[ViewVC] Diff of: cvs/Convert-BER-XS/XS.pm

Comparing Convert-BER-XS/XS.pm (file contents):
Revision 1.5 by root, Fri Apr 19 19:46:41 2019 UTC vs.
Revision 1.62 by root, Thu Feb 6 23:15:44 2020 UTC

…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use Convert::BER::XS ':all';	7	use Convert::BER::XS ':all';
8		8
9	my $ber = ber_decode $buf	9	my $ber = ber_decode $buf, $Convert::BER::XS::SNMP_PROFILE
10	or die "unable to decode SNMP v1/v2c Message";	10	or die "unable to decode SNMP message";
11		11
12	# the above results in a data structure consisting of (class, tag,	12	# The above results in a data structure consisting of
		13	# (class, tag, flags, data)
13	# constructed, data) tuples. here is such a message, SNMPv1 trap	14	# tuples. Below is such a message, SNMPv1 trap
14	# with a cisoc mac change notification	15	# with a Cisco mac change notification.
		16	# Did you know that Cisco is in the news almost
		17	# every week because of some backdoor password
		18	# or other extremely stupid security bug?
15		19
16	[ ASN_UNIVERSAL, ASN_SEQUENCE, 1,	20	[ ASN_UNIVERSAL, ASN_SEQUENCE, 1,
17	[	21	[
18	[ ASN_UNIVERSAL, ASN_INTEGER32, 0, 0 ], # snmp version 1	22	[ ASN_UNIVERSAL, ASN_INTEGER, 0, 0 ], # snmp version 1
19	[ ASN_UNIVERSAL, 4, 0, "public" ], # community	23	[ ASN_UNIVERSAL, 4, 0, "public" ], # community
20	[ ASN_CONTEXT, 4, 1, # CHOICE, constructed	24	[ ASN_CONTEXT, 4, 1, # CHOICE, constructed - trap PDU
21	[	25	[
22	[ ASN_UNIVERSAL, ASN_OBJECT_IDENTIFIER, 0, "1.3.6.1.4.1.9.9.215.2" ], # enterprise oid	26	[ ASN_UNIVERSAL, ASN_OBJECT_IDENTIFIER, 0, "1.3.6.1.4.1.9.9.215.2" ], # enterprise oid
23	[ ASN_APPLICATION, 0, 0, "\x0a\x00\x00\x01" ], # SNMP IpAddress, 10.0.0.1	27	[ ASN_APPLICATION, SNMP_IPADDRESS, 0, "10.0.0.1" ], # SNMP IpAddress
24	[ ASN_UNIVERSAL, ASN_INTEGER32, 0, 6 ], # generic trap	28	[ ASN_UNIVERSAL, ASN_INTEGER, 0, 6 ], # generic trap
25	[ ASN_UNIVERSAL, ASN_INTEGER32, 0, 1 ], # specific trap	29	[ ASN_UNIVERSAL, ASN_INTEGER, 0, 1 ], # specific trap
26	[ ASN_APPLICATION, ASN_TIMETICKS, 0, 1817903850 ], # SNMP TimeTicks	30	[ ASN_APPLICATION, SNMP_TIMETICKS, 0, 1817903850 ], # SNMP TimeTicks
27	[ ASN_UNIVERSAL, ASN_SEQUENCE, 1, # the varbindlist	31	[ ASN_UNIVERSAL, ASN_SEQUENCE, 1, # the varbindlist
28	[	32	[
29	[ ASN_UNIVERSAL, ASN_SEQUENCE, 1, # a single varbind, "key value" pair	33	[ ASN_UNIVERSAL, ASN_SEQUENCE, 1, # a single varbind, "key value" pair
30	[	34	[
31	[ ASN_UNIVERSAL, ASN_OBJECT_IDENTIFIER, 0, "1.3.6.1.4.1.9.9.215.1.1.8.1.2.1" ], # the oid	35	[ ASN_UNIVERSAL, ASN_OBJECT_IDENTIFIER, 0, "1.3.6.1.4.1.9.9.215.1.1.8.1.2.1" ],
32	[ ASN_UNIVERSAL, ASN_OCTET_STRING, 0, "...data..." # the value	36	[ ASN_UNIVERSAL, ASN_OCTET_STRING, 0, "...data..." # the value
33	]	37	]
34	]	38	]
35	],	39	],
36	...	40	...
		41	# let's dump it, for debugging
		42
		43	ber_dump $ber, $Convert::BER::XS::SNMP_PROFILE;
37		44
38	# let's decode it a bit with some helper functions	45	# let's decode it a bit with some helper functions
39		46
40	my $msg = ber_is_seq $ber	47	my $msg = ber_is_seq $ber
41	or die "SNMP message does not start with a sequence";	48	or die "SNMP message does not start with a sequence";
42		49
43	ber_is $msg->[0], ASN_UNIVERSAL, ASN_INTEGER32, 0	50	ber_is $msg->[0], ASN_UNIVERSAL, ASN_INTEGER, 0
44	or die "SNMP message does not start with snmp version\n";	51	or die "SNMP message does not start with snmp version\n";
45		52
46	# message is SNMP v1 or v2c?	53	# message is SNMP v1 or v2c?
47	if ($msg->[0][BER_DATA] == 0 \|\| $msg->[0][BER_DATA] == 1) {	54	if ($msg->[0][BER_DATA] == 0 \|\| $msg->[0][BER_DATA] == 1) {
48		55
…		…
51	my $trap = $msg->[2][BER_DATA];	58	my $trap = $msg->[2][BER_DATA];
52		59
53	# check whether trap is a cisco mac notification mac changed message	60	# check whether trap is a cisco mac notification mac changed message
54	if (	61	if (
55	(ber_is_oid $trap->[0], "1.3.6.1.4.1.9.9.215.2") # cmnInterfaceObjects	62	(ber_is_oid $trap->[0], "1.3.6.1.4.1.9.9.215.2") # cmnInterfaceObjects
56	and (ber_is_i32 $trap->[2], 6)	63	and (ber_is_int $trap->[2], 6)
57	and (ber_is_i32 $trap->[3], 1) # mac changed msg	64	and (ber_is_int $trap->[3], 1) # mac changed msg
58	) {	65	) {
59	... and so on	66	... and so on
60		67
61	# finally, let's encode it again and hope it results in the same bit pattern	68	# finally, let's encode it again and hope it results in the same bit pattern
62		69
63	my $buf = ber_encode $ber;	70	my $buf = ber_encode $ber, $Convert::BER::XS::SNMP_PROFILE;
64		71
65	=head1 DESCRIPTION	72	=head1 DESCRIPTION
66		73
67	This module implements a I<very> low level BER/DER en-/decoder.	74	This module implements a I<very> low level BER/DER en-/decoder.
68		75
69	If is tuned for low memory and high speed, while still maintaining some	76	It is tuned for low memory and high speed, while still maintaining some
70	level of user-friendlyness.	77	level of user-friendlyness.
71		78
72	Currently, not much is documented, as this is an initial release to	79	=head2 EXPORT TAGS AND CONSTANTS
73	reserve CPAN namespace, stay tuned for a few days.	80
		81	By default this module doesn't export any symbols, but if you don't want
		82	to break your keyboard, editor or eyesight with extremely long names, I
		83	recommend importing the C<:all> tag. Still, you can selectively import
		84	things.
		85
		86	=over
		87
		88	=item C<:all>
		89
		90	All of the below. Really. Recommended for at least first steps, or if you
		91	don't care about a few kilobytes of wasted memory (and namespace).
		92
		93	=item C<:const>
		94
		95	All of the strictly ASN.1-related constants defined by this module, the
		96	same as C<:const_asn :const_index>. Notably, this does not contain
		97	C<:const_ber_type> and C<:const_snmp>.
		98
		99	A good set to get everything you need to decode and match BER data would be
		100	C<:decode :const>.
		101
		102	=item C<:const_index>
		103
		104	The BER tuple array index constants:
		105
		106	BER_CLASS BER_TAG BER_FLAGS BER_DATA
		107
		108	=item C<:const_asn>
		109
		110	ASN class values (these are C<0>, C<1>, C<2> and C<3>, respectively -
		111	exactly the two topmost bits from the identifier octet shifted 6 bits to
		112	the right):
		113
		114	ASN_UNIVERSAL ASN_APPLICATION ASN_CONTEXT ASN_PRIVATE
		115
		116	ASN tag values (some of which are aliases, such as C<ASN_OID>). Their
		117	numerical value corresponds exactly to the numbers used in BER/X.690.
		118
		119	ASN_BOOLEAN ASN_INTEGER ASN_BIT_STRING ASN_OCTET_STRING ASN_NULL ASN_OID
		120	ASN_OBJECT_IDENTIFIER ASN_OBJECT_DESCRIPTOR ASN_EXTERNAL ASN_REAL ASN_SEQUENCE ASN_ENUMERATED
		121	ASN_EMBEDDED_PDV ASN_UTF8_STRING ASN_RELATIVE_OID ASN_SET ASN_NUMERIC_STRING
		122	ASN_PRINTABLE_STRING ASN_TELETEX_STRING ASN_T61_STRING ASN_VIDEOTEX_STRING ASN_IA5_STRING
		123	ASN_ASCII_STRING ASN_UTC_TIME ASN_GENERALIZED_TIME ASN_GRAPHIC_STRING ASN_VISIBLE_STRING
		124	ASN_ISO646_STRING ASN_GENERAL_STRING ASN_UNIVERSAL_STRING ASN_CHARACTER_STRING ASN_BMP_STRING
		125
		126	=item C<:const_ber_type>
		127
		128	The BER type constants, explained in the PROFILES section.
		129
		130	BER_TYPE_BYTES BER_TYPE_UTF8 BER_TYPE_UCS2 BER_TYPE_UCS4 BER_TYPE_INT
		131	BER_TYPE_OID BER_TYPE_RELOID BER_TYPE_NULL BER_TYPE_BOOL BER_TYPE_REAL
		132	BER_TYPE_IPADDRESS BER_TYPE_CROAK
		133
		134	=item C<:const_snmp>
		135
		136	Constants only relevant to SNMP. These are the tag values used by SNMP in
		137	the C<ASN_APPLICATION> namespace and have the exact numerical value as in
		138	BER/RFC 2578.
		139
		140	SNMP_IPADDRESS SNMP_COUNTER32 SNMP_UNSIGNED32 SNMP_GAUGE32
		141	SNMP_TIMETICKS SNMP_OPAQUE SNMP_COUNTER64
		142
		143	=item C<:decode>
		144
		145	C<ber_decode> and the match helper functions:
		146
		147	ber_decode ber-decode_prefix
		148	ber_is ber_is_seq ber_is_int ber_is_oid
		149	ber_dump
		150
		151	=item C<:encode>
		152
		153	C<ber_encode> and the construction helper functions:
		154
		155	ber_encode
		156	ber_int
		157
		158	=back
74		159
75	=head2 ASN.1/BER/DER/... BASICS	160	=head2 ASN.1/BER/DER/... BASICS
76		161
77	ASN.1 is a strange language that can be sed to describe protocols and	162	ASN.1 is a strange language that can be used to describe protocols and
78	data structures. It supports various mappings to JSON, XML, but most	163	data structures. It supports various mappings to JSON, XML, but most
79	importantly, to a various binary encodings such as BER, that is the topic	164	importantly, to a various binary encodings such as BER, that is the topic
80	of this module, and is used in SNMP or LDAP for example.	165	of this module, and is used in SNMP, LDAP or X.509 for example.
81		166
82	While ASN.1 defines a schema that is useful to interpret encoded data,	167	While ASN.1 defines a schema that is useful to interpret encoded data,
83	the BER encoding is actually somehat self-describing: you might not know	168	the BER encoding is actually somewhat self-describing: you might not know
84	whether something is a string or a number or a sequence or something else,	169	whether something is a string or a number or a sequence or something else,
85	but you can nevertheless decode the overall structure, even if you end up	170	but you can nevertheless decode the overall structure, even if you end up
86	with just a binary blob for the actual value.	171	with just a binary blob for the actual value.
87		172
88	This works because BER values are tagged with a type and a namespace,	173	This works because BER values are tagged with a type and a namespace,
89	and also have a flag that says whther a value consists of subvalues (is	174	and also have a flag that says whether a value consists of subvalues (is
90	"constructed") or not (is "primitive").	175	"constructed") or not (is "primitive").
91		176
92	Tags are simple integers, and ASN.1 defines a somewhat weird assortment of	177	Tags are simple integers, and ASN.1 defines a somewhat weird assortment
93	those - for example, you have 32 bit signed integers and 16(!) different	178	of those - for example, you have one integers and 16(!) different
94	string types, but there is no unsigned32 type for example. Different	179	string types, but there is no Unsigned32 type for example. Different
95	applications work around this in different ways, for example, SNMP defines	180	applications work around this in different ways, for example, SNMP defines
96	application-specific Gauge32, Counter32 and Unsigned32, which are mapped	181	application-specific Gauge32, Counter32 and Unsigned32, which are mapped
97	to two different tags: you can distinguish between Counter32 and the	182	to two different tags: you can distinguish between Counter32 and the
98	others, but not between Gause32 and Unsigned32, without the ASN.1 schema.	183	others, but not between Gause32 and Unsigned32, without the ASN.1 schema.
99		184
…		…
102	=head2 DECODED BER REPRESENTATION	187	=head2 DECODED BER REPRESENTATION
103		188
104	This module represents every BER value as a 4-element tuple (actually an	189	This module represents every BER value as a 4-element tuple (actually an
105	array-reference):	190	array-reference):
106		191
107	[CLASS, TAG, CONSTRUCTED, DATA]	192	[CLASS, TAG, FLAGS, DATA]
		193
		194	For example:
		195
		196	[ASN_UNIVERSAL, ASN_INTEGER, 0, 177] # the integer 177
		197	[ASN_UNIVERSAL, ASN_OCTET_STRING, 0, "john"] # the string "john"
		198	[ASN_UNIVERSAL, ASN_OID, 0, "1.3.6.133"] # some OID
		199	[ASN_UNIVERSAL, ASN_SEQUENCE, 1, [ [ASN_UNIVERSAL... # a sequence
		200
		201	To avoid non-descriptive hardcoded array index numbers, this module
		202	defines symbolic constants to access these members: C<BER_CLASS>,
		203	C<BER_TAG>, C<BER_FLAGS> and C<BER_DATA>.
		204
		205	Also, the first three members are integers with a little caveat: for
		206	performance reasons, these are readonly and shared, so you must not modify
		207	them (increment, assign to them etc.) in any way. You may modify the
		208	I<DATA> member, and you may re-assign the array itself, e.g.:
		209
		210	$ber = ber_decode $binbuf;
		211
		212	# the following is NOT legal:
		213	$ber->[BER_CLASS] = ASN_PRIVATE; # ERROR, CLASS/TAG/FLAGS are READ ONLY(!)
		214
		215	# but all of the following are fine:
		216	$ber->[BER_DATA] = "string";
		217	$ber->[BER_DATA] = [ASN_UNIVERSAL, ASN_INTEGER, 0, 123];
		218	@$ber = (ASN_APPLICATION, SNMP_TIMETICKS, 0, 1000);
108		219
109	I<CLASS> is something like a namespace for I<TAG>s - there is the	220	I<CLASS> is something like a namespace for I<TAG>s - there is the
110	C<ASN_UNIVERSAL> namespace which defines tags common to all ASN.1	221	C<ASN_UNIVERSAL> namespace which defines tags common to all ASN.1
111	implementations, the C<ASN_APPLICATION> namespace which defines tags for	222	implementations, the C<ASN_APPLICATION> namespace which defines tags for
112	specific applications (for example, the SNMP C<Unsigned32> type is in this	223	specific applications (for example, the SNMP C<Unsigned32> type is in this
113	namespace), a special-purpose context namespace (C<ASN_CONTEXT>, used e.g.	224	namespace), a special-purpose context namespace (C<ASN_CONTEXT>, used e.g.
114	for C<CHOICE>) and a private namespace (C<ASN_PRIVATE>).	225	for C<CHOICE>) and a private namespace (C<ASN_PRIVATE>).
115		226
116	The meaning of the I<TAG> depends on the namespace, and defines a	227	The meaning of the I<TAG> depends on the namespace, and defines a
117	(partial) interpretation of the data value. For example, right now, SNMP	228	(partial) interpretation of the data value. For example, SNMP defines
118	application namespace knowledge ix hardcoded into this module, so it	229	extra tags in the C<ASN_APPLICATION> namespace, and to take full advantage
119	knows that SNMP C<Unsigned32> values need to be decoded into actual perl	230	of these, you need to tell this module how to handle those via profiles.
120	integers.
121		231
122	The most common tags in the C<ASN_UNIVERSAL> namespace are	232	The most common tags in the C<ASN_UNIVERSAL> namespace are
123	C<ASN_INTEGER32>, C<ASN_BIT_STRING>, C<ASN_NULL>, C<ASN_OCTET_STRING>,	233	C<ASN_INTEGER>, C<ASN_BIT_STRING>, C<ASN_NULL>, C<ASN_OCTET_STRING>,
124	C<ASN_OBJECT_IDENTIFIER>, C<ASN_SEQUENCE>, C<ASN_SET> and	234	C<ASN_OBJECT_IDENTIFIER>, C<ASN_SEQUENCE>, C<ASN_SET> and
125	C<ASN_IA5_STRING>.	235	C<ASN_IA5_STRING>.
126		236
127	The most common tags in SNMP's C<ASN_APPLICATION> namespace	237	The most common tags in SNMP's C<ASN_APPLICATION> namespace are
128	are C<SNMP_IPADDRESS>, C<SNMP_COUNTER32>, C<SNMP_UNSIGNED32>,	238	C<SNMP_COUNTER32>, C<SNMP_UNSIGNED32>, C<SNMP_TIMETICKS> and
129	C<SNMP_TIMETICKS>, C<SNMP_OPAQUE> and C<SNMP_COUNTER64>.	239	C<SNMP_COUNTER64>.
130		240
131	The I<CONSTRUCTED> flag is really just a boolean - if it is false, the	241	The I<FLAGS> value is really just a boolean at this time (but might
132	the value is "primitive" and contains no subvalues, kind of like a	242	get extended) - if it is C<0>, the value is "primitive" and contains
133	non-reference perl scalar. IF it is true, then the value is "constructed"	243	no subvalues, kind of like a non-reference perl scalar. If it is C<1>,
134	which just means it contains a list of subvalues which this module will	244	then the value is "constructed" which just means it contains a list of
135	en-/decode as BER tuples themselves.	245	subvalues which this module will en-/decode as BER tuples themselves.
136		246
137	The I<DATA> value is either a reference to an array of further tuples (if	247	The I<DATA> value is either a reference to an array of further tuples
138	the value is I<CONSTRUCTED>), some decoded representation of the value,	248	(if the value is I<FLAGS>), some decoded representation of the value, if
139	if this module knows how to decode it (e.g. for the integer types above)	249	this module knows how to decode it (e.g. for the integer types above) or
140	or a binary string with the raw octets if this module doesn't know how to	250	a binary string with the raw octets if this module doesn't know how to
141	interpret the namespace/tag.	251	interpret the namespace/tag.
142		252
143	Thus, you can always decode a BER data structure and at worst you get a	253	Thus, you can always decode a BER data structure and at worst you get a
144	string in place of some nice decoded value.	254	string in place of some nice decoded value.
145		255
146	See the SYNOPSIS for an example of such an encoded tuple representation.	256	See the SYNOPSIS for an example of such an encoded tuple representation.
		257
		258	=head2 DECODING AND ENCODING
		259
		260	=over
		261
		262	=item $tuple = ber_decode $bindata[, $profile]
		263
		264	Decodes binary BER data in C<$bindata> and returns the resulting BER
		265	tuple. Croaks on any decoding error, so the returned C<$tuple> is always
		266	valid.
		267
		268	How tags are interpreted is defined by the second argument, which must
		269	be a C<Convert::BER::XS::Profile> object. If it is missing, the default
		270	profile will be used (C<$Convert::BER::XS::DEFAULT_PROFILE>).
		271
		272	In addition to rolling your own, this module provides a
		273	C<$Convert::BER::XS::SNMP_PROFILE> that knows about the additional SNMP
		274	types.
		275
		276	Example: decode a BER blob using the default profile - SNMP values will be
		277	decided as raw strings.
		278
		279	$tuple = ber_decode $data;
		280
		281	Example: as above, but use the provided SNMP profile.
		282
		283	$tuple = ber_encode $data, $Convert::BER::XS::SNMP_PROFILE;
		284
		285	=item ($tuple, $bytes) = ber_decode_prefix $bindata[, $profile]
		286
		287	Works like C<ber_decode>, except it doesn't croak when there is data after
		288	the BER data, but instead returns the decoded value and the number of
		289	bytes it decoded.
		290
		291	This is useful when you have BER data at the start of a buffer and other
		292	data after, and you need to find the length.
		293
		294	Also, since BER is self-delimited, this can be used to decode multiple BER
		295	values joined together.
		296
		297	=item $bindata = ber_encode $tuple[, $profile]
		298
		299	Encodes the BER tuple into a BER/DER data structure. As with
		300	Cyber_decode>, an optional profile can be given.
		301
		302	The encoded data should be both BER and DER ("shortest form") compliant
		303	unless the input says otherwise (e.g. it uses constructed strings).
		304
		305	=back
		306
		307	=head2 HELPER FUNCTIONS
		308
		309	Working with a 4-tuple for every value can be annoying. Or, rather, I<is>
		310	annoying. To reduce this a bit, this module defines a number of helper
		311	functions, both to match BER tuples and to construct BER tuples:
		312
		313	=head3 MATCH HELPERS
		314
		315	These functions accept a BER tuple as first argument and either partially
		316	or fully match it. They often come in two forms, one which exactly matches
		317	a value, and one which only matches the type and returns the value.
		318
		319	They do check whether valid tuples are passed in and croak otherwise. As
		320	a ease-of-use exception, they usually also accept C<undef> instead of a
		321	tuple reference, in which case they silently fail to match.
		322
		323	=over
		324
		325	=item $bool = ber_is $tuple, $class, $tag, $flags, $data
		326
		327	This takes a BER C<$tuple> and matches its elements against the provided
		328	values, all of which are optional - values that are either missing or
		329	C<undef> will be ignored, the others will be matched exactly (e.g. as if
		330	you used C<==> or C<eq> (for C<$data>)).
		331
		332	Some examples:
		333
		334	ber_is $tuple, ASN_UNIVERSAL, ASN_SEQUENCE, 1
		335	orf die "tuple is not an ASN SEQUENCE";
		336
		337	ber_is $tuple, ASN_UNIVERSAL, ASN_NULL
		338	or die "tuple is not an ASN NULL value";
		339
		340	ber_is $tuple, ASN_UNIVERSAL, ASN_INTEGER, 0, 50
		341	or die "BER integer must be 50";
		342
		343	=item $seq = ber_is_seq $tuple
		344
		345	Returns the sequence members (the array of subvalues) if the C<$tuple> is
		346	an ASN SEQUENCE, i.e. the C<BER_DATA> member. If the C<$tuple> is not a
		347	sequence it returns C<undef>. For example, SNMP version 1/2c/3 packets all
		348	consist of an outer SEQUENCE value:
		349
		350	my $ber = ber_decode $snmp_data;
		351
		352	my $snmp = ber_is_seq $ber
		353	or die "SNMP packet invalid: does not start with SEQUENCE";
		354
		355	# now we know $snmp is a sequence, so decode the SNMP version
		356
		357	my $version = ber_is_int $snmp->[0]
		358	or die "SNMP packet invalid: does not start with version number";
		359
		360	=item $bool = ber_is_int $tuple, $int
		361
		362	Returns a true value if the C<$tuple> represents an ASN INTEGER with
		363	the value C<$int>.
		364
		365	=item $int = ber_is_int $tuple
		366
		367	Returns true (and extracts the integer value) if the C<$tuple> is an
		368	C<ASN_INTEGER>. For C<0>, this function returns a special value that is 0
		369	but true.
		370
		371	=item $bool = ber_is_oid $tuple, $oid_string
		372
		373	Returns true if the C<$tuple> represents an ASN_OBJECT_IDENTIFIER
		374	that exactly matches C<$oid_string>. Example:
		375
		376	ber_is_oid $tuple, "1.3.6.1.4"
		377	or die "oid must be 1.3.6.1.4";
		378
		379	=item $oid = ber_is_oid $tuple
		380
		381	Returns true (and extracts the OID string) if the C<$tuple> is an ASN
		382	OBJECT IDENTIFIER. Otherwise, it returns C<undef>.
		383
		384	=back
		385
		386	=head3 CONSTRUCTION HELPERS
		387
		388	=over
		389
		390	=item $tuple = ber_int $value
		391
		392	Constructs a new C<ASN_INTEGER> tuple.
		393
		394	=back
147		395
148	=head2 RELATIONSHIP TO L<Convert::BER> and L<Convert::ASN1>	396	=head2 RELATIONSHIP TO L<Convert::BER> and L<Convert::ASN1>
149		397
150	This module is I<not> the XS version of L<Convert::BER>, but a different	398	This module is I<not> the XS version of L<Convert::BER>, but a different
151	take at doing the same thing. I imagine this module would be a good base	399	take at doing the same thing. I imagine this module would be a good base
…		…
159	use common::sense;	407	use common::sense;
160		408
161	use XSLoader ();	409	use XSLoader ();
162	use Exporter qw(import);	410	use Exporter qw(import);
163		411
		412	use Carp ();
		413
164	our $VERSION = 0.1;	414	our $VERSION;
165		415
		416	BEGIN {
		417	$VERSION = 1.21;
166	XSLoader::load __PACKAGE__, $VERSION;	418	XSLoader::load __PACKAGE__, $VERSION;
		419	}
167		420
168	our %EXPORT_TAGS = (	421	our %EXPORT_TAGS = (
		422	const_index => [qw(
		423	BER_CLASS BER_TAG BER_FLAGS BER_DATA
		424	)],
		425	const_asn_class => [qw(
		426	ASN_UNIVERSAL ASN_APPLICATION ASN_CONTEXT ASN_PRIVATE
		427	)],
		428	const_asn_tag => [qw(
		429	ASN_BOOLEAN ASN_INTEGER ASN_BIT_STRING ASN_OCTET_STRING ASN_NULL ASN_OID ASN_OBJECT_IDENTIFIER
		430	ASN_OBJECT_DESCRIPTOR ASN_EXTERNAL ASN_REAL ASN_SEQUENCE ASN_ENUMERATED
		431	ASN_EMBEDDED_PDV ASN_UTF8_STRING ASN_RELATIVE_OID ASN_SET ASN_NUMERIC_STRING
		432	ASN_PRINTABLE_STRING ASN_TELETEX_STRING ASN_T61_STRING ASN_VIDEOTEX_STRING ASN_IA5_STRING
		433	ASN_ASCII_STRING ASN_UTC_TIME ASN_GENERALIZED_TIME ASN_GRAPHIC_STRING ASN_VISIBLE_STRING
		434	ASN_ISO646_STRING ASN_GENERAL_STRING ASN_UNIVERSAL_STRING ASN_CHARACTER_STRING ASN_BMP_STRING
		435	)],
		436	const_ber_type => [qw(
		437	BER_TYPE_BYTES BER_TYPE_UTF8 BER_TYPE_UCS2 BER_TYPE_UCS4 BER_TYPE_INT
		438	BER_TYPE_OID BER_TYPE_RELOID BER_TYPE_NULL BER_TYPE_BOOL BER_TYPE_REAL
		439	BER_TYPE_IPADDRESS BER_TYPE_CROAK
		440	)],
169	const => [qw(	441	const_snmp => [qw(
170	BER_CLASS BER_TAG BER_CONSTRUCTED BER_DATA	442	SNMP_IPADDRESS SNMP_COUNTER32 SNMP_GAUGE32 SNMP_UNSIGNED32
171		443	SNMP_TIMETICKS SNMP_OPAQUE SNMP_COUNTER64
172	ASN_BOOLEAN ASN_INTEGER32 ASN_BIT_STRING ASN_OCTET_STRING ASN_NULL ASN_OBJECT_IDENTIFIER ASN_TAG_BER ASN_TAG_MASK	444	)],
173	ASN_CONSTRUCTED ASN_UNIVERSAL ASN_APPLICATION ASN_CONTEXT ASN_PRIVATE ASN_CLASS_MASK ASN_CLASS_SHIFT	445	decode => [qw(
174	ASN_SEQUENCE	446	ber_decode ber_decode_prefix
175		447	ber_is ber_is_seq ber_is_int ber_is_oid
176	SNMP_IPADDRESS SNMP_COUNTER32 SNMP_UNSIGNED32 SNMP_TIMETICKS SNMP_OPAQUE SNMP_COUNTER64	448	ber_dump
177	)],	449	)],
178	encode => [qw(	450	encode => [qw(
179	ber_decode
180	ber_is ber_is_seq ber_is_i32 ber_is_oid
181	)],
182	decode => [qw(
183	ber_encode	451	ber_encode
		452	ber_int
184	)],	453	)],
185	);	454	);
186		455
187	our @EXPORT_OK = map @$_, values %EXPORT_TAGS;	456	our @EXPORT_OK = map @$_, values %EXPORT_TAGS;
188		457
189	$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)];
		460	$EXPORT_TAGS{const} = [map @{ $EXPORT_TAGS{$_} }, qw(const_index const_asn)];
190		461
191	1;	462	our $DEFAULT_PROFILE = new Convert::BER::XS::Profile;
192		463
193	=head2 BUGS / SHORTCOMINGs	464	$DEFAULT_PROFILE->_set_default;
194		465
195	This module does have a number of SNMPisms hardcoded, such as the SNMP	466	# additional SNMP application types
196	tags for Unsigned32 and so on. More configurability is needed, and, if	467	our $SNMP_PROFILE = new Convert::BER::XS::Profile;
197	ever implemented, will come in a form similar to how L<JSON::XS> and	468
198	L<CBOR::XS> respresent things, namely with an object-oriented interface.	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	$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_TIMETICKS , BER_TYPE_INT);
		473
		474	# decodes REAL values according to ECMA-63
		475	# this is pretty strict, except it doesn't catch -0.
		476	# I don't have access to ISO 6093 (or BS 6727, or ANSI X.3-42)), so this is all guesswork.
		477	sub _decode_real_decimal {
		478	my ($format, $val) = @_;
		479
		480	$val =~ y/,/./; # probably not in ISO-6093
		481
		482	if ($format == 1) {
		483	$val =~ /^ \ * [+-]? [0-9]+ \z/x
		484	or Carp::croak "BER_TYPE_REAL NR1 value not in NR1 format ($val) (X.690 8.5.8)";
		485	} elsif ($format == 2) {
		486	$val =~ /^ \ * [+-]? (?: [0-9]+\.[0-9]* \| [0-9]*\.[0-9]+ ) \z/x
		487	or Carp::croak "BER_TYPE_REAL NR2 value not in NR2 format ($val) (X.690 8.5.8)";
		488	} elsif ($format == 3) {
		489	$val =~ /^ \ * [+-] (?: [0-9]+\.[0-9]* \| [0-9]*\.[0-9]+ ) [eE] [+-]? [0-9]+ \z/x
		490	or Carp::croak "BER_TYPE_REAL NR3 value not in NR3 format ($val) (X.690 8.5.8)";
		491	} else {
		492	Carp::croak "BER_TYPE_REAL invalid decimal numerical representation format $format";
		493	}
		494
		495	$val
		496	}
		497
		498	# this is a mess, but perl's support for floating point formatting is nearly nonexistant
		499	sub _encode_real_decimal {
		500	my ($val, $nvdig) = @_;
		501
		502	$val = sprintf "%.*G", $nvdig + 1, $val;
		503
		504	if ($val =~ /E/) {
		505	$val =~ s/E(?=[^+-])/E+/;
		506	$val =~ s/E/.E/ if $val !~ /\./;
		507	$val =~ s/^/+/ unless $val =~ /^-/;
		508
		509	return "\x03$val" # NR3
		510	}
		511
		512	$val =~ /\./
		513	? "\x02$val" # NR2
		514	: "\x01$val" # NR1
		515	}
		516
		517	=head2 DEBUGGING
		518
		519	To aid debugging, you can call the C<ber_dump> function to print a "nice"
		520	representation to STDOUT.
		521
		522	=over
		523
		524	=item ber_dump $tuple[, $profile[, $prefix]]
		525
		526	In addition to specifying the BER C<$tuple> to dump, you can also specify
		527	a C<$profile> and a C<$prefix> string that is printed in front of each line.
		528
		529	If C<$profile> is C<$Convert::BER::XS::SNMP_PROFILE>, then C<ber_dump>
		530	will try to improve its output for SNMP data.
		531
		532	The output usually contains three columns, the "human readable" tag, the
		533	BER type used to decode it, and the data value.
		534
		535	This function is somewhat slow and uses a number of heuristics and tricks,
		536	so it really is only suitable for debug prints.
		537
		538	Example output:
		539
		540	SEQUENCE
		541	\| OCTET_STRING bytes 800063784300454045045400000001
		542	\| OCTET_STRING bytes
		543	\| CONTEXT (7) CONSTRUCTED
		544	\| \| INTEGER int 1058588941
		545	\| \| INTEGER int 0
		546	\| \| INTEGER int 0
		547	\| \| SEQUENCE
		548	\| \| \| SEQUENCE
		549	\| \| \| \| OID oid 1.3.6.1.2.1.1.3.0
		550	\| \| \| \| TIMETICKS int 638085796
		551
		552	=back
		553
		554	=cut
		555
		556	# reverse enum, very slow and ugly hack
		557	sub _re {
		558	my ($export_tag, $value) = @_;
		559
		560	for my $symbol (@{ $EXPORT_TAGS{$export_tag} }) {
		561	$value == eval $symbol
		562	and return $symbol;
		563	}
		564
		565	"($value)"
		566	}
		567
		568	$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_COUNTER64 , BER_TYPE_INT);
		569
		570	sub _ber_dump {
		571	my ($ber, $profile, $indent) = @_;
		572
		573	if (my $seq = ber_is_seq $ber) {
		574	printf "%sSEQUENCE\n", $indent;
		575	&_ber_dump ($_, $profile, "$indent\| ")
		576	for @$seq;
		577	} else {
		578	my $asn = $ber->[BER_CLASS] == ASN_UNIVERSAL;
		579
		580	my $class = _re const_asn_class => $ber->[BER_CLASS];
		581	my $tag = $asn ? _re const_asn_tag => $ber->[BER_TAG] : $ber->[BER_TAG];
		582	my $type = _re const_ber_type => $profile->get ($ber->[BER_CLASS], $ber->[BER_TAG]);
		583	my $data = $ber->[BER_DATA];
		584
		585	if ($profile == $SNMP_PROFILE and $ber->[BER_CLASS] == ASN_APPLICATION) {
		586	$tag = _re const_snmp => $ber->[BER_TAG];
		587	} elsif (!$asn) {
		588	$tag = "$class ($tag)";
		589	}
		590
		591	$class =~ s/^ASN_//;
		592	$tag =~ s/^(ASN_\|SNMP_)//;
		593	$type =~ s/^BER_TYPE_//;
		594
		595	if ($ber->[BER_FLAGS]) {
		596	printf "$indent%-16.16s\n", $tag;
		597	&_ber_dump ($_, $profile, "$indent\| ")
		598	for @$data;
		599	} else {
		600	if ($data =~ y/\x20-\x7e//c / (length $data \|\| 1) > 0.2 or $data =~ /\x00./s) {
		601	# assume binary
		602	$data = unpack "H*", $data;
		603	} else {
		604	$data =~ s/[^\x20-\x7e]/./g;
		605	$data = "\"$data\"" if $tag =~ /string/i \|\| !length $data;
		606	}
		607
		608	substr $data, 40, 1e9, "..." if 40 < length $data;
		609
		610	printf "$indent%-16.16s %-6.6s %s\n", $tag, lc $type, $data;
		611	}
		612	}
		613	}
		614
		615	sub ber_dump($;$$) {
		616	_ber_dump $_[0], $_[1] \|\| $DEFAULT_PROFILE, $_[2];
		617	}
		618
		619	=head1 PROFILES
		620
		621	While any BER data can be correctly encoded and decoded out of the box, it
		622	can be inconvenient to have to manually decode some values into a "better"
		623	format: for instance, SNMP TimeTicks values are decoded into the raw octet
		624	strings of their BER representation, which is quite hard to decode. With
		625	profiles, you can change which class/tag combinations map to which decoder
		626	function inside C<ber_decode> (and of course also which encoder functions
		627	are used in C<ber_encode>).
		628
		629	This works by mapping specific class/tag combinations to an internal "ber
		630	type".
		631
		632	The default profile supports the standard ASN.1 types, but no
		633	application-specific ones. This means that class/tag combinations not in
		634	the base set of ASN.1 are decoded into their raw octet strings.
		635
		636	C<Convert::BER::XS> defines two profile variables you can use out of the box:
		637
		638	=over
		639
		640	=item C<$Convert::BER::XS::DEFAULT_PROFILE>
		641
		642	This is the default profile, i.e. the profile that is used when no
		643	profile is specified for de-/encoding.
		644
		645	You can modify it, but remember that this modifies the defaults for all
		646	callers that rely on the default profile.
		647
		648	=item C<$Convert::BER::XS::SNMP_PROFILE>
		649
		650	A profile with mappings for SNMP-specific application tags added. This is
		651	useful when de-/encoding SNMP data.
		652
		653	Example:
		654
		655	$ber = ber_decode $data, $Convert::BER::XS::SNMP_PROFILE;
		656
		657	=back
		658
		659	=head2 The Convert::BER::XS::Profile class
		660
		661	=over
		662
		663	=item $profile = new Convert::BER::XS::Profile
		664
		665	Create a new profile. The profile will be identical to the default
		666	profile.
		667
		668	=item $profile->set ($class, $tag, $type)
		669
		670	Sets the mapping for the given C<$class>/C<$tag> combination to C<$type>,
		671	which must be one of the C<BER_TYPE_*> constants.
		672
		673	Note that currently, the mapping is stored in a flat array, so large
		674	values of C<$tag> will consume large amounts of memory.
		675
		676	Example:
		677
		678	$profile = new Convert::BER::XS::Profile;
		679	$profile->set (ASN_APPLICATION, SNMP_COUNTER32, BER_TYPE_INT);
		680	$ber = ber_decode $data, $profile;
		681
		682	=item $type = $profile->get ($class, $tag)
		683
		684	Returns the BER type mapped to the given C<$class>/C<$tag> combination.
		685
		686	=back
		687
		688	=head2 BER Types
		689
		690	This lists the predefined BER types. BER types are formatters used
		691	internally to format and encode BER values. You can assign any C<BER_TYPE>
		692	to any C<CLASS>/C<TAG> combination tgo change how that tag is decoded or
		693	encoded.
		694
		695	=over
		696
		697	=item C<BER_TYPE_BYTES>
		698
		699	The raw octets of the value. This is the default type for unknown tags and
		700	de-/encodes the value as if it were an octet string, i.e. by copying the
		701	raw bytes.
		702
		703	=item C<BER_TYPE_UTF8>
		704
		705	Like C<BER_TYPE_BYTES>, but decodes the value as if it were a UTF-8 string
		706	(without validation!) and encodes a perl unicode string into a UTF-8 BER
		707	string.
		708
		709	=item C<BER_TYPE_UCS2>
		710
		711	Similar to C<BER_TYPE_UTF8>, but treats the BER value as UCS-2 encoded
		712	string.
		713
		714	=item C<BER_TYPE_UCS4>
		715
		716	Similar to C<BER_TYPE_UTF8>, but treats the BER value as UCS-4 encoded
		717	string.
		718
		719	=item C<BER_TYPE_INT>
		720
		721	Encodes and decodes a BER integer value to a perl integer scalar. This
		722	should correctly handle 64 bit signed and unsigned values.
		723
		724	=item C<BER_TYPE_OID>
		725
		726	Encodes and decodes an OBJECT IDENTIFIER into dotted form without leading
		727	dot, e.g. C<1.3.6.1.213>.
		728
		729	=item C<BER_TYPE_RELOID>
		730
		731	Same as C<BER_TYPE_OID> but uses relative object identifier
		732	encoding: ASN.1 uses some hack encoding of the first two OID components
		733	into a single integer in a weird attempt to save an insignificant amount
		734	of space in an otherwise wasteful encoding, and relative OIDs are
		735	basically OIDs without this hack. The practical difference is that the
		736	second component of an OID can only have the values 1..40, while relative
		737	OIDs do not have this restriction.
		738
		739	=item C<BER_TYPE_NULL>
		740
		741	Decodes an C<ASN_NULL> value into C<undef>, and always encodes a
		742	C<ASN_NULL> type, regardless of the perl value.
		743
		744	=item C<BER_TYPE_BOOL>
		745
		746	Decodes an C<ASN_BOOLEAN> value into C<0> or C<1>, and encodes a perl
		747	boolean value into an C<ASN_BOOLEAN>.
		748
		749	=item C<BER_TYPE_REAL>
		750
		751	Decodes/encodes a BER real value. NOT IMPLEMENTED.
		752
		753	=item C<BER_TYPE_IPADDRESS>
		754
		755	Decodes/encodes a four byte string into an IPv4 dotted-quad address string
		756	in Perl. Given the obsolete nature of this type, this is a low-effort
		757	implementation that simply uses C<sprintf> and C<sscanf>-style conversion,
		758	so it won't handle all string forms supported by C<inet_aton> for example.
		759
		760	=item C<BER_TYPE_CROAK>
		761
		762	Always croaks when encountered during encoding or decoding - the
		763	default behaviour when encountering an unknown type is to treat it as
		764	C<BER_TYPE_BYTES>. When you don't want that but instead prefer a hard
		765	error for some types, then C<BER_TYPE_CROAK> is for you.
		766
		767	=back
		768
		769	=head2 Example Profile
		770
		771	The following creates a profile suitable for SNMP - it's exactly identical
		772	to the C<$Convert::BER::XS::SNMP_PROFILE> profile.
		773
		774	our $SNMP_PROFILE = new Convert::BER::XS::Profile;
		775
		776	$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_IPADDRESS , BER_TYPE_IPADDRESS);
		777	$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_COUNTER32 , BER_TYPE_INT);
		778	$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_UNSIGNED32, BER_TYPE_INT);
		779	$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_TIMETICKS , BER_TYPE_INT);
		780	$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_OPAQUE , BER_TYPE_BYTES);
		781	$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_COUNTER64 , BER_TYPE_INT);
		782
		783	=head2 LIMITATIONS/NOTES
		784
		785	This module can only en-/decode 64 bit signed and unsigned
		786	integers/tags/lengths, and only when your perl supports those. So no UUID
		787	OIDs for now (unless you map the C<OBJECT IDENTIFIER> tag to something
		788	other than C<BER_TYPE_OID>).
		789
		790	This module does not generally care about ranges, i.e. it will happily
		791	de-/encode 64 bit integers into an C<SNMP_UNSIGNED32> value, or a negative
		792	number into an C<SNMP_COUNTER64>.
		793
		794	OBJECT IDENTIFIEERs cannot have unlimited length, although the limit is
		795	much larger than e.g. the one imposed by SNMP or other protocols, and is
		796	about 4kB.
		797
		798	Constructed strings are decoded just fine, but there should be a way to
		799	join them for convenience.
		800
		801	REAL values will always be encoded in decimal form and ssometimes is
		802	forced into a perl "NV" type, potentially losing precision.
		803
		804	=head2 ITHREADS SUPPORT
		805
		806	This module is unlikely to work in any other than the loading thread when
		807	the (officially discouraged) ithreads are in use.
199		808
200	=head1 AUTHOR	809	=head1 AUTHOR
201		810
202	Marc Lehmann <schmorp@schmorp.de>	811	Marc Lehmann <schmorp@schmorp.de>
203	http://software.schmorp.de/pkg/Convert-BER-XS	812	http://software.schmorp.de/pkg/Convert-BER-XS
204		813
205	=cut	814	=cut
206		815
		816	1;
		817

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Comparing Convert-BER-XS/XS.pm (file contents): Revision 1.5 by root, Fri Apr 19 19:46:41 2019 UTC vs. Revision 1.62 by root, Thu Feb 6 23:15:44 2020 UTC

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Comparing Convert-BER-XS/XS.pm (file contents):
Revision 1.5 by root, Fri Apr 19 19:46:41 2019 UTC vs.
Revision 1.62 by root, Thu Feb 6 23:15:44 2020 UTC