* ea_get_int - fetch an integer attribute
* @e: attribute list
* @id: attribute ID
* @def: default value
*
* This function is a shortcut for retrieving a value of an integer attribute
* by calling ea_find() to find the attribute, extracting its value or returning
* a provided default if no such attribute is present.
*/
int
ea_get_int(ea_list *e, unsigned id, int def)
{
eattr *a = ea_find(e, id);
if (!a)
return def;
return a->u.data;
}
static inline void
ea_do_sort(ea_list *e)
{
unsigned n = e->count;
eattr *a = e->attrs;
eattr *b = alloca(n * sizeof(eattr));
unsigned s, ss;
/* We need to use a stable sorting algorithm, hence mergesort */
do
{
s = ss = 0;
while (s < n)
{
eattr *p, *q, *lo, *hi;
p = b;
ss = s;
*p++ = a[s++];
while (s < n && p[-1].id <= a[s].id)
*p++ = a[s++];
if (s < n)
{
q = p;
*p++ = a[s++];
while (s < n && p[-1].id <= a[s].id)
*p++ = a[s++];
lo = b;
hi = q;
s = ss;
while (lo < q && hi < p)
if (lo->id <= hi->id)
a[s++] = *lo++;
else
a[s++] = *hi++;
while (lo < q)
a[s++] = *lo++;
while (hi < p)
a[s++] = *hi++;
}
}
}
while (ss);
}
static inline void
ea_do_prune(ea_list *e)
{
eattr *s, *d, *l, *s0;
int i = 0;
/* Discard duplicates and undefs. Do you remember sorting was stable? */
s = d = e->attrs;
l = e->attrs + e->count;
while (s < l)
{
s0 = s++;
while (s < l && s->id == s[-1].id)
s++;
/* s0 is the most recent version, s[-1] the oldest one */
if ((s0->type & EAF_TYPE_MASK) != EAF_TYPE_UNDEF)
{
*d = *s0;
d->type = (d->type & ~EAF_ORIGINATED) | (s[-1].type & EAF_ORIGINATED);
d++;
i++;
}
}
e->count = i;
}
/**
* ea_sort - sort an attribute list
* @e: list to be sorted
*
* This function takes a &ea_list chain and sorts the attributes
* within each of its entries.
*
* If an attribute occurs multiple times in a single &ea_list,
* ea_sort() leaves only the first (the only significant) occurrence.
*/
void
ea_sort(ea_list *e)
{
while (e)
{
if (!(e->flags & EALF_SORTED))
{
ea_do_sort(e);
ea_do_prune(e);
e->flags |= EALF_SORTED;
}
if (e->count > 5)
e->flags |= EALF_BISECT;
e = e->next;
}
}
/**
* ea_scan - estimate attribute list size
* @e: attribute list
*
* This function calculates an upper bound of the size of
* a given &ea_list after merging with ea_merge().
*/
unsigned
ea_scan(ea_list *e)
{
unsigned cnt = 0;
while (e)
{
cnt += e->count;
e = e->next;
}
return sizeof(ea_list) + sizeof(eattr)*cnt;
}
/**
* ea_merge - merge segments of an attribute list
* @e: attribute list
* @t: buffer to store the result to
*
* This function takes a possibly multi-segment attribute list
* and merges all of its segments to one.
*
* The primary use of this function is for &ea_list normalization:
* first call ea_scan() to determine how much memory will the result
* take, then allocate a buffer (usually using alloca()), merge the
* segments with ea_merge() and finally sort and prune the result
* by calling ea_sort().
*/
void
ea_merge(ea_list *e, ea_list *t)
{
eattr *d = t->attrs;
t->flags = 0;
t->count = 0;
t->next = NULL;
while (e)
{
memcpy(d, e->attrs, sizeof(eattr)*e->count);
t->count += e->count;
d += e->count;
e = e->next;
}
}
/**
* ea_same - compare two &ea_list's
* @x: attribute list
* @y: attribute list
*
* ea_same() compares two normalized attribute lists @x and @y and returns
* 1 if they contain the same attributes, 0 otherwise.
*/
int
ea_same(ea_list *x, ea_list *y)
{
int c;
if (!x || !y)
return x == y;
ASSERT(!x->next && !y->next);
if (x->count != y->count)
return 0;
for(c=0; c<x->count; c++)
{
eattr *a = &x->attrs[c];
eattr *b = &y->attrs[c];
if (a->id != b->id ||
a->flags != b->flags ||
a->type != b->type ||
((a->type & EAF_EMBEDDED) ? a->u.data != b->u.data :
(a->u.ptr->length != b->u.ptr->length || memcmp(a->u.ptr->data, b->u.ptr->data, a->u.ptr->length))))
return 0;
}
return 1;
}
static inline ea_list *
ea_list_copy(ea_list *o)
{
ea_list *n;
unsigned i, len;
if (!o)
return NULL;
ASSERT(!o->next);
len = sizeof(ea_list) + sizeof(eattr) * o->count;
n = mb_alloc(rta_pool, len);
memcpy(n, o, len);
n->flags |= EALF_CACHED;
for(i=0; i<o->count; i++)
{
eattr *a = &n->attrs[i];
if (!(a->type & EAF_EMBEDDED))
{
unsigned size = sizeof(struct adata) + a->u.ptr->length;
struct adata *d = mb_alloc(rta_pool, size);
memcpy(d, a->u.ptr, size);
a->u.ptr = d;
}
}
return n;
}
static inline void
ea_free(ea_list *o)
{
int i;
if (o)
{
ASSERT(!o->next);
for(i=0; i<o->count; i++)
{
eattr *a = &o->attrs[i];
if (!(a->type & EAF_EMBEDDED))
mb_free(a->u.ptr);
}
mb_free(o);
}
}
static int
get_generic_attr(eattr *a, byte **buf, int buflen UNUSED)
{
if (a->id == EA_GEN_IGP_METRIC)
{
*buf += bsprintf(*buf, "igp_metric");
return GA_NAME;
}
return GA_UNKNOWN;
}
static inline void
opaque_format(struct adata *ad, byte *buf, unsigned int size)
{
byte *bound = buf + size - 10;
int i;
for(i = 0; i < ad->length; i++)
{
if (buf > bound)
{
strcpy(buf, " ...");
return;
}
if (i)
*buf++ = ' ';
buf += bsprintf(buf, "%02x", ad->data[i]);
}
*buf = 0;
return;
}
static inline void
ea_show_int_set(struct cli *c, struct adata *ad, int way, byte *pos, byte *buf, byte *end)
{
int i = int_set_format(ad, way, 0, pos, end - pos);
cli_printf(c, -1012, "%s", buf);
while (i)
{
i = int_set_format(ad, way, i, buf, end - buf - 1);
cli_printf(c, -1012, "\t%s", buf);
}
}
static inline void
ea_show_ec_set(struct cli *c, struct adata *ad, byte *pos, byte *buf, byte *end)
{
int i = ec_set_format(ad, 0, pos, end - pos);
cli_printf(c, -1012, "%s", buf);
while (i)
{
i = ec_set_format(ad, i, buf, end - buf - 1);
cli_printf(c, -1012, "\t%s", buf);
}
}
/**
* ea_show - print an &eattr to CLI
* @c: destination CLI
* @e: attribute to be printed
*
* This function takes an extended attribute represented by its &eattr
* structure and prints it to the CLI according to the type information.
*
* If the protocol defining the attribute provides its own
* get_attr() hook, it's consulted first.
*/
void
ea_show(struct cli *c, eattr *e)
{
struct protocol *p;
int status = GA_UNKNOWN;
struct adata *ad = (e->type & EAF_EMBEDDED) ? NULL : e->u.ptr;
byte buf[CLI_MSG_SIZE];
byte *pos = buf, *end = buf + sizeof(buf);
if (p = attr_class_to_protocol[EA_PROTO(e->id)])
{
pos += bsprintf(pos, "%s.", p->name);
if (p->get_attr)
status = p->get_attr(e, pos, end - pos);
pos += strlen(pos);
}
else if (EA_PROTO(e->id))
pos += bsprintf(pos, "%02x.", EA_PROTO(e->id));
else
status = get_generic_attr(e, &pos, end - pos);
if (status < GA_NAME)
pos += bsprintf(pos, "%02x", EA_ID(e->id));
if (status < GA_FULL)
{
*pos++ = ':';
*pos++ = ' ';
switch (e->type & EAF_TYPE_MASK)
{
case EAF_TYPE_INT:
bsprintf(pos, "%u", e->u.data);
break;
case EAF_TYPE_OPAQUE:
opaque_format(ad, pos, end - pos);
break;
case EAF_TYPE_IP_ADDRESS:
bsprintf(pos, "%I", *(ip_addr *) ad->data);
break;
case EAF_TYPE_ROUTER_ID:
bsprintf(pos, "%R", e->u.data);
break;
case EAF_TYPE_AS_PATH:
as_path_format(ad, pos, end - pos);
break;
case EAF_TYPE_INT_SET:
ea_show_int_set(c, ad, 1, pos, buf, end);
return;
case EAF_TYPE_EC_SET:
ea_show_ec_set(c, ad, pos, buf, end);
return;
case EAF_TYPE_UNDEF:
default:
bsprintf(pos, "<type %02x>", e->type);
}
}
cli_printf(c, -1012, "%s", buf);
}
/**
* ea_dump - dump an extended attribute
* @e: attribute to be dumped
*
* ea_dump() dumps contents of the extended attribute given to
* the debug output.
*/
void
ea_dump(ea_list *e)
{
int i;
if (!e)
{
debug("NONE");
return;
}
while (e)
{
debug("[%c%c%c]",
(e->flags & EALF_SORTED) ? 'S' : 's',
(e->flags & EALF_BISECT) ? 'B' : 'b',
(e->flags & EALF_CACHED) ? 'C' : 'c');
for(i=0; i<e->count; i++)
{
eattr *a = &e->attrs[i];
debug(" %02x:%02x.%02x", EA_PROTO(a->id), EA_ID(a->id), a->flags);
if (a->type & EAF_TEMP)
debug("T");
debug("=%c", "?iO?I?P???S?????" [a->type & EAF_TYPE_MASK]);
if (a->type & EAF_ORIGINATED)
debug("o");
if (a->type & EAF_EMBEDDED)
debug(":%08x", a->u.data);
else
{
int j, len = a->u.ptr->length;
debug("[%d]:", len);
for(j=0; j<len; j++)
debug("%02x", a->u.ptr->data[j]);
}
}
if (e = e->next)
debug(" | ");
}
}
/**
* ea_hash - calculate an &ea_list hash key
* @e: attribute list
*
* ea_hash() takes an extended attribute list and calculated a hopefully
* uniformly distributed hash value from its contents.
*/
inline unsigned int
ea_hash(ea_list *e)
{
u32 h = 0;
int i;
if (e) /* Assuming chain of length 1 */
{
for(i=0; i<e->count; i++)
{
struct eattr *a = &e->attrs[i];
h ^= a->id;
if (a->type & EAF_EMBEDDED)
h ^= a->u.data;
else
{
struct adata *d = a->u.ptr;
int size = d->length;
byte *z = d->data;
while (size >= 4)
{
h ^= *(u32 *)z;
z += 4;
size -= 4;
}
while (size--)
h = (h >> 24) ^ (h << 8) ^ *z++;
}
}
h ^= h >> 16;
h ^= h >> 6;
h &= 0xffff;
}
return h;
}
/**
* ea_append - concatenate &ea_list's
* @to: destination list (can be %NULL)
* @what: list to be appended (can be %NULL)
*
* This function appends the &ea_list @what at the end of
* &ea_list @to and returns a pointer to the resulting list.
*/
ea_list *
ea_append(ea_list *to, ea_list *what)
{
ea_list *res;
if (!to)
return what;
res = to;
while (to->next)
to = to->next;
to->next = what;
return res;
}
/*
* rta's
*/
static unsigned int rta_cache_count;
static unsigned int rta_cache_size = 32;
static unsigned int rta_cache_limit;
static unsigned int rta_cache_mask;
static rta **rta_hash_table;
static void
rta_alloc_hash(void)
{
rta_hash_table = mb_allocz(rta_pool, sizeof(rta *) * rta_cache_size);
if (rta_cache_size < 32768)
rta_cache_limit = rta_cache_size * 2;
else
rta_cache_limit = ~0;
rta_cache_mask = rta_cache_size - 1;
}
static inline unsigned int
rta_hash(rta *a)
{
return (a->proto->hash_key ^ ipa_hash(a->gw) ^
mpnh_hash(a->nexthops) ^ ea_hash(a->eattrs)) & 0xffff;
}
static inline int
rta_same(rta *x, rta *y)
{
return (x->proto == y->proto &&
x->source == y->source &&
x->scope == y->scope &&
x->cast == y->cast &&
x->dest == y->dest &&
x->flags == y->flags &&
x->igp_metric == y->igp_metric &&
ipa_equal(x->gw, y->gw) &&
ipa_equal(x->from, y->from) &&
x->iface == y->iface &&
x->hostentry == y->hostentry &&
mpnh_same(x->nexthops, y->nexthops) &&
ea_same(x->eattrs, y->eattrs));
}
static rta *
rta_copy(rta *o)
{
rta *r = sl_alloc(rta_slab);
memcpy(r, o, sizeof(rta));
r->uc = 1;
r->nexthops = mpnh_copy(o->nexthops);
r->eattrs = ea_list_copy(o->eattrs);
return r;
}
static inline void
rta_insert(rta *r)
{
unsigned int h = r->hash_key & rta_cache_mask;
r->next = rta_hash_table[h];
if (r->next)
r->next->pprev = &r->next;
r->pprev = &rta_hash_table[h];
rta_hash_table[h] = r;
}
static void
rta_rehash(void)
{
unsigned int ohs = rta_cache_size;
unsigned int h;
rta *r, *n;
rta **oht = rta_hash_table;
rta_cache_size = 2*rta_cache_size;
DBG("Rehashing rta cache from %d to %d entries.\n", ohs, rta_cache_size);
rta_alloc_hash();
for(h=0; h<ohs; h++)
for(r=oht[h]; r; r=n)
{
n = r->next;
rta_insert(r);
}
mb_free(oht);
}
/**
* rta_lookup - look up a &rta in attribute cache
* @o: a un-cached &rta
*
* rta_lookup() gets an un-cached &rta structure and returns its cached
* counterpart. It starts with examining the attribute cache to see whether
* there exists a matching entry. If such an entry exists, it's returned and
* its use count is incremented, else a new entry is created with use count
* set to 1.
*
* The extended attribute lists attached to the &rta are automatically
* converted to the normalized form.
*/
rta *
rta_lookup(rta *o)
{
rta *r;
unsigned int h;
ASSERT(!(o->aflags & RTAF_CACHED));
if (o->eattrs)
{
if (o->eattrs->next) /* Multiple ea_list's, need to merge them */
{
ea_list *ml = alloca(ea_scan(o->eattrs));
ea_merge(o->eattrs, ml);
o->eattrs = ml;
}
ea_sort(o->eattrs);
}
h = rta_hash(o);
for(r=rta_hash_table[h & rta_cache_mask]; r; r=r->next)
if (r->hash_key == h && rta_same(r, o))
return rta_clone(r);
r = rta_copy(o);
r->hash_key = h;
r->aflags = RTAF_CACHED;
rt_lock_hostentry(r->hostentry);
rta_insert(r);
if (++rta_cache_count > rta_cache_limit)
rta_rehash();
return r;
}
void
rta__free(rta *a)
{
ASSERT(rta_cache_count && (a->aflags & RTAF_CACHED));
rta_cache_count--;
*a->pprev = a->next;
if (a->next)
a->next->pprev = a->pprev;
a->aflags = 0; /* Poison the entry */
rt_unlock_hostentry(a->hostentry);
mpnh_free(a->nexthops);
ea_free(a->eattrs);
sl_free(rta_slab, a);
}
/**
* rta_dump - dump route attributes
* @a: attribute structure to dump
*
* This function takes a &rta and dumps its contents to the debug output.
*/
void
rta_dump(rta *a)
{
static char *rts[] = { "RTS_DUMMY", "RTS_STATIC", "RTS_INHERIT", "RTS_DEVICE",
"RTS_STAT_DEV", "RTS_REDIR", "RTS_RIP",
"RTS_OSPF", "RTS_OSPF_IA", "RTS_OSPF_EXT1",
"RTS_OSPF_EXT2", "RTS_BGP" };
static char *rtc[] = { "", " BC", " MC", " AC" };
static char *rtd[] = { "", " DEV", " HOLE", " UNREACH", " PROHIBIT" };
debug("p=%s uc=%d %s %s%s%s h=%04x",
a->proto->name, a->uc, rts[a->source], ip_scope_text(a->scope), rtc[a->cast],
rtd[a->dest], a->hash_key);
if (!(a->aflags & RTAF_CACHED))
debug(" !CACHED");
debug(" <-%I", a->from);
if (a->dest == RTD_ROUTER)
debug(" ->%I", a->gw);
if (a->dest == RTD_DEVICE || a->dest == RTD_ROUTER)
debug(" [%s]", a->iface ? a->iface->name : "???" );
if (a->eattrs)
{
debug(" EA: ");
ea_dump(a->eattrs);
}
}
/**
* rta_dump_all - dump attribute cache
*
* This function dumps the whole contents of route attribute cache
* to the debug output.
*/
void
rta_dump_all(void)
{
rta *a;
unsigned int h;
debug("Route attribute cache (%d entries, rehash at %d):\n", rta_cache_count, rta_cache_limit);
for(h=0; h<rta_cache_size; h++)
for(a=rta_hash_table[h]; a; a=a->next)
{
debug("%p ", a);
rta_dump(a);
debug("\n");
}
debug("\n");
}
void
rta_show(struct cli *c, rta *a, ea_list *eal)
{
static char *src_names[] = { "dummy", "static", "inherit", "device", "static-device", "redirect",
"RIP", "OSPF", "OSPF-IA", "OSPF-E1", "OSPF-E2", "BGP", "pipe" };
static char *cast_names[] = { "unicast", "broadcast", "multicast", "anycast" };
int i;
cli_printf(c, -1008, "\tType: %s %s %s", src_names[a->source], cast_names[a->cast], ip_scope_text(a->scope));
if (!eal)
eal = a->eattrs;
for(; eal; eal=eal->next)
for(i=0; i<eal->count; i++)
ea_show(c, &eal->attrs[i]);
}
/**
* rta_init - initialize route attribute cache
*
* This function is called during initialization of the routing
* table module to set up the internals of the attribute cache.
*/
void
rta_init(void)
{
rta_pool = rp_new(&root_pool, "Attributes");
rta_slab = sl_new(rta_pool, sizeof(rta));
mpnh_slab = sl_new(rta_pool, sizeof(struct mpnh));
rta_alloc_hash();
}
/*
* Documentation for functions declared inline in route.h
*/
#if 0
/**
* rta_clone - clone route attributes
* @r: a &rta to be cloned
*
* rta_clone() takes a cached &rta and returns its identical cached
* copy. Currently it works by just returning the original &rta with
* its use count incremented.
*/
static inline rta *rta_clone(rta *r)
{ DUMMY; }
/**
* rta_free - free route attributes
* @r: a &rta to be freed
*
* If you stop using a &rta (for example when deleting a route which uses
* it), you need to call rta_free() to notify the attribute cache the
* attribute is no longer in use and can be freed if you were the last
* user (which rta_free() tests by inspecting the use count).
*/
static inline void rta_free(rta *r)
{ DUMMY; }
#endif
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