bird/proto/radv/radv.c
Michal 'vorner' Vaner 2a95e63343 RAdv: Support for more specific routes (RFC 4191)
The patch implements Default Router Preferences and More-Specific Routes
(RFC 4191) for RAdv protocol, allowing to announce router preference and
more specific routes in router advertisements. Routes can be exported to
RAdv like to regular routing protocols.

Some cleanups, bugfixes and other changes done by Ondrej Zajicek.
2017-10-04 16:27:02 +02:00

751 lines
17 KiB
C

/*
* BIRD -- Router Advertisement
*
*
* Can be freely distributed and used under the terms of the GNU GPL.
*/
#include <stdlib.h>
#include "radv.h"
/**
* DOC: Router Advertisements
*
* The RAdv protocol is implemented in two files: |radv.c| containing the
* interface with BIRD core and the protocol logic and |packets.c| handling low
* level protocol stuff (RX, TX and packet formats). The protocol does not
* export any routes.
*
* The RAdv is structured in the usual way - for each handled interface there is
* a structure &radv_iface that contains a state related to that interface
* together with its resources (a socket, a timer). There is also a prepared RA
* stored in a TX buffer of the socket associated with an iface. These iface
* structures are created and removed according to iface events from BIRD core
* handled by radv_if_notify() callback.
*
* The main logic of RAdv consists of two functions: radv_iface_notify(), which
* processes asynchronous events (specified by RA_EV_* codes), and radv_timer(),
* which triggers sending RAs and computes the next timeout.
*
* The RAdv protocol could receive routes (through radv_import_control() and
* radv_rt_notify()), but only the configured trigger route is tracked (in
* &active var). When a radv protocol is reconfigured, the connected routing
* table is examined (in radv_check_active()) to have proper &active value in
* case of the specified trigger prefix was changed.
*
* Supported standards:
* - RFC 4861 - main RA standard
* - RFC 4191 - Default Router Preferences and More-Specific Routes
* - RFC 6106 - DNS extensions (RDDNS, DNSSL)
*/
static void radv_prune_prefixes(struct radv_iface *ifa);
static void radv_prune_routes(struct radv_proto *p);
/* Invalidate cached RA packet */
static inline void radv_invalidate(struct radv_iface *ifa)
{ ifa->plen = 0; }
static void
radv_timer(timer *tm)
{
struct radv_iface *ifa = tm->data;
struct radv_proto *p = ifa->ra;
RADV_TRACE(D_EVENTS, "Timer fired on %s", ifa->iface->name);
if (ifa->prune_time <= now)
radv_prune_prefixes(ifa);
if (p->prune_time <= now)
radv_prune_routes(p);
radv_send_ra(ifa);
/* Update timer */
ifa->last = now;
unsigned after = ifa->cf->min_ra_int;
after += random() % (ifa->cf->max_ra_int - ifa->cf->min_ra_int + 1);
if (ifa->initial)
ifa->initial--;
if (ifa->initial)
after = MIN(after, MAX_INITIAL_RTR_ADVERT_INTERVAL);
tm_start(ifa->timer, after);
}
static struct radv_prefix_config default_prefix = {
.onlink = 1,
.autonomous = 1,
.valid_lifetime = DEFAULT_VALID_LIFETIME,
.preferred_lifetime = DEFAULT_PREFERRED_LIFETIME
};
static struct radv_prefix_config dead_prefix = {
};
/* Find a corresponding config for the given prefix */
static struct radv_prefix_config *
radv_prefix_match(struct radv_iface *ifa, struct ifa *a)
{
struct radv_proto *p = ifa->ra;
struct radv_config *cf = (struct radv_config *) (p->p.cf);
struct radv_prefix_config *pc;
if (a->scope <= SCOPE_LINK)
return NULL;
WALK_LIST(pc, ifa->cf->pref_list)
if ((a->pxlen >= pc->pxlen) && ipa_in_net(a->prefix, pc->prefix, pc->pxlen))
return pc;
WALK_LIST(pc, cf->pref_list)
if ((a->pxlen >= pc->pxlen) && ipa_in_net(a->prefix, pc->prefix, pc->pxlen))
return pc;
return &default_prefix;
}
/*
* Go through the list of prefixes, compare them with configs and decide if we
* want them or not.
*/
static void
radv_prepare_prefixes(struct radv_iface *ifa)
{
struct radv_proto *p = ifa->ra;
struct radv_iface_config *cf = ifa->cf;
struct radv_prefix *pfx, *next;
/* First mark all the prefixes as unused */
WALK_LIST(pfx, ifa->prefixes)
pfx->mark = 0;
/* Find all the prefixes we want to use and make sure they are in the list. */
struct ifa *addr;
WALK_LIST(addr, ifa->iface->addrs)
{
struct radv_prefix_config *pc = radv_prefix_match(ifa, addr);
if (!pc || pc->skip)
continue;
/* Do we have it already? */
struct radv_prefix *existing = NULL;
WALK_LIST(pfx, ifa->prefixes)
if ((pfx->len == addr->pxlen) && ipa_equal(pfx->prefix, addr->prefix))
{
existing = pfx;
break;
}
if (!existing)
{
RADV_TRACE(D_EVENTS, "Adding new prefix %I/%d on %s",
addr->prefix, addr->pxlen, ifa->iface->name);
existing = mb_allocz(ifa->pool, sizeof *existing);
existing->prefix = addr->prefix;
existing->len = addr->pxlen;
add_tail(&ifa->prefixes, NODE existing);
}
/*
* Update the information (it may have changed, or even bring a prefix back
* to life).
*/
existing->alive = 1;
existing->mark = 1;
existing->cf = pc;
}
WALK_LIST_DELSAFE(pfx, next, ifa->prefixes)
{
if (pfx->alive && !pfx->mark)
{
RADV_TRACE(D_EVENTS, "Invalidating prefix %I/$d on %s",
pfx->prefix, pfx->len, ifa->iface->name);
pfx->alive = 0;
pfx->expires = now + cf->linger_time;
pfx->cf = &dead_prefix;
}
}
}
static void
radv_prune_prefixes(struct radv_iface *ifa)
{
struct radv_proto *p = ifa->ra;
bird_clock_t next = TIME_INFINITY;
int changed = 0;
struct radv_prefix *px, *pxn;
WALK_LIST_DELSAFE(px, pxn, ifa->prefixes)
{
if (!px->alive)
{
if (px->expires <= now)
{
RADV_TRACE(D_EVENTS, "Removing prefix %I/%d on %s",
px->prefix, px->len, ifa->iface->name);
rem_node(NODE px);
mb_free(px);
changed = 1;
}
else
next = MIN(next, px->expires);
}
}
if (changed)
radv_invalidate(ifa);
ifa->prune_time = next;
}
static char* ev_name[] = { NULL, "Init", "Change", "RS" };
void
radv_iface_notify(struct radv_iface *ifa, int event)
{
struct radv_proto *p = ifa->ra;
if (!ifa->sk)
return;
RADV_TRACE(D_EVENTS, "Event %s on %s", ev_name[event], ifa->iface->name);
switch (event)
{
case RA_EV_CHANGE:
radv_invalidate(ifa);
case RA_EV_INIT:
ifa->initial = MAX_INITIAL_RTR_ADVERTISEMENTS;
radv_prepare_prefixes(ifa);
radv_prune_prefixes(ifa);
break;
case RA_EV_RS:
break;
}
/* Update timer */
unsigned delta = now - ifa->last;
unsigned after = 0;
if (delta < ifa->cf->min_delay)
after = ifa->cf->min_delay - delta;
tm_start(ifa->timer, after);
}
static void
radv_iface_notify_all(struct radv_proto *p, int event)
{
struct radv_iface *ifa;
WALK_LIST(ifa, p->iface_list)
radv_iface_notify(ifa, event);
}
static struct radv_iface *
radv_iface_find(struct radv_proto *p, struct iface *what)
{
struct radv_iface *ifa;
WALK_LIST(ifa, p->iface_list)
if (ifa->iface == what)
return ifa;
return NULL;
}
static void
radv_iface_add(struct object_lock *lock)
{
struct radv_iface *ifa = lock->data;
struct radv_proto *p = ifa->ra;
if (! radv_sk_open(ifa))
{
log(L_ERR "%s: Socket open failed on interface %s", p->p.name, ifa->iface->name);
return;
}
radv_iface_notify(ifa, RA_EV_INIT);
}
static inline struct ifa *
find_lladdr(struct iface *iface)
{
struct ifa *a;
WALK_LIST(a, iface->addrs)
if (a->scope == SCOPE_LINK)
return a;
return NULL;
}
static void
radv_iface_new(struct radv_proto *p, struct iface *iface, struct radv_iface_config *cf)
{
struct radv_iface *ifa;
RADV_TRACE(D_EVENTS, "Adding interface %s", iface->name);
pool *pool = rp_new(p->p.pool, iface->name);
ifa = mb_allocz(pool, sizeof(struct radv_iface));
ifa->pool = pool;
ifa->ra = p;
ifa->cf = cf;
ifa->iface = iface;
init_list(&ifa->prefixes);
ifa->prune_time = TIME_INFINITY;
add_tail(&p->iface_list, NODE ifa);
ifa->addr = find_lladdr(iface);
if (!ifa->addr)
{
log(L_ERR "%s: Missing link-local address on interface %s", p->p.name, iface->name);
return;
}
timer *tm = tm_new(pool);
tm->hook = radv_timer;
tm->data = ifa;
tm->randomize = 0;
tm->recurrent = 0;
ifa->timer = tm;
struct object_lock *lock = olock_new(pool);
lock->type = OBJLOCK_IP;
lock->port = ICMPV6_PROTO;
lock->iface = iface;
lock->data = ifa;
lock->hook = radv_iface_add;
ifa->lock = lock;
olock_acquire(lock);
}
static void
radv_iface_remove(struct radv_iface *ifa)
{
struct radv_proto *p = ifa->ra;
RADV_TRACE(D_EVENTS, "Removing interface %s", ifa->iface->name);
rem_node(NODE ifa);
rfree(ifa->pool);
}
static void
radv_if_notify(struct proto *P, unsigned flags, struct iface *iface)
{
struct radv_proto *p = (struct radv_proto *) P;
struct radv_config *cf = (struct radv_config *) (P->cf);
if (iface->flags & IF_IGNORE)
return;
if (flags & IF_CHANGE_UP)
{
struct radv_iface_config *ic = (struct radv_iface_config *)
iface_patt_find(&cf->patt_list, iface, NULL);
if (ic)
radv_iface_new(p, iface, ic);
return;
}
struct radv_iface *ifa = radv_iface_find(p, iface);
if (!ifa)
return;
if (flags & IF_CHANGE_DOWN)
{
radv_iface_remove(ifa);
return;
}
if ((flags & IF_CHANGE_LINK) && (iface->flags & IF_LINK_UP))
radv_iface_notify(ifa, RA_EV_INIT);
}
static void
radv_ifa_notify(struct proto *P, unsigned flags UNUSED, struct ifa *a)
{
struct radv_proto *p = (struct radv_proto *) P;
if (a->flags & IA_SECONDARY)
return;
if (a->scope <= SCOPE_LINK)
return;
struct radv_iface *ifa = radv_iface_find(p, a->iface);
if (ifa)
radv_iface_notify(ifa, RA_EV_CHANGE);
}
static inline int radv_net_match_trigger(struct radv_config *cf, net *n)
{
return cf->trigger_valid &&
(n->n.pxlen == cf->trigger_pxlen) &&
ipa_equal(n->n.prefix, cf->trigger_prefix);
}
int
radv_import_control(struct proto *P, rte **new, ea_list **attrs UNUSED, struct linpool *pool UNUSED)
{
// struct radv_proto *p = (struct radv_proto *) P;
struct radv_config *cf = (struct radv_config *) (P->cf);
if (radv_net_match_trigger(cf, (*new)->net))
return RIC_PROCESS;
if (cf->propagate_routes)
return RIC_PROCESS;
else
return RIC_DROP;
}
static void
radv_rt_notify(struct proto *P, rtable *tbl UNUSED, net *n, rte *new, rte *old UNUSED, ea_list *attrs)
{
struct radv_proto *p = (struct radv_proto *) P;
struct radv_config *cf = (struct radv_config *) (P->cf);
struct radv_route *rt;
if (radv_net_match_trigger(cf, n))
{
u8 old_active = p->active;
p->active = !!new;
if (p->active == old_active)
return;
if (p->active)
RADV_TRACE(D_EVENTS, "Triggered");
else
RADV_TRACE(D_EVENTS, "Suppressed");
radv_iface_notify_all(p, RA_EV_CHANGE);
return;
}
if (!cf->propagate_routes)
return;
/*
* Some other route we want to send (or stop sending). Update the cache,
* with marking a removed one as dead or creating a new one as needed.
*
* And yes, we exclude the trigger route on purpose.
*/
if (new)
{
/* Update */
uint preference = ea_get_int(attrs, EA_RA_PREFERENCE, RA_PREF_MEDIUM);
uint lifetime = ea_get_int(attrs, EA_RA_LIFETIME, 0);
uint lifetime_set = !!ea_find(attrs, EA_RA_LIFETIME);
if ((preference != RA_PREF_LOW) &&
(preference != RA_PREF_MEDIUM) &&
(preference != RA_PREF_HIGH))
{
log(L_WARN "%s: Invalid ra_preference value %u on route %I/%d",
p->p.name, preference, n->n.prefix, n->n.pxlen);
preference = RA_PREF_MEDIUM;
lifetime = 0;
lifetime_set = 1;
}
rt = fib_get(&p->routes, &n->n.prefix, n->n.pxlen);
/* Ignore update if nothing changed */
if (rt->alive &&
(rt->preference == preference) &&
(rt->lifetime == lifetime) &&
(rt->lifetime_set == lifetime_set))
return;
if (p->routes.entries == 18)
log(L_WARN "%s: More than 17 routes exported to RAdv", p->p.name);
rt->alive = 1;
rt->preference = preference;
rt->lifetime = lifetime;
rt->lifetime_set = lifetime_set;
}
else
{
/* Withdraw */
rt = fib_find(&p->routes, &n->n.prefix, n->n.pxlen);
if (!rt || !rt->alive)
return;
/* Invalidate the route */
rt->alive = 0;
rt->expires = now + cf->route_linger_time;
p->prune_time = MIN(p->prune_time, rt->expires);
}
radv_iface_notify_all(p, RA_EV_CHANGE);
}
/*
* Cleans up all the dead routes that expired and schedules itself to be run
* again if there are more routes waiting for expiration.
*/
static void
radv_prune_routes(struct radv_proto *p)
{
bird_clock_t next = TIME_INFINITY;
int changed = 0;
/* Should not happen */
if (!p->fib_up)
return;
struct fib_iterator fit;
FIB_ITERATE_INIT(&fit, &p->routes);
again:
FIB_ITERATE_START(&p->routes, &fit, node)
{
struct radv_route *rt = (void *) node;
if (!rt->alive)
{
/* Delete expired nodes */
if (rt->expires <= now)
{
FIB_ITERATE_PUT(&fit, node);
fib_delete(&p->routes, node);
changed = 1;
goto again;
}
else
next = MIN(next, rt->expires);
}
}
FIB_ITERATE_END(node);
if (changed)
{
struct radv_iface *ifa;
WALK_LIST(ifa, p->iface_list)
radv_invalidate(ifa);
}
p->prune_time = next;
}
static int
radv_check_active(struct radv_proto *p)
{
struct radv_config *cf = (struct radv_config *) (p->p.cf);
if (! cf->trigger_valid)
return 1;
return rt_examine(p->p.table, cf->trigger_prefix, cf->trigger_pxlen,
&(p->p), p->p.cf->out_filter);
}
static struct proto *
radv_init(struct proto_config *c)
{
struct proto *P = proto_new(c, sizeof(struct radv_proto));
P->accept_ra_types = RA_OPTIMAL;
P->import_control = radv_import_control;
P->rt_notify = radv_rt_notify;
P->if_notify = radv_if_notify;
P->ifa_notify = radv_ifa_notify;
return P;
}
static void
radv_set_fib(struct radv_proto *p, int up)
{
if (up == p->fib_up)
return;
if (up)
fib_init(&p->routes, p->p.pool, sizeof(struct radv_route), 4, NULL);
else
fib_free(&p->routes);
p->fib_up = up;
p->prune_time = TIME_INFINITY;
}
static int
radv_start(struct proto *P)
{
struct radv_proto *p = (struct radv_proto *) P;
struct radv_config *cf = (struct radv_config *) (P->cf);
init_list(&(p->iface_list));
p->valid = 1;
p->active = !cf->trigger_valid;
p->fib_up = 0;
radv_set_fib(p, cf->propagate_routes);
p->prune_time = TIME_INFINITY;
return PS_UP;
}
static inline void
radv_iface_shutdown(struct radv_iface *ifa)
{
if (ifa->sk)
{
radv_invalidate(ifa);
radv_send_ra(ifa);
}
}
static int
radv_shutdown(struct proto *P)
{
struct radv_proto *p = (struct radv_proto *) P;
p->valid = 0;
struct radv_iface *ifa;
WALK_LIST(ifa, p->iface_list)
radv_iface_shutdown(ifa);
return PS_DOWN;
}
static int
radv_reconfigure(struct proto *P, struct proto_config *c)
{
struct radv_proto *p = (struct radv_proto *) P;
struct radv_config *old = (struct radv_config *) (P->cf);
struct radv_config *new = (struct radv_config *) c;
P->cf = c; /* radv_check_active() requires proper P->cf */
p->active = radv_check_active(p);
/* Allocate or free FIB */
radv_set_fib(p, new->propagate_routes);
/* We started to accept routes so we need to refeed them */
if (!old->propagate_routes && new->propagate_routes)
proto_request_feeding(&p->p);
struct iface *iface;
WALK_LIST(iface, iface_list)
{
struct radv_iface *ifa = radv_iface_find(p, iface);
struct radv_iface_config *ic = (struct radv_iface_config *)
iface_patt_find(&new->patt_list, iface, NULL);
if (ifa && ic)
{
ifa->cf = ic;
/* We cheat here - always notify the change even if there isn't
any. That would leads just to a few unnecessary RAs. */
radv_iface_notify(ifa, RA_EV_CHANGE);
}
if (ifa && !ic)
{
radv_iface_shutdown(ifa);
radv_iface_remove(ifa);
}
if (!ifa && ic)
radv_iface_new(p, iface, ic);
}
return 1;
}
static void
radv_copy_config(struct proto_config *dest, struct proto_config *src)
{
struct radv_config *d = (struct radv_config *) dest;
struct radv_config *s = (struct radv_config *) src;
/* We clean up patt_list, ifaces are non-sharable */
init_list(&d->patt_list);
/* We copy pref_list, shallow copy suffices */
cfg_copy_list(&d->pref_list, &s->pref_list, sizeof(struct radv_prefix_config));
}
static void
radv_get_status(struct proto *P, byte *buf)
{
struct radv_proto *p = (struct radv_proto *) P;
if (!p->active)
strcpy(buf, "Suppressed");
}
static const char *
radv_pref_str(u32 pref)
{
switch (pref)
{
case RA_PREF_LOW:
return "low";
case RA_PREF_MEDIUM:
return "medium";
case RA_PREF_HIGH:
return "high";
default:
return "??";
}
}
/* The buffer has some minimal size */
static int
radv_get_attr(eattr *a, byte *buf, int buflen UNUSED)
{
switch (a->id)
{
case EA_RA_PREFERENCE:
bsprintf(buf, "preference: %s", radv_pref_str(a->u.data));
return GA_FULL;
case EA_RA_LIFETIME:
bsprintf(buf, "lifetime");
return GA_NAME;
default:
return GA_UNKNOWN;
}
}
struct protocol proto_radv = {
.name = "RAdv",
.template = "radv%d",
.attr_class = EAP_RADV,
.config_size = sizeof(struct radv_config),
.init = radv_init,
.start = radv_start,
.shutdown = radv_shutdown,
.reconfigure = radv_reconfigure,
.copy_config = radv_copy_config,
.get_status = radv_get_status,
.get_attr = radv_get_attr
};