mainloop.c 94 KB
Newer Older
Roger Dingledine's avatar
Roger Dingledine committed
1
2
/* Copyright (c) 2001 Matej Pfajfar.
 * Copyright (c) 2001-2004, Roger Dingledine.
3
 * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
Nick Mathewson's avatar
Nick Mathewson committed
4
 * Copyright (c) 2007-2018, The Tor Project, Inc. */
5
/* See LICENSE for licensing information */
Roger Dingledine's avatar
Roger Dingledine committed
6

Roger Dingledine's avatar
Roger Dingledine committed
7
/**
8
 * \file mainloop.c
9
 * \brief Toplevel module. Handles signals, multiplexes between
10
 *     connections, implements main loop, and drives scheduled events.
Nick Mathewson's avatar
Nick Mathewson committed
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
 *
 * For the main loop itself; see run_main_loop_once().  It invokes the rest of
 * Tor mostly through Libevent callbacks.  Libevent callbacks can happen when
 * a timer elapses, a signal is received, a socket is ready to read or write,
 * or an event is manually activated.
 *
 * Most events in Tor are driven from these callbacks:
 *  <ul>
 *   <li>conn_read_callback() and conn_write_callback() here, which are
 *     invoked when a socket is ready to read or write respectively.
 *   <li>signal_callback(), which handles incoming signals.
 *  </ul>
 * Other events are used for specific purposes, or for building more complex
 * control structures.  If you search for usage of tor_libevent_new(), you
 * will find all the events that we construct in Tor.
 *
 * Tor has numerous housekeeping operations that need to happen
 * regularly. They are handled in different ways:
 * <ul>
 *   <li>The most frequent operations are handled after every read or write
 *    event, at the end of connection_handle_read() and
 *    connection_handle_write().
 *
 *   <li>The next most frequent operations happen after each invocation of the
 *     main loop, in run_main_loop_once().
 *
 *   <li>Once per second, we run all of the operations listed in
 *     second_elapsed_callback(), and in its child, run_scheduled_events().
 *
 *   <li>Once-a-second operations are handled in second_elapsed_callback().
 *
 *   <li>More infrequent operations take place based on the periodic event
 *     driver in periodic.c .  These are stored in the periodic_events[]
 *     table.
 * </ul>
 *
Roger Dingledine's avatar
Roger Dingledine committed
47
 **/
48

49
#define MAINLOOP_PRIVATE
50
#include "core/or/or.h"
51

52
53
54
55
56
57
58
59
#include "app/config/config.h"
#include "app/config/statefile.h"
#include "app/main/ntmain.h"
#include "core/mainloop/connection.h"
#include "core/mainloop/cpuworker.h"
#include "core/mainloop/mainloop.h"
#include "core/mainloop/netstatus.h"
#include "core/mainloop/periodic.h"
60
61
#include "core/or/channel.h"
#include "core/or/channelpadding.h"
62
#include "core/or/channeltls.h"
63
64
65
66
67
#include "core/or/circuitbuild.h"
#include "core/or/circuitlist.h"
#include "core/or/circuituse.h"
#include "core/or/connection_edge.h"
#include "core/or/connection_or.h"
68
69
70
71
72
73
74
#include "core/or/dos.h"
#include "core/or/status.h"
#include "feature/client/addressmap.h"
#include "feature/client/bridges.h"
#include "feature/client/dnsserv.h"
#include "feature/client/entrynodes.h"
#include "feature/client/transports.h"
75
#include "feature/control/control.h"
76
#include "feature/dirauth/authmode.h"
77
#include "feature/dirauth/reachability.h"
78
79
80
#include "feature/dircache/consdiffmgr.h"
#include "feature/dircache/dirserv.h"
#include "feature/dircommon/directory.h"
81
82
83
#include "feature/hibernate/hibernate.h"
#include "feature/hs/hs_cache.h"
#include "feature/hs/hs_client.h"
84
#include "feature/hs/hs_service.h"
85
86
87
#include "feature/nodelist/microdesc.h"
#include "feature/nodelist/networkstatus.h"
#include "feature/nodelist/nodelist.h"
88
89
90
91
92
#include "feature/nodelist/routerlist.h"
#include "feature/relay/dns.h"
#include "feature/relay/routerkeys.h"
#include "feature/relay/routermode.h"
#include "feature/relay/selftest.h"
93
#include "feature/rend/rendcache.h"
94
#include "feature/rend/rendservice.h"
95
#include "feature/stats/geoip.h"
96
#include "feature/stats/predict_ports.h"
97
#include "feature/stats/rephist.h"
98
99
100
101
102
#include "lib/container/buffers.h"
#include "lib/crypt_ops/crypto_rand.h"
#include "lib/err/backtrace.h"
#include "lib/tls/buffers_tls.h"

Nick Mathewson's avatar
Nick Mathewson committed
103
#include "lib/net/buffers_net.h"
104
#include "lib/evloop/compat_libevent.h"
105

106
107
#include <event2/event.h>

108
#include "feature/dirauth/dirvote.h"
109
#include "feature/dirauth/authmode.h"
110

111
112
113
114
115
116
117
#include "core/or/cell_st.h"
#include "core/or/entry_connection_st.h"
#include "feature/nodelist/networkstatus_st.h"
#include "core/or/or_connection_st.h"
#include "app/config/or_state_st.h"
#include "feature/nodelist/routerinfo_st.h"
#include "core/or/socks_request_st.h"
118

119
120
121
122
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

123
#ifdef HAVE_SYSTEMD
124
125
126
127
128
#   if defined(__COVERITY__) && !defined(__INCLUDE_LEVEL__)
/* Systemd's use of gcc's __INCLUDE_LEVEL__ extension macro appears to confuse
 * Coverity. Here's a kludge to unconfuse it.
 */
#   define __INCLUDE_LEVEL__ 2
129
#endif /* defined(__COVERITY__) && !defined(__INCLUDE_LEVEL__) */
130
#include <systemd/sd-daemon.h>
131
#endif /* defined(HAVE_SYSTEMD) */
132

133
/* Token bucket for all traffic. */
134
token_bucket_rw_t global_bucket;
135
136

/* Token bucket for relayed traffic. */
137
token_bucket_rw_t global_relayed_bucket;
138

139
/* XXX we might want to keep stats about global_relayed_*_bucket too. Or not.*/
140
/** How many bytes have we read since we started the process? */
141
static uint64_t stats_n_bytes_read = 0;
142
/** How many bytes have we written since we started the process? */
143
static uint64_t stats_n_bytes_written = 0;
144
/** What time did this process start up? */
145
time_t time_of_process_start = 0;
Roger Dingledine's avatar
Roger Dingledine committed
146
/** How many seconds have we been running? */
147
static long stats_n_seconds_working = 0;
Alexander Færøy's avatar
Alexander Færøy committed
148
149
150
151
152
153
/** How many times have we returned from the main loop successfully? */
static uint64_t stats_n_main_loop_successes = 0;
/** How many times have we received an error from the main loop? */
static uint64_t stats_n_main_loop_errors = 0;
/** How many times have we returned from the main loop with no events. */
static uint64_t stats_n_main_loop_idle = 0;
154
155
156
157
158
159
160

/** How often will we honor SIGNEWNYM requests? */
#define MAX_SIGNEWNYM_RATE 10
/** When did we last process a SIGNEWNYM request? */
static time_t time_of_last_signewnym = 0;
/** Is there a signewnym request we're currently waiting to handle? */
static int signewnym_is_pending = 0;
161
162
/** Mainloop event for the deferred signewnym call. */
static mainloop_event_t *handle_deferred_signewnym_ev = NULL;
163
164
/** How many times have we called newnym? */
static unsigned newnym_epoch = 0;
165

166
/** Smartlist of all open connections. */
167
STATIC smartlist_t *connection_array = NULL;
168
169
/** List of connections that have been marked for close and need to be freed
 * and removed from connection_array. */
170
static smartlist_t *closeable_connection_lst = NULL;
171
172
/** List of linked connections that are currently reading data into their
 * inbuf from their partner's outbuf. */
173
static smartlist_t *active_linked_connection_lst = NULL;
174
175
176
/** Flag: Set to true iff we entered the current libevent main loop via
 * <b>loop_once</b>. If so, there's no need to trigger a loopexit in order
 * to handle linked connections. */
177
static int called_loop_once = 0;
178
179
180
181
182
183
184
185
/** Flag: if true, it's time to shut down, so the main loop should exit as
 * soon as possible.
 */
static int main_loop_should_exit = 0;
/** The return value that the main loop should yield when it exits, if
 * main_loop_should_exit is true.
 */
static int main_loop_exit_value = 0;
Roger Dingledine's avatar
Roger Dingledine committed
186

Roger Dingledine's avatar
Roger Dingledine committed
187
/** We set this to 1 when we've opened a circuit, so we can print a log
188
189
190
191
192
 * entry to inform the user that Tor is working.  We set it to 0 when
 * we think the fact that we once opened a circuit doesn't mean we can do so
 * any longer (a big time jump happened, when we notice our directory is
 * heinously out-of-date, etc.
 */
193
static int can_complete_circuits = 0;
194

195
196
197
198
199
200
/** How often do we check for router descriptors that we should download
 * when we have too little directory info? */
#define GREEDY_DESCRIPTOR_RETRY_INTERVAL (10)
/** How often do we check for router descriptors that we should download
 * when we have enough directory info? */
#define LAZY_DESCRIPTOR_RETRY_INTERVAL (60)
201

202
203
204
205
206
207
208
209
210
static int conn_close_if_marked(int i);
static int run_main_loop_until_done(void);
static void connection_start_reading_from_linked_conn(connection_t *conn);
static int connection_should_read_from_linked_conn(connection_t *conn);
static void conn_read_callback(evutil_socket_t fd, short event, void *_conn);
static void conn_write_callback(evutil_socket_t fd, short event, void *_conn);
static void second_elapsed_callback(periodic_timer_t *timer, void *args);
static void shutdown_did_not_work_callback(evutil_socket_t fd, short event,
                                           void *arg) ATTR_NORETURN;
Roger Dingledine's avatar
Roger Dingledine committed
211

Roger Dingledine's avatar
Roger Dingledine committed
212
/****************************************************************************
213
214
215
216
217
 *
 * This section contains accessors and other methods on the connection_array
 * variables (which are global within this file and unavailable outside it).
 *
 ****************************************************************************/
Roger Dingledine's avatar
Roger Dingledine committed
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
/** Return 1 if we have successfully built a circuit, and nothing has changed
 * to make us think that maybe we can't.
 */
int
have_completed_a_circuit(void)
{
  return can_complete_circuits;
}

/** Note that we have successfully built a circuit, so that reachability
 * testing and introduction points and so on may be attempted. */
void
note_that_we_completed_a_circuit(void)
{
  can_complete_circuits = 1;
}

/** Note that something has happened (like a clock jump, or DisableNetwork) to
 * make us think that maybe we can't complete circuits. */
void
note_that_we_maybe_cant_complete_circuits(void)
{
  can_complete_circuits = 0;
}

Roger Dingledine's avatar
Roger Dingledine committed
244
/** Add <b>conn</b> to the array of connections that we can poll on.  The
245
246
247
 * connection's socket must be set; the connection starts out
 * non-reading and non-writing.
 */
248
int
249
connection_add_impl(connection_t *conn, int is_connecting)
250
{
Roger Dingledine's avatar
Roger Dingledine committed
251
  tor_assert(conn);
252
  tor_assert(SOCKET_OK(conn->s) ||
253
254
             conn->linked ||
             (conn->type == CONN_TYPE_AP &&
255
              TO_EDGE_CONN(conn)->is_dns_request));
Roger Dingledine's avatar
Roger Dingledine committed
256

257
  tor_assert(conn->conn_array_index == -1); /* can only connection_add once */
258
259
  conn->conn_array_index = smartlist_len(connection_array);
  smartlist_add(connection_array, conn);
Roger Dingledine's avatar
Roger Dingledine committed
260

261
  (void) is_connecting;
262

263
  if (SOCKET_OK(conn->s) || conn->linked) {
264
265
266
267
    conn->read_event = tor_event_new(tor_libevent_get_base(),
         conn->s, EV_READ|EV_PERSIST, conn_read_callback, conn);
    conn->write_event = tor_event_new(tor_libevent_get_base(),
         conn->s, EV_WRITE|EV_PERSIST, conn_write_callback, conn);
268
    /* XXXX CHECK FOR NULL RETURN! */
269
  }
Roger Dingledine's avatar
Roger Dingledine committed
270

Roger Dingledine's avatar
Roger Dingledine committed
271
  log_debug(LD_NET,"new conn type %s, socket %d, address %s, n_conns %d.",
272
            conn_type_to_string(conn->type), (int)conn->s, conn->address,
273
            smartlist_len(connection_array));
Roger Dingledine's avatar
Roger Dingledine committed
274
275
276
277

  return 0;
}

278
279
280
281
282
283
/** Tell libevent that we don't care about <b>conn</b> any more. */
void
connection_unregister_events(connection_t *conn)
{
  if (conn->read_event) {
    if (event_del(conn->read_event))
284
      log_warn(LD_BUG, "Error removing read event for %d", (int)conn->s);
285
286
287
288
    tor_free(conn->read_event);
  }
  if (conn->write_event) {
    if (event_del(conn->write_event))
289
      log_warn(LD_BUG, "Error removing write event for %d", (int)conn->s);
290
291
    tor_free(conn->write_event);
  }
292
  if (conn->type == CONN_TYPE_AP_DNS_LISTENER) {
293
294
295
296
    dnsserv_close_listener(conn);
  }
}

Roger Dingledine's avatar
Roger Dingledine committed
297
/** Remove the connection from the global list, and remove the
Nick Mathewson's avatar
Nick Mathewson committed
298
299
300
 * corresponding poll entry.  Calling this function will shift the last
 * connection (if any) into the position occupied by conn.
 */
301
302
303
int
connection_remove(connection_t *conn)
{
Roger Dingledine's avatar
Roger Dingledine committed
304
  int current_index;
305
  connection_t *tmp;
Roger Dingledine's avatar
Roger Dingledine committed
306

Roger Dingledine's avatar
Roger Dingledine committed
307
  tor_assert(conn);
Roger Dingledine's avatar
Roger Dingledine committed
308

309
  log_debug(LD_NET,"removing socket %d (type %s), n_conns now %d",
310
            (int)conn->s, conn_type_to_string(conn->type),
311
            smartlist_len(connection_array));
Roger Dingledine's avatar
Roger Dingledine committed
312

313
  if (conn->type == CONN_TYPE_AP && conn->socket_family == AF_UNIX) {
314
    log_info(LD_NET, "Closing SOCKS Unix socket connection");
315
316
  }

Karsten Loesing's avatar
Karsten Loesing committed
317
318
  control_event_conn_bandwidth(conn);

319
320
  tor_assert(conn->conn_array_index >= 0);
  current_index = conn->conn_array_index;
321
  connection_unregister_events(conn); /* This is redundant, but cheap. */
322
323
  if (current_index == smartlist_len(connection_array)-1) { /* at the end */
    smartlist_del(connection_array, current_index);
Roger Dingledine's avatar
Roger Dingledine committed
324
    return 0;
Roger Dingledine's avatar
Roger Dingledine committed
325
  }
Roger Dingledine's avatar
Roger Dingledine committed
326

327
  /* replace this one with the one at the end */
328
329
330
  smartlist_del(connection_array, current_index);
  tmp = smartlist_get(connection_array, current_index);
  tmp->conn_array_index = current_index;
Roger Dingledine's avatar
Roger Dingledine committed
331

Roger Dingledine's avatar
Roger Dingledine committed
332
  return 0;
Roger Dingledine's avatar
Roger Dingledine committed
333
334
}

335
/** If <b>conn</b> is an edge conn, remove it from the list
336
337
338
 * of conn's on this circuit. If it's not on an edge,
 * flush and send destroys for all circuits on this conn.
 *
339
340
 * Remove it from connection_array (if applicable) and
 * from closeable_connection_list.
341
342
343
 *
 * Then free it.
 */
344
static void
345
connection_unlink(connection_t *conn)
346
{
347
  connection_about_to_close_connection(conn);
348
  if (conn->conn_array_index >= 0) {
349
350
    connection_remove(conn);
  }
351
352
353
354
355
356
357
  if (conn->linked_conn) {
    conn->linked_conn->linked_conn = NULL;
    if (! conn->linked_conn->marked_for_close &&
        conn->linked_conn->reading_from_linked_conn)
      connection_start_reading(conn->linked_conn);
    conn->linked_conn = NULL;
  }
358
  smartlist_remove(closeable_connection_lst, conn);
359
  smartlist_remove(active_linked_connection_lst, conn);
360
  if (conn->type == CONN_TYPE_EXIT) {
361
    assert_connection_edge_not_dns_pending(TO_EDGE_CONN(conn));
362
  }
363
364
  if (conn->type == CONN_TYPE_OR) {
    if (!tor_digest_is_zero(TO_OR_CONN(conn)->identity_digest))
365
      connection_or_clear_identity(TO_OR_CONN(conn));
366
367
368
369
370
371
372
373
374
375
376
377
    /* connection_unlink() can only get called if the connection
     * was already on the closeable list, and it got there by
     * connection_mark_for_close(), which was called from
     * connection_or_close_normally() or
     * connection_or_close_for_error(), so the channel should
     * already be in CHANNEL_STATE_CLOSING, and then the
     * connection_about_to_close_connection() goes to
     * connection_or_about_to_close(), which calls channel_closed()
     * to notify the channel_t layer, and closed the channel, so
     * nothing more to do here to deal with the channel associated
     * with an orconn.
     */
378
  }
379
380
381
  connection_free(conn);
}

382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
/**
 * Callback: used to activate read events for all linked connections, so
 * libevent knows to call their read callbacks.  This callback run as a
 * postloop event, so that the events _it_ activates don't happen until
 * Libevent has a chance to check for other events.
 */
static void
schedule_active_linked_connections_cb(mainloop_event_t *event, void *arg)
{
  (void)event;
  (void)arg;

  /* All active linked conns should get their read events activated,
   * so that libevent knows to run their callbacks. */
  SMARTLIST_FOREACH(active_linked_connection_lst, connection_t *, conn,
                    event_active(conn->read_event, EV_READ, 1));
}

/** Event that invokes schedule_active_linked_connections_cb. */
static mainloop_event_t *schedule_active_linked_connections_event = NULL;

403
404
/** Initialize the global connection list, closeable connection list,
 * and active connection list. */
405
406
void
tor_init_connection_lists(void)
407
408
409
410
411
412
413
414
415
{
  if (!connection_array)
    connection_array = smartlist_new();
  if (!closeable_connection_lst)
    closeable_connection_lst = smartlist_new();
  if (!active_linked_connection_lst)
    active_linked_connection_lst = smartlist_new();
}

416
/** Schedule <b>conn</b> to be closed. **/
417
418
419
void
add_connection_to_closeable_list(connection_t *conn)
{
Nick Mathewson's avatar
Nick Mathewson committed
420
  tor_assert(!smartlist_contains(closeable_connection_lst, conn));
421
  tor_assert(conn->marked_for_close);
422
  assert_connection_ok(conn, time(NULL));
423
  smartlist_add(closeable_connection_lst, conn);
424
  mainloop_schedule_postloop_cleanup();
425
426
}

427
/** Return 1 if conn is on the closeable list, else return 0. */
428
429
430
int
connection_is_on_closeable_list(connection_t *conn)
{
Nick Mathewson's avatar
Nick Mathewson committed
431
  return smartlist_contains(closeable_connection_lst, conn);
432
433
}

434
/** Return true iff conn is in the current poll array. */
435
436
437
int
connection_in_array(connection_t *conn)
{
Nick Mathewson's avatar
Nick Mathewson committed
438
  return smartlist_contains(connection_array, conn);
439
440
}

441
/** Set <b>*array</b> to an array of all connections. <b>*array</b> must not
Roger Dingledine's avatar
Roger Dingledine committed
442
 * be modified.
443
 */
444
445
MOCK_IMPL(smartlist_t *,
get_connection_array, (void))
446
{
447
  if (!connection_array)
448
    connection_array = smartlist_new();
449
  return connection_array;
450
451
}

452
453
454
455
/**
 * Return the amount of network traffic read, in bytes, over the life of this
 * process.
 */
456
457
MOCK_IMPL(uint64_t,
get_bytes_read,(void))
458
459
460
461
{
  return stats_n_bytes_read;
}

462
463
464
465
/**
 * Return the amount of network traffic read, in bytes, over the life of this
 * process.
 */
466
467
MOCK_IMPL(uint64_t,
get_bytes_written,(void))
468
469
470
471
{
  return stats_n_bytes_written;
}

472
473
474
475
476
477
478
479
480
481
482
/**
 * Increment the amount of network traffic read and written, over the life of
 * this process.
 */
void
stats_increment_bytes_read_and_written(uint64_t r, uint64_t w)
{
  stats_n_bytes_read += r;
  stats_n_bytes_written += w;
}

483
/** Set the event mask on <b>conn</b> to <b>events</b>.  (The event
484
 * mask is a bitmask whose bits are READ_EVENT and WRITE_EVENT)
485
 */
486
void
487
connection_watch_events(connection_t *conn, watchable_events_t events)
488
{
489
  if (events & READ_EVENT)
490
491
492
493
    connection_start_reading(conn);
  else
    connection_stop_reading(conn);

494
  if (events & WRITE_EVENT)
495
496
497
    connection_start_writing(conn);
  else
    connection_stop_writing(conn);
Roger Dingledine's avatar
Roger Dingledine committed
498
499
}

Roger Dingledine's avatar
Roger Dingledine committed
500
/** Return true iff <b>conn</b> is listening for read events. */
501
502
503
int
connection_is_reading(connection_t *conn)
{
504
  tor_assert(conn);
505

506
507
  return conn->reading_from_linked_conn ||
    (conn->read_event && event_pending(conn->read_event, EV_READ, NULL));
Roger Dingledine's avatar
Roger Dingledine committed
508
509
}

Alexander Færøy's avatar
Alexander Færøy committed
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
/** Reset our main loop counters. */
void
reset_main_loop_counters(void)
{
  stats_n_main_loop_successes = 0;
  stats_n_main_loop_errors = 0;
  stats_n_main_loop_idle = 0;
}

/** Increment the main loop success counter. */
static void
increment_main_loop_success_count(void)
{
  ++stats_n_main_loop_successes;
}

/** Get the main loop success counter. */
uint64_t
get_main_loop_success_count(void)
{
  return stats_n_main_loop_successes;
}

/** Increment the main loop error counter. */
static void
increment_main_loop_error_count(void)
{
  ++stats_n_main_loop_errors;
}

/** Get the main loop error counter. */
uint64_t
get_main_loop_error_count(void)
{
  return stats_n_main_loop_errors;
}

/** Increment the main loop idle counter. */
static void
increment_main_loop_idle_count(void)
{
  ++stats_n_main_loop_idle;
}

/** Get the main loop idle counter. */
uint64_t
get_main_loop_idle_count(void)
{
  return stats_n_main_loop_idle;
}

561
/** Check whether <b>conn</b> is correct in having (or not having) a
562
 * read/write event (passed in <b>ev</b>). On success, return 0. On failure,
563
 * log a warning and return -1. */
564
565
566
567
568
569
static int
connection_check_event(connection_t *conn, struct event *ev)
{
  int bad;

  if (conn->type == CONN_TYPE_AP && TO_EDGE_CONN(conn)->is_dns_request) {
570
571
572
573
    /* DNS requests which we launch through the dnsserv.c module do not have
     * any underlying socket or any underlying linked connection, so they
     * shouldn't have any attached events either.
     */
574
575
    bad = ev != NULL;
  } else {
Chelsea H. Komlo's avatar
Chelsea H. Komlo committed
576
    /* Everything else should have an underlying socket, or a linked
577
578
     * connection (which is also tracked with a read_event/write_event pair).
     */
579
580
581
582
583
584
585
586
587
588
589
    bad = ev == NULL;
  }

  if (bad) {
    log_warn(LD_BUG, "Event missing on connection %p [%s;%s]. "
             "socket=%d. linked=%d. "
             "is_dns_request=%d. Marked_for_close=%s:%d",
             conn,
             conn_type_to_string(conn->type),
             conn_state_to_string(conn->type, conn->state),
             (int)conn->s, (int)conn->linked,
Nick Mathewson's avatar
Nick Mathewson committed
590
591
             (conn->type == CONN_TYPE_AP &&
                               TO_EDGE_CONN(conn)->is_dns_request),
592
593
594
595
596
597
598
599
600
             conn->marked_for_close_file ? conn->marked_for_close_file : "-",
             conn->marked_for_close
             );
    log_backtrace(LOG_WARN, LD_BUG, "Backtrace attached.");
    return -1;
  }
  return 0;
}

Roger Dingledine's avatar
Roger Dingledine committed
601
/** Tell the main loop to stop notifying <b>conn</b> of any read events. */
602
603
MOCK_IMPL(void,
connection_stop_reading,(connection_t *conn))
604
{
605
  tor_assert(conn);
606

607
  if (connection_check_event(conn, conn->read_event) < 0) {
608
609
    return;
  }
610

611
612
613
614
615
616
617
  if (conn->linked) {
    conn->reading_from_linked_conn = 0;
    connection_stop_reading_from_linked_conn(conn);
  } else {
    if (event_del(conn->read_event))
      log_warn(LD_NET, "Error from libevent setting read event state for %d "
               "to unwatched: %s",
618
               (int)conn->s,
619
620
               tor_socket_strerror(tor_socket_errno(conn->s)));
  }
621
622
}

Roger Dingledine's avatar
Roger Dingledine committed
623
/** Tell the main loop to start notifying <b>conn</b> of any read events. */
624
625
MOCK_IMPL(void,
connection_start_reading,(connection_t *conn))
626
{
627
  tor_assert(conn);
628

629
  if (connection_check_event(conn, conn->read_event) < 0) {
630
631
    return;
  }
632

633
634
635
636
637
638
639
640
  if (conn->linked) {
    conn->reading_from_linked_conn = 1;
    if (connection_should_read_from_linked_conn(conn))
      connection_start_reading_from_linked_conn(conn);
  } else {
    if (event_add(conn->read_event, NULL))
      log_warn(LD_NET, "Error from libevent setting read event state for %d "
               "to watched: %s",
641
               (int)conn->s,
642
643
               tor_socket_strerror(tor_socket_errno(conn->s)));
  }
644
645
}

Roger Dingledine's avatar
Roger Dingledine committed
646
/** Return true iff <b>conn</b> is listening for write events. */
647
648
649
int
connection_is_writing(connection_t *conn)
{
650
651
  tor_assert(conn);

652
653
  return conn->writing_to_linked_conn ||
    (conn->write_event && event_pending(conn->write_event, EV_WRITE, NULL));
654
655
}

Roger Dingledine's avatar
Roger Dingledine committed
656
/** Tell the main loop to stop notifying <b>conn</b> of any write events. */
657
658
MOCK_IMPL(void,
connection_stop_writing,(connection_t *conn))
659
{
660
  tor_assert(conn);
661

662
663
664
  if (connection_check_event(conn, conn->write_event) < 0) {
    return;
  }
665

666
667
668
669
670
671
672
673
  if (conn->linked) {
    conn->writing_to_linked_conn = 0;
    if (conn->linked_conn)
      connection_stop_reading_from_linked_conn(conn->linked_conn);
  } else {
    if (event_del(conn->write_event))
      log_warn(LD_NET, "Error from libevent setting write event state for %d "
               "to unwatched: %s",
674
               (int)conn->s,
675
676
               tor_socket_strerror(tor_socket_errno(conn->s)));
  }
677
678
}

Roger Dingledine's avatar
Roger Dingledine committed
679
/** Tell the main loop to start notifying <b>conn</b> of any write events. */
680
681
MOCK_IMPL(void,
connection_start_writing,(connection_t *conn))
682
{
683
  tor_assert(conn);
684

685
686
687
  if (connection_check_event(conn, conn->write_event) < 0) {
    return;
  }
688

689
690
691
692
693
694
695
696
697
  if (conn->linked) {
    conn->writing_to_linked_conn = 1;
    if (conn->linked_conn &&
        connection_should_read_from_linked_conn(conn->linked_conn))
      connection_start_reading_from_linked_conn(conn->linked_conn);
  } else {
    if (event_add(conn->write_event, NULL))
      log_warn(LD_NET, "Error from libevent setting write event state for %d "
               "to watched: %s",
698
               (int)conn->s,
699
700
701
702
               tor_socket_strerror(tor_socket_errno(conn->s)));
  }
}

703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
/** Return true iff <b>conn</b> is linked conn, and reading from the conn
 * linked to it would be good and feasible.  (Reading is "feasible" if the
 * other conn exists and has data in its outbuf, and is "good" if we have our
 * reading_from_linked_conn flag set and the other conn has its
 * writing_to_linked_conn flag set.)*/
static int
connection_should_read_from_linked_conn(connection_t *conn)
{
  if (conn->linked && conn->reading_from_linked_conn) {
    if (! conn->linked_conn ||
        (conn->linked_conn->writing_to_linked_conn &&
         buf_datalen(conn->linked_conn->outbuf)))
      return 1;
  }
  return 0;
}

Nick Mathewson's avatar
Nick Mathewson committed
720
721
722
/** Event to run 'shutdown did not work callback'. */
static struct event *shutdown_did_not_work_event = NULL;

723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
/** Failsafe measure that should never actually be necessary: If
 * tor_shutdown_event_loop_and_exit() somehow doesn't successfully exit the
 * event loop, then this callback will kill Tor with an assertion failure
 * seconds later
 */
static void
shutdown_did_not_work_callback(evutil_socket_t fd, short event, void *arg)
{
  // LCOV_EXCL_START
  (void) fd;
  (void) event;
  (void) arg;
  tor_assert_unreached();
  // LCOV_EXCL_STOP
}

739
740
741
742
743
744
745
746
747
748
749
750
751
752
#ifdef ENABLE_RESTART_DEBUGGING
static struct event *tor_shutdown_event_loop_for_restart_event = NULL;
static void
tor_shutdown_event_loop_for_restart_cb(
                      evutil_socket_t fd, short event, void *arg)
{
  (void)fd;
  (void)event;
  (void)arg;
  tor_event_free(tor_shutdown_event_loop_for_restart_event);
  tor_shutdown_event_loop_and_exit(0);
}
#endif

753
754
755
756
757
758
759
760
761
762
763
764
765
/**
 * After finishing the current callback (if any), shut down the main loop,
 * clean up the process, and exit with <b>exitcode</b>.
 */
void
tor_shutdown_event_loop_and_exit(int exitcode)
{
  if (main_loop_should_exit)
    return; /* Ignore multiple calls to this function. */

  main_loop_should_exit = 1;
  main_loop_exit_value = exitcode;

766
767
  /* Die with an assertion failure in ten seconds, if for some reason we don't
   * exit normally. */
768
  /* XXXX We should consider this code if it's never used. */
769
  struct timeval ten_seconds = { 10, 0 };
Nick Mathewson's avatar
Nick Mathewson committed
770
771
772
773
  shutdown_did_not_work_event = tor_evtimer_new(
                  tor_libevent_get_base(),
                  shutdown_did_not_work_callback, NULL);
  event_add(shutdown_did_not_work_event, &ten_seconds);
774

775
776
777
  /* Unlike exit_loop_after_delay(), exit_loop_after_callback
   * prevents other callbacks from running. */
  tor_libevent_exit_loop_after_callback(tor_libevent_get_base());
778
779
780
781
782
783
784
785
786
}

/** Return true iff tor_shutdown_event_loop_and_exit() has been called. */
int
tor_event_loop_shutdown_is_pending(void)
{
  return main_loop_should_exit;
}

787
788
789
790
/** Helper: Tell the main loop to begin reading bytes into <b>conn</b> from
 * its linked connection, if it is not doing so already.  Called by
 * connection_start_reading and connection_start_writing as appropriate. */
static void
791
792
793
794
795
796
797
798
connection_start_reading_from_linked_conn(connection_t *conn)
{
  tor_assert(conn);
  tor_assert(conn->linked == 1);

  if (!conn->active_on_link) {
    conn->active_on_link = 1;
    smartlist_add(active_linked_connection_lst, conn);
799
    mainloop_event_activate(schedule_active_linked_connections_event);
800
  } else {
Nick Mathewson's avatar
Nick Mathewson committed
801
    tor_assert(smartlist_contains(active_linked_connection_lst, conn));
802
803
804
  }
}

805
806
807
/** Tell the main loop to stop reading bytes into <b>conn</b> from its linked
 * connection, if is currently doing so.  Called by connection_stop_reading,
 * connection_stop_writing, and connection_read. */
808
809
810
811
812
813
814
815
void
connection_stop_reading_from_linked_conn(connection_t *conn)
{
  tor_assert(conn);
  tor_assert(conn->linked == 1);

  if (conn->active_on_link) {
    conn->active_on_link = 0;
816
817
818
    /* FFFF We could keep an index here so we can smartlist_del
     * cleanly.  On the other hand, this doesn't show up on profiles,
     * so let's leave it alone for now. */
819
820
    smartlist_remove(active_linked_connection_lst, conn);
  } else {
Nick Mathewson's avatar
Nick Mathewson committed
821
    tor_assert(!smartlist_contains(active_linked_connection_lst, conn));
822
  }
823
824
}

825
/** Close all connections that have been scheduled to get closed. */
826
STATIC void
827
828
829
830
831
close_closeable_connections(void)
{
  int i;
  for (i = 0; i < smartlist_len(closeable_connection_lst); ) {
    connection_t *conn = smartlist_get(closeable_connection_lst, i);
832
    if (conn->conn_array_index < 0) {
833
      connection_unlink(conn); /* blow it away right now */
834
    } else {
835
      if (!conn_close_if_marked(conn->conn_array_index))
836
837
        ++i;
    }
838
839
840
  }
}

841
/** Count moribund connections for the OOS handler */
842
843
MOCK_IMPL(int,
connection_count_moribund, (void))
844
{
845
  int moribund = 0;
846
847
848
849
850

  /*
   * Count things we'll try to kill when close_closeable_connections()
   * runs next.
   */
851
  SMARTLIST_FOREACH_BEGIN(closeable_connection_lst, connection_t *, conn) {
852
    if (SOCKET_OK(conn->s) && connection_is_moribund(conn)) ++moribund;
853
  } SMARTLIST_FOREACH_END(conn);
854
855
856
857

  return moribund;
}

858
859
/** Libevent callback: this gets invoked when (connection_t*)<b>conn</b> has
 * some data to read. */
860
static void
861
conn_read_callback(evutil_socket_t fd, short event, void *_conn)
862
863
{
  connection_t *conn = _conn;
864
865
  (void)fd;
  (void)event;
866

867
  log_debug(LD_NET,"socket %d wants to read.",(int)conn->s);
868

869
  /* assert_connection_ok(conn, time(NULL)); */
870
871
872

  if (connection_handle_read(conn) < 0) {
    if (!conn->marked_for_close) {
873
#ifndef _WIN32
874
      log_warn(LD_BUG,"Unhandled error on read for %s connection "
875
               "(fd %d); removing",
876
               conn_type_to_string(conn->type), (int)conn->s);
877
      tor_fragile_assert();
878
#endif /* !defined(_WIN32) */
879
      if (CONN_IS_EDGE(conn))
880
        connection_edge_end_errno(TO_EDGE_CONN(conn));
881
882
883
884
885
886
887
888
889
      connection_mark_for_close(conn);
    }
  }
  assert_connection_ok(conn, time(NULL));

  if (smartlist_len(closeable_connection_lst))
    close_closeable_connections();
}

890
891
/** Libevent callback: this gets invoked when (connection_t*)<b>conn</b> has
 * some data to write. */
892
static void
893
conn_write_callback(evutil_socket_t fd, short events, void *_conn)
894
895
{
  connection_t *conn = _conn;
896
897
  (void)fd;
  (void)events;
898

899
900
  LOG_FN_CONN(conn, (LOG_DEBUG, LD_NET, "socket %d wants to write.",
                     (int)conn->s));
901

902
  /* assert_connection_ok(conn, time(NULL)); */
903

904
  if (connection_handle_write(conn, 0) < 0) {
905
906
    if (!conn->marked_for_close) {
      /* this connection is broken. remove it. */
907
      log_fn(LOG_WARN,LD_BUG,
Roger Dingledine's avatar
Roger Dingledine committed
908
             "unhandled error on write for %s connection (fd %d); removing",
909
             conn_type_to_string(conn->type), (int)conn->s);
910
      tor_fragile_assert();
911
912
      if (CONN_IS_EDGE(conn)) {
        /* otherwise we cry wolf about duplicate close */
913
914
915
        edge_connection_t *edge_conn = TO_EDGE_CONN(conn);
        if (!edge_conn->end_reason)
          edge_conn->end_reason = END_STREAM_REASON_INTERNAL;
916
        edge_conn->edge_has_sent_end = 1;
917
      }
918
      connection_close_immediate(conn); /* So we don't try to flush. */
919
920
921
922
923
924
925
926
927
      connection_mark_for_close(conn);
    }
  }
  assert_connection_ok(conn, time(NULL));

  if (smartlist_len(closeable_connection_lst))
    close_closeable_connections();
}

Roger Dingledine's avatar
Roger Dingledine committed
928
/** If the connection at connection_array[i] is marked for close, then:
929
930
931
932
933
 *    - If it has data that it wants to flush, try to flush it.
 *    - If it _still_ has data to flush, and conn->hold_open_until_flushed is
 *      true, then leave the connection open and return.
 *    - Otherwise, remove the connection from connection_array and from
 *      all other lists, close it, and free it.
934
 * Returns 1 if the connection was closed, 0 otherwise.
935
 */
936
937
938
static int
conn_close_if_marked(int i)
{
Roger Dingledine's avatar
Roger Dingledine committed
939
  connection_t *conn;
940
  int retval;
941
  time_t now;
Roger Dingledine's avatar
Roger Dingledine committed
942

943
  conn = smartlist_get(connection_array, i);
944
  if (!conn->marked_for_close)
945
    return 0; /* nothing to see here, move along */
946
947
  now = time(NULL);
  assert_connection_ok(conn, now);
948
  /* assert_all_pending_dns_resolves_ok(); */
949

Nick Mathewson's avatar
Nick Mathewson committed
950
951
  log_debug(LD_NET,"Cleaning up connection (fd "TOR_SOCKET_T_FORMAT").",
            conn->s);
952
953
954

  /* If the connection we are about to close was trying to connect to
  a proxy server and failed, the client won't be able to use that
955
  proxy. We should warn the user about this. */
956
957
  if (conn->proxy_state == PROXY_INFANT)
    log_failed_proxy_connection(conn);
958

959
960
  if ((SOCKET_OK(conn->s) || conn->linked_conn) &&
      connection_wants_to_flush(conn)) {
961
    /* s == -1 means it's an incomplete edge connection, or that the socket
962
     * has already been closed as unflushable. */
963
    ssize_t sz = connection_bucket_write_limit(conn, now);
964
    if (!conn->hold_open_until_flushed)
965
966
967
      log_info(LD_NET,
               "Conn (addr %s, fd %d, type %s, state %d) marked, but wants "
               "to flush %d bytes. (Marked at %s:%d)",
968
               escaped_safe_str_client(conn->address),
969
               (int)conn->s, conn_type_to_string(conn->type), conn->state,
970
971
               (int)conn->outbuf_flushlen,
                conn->marked_for_close_file, conn->marked_for_close);
972
    if (conn->linked_conn) {
973
      retval = buf_move_to_buf(conn->linked_conn->inbuf, conn->outbuf,
974
975
976
977
978
979
                               &conn->outbuf_flushlen);
      if (retval >= 0) {
        /* The linked conn will notice that it has data when it notices that
         * we're gone. */
        connection_start_reading_from_linked_conn(conn->linked_conn);
      }
980
      log_debug(LD_GENERAL, "Flushed last %d bytes from a linked conn; "
981
               "%d left; flushlen %d; wants-to-flush==%d", retval,
982
983
                (int)connection_get_outbuf_len(conn),
                (int)conn->outbuf_flushlen,
984
                connection_wants_to_flush(conn));
985
    } else if (connection_speaks_cells(conn)) {
986
      if (conn->state == OR_CONN_STATE_OPEN) {
987
        retval = buf_flush_to_tls(conn->outbuf, TO_OR_CONN(conn)->tls, sz,
988
                               &conn->outbuf_flushlen);
989
      } else
990
        retval = -1; /* never flush non-open broken tls connections */
991
    } else {
992
      retval = buf_flush_to_socket(conn->outbuf, conn->s, sz,
993
                                   &conn->outbuf_flushlen);
994
    }
995
996
997
    if (retval >= 0 && /* Technically, we could survive things like
                          TLS_WANT_WRITE here. But don't bother for now. */
        conn->hold_open_until_flushed && connection_wants_to_flush(conn)) {
998
      if (retval > 0) {
999
1000
        LOG_FN_CONN(conn, (LOG_INFO,LD_NET,
                           "Holding conn (fd %d) open for more flushing.",
For faster browsing, not all history is shown. View entire blame