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5c0c651c
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1/* BGP Keepalives.
2 * Implements a producer thread to generate BGP keepalives for peers.
3 * Copyright (C) 2017 Cumulus Networks, Inc.
4 * Quentin Young
5 *
6 * This file is part of FRRouting.
7 *
8 * FRRouting is free software; you can redistribute it and/or modify it under
9 * the terms of the GNU General Public License as published by the Free
10 * Software Foundation; either version 2, or (at your option) any later
11 * version.
12 *
13 * FRRouting is distributed in the hope that it will be useful, but WITHOUT ANY
14 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
15 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
16 * details.
17 *
18 * You should have received a copy of the GNU General Public License along
19 * with this program; see the file COPYING; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
03014d48 21 */
5c0c651c 22
6ee8ea1c 23/* clang-format off */
03014d48 24#include <zebra.h>
6ee8ea1c 25#include <pthread.h> // for pthread_mutex_lock, pthread_mutex_unlock
03014d48 26
6ee8ea1c
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27#include "frr_pthread.h" // for frr_pthread
28#include "hash.h" // for hash, hash_clean, hash_create_size...
29#include "log.h" // for zlog_debug
30#include "memory.h" // for MTYPE_TMP, XFREE, XCALLOC, XMALLOC
31#include "monotime.h" // for monotime, monotime_since
03014d48 32
6ee8ea1c
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33#include "bgpd/bgpd.h" // for peer, PEER_THREAD_KEEPALIVES_ON, peer...
34#include "bgpd/bgp_debug.h" // for bgp_debug_neighbor_events
35#include "bgpd/bgp_packet.h" // for bgp_keepalive_send
03014d48 36#include "bgpd/bgp_keepalives.h"
6ee8ea1c 37/* clang-format on */
03014d48 38
a715eab3 39/*
03014d48
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40 * Peer KeepAlive Timer.
41 * Associates a peer with the time of its last keepalive.
42 */
43struct pkat {
a715eab3 44 /* the peer to send keepalives to */
03014d48 45 struct peer *peer;
a715eab3 46 /* absolute time of last keepalive sent */
03014d48
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47 struct timeval last;
48};
49
50/* List of peers we are sending keepalives for, and associated mutex. */
bd8b71e4
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51static pthread_mutex_t *peerhash_mtx;
52static pthread_cond_t *peerhash_cond;
53static struct hash *peerhash;
03014d48 54
03014d48
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55static struct pkat *pkat_new(struct peer *peer)
56{
57 struct pkat *pkat = XMALLOC(MTYPE_TMP, sizeof(struct pkat));
58 pkat->peer = peer;
59 monotime(&pkat->last);
60 return pkat;
61}
62
63static void pkat_del(void *pkat)
64{
65 XFREE(MTYPE_TMP, pkat);
66}
03014d48 67
bd8b71e4 68
03014d48 69/*
424ab01d
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70 * Callback for hash_iterate. Determines if a peer needs a keepalive and if so,
71 * generates and sends it.
03014d48
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72 *
73 * For any given peer, if the elapsed time since its last keepalive exceeds its
74 * configured keepalive timer, a keepalive is sent to the peer and its
75 * last-sent time is reset. Additionally, If the elapsed time does not exceed
76 * the configured keepalive timer, but the time until the next keepalive is due
77 * is within a hardcoded tolerance, a keepalive is sent as if the configured
78 * timer was exceeded. Doing this helps alleviate nanosecond sleeps between
79 * ticks by grouping together peers who are due for keepalives at roughly the
80 * same time. This tolerance value is arbitrarily chosen to be 100ms.
81 *
82 * In addition, this function calculates the maximum amount of time that the
83 * keepalive thread can sleep before another tick needs to take place. This is
84 * equivalent to shortest time until a keepalive is due for any one peer.
85 *
86 * @return maximum time to wait until next update (0 if infinity)
87 */
e3b78da8 88static void peer_process(struct hash_bucket *hb, void *arg)
03014d48 89{
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90 struct pkat *pkat = hb->data;
91
92 struct timeval *next_update = arg;
03014d48 93
03014d48
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94 static struct timeval elapsed; // elapsed time since keepalive
95 static struct timeval ka = {0}; // peer->v_keepalive as a timeval
96 static struct timeval diff; // ka - elapsed
97
2b64873d 98 static const struct timeval tolerance = {0, 100000};
03014d48 99
bfc18a02
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100 uint32_t v_ka = atomic_load_explicit(&pkat->peer->v_keepalive,
101 memory_order_relaxed);
102
103 /* 0 keepalive timer means no keepalives */
104 if (v_ka == 0)
105 return;
106
a715eab3 107 /* calculate elapsed time since last keepalive */
bd8b71e4 108 monotime_since(&pkat->last, &elapsed);
03014d48 109
a715eab3 110 /* calculate difference between elapsed time and configured time */
bfc18a02 111 ka.tv_sec = v_ka;
bd8b71e4 112 timersub(&ka, &elapsed, &diff);
03014d48 113
bd8b71e4
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114 int send_keepalive =
115 elapsed.tv_sec >= ka.tv_sec || timercmp(&diff, &tolerance, <);
03014d48 116
bd8b71e4
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117 if (send_keepalive) {
118 if (bgp_debug_neighbor_events(pkat->peer))
119 zlog_debug("%s [FSM] Timer (keepalive timer expire)",
120 pkat->peer->host);
03014d48 121
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122 bgp_keepalive_send(pkat->peer);
123 monotime(&pkat->last);
6006b807 124 memset(&elapsed, 0, sizeof(elapsed));
a715eab3 125 diff = ka;
03014d48
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126 }
127
a715eab3 128 /* if calculated next update for this peer < current delay, use it */
2ccf91b1 129 if (next_update->tv_sec < 0 || timercmp(&diff, next_update, <))
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130 *next_update = diff;
131}
132
74df8d6d 133static bool peer_hash_cmp(const void *f, const void *s)
bd8b71e4
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134{
135 const struct pkat *p1 = f;
136 const struct pkat *p2 = s;
74df8d6d 137
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138 return p1->peer == p2->peer;
139}
140
d8b87afe 141static unsigned int peer_hash_key(const void *arg)
bd8b71e4 142{
d8b87afe 143 const struct pkat *pkat = arg;
bd8b71e4 144 return (uintptr_t)pkat->peer;
03014d48
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145}
146
a715eab3 147/* Cleanup handler / deinitializer. */
b72b6f4f 148static void bgp_keepalives_finish(void *arg)
419dfe6a 149{
bd8b71e4
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150 if (peerhash) {
151 hash_clean(peerhash, pkat_del);
152 hash_free(peerhash);
153 }
419dfe6a 154
bd8b71e4 155 peerhash = NULL;
419dfe6a 156
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157 pthread_mutex_unlock(peerhash_mtx);
158 pthread_mutex_destroy(peerhash_mtx);
159 pthread_cond_destroy(peerhash_cond);
419dfe6a 160
424ab01d
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161 XFREE(MTYPE_TMP, peerhash_mtx);
162 XFREE(MTYPE_TMP, peerhash_cond);
419dfe6a
QY
163}
164
a715eab3 165/*
419dfe6a 166 * Entry function for peer keepalive generation pthread.
419dfe6a 167 */
b72b6f4f 168void *bgp_keepalives_start(void *arg)
419dfe6a 169{
a715eab3
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170 struct frr_pthread *fpt = arg;
171 fpt->master->owner = pthread_self();
172
419dfe6a 173 struct timeval currtime = {0, 0};
bd8b71e4 174 struct timeval aftertime = {0, 0};
419dfe6a
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175 struct timeval next_update = {0, 0};
176 struct timespec next_update_ts = {0, 0};
177
85ba04f3
MS
178 /*
179 * The RCU mechanism for each pthread is initialized in a "locked"
180 * state. That's ok for pthreads using the frr_pthread,
181 * thread_fetch event loop, because that event loop unlocks regularly.
182 * For foreign pthreads, the lock needs to be unlocked so that the
183 * background rcu pthread can run.
184 */
185 rcu_read_unlock();
186
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187 peerhash_mtx = XCALLOC(MTYPE_TMP, sizeof(pthread_mutex_t));
188 peerhash_cond = XCALLOC(MTYPE_TMP, sizeof(pthread_cond_t));
189
190 /* initialize mutex */
191 pthread_mutex_init(peerhash_mtx, NULL);
192
193 /* use monotonic clock with condition variable */
194 pthread_condattr_t attrs;
195 pthread_condattr_init(&attrs);
196 pthread_condattr_setclock(&attrs, CLOCK_MONOTONIC);
197 pthread_cond_init(peerhash_cond, &attrs);
198 pthread_condattr_destroy(&attrs);
199
c80bedb8
DS
200 /*
201 * We are not using normal FRR pthread mechanics and are
202 * not using fpt_run
203 */
204 frr_pthread_set_name(fpt);
a9198bc1 205
a715eab3
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206 /* initialize peer hashtable */
207 peerhash = hash_create_size(2048, peer_hash_key, peer_hash_cmp, NULL);
bd8b71e4 208 pthread_mutex_lock(peerhash_mtx);
03014d48 209
a715eab3 210 /* register cleanup handler */
b72b6f4f 211 pthread_cleanup_push(&bgp_keepalives_finish, NULL);
03014d48 212
a715eab3
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213 /* notify anybody waiting on us that we are done starting up */
214 frr_pthread_notify_running(fpt);
03014d48 215
a715eab3 216 while (atomic_load_explicit(&fpt->running, memory_order_relaxed)) {
bd8b71e4
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217 if (peerhash->count > 0)
218 pthread_cond_timedwait(peerhash_cond, peerhash_mtx,
03014d48
QY
219 &next_update_ts);
220 else
bd8b71e4 221 while (peerhash->count == 0
a715eab3
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222 && atomic_load_explicit(&fpt->running,
223 memory_order_relaxed))
bd8b71e4 224 pthread_cond_wait(peerhash_cond, peerhash_mtx);
03014d48
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225
226 monotime(&currtime);
bd8b71e4
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227
228 next_update.tv_sec = -1;
229
230 hash_iterate(peerhash, peer_process, &next_update);
231 if (next_update.tv_sec == -1)
6006b807 232 memset(&next_update, 0, sizeof(next_update));
bd8b71e4
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233
234 monotime_since(&currtime, &aftertime);
235
03014d48
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236 timeradd(&currtime, &next_update, &next_update);
237 TIMEVAL_TO_TIMESPEC(&next_update, &next_update_ts);
238 }
239
a715eab3 240 /* clean up */
03014d48
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241 pthread_cleanup_pop(1);
242
243 return NULL;
244}
245
246/* --- thread external functions ------------------------------------------- */
247
b72b6f4f 248void bgp_keepalives_on(struct peer *peer)
03014d48 249{
096476dd
QY
250 if (CHECK_FLAG(peer->thread_flags, PEER_THREAD_KEEPALIVES_ON))
251 return;
252
1ac267a2 253 struct frr_pthread *fpt = bgp_pth_ka;
a715eab3
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254 assert(fpt->running);
255
bd8b71e4
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256 /* placeholder bucket data to use for fast key lookups */
257 static struct pkat holder = {0};
258
68ede9c4
DS
259 /*
260 * We need to ensure that bgp_keepalives_init was called first
261 */
262 assert(peerhash_mtx);
934af458 263
cb1991af 264 frr_with_mutex (peerhash_mtx) {
bd8b71e4
QY
265 holder.peer = peer;
266 if (!hash_lookup(peerhash, &holder)) {
267 struct pkat *pkat = pkat_new(peer);
8e3aae66 268 (void)hash_get(peerhash, pkat, hash_alloc_intern);
bd8b71e4
QY
269 peer_lock(peer);
270 }
49507a6f 271 SET_FLAG(peer->thread_flags, PEER_THREAD_KEEPALIVES_ON);
03014d48 272 }
b72b6f4f 273 bgp_keepalives_wake();
03014d48
QY
274}
275
b72b6f4f 276void bgp_keepalives_off(struct peer *peer)
03014d48 277{
096476dd
QY
278 if (!CHECK_FLAG(peer->thread_flags, PEER_THREAD_KEEPALIVES_ON))
279 return;
280
1ac267a2 281 struct frr_pthread *fpt = bgp_pth_ka;
a715eab3
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282 assert(fpt->running);
283
bd8b71e4
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284 /* placeholder bucket data to use for fast key lookups */
285 static struct pkat holder = {0};
49507a6f 286
68ede9c4
DS
287 /*
288 * We need to ensure that bgp_keepalives_init was called first
289 */
290 assert(peerhash_mtx);
934af458 291
cb1991af 292 frr_with_mutex (peerhash_mtx) {
bd8b71e4
QY
293 holder.peer = peer;
294 struct pkat *res = hash_release(peerhash, &holder);
295 if (res) {
296 pkat_del(res);
297 peer_unlock(peer);
298 }
49507a6f 299 UNSET_FLAG(peer->thread_flags, PEER_THREAD_KEEPALIVES_ON);
03014d48 300 }
03014d48
QY
301}
302
4d762f26 303void bgp_keepalives_wake(void)
03014d48 304{
cb1991af 305 frr_with_mutex (peerhash_mtx) {
bd8b71e4 306 pthread_cond_signal(peerhash_cond);
03014d48 307 }
03014d48 308}
0ca8b79f 309
a715eab3 310int bgp_keepalives_stop(struct frr_pthread *fpt, void **result)
0ca8b79f 311{
a715eab3
QY
312 assert(fpt->running);
313
314 atomic_store_explicit(&fpt->running, false, memory_order_relaxed);
b72b6f4f 315 bgp_keepalives_wake();
a715eab3 316
0ca8b79f
QY
317 pthread_join(fpt->thread, result);
318 return 0;
319}