summaryrefslogtreecommitdiffstats
path: root/bgpd/bgp_io.c
blob: 5ab14d5cd61db24269c7968455cfb5ab2e4b8ff7 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
/* BGP I/O.
 * Implements packet I/O in a pthread.
 * Copyright (C) 2017  Cumulus Networks
 * Quentin Young
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; see the file COPYING; if not, write to the
 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
 * MA 02110-1301 USA
 */

/* clang-format off */
#include <zebra.h>
#include <pthread.h>		// for pthread_mutex_unlock, pthread_mutex_lock

#include "frr_pthread.h"	// for frr_pthread_get, frr_pthread
#include "linklist.h"		// for list_delete, list_delete_all_node, lis...
#include "log.h"		// for zlog_debug, safe_strerror, zlog_err
#include "memory.h"		// for MTYPE_TMP, XCALLOC, XFREE
#include "network.h"		// for ERRNO_IO_RETRY
#include "stream.h"		// for stream_get_endp, stream_getw_from, str...
#include "ringbuf.h"		// for ringbuf_remain, ringbuf_peek, ringbuf_...
#include "thread.h"		// for THREAD_OFF, THREAD_ARG, thread, thread...
#include "zassert.h"		// for assert

#include "bgpd/bgp_io.h"
#include "bgpd/bgp_debug.h"	// for bgp_debug_neighbor_events, bgp_type_str
#include "bgpd/bgp_fsm.h"	// for BGP_EVENT_ADD, bgp_event
#include "bgpd/bgp_packet.h"	// for bgp_notify_send_with_data, bgp_notify...
#include "bgpd/bgpd.h"		// for peer, BGP_MARKER_SIZE, bgp_master, bm
/* clang-format on */

/* forward declarations */
static uint16_t bgp_write(struct peer *);
static uint16_t bgp_read(struct peer *);
static int bgp_process_writes(struct thread *);
static int bgp_process_reads(struct thread *);
static bool validate_header(struct peer *);

/* generic i/o status codes */
#define BGP_IO_TRANS_ERR (1 << 0) // EAGAIN or similar occurred
#define BGP_IO_FATAL_ERR (1 << 1) // some kind of fatal TCP error

/* Start and stop routines for I/O pthread + control variables
 * ------------------------------------------------------------------------ */
_Atomic bool bgp_io_thread_run;
_Atomic bool bgp_io_thread_started;

void bgp_io_init()
{
	bgp_io_thread_run = false;
	bgp_io_thread_started = false;
}

/* Unused callback for thread_add_read() */
static int bgp_io_dummy(struct thread *thread) { return 0; }

void *bgp_io_start(void *arg)
{
	struct frr_pthread *fpt = frr_pthread_get(PTHREAD_IO);
	fpt->master->owner = pthread_self();

	// fd so we can sleep in poll()
	int sleeper[2];
	pipe(sleeper);
	thread_add_read(fpt->master, &bgp_io_dummy, NULL, sleeper[0], NULL);

	// we definitely don't want to handle signals
	fpt->master->handle_signals = false;

	struct thread task;

	atomic_store_explicit(&bgp_io_thread_run, true, memory_order_seq_cst);
	atomic_store_explicit(&bgp_io_thread_started, true,
			      memory_order_seq_cst);

	while (bgp_io_thread_run) {
		if (thread_fetch(fpt->master, &task)) {
			thread_call(&task);
		}
	}

	close(sleeper[1]);
	close(sleeper[0]);

	return NULL;
}

static int bgp_io_finish(struct thread *thread)
{
	atomic_store_explicit(&bgp_io_thread_run, false, memory_order_seq_cst);
	return 0;
}

int bgp_io_stop(void **result, struct frr_pthread *fpt)
{
	thread_add_event(fpt->master, &bgp_io_finish, NULL, 0, NULL);
	pthread_join(fpt->thread, result);
	return 0;
}

/* Extern API -------------------------------------------------------------- */
void bgp_io_running(void)
{
	while (!atomic_load_explicit(&bgp_io_thread_started,
				     memory_order_seq_cst))
		frr_pthread_yield();
}

void bgp_writes_on(struct peer *peer)
{
	assert(peer->status != Deleted);
	assert(peer->obuf);
	assert(peer->ibuf);
	assert(peer->ibuf_work);
	assert(!peer->t_connect_check_r);
	assert(!peer->t_connect_check_w);
	assert(peer->fd);

	struct frr_pthread *fpt = frr_pthread_get(PTHREAD_IO);

	thread_add_write(fpt->master, bgp_process_writes, peer, peer->fd,
			 &peer->t_write);
	SET_FLAG(peer->thread_flags, PEER_THREAD_WRITES_ON);
}

void bgp_writes_off(struct peer *peer)
{
	struct frr_pthread *fpt = frr_pthread_get(PTHREAD_IO);

	thread_cancel_async(fpt->master, &peer->t_write, NULL);
	THREAD_OFF(peer->t_generate_updgrp_packets);

	UNSET_FLAG(peer->thread_flags, PEER_THREAD_WRITES_ON);
}

void bgp_reads_on(struct peer *peer)
{
	assert(peer->status != Deleted);
	assert(peer->ibuf);
	assert(peer->fd);
	assert(peer->ibuf_work);
	assert(peer->obuf);
	assert(!peer->t_connect_check_r);
	assert(!peer->t_connect_check_w);
	assert(peer->fd);

	struct frr_pthread *fpt = frr_pthread_get(PTHREAD_IO);

	thread_add_read(fpt->master, bgp_process_reads, peer, peer->fd,
			&peer->t_read);

	SET_FLAG(peer->thread_flags, PEER_THREAD_READS_ON);
}

void bgp_reads_off(struct peer *peer)
{
	struct frr_pthread *fpt = frr_pthread_get(PTHREAD_IO);

	thread_cancel_async(fpt->master, &peer->t_read, NULL);
	THREAD_OFF(peer->t_process_packet);

	UNSET_FLAG(peer->thread_flags, PEER_THREAD_READS_ON);
}

/* Internal functions ------------------------------------------------------- */

/**
 * Called from I/O pthread when a file descriptor has become ready for writing.
 */
static int bgp_process_writes(struct thread *thread)
{
	static struct peer *peer;
	peer = THREAD_ARG(thread);
	uint16_t status;
	bool reschedule;
	bool fatal = false;

	if (peer->fd < 0)
		return -1;

	struct frr_pthread *fpt = frr_pthread_get(PTHREAD_IO);

	pthread_mutex_lock(&peer->io_mtx);
	{
		status = bgp_write(peer);
		reschedule = (stream_fifo_head(peer->obuf) != NULL);
	}
	pthread_mutex_unlock(&peer->io_mtx);

	if (CHECK_FLAG(status, BGP_IO_TRANS_ERR)) { /* no problem */
	}

	if (CHECK_FLAG(status, BGP_IO_FATAL_ERR)) {
		reschedule = false; /* problem */
		fatal = true;
	}

	if (reschedule) {
		thread_add_write(fpt->master, bgp_process_writes, peer,
				 peer->fd, &peer->t_write);
	} else if (!fatal) {
		BGP_TIMER_ON(peer->t_generate_updgrp_packets,
			     bgp_generate_updgrp_packets, 0);
	}

	return 0;
}

/**
 * Called from I/O pthread when a file descriptor has become ready for reading,
 * or has hung up.
 *
 * We read as much data as possible, process as many packets as we can and
 * place them on peer->ibuf for secondary processing by the main thread.
 */
static int bgp_process_reads(struct thread *thread)
{
	/* clang-format off */
	static struct peer *peer;	// peer to read from
	uint16_t status;		// bgp_read status code
	bool more = true;		// whether we got more data
	bool fatal = false;		// whether fatal error occurred
	bool added_pkt = false;		// whether we pushed onto ->ibuf
	bool header_valid = true;	// whether header is valid
	/* clang-format on */

	peer = THREAD_ARG(thread);

	if (peer->fd < 0)
		return -1;

	struct frr_pthread *fpt = frr_pthread_get(PTHREAD_IO);

	pthread_mutex_lock(&peer->io_mtx);
	{
		status = bgp_read(peer);
	}
	pthread_mutex_unlock(&peer->io_mtx);

	/* error checking phase */
	if (CHECK_FLAG(status, BGP_IO_TRANS_ERR)) {
		/* no problem; just don't process packets */
		more = false;
	}

	if (CHECK_FLAG(status, BGP_IO_FATAL_ERR)) {
		/* problem; tear down session */
		more = false;
		fatal = true;
	}

	while (more) {
		/* static buffer for transferring packets */
		static unsigned char pktbuf[BGP_MAX_PACKET_SIZE];
		/* shorter alias to peer's input buffer */
		struct ringbuf *ibw = peer->ibuf_work;
		/* packet size as given by header */
		uint16_t pktsize = 0;

		/* check that we have enough data for a header */
		if (ringbuf_remain(ibw) < BGP_HEADER_SIZE)
			break;

		/* validate header */
		header_valid = validate_header(peer);

		if (!header_valid) {
			fatal = true;
			break;
		}

		/* header is valid; retrieve packet size */
		ringbuf_peek(ibw, BGP_MARKER_SIZE, &pktsize, sizeof(pktsize));

		pktsize = ntohs(pktsize);

		/* if this fails we are seriously screwed */
		assert(pktsize <= BGP_MAX_PACKET_SIZE);

		/* If we have that much data, chuck it into its own
		 * stream and append to input queue for processing. */
		if (ringbuf_remain(ibw) >= pktsize) {
			struct stream *pkt = stream_new(pktsize);
			assert(ringbuf_get(ibw, pktbuf, pktsize) == pktsize);
			stream_put(pkt, pktbuf, pktsize);

			pthread_mutex_lock(&peer->io_mtx);
			{
				stream_fifo_push(peer->ibuf, pkt);
			}
			pthread_mutex_unlock(&peer->io_mtx);

			added_pkt = true;
		} else
			break;
	}

	assert(ringbuf_space(peer->ibuf_work) >= BGP_MAX_PACKET_SIZE);

	/* handle invalid header */
	if (fatal) {
		/* wipe buffer just in case someone screwed up */
		ringbuf_wipe(peer->ibuf_work);
	} else {
		thread_add_read(fpt->master, bgp_process_reads, peer, peer->fd,
				&peer->t_read);
		if (added_pkt)
			thread_add_timer_msec(bm->master, bgp_process_packet,
					      peer, 0, &peer->t_process_packet);
	}

	return 0;
}

/**
 * Flush peer output buffer.
 *
 * This function pops packets off of peer->obuf and writes them to peer->fd.
 * The amount of packets written is equal to the minimum of peer->wpkt_quanta
 * and the number of packets on the output buffer, unless an error occurs.
 *
 * If write() returns an error, the appropriate FSM event is generated.
 *
 * The return value is equal to the number of packets written
 * (which may be zero).
 */
static uint16_t bgp_write(struct peer *peer)
{
	u_char type;
	struct stream *s;
	int num;
	int update_last_write = 0;
	unsigned int count = 0;
	uint32_t oc;
	uint32_t uo;
	uint16_t status = 0;
	uint32_t wpkt_quanta_old;

	// save current # updates sent
	oc = atomic_load_explicit(&peer->update_out, memory_order_relaxed);

	// cache current write quanta
	wpkt_quanta_old =
	    atomic_load_explicit(&peer->bgp->wpkt_quanta, memory_order_relaxed);

	while (count < wpkt_quanta_old && (s = stream_fifo_head(peer->obuf))) {
		int writenum;
		do {
			writenum = stream_get_endp(s) - stream_get_getp(s);
			num = write(peer->fd, STREAM_PNT(s), writenum);

			if (num < 0) {
				if (!ERRNO_IO_RETRY(errno)) {
					BGP_EVENT_ADD(peer, TCP_fatal_error);
					SET_FLAG(status, BGP_IO_FATAL_ERR);
				} else {
					SET_FLAG(status, BGP_IO_TRANS_ERR);
				}

				goto done;
			} else if (num != writenum) // incomplete write
				stream_forward_getp(s, num);

		} while (num != writenum);

		/* Retrieve BGP packet type. */
		stream_set_getp(s, BGP_MARKER_SIZE + 2);
		type = stream_getc(s);

		switch (type) {
		case BGP_MSG_OPEN:
			atomic_fetch_add_explicit(&peer->open_out, 1,
						  memory_order_relaxed);
			break;
		case BGP_MSG_UPDATE:
			atomic_fetch_add_explicit(&peer->update_out, 1,
						  memory_order_relaxed);
			break;
		case BGP_MSG_NOTIFY:
			atomic_fetch_add_explicit(&peer->notify_out, 1,
						  memory_order_relaxed);
			/* Double start timer. */
			peer->v_start *= 2;

			/* Overflow check. */
			if (peer->v_start >= (60 * 2))
				peer->v_start = (60 * 2);

			/* Handle Graceful Restart case where the state changes
			 * to Connect instead of Idle */
			BGP_EVENT_ADD(peer, BGP_Stop);
			goto done;

		case BGP_MSG_KEEPALIVE:
			atomic_fetch_add_explicit(&peer->keepalive_out, 1,
						  memory_order_relaxed);
			break;
		case BGP_MSG_ROUTE_REFRESH_NEW:
		case BGP_MSG_ROUTE_REFRESH_OLD:
			atomic_fetch_add_explicit(&peer->refresh_out, 1,
						  memory_order_relaxed);
			break;
		case BGP_MSG_CAPABILITY:
			atomic_fetch_add_explicit(&peer->dynamic_cap_out, 1,
						  memory_order_relaxed);
			break;
		}

		count++;

		stream_free(stream_fifo_pop(peer->obuf));
		update_last_write = 1;
	}

done : {
	/* Update last_update if UPDATEs were written. */
	uo = atomic_load_explicit(&peer->update_out, memory_order_relaxed);
	if (uo > oc)
		atomic_store_explicit(&peer->last_update, bgp_clock(),
				      memory_order_relaxed);

	/* If we TXed any flavor of packet */
	if (update_last_write)
		atomic_store_explicit(&peer->last_write, bgp_clock(),
				      memory_order_relaxed);
}

	return status;
}

/**
 * Reads a chunk of data from peer->fd into peer->ibuf_work.
 *
 * @return status flag (see top-of-file)
 */
static uint16_t bgp_read(struct peer *peer)
{
	size_t readsize; // how many bytes we want to read
	ssize_t nbytes;  // how many bytes we actually read
	uint16_t status = 0;
	static uint8_t ibw[BGP_MAX_PACKET_SIZE * BGP_READ_PACKET_MAX];

	readsize = MIN(ringbuf_space(peer->ibuf_work), sizeof(ibw));
	nbytes = read(peer->fd, ibw, readsize);

	/* EAGAIN or EWOULDBLOCK; come back later */
	if (nbytes < 0 && ERRNO_IO_RETRY(errno)) {
		SET_FLAG(status, BGP_IO_TRANS_ERR);
	/* Fatal error; tear down session */
	} else if (nbytes < 0) {
		zlog_err("%s [Error] bgp_read_packet error: %s", peer->host,
			 safe_strerror(errno));

		if (peer->status == Established) {
			if (CHECK_FLAG(peer->sflags, PEER_STATUS_NSF_MODE)) {
				peer->last_reset = PEER_DOWN_NSF_CLOSE_SESSION;
				SET_FLAG(peer->sflags, PEER_STATUS_NSF_WAIT);
			} else
				peer->last_reset = PEER_DOWN_CLOSE_SESSION;
		}

		BGP_EVENT_ADD(peer, TCP_fatal_error);
		SET_FLAG(status, BGP_IO_FATAL_ERR);
	/* Received EOF / TCP session closed */
	} else if (nbytes == 0) {
		if (bgp_debug_neighbor_events(peer))
			zlog_debug("%s [Event] BGP connection closed fd %d",
				   peer->host, peer->fd);

		if (peer->status == Established) {
			if (CHECK_FLAG(peer->sflags, PEER_STATUS_NSF_MODE)) {
				peer->last_reset = PEER_DOWN_NSF_CLOSE_SESSION;
				SET_FLAG(peer->sflags, PEER_STATUS_NSF_WAIT);
			} else
				peer->last_reset = PEER_DOWN_CLOSE_SESSION;
		}

		BGP_EVENT_ADD(peer, TCP_connection_closed);
		SET_FLAG(status, BGP_IO_FATAL_ERR);
	} else {
		assert(ringbuf_put(peer->ibuf_work, ibw, nbytes)
		       == (size_t)nbytes);
	}

	return status;
}

/*
 * Called after we have read a BGP packet header. Validates marker, message
 * type and packet length. If any of these aren't correct, sends a notify.
 *
 * Assumes that there are at least BGP_HEADER_SIZE readable bytes in the input
 * buffer.
 */
static bool validate_header(struct peer *peer)
{
	uint16_t size;
	uint8_t type;
	struct ringbuf *pkt = peer->ibuf_work;

	static uint8_t m_correct[BGP_MARKER_SIZE] = {
		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
		0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
	uint8_t m_rx[BGP_MARKER_SIZE] = {0x00};

	if (ringbuf_peek(pkt, 0, m_rx, BGP_MARKER_SIZE) != BGP_MARKER_SIZE)
		return false;

	if (memcmp(m_correct, m_rx, BGP_MARKER_SIZE) != 0) {
		bgp_notify_send(peer, BGP_NOTIFY_HEADER_ERR,
				BGP_NOTIFY_HEADER_NOT_SYNC);
		return false;
	}

	/* Get size and type in network byte order. */
	ringbuf_peek(pkt, BGP_MARKER_SIZE, &size, sizeof(size));
	ringbuf_peek(pkt, BGP_MARKER_SIZE + 2, &type, sizeof(type));

	size = ntohs(size);

	/* BGP type check. */
	if (type != BGP_MSG_OPEN && type != BGP_MSG_UPDATE
	    && type != BGP_MSG_NOTIFY && type != BGP_MSG_KEEPALIVE
	    && type != BGP_MSG_ROUTE_REFRESH_NEW
	    && type != BGP_MSG_ROUTE_REFRESH_OLD
	    && type != BGP_MSG_CAPABILITY) {
		if (bgp_debug_neighbor_events(peer))
			zlog_debug("%s unknown message type 0x%02x", peer->host,
				   type);

		bgp_notify_send_with_data(peer, BGP_NOTIFY_HEADER_ERR,
					  BGP_NOTIFY_HEADER_BAD_MESTYPE,
					  &type, 1);
		return false;
	}

	/* Minimum packet length check. */
	if ((size < BGP_HEADER_SIZE) || (size > BGP_MAX_PACKET_SIZE)
	    || (type == BGP_MSG_OPEN && size < BGP_MSG_OPEN_MIN_SIZE)
	    || (type == BGP_MSG_UPDATE && size < BGP_MSG_UPDATE_MIN_SIZE)
	    || (type == BGP_MSG_NOTIFY && size < BGP_MSG_NOTIFY_MIN_SIZE)
	    || (type == BGP_MSG_KEEPALIVE && size != BGP_MSG_KEEPALIVE_MIN_SIZE)
	    || (type == BGP_MSG_ROUTE_REFRESH_NEW
		&& size < BGP_MSG_ROUTE_REFRESH_MIN_SIZE)
	    || (type == BGP_MSG_ROUTE_REFRESH_OLD
		&& size < BGP_MSG_ROUTE_REFRESH_MIN_SIZE)
	    || (type == BGP_MSG_CAPABILITY
		&& size < BGP_MSG_CAPABILITY_MIN_SIZE)) {
		if (bgp_debug_neighbor_events(peer)) {
			zlog_debug("%s bad message length - %d for %s",
				   peer->host, size,
				   type == 128 ? "ROUTE-REFRESH"
					       : bgp_type_str[(int) type]);
		}

		uint16_t nsize = htons(size);

		bgp_notify_send_with_data(peer, BGP_NOTIFY_HEADER_ERR,
					  BGP_NOTIFY_HEADER_BAD_MESLEN,
					  (unsigned char *) &nsize, 2);
		return false;
	}

	return true;
}