This file is indexed.

/usr/share/perl5/Mail/SpamAssassin/AsyncLoop.pm is in spamassassin 3.3.2-2ubuntu1.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

  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
# <@LICENSE>
# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements.  See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to you under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License.  You may obtain a copy of the License at:
# 
#     http://www.apache.org/licenses/LICENSE-2.0
# 
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# </@LICENSE>

=head1 NAME

Mail::SpamAssassin::AsyncLoop - scanner asynchronous event loop

=head1 DESCRIPTION

An asynchronous event loop used for long-running operations, performed "in the
background" during the Mail::SpamAssassin::check() scan operation, such as DNS
blocklist lookups.

=head1 METHODS

=over 4

=cut

package Mail::SpamAssassin::AsyncLoop;

use strict;
use warnings;
use bytes;
use re 'taint';

use Time::HiRes qw(time);

use Mail::SpamAssassin;
use Mail::SpamAssassin::Logger;

our @ISA = qw();

# obtain timer resolution if possible
BEGIN {
  use vars qw($timer_resolution);
  eval {
    $timer_resolution = Time::HiRes->can('clock_getres')
      ? Time::HiRes::clock_getres(Time::HiRes::CLOCK_REALTIME())
      : 0.001;  # wild guess, assume resolution is better than 1s
    1;
  } or do {
    $timer_resolution = 1;  # Perl's builtin timer ticks at one second
  };
}

#############################################################################

sub new {
  my $class = shift;
  $class = ref($class) || $class;

  my ($main) = @_;
  my $self = {
    main                => $main,
    queries_started     => 0,
    queries_completed   => 0,
    total_queries_started   => 0,
    total_queries_completed => 0,
    pending_lookups     => { },
    timing_by_query     => { },
  };

  bless ($self, $class);
  $self;
}

# ---------------------------------------------------------------------------

=item $obj = $async->start_lookup($obj)

Register the start of a long-running asynchronous lookup operation. C<$obj>
is a hash reference containing the following items:

=over 4

=item key (required)

A key string, unique to this lookup.  This is what is reported in
debug messages, used as the key for C<get_lookup()>, etc.

=item id (required)

An ID string, also unique to this lookup.  Typically, this is the DNS packet ID
as returned by DnsResolver's C<bgsend> method.  Sadly, the Net::DNS
architecture forces us to keep a separate ID string for this task instead of
reusing C<key> -- if you are not using DNS lookups through DnsResolver, it
should be OK to just reuse C<key>.

=item type (required)

A string, typically one word, used to describe the type of lookup in log
messages, such as C<DNSBL>, C<MX>, C<TXT>.

=item poll_callback (optional)

A code reference, which will be called periodically during the
background-processing period.  If you will be performing an async lookup on a
non-DNS-based service, you will need to implement this so that it checks for
new responses and calls C<set_response_packet()> or C<report_id_complete()> as
appropriate.   DNS-based lookups can leave it undefined, since
DnsResolver::poll_responses() will be called automatically anyway.

The code reference will be called with one argument, the C<$ent> object.

=item completed_callback (optional)

A code reference which will be called when an asynchronous task (e.g. a
DNS lookup) is completed, either normally, or aborted, e.g. by a timeout.

When a task has been reported as completed via C<set_response_packet()>
the response (as provided to C<set_response_packet()>) is stored in
$ent->{response_packet} (possibly undef, its semantics is defined by the
caller). When completion is reported via C<report_id_complete()> or a
task was aborted, the $ent->{response_packet} is guaranteed to be undef.
If it is necessary to distinguish between the last two cases, the
$ent->{status} may be examined for a string 'ABORTING' or 'FINISHED'.

The code reference will be called with one argument, the C<$ent> object.

=item zone (optional)

A zone specification (typically a DNS zone name - e.g. host, domain, or RBL)
which may be used as a key to look up per-zone settings. No semantics on this
parameter is imposed by this module. Currently used to fetch by-zone timeouts.

=item timeout_initial (optional)

An initial value of elapsed time for which we are willing to wait for a
response (time in seconds, floating point value is allowed). When elapsed
time since a query started exceeds the timeout value and there are no other
queries to wait for, the query is aborted. The actual timeout value ranges
from timeout_initial and gradually approaches timeout_min (see next parameter)
as the number of already completed queries approaches the number of all
queries started.

If a caller does not explicitly provide this parameter or its value is
undefined, a default initial timeout value is settable by a configuration
variable rbl_timeout.

If a value of the timeout_initial parameter is below timeout_min, the initial
timeout is set to timeout_min.

=item timeout_min (optional)

A lower bound (in seconds) to which the actual timeout approaches as the
number of queries completed approaches the number of all queries started.
Defaults to 0.2 * timeout_initial.

=back

C<$obj> is returned by this method.

=cut

sub start_lookup {
  my ($self, $ent, $master_deadline) = @_;

  die "oops, no id"   unless $ent->{id}   ne '';
  die "oops, no key"  unless $ent->{key}  ne '';
  die "oops, no type" unless $ent->{type} ne '';

  my $now = time;
  my $key = $ent->{key};
  my $id  = $ent->{id};
  $ent->{status} = 'STARTED';
  $ent->{start_time} = $now  if !defined $ent->{start_time};

  # are there any applicable per-zone settings?
  my $zone = $ent->{zone};
  my $settings;  # a ref to a by-zone or to global settings
  my $conf_by_zone = $self->{main}->{conf}->{by_zone};
  if (defined $zone && $conf_by_zone) {
  # dbg("async: searching for by_zone settings for $zone");
    $zone =~ s/^\.//;  $zone =~ s/\.\z//;  # strip leading and trailing dot
    for (;;) {  # 2.10.example.com, 10.example.com, example.com, com, ''
      if (exists $conf_by_zone->{$zone}) {
        $settings = $conf_by_zone->{$zone};
        dbg("async: applying by_zone settings for $zone");
        last;
      } elsif ($zone eq '') {
        last;
      } else {  # strip one level, careful with address literals
        $zone = ($zone =~ /^( (?: [^.] | \[ (?: \\. | [^\]\\] )* \] )* )
                            \. (.*) \z/xs) ? $2 : '';
      }
    }
  }

  my $t_init = $ent->{timeout_initial};  # application-specified has precedence
  $t_init = $settings->{rbl_timeout}  if $settings && !defined $t_init;
  $t_init = $self->{main}->{conf}->{rbl_timeout}  if !defined $t_init;
  $t_init = 0  if !defined $t_init;      # last-resort default, just in case

  my $t_end = $ent->{timeout_min};       # application-specified has precedence
  $t_end = $settings->{rbl_timeout_min}  if $settings && !defined $t_end;
  $t_end = 0.2 * $t_init  if !defined $t_end;
  $t_end = 0  if $t_end < 0;  # just in case
  $t_init = $t_end  if $t_init < $t_end;

  my $clipped_by_master_deadline = 0;
  if (defined $master_deadline) {
    my $time_avail = $master_deadline - time;
    $time_avail = 0.5  if $time_avail < 0.5;  # give some slack
    if ($t_init > $time_avail) {
      $t_init = $time_avail; $clipped_by_master_deadline = 1;
      $t_end  = $time_avail  if $t_end > $time_avail;
    }
  }
  $ent->{timeout_initial} = $t_init;
  $ent->{timeout_min} = $t_end;

  $ent->{display_id} =  # identifies entry in debug logging and similar
    join(", ", grep { defined }
               map { ref $ent->{$_} ? @{$ent->{$_}} : $ent->{$_} }
               qw(sets rules rulename type key) );

  $self->{queries_started}++;
  $self->{total_queries_started}++;
  $self->{pending_lookups}->{$key} = $ent;

  dbg("async: starting: %s (timeout %.1fs, min %.1fs)%s",
      $ent->{display_id}, $ent->{timeout_initial}, $ent->{timeout_min},
      !$clipped_by_master_deadline ? '' : ', capped by time limit');
  $ent;
}

# ---------------------------------------------------------------------------

=item $obj = $async->get_lookup($key)

Retrieve the pending-lookup object for the given key C<$key>.

If the lookup is complete, this will return C<undef>.

Note that a lookup is still considered "pending" until C<complete_lookups()> is
called, even if it has been reported as complete via C<set_response_packet()>
or C<report_id_complete()>.

=cut

sub get_lookup {
  my ($self, $key) = @_;
  return $self->{pending_lookups}->{$key};
}

# ---------------------------------------------------------------------------

=item @objs = $async->get_pending_lookups()

Retrieve the lookup objects for all pending lookups.

Note that a lookup is still considered "pending" until C<complete_lookups()> is
called, even if it has been reported as complete via C<set_response_packet()>
or C<report_id_complete()>.

=cut

sub get_pending_lookups {
  my ($self) = @_;
  return values %{$self->{pending_lookups}};
}

# ---------------------------------------------------------------------------

=item $async->log_lookups_timing()

Log sorted timing for all completed lookups.

=cut

sub log_lookups_timing {
  my ($self) = @_;
  my $timings = $self->{timing_by_query};
  for my $key (sort { $timings->{$a} <=> $timings->{$b} } keys %$timings) {
    dbg("async: timing: %.3f %s", $timings->{$key}, $key);
  }
}

# ---------------------------------------------------------------------------

=item $alldone = $async->complete_lookups()

Perform a poll of the pending lookups, to see if any are completed; if they
are, their <completed_callback> is called with the entry object for that
lookup.

If there are no lookups remaining, or if too long has elapsed since any results
were returned, C<1> is returned, otherwise C<0>.

=cut

sub complete_lookups {
  my ($self, $timeout, $allow_aborting_of_expired) = @_;
  my $alldone = 0;
  my $anydone = 0;
  my $allexpired = 1;
  my %typecount;

  my $pending = $self->{pending_lookups};
  $self->{queries_started} = 0;
  $self->{queries_completed} = 0;

  my $now = time;

  if (defined $timeout && $timeout > 0 &&
      %$pending && $self->{total_queries_started} > 0)
  {
    # shrink a 'select' timeout if a caller specified unnecessarily long
    # value beyond the latest deadline of any outstanding request;
    # can save needless wait time (up to 1 second in harvest_dnsbl_queries)
    my $r = $self->{total_queries_completed} / $self->{total_queries_started};
    my $r2 = $r * $r;  # 0..1
    my $max_deadline;
    while (my($key,$ent) = each %$pending) {
      my $t_init = $ent->{timeout_initial};
      my $dt = $t_init - ($t_init - $ent->{timeout_min}) * $r2;
      my $deadline = $ent->{start_time} + $dt;
      $max_deadline = $deadline  if !defined $max_deadline ||
                                    $deadline > $max_deadline;
    }
    if (defined $max_deadline) {
      # adjust to timer resolution, only deals with 1s and with fine resolution
      $max_deadline = 1 + int $max_deadline
        if $timer_resolution == 1 && $max_deadline > int $max_deadline;
      my $sufficient_timeout = $max_deadline - $now;
      $sufficient_timeout = 0  if $sufficient_timeout < 0;
      if ($timeout > $sufficient_timeout) {
        dbg("async: reducing select timeout from %.1f to %.1f s",
            $timeout, $sufficient_timeout);
        $timeout = $sufficient_timeout;
      }
    }
  }

  # trap this loop in an eval { } block, as Net::DNS could throw
  # die()s our way; in particular, process_dnsbl_results() has
  # thrown die()s before (bug 3794).
  eval {

    if (%$pending) {  # any outstanding requests still?
      $self->{last_poll_responses_time} = $now;
      my $nfound = $self->{main}->{resolver}->poll_responses($timeout);
      dbg("async: select found %s responses ready (t.o.=%.1f)",
          !$nfound ? 'no' : $nfound,  $timeout);
    }
    $now = time;  # capture new timestamp, after possible sleep in 'select'

    while (my($key,$ent) = each %$pending) {
      my $id = $ent->{id};
      if (defined $ent->{poll_callback}) {  # call a "poll_callback" if exists
        # be nice, provide fresh info to a callback routine
        $ent->{status} = 'FINISHED'  if exists $self->{finished}->{$id};
        # a callback might call set_response_packet() or report_id_complete()
      # dbg("async: calling poll_callback on key $key");
        $ent->{poll_callback}->($ent);
      }
      my $finished = exists $self->{finished}->{$id};
      if ($finished) {
        $anydone = 1;
        delete $self->{finished}->{$id};
        $ent->{status} = 'FINISHED';
        $ent->{finish_time} = $now  if !defined $ent->{finish_time};
        my $elapsed = $ent->{finish_time} - $ent->{start_time};
        dbg("async: completed in %.3f s: %s", $elapsed, $ent->{display_id});

        # call a "completed_callback" sub, if one exists
        if (defined $ent->{completed_callback}) {
        # dbg("async: calling completed_callback on key $key");
          $ent->{completed_callback}->($ent);
        }
        $self->{timing_by_query}->{". $key"} += $elapsed;
        $self->{queries_completed}++;
        $self->{total_queries_completed}++;
        delete $pending->{$key};
      }
    }

    if (%$pending) {  # still any requests outstanding? are they expired?
      my $r =
        !$allow_aborting_of_expired || !$self->{total_queries_started} ? 1.0
        : $self->{total_queries_completed} / $self->{total_queries_started};
      my $r2 = $r * $r;  # 0..1
      while (my($key,$ent) = each %$pending) {
        $typecount{$ent->{type}}++;
        my $t_init = $ent->{timeout_initial};
        my $dt = $t_init - ($t_init - $ent->{timeout_min}) * $r2;
        # adjust to timer resolution, only deals with 1s and fine resolution
        $dt = 1 + int $dt  if $timer_resolution == 1 && $dt > int $dt;
        $allexpired = 0  if $now <= $ent->{start_time} + $dt;
      }
      dbg("async: queries completed: %d, started: %d",
          $self->{queries_completed}, $self->{queries_started});
    }

    # ensure we don't get stuck if a request gets lost in the ether.
    if (! %$pending) {
      $alldone = 1;
    }
    elsif ($allexpired && $allow_aborting_of_expired) {
      # avoid looping forever if we haven't got all results.
      dbg("async: escaping: lost or timed out requests or responses");
      $self->abort_remaining_lookups();
      $alldone = 1;
    }
    else {
      dbg("async: queries active: %s%s at %s",
          join (' ', map { "$_=$typecount{$_}" } sort keys %typecount),
          $allexpired ? ', all expired' : '', scalar(localtime(time)));
      $alldone = 0;
    }
    1;

  } or do {
    my $eval_stat = $@ ne '' ? $@ : "errno=$!";  chomp $eval_stat;
    dbg("async: caught complete_lookups death, aborting: %s", $eval_stat);
    $alldone = 1;      # abort remaining
  };

  return wantarray ? ($alldone,$anydone) : $alldone;
}

# ---------------------------------------------------------------------------

=item $async->abort_remaining_lookups()

Abort any remaining lookups.

=cut

sub abort_remaining_lookups {
  my ($self) = @_;

  my $pending = $self->{pending_lookups};
  my $foundcnt = 0;
  my $now = time;
  while (my($key,$ent) = each %$pending) {
    dbg("async: aborting after %.3f s, %s: %s",
        $now - $ent->{start_time},
        (defined $ent->{timeout_initial} &&
         $now > $ent->{start_time} + $ent->{timeout_initial}
           ? 'past original deadline' : 'deadline shrunk'),
        $ent->{display_id} );
    $foundcnt++;
    $self->{timing_by_query}->{"X $key"} = $now - $ent->{start_time};

    if (defined $ent->{completed_callback}) {
      $ent->{finish_time} = $now  if !defined $ent->{finish_time};
      $ent->{response_packet} = undef;
      $ent->{status} = 'ABORTING';
      $ent->{completed_callback}->($ent);
    }
    delete $pending->{$key};
  }
  dbg("async: aborted %d remaining lookups", $foundcnt)  if $foundcnt > 0;
  delete $self->{last_poll_responses_time};
  $self->{main}->{resolver}->bgabort();
  1;
}

# ---------------------------------------------------------------------------

=item $async->set_response_packet($id, $pkt, $key, $timestamp)

Register a "response packet" for a given query.  C<$id> is the ID for the
query, and must match the C<id> supplied in C<start_lookup()>. C<$pkt> is the
packet object for the response. A parameter C<$key> identifies an entry in a
hash %{$self->{pending_lookups}} where the object which spawned this query can
be found, and through which futher information about the query is accessible.

If this was called, C<$pkt> will be available in the C<completed_callback>
function as C<$ent-<gt>{response_packet}>.

One or the other of C<set_response_packet()> or C<report_id_complete()>
should be called, but not both.

=cut

sub set_response_packet {
  my ($self, $id, $pkt, $key, $timestamp) = @_;
  $self->{finished}->{$id} = 1;  # only key existence matters, any value
  $timestamp = time  if !defined $timestamp;
  my $pending = $self->{pending_lookups};
  if (!defined $key) {  # backwards compatibility with 3.2.3 and older plugins
    # a third-party plugin did not provide $key in a call, search for it:
    if ($id eq $pending->{$id}->{id}) {  # I feel lucky, key==id ?
      $key = $id;
    } else {  # then again, maybe not, be more systematic
      for my $tkey (keys %$pending) {
        if ($id eq $pending->{$tkey}->{id}) { $key = $tkey; last }
      }
    }
    dbg("async: got response on id $id, search found key $key");
  }
  if (!defined $key) {
    info("async: no key, response packet not remembered, id $id");
  } else {
    my $ent = $pending->{$key};
    if ($id ne $ent->{id}) {
      info("async: ignoring response, mismatched id $id, expected $ent->{id}");
    } else {
      $ent->{finish_time} = $timestamp;
      $ent->{response_packet} = $pkt;
    }
  }
  1;
}

=item $async->report_id_complete($id,$key,$key,$timestamp)

Register that a query has completed, and is no longer "pending". C<$id> is the
ID for the query, and must match the C<id> supplied in C<start_lookup()>.

One or the other of C<set_response_packet()> or C<report_id_complete()>
should be called, but not both.

=cut

sub report_id_complete {
  my ($self, $id, $key, $timestamp) = @_;
  $self->set_response_packet($id, undef, $key, $timestamp);
}

# ---------------------------------------------------------------------------

=item $time = $async->last_poll_responses_time()

Get the time of the last call to C<poll_responses()> (which is called
from C<complete_lookups()>.  If C<poll_responses()> was never called or
C<abort_remaining_lookups()> has been called C<last_poll_responses_time()>
will return undef.

=cut

sub last_poll_responses_time {
  my ($self) = @_;
  return $self->{last_poll_responses_time};
}  

1;

=back

=cut