Annotation of embedaddon/bird/proto/ospf/lsalib.c, revision 1.1
1.1 ! misho 1: /*
! 2: * BIRD -- OSPF
! 3: *
! 4: * (c) 1999--2004 Ondrej Filip <feela@network.cz>
! 5: * (c) 2009--2015 Ondrej Zajicek <santiago@crfreenet.org>
! 6: * (c) 2009--2015 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: #include "lib/fletcher16.h"
! 14:
! 15: #ifndef CPU_BIG_ENDIAN
! 16: void
! 17: lsa_hton_hdr(struct ospf_lsa_header *h, struct ospf_lsa_header *n)
! 18: {
! 19: n->age = htons(h->age);
! 20: n->type_raw = htons(h->type_raw);
! 21: n->id = htonl(h->id);
! 22: n->rt = htonl(h->rt);
! 23: n->sn = htonl(h->sn);
! 24: n->checksum = htons(h->checksum);
! 25: n->length = htons(h->length);
! 26: }
! 27:
! 28: void
! 29: lsa_ntoh_hdr(struct ospf_lsa_header *n, struct ospf_lsa_header *h)
! 30: {
! 31: h->age = ntohs(n->age);
! 32: h->type_raw = ntohs(n->type_raw);
! 33: h->id = ntohl(n->id);
! 34: h->rt = ntohl(n->rt);
! 35: h->sn = ntohl(n->sn);
! 36: h->checksum = ntohs(n->checksum);
! 37: h->length = ntohs(n->length);
! 38: }
! 39:
! 40: void
! 41: lsa_hton_body(void *h, void *n, u16 len)
! 42: {
! 43: u32 *hid = h;
! 44: u32 *nid = n;
! 45: uint i;
! 46:
! 47: for (i = 0; i < (len / sizeof(u32)); i++)
! 48: nid[i] = htonl(hid[i]);
! 49: }
! 50:
! 51: void
! 52: lsa_ntoh_body(void *n, void *h, u16 len)
! 53: {
! 54: u32 *nid = n;
! 55: u32 *hid = h;
! 56: uint i;
! 57:
! 58: for (i = 0; i < (len / sizeof(u32)); i++)
! 59: hid[i] = ntohl(nid[i]);
! 60: }
! 61: #endif /* little endian */
! 62:
! 63:
! 64:
! 65: int
! 66: lsa_flooding_allowed(u32 type, u32 domain, struct ospf_iface *ifa)
! 67: {
! 68: /* Handle inactive vlinks */
! 69: if (ifa->state == OSPF_IS_DOWN)
! 70: return 0;
! 71:
! 72: /* 4.5.2 (Case 2) */
! 73: switch (LSA_SCOPE(type))
! 74: {
! 75: case LSA_SCOPE_LINK:
! 76: return ifa->iface_id == domain;
! 77:
! 78: case LSA_SCOPE_AREA:
! 79: return ifa->oa->areaid == domain;
! 80:
! 81: case LSA_SCOPE_AS:
! 82: if (ifa->type == OSPF_IT_VLINK)
! 83: return 0;
! 84: if (!oa_is_ext(ifa->oa))
! 85: return 0;
! 86: return 1;
! 87:
! 88: default:
! 89: log(L_ERR "OSPF: LSA with invalid scope");
! 90: return 0;
! 91: }
! 92: }
! 93:
! 94:
! 95: static int
! 96: unknown_lsa_type(u32 type)
! 97: {
! 98: switch (type)
! 99: {
! 100: case LSA_T_RT:
! 101: case LSA_T_NET:
! 102: case LSA_T_SUM_NET:
! 103: case LSA_T_SUM_RT:
! 104: case LSA_T_EXT:
! 105: case LSA_T_NSSA:
! 106: case LSA_T_LINK:
! 107: case LSA_T_PREFIX:
! 108: return 0;
! 109:
! 110: default:
! 111: return 1;
! 112: }
! 113: }
! 114:
! 115: #define LSA_V2_TMAX 8
! 116: static const u16 lsa_v2_types[LSA_V2_TMAX] =
! 117: {0, LSA_T_RT, LSA_T_NET, LSA_T_SUM_NET, LSA_T_SUM_RT, LSA_T_EXT, 0, LSA_T_NSSA};
! 118:
! 119: void
! 120: lsa_get_type_domain_(u32 itype, struct ospf_iface *ifa, u32 *otype, u32 *domain)
! 121: {
! 122: if (ospf_is_v2(ifa->oa->po))
! 123: {
! 124: itype = itype & LSA_T_V2_MASK;
! 125: itype = (itype < LSA_V2_TMAX) ? lsa_v2_types[itype] : 0;
! 126: }
! 127: else
! 128: {
! 129: /* For unkown LSAs without U-bit change scope to LSA_SCOPE_LINK */
! 130: if (unknown_lsa_type(itype) && !(itype & LSA_UBIT))
! 131: itype = itype & ~LSA_SCOPE_MASK;
! 132: }
! 133:
! 134: *otype = itype;
! 135:
! 136: switch (LSA_SCOPE(itype))
! 137: {
! 138: case LSA_SCOPE_LINK:
! 139: *domain = ifa->iface_id;
! 140: return;
! 141:
! 142: case LSA_SCOPE_AREA:
! 143: *domain = ifa->oa->areaid;
! 144: return;
! 145:
! 146: case LSA_SCOPE_AS:
! 147: default:
! 148: *domain = 0;
! 149: return;
! 150: }
! 151: }
! 152:
! 153:
! 154: void
! 155: lsa_generate_checksum(struct ospf_lsa_header *lsa, const u8 *body)
! 156: {
! 157: struct fletcher16_context ctx;
! 158: struct ospf_lsa_header hdr;
! 159: u16 len = lsa->length;
! 160:
! 161: /*
! 162: * lsa and body are in the host order, we need to compute Fletcher-16 checksum
! 163: * for data in the network order. We also skip the initial age field.
! 164: */
! 165:
! 166: lsa_hton_hdr(lsa, &hdr);
! 167: hdr.checksum = 0;
! 168:
! 169: fletcher16_init(&ctx);
! 170: fletcher16_update(&ctx, (u8 *) &hdr + 2, sizeof(struct ospf_lsa_header) - 2);
! 171: fletcher16_update_n32(&ctx, body, len - sizeof(struct ospf_lsa_header));
! 172: lsa->checksum = fletcher16_final(&ctx, len, OFFSETOF(struct ospf_lsa_header, checksum));
! 173: }
! 174:
! 175: u16
! 176: lsa_verify_checksum(const void *lsa_n, int lsa_len)
! 177: {
! 178: struct fletcher16_context ctx;
! 179:
! 180: /* The whole LSA is at lsa_n in net order, we just skip initial age field */
! 181:
! 182: fletcher16_init(&ctx);
! 183: fletcher16_update(&ctx, (u8 *) lsa_n + 2, lsa_len - 2);
! 184:
! 185: return fletcher16_compute(&ctx) == 0;
! 186: }
! 187:
! 188:
! 189: int
! 190: lsa_comp(struct ospf_lsa_header *l1, struct ospf_lsa_header *l2)
! 191: /* Return codes from point of view of l1 */
! 192: {
! 193: u32 sn1, sn2;
! 194:
! 195: sn1 = l1->sn - LSA_INITSEQNO + 1;
! 196: sn2 = l2->sn - LSA_INITSEQNO + 1;
! 197:
! 198: if (sn1 > sn2)
! 199: return CMP_NEWER;
! 200: if (sn1 < sn2)
! 201: return CMP_OLDER;
! 202:
! 203: if (l1->checksum != l2->checksum)
! 204: return l1->checksum < l2->checksum ? CMP_OLDER : CMP_NEWER;
! 205:
! 206: if ((l1->age == LSA_MAXAGE) && (l2->age != LSA_MAXAGE))
! 207: return CMP_NEWER;
! 208: if ((l2->age == LSA_MAXAGE) && (l1->age != LSA_MAXAGE))
! 209: return CMP_OLDER;
! 210:
! 211: if (ABS(l1->age - l2->age) > LSA_MAXAGEDIFF)
! 212: return l1->age < l2->age ? CMP_NEWER : CMP_OLDER;
! 213:
! 214: return CMP_SAME;
! 215: }
! 216:
! 217:
! 218: static inline int
! 219: lsa_walk_rt2(struct ospf_lsa_rt_walk *rt)
! 220: {
! 221: if (rt->buf >= rt->bufend)
! 222: return 0;
! 223:
! 224: struct ospf_lsa_rt2_link *l = rt->buf;
! 225: rt->buf += sizeof(struct ospf_lsa_rt2_link) + l->no_tos * sizeof(struct ospf_lsa_rt2_tos);
! 226:
! 227: rt->type = l->type;
! 228: rt->metric = l->metric;
! 229: rt->id = l->id;
! 230: rt->data = l->data;
! 231: return 1;
! 232: }
! 233:
! 234: static inline int
! 235: lsa_walk_rt3(struct ospf_lsa_rt_walk *rt)
! 236: {
! 237: while (rt->buf >= rt->bufend)
! 238: {
! 239: rt->en = ospf_hash_find_rt3_next(rt->en);
! 240: if (!rt->en)
! 241: return 0;
! 242:
! 243: rt->buf = rt->en->lsa_body;
! 244: rt->bufend = rt->buf + rt->en->lsa.length - sizeof(struct ospf_lsa_header);
! 245: rt->buf += sizeof(struct ospf_lsa_rt);
! 246: }
! 247:
! 248: struct ospf_lsa_rt3_link *l = rt->buf;
! 249: rt->buf += sizeof(struct ospf_lsa_rt3_link);
! 250:
! 251: rt->type = l->type;
! 252: rt->metric = l->metric;
! 253: rt->lif = l->lif;
! 254: rt->nif = l->nif;
! 255: rt->id = l->id;
! 256: return 1;
! 257: }
! 258:
! 259: void
! 260: lsa_walk_rt_init(struct ospf_proto *p, struct top_hash_entry *act, struct ospf_lsa_rt_walk *rt)
! 261: {
! 262: rt->ospf2 = ospf_is_v2(p);
! 263: rt->id = rt->data = rt->lif = rt->nif = 0;
! 264:
! 265: if (rt->ospf2)
! 266: rt->en = act;
! 267: else
! 268: rt->en = ospf_hash_find_rt3_first(p->gr, act->domain, act->lsa.rt);
! 269:
! 270: rt->buf = rt->en->lsa_body;
! 271: rt->bufend = rt->buf + rt->en->lsa.length - sizeof(struct ospf_lsa_header);
! 272: rt->buf += sizeof(struct ospf_lsa_rt);
! 273: }
! 274:
! 275: int
! 276: lsa_walk_rt(struct ospf_lsa_rt_walk *rt)
! 277: {
! 278: return rt->ospf2 ? lsa_walk_rt2(rt) : lsa_walk_rt3(rt);
! 279: }
! 280:
! 281:
! 282: void
! 283: lsa_parse_sum_net(struct top_hash_entry *en, int ospf2, ip_addr *ip, int *pxlen, u8 *pxopts, u32 *metric)
! 284: {
! 285: if (ospf2)
! 286: {
! 287: struct ospf_lsa_sum2 *ls = en->lsa_body;
! 288: *ip = ipa_from_u32(en->lsa.id & ls->netmask);
! 289: *pxlen = u32_masklen(ls->netmask);
! 290: *pxopts = 0;
! 291: *metric = ls->metric & LSA_METRIC_MASK;
! 292: }
! 293: else
! 294: {
! 295: struct ospf_lsa_sum3_net *ls = en->lsa_body;
! 296: u16 rest;
! 297: lsa_get_ipv6_prefix(ls->prefix, ip, pxlen, pxopts, &rest);
! 298: *metric = ls->metric & LSA_METRIC_MASK;
! 299: }
! 300: }
! 301:
! 302: void
! 303: lsa_parse_sum_rt(struct top_hash_entry *en, int ospf2, u32 *drid, u32 *metric, u32 *options)
! 304: {
! 305: if (ospf2)
! 306: {
! 307: struct ospf_lsa_sum2 *ls = en->lsa_body;
! 308: *drid = en->lsa.id;
! 309: *metric = ls->metric & LSA_METRIC_MASK;
! 310: *options = 0;
! 311: }
! 312: else
! 313: {
! 314: struct ospf_lsa_sum3_rt *ls = en->lsa_body;
! 315: *drid = ls->drid;
! 316: *metric = ls->metric & LSA_METRIC_MASK;
! 317: *options = ls->options & LSA_OPTIONS_MASK;
! 318: }
! 319: }
! 320:
! 321: void
! 322: lsa_parse_ext(struct top_hash_entry *en, int ospf2, struct ospf_lsa_ext_local *rt)
! 323: {
! 324: if (ospf2)
! 325: {
! 326: struct ospf_lsa_ext2 *ext = en->lsa_body;
! 327: rt->ip = ipa_from_u32(en->lsa.id & ext->netmask);
! 328: rt->pxlen = u32_masklen(ext->netmask);
! 329: rt->pxopts = 0;
! 330: rt->metric = ext->metric & LSA_METRIC_MASK;
! 331: rt->ebit = ext->metric & LSA_EXT2_EBIT;
! 332:
! 333: rt->fbit = ext->fwaddr;
! 334: rt->fwaddr = ipa_from_u32(ext->fwaddr);
! 335:
! 336: rt->tag = ext->tag;
! 337: rt->propagate = lsa_get_options(&en->lsa) & OPT_P;
! 338: }
! 339: else
! 340: {
! 341: struct ospf_lsa_ext3 *ext = en->lsa_body;
! 342: u16 rest;
! 343: u32 *buf = lsa_get_ipv6_prefix(ext->rest, &rt->ip, &rt->pxlen, &rt->pxopts, &rest);
! 344: rt->metric = ext->metric & LSA_METRIC_MASK;
! 345: rt->ebit = ext->metric & LSA_EXT3_EBIT;
! 346:
! 347: rt->fbit = ext->metric & LSA_EXT3_FBIT;
! 348: if (rt->fbit)
! 349: buf = lsa_get_ipv6_addr(buf, &rt->fwaddr);
! 350: else
! 351: rt->fwaddr = IPA_NONE;
! 352:
! 353: rt->tag = (ext->metric & LSA_EXT3_TBIT) ? *buf++ : 0;
! 354: rt->propagate = rt->pxopts & OPT_PX_P;
! 355: }
! 356: }
! 357:
! 358: #define HDRLEN sizeof(struct ospf_lsa_header)
! 359:
! 360: static int
! 361: lsa_validate_rt2(struct ospf_lsa_header *lsa, struct ospf_lsa_rt *body)
! 362: {
! 363: if (lsa->length < (HDRLEN + sizeof(struct ospf_lsa_rt)))
! 364: return 0;
! 365:
! 366: uint i = 0;
! 367: void *buf = body;
! 368: void *bufend = buf + lsa->length - HDRLEN;
! 369: buf += sizeof(struct ospf_lsa_rt);
! 370:
! 371: while (buf < bufend)
! 372: {
! 373: struct ospf_lsa_rt2_link *l = buf;
! 374: buf += sizeof(struct ospf_lsa_rt2_link) + l->no_tos * sizeof(struct ospf_lsa_rt2_tos);
! 375: i++;
! 376:
! 377: if (buf > bufend)
! 378: return 0;
! 379:
! 380: if (!((l->type == LSART_PTP) ||
! 381: (l->type == LSART_NET) ||
! 382: (l->type == LSART_STUB) ||
! 383: (l->type == LSART_VLNK)))
! 384: return 0;
! 385: }
! 386:
! 387: if ((body->options & LSA_RT2_LINKS) != i)
! 388: return 0;
! 389:
! 390: return 1;
! 391: }
! 392:
! 393:
! 394: static int
! 395: lsa_validate_rt3(struct ospf_lsa_header *lsa, struct ospf_lsa_rt *body)
! 396: {
! 397: if (lsa->length < (HDRLEN + sizeof(struct ospf_lsa_rt)))
! 398: return 0;
! 399:
! 400: void *buf = body;
! 401: void *bufend = buf + lsa->length - HDRLEN;
! 402: buf += sizeof(struct ospf_lsa_rt);
! 403:
! 404: while (buf < bufend)
! 405: {
! 406: struct ospf_lsa_rt3_link *l = buf;
! 407: buf += sizeof(struct ospf_lsa_rt3_link);
! 408:
! 409: if (buf > bufend)
! 410: return 0;
! 411:
! 412: if (!((l->type == LSART_PTP) ||
! 413: (l->type == LSART_NET) ||
! 414: (l->type == LSART_VLNK)))
! 415: return 0;
! 416: }
! 417: return 1;
! 418: }
! 419:
! 420: static int
! 421: lsa_validate_net(struct ospf_lsa_header *lsa, struct ospf_lsa_net *body UNUSED)
! 422: {
! 423: if (lsa->length < (HDRLEN + sizeof(struct ospf_lsa_net)))
! 424: return 0;
! 425:
! 426: return 1;
! 427: }
! 428:
! 429: static int
! 430: lsa_validate_sum2(struct ospf_lsa_header *lsa, struct ospf_lsa_sum2 *body)
! 431: {
! 432: if (lsa->length < (HDRLEN + sizeof(struct ospf_lsa_sum2)))
! 433: return 0;
! 434:
! 435: /* First field should have TOS = 0, we ignore other TOS fields */
! 436: if ((body->metric & LSA_SUM2_TOS) != 0)
! 437: return 0;
! 438:
! 439: return 1;
! 440: }
! 441:
! 442: static inline int
! 443: pxlen(u32 *buf)
! 444: {
! 445: return *buf >> 24;
! 446: }
! 447:
! 448: static int
! 449: lsa_validate_sum3_net(struct ospf_lsa_header *lsa, struct ospf_lsa_sum3_net *body)
! 450: {
! 451: if (lsa->length < (HDRLEN + sizeof(struct ospf_lsa_sum3_net) + 4))
! 452: return 0;
! 453:
! 454: u8 pxl = pxlen(body->prefix);
! 455: if (pxl > MAX_PREFIX_LENGTH)
! 456: return 0;
! 457:
! 458: if (lsa->length != (HDRLEN + sizeof(struct ospf_lsa_sum3_net) +
! 459: IPV6_PREFIX_SPACE(pxl)))
! 460: return 0;
! 461:
! 462: return 1;
! 463: }
! 464:
! 465: static int
! 466: lsa_validate_sum3_rt(struct ospf_lsa_header *lsa, struct ospf_lsa_sum3_rt *body UNUSED)
! 467: {
! 468: if (lsa->length != (HDRLEN + sizeof(struct ospf_lsa_sum3_rt)))
! 469: return 0;
! 470:
! 471: return 1;
! 472: }
! 473:
! 474: static int
! 475: lsa_validate_ext2(struct ospf_lsa_header *lsa, struct ospf_lsa_ext2 *body)
! 476: {
! 477: if (lsa->length < (HDRLEN + sizeof(struct ospf_lsa_ext2)))
! 478: return 0;
! 479:
! 480: /* First field should have TOS = 0, we ignore other TOS fields */
! 481: if ((body->metric & LSA_EXT2_TOS) != 0)
! 482: return 0;
! 483:
! 484: return 1;
! 485: }
! 486:
! 487: static int
! 488: lsa_validate_ext3(struct ospf_lsa_header *lsa, struct ospf_lsa_ext3 *body)
! 489: {
! 490: if (lsa->length < (HDRLEN + sizeof(struct ospf_lsa_ext3) + 4))
! 491: return 0;
! 492:
! 493: u8 pxl = pxlen(body->rest);
! 494: if (pxl > MAX_PREFIX_LENGTH)
! 495: return 0;
! 496:
! 497: int len = IPV6_PREFIX_SPACE(pxl);
! 498: if (body->metric & LSA_EXT3_FBIT) // forwardinf address
! 499: len += 16;
! 500: if (body->metric & LSA_EXT3_TBIT) // route tag
! 501: len += 4;
! 502: if (*body->rest & 0xFFFF) // referenced LS type field
! 503: len += 4;
! 504:
! 505: if (lsa->length != (HDRLEN + sizeof(struct ospf_lsa_ext3) + len))
! 506: return 0;
! 507:
! 508: return 1;
! 509: }
! 510:
! 511: static int
! 512: lsa_validate_pxlist(struct ospf_lsa_header *lsa, u32 pxcount, uint offset, u8 *pbuf)
! 513: {
! 514: uint bound = lsa->length - HDRLEN - 4;
! 515: u32 i;
! 516:
! 517: for (i = 0; i < pxcount; i++)
! 518: {
! 519: if (offset > bound)
! 520: return 0;
! 521:
! 522: u8 pxl = pxlen((u32 *) (pbuf + offset));
! 523: if (pxl > MAX_PREFIX_LENGTH)
! 524: return 0;
! 525:
! 526: offset += IPV6_PREFIX_SPACE(pxl);
! 527: }
! 528:
! 529: if (lsa->length != (HDRLEN + offset))
! 530: return 0;
! 531:
! 532: return 1;
! 533: }
! 534:
! 535: static int
! 536: lsa_validate_link(struct ospf_lsa_header *lsa, struct ospf_lsa_link *body)
! 537: {
! 538: if (lsa->length < (HDRLEN + sizeof(struct ospf_lsa_link)))
! 539: return 0;
! 540:
! 541: return lsa_validate_pxlist(lsa, body->pxcount, sizeof(struct ospf_lsa_link), (u8 *) body);
! 542: }
! 543:
! 544: static int
! 545: lsa_validate_prefix(struct ospf_lsa_header *lsa, struct ospf_lsa_prefix *body)
! 546: {
! 547: if (lsa->length < (HDRLEN + sizeof(struct ospf_lsa_prefix)))
! 548: return 0;
! 549:
! 550: return lsa_validate_pxlist(lsa, body->pxcount, sizeof(struct ospf_lsa_prefix), (u8 *) body);
! 551: }
! 552:
! 553:
! 554: /**
! 555: * lsa_validate - check whether given LSA is valid
! 556: * @lsa: LSA header
! 557: * @lsa_type: one of %LSA_T_xxx
! 558: * @ospf2: %true means OSPF version 2, %false means OSPF version 3
! 559: * @body: pointer to LSA body
! 560: *
! 561: * Checks internal structure of given LSA body (minimal length,
! 562: * consistency). Returns true if valid.
! 563: */
! 564: int
! 565: lsa_validate(struct ospf_lsa_header *lsa, u32 lsa_type, int ospf2, void *body)
! 566: {
! 567: if (ospf2)
! 568: {
! 569: switch (lsa_type)
! 570: {
! 571: case LSA_T_RT:
! 572: return lsa_validate_rt2(lsa, body);
! 573: case LSA_T_NET:
! 574: return lsa_validate_net(lsa, body);
! 575: case LSA_T_SUM_NET:
! 576: return lsa_validate_sum2(lsa, body);
! 577: case LSA_T_SUM_RT:
! 578: return lsa_validate_sum2(lsa, body);
! 579: case LSA_T_EXT:
! 580: case LSA_T_NSSA:
! 581: return lsa_validate_ext2(lsa, body);
! 582: default:
! 583: return 0; /* Should not happen, unknown LSAs are already rejected */
! 584: }
! 585: }
! 586: else
! 587: {
! 588: switch (lsa_type)
! 589: {
! 590: case LSA_T_RT:
! 591: return lsa_validate_rt3(lsa, body);
! 592: case LSA_T_NET:
! 593: return lsa_validate_net(lsa, body);
! 594: case LSA_T_SUM_NET:
! 595: return lsa_validate_sum3_net(lsa, body);
! 596: case LSA_T_SUM_RT:
! 597: return lsa_validate_sum3_rt(lsa, body);
! 598: case LSA_T_EXT:
! 599: case LSA_T_NSSA:
! 600: return lsa_validate_ext3(lsa, body);
! 601: case LSA_T_LINK:
! 602: return lsa_validate_link(lsa, body);
! 603: case LSA_T_PREFIX:
! 604: return lsa_validate_prefix(lsa, body);
! 605: default:
! 606: return 1; /* Unknown LSAs are OK in OSPFv3 */
! 607: }
! 608: }
! 609: }
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