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_auth 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   u8 priority;
  36   u8 options3;
  37   u8 options2;
  38   u8 options;
  39   u16 helloint;
  40   u16 deadint;
  41   u32 dr;
  42   u32 bdr;
  43
  44   u32 neighbors[];
  45 };
  46
  47
  48 void
  49 ospf_send_hello(struct ospf_iface *ifa, int kind, struct ospf_neighbor *dirn)
  50 {
  51   struct ospf_proto *p = ifa->oa->po;
  52   struct ospf_packet *pkt;
  53   struct ospf_neighbor *neigh, *n1;
  54   struct nbma_node *nb;
  55   u32 *neighbors;
  56   uint length;
  57   int i, max;
  58
  59   if (ifa->state <= OSPF_IS_LOOP)
  60     return;
  61
  62   if (ifa->stub)
  63     return;
  64
  65
  66   pkt = ospf_tx_buffer(ifa);
  67   ospf_pkt_fill_hdr(ifa, pkt, HELLO_P);
  68
  69   if (ospf_is_v2(p))
  70   {
  71     struct ospf_hello2_packet *ps = (void *) pkt;
  72
  73     if ((ifa->type == OSPF_IT_VLINK) ||
  74         ((ifa->type == OSPF_IT_PTP) && !ifa->ptp_netmask))
  75       ps->netmask = 0;
  76     else
  77       ps->netmask = htonl(u32_mkmask(ifa->addr->pxlen));
  78
  79     ps->helloint = ntohs(ifa->helloint);
  80     ps->options = ifa->oa->options;
  81     ps->priority = ifa->priority;
  82     ps->deadint = htonl(ifa->deadint);
  83     ps->dr = htonl(ipa_to_u32(ifa->drip));
  84     ps->bdr = htonl(ipa_to_u32(ifa->bdrip));
  85
  86     length = sizeof(struct ospf_hello2_packet);
  87     neighbors = ps->neighbors;
  88   }
  89   else
  90   {
  91     struct ospf_hello3_packet *ps = (void *) pkt;
  92
  93     ps->iface_id = htonl(ifa->iface_id);
  94     ps->priority = ifa->priority;
  95     ps->options3 = ifa->oa->options >> 16;
  96     ps->options2 = ifa->oa->options >> 8;
  97     ps->options = ifa->oa->options;
  98     ps->helloint = ntohs(ifa->helloint);
  99     ps->deadint = htons(ifa->deadint);
 100     ps->dr = htonl(ifa->drid);
 101     ps->bdr = htonl(ifa->bdrid);
 102
 103     length = sizeof(struct ospf_hello3_packet);
 104     neighbors = ps->neighbors;
 105   }
 106
 107   i = 0;
 108   max = (ospf_pkt_maxsize(ifa) - length) / sizeof(u32);
 109
 110   /* Fill all neighbors */
 111   if (kind != OHS_SHUTDOWN)
 112   {
 113     WALK_LIST(neigh, ifa->neigh_list)
 114     {
 115       if (i == max)
 116       {
 117         log(L_WARN "%s: Too many neighbors on %s", p->p.name, ifa->ifname);
 118         break;
 119       }
 120       neighbors[i] = htonl(neigh->rid);
 121       i++;
 122     }
 123   }
 124
 125   length += i * sizeof(u32);
 126   pkt->length = htons(length);
 127
 128   OSPF_TRACE(D_PACKETS, "HELLO packet sent via %s", ifa->ifname);
 129
 130   switch(ifa->type)
 131   {
 132   case OSPF_IT_BCAST:
 133   case OSPF_IT_PTP:
 134     ospf_send_to_all(ifa);
 135     break;
 136
 137   case OSPF_IT_NBMA:
 138     if (dirn)           /* Response to received hello */
 139     {
 140       ospf_send_to(ifa, dirn->ip);
 141       break;
 142     }
 143
 144     int to_all = ifa->state > OSPF_IS_DROTHER;
 145     int me_elig = ifa->priority > 0;
 146
 147     if (kind == OHS_POLL)       /* Poll timer */
 148     {
 149       WALK_LIST(nb, ifa->nbma_list)
 150         if (!nb->found && (to_all || (me_elig && nb->eligible)))
 151           ospf_send_to(ifa, nb->ip);
 152     }
 153     else                        /* Hello timer */
 154     {
 155       WALK_LIST(n1, ifa->neigh_list)
 156         if (to_all || (me_elig && (n1->priority > 0)) ||
 157             (n1->rid == ifa->drid) || (n1->rid == ifa->bdrid))
 158           ospf_send_to(ifa, n1->ip);
 159     }
 160     break;
 161
 162   case OSPF_IT_PTMP:
 163     WALK_LIST(n1, ifa->neigh_list)
 164       ospf_send_to(ifa, n1->ip);
 165
 166     WALK_LIST(nb, ifa->nbma_list)
 167       if (!nb->found)
 168         ospf_send_to(ifa, nb->ip);
 169
 170     /* If there is no other target, we also send HELLO packet to the other end */
 171     if (ipa_nonzero(ifa->addr->opposite) && !ifa->strictnbma &&
 172         EMPTY_LIST(ifa->neigh_list) && EMPTY_LIST(ifa->nbma_list))
 173       ospf_send_to(ifa, ifa->addr->opposite);
 174     break;
 175
 176   case OSPF_IT_VLINK:
 177     ospf_send_to(ifa, ifa->vip);
 178     break;
 179
 180   default:
 181     bug("Bug in ospf_send_hello()");
 182   }
 183 }
 184
 185
 186 void
 187 ospf_receive_hello(struct ospf_packet *pkt, struct ospf_iface *ifa,
 188                    struct ospf_neighbor *n, ip_addr faddr)
 189 {
 190   struct ospf_proto *p = ifa->oa->po;
 191   const char *err_dsc = NULL;
 192   u32 rcv_iface_id, rcv_helloint, rcv_deadint, rcv_dr, rcv_bdr;
 193   u8 rcv_options, rcv_priority;
 194   u32 *neighbors;
 195   u32 neigh_count;
 196   uint plen, i, err_val = 0;
 197
 198   /* RFC 2328 10.5 */
 199
 200   /*
 201    * We may not yet havethe associate neighbor, so we use Router ID from the
 202    * packet instead of one from the neighbor structure for log messages.
 203    */
 204   u32 rcv_rid = ntohl(pkt->routerid);
 205   OSPF_TRACE(D_PACKETS, "HELLO packet received from nbr %R on %s", rcv_rid, ifa->ifname);
 206
 207   plen = ntohs(pkt->length);
 208
 209   if (ospf_is_v2(p))
 210   {
 211     struct ospf_hello2_packet *ps = (void *) pkt;
 212
 213     if (plen < sizeof(struct ospf_hello2_packet))
 214       DROP("too short", plen);
 215
 216     rcv_iface_id = 0;
 217     rcv_helloint = ntohs(ps->helloint);
 218     rcv_deadint = ntohl(ps->deadint);
 219     rcv_dr = ntohl(ps->dr);
 220     rcv_bdr = ntohl(ps->bdr);
 221     rcv_options = ps->options;
 222     rcv_priority = ps->priority;
 223
 224     int pxlen = u32_masklen(ntohl(ps->netmask));
 225     if (pxlen < 0)
 226       DROP("prefix garbled", ntohl(ps->netmask));
 227
 228     if ((ifa->type != OSPF_IT_VLINK) &&
 229         (ifa->type != OSPF_IT_PTP) &&
 230         ((uint) pxlen != ifa->addr->pxlen))
 231       DROP("prefix length mismatch", pxlen);
 232
 233     neighbors = ps->neighbors;
 234     neigh_count = (plen - sizeof(struct ospf_hello2_packet)) / sizeof(u32);
 235   }
 236   else /* OSPFv3 */
 237   {
 238     struct ospf_hello3_packet *ps = (void *) pkt;
 239
 240     if (plen < sizeof(struct ospf_hello3_packet))
 241       DROP("too short", plen);
 242
 243     rcv_iface_id = ntohl(ps->iface_id);
 244     rcv_helloint = ntohs(ps->helloint);
 245     rcv_deadint = ntohs(ps->deadint);
 246     rcv_dr = ntohl(ps->dr);
 247     rcv_bdr = ntohl(ps->bdr);
 248     rcv_options = ps->options;
 249     rcv_priority = ps->priority;
 250
 251     neighbors = ps->neighbors;
 252     neigh_count = (plen - sizeof(struct ospf_hello3_packet)) / sizeof(u32);
 253   }
 254
 255   if (rcv_helloint != ifa->helloint)
 256     DROP("hello interval mismatch", rcv_helloint);
 257
 258   if (rcv_deadint != ifa->deadint)
 259     DROP("dead interval mismatch", rcv_deadint);
 260
 261   /* Check whether bits E, N match */
 262   if ((rcv_options ^ ifa->oa->options) & (OPT_E | OPT_N))
 263     DROP("area type mismatch", rcv_options);
 264
 265   /* Check consistency of existing neighbor entry */
 266   if (n)
 267   {
 268     uint t = ifa->type;
 269     if (ospf_is_v2(p) && ((t == OSPF_IT_BCAST) || (t == OSPF_IT_NBMA) || (t == OSPF_IT_PTMP)))
 270     {
 271       /* Neighbor identified by IP address; Router ID may change */
 272       if (n->rid != rcv_rid)
 273       {
 274         OSPF_TRACE(D_EVENTS, "Neighbor %R on %s changed Router ID to %R",
 275                    n->rid, ifa->ifname, rcv_rid);
 276         ospf_neigh_sm(n, INM_KILLNBR);
 277         n = NULL;
 278       }
 279     }
 280     else /* OSPFv3 or OSPFv2/PtP */
 281     {
 282       /* Neighbor identified by Router ID; IP address may change */
 283       if (!ipa_equal(faddr, n->ip))
 284       {
 285         OSPF_TRACE(D_EVENTS, "Neighbor %R on %s changed IP address to %I",
 286                    n->rid, ifa->ifname, n->ip, faddr);
 287         n->ip = faddr;
 288       }
 289     }
 290   }
 291
 292   if (!n)
 293   {
 294     if ((ifa->type == OSPF_IT_NBMA) || (ifa->type == OSPF_IT_PTMP))
 295     {
 296       struct nbma_node *nn = find_nbma_node(ifa, faddr);
 297
 298       if (!nn && ifa->strictnbma)
 299         DROP1("new neighbor denied");
 300
 301       if (nn && (ifa->type == OSPF_IT_NBMA) &&
 302           (((rcv_priority == 0) && nn->eligible) ||
 303            ((rcv_priority > 0) && !nn->eligible)))
 304         DROP("eligibility mismatch", rcv_priority);
 305
 306       if (nn)
 307         nn->found = 1;
 308     }
 309
 310     OSPF_TRACE(D_EVENTS, "New neighbor %R on %s, IP address %I",
 311                rcv_rid, ifa->ifname, faddr);
 312
 313     n = ospf_neighbor_new(ifa);
 314
 315     n->rid = rcv_rid;
 316     n->ip = faddr;
 317     n->dr = rcv_dr;
 318     n->bdr = rcv_bdr;
 319     n->priority = rcv_priority;
 320     n->iface_id = rcv_iface_id;
 321
 322     if (n->ifa->cf->bfd)
 323       ospf_neigh_update_bfd(n, n->ifa->bfd);
 324   }
 325
 326   u32 n_id = ospf_is_v2(p) ? ipa_to_u32(n->ip) : n->rid;
 327
 328   u32 old_dr = n->dr;
 329   u32 old_bdr = n->bdr;
 330   u32 old_priority = n->priority;
 331   u32 old_iface_id = n->iface_id;
 332
 333   n->dr = rcv_dr;
 334   n->bdr = rcv_bdr;
 335   n->priority = rcv_priority;
 336   n->iface_id = rcv_iface_id;
 337
 338
 339   /* Update inactivity timer */
 340   ospf_neigh_sm(n, INM_HELLOREC);
 341
 342   /* RFC 2328 9.5.1 - non-eligible routers reply to hello on NBMA nets */
 343   if (ifa->type == OSPF_IT_NBMA)
 344     if ((ifa->priority == 0) && (n->priority > 0))
 345       ospf_send_hello(n->ifa, OHS_HELLO, n);
 346
 347
 348   /* Examine list of neighbors */
 349   for (i = 0; i < neigh_count; i++)
 350     if (neighbors[i] == htonl(p->router_id))
 351       goto found_self;
 352
 353   ospf_neigh_sm(n, INM_1WAYREC);
 354   return;
 355
 356 found_self:
 357   ospf_neigh_sm(n, INM_2WAYREC);
 358
 359
 360   if (n->iface_id != old_iface_id)
 361   {
 362     /* If neighbor is DR, also update cached DR interface ID */
 363     if (ifa->drid == n->rid)
 364       ifa->dr_iface_id = n->iface_id;
 365
 366     /* RFC 5340 4.4.3 Event 4 - change of neighbor's interface ID */
 367     ospf_notify_rt_lsa(ifa->oa);
 368
 369     /* Missed in RFC 5340 4.4.3 Event 4 - (Px-)Net-LSA uses iface_id to ref Link-LSAs */
 370     ospf_notify_net_lsa(ifa);
 371   }
 372
 373   if (ifa->state == OSPF_IS_WAITING)
 374   {
 375     /* Neighbor is declaring itself DR (and there is no BDR) or as BDR */
 376     if (((n->dr == n_id) && (n->bdr == 0)) || (n->bdr == n_id))
 377       ospf_iface_sm(ifa, ISM_BACKS);
 378   }
 379   else if (ifa->state >= OSPF_IS_DROTHER)
 380   {
 381     /* Neighbor changed priority or started/stopped declaring itself as DR/BDR */
 382     if ((n->priority != old_priority) ||
 383         ((n->dr == n_id) && (old_dr != n_id)) ||
 384         ((n->dr != n_id) && (old_dr == n_id)) ||
 385         ((n->bdr == n_id) && (old_bdr != n_id)) ||
 386         ((n->bdr != n_id) && (old_bdr == n_id)))
 387       ospf_iface_sm(ifa, ISM_NEICH);
 388   }
 389
 390   return;
 391
 392 drop:
 393   LOG_PKT("Bad HELLO packet from nbr %R on %s - %s (%u)",
 394           rcv_rid, ifa->ifname, err_dsc, err_val);
 395 }