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Revision 1.21 by root, Sat Apr 20 14:49:56 2019 UTC vs.
Revision 1.62 by root, Thu Feb 6 23:15:44 2020 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?
19 19
20 [ ASN_UNIVERSAL, ASN_SEQUENCE, 1, 20 [ ASN_UNIVERSAL, ASN_SEQUENCE, 1,
21 [ 21 [
22 [ ASN_UNIVERSAL, ASN_INTEGER32, 0, 0 ], # snmp version 1 22 [ ASN_UNIVERSAL, ASN_INTEGER, 0, 0 ], # snmp version 1
23 [ ASN_UNIVERSAL, 4, 0, "public" ], # community 23 [ ASN_UNIVERSAL, 4, 0, "public" ], # community
24 [ ASN_CONTEXT, 4, 1, # CHOICE, constructed - trap PDU 24 [ ASN_CONTEXT, 4, 1, # CHOICE, constructed - trap PDU
25 [ 25 [
26 [ 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
27 [ ASN_APPLICATION, SNMP_IPADDRESS, 0, "10.0.0.1" ], # SNMP IpAddress 27 [ ASN_APPLICATION, SNMP_IPADDRESS, 0, "10.0.0.1" ], # SNMP IpAddress
28 [ ASN_UNIVERSAL, ASN_INTEGER32, 0, 6 ], # generic trap 28 [ ASN_UNIVERSAL, ASN_INTEGER, 0, 6 ], # generic trap
29 [ ASN_UNIVERSAL, ASN_INTEGER32, 0, 1 ], # specific trap 29 [ ASN_UNIVERSAL, ASN_INTEGER, 0, 1 ], # specific trap
30 [ ASN_APPLICATION, SNMP_TIMETICKS, 0, 1817903850 ], # SNMP TimeTicks 30 [ ASN_APPLICATION, SNMP_TIMETICKS, 0, 1817903850 ], # SNMP TimeTicks
31 [ ASN_UNIVERSAL, ASN_SEQUENCE, 1, # the varbindlist 31 [ ASN_UNIVERSAL, ASN_SEQUENCE, 1, # the varbindlist
32 [ 32 [
33 [ ASN_UNIVERSAL, ASN_SEQUENCE, 1, # a single varbind, "key value" pair 33 [ ASN_UNIVERSAL, ASN_SEQUENCE, 1, # a single varbind, "key value" pair
34 [ 34 [
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";
46 49
47 ber_is $msg->[0], ASN_UNIVERSAL, ASN_INTEGER32, 0 50 ber_is $msg->[0], ASN_UNIVERSAL, ASN_INTEGER, 0
48 or die "SNMP message does not start with snmp version\n"; 51 or die "SNMP message does not start with snmp version\n";
49 52
50 # message is SNMP v1 or v2c? 53 # message is SNMP v1 or v2c?
51 if ($msg->[0][BER_DATA] == 0 || $msg->[0][BER_DATA] == 1) { 54 if ($msg->[0][BER_DATA] == 0 || $msg->[0][BER_DATA] == 1) {
52 55
55 my $trap = $msg->[2][BER_DATA]; 58 my $trap = $msg->[2][BER_DATA];
56 59
57 # check whether trap is a cisco mac notification mac changed message 60 # check whether trap is a cisco mac notification mac changed message
58 if ( 61 if (
59 (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
60 and (ber_is_i32 $trap->[2], 6) 63 and (ber_is_int $trap->[2], 6)
61 and (ber_is_i32 $trap->[3], 1) # mac changed msg 64 and (ber_is_int $trap->[3], 1) # mac changed msg
62 ) { 65 ) {
63 ... and so on 66 ... and so on
64 67
65 # 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
66 69
67 my $buf = ber_encode $ber, $Convert::BER::XS::SNMP_PROFILE; 70 my $buf = ber_encode $ber, $Convert::BER::XS::SNMP_PROFILE;
68 71
69=head1 DESCRIPTION 72=head1 DESCRIPTION
70 73
71WARNING: Before release 1.0, the API is not considered stable in any way.
72
73This module implements a I<very> low level BER/DER en-/decoder. 74This module implements a I<very> low level BER/DER en-/decoder.
74 75
75It is tuned for low memory and high speed, while still maintaining some 76It is tuned for low memory and high speed, while still maintaining some
76level of user-friendlyness. 77level of user-friendlyness.
77 78
78=head2 EXPORT TAGS AND CONSTANTS 79=head2 EXPORT TAGS AND CONSTANTS
79 80
80By default this module doesn't export any symbols, but if you don't want 81By 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 82to break your keyboard, editor or eyesight with extremely long names, I
82recommend importing the C<:all> tag. Still, you can selectively import 83recommend importing the C<:all> tag. Still, you can selectively import
83things. 84things.
84 85
85=over 86=over
86 87
87=item C<:all> 88=item C<:all>
88 89
89All of the below. Really. Rcommended for at least first steps, or if you 90All 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). 91don't care about a few kilobytes of wasted memory (and namespace).
91 92
92=item C<:const> 93=item C<:const>
93 94
94All of the stricly ASN.1-related constants defined by this module, the 95All of the strictly ASN.1-related constants defined by this module, the
95same as C<:const_asn :const_index>. Notably, this does not contain 96same as C<:const_asn :const_index>. Notably, this does not contain
96C<:const_ber_type> and C<:const_snmp>. 97C<:const_ber_type> and C<:const_snmp>.
97 98
98A good set to get everything you need to decode and match BER data would be 99A good set to get everything you need to decode and match BER data would be
99C<:decode :const>. 100C<:decode :const>.
100 101
101=item C<:const_index>> 102=item C<:const_index>
102 103
103The BER tuple array index constants: 104The BER tuple array index constants:
104 105
105 BER_CLASS BER_TAG BER_CONSTRUCTED BER_DATA 106 BER_CLASS BER_TAG BER_FLAGS BER_DATA
106 107
107=item C<:const_asn> 108=item C<:const_asn>
108 109
109ASN class values (these are C<0>, C<1>, C<2> and C<3>, reespectively - 110ASN 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 111exactly the two topmost bits from the identifier octet shifted 6 bits to
111the right): 112the right):
112 113
113 ASN_UNIVERSAL ASN_APPLICATION ASN_CONTEXT ASN_PRIVATE 114 ASN_UNIVERSAL ASN_APPLICATION ASN_CONTEXT ASN_PRIVATE
114 115
115ASN tag values (some of which are aliases, such as C<ASN_OID>). Their 116ASN 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. 117numerical value corresponds exactly to the numbers used in BER/X.690.
117 118
118 ASN_BOOLEAN ASN_INTEGER32 ASN_BIT_STRING ASN_OCTET_STRING ASN_NULL ASN_OBJECT_IDENTIFIER 119 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 120 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 121 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 122 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 123 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 124 ASN_ISO646_STRING ASN_GENERAL_STRING ASN_UNIVERSAL_STRING ASN_CHARACTER_STRING ASN_BMP_STRING
124 125
134 135
135Constants only relevant to SNMP. These are the tag values used by SNMP in 136Constants 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 137the C<ASN_APPLICATION> namespace and have the exact numerical value as in
137BER/RFC 2578. 138BER/RFC 2578.
138 139
139 SNMP_IPADDRESS SNMP_COUNTER32 SNMP_UNSIGNED32 SNMP_TIMETICKS SNMP_OPAQUE SNMP_COUNTER64 140 SNMP_IPADDRESS SNMP_COUNTER32 SNMP_UNSIGNED32 SNMP_GAUGE32
141 SNMP_TIMETICKS SNMP_OPAQUE SNMP_COUNTER64
140 142
141=item C<:decode> 143=item C<:decode>
142 144
143C<ber_decode> and the match helper functions: 145C<ber_decode> and the match helper functions:
144 146
147 ber_decode ber-decode_prefix
145 ber_decode ber_is ber_is_seq ber_is_i32 ber_is_oid 148 ber_is ber_is_seq ber_is_int ber_is_oid
149 ber_dump
146 150
147=item C<:encode> 151=item C<:encode>
148 152
149C<ber_encode> and the construction helper functions: 153C<ber_encode> and the construction helper functions:
150 154
151 ber_encode ber_i32 155 ber_encode
156 ber_int
152 157
153=back 158=back
154 159
155=head2 ASN.1/BER/DER/... BASICS 160=head2 ASN.1/BER/DER/... BASICS
156 161
157ASN.1 is a strange language that can be used to describe protocols and 162ASN.1 is a strange language that can be used to describe protocols and
158data structures. It supports various mappings to JSON, XML, but most 163data structures. It supports various mappings to JSON, XML, but most
159importantly, to a various binary encodings such as BER, that is the topic 164importantly, to a various binary encodings such as BER, that is the topic
160of this module, and is used in SNMP or LDAP for example. 165of this module, and is used in SNMP, LDAP or X.509 for example.
161 166
162While ASN.1 defines a schema that is useful to interpret encoded data, 167While ASN.1 defines a schema that is useful to interpret encoded data,
163the BER encoding is actually somewhat self-describing: you might not know 168the 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, 169whether 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 170but you can nevertheless decode the overall structure, even if you end up
167 172
168This works because BER values are tagged with a type and a namespace, 173This 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 174and also have a flag that says whether a value consists of subvalues (is
170"constructed") or not (is "primitive"). 175"constructed") or not (is "primitive").
171 176
172Tags are simple integers, and ASN.1 defines a somewhat weird assortment of 177Tags are simple integers, and ASN.1 defines a somewhat weird assortment
173those - for example, you have 32 bit signed integers and 16(!) different 178of those - for example, you have one integers and 16(!) different
174string types, but there is no unsigned32 type for example. Different 179string types, but there is no Unsigned32 type for example. Different
175applications work around this in different ways, for example, SNMP defines 180applications work around this in different ways, for example, SNMP defines
176application-specific Gauge32, Counter32 and Unsigned32, which are mapped 181application-specific Gauge32, Counter32 and Unsigned32, which are mapped
177to two different tags: you can distinguish between Counter32 and the 182to two different tags: you can distinguish between Counter32 and the
178others, but not between Gause32 and Unsigned32, without the ASN.1 schema. 183others, but not between Gause32 and Unsigned32, without the ASN.1 schema.
179 184
182=head2 DECODED BER REPRESENTATION 187=head2 DECODED BER REPRESENTATION
183 188
184This module represents every BER value as a 4-element tuple (actually an 189This module represents every BER value as a 4-element tuple (actually an
185array-reference): 190array-reference):
186 191
187 [CLASS, TAG, CONSTRUCTED, DATA] 192 [CLASS, TAG, FLAGS, DATA]
193
194For 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
188 200
189To avoid non-descriptive hardcoded array index numbers, this module 201To avoid non-descriptive hardcoded array index numbers, this module
190defines symbolic constants to access these members: C<BER_CLASS>, 202defines symbolic constants to access these members: C<BER_CLASS>,
191C<BER_TAG>, C<BER_CONSTRUCTED> and C<BER_DATA>. 203C<BER_TAG>, C<BER_FLAGS> and C<BER_DATA>.
192 204
193Also, the first three members are integers with a little caveat: for 205Also, the first three members are integers with a little caveat: for
194performance reasons, these are readonly and shared, so you must not modify 206performance reasons, these are readonly and shared, so you must not modify
195them (increment, assign to them etc.) in any way. You may modify the 207them (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.: 208I<DATA> member, and you may re-assign the array itself, e.g.:
197 209
198 $ber = ber_decode $binbuf; 210 $ber = ber_decode $binbuf;
199 211
200 # the following is NOT legal: 212 # the following is NOT legal:
201 $ber->[BER_CLASS] = ASN_PRIVATE; # ERROR, CLASS/TAG/CONSTRUCTED are READ ONLY(!) 213 $ber->[BER_CLASS] = ASN_PRIVATE; # ERROR, CLASS/TAG/FLAGS are READ ONLY(!)
202 214
203 # but all of the following are fine: 215 # but all of the following are fine:
204 $ber->[BER_DATA] = "string"; 216 $ber->[BER_DATA] = "string";
205 $ber->[BER_DATA] = [ASN_UNIVERSAL, ASN_INTEGER32, 0, 123]; 217 $ber->[BER_DATA] = [ASN_UNIVERSAL, ASN_INTEGER, 0, 123];
206 @$ber = (ASN_APPLICATION, SNMP_TIMETICKS, 0, 1000); 218 @$ber = (ASN_APPLICATION, SNMP_TIMETICKS, 0, 1000);
207 219
208I<CLASS> is something like a namespace for I<TAG>s - there is the 220I<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 221C<ASN_UNIVERSAL> namespace which defines tags common to all ASN.1
210implementations, the C<ASN_APPLICATION> namespace which defines tags for 222implementations, the C<ASN_APPLICATION> namespace which defines tags for
211specific applications (for example, the SNMP C<Unsigned32> type is in this 223specific applications (for example, the SNMP C<Unsigned32> type is in this
212namespace), a special-purpose context namespace (C<ASN_CONTEXT>, used e.g. 224namespace), a special-purpose context namespace (C<ASN_CONTEXT>, used e.g.
213for C<CHOICE>) and a private namespace (C<ASN_PRIVATE>). 225for C<CHOICE>) and a private namespace (C<ASN_PRIVATE>).
214 226
215The meaning of the I<TAG> depends on the namespace, and defines a 227The meaning of the I<TAG> depends on the namespace, and defines a
216(partial) interpretation of the data value. For example, right now, SNMP 228(partial) interpretation of the data value. For example, SNMP defines
217application namespace knowledge ix hardcoded into this module, so it 229extra 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 230of these, you need to tell this module how to handle those via profiles.
219integers.
220 231
221The most common tags in the C<ASN_UNIVERSAL> namespace are 232The most common tags in the C<ASN_UNIVERSAL> namespace are
222C<ASN_INTEGER32>, C<ASN_BIT_STRING>, C<ASN_NULL>, C<ASN_OCTET_STRING>, 233C<ASN_INTEGER>, C<ASN_BIT_STRING>, C<ASN_NULL>, C<ASN_OCTET_STRING>,
223C<ASN_OBJECT_IDENTIFIER>, C<ASN_SEQUENCE>, C<ASN_SET> and 234C<ASN_OBJECT_IDENTIFIER>, C<ASN_SEQUENCE>, C<ASN_SET> and
224C<ASN_IA5_STRING>. 235C<ASN_IA5_STRING>.
225 236
226The most common tags in SNMP's C<ASN_APPLICATION> namespace 237The most common tags in SNMP's C<ASN_APPLICATION> namespace are
227are C<SNMP_IPADDRESS>, C<SNMP_COUNTER32>, C<SNMP_UNSIGNED32>, 238C<SNMP_COUNTER32>, C<SNMP_UNSIGNED32>, C<SNMP_TIMETICKS> and
228C<SNMP_TIMETICKS>, C<SNMP_OPAQUE> and C<SNMP_COUNTER64>. 239C<SNMP_COUNTER64>.
229 240
230The I<CONSTRUCTED> flag is really just a boolean - if it is false, the 241The 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 242get 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" 243no 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 244then the value is "constructed" which just means it contains a list of
234en-/decode as BER tuples themselves. 245subvalues which this module will en-/decode as BER tuples themselves.
235 246
236The I<DATA> value is either a reference to an array of further tuples (if 247The I<DATA> value is either a reference to an array of further tuples
237the value is I<CONSTRUCTED>), some decoded representation of the value, 248(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) 249this 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 250a binary string with the raw octets if this module doesn't know how to
240interpret the namespace/tag. 251interpret the namespace/tag.
241 252
242Thus, you can always decode a BER data structure and at worst you get a 253Thus, you can always decode a BER data structure and at worst you get a
243string in place of some nice decoded value. 254string in place of some nice decoded value.
244 255
246 257
247=head2 DECODING AND ENCODING 258=head2 DECODING AND ENCODING
248 259
249=over 260=over
250 261
251=item $tuple = ber_decoded $bindata 262=item $tuple = ber_decode $bindata[, $profile]
252 263
253Decodes binary BER data in C<$bindata> and returns the resulting BER 264Decodes binary BER data in C<$bindata> and returns the resulting BER
254tuple. Croaks on any decoding error, so the returned C<$tuple> is always 265tuple. Croaks on any decoding error, so the returned C<$tuple> is always
255valid. 266valid.
256 267
268How tags are interpreted is defined by the second argument, which must
269be a C<Convert::BER::XS::Profile> object. If it is missing, the default
270profile will be used (C<$Convert::BER::XS::DEFAULT_PROFILE>).
271
272In addition to rolling your own, this module provides a
273C<$Convert::BER::XS::SNMP_PROFILE> that knows about the additional SNMP
274types.
275
276Example: decode a BER blob using the default profile - SNMP values will be
277decided as raw strings.
278
279 $tuple = ber_decode $data;
280
281Example: 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
287Works like C<ber_decode>, except it doesn't croak when there is data after
288the BER data, but instead returns the decoded value and the number of
289bytes it decoded.
290
291This is useful when you have BER data at the start of a buffer and other
292data after, and you need to find the length.
293
294Also, since BER is self-delimited, this can be used to decode multiple BER
295values joined together.
296
257=item $bindata = ber_encode $tuple 297=item $bindata = ber_encode $tuple[, $profile]
258 298
259Encodes the BER tuple into a BER/DER data structure. 299Encodes the BER tuple into a BER/DER data structure. As with
300Cyber_decode>, an optional profile can be given.
301
302The encoded data should be both BER and DER ("shortest form") compliant
303unless the input says otherwise (e.g. it uses constructed strings).
260 304
261=back 305=back
262 306
263=head2 HELPER FUNCTIONS 307=head2 HELPER FUNCTIONS
264 308
265Working with a 4-tuple for every value can be annoying. Or, rather, I<is> 309Working 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 310annoying. To reduce this a bit, this module defines a number of helper
267functions, both to match BER tuples and to conmstruct BER tuples: 311functions, both to match BER tuples and to construct BER tuples:
268 312
269=head3 MATCH HELPERS 313=head3 MATCH HELPERS
270 314
271Thse functions accept a BER tuple as first argument and either paertially 315These 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 316or 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. 317a value, and one which only matches the type and returns the value.
274 318
275They do check whether valid tuples are passed in and croak otherwise. As 319They 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 320a ease-of-use exception, they usually also accept C<undef> instead of a
277tuple reference. in which case they silently fail to match. 321tuple reference, in which case they silently fail to match.
278 322
279=over 323=over
280 324
281=item $bool = ber_is $tuple, $class, $tag, $constructed, $data 325=item $bool = ber_is $tuple, $class, $tag, $flags, $data
282 326
283This takes a BER C<$tuple> and matches its elements agains the privded 327This takes a BER C<$tuple> and matches its elements against the provided
284values, all of which are optional - values that are either missing or 328values, all of which are optional - values that are either missing or
285C<undef> will be ignored, the others will be matched exactly (e.g. as if 329C<undef> will be ignored, the others will be matched exactly (e.g. as if
286you used C<==> or C<eq> (for C<$data>)). 330you used C<==> or C<eq> (for C<$data>)).
287 331
288Some examples: 332Some examples:
291 orf die "tuple is not an ASN SEQUENCE"; 335 orf die "tuple is not an ASN SEQUENCE";
292 336
293 ber_is $tuple, ASN_UNIVERSAL, ASN_NULL 337 ber_is $tuple, ASN_UNIVERSAL, ASN_NULL
294 or die "tuple is not an ASN NULL value"; 338 or die "tuple is not an ASN NULL value";
295 339
296 ber_is $tuple, ASN_UNIVERSAL, ASN_INTEGER32, 0, 50 340 ber_is $tuple, ASN_UNIVERSAL, ASN_INTEGER, 0, 50
297 or die "BER integer must be 50"; 341 or die "BER integer must be 50";
298 342
299=item $seq = ber_is_seq $tuple 343=item $seq = ber_is_seq $tuple
300 344
301Returns the sequence members (the array of subvalues) if the C<$tuple> is 345Returns the sequence members (the array of subvalues) if the C<$tuple> is
308 my $snmp = ber_is_seq $ber 352 my $snmp = ber_is_seq $ber
309 or die "SNMP packet invalid: does not start with SEQUENCE"; 353 or die "SNMP packet invalid: does not start with SEQUENCE";
310 354
311 # now we know $snmp is a sequence, so decode the SNMP version 355 # now we know $snmp is a sequence, so decode the SNMP version
312 356
313 my $version = ber_is_i32 $snmp->[0] 357 my $version = ber_is_int $snmp->[0]
314 or die "SNMP packet invalid: does not start with version number"; 358 or die "SNMP packet invalid: does not start with version number";
315 359
316=item $bool = ber_is_i32 $tuple, $i32 360=item $bool = ber_is_int $tuple, $int
317 361
318Returns a true value if the C<$tuple> represents an ASN INTEGER32 with 362Returns a true value if the C<$tuple> represents an ASN INTEGER with
319the value C<$i32>. 363the value C<$int>.
320 364
321=item $i32 = ber_is_i32 $tuple 365=item $int = ber_is_int $tuple
322 366
323Returns true (and extracts the integer value) if the C<$tuple> is an ASN 367Returns 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 368C<ASN_INTEGER>. For C<0>, this function returns a special value that is 0
325true. 369but true.
326 370
327=item $bool = ber_is_oid $tuple, $oid_string 371=item $bool = ber_is_oid $tuple, $oid_string
328 372
329Returns true if the C<$tuple> represents an ASN_OBJECT_IDENTIFIER 373Returns true if the C<$tuple> represents an ASN_OBJECT_IDENTIFIER
330that exactly matches C<$oid_string>. Example: 374that exactly matches C<$oid_string>. Example:
341 385
342=head3 CONSTRUCTION HELPERS 386=head3 CONSTRUCTION HELPERS
343 387
344=over 388=over
345 389
346=item $tuple = ber_i32 $value 390=item $tuple = ber_int $value
347 391
348Constructs a new C<ASN_INTEGER32> tuple. 392Constructs a new C<ASN_INTEGER> tuple.
349 393
350=back 394=back
351 395
352=head2 RELATIONSHIP TO L<Convert::BER> and L<Convert::ASN1> 396=head2 RELATIONSHIP TO L<Convert::BER> and L<Convert::ASN1>
353 397
363use common::sense; 407use common::sense;
364 408
365use XSLoader (); 409use XSLoader ();
366use Exporter qw(import); 410use Exporter qw(import);
367 411
412use Carp ();
413
368our $VERSION; 414our $VERSION;
369 415
370BEGIN { 416BEGIN {
371 $VERSION = 0.8; 417 $VERSION = 1.21;
372 XSLoader::load __PACKAGE__, $VERSION; 418 XSLoader::load __PACKAGE__, $VERSION;
373} 419}
374 420
375our %EXPORT_TAGS = ( 421our %EXPORT_TAGS = (
376 const_index => [qw( 422 const_index => [qw(
377 BER_CLASS BER_TAG BER_CONSTRUCTED BER_DATA 423 BER_CLASS BER_TAG BER_FLAGS BER_DATA
378 )], 424 )],
425 const_asn_class => [qw(
426 ASN_UNIVERSAL ASN_APPLICATION ASN_CONTEXT ASN_PRIVATE
427 )],
379 const_asn => [qw( 428 const_asn_tag => [qw(
380 ASN_BOOLEAN ASN_INTEGER32 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
381 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
382 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
383 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
384 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
385 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
386
387 ASN_UNIVERSAL ASN_APPLICATION ASN_CONTEXT ASN_PRIVATE
388 )], 435 )],
389 const_ber_type => [qw( 436 const_ber_type => [qw(
390 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
391 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
392 BER_TYPE_IPADDRESS BER_TYPE_CROAK 439 BER_TYPE_IPADDRESS BER_TYPE_CROAK
393 )], 440 )],
394 const_snmp => [qw( 441 const_snmp => [qw(
395 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
396 )], 444 )],
397 decode => [qw( 445 decode => [qw(
398 ber_decode 446 ber_decode ber_decode_prefix
399 ber_is ber_is_seq ber_is_i32 ber_is_oid 447 ber_is ber_is_seq ber_is_int ber_is_oid
448 ber_dump
400 )], 449 )],
401 encode => [qw( 450 encode => [qw(
402 ber_encode 451 ber_encode
403 ber_i32 452 ber_int
404 )], 453 )],
405); 454);
406 455
407our @EXPORT_OK = map @$_, values %EXPORT_TAGS; 456our @EXPORT_OK = map @$_, values %EXPORT_TAGS;
408 457
409$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)];
410$EXPORT_TAGS{const} = [map @{ $EXPORT_TAGS{$_} }, qw(const_index const_asn)]; 460$EXPORT_TAGS{const} = [map @{ $EXPORT_TAGS{$_} }, qw(const_index const_asn)];
411use Data::Dump; ddx \%EXPORT_TAGS; 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$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_TIMETICKS , BER_TYPE_INT);
473
474# decodes REAL values according to ECMA-63
475# this is pretty strict, except it doesn't catch -0.
476# I don't have access to ISO 6093 (or BS 6727, or ANSI X.3-42)), so this is all guesswork.
477sub _decode_real_decimal {
478 my ($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 $val
496}
497
498# this is a mess, but perl's support for floating point formatting is nearly nonexistant
499sub _encode_real_decimal {
500 my ($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
519To aid debugging, you can call the C<ber_dump> function to print a "nice"
520representation to STDOUT.
521
522=over
523
524=item ber_dump $tuple[, $profile[, $prefix]]
525
526In addition to specifying the BER C<$tuple> to dump, you can also specify
527a C<$profile> and a C<$prefix> string that is printed in front of each line.
528
529If C<$profile> is C<$Convert::BER::XS::SNMP_PROFILE>, then C<ber_dump>
530will try to improve its output for SNMP data.
531
532The output usually contains three columns, the "human readable" tag, the
533BER type used to decode it, and the data value.
534
535This function is somewhat slow and uses a number of heuristics and tricks,
536so it really is only suitable for debug prints.
537
538Example 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
557sub _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$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_COUNTER64 , BER_TYPE_INT);
569
570sub _ber_dump {
571 my ($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, $_[2];
617}
412 618
413=head1 PROFILES 619=head1 PROFILES
414 620
415While any BER data can be correctly encoded and decoded out of the box, it 621While any BER data can be correctly encoded and decoded out of the box, it
416can be inconvenient to have to manually decode some values into a "better" 622can be inconvenient to have to manually decode some values into a "better"
477 683
478Returns the BER type mapped to the given C<$class>/C<$tag> combination. 684Returns the BER type mapped to the given C<$class>/C<$tag> combination.
479 685
480=back 686=back
481 687
482=head2 BER TYPES 688=head2 BER Types
483 689
484This lists the predefined BER types - you can map any C<CLASS>/C<TAG> 690This lists the predefined BER types. BER types are formatters used
485combination to any C<BER_TYPE_*>. 691internally to format and encode BER values. You can assign any C<BER_TYPE>
692to any C<CLASS>/C<TAG> combination tgo change how that tag is decoded or
693encoded.
486 694
487=over 695=over
488 696
489=item C<BER_TYPE_BYTES> 697=item C<BER_TYPE_BYTES>
490 698
519dot, e.g. C<1.3.6.1.213>. 727dot, e.g. C<1.3.6.1.213>.
520 728
521=item C<BER_TYPE_RELOID> 729=item C<BER_TYPE_RELOID>
522 730
523Same as C<BER_TYPE_OID> but uses relative object identifier 731Same as C<BER_TYPE_OID> but uses relative object identifier
524encoding: ASN.1 has this hack of encoding the first two OID components 732encoding: 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 733into a single integer in a weird attempt to save an insignificant amount
526of space in an otherwise wasteful encoding, and relative OIDs are 734of space in an otherwise wasteful encoding, and relative OIDs are
527basically OIDs without this hack. The practical difference is that the 735basically OIDs without this hack. The practical difference is that the
528second component of an OID can only have the values 1..40, while relative 736second component of an OID can only have the values 1..40, while relative
529OIDs do not have this restriction. 737OIDs do not have this restriction.
556C<BER_TYPE_BYTES>. When you don't want that but instead prefer a hard 764C<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. 765error for some types, then C<BER_TYPE_CROAK> is for you.
558 766
559=back 767=back
560 768
561=cut 769=head2 Example Profile
562 770
563our $DEFAULT_PROFILE = new Convert::BER::XS::Profile; 771The following creates a profile suitable for SNMP - it's exactly identical
772to the C<$Convert::BER::XS::SNMP_PROFILE> profile.
773
564our $SNMP_PROFILE = new Convert::BER::XS::Profile; 774 our $SNMP_PROFILE = new Convert::BER::XS::Profile;
565 775
566# additional SNMP application types
567$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_IPADDRESS , BER_TYPE_IPADDRESS); 776 $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_IPADDRESS , BER_TYPE_IPADDRESS);
568$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_COUNTER32 , BER_TYPE_INT); 777 $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_COUNTER32 , BER_TYPE_INT);
569$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_UNSIGNED32, BER_TYPE_INT); 778 $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_UNSIGNED32, BER_TYPE_INT);
570$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_TIMETICKS , BER_TYPE_INT); 779 $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_TIMETICKS , BER_TYPE_INT);
571$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_OPAQUE , BER_TYPE_IPADDRESS); 780 $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_OPAQUE , BER_TYPE_BYTES);
572$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_COUNTER64 , BER_TYPE_INT); 781 $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_COUNTER64 , BER_TYPE_INT);
573
574$DEFAULT_PROFILE->_set_default;
575
5761;
577 782
578=head2 LIMITATIONS/NOTES 783=head2 LIMITATIONS/NOTES
579 784
580This module can only en-/decode 64 bit signed and unsigned integers, and 785This module can only en-/decode 64 bit signed and unsigned
581only when your perl supports those. 786integers/tags/lengths, and only when your perl supports those. So no UUID
787OIDs for now (unless you map the C<OBJECT IDENTIFIER> tag to something
788other than C<BER_TYPE_OID>).
582 789
583This module does not generally care about ranges, i.e. it will happily 790This 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 791de-/encode 64 bit integers into an C<SNMP_UNSIGNED32> value, or a negative
585number into an C<SNMP_COUNTER64>. 792number into an C<SNMP_COUNTER64>.
586 793
587OBJECT IDENTIFIEERs cannot have unlimited length, although the limit is 794OBJECT 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 795much larger than e.g. the one imposed by SNMP or other protocols, and is
589about 4kB. 796about 4kB.
590 797
591REAL values are not supported and will currently croak. 798Constructed strings are decoded just fine, but there should be a way to
799join them for convenience.
592 800
593This module has undergone little to no testing so far. 801REAL values will always be encoded in decimal form and ssometimes is
802forced into a perl "NV" type, potentially losing precision.
594 803
595=head2 ITHREADS SUPPORT 804=head2 ITHREADS SUPPORT
596 805
597This module is unlikely to work when the (officially discouraged) ithreads 806This module is unlikely to work in any other than the loading thread when
598are in use. 807the (officially discouraged) ithreads are in use.
599 808
600=head1 AUTHOR 809=head1 AUTHOR
601 810
602 Marc Lehmann <schmorp@schmorp.de> 811 Marc Lehmann <schmorp@schmorp.de>
603 http://software.schmorp.de/pkg/Convert-BER-XS 812 http://software.schmorp.de/pkg/Convert-BER-XS
604 813
605=cut 814=cut
606 815
8161;
817

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