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Revision 1.21 by root, Sat Apr 20 14:49:56 2019 UTC vs.
Revision 1.63 by root, Wed Mar 3 05:30:23 2021 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 # decode a binary BER data structure using the SNMP profile
9 my $ber = ber_decode $buf, $Convert::BER::XS::SNMP_PROFILE 10 my $ber = ber_decode $buf, $Convert::BER::XS::SNMP_PROFILE
10 or die "unable to decode SNMP message"; 11 or die "unable to decode SNMP message";
11 12
12 # The above results in a data structure consisting of 13 # The above results in a data structure consisting of
13 # (class, tag, # constructed, data) 14 # (class, tag, flags, data)
14 # tuples. Below is such a message, SNMPv1 trap 15 # tuples. Below is such a message, an SNMPv1 trap
15 # with a Cisco mac change notification. 16 # with a Cisco mac change notification.
16 # Did you know that Cisco is in the news almost 17 # (Did you know that Cisco is in the news almost
17 # every week because of some backdoor password 18 # every week because of some backdoor password
18 # or other extremely stupid security bug? 19 # or other extremely stupid security bug?)
19 20
20 [ ASN_UNIVERSAL, ASN_SEQUENCE, 1, 21 [ ASN_UNIVERSAL, ASN_SEQUENCE, 1,
21 [ 22 [
22 [ ASN_UNIVERSAL, ASN_INTEGER32, 0, 0 ], # snmp version 1 23 [ ASN_UNIVERSAL, ASN_INTEGER, 0, 0 ], # snmp version 1
23 [ ASN_UNIVERSAL, 4, 0, "public" ], # community 24 [ ASN_UNIVERSAL, 4, 0, "public" ], # community
24 [ ASN_CONTEXT, 4, 1, # CHOICE, constructed - trap PDU 25 [ ASN_CONTEXT, 4, 1, # CHOICE, constructed - trap PDU
25 [ 26 [
26 [ ASN_UNIVERSAL, ASN_OBJECT_IDENTIFIER, 0, "1.3.6.1.4.1.9.9.215.2" ], # enterprise oid 27 [ ASN_UNIVERSAL, ASN_OBJECT_IDENTIFIER, 0, "1.3.6.1.4.1.9.9.215.2" ], # enterprise oid
27 [ ASN_APPLICATION, SNMP_IPADDRESS, 0, "10.0.0.1" ], # SNMP IpAddress 28 [ ASN_APPLICATION, SNMP_IPADDRESS, 0, "10.0.0.1" ], # SNMP IpAddress
28 [ ASN_UNIVERSAL, ASN_INTEGER32, 0, 6 ], # generic trap 29 [ ASN_UNIVERSAL, ASN_INTEGER, 0, 6 ], # generic trap
29 [ ASN_UNIVERSAL, ASN_INTEGER32, 0, 1 ], # specific trap 30 [ ASN_UNIVERSAL, ASN_INTEGER, 0, 1 ], # specific trap
30 [ ASN_APPLICATION, SNMP_TIMETICKS, 0, 1817903850 ], # SNMP TimeTicks 31 [ ASN_APPLICATION, SNMP_TIMETICKS, 0, 1817903850 ], # SNMP TimeTicks
31 [ ASN_UNIVERSAL, ASN_SEQUENCE, 1, # the varbindlist 32 [ ASN_UNIVERSAL, ASN_SEQUENCE, 1, # the varbindlist
32 [ 33 [
33 [ ASN_UNIVERSAL, ASN_SEQUENCE, 1, # a single varbind, "key value" pair 34 [ ASN_UNIVERSAL, ASN_SEQUENCE, 1, # a single varbind, "key value" pair
34 [ 35 [
37 ] 38 ]
38 ] 39 ]
39 ], 40 ],
40 ... 41 ...
41 42
43 # let's dump the above structure, for debugging
44 ber_dump $ber, $Convert::BER::XS::SNMP_PROFILE;
45
42 # let's decode it a bit with some helper functions 46 # let's decode it a bit with some helper functions.
43 47 # first check whether it starts with a sequence
44 my $msg = ber_is_seq $ber 48 my $msg = ber_is_seq $ber
45 or die "SNMP message does not start with a sequence"; 49 or die "SNMP message does not start with a sequence";
46 50
51 # then check if its some kind of integer
47 ber_is $msg->[0], ASN_UNIVERSAL, ASN_INTEGER32, 0 52 ber_is $msg->[0], ASN_UNIVERSAL, ASN_INTEGER, 0
48 or die "SNMP message does not start with snmp version\n"; 53 or die "SNMP message does not start with snmp version";
49 54
50 # message is SNMP v1 or v2c? 55 # message is SNMP v1 or v2c?
51 if ($msg->[0][BER_DATA] == 0 || $msg->[0][BER_DATA] == 1) { 56 if ($msg->[0][BER_DATA] == 0 || $msg->[0][BER_DATA] == 1) {
52 57
53 # message is v1 trap? 58 # message is v1 trap?
55 my $trap = $msg->[2][BER_DATA]; 60 my $trap = $msg->[2][BER_DATA];
56 61
57 # check whether trap is a cisco mac notification mac changed message 62 # check whether trap is a cisco mac notification mac changed message
58 if ( 63 if (
59 (ber_is_oid $trap->[0], "1.3.6.1.4.1.9.9.215.2") # cmnInterfaceObjects 64 (ber_is_oid $trap->[0], "1.3.6.1.4.1.9.9.215.2") # cmnInterfaceObjects
60 and (ber_is_i32 $trap->[2], 6) 65 and (ber_is_int $trap->[2], 6)
61 and (ber_is_i32 $trap->[3], 1) # mac changed msg 66 and (ber_is_int $trap->[3], 1) # mac changed msg
62 ) { 67 ) {
63 ... and so on 68 ... and so on
64 69
65 # finally, let's encode it again and hope it results in the same bit pattern 70 # finally, let's encode it again and hope it results in the same bit pattern
66
67 my $buf = ber_encode $ber, $Convert::BER::XS::SNMP_PROFILE; 71 my $buf = ber_encode $ber, $Convert::BER::XS::SNMP_PROFILE;
68 72
69=head1 DESCRIPTION 73=head1 DESCRIPTION
70
71WARNING: Before release 1.0, the API is not considered stable in any way.
72 74
73This module implements a I<very> low level BER/DER en-/decoder. 75This module implements a I<very> low level BER/DER en-/decoder.
74 76
75It is tuned for low memory and high speed, while still maintaining some 77It is tuned for low memory and high speed, while still maintaining some
76level of user-friendlyness. 78level of user-friendlyness.
77 79
78=head2 EXPORT TAGS AND CONSTANTS 80=head2 EXPORT TAGS AND CONSTANTS
79 81
80By default this module doesn't export any symbols, but if you don't want 82By default this module doesn't export any symbols, but if you don't want
81to break your keyboard, editor or eyesigh with extreemly long names, I 83to break your keyboard, editor or eyesight with extremely long names, I
82recommend importing the C<:all> tag. Still, you can selectively import 84recommend importing the C<:all> tag. Still, you can selectively import
83things. 85things.
84 86
85=over 87=over
86 88
87=item C<:all> 89=item C<:all>
88 90
89All of the below. Really. Rcommended for at least first steps, or if you 91All of the below. Really. Recommended for at least first steps, or if you
90don't care about a few kilobytes of wasted memory (and namespace). 92don't care about a few kilobytes of wasted memory (and namespace).
91 93
92=item C<:const> 94=item C<:const>
93 95
94All of the stricly ASN.1-related constants defined by this module, the 96All of the strictly ASN.1-related constants defined by this module, the
95same as C<:const_asn :const_index>. Notably, this does not contain 97same as C<:const_asn :const_index>. Notably, this does not contain
96C<:const_ber_type> and C<:const_snmp>. 98C<:const_ber_type> and C<:const_snmp>.
97 99
98A good set to get everything you need to decode and match BER data would be 100A good set to get everything you need to decode and match BER data would be
99C<:decode :const>. 101C<:decode :const>.
100 102
101=item C<:const_index>> 103=item C<:const_index>
102 104
103The BER tuple array index constants: 105The BER tuple array index constants:
104 106
105 BER_CLASS BER_TAG BER_CONSTRUCTED BER_DATA 107 BER_CLASS BER_TAG BER_FLAGS BER_DATA
106 108
107=item C<:const_asn> 109=item C<:const_asn>
108 110
109ASN class values (these are C<0>, C<1>, C<2> and C<3>, reespectively - 111ASN class values (these are C<0>, C<1>, C<2> and C<3>, respectively -
110exactly thw two topmost bits from the identifdier octet shifted 6 bits to 112exactly the two topmost bits from the identifier octet shifted 6 bits to
111the right): 113the right):
112 114
113 ASN_UNIVERSAL ASN_APPLICATION ASN_CONTEXT ASN_PRIVATE 115 ASN_UNIVERSAL ASN_APPLICATION ASN_CONTEXT ASN_PRIVATE
114 116
115ASN tag values (some of which are aliases, such as C<ASN_OID>). Their 117ASN 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. 118numerical value corresponds exactly to the numbers used in BER/X.690.
117 119
118 ASN_BOOLEAN ASN_INTEGER32 ASN_BIT_STRING ASN_OCTET_STRING ASN_NULL ASN_OBJECT_IDENTIFIER 120 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 121 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 122 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 123 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 124 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 125 ASN_ISO646_STRING ASN_GENERAL_STRING ASN_UNIVERSAL_STRING ASN_CHARACTER_STRING ASN_BMP_STRING
124 126
134 136
135Constants only relevant to SNMP. These are the tag values used by SNMP in 137Constants 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 138the C<ASN_APPLICATION> namespace and have the exact numerical value as in
137BER/RFC 2578. 139BER/RFC 2578.
138 140
139 SNMP_IPADDRESS SNMP_COUNTER32 SNMP_UNSIGNED32 SNMP_TIMETICKS SNMP_OPAQUE SNMP_COUNTER64 141 SNMP_IPADDRESS SNMP_COUNTER32 SNMP_UNSIGNED32 SNMP_GAUGE32
142 SNMP_TIMETICKS SNMP_OPAQUE SNMP_COUNTER64
140 143
141=item C<:decode> 144=item C<:decode>
142 145
143C<ber_decode> and the match helper functions: 146C<ber_decode> and the match helper functions:
144 147
148 ber_decode ber-decode_prefix
145 ber_decode ber_is ber_is_seq ber_is_i32 ber_is_oid 149 ber_is ber_is_seq ber_is_int ber_is_oid
150 ber_dump
146 151
147=item C<:encode> 152=item C<:encode>
148 153
149C<ber_encode> and the construction helper functions: 154C<ber_encode> and the construction helper functions:
150 155
151 ber_encode ber_i32 156 ber_encode
157 ber_int
152 158
153=back 159=back
154 160
155=head2 ASN.1/BER/DER/... BASICS 161=head2 ASN.1/BER/DER/... BASICS
156 162
157ASN.1 is a strange language that can be used to describe protocols and 163ASN.1 is a strange language that can be used to describe protocols and
158data structures. It supports various mappings to JSON, XML, but most 164data structures. It supports various mappings to JSON, XML, but most
159importantly, to a various binary encodings such as BER, that is the topic 165importantly, to a various binary encodings such as BER, that is the topic
160of this module, and is used in SNMP or LDAP for example. 166of this module, and is used in SNMP, LDAP or X.509 for example.
161 167
162While ASN.1 defines a schema that is useful to interpret encoded data, 168While ASN.1 defines a schema that is useful to interpret encoded data,
163the BER encoding is actually somewhat self-describing: you might not know 169the BER encoding is actually somewhat self-describing: you might not know
164whether something is a string or a number or a sequence or something else, 170whether something is a string or a number or a sequence or something else,
165but you can nevertheless decode the overall structure, even if you end up 171but you can nevertheless decode the overall structure, even if you end up
167 173
168This works because BER values are tagged with a type and a namespace, 174This works because BER values are tagged with a type and a namespace,
169and also have a flag that says whether a value consists of subvalues (is 175and also have a flag that says whether a value consists of subvalues (is
170"constructed") or not (is "primitive"). 176"constructed") or not (is "primitive").
171 177
172Tags are simple integers, and ASN.1 defines a somewhat weird assortment of 178Tags are simple integers, and ASN.1 defines a somewhat weird assortment
173those - for example, you have 32 bit signed integers and 16(!) different 179of those - for example, you have one integer but 16(!) different
174string types, but there is no unsigned32 type for example. Different 180string types, but there is no Unsigned32 type for example. Different
175applications work around this in different ways, for example, SNMP defines 181applications work around this in different ways, for example, SNMP defines
176application-specific Gauge32, Counter32 and Unsigned32, which are mapped 182application-specific Gauge32, Counter32 and Unsigned32, which are mapped
177to two different tags: you can distinguish between Counter32 and the 183to two different tags: you can distinguish between Counter32 and the
178others, but not between Gause32 and Unsigned32, without the ASN.1 schema. 184others, but not between Gause32 and Unsigned32, without the ASN.1 schema.
179 185
182=head2 DECODED BER REPRESENTATION 188=head2 DECODED BER REPRESENTATION
183 189
184This module represents every BER value as a 4-element tuple (actually an 190This module represents every BER value as a 4-element tuple (actually an
185array-reference): 191array-reference):
186 192
187 [CLASS, TAG, CONSTRUCTED, DATA] 193 [CLASS, TAG, FLAGS, DATA]
194
195For example:
196
197 [ASN_UNIVERSAL, ASN_INTEGER, 0, 177] # the integer 177
198 [ASN_UNIVERSAL, ASN_OCTET_STRING, 0, "john"] # the string "john"
199 [ASN_UNIVERSAL, ASN_OID, 0, "1.3.6.133"] # some OID
200 [ASN_UNIVERSAL, ASN_SEQUENCE, 1, [ [ASN_UNIVERSAL... # a sequence
188 201
189To avoid non-descriptive hardcoded array index numbers, this module 202To avoid non-descriptive hardcoded array index numbers, this module
190defines symbolic constants to access these members: C<BER_CLASS>, 203defines symbolic constants to access these members: C<BER_CLASS>,
191C<BER_TAG>, C<BER_CONSTRUCTED> and C<BER_DATA>. 204C<BER_TAG>, C<BER_FLAGS> and C<BER_DATA>.
192 205
193Also, the first three members are integers with a little caveat: for 206Also, the first three members are integers with a little caveat: for
194performance reasons, these are readonly and shared, so you must not modify 207performance reasons, these are readonly and shared, so you must not modify
195them (increment, assign to them etc.) in any way. You may modify the 208them (increment, assign to them etc.) in any way. You may modify the
196I<DATA> member, and you may re-assign the array itself, e.g.: 209I<DATA> member, and you may re-assign the array itself, e.g.:
197 210
198 $ber = ber_decode $binbuf; 211 $ber = ber_decode $binbuf;
199 212
200 # the following is NOT legal: 213 # the following is NOT legal:
201 $ber->[BER_CLASS] = ASN_PRIVATE; # ERROR, CLASS/TAG/CONSTRUCTED are READ ONLY(!) 214 $ber->[BER_CLASS] = ASN_PRIVATE; # ERROR, CLASS/TAG/FLAGS are READ ONLY(!)
202 215
203 # but all of the following are fine: 216 # but all of the following are fine:
204 $ber->[BER_DATA] = "string"; 217 $ber->[BER_DATA] = "string";
205 $ber->[BER_DATA] = [ASN_UNIVERSAL, ASN_INTEGER32, 0, 123]; 218 $ber->[BER_DATA] = [ASN_UNIVERSAL, ASN_INTEGER, 0, 123];
206 @$ber = (ASN_APPLICATION, SNMP_TIMETICKS, 0, 1000); 219 @$ber = (ASN_APPLICATION, SNMP_TIMETICKS, 0, 1000);
207 220
208I<CLASS> is something like a namespace for I<TAG>s - there is the 221I<CLASS> is something like a namespace for I<TAG>s - there is the
209C<ASN_UNIVERSAL> namespace which defines tags common to all ASN.1 222C<ASN_UNIVERSAL> namespace which defines tags common to all ASN.1
210implementations, the C<ASN_APPLICATION> namespace which defines tags for 223implementations, the C<ASN_APPLICATION> namespace which defines tags for
211specific applications (for example, the SNMP C<Unsigned32> type is in this 224specific applications (for example, the SNMP C<Unsigned32> type is in this
212namespace), a special-purpose context namespace (C<ASN_CONTEXT>, used e.g. 225namespace), a special-purpose context namespace (C<ASN_CONTEXT>, used e.g.
213for C<CHOICE>) and a private namespace (C<ASN_PRIVATE>). 226for C<CHOICE>) and a private namespace (C<ASN_PRIVATE>).
214 227
215The meaning of the I<TAG> depends on the namespace, and defines a 228The meaning of the I<TAG> depends on the namespace, and defines a
216(partial) interpretation of the data value. For example, right now, SNMP 229(partial) interpretation of the data value. For example, SNMP defines
217application namespace knowledge ix hardcoded into this module, so it 230extra tags in the C<ASN_APPLICATION> namespace, and to take full advantage
218knows that SNMP C<Unsigned32> values need to be decoded into actual perl 231of these, you need to tell this module how to handle those via profiles.
219integers.
220 232
221The most common tags in the C<ASN_UNIVERSAL> namespace are 233The most common tags in the C<ASN_UNIVERSAL> namespace are
222C<ASN_INTEGER32>, C<ASN_BIT_STRING>, C<ASN_NULL>, C<ASN_OCTET_STRING>, 234C<ASN_INTEGER>, C<ASN_BIT_STRING>, C<ASN_NULL>, C<ASN_OCTET_STRING>,
223C<ASN_OBJECT_IDENTIFIER>, C<ASN_SEQUENCE>, C<ASN_SET> and 235C<ASN_OBJECT_IDENTIFIER>, C<ASN_SEQUENCE>, C<ASN_SET> and
224C<ASN_IA5_STRING>. 236C<ASN_IA5_STRING>.
225 237
226The most common tags in SNMP's C<ASN_APPLICATION> namespace 238The most common tags in SNMP's C<ASN_APPLICATION> namespace are
227are C<SNMP_IPADDRESS>, C<SNMP_COUNTER32>, C<SNMP_UNSIGNED32>, 239C<SNMP_COUNTER32>, C<SNMP_UNSIGNED32>, C<SNMP_TIMETICKS> and
228C<SNMP_TIMETICKS>, C<SNMP_OPAQUE> and C<SNMP_COUNTER64>. 240C<SNMP_COUNTER64>.
229 241
230The I<CONSTRUCTED> flag is really just a boolean - if it is false, the 242The I<FLAGS> value is really just a boolean at this time (but might
231the value is "primitive" and contains no subvalues, kind of like a 243get extended) - if it is C<0>, the value is "primitive" and contains
232non-reference perl scalar. IF it is true, then the value is "constructed" 244no subvalues, kind of like a non-reference perl scalar. If it is C<1>,
233which just means it contains a list of subvalues which this module will 245then the value is "constructed" which just means it contains a list of
234en-/decode as BER tuples themselves. 246subvalues which this module will en-/decode as BER tuples themselves.
235 247
236The I<DATA> value is either a reference to an array of further tuples (if 248The I<DATA> value is either a reference to an array of further tuples
237the value is I<CONSTRUCTED>), some decoded representation of the value, 249(if the value is I<FLAGS>), some decoded representation of the value, if
238if this module knows how to decode it (e.g. for the integer types above) 250this module knows how to decode it (e.g. for the integer types above) or
239or a binary string with the raw octets if this module doesn't know how to 251a binary string with the raw octets if this module doesn't know how to
240interpret the namespace/tag. 252interpret the namespace/tag.
241 253
242Thus, you can always decode a BER data structure and at worst you get a 254Thus, you can always decode a BER data structure and at worst you get a
243string in place of some nice decoded value. 255string in place of some nice decoded value.
244 256
246 258
247=head2 DECODING AND ENCODING 259=head2 DECODING AND ENCODING
248 260
249=over 261=over
250 262
251=item $tuple = ber_decoded $bindata 263=item $tuple = ber_decode $bindata[, $profile]
252 264
253Decodes binary BER data in C<$bindata> and returns the resulting BER 265Decodes binary BER data in C<$bindata> and returns the resulting BER
254tuple. Croaks on any decoding error, so the returned C<$tuple> is always 266tuple. Croaks on any decoding error, so the returned C<$tuple> is always
255valid. 267valid.
256 268
269How tags are interpreted is defined by the second argument, which must
270be a C<Convert::BER::XS::Profile> object. If it is missing, the default
271profile will be used (C<$Convert::BER::XS::DEFAULT_PROFILE>).
272
273In addition to rolling your own, this module provides a
274C<$Convert::BER::XS::SNMP_PROFILE> that knows about the additional SNMP
275types.
276
277Example: decode a BER blob using the default profile - SNMP values will be
278decided as raw strings.
279
280 $tuple = ber_decode $data;
281
282Example: as above, but use the provided SNMP profile.
283
284 $tuple = ber_encode $data, $Convert::BER::XS::SNMP_PROFILE;
285
286=item ($tuple, $bytes) = ber_decode_prefix $bindata[, $profile]
287
288Works like C<ber_decode>, except it doesn't croak when there is data after
289the BER data, but instead returns the decoded value and the number of
290bytes it decoded.
291
292This is useful when you have BER data at the start of a buffer and other
293data after, and you need to find the length.
294
295Also, since BER is self-delimited, this can be used to decode multiple BER
296values joined together.
297
257=item $bindata = ber_encode $tuple 298=item $bindata = ber_encode $tuple[, $profile]
258 299
259Encodes the BER tuple into a BER/DER data structure. 300Encodes the BER tuple into a BER/DER data structure. As with
301Cyber_decode>, an optional profile can be given.
302
303The encoded data should be both BER and DER ("shortest form") compliant
304unless the input says otherwise (e.g. it uses constructed strings).
260 305
261=back 306=back
262 307
263=head2 HELPER FUNCTIONS 308=head2 HELPER FUNCTIONS
264 309
265Working with a 4-tuple for every value can be annoying. Or, rather, I<is> 310Working with a 4-tuple for every value can be annoying. Or, rather, I<is>
266annoying. To reduce this a bit, this module defines a number of helper 311annoying. To reduce this a bit, this module defines a number of helper
267functions, both to match BER tuples and to conmstruct BER tuples: 312functions, both to match BER tuples and to construct BER tuples:
268 313
269=head3 MATCH HELPERS 314=head3 MATCH HELPERS
270 315
271Thse functions accept a BER tuple as first argument and either paertially 316These functions accept a BER tuple as first argument and either partially
272or fully match it. They often come in two forms, one which exactly matches 317or fully match it. They often come in two forms, one which exactly matches
273a value, and one which only matches the type and returns the value. 318a value, and one which only matches the type and returns the value.
274 319
275They do check whether valid tuples are passed in and croak otherwise. As 320They do check whether valid tuples are passed in and croak otherwise. As
276a ease-of-use exception, they usually also accept C<undef> instead of a 321a ease-of-use exception, they usually also accept C<undef> instead of a
277tuple reference. in which case they silently fail to match. 322tuple reference, in which case they silently fail to match.
278 323
279=over 324=over
280 325
281=item $bool = ber_is $tuple, $class, $tag, $constructed, $data 326=item $bool = ber_is $tuple, $class, $tag, $flags, $data
282 327
283This takes a BER C<$tuple> and matches its elements agains the privded 328This takes a BER C<$tuple> and matches its elements against the provided
284values, all of which are optional - values that are either missing or 329values, all of which are optional - values that are either missing or
285C<undef> will be ignored, the others will be matched exactly (e.g. as if 330C<undef> will be ignored, the others will be matched exactly (e.g. as if
286you used C<==> or C<eq> (for C<$data>)). 331you used C<==> or C<eq> (for C<$data>)).
287 332
288Some examples: 333Some examples:
291 orf die "tuple is not an ASN SEQUENCE"; 336 orf die "tuple is not an ASN SEQUENCE";
292 337
293 ber_is $tuple, ASN_UNIVERSAL, ASN_NULL 338 ber_is $tuple, ASN_UNIVERSAL, ASN_NULL
294 or die "tuple is not an ASN NULL value"; 339 or die "tuple is not an ASN NULL value";
295 340
296 ber_is $tuple, ASN_UNIVERSAL, ASN_INTEGER32, 0, 50 341 ber_is $tuple, ASN_UNIVERSAL, ASN_INTEGER, 0, 50
297 or die "BER integer must be 50"; 342 or die "BER integer must be 50";
298 343
299=item $seq = ber_is_seq $tuple 344=item $seq = ber_is_seq $tuple
300 345
301Returns the sequence members (the array of subvalues) if the C<$tuple> is 346Returns the sequence members (the array of subvalues) if the C<$tuple> is
308 my $snmp = ber_is_seq $ber 353 my $snmp = ber_is_seq $ber
309 or die "SNMP packet invalid: does not start with SEQUENCE"; 354 or die "SNMP packet invalid: does not start with SEQUENCE";
310 355
311 # now we know $snmp is a sequence, so decode the SNMP version 356 # now we know $snmp is a sequence, so decode the SNMP version
312 357
313 my $version = ber_is_i32 $snmp->[0] 358 my $version = ber_is_int $snmp->[0]
314 or die "SNMP packet invalid: does not start with version number"; 359 or die "SNMP packet invalid: does not start with version number";
315 360
316=item $bool = ber_is_i32 $tuple, $i32 361=item $bool = ber_is_int $tuple, $int
317 362
318Returns a true value if the C<$tuple> represents an ASN INTEGER32 with 363Returns a true value if the C<$tuple> represents an ASN INTEGER with
319the value C<$i32>. 364the value C<$int>.
320 365
321=item $i32 = ber_is_i32 $tuple 366=item $int = ber_is_int $tuple
322 367
323Returns true (and extracts the integer value) if the C<$tuple> is an ASN 368Returns true (and extracts the integer value) if the C<$tuple> is an
324INTEGER32. For C<0>, this function returns a special value that is 0 but 369C<ASN_INTEGER>. For C<0>, this function returns a special value that is 0
325true. 370but true.
326 371
327=item $bool = ber_is_oid $tuple, $oid_string 372=item $bool = ber_is_oid $tuple, $oid_string
328 373
329Returns true if the C<$tuple> represents an ASN_OBJECT_IDENTIFIER 374Returns true if the C<$tuple> represents an ASN_OBJECT_IDENTIFIER
330that exactly matches C<$oid_string>. Example: 375that exactly matches C<$oid_string>. Example:
341 386
342=head3 CONSTRUCTION HELPERS 387=head3 CONSTRUCTION HELPERS
343 388
344=over 389=over
345 390
346=item $tuple = ber_i32 $value 391=item $tuple = ber_int $value
347 392
348Constructs a new C<ASN_INTEGER32> tuple. 393Constructs a new C<ASN_INTEGER> tuple.
349 394
350=back 395=back
351 396
352=head2 RELATIONSHIP TO L<Convert::BER> and L<Convert::ASN1> 397=head2 RELATIONSHIP TO L<Convert::BER> and L<Convert::ASN1>
353 398
363use common::sense; 408use common::sense;
364 409
365use XSLoader (); 410use XSLoader ();
366use Exporter qw(import); 411use Exporter qw(import);
367 412
413use Carp ();
414
368our $VERSION; 415our $VERSION;
369 416
370BEGIN { 417BEGIN {
371 $VERSION = 0.8; 418 $VERSION = 1.21;
372 XSLoader::load __PACKAGE__, $VERSION; 419 XSLoader::load __PACKAGE__, $VERSION;
373} 420}
374 421
375our %EXPORT_TAGS = ( 422our %EXPORT_TAGS = (
376 const_index => [qw( 423 const_index => [qw(
377 BER_CLASS BER_TAG BER_CONSTRUCTED BER_DATA 424 BER_CLASS BER_TAG BER_FLAGS BER_DATA
378 )], 425 )],
426 const_asn_class => [qw(
427 ASN_UNIVERSAL ASN_APPLICATION ASN_CONTEXT ASN_PRIVATE
428 )],
379 const_asn => [qw( 429 const_asn_tag => [qw(
380 ASN_BOOLEAN ASN_INTEGER32 ASN_BIT_STRING ASN_OCTET_STRING ASN_NULL ASN_OBJECT_IDENTIFIER 430 ASN_BOOLEAN ASN_INTEGER ASN_BIT_STRING ASN_OCTET_STRING ASN_NULL ASN_OID ASN_OBJECT_IDENTIFIER
381 ASN_OBJECT_DESCRIPTOR ASN_OID ASN_EXTERNAL ASN_REAL ASN_SEQUENCE ASN_ENUMERATED 431 ASN_OBJECT_DESCRIPTOR ASN_EXTERNAL ASN_REAL ASN_SEQUENCE ASN_ENUMERATED
382 ASN_EMBEDDED_PDV ASN_UTF8_STRING ASN_RELATIVE_OID ASN_SET ASN_NUMERIC_STRING 432 ASN_EMBEDDED_PDV ASN_UTF8_STRING ASN_RELATIVE_OID ASN_SET ASN_NUMERIC_STRING
383 ASN_PRINTABLE_STRING ASN_TELETEX_STRING ASN_T61_STRING ASN_VIDEOTEX_STRING ASN_IA5_STRING 433 ASN_PRINTABLE_STRING ASN_TELETEX_STRING ASN_T61_STRING ASN_VIDEOTEX_STRING ASN_IA5_STRING
384 ASN_ASCII_STRING ASN_UTC_TIME ASN_GENERALIZED_TIME ASN_GRAPHIC_STRING ASN_VISIBLE_STRING 434 ASN_ASCII_STRING ASN_UTC_TIME ASN_GENERALIZED_TIME ASN_GRAPHIC_STRING ASN_VISIBLE_STRING
385 ASN_ISO646_STRING ASN_GENERAL_STRING ASN_UNIVERSAL_STRING ASN_CHARACTER_STRING ASN_BMP_STRING 435 ASN_ISO646_STRING ASN_GENERAL_STRING ASN_UNIVERSAL_STRING ASN_CHARACTER_STRING ASN_BMP_STRING
386
387 ASN_UNIVERSAL ASN_APPLICATION ASN_CONTEXT ASN_PRIVATE
388 )], 436 )],
389 const_ber_type => [qw( 437 const_ber_type => [qw(
390 BER_TYPE_BYTES BER_TYPE_UTF8 BER_TYPE_UCS2 BER_TYPE_UCS4 BER_TYPE_INT 438 BER_TYPE_BYTES BER_TYPE_UTF8 BER_TYPE_UCS2 BER_TYPE_UCS4 BER_TYPE_INT
391 BER_TYPE_OID BER_TYPE_RELOID BER_TYPE_NULL BER_TYPE_BOOL BER_TYPE_REAL 439 BER_TYPE_OID BER_TYPE_RELOID BER_TYPE_NULL BER_TYPE_BOOL BER_TYPE_REAL
392 BER_TYPE_IPADDRESS BER_TYPE_CROAK 440 BER_TYPE_IPADDRESS BER_TYPE_CROAK
393 )], 441 )],
394 const_snmp => [qw( 442 const_snmp => [qw(
395 SNMP_IPADDRESS SNMP_COUNTER32 SNMP_UNSIGNED32 SNMP_TIMETICKS SNMP_OPAQUE SNMP_COUNTER64 443 SNMP_IPADDRESS SNMP_COUNTER32 SNMP_GAUGE32 SNMP_UNSIGNED32
444 SNMP_TIMETICKS SNMP_OPAQUE SNMP_COUNTER64
396 )], 445 )],
397 decode => [qw( 446 decode => [qw(
398 ber_decode 447 ber_decode ber_decode_prefix
399 ber_is ber_is_seq ber_is_i32 ber_is_oid 448 ber_is ber_is_seq ber_is_int ber_is_oid
449 ber_dump
400 )], 450 )],
401 encode => [qw( 451 encode => [qw(
402 ber_encode 452 ber_encode
403 ber_i32 453 ber_int
404 )], 454 )],
405); 455);
406 456
407our @EXPORT_OK = map @$_, values %EXPORT_TAGS; 457our @EXPORT_OK = map @$_, values %EXPORT_TAGS;
408 458
409$EXPORT_TAGS{all} = \@EXPORT_OK; 459$EXPORT_TAGS{all} = \@EXPORT_OK;
460$EXPORT_TAGS{const_asn} = [map @{ $EXPORT_TAGS{$_} }, qw(const_asn_class const_asn_tag)];
410$EXPORT_TAGS{const} = [map @{ $EXPORT_TAGS{$_} }, qw(const_index const_asn)]; 461$EXPORT_TAGS{const} = [map @{ $EXPORT_TAGS{$_} }, qw(const_index const_asn)];
411use Data::Dump; ddx \%EXPORT_TAGS; 462
463our $DEFAULT_PROFILE = new Convert::BER::XS::Profile;
464
465$DEFAULT_PROFILE->_set_default;
466
467# additional SNMP application types
468our $SNMP_PROFILE = new Convert::BER::XS::Profile;
469
470$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_IPADDRESS , BER_TYPE_IPADDRESS);
471$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_COUNTER32 , BER_TYPE_INT);
472$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_COUNTER64 , BER_TYPE_INT);
473$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_UNSIGNED32, BER_TYPE_INT);
474$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_TIMETICKS , BER_TYPE_INT);
475
476# decodes REAL values according to ECMA-63
477# this is pretty strict, except it doesn't catch -0.
478# I don't have access to ISO 6093 (or BS 6727, or ANSI X.3-42)), so this is all guesswork.
479sub _decode_real_decimal {
480 my ($format, $val) = @_;
481
482 $val =~ y/,/./; # probably not in ISO-6093
483
484 if ($format == 1) {
485 $val =~ /^ \ * [+-]? [0-9]+ \z/x
486 or Carp::croak "BER_TYPE_REAL NR1 value not in NR1 format ($val) (X.690 8.5.8)";
487 } elsif ($format == 2) {
488 $val =~ /^ \ * [+-]? (?: [0-9]+\.[0-9]* | [0-9]*\.[0-9]+ ) \z/x
489 or Carp::croak "BER_TYPE_REAL NR2 value not in NR2 format ($val) (X.690 8.5.8)";
490 } elsif ($format == 3) {
491 $val =~ /^ \ * [+-] (?: [0-9]+\.[0-9]* | [0-9]*\.[0-9]+ ) [eE] [+-]? [0-9]+ \z/x
492 or Carp::croak "BER_TYPE_REAL NR3 value not in NR3 format ($val) (X.690 8.5.8)";
493 } else {
494 Carp::croak "BER_TYPE_REAL invalid decimal numerical representation format $format";
495 }
496
497 $val
498}
499
500# this is a mess, but perl's support for floating point formatting is nearly nonexistant
501sub _encode_real_decimal {
502 my ($val, $nvdig) = @_;
503
504 $val = sprintf "%.*G", $nvdig + 1, $val;
505
506 if ($val =~ /E/) {
507 $val =~ s/E(?=[^+-])/E+/;
508 $val =~ s/E/.E/ if $val !~ /\./;
509 $val =~ s/^/+/ unless $val =~ /^-/;
510
511 return "\x03$val" # NR3
512 }
513
514 $val =~ /\./
515 ? "\x02$val" # NR2
516 : "\x01$val" # NR1
517}
518
519=head2 DEBUGGING
520
521To aid debugging, you can call the C<ber_dump> function to print a "nice"
522representation to STDOUT.
523
524=over
525
526=item ber_dump $tuple[, $profile[, $prefix]]
527
528In addition to specifying the BER C<$tuple> to dump, you can also specify
529a C<$profile> and a C<$prefix> string that is printed in front of each line.
530
531If C<$profile> is C<$Convert::BER::XS::SNMP_PROFILE>, then C<ber_dump>
532will try to improve its output for SNMP data.
533
534The output usually contains three columns, the "human readable" tag, the
535BER type used to decode it, and the data value.
536
537This function is somewhat slow and uses a number of heuristics and tricks,
538so it really is only suitable for debug prints.
539
540Example output:
541
542 SEQUENCE
543 | OCTET_STRING bytes 800063784300454045045400000001
544 | OCTET_STRING bytes
545 | CONTEXT (7) CONSTRUCTED
546 | | INTEGER int 1058588941
547 | | INTEGER int 0
548 | | INTEGER int 0
549 | | SEQUENCE
550 | | | SEQUENCE
551 | | | | OID oid 1.3.6.1.2.1.1.3.0
552 | | | | TIMETICKS int 638085796
553
554=back
555
556=cut
557
558# reverse enum, very slow and ugly hack
559sub _re {
560 my ($export_tag, $value) = @_;
561
562 for my $symbol (@{ $EXPORT_TAGS{$export_tag} }) {
563 $value == eval $symbol
564 and return $symbol;
565 }
566
567 "($value)"
568}
569
570sub _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, $data;
611 }
612 }
613}
614
615sub ber_dump($;$$) {
616 _ber_dump $_[0], $_[1] || $DEFAULT_PROFILE, $_[2];
617}
412 618
413=head1 PROFILES 619=head1 PROFILES
414 620
415While any BER data can be correctly encoded and decoded out of the box, it 621While any BER data can be correctly encoded and decoded out of the box, it
416can be inconvenient to have to manually decode some values into a "better" 622can be inconvenient to have to manually decode some values into a "better"
442=item C<$Convert::BER::XS::SNMP_PROFILE> 648=item C<$Convert::BER::XS::SNMP_PROFILE>
443 649
444A profile with mappings for SNMP-specific application tags added. This is 650A profile with mappings for SNMP-specific application tags added. This is
445useful when de-/encoding SNMP data. 651useful when de-/encoding SNMP data.
446 652
653The L<Example Profile> section, below, shows how this profile is being
654constructed.
655
447Example: 656Example:
448 657
449 $ber = ber_decode $data, $Convert::BER::XS::SNMP_PROFILE; 658 $ber = ber_decode $data, $Convert::BER::XS::SNMP_PROFILE;
450 659
451=back 660=back
477 686
478Returns the BER type mapped to the given C<$class>/C<$tag> combination. 687Returns the BER type mapped to the given C<$class>/C<$tag> combination.
479 688
480=back 689=back
481 690
482=head2 BER TYPES 691=head2 BER Types
483 692
484This lists the predefined BER types - you can map any C<CLASS>/C<TAG> 693This lists the predefined BER types. BER types are formatters used
485combination to any C<BER_TYPE_*>. 694internally to format and encode BER values. You can assign any C<BER_TYPE>
695to any C<CLASS>/C<TAG> combination tgo change how that tag is decoded or
696encoded.
486 697
487=over 698=over
488 699
489=item C<BER_TYPE_BYTES> 700=item C<BER_TYPE_BYTES>
490 701
519dot, e.g. C<1.3.6.1.213>. 730dot, e.g. C<1.3.6.1.213>.
520 731
521=item C<BER_TYPE_RELOID> 732=item C<BER_TYPE_RELOID>
522 733
523Same as C<BER_TYPE_OID> but uses relative object identifier 734Same as C<BER_TYPE_OID> but uses relative object identifier
524encoding: ASN.1 has this hack of encoding the first two OID components 735encoding: ASN.1 uses some hack encoding of the first two OID components
525into a single integer in a weird attempt to save an insignificant amount 736into a single integer in a weird attempt to save an insignificant amount
526of space in an otherwise wasteful encoding, and relative OIDs are 737of space in an otherwise wasteful encoding, and relative OIDs are
527basically OIDs without this hack. The practical difference is that the 738basically OIDs without this hack. The practical difference is that the
528second component of an OID can only have the values 1..40, while relative 739second component of an OID can only have the values 1..40, while relative
529OIDs do not have this restriction. 740OIDs do not have this restriction.
556C<BER_TYPE_BYTES>. When you don't want that but instead prefer a hard 767C<BER_TYPE_BYTES>. When you don't want that but instead prefer a hard
557error for some types, then C<BER_TYPE_CROAK> is for you. 768error for some types, then C<BER_TYPE_CROAK> is for you.
558 769
559=back 770=back
560 771
561=cut 772=head2 Example Profile
562 773
563our $DEFAULT_PROFILE = new Convert::BER::XS::Profile; 774The following creates a profile suitable for SNMP - it's exactly identical
775to the C<$Convert::BER::XS::SNMP_PROFILE> profile.
776
564our $SNMP_PROFILE = new Convert::BER::XS::Profile; 777 our $SNMP_PROFILE = new Convert::BER::XS::Profile;
565 778
566# additional SNMP application types
567$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_IPADDRESS , BER_TYPE_IPADDRESS); 779 $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_IPADDRESS , BER_TYPE_IPADDRESS);
568$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_COUNTER32 , BER_TYPE_INT); 780 $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_COUNTER32 , BER_TYPE_INT);
569$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_UNSIGNED32, BER_TYPE_INT); 781 $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_UNSIGNED32, BER_TYPE_INT);
570$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_TIMETICKS , BER_TYPE_INT); 782 $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_TIMETICKS , BER_TYPE_INT);
571$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_OPAQUE , BER_TYPE_IPADDRESS); 783 $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_OPAQUE , BER_TYPE_BYTES);
572$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_COUNTER64 , BER_TYPE_INT); 784 $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_COUNTER64 , BER_TYPE_INT);
573
574$DEFAULT_PROFILE->_set_default;
575
5761;
577 785
578=head2 LIMITATIONS/NOTES 786=head2 LIMITATIONS/NOTES
579 787
580This module can only en-/decode 64 bit signed and unsigned integers, and 788This module can only en-/decode 64 bit signed and unsigned
581only when your perl supports those. 789integers/tags/lengths, and only when your perl supports those. So no UUID
790OIDs for now (unless you map the C<OBJECT IDENTIFIER> tag to something
791other than C<BER_TYPE_OID>).
582 792
583This module does not generally care about ranges, i.e. it will happily 793This module does not generally care about ranges, i.e. it will happily
584de-/encode 64 bit integers into an C<ASN_INTEGER32> value, or a negative 794de-/encode 64 bit integers into an C<SNMP_UNSIGNED32> value, or a negative
585number into an C<SNMP_COUNTER64>. 795number into an C<SNMP_COUNTER64>.
586 796
587OBJECT IDENTIFIEERs cannot have unlimited length, although the limit is 797OBJECT IDENTIFIEERs cannot have unlimited length, although the limit is
588much larger than e.g. the one imposed by SNMP or other protocols,a nd is 798much larger than e.g. the one imposed by SNMP or other protocols, and is
589about 4kB. 799about 4kB.
590 800
591REAL values are not supported and will currently croak. 801Constructed strings are decoded just fine, but there should be a way to
802join them for convenience.
592 803
593This module has undergone little to no testing so far. 804REAL values will always be encoded in decimal form and ssometimes is
805forced into a perl "NV" type, potentially losing precision.
594 806
595=head2 ITHREADS SUPPORT 807=head2 ITHREADS SUPPORT
596 808
597This module is unlikely to work when the (officially discouraged) ithreads 809This module is unlikely to work in any other than the loading thread when
598are in use. 810the (officially discouraged) ithreads are in use.
599 811
600=head1 AUTHOR 812=head1 AUTHOR
601 813
602 Marc Lehmann <schmorp@schmorp.de> 814 Marc Lehmann <schmorp@schmorp.de>
603 http://software.schmorp.de/pkg/Convert-BER-XS 815 http://software.schmorp.de/pkg/Convert-BER-XS
604 816
605=cut 817=cut
606 818
8191;
820

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