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 & HELLO2_OPT_MASK;
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 & HELLO3_OPT_MASK) | (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: }
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