bgpd/bgp_io.c

   1 /* BGP I/O.
   2  * Implements packet I/O in a pthread.
   3  * Copyright (C) 2017  Cumulus Networks
   4  * Quentin Young
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful, but
  12  * WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; see the file COPYING; if not, write to the
  18  * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
  19  * MA 02110-1301 USA
  20  */
  21
  22 /* clang-format off */
  23 #include <zebra.h>
  24 #include <pthread.h>            // for pthread_mutex_unlock, pthread_mutex_lock
  25
  26 #include "frr_pthread.h"
  27 #include "linklist.h"           // for list_delete, list_delete_all_node, lis...
  28 #include "log.h"                // for zlog_debug, safe_strerror, zlog_err
  29 #include "memory.h"             // for MTYPE_TMP, XCALLOC, XFREE
  30 #include "network.h"            // for ERRNO_IO_RETRY
  31 #include "stream.h"             // for stream_get_endp, stream_getw_from, str...
  32 #include "ringbuf.h"            // for ringbuf_remain, ringbuf_peek, ringbuf_...
  33 #include "thread.h"             // for THREAD_OFF, THREAD_ARG, thread, thread...
  34 #include "zassert.h"            // for assert
  35
  36 #include "bgpd/bgp_io.h"
  37 #include "bgpd/bgp_debug.h"     // for bgp_debug_neighbor_events, bgp_type_str
  38 #include "bgpd/bgp_errors.h"    // for expanded error reference information
  39 #include "bgpd/bgp_fsm.h"       // for BGP_EVENT_ADD, bgp_event
  40 #include "bgpd/bgp_packet.h"    // for bgp_notify_send_with_data, bgp_notify...
  41 #include "bgpd/bgpd.h"          // for peer, BGP_MARKER_SIZE, bgp_master, bm
  42 /* clang-format on */
  43
  44 /* forward declarations */
  45 static uint16_t bgp_write(struct peer *);
  46 static uint16_t bgp_read(struct peer *);
  47 static int bgp_process_writes(struct thread *);
  48 static int bgp_process_reads(struct thread *);
  49 static bool validate_header(struct peer *);
  50
  51 /* generic i/o status codes */
  52 #define BGP_IO_TRANS_ERR (1 << 0) // EAGAIN or similar occurred
  53 #define BGP_IO_FATAL_ERR (1 << 1) // some kind of fatal TCP error
  54
  55 /* Thread external API ----------------------------------------------------- */
  56
  57 void bgp_writes_on(struct peer *peer)
  58 {
  59         struct frr_pthread *fpt = bgp_pth_io;
  60         assert(fpt->running);
  61
  62         assert(peer->status != Deleted);
  63         assert(peer->obuf);
  64         assert(peer->ibuf);
  65         assert(peer->ibuf_work);
  66         assert(!peer->t_connect_check_r);
  67         assert(!peer->t_connect_check_w);
  68         assert(peer->fd);
  69
  70         thread_add_write(fpt->master, bgp_process_writes, peer, peer->fd,
  71                          &peer->t_write);
  72         SET_FLAG(peer->thread_flags, PEER_THREAD_WRITES_ON);
  73 }
  74
  75 void bgp_writes_off(struct peer *peer)
  76 {
  77         struct frr_pthread *fpt = bgp_pth_io;
  78         assert(fpt->running);
  79
  80         thread_cancel_async(fpt->master, &peer->t_write, NULL);
  81         THREAD_OFF(peer->t_generate_updgrp_packets);
  82
  83         UNSET_FLAG(peer->thread_flags, PEER_THREAD_WRITES_ON);
  84 }
  85
  86 void bgp_reads_on(struct peer *peer)
  87 {
  88         struct frr_pthread *fpt = bgp_pth_io;
  89         assert(fpt->running);
  90
  91         assert(peer->status != Deleted);
  92         assert(peer->ibuf);
  93         assert(peer->fd);
  94         assert(peer->ibuf_work);
  95         assert(peer->obuf);
  96         assert(!peer->t_connect_check_r);
  97         assert(!peer->t_connect_check_w);
  98         assert(peer->fd);
  99
 100         thread_add_read(fpt->master, bgp_process_reads, peer, peer->fd,
 101                         &peer->t_read);
 102
 103         SET_FLAG(peer->thread_flags, PEER_THREAD_READS_ON);
 104 }
 105
 106 void bgp_reads_off(struct peer *peer)
 107 {
 108         struct frr_pthread *fpt = bgp_pth_io;
 109         assert(fpt->running);
 110
 111         thread_cancel_async(fpt->master, &peer->t_read, NULL);
 112         THREAD_OFF(peer->t_process_packet);
 113
 114         UNSET_FLAG(peer->thread_flags, PEER_THREAD_READS_ON);
 115 }
 116
 117 /* Thread internal functions ----------------------------------------------- */
 118
 119 /*
 120  * Called from I/O pthread when a file descriptor has become ready for writing.
 121  */
 122 static int bgp_process_writes(struct thread *thread)
 123 {
 124         static struct peer *peer;
 125         peer = THREAD_ARG(thread);
 126         uint16_t status;
 127         bool reschedule;
 128         bool fatal = false;
 129
 130         if (peer->fd < 0)
 131                 return -1;
 132
 133         struct frr_pthread *fpt = bgp_pth_io;
 134
 135         pthread_mutex_lock(&peer->io_mtx);
 136         {
 137                 status = bgp_write(peer);
 138                 reschedule = (stream_fifo_head(peer->obuf) != NULL);
 139         }
 140         pthread_mutex_unlock(&peer->io_mtx);
 141
 142         /* no problem */
 143         if (CHECK_FLAG(status, BGP_IO_TRANS_ERR)) {
 144         }
 145
 146         /* problem */
 147         if (CHECK_FLAG(status, BGP_IO_FATAL_ERR)) {
 148                 reschedule = false;
 149                 fatal = true;
 150         }
 151
 152         if (reschedule) {
 153                 thread_add_write(fpt->master, bgp_process_writes, peer,
 154                                  peer->fd, &peer->t_write);
 155         } else if (!fatal) {
 156                 BGP_TIMER_ON(peer->t_generate_updgrp_packets,
 157                              bgp_generate_updgrp_packets, 0);
 158         }
 159
 160         return 0;
 161 }
 162
 163 /*
 164  * Called from I/O pthread when a file descriptor has become ready for reading,
 165  * or has hung up.
 166  *
 167  * We read as much data as possible, process as many packets as we can and
 168  * place them on peer->ibuf for secondary processing by the main thread.
 169  */
 170 static int bgp_process_reads(struct thread *thread)
 171 {
 172         /* clang-format off */
 173         static struct peer *peer;       // peer to read from
 174         uint16_t status;                // bgp_read status code
 175         bool more = true;               // whether we got more data
 176         bool fatal = false;             // whether fatal error occurred
 177         bool added_pkt = false;         // whether we pushed onto ->ibuf
 178         /* clang-format on */
 179
 180         peer = THREAD_ARG(thread);
 181
 182         if (peer->fd < 0 || bm->terminating)
 183                 return -1;
 184
 185         struct frr_pthread *fpt = bgp_pth_io;
 186
 187         pthread_mutex_lock(&peer->io_mtx);
 188         {
 189                 status = bgp_read(peer);
 190         }
 191         pthread_mutex_unlock(&peer->io_mtx);
 192
 193         /* error checking phase */
 194         if (CHECK_FLAG(status, BGP_IO_TRANS_ERR)) {
 195                 /* no problem; just don't process packets */
 196                 more = false;
 197         }
 198
 199         if (CHECK_FLAG(status, BGP_IO_FATAL_ERR)) {
 200                 /* problem; tear down session */
 201                 more = false;
 202                 fatal = true;
 203         }
 204
 205         while (more) {
 206                 /* static buffer for transferring packets */
 207                 static unsigned char pktbuf[BGP_MAX_PACKET_SIZE];
 208                 /* shorter alias to peer's input buffer */
 209                 struct ringbuf *ibw = peer->ibuf_work;
 210                 /* packet size as given by header */
 211                 uint16_t pktsize = 0;
 212
 213                 /* check that we have enough data for a header */
 214                 if (ringbuf_remain(ibw) < BGP_HEADER_SIZE)
 215                         break;
 216
 217                 /* check that header is valid */
 218                 if (!validate_header(peer)) {
 219                         fatal = true;
 220                         break;
 221                 }
 222
 223                 /* header is valid; retrieve packet size */
 224                 ringbuf_peek(ibw, BGP_MARKER_SIZE, &pktsize, sizeof(pktsize));
 225
 226                 pktsize = ntohs(pktsize);
 227
 228                 /* if this fails we are seriously screwed */
 229                 assert(pktsize <= BGP_MAX_PACKET_SIZE);
 230
 231                 /*
 232                  * If we have that much data, chuck it into its own
 233                  * stream and append to input queue for processing.
 234                  */
 235                 if (ringbuf_remain(ibw) >= pktsize) {
 236                         struct stream *pkt = stream_new(pktsize);
 237                         assert(ringbuf_get(ibw, pktbuf, pktsize) == pktsize);
 238                         stream_put(pkt, pktbuf, pktsize);
 239
 240                         pthread_mutex_lock(&peer->io_mtx);
 241                         {
 242                                 stream_fifo_push(peer->ibuf, pkt);
 243                         }
 244                         pthread_mutex_unlock(&peer->io_mtx);
 245
 246                         added_pkt = true;
 247                 } else
 248                         break;
 249         }
 250
 251         assert(ringbuf_space(peer->ibuf_work) >= BGP_MAX_PACKET_SIZE);
 252
 253         /* handle invalid header */
 254         if (fatal) {
 255                 /* wipe buffer just in case someone screwed up */
 256                 ringbuf_wipe(peer->ibuf_work);
 257         } else {
 258                 thread_add_read(fpt->master, bgp_process_reads, peer, peer->fd,
 259                                 &peer->t_read);
 260                 if (added_pkt)
 261                         thread_add_timer_msec(bm->master, bgp_process_packet,
 262                                               peer, 0, &peer->t_process_packet);
 263         }
 264
 265         return 0;
 266 }
 267
 268 /*
 269  * Flush peer output buffer.
 270  *
 271  * This function pops packets off of peer->obuf and writes them to peer->fd.
 272  * The amount of packets written is equal to the minimum of peer->wpkt_quanta
 273  * and the number of packets on the output buffer, unless an error occurs.
 274  *
 275  * If write() returns an error, the appropriate FSM event is generated.
 276  *
 277  * The return value is equal to the number of packets written
 278  * (which may be zero).
 279  */
 280 static uint16_t bgp_write(struct peer *peer)
 281 {
 282         uint8_t type;
 283         struct stream *s;
 284         int num;
 285         int update_last_write = 0;
 286         unsigned int count = 0;
 287         uint32_t uo = 0;
 288         uint16_t status = 0;
 289         uint32_t wpkt_quanta_old;
 290
 291         wpkt_quanta_old = atomic_load_explicit(&peer->bgp->wpkt_quanta,
 292                                                memory_order_relaxed);
 293
 294         while (count < wpkt_quanta_old && (s = stream_fifo_head(peer->obuf))) {
 295                 int writenum;
 296                 do {
 297                         writenum = stream_get_endp(s) - stream_get_getp(s);
 298                         num = write(peer->fd, STREAM_PNT(s), writenum);
 299
 300                         if (num < 0) {
 301                                 if (!ERRNO_IO_RETRY(errno)) {
 302                                         BGP_EVENT_ADD(peer, TCP_fatal_error);
 303                                         SET_FLAG(status, BGP_IO_FATAL_ERR);
 304                                 } else {
 305                                         SET_FLAG(status, BGP_IO_TRANS_ERR);
 306                                 }
 307
 308                                 goto done;
 309                         } else if (num != writenum)
 310                                 stream_forward_getp(s, num);
 311
 312                 } while (num != writenum);
 313
 314                 /* Retrieve BGP packet type. */
 315                 stream_set_getp(s, BGP_MARKER_SIZE + 2);
 316                 type = stream_getc(s);
 317
 318                 switch (type) {
 319                 case BGP_MSG_OPEN:
 320                         atomic_fetch_add_explicit(&peer->open_out, 1,
 321                                                   memory_order_relaxed);
 322                         break;
 323                 case BGP_MSG_UPDATE:
 324                         atomic_fetch_add_explicit(&peer->update_out, 1,
 325                                                   memory_order_relaxed);
 326                         uo++;
 327                         break;
 328                 case BGP_MSG_NOTIFY:
 329                         atomic_fetch_add_explicit(&peer->notify_out, 1,
 330                                                   memory_order_relaxed);
 331                         /* Double start timer. */
 332                         peer->v_start *= 2;
 333
 334                         /* Overflow check. */
 335                         if (peer->v_start >= (60 * 2))
 336                                 peer->v_start = (60 * 2);
 337
 338                         /*
 339                          * Handle Graceful Restart case where the state changes
 340                          * to Connect instead of Idle.
 341                          */
 342                         BGP_EVENT_ADD(peer, BGP_Stop);
 343                         goto done;
 344
 345                 case BGP_MSG_KEEPALIVE:
 346                         atomic_fetch_add_explicit(&peer->keepalive_out, 1,
 347                                                   memory_order_relaxed);
 348                         break;
 349                 case BGP_MSG_ROUTE_REFRESH_NEW:
 350                 case BGP_MSG_ROUTE_REFRESH_OLD:
 351                         atomic_fetch_add_explicit(&peer->refresh_out, 1,
 352                                                   memory_order_relaxed);
 353                         break;
 354                 case BGP_MSG_CAPABILITY:
 355                         atomic_fetch_add_explicit(&peer->dynamic_cap_out, 1,
 356                                                   memory_order_relaxed);
 357                         break;
 358                 }
 359
 360                 count++;
 361
 362                 stream_free(stream_fifo_pop(peer->obuf));
 363                 update_last_write = 1;
 364         }
 365
 366 done : {
 367         /*
 368          * Update last_update if UPDATEs were written.
 369          * Note: that these are only updated at end,
 370          *       not per message (i.e., per loop)
 371          */
 372         if (uo)
 373                 atomic_store_explicit(&peer->last_update, bgp_clock(),
 374                                       memory_order_relaxed);
 375
 376         /* If we TXed any flavor of packet */
 377         if (update_last_write)
 378                 atomic_store_explicit(&peer->last_write, bgp_clock(),
 379                                       memory_order_relaxed);
 380 }
 381
 382         return status;
 383 }
 384
 385 /*
 386  * Reads a chunk of data from peer->fd into peer->ibuf_work.
 387  *
 388  * @return status flag (see top-of-file)
 389  */
 390 static uint16_t bgp_read(struct peer *peer)
 391 {
 392         size_t readsize; // how many bytes we want to read
 393         ssize_t nbytes;  // how many bytes we actually read
 394         uint16_t status = 0;
 395         static uint8_t ibw[BGP_MAX_PACKET_SIZE * BGP_READ_PACKET_MAX];
 396
 397         readsize = MIN(ringbuf_space(peer->ibuf_work), sizeof(ibw));
 398         nbytes = read(peer->fd, ibw, readsize);
 399
 400         /* EAGAIN or EWOULDBLOCK; come back later */
 401         if (nbytes < 0 && ERRNO_IO_RETRY(errno)) {
 402                 SET_FLAG(status, BGP_IO_TRANS_ERR);
 403                 /* Fatal error; tear down session */
 404         } else if (nbytes < 0) {
 405                 flog_err(EC_BGP_UPDATE_RCV,
 406                          "%s [Error] bgp_read_packet error: %s", peer->host,
 407                          safe_strerror(errno));
 408
 409                 if (peer->status == Established) {
 410                         if (CHECK_FLAG(peer->sflags, PEER_STATUS_NSF_MODE)) {
 411                                 peer->last_reset = PEER_DOWN_NSF_CLOSE_SESSION;
 412                                 SET_FLAG(peer->sflags, PEER_STATUS_NSF_WAIT);
 413                         } else
 414                                 peer->last_reset = PEER_DOWN_CLOSE_SESSION;
 415                 }
 416
 417                 BGP_EVENT_ADD(peer, TCP_fatal_error);
 418                 SET_FLAG(status, BGP_IO_FATAL_ERR);
 419                 /* Received EOF / TCP session closed */
 420         } else if (nbytes == 0) {
 421                 if (bgp_debug_neighbor_events(peer))
 422                         zlog_debug("%s [Event] BGP connection closed fd %d",
 423                                    peer->host, peer->fd);
 424
 425                 if (peer->status == Established) {
 426                         if (CHECK_FLAG(peer->sflags, PEER_STATUS_NSF_MODE)) {
 427                                 peer->last_reset = PEER_DOWN_NSF_CLOSE_SESSION;
 428                                 SET_FLAG(peer->sflags, PEER_STATUS_NSF_WAIT);
 429                         } else
 430                                 peer->last_reset = PEER_DOWN_CLOSE_SESSION;
 431                 }
 432
 433                 BGP_EVENT_ADD(peer, TCP_connection_closed);
 434                 SET_FLAG(status, BGP_IO_FATAL_ERR);
 435         } else {
 436                 assert(ringbuf_put(peer->ibuf_work, ibw, nbytes)
 437                        == (size_t)nbytes);
 438         }
 439
 440         return status;
 441 }
 442
 443 /*
 444  * Called after we have read a BGP packet header. Validates marker, message
 445  * type and packet length. If any of these aren't correct, sends a notify.
 446  *
 447  * Assumes that there are at least BGP_HEADER_SIZE readable bytes in the input
 448  * buffer.
 449  */
 450 static bool validate_header(struct peer *peer)
 451 {
 452         uint16_t size;
 453         uint8_t type;
 454         struct ringbuf *pkt = peer->ibuf_work;
 455
 456         static uint8_t m_correct[BGP_MARKER_SIZE] = {
 457                 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
 458                 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
 459         uint8_t m_rx[BGP_MARKER_SIZE] = {0x00};
 460
 461         if (ringbuf_peek(pkt, 0, m_rx, BGP_MARKER_SIZE) != BGP_MARKER_SIZE)
 462                 return false;
 463
 464         if (memcmp(m_correct, m_rx, BGP_MARKER_SIZE) != 0) {
 465                 bgp_notify_send(peer, BGP_NOTIFY_HEADER_ERR,
 466                                 BGP_NOTIFY_HEADER_NOT_SYNC);
 467                 return false;
 468         }
 469
 470         /* Get size and type in network byte order. */
 471         ringbuf_peek(pkt, BGP_MARKER_SIZE, &size, sizeof(size));
 472         ringbuf_peek(pkt, BGP_MARKER_SIZE + 2, &type, sizeof(type));
 473
 474         size = ntohs(size);
 475
 476         /* BGP type check. */
 477         if (type != BGP_MSG_OPEN && type != BGP_MSG_UPDATE
 478             && type != BGP_MSG_NOTIFY && type != BGP_MSG_KEEPALIVE
 479             && type != BGP_MSG_ROUTE_REFRESH_NEW
 480             && type != BGP_MSG_ROUTE_REFRESH_OLD
 481             && type != BGP_MSG_CAPABILITY) {
 482                 if (bgp_debug_neighbor_events(peer))
 483                         zlog_debug("%s unknown message type 0x%02x", peer->host,
 484                                    type);
 485
 486                 bgp_notify_send_with_data(peer, BGP_NOTIFY_HEADER_ERR,
 487                                           BGP_NOTIFY_HEADER_BAD_MESTYPE, &type,
 488                                           1);
 489                 return false;
 490         }
 491
 492         /* Minimum packet length check. */
 493         if ((size < BGP_HEADER_SIZE) || (size > BGP_MAX_PACKET_SIZE)
 494             || (type == BGP_MSG_OPEN && size < BGP_MSG_OPEN_MIN_SIZE)
 495             || (type == BGP_MSG_UPDATE && size < BGP_MSG_UPDATE_MIN_SIZE)
 496             || (type == BGP_MSG_NOTIFY && size < BGP_MSG_NOTIFY_MIN_SIZE)
 497             || (type == BGP_MSG_KEEPALIVE && size != BGP_MSG_KEEPALIVE_MIN_SIZE)
 498             || (type == BGP_MSG_ROUTE_REFRESH_NEW
 499                 && size < BGP_MSG_ROUTE_REFRESH_MIN_SIZE)
 500             || (type == BGP_MSG_ROUTE_REFRESH_OLD
 501                 && size < BGP_MSG_ROUTE_REFRESH_MIN_SIZE)
 502             || (type == BGP_MSG_CAPABILITY
 503                 && size < BGP_MSG_CAPABILITY_MIN_SIZE)) {
 504                 if (bgp_debug_neighbor_events(peer)) {
 505                         zlog_debug("%s bad message length - %d for %s",
 506                                    peer->host, size,
 507                                    type == 128 ? "ROUTE-REFRESH"
 508                                                : bgp_type_str[(int)type]);
 509                 }
 510
 511                 uint16_t nsize = htons(size);
 512
 513                 bgp_notify_send_with_data(peer, BGP_NOTIFY_HEADER_ERR,
 514                                           BGP_NOTIFY_HEADER_BAD_MESLEN,
 515                                           (unsigned char *)&nsize, 2);
 516                 return false;
 517         }
 518
 519         return true;
 520 }