proto/ospf/hello.c

   1 /*
   2  *      BIRD -- OSPF
   3  *
   4  *      (c) 1999--2004 Ondrej Filip <feela@network.cz>
   5  *      (c) 2009--2014 Ondrej Zajicek <santiago@crfreenet.org>
   6  *      (c) 2009--2014 CZ.NIC z.s.p.o.
   7  *
   8  *      Can be freely distributed and used under the terms of the GNU GPL.
   9  */
  10
  11 #include "ospf.h"
  12
  13
  14 struct ospf_hello2_packet
  15 {
  16   struct ospf_packet hdr;
  17   union ospf_auth2 auth;
  18
  19   u32 netmask;
  20   u16 helloint;
  21   u8 options;
  22   u8 priority;
  23   u32 deadint;
  24   u32 dr;
  25   u32 bdr;
  26
  27   u32 neighbors[];
  28 };
  29
  30 struct ospf_hello3_packet
  31 {
  32   struct ospf_packet hdr;
  33
  34   u32 iface_id;
  35   u32 options;
  36   u16 helloint;
  37   u16 deadint;
  38   u32 dr;
  39   u32 bdr;
  40
  41   u32 neighbors[];
  42 };
  43
  44
  45 uint
  46 ospf_hello3_options(struct ospf_packet *pkt)
  47 {
  48   struct ospf_hello3_packet *ps = (void *) pkt;
  49   return ntohl(ps->options) & 0x00FFFFFF;
  50 }
  51
  52 void
  53 ospf_send_hello(struct ospf_iface *ifa, int kind, struct ospf_neighbor *dirn)
  54 {
  55   struct ospf_proto *p = ifa->oa->po;
  56   struct ospf_packet *pkt;
  57   struct ospf_neighbor *neigh, *n1;
  58   struct nbma_node *nb;
  59   u32 *neighbors;
  60   uint length;
  61   int i, max;
  62
  63   if (ifa->state <= OSPF_IS_LOOP)
  64     return;
  65
  66   if (ifa->stub)
  67     return;
  68
  69
  70   pkt = ospf_tx_buffer(ifa);
  71   ospf_pkt_fill_hdr(ifa, pkt, HELLO_P);
  72
  73   if (ospf_is_v2(p))
  74   {
  75     struct ospf_hello2_packet *ps = (void *) pkt;
  76
  77     if ((ifa->type == OSPF_IT_VLINK) ||
  78         ((ifa->type == OSPF_IT_PTP) && !ifa->ptp_netmask))
  79       ps->netmask = 0;
  80     else
  81       ps->netmask = htonl(u32_mkmask(ifa->addr->prefix.pxlen));
  82
  83     ps->helloint = ntohs(ifa->helloint);
  84     ps->options = ifa->oa->options;
  85     ps->priority = ifa->priority;
  86     ps->deadint = htonl(ifa->deadint);
  87     ps->dr = htonl(ipa_to_u32(ifa->drip));
  88     ps->bdr = htonl(ipa_to_u32(ifa->bdrip));
  89
  90     length = sizeof(struct ospf_hello2_packet);
  91     neighbors = ps->neighbors;
  92   }
  93   else
  94   {
  95     struct ospf_hello3_packet *ps = (void *) pkt;
  96     u32 options = ifa->oa->options | (ifa->autype == OSPF_AUTH_CRYPT ? OPT_AT : 0);
  97
  98     ps->iface_id = htonl(ifa->iface_id);
  99     ps->options = ntohl(options | (ifa->priority << 24));
 100     ps->helloint = ntohs(ifa->helloint);
 101     ps->deadint = htons(ifa->deadint);
 102     ps->dr = htonl(ifa->drid);
 103     ps->bdr = htonl(ifa->bdrid);
 104
 105     length = sizeof(struct ospf_hello3_packet);
 106     neighbors = ps->neighbors;
 107   }
 108
 109   i = 0;
 110   max = (ospf_pkt_maxsize(ifa) - length) / sizeof(u32);
 111
 112   /* Fill all neighbors */
 113   if (kind != OHS_SHUTDOWN)
 114   {
 115     WALK_LIST(neigh, ifa->neigh_list)
 116     {
 117       if (i == max)
 118       {
 119         log(L_WARN "%s: Too many neighbors on %s", p->p.name, ifa->ifname);
 120         break;
 121       }
 122       neighbors[i] = htonl(neigh->rid);
 123       i++;
 124     }
 125   }
 126
 127   length += i * sizeof(u32);
 128   pkt->length = htons(length);
 129
 130   OSPF_TRACE(D_PACKETS, "HELLO packet sent via %s", ifa->ifname);
 131
 132   switch(ifa->type)
 133   {
 134   case OSPF_IT_BCAST:
 135   case OSPF_IT_PTP:
 136     ospf_send_to_all(ifa);
 137     break;
 138
 139   case OSPF_IT_NBMA:
 140     if (dirn)           /* Response to received hello */
 141     {
 142       ospf_send_to(ifa, dirn->ip);
 143       break;
 144     }
 145
 146     int to_all = ifa->state > OSPF_IS_DROTHER;
 147     int me_elig = ifa->priority > 0;
 148
 149     if (kind == OHS_POLL)       /* Poll timer */
 150     {
 151       WALK_LIST(nb, ifa->nbma_list)
 152         if (!nb->found && (to_all || (me_elig && nb->eligible)))
 153           ospf_send_to(ifa, nb->ip);
 154     }
 155     else                        /* Hello timer */
 156     {
 157       WALK_LIST(n1, ifa->neigh_list)
 158         if (to_all || (me_elig && (n1->priority > 0)) ||
 159             (n1->rid == ifa->drid) || (n1->rid == ifa->bdrid))
 160           ospf_send_to(ifa, n1->ip);
 161     }
 162     break;
 163
 164   case OSPF_IT_PTMP:
 165     WALK_LIST(n1, ifa->neigh_list)
 166       ospf_send_to(ifa, n1->ip);
 167
 168     WALK_LIST(nb, ifa->nbma_list)
 169       if (!nb->found)
 170         ospf_send_to(ifa, nb->ip);
 171
 172     /* If there is no other target, we also send HELLO packet to the other end */
 173     if (ipa_nonzero(ifa->addr->opposite) && !ifa->strictnbma &&
 174         EMPTY_LIST(ifa->neigh_list) && EMPTY_LIST(ifa->nbma_list))
 175       ospf_send_to(ifa, ifa->addr->opposite);
 176     break;
 177
 178   case OSPF_IT_VLINK:
 179     ospf_send_to(ifa, ifa->vip);
 180     break;
 181
 182   default:
 183     bug("Bug in ospf_send_hello()");
 184   }
 185 }
 186
 187
 188 void
 189 ospf_receive_hello(struct ospf_packet *pkt, struct ospf_iface *ifa,
 190                    struct ospf_neighbor *n, ip_addr faddr)
 191 {
 192   struct ospf_proto *p = ifa->oa->po;
 193   const char *err_dsc = NULL;
 194   u32 rcv_iface_id, rcv_helloint, rcv_deadint, rcv_dr, rcv_bdr;
 195   uint rcv_options, rcv_priority;
 196   uint loc_options = ifa->oa->options;
 197   u32 *neighbors;
 198   u32 neigh_count;
 199   uint plen, i, err_val = 0;
 200
 201   /* RFC 2328 10.5 */
 202
 203   /*
 204    * We may not yet have the associate neighbor, so we use Router ID from the
 205    * packet instead of one from the neighbor structure for log messages.
 206    */
 207   u32 rcv_rid = ntohl(pkt->routerid);
 208   OSPF_TRACE(D_PACKETS, "HELLO packet received from nbr %R on %s", rcv_rid, ifa->ifname);
 209
 210   plen = ntohs(pkt->length);
 211
 212   if (ospf_is_v2(p))
 213   {
 214     struct ospf_hello2_packet *ps = (void *) pkt;
 215
 216     if (plen < sizeof(struct ospf_hello2_packet))
 217       DROP("too short", plen);
 218
 219     rcv_iface_id = 0;
 220     rcv_helloint = ntohs(ps->helloint);
 221     rcv_deadint = ntohl(ps->deadint);
 222     rcv_dr = ntohl(ps->dr);
 223     rcv_bdr = ntohl(ps->bdr);
 224     rcv_options = ps->options;
 225     rcv_priority = ps->priority;
 226
 227     int pxlen = u32_masklen(ntohl(ps->netmask));
 228     if (pxlen < 0)
 229       DROP("prefix garbled", ntohl(ps->netmask));
 230
 231     if ((ifa->type != OSPF_IT_VLINK) &&
 232         (ifa->type != OSPF_IT_PTP) &&
 233         ((uint) pxlen != ifa->addr->prefix.pxlen))
 234       DROP("prefix length mismatch", pxlen);
 235
 236     neighbors = ps->neighbors;
 237     neigh_count = (plen - sizeof(struct ospf_hello2_packet)) / sizeof(u32);
 238   }
 239   else /* OSPFv3 */
 240   {
 241     struct ospf_hello3_packet *ps = (void *) pkt;
 242
 243     if (plen < sizeof(struct ospf_hello3_packet))
 244       DROP("too short", plen);
 245
 246     rcv_iface_id = ntohl(ps->iface_id);
 247     rcv_helloint = ntohs(ps->helloint);
 248     rcv_deadint = ntohs(ps->deadint);
 249     rcv_dr = ntohl(ps->dr);
 250     rcv_bdr = ntohl(ps->bdr);
 251     rcv_options = ntohl(ps->options) & 0x00FFFFFF;
 252     rcv_priority = ntohl(ps->options) >> 24;
 253
 254     neighbors = ps->neighbors;
 255     neigh_count = (plen - sizeof(struct ospf_hello3_packet)) / sizeof(u32);
 256   }
 257
 258   if (rcv_helloint != ifa->helloint)
 259     DROP("hello interval mismatch", rcv_helloint);
 260
 261   if (rcv_deadint != ifa->deadint)
 262     DROP("dead interval mismatch", rcv_deadint);
 263
 264   /* Check whether bits E, N match */
 265   if ((rcv_options ^ loc_options) & (OPT_E | OPT_N))
 266     DROP("area type mismatch", rcv_options);
 267
 268   /* RFC 5838 2.4 - AF-bit check unless on IPv6 unicast */
 269   if ((loc_options & OPT_AF) && !(loc_options & OPT_V6) && !(rcv_options & OPT_AF))
 270     DROP("AF-bit mismatch", rcv_options);
 271
 272   /* Check consistency of existing neighbor entry */
 273   if (n)
 274   {
 275     uint t = ifa->type;
 276     if (ospf_is_v2(p) && ((t == OSPF_IT_BCAST) || (t == OSPF_IT_NBMA) || (t == OSPF_IT_PTMP)))
 277     {
 278       /* Neighbor identified by IP address; Router ID may change */
 279       if (n->rid != rcv_rid)
 280       {
 281         OSPF_TRACE(D_EVENTS, "Neighbor %R on %s changed Router ID to %R",
 282                    n->rid, ifa->ifname, rcv_rid);
 283         ospf_neigh_sm(n, INM_KILLNBR);
 284         n = NULL;
 285       }
 286     }
 287     else /* OSPFv3 or OSPFv2/PtP */
 288     {
 289       /* Neighbor identified by Router ID; IP address may change */
 290       if (!ipa_equal(faddr, n->ip))
 291       {
 292         OSPF_TRACE(D_EVENTS, "Neighbor %R on %s changed IP address to %I",
 293                    n->rid, ifa->ifname, faddr);
 294         n->ip = faddr;
 295       }
 296     }
 297   }
 298
 299   if (!n)
 300   {
 301     if ((ifa->type == OSPF_IT_NBMA) || (ifa->type == OSPF_IT_PTMP))
 302     {
 303       struct nbma_node *nn = find_nbma_node(ifa, faddr);
 304
 305       if (!nn && ifa->strictnbma)
 306         DROP1("new neighbor denied");
 307
 308       if (nn && (ifa->type == OSPF_IT_NBMA) &&
 309           (((rcv_priority == 0) && nn->eligible) ||
 310            ((rcv_priority > 0) && !nn->eligible)))
 311         DROP("eligibility mismatch", rcv_priority);
 312
 313       if (nn)
 314         nn->found = 1;
 315     }
 316
 317     OSPF_TRACE(D_EVENTS, "New neighbor %R on %s, IP address %I",
 318                rcv_rid, ifa->ifname, faddr);
 319
 320     n = ospf_neighbor_new(ifa);
 321
 322     n->rid = rcv_rid;
 323     n->ip = faddr;
 324     n->dr = rcv_dr;
 325     n->bdr = rcv_bdr;
 326     n->priority = rcv_priority;
 327     n->iface_id = rcv_iface_id;
 328
 329     if (n->ifa->cf->bfd)
 330       ospf_neigh_update_bfd(n, n->ifa->bfd);
 331   }
 332
 333   u32 n_id = ospf_is_v2(p) ? ipa_to_u32(n->ip) : n->rid;
 334
 335   u32 old_dr = n->dr;
 336   u32 old_bdr = n->bdr;
 337   u32 old_priority = n->priority;
 338   u32 old_iface_id = n->iface_id;
 339
 340   n->dr = rcv_dr;
 341   n->bdr = rcv_bdr;
 342   n->priority = rcv_priority;
 343   n->iface_id = rcv_iface_id;
 344
 345   /* Update inactivity timer */
 346   ospf_neigh_sm(n, INM_HELLOREC);
 347
 348   /* RFC 2328 9.5.1 - non-eligible routers reply to hello on NBMA nets */
 349   if (ifa->type == OSPF_IT_NBMA)
 350     if ((ifa->priority == 0) && (n->priority > 0))
 351       ospf_send_hello(n->ifa, OHS_HELLO, n);
 352
 353
 354   /* Examine list of neighbors */
 355   for (i = 0; i < neigh_count; i++)
 356     if (neighbors[i] == htonl(p->router_id))
 357       goto found_self;
 358
 359   ospf_neigh_sm(n, INM_1WAYREC);
 360   return;
 361
 362 found_self:
 363   ospf_neigh_sm(n, INM_2WAYREC);
 364
 365
 366   if (n->iface_id != old_iface_id)
 367   {
 368     /* If neighbor is DR, also update cached DR interface ID */
 369     if (ifa->drid == n->rid)
 370       ifa->dr_iface_id = n->iface_id;
 371
 372     /* RFC 5340 4.4.3 Event 4 - change of neighbor's interface ID */
 373     ospf_notify_rt_lsa(ifa->oa);
 374
 375     /* Missed in RFC 5340 4.4.3 Event 4 - (Px-)Net-LSA uses iface_id to ref Link-LSAs */
 376     ospf_notify_net_lsa(ifa);
 377   }
 378
 379   if (ifa->state == OSPF_IS_WAITING)
 380   {
 381     /* Neighbor is declaring itself DR (and there is no BDR) or as BDR */
 382     if (((n->dr == n_id) && (n->bdr == 0)) || (n->bdr == n_id))
 383       ospf_iface_sm(ifa, ISM_BACKS);
 384   }
 385   else if (ifa->state >= OSPF_IS_DROTHER)
 386   {
 387     /* Neighbor changed priority or started/stopped declaring itself as DR/BDR */
 388     if ((n->priority != old_priority) ||
 389         ((n->dr == n_id) && (old_dr != n_id)) ||
 390         ((n->dr != n_id) && (old_dr == n_id)) ||
 391         ((n->bdr == n_id) && (old_bdr != n_id)) ||
 392         ((n->bdr != n_id) && (old_bdr == n_id)))
 393       ospf_iface_sm(ifa, ISM_NEICH);
 394   }
 395
 396   return;
 397
 398 drop:
 399   LOG_PKT("Bad HELLO packet from nbr %R on %s - %s (%u)",
 400           rcv_rid, ifa->ifname, err_dsc, err_val);
 401 }