bgp.c

   1 /*
   2  * BGPv4
   3  * Used to advertise routes for upstream (l2tp port, rather than gratiutious
   4  * arp) and downstream--allowing routers to load-balance both.
   5  *
   6  * Implementation limitations:
   7  * - We never listen for incoming connections (session always initiated by us).
   8  * - Any routes advertised by the peer are accepted, but ignored.
   9  * - No password support; neither RFC1771 (which no-one seems to do anyway)
  10  *   nor RFC2385 (which requires a kernel patch on 2.4 kernels).
  11  */
  12
  13 char const *cvs_id_bgp = "$Id: bgp.c,v 1.5 2004-11-05 04:55:26 bodea Exp $";
  14
  15 #include <stdlib.h>
  16 #include <unistd.h>
  17 #include <string.h>
  18 #include <time.h>
  19 #include <errno.h>
  20 #include <sys/socket.h>
  21 #include <netinet/in.h>
  22 #include <arpa/inet.h>
  23 #include <netdb.h>
  24 #include <fcntl.h>
  25
  26 #include "l2tpns.h"
  27 #include "bgp.h"
  28 #include "util.h"
  29
  30 static void bgp_clear(struct bgp_peer *peer);
  31 static void bgp_set_retry(struct bgp_peer *peer);
  32 static void bgp_cidr(in_addr_t ip, in_addr_t mask, struct bgp_ip_prefix *pfx);
  33 static struct bgp_route_list *bgp_insert_route(struct bgp_route_list *head,
  34     struct bgp_route_list *new);
  35
  36 static void bgp_free_routes(struct bgp_route_list *routes);
  37 static char const *bgp_state_str(enum bgp_state state);
  38 static char const *bgp_msg_type_str(u8 type);
  39 static int bgp_connect(struct bgp_peer *peer);
  40 static int bgp_handle_connect(struct bgp_peer *peer);
  41 static int bgp_write(struct bgp_peer *peer);
  42 static int bgp_read(struct bgp_peer *peer);
  43 static int bgp_handle_input(struct bgp_peer *peer);
  44 static int bgp_send_open(struct bgp_peer *peer);
  45 static int bgp_send_keepalive(struct bgp_peer *peer);
  46 static int bgp_send_update(struct bgp_peer *peer);
  47 static int bgp_send_notification(struct bgp_peer *peer, u8 code, u8 subcode);
  48
  49 static u16 our_as;
  50
  51 /* prepare peer structure, globals */
  52 int bgp_setup(int as)
  53 {
  54     int i;
  55     struct bgp_peer *peer;
  56
  57     for (i = 0; i < BGP_NUM_PEERS; i++)
  58     {
  59         peer = &bgp_peers[i];
  60         memset(peer, 0, sizeof(*peer));
  61
  62         peer->addr = INADDR_NONE;
  63         peer->sock = -1;
  64         peer->state = peer->next_state = Disabled;
  65
  66         if (!((peer->outbuf = malloc(sizeof(*peer->outbuf)))
  67             && (peer->inbuf = malloc(sizeof(*peer->inbuf)))))
  68         {
  69             LOG(0, 0, 0, 0, "Can't allocate buffers for bgp peer (%s)\n",
  70                 strerror(errno));
  71
  72             return 0;
  73         }
  74     }
  75
  76     if (as < 1)
  77         as = 0;
  78
  79     if ((our_as = as))
  80         return 0;
  81
  82     bgp_routes = 0;
  83     bgp_configured = 0; /* set by bgp_start */
  84
  85     return 1;
  86 }
  87
  88 /* start connection with a peer */
  89 int bgp_start(struct bgp_peer *peer, char *name, int as, int enable)
  90 {
  91     struct hostent *h;
  92     int ibgp;
  93     int i;
  94     struct bgp_path_attr a;
  95     char path_attrs[64];
  96     char *p = path_attrs;
  97     in_addr_t ip;
  98     u32 metric = htonl(BGP_METRIC);
  99     u32 no_export = htonl(BGP_COMMUNITY_NO_EXPORT);
 100
 101     if (!our_as)
 102         return 0;
 103
 104     if (peer->state != Disabled)
 105         bgp_halt(peer);
 106
 107     snprintf(peer->name, sizeof(peer->name), "%s", name);
 108
 109     if (!(h = gethostbyname(name)) || h->h_addrtype != AF_INET)
 110     {
 111         LOG(0, 0, 0, 0, "Can't get address for BGP peer %s (%s)\n",
 112             name, h ? "no address" : hstrerror(h_errno));
 113
 114         return 0;
 115     }
 116
 117     memcpy(&peer->addr, h->h_addr, sizeof(peer->addr));
 118     peer->as = as > 0 ? as : our_as;
 119     ibgp = peer->as == our_as;
 120
 121     /* clear buffers, go to Idle state */
 122     peer->next_state = Idle;
 123     bgp_clear(peer);
 124
 125     /* set initial routing state */
 126     peer->routing = enable;
 127
 128     /* all our routes use the same attributes, so prepare it in advance */
 129     if (peer->path_attrs)
 130         free(peer->path_attrs);
 131
 132     peer->path_attr_len = 0;
 133
 134     /* ORIGIN */
 135     a.flags = BGP_PATH_ATTR_FLAG_TRANS;
 136     a.code = BGP_PATH_ATTR_CODE_ORIGIN;
 137     a.data.s.len = 1;
 138     a.data.s.value[0] = BGP_PATH_ATTR_CODE_ORIGIN_IGP;
 139
 140 #define ADD_ATTRIBUTE()         do { \
 141     i = BGP_PATH_ATTR_SIZE(a);  \
 142     memcpy(p, &a, i);           \
 143     p += i;                     \
 144     peer->path_attr_len += i;   } while (0)
 145
 146     ADD_ATTRIBUTE();
 147
 148     /* AS_PATH */
 149     a.flags = BGP_PATH_ATTR_FLAG_TRANS;
 150     a.code = BGP_PATH_ATTR_CODE_AS_PATH;
 151     if (ibgp)
 152     {
 153         /* empty path */
 154         a.data.s.len = 0;
 155     }
 156     else
 157     {
 158         /* just our AS */
 159         struct {
 160             u8 type;
 161             u8 len;
 162             u16 value;
 163         } as_path = {
 164             BGP_PATH_ATTR_CODE_AS_PATH_AS_SEQUENCE,
 165             1,
 166             htons(our_as),
 167         };
 168
 169         a.data.s.len = sizeof(as_path);
 170         memcpy(&a.data.s.value, &as_path, sizeof(as_path));
 171     }
 172
 173     ADD_ATTRIBUTE();
 174
 175     /* NEXT_HOP */
 176     a.flags = BGP_PATH_ATTR_FLAG_TRANS;
 177     a.code = BGP_PATH_ATTR_CODE_NEXT_HOP;
 178     ip = my_address; /* we're it */
 179     a.data.s.len = sizeof(ip);
 180     memcpy(a.data.s.value, &ip, sizeof(ip));
 181
 182     ADD_ATTRIBUTE();
 183
 184     /* MULTI_EXIT_DISC */
 185     a.flags = BGP_PATH_ATTR_FLAG_OPTIONAL;
 186     a.code = BGP_PATH_ATTR_CODE_MULTI_EXIT_DISC;
 187     a.data.s.len = sizeof(metric);
 188     memcpy(a.data.s.value, &metric, sizeof(metric));
 189
 190     ADD_ATTRIBUTE();
 191
 192     if (ibgp)
 193     {
 194         u32 local_pref = htonl(BGP_LOCAL_PREF);
 195
 196         /* LOCAL_PREF */
 197         a.flags = BGP_PATH_ATTR_FLAG_TRANS;
 198         a.code = BGP_PATH_ATTR_CODE_LOCAL_PREF;
 199         a.data.s.len = sizeof(local_pref);
 200         memcpy(a.data.s.value, &local_pref, sizeof(local_pref));
 201
 202         ADD_ATTRIBUTE();
 203     }
 204
 205     /* COMMUNITIES */
 206     a.flags = BGP_PATH_ATTR_FLAG_OPTIONAL | BGP_PATH_ATTR_FLAG_TRANS;
 207     a.code = BGP_PATH_ATTR_CODE_COMMUNITIES;
 208     a.data.s.len = sizeof(no_export);
 209     memcpy(a.data.s.value, &no_export, sizeof(no_export));
 210
 211     ADD_ATTRIBUTE();
 212
 213     if (!(peer->path_attrs = malloc(peer->path_attr_len)))
 214     {
 215         LOG(0, 0, 0, 0, "Can't allocate path_attrs for %s (%s)\n",
 216             name, strerror(errno));
 217
 218         return 0;
 219     }
 220
 221     memcpy(peer->path_attrs, path_attrs, peer->path_attr_len);
 222
 223     LOG(4, 0, 0, 0, "Initiating BGP connection to %s (routing %s)\n",
 224         name, enable ? "enabled" : "suspended");
 225
 226     /* we have at least one peer configured */
 227     bgp_configured = 1;
 228
 229     /* connect */
 230     return bgp_connect(peer);
 231 }
 232
 233 /* clear counters, timers, routes and buffers; close socket; move to
 234    next_state, which may be Disabled or Idle */
 235 static void bgp_clear(struct bgp_peer *peer)
 236 {
 237     if (peer->sock != -1)
 238     {
 239         close(peer->sock);
 240         peer->sock = -1;
 241     }
 242
 243     peer->keepalive_time = 0;
 244     peer->hold = 0;
 245     peer->expire_time = 0;
 246
 247     bgp_free_routes(peer->routes);
 248     peer->routes = 0;
 249
 250     peer->outbuf->packet.header.len = 0;
 251     peer->outbuf->done = 0;
 252     peer->inbuf->packet.header.len = 0;
 253     peer->inbuf->done = 0;
 254
 255     peer->cli_flag = 0;
 256
 257     if (peer->state != peer->next_state)
 258     {
 259         peer->state = peer->next_state;
 260         peer->state_time = time_now;
 261
 262         LOG(4, 0, 0, 0, "BGP peer %s: state %s\n", peer->name,
 263             bgp_state_str(peer->next_state));
 264     }
 265 }
 266
 267 /* initiate a clean shutdown */
 268 void bgp_stop(struct bgp_peer *peer)
 269 {
 270     LOG(4, 0, 0, 0, "Terminating BGP connection to %s\n", peer->name);
 271     bgp_send_notification(peer, BGP_ERR_CEASE, 0);
 272 }
 273
 274 /* drop connection (if any) and set state to Disabled */
 275 void bgp_halt(struct bgp_peer *peer)
 276 {
 277     LOG(4, 0, 0, 0, "Aborting BGP connection to %s\n", peer->name);
 278     peer->next_state = Disabled;
 279     bgp_clear(peer);
 280 }
 281
 282 /* drop connection (if any) and set to Idle for connection retry */
 283 int bgp_restart(struct bgp_peer *peer)
 284 {
 285     peer->next_state = Idle;
 286     bgp_clear(peer);
 287
 288     /* restart now */
 289     peer->retry_time = time_now;
 290     peer->retry_count = 0;
 291
 292     /* connect */
 293     return bgp_connect(peer);
 294 }
 295
 296 static void bgp_set_retry(struct bgp_peer *peer)
 297 {
 298     if (peer->retry_count++ < BGP_MAX_RETRY)
 299     {
 300         peer->retry_time = time_now + (BGP_RETRY_BACKOFF * peer->retry_count);
 301         peer->next_state = Idle;
 302         bgp_clear(peer);
 303     }
 304     else
 305         bgp_halt(peer); /* give up */
 306 }
 307
 308 /* convert ip/mask to CIDR notation */
 309 static void bgp_cidr(in_addr_t ip, in_addr_t mask, struct bgp_ip_prefix *pfx)
 310 {
 311     int i;
 312     u32 b;
 313
 314     /* convert to prefix notation */
 315     pfx->len = 32;
 316     pfx->prefix = ip;
 317
 318     if (!mask) /* bogus */
 319         mask = 0xffffffff;
 320
 321     for (i = 0; i < 32 && ((b = ntohl(1 << i)), !(mask & b)); i++)
 322     {
 323         pfx->len--;
 324         pfx->prefix &= ~b;
 325     }
 326 }
 327
 328 /* insert route into list; sorted */
 329 static struct bgp_route_list *bgp_insert_route(struct bgp_route_list *head,
 330     struct bgp_route_list *new)
 331 {
 332     struct bgp_route_list *p = head;
 333     struct bgp_route_list *e = 0;
 334
 335     while (p && memcmp(&p->dest, &new->dest, sizeof(p->dest)) < 0)
 336     {
 337         e = p;
 338         p = p->next;
 339     }
 340
 341     if (e)
 342     {
 343         new->next = e->next;
 344         e->next = new;
 345     }
 346     else
 347     {
 348         new->next = head;
 349         head = new;
 350     }
 351
 352     return head;
 353 }
 354
 355 /* add route to list for peers */
 356 /*
 357  * Note:  this doesn't do route aggregation, nor drop routes if a less
 358  * specific match already exists (partly because I'm lazy, but also so
 359  * that if that route is later deleted we don't have to be concerned
 360  * about adding back the more specific one).
 361  */
 362 int bgp_add_route(in_addr_t ip, in_addr_t mask)
 363 {
 364     struct bgp_route_list *r = bgp_routes;
 365     struct bgp_route_list add;
 366     int i;
 367
 368     bgp_cidr(ip, mask, &add.dest);
 369     add.next = 0;
 370
 371     /* check for duplicate */
 372     while (r)
 373     {
 374         i = memcmp(&r->dest, &add.dest, sizeof(r->dest));
 375         if (!i)
 376             return 1; /* already covered */
 377
 378         if (i > 0)
 379             break;
 380
 381         r = r->next;
 382     }
 383
 384     /* insert into route list; sorted */
 385     if (!(r = malloc(sizeof(*r))))
 386     {
 387         LOG(0, 0, 0, 0, "Can't allocate route for %s/%d (%s)\n",
 388             inet_toa(add.dest.prefix), add.dest.len, strerror(errno));
 389
 390         return 0;
 391     }
 392
 393     memcpy(r, &add, sizeof(*r));
 394     bgp_routes = bgp_insert_route(bgp_routes, r);
 395
 396     /* flag established peers for update */
 397     for (i = 0; i < BGP_NUM_PEERS; i++)
 398         if (bgp_peers[i].state == Established)
 399             bgp_peers[i].update_routes = 1;
 400
 401     LOG(4, 0, 0, 0, "Registered BGP route %s/%d\n", inet_toa(add.dest.prefix),
 402         add.dest.len);
 403
 404     return 1;
 405 }
 406
 407 /* remove route from list for peers */
 408 int bgp_del_route(in_addr_t ip, in_addr_t mask)
 409 {
 410     struct bgp_route_list *r = bgp_routes;
 411     struct bgp_route_list *e = 0;
 412     struct bgp_route_list del;
 413     int i;
 414
 415     bgp_cidr(ip, mask, &del.dest);
 416     del.next = 0;
 417
 418     /* find entry in routes list and remove */
 419     while (r)
 420     {
 421         i = memcmp(&r->dest, &del.dest, sizeof(r->dest));
 422         if (!i)
 423         {
 424             if (e)
 425                 e->next = r->next;
 426             else
 427                 bgp_routes = r->next;
 428
 429             free(r);
 430             break;
 431         }
 432
 433         e = r;
 434
 435         if (i > 0)
 436             r = 0; /* stop */
 437         else
 438             r = r->next;
 439     }
 440
 441     /* not found */
 442     if (!r)
 443         return 1;
 444
 445     /* flag established peers for update */
 446     for (i = 0; i < BGP_NUM_PEERS; i++)
 447         if (bgp_peers[i].state == Established)
 448             bgp_peers[i].update_routes = 1;
 449
 450     LOG(4, 0, 0, 0, "Removed BGP route %s/%d\n", inet_toa(del.dest.prefix),
 451         del.dest.len);
 452
 453     return 1;
 454 }
 455
 456 /* enable or disable routing */
 457 void bgp_enable_routing(int enable)
 458 {
 459     int i;
 460
 461     for (i = 0; i < BGP_NUM_PEERS; i++)
 462     {
 463         bgp_peers[i].routing = enable;
 464
 465         /* flag established peers for update */
 466         if (bgp_peers[i].state == Established)
 467             bgp_peers[i].update_routes = 1;
 468     }
 469
 470     LOG(4, 0, 0, 0, "%s BGP routing\n", enable ? "Enabled" : "Suspended");
 471 }
 472
 473 /* return a bitmask indicating if the socket should be added to the
 474    read set (1) and or write set (2) for select */
 475 int bgp_select_state(struct bgp_peer *peer)
 476 {
 477     int flags = 0;
 478
 479     if (!bgp_configured)
 480         return 0;
 481
 482     if (peer->state == Disabled || peer->state == Idle)
 483         return 0;
 484
 485     if (peer->inbuf->done < BGP_MAX_PACKET_SIZE)
 486         flags |= 1;
 487
 488     if (peer->state == Connect ||               /* connection in progress */
 489         peer->update_routes ||                  /* routing updates */
 490         peer->outbuf->packet.header.len)        /* pending output */
 491         flags |= 2;
 492
 493     return flags;
 494 }
 495
 496 /* process bgp peer */
 497 int bgp_process(struct bgp_peer *peer, int readable, int writable)
 498 {
 499     if (!bgp_configured)
 500         return 0;
 501
 502     if (*peer->name && peer->cli_flag == BGP_CLI_RESTART)
 503         return bgp_restart(peer);
 504
 505     if (peer->state == Disabled)
 506         return 1;
 507
 508     if (peer->cli_flag)
 509     {
 510         switch (peer->cli_flag)
 511         {
 512         case BGP_CLI_SUSPEND:
 513             if (peer->routing)
 514             {
 515                 peer->routing = 0;
 516                 if (peer->state == Established)
 517                     peer->update_routes = 1;
 518             }
 519
 520             break;
 521
 522         case BGP_CLI_ENABLE:
 523             if (!peer->routing)
 524             {
 525                 peer->routing = 1;
 526                 if (peer->state == Established)
 527                     peer->update_routes = 1;
 528             }
 529
 530             break;
 531         }
 532
 533         peer->cli_flag = 0;
 534     }
 535
 536     /* handle empty/fill of buffers */
 537     if (writable)
 538     {
 539         int r = 1;
 540         if (peer->state == Connect)
 541             r = bgp_handle_connect(peer);
 542         else if (peer->outbuf->packet.header.len)
 543             r = bgp_write(peer);
 544
 545         if (!r)
 546             return 0;
 547     }
 548
 549     if (readable)
 550     {
 551         if (!bgp_read(peer))
 552             return 0;
 553     }
 554
 555     /* process input buffer contents */
 556     while (peer->inbuf->done >= sizeof(peer->inbuf->packet.header)
 557         && !peer->outbuf->packet.header.len) /* may need to queue a response */
 558     {
 559         if (bgp_handle_input(peer) < 0)
 560             return 0;
 561     }
 562
 563     /* process pending updates */
 564     if (peer->update_routes
 565         && !peer->outbuf->packet.header.len) /* ditto */
 566     {
 567         if (!bgp_send_update(peer))
 568             return 0;
 569     }
 570
 571     /* process timers */
 572     if (peer->state == Established)
 573     {
 574         if (time_now > peer->expire_time)
 575         {
 576             LOG(1, 0, 0, 0, "No message from BGP peer %s in %ds\n",
 577                 peer->name, peer->hold);
 578
 579             bgp_send_notification(peer, BGP_ERR_HOLD_TIMER_EXP, 0);
 580             return 0;
 581         }
 582
 583         if (time_now > peer->keepalive_time && !peer->outbuf->packet.header.len)
 584             bgp_send_keepalive(peer);
 585     }
 586     else if (peer->state == Idle)
 587     {
 588         if (time_now > peer->retry_time)
 589             return bgp_connect(peer);
 590     }
 591     else if (time_now > peer->state_time + BGP_KEEPALIVE_TIME)
 592     {
 593         LOG(1, 0, 0, 0, "%s timer expired for BGP peer %s\n",
 594             bgp_state_str(peer->state), peer->name);
 595
 596         return bgp_restart(peer);
 597     }
 598
 599     return 1;
 600 }
 601
 602 static void bgp_free_routes(struct bgp_route_list *routes)
 603 {
 604     struct bgp_route_list *tmp;
 605
 606     while ((tmp = routes))
 607     {
 608         routes = tmp->next;
 609         free(tmp);
 610     }
 611 }
 612
 613 static char const *bgp_state_str(enum bgp_state state)
 614 {
 615     switch (state)
 616     {
 617     case Disabled:      return "Disabled";
 618     case Idle:          return "Idle";
 619     case Connect:       return "Connect";
 620     case Active:        return "Active";
 621     case OpenSent:      return "OpenSent";
 622     case OpenConfirm:   return "OpenConfirm";
 623     case Established:   return "Established";
 624     }
 625
 626     return "?";
 627 }
 628
 629 static char const *bgp_msg_type_str(u8 type)
 630 {
 631     switch (type)
 632     {
 633     case BGP_MSG_OPEN:          return "OPEN";
 634     case BGP_MSG_UPDATE:        return "UPDATE";
 635     case BGP_MSG_NOTIFICATION:  return "NOTIFICATION";
 636     case BGP_MSG_KEEPALIVE:     return "KEEPALIVE";
 637     }
 638
 639     return "?";
 640 }
 641
 642 /* attempt to connect to peer */
 643 static int bgp_connect(struct bgp_peer *peer)
 644 {
 645     static int bgp_port = 0;
 646     struct sockaddr_in addr;
 647
 648     if (!bgp_port)
 649     {
 650         struct servent *serv;
 651         if (!(serv = getservbyname("bgp", "tcp")))
 652         {
 653             LOG(0, 0, 0, 0, "Can't get bgp service (%s)\n", strerror(errno));
 654             return 0;
 655         }
 656
 657         bgp_port = serv->s_port;
 658     }
 659
 660     if ((peer->sock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0)
 661     {
 662         LOG(0, 0, 0, 0, "Can't create a socket for BGP peer %s (%s)\n",
 663             peer->name, strerror(errno));
 664
 665         peer->state = peer->next_state = Disabled;
 666         return 0;
 667     }
 668
 669     /* set to non-blocking */
 670     fcntl(peer->sock, F_SETFL, fcntl(peer->sock, F_GETFL, 0) | O_NONBLOCK);
 671
 672     /* try connect */
 673     memset(&addr, 0, sizeof(addr));
 674     addr.sin_family = AF_INET;
 675     addr.sin_port = bgp_port;
 676     addr.sin_addr.s_addr = peer->addr;
 677
 678     while (connect(peer->sock, (struct sockaddr *) &addr, sizeof(addr)) == -1)
 679     {
 680         if (errno == EINTR) /* SIGALARM handler */
 681             continue;
 682
 683         if (errno != EINPROGRESS)
 684         {
 685             LOG(1, 0, 0, 0, "Can't connect to BGP peer %s (%s)\n",
 686                 inet_ntoa(addr.sin_addr), strerror(errno));
 687
 688             bgp_set_retry(peer);
 689             return 0;
 690         }
 691
 692         peer->state = Connect;
 693         peer->state_time = time_now;
 694
 695         LOG(4, 0, 0, 0, "BGP peer %s: state Connect\n", peer->name);
 696         return 1;
 697     }
 698
 699     peer->state = Active;
 700     peer->state_time = time_now;
 701     peer->retry_time = peer->retry_count = 0;
 702
 703     LOG(4, 0, 0, 0, "BGP peer %s: state Active\n", inet_ntoa(addr.sin_addr));
 704
 705     return bgp_send_open(peer);
 706 }
 707
 708 /* complete partial connection (state = Connect) */
 709 static int bgp_handle_connect(struct bgp_peer *peer)
 710 {
 711     int err = 0;
 712     int len = sizeof(int);
 713     getsockopt(peer->sock, SOL_SOCKET, SO_ERROR, &err, &len);
 714     if (err)
 715     {
 716         LOG(1, 0, 0, 0, "Can't connect to BGP peer %s (%s)\n", peer->name,
 717             strerror(err));
 718
 719         bgp_set_retry(peer);
 720         return 0;
 721     }
 722
 723     peer->state = Active;
 724     peer->state_time = time_now;
 725
 726     LOG(4, 0, 0, 0, "BGP peer %s: state Active\n", peer->name);
 727
 728     return bgp_send_open(peer);
 729 }
 730
 731 /* initiate a write */
 732 static int bgp_write(struct bgp_peer *peer)
 733 {
 734     int len = htons(peer->outbuf->packet.header.len);
 735     int r;
 736
 737     while ((r = write(peer->sock, &peer->outbuf->packet + peer->outbuf->done,
 738         len - peer->outbuf->done)) == -1)
 739     {
 740         if (errno == EINTR)
 741             continue;
 742
 743         if (errno == EAGAIN)
 744             return 1;
 745
 746         if (errno == EPIPE)
 747             LOG(1, 0, 0, 0, "Connection to BGP peer %s closed\n", peer->name);
 748         else
 749             LOG(1, 0, 0, 0, "Can't write to BGP peer %s (%s)\n", peer->name,
 750                 strerror(errno));
 751
 752         bgp_set_retry(peer);
 753         return 0;
 754     }
 755
 756     if (r < len)
 757     {
 758         peer->outbuf->done += r;
 759         return 1;
 760     }
 761
 762     LOG(4, 0, 0, 0, "Sent %s to BGP peer %s\n",
 763         bgp_msg_type_str(peer->outbuf->packet.header.type), peer->name);
 764
 765     peer->outbuf->packet.header.len = 0;
 766     peer->outbuf->done = 0;
 767
 768     if (peer->state == Established)
 769         peer->keepalive_time = time_now + BGP_KEEPALIVE_TIME;
 770
 771     if (peer->state != peer->next_state)
 772     {
 773         if (peer->next_state == Disabled || peer->next_state == Idle)
 774         {
 775             bgp_clear(peer);
 776             return 0;
 777         }
 778
 779         peer->state = peer->next_state;
 780         peer->state_time = time_now;
 781
 782         LOG(4, 0, 0, 0, "BGP peer %s: state %s\n", peer->name,
 783             bgp_state_str(peer->state));
 784     }
 785
 786     return 1;
 787 }
 788
 789 /* initiate a read */
 790 static int bgp_read(struct bgp_peer *peer)
 791 {
 792     int r;
 793
 794     while ((r = read(peer->sock, &peer->inbuf->packet + peer->inbuf->done,
 795         BGP_MAX_PACKET_SIZE - peer->inbuf->done)) < 1)
 796     {
 797         if (!r)
 798         {
 799             LOG(1, 0, 0, 0, "Connection to BGP peer %s closed\n", peer->name);
 800         }
 801         else
 802         {
 803             if (errno == EINTR)
 804                 continue;
 805
 806             if (errno == EAGAIN)
 807                 return 1;
 808
 809             LOG(1, 0, 0, 0, "Can't read from BGP peer %s (%s)\n", peer->name,
 810                 strerror(errno));
 811         }
 812
 813         bgp_set_retry(peer);
 814         return 0;
 815     }
 816
 817     peer->inbuf->done += r;
 818     return 1;
 819 }
 820
 821 /* process buffered packets */
 822 static int bgp_handle_input(struct bgp_peer *peer)
 823 {
 824     struct bgp_packet *p = &peer->inbuf->packet;
 825     int len = ntohs(p->header.len);
 826
 827     if (len > BGP_MAX_PACKET_SIZE)
 828     {
 829         LOG(1, 0, 0, 0, "Bad header length from BGP %s\n", peer->name);
 830         bgp_send_notification(peer, BGP_ERR_HEADER, BGP_ERR_HDR_BAD_LEN);
 831         return 0;
 832     }
 833
 834     if (peer->inbuf->done < len)
 835         return 0;
 836
 837     LOG(4, 0, 0, 0, "Received %s from BGP peer %s\n",
 838         bgp_msg_type_str(p->header.type), peer->name);
 839
 840     switch (p->header.type)
 841     {
 842     case BGP_MSG_OPEN:
 843         {
 844             struct bgp_data_open data;
 845             int i;
 846
 847             for (i = 0; i < sizeof(p->header.marker); i++)
 848             {
 849                 if ((unsigned char) p->header.marker[i] != 0xff)
 850                 {
 851                     LOG(1, 0, 0, 0, "Invalid marker from BGP peer %s\n",
 852                         peer->name);
 853
 854                     bgp_send_notification(peer, BGP_ERR_HEADER,
 855                         BGP_ERR_HDR_NOT_SYNC);
 856
 857                     return 0;
 858                 }
 859             }
 860
 861             if (peer->state != OpenSent)
 862             {
 863                 LOG(1, 0, 0, 0, "OPEN from BGP peer %s in %s state\n",
 864                     peer->name, bgp_state_str(peer->state));
 865
 866                 bgp_send_notification(peer, BGP_ERR_FSM, 0);
 867                 return 0;
 868             }
 869
 870             memcpy(&data, p->data, len - sizeof(p->header));
 871
 872             if (data.version != BGP_VERSION)
 873             {
 874                 LOG(1, 0, 0, 0, "Bad version (%d) sent by BGP peer %s\n",
 875                     (int) data.version, peer->name);
 876
 877                 bgp_send_notification(peer, BGP_ERR_OPEN, BGP_ERR_OPN_VERSION);
 878                 return 0;
 879             }
 880
 881             if (ntohs(data.as) != peer->as)
 882             {
 883                 LOG(1, 0, 0, 0, "Bad AS sent by BGP peer %s (got %d, "
 884                     "expected %d)\n", peer->name, (int) htons(data.as),
 885                     (int) peer->as);
 886
 887                 bgp_send_notification(peer, BGP_ERR_OPEN, BGP_ERR_OPN_BAD_AS);
 888                 return 0;
 889             }
 890
 891             if ((peer->hold = ntohs(data.hold_time)) < 10)
 892             {
 893                 LOG(1, 0, 0, 0, "Bad hold time (%d) from BGP peer %s\n",
 894                     peer->hold, peer->name);
 895
 896                 bgp_send_notification(peer, BGP_ERR_OPEN, BGP_ERR_OPN_HOLD_TIME);
 897                 return 0;
 898             }
 899
 900             /* next transition requires an exchange of keepalives */
 901             bgp_send_keepalive(peer);
 902
 903             /* FIXME: may need to check for optional params */
 904         }
 905
 906         break;
 907
 908     case BGP_MSG_KEEPALIVE:
 909         if (peer->state == OpenConfirm)
 910         {
 911             peer->state = peer->next_state = Established;
 912             peer->state_time = time_now;
 913             peer->keepalive_time = time_now + BGP_KEEPALIVE_TIME;
 914             peer->update_routes = 1;
 915             peer->retry_count = 0;
 916             peer->retry_time = 0;
 917
 918             LOG(4, 0, 0, 0, "BGP peer %s: state Established\n", peer->name);
 919         }
 920
 921         break;
 922
 923     case BGP_MSG_NOTIFICATION:
 924         if (len > sizeof(p->header))
 925         {
 926             struct bgp_data_notification *notification =
 927                 (struct bgp_data_notification *) p->data;
 928
 929             if (notification->error_code == BGP_ERR_CEASE)
 930             {
 931                 LOG(4, 0, 0, 0, "BGP peer %s sent CEASE\n", peer->name);
 932                 bgp_halt(peer);
 933                 return 0;
 934             }
 935
 936             /* FIXME: should handle more notifications */
 937             LOG(4, 0, 0, 0, "BGP peer %s sent unhandled NOTIFICATION %d\n",
 938                 peer->name, (int) notification->error_code);
 939         }
 940
 941         break;
 942     }
 943
 944     /* reset timer */
 945     peer->expire_time = time_now + peer->hold;
 946
 947     /* see if there's another message in the same packet/buffer */
 948     if (peer->inbuf->done > len)
 949     {
 950         peer->inbuf->done -= len;
 951         memmove(p, (char *) p + len, peer->inbuf->done);
 952     }
 953     else
 954     {
 955         peer->inbuf->packet.header.len = 0;
 956         peer->inbuf->done = 0;
 957     }
 958
 959     return peer->inbuf->done;
 960 }
 961
 962 /* send/buffer OPEN message */
 963 static int bgp_send_open(struct bgp_peer *peer)
 964 {
 965     struct bgp_data_open data;
 966     u16 len = sizeof(peer->outbuf->packet.header);
 967
 968     memset(peer->outbuf->packet.header.marker, 0xff,
 969         sizeof(peer->outbuf->packet.header.marker));
 970
 971     peer->outbuf->packet.header.type = BGP_MSG_OPEN;
 972
 973     data.version = BGP_VERSION;
 974     data.as = htons(our_as);
 975     data.hold_time = htons(BGP_HOLD_TIME);
 976     data.identifier = my_address;
 977     data.opt_len = 0;
 978
 979     memcpy(peer->outbuf->packet.data, &data, BGP_DATA_OPEN_SIZE);
 980     len += BGP_DATA_OPEN_SIZE;
 981
 982     peer->outbuf->packet.header.len = htons(len);
 983     peer->outbuf->done = 0;
 984     peer->next_state = OpenSent;
 985
 986     return bgp_write(peer);
 987 }
 988
 989 /* send/buffer KEEPALIVE message */
 990 static int bgp_send_keepalive(struct bgp_peer *peer)
 991 {
 992     memset(peer->outbuf->packet.header.marker, 0xff,
 993         sizeof(peer->outbuf->packet.header.marker));
 994
 995     peer->outbuf->packet.header.type = BGP_MSG_KEEPALIVE;
 996     peer->outbuf->packet.header.len =
 997         htons(sizeof(peer->outbuf->packet.header));
 998
 999     peer->outbuf->done = 0;
1000     peer->next_state = (peer->state == OpenSent) ? OpenConfirm : peer->state;
1001
1002     return bgp_write(peer);
1003 }
1004
1005 /* send/buffer UPDATE message */
1006 static int bgp_send_update(struct bgp_peer *peer)
1007 {
1008     u16 unf_len = 0;
1009     u16 attr_len;
1010     u16 len = sizeof(peer->outbuf->packet.header);
1011     struct bgp_route_list *have = peer->routes;
1012     struct bgp_route_list *want = peer->routing ? bgp_routes : 0;
1013     struct bgp_route_list *e = 0;
1014     struct bgp_route_list *add = 0;
1015     int s;
1016
1017     char *data = (char *) &peer->outbuf->packet.data;
1018
1019     /* need leave room for attr_len, bgp_path_attrs and one prefix */
1020     char *max = (char *) &peer->outbuf->packet.data
1021         + sizeof(peer->outbuf->packet.data)
1022         - sizeof(attr_len) - peer->path_attr_len - sizeof(struct bgp_ip_prefix);
1023
1024     /* skip over unf_len */
1025     data += sizeof(unf_len);
1026     len += sizeof(unf_len);
1027
1028     memset(peer->outbuf->packet.header.marker, 0xff,
1029         sizeof(peer->outbuf->packet.header.marker));
1030
1031     peer->outbuf->packet.header.type = BGP_MSG_UPDATE;
1032
1033     peer->update_routes = 0; /* tentatively clear */
1034
1035     /* find differences */
1036     while ((have || want) && data < (max - sizeof(struct bgp_ip_prefix)))
1037     {
1038         if (have)
1039             s = want
1040                 ? memcmp(&have->dest, &want->dest, sizeof(have->dest))
1041                 : -1;
1042         else
1043             s = 1;
1044
1045         if (s < 0) /* found one to delete */
1046         {
1047             struct bgp_route_list *tmp = have;
1048             have = have->next;
1049
1050             s = BGP_IP_PREFIX_SIZE(tmp->dest);
1051             memcpy(data, &tmp->dest, s);
1052             data += s;
1053             unf_len += s;
1054             len += s;
1055
1056             LOG(5, 0, 0, 0, "Withdrawing route %s/%d from BGP peer %s\n",
1057                 inet_toa(tmp->dest.prefix), tmp->dest.len, peer->name);
1058
1059             free(tmp);
1060
1061             if (e)
1062                 e->next = have;
1063             else
1064                 peer->routes = have;
1065         }
1066         else
1067         {
1068             if (!s) /* same */
1069             {
1070                 e = have; /* stash the last found to relink above */
1071                 have = have->next;
1072                 want = want->next;
1073             }
1074             else if (s > 0) /* addition reqd. */
1075             {
1076                 if (add)
1077                 {
1078                     peer->update_routes = 1; /* only one add per packet */
1079                     if (!have)
1080                         break;
1081                 }
1082                 else
1083                     add = want;
1084
1085                 if (want)
1086                     want = want->next;
1087             }
1088         }
1089     }
1090
1091     if (have || want)
1092         peer->update_routes = 1; /* more to do */
1093
1094     /* anything changed? */
1095     if (!(unf_len || add))
1096         return 1;
1097
1098     /* go back and insert unf_len */
1099     unf_len = htons(unf_len);
1100     memcpy(&peer->outbuf->packet.data, &unf_len, sizeof(unf_len));
1101
1102     if (add)
1103     {
1104         if (!(e = malloc(sizeof(*e))))
1105         {
1106             LOG(0, 0, 0, 0, "Can't allocate route for %s/%d (%s)\n",
1107                 inet_toa(add->dest.prefix), add->dest.len, strerror(errno));
1108
1109             return 0;
1110         }
1111
1112         memcpy(e, add, sizeof(*e));
1113         e->next = 0;
1114         peer->routes = bgp_insert_route(peer->routes, e);
1115
1116         attr_len = htons(peer->path_attr_len);
1117         memcpy(data, &attr_len, sizeof(attr_len));
1118         data += sizeof(attr_len);
1119         len += sizeof(attr_len);
1120
1121         memcpy(data, peer->path_attrs, peer->path_attr_len);
1122         data += peer->path_attr_len;
1123         len += peer->path_attr_len;
1124
1125         s = BGP_IP_PREFIX_SIZE(add->dest);
1126         memcpy(data, &add->dest, s);
1127         data += s;
1128         len += s;
1129
1130         LOG(5, 0, 0, 0, "Advertising route %s/%d to BGP peer %s\n",
1131             inet_toa(add->dest.prefix), add->dest.len, peer->name);
1132     }
1133     else
1134     {
1135         attr_len = 0;
1136         memcpy(data, &attr_len, sizeof(attr_len));
1137         data += sizeof(attr_len);
1138         len += sizeof(attr_len);
1139     }
1140
1141     peer->outbuf->packet.header.len = htons(len);
1142     peer->outbuf->done = 0;
1143
1144     return bgp_write(peer);
1145 }
1146
1147 /* send/buffer NOTIFICATION message */
1148 static int bgp_send_notification(struct bgp_peer *peer, u8 code, u8 subcode)
1149 {
1150     struct bgp_data_notification data;
1151     u16 len = 0;
1152
1153     data.error_code = code;
1154     len += sizeof(data.error_code);
1155
1156     data.error_subcode = subcode;
1157     len += sizeof(data.error_code);
1158
1159     memset(peer->outbuf->packet.header.marker, 0xff,
1160         sizeof(peer->outbuf->packet.header.marker));
1161
1162     peer->outbuf->packet.header.type = BGP_MSG_NOTIFICATION;
1163     peer->outbuf->packet.header.len =
1164         htons(sizeof(peer->outbuf->packet.header) + len);
1165
1166     memcpy(peer->outbuf->packet.data, &data, len);
1167
1168     peer->outbuf->done = 0;
1169     peer->next_state = code == BGP_ERR_CEASE ? Disabled : Idle;
1170
1171     /* we're dying; ignore any pending input */
1172     peer->inbuf->packet.header.len = 0;
1173     peer->inbuf->done = 0;
1174
1175     return bgp_write(peer);
1176 }
1177
1178 /* CLI stuff */
1179
1180 #include <libcli.h>
1181
1182 int cmd_show_bgp(struct cli_def *cli, char *command, char **argv, int argc)
1183 {
1184     int i;
1185     int hdr = 0;
1186     char *addr;
1187
1188     if (!bgp_configured)
1189         return CLI_OK;
1190
1191     if (CLI_HELP_REQUESTED)
1192         return cli_arg_help(cli, 1,
1193             "A.B.C.D", "BGP peer address",
1194             "NAME",    "BGP peer name",
1195             NULL);
1196
1197     cli_print(cli, "BGPv%d router identifier %s, local AS number %d, "
1198         "hold time %ds", BGP_VERSION, inet_toa(my_address), (int) our_as,
1199         BGP_HOLD_TIME);
1200
1201     time(&time_now);
1202
1203     for (i = 0; i < BGP_NUM_PEERS; i++)
1204     {
1205         if (!*bgp_peers[i].name)
1206             continue;
1207
1208         addr = inet_toa(bgp_peers[i].addr);
1209         if (argc && strcmp(addr, argv[0]) &&
1210           strncmp(bgp_peers[i].name, argv[0], strlen(argv[0])))
1211             continue;
1212
1213         if (!hdr++)
1214         {
1215             cli_print(cli, "");
1216             cli_print(cli, "Peer                  AS         Address "
1217                 "State       Retries Retry in Route Pend");
1218             cli_print(cli, "------------------ ----- --------------- "
1219                 "----------- ------- -------- ----- ----");
1220         }
1221
1222         cli_print(cli, "%-18.18s %5d %15s %-11s %7d %7ds %5s %4s",
1223             bgp_peers[i].name,
1224             bgp_peers[i].as,
1225             addr,
1226             bgp_state_str(bgp_peers[i].state),
1227             bgp_peers[i].retry_count,
1228             bgp_peers[i].retry_time ? bgp_peers[i].retry_time - time_now : 0,
1229             bgp_peers[i].routing ? "yes" : "no",
1230             bgp_peers[i].update_routes ? "yes" : "no");
1231     }
1232
1233     return CLI_OK;
1234 }
1235
1236 int cmd_suspend_bgp(struct cli_def *cli, char *command, char **argv, int argc)
1237 {
1238     int i;
1239     char *addr;
1240
1241     if (!bgp_configured)
1242         return CLI_OK;
1243
1244     if (CLI_HELP_REQUESTED)
1245         return cli_arg_help(cli, 1,
1246             "A.B.C.D", "BGP peer address",
1247             "NAME",    "BGP peer name",
1248             NULL);
1249
1250     for (i = 0; i < BGP_NUM_PEERS; i++)
1251     {
1252         if (bgp_peers[i].state != Established)
1253             continue;
1254
1255         if (!bgp_peers[i].routing)
1256             continue;
1257
1258         addr = inet_toa(bgp_peers[i].addr);
1259         if (argc && strcmp(addr, argv[0]) && strcmp(bgp_peers[i].name, argv[0]))
1260             continue;
1261
1262         bgp_peers[i].cli_flag = BGP_CLI_SUSPEND;
1263         cli_print(cli, "Suspending peer %s", bgp_peers[i].name);
1264     }
1265
1266     return CLI_OK;
1267 }
1268
1269 int cmd_no_suspend_bgp(struct cli_def *cli, char *command, char **argv, int argc)
1270 {
1271     int i;
1272     char *addr;
1273
1274     if (!bgp_configured)
1275         return CLI_OK;
1276
1277     if (CLI_HELP_REQUESTED)
1278         return cli_arg_help(cli, 1,
1279             "A.B.C.D", "BGP peer address",
1280             "NAME",    "BGP peer name",
1281             NULL);
1282
1283     for (i = 0; i < BGP_NUM_PEERS; i++)
1284     {
1285         if (bgp_peers[i].state != Established)
1286             continue;
1287
1288         if (bgp_peers[i].routing)
1289             continue;
1290
1291         addr = inet_toa(bgp_peers[i].addr);
1292         if (argc && strcmp(addr, argv[0]) &&
1293           strncmp(bgp_peers[i].name, argv[0], strlen(argv[0])))
1294             continue;
1295
1296         bgp_peers[i].cli_flag = BGP_CLI_ENABLE;
1297         cli_print(cli, "Un-suspending peer %s", bgp_peers[i].name);
1298     }
1299
1300     return CLI_OK;
1301 }
1302
1303 int cmd_restart_bgp(struct cli_def *cli, char *command, char **argv, int argc)
1304 {
1305     int i;
1306     char *addr;
1307
1308     if (!bgp_configured)
1309         return CLI_OK;
1310
1311     if (CLI_HELP_REQUESTED)
1312         return cli_arg_help(cli, 1,
1313             "A.B.C.D", "BGP peer address",
1314             "NAME",    "BGP peer name",
1315             NULL);
1316
1317     for (i = 0; i < BGP_NUM_PEERS; i++)
1318     {
1319         if (!*bgp_peers[i].name)
1320             continue;
1321
1322         addr = inet_toa(bgp_peers[i].addr);
1323         if (argc && strcmp(addr, argv[0]) &&
1324           strncmp(bgp_peers[i].name, argv[0], strlen(argv[0])))
1325             continue;
1326
1327         bgp_peers[i].cli_flag = BGP_CLI_RESTART;
1328         cli_print(cli, "Restarting peer %s", bgp_peers[i].name);
1329     }
1330
1331     return CLI_OK;
1332 }