bird/proto/radv/radv.c
Ondrej Zajicek 36da2857bc Implements router advertisements activated by received routes.
The RAdv protocol could be configured to change its behavior based on
availability of routes, e.g., do not announce router lifetime when a
default route is not available.
2013-02-08 23:58:27 +01:00

434 lines
9.9 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 import or 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 6106 - DNS extensions (RDDNS, DNSSL)
*/
static void
radv_timer(timer *tm)
{
struct radv_iface *ifa = tm->data;
struct proto_radv *ra = ifa->ra;
RADV_TRACE(D_EVENTS, "Timer fired on %s", ifa->iface->name);
radv_send_ra(ifa, 0);
/* 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 char* ev_name[] = { NULL, "Init", "Change", "RS" };
void
radv_iface_notify(struct radv_iface *ifa, int event)
{
struct proto_radv *ra = 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:
ifa->plen = 0;
case RA_EV_INIT:
ifa->initial = MAX_INITIAL_RTR_ADVERTISEMENTS;
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 proto_radv *ra, int event)
{
struct radv_iface *ifa;
WALK_LIST(ifa, ra->iface_list)
radv_iface_notify(ifa, event);
}
static struct radv_iface *
radv_iface_find(struct proto_radv *ra, struct iface *what)
{
struct radv_iface *ifa;
WALK_LIST(ifa, ra->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 proto_radv *ra = ifa->ra;
if (! radv_sk_open(ifa))
{
log(L_ERR "%s: Socket open failed on interface %s", ra->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 proto_radv *ra, struct iface *iface, struct radv_iface_config *cf)
{
pool *pool = ra->p.pool;
struct radv_iface *ifa;
RADV_TRACE(D_EVENTS, "Adding interface %s", iface->name);
ifa = mb_allocz(pool, sizeof(struct radv_iface));
ifa->ra = ra;
ifa->cf = cf;
ifa->iface = iface;
add_tail(&ra->iface_list, NODE ifa);
ifa->addr = find_lladdr(iface);
if (!ifa->addr)
{
log(L_ERR "%s: Cannot find link-locad addr on interface %s", ra->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->addr = IPA_NONE;
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 proto_radv *ra = ifa->ra;
RADV_TRACE(D_EVENTS, "Removing interface %s", ifa->iface->name);
rem_node(NODE ifa);
rfree(ifa->sk);
rfree(ifa->timer);
rfree(ifa->lock);
mb_free(ifa);
}
static void
radv_if_notify(struct proto *p, unsigned flags, struct iface *iface)
{
struct proto_radv *ra = (struct proto_radv *) 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(ra, iface, ic);
return;
}
struct radv_iface *ifa = radv_iface_find(ra, 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, struct ifa *a)
{
struct proto_radv *ra = (struct proto_radv *) p;
if (a->flags & IA_SECONDARY)
return;
if (a->scope <= SCOPE_LINK)
return;
struct radv_iface *ifa = radv_iface_find(ra, 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 proto_radv *ra = (struct proto_radv *) p;
struct radv_config *cf = (struct radv_config *) (p->cf);
if (radv_net_match_trigger(cf, (*new)->net))
return RIC_PROCESS;
return RIC_DROP;
}
static void
radv_rt_notify(struct proto *p, rtable *tbl UNUSED, net *n, rte *new, rte *old UNUSED, ea_list *attrs UNUSED)
{
struct proto_radv *ra = (struct proto_radv *) p;
struct radv_config *cf = (struct radv_config *) (p->cf);
if (radv_net_match_trigger(cf, n))
{
u8 old_active = ra->active;
ra->active = !!new;
if (ra->active == old_active)
return;
if (ra->active)
RADV_TRACE(D_EVENTS, "Triggered");
else
RADV_TRACE(D_EVENTS, "Suppressed");
radv_iface_notify_all(ra, RA_EV_CHANGE);
}
}
static int
radv_check_active(struct proto_radv *ra)
{
struct radv_config *cf = (struct radv_config *) (ra->p.cf);
if (! cf->trigger_valid)
return 1;
return rt_examine(ra->p.table, cf->trigger_prefix, cf->trigger_pxlen,
&(ra->p), ra->p.cf->out_filter);
}
static struct proto *
radv_init(struct proto_config *c)
{
struct proto *p = proto_new(c, sizeof(struct proto_radv));
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 int
radv_start(struct proto *p)
{
struct proto_radv *ra = (struct proto_radv *) p;
struct radv_config *cf = (struct radv_config *) (p->cf);
init_list(&(ra->iface_list));
ra->active = !cf->trigger_valid;
return PS_UP;
}
static inline void
radv_iface_shutdown(struct radv_iface *ifa)
{
if (ifa->sk)
radv_send_ra(ifa, 1);
}
static int
radv_shutdown(struct proto *p)
{
struct proto_radv *ra = (struct proto_radv *) p;
struct radv_iface *ifa;
WALK_LIST(ifa, ra->iface_list)
radv_iface_shutdown(ifa);
return PS_DOWN;
}
static int
radv_reconfigure(struct proto *p, struct proto_config *c)
{
struct proto_radv *ra = (struct proto_radv *) p;
// struct radv_config *old = (struct radv_config *) (p->cf);
struct radv_config *new = (struct radv_config *) c;
/*
* The question is why there is a reconfigure function for RAdv if
* it has almost none internal state so restarting the protocol
* would probably suffice. One small reason is that restarting the
* protocol would lead to sending a RA with Router Lifetime 0
* causing nodes to temporary remove their default routes.
*/
p->cf = c; /* radv_check_active() requires proper p->cf */
ra->active = radv_check_active(ra);
struct iface *iface;
WALK_LIST(iface, iface_list)
{
struct radv_iface *ifa = radv_iface_find(ra, 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(ra, 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 proto_radv *ra = (struct proto_radv *) p;
if (!ra->active)
strcpy(buf, "Suppressed");
}
struct protocol proto_radv = {
.name = "RAdv",
.template = "radv%d",
.init = radv_init,
.start = radv_start,
.shutdown = radv_shutdown,
.reconfigure = radv_reconfigure,
.copy_config = radv_copy_config,
.get_status = radv_get_status
};