Commit e2d2b3ef authored by Michal 'vorner' Vaner's avatar Michal 'vorner' Vaner Committed by Ondrej Zajicek (work)
Browse files

RAdv: Buffer prefixes awhile after they disappear 

Keep a cache of all the relevant prefixes we send out. When a prefix
appears, insert it into the cache. If it dies, keep it there for a
while, marked as dead.

Send out the dead prefixes with zero lifetime.
parent 3ac5d1ce

proto/radv/packets.c

+9 −44
Original line number Diff line number Diff line
@@ -70,36 +70,6 @@ struct radv_opt_dnssl 
  char domain[];

};





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 *

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;

}



static int

radv_prepare_rdnss(struct radv_iface *ifa, list *rdnss_list, char **buf, char *bufend)

{
@@ -236,9 +206,10 @@ radv_prepare_dnssl(struct radv_iface *ifa, list *dnssl_list, char **buf, char *b 
}



static int

radv_prepare_prefix(struct radv_iface *ifa, struct radv_prefix_config *pc,

  struct ifa *addr, char **buf, char *bufend)

radv_prepare_prefix(struct radv_iface *ifa, struct radv_prefix *prefix,

		    char **buf, char *bufend)

{

  struct radv_prefix_config *pc = prefix->config;

  struct radv_opt_prefix *op = (void *) *buf;



  if (*buf + sizeof(*op) > bufend)
@@ -250,7 +221,7 @@ radv_prepare_prefix(struct radv_iface *ifa, struct radv_prefix_config *pc, 


  op->type = OPT_PREFIX;

  op->length = 4;

  op->pxlen = addr->pxlen;

  op->pxlen = prefix->len;

  op->flags = (pc->onlink ? OPT_PX_ONLINK : 0) |

    (pc->autonomous ? OPT_PX_AUTONOMOUS : 0);

  op->valid_lifetime = (ifa->ra->active || !pc->valid_lifetime_sensitive) ?
@@ -258,7 +229,7 @@ radv_prepare_prefix(struct radv_iface *ifa, struct radv_prefix_config *pc, 
  op->preferred_lifetime = (ifa->ra->active || !pc->preferred_lifetime_sensitive) ?

    htonl(pc->preferred_lifetime) : 0;

  op->reserved = 0;

  op->prefix = addr->prefix;

  op->prefix = prefix->prefix;

  ipa_hton(op->prefix);

  *buf += sizeof(*op);
@@ -300,16 +271,10 @@ radv_prepare_ra(struct radv_iface *ifa) 
    buf += sizeof (*om);

  }



  struct ifa *addr;

  WALK_LIST(addr, ifa->iface->addrs)

  struct radv_prefix *prefix;

  WALK_LIST(prefix, ifa->prefixes)

  {

    struct radv_prefix_config *pc;

    pc = radv_prefix_match(ifa, addr);



    if (!pc || pc->skip)

      continue;



    if (radv_prepare_prefix(ifa, pc, addr, &buf, bufend) < 0)

    if (radv_prepare_prefix(ifa, prefix, &buf, bufend) < 0)

      goto done;

  }
@@ -419,7 +384,7 @@ radv_err_hook(sock *sk, int err) 
int

radv_sk_open(struct radv_iface *ifa)

{

  sock *sk = sk_new(ifa->ra->p.pool);

  sock *sk = sk_new(ifa->pool);

  sk->type = SK_IP;

  sk->dport = ICMPV6_PROTO;

  sk->saddr = ifa->addr->ip;

proto/radv/radv.c

+139 −7
Original line number Diff line number Diff line
@@ -51,6 +51,15 @@ radv_timer(timer *tm) 


  RADV_TRACE(D_EVENTS, "Timer fired on %s", ifa->iface->name);



  /* If some dead prefixes expired, regenerate the prefix list and the packet.

   * We do so by pretending there was a change on the interface.

   *

   * This sets the timer, but we replace it just at the end of this function

   * (replacing a timer is fine).

   */

  if (ifa->prefix_expires != 0 && ifa->prefix_expires <= now)

    radv_iface_notify(ifa, RA_EV_GC);



  radv_send_ra(ifa, 0);



  /* Update timer */
@@ -67,7 +76,129 @@ radv_timer(timer *tm) 
  tm_start(ifa->timer, after);

}



static char* ev_name[] = { NULL, "Init", "Change", "RS" };

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

prefixes_prepare(struct radv_iface *ifa)

{

  struct radv_proto *p = ifa->ra;

  /* First mark all the prefixes as unused */

  struct radv_prefix *pfx;



  WALK_LIST(pfx, ifa->prefixes)

    pfx->mark = 0;



  /* Now 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 &&

	  memcmp(&pfx->prefix, &addr->prefix, sizeof pfx->prefix) == 0)

      {

	existing = pfx;

	break;

      }



    if (!existing)

    {

      RADV_TRACE(D_EVENTS, "Allocating new prefix %I on %s", addr->prefix,

		 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->config = pc;

  }



  /*

   * Garbage-collect the prefixes. If something isn't used, it dies (but isn't

   * dropped just yet). If something is dead and rots there for long enough,

   * clean it up.

   */

  // XXX: Make these 5 minutes it configurable

  bird_clock_t rotten = now + 300;

  struct radv_prefix *next;

  bird_clock_t expires_soonest = 0;

  WALK_LIST_DELSAFE(pfx, next, ifa->prefixes) {

    if (pfx->alive && !pfx->mark)

    {

      RADV_TRACE(D_EVENTS, "Marking prefix %I on %s as dead", pfx->prefix,

		 ifa->iface->name);

      // It just died

      pfx->alive = 0;

      pfx->expires = rotten;

      pfx->config = &dead_prefix;

    }

    if (!pfx->alive)

      if (pfx->expires <= now)

      {

	RADV_TRACE(D_EVENTS, "Dropping long dead prefix %I on %s", pfx->prefix,

		   ifa->iface->name);

	// It's dead and rotten, clean it up

	rem_node(NODE pfx);

	mb_free(pfx);

      }

      else

      {

	ASSERT(pfx->expires != 0);

	// Let it rot for a while more, but look when it's ripe.

	if (expires_soonest == 0 || pfx->expires < expires_soonest)

	  expires_soonest = pfx->expires;

      }

  }

  ifa->prefix_expires = expires_soonest;

}



static char* ev_name[] = { NULL, "Init", "Change", "RS", "Garbage collect" };



void

radv_iface_notify(struct radv_iface *ifa, int event)
@@ -82,6 +213,7 @@ radv_iface_notify(struct radv_iface *ifa, int event) 
  switch (event)

  {

  case RA_EV_CHANGE:

  case RA_EV_GC:

    ifa->plen = 0;

  case RA_EV_INIT:

    ifa->initial = MAX_INITIAL_RTR_ADVERTISEMENTS;
@@ -91,6 +223,8 @@ radv_iface_notify(struct radv_iface *ifa, int event) 
    break;

  }



  prefixes_prepare(ifa);



  /* Update timer */

  unsigned delta = now - ifa->last;

  unsigned after = 0;
@@ -152,15 +286,17 @@ find_lladdr(struct iface *iface) 
static void

radv_iface_new(struct radv_proto *p, struct iface *iface, struct radv_iface_config *cf)

{

  pool *pool = p->p.pool;

  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);



  add_tail(&p->iface_list, NODE ifa);
@@ -198,11 +334,7 @@ radv_iface_remove(struct radv_iface *ifa) 


  rem_node(NODE ifa);



  rfree(ifa->sk);

  rfree(ifa->timer);

  rfree(ifa->lock);



  mb_free(ifa);

  rfree(ifa->pool);

}



static void

proto/radv/radv.h

+22 −1
Original line number Diff line number Diff line
@@ -121,6 +121,23 @@ struct radv_proto 
  u8 active;			/* Whether radv is active w.r.t. triggers */

};



struct radv_prefix		/* One prefix we advertise */

{

  node n;

  ip_addr prefix;

  u8 len;

  /* Is the prefix alive? If not, we advertise it with 0 lifetime, so clients

   * stop using it. */

  u8 alive;

  u8 mark;			/* A temporary mark for processing */

  /* The (absolute) time when we drop this prefix from advertising. It is valid

   * only if !alive. */

  bird_clock_t expires;

  /* The config tied to this prefix. Always valid (we place a dummy config here

   * when !alive). */

  struct radv_prefix_config *config;

};



struct radv_iface

{

  node n;
@@ -128,6 +145,9 @@ struct radv_iface 
  struct radv_iface_config *cf;	/* Related config, must be updated in reconfigure */

  struct iface *iface;

  struct ifa *addr;		/* Link-local address of iface */

  struct pool *pool;		/* A pool for interface-specific things */

  list prefixes;		/* The prefixes we advertise */

  bird_clock_t prefix_expires;	/* When the soonest prefix expires (0 = none dead) */



  timer *timer;

  struct object_lock *lock;
@@ -135,12 +155,13 @@ struct radv_iface 


  bird_clock_t last;		/* Time of last sending of RA */

  u16 plen;			/* Length of prepared RA in tbuf, or 0 if not valid */

  byte initial;			/* List of active ifaces */

  byte initial;			/* How many RAs are still to be sent as initial */

};



#define RA_EV_INIT 1		/* Switch to initial mode */

#define RA_EV_CHANGE 2		/* Change of options or prefixes */

#define RA_EV_RS 3		/* Received RS */

#define RA_EV_GC 4		/* Internal garbage collection of prefixes */



/* Default Router Preferences (RFC 4191) */

#define RA_PREF_LOW	0x18

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