bird/sysdep/unix/krt.c

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/*
* BIRD -- UNIX Kernel Synchronization
*
* (c) 1998--2000 Martin Mares <mj@ucw.cz>
*
* Can be freely distributed and used under the terms of the GNU GPL.
*/
/**
* DOC: Kernel synchronization
*
* This system dependent module implements the Kernel and Device protocol,
* that is synchronization of interface lists and routing tables with the
* OS kernel.
*
* The whole kernel synchronization is a bit messy and touches some internals
* of the routing table engine, because routing table maintenance is a typical
* example of the proverbial compatibility between different Unices and we want
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* to keep the overhead of our KRT business as low as possible and avoid maintaining
* a local routing table copy.
*
* The kernel syncer can work in three different modes (according to system config header):
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* Either with a single routing table and single KRT protocol [traditional UNIX]
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* or with many routing tables and separate KRT protocols for all of them
* or with many routing tables, but every scan including all tables, so we start
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* separate KRT protocols which cooperate with each other [Linux 2.2].
* In this case, we keep only a single scan timer.
*
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* We use FIB node flags in the routing table to keep track of route
* synchronization status. We also attach temporary &rte's to the routing table,
* but it cannot do any harm to the rest of BIRD since table synchronization is
* an atomic process.
*
* When starting up, we cheat by looking if there is another
* KRT instance to be initialized later and performing table scan
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* only once for all the instances.
*/
/*
* If you are brave enough, continue now. You cannot say you haven't been warned.
*/
#undef LOCAL_DEBUG
#include "nest/bird.h"
#include "nest/iface.h"
#include "nest/route.h"
#include "nest/protocol.h"
#include "lib/timer.h"
#include "conf/conf.h"
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#include "lib/string.h"
#include "unix.h"
#include "krt.h"
static int krt_uptodate(rte *k, rte *e);
/*
* Global resources
*/
pool *krt_pool;
void
krt_io_init(void)
{
krt_pool = rp_new(&root_pool, "Kernel Syncer");
krt_if_io_init();
}
/*
* Interfaces
*/
struct proto_config *cf_kif;
static struct kif_proto *kif_proto;
static timer *kif_scan_timer;
static bird_clock_t kif_last_shot;
static void
kif_preconfig(struct protocol *P UNUSED, struct config *c UNUSED)
{
cf_kif = NULL;
}
static void
kif_scan(timer *t)
{
struct kif_proto *p = t->data;
KRT_TRACE(p, D_EVENTS, "Scanning interfaces");
kif_last_shot = now;
krt_if_scan(p);
}
static void
kif_force_scan(void)
{
if (kif_proto && kif_last_shot + 2 < now)
{
kif_scan(kif_scan_timer);
tm_start(kif_scan_timer, ((struct kif_config *) kif_proto->p.cf)->scan_time);
}
}
static struct proto *
kif_init(struct proto_config *c)
{
struct kif_proto *p = proto_new(c, sizeof(struct kif_proto));
return &p->p;
}
static int
kif_start(struct proto *P)
{
struct kif_proto *p = (struct kif_proto *) P;
kif_proto = p;
krt_if_start(p);
/* Start periodic interface scanning */
kif_scan_timer = tm_new(P->pool);
kif_scan_timer->hook = kif_scan;
kif_scan_timer->data = p;
kif_scan_timer->recurrent = KIF_CF->scan_time;
kif_scan(kif_scan_timer);
tm_start(kif_scan_timer, KIF_CF->scan_time);
return PS_UP;
}
static int
kif_shutdown(struct proto *P)
{
struct kif_proto *p = (struct kif_proto *) P;
tm_stop(kif_scan_timer);
krt_if_shutdown(p);
kif_proto = NULL;
if_start_update(); /* Remove all interfaces */
if_end_update();
/*
* FIXME: Is it really a good idea? It causes routes to be flushed,
* but at the same time it avoids sending of these deletions to the kernel,
* because krt thinks the kernel itself has already removed the route
* when downing the interface. Sad.
*/
return PS_DOWN;
}
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static int
kif_reconfigure(struct proto *p, struct proto_config *new)
{
struct kif_config *o = (struct kif_config *) p->cf;
struct kif_config *n = (struct kif_config *) new;
if (!kif_params_same(&o->iface, &n->iface))
return 0;
if (o->scan_time != n->scan_time)
{
tm_stop(kif_scan_timer);
kif_scan_timer->recurrent = n->scan_time;
kif_scan(kif_scan_timer);
tm_start(kif_scan_timer, n->scan_time);
}
return 1;
}
struct protocol proto_unix_iface = {
name: "Device",
template: "device%d",
preconfig: kif_preconfig,
init: kif_init,
start: kif_start,
shutdown: kif_shutdown,
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reconfigure: kif_reconfigure,
};
/*
* Tracing of routes
*/
static void
krt_trace_in_print(struct krt_proto *p, rte *e, char *msg)
{
DBG("KRT: %I/%d: %s\n", e->net->n.prefix, e->net->n.pxlen, msg);
log(L_TRACE "%s: %I/%d: %s", p->p.name, e->net->n.prefix, e->net->n.pxlen, msg);
}
static inline void
krt_trace_in(struct krt_proto *p, rte *e, char *msg)
{
if (p->p.debug & D_PACKETS)
krt_trace_in_print(p, e, msg);
}
/*
* Inherited Routes
*/
#ifdef KRT_ALLOW_LEARN
static inline int
krt_same_key(rte *a, rte *b)
{
return a->u.krt.proto == b->u.krt.proto &&
a->u.krt.metric == b->u.krt.metric &&
a->u.krt.type == b->u.krt.type;
}
static void
krt_learn_announce_update(struct krt_proto *p, rte *e)
{
net *n = e->net;
rta *aa = rta_clone(e->attrs);
rte *ee = rte_get_temp(aa);
net *nn = net_get(p->p.table, n->n.prefix, n->n.pxlen);
ee->net = nn;
ee->pflags = 0;
ee->pref = p->p.preference;
ee->u.krt = e->u.krt;
rte_update(p->p.table, nn, &p->p, ee);
}
static void
krt_learn_announce_delete(struct krt_proto *p, net *n)
{
n = net_find(p->p.table, n->n.prefix, n->n.pxlen);
if (n)
rte_update(p->p.table, n, &p->p, NULL);
}
static void
krt_learn_scan(struct krt_proto *p, rte *e)
{
net *n0 = e->net;
net *n = net_get(&p->krt_table, n0->n.prefix, n0->n.pxlen);
rte *m, **mm;
e->attrs->source = RTS_INHERIT;
for(mm=&n->routes; m = *mm; mm=&m->next)
if (krt_same_key(m, e))
break;
if (m)
{
if (krt_uptodate(m, e))
{
krt_trace_in(p, e, "[alien] seen");
rte_free(e);
m->u.krt.seen = 1;
}
else
{
krt_trace_in(p, e, "[alien] updated");
*mm = m->next;
rte_free(m);
m = NULL;
}
}
else
krt_trace_in(p, e, "[alien] created");
if (!m)
{
e->attrs = rta_lookup(e->attrs);
e->next = n->routes;
n->routes = e;
e->u.krt.seen = 1;
}
}
static void
krt_learn_prune(struct krt_proto *p)
{
struct fib *fib = &p->krt_table.fib;
struct fib_iterator fit;
KRT_TRACE(p, D_EVENTS, "Pruning inherited routes");
FIB_ITERATE_INIT(&fit, fib);
again:
FIB_ITERATE_START(fib, &fit, f)
{
net *n = (net *) f;
rte *e, **ee, *best, **pbest, *old_best;
old_best = n->routes;
best = NULL;
pbest = NULL;
ee = &n->routes;
while (e = *ee)
{
if (!e->u.krt.seen)
{
*ee = e->next;
rte_free(e);
continue;
}
if (!best || best->u.krt.metric > e->u.krt.metric)
{
best = e;
pbest = ee;
}
e->u.krt.seen = 0;
ee = &e->next;
}
if (!n->routes)
{
DBG("%I/%d: deleting\n", n->n.prefix, n->n.pxlen);
if (old_best)
{
krt_learn_announce_delete(p, n);
n->n.flags &= ~KRF_INSTALLED;
}
FIB_ITERATE_PUT(&fit, f);
fib_delete(fib, f);
goto again;
}
*pbest = best->next;
best->next = n->routes;
n->routes = best;
if (best != old_best || !(n->n.flags & KRF_INSTALLED))
{
DBG("%I/%d: announcing (metric=%d)\n", n->n.prefix, n->n.pxlen, best->u.krt.metric);
krt_learn_announce_update(p, best);
n->n.flags |= KRF_INSTALLED;
}
else
DBG("%I/%d: uptodate (metric=%d)\n", n->n.prefix, n->n.pxlen, best->u.krt.metric);
}
FIB_ITERATE_END(f);
}
static void
krt_learn_async(struct krt_proto *p, rte *e, int new)
{
net *n0 = e->net;
net *n = net_get(&p->krt_table, n0->n.prefix, n0->n.pxlen);
rte *g, **gg, *best, **bestp, *old_best;
e->attrs->source = RTS_INHERIT;
old_best = n->routes;
for(gg=&n->routes; g = *gg; gg = &g->next)
if (krt_same_key(g, e))
break;
if (new)
{
if (g)
{
if (krt_uptodate(g, e))
{
krt_trace_in(p, e, "[alien async] same");
rte_free(e);
return;
}
krt_trace_in(p, e, "[alien async] updated");
*gg = g->next;
rte_free(g);
}
else
krt_trace_in(p, e, "[alien async] created");
e->attrs = rta_lookup(e->attrs);
e->next = n->routes;
n->routes = e;
}
else if (!g)
{
krt_trace_in(p, e, "[alien async] delete failed");
rte_free(e);
return;
}
else
{
krt_trace_in(p, e, "[alien async] removed");
*gg = g->next;
rte_free(e);
rte_free(g);
}
best = n->routes;
bestp = &n->routes;
for(gg=&n->routes; g=*gg; gg=&g->next)
if (best->u.krt.metric > g->u.krt.metric)
{
best = g;
bestp = gg;
}
if (best)
{
*bestp = best->next;
best->next = n->routes;
n->routes = best;
}
if (best != old_best)
{
DBG("krt_learn_async: distributing change\n");
if (best)
{
krt_learn_announce_update(p, best);
n->n.flags |= KRF_INSTALLED;
}
else
{
n->routes = NULL;
krt_learn_announce_delete(p, n);
n->n.flags &= ~KRF_INSTALLED;
}
}
}
static void
krt_learn_init(struct krt_proto *p)
{
if (KRT_CF->learn)
rt_setup(p->p.pool, &p->krt_table, "Inherited", NULL);
}
static void
krt_dump(struct proto *P)
{
struct krt_proto *p = (struct krt_proto *) P;
if (!KRT_CF->learn)
return;
debug("KRT: Table of inheritable routes\n");
rt_dump(&p->krt_table);
}
static void
krt_dump_attrs(rte *e)
{
debug(" [m=%d,p=%d,t=%d]", e->u.krt.metric, e->u.krt.proto, e->u.krt.type);
}
#endif
/*
* Routes
*/
#ifdef CONFIG_ALL_TABLES_AT_ONCE
static timer *krt_scan_timer;
static int krt_instance_count;
static list krt_instance_list;
#endif
static void
krt_flush_routes(struct krt_proto *p)
{
struct rtable *t = p->p.table;
KRT_TRACE(p, D_EVENTS, "Flushing kernel routes");
FIB_WALK(&t->fib, f)
{
net *n = (net *) f;
rte *e = n->routes;
if (e)
{
rta *a = e->attrs;
if (a->source != RTS_DEVICE && a->source != RTS_INHERIT)
krt_set_notify(p, e->net, NULL, e);
}
}
FIB_WALK_END;
}
static int
krt_uptodate(rte *k, rte *e)
{
rta *ka = k->attrs, *ea = e->attrs;
if (ka->dest != ea->dest)
return 0;
switch (ka->dest)
{
case RTD_ROUTER:
return ipa_equal(ka->gw, ea->gw);
case RTD_DEVICE:
return !strcmp(ka->iface->name, ea->iface->name);
default:
return 1;
}
}
/*
* This gets called back when the low-level scanning code discovers a route.
* We expect that the route is a temporary rte and its attributes are uncached.
*/
void
krt_got_route(struct krt_proto *p, rte *e)
{
rte *old;
net *net = e->net;
int verdict;
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#ifdef KRT_ALLOW_LEARN
int src = e->u.krt.src;
#endif
#ifdef CONFIG_AUTO_ROUTES
if (e->attrs->dest == RTD_DEVICE)
{
/* It's a device route. Probably a kernel-generated one. */
verdict = KRF_IGNORE;
goto sentenced;
}
#endif
#ifdef KRT_ALLOW_LEARN
if (src == KRT_SRC_ALIEN)
{
if (KRT_CF->learn)
krt_learn_scan(p, e);
else
{
krt_trace_in(p, e, "alien route, ignored");
rte_free(e);
}
return;
}
#endif
if (net->n.flags & KRF_VERDICT_MASK)
{
/* Route to this destination was already seen. Strange, but it happens... */
krt_trace_in(p, e, "already seen");
rte_free(e);
return;
}
if (net->n.flags & KRF_INSTALLED)
{
old = net->routes;
ASSERT(old);
if (krt_uptodate(e, old))
verdict = KRF_SEEN;
else
verdict = KRF_UPDATE;
}
else
verdict = KRF_DELETE;
sentenced:
krt_trace_in(p, e, ((char *[]) { "?", "seen", "will be updated", "will be removed", "ignored" }) [verdict]);
net->n.flags = (net->n.flags & ~KRF_VERDICT_MASK) | verdict;
if (verdict == KRF_UPDATE || verdict == KRF_DELETE)
{
/* Get a cached copy of attributes and link the route */
rta *a = e->attrs;
a->source = RTS_DUMMY;
e->attrs = rta_lookup(a);
e->next = net->routes;
net->routes = e;
}
else
rte_free(e);
}
static void
krt_prune(struct krt_proto *p)
{
struct rtable *t = p->p.table;
KRT_TRACE(p, D_EVENTS, "Pruning table %s", t->name);
FIB_WALK(&t->fib, f)
{
net *n = (net *) f;
int verdict = f->flags & KRF_VERDICT_MASK;
rte *new, *old;
if (verdict != KRF_CREATE && verdict != KRF_SEEN && verdict != KRF_IGNORE)
{
old = n->routes;
n->routes = old->next;
}
else
old = NULL;
new = n->routes;
switch (verdict)
{
case KRF_CREATE:
if (new && (f->flags & KRF_INSTALLED))
{
krt_trace_in(p, new, "reinstalling");
krt_set_notify(p, n, new, NULL);
}
break;
case KRF_SEEN:
case KRF_IGNORE:
/* Nothing happens */
break;
case KRF_UPDATE:
krt_trace_in(p, new, "updating");
krt_set_notify(p, n, new, old);
break;
case KRF_DELETE:
krt_trace_in(p, old, "deleting");
krt_set_notify(p, n, NULL, old);
break;
default:
bug("krt_prune: invalid route status");
}
if (old)
rte_free(old);
f->flags &= ~KRF_VERDICT_MASK;
}
FIB_WALK_END;
#ifdef KRT_ALLOW_LEARN
if (KRT_CF->learn)
krt_learn_prune(p);
#endif
p->initialized = 1;
}
void
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krt_got_route_async(struct krt_proto *p, rte *e, int new
#ifndef KRT_ALLOW_LEARN
UNUSED
#endif
)
{
net *net = e->net;
int src = e->u.krt.src;
switch (src)
{
case KRT_SRC_BIRD:
ASSERT(0); /* Should be filtered by the back end */
case KRT_SRC_REDIRECT:
DBG("It's a redirect, kill him! Kill! Kill!\n");
krt_set_notify(p, net, NULL, e);
break;
case KRT_SRC_ALIEN:
#ifdef KRT_ALLOW_LEARN
if (KRT_CF->learn)
{
krt_learn_async(p, e, new);
return;
}
#endif
}
rte_free(e);
}
/*
* Periodic scanning
*/
static void
krt_scan(timer *t UNUSED)
{
struct krt_proto *p;
kif_force_scan();
#ifdef CONFIG_ALL_TABLES_AT_ONCE
{
void *q;
/* We need some node to decide whether to print the debug messages or not */
p = SKIP_BACK(struct krt_proto, instance_node, HEAD(krt_instance_list));
if (p->instance_node.next)
KRT_TRACE(p, D_EVENTS, "Scanning routing table");
krt_scan_fire(NULL);
WALK_LIST(q, krt_instance_list)
{
p = SKIP_BACK(struct krt_proto, instance_node, q);
krt_prune(p);
}
}
#else
p = t->data;
KRT_TRACE(p, D_EVENTS, "Scanning routing table");
krt_scan_fire(p);
krt_prune(p);
#endif
}
/*
* Updates
*/
static void
krt_notify(struct proto *P, net *net, rte *new, rte *old, struct ea_list *attrs UNUSED)
{
struct krt_proto *p = (struct krt_proto *) P;
if (shutting_down && KRT_CF->persist)
return;
if (new && (!krt_capable(new) || new->attrs->source == RTS_INHERIT))
new = NULL;
if (!(net->n.flags & KRF_INSTALLED))
old = NULL;
if (new)
net->n.flags |= KRF_INSTALLED;
else
net->n.flags &= ~KRF_INSTALLED;
if (p->initialized) /* Before first scan we don't touch the routes */
krt_set_notify(p, net, new, old);
}
/*
* Protocol glue
*/
struct proto_config *cf_krt;
static void
krt_preconfig(struct protocol *P UNUSED, struct config *c)
{
cf_krt = NULL;
krt_scan_preconfig(c);
}
static void
krt_postconfig(struct proto_config *C)
{
struct krt_config *c = (struct krt_config *) C;
#ifdef CONFIG_ALL_TABLES_AT_ONCE
struct krt_config *first = (struct krt_config *) cf_krt;
if (first->scan_time != c->scan_time)
cf_error("All kernel syncers must use the same table scan interval");
#endif
if (C->table->krt_attached)
cf_error("Kernel syncer (%s) already attached to table %s", C->table->krt_attached->name, C->table->name);
C->table->krt_attached = C;
krt_scan_postconfig(c);
}
static timer *
krt_start_timer(struct krt_proto *p)
{
timer *t;
t = tm_new(p->krt_pool);
t->hook = krt_scan;
t->data = p;
t->recurrent = KRT_CF->scan_time;
tm_start(t, 0);
return t;
}
static int
krt_start(struct proto *P)
{
struct krt_proto *p = (struct krt_proto *) P;
int first = 1;
#ifdef CONFIG_ALL_TABLES_AT_ONCE
if (!krt_instance_count++)
init_list(&krt_instance_list);
else
first = 0;
p->krt_pool = krt_pool;
add_tail(&krt_instance_list, &p->instance_node);
#else
p->krt_pool = P->pool;
#endif
#ifdef KRT_ALLOW_LEARN
krt_learn_init(p);
#endif
krt_scan_start(p, first);
krt_set_start(p, first);
/* Start periodic routing table scanning */
#ifdef CONFIG_ALL_TABLES_AT_ONCE
if (first)
krt_scan_timer = krt_start_timer(p);
else
tm_start(p->scan_timer, 0);
p->scan_timer = krt_scan_timer;
#else
p->scan_timer = krt_start_timer(p);
#endif
return PS_UP;
}
static int
krt_shutdown(struct proto *P)
{
struct krt_proto *p = (struct krt_proto *) P;
int last = 1;
#ifdef CONFIG_ALL_TABLES_AT_ONCE
rem_node(&p->instance_node);
if (--krt_instance_count)
last = 0;
else
#endif
tm_stop(p->scan_timer);
if (!KRT_CF->persist)
krt_flush_routes(p);
krt_set_shutdown(p, last);
krt_scan_shutdown(p, last);
#ifdef CONFIG_ALL_TABLES_AT_ONCE
if (last)
rfree(krt_scan_timer);
#endif
return PS_DOWN;
}
static struct proto *
krt_init(struct proto_config *c)
{
struct krt_proto *p = proto_new(c, sizeof(struct krt_proto));
p->p.rt_notify = krt_notify;
p->p.min_scope = SCOPE_HOST;
return &p->p;
}
static int
krt_reconfigure(struct proto *p, struct proto_config *new)
{
struct krt_config *o = (struct krt_config *) p->cf;
struct krt_config *n = (struct krt_config *) new;
return o->scan_time == n->scan_time
&& o->learn == n->learn /* persist needn't be the same */
&& krt_set_params_same(&o->set, &n->set)
&& krt_scan_params_same(&o->scan, &n->scan)
;
}
struct protocol proto_unix_kernel = {
name: "Kernel",
template: "kernel%d",
preconfig: krt_preconfig,
postconfig: krt_postconfig,
init: krt_init,
start: krt_start,
shutdown: krt_shutdown,
reconfigure: krt_reconfigure,
#ifdef KRT_ALLOW_LEARN
dump: krt_dump,
dump_attrs: krt_dump_attrs,
#endif
};