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Revision 1.28 by root, Sat Apr 20 15:37:27 2019 UTC vs.
Revision 1.45 by root, Sun Apr 21 02:45:12 2019 UTC

… …
8 8
9 my $ber = ber_decode $buf, $Convert::BER::XS::SNMP_PROFILE 9 my $ber = ber_decode $buf, $Convert::BER::XS::SNMP_PROFILE
10 or die "unable to decode SNMP message"; 10 or die "unable to decode SNMP message";
11 11
12 # The above results in a data structure consisting of 12 # The above results in a data structure consisting of
13 # (class, tag, # constructed, data) 13 # (class, tag, flags, data)
14 # tuples. Below is such a message, SNMPv1 trap 14 # tuples. Below is such a message, SNMPv1 trap
15 # with a Cisco mac change notification. 15 # with a Cisco mac change notification.
16 # Did you know that Cisco is in the news almost 16 # Did you know that Cisco is in the news almost
17 # every week because of some backdoor password 17 # every week because of some backdoor password
18 # or other extremely stupid security bug? 18 # or other extremely stupid security bug?
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36 [ ASN_UNIVERSAL, ASN_OCTET_STRING, 0, "...data..." # the value 36 [ ASN_UNIVERSAL, ASN_OCTET_STRING, 0, "...data..." # the value
37 ] 37 ]
38 ] 38 ]
39 ], 39 ],
40 ... 40 ...
41 # let's dump it, for debugging
42
43 ber_dump $ber, $Convert::BER::XS::SNMP_PROFILE;
41 44
42 # let's decode it a bit with some helper functions 45 # let's decode it a bit with some helper functions
43 46
44 my $msg = ber_is_seq $ber 47 my $msg = ber_is_seq $ber
45 or die "SNMP message does not start with a sequence"; 48 or die "SNMP message does not start with a sequence";
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113 ASN_UNIVERSAL ASN_APPLICATION ASN_CONTEXT ASN_PRIVATE 116 ASN_UNIVERSAL ASN_APPLICATION ASN_CONTEXT ASN_PRIVATE
114 117
115ASN tag values (some of which are aliases, such as C<ASN_OID>). Their 118ASN tag values (some of which are aliases, such as C<ASN_OID>). Their
116numerical value corresponds exactly to the numbers used in BER/X.690. 119numerical value corresponds exactly to the numbers used in BER/X.690.
117 120
118 ASN_BOOLEAN ASN_INTEGER ASN_BIT_STRING ASN_OCTET_STRING ASN_NULL ASN_OBJECT_IDENTIFIER 121 ASN_BOOLEAN ASN_INTEGER ASN_BIT_STRING ASN_OCTET_STRING ASN_NULL ASN_OID
119 ASN_OBJECT_DESCRIPTOR ASN_OID ASN_EXTERNAL ASN_REAL ASN_SEQUENCE ASN_ENUMERATED 122 ASN_OBJECT_IDENTIFIER ASN_OBJECT_DESCRIPTOR ASN_EXTERNAL ASN_REAL ASN_SEQUENCE ASN_ENUMERATED
120 ASN_EMBEDDED_PDV ASN_UTF8_STRING ASN_RELATIVE_OID ASN_SET ASN_NUMERIC_STRING 123 ASN_EMBEDDED_PDV ASN_UTF8_STRING ASN_RELATIVE_OID ASN_SET ASN_NUMERIC_STRING
121 ASN_PRINTABLE_STRING ASN_TELETEX_STRING ASN_T61_STRING ASN_VIDEOTEX_STRING ASN_IA5_STRING 124 ASN_PRINTABLE_STRING ASN_TELETEX_STRING ASN_T61_STRING ASN_VIDEOTEX_STRING ASN_IA5_STRING
122 ASN_ASCII_STRING ASN_UTC_TIME ASN_GENERALIZED_TIME ASN_GRAPHIC_STRING ASN_VISIBLE_STRING 125 ASN_ASCII_STRING ASN_UTC_TIME ASN_GENERALIZED_TIME ASN_GRAPHIC_STRING ASN_VISIBLE_STRING
123 ASN_ISO646_STRING ASN_GENERAL_STRING ASN_UNIVERSAL_STRING ASN_CHARACTER_STRING ASN_BMP_STRING 126 ASN_ISO646_STRING ASN_GENERAL_STRING ASN_UNIVERSAL_STRING ASN_CHARACTER_STRING ASN_BMP_STRING
124 127
… …
134 137
135Constants only relevant to SNMP. These are the tag values used by SNMP in 138Constants only relevant to SNMP. These are the tag values used by SNMP in
136the C<ASN_APPLICATION> namespace and have the exact numerical value as in 139the C<ASN_APPLICATION> namespace and have the exact numerical value as in
137BER/RFC 2578. 140BER/RFC 2578.
138 141
139 SNMP_IPADDRESS SNMP_COUNTER32 SNMP_UNSIGNED32 SNMP_TIMETICKS SNMP_OPAQUE SNMP_COUNTER64 142 SNMP_IPADDRESS SNMP_COUNTER32 SNMP_UNSIGNED32 SNMP_GAUGE32
143 SNMP_TIMETICKS SNMP_OPAQUE SNMP_COUNTER64
140 144
141=item C<:decode> 145=item C<:decode>
142 146
143C<ber_decode> and the match helper functions: 147C<ber_decode> and the match helper functions:
144 148
149 ber_decode ber-decode_prefix
145 ber_decode ber_is ber_is_seq ber_is_int ber_is_oid 150 ber_is ber_is_seq ber_is_int ber_is_oid
151 ber_dump
146 152
147=item C<:encode> 153=item C<:encode>
148 154
149C<ber_encode> and the construction helper functions: 155C<ber_encode> and the construction helper functions:
150 156
151 ber_encode ber_int 157 ber_encode
158 ber_int
152 159
153=back 160=back
154 161
155=head2 ASN.1/BER/DER/... BASICS 162=head2 ASN.1/BER/DER/... BASICS
156 163
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252 259
253=head2 DECODING AND ENCODING 260=head2 DECODING AND ENCODING
254 261
255=over 262=over
256 263
257=item $tuple = ber_decoded $bindata[, $profile] 264=item $tuple = ber_decode $bindata[, $profile]
258 265
259Decodes binary BER data in C<$bindata> and returns the resulting BER 266Decodes binary BER data in C<$bindata> and returns the resulting BER
260tuple. Croaks on any decoding error, so the returned C<$tuple> is always 267tuple. Croaks on any decoding error, so the returned C<$tuple> is always
261valid. 268valid.
262 269
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275 282
276Example: as above, but use the provided SNMP profile. 283Example: as above, but use the provided SNMP profile.
277 284
278 $tuple = ber_encode $data, $Convert::BER::XS::SNMP_PROFILE; 285 $tuple = ber_encode $data, $Convert::BER::XS::SNMP_PROFILE;
279 286
287=item ($tuple, $bytes) = ber_decode_prefix $bindata[, $profile]
288
289Works like C<ber_decode>, except it doesn't croak when there is data after
290the BER data, but instead returns the decoded value and the number of
291bytes it decoded.
292
293This is useful when you have BER data at the start of a buffer and other
294data after, and you need to find the length.
295
296Also, since BER is self-delimited, this can be used to decode multiple BER
297values joined together.
298
280=item $bindata = ber_encode $tuple[, $profile] 299=item $bindata = ber_encode $tuple[, $profile]
281 300
282Encodes the BER tuple into a BER/DER data structure. AS with 301Encodes the BER tuple into a BER/DER data structure. AS with
283Cyber_decode>, an optional profile can be given. 302Cyber_decode>, an optional profile can be given.
284 303
… …
303a ease-of-use exception, they usually also accept C<undef> instead of a 322a ease-of-use exception, they usually also accept C<undef> instead of a
304tuple reference, in which case they silently fail to match. 323tuple reference, in which case they silently fail to match.
305 324
306=over 325=over
307 326
308=item $bool = ber_is $tuple, $class, $tag, $constructed, $data 327=item $bool = ber_is $tuple, $class, $tag, $flags, $data
309 328
310This takes a BER C<$tuple> and matches its elements against the provided 329This takes a BER C<$tuple> and matches its elements against the provided
311values, all of which are optional - values that are either missing or 330values, all of which are optional - values that are either missing or
312C<undef> will be ignored, the others will be matched exactly (e.g. as if 331C<undef> will be ignored, the others will be matched exactly (e.g. as if
313you used C<==> or C<eq> (for C<$data>)). 332you used C<==> or C<eq> (for C<$data>)).
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393use Exporter qw(import); 412use Exporter qw(import);
394 413
395our $VERSION; 414our $VERSION;
396 415
397BEGIN { 416BEGIN {
398 $VERSION = 0.8; 417 $VERSION = '1.0';
399 XSLoader::load __PACKAGE__, $VERSION; 418 XSLoader::load __PACKAGE__, $VERSION;
400} 419}
401 420
402our %EXPORT_TAGS = ( 421our %EXPORT_TAGS = (
403 const_index => [qw( 422 const_index => [qw(
404 BER_CLASS BER_TAG BER_FLAGS BER_DATA 423 BER_CLASS BER_TAG BER_FLAGS BER_DATA
405 )], 424 )],
425 const_asn_class => [qw(
426 ASN_UNIVERSAL ASN_APPLICATION ASN_CONTEXT ASN_PRIVATE
427 )],
406 const_asn => [qw( 428 const_asn_tag => [qw(
407 ASN_BOOLEAN ASN_INTEGER ASN_BIT_STRING ASN_OCTET_STRING ASN_NULL ASN_OBJECT_IDENTIFIER 429 ASN_BOOLEAN ASN_INTEGER ASN_BIT_STRING ASN_OCTET_STRING ASN_NULL ASN_OID ASN_OBJECT_IDENTIFIER
408 ASN_OBJECT_DESCRIPTOR ASN_OID ASN_EXTERNAL ASN_REAL ASN_SEQUENCE ASN_ENUMERATED 430 ASN_OBJECT_DESCRIPTOR ASN_EXTERNAL ASN_REAL ASN_SEQUENCE ASN_ENUMERATED
409 ASN_EMBEDDED_PDV ASN_UTF8_STRING ASN_RELATIVE_OID ASN_SET ASN_NUMERIC_STRING 431 ASN_EMBEDDED_PDV ASN_UTF8_STRING ASN_RELATIVE_OID ASN_SET ASN_NUMERIC_STRING
410 ASN_PRINTABLE_STRING ASN_TELETEX_STRING ASN_T61_STRING ASN_VIDEOTEX_STRING ASN_IA5_STRING 432 ASN_PRINTABLE_STRING ASN_TELETEX_STRING ASN_T61_STRING ASN_VIDEOTEX_STRING ASN_IA5_STRING
411 ASN_ASCII_STRING ASN_UTC_TIME ASN_GENERALIZED_TIME ASN_GRAPHIC_STRING ASN_VISIBLE_STRING 433 ASN_ASCII_STRING ASN_UTC_TIME ASN_GENERALIZED_TIME ASN_GRAPHIC_STRING ASN_VISIBLE_STRING
412 ASN_ISO646_STRING ASN_GENERAL_STRING ASN_UNIVERSAL_STRING ASN_CHARACTER_STRING ASN_BMP_STRING 434 ASN_ISO646_STRING ASN_GENERAL_STRING ASN_UNIVERSAL_STRING ASN_CHARACTER_STRING ASN_BMP_STRING
413
414 ASN_UNIVERSAL ASN_APPLICATION ASN_CONTEXT ASN_PRIVATE
415 )], 435 )],
416 const_ber_type => [qw( 436 const_ber_type => [qw(
417 BER_TYPE_BYTES BER_TYPE_UTF8 BER_TYPE_UCS2 BER_TYPE_UCS4 BER_TYPE_INT 437 BER_TYPE_BYTES BER_TYPE_UTF8 BER_TYPE_UCS2 BER_TYPE_UCS4 BER_TYPE_INT
418 BER_TYPE_OID BER_TYPE_RELOID BER_TYPE_NULL BER_TYPE_BOOL BER_TYPE_REAL 438 BER_TYPE_OID BER_TYPE_RELOID BER_TYPE_NULL BER_TYPE_BOOL BER_TYPE_REAL
419 BER_TYPE_IPADDRESS BER_TYPE_CROAK 439 BER_TYPE_IPADDRESS BER_TYPE_CROAK
420 )], 440 )],
421 const_snmp => [qw( 441 const_snmp => [qw(
422 SNMP_IPADDRESS SNMP_COUNTER32 SNMP_UNSIGNED32 SNMP_TIMETICKS SNMP_OPAQUE SNMP_COUNTER64 442 SNMP_IPADDRESS SNMP_COUNTER32 SNMP_GAUGE32 SNMP_UNSIGNED32
443 SNMP_TIMETICKS SNMP_OPAQUE SNMP_COUNTER64
423 )], 444 )],
424 decode => [qw( 445 decode => [qw(
425 ber_decode 446 ber_decode ber_decode_prefix
426 ber_is ber_is_seq ber_is_int ber_is_oid 447 ber_is ber_is_seq ber_is_int ber_is_oid
448 ber_dump
427 )], 449 )],
428 encode => [qw( 450 encode => [qw(
429 ber_encode 451 ber_encode
430 ber_int 452 ber_int
431 )], 453 )],
432); 454);
433 455
434our @EXPORT_OK = map @$_, values %EXPORT_TAGS; 456our @EXPORT_OK = map @$_, values %EXPORT_TAGS;
435 457
436$EXPORT_TAGS{all} = \@EXPORT_OK; 458$EXPORT_TAGS{all} = \@EXPORT_OK;
459$EXPORT_TAGS{const_asn} = [map @{ $EXPORT_TAGS{$_} }, qw(const_asn_class const_asn_tag)];
437$EXPORT_TAGS{const} = [map @{ $EXPORT_TAGS{$_} }, qw(const_index const_asn)]; 460$EXPORT_TAGS{const} = [map @{ $EXPORT_TAGS{$_} }, qw(const_index const_asn)];
461
462our $DEFAULT_PROFILE = new Convert::BER::XS::Profile;
463
464$DEFAULT_PROFILE->_set_default;
465
466# additional SNMP application types
467our $SNMP_PROFILE = new Convert::BER::XS::Profile;
468
469$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_IPADDRESS , BER_TYPE_IPADDRESS);
470$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_COUNTER32 , BER_TYPE_INT);
471$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_UNSIGNED32, BER_TYPE_INT);
472$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_TIMETICKS , BER_TYPE_INT);
473$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_OPAQUE , BER_TYPE_IPADDRESS);
474
475=head2 DEBUGGING
476
477To aid debugging, you cna call the C<ber_dump> function to print a "nice"
478representation to STDOUT.
479
480=over
481
482=item ber_dump $tuple[, $profile[, $prefix]]
483
484In addition to specifying the BER C<$tuple> to dump, youc an also specify
485a C<$profile> and a C<$prefix> string that is printed in front of each line.
486
487If C<$profile> is C<$Convert::BER::XS::SNMP_PROFILE>, then C<ber_dump>
488will try to improve its output for SNMP data.
489
490The output usually contains three columns, the "human readable" tag, the
491BER type used to decode it, and the data value.
492
493This function is somewhat slow and uses a number of heuristics and tricks,
494so it really is only suitable for debug prints.
495
496Example output:
497
498 SEQUENCE
499 | OCTET_STRING bytes 800063784300454045045400000001
500 | OCTET_STRING bytes
501 | CONTEXT (7) bytes CONSTRUCTED
502 | | INTEGER int 1058588941
503 | | INTEGER int 0
504 | | INTEGER int 0
505 | | SEQUENCE
506 | | | SEQUENCE
507 | | | | OID oid 1.3.6.1.2.1.1.3.0
508 | | | | TIMETICKS int 638085796
509
510=back
511
512=cut
513
514# reverse enum, very slow and ugly hack
515sub _re {
516 my ($export_tag, $value) = @_;
517
518 for my $symbol (@{ $EXPORT_TAGS{$export_tag} }) {
519 $value == eval $symbol
520 and return $symbol;
521 }
522
523 "($value)"
524}
525
526$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_COUNTER64 , BER_TYPE_INT);
527
528sub _ber_dump {
529 my ($ber, $profile, $indent) = @_;
530
531 if (my $seq = ber_is_seq $ber) {
532 printf "%sSEQUENCE\n", $indent;
533 &_ber_dump ($_, $profile, "$indent| ")
534 for @$seq;
535 } else {
536 my $asn = $ber->[BER_CLASS] == ASN_UNIVERSAL;
537
538 my $class = _re const_asn_class => $ber->[BER_CLASS];
539 my $tag = $asn ? _re const_asn_tag => $ber->[BER_TAG] : $ber->[BER_TAG];
540 my $type = _re const_ber_type => $profile->get ($ber->[BER_CLASS], $ber->[BER_TAG]);
541 my $data = $ber->[BER_DATA];
542
543 if ($profile == $SNMP_PROFILE and $ber->[BER_CLASS] == ASN_APPLICATION) {
544 $tag = _re const_snmp => $ber->[BER_TAG];
545 } elsif (!$asn) {
546 $tag = "$class ($tag)";
547 }
548
549 $class =~ s/^ASN_//;
550 $tag =~ s/^(ASN_|SNMP_)//;
551 $type =~ s/^BER_TYPE_//;
552
553 if ($ber->[BER_FLAGS]) {
554 printf "$indent%-16.16s %-6.6s CONSTRUCTED\n", $tag, lc $type;
555 &_ber_dump ($_, $profile, "$indent| ")
556 for @$data;
557 } else {
558 if ($data =~ y/\x20-\x7e//c / (length $data || 1) > 0.2 or $data =~ /\x00./s) {
559 # assume binary
560 $data = unpack "H*", $data;
561 } else {
562 $data =~ s/[^\x20-\x7e]/./g;
563 $data = "\"$data\"" if $type =~ /string/i || !length $data;
564 }
565
566 substr $data, 40, 1e9, "..." if 40 < length $data;
567
568 printf "$indent%-16.16s %-6.6s %s\n", $tag, lc $type, $data;
569 }
570 }
571}
572
573sub ber_dump($;$$) {
574 _ber_dump $_[0], $_[1] || $DEFAULT_PROFILE, $_[2];
575}
438 576
439=head1 PROFILES 577=head1 PROFILES
440 578
441While any BER data can be correctly encoded and decoded out of the box, it 579While any BER data can be correctly encoded and decoded out of the box, it
442can be inconvenient to have to manually decode some values into a "better" 580can be inconvenient to have to manually decode some values into a "better"
… …
503 641
504Returns the BER type mapped to the given C<$class>/C<$tag> combination. 642Returns the BER type mapped to the given C<$class>/C<$tag> combination.
505 643
506=back 644=back
507 645
508=head2 BER TYPES 646=head2 BER Types
509 647
510This lists the predefined BER types - you can map any C<CLASS>/C<TAG> 648This lists the predefined BER types. BER types are formatters used
511combination to any C<BER_TYPE_*>. 649internally to format and encode BER values. You can assign any C<BER_TYPE>
650to any C<CLASS>/C<TAG> combination tgo change how that tag is decoded or
651encoded.
512 652
513=over 653=over
514 654
515=item C<BER_TYPE_BYTES> 655=item C<BER_TYPE_BYTES>
516 656
… …
582C<BER_TYPE_BYTES>. When you don't want that but instead prefer a hard 722C<BER_TYPE_BYTES>. When you don't want that but instead prefer a hard
583error for some types, then C<BER_TYPE_CROAK> is for you. 723error for some types, then C<BER_TYPE_CROAK> is for you.
584 724
585=back 725=back
586 726
587=cut 727=head2 Example Profile
588 728
589our $DEFAULT_PROFILE = new Convert::BER::XS::Profile; 729The following creates a profile suitable for SNMP - it's exactly identical
730to the C<$Convert::BER::XS::SNMP_PROFILE> profile.
731
590our $SNMP_PROFILE = new Convert::BER::XS::Profile; 732 our $SNMP_PROFILE = new Convert::BER::XS::Profile;
591 733
592# additional SNMP application types
593$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_IPADDRESS , BER_TYPE_IPADDRESS); 734 $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_IPADDRESS , BER_TYPE_IPADDRESS);
594$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_COUNTER32 , BER_TYPE_INT); 735 $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_COUNTER32 , BER_TYPE_INT);
595$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_UNSIGNED32, BER_TYPE_INT); 736 $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_UNSIGNED32, BER_TYPE_INT);
596$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_TIMETICKS , BER_TYPE_INT); 737 $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_TIMETICKS , BER_TYPE_INT);
597$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_OPAQUE , BER_TYPE_IPADDRESS); 738 $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_OPAQUE , BER_TYPE_IPADDRESS);
598$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_COUNTER64 , BER_TYPE_INT); 739 $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_COUNTER64 , BER_TYPE_INT);
599
600$DEFAULT_PROFILE->_set_default;
601
6021;
603 740
604=head2 LIMITATIONS/NOTES 741=head2 LIMITATIONS/NOTES
605 742
606This module can only en-/decode 64 bit signed and unsigned integers, and 743This module can only en-/decode 64 bit signed and unsigned integers, and
607only when your perl supports those. 744only when your perl supports those. So no UUID OIDs for now.
608 745
609This module does not generally care about ranges, i.e. it will happily 746This module does not generally care about ranges, i.e. it will happily
610de-/encode 64 bit integers into an C<ASN_INTEGER> value, or a negative 747de-/encode 64 bit integers into an C<ASN_INTEGER> value, or a negative
611number into an C<SNMP_COUNTER64>. 748number into an C<SNMP_COUNTER64>.
612 749
613OBJECT IDENTIFIEERs cannot have unlimited length, although the limit is 750OBJECT IDENTIFIEERs cannot have unlimited length, although the limit is
614much larger than e.g. the one imposed by SNMP or other protocols,a nd is 751much larger than e.g. the one imposed by SNMP or other protocols, and is
615about 4kB. 752about 4kB.
616 753
617Indefinite length encoding is not supported. 754Indefinite length encoding is not supported.
618 755
619Constructed strings are decoded just fine, but there should be a way to 756Constructed strings are decoded just fine, but there should be a way to
620join them for convenience. 757join them for convenience.
621 758
622REAL values are not supported and will currently croak. 759REAL values are not supported and will currently croak.
623 760
761The encoder and decoder tend to accept more formats than should be
762strictly supported - security sensitive applications are strongly advised
763to review the code first.
764
624This module has undergone little to no testing so far. 765This module has undergone little to no testing so far.
625 766
626=head2 ITHREADS SUPPORT 767=head2 ITHREADS SUPPORT
627 768
628This module is unlikely to work when the (officially discouraged) ithreads 769This module is unlikely to work when the (officially discouraged) ithreads
… …
633 Marc Lehmann <schmorp@schmorp.de> 774 Marc Lehmann <schmorp@schmorp.de>
634 http://software.schmorp.de/pkg/Convert-BER-XS 775 http://software.schmorp.de/pkg/Convert-BER-XS
635 776
636=cut 777=cut
637 778
7791;
780

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