From e2d2b3ef21f082a034e79d0880d4b36428029a59 Mon Sep 17 00:00:00 2001 From: Michal 'vorner' Vaner Date: Fri, 11 Aug 2017 12:25:36 +0200 Subject: [PATCH] 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. --- proto/radv/packets.c | 53 +++------------- proto/radv/radv.c | 146 ++++++++++++++++++++++++++++++++++++++++--- proto/radv/radv.h | 23 ++++++- 3 files changed, 170 insertions(+), 52 deletions(-) diff --git a/proto/radv/packets.c b/proto/radv/packets.c index bf051f62..088d177c 100644 --- a/proto/radv/packets.c +++ b/proto/radv/packets.c @@ -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; diff --git a/proto/radv/radv.c b/proto/radv/radv.c index 91f9853d..303cf251 100644 --- a/proto/radv/radv.c +++ b/proto/radv/radv.c @@ -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 diff --git a/proto/radv/radv.h b/proto/radv/radv.h index 559a3f3f..54d7c6f0 100644 --- a/proto/radv/radv.h +++ b/proto/radv/radv.h @@ -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