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.
This commit is contained in:
Michal 'vorner' Vaner
Ondrej Zajicek (work)
parent
3ac5d1ce4c
commit
e2d2b3ef21
3 changed files with 170 additions and 52 deletions
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@ -70,36 +70,6 @@ struct radv_opt_dnssl
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char domain[];
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};
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static struct radv_prefix_config default_prefix = {
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.onlink = 1,
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.autonomous = 1,
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.valid_lifetime = DEFAULT_VALID_LIFETIME,
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.preferred_lifetime = DEFAULT_PREFERRED_LIFETIME
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};
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static struct radv_prefix_config *
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radv_prefix_match(struct radv_iface *ifa, struct ifa *a)
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{
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struct radv_proto *p = ifa->ra;
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struct radv_config *cf = (struct radv_config *) (p->p.cf);
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struct radv_prefix_config *pc;
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if (a->scope <= SCOPE_LINK)
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return NULL;
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WALK_LIST(pc, ifa->cf->pref_list)
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if ((a->pxlen >= pc->pxlen) && ipa_in_net(a->prefix, pc->prefix, pc->pxlen))
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return pc;
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WALK_LIST(pc, cf->pref_list)
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if ((a->pxlen >= pc->pxlen) && ipa_in_net(a->prefix, pc->prefix, pc->pxlen))
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return pc;
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return &default_prefix;
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}
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static int
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radv_prepare_rdnss(struct radv_iface *ifa, list *rdnss_list, char **buf, char *bufend)
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{
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@ -236,9 +206,10 @@ radv_prepare_dnssl(struct radv_iface *ifa, list *dnssl_list, char **buf, char *b
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}
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static int
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radv_prepare_prefix(struct radv_iface *ifa, struct radv_prefix_config *pc,
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struct ifa *addr, char **buf, char *bufend)
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radv_prepare_prefix(struct radv_iface *ifa, struct radv_prefix *prefix,
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char **buf, char *bufend)
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{
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struct radv_prefix_config *pc = prefix->config;
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struct radv_opt_prefix *op = (void *) *buf;
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if (*buf + sizeof(*op) > bufend)
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@ -250,7 +221,7 @@ radv_prepare_prefix(struct radv_iface *ifa, struct radv_prefix_config *pc,
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op->type = OPT_PREFIX;
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op->length = 4;
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op->pxlen = addr->pxlen;
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op->pxlen = prefix->len;
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op->flags = (pc->onlink ? OPT_PX_ONLINK : 0) |
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(pc->autonomous ? OPT_PX_AUTONOMOUS : 0);
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op->valid_lifetime = (ifa->ra->active || !pc->valid_lifetime_sensitive) ?
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@ -258,7 +229,7 @@ radv_prepare_prefix(struct radv_iface *ifa, struct radv_prefix_config *pc,
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op->preferred_lifetime = (ifa->ra->active || !pc->preferred_lifetime_sensitive) ?
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htonl(pc->preferred_lifetime) : 0;
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op->reserved = 0;
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op->prefix = addr->prefix;
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op->prefix = prefix->prefix;
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ipa_hton(op->prefix);
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*buf += sizeof(*op);
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@ -300,16 +271,10 @@ radv_prepare_ra(struct radv_iface *ifa)
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buf += sizeof (*om);
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}
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struct ifa *addr;
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WALK_LIST(addr, ifa->iface->addrs)
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struct radv_prefix *prefix;
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WALK_LIST(prefix, ifa->prefixes)
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{
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struct radv_prefix_config *pc;
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pc = radv_prefix_match(ifa, addr);
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if (!pc || pc->skip)
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continue;
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if (radv_prepare_prefix(ifa, pc, addr, &buf, bufend) < 0)
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if (radv_prepare_prefix(ifa, prefix, &buf, bufend) < 0)
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goto done;
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}
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@ -419,7 +384,7 @@ radv_err_hook(sock *sk, int err)
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int
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radv_sk_open(struct radv_iface *ifa)
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{
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sock *sk = sk_new(ifa->ra->p.pool);
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sock *sk = sk_new(ifa->pool);
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sk->type = SK_IP;
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sk->dport = ICMPV6_PROTO;
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sk->saddr = ifa->addr->ip;
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@ -51,6 +51,15 @@ radv_timer(timer *tm)
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RADV_TRACE(D_EVENTS, "Timer fired on %s", ifa->iface->name);
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/* If some dead prefixes expired, regenerate the prefix list and the packet.
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* We do so by pretending there was a change on the interface.
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*
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* This sets the timer, but we replace it just at the end of this function
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* (replacing a timer is fine).
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*/
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if (ifa->prefix_expires != 0 && ifa->prefix_expires <= now)
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radv_iface_notify(ifa, RA_EV_GC);
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radv_send_ra(ifa, 0);
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/* Update timer */
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@ -67,7 +76,129 @@ radv_timer(timer *tm)
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tm_start(ifa->timer, after);
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}
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static char* ev_name[] = { NULL, "Init", "Change", "RS" };
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static struct radv_prefix_config default_prefix = {
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.onlink = 1,
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.autonomous = 1,
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.valid_lifetime = DEFAULT_VALID_LIFETIME,
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.preferred_lifetime = DEFAULT_PREFERRED_LIFETIME
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};
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static struct radv_prefix_config dead_prefix = {
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};
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/* Find a corresponding config for the given prefix */
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static struct radv_prefix_config *
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radv_prefix_match(struct radv_iface *ifa, struct ifa *a)
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{
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struct radv_proto *p = ifa->ra;
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struct radv_config *cf = (struct radv_config *) (p->p.cf);
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struct radv_prefix_config *pc;
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if (a->scope <= SCOPE_LINK)
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return NULL;
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WALK_LIST(pc, ifa->cf->pref_list)
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if ((a->pxlen >= pc->pxlen) && ipa_in_net(a->prefix, pc->prefix, pc->pxlen))
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return pc;
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WALK_LIST(pc, cf->pref_list)
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if ((a->pxlen >= pc->pxlen) && ipa_in_net(a->prefix, pc->prefix, pc->pxlen))
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return pc;
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return &default_prefix;
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}
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/*
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* Go through the list of prefixes, compare them with configs and decide if we
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* want them or not. */
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static void
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prefixes_prepare(struct radv_iface *ifa)
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{
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struct radv_proto *p = ifa->ra;
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/* First mark all the prefixes as unused */
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struct radv_prefix *pfx;
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WALK_LIST(pfx, ifa->prefixes)
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pfx->mark = 0;
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/* Now find all the prefixes we want to use and make sure they are in the
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* list. */
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struct ifa *addr;
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WALK_LIST(addr, ifa->iface->addrs)
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{
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struct radv_prefix_config *pc = radv_prefix_match(ifa, addr);
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if (!pc || pc->skip)
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continue;
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/* Do we have it already? */
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struct radv_prefix *existing = NULL;
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WALK_LIST(pfx, ifa->prefixes)
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if (pfx->len == addr->pxlen &&
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memcmp(&pfx->prefix, &addr->prefix, sizeof pfx->prefix) == 0)
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{
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existing = pfx;
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break;
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}
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if (!existing)
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{
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RADV_TRACE(D_EVENTS, "Allocating new prefix %I on %s", addr->prefix,
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ifa->iface->name);
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existing = mb_allocz(ifa->pool, sizeof *existing);
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existing->prefix = addr->prefix;
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existing->len = addr->pxlen;
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add_tail(&ifa->prefixes, NODE existing);
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}
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/*
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* Update the information (it may have changed, or even bring a prefix back
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* to life).
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*/
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existing->alive = 1;
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existing->mark = 1;
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existing->config = pc;
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}
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/*
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* Garbage-collect the prefixes. If something isn't used, it dies (but isn't
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* dropped just yet). If something is dead and rots there for long enough,
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* clean it up.
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*/
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// XXX: Make these 5 minutes it configurable
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bird_clock_t rotten = now + 300;
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struct radv_prefix *next;
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bird_clock_t expires_soonest = 0;
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WALK_LIST_DELSAFE(pfx, next, ifa->prefixes) {
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if (pfx->alive && !pfx->mark)
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{
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RADV_TRACE(D_EVENTS, "Marking prefix %I on %s as dead", pfx->prefix,
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ifa->iface->name);
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// It just died
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pfx->alive = 0;
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pfx->expires = rotten;
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pfx->config = &dead_prefix;
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}
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if (!pfx->alive)
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if (pfx->expires <= now)
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{
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RADV_TRACE(D_EVENTS, "Dropping long dead prefix %I on %s", pfx->prefix,
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ifa->iface->name);
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// It's dead and rotten, clean it up
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rem_node(NODE pfx);
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mb_free(pfx);
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}
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else
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{
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ASSERT(pfx->expires != 0);
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// Let it rot for a while more, but look when it's ripe.
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if (expires_soonest == 0 || pfx->expires < expires_soonest)
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expires_soonest = pfx->expires;
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}
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}
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ifa->prefix_expires = expires_soonest;
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}
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static char* ev_name[] = { NULL, "Init", "Change", "RS", "Garbage collect" };
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void
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radv_iface_notify(struct radv_iface *ifa, int event)
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@ -82,6 +213,7 @@ radv_iface_notify(struct radv_iface *ifa, int event)
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switch (event)
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{
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case RA_EV_CHANGE:
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case RA_EV_GC:
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ifa->plen = 0;
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case RA_EV_INIT:
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ifa->initial = MAX_INITIAL_RTR_ADVERTISEMENTS;
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@ -91,6 +223,8 @@ radv_iface_notify(struct radv_iface *ifa, int event)
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break;
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}
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prefixes_prepare(ifa);
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/* Update timer */
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unsigned delta = now - ifa->last;
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unsigned after = 0;
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@ -152,15 +286,17 @@ find_lladdr(struct iface *iface)
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static void
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radv_iface_new(struct radv_proto *p, struct iface *iface, struct radv_iface_config *cf)
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{
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pool *pool = p->p.pool;
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struct radv_iface *ifa;
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RADV_TRACE(D_EVENTS, "Adding interface %s", iface->name);
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pool *pool = rp_new(p->p.pool, iface->name);
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ifa = mb_allocz(pool, sizeof(struct radv_iface));
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ifa->pool = pool;
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ifa->ra = p;
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ifa->cf = cf;
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ifa->iface = iface;
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init_list(&ifa->prefixes);
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add_tail(&p->iface_list, NODE ifa);
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@ -198,11 +334,7 @@ radv_iface_remove(struct radv_iface *ifa)
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rem_node(NODE ifa);
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rfree(ifa->sk);
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rfree(ifa->timer);
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rfree(ifa->lock);
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mb_free(ifa);
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rfree(ifa->pool);
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}
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static void
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@ -121,6 +121,23 @@ struct radv_proto
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u8 active; /* Whether radv is active w.r.t. triggers */
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};
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struct radv_prefix /* One prefix we advertise */
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{
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node n;
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ip_addr prefix;
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u8 len;
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/* Is the prefix alive? If not, we advertise it with 0 lifetime, so clients
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* stop using it. */
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u8 alive;
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u8 mark; /* A temporary mark for processing */
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/* The (absolute) time when we drop this prefix from advertising. It is valid
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* only if !alive. */
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bird_clock_t expires;
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/* The config tied to this prefix. Always valid (we place a dummy config here
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* when !alive). */
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struct radv_prefix_config *config;
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};
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struct radv_iface
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{
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node n;
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@ -128,6 +145,9 @@ struct radv_iface
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struct radv_iface_config *cf; /* Related config, must be updated in reconfigure */
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struct iface *iface;
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struct ifa *addr; /* Link-local address of iface */
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struct pool *pool; /* A pool for interface-specific things */
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list prefixes; /* The prefixes we advertise */
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bird_clock_t prefix_expires; /* When the soonest prefix expires (0 = none dead) */
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timer *timer;
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struct object_lock *lock;
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@ -135,12 +155,13 @@ struct radv_iface
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bird_clock_t last; /* Time of last sending of RA */
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u16 plen; /* Length of prepared RA in tbuf, or 0 if not valid */
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byte initial; /* List of active ifaces */
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byte initial; /* How many RAs are still to be sent as initial */
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};
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#define RA_EV_INIT 1 /* Switch to initial mode */
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#define RA_EV_CHANGE 2 /* Change of options or prefixes */
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#define RA_EV_RS 3 /* Received RS */
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#define RA_EV_GC 4 /* Internal garbage collection of prefixes */
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/* Default Router Preferences (RFC 4191) */
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#define RA_PREF_LOW 0x18
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