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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 | |
21 | */ | |
22 | ||
23 | /* clang-format off */ | |
24 | #include <zebra.h> | |
25 | #include <pthread.h> // for pthread_mutex_lock, pthread_mutex_unlock | |
26 | ||
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 | |
32 | ||
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 | |
36 | #include "bgpd/bgp_keepalives.h" | |
37 | /* clang-format on */ | |
38 | ||
39 | /* | |
40 | * Peer KeepAlive Timer. | |
41 | * Associates a peer with the time of its last keepalive. | |
42 | */ | |
43 | struct pkat { | |
44 | /* the peer to send keepalives to */ | |
45 | struct peer *peer; | |
46 | /* absolute time of last keepalive sent */ | |
47 | struct timeval last; | |
48 | }; | |
49 | ||
50 | /* List of peers we are sending keepalives for, and associated mutex. */ | |
51 | static pthread_mutex_t *peerhash_mtx; | |
52 | static pthread_cond_t *peerhash_cond; | |
53 | static struct hash *peerhash; | |
54 | ||
55 | static 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 | ||
63 | static void pkat_del(void *pkat) | |
64 | { | |
65 | XFREE(MTYPE_TMP, pkat); | |
66 | } | |
67 | ||
68 | ||
69 | /* | |
70 | * Callback for hash_iterate. Determines if a peer needs a keepalive and if so, | |
71 | * generates and sends it. | |
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 | */ | |
88 | static void peer_process(struct hash_bucket *hb, void *arg) | |
89 | { | |
90 | struct pkat *pkat = hb->data; | |
91 | ||
92 | struct timeval *next_update = arg; | |
93 | ||
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 | ||
98 | static const struct timeval tolerance = {0, 100000}; | |
99 | ||
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 | ||
107 | /* calculate elapsed time since last keepalive */ | |
108 | monotime_since(&pkat->last, &elapsed); | |
109 | ||
110 | /* calculate difference between elapsed time and configured time */ | |
111 | ka.tv_sec = v_ka; | |
112 | timersub(&ka, &elapsed, &diff); | |
113 | ||
114 | int send_keepalive = | |
115 | elapsed.tv_sec >= ka.tv_sec || timercmp(&diff, &tolerance, <); | |
116 | ||
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); | |
121 | ||
122 | bgp_keepalive_send(pkat->peer); | |
123 | monotime(&pkat->last); | |
124 | memset(&elapsed, 0x00, sizeof(struct timeval)); | |
125 | diff = ka; | |
126 | } | |
127 | ||
128 | /* if calculated next update for this peer < current delay, use it */ | |
129 | if (next_update->tv_sec < 0 || timercmp(&diff, next_update, <)) | |
130 | *next_update = diff; | |
131 | } | |
132 | ||
133 | static bool peer_hash_cmp(const void *f, const void *s) | |
134 | { | |
135 | const struct pkat *p1 = f; | |
136 | const struct pkat *p2 = s; | |
137 | ||
138 | return p1->peer == p2->peer; | |
139 | } | |
140 | ||
141 | static unsigned int peer_hash_key(const void *arg) | |
142 | { | |
143 | const struct pkat *pkat = arg; | |
144 | return (uintptr_t)pkat->peer; | |
145 | } | |
146 | ||
147 | /* Cleanup handler / deinitializer. */ | |
148 | static void bgp_keepalives_finish(void *arg) | |
149 | { | |
150 | if (peerhash) { | |
151 | hash_clean(peerhash, pkat_del); | |
152 | hash_free(peerhash); | |
153 | } | |
154 | ||
155 | peerhash = NULL; | |
156 | ||
157 | pthread_mutex_unlock(peerhash_mtx); | |
158 | pthread_mutex_destroy(peerhash_mtx); | |
159 | pthread_cond_destroy(peerhash_cond); | |
160 | ||
161 | XFREE(MTYPE_TMP, peerhash_mtx); | |
162 | XFREE(MTYPE_TMP, peerhash_cond); | |
163 | } | |
164 | ||
165 | /* | |
166 | * Entry function for peer keepalive generation pthread. | |
167 | */ | |
168 | void *bgp_keepalives_start(void *arg) | |
169 | { | |
170 | struct frr_pthread *fpt = arg; | |
171 | fpt->master->owner = pthread_self(); | |
172 | ||
173 | struct timeval currtime = {0, 0}; | |
174 | struct timeval aftertime = {0, 0}; | |
175 | struct timeval next_update = {0, 0}; | |
176 | struct timespec next_update_ts = {0, 0}; | |
177 | ||
178 | peerhash_mtx = XCALLOC(MTYPE_TMP, sizeof(pthread_mutex_t)); | |
179 | peerhash_cond = XCALLOC(MTYPE_TMP, sizeof(pthread_cond_t)); | |
180 | ||
181 | /* initialize mutex */ | |
182 | pthread_mutex_init(peerhash_mtx, NULL); | |
183 | ||
184 | /* use monotonic clock with condition variable */ | |
185 | pthread_condattr_t attrs; | |
186 | pthread_condattr_init(&attrs); | |
187 | pthread_condattr_setclock(&attrs, CLOCK_MONOTONIC); | |
188 | pthread_cond_init(peerhash_cond, &attrs); | |
189 | pthread_condattr_destroy(&attrs); | |
190 | ||
191 | /* | |
192 | * We are not using normal FRR pthread mechanics and are | |
193 | * not using fpt_run | |
194 | */ | |
195 | frr_pthread_set_name(fpt); | |
196 | ||
197 | /* initialize peer hashtable */ | |
198 | peerhash = hash_create_size(2048, peer_hash_key, peer_hash_cmp, NULL); | |
199 | pthread_mutex_lock(peerhash_mtx); | |
200 | ||
201 | /* register cleanup handler */ | |
202 | pthread_cleanup_push(&bgp_keepalives_finish, NULL); | |
203 | ||
204 | /* notify anybody waiting on us that we are done starting up */ | |
205 | frr_pthread_notify_running(fpt); | |
206 | ||
207 | while (atomic_load_explicit(&fpt->running, memory_order_relaxed)) { | |
208 | if (peerhash->count > 0) | |
209 | pthread_cond_timedwait(peerhash_cond, peerhash_mtx, | |
210 | &next_update_ts); | |
211 | else | |
212 | while (peerhash->count == 0 | |
213 | && atomic_load_explicit(&fpt->running, | |
214 | memory_order_relaxed)) | |
215 | pthread_cond_wait(peerhash_cond, peerhash_mtx); | |
216 | ||
217 | monotime(&currtime); | |
218 | ||
219 | next_update.tv_sec = -1; | |
220 | ||
221 | hash_iterate(peerhash, peer_process, &next_update); | |
222 | if (next_update.tv_sec == -1) | |
223 | memset(&next_update, 0x00, sizeof(next_update)); | |
224 | ||
225 | monotime_since(&currtime, &aftertime); | |
226 | ||
227 | timeradd(&currtime, &next_update, &next_update); | |
228 | TIMEVAL_TO_TIMESPEC(&next_update, &next_update_ts); | |
229 | } | |
230 | ||
231 | /* clean up */ | |
232 | pthread_cleanup_pop(1); | |
233 | ||
234 | return NULL; | |
235 | } | |
236 | ||
237 | /* --- thread external functions ------------------------------------------- */ | |
238 | ||
239 | void bgp_keepalives_on(struct peer *peer) | |
240 | { | |
241 | if (CHECK_FLAG(peer->thread_flags, PEER_THREAD_KEEPALIVES_ON)) | |
242 | return; | |
243 | ||
244 | struct frr_pthread *fpt = bgp_pth_ka; | |
245 | assert(fpt->running); | |
246 | ||
247 | /* placeholder bucket data to use for fast key lookups */ | |
248 | static struct pkat holder = {0}; | |
249 | ||
250 | /* | |
251 | * We need to ensure that bgp_keepalives_init was called first | |
252 | */ | |
253 | assert(peerhash_mtx); | |
254 | ||
255 | frr_with_mutex(peerhash_mtx) { | |
256 | holder.peer = peer; | |
257 | if (!hash_lookup(peerhash, &holder)) { | |
258 | struct pkat *pkat = pkat_new(peer); | |
259 | hash_get(peerhash, pkat, hash_alloc_intern); | |
260 | peer_lock(peer); | |
261 | } | |
262 | SET_FLAG(peer->thread_flags, PEER_THREAD_KEEPALIVES_ON); | |
263 | } | |
264 | bgp_keepalives_wake(); | |
265 | } | |
266 | ||
267 | void bgp_keepalives_off(struct peer *peer) | |
268 | { | |
269 | if (!CHECK_FLAG(peer->thread_flags, PEER_THREAD_KEEPALIVES_ON)) | |
270 | return; | |
271 | ||
272 | struct frr_pthread *fpt = bgp_pth_ka; | |
273 | assert(fpt->running); | |
274 | ||
275 | /* placeholder bucket data to use for fast key lookups */ | |
276 | static struct pkat holder = {0}; | |
277 | ||
278 | /* | |
279 | * We need to ensure that bgp_keepalives_init was called first | |
280 | */ | |
281 | assert(peerhash_mtx); | |
282 | ||
283 | frr_with_mutex(peerhash_mtx) { | |
284 | holder.peer = peer; | |
285 | struct pkat *res = hash_release(peerhash, &holder); | |
286 | if (res) { | |
287 | pkat_del(res); | |
288 | peer_unlock(peer); | |
289 | } | |
290 | UNSET_FLAG(peer->thread_flags, PEER_THREAD_KEEPALIVES_ON); | |
291 | } | |
292 | } | |
293 | ||
294 | void bgp_keepalives_wake(void) | |
295 | { | |
296 | frr_with_mutex(peerhash_mtx) { | |
297 | pthread_cond_signal(peerhash_cond); | |
298 | } | |
299 | } | |
300 | ||
301 | int bgp_keepalives_stop(struct frr_pthread *fpt, void **result) | |
302 | { | |
303 | assert(fpt->running); | |
304 | ||
305 | atomic_store_explicit(&fpt->running, false, memory_order_relaxed); | |
306 | bgp_keepalives_wake(); | |
307 | ||
308 | pthread_join(fpt->thread, result); | |
309 | return 0; | |
310 | } |