proto/bgp/attrs.c

   1 /*
   2  *      BIRD -- BGP Attributes
   3  *
   4  *      (c) 2000 Martin Mares <mj@ucw.cz>
   5  *      (c) 2008--2016 Ondrej Zajicek <santiago@crfreenet.org>
   6  *      (c) 2008--2016 CZ.NIC z.s.p.o.
   7  *
   8  *      Can be freely distributed and used under the terms of the GNU GPL.
   9  */
  10
  11 #undef LOCAL_DEBUG
  12
  13 #include <stdlib.h>
  14
  15 #include "nest/bird.h"
  16 #include "nest/iface.h"
  17 #include "nest/protocol.h"
  18 #include "nest/route.h"
  19 #include "nest/attrs.h"
  20 #include "conf/conf.h"
  21 #include "lib/resource.h"
  22 #include "lib/string.h"
  23 #include "lib/unaligned.h"
  24
  25 #include "bgp.h"
  26
  27 /*
  28  *   UPDATE message error handling
  29  *
  30  * All checks from RFC 4271 6.3 are done as specified with these exceptions:
  31  *  - The semantic check of an IP address from NEXT_HOP attribute is missing.
  32  *  - Checks of some optional attribute values are missing.
  33  *  - Syntactic and semantic checks of NLRIs (done in DECODE_PREFIX())
  34  *    are probably inadequate.
  35  *
  36  * Loop detection based on AS_PATH causes updates to be withdrawn. RFC
  37  * 4271 does not explicitly specifiy the behavior in that case.
  38  *
  39  * Loop detection related to route reflection (based on ORIGINATOR_ID
  40  * and CLUSTER_LIST) causes updates to be withdrawn. RFC 4456 8
  41  * specifies that such updates should be ignored, but that is generally
  42  * a bad idea.
  43  *
  44  * BGP attribute table has several hooks:
  45  *
  46  * export - Hook that validates and normalizes attribute during export phase.
  47  * Receives eattr, may modify it (e.g., sort community lists for canonical
  48  * representation), UNSET() it (e.g., skip empty lists), or WITHDRAW() it if
  49  * necessary. May assume that eattr has value valid w.r.t. its type, but may be
  50  * invalid w.r.t. BGP constraints. Optional.
  51  *
  52  * encode - Hook that converts internal representation to external one during
  53  * packet writing. Receives eattr and puts it in the buffer (including attribute
  54  * header). Returns number of bytes, or -1 if not enough space. May assume that
  55  * eattr has value valid w.r.t. its type and validated by export hook. Mandatory
  56  * for all known attributes that exist internally after export phase (i.e., all
  57  * except pseudoattributes MP_(UN)REACH_NLRI).
  58  *
  59  * decode - Hook that converts external representation to internal one during
  60  * packet parsing. Receives attribute data in buffer, validates it and adds
  61  * attribute to ea_list. If data are invalid, steps DISCARD(), WITHDRAW() or
  62  * bgp_parse_error() may be used to escape. Mandatory for all known attributes.
  63  *
  64  * format - Optional hook that converts eattr to textual representation.
  65  */
  66
  67
  68 struct bgp_attr_desc {
  69   const char *name;
  70   uint type;
  71   uint flags;
  72   void (*export)(struct bgp_export_state *s, eattr *a);
  73   int  (*encode)(struct bgp_write_state *s, eattr *a, byte *buf, uint size);
  74   void (*decode)(struct bgp_parse_state *s, uint code, uint flags, byte *data, uint len, ea_list **to);
  75   void (*format)(eattr *ea, byte *buf, uint size);
  76 };
  77
  78 static const struct bgp_attr_desc bgp_attr_table[];
  79
  80 static inline int bgp_attr_known(uint code);
  81
  82 eattr *
  83 bgp_set_attr(ea_list **attrs, struct linpool *pool, uint code, uint flags, uintptr_t val)
  84 {
  85   ASSERT(bgp_attr_known(code));
  86
  87   return ea_set_attr(
  88       attrs,
  89       pool,
  90       EA_CODE(PROTOCOL_BGP, code),
  91       flags,
  92       bgp_attr_table[code].type,
  93       val
  94   );
  95 }
  96
  97
  98
  99 #define REPORT(msg, args...) \
 100   ({ log(L_REMOTE "%s: " msg, s->proto->p.name, ## args); })
 101
 102 #define DISCARD(msg, args...) \
 103   ({ REPORT(msg, ## args); return; })
 104
 105 #define WITHDRAW(msg, args...) \
 106   ({ REPORT(msg, ## args); s->err_withdraw = 1; return; })
 107
 108 #define UNSET(a) \
 109   ({ a->type = EAF_TYPE_UNDEF; return; })
 110
 111 #define NEW_BGP         "Discarding %s attribute received from AS4-aware neighbor"
 112 #define BAD_EBGP        "Discarding %s attribute received from EBGP neighbor"
 113 #define BAD_LENGTH      "Malformed %s attribute - invalid length (%u)"
 114 #define BAD_VALUE       "Malformed %s attribute - invalid value (%u)"
 115 #define NO_MANDATORY    "Missing mandatory %s attribute"
 116
 117
 118 static inline int
 119 bgp_put_attr_hdr3(byte *buf, uint code, uint flags, uint len)
 120 {
 121   *buf++ = flags;
 122   *buf++ = code;
 123   *buf++ = len;
 124   return 3;
 125 }
 126
 127 static inline int
 128 bgp_put_attr_hdr4(byte *buf, uint code, uint flags, uint len)
 129 {
 130   *buf++ = flags | BAF_EXT_LEN;
 131   *buf++ = code;
 132   put_u16(buf, len);
 133   return 4;
 134 }
 135
 136 static inline int
 137 bgp_put_attr_hdr(byte *buf, uint code, uint flags, uint len)
 138 {
 139   if (len < 256)
 140     return bgp_put_attr_hdr3(buf, code, flags, len);
 141   else
 142     return bgp_put_attr_hdr4(buf, code, flags, len);
 143 }
 144
 145 static int
 146 bgp_encode_u8(struct bgp_write_state *s UNUSED, eattr *a, byte *buf, uint size)
 147 {
 148   if (size < (3+1))
 149     return -1;
 150
 151   bgp_put_attr_hdr3(buf, EA_ID(a->id), a->flags, 1);
 152   buf[3] = a->u.data;
 153
 154   return 3+1;
 155 }
 156
 157 static int
 158 bgp_encode_u32(struct bgp_write_state *s UNUSED, eattr *a, byte *buf, uint size)
 159 {
 160   if (size < (3+4))
 161     return -1;
 162
 163   bgp_put_attr_hdr3(buf, EA_ID(a->id), a->flags, 4);
 164   put_u32(buf+3, a->u.data);
 165
 166   return 3+4;
 167 }
 168
 169 static int
 170 bgp_encode_u32s(struct bgp_write_state *s UNUSED, eattr *a, byte *buf, uint size)
 171 {
 172   uint len = a->u.ptr->length;
 173
 174   if (size < (4+len))
 175     return -1;
 176
 177   uint hdr = bgp_put_attr_hdr(buf, EA_ID(a->id), a->flags, len);
 178   put_u32s(buf + hdr, (u32 *) a->u.ptr->data, len / 4);
 179
 180   return hdr + len;
 181 }
 182
 183 static int
 184 bgp_put_attr(byte *buf, uint size, uint code, uint flags, byte *data, uint len)
 185 {
 186   if (size < (4+len))
 187     return -1;
 188
 189   uint hdr = bgp_put_attr_hdr(buf, code, flags, len);
 190   memcpy(buf + hdr, data, len);
 191
 192   return hdr + len;
 193 }
 194
 195 static int
 196 bgp_encode_raw(struct bgp_write_state *s UNUSED, eattr *a, byte *buf, uint size)
 197 {
 198   return bgp_put_attr(buf, size, EA_ID(a->id), a->flags, a->u.ptr->data, a->u.ptr->length);
 199 }
 200
 201
 202 /*
 203  *      Attribute hooks
 204  */
 205
 206 static void
 207 bgp_export_origin(struct bgp_export_state *s, eattr *a)
 208 {
 209   if (a->u.data > 2)
 210     WITHDRAW(BAD_VALUE, "ORIGIN", a->u.data);
 211 }
 212
 213 static void
 214 bgp_decode_origin(struct bgp_parse_state *s, uint code UNUSED, uint flags, byte *data, uint len, ea_list **to)
 215 {
 216   if (len != 1)
 217     WITHDRAW(BAD_LENGTH, "ORIGIN", len);
 218
 219   if (data[0] > 2)
 220     WITHDRAW(BAD_VALUE, "ORIGIN", data[0]);
 221
 222   bgp_set_attr_u32(to, s->pool, BA_ORIGIN, flags, data[0]);
 223 }
 224
 225 static void
 226 bgp_format_origin(eattr *a, byte *buf, uint size UNUSED)
 227 {
 228   static const char *bgp_origin_names[] = { "IGP", "EGP", "Incomplete" };
 229
 230   bsprintf(buf, (a->u.data <= 2) ? bgp_origin_names[a->u.data] : "?");
 231 }
 232
 233
 234 static int
 235 bgp_encode_as_path(struct bgp_write_state *s, eattr *a, byte *buf, uint size)
 236 {
 237   byte *data = a->u.ptr->data;
 238   uint len = a->u.ptr->length;
 239
 240   if (!s->as4_session)
 241   {
 242     /* Prepare 16-bit AS_PATH (from 32-bit one) in a temporary buffer */
 243     byte *src = data;
 244     data = alloca(len);
 245     len = as_path_32to16(data, src, len);
 246   }
 247
 248   return bgp_put_attr(buf, size, BA_AS_PATH, a->flags, data, len);
 249 }
 250
 251 static void
 252 bgp_decode_as_path(struct bgp_parse_state *s, uint code UNUSED, uint flags, byte *data, uint len, ea_list **to)
 253 {
 254   struct bgp_proto *p = s->proto;
 255   int as_length = s->as4_session ? 4 : 2;
 256   int as_confed = p->cf->confederation && p->is_interior;
 257   char err[128];
 258
 259   if (!as_path_valid(data, len, as_length, as_confed, err, sizeof(err)))
 260     WITHDRAW("Malformed AS_PATH attribute - %s", err);
 261
 262   /* In some circumstances check for initial AS_CONFED_SEQUENCE; RFC 5065 5.0 */
 263   if (p->is_interior && !p->is_internal &&
 264       ((len < 2) || (data[0] != AS_PATH_CONFED_SEQUENCE)))
 265     WITHDRAW("Malformed AS_PATH attribute - %s", "missing initial AS_CONFED_SEQUENCE");
 266
 267   if (!s->as4_session)
 268   {
 269     /* Prepare 32-bit AS_PATH (from 16-bit one) in a temporary buffer */
 270     byte *src = data;
 271     data = alloca(2*len);
 272     len = as_path_16to32(data, src, len);
 273   }
 274
 275   bgp_set_attr_data(to, s->pool, BA_AS_PATH, flags, data, len);
 276 }
 277
 278
 279 static int
 280 bgp_encode_next_hop(struct bgp_write_state *s, eattr *a, byte *buf, uint size)
 281 {
 282   /*
 283    * The NEXT_HOP attribute is used only in traditional (IPv4) BGP. In MP-BGP,
 284    * the next hop is encoded as a part of the MP_REACH_NLRI attribute, so we
 285    * store it and encode it later by AFI-specific hooks.
 286    */
 287
 288   if (!s->mp_reach)
 289   {
 290     // ASSERT(a->u.ptr->length == sizeof(ip_addr));
 291
 292     /* FIXME: skip IPv6 next hops for IPv4 routes during MRT dump */
 293     ip_addr *addr = (void *) a->u.ptr->data;
 294     if ((a->u.ptr->length != sizeof(ip_addr)) || !ipa_is_ip4(*addr))
 295       return 0;
 296
 297     if (size < (3+4))
 298       return -1;
 299
 300     bgp_put_attr_hdr3(buf, BA_NEXT_HOP, a->flags, 4);
 301     put_ip4(buf+3, ipa_to_ip4(*addr));
 302
 303     return 3+4;
 304   }
 305   else
 306   {
 307     s->mp_next_hop = a;
 308     return 0;
 309   }
 310 }
 311
 312 static void
 313 bgp_decode_next_hop(struct bgp_parse_state *s, uint code UNUSED, uint flags UNUSED, byte *data, uint len, ea_list **to UNUSED)
 314 {
 315   if (len != 4)
 316     WITHDRAW(BAD_LENGTH, "NEXT_HOP", len);
 317
 318   /* Semantic checks are done later */
 319   s->ip_next_hop_len = len;
 320   s->ip_next_hop_data = data;
 321 }
 322
 323 /* TODO: This function should use AF-specific hook */
 324 static void
 325 bgp_format_next_hop(eattr *a, byte *buf, uint size UNUSED)
 326 {
 327   ip_addr *nh = (void *) a->u.ptr->data;
 328   uint len = a->u.ptr->length;
 329
 330   ASSERT((len == 16) || (len == 32));
 331
 332   /* in IPv6, we may have two addresses in NEXT HOP */
 333   if ((len == 16) || ipa_zero(nh[1]))
 334     bsprintf(buf, "%I", nh[0]);
 335   else
 336     bsprintf(buf, "%I %I", nh[0], nh[1]);
 337 }
 338
 339
 340 static void
 341 bgp_decode_med(struct bgp_parse_state *s, uint code UNUSED, uint flags, byte *data, uint len, ea_list **to)
 342 {
 343   if (len != 4)
 344     WITHDRAW(BAD_LENGTH, "MULTI_EXIT_DISC", len);
 345
 346   u32 val = get_u32(data);
 347   bgp_set_attr_u32(to, s->pool, BA_MULTI_EXIT_DISC, flags, val);
 348 }
 349
 350
 351 static void
 352 bgp_export_local_pref(struct bgp_export_state *s, eattr *a)
 353 {
 354   if (!s->proto->is_interior && !s->proto->cf->allow_local_pref)
 355     UNSET(a);
 356 }
 357
 358 static void
 359 bgp_decode_local_pref(struct bgp_parse_state *s, uint code UNUSED, uint flags, byte *data, uint len, ea_list **to)
 360 {
 361   if (!s->proto->is_interior && !s->proto->cf->allow_local_pref)
 362     DISCARD(BAD_EBGP, "LOCAL_PREF");
 363
 364   if (len != 4)
 365     WITHDRAW(BAD_LENGTH, "LOCAL_PREF", len);
 366
 367   u32 val = get_u32(data);
 368   bgp_set_attr_u32(to, s->pool, BA_LOCAL_PREF, flags, val);
 369 }
 370
 371
 372 static void
 373 bgp_decode_atomic_aggr(struct bgp_parse_state *s, uint code UNUSED, uint flags, byte *data UNUSED, uint len, ea_list **to)
 374 {
 375   if (len != 0)
 376     DISCARD(BAD_LENGTH, "ATOMIC_AGGR", len);
 377
 378   bgp_set_attr_data(to, s->pool, BA_ATOMIC_AGGR, flags, NULL, 0);
 379 }
 380
 381 static int
 382 bgp_encode_aggregator(struct bgp_write_state *s, eattr *a, byte *buf, uint size)
 383 {
 384   byte *data = a->u.ptr->data;
 385   uint len = a->u.ptr->length;
 386
 387   if (!s->as4_session)
 388   {
 389     /* Prepare 16-bit AGGREGATOR (from 32-bit one) in a temporary buffer */
 390     byte *src = data;
 391     data = alloca(6);
 392     len = aggregator_32to16(data, src);
 393   }
 394
 395   return bgp_put_attr(buf, size, BA_AGGREGATOR, a->flags, data, len);
 396 }
 397
 398 static void
 399 bgp_decode_aggregator(struct bgp_parse_state *s, uint code UNUSED, uint flags, byte *data, uint len, ea_list **to)
 400 {
 401   if (len != (s->as4_session ? 8 : 6))
 402     DISCARD(BAD_LENGTH, "AGGREGATOR", len);
 403
 404   if (!s->as4_session)
 405   {
 406     /* Prepare 32-bit AGGREGATOR (from 16-bit one) in a temporary buffer */
 407     byte *src = data;
 408     data = alloca(8);
 409     len = aggregator_16to32(data, src);
 410   }
 411
 412   bgp_set_attr_data(to, s->pool, BA_AGGREGATOR, flags, data, len);
 413 }
 414
 415 static void
 416 bgp_format_aggregator(eattr *a, byte *buf, uint size UNUSED)
 417 {
 418   byte *data = a->u.ptr->data;
 419
 420   bsprintf(buf, "%I4 AS%u", get_ip4(data+4), get_u32(data+0));
 421 }
 422
 423
 424 static void
 425 bgp_export_community(struct bgp_export_state *s, eattr *a)
 426 {
 427   if (a->u.ptr->length == 0)
 428     UNSET(a);
 429
 430   a->u.ptr = int_set_sort(s->pool, a->u.ptr);
 431 }
 432
 433 static void
 434 bgp_decode_community(struct bgp_parse_state *s, uint code UNUSED, uint flags, byte *data, uint len, ea_list **to)
 435 {
 436   if (!len || (len % 4))
 437     WITHDRAW(BAD_LENGTH, "COMMUNITY", len);
 438
 439   struct adata *ad = lp_alloc_adata(s->pool, len);
 440   get_u32s(data, (u32 *) ad->data, len / 4);
 441   bgp_set_attr_ptr(to, s->pool, BA_COMMUNITY, flags, ad);
 442 }
 443
 444
 445 static void
 446 bgp_export_originator_id(struct bgp_export_state *s, eattr *a)
 447 {
 448   if (!s->proto->is_internal)
 449     UNSET(a);
 450 }
 451
 452 static void
 453 bgp_decode_originator_id(struct bgp_parse_state *s, uint code UNUSED, uint flags, byte *data, uint len, ea_list **to)
 454 {
 455   if (!s->proto->is_internal)
 456     DISCARD(BAD_EBGP, "ORIGINATOR_ID");
 457
 458   if (len != 4)
 459     WITHDRAW(BAD_LENGTH, "ORIGINATOR_ID", len);
 460
 461   u32 val = get_u32(data);
 462   bgp_set_attr_u32(to, s->pool, BA_ORIGINATOR_ID, flags, val);
 463 }
 464
 465
 466 static void
 467 bgp_export_cluster_list(struct bgp_export_state *s UNUSED, eattr *a)
 468 {
 469   if (!s->proto->is_internal)
 470     UNSET(a);
 471
 472   if (a->u.ptr->length == 0)
 473     UNSET(a);
 474 }
 475
 476 static void
 477 bgp_decode_cluster_list(struct bgp_parse_state *s, uint code UNUSED, uint flags, byte *data, uint len, ea_list **to)
 478 {
 479   if (!s->proto->is_internal)
 480     DISCARD(BAD_EBGP, "CLUSTER_LIST");
 481
 482   if (!len || (len % 4))
 483     WITHDRAW(BAD_LENGTH, "CLUSTER_LIST", len);
 484
 485   struct adata *ad = lp_alloc_adata(s->pool, len);
 486   get_u32s(data, (u32 *) ad->data, len / 4);
 487   bgp_set_attr_ptr(to, s->pool, BA_CLUSTER_LIST, flags, ad);
 488 }
 489
 490 static void
 491 bgp_format_cluster_list(eattr *a, byte *buf, uint size)
 492 {
 493   /* Truncates cluster lists larger than buflen, probably not a problem */
 494   int_set_format(a->u.ptr, 0, -1, buf, size);
 495 }
 496
 497
 498 static inline u32
 499 get_af3(byte *buf)
 500 {
 501   return (get_u16(buf) << 16) | buf[2];
 502 }
 503
 504 static void
 505 bgp_decode_mp_reach_nlri(struct bgp_parse_state *s, uint code UNUSED, uint flags UNUSED, byte *data, uint len, ea_list **to UNUSED)
 506 {
 507   /*
 508    *    2 B     MP_REACH_NLRI data - Address Family Identifier
 509    *    1 B     MP_REACH_NLRI data - Subsequent Address Family Identifier
 510    *    1 B     MP_REACH_NLRI data - Length of Next Hop Network Address
 511    *    var     MP_REACH_NLRI data - Network Address of Next Hop
 512    *    1 B     MP_REACH_NLRI data - Reserved (zero)
 513    *    var     MP_REACH_NLRI data - Network Layer Reachability Information
 514    */
 515
 516   if ((len < 5) || (len < (5 + (uint) data[3])))
 517     bgp_parse_error(s, 9);
 518
 519   s->mp_reach_af = get_af3(data);
 520   s->mp_next_hop_len = data[3];
 521   s->mp_next_hop_data = data + 4;
 522   s->mp_reach_len = len - 5 - s->mp_next_hop_len;
 523   s->mp_reach_nlri = data + 5 + s->mp_next_hop_len;
 524 }
 525
 526
 527 static void
 528 bgp_decode_mp_unreach_nlri(struct bgp_parse_state *s, uint code UNUSED, uint flags UNUSED, byte *data, uint len, ea_list **to UNUSED)
 529 {
 530   /*
 531    *    2 B     MP_UNREACH_NLRI data - Address Family Identifier
 532    *    1 B     MP_UNREACH_NLRI data - Subsequent Address Family Identifier
 533    *    var     MP_UNREACH_NLRI data - Network Layer Reachability Information
 534    */
 535
 536   if (len < 3)
 537     bgp_parse_error(s, 9);
 538
 539   s->mp_unreach_af = get_af3(data);
 540   s->mp_unreach_len = len - 3;
 541   s->mp_unreach_nlri = data + 3;
 542 }
 543
 544
 545 static void
 546 bgp_export_ext_community(struct bgp_export_state *s, eattr *a)
 547 {
 548   a->u.ptr = ec_set_del_nontrans(s->pool, a->u.ptr);
 549
 550   if (a->u.ptr->length == 0)
 551     UNSET(a);
 552
 553   ec_set_sort_x(a->u.ptr);
 554 }
 555
 556 static void
 557 bgp_decode_ext_community(struct bgp_parse_state *s, uint code UNUSED, uint flags, byte *data, uint len, ea_list **to)
 558 {
 559   if (!len || (len % 8))
 560     WITHDRAW(BAD_LENGTH, "EXT_COMMUNITY", len);
 561
 562   struct adata *ad = lp_alloc_adata(s->pool, len);
 563   get_u32s(data, (u32 *) ad->data, len / 4);
 564   bgp_set_attr_ptr(to, s->pool, BA_EXT_COMMUNITY, flags, ad);
 565 }
 566
 567
 568 static void
 569 bgp_decode_as4_aggregator(struct bgp_parse_state *s, uint code UNUSED, uint flags, byte *data, uint len, ea_list **to)
 570 {
 571   if (s->as4_session)
 572     DISCARD(NEW_BGP, "AS4_AGGREGATOR");
 573
 574   if (len != 8)
 575     DISCARD(BAD_LENGTH, "AS4_AGGREGATOR", len);
 576
 577   bgp_set_attr_data(to, s->pool, BA_AS4_AGGREGATOR, flags, data, len);
 578 }
 579
 580 static void
 581 bgp_decode_as4_path(struct bgp_parse_state *s, uint code UNUSED, uint flags, byte *data, uint len, ea_list **to)
 582 {
 583   char err[128];
 584
 585   if (s->as4_session)
 586     DISCARD(NEW_BGP, "AS4_PATH");
 587
 588   if (len < 6)
 589     DISCARD(BAD_LENGTH, "AS4_PATH", len);
 590
 591   if (!as_path_valid(data, len, 4, 1, err, sizeof(err)))
 592     DISCARD("Malformed AS4_PATH attribute - %s", err);
 593
 594   struct adata *a = lp_alloc_adata(s->pool, len);
 595   memcpy(a->data, data, len);
 596
 597   /* AS_CONFED* segments are invalid in AS4_PATH; RFC 6793 6 */
 598   if (as_path_contains_confed(a))
 599   {
 600     REPORT("Discarding AS_CONFED* segment from AS4_PATH attribute");
 601     a = as_path_strip_confed(s->pool, a);
 602   }
 603
 604   bgp_set_attr_ptr(to, s->pool, BA_AS4_PATH, flags, a);
 605 }
 606
 607 static void
 608 bgp_export_large_community(struct bgp_export_state *s, eattr *a)
 609 {
 610   if (a->u.ptr->length == 0)
 611     UNSET(a);
 612
 613   a->u.ptr = lc_set_sort(s->pool, a->u.ptr);
 614 }
 615
 616 static void
 617 bgp_decode_large_community(struct bgp_parse_state *s, uint code UNUSED, uint flags, byte *data, uint len, ea_list **to)
 618 {
 619   if (!len || (len % 12))
 620     WITHDRAW(BAD_LENGTH, "LARGE_COMMUNITY", len);
 621
 622   struct adata *ad = lp_alloc_adata(s->pool, len);
 623   get_u32s(data, (u32 *) ad->data, len / 4);
 624   bgp_set_attr_ptr(to, s->pool, BA_LARGE_COMMUNITY, flags, ad);
 625 }
 626
 627 static void
 628 bgp_export_mpls_label_stack(struct bgp_export_state *s, eattr *a)
 629 {
 630   net_addr *n = s->route->net->n.addr;
 631   u32 *labels = (u32 *) a->u.ptr->data;
 632   uint lnum = a->u.ptr->length / 4;
 633
 634   /* Perhaps we should just ignore it? */
 635   if (!s->mpls)
 636     WITHDRAW("Unexpected MPLS stack");
 637
 638   /* Empty MPLS stack is not allowed */
 639   if (!lnum)
 640     WITHDRAW("Malformed MPLS stack - empty");
 641
 642   /* This is ugly, but we must ensure that labels fit into NLRI field */
 643   if ((24*lnum + (net_is_vpn(n) ? 64 : 0) + net_pxlen(n)) > 255)
 644     WITHDRAW("Malformed MPLS stack - too many labels (%u)", lnum);
 645
 646   for (uint i = 0; i < lnum; i++)
 647   {
 648     if (labels[i] > 0xfffff)
 649       WITHDRAW("Malformed MPLS stack - invalid label (%u)", labels[i]);
 650
 651     /* TODO: Check for special-purpose label values? */
 652   }
 653 }
 654
 655 static int
 656 bgp_encode_mpls_label_stack(struct bgp_write_state *s, eattr *a, byte *buf UNUSED, uint size UNUSED)
 657 {
 658   /*
 659    * MPLS labels are encoded as a part of the NLRI in MP_REACH_NLRI attribute,
 660    * so we store MPLS_LABEL_STACK and encode it later by AFI-specific hooks.
 661    */
 662
 663   s->mpls_labels = a->u.ptr;
 664   return 0;
 665 }
 666
 667 static void
 668 bgp_decode_mpls_label_stack(struct bgp_parse_state *s, uint code UNUSED, uint flags UNUSED, byte *data UNUSED, uint len UNUSED, ea_list **to UNUSED)
 669 {
 670   DISCARD("Discarding received attribute #0");
 671 }
 672
 673 static void
 674 bgp_format_mpls_label_stack(eattr *a, byte *buf, uint size)
 675 {
 676   u32 *labels = (u32 *) a->u.ptr->data;
 677   uint lnum = a->u.ptr->length / 4;
 678   char *pos = buf;
 679
 680   for (uint i = 0; i < lnum; i++)
 681   {
 682     if (size < 20)
 683     {
 684       bsprintf(pos, "...");
 685       return;
 686     }
 687
 688     uint l = bsprintf(pos, "%d/", labels[i]);
 689     ADVANCE(pos, size, l);
 690   }
 691
 692   /* Clear last slash or terminate empty string */
 693   pos[lnum ? -1 : 0] = 0;
 694 }
 695
 696 static inline void
 697 bgp_decode_unknown(struct bgp_parse_state *s, uint code, uint flags, byte *data, uint len, ea_list **to)
 698 {
 699   /* Cannot use bgp_set_attr_data() as it works on known attributes only */
 700   ea_set_attr_data(to, s->pool, EA_CODE(PROTOCOL_BGP, code), flags, EAF_TYPE_OPAQUE, data, len);
 701 }
 702
 703
 704 /*
 705  *      Attribute table
 706  */
 707
 708 static const struct bgp_attr_desc bgp_attr_table[] = {
 709   [BA_ORIGIN] = {
 710     .name = "origin",
 711     .type = EAF_TYPE_INT,
 712     .flags = BAF_TRANSITIVE,
 713     .export = bgp_export_origin,
 714     .encode = bgp_encode_u8,
 715     .decode = bgp_decode_origin,
 716     .format = bgp_format_origin,
 717   },
 718   [BA_AS_PATH] = {
 719     .name = "as_path",
 720     .type = EAF_TYPE_AS_PATH,
 721     .flags = BAF_TRANSITIVE,
 722     .encode = bgp_encode_as_path,
 723     .decode = bgp_decode_as_path,
 724   },
 725   [BA_NEXT_HOP] = {
 726     .name = "next_hop",
 727     .type = EAF_TYPE_IP_ADDRESS,
 728     .flags = BAF_TRANSITIVE,
 729     .encode = bgp_encode_next_hop,
 730     .decode = bgp_decode_next_hop,
 731     .format = bgp_format_next_hop,
 732   },
 733   [BA_MULTI_EXIT_DISC] = {
 734     .name = "med",
 735     .type = EAF_TYPE_INT,
 736     .flags = BAF_OPTIONAL,
 737     .encode = bgp_encode_u32,
 738     .decode = bgp_decode_med,
 739   },
 740   [BA_LOCAL_PREF] = {
 741     .name = "local_pref",
 742     .type = EAF_TYPE_INT,
 743     .flags = BAF_TRANSITIVE,
 744     .export = bgp_export_local_pref,
 745     .encode = bgp_encode_u32,
 746     .decode = bgp_decode_local_pref,
 747   },
 748   [BA_ATOMIC_AGGR] = {
 749     .name = "atomic_aggr",
 750     .type = EAF_TYPE_OPAQUE,
 751     .flags = BAF_TRANSITIVE,
 752     .encode = bgp_encode_raw,
 753     .decode = bgp_decode_atomic_aggr,
 754   },
 755   [BA_AGGREGATOR] = {
 756     .name = "aggregator",
 757     .type = EAF_TYPE_OPAQUE,
 758     .flags = BAF_OPTIONAL | BAF_TRANSITIVE,
 759     .encode = bgp_encode_aggregator,
 760     .decode = bgp_decode_aggregator,
 761     .format = bgp_format_aggregator,
 762   },
 763   [BA_COMMUNITY] = {
 764     .name = "community",
 765     .type = EAF_TYPE_INT_SET,
 766     .flags = BAF_OPTIONAL | BAF_TRANSITIVE,
 767     .export = bgp_export_community,
 768     .encode = bgp_encode_u32s,
 769     .decode = bgp_decode_community,
 770   },
 771   [BA_ORIGINATOR_ID] = {
 772     .name = "originator_id",
 773     .type = EAF_TYPE_ROUTER_ID,
 774     .flags = BAF_OPTIONAL,
 775     .export = bgp_export_originator_id,
 776     .encode = bgp_encode_u32,
 777     .decode = bgp_decode_originator_id,
 778   },
 779   [BA_CLUSTER_LIST] = {
 780     .name = "cluster_list",
 781     .type = EAF_TYPE_INT_SET,
 782     .flags = BAF_OPTIONAL,
 783     .export = bgp_export_cluster_list,
 784     .encode = bgp_encode_u32s,
 785     .decode = bgp_decode_cluster_list,
 786     .format = bgp_format_cluster_list,
 787   },
 788   [BA_MP_REACH_NLRI] = {
 789     .name = "mp_reach_nlri",
 790     .type = EAF_TYPE_OPAQUE,
 791     .flags = BAF_OPTIONAL,
 792     .decode = bgp_decode_mp_reach_nlri,
 793   },
 794   [BA_MP_UNREACH_NLRI] = {
 795     .name = "mp_unreach_nlri",
 796     .type = EAF_TYPE_OPAQUE,
 797     .flags = BAF_OPTIONAL,
 798     .decode = bgp_decode_mp_unreach_nlri,
 799   },
 800   [BA_EXT_COMMUNITY] = {
 801     .name = "ext_community",
 802     .type = EAF_TYPE_EC_SET,
 803     .flags = BAF_OPTIONAL | BAF_TRANSITIVE,
 804     .export = bgp_export_ext_community,
 805     .encode = bgp_encode_u32s,
 806     .decode = bgp_decode_ext_community,
 807   },
 808   [BA_AS4_PATH] = {
 809     .name = "as4_path",
 810     .type = EAF_TYPE_AS_PATH,
 811     .flags = BAF_OPTIONAL | BAF_TRANSITIVE,
 812     .encode = bgp_encode_raw,
 813     .decode = bgp_decode_as4_path,
 814   },
 815   [BA_AS4_AGGREGATOR] = {
 816     .name = "as4_aggregator",
 817     .type = EAF_TYPE_OPAQUE,
 818     .flags = BAF_OPTIONAL | BAF_TRANSITIVE,
 819     .encode = bgp_encode_raw,
 820     .decode = bgp_decode_as4_aggregator,
 821     .format = bgp_format_aggregator,
 822   },
 823   [BA_LARGE_COMMUNITY] = {
 824     .name = "large_community",
 825     .type = EAF_TYPE_LC_SET,
 826     .flags = BAF_OPTIONAL | BAF_TRANSITIVE,
 827     .export = bgp_export_large_community,
 828     .encode = bgp_encode_u32s,
 829     .decode = bgp_decode_large_community,
 830   },
 831   [BA_MPLS_LABEL_STACK] = {
 832     .name = "mpls_label_stack",
 833     .type = EAF_TYPE_INT_SET,
 834     .export = bgp_export_mpls_label_stack,
 835     .encode = bgp_encode_mpls_label_stack,
 836     .decode = bgp_decode_mpls_label_stack,
 837     .format = bgp_format_mpls_label_stack,
 838   },
 839 };
 840
 841 static inline int
 842 bgp_attr_known(uint code)
 843 {
 844   return (code < ARRAY_SIZE(bgp_attr_table)) && bgp_attr_table[code].name;
 845 }
 846
 847
 848 /*
 849  *      Attribute export
 850  */
 851
 852 static inline void
 853 bgp_export_attr(struct bgp_export_state *s, eattr *a, ea_list *to)
 854 {
 855   if (EA_PROTO(a->id) != PROTOCOL_BGP)
 856     return;
 857
 858   uint code = EA_ID(a->id);
 859
 860   if (bgp_attr_known(code))
 861   {
 862     const struct bgp_attr_desc *desc = &bgp_attr_table[code];
 863
 864     /* The flags might have been zero if the attr was added by filters */
 865     a->flags = (a->flags & BAF_PARTIAL) | desc->flags;
 866
 867     /* Set partial bit if new opt-trans attribute is attached to non-local route */
 868     if ((s->src != NULL) && (a->type & EAF_ORIGINATED) &&
 869         (a->flags & BAF_OPTIONAL) && (a->flags & BAF_TRANSITIVE))
 870       a->flags |= BAF_PARTIAL;
 871
 872     /* Call specific hook */
 873     CALL(desc->export, s, a);
 874
 875     /* Attribute might become undefined in hook */
 876     if ((a->type & EAF_TYPE_MASK) == EAF_TYPE_UNDEF)
 877       return;
 878   }
 879   else
 880   {
 881     /* Don't re-export unknown non-transitive attributes */
 882     if (!(a->flags & BAF_TRANSITIVE))
 883       return;
 884
 885     a->flags |= BAF_PARTIAL;
 886   }
 887
 888   /* Append updated attribute */
 889   to->attrs[to->count++] = *a;
 890 }
 891
 892 /**
 893  * bgp_export_attrs - export BGP attributes
 894  * @s: BGP export state
 895  * @attrs: a list of extended attributes
 896  *
 897  * The bgp_export_attrs() function takes a list of attributes and merges it to
 898  * one newly allocated and sorted segment. Attributes are validated and
 899  * normalized by type-specific export hooks and attribute flags are updated.
 900  * Some attributes may be eliminated (e.g. unknown non-tranitive attributes, or
 901  * empty community sets).
 902  *
 903  * Result: one sorted attribute list segment, or NULL if attributes are unsuitable.
 904  */
 905 static inline ea_list *
 906 bgp_export_attrs(struct bgp_export_state *s, ea_list *attrs)
 907 {
 908   /* Merge the attribute list */
 909   ea_list *new = lp_alloc(s->pool, ea_scan(attrs));
 910   ea_merge(attrs, new);
 911   ea_sort(new);
 912
 913   uint i, count;
 914   count = new->count;
 915   new->count = 0;
 916
 917   /* Export each attribute */
 918   for (i = 0; i < count; i++)
 919     bgp_export_attr(s, &new->attrs[i], new);
 920
 921   if (s->err_withdraw)
 922     return NULL;
 923
 924   return new;
 925 }
 926
 927
 928 /*
 929  *      Attribute encoding
 930  */
 931
 932 static inline int
 933 bgp_encode_attr(struct bgp_write_state *s, eattr *a, byte *buf, uint size)
 934 {
 935   ASSERT(EA_PROTO(a->id) == PROTOCOL_BGP);
 936
 937   uint code = EA_ID(a->id);
 938
 939   if (bgp_attr_known(code))
 940     return bgp_attr_table[code].encode(s, a, buf, size);
 941   else
 942     return bgp_encode_raw(s, a, buf, size);
 943 }
 944
 945 /**
 946  * bgp_encode_attrs - encode BGP attributes
 947  * @s: BGP write state
 948  * @attrs: a list of extended attributes
 949  * @buf: buffer
 950  * @end: buffer end
 951  *
 952  * The bgp_encode_attrs() function takes a list of extended attributes
 953  * and converts it to its BGP representation (a part of an Update message).
 954  * BGP write state may be fake when called from MRT protocol.
 955  *
 956  * Result: Length of the attribute block generated or -1 if not enough space.
 957  */
 958 int
 959 bgp_encode_attrs(struct bgp_write_state *s, ea_list *attrs, byte *buf, byte *end)
 960 {
 961   byte *pos = buf;
 962   int i, len;
 963
 964   for (i = 0; i < attrs->count; i++)
 965   {
 966     len = bgp_encode_attr(s, &attrs->attrs[i], pos, end - pos);
 967
 968     if (len < 0)
 969       return -1;
 970
 971     pos += len;
 972   }
 973
 974   return pos - buf;
 975 }
 976
 977
 978 /*
 979  *      Attribute decoding
 980  */
 981
 982 static void bgp_process_as4_attrs(ea_list **attrs, struct linpool *pool);
 983
 984 static inline int
 985 bgp_as_path_loopy(struct bgp_proto *p, ea_list *attrs, u32 asn)
 986 {
 987   eattr *e = bgp_find_attr(attrs, BA_AS_PATH);
 988   int num = p->cf->allow_local_as + 1;
 989   return (e && (num > 0) && as_path_contains(e->u.ptr, asn, num));
 990 }
 991
 992 static inline int
 993 bgp_originator_id_loopy(struct bgp_proto *p, ea_list *attrs)
 994 {
 995   eattr *e = bgp_find_attr(attrs, BA_ORIGINATOR_ID);
 996   return (e && (e->u.data == p->local_id));
 997 }
 998
 999 static inline int
1000 bgp_cluster_list_loopy(struct bgp_proto *p, ea_list *attrs)
1001 {
1002   eattr *e = bgp_find_attr(attrs, BA_CLUSTER_LIST);
1003   return (e && int_set_contains(e->u.ptr, p->rr_cluster_id));
1004 }
1005
1006 static inline void
1007 bgp_decode_attr(struct bgp_parse_state *s, uint code, uint flags, byte *data, uint len, ea_list **to)
1008 {
1009   /* Handle duplicate attributes; RFC 7606 3 (g) */
1010   if (BIT32_TEST(s->attrs_seen, code))
1011   {
1012     if ((code == BA_MP_REACH_NLRI) || (code == BA_MP_UNREACH_NLRI))
1013       bgp_parse_error(s, 1);
1014     else
1015       DISCARD("Discarding duplicate attribute (code %u)", code);
1016   }
1017   BIT32_SET(s->attrs_seen, code);
1018
1019   if (bgp_attr_known(code))
1020   {
1021     const struct bgp_attr_desc *desc = &bgp_attr_table[code];
1022
1023     /* Handle conflicting flags; RFC 7606 3 (c) */
1024     if ((flags ^ desc->flags) & (BAF_OPTIONAL | BAF_TRANSITIVE))
1025       WITHDRAW("Malformed %s attribute - conflicting flags (%02x)", desc->name, flags);
1026
1027     desc->decode(s, code, flags, data, len, to);
1028   }
1029   else /* Unknown attribute */
1030   {
1031     if (!(flags & BAF_OPTIONAL))
1032       WITHDRAW("Unknown attribute (code %u) - conflicting flags (%02x)", code, flags);
1033
1034     bgp_decode_unknown(s, code, flags, data, len, to);
1035   }
1036 }
1037
1038 /**
1039  * bgp_decode_attrs - check and decode BGP attributes
1040  * @s: BGP parse state
1041  * @data: start of attribute block
1042  * @len: length of attribute block
1043  *
1044  * This function takes a BGP attribute block (a part of an Update message), checks
1045  * its consistency and converts it to a list of BIRD route attributes represented
1046  * by an (uncached) &rta.
1047  */
1048 ea_list *
1049 bgp_decode_attrs(struct bgp_parse_state *s, byte *data, uint len)
1050 {
1051   struct bgp_proto *p = s->proto;
1052   ea_list *attrs = NULL;
1053   uint code, flags, alen;
1054   byte *pos = data;
1055
1056   /* Parse the attributes */
1057   while (len)
1058   {
1059     alen = 0;
1060
1061     /* Read attribute type */
1062     if (len < 2)
1063       goto framing_error;
1064     flags = pos[0];
1065     code = pos[1];
1066     ADVANCE(pos, len, 2);
1067
1068     /* Read attribute length */
1069     if (flags & BAF_EXT_LEN)
1070     {
1071       if (len < 2)
1072         goto framing_error;
1073       alen = get_u16(pos);
1074       ADVANCE(pos, len, 2);
1075     }
1076     else
1077     {
1078       if (len < 1)
1079         goto framing_error;
1080       alen = *pos;
1081       ADVANCE(pos, len, 1);
1082     }
1083
1084     if (alen > len)
1085       goto framing_error;
1086
1087     DBG("Attr %02x %02x %u\n", code, flags, alen);
1088
1089     bgp_decode_attr(s, code, flags, pos, alen, &attrs);
1090     ADVANCE(pos, len, alen);
1091   }
1092
1093   if (s->err_withdraw)
1094     goto withdraw;
1095
1096   /* If there is no reachability NLRI, we are finished */
1097   if (!s->ip_reach_len && !s->mp_reach_len)
1098     return NULL;
1099
1100
1101   /* Handle missing mandatory attributes; RFC 7606 3 (d) */
1102   if (!BIT32_TEST(s->attrs_seen, BA_ORIGIN))
1103   { REPORT(NO_MANDATORY, "ORIGIN"); goto withdraw; }
1104
1105   if (!BIT32_TEST(s->attrs_seen, BA_AS_PATH))
1106   { REPORT(NO_MANDATORY, "AS_PATH"); goto withdraw; }
1107
1108   if (s->ip_reach_len && !BIT32_TEST(s->attrs_seen, BA_NEXT_HOP))
1109   { REPORT(NO_MANDATORY, "NEXT_HOP"); goto withdraw; }
1110
1111   /* When receiving attributes from non-AS4-aware BGP speaker, we have to
1112      reconstruct AS_PATH and AGGREGATOR attributes; RFC 6793 4.2.3 */
1113   if (!p->as4_session)
1114     bgp_process_as4_attrs(&attrs, s->pool);
1115
1116   /* Reject routes with our ASN in AS_PATH attribute */
1117   if (bgp_as_path_loopy(p, attrs, p->local_as))
1118     goto withdraw;
1119
1120   /* Reject routes with our Confederation ID in AS_PATH attribute; RFC 5065 4.0 */
1121   if ((p->public_as != p->local_as) && bgp_as_path_loopy(p, attrs, p->public_as))
1122     goto withdraw;
1123
1124   /* Reject routes with our Router ID in ORIGINATOR_ID attribute; RFC 4456 8 */
1125   if (p->is_internal && bgp_originator_id_loopy(p, attrs))
1126     goto withdraw;
1127
1128   /* Reject routes with our Cluster ID in CLUSTER_LIST attribute; RFC 4456 8 */
1129   if (p->rr_client && bgp_cluster_list_loopy(p, attrs))
1130     goto withdraw;
1131
1132   /* If there is no local preference, define one */
1133   if (!BIT32_TEST(s->attrs_seen, BA_LOCAL_PREF))
1134     bgp_set_attr_u32(&attrs, s->pool, BA_LOCAL_PREF, 0, p->cf->default_local_pref);
1135
1136   return attrs;
1137
1138
1139 framing_error:
1140   /* RFC 7606 4 - handle attribute framing errors */
1141   REPORT("Malformed attribute list - framing error (%u/%u) at %d",
1142          alen, len, (int) (pos - s->attrs));
1143
1144 withdraw:
1145   /* RFC 7606 5.2 - handle missing NLRI during errors */
1146   if (!s->ip_reach_len && !s->mp_reach_len)
1147     bgp_parse_error(s, 1);
1148
1149   s->err_withdraw = 1;
1150   return NULL;
1151 }
1152
1153
1154 /*
1155  *      Route bucket hash table
1156  */
1157
1158 #define RBH_KEY(b)              b->eattrs, b->hash
1159 #define RBH_NEXT(b)             b->next
1160 #define RBH_EQ(a1,h1,a2,h2)     h1 == h2 && ea_same(a1, a2)
1161 #define RBH_FN(a,h)             h
1162
1163 #define RBH_REHASH              bgp_rbh_rehash
1164 #define RBH_PARAMS              /8, *2, 2, 2, 8, 20
1165
1166
1167 HASH_DEFINE_REHASH_FN(RBH, struct bgp_bucket)
1168
1169 void
1170 bgp_init_bucket_table(struct bgp_channel *c)
1171 {
1172   HASH_INIT(c->bucket_hash, c->pool, 8);
1173
1174   init_list(&c->bucket_queue);
1175   c->withdraw_bucket = NULL;
1176 }
1177
1178 void
1179 bgp_free_bucket_table(struct bgp_channel *c)
1180 {
1181   HASH_FREE(c->bucket_hash);
1182
1183   struct bgp_bucket *b;
1184   WALK_LIST_FIRST(b, c->bucket_queue)
1185   {
1186     rem_node(&b->send_node);
1187     mb_free(b);
1188   }
1189
1190   mb_free(c->withdraw_bucket);
1191   c->withdraw_bucket = NULL;
1192 }
1193
1194 static struct bgp_bucket *
1195 bgp_get_bucket(struct bgp_channel *c, ea_list *new)
1196 {
1197   /* Hash and lookup */
1198   u32 hash = ea_hash(new);
1199   struct bgp_bucket *b = HASH_FIND(c->bucket_hash, RBH, new, hash);
1200
1201   if (b)
1202     return b;
1203
1204   uint ea_size = sizeof(ea_list) + new->count * sizeof(eattr);
1205   uint ea_size_aligned = BIRD_ALIGN(ea_size, CPU_STRUCT_ALIGN);
1206   uint size = sizeof(struct bgp_bucket) + ea_size_aligned;
1207   uint i;
1208   byte *dest;
1209
1210   /* Gather total size of non-inline attributes */
1211   for (i = 0; i < new->count; i++)
1212   {
1213     eattr *a = &new->attrs[i];
1214
1215     if (!(a->type & EAF_EMBEDDED))
1216       size += BIRD_ALIGN(sizeof(struct adata) + a->u.ptr->length, CPU_STRUCT_ALIGN);
1217   }
1218
1219   /* Create the bucket */
1220   b = mb_alloc(c->pool, size);
1221   init_list(&b->prefixes);
1222   b->hash = hash;
1223
1224   /* Copy list of extended attributes */
1225   memcpy(b->eattrs, new, ea_size);
1226   dest = ((byte *) b->eattrs) + ea_size_aligned;
1227
1228   /* Copy values of non-inline attributes */
1229   for (i = 0; i < new->count; i++)
1230   {
1231     eattr *a = &b->eattrs->attrs[i];
1232
1233     if (!(a->type & EAF_EMBEDDED))
1234     {
1235       struct adata *oa = a->u.ptr;
1236       struct adata *na = (struct adata *) dest;
1237       memcpy(na, oa, sizeof(struct adata) + oa->length);
1238       a->u.ptr = na;
1239       dest += BIRD_ALIGN(sizeof(struct adata) + na->length, CPU_STRUCT_ALIGN);
1240     }
1241   }
1242
1243   /* Insert the bucket to send queue and bucket hash */
1244   add_tail(&c->bucket_queue, &b->send_node);
1245   HASH_INSERT2(c->bucket_hash, RBH, c->pool, b);
1246
1247   return b;
1248 }
1249
1250 static struct bgp_bucket *
1251 bgp_get_withdraw_bucket(struct bgp_channel *c)
1252 {
1253   if (!c->withdraw_bucket)
1254   {
1255     c->withdraw_bucket = mb_allocz(c->pool, sizeof(struct bgp_bucket));
1256     init_list(&c->withdraw_bucket->prefixes);
1257   }
1258
1259   return c->withdraw_bucket;
1260 }
1261
1262 void
1263 bgp_free_bucket(struct bgp_channel *c, struct bgp_bucket *b)
1264 {
1265   rem_node(&b->send_node);
1266   HASH_REMOVE2(c->bucket_hash, RBH, c->pool, b);
1267   mb_free(b);
1268 }
1269
1270 void
1271 bgp_defer_bucket(struct bgp_channel *c, struct bgp_bucket *b)
1272 {
1273   rem_node(&b->send_node);
1274   add_tail(&c->bucket_queue, &b->send_node);
1275 }
1276
1277 void
1278 bgp_withdraw_bucket(struct bgp_channel *c, struct bgp_bucket *b)
1279 {
1280   struct bgp_proto *p = (void *) c->c.proto;
1281   struct bgp_bucket *wb = bgp_get_withdraw_bucket(c);
1282
1283   log(L_ERR "%s: Attribute list too long", p->p.name);
1284   while (!EMPTY_LIST(b->prefixes))
1285   {
1286     struct bgp_prefix *px = HEAD(b->prefixes);
1287
1288     log(L_ERR "%s: - withdrawing %N", p->p.name, &px->net);
1289     rem_node(&px->buck_node);
1290     add_tail(&wb->prefixes, &px->buck_node);
1291   }
1292 }
1293
1294
1295 /*
1296  *      Prefix hash table
1297  */
1298
1299 #define PXH_KEY(px)             px->net, px->path_id, px->hash
1300 #define PXH_NEXT(px)            px->next
1301 #define PXH_EQ(n1,i1,h1,n2,i2,h2) h1 == h2 && i1 == i2 && net_equal(n1, n2)
1302 #define PXH_FN(n,i,h)           h
1303
1304 #define PXH_REHASH              bgp_pxh_rehash
1305 #define PXH_PARAMS              /8, *2, 2, 2, 8, 24
1306
1307
1308 HASH_DEFINE_REHASH_FN(PXH, struct bgp_prefix)
1309
1310 void
1311 bgp_init_prefix_table(struct bgp_channel *c)
1312 {
1313   HASH_INIT(c->prefix_hash, c->pool, 8);
1314
1315   uint alen = net_addr_length[c->c.net_type];
1316   c->prefix_slab = alen ? sl_new(c->pool, sizeof(struct bgp_prefix) + alen) : NULL;
1317 }
1318
1319 void
1320 bgp_free_prefix_table(struct bgp_channel *c)
1321 {
1322   HASH_FREE(c->prefix_hash);
1323
1324   rfree(c->prefix_slab);
1325   c->prefix_slab = NULL;
1326 }
1327
1328 static struct bgp_prefix *
1329 bgp_get_prefix(struct bgp_channel *c, net_addr *net, u32 path_id)
1330 {
1331   u32 hash = net_hash(net) ^ u32_hash(path_id);
1332   struct bgp_prefix *px = HASH_FIND(c->prefix_hash, PXH, net, path_id, hash);
1333
1334   if (px)
1335   {
1336     rem_node(&px->buck_node);
1337     return px;
1338   }
1339
1340   if (c->prefix_slab)
1341     px = sl_alloc(c->prefix_slab);
1342   else
1343     px = mb_alloc(c->pool, sizeof(struct bgp_prefix) + net->length);
1344
1345   px->buck_node.next = NULL;
1346   px->buck_node.prev = NULL;
1347   px->hash = hash;
1348   px->path_id = path_id;
1349   net_copy(px->net, net);
1350
1351   HASH_INSERT2(c->prefix_hash, PXH, c->pool, px);
1352
1353   return px;
1354 }
1355
1356 void
1357 bgp_free_prefix(struct bgp_channel *c, struct bgp_prefix *px)
1358 {
1359   rem_node(&px->buck_node);
1360   HASH_REMOVE2(c->prefix_hash, PXH, c->pool, px);
1361
1362   if (c->prefix_slab)
1363     sl_free(c->prefix_slab, px);
1364   else
1365     mb_free(px);
1366 }
1367
1368
1369 /*
1370  *      BGP protocol glue
1371  */
1372
1373 int
1374 bgp_preexport(struct proto *P, rte **new, struct linpool *pool UNUSED)
1375 {
1376   rte *e = *new;
1377   struct proto *SRC = e->attrs->src->proto;
1378   struct bgp_proto *p = (struct bgp_proto *) P;
1379   struct bgp_proto *src = (SRC->proto == &proto_bgp) ? (struct bgp_proto *) SRC : NULL;
1380
1381   /* Reject our routes */
1382   if (src == p)
1383     return -1;
1384
1385   /* Accept non-BGP routes */
1386   if (src == NULL)
1387     return 0;
1388
1389   /* IBGP route reflection, RFC 4456 */
1390   if (p->is_internal && src->is_internal && (p->local_as == src->local_as))
1391   {
1392     /* Rejected unless configured as route reflector */
1393     if (!p->rr_client && !src->rr_client)
1394       return -1;
1395
1396     /* Generally, this should be handled when path is received, but we check it
1397        also here as rr_cluster_id may be undefined or different in src. */
1398     if (p->rr_cluster_id && bgp_cluster_list_loopy(p, e->attrs->eattrs))
1399       return -1;
1400   }
1401
1402   /* Handle well-known communities, RFC 1997 */
1403   struct eattr *c;
1404   if (p->cf->interpret_communities &&
1405       (c = ea_find(e->attrs->eattrs, EA_CODE(PROTOCOL_BGP, BA_COMMUNITY))))
1406   {
1407     struct adata *d = c->u.ptr;
1408
1409     /* Do not export anywhere */
1410     if (int_set_contains(d, BGP_COMM_NO_ADVERTISE))
1411       return -1;
1412
1413     /* Do not export outside of AS (or member-AS) */
1414     if (!p->is_internal && int_set_contains(d, BGP_COMM_NO_EXPORT_SUBCONFED))
1415       return -1;
1416
1417     /* Do not export outside of AS (or confederation) */
1418     if (!p->is_interior && int_set_contains(d, BGP_COMM_NO_EXPORT))
1419       return -1;
1420
1421     /* Do not export LLGR_STALE routes to LLGR-ignorant peers */
1422     if (!p->conn->remote_caps->llgr_aware && int_set_contains(d, BGP_COMM_LLGR_STALE))
1423       return -1;
1424   }
1425
1426   return 0;
1427 }
1428
1429
1430 static adata null_adata;        /* adata of length 0 */
1431
1432 static ea_list *
1433 bgp_update_attrs(struct bgp_proto *p, struct bgp_channel *c, rte *e, ea_list *attrs0, struct linpool *pool)
1434 {
1435   struct proto *SRC = e->attrs->src->proto;
1436   struct bgp_proto *src = (SRC->proto == &proto_bgp) ? (void *) SRC : NULL;
1437   struct bgp_export_state s = { .proto = p, .channel = c, .pool = pool, .src = src, .route = e, .mpls = c->desc->mpls };
1438   ea_list *attrs = attrs0;
1439   eattr *a;
1440   adata *ad;
1441
1442   /* ORIGIN attribute - mandatory, attach if missing */
1443   if (! bgp_find_attr(attrs0, BA_ORIGIN))
1444     bgp_set_attr_u32(&attrs, pool, BA_ORIGIN, 0, src ? ORIGIN_INCOMPLETE : ORIGIN_IGP);
1445
1446   /* AS_PATH attribute - mandatory */
1447   a = bgp_find_attr(attrs0, BA_AS_PATH);
1448   ad = a ? a->u.ptr : &null_adata;
1449
1450   /* AS_PATH attribute - strip AS_CONFED* segments outside confederation */
1451   if ((!p->cf->confederation || !p->is_interior) && as_path_contains_confed(ad))
1452     ad = as_path_strip_confed(pool, ad);
1453
1454   /* AS_PATH attribute - keep or prepend ASN */
1455   if (p->is_internal || p->rs_client)
1456   {
1457     /* IBGP or route server -> just ensure there is one */
1458     if (!a)
1459       bgp_set_attr_ptr(&attrs, pool, BA_AS_PATH, 0, &null_adata);
1460   }
1461   else if (p->is_interior)
1462   {
1463     /* Confederation -> prepend ASN as AS_CONFED_SEQUENCE */
1464     ad = as_path_prepend2(pool, ad, AS_PATH_CONFED_SEQUENCE, p->public_as);
1465     bgp_set_attr_ptr(&attrs, pool, BA_AS_PATH, 0, ad);
1466   }
1467   else /* Regular EBGP (no RS, no confederation) */
1468   {
1469     /* Regular EBGP -> prepend ASN as regular sequence */
1470     ad = as_path_prepend2(pool, ad, AS_PATH_SEQUENCE, p->public_as);
1471     bgp_set_attr_ptr(&attrs, pool, BA_AS_PATH, 0, ad);
1472
1473     /* MULTI_EXIT_DESC attribute - accept only if set in export filter */
1474     a = bgp_find_attr(attrs0, BA_MULTI_EXIT_DISC);
1475     if (a && !(a->type & EAF_FRESH))
1476       bgp_unset_attr(&attrs, pool, BA_MULTI_EXIT_DISC);
1477   }
1478
1479   /* NEXT_HOP attribute - delegated to AF-specific hook */
1480   a = bgp_find_attr(attrs0, BA_NEXT_HOP);
1481   bgp_update_next_hop(&s, a, &attrs);
1482
1483   /* LOCAL_PREF attribute - required for IBGP, attach if missing */
1484   if (p->is_interior && ! bgp_find_attr(attrs0, BA_LOCAL_PREF))
1485     bgp_set_attr_u32(&attrs, pool, BA_LOCAL_PREF, 0, p->cf->default_local_pref);
1486
1487   /* IBGP route reflection, RFC 4456 */
1488   if (src && src->is_internal && p->is_internal && (src->local_as == p->local_as))
1489   {
1490     /* ORIGINATOR_ID attribute - attach if not already set */
1491     if (! bgp_find_attr(attrs0, BA_ORIGINATOR_ID))
1492       bgp_set_attr_u32(&attrs, pool, BA_ORIGINATOR_ID, 0, src->remote_id);
1493
1494     /* CLUSTER_LIST attribute - prepend cluster ID */
1495     a = bgp_find_attr(attrs0, BA_CLUSTER_LIST);
1496     ad = a ? a->u.ptr : NULL;
1497
1498     /* Prepend src cluster ID */
1499     if (src->rr_cluster_id)
1500       ad = int_set_prepend(pool, ad, src->rr_cluster_id);
1501
1502     /* Prepend dst cluster ID if src and dst clusters are different */
1503     if (p->rr_cluster_id && (src->rr_cluster_id != p->rr_cluster_id))
1504       ad = int_set_prepend(pool, ad, p->rr_cluster_id);
1505
1506     /* Should be at least one prepended cluster ID */
1507     bgp_set_attr_ptr(&attrs, pool, BA_CLUSTER_LIST, 0, ad);
1508   }
1509
1510   /* AS4_* transition attributes, RFC 6793 4.2.2 */
1511   if (! p->as4_session)
1512   {
1513     a = bgp_find_attr(attrs, BA_AS_PATH);
1514     if (a && as_path_contains_as4(a->u.ptr))
1515     {
1516       bgp_set_attr_ptr(&attrs, pool, BA_AS_PATH, 0, as_path_to_old(pool, a->u.ptr));
1517       bgp_set_attr_ptr(&attrs, pool, BA_AS4_PATH, 0, as_path_strip_confed(pool, a->u.ptr));
1518     }
1519
1520     a = bgp_find_attr(attrs, BA_AGGREGATOR);
1521     if (a && aggregator_contains_as4(a->u.ptr))
1522     {
1523       bgp_set_attr_ptr(&attrs, pool, BA_AGGREGATOR, 0, aggregator_to_old(pool, a->u.ptr));
1524       bgp_set_attr_ptr(&attrs, pool, BA_AS4_AGGREGATOR, 0, a->u.ptr);
1525     }
1526   }
1527
1528   /*
1529    * Presence of mandatory attributes ORIGIN and AS_PATH is ensured by above
1530    * conditions. Presence and validity of quasi-mandatory NEXT_HOP attribute
1531    * should be checked in AF-specific hooks.
1532    */
1533
1534   /* Apply per-attribute export hooks for validatation and normalization */
1535   return bgp_export_attrs(&s, attrs);
1536 }
1537
1538 void
1539 bgp_rt_notify(struct proto *P, struct channel *C, net *n, rte *new, rte *old)
1540 {
1541   struct bgp_proto *p = (void *) P;
1542   struct bgp_channel *c = (void *) C;
1543   struct bgp_bucket *buck;
1544   struct bgp_prefix *px;
1545   u32 path;
1546
1547   if (new)
1548   {
1549     struct ea_list *attrs = bgp_update_attrs(p, c, new, new->attrs->eattrs, bgp_linpool2);
1550
1551     /* If attributes are invalid, we fail back to withdraw */
1552     buck = attrs ? bgp_get_bucket(c, attrs) : bgp_get_withdraw_bucket(c);
1553     path = new->attrs->src->global_id;
1554
1555     lp_flush(bgp_linpool2);
1556   }
1557   else
1558   {
1559     buck = bgp_get_withdraw_bucket(c);
1560     path = old->attrs->src->global_id;
1561   }
1562
1563   px = bgp_get_prefix(c, n->n.addr, c->add_path_tx ? path : 0);
1564   add_tail(&buck->prefixes, &px->buck_node);
1565
1566   bgp_schedule_packet(p->conn, c, PKT_UPDATE);
1567 }
1568
1569
1570 static inline u32
1571 bgp_get_neighbor(rte *r)
1572 {
1573   eattr *e = ea_find(r->attrs->eattrs, EA_CODE(PROTOCOL_BGP, BA_AS_PATH));
1574   u32 as;
1575
1576   if (e && as_path_get_first_regular(e->u.ptr, &as))
1577     return as;
1578
1579   /* If AS_PATH is not defined, we treat rte as locally originated */
1580   struct bgp_proto *p = (void *) r->attrs->src->proto;
1581   return p->cf->confederation ?: p->local_as;
1582 }
1583
1584 static inline int
1585 rte_resolvable(rte *rt)
1586 {
1587   return rt->attrs->dest == RTD_UNICAST;
1588 }
1589
1590 static inline int
1591 rte_stale(rte *r)
1592 {
1593   if (r->u.bgp.stale < 0)
1594   {
1595     /* If staleness is unknown, compute and cache it */
1596     eattr *a = ea_find(r->attrs->eattrs, EA_CODE(PROTOCOL_BGP, BA_COMMUNITY));
1597     r->u.bgp.stale = a && int_set_contains(a->u.ptr, BGP_COMM_LLGR_STALE);
1598   }
1599
1600   return r->u.bgp.stale;
1601 }
1602
1603 int
1604 bgp_rte_better(rte *new, rte *old)
1605 {
1606   struct bgp_proto *new_bgp = (struct bgp_proto *) new->attrs->src->proto;
1607   struct bgp_proto *old_bgp = (struct bgp_proto *) old->attrs->src->proto;
1608   eattr *x, *y;
1609   u32 n, o;
1610
1611   /* Skip suppressed routes (see bgp_rte_recalculate()) */
1612   n = new->u.bgp.suppressed;
1613   o = old->u.bgp.suppressed;
1614   if (n > o)
1615     return 0;
1616   if (n < o)
1617     return 1;
1618
1619   /* RFC 4271 9.1.2.1. Route resolvability test */
1620   n = rte_resolvable(new);
1621   o = rte_resolvable(old);
1622   if (n > o)
1623     return 1;
1624   if (n < o)
1625     return 0;
1626
1627   /* LLGR draft - depreference stale routes */
1628   n = rte_stale(new);
1629   o = rte_stale(old);
1630   if (n > o)
1631     return 0;
1632   if (n < o)
1633     return 1;
1634
1635  /* Start with local preferences */
1636   x = ea_find(new->attrs->eattrs, EA_CODE(PROTOCOL_BGP, BA_LOCAL_PREF));
1637   y = ea_find(old->attrs->eattrs, EA_CODE(PROTOCOL_BGP, BA_LOCAL_PREF));
1638   n = x ? x->u.data : new_bgp->cf->default_local_pref;
1639   o = y ? y->u.data : old_bgp->cf->default_local_pref;
1640   if (n > o)
1641     return 1;
1642   if (n < o)
1643     return 0;
1644
1645   /* RFC 4271 9.1.2.2. a)  Use AS path lengths */
1646   if (new_bgp->cf->compare_path_lengths || old_bgp->cf->compare_path_lengths)
1647   {
1648     x = ea_find(new->attrs->eattrs, EA_CODE(PROTOCOL_BGP, BA_AS_PATH));
1649     y = ea_find(old->attrs->eattrs, EA_CODE(PROTOCOL_BGP, BA_AS_PATH));
1650     n = x ? as_path_getlen(x->u.ptr) : AS_PATH_MAXLEN;
1651     o = y ? as_path_getlen(y->u.ptr) : AS_PATH_MAXLEN;
1652     if (n < o)
1653       return 1;
1654     if (n > o)
1655       return 0;
1656   }
1657
1658   /* RFC 4271 9.1.2.2. b) Use origins */
1659   x = ea_find(new->attrs->eattrs, EA_CODE(PROTOCOL_BGP, BA_ORIGIN));
1660   y = ea_find(old->attrs->eattrs, EA_CODE(PROTOCOL_BGP, BA_ORIGIN));
1661   n = x ? x->u.data : ORIGIN_INCOMPLETE;
1662   o = y ? y->u.data : ORIGIN_INCOMPLETE;
1663   if (n < o)
1664     return 1;
1665   if (n > o)
1666     return 0;
1667
1668   /* RFC 4271 9.1.2.2. c) Compare MED's */
1669   /* Proper RFC 4271 path selection cannot be interpreted as finding
1670    * the best path in some ordering. It is implemented partially in
1671    * bgp_rte_recalculate() when deterministic_med option is
1672    * active. Without that option, the behavior is just an
1673    * approximation, which in specific situations may lead to
1674    * persistent routing loops, because it is nondeterministic - it
1675    * depends on the order in which routes appeared. But it is also the
1676    * same behavior as used by default in Cisco routers, so it is
1677    * probably not a big issue.
1678    */
1679   if (new_bgp->cf->med_metric || old_bgp->cf->med_metric ||
1680       (bgp_get_neighbor(new) == bgp_get_neighbor(old)))
1681   {
1682     x = ea_find(new->attrs->eattrs, EA_CODE(PROTOCOL_BGP, BA_MULTI_EXIT_DISC));
1683     y = ea_find(old->attrs->eattrs, EA_CODE(PROTOCOL_BGP, BA_MULTI_EXIT_DISC));
1684     n = x ? x->u.data : new_bgp->cf->default_med;
1685     o = y ? y->u.data : old_bgp->cf->default_med;
1686     if (n < o)
1687       return 1;
1688     if (n > o)
1689       return 0;
1690   }
1691
1692   /* RFC 4271 9.1.2.2. d) Prefer external peers */
1693   if (new_bgp->is_interior > old_bgp->is_interior)
1694     return 0;
1695   if (new_bgp->is_interior < old_bgp->is_interior)
1696     return 1;
1697
1698   /* RFC 4271 9.1.2.2. e) Compare IGP metrics */
1699   n = new_bgp->cf->igp_metric ? new->attrs->igp_metric : 0;
1700   o = old_bgp->cf->igp_metric ? old->attrs->igp_metric : 0;
1701   if (n < o)
1702     return 1;
1703   if (n > o)
1704     return 0;
1705
1706   /* RFC 4271 9.1.2.2. f) Compare BGP identifiers */
1707   /* RFC 4456 9. a) Use ORIGINATOR_ID instead of local neighbor ID */
1708   x = ea_find(new->attrs->eattrs, EA_CODE(PROTOCOL_BGP, BA_ORIGINATOR_ID));
1709   y = ea_find(old->attrs->eattrs, EA_CODE(PROTOCOL_BGP, BA_ORIGINATOR_ID));
1710   n = x ? x->u.data : new_bgp->remote_id;
1711   o = y ? y->u.data : old_bgp->remote_id;
1712
1713   /* RFC 5004 - prefer older routes */
1714   /* (if both are external and from different peer) */
1715   if ((new_bgp->cf->prefer_older || old_bgp->cf->prefer_older) &&
1716       !new_bgp->is_internal && n != o)
1717     return 0;
1718
1719   /* rest of RFC 4271 9.1.2.2. f) */
1720   if (n < o)
1721     return 1;
1722   if (n > o)
1723     return 0;
1724
1725   /* RFC 4456 9. b) Compare cluster list lengths */
1726   x = ea_find(new->attrs->eattrs, EA_CODE(PROTOCOL_BGP, BA_CLUSTER_LIST));
1727   y = ea_find(old->attrs->eattrs, EA_CODE(PROTOCOL_BGP, BA_CLUSTER_LIST));
1728   n = x ? int_set_get_size(x->u.ptr) : 0;
1729   o = y ? int_set_get_size(y->u.ptr) : 0;
1730   if (n < o)
1731     return 1;
1732   if (n > o)
1733     return 0;
1734
1735   /* RFC 4271 9.1.2.2. g) Compare peer IP adresses */
1736   return ipa_compare(new_bgp->remote_ip, old_bgp->remote_ip) < 0;
1737 }
1738
1739
1740 int
1741 bgp_rte_mergable(rte *pri, rte *sec)
1742 {
1743   struct bgp_proto *pri_bgp = (struct bgp_proto *) pri->attrs->src->proto;
1744   struct bgp_proto *sec_bgp = (struct bgp_proto *) sec->attrs->src->proto;
1745   eattr *x, *y;
1746   u32 p, s;
1747
1748   /* Skip suppressed routes (see bgp_rte_recalculate()) */
1749   if (pri->u.bgp.suppressed != sec->u.bgp.suppressed)
1750     return 0;
1751
1752   /* RFC 4271 9.1.2.1. Route resolvability test */
1753   if (!rte_resolvable(sec))
1754     return 0;
1755
1756   /* LLGR draft - depreference stale routes */
1757   if (rte_stale(pri) != rte_stale(sec))
1758     return 0;
1759
1760   /* Start with local preferences */
1761   x = ea_find(pri->attrs->eattrs, EA_CODE(PROTOCOL_BGP, BA_LOCAL_PREF));
1762   y = ea_find(sec->attrs->eattrs, EA_CODE(PROTOCOL_BGP, BA_LOCAL_PREF));
1763   p = x ? x->u.data : pri_bgp->cf->default_local_pref;
1764   s = y ? y->u.data : sec_bgp->cf->default_local_pref;
1765   if (p != s)
1766     return 0;
1767
1768   /* RFC 4271 9.1.2.2. a)  Use AS path lengths */
1769   if (pri_bgp->cf->compare_path_lengths || sec_bgp->cf->compare_path_lengths)
1770   {
1771     x = ea_find(pri->attrs->eattrs, EA_CODE(PROTOCOL_BGP, BA_AS_PATH));
1772     y = ea_find(sec->attrs->eattrs, EA_CODE(PROTOCOL_BGP, BA_AS_PATH));
1773     p = x ? as_path_getlen(x->u.ptr) : AS_PATH_MAXLEN;
1774     s = y ? as_path_getlen(y->u.ptr) : AS_PATH_MAXLEN;
1775
1776     if (p != s)
1777       return 0;
1778
1779 //    if (DELTA(p, s) > pri_bgp->cf->relax_multipath)
1780 //      return 0;
1781   }
1782
1783   /* RFC 4271 9.1.2.2. b) Use origins */
1784   x = ea_find(pri->attrs->eattrs, EA_CODE(PROTOCOL_BGP, BA_ORIGIN));
1785   y = ea_find(sec->attrs->eattrs, EA_CODE(PROTOCOL_BGP, BA_ORIGIN));
1786   p = x ? x->u.data : ORIGIN_INCOMPLETE;
1787   s = y ? y->u.data : ORIGIN_INCOMPLETE;
1788   if (p != s)
1789     return 0;
1790
1791   /* RFC 4271 9.1.2.2. c) Compare MED's */
1792   if (pri_bgp->cf->med_metric || sec_bgp->cf->med_metric ||
1793       (bgp_get_neighbor(pri) == bgp_get_neighbor(sec)))
1794   {
1795     x = ea_find(pri->attrs->eattrs, EA_CODE(PROTOCOL_BGP, BA_MULTI_EXIT_DISC));
1796     y = ea_find(sec->attrs->eattrs, EA_CODE(PROTOCOL_BGP, BA_MULTI_EXIT_DISC));
1797     p = x ? x->u.data : pri_bgp->cf->default_med;
1798     s = y ? y->u.data : sec_bgp->cf->default_med;
1799     if (p != s)
1800       return 0;
1801   }
1802
1803   /* RFC 4271 9.1.2.2. d) Prefer external peers */
1804   if (pri_bgp->is_interior != sec_bgp->is_interior)
1805     return 0;
1806
1807   /* RFC 4271 9.1.2.2. e) Compare IGP metrics */
1808   p = pri_bgp->cf->igp_metric ? pri->attrs->igp_metric : 0;
1809   s = sec_bgp->cf->igp_metric ? sec->attrs->igp_metric : 0;
1810   if (p != s)
1811     return 0;
1812
1813   /* Remaining criteria are ignored */
1814
1815   return 1;
1816 }
1817
1818
1819 static inline int
1820 same_group(rte *r, u32 lpref, u32 lasn)
1821 {
1822   return (r->pref == lpref) && (bgp_get_neighbor(r) == lasn);
1823 }
1824
1825 static inline int
1826 use_deterministic_med(rte *r)
1827 {
1828   struct proto *P = r->attrs->src->proto;
1829   return (P->proto == &proto_bgp) && ((struct bgp_proto *) P)->cf->deterministic_med;
1830 }
1831
1832 int
1833 bgp_rte_recalculate(rtable *table, net *net, rte *new, rte *old, rte *old_best)
1834 {
1835   rte *r, *s;
1836   rte *key = new ? new : old;
1837   u32 lpref = key->pref;
1838   u32 lasn = bgp_get_neighbor(key);
1839   int old_is_group_best = 0;
1840
1841   /*
1842    * Proper RFC 4271 path selection is a bit complicated, it cannot be
1843    * implemented just by rte_better(), because it is not a linear
1844    * ordering. But it can be splitted to two levels, where the lower
1845    * level chooses the best routes in each group of routes from the
1846    * same neighboring AS and higher level chooses the best route (with
1847    * a slightly different ordering) between the best-in-group routes.
1848    *
1849    * When deterministic_med is disabled, we just ignore this issue and
1850    * choose the best route by bgp_rte_better() alone. If enabled, the
1851    * lower level of the route selection is done here (for the group
1852    * to which the changed route belongs), all routes in group are
1853    * marked as suppressed, just chosen best-in-group is not.
1854    *
1855    * Global best route selection then implements higher level by
1856    * choosing between non-suppressed routes (as they are always
1857    * preferred over suppressed routes). Routes from BGP protocols
1858    * that do not set deterministic_med are just never suppressed. As
1859    * they do not participate in the lower level selection, it is OK
1860    * that this fn is not called for them.
1861    *
1862    * The idea is simple, the implementation is more problematic,
1863    * mostly because of optimizations in rte_recalculate() that
1864    * avoids full recalculation in most cases.
1865    *
1866    * We can assume that at least one of new, old is non-NULL and both
1867    * are from the same protocol with enabled deterministic_med. We
1868    * group routes by both neighbor AS (lasn) and preference (lpref),
1869    * because bgp_rte_better() does not handle preference itself.
1870    */
1871
1872   /* If new and old are from different groups, we just process that
1873      as two independent events */
1874   if (new && old && !same_group(old, lpref, lasn))
1875   {
1876     int i1, i2;
1877     i1 = bgp_rte_recalculate(table, net, NULL, old, old_best);
1878     i2 = bgp_rte_recalculate(table, net, new, NULL, old_best);
1879     return i1 || i2;
1880   }
1881
1882   /*
1883    * We could find the best-in-group and then make some shortcuts like
1884    * in rte_recalculate, but as we would have to walk through all
1885    * net->routes just to find it, it is probably not worth. So we
1886    * just have two simpler fast cases that use just the old route.
1887    * We also set suppressed flag to avoid using it in bgp_rte_better().
1888    */
1889
1890   if (new)
1891     new->u.bgp.suppressed = 1;
1892
1893   if (old)
1894   {
1895     old_is_group_best = !old->u.bgp.suppressed;
1896     old->u.bgp.suppressed = 1;
1897     int new_is_better = new && bgp_rte_better(new, old);
1898
1899     /* The first case - replace not best with worse (or remove not best) */
1900     if (!old_is_group_best && !new_is_better)
1901       return 0;
1902
1903     /* The second case - replace the best with better */
1904     if (old_is_group_best && new_is_better)
1905     {
1906       /* new is best-in-group, the see discussion below - this is
1907          a special variant of NBG && OBG. From OBG we can deduce
1908          that same_group(old_best) iff (old == old_best)  */
1909       new->u.bgp.suppressed = 0;
1910       return (old == old_best);
1911     }
1912   }
1913
1914   /* The default case - find a new best-in-group route */
1915   r = new; /* new may not be in the list */
1916   for (s=net->routes; rte_is_valid(s); s=s->next)
1917     if (use_deterministic_med(s) && same_group(s, lpref, lasn))
1918     {
1919       s->u.bgp.suppressed = 1;
1920       if (!r || bgp_rte_better(s, r))
1921         r = s;
1922     }
1923
1924   /* Simple case - the last route in group disappears */
1925   if (!r)
1926     return 0;
1927
1928   /* Found best-in-group */
1929   r->u.bgp.suppressed = 0;
1930
1931   /*
1932    * There are generally two reasons why we have to force
1933    * recalculation (return 1): First, the new route may be wrongfully
1934    * chosen to be the best in the first case check in
1935    * rte_recalculate(), this may happen only if old_best is from the
1936    * same group. Second, another (different than new route)
1937    * best-in-group is chosen and that may be the proper best (although
1938    * rte_recalculate() without ignore that possibility).
1939    *
1940    * There are three possible cases according to whether the old route
1941    * was the best in group (OBG, stored in old_is_group_best) and
1942    * whether the new route is the best in group (NBG, tested by r == new).
1943    * These cases work even if old or new is NULL.
1944    *
1945    * NBG -> new is a possible candidate for the best route, so we just
1946    *        check for the first reason using same_group().
1947    *
1948    * !NBG && OBG -> Second reason applies, return 1
1949    *
1950    * !NBG && !OBG -> Best in group does not change, old != old_best,
1951    *                 rte_better(new, old_best) is false and therefore
1952    *                 the first reason does not apply, return 0
1953    */
1954
1955   if (r == new)
1956     return old_best && same_group(old_best, lpref, lasn);
1957   else
1958     return old_is_group_best;
1959 }
1960
1961 struct rte *
1962 bgp_rte_modify_stale(struct rte *r, struct linpool *pool)
1963 {
1964   eattr *a = ea_find(r->attrs->eattrs, EA_CODE(PROTOCOL_BGP, BA_COMMUNITY));
1965   struct adata *ad = a ? a->u.ptr : NULL;
1966   uint flags = a ? a->flags : BAF_PARTIAL;
1967
1968   if (ad && int_set_contains(ad, BGP_COMM_NO_LLGR))
1969     return NULL;
1970
1971   if (ad && int_set_contains(ad, BGP_COMM_LLGR_STALE))
1972     return r;
1973
1974   r = rte_cow_rta(r, pool);
1975   bgp_set_attr_ptr(&(r->attrs->eattrs), pool, BA_COMMUNITY, flags,
1976                    int_set_add(pool, ad, BGP_COMM_LLGR_STALE));
1977   r->u.bgp.stale = 1;
1978
1979   return r;
1980 }
1981
1982
1983 /*
1984  * Reconstruct AS_PATH and AGGREGATOR according to RFC 6793 4.2.3
1985  */
1986 static void
1987 bgp_process_as4_attrs(ea_list **attrs, struct linpool *pool)
1988 {
1989   eattr *p2 = bgp_find_attr(*attrs, BA_AS_PATH);
1990   eattr *p4 = bgp_find_attr(*attrs, BA_AS4_PATH);
1991   eattr *a2 = bgp_find_attr(*attrs, BA_AGGREGATOR);
1992   eattr *a4 = bgp_find_attr(*attrs, BA_AS4_AGGREGATOR);
1993
1994   /* First, unset AS4_* attributes */
1995   if (p4) bgp_unset_attr(attrs, pool, BA_AS4_PATH);
1996   if (a4) bgp_unset_attr(attrs, pool, BA_AS4_AGGREGATOR);
1997
1998   /* Handle AGGREGATOR attribute */
1999   if (a2 && a4)
2000   {
2001     u32 a2_asn = get_u32(a2->u.ptr->data);
2002
2003     /* If routes were aggregated by an old router, then AS4_PATH and
2004        AS4_AGGREGATOR are invalid. In that case we give up. */
2005     if (a2_asn != AS_TRANS)
2006       return;
2007
2008     /* Use AS4_AGGREGATOR instead of AGGREGATOR */
2009     a2->u.ptr = a4->u.ptr;
2010   }
2011
2012   /* Handle AS_PATH attribute */
2013   if (p2 && p4)
2014   {
2015     /* Both as_path_getlen() and as_path_cut() take AS_CONFED* as zero length */
2016     int p2_len = as_path_getlen(p2->u.ptr);
2017     int p4_len = as_path_getlen(p4->u.ptr);
2018
2019     /* AS_PATH is too short, give up */
2020     if (p2_len < p4_len)
2021       return;
2022
2023     /* Merge AS_PATH and AS4_PATH */
2024     as_path_cut(p2->u.ptr, p2_len - p4_len);
2025     p2->u.ptr = as_path_merge(pool, p2->u.ptr, p4->u.ptr);
2026   }
2027 }
2028
2029 int
2030 bgp_get_attr(eattr *a, byte *buf, int buflen)
2031 {
2032   uint i = EA_ID(a->id);
2033   const struct bgp_attr_desc *d;
2034   int len;
2035
2036   if (bgp_attr_known(i))
2037   {
2038     d = &bgp_attr_table[i];
2039     len = bsprintf(buf, "%s", d->name);
2040     buf += len;
2041     if (d->format)
2042     {
2043       *buf++ = ':';
2044       *buf++ = ' ';
2045       d->format(a, buf, buflen - len - 2);
2046       return GA_FULL;
2047     }
2048     return GA_NAME;
2049   }
2050
2051   bsprintf(buf, "%02x%s", i, (a->flags & BAF_TRANSITIVE) ? " [t]" : "");
2052   return GA_NAME;
2053 }
2054
2055 void
2056 bgp_get_route_info(rte *e, byte *buf)
2057 {
2058   eattr *p = ea_find(e->attrs->eattrs, EA_CODE(PROTOCOL_BGP, BA_AS_PATH));
2059   eattr *o = ea_find(e->attrs->eattrs, EA_CODE(PROTOCOL_BGP, BA_ORIGIN));
2060   u32 origas;
2061
2062   buf += bsprintf(buf, " (%d", e->pref);
2063
2064   if (e->u.bgp.suppressed)
2065     buf += bsprintf(buf, "-");
2066
2067   if (rte_stale(e))
2068     buf += bsprintf(buf, "s");
2069
2070   if (e->attrs->hostentry)
2071   {
2072     if (!rte_resolvable(e))
2073       buf += bsprintf(buf, "/-");
2074     else if (e->attrs->igp_metric >= IGP_METRIC_UNKNOWN)
2075       buf += bsprintf(buf, "/?");
2076     else
2077       buf += bsprintf(buf, "/%d", e->attrs->igp_metric);
2078   }
2079   buf += bsprintf(buf, ") [");
2080
2081   if (p && as_path_get_last(p->u.ptr, &origas))
2082     buf += bsprintf(buf, "AS%u", origas);
2083   if (o)
2084     buf += bsprintf(buf, "%c", "ie?"[o->u.data]);
2085   strcpy(buf, "]");
2086 }