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 1.12 2005/09/02 23:39:36 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 struct bgp_route_list *bgp_insert_route(struct bgp_route_list *head,
  33     struct bgp_route_list *new);
  34
  35 static void bgp_free_routes(struct bgp_route_list *routes);
  36 static char const *bgp_msg_type_str(uint8_t type);
  37 static int bgp_connect(struct bgp_peer *peer);
  38 static int bgp_handle_connect(struct bgp_peer *peer);
  39 static int bgp_write(struct bgp_peer *peer);
  40 static int bgp_read(struct bgp_peer *peer);
  41 static int bgp_handle_input(struct bgp_peer *peer);
  42 static int bgp_send_open(struct bgp_peer *peer);
  43 static int bgp_send_keepalive(struct bgp_peer *peer);
  44 static int bgp_send_update(struct bgp_peer *peer);
  45 static int bgp_send_notification(struct bgp_peer *peer, uint8_t code,
  46     uint8_t subcode);
  47
  48 static uint16_t our_as;
  49 static struct bgp_route_list *bgp_routes = 0;
  50
  51 int bgp_configured = 0;
  52 struct bgp_peer *bgp_peers = 0;
  53
  54 /* prepare peer structure, globals */
  55 int bgp_setup(int as)
  56 {
  57     int i;
  58     struct bgp_peer *peer;
  59
  60     for (i = 0; i < BGP_NUM_PEERS; i++)
  61     {
  62         peer = &bgp_peers[i];
  63         memset(peer, 0, sizeof(*peer));
  64
  65         peer->addr = INADDR_NONE;
  66         peer->sock = -1;
  67         peer->state = peer->next_state = Disabled;
  68
  69         if (!((peer->outbuf = malloc(sizeof(*peer->outbuf)))
  70             && (peer->inbuf = malloc(sizeof(*peer->inbuf)))))
  71         {
  72             LOG(0, 0, 0, "Can't allocate buffers for bgp peer (%s)\n",
  73                 strerror(errno));
  74
  75             return 0;
  76         }
  77
  78         peer->edata.type = FD_TYPE_BGP;
  79         peer->edata.index = i;
  80         peer->events = 0;
  81     }
  82
  83     if (as < 1)
  84         as = 0;
  85
  86     if ((our_as = as))
  87         return 0;
  88
  89     bgp_routes = 0;
  90     bgp_configured = 0; /* set by bgp_start */
  91
  92     return 1;
  93 }
  94
  95 /* start connection with a peer */
  96 int bgp_start(struct bgp_peer *peer, char *name, int as, int keepalive,
  97     int hold, int enable)
  98 {
  99     struct hostent *h;
 100     int ibgp;
 101     int i;
 102     struct bgp_path_attr a;
 103     char path_attrs[64];
 104     char *p = path_attrs;
 105     in_addr_t ip;
 106     uint32_t metric = htonl(BGP_METRIC);
 107     uint32_t no_export = htonl(BGP_COMMUNITY_NO_EXPORT);
 108
 109     if (!our_as)
 110         return 0;
 111
 112     if (peer->state != Disabled)
 113         bgp_halt(peer);
 114
 115     snprintf(peer->name, sizeof(peer->name), "%s", name);
 116
 117     if (!(h = gethostbyname(name)) || h->h_addrtype != AF_INET)
 118     {
 119         LOG(0, 0, 0, "Can't get address for BGP peer %s (%s)\n",
 120             name, h ? "no address" : hstrerror(h_errno));
 121
 122         return 0;
 123     }
 124
 125     memcpy(&peer->addr, h->h_addr, sizeof(peer->addr));
 126     peer->as = as > 0 ? as : our_as;
 127     ibgp = peer->as == our_as;
 128
 129     /* set initial timer values */
 130     peer->init_keepalive = keepalive == -1 ? BGP_KEEPALIVE_TIME : keepalive;
 131     peer->init_hold = hold == -1 ? BGP_HOLD_TIME : hold;
 132
 133     if (peer->init_hold < 3)
 134         peer->init_hold = 3;
 135
 136     if (peer->init_keepalive * 3 > peer->init_hold)
 137         peer->init_keepalive = peer->init_hold / 3;
 138
 139     /* clear buffers, go to Idle state */
 140     peer->next_state = Idle;
 141     bgp_clear(peer);
 142
 143     /* set initial routing state */
 144     peer->routing = enable;
 145
 146     /* all our routes use the same attributes, so prepare it in advance */
 147     if (peer->path_attrs)
 148         free(peer->path_attrs);
 149
 150     peer->path_attr_len = 0;
 151
 152     /* ORIGIN */
 153     a.flags = BGP_PATH_ATTR_FLAG_TRANS;
 154     a.code = BGP_PATH_ATTR_CODE_ORIGIN;
 155     a.data.s.len = 1;
 156     a.data.s.value[0] = BGP_PATH_ATTR_CODE_ORIGIN_IGP;
 157
 158 #define ADD_ATTRIBUTE()         do { \
 159     i = BGP_PATH_ATTR_SIZE(a);  \
 160     memcpy(p, &a, i);           \
 161     p += i;                     \
 162     peer->path_attr_len += i;   } while (0)
 163
 164     ADD_ATTRIBUTE();
 165
 166     /* AS_PATH */
 167     a.flags = BGP_PATH_ATTR_FLAG_TRANS;
 168     a.code = BGP_PATH_ATTR_CODE_AS_PATH;
 169     if (ibgp)
 170     {
 171         /* empty path */
 172         a.data.s.len = 0;
 173     }
 174     else
 175     {
 176         /* just our AS */
 177         struct {
 178             uint8_t type;
 179             uint8_t len;
 180             uint16_t value;
 181         } as_path = {
 182             BGP_PATH_ATTR_CODE_AS_PATH_AS_SEQUENCE,
 183             1,
 184             htons(our_as),
 185         };
 186
 187         a.data.s.len = sizeof(as_path);
 188         memcpy(&a.data.s.value, &as_path, sizeof(as_path));
 189     }
 190
 191     ADD_ATTRIBUTE();
 192
 193     /* NEXT_HOP */
 194     a.flags = BGP_PATH_ATTR_FLAG_TRANS;
 195     a.code = BGP_PATH_ATTR_CODE_NEXT_HOP;
 196     ip = my_address; /* we're it */
 197     a.data.s.len = sizeof(ip);
 198     memcpy(a.data.s.value, &ip, sizeof(ip));
 199
 200     ADD_ATTRIBUTE();
 201
 202     /* MULTI_EXIT_DISC */
 203     a.flags = BGP_PATH_ATTR_FLAG_OPTIONAL;
 204     a.code = BGP_PATH_ATTR_CODE_MULTI_EXIT_DISC;
 205     a.data.s.len = sizeof(metric);
 206     memcpy(a.data.s.value, &metric, sizeof(metric));
 207
 208     ADD_ATTRIBUTE();
 209
 210     if (ibgp)
 211     {
 212         uint32_t local_pref = htonl(BGP_LOCAL_PREF);
 213
 214         /* LOCAL_PREF */
 215         a.flags = BGP_PATH_ATTR_FLAG_TRANS;
 216         a.code = BGP_PATH_ATTR_CODE_LOCAL_PREF;
 217         a.data.s.len = sizeof(local_pref);
 218         memcpy(a.data.s.value, &local_pref, sizeof(local_pref));
 219
 220         ADD_ATTRIBUTE();
 221     }
 222
 223     /* COMMUNITIES */
 224     a.flags = BGP_PATH_ATTR_FLAG_OPTIONAL | BGP_PATH_ATTR_FLAG_TRANS;
 225     a.code = BGP_PATH_ATTR_CODE_COMMUNITIES;
 226     a.data.s.len = sizeof(no_export);
 227     memcpy(a.data.s.value, &no_export, sizeof(no_export));
 228
 229     ADD_ATTRIBUTE();
 230
 231     if (!(peer->path_attrs = malloc(peer->path_attr_len)))
 232     {
 233         LOG(0, 0, 0, "Can't allocate path_attrs for %s (%s)\n",
 234             name, strerror(errno));
 235
 236         return 0;
 237     }
 238
 239     memcpy(peer->path_attrs, path_attrs, peer->path_attr_len);
 240
 241     LOG(4, 0, 0, "Initiating BGP connection to %s (routing %s)\n",
 242         name, enable ? "enabled" : "suspended");
 243
 244     /* we have at least one peer configured */
 245     bgp_configured = 1;
 246
 247     /* connect */
 248     return bgp_connect(peer);
 249 }
 250
 251 /* clear counters, timers, routes and buffers; close socket; move to
 252    next_state, which may be Disabled or Idle */
 253 static void bgp_clear(struct bgp_peer *peer)
 254 {
 255     if (peer->sock != -1)
 256     {
 257         close(peer->sock);
 258         peer->sock = -1;
 259     }
 260
 261     peer->keepalive_time = 0;
 262     peer->expire_time = 0;
 263
 264     peer->keepalive = peer->init_keepalive;
 265     peer->hold = peer->init_hold;
 266
 267     bgp_free_routes(peer->routes);
 268     peer->routes = 0;
 269
 270     peer->outbuf->packet.header.len = 0;
 271     peer->outbuf->done = 0;
 272     peer->inbuf->packet.header.len = 0;
 273     peer->inbuf->done = 0;
 274
 275     peer->cli_flag = 0;
 276     peer->events = 0;
 277
 278     if (peer->state != peer->next_state)
 279     {
 280         peer->state = peer->next_state;
 281         peer->state_time = time_now;
 282
 283         LOG(4, 0, 0, "BGP peer %s: state %s\n", peer->name,
 284             bgp_state_str(peer->next_state));
 285     }
 286 }
 287
 288 /* initiate a clean shutdown */
 289 void bgp_stop(struct bgp_peer *peer)
 290 {
 291     LOG(4, 0, 0, "Terminating BGP connection to %s\n", peer->name);
 292     bgp_send_notification(peer, BGP_ERR_CEASE, 0);
 293 }
 294
 295 /* drop connection (if any) and set state to Disabled */
 296 void bgp_halt(struct bgp_peer *peer)
 297 {
 298     LOG(4, 0, 0, "Aborting BGP connection to %s\n", peer->name);
 299     peer->next_state = Disabled;
 300     bgp_clear(peer);
 301 }
 302
 303 /* drop connection (if any) and set to Idle for connection retry */
 304 int bgp_restart(struct bgp_peer *peer)
 305 {
 306     peer->next_state = Idle;
 307     bgp_clear(peer);
 308
 309     /* restart now */
 310     peer->retry_time = time_now;
 311     peer->retry_count = 0;
 312
 313     /* connect */
 314     return bgp_connect(peer);
 315 }
 316
 317 static void bgp_set_retry(struct bgp_peer *peer)
 318 {
 319     if (peer->retry_count++ < BGP_MAX_RETRY)
 320     {
 321         peer->retry_time = time_now + (BGP_RETRY_BACKOFF * peer->retry_count);
 322         peer->next_state = Idle;
 323         bgp_clear(peer);
 324     }
 325     else
 326         bgp_halt(peer); /* give up */
 327 }
 328
 329 /* insert route into list; sorted */
 330 static struct bgp_route_list *bgp_insert_route(struct bgp_route_list *head,
 331     struct bgp_route_list *new)
 332 {
 333     struct bgp_route_list *p = head;
 334     struct bgp_route_list *e = 0;
 335
 336     while (p && memcmp(&p->dest, &new->dest, sizeof(p->dest)) < 0)
 337     {
 338         e = p;
 339         p = p->next;
 340     }
 341
 342     if (e)
 343     {
 344         new->next = e->next;
 345         e->next = new;
 346     }
 347     else
 348     {
 349         new->next = head;
 350         head = new;
 351     }
 352
 353     return head;
 354 }
 355
 356 /* add route to list for peers */
 357 /*
 358  * Note:  this doesn't do route aggregation, nor drop routes if a less
 359  * specific match already exists (partly because I'm lazy, but also so
 360  * that if that route is later deleted we don't have to be concerned
 361  * about adding back the more specific one).
 362  */
 363 int bgp_add_route(in_addr_t ip, int prefixlen)
 364 {
 365     struct bgp_route_list *r = bgp_routes;
 366     struct bgp_route_list add;
 367     int i;
 368
 369     add.dest.prefix = ip;
 370     add.dest.len = prefixlen;
 371     add.next = 0;
 372
 373     /* check for duplicate */
 374     while (r)
 375     {
 376         i = memcmp(&r->dest, &add.dest, sizeof(r->dest));
 377         if (!i)
 378             return 1; /* already covered */
 379
 380         if (i > 0)
 381             break;
 382
 383         r = r->next;
 384     }
 385
 386     /* insert into route list; sorted */
 387     if (!(r = malloc(sizeof(*r))))
 388     {
 389         LOG(0, 0, 0, "Can't allocate route for %s/%d (%s)\n",
 390             fmtaddr(add.dest.prefix, 0), add.dest.len, strerror(errno));
 391
 392         return 0;
 393     }
 394
 395     memcpy(r, &add, sizeof(*r));
 396     bgp_routes = bgp_insert_route(bgp_routes, r);
 397
 398     /* flag established peers for update */
 399     for (i = 0; i < BGP_NUM_PEERS; i++)
 400         if (bgp_peers[i].state == Established)
 401             bgp_peers[i].update_routes = 1;
 402
 403     LOG(4, 0, 0, "Registered BGP route %s/%d\n",
 404         fmtaddr(add.dest.prefix, 0), add.dest.len);
 405
 406     return 1;
 407 }
 408
 409 /* remove route from list for peers */
 410 int bgp_del_route(in_addr_t ip, int prefixlen)
 411 {
 412     struct bgp_route_list *r = bgp_routes;
 413     struct bgp_route_list *e = 0;
 414     struct bgp_route_list del;
 415     int i;
 416
 417     del.dest.prefix = ip;
 418     del.dest.len = prefixlen;
 419     del.next = 0;
 420
 421     /* find entry in routes list and remove */
 422     while (r)
 423     {
 424         i = memcmp(&r->dest, &del.dest, sizeof(r->dest));
 425         if (!i)
 426         {
 427             if (e)
 428                 e->next = r->next;
 429             else
 430                 bgp_routes = r->next;
 431
 432             free(r);
 433             break;
 434         }
 435
 436         e = r;
 437
 438         if (i > 0)
 439             r = 0; /* stop */
 440         else
 441             r = r->next;
 442     }
 443
 444     /* not found */
 445     if (!r)
 446         return 1;
 447
 448     /* flag established peers for update */
 449     for (i = 0; i < BGP_NUM_PEERS; i++)
 450         if (bgp_peers[i].state == Established)
 451             bgp_peers[i].update_routes = 1;
 452
 453     LOG(4, 0, 0, "Removed BGP route %s/%d\n",
 454         fmtaddr(del.dest.prefix, 0), del.dest.len);
 455
 456     return 1;
 457 }
 458
 459 /* enable or disable routing */
 460 void bgp_enable_routing(int enable)
 461 {
 462     int i;
 463
 464     for (i = 0; i < BGP_NUM_PEERS; i++)
 465     {
 466         bgp_peers[i].routing = enable;
 467
 468         /* flag established peers for update */
 469         if (bgp_peers[i].state == Established)
 470             bgp_peers[i].update_routes = 1;
 471     }
 472
 473     LOG(4, 0, 0, "%s BGP routing\n", enable ? "Enabled" : "Suspended");
 474 }
 475
 476 #ifdef HAVE_EPOLL
 477 # include <sys/epoll.h>
 478 #else
 479 # include "fake_epoll.h"
 480 #endif
 481
 482 /* return a bitmask of the events required to poll this peer's fd */
 483 int bgp_set_poll()
 484 {
 485     int i;
 486
 487     if (!bgp_configured)
 488         return 0;
 489
 490     for (i = 0; i < BGP_NUM_PEERS; i++)
 491     {
 492         struct bgp_peer *peer = &bgp_peers[i];
 493         int events = 0;
 494
 495         if (peer->state == Disabled || peer->state == Idle)
 496             continue;
 497
 498         if (peer->inbuf->done < BGP_MAX_PACKET_SIZE)
 499             events |= EPOLLIN;
 500
 501         if (peer->state == Connect ||           /* connection in progress */
 502             peer->update_routes ||              /* routing updates */
 503             peer->outbuf->packet.header.len)    /* pending output */
 504             events |= EPOLLOUT;
 505
 506         if (peer->events != events)
 507         {
 508             struct epoll_event ev;
 509
 510             ev.events = peer->events = events;
 511             ev.data.ptr = &peer->edata;
 512             epoll_ctl(epollfd, EPOLL_CTL_MOD, peer->sock, &ev);
 513         }
 514     }
 515
 516     return 1;
 517 }
 518
 519 /* process bgp events/timers */
 520 int bgp_process(uint32_t events[])
 521 {
 522     int i;
 523
 524     if (!bgp_configured)
 525         return 0;
 526
 527     for (i = 0; i < BGP_NUM_PEERS; i++)
 528     {
 529         struct bgp_peer *peer = &bgp_peers[i];
 530
 531         if (*peer->name && peer->cli_flag == BGP_CLI_RESTART)
 532         {
 533             bgp_restart(peer);
 534             continue;
 535         }
 536
 537         if (peer->state == Disabled)
 538             continue;
 539
 540         if (peer->cli_flag)
 541         {
 542             switch (peer->cli_flag)
 543             {
 544             case BGP_CLI_SUSPEND:
 545                 if (peer->routing)
 546                 {
 547                     peer->routing = 0;
 548                     if (peer->state == Established)
 549                         peer->update_routes = 1;
 550                 }
 551
 552                 break;
 553
 554             case BGP_CLI_ENABLE:
 555                 if (!peer->routing)
 556                 {
 557                     peer->routing = 1;
 558                     if (peer->state == Established)
 559                         peer->update_routes = 1;
 560                 }
 561
 562                 break;
 563             }
 564
 565             peer->cli_flag = 0;
 566         }
 567
 568         /* handle empty/fill of buffers */
 569         if (events[i] & EPOLLOUT)
 570         {
 571             int r = 1;
 572             if (peer->state == Connect)
 573                 r = bgp_handle_connect(peer);
 574             else if (peer->outbuf->packet.header.len)
 575                 r = bgp_write(peer);
 576
 577             if (!r)
 578                 continue;
 579         }
 580
 581         if (events[i] & (EPOLLIN|EPOLLHUP))
 582         {
 583             if (!bgp_read(peer))
 584                 continue;
 585         }
 586
 587         /* process input buffer contents */
 588         while (peer->inbuf->done >= sizeof(peer->inbuf->packet.header)
 589             && !peer->outbuf->packet.header.len) /* may need to queue a response */
 590         {
 591             if (bgp_handle_input(peer) < 0)
 592                 continue;
 593         }
 594
 595         /* process pending updates */
 596         if (peer->update_routes
 597             && !peer->outbuf->packet.header.len) /* ditto */
 598         {
 599             if (!bgp_send_update(peer))
 600                 continue;
 601         }
 602
 603         /* process timers */
 604         if (peer->state == Established)
 605         {
 606             if (time_now > peer->expire_time)
 607             {
 608                 LOG(1, 0, 0, "No message from BGP peer %s in %ds\n",
 609                     peer->name, peer->hold);
 610
 611                 bgp_send_notification(peer, BGP_ERR_HOLD_TIMER_EXP, 0);
 612                 continue;
 613             }
 614
 615             if (time_now > peer->keepalive_time && !peer->outbuf->packet.header.len)
 616                 bgp_send_keepalive(peer);
 617         }
 618         else if (peer->state == Idle)
 619         {
 620             if (time_now > peer->retry_time)
 621                 bgp_connect(peer);
 622         }
 623         else if (time_now > peer->state_time + BGP_STATE_TIME)
 624         {
 625             LOG(1, 0, 0, "%s timer expired for BGP peer %s\n",
 626                 bgp_state_str(peer->state), peer->name);
 627
 628             bgp_restart(peer);
 629         }
 630     }
 631
 632     return 1;
 633 }
 634
 635 static void bgp_free_routes(struct bgp_route_list *routes)
 636 {
 637     struct bgp_route_list *tmp;
 638
 639     while ((tmp = routes))
 640     {
 641         routes = tmp->next;
 642         free(tmp);
 643     }
 644 }
 645
 646 char const *bgp_state_str(enum bgp_state state)
 647 {
 648     switch (state)
 649     {
 650     case Disabled:      return "Disabled";
 651     case Idle:          return "Idle";
 652     case Connect:       return "Connect";
 653     case Active:        return "Active";
 654     case OpenSent:      return "OpenSent";
 655     case OpenConfirm:   return "OpenConfirm";
 656     case Established:   return "Established";
 657     }
 658
 659     return "?";
 660 }
 661
 662 static char const *bgp_msg_type_str(uint8_t type)
 663 {
 664     switch (type)
 665     {
 666     case BGP_MSG_OPEN:          return "OPEN";
 667     case BGP_MSG_UPDATE:        return "UPDATE";
 668     case BGP_MSG_NOTIFICATION:  return "NOTIFICATION";
 669     case BGP_MSG_KEEPALIVE:     return "KEEPALIVE";
 670     }
 671
 672     return "?";
 673 }
 674
 675 /* attempt to connect to peer */
 676 static int bgp_connect(struct bgp_peer *peer)
 677 {
 678     static int bgp_port = 0;
 679     struct sockaddr_in addr;
 680     struct epoll_event ev;
 681
 682     if (!bgp_port)
 683     {
 684         struct servent *serv;
 685         if (!(serv = getservbyname("bgp", "tcp")))
 686         {
 687             LOG(0, 0, 0, "Can't get bgp service (%s)\n", strerror(errno));
 688             return 0;
 689         }
 690
 691         bgp_port = serv->s_port;
 692     }
 693
 694     if ((peer->sock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0)
 695     {
 696         LOG(0, 0, 0, "Can't create a socket for BGP peer %s (%s)\n",
 697             peer->name, strerror(errno));
 698
 699         peer->state = peer->next_state = Disabled;
 700         return 0;
 701     }
 702
 703     /* add to poll set */
 704     ev.events = peer->events = EPOLLOUT;
 705     ev.data.ptr = &peer->edata;
 706     epoll_ctl(epollfd, EPOLL_CTL_ADD, peer->sock, &ev);
 707
 708     /* set to non-blocking */
 709     fcntl(peer->sock, F_SETFL, fcntl(peer->sock, F_GETFL, 0) | O_NONBLOCK);
 710
 711     /* try connect */
 712     memset(&addr, 0, sizeof(addr));
 713     addr.sin_family = AF_INET;
 714     addr.sin_port = bgp_port;
 715     addr.sin_addr.s_addr = peer->addr;
 716
 717     while (connect(peer->sock, (struct sockaddr *) &addr, sizeof(addr)) == -1)
 718     {
 719         if (errno == EINTR) /* SIGALARM handler */
 720             continue;
 721
 722         if (errno != EINPROGRESS)
 723         {
 724             LOG(1, 0, 0, "Can't connect to BGP peer %s (%s)\n",
 725                 inet_ntoa(addr.sin_addr), strerror(errno));
 726
 727             bgp_set_retry(peer);
 728             return 0;
 729         }
 730
 731         peer->state = Connect;
 732         peer->state_time = time_now;
 733
 734         LOG(4, 0, 0, "BGP peer %s: state Connect\n", peer->name);
 735         return 1;
 736     }
 737
 738     peer->state = Active;
 739     peer->state_time = time_now;
 740     peer->retry_time = peer->retry_count = 0;
 741
 742     LOG(4, 0, 0, "BGP peer %s: state Active\n", inet_ntoa(addr.sin_addr));
 743
 744     return bgp_send_open(peer);
 745 }
 746
 747 /* complete partial connection (state = Connect) */
 748 static int bgp_handle_connect(struct bgp_peer *peer)
 749 {
 750     int err = 0;
 751     socklen_t len = sizeof(int);
 752     getsockopt(peer->sock, SOL_SOCKET, SO_ERROR, &err, &len);
 753     if (err)
 754     {
 755         LOG(1, 0, 0, "Can't connect to BGP peer %s (%s)\n", peer->name,
 756             strerror(err));
 757
 758         bgp_set_retry(peer);
 759         return 0;
 760     }
 761
 762     peer->state = Active;
 763     peer->state_time = time_now;
 764
 765     LOG(4, 0, 0, "BGP peer %s: state Active\n", peer->name);
 766
 767     return bgp_send_open(peer);
 768 }
 769
 770 /* initiate a write */
 771 static int bgp_write(struct bgp_peer *peer)
 772 {
 773     int len = htons(peer->outbuf->packet.header.len);
 774     int r;
 775
 776     while ((r = write(peer->sock, &peer->outbuf->packet + peer->outbuf->done,
 777         len - peer->outbuf->done)) == -1)
 778     {
 779         if (errno == EINTR)
 780             continue;
 781
 782         if (errno == EAGAIN)
 783             return 1;
 784
 785         if (errno == EPIPE)
 786             LOG(1, 0, 0, "Connection to BGP peer %s closed\n", peer->name);
 787         else
 788             LOG(1, 0, 0, "Can't write to BGP peer %s (%s)\n", peer->name,
 789                 strerror(errno));
 790
 791         bgp_set_retry(peer);
 792         return 0;
 793     }
 794
 795     if (r < len)
 796     {
 797         peer->outbuf->done += r;
 798         return 1;
 799     }
 800
 801     LOG(4, 0, 0, "Sent %s to BGP peer %s\n",
 802         bgp_msg_type_str(peer->outbuf->packet.header.type), peer->name);
 803
 804     peer->outbuf->packet.header.len = 0;
 805     peer->outbuf->done = 0;
 806
 807     if (peer->state == Established)
 808         peer->keepalive_time = time_now + peer->keepalive;
 809
 810     if (peer->state != peer->next_state)
 811     {
 812         if (peer->next_state == Disabled || peer->next_state == Idle)
 813         {
 814             bgp_clear(peer);
 815             return 0;
 816         }
 817
 818         peer->state = peer->next_state;
 819         peer->state_time = time_now;
 820
 821         LOG(4, 0, 0, "BGP peer %s: state %s\n", peer->name,
 822             bgp_state_str(peer->state));
 823     }
 824
 825     return 1;
 826 }
 827
 828 /* initiate a read */
 829 static int bgp_read(struct bgp_peer *peer)
 830 {
 831     int r;
 832
 833     while ((r = read(peer->sock, &peer->inbuf->packet + peer->inbuf->done,
 834         BGP_MAX_PACKET_SIZE - peer->inbuf->done)) < 1)
 835     {
 836         if (!r)
 837         {
 838             LOG(1, 0, 0, "Connection to BGP peer %s closed\n", peer->name);
 839         }
 840         else
 841         {
 842             if (errno == EINTR)
 843                 continue;
 844
 845             if (errno == EAGAIN)
 846                 return 1;
 847
 848             LOG(1, 0, 0, "Can't read from BGP peer %s (%s)\n", peer->name,
 849                 strerror(errno));
 850         }
 851
 852         bgp_set_retry(peer);
 853         return 0;
 854     }
 855
 856     peer->inbuf->done += r;
 857     return 1;
 858 }
 859
 860 /* process buffered packets */
 861 static int bgp_handle_input(struct bgp_peer *peer)
 862 {
 863     struct bgp_packet *p = &peer->inbuf->packet;
 864     int len = ntohs(p->header.len);
 865
 866     if (len > BGP_MAX_PACKET_SIZE)
 867     {
 868         LOG(1, 0, 0, "Bad header length from BGP %s\n", peer->name);
 869         bgp_send_notification(peer, BGP_ERR_HEADER, BGP_ERR_HDR_BAD_LEN);
 870         return 0;
 871     }
 872
 873     if (peer->inbuf->done < len)
 874         return 0;
 875
 876     LOG(4, 0, 0, "Received %s from BGP peer %s\n",
 877         bgp_msg_type_str(p->header.type), peer->name);
 878
 879     switch (p->header.type)
 880     {
 881     case BGP_MSG_OPEN:
 882         {
 883             struct bgp_data_open data;
 884             int hold;
 885             int i;
 886
 887             for (i = 0; i < sizeof(p->header.marker); i++)
 888             {
 889                 if ((unsigned char) p->header.marker[i] != 0xff)
 890                 {
 891                     LOG(1, 0, 0, "Invalid marker from BGP peer %s\n",
 892                         peer->name);
 893
 894                     bgp_send_notification(peer, BGP_ERR_HEADER,
 895                         BGP_ERR_HDR_NOT_SYNC);
 896
 897                     return 0;
 898                 }
 899             }
 900
 901             if (peer->state != OpenSent)
 902             {
 903                 LOG(1, 0, 0, "OPEN from BGP peer %s in %s state\n",
 904                     peer->name, bgp_state_str(peer->state));
 905
 906                 bgp_send_notification(peer, BGP_ERR_FSM, 0);
 907                 return 0;
 908             }
 909
 910             memcpy(&data, p->data, len - sizeof(p->header));
 911
 912             if (data.version != BGP_VERSION)
 913             {
 914                 LOG(1, 0, 0, "Bad version (%d) sent by BGP peer %s\n",
 915                     (int) data.version, peer->name);
 916
 917                 bgp_send_notification(peer, BGP_ERR_OPEN, BGP_ERR_OPN_VERSION);
 918                 return 0;
 919             }
 920
 921             if (ntohs(data.as) != peer->as)
 922             {
 923                 LOG(1, 0, 0, "Bad AS sent by BGP peer %s (got %d, "
 924                     "expected %d)\n", peer->name, (int) htons(data.as),
 925                     (int) peer->as);
 926
 927                 bgp_send_notification(peer, BGP_ERR_OPEN, BGP_ERR_OPN_BAD_AS);
 928                 return 0;
 929             }
 930
 931             if ((hold = ntohs(data.hold_time)) < 3)
 932             {
 933                 LOG(1, 0, 0, "Bad hold time (%d) from BGP peer %s\n",
 934                     hold, peer->name);
 935
 936                 bgp_send_notification(peer, BGP_ERR_OPEN, BGP_ERR_OPN_HOLD_TIME);
 937                 return 0;
 938             }
 939
 940             /* pick lowest hold time */
 941             if (hold < peer->hold)
 942                 peer->hold = hold;
 943
 944             /* adjust our keepalive based on negotiated hold value */
 945             if (peer->keepalive * 3 > peer->hold)
 946                 peer->keepalive = peer->hold / 3;
 947
 948             /* next transition requires an exchange of keepalives */
 949             bgp_send_keepalive(peer);
 950
 951             /* FIXME: may need to check for optional params */
 952         }
 953
 954         break;
 955
 956     case BGP_MSG_KEEPALIVE:
 957         if (peer->state == OpenConfirm)
 958         {
 959             peer->state = peer->next_state = Established;
 960             peer->state_time = time_now;
 961             peer->keepalive_time = time_now + peer->keepalive;
 962             peer->update_routes = 1;
 963             peer->retry_count = 0;
 964             peer->retry_time = 0;
 965
 966             LOG(4, 0, 0, "BGP peer %s: state Established\n", peer->name);
 967         }
 968
 969         break;
 970
 971     case BGP_MSG_NOTIFICATION:
 972         if (len > sizeof(p->header))
 973         {
 974             struct bgp_data_notification *notification =
 975                 (struct bgp_data_notification *) p->data;
 976
 977             if (notification->error_code == BGP_ERR_CEASE)
 978             {
 979                 LOG(4, 0, 0, "BGP peer %s sent CEASE\n", peer->name);
 980                 bgp_restart(peer);
 981                 return 0;
 982             }
 983
 984             /* FIXME: should handle more notifications */
 985             LOG(4, 0, 0, "BGP peer %s sent unhandled NOTIFICATION %d\n",
 986                 peer->name, (int) notification->error_code);
 987         }
 988
 989         break;
 990     }
 991
 992     /* reset timer */
 993     peer->expire_time = time_now + peer->hold;
 994
 995     /* see if there's another message in the same packet/buffer */
 996     if (peer->inbuf->done > len)
 997     {
 998         peer->inbuf->done -= len;
 999         memmove(p, (char *) p + len, peer->inbuf->done);
1000     }
1001     else
1002     {
1003         peer->inbuf->packet.header.len = 0;
1004         peer->inbuf->done = 0;
1005     }
1006
1007     return peer->inbuf->done;
1008 }
1009
1010 /* send/buffer OPEN message */
1011 static int bgp_send_open(struct bgp_peer *peer)
1012 {
1013     struct bgp_data_open data;
1014     uint16_t len = sizeof(peer->outbuf->packet.header);
1015
1016     memset(peer->outbuf->packet.header.marker, 0xff,
1017         sizeof(peer->outbuf->packet.header.marker));
1018
1019     peer->outbuf->packet.header.type = BGP_MSG_OPEN;
1020
1021     data.version = BGP_VERSION;
1022     data.as = htons(our_as);
1023     data.hold_time = htons(peer->hold);
1024     data.identifier = my_address;
1025     data.opt_len = 0;
1026
1027     memcpy(peer->outbuf->packet.data, &data, BGP_DATA_OPEN_SIZE);
1028     len += BGP_DATA_OPEN_SIZE;
1029
1030     peer->outbuf->packet.header.len = htons(len);
1031     peer->outbuf->done = 0;
1032     peer->next_state = OpenSent;
1033
1034     return bgp_write(peer);
1035 }
1036
1037 /* send/buffer KEEPALIVE message */
1038 static int bgp_send_keepalive(struct bgp_peer *peer)
1039 {
1040     memset(peer->outbuf->packet.header.marker, 0xff,
1041         sizeof(peer->outbuf->packet.header.marker));
1042
1043     peer->outbuf->packet.header.type = BGP_MSG_KEEPALIVE;
1044     peer->outbuf->packet.header.len =
1045         htons(sizeof(peer->outbuf->packet.header));
1046
1047     peer->outbuf->done = 0;
1048     peer->next_state = (peer->state == OpenSent) ? OpenConfirm : peer->state;
1049
1050     return bgp_write(peer);
1051 }
1052
1053 /* send/buffer UPDATE message */
1054 static int bgp_send_update(struct bgp_peer *peer)
1055 {
1056     uint16_t unf_len = 0;
1057     uint16_t attr_len;
1058     uint16_t len = sizeof(peer->outbuf->packet.header);
1059     struct bgp_route_list *have = peer->routes;
1060     struct bgp_route_list *want = peer->routing ? bgp_routes : 0;
1061     struct bgp_route_list *e = 0;
1062     struct bgp_route_list *add = 0;
1063     int s;
1064
1065     char *data = (char *) &peer->outbuf->packet.data;
1066
1067     /* need leave room for attr_len, bgp_path_attrs and one prefix */
1068     char *max = (char *) &peer->outbuf->packet.data
1069         + sizeof(peer->outbuf->packet.data)
1070         - sizeof(attr_len) - peer->path_attr_len - sizeof(struct bgp_ip_prefix);
1071
1072     /* skip over unf_len */
1073     data += sizeof(unf_len);
1074     len += sizeof(unf_len);
1075
1076     memset(peer->outbuf->packet.header.marker, 0xff,
1077         sizeof(peer->outbuf->packet.header.marker));
1078
1079     peer->outbuf->packet.header.type = BGP_MSG_UPDATE;
1080
1081     peer->update_routes = 0; /* tentatively clear */
1082
1083     /* find differences */
1084     while ((have || want) && data < (max - sizeof(struct bgp_ip_prefix)))
1085     {
1086         if (have)
1087             s = want
1088                 ? memcmp(&have->dest, &want->dest, sizeof(have->dest))
1089                 : -1;
1090         else
1091             s = 1;
1092
1093         if (s < 0) /* found one to delete */
1094         {
1095             struct bgp_route_list *tmp = have;
1096             have = have->next;
1097
1098             s = BGP_IP_PREFIX_SIZE(tmp->dest);
1099             memcpy(data, &tmp->dest, s);
1100             data += s;
1101             unf_len += s;
1102             len += s;
1103
1104             LOG(5, 0, 0, "Withdrawing route %s/%d from BGP peer %s\n",
1105                 fmtaddr(tmp->dest.prefix, 0), tmp->dest.len, peer->name);
1106
1107             free(tmp);
1108
1109             if (e)
1110                 e->next = have;
1111             else
1112                 peer->routes = have;
1113         }
1114         else
1115         {
1116             if (!s) /* same */
1117             {
1118                 e = have; /* stash the last found to relink above */
1119                 have = have->next;
1120                 want = want->next;
1121             }
1122             else if (s > 0) /* addition reqd. */
1123             {
1124                 if (add)
1125                 {
1126                     peer->update_routes = 1; /* only one add per packet */
1127                     if (!have)
1128                         break;
1129                 }
1130                 else
1131                     add = want;
1132
1133                 if (want)
1134                     want = want->next;
1135             }
1136         }
1137     }
1138
1139     if (have || want)
1140         peer->update_routes = 1; /* more to do */
1141
1142     /* anything changed? */
1143     if (!(unf_len || add))
1144         return 1;
1145
1146     /* go back and insert unf_len */
1147     unf_len = htons(unf_len);
1148     memcpy(&peer->outbuf->packet.data, &unf_len, sizeof(unf_len));
1149
1150     if (add)
1151     {
1152         if (!(e = malloc(sizeof(*e))))
1153         {
1154             LOG(0, 0, 0, "Can't allocate route for %s/%d (%s)\n",
1155                 fmtaddr(add->dest.prefix, 0), add->dest.len, strerror(errno));
1156
1157             return 0;
1158         }
1159
1160         memcpy(e, add, sizeof(*e));
1161         e->next = 0;
1162         peer->routes = bgp_insert_route(peer->routes, e);
1163
1164         attr_len = htons(peer->path_attr_len);
1165         memcpy(data, &attr_len, sizeof(attr_len));
1166         data += sizeof(attr_len);
1167         len += sizeof(attr_len);
1168
1169         memcpy(data, peer->path_attrs, peer->path_attr_len);
1170         data += peer->path_attr_len;
1171         len += peer->path_attr_len;
1172
1173         s = BGP_IP_PREFIX_SIZE(add->dest);
1174         memcpy(data, &add->dest, s);
1175         data += s;
1176         len += s;
1177
1178         LOG(5, 0, 0, "Advertising route %s/%d to BGP peer %s\n",
1179             fmtaddr(add->dest.prefix, 0), add->dest.len, peer->name);
1180     }
1181     else
1182     {
1183         attr_len = 0;
1184         memcpy(data, &attr_len, sizeof(attr_len));
1185         data += sizeof(attr_len);
1186         len += sizeof(attr_len);
1187     }
1188
1189     peer->outbuf->packet.header.len = htons(len);
1190     peer->outbuf->done = 0;
1191
1192     return bgp_write(peer);
1193 }
1194
1195 /* send/buffer NOTIFICATION message */
1196 static int bgp_send_notification(struct bgp_peer *peer, uint8_t code,
1197     uint8_t subcode)
1198 {
1199     struct bgp_data_notification data;
1200     uint16_t len = 0;
1201
1202     data.error_code = code;
1203     len += sizeof(data.error_code);
1204
1205     data.error_subcode = subcode;
1206     len += sizeof(data.error_code);
1207
1208     memset(peer->outbuf->packet.header.marker, 0xff,
1209         sizeof(peer->outbuf->packet.header.marker));
1210
1211     peer->outbuf->packet.header.type = BGP_MSG_NOTIFICATION;
1212     peer->outbuf->packet.header.len =
1213         htons(sizeof(peer->outbuf->packet.header) + len);
1214
1215     memcpy(peer->outbuf->packet.data, &data, len);
1216
1217     peer->outbuf->done = 0;
1218     peer->next_state = code == BGP_ERR_CEASE ? Disabled : Idle;
1219
1220     /* we're dying; ignore any pending input */
1221     peer->inbuf->packet.header.len = 0;
1222     peer->inbuf->done = 0;
1223
1224     return bgp_write(peer);
1225 }