This file is indexed.

/usr/share/perl5/Mail/SpamAssassin/Dns.pm is in spamassassin 3.4.0-6.

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
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
# <@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>

use strict;  # make Test::Perl::Critic happy
package Mail::SpamAssassin::Dns; 1;

package Mail::SpamAssassin::PerMsgStatus;

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

use Mail::SpamAssassin::Conf;
use Mail::SpamAssassin::PerMsgStatus;
use Mail::SpamAssassin::AsyncLoop;
use Mail::SpamAssassin::Constants qw(:ip);
use Mail::SpamAssassin::Util qw(untaint_var am_running_on_windows);

use File::Spec;
use IO::Socket;
use POSIX ":sys_wait_h";

use vars qw{
  $KNOWN_BAD_DIALUP_RANGES @EXISTING_DOMAINS $IS_DNS_AVAILABLE $LAST_DNS_CHECK 
};

# use very well-connected domains (fast DNS response, many DNS servers,
# geographical distribution is a plus, TTL of at least 3600s)
@EXISTING_DOMAINS = qw{
  adelphia.net
  akamai.com
  apache.org
  cingular.com
  colorado.edu
  comcast.net
  doubleclick.com
  ebay.com
  gmx.net
  google.com
  intel.com
  kernel.org
  linux.org
  mit.edu
  motorola.com
  msn.com
  sourceforge.net
  sun.com
  w3.org
  yahoo.com
};

$IS_DNS_AVAILABLE = undef;

#Removed $VERSION per BUG 6422
#$VERSION = 'bogus';     # avoid CPAN.pm picking up razor ver

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

BEGIN {
  # some trickery. Load these modules right here, if possible; that way, if
  # the module exists, we'll get it loaded now.  Very useful to avoid attempted
  # loads later (which will happen).  If we do a fork(), we could wind up
  # attempting to load these modules in *every* subprocess.
  #
# # We turn off strict and warnings, because Net::DNS and Razor both contain
# # crud that -w complains about (perl 5.6.0).  Not that this seems to work,
# # mind ;)
# no strict;
# local ($^W) = 0;

  no warnings;
  eval {
    require Net::DNS;
    require Net::DNS::Resolver;
  };
  eval {
    require MIME::Base64;
  };
  eval {
    require IO::Socket::UNIX;
  };
};

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

sub do_rbl_lookup {
  my ($self, $rule, $set, $type, $host, $subtest) = @_;

  $host =~ s/\.\z//s;  # strip a redundant trailing dot
  my $key = "dns:$type:$host";
  my $existing_ent = $self->{async}->get_lookup($key);

  # only make a specific query once
  if (!$existing_ent) {
    my $ent = {
      key => $key,
      zone => $host,  # serves to fetch other per-zone settings
      type => "DNSBL-".$type,
      sets => [ ],  # filled in below
      rules => [ ], # filled in below
      # id is filled in after we send the query below
    };
    $existing_ent = $self->{async}->bgsend_and_start_lookup(
        $host, $type, undef, $ent,
        sub { my($ent, $pkt) = @_; $self->process_dnsbl_result($ent, $pkt) },
      master_deadline => $self->{master_deadline} );
  }

  if ($existing_ent) {
    # always add set
    push @{$existing_ent->{sets}}, $set;

    # sometimes match or always match
    if (defined $subtest) {
      $self->{dnspost}->{$set}->{$subtest} = $rule;
    } else {
      push @{$existing_ent->{rules}}, $rule;
    }

    $self->{rule_to_rblkey}->{$rule} = $key;
  }
}

# TODO: these are constant so they should only be added once at startup
sub register_rbl_subtest {
  my ($self, $rule, $set, $subtest) = @_;
  $self->{dnspost}->{$set}->{$subtest} = $rule;
}

sub do_dns_lookup {
  my ($self, $rule, $type, $host) = @_;

  $host =~ s/\.\z//s;  # strip a redundant trailing dot
  my $key = "dns:$type:$host";

  my $ent = {
    key => $key,
    zone => $host,  # serves to fetch other per-zone settings
    type => "DNSBL-".$type,
    rules => [ $rule ],
    # id is filled in after we send the query below
  };
  $ent = $self->{async}->bgsend_and_start_lookup(
      $host, $type, undef, $ent,
      sub { my($ent, $pkt) = @_; $self->process_dnsbl_result($ent, $pkt) },
    master_deadline => $self->{master_deadline} );
  $ent;
}

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

sub dnsbl_hit {
  my ($self, $rule, $question, $answer) = @_;

  my $log = "";
  if (substr($rule, 0, 2) eq "__") {
    # don't bother with meta rules
  } elsif ($answer->type eq 'TXT') {
    # txtdata returns a non- zone-file-format encoded result, unlike rdatastr;
    # avoid space-separated RDATA <character-string> fields if possible,
    # txtdata provides a list of strings in a list context since Net::DNS 0.69
    $log = join('',$answer->txtdata);
    local $1;
    $log =~ s{ (?<! [<(\[] ) (https? : // \S+)}{<$1>}xgi;
  } else {  # assuming $answer->type eq 'A'
    local($1,$2,$3,$4,$5);
    if ($question->string =~ m/^((?:[0-9a-fA-F]\.){32})(\S+\w)/) {
      $log = ' listed in ' . lc($2);
      my $ipv6addr = join('', reverse split(/\./, lc $1));
      $ipv6addr =~ s/\G(....)/$1:/g;  chop $ipv6addr;
      $ipv6addr =~ s/:0{1,3}/:/g;
      $log = $ipv6addr . $log;
    } elsif ($question->string =~ m/^(\d+)\.(\d+)\.(\d+)\.(\d+)\.(\S+\w)/) {
      $log = "$4.$3.$2.$1 listed in " . lc($5);
    } else {
      $log = 'listed in ' . $question->string;
    }
  }

  # TODO: this may result in some log messages appearing under the
  # wrong rules, since we could see this sequence: { test one hits,
  # test one's message is logged, test two hits, test one fires again
  # on another IP, test one's message is logged for that other IP --
  # but under test two's heading }.   Right now though it's better
  # than just not logging at all.

  $self->{already_logged} ||= { };
  if ($log && !$self->{already_logged}->{$log}) {
    $self->test_log($log);
    $self->{already_logged}->{$log} = 1;
  }

  if (!$self->{tests_already_hit}->{$rule}) {
    $self->got_hit($rule, "RBL: ", ruletype => "dnsbl");
  }
}

sub dnsbl_uri {
  my ($self, $question, $answer) = @_;

  my $qname = $question->qname;

  # txtdata returns a non- zone-file-format encoded result, unlike rdatastr;
  # avoid space-separated RDATA <character-string> fields if possible,
  # txtdata provides a list of strings in a list context since Net::DNS 0.69
  #
  my $rdatastr = $answer->UNIVERSAL::can('txtdata') ? join('',$answer->txtdata)
                                                    : $answer->rdatastr;
  if (defined $qname && defined $rdatastr) {
    my $qclass = $question->qclass;
    my $qtype = $question->qtype;
    my @vals;
    push(@vals, "class=$qclass") if $qclass ne "IN";
    push(@vals, "type=$qtype") if $qtype ne "A";
    my $uri = "dns:$qname" . (@vals ? "?" . join(";", @vals) : "");
    push @{ $self->{dnsuri}->{$uri} }, $rdatastr;

    dbg("dns: hit <$uri> $rdatastr");
  }
}

# called as a completion routine to bgsend by DnsResolver::poll_responses;
# returns 1 on successful packet processing
sub process_dnsbl_result {
  my ($self, $ent, $pkt) = @_;

  return if !$pkt;
  my $question = ($pkt->question)[0];
  return if !$question;

  my $sets = $ent->{sets} || [];
  my $rules = $ent->{rules};

  # NO_DNS_FOR_FROM
  if ($self->{sender_host} &&
        # fishy, qname should have been "RFC 1035 zone format" -decoded first
      lc($question->qname) eq lc($self->{sender_host}) &&
      $question->qtype =~ /^(?:A|MX)$/ &&
      $pkt->header->rcode =~ /^(?:NXDOMAIN|SERVFAIL)$/ &&
      ++$self->{sender_host_fail} == 2)
  {
    for my $rule (@{$rules}) {
      $self->got_hit($rule, "DNS: ", ruletype => "dns");
    }
  }

  # DNSBL tests are here
  foreach my $answer ($pkt->answer) {
    next if !$answer;
    # track all responses
    $self->dnsbl_uri($question, $answer);
    my $answ_type = $answer->type;
    # TODO: there are some CNAME returns that might be useful
    next if ($answ_type ne 'A' && $answ_type ne 'TXT');
    # skip any A record that isn't on 127/8
    next if ($answ_type eq 'A' && $answer->rdatastr !~ /^127\./);
    for my $rule (@{$rules}) {
      $self->dnsbl_hit($rule, $question, $answer);
    }
    for my $set (@{$sets}) {
      if ($self->{dnspost}->{$set}) {
	$self->process_dnsbl_set($set, $question, $answer);
      }
    }
  }
  return 1;
}

sub process_dnsbl_set {
  my ($self, $set, $question, $answer) = @_;

  # txtdata returns a non- zone-file-format encoded result, unlike rdatastr;
  # avoid space-separated RDATA <character-string> fields if possible,
  # txtdata provides a list of strings in a list context since Net::DNS 0.69
  #
  my $rdatastr = $answer->UNIVERSAL::can('txtdata') ? join('',$answer->txtdata)
                                                    : $answer->rdatastr;

  while (my ($subtest, $rule) = each %{ $self->{dnspost}->{$set} }) {
    next if $self->{tests_already_hit}->{$rule};

    if ($subtest =~ /^\d+\.\d+\.\d+\.\d+$/) {
      # test for exact equality, not a regexp (an IPv4 address)
      $self->dnsbl_hit($rule, $question, $answer)  if $subtest eq $rdatastr;
    }
    # senderbase
    elsif ($subtest =~ s/^sb://) {
      # SB rules are not available to users
      if ($self->{conf}->{user_defined_rules}->{$rule}) {
        dbg("dns: skipping rule '$rule': not supported when user-defined");
        next;
      }

      $rdatastr =~ s/^\d+-//;
      my %sb = ($rdatastr =~ m/(?:^|\|)(\d+)=([^|]+)/g);
      my $undef = 0;
      while ($subtest =~ m/\bS(\d+)\b/g) {
	if (!defined $sb{$1}) {
	  $undef = 1;
	  last;
	}
	$subtest =~ s/\bS(\d+)\b/\$sb{$1}/;
      }

      # untaint. (bug 3325)
      $subtest = untaint_var($subtest);

      $self->got_hit($rule, "SenderBase: ", ruletype => "dnsbl") if !$undef && eval $subtest;
    }
    # bitmask
    elsif ($subtest =~ /^\d+$/) {
      # Bug 6803: response should be within 127.0.0.0/8, ignore otherwise
      if ($rdatastr =~ m/^127\.\d{1,3}\.\d{1,3}\.\d{1,3}$/ &&
	  Mail::SpamAssassin::Util::my_inet_aton($rdatastr) & $subtest)
      {
	$self->dnsbl_hit($rule, $question, $answer);
      }
    }
    # regular expression
    else {
      my $test = qr/$subtest/;
      if ($rdatastr =~ /$test/) {
	$self->dnsbl_hit($rule, $question, $answer);
      }
    }
  }
}

sub harvest_until_rule_completes {
  my ($self, $rule) = @_;

  dbg("dns: harvest_until_rule_completes");
  my $result = 0;

  for (my $first=1;  ; $first=0) {
    # complete_lookups() may call completed_callback(), which may
    # call start_lookup() again (like in Plugin::URIDNSBL)
    my ($alldone,$anydone) =
      $self->{async}->complete_lookups($first ? 0 : 1.0,  1);

    $result = 1  if $self->is_rule_complete($rule);
    last  if $result || $alldone;

    dbg("dns: harvest_until_rule_completes - check_tick");
    $self->{main}->call_plugins ("check_tick", { permsgstatus => $self });
  }

  return $result;
}

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

  dbg("dns: harvest_dnsbl_queries");

  for (my $first=1;  ; $first=0) {
    # complete_lookups() may call completed_callback(), which may
    # call start_lookup() again (like in Plugin::URIDNSBL)

    # the first time around we specify a 0 timeout, which gives
    # complete_lookups a chance to ripe any available results and
    # abort overdue requests, without needlessly waiting for more

    my ($alldone,$anydone) =
      $self->{async}->complete_lookups($first ? 0 : 1.0,  1);

    last  if $alldone;

    dbg("dns: harvest_dnsbl_queries - check_tick");
    $self->{main}->call_plugins ("check_tick", { permsgstatus => $self });
  }

  # explicitly abort anything left
  $self->{async}->abort_remaining_lookups();
  $self->{async}->log_lookups_timing();
  $self->mark_all_async_rules_complete();
  1;
}

# collect and process whatever DNS responses have already arrived,
# don't waste time waiting for more, don't poll too often.
# don't abort any queries even if overdue, 
sub harvest_completed_queries {
  my ($self) = @_;

  # don't bother collecting responses too often
  my $last_poll_time = $self->{async}->last_poll_responses_time();
  return if defined $last_poll_time && time - $last_poll_time < 0.1;

  my ($alldone,$anydone) = $self->{async}->complete_lookups(0, 0);
  if ($anydone) {
    dbg("dns: harvested completed queries");
#   $self->{main}->call_plugins ("check_tick", { permsgstatus => $self });
  }
}

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

  # DNS URIs
  my $rbl_tag = $self->{tag_data}->{RBL};  # just in case, should be empty
  $rbl_tag = ''  if !defined $rbl_tag;
  while (my ($dnsuri, $answers) = each %{ $self->{dnsuri} }) {
    # when parsing, look for elements of \".*?\" or \S+ with ", " as separator
    $rbl_tag .= "<$dnsuri>" . " [" . join(", ", @{ $answers }) . "]\n";
  }
  if (defined $rbl_tag && $rbl_tag ne '') {
    chomp $rbl_tag;
    $self->set_tag('RBL', $rbl_tag);
  }
}

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

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

  $self->set_rbl_tag_data();

  delete $self->{dnspost};
  delete $self->{dnsuri};
}

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

sub load_resolver {
  my ($self) = @_;
  $self->{resolver} = $self->{main}->{resolver};
  return $self->{resolver}->load_resolver();
}

sub clear_resolver {
  my ($self) = @_;
  dbg("dns: clear_resolver");
  $self->{main}->{resolver}->{res} = undef;
  return 0;
}

sub lookup_ns {
  my ($self, $dom) = @_;

  return unless $self->load_resolver();
  return if ($self->server_failed_to_respond_for_domain ($dom));

  my $nsrecords;
  dbg("dns: looking up NS for '$dom'");

  eval {
    my $query = $self->{resolver}->send($dom, 'NS');
    my @nses;
    if ($query) {
      foreach my $rr ($query->answer) {
        if ($rr->type eq "NS") { push (@nses, $rr->nsdname); }
      }
    }
    $nsrecords = [ @nses ];
    1;
  } or do {
    my $eval_stat = $@ ne '' ? $@ : "errno=$!";  chomp $eval_stat;
    dbg("dns: NS lookup failed horribly, perhaps bad resolv.conf setting? (%s)", $eval_stat);
    return;
  };

  $nsrecords;
}

sub is_dns_available {
  my ($self) = @_;
  my $dnsopt = $self->{conf}->{dns_available};
  my $dnsint = $self->{conf}->{dns_test_interval} || 600;
  my @domains;

  $LAST_DNS_CHECK ||= 0;
  my $diff = time() - $LAST_DNS_CHECK;

  # undef $IS_DNS_AVAILABLE if we should be testing for
  # working DNS and our check interval time has passed
  if ($dnsopt eq "test" && $diff > $dnsint) {
    $IS_DNS_AVAILABLE = undef;
    dbg("dns: is_dns_available() last checked %.1f seconds ago; re-checking",
        $diff);
  }

  return $IS_DNS_AVAILABLE if (defined $IS_DNS_AVAILABLE);
  $LAST_DNS_CHECK = time();

  $IS_DNS_AVAILABLE = 0;
  if ($dnsopt eq "no") {
    dbg("dns: dns_available set to no in config file, skipping test");
    return $IS_DNS_AVAILABLE;
  }

  # Even if "dns_available" is explicitly set to "yes", we want to ignore
  # DNS if we're only supposed to be looking at local tests.
  goto done if ($self->{main}->{local_tests_only});

  # Check version numbers - runtime check only
  if (defined $Net::DNS::VERSION) {
    use version 0.77;
    if (am_running_on_windows()) {
      if (version->parse($Net::DNS::VERSION) < version->parse('0.46')) {
	warn("dns: Net::DNS version is $Net::DNS::VERSION, but need 0.46 for Win32");
	return $IS_DNS_AVAILABLE;
      }
    }
    else {
      if (version->parse($Net::DNS::VERSION) < version->parse('0.34')) {
	warn("dns: Net::DNS version is $Net::DNS::VERSION, but need 0.34");
	return $IS_DNS_AVAILABLE;
      }
    }
  }

  $self->clear_resolver();
  goto done unless $self->load_resolver();

  if ($dnsopt eq "yes") {
    # optionally shuffle the list of nameservers to distribute the load
    if ($self->{conf}->{dns_options}->{rotate}) {
      my @nameservers = $self->{resolver}->available_nameservers();
      Mail::SpamAssassin::Util::fisher_yates_shuffle(\@nameservers);
      dbg("dns: shuffled NS list: " . join(", ", @nameservers));
      $self->{resolver}->available_nameservers(@nameservers);
    }
    $IS_DNS_AVAILABLE = 1;
    dbg("dns: dns_available set to yes in config file, skipping test");
    return $IS_DNS_AVAILABLE;
  }

  if ($dnsopt =~ /^test:\s*(\S.*)$/) {
    @domains = split (/\s+/, $1);
    dbg("dns: looking up NS records for user specified domains: %s",
        join(", ", @domains));
  } else {
    @domains = @EXISTING_DOMAINS;
    dbg("dns: looking up NS records for built-in domains");
  }

  # do the test with a full set of configured nameservers
  my @nameservers = $self->{resolver}->configured_nameservers();

  # optionally shuffle the list of nameservers to distribute the load
  if ($self->{conf}->{dns_options}->{rotate}) {
    Mail::SpamAssassin::Util::fisher_yates_shuffle(\@nameservers);
    dbg("dns: shuffled NS list, testing: " . join(", ", @nameservers));
  } else {
    dbg("dns: testing resolver nameservers: " . join(", ", @nameservers));
  }

  # Try the different nameservers here and collect a list of working servers
  my @good_nameservers;
  foreach my $ns (@nameservers) {
    $self->{resolver}->available_nameservers($ns);  # try just this one
    for (my $retry = 3; $retry > 0 && @domains; $retry--) {
      my $domain = splice(@domains, rand(@domains), 1);
      dbg("dns: trying ($retry) $domain, server $ns ...");
      my $result = $self->lookup_ns($domain);
      $self->{resolver}->finish_socket();
      if (!$result) {
        dbg("dns: NS lookup of $domain using $ns failed horribly, ".
            "may not be a valid nameserver");
        last;
      } elsif (!@$result) {
        dbg("dns: NS lookup of $domain using $ns failed, no results found");
      } else {
        dbg("dns: NS lookup of $domain using $ns succeeded => DNS available".
            " (set dns_available to override)");
        push(@good_nameservers, $ns);
        last;
      }
    }
  }

  if (!@good_nameservers) {
    dbg("dns: all NS queries failed => DNS unavailable ".
        "(set dns_available to override)");
  } else {
    $IS_DNS_AVAILABLE = 1;
    dbg("dns: NS list: ".join(", ", @good_nameservers));
    $self->{resolver}->available_nameservers(@good_nameservers);
  }

done:
  # jm: leaving this in!
  dbg("dns: is DNS available? " . $IS_DNS_AVAILABLE);
  return $IS_DNS_AVAILABLE;
}

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

sub server_failed_to_respond_for_domain {
  my ($self, $dom) = @_;
  if ($self->{dns_server_too_slow}->{$dom}) {
    dbg("dns: server for '$dom' failed to reply previously, not asking again");
    return 1;
  }
  return 0;
}

sub set_server_failed_to_respond_for_domain {
  my ($self, $dom) = @_;
  dbg("dns: server for '$dom' failed to reply, marking as bad");
  $self->{dns_server_too_slow}->{$dom} = 1;
}

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

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

  dbg("dns: entering helper-app run mode");
  $self->{old_slash} = $/;              # Razor pollutes this
  %{$self->{old_env}} = ();
  if ( %ENV ) {
    # undefined values in %ENV can result due to autovivification elsewhere,
    # this prevents later possible warnings when we restore %ENV
    while (my ($key, $value) = each %ENV) {
      $self->{old_env}->{$key} = $value if defined $value;
    }
  }

  Mail::SpamAssassin::Util::clean_path_in_taint_mode();

  my $newhome;
  if ($self->{main}->{home_dir_for_helpers}) {
    $newhome = $self->{main}->{home_dir_for_helpers};
  } else {
    # use spamd -u user's home dir
    $newhome = (Mail::SpamAssassin::Util::portable_getpwuid ($>))[7];
  }

  if ($newhome) {
    $ENV{'HOME'} = Mail::SpamAssassin::Util::untaint_file_path ($newhome);
  }

  # enforce SIGCHLD as DEFAULT; IGNORE causes spurious kernel warnings
  # on Red Hat NPTL kernels (bug 1536), and some users of the
  # Mail::SpamAssassin modules set SIGCHLD to be a fatal signal
  # for some reason! (bug 3507)
  $self->{old_sigchld_handler} = $SIG{CHLD};
  $SIG{CHLD} = 'DEFAULT';
}

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

  dbg("dns: leaving helper-app run mode");
  $/ = $self->{old_slash};
  %ENV = %{$self->{old_env}};

  if (defined $self->{old_sigchld_handler}) {
    $SIG{CHLD} = $self->{old_sigchld_handler};
  } else {
    # if SIGCHLD has never been explicitly set, it's returned as undef.
    # however, when *setting* SIGCHLD, using undef(%) or assigning to an
    # undef value produces annoying 'Use of uninitialized value in scalar
    # assignment' warnings.  That's silly.  workaround:
    $SIG{CHLD} = 'DEFAULT';
  }
}

# note: this must be called before leave_helper_run_mode() is called,
# as the SIGCHLD signal must be set to DEFAULT for it to work.
sub cleanup_kids {
  my ($self, $pid) = @_;
  
  if ($SIG{CHLD} && $SIG{CHLD} ne 'IGNORE') {	# running from spamd
    waitpid ($pid, 0);
  }
}

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

sub register_async_rule_start {
  my ($self, $rule) = @_;
  dbg("dns: $rule lookup start");
  $self->{rule_to_rblkey}->{$rule} = '*ASYNC_START';
}

sub register_async_rule_finish {
  my ($self, $rule) = @_;
  dbg("dns: $rule lookup finished");
  delete $self->{rule_to_rblkey}->{$rule};
}

sub mark_all_async_rules_complete {
  my ($self) = @_;
  $self->{rule_to_rblkey} = { };
}

sub is_rule_complete {
  my ($self, $rule) = @_;

  my $key = $self->{rule_to_rblkey}->{$rule};
  if (!defined $key) {
    # dbg("dns: $rule lookup complete, not in list");
    return 1;
  }

  if ($key eq '*ASYNC_START') {
    dbg("dns: $rule lookup not yet complete");
    return 0;       # not yet complete
  }

  my $ent = $self->{async}->get_lookup($key);
  if (!defined $ent) {
    dbg("dns: $rule lookup complete, $key no longer pending");
    return 1;
  }

  dbg("dns: $rule lookup not yet complete");
  return 0;         # not yet complete
}

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

# interface called by SPF plugin
sub check_for_from_dns {
  my ($self, $pms) = @_;
  if (defined $pms->{sender_host_fail}) {
    return ($pms->{sender_host_fail} == 2); # both MX and A need to fail
  }
}

1;