Internet on FIRE

/*

 *        BIRD -- OSPF

 *

 *        (c) 2000--2004 Ondrej Filip <feela@network.cz>

 *        (c) 2009--2014 Ondrej Zajicek <santiago@crfreenet.org>

 *        (c) 2009--2014 CZ.NIC z.s.p.o.

 *

 *        Can be freely distributed and used under the terms of the GNU GPL.

 */

#include "ospf.h"

/*

struct ospf_lsupd_packet

{

  struct ospf_packet hdr;

  // union ospf_auth auth;

  u32 lsa_count;

  void lsas[];

};

*/

void

ospf_dump_lsahdr(struct ospf_proto *p, struct ospf_lsa_header *lsa_n)

{

  struct ospf_lsa_header lsa;

  u32 lsa_etype;

  lsa_ntoh_hdr(lsa_n, &lsa);

  lsa_etype = lsa_get_etype(&lsa, p);

  log(L_TRACE "%s:     LSA      Type: %04x, Id: %R, Rt: %R, Age: %u, Seq: %08x, Sum: %04x",

      p->p.name, lsa_etype, lsa.id, lsa.rt, lsa.age, lsa.sn, lsa.checksum);

}

void

ospf_dump_common(struct ospf_proto *p, struct ospf_packet *pkt)

{

  log(L_TRACE "%s:     length   %d", p->p.name, ntohs(pkt->length));

  log(L_TRACE "%s:     router   %R", p->p.name, ntohl(pkt->routerid));

}

static inline uint

ospf_lsupd_hdrlen(struct ospf_proto *p)

{

  return ospf_pkt_hdrlen(p) + 4; /* + u32 lsa count field */

}

static inline u32

ospf_lsupd_get_lsa_count(struct ospf_packet *pkt, uint hdrlen)

{

  u32 *c = ((void *) pkt) + hdrlen - 4;

  return ntohl(*c);

}

static inline void

ospf_lsupd_set_lsa_count(struct ospf_packet *pkt, uint hdrlen, u32 val)

{

  u32 *c = ((void *) pkt) + hdrlen - 4;

  *c = htonl(val);

}

static inline void

ospf_lsupd_body(struct ospf_proto *p, struct ospf_packet *pkt,

                uint *offset, uint *bound, uint *lsa_count)

{

  uint hlen = ospf_lsupd_hdrlen(p);

  *offset = hlen;

  *bound = ntohs(pkt->length) - sizeof(struct ospf_lsa_header);

  *lsa_count = ospf_lsupd_get_lsa_count(pkt, hlen);

}

static void

ospf_dump_lsupd(struct ospf_proto *p, struct ospf_packet *pkt)

{

  uint offset, bound, i, lsa_count, lsalen;

  ASSERT(pkt->type == LSUPD_P);

  ospf_dump_common(p, pkt);

  ospf_lsupd_body(p, pkt, &offset, &bound, &lsa_count);

  for (i = 0; i < lsa_count; i++)

  {

    if (offset > bound)

    {

      log(L_TRACE "%s:     LSA      invalid", p->p.name);

      return;

    }

    struct ospf_lsa_header *lsa = ((void *) pkt) + offset;

    ospf_dump_lsahdr(p, lsa);

    lsalen = ntohs(lsa->length);

    offset += lsalen;

    if (((lsalen % 4) != 0) || (lsalen <= sizeof(struct ospf_lsa_header)))

    {

      log(L_TRACE "%s:     LSA      invalid", p->p.name);

      return;

    }

  }

}

static inline void

ospf_lsa_lsrt_up(struct top_hash_entry *en, struct ospf_neighbor *n)

{

  struct top_hash_entry *ret = ospf_hash_get_entry(n->lsrth, en);

  if (!SNODE_VALID(ret))

  {

    en->ret_count++;

    s_add_tail(&n->lsrtl, SNODE ret);

  }

  ret->lsa = en->lsa;

  ret->lsa_body = LSA_BODY_DUMMY;

}

static inline int

ospf_lsa_lsrt_down(struct top_hash_entry *en, struct ospf_neighbor *n)

{

  struct top_hash_entry *ret = ospf_hash_find_entry(n->lsrth, en);

  if (ret)

  {

    en->ret_count--;

    s_rem_node(SNODE ret);

    ospf_hash_delete(n->lsrth, ret);

    return 1;

  }

  return 0;

}

void

ospf_add_flushed_to_lsrt(struct ospf_proto *p, struct ospf_neighbor *n)

{

  struct top_hash_entry *en;

  WALK_SLIST(en, p->lsal)

    if ((en->lsa.age == LSA_MAXAGE) && (en->lsa_body != NULL) &&

        lsa_flooding_allowed(en->lsa_type, en->domain, n->ifa))

      ospf_lsa_lsrt_up(en, n);

}

static void ospf_send_lsupd_to_ifa(struct ospf_proto *p, struct top_hash_entry *en, struct ospf_iface *ifa);

/**

 * ospf_flood_lsa - send LSA to the neighbors

 * @p: OSPF protocol instance

 * @en: LSA entry

 * @from: neighbor than sent this LSA (or NULL if LSA is local)

 *

 * return value - was the LSA flooded back?

 */

int

ospf_flood_lsa(struct ospf_proto *p, struct top_hash_entry *en, struct ospf_neighbor *from)

{

  struct ospf_iface *ifa;

  struct ospf_neighbor *n;

  /* RFC 2328 13.3 */

  int back = 0;

  WALK_LIST(ifa, p->iface_list)

  {

    if (ifa->stub)

      continue;

    if (! lsa_flooding_allowed(en->lsa_type, en->domain, ifa))

      continue;

    DBG("Wanted to flood LSA: Type: %u, ID: %R, RT: %R, SN: 0x%x, Age %u\n",

        hh->type, hh->id, hh->rt, hh->sn, hh->age);

    int used = 0;

    WALK_LIST(n, ifa->neigh_list)

    {

      /* 13.3 (1a) */

      if (n->state < NEIGHBOR_EXCHANGE)

        continue;

      /* 13.3 (1b) */

      if (n->state < NEIGHBOR_FULL)

      {

        struct top_hash_entry *req = ospf_hash_find_entry(n->lsrqh, en);

        if (req != NULL)

        {

          int cmp = lsa_comp(&en->lsa, &req->lsa);

          /* If same or newer, remove LSA from the link state request list */

          if (cmp > CMP_OLDER)

          {

            s_rem_node(SNODE req);

            ospf_hash_delete(n->lsrqh, req);

            n->want_lsreq = 1;

            if ((EMPTY_SLIST(n->lsrql)) && (n->state == NEIGHBOR_LOADING))

              ospf_neigh_sm(n, INM_LOADDONE);

          }

          /* If older or same, skip processing of this neighbor */

          if (cmp < CMP_NEWER)

            continue;

        }

      }

      /* 13.3 (1c) */

      if (n == from)

        continue;

      /* In OSPFv3, there should be check whether receiving router understand

         that type of LSA (for LSA types with U-bit == 0). But as we do not support

         any optional LSA types, this is not needed yet */

      /* 13.3 (1d) - add LSA to the link state retransmission list */

      ospf_lsa_lsrt_up(en, n);

      used = 1;

    }

    /* 13.3 (2) */

    if (!used)

      continue;

    if (from && (from->ifa == ifa))

    {

      /* 13.3 (3) */

      if ((from->rid == ifa->drid) || (from->rid == ifa->bdrid))

        continue;

      /* 13.3 (4) */

      if (ifa->state == OSPF_IS_BACKUP)

        continue;

      back = 1;

    }

    /* 13.3 (5) - finally flood the packet */

    ospf_send_lsupd_to_ifa(p, en, ifa);

  }

  return back;

}

static uint

ospf_prepare_lsupd(struct ospf_proto *p, struct ospf_iface *ifa,

                   struct top_hash_entry **lsa_list, uint lsa_count)

{

  struct ospf_packet *pkt;

  uint hlen, pos, i, maxsize;

  pkt = ospf_tx_buffer(ifa);

  hlen = ospf_lsupd_hdrlen(p);

  maxsize = ospf_pkt_maxsize(ifa);

  ospf_pkt_fill_hdr(ifa, pkt, LSUPD_P);

  pos = hlen;

  for (i = 0; i < lsa_count; i++)

  {

    struct top_hash_entry *en = lsa_list[i];

    uint len = en->lsa.length;

    if ((pos + len) > maxsize)

    {

      /* The packet if full, stop adding LSAs and sent it */

      if (i > 0)

        break;

      /* LSA is larger than MTU, check buffer size */

      if (ospf_iface_assure_bufsize(ifa, pos + len) < 0)

      {

        /* Cannot fit in a tx buffer, skip that */

        log(L_ERR "%s: LSA too large to send on %s (Type: %04x, Id: %R, Rt: %R)", 

            p->p.name, ifa->ifname, en->lsa_type, en->lsa.id, en->lsa.rt);

        break;

      }

      /* TX buffer could be reallocated */

      pkt = ospf_tx_buffer(ifa);

    }

    struct ospf_lsa_header *buf = ((void *) pkt) + pos;

    lsa_hton_hdr(&en->lsa, buf);

    lsa_hton_body(en->lsa_body, ((void *) buf) + sizeof(struct ospf_lsa_header),

                  len - sizeof(struct ospf_lsa_header));

    buf->age = htons(MIN(en->lsa.age + ifa->inftransdelay, LSA_MAXAGE));

    pos += len;

  }

  ospf_lsupd_set_lsa_count(pkt, hlen, i);

  pkt->length = htons(pos);

  return i;

}

static void

ospf_send_lsupd_to_ifa(struct ospf_proto *p, struct top_hash_entry *en, struct ospf_iface *ifa)

{

  uint c = ospf_prepare_lsupd(p, ifa, &en, 1);

  if (!c)        /* Too large LSA */

    return;

  OSPF_PACKET(ospf_dump_lsupd, ospf_tx_buffer(ifa),

              "LSUPD packet flooded via %s", ifa->ifname);

  if (ifa->type == OSPF_IT_BCAST)

  {

    if ((ifa->state == OSPF_IS_DR) || (ifa->state == OSPF_IS_BACKUP))

      ospf_send_to_all(ifa);

    else

      ospf_send_to_des(ifa);

  }

  else

    ospf_send_to_agt(ifa, NEIGHBOR_EXCHANGE);

}

int

ospf_send_lsupd(struct ospf_proto *p, struct top_hash_entry **lsa_list, uint lsa_count, struct ospf_neighbor *n)

{

  struct ospf_iface *ifa = n->ifa;

  uint i, c;

  for (i = 0; i < lsa_count; i += c)

  {

    c = ospf_prepare_lsupd(p, ifa, lsa_list + i, lsa_count - i);

    if (!c)        /* Too large LSA */

      { i++; continue; }

    OSPF_PACKET(ospf_dump_lsupd, ospf_tx_buffer(ifa),

                "LSUPD packet sent to %I via %s", n->ip, ifa->ifname);

    ospf_send_to(ifa, n->ip);

  }

  return lsa_count;

}

void

ospf_rxmt_lsupd(struct ospf_proto *p, struct ospf_neighbor *n)

{

  const uint max = 128;

  struct top_hash_entry *entries[max];

  struct top_hash_entry *ret, *nxt, *en;

  uint i = 0;

  WALK_SLIST_DELSAFE(ret, nxt, n->lsrtl)

  {

    if (i == max)

      break;

    en = ospf_hash_find_entry(p->gr, ret);

    if (!en)

    {

      /* Probably flushed LSA, this should not happen */

      log(L_WARN "%s: LSA disappeared (Type: %04x, Id: %R, Rt: %R)",

          p->p.name, ret->lsa_type, ret->lsa.id, ret->lsa.rt);

      s_rem_node(SNODE ret);

      ospf_hash_delete(n->lsrth, ret);

      continue;

    }

    entries[i] = en;

    i++;

  }

  ospf_send_lsupd(p, entries, i, n);

}

static inline int

ospf_addr_is_local(struct ospf_proto *p, struct ospf_area *oa, ip_addr ip)

{

  struct ospf_iface *ifa;

  WALK_LIST(ifa, p->iface_list)

    if ((ifa->oa == oa) && ifa->addr && ipa_equal(ifa->addr->ip, ip))

      return 1;

  return 0;

}

void

ospf_receive_lsupd(struct ospf_packet *pkt, struct ospf_iface *ifa,

                   struct ospf_neighbor *n)

{

  struct ospf_proto *p = ifa->oa->po;

  /* RFC 2328 13. */

  int skip_lsreq = 0;

  n->want_lsreq = 0;

  uint plen = ntohs(pkt->length);

  if (plen < (ospf_lsupd_hdrlen(p) + sizeof(struct ospf_lsa_header)))

  {

    log(L_ERR "OSPF: Bad LSUPD packet from %I - too short (%u B)", n->ip, plen);

    return;

  }

  OSPF_PACKET(ospf_dump_lsupd, pkt, "LSUPD packet received from %I via %s", n->ip, ifa->ifname);

  if (n->state < NEIGHBOR_EXCHANGE)

  {

    OSPF_TRACE(D_PACKETS, "Received lsupd in lesser state than EXCHANGE from (%I)", n->ip);

    return;

  }

  ospf_neigh_sm(n, INM_HELLOREC);        /* Questionable */

  uint offset, bound, i, lsa_count;

  ospf_lsupd_body(p, pkt, &offset, &bound, &lsa_count);

  for (i = 0; i < lsa_count; i++)

  {

    struct ospf_lsa_header lsa, *lsa_n;

    struct top_hash_entry *en;

    u32 lsa_len, lsa_type, lsa_domain;

    if (offset > bound)

    {

      log(L_WARN "%s: Received LSUPD from %I is too short", p->p.name, n->ip);

      ospf_neigh_sm(n, INM_BADLSREQ);

      return;

    }

    /* LSA header in network order */

    lsa_n = ((void *) pkt) + offset;

    lsa_len = ntohs(lsa_n->length);

    offset += lsa_len;

    if ((offset > plen) || ((lsa_len % 4) != 0) ||

        (lsa_len <= sizeof(struct ospf_lsa_header)))

    {

      log(L_WARN "%s: Received LSA from %I with bad length", p->p.name, n->ip);

      ospf_neigh_sm(n, INM_BADLSREQ);

      return;

    }

    /* RFC 2328 13. (1) - validate LSA checksum */

    u16 chsum = lsa_n->checksum;

    if (chsum != lsasum_check(lsa_n, NULL))

    {

      log(L_WARN "%s: Received LSA from %I with bad checksum: %x %x",

          p->p.name, n->ip, chsum, lsa_n->checksum);

      continue;

    }

    /* LSA header in host order */

    lsa_ntoh_hdr(lsa_n, &lsa);

    lsa_get_type_domain(&lsa, ifa, &lsa_type, &lsa_domain);

    DBG("Update Type: %04x, Id: %R, Rt: %R, Sn: 0x%08x, Age: %u, Sum: %u\n",

        lsa_type, lsa.id, lsa.rt, lsa.sn, lsa.age, lsa.checksum);

    /* RFC 2328 13. (2) */

    if (!lsa_type)

    {

      log(L_WARN "%s: Received unknown LSA type from %I", p->p.name, n->ip);

      continue;

    }

    /* RFC 5340 4.5.1 (2) and RFC 2328 13. (3) */

    if (!oa_is_ext(ifa->oa) && (LSA_SCOPE(lsa_type) == LSA_SCOPE_AS))

    {

      log(L_WARN "%s: Received LSA with AS scope in stub area from %I", p->p.name, n->ip);

      continue;

    }

    /* Errata 3746 to RFC 2328 - rt-summary-LSAs forbidden in stub areas */

    if (!oa_is_ext(ifa->oa) && (lsa_type == LSA_T_SUM_RT))

    {

      log(L_WARN "%s: Received rt-summary-LSA in stub area from %I", p->p.name, n->ip);

      continue;

    }

    /* RFC 5340 4.5.1 (3) */

    if (LSA_SCOPE(lsa_type) == LSA_SCOPE_RES)

    {

      log(L_WARN "%s: Received LSA with invalid scope from %I", p->p.name, n->ip);

      continue;

    }

    /* Find local copy of LSA in link state database */

    en = ospf_hash_find(p->gr, lsa_domain, lsa.id, lsa.rt, lsa_type);

#ifdef LOCAL_DEBUG

    if (en)

      DBG("I have Type: %04x, Id: %R, Rt: %R, Sn: 0x%08x, Age: %u, Sum: %u\n",

          en->lsa_type, en->lsa.id, en->lsa.rt, en->lsa.sn, en->lsa.age, en->lsa.checksum);

#endif

    /* 13. (4) - ignore maxage LSA if i have no local copy */

    if ((lsa.age == LSA_MAXAGE) && !en && (p->padj == 0))

    {

      /* 13.5. - schedule ACKs (tbl 19, case 5) */ 

      ospf_enqueue_lsack(n, lsa_n, ACKL_DIRECT);

      continue;

    }

    /* 13. (5) - received LSA is newer (or no local copy) */

    if (!en || (lsa_comp(&lsa, &en->lsa) == CMP_NEWER))

    {

      /* 13. (5a) - enforce minimum time between updates for received LSAs */

      /* We also use this to ratelimit reactions to received self-originated LSAs */

      if (en && ((now - en->inst_time) < MINLSARRIVAL))

      {

        OSPF_TRACE(D_EVENTS, "Skipping LSA received in less that MinLSArrival");

        skip_lsreq = 1;

        continue;

      }

      /* Copy and validate LSA body */

      int blen = lsa.length - sizeof(struct ospf_lsa_header);

      void *body = mb_alloc(p->p.pool, blen);

      lsa_ntoh_body(lsa_n + 1, body, blen);

      if (lsa_validate(&lsa, lsa_type, ospf_is_v2(p), body) == 0)

      {

        log(L_WARN "%s: Received invalid LSA from %I", p->p.name, n->ip);

        mb_free(body);

        continue;

      }

      /* 13. (5f) - handle self-originated LSAs, see also 13.4. */

      if ((lsa.rt == p->router_id) ||

          (ospf_is_v2(p) && (lsa_type == LSA_T_NET) && ospf_addr_is_local(p, ifa->oa, ipa_from_u32(lsa.id))))

      {

        OSPF_TRACE(D_EVENTS, "Received unexpected self-originated LSA");

        ospf_advance_lsa(p, en, &lsa, lsa_type, lsa_domain, body);

        continue;

      }

      /* 13. (5c) - remove old LSA from all retransmission lists */

      /*

       * We only need to remove it from the retransmission list of the neighbor

       * that send us the new LSA. The old LSA is automatically replaced in

       * retransmission lists by the new LSA.

       */

      if (en)

        ospf_lsa_lsrt_down(en, n);

#if 0

      /*

       * Old code for removing LSA from all retransmission lists. Must be done

       * before (5b), otherwise it also removes the new entries from (5b).

       */

      struct ospf_iface *ifi;

      struct ospf_neighbor *ni;

      WALK_LIST(ifi, p->iface_list)

        WALK_LIST(ni, ifi->neigh_list)

        if (ni->state > NEIGHBOR_EXSTART)

          ospf_lsa_lsrt_down(en, ni);

#endif

      /* 13. (5d) - install new LSA into database */

      en = ospf_install_lsa(p, &lsa, lsa_type, lsa_domain, body);

      /* RFC 5340 4.4.3 Events 6+7 - new Link LSA received */

      if (lsa_type == LSA_T_LINK)

        ospf_notify_net_lsa(ifa);

      /* 13. (5b) - flood new LSA */

      int flood_back = ospf_flood_lsa(p, en, n);

      /* 13.5. - schedule ACKs (tbl 19, cases 1+2) */ 

      if (! flood_back)

        if ((ifa->state != OSPF_IS_BACKUP) || (n->rid == ifa->drid))

          ospf_enqueue_lsack(n, lsa_n, ACKL_DELAY);

      /* FIXME: remove LSA entry if it is LSA_MAXAGE and it is possible? */

      continue;

    }

    /* FIXME pg145 (6) */

    /* 13. (7) - received LSA is same */

    if (lsa_comp(&lsa, &en->lsa) == CMP_SAME)

    {

      /* Duplicate LSA, treat as implicit ACK */

      int implicit_ack = ospf_lsa_lsrt_down(en, n);

      /* 13.5. - schedule ACKs (tbl 19, cases 3+4) */ 

      if (implicit_ack)

      {

        if ((ifa->state == OSPF_IS_BACKUP) && (n->rid == ifa->drid))

          ospf_enqueue_lsack(n, lsa_n, ACKL_DELAY);

      }

      else

        ospf_enqueue_lsack(n, lsa_n, ACKL_DIRECT);

      skip_lsreq = 1;

      continue;

    }

    /* 13. (8) - received LSA is older */

    {

      /* Seqnum is wrapping, wait until it is flushed */

      if ((en->lsa.age == LSA_MAXAGE) && (en->lsa.sn == LSA_MAXSEQNO))

        continue;

      /* Send newer local copy back to neighbor */

      /* FIXME - check for MinLSArrival ? */

      ospf_send_lsupd(p, &en, 1, n);

    }

  }

  /* Send direct LSACKs */

  ospf_send_lsack(p, n, ACKL_DIRECT);

  /*

   * In loading state, we should ask for another batch of LSAs. This is only

   * vaguely mentioned in RFC 2328. We send a new LSREQ only if the current

   * LSUPD actually removed some entries from LSA request list (want_lsreq) and

   * did not contain duplicate or early LSAs (skip_lsreq). The first condition

   * prevents endless floods, the second condition helps with flow control.

   */

  if ((n->state == NEIGHBOR_LOADING) && n->want_lsreq && !skip_lsreq)

    ospf_send_lsreq(p, n);

}