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Revision 1.14 by root, Sat Apr 20 01:31:07 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 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, 0, 0, "\x0a\x00\x00\x01" ], # SNMP IpAddress, 10.0.0.1 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, ASN_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 [
35 [ ASN_UNIVERSAL, ASN_OBJECT_IDENTIFIER, 0, "1.3.6.1.4.1.9.9.215.1.1.8.1.2.1" ], 35 [ ASN_UNIVERSAL, ASN_OBJECT_IDENTIFIER, 0, "1.3.6.1.4.1.9.9.215.1.1.8.1.2.1" ],
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; 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
75If 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
78Currently, not much is documented, as this is an initial release to 79=head2 EXPORT TAGS AND CONSTANTS
79reserve CPAN namespace, stay tuned for a few days. 80
81By default this module doesn't export any symbols, but if you don't want
82to break your keyboard, editor or eyesight with extremely long names, I
83recommend importing the C<:all> tag. Still, you can selectively import
84things.
85
86=over
87
88=item C<:all>
89
90All of the below. Really. Recommended for at least first steps, or if you
91don't care about a few kilobytes of wasted memory (and namespace).
92
93=item C<:const>
94
95All of the strictly ASN.1-related constants defined by this module, the
96same as C<:const_asn :const_index>. Notably, this does not contain
97C<:const_ber_type> and C<:const_snmp>.
98
99A good set to get everything you need to decode and match BER data would be
100C<:decode :const>.
101
102=item C<:const_index>
103
104The BER tuple array index constants:
105
106 BER_CLASS BER_TAG BER_FLAGS BER_DATA
107
108=item C<:const_asn>
109
110ASN class values (these are C<0>, C<1>, C<2> and C<3>, respectively -
111exactly the two topmost bits from the identifier octet shifted 6 bits to
112the right):
113
114 ASN_UNIVERSAL ASN_APPLICATION ASN_CONTEXT ASN_PRIVATE
115
116ASN tag values (some of which are aliases, such as C<ASN_OID>). Their
117numerical 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
128The 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
136Constants only relevant to SNMP. These are the tag values used by SNMP in
137the C<ASN_APPLICATION> namespace and have the exact numerical value as in
138BER/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
145C<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
153C<ber_encode> and the construction helper functions:
154
155 ber_encode
156 ber_int
157
158=back
80 159
81=head2 ASN.1/BER/DER/... BASICS 160=head2 ASN.1/BER/DER/... BASICS
82 161
83ASN.1 is a strange language that can be sed to describe protocols and 162ASN.1 is a strange language that can be used to describe protocols and
84data structures. It supports various mappings to JSON, XML, but most 163data structures. It supports various mappings to JSON, XML, but most
85importantly, 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
86of 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.
87 166
88While 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,
89the BER encoding is actually somewhat self-describing: you might not know 168the BER encoding is actually somewhat self-describing: you might not know
90whether 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,
91but 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
92with just a binary blob for the actual value. 171with just a binary blob for the actual value.
93 172
94This 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,
95and also have a flag that says whther a value consists of subvalues (is 174and also have a flag that says whether a value consists of subvalues (is
96"constructed") or not (is "primitive"). 175"constructed") or not (is "primitive").
97 176
98Tags are simple integers, and ASN.1 defines a somewhat weird assortment of 177Tags are simple integers, and ASN.1 defines a somewhat weird assortment
99those - for example, you have 32 bit signed integers and 16(!) different 178of those - for example, you have one integers and 16(!) different
100string types, but there is no unsigned32 type for example. Different 179string types, but there is no Unsigned32 type for example. Different
101applications work around this in different ways, for example, SNMP defines 180applications work around this in different ways, for example, SNMP defines
102application-specific Gauge32, Counter32 and Unsigned32, which are mapped 181application-specific Gauge32, Counter32 and Unsigned32, which are mapped
103to two different tags: you can distinguish between Counter32 and the 182to two different tags: you can distinguish between Counter32 and the
104others, but not between Gause32 and Unsigned32, without the ASN.1 schema. 183others, but not between Gause32 and Unsigned32, without the ASN.1 schema.
105 184
108=head2 DECODED BER REPRESENTATION 187=head2 DECODED BER REPRESENTATION
109 188
110This 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
111array-reference): 190array-reference):
112 191
113 [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
114 200
115To avoid non-descriptive hardcoded array index numbers, this module 201To avoid non-descriptive hardcoded array index numbers, this module
116defines symbolic constants to access these members: C<BER_CLASS>, 202defines symbolic constants to access these members: C<BER_CLASS>,
117C<BER_TAG>, C<BER_CONSTRUCTED> and C<BER_DATA>. 203C<BER_TAG>, C<BER_FLAGS> and C<BER_DATA>.
118 204
119Also, the first three members are integers with a little caveat: for 205Also, the first three members are integers with a little caveat: for
120performance reasons, these are readonly and shared, so you must not modify 206performance reasons, these are readonly and shared, so you must not modify
121them (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
122I<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.:
123 209
124 $ber = ber_decode $binbuf; 210 $ber = ber_decode $binbuf;
125 211
126 # the following is NOT legal: 212 # the following is NOT legal:
127 $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(!)
128 214
129 # but all of the following are fine: 215 # but all of the following are fine:
130 $ber->[BER_DATA] = "string"; 216 $ber->[BER_DATA] = "string";
131 $ber->[BER_DATA] = [ASN_UNIVERSAL, ASN_INTEGER32, 0, 123]; 217 $ber->[BER_DATA] = [ASN_UNIVERSAL, ASN_INTEGER, 0, 123];
132 @$ber = (ASN_APPLICATION, SNMP_TIMETICKS, 0, 1000); 218 @$ber = (ASN_APPLICATION, SNMP_TIMETICKS, 0, 1000);
133 219
134I<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
135C<ASN_UNIVERSAL> namespace which defines tags common to all ASN.1 221C<ASN_UNIVERSAL> namespace which defines tags common to all ASN.1
136implementations, the C<ASN_APPLICATION> namespace which defines tags for 222implementations, the C<ASN_APPLICATION> namespace which defines tags for
137specific applications (for example, the SNMP C<Unsigned32> type is in this 223specific applications (for example, the SNMP C<Unsigned32> type is in this
138namespace), a special-purpose context namespace (C<ASN_CONTEXT>, used e.g. 224namespace), a special-purpose context namespace (C<ASN_CONTEXT>, used e.g.
139for C<CHOICE>) and a private namespace (C<ASN_PRIVATE>). 225for C<CHOICE>) and a private namespace (C<ASN_PRIVATE>).
140 226
141The 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
142(partial) interpretation of the data value. For example, right now, SNMP 228(partial) interpretation of the data value. For example, SNMP defines
143application namespace knowledge ix hardcoded into this module, so it 229extra tags in the C<ASN_APPLICATION> namespace, and to take full advantage
144knows 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.
145integers.
146 231
147The most common tags in the C<ASN_UNIVERSAL> namespace are 232The most common tags in the C<ASN_UNIVERSAL> namespace are
148C<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>,
149C<ASN_OBJECT_IDENTIFIER>, C<ASN_SEQUENCE>, C<ASN_SET> and 234C<ASN_OBJECT_IDENTIFIER>, C<ASN_SEQUENCE>, C<ASN_SET> and
150C<ASN_IA5_STRING>. 235C<ASN_IA5_STRING>.
151 236
152The most common tags in SNMP's C<ASN_APPLICATION> namespace 237The most common tags in SNMP's C<ASN_APPLICATION> namespace are
153are C<SNMP_IPADDRESS>, C<SNMP_COUNTER32>, C<SNMP_UNSIGNED32>, 238C<SNMP_COUNTER32>, C<SNMP_UNSIGNED32>, C<SNMP_TIMETICKS> and
154C<SNMP_TIMETICKS>, C<SNMP_OPAQUE> and C<SNMP_COUNTER64>. 239C<SNMP_COUNTER64>.
155 240
156The 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
157the value is "primitive" and contains no subvalues, kind of like a 242get extended) - if it is C<0>, the value is "primitive" and contains
158non-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>,
159which 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
160en-/decode as BER tuples themselves. 245subvalues which this module will en-/decode as BER tuples themselves.
161 246
162The 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
163the value is I<CONSTRUCTED>), some decoded representation of the value, 248(if the value is I<FLAGS>), some decoded representation of the value, if
164if 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
165or 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
166interpret the namespace/tag. 251interpret the namespace/tag.
167 252
168Thus, 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
169string in place of some nice decoded value. 254string in place of some nice decoded value.
170 255
172 257
173=head2 DECODING AND ENCODING 258=head2 DECODING AND ENCODING
174 259
175=over 260=over
176 261
177=item $tuple = ber_decoded $bindata 262=item $tuple = ber_decode $bindata[, $profile]
178 263
179Decodes binary BER data in C<$bindata> and returns the resulting BER 264Decodes binary BER data in C<$bindata> and returns the resulting BER
180tuple. Croaks on any decoding error, so the returned C<$tuple> is always 265tuple. Croaks on any decoding error, so the returned C<$tuple> is always
181valid. 266valid.
182 267
268How tags are interpreted is defined by the second argument, which must
269be a C<Convert::BER::XS::Profile> object. If it is missing, the default
270profile will be used (C<$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
183=item $bindata = ber_encode $tuple 297=item $bindata = ber_encode $tuple[, $profile]
184 298
185Encodes 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).
186 304
187=back 305=back
188 306
189=head2 HELPER FUNCTIONS 307=head2 HELPER FUNCTIONS
190 308
191Working 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>
192annoying. 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
193functions, both to match BER tuples and to conmstruct BER tuples: 311functions, both to match BER tuples and to construct BER tuples:
194 312
195=head3 MATCH HELPERS 313=head3 MATCH HELPERS
196 314
197Thse functions accept a BER tuple as first argument and either paertially 315These functions accept a BER tuple as first argument and either partially
198or 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
199a 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.
200 318
201They 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
202a 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
203tuple reference. in which case they silently fail to match. 321tuple reference, in which case they silently fail to match.
204 322
205=over 323=over
206 324
207=item $bool = ber_is $tuple, $class, $tag, $constructed, $data 325=item $bool = ber_is $tuple, $class, $tag, $flags, $data
208 326
209This takes a BER C<$tuple> and matches its elements agains the privded 327This takes a BER C<$tuple> and matches its elements against the provided
210values, all of which are optional - values that are either missing or 328values, all of which are optional - values that are either missing or
211C<undef> will be ignored, the others will be matched exactly (e.g. as if 329C<undef> will be ignored, the others will be matched exactly (e.g. as if
212you used C<==> or C<eq> (for C<$data>)). 330you used C<==> or C<eq> (for C<$data>)).
213 331
214Some examples: 332Some examples:
217 orf die "tuple is not an ASN SEQUENCE"; 335 orf die "tuple is not an ASN SEQUENCE";
218 336
219 ber_is $tuple, ASN_UNIVERSAL, ASN_NULL 337 ber_is $tuple, ASN_UNIVERSAL, ASN_NULL
220 or die "tuple is not an ASN NULL value"; 338 or die "tuple is not an ASN NULL value";
221 339
222 ber_is $tuple, ASN_UNIVERSAL, ASN_INTEGER32, 0, 50 340 ber_is $tuple, ASN_UNIVERSAL, ASN_INTEGER, 0, 50
223 or die "BER integer must be 50"; 341 or die "BER integer must be 50";
224 342
225=item $seq = ber_is_seq $tuple 343=item $seq = ber_is_seq $tuple
226 344
227Returns the sequence members (the array of subvalues) if the C<$tuple> is 345Returns the sequence members (the array of subvalues) if the C<$tuple> is
234 my $snmp = ber_is_seq $ber 352 my $snmp = ber_is_seq $ber
235 or die "SNMP packet invalid: does not start with SEQUENCE"; 353 or die "SNMP packet invalid: does not start with SEQUENCE";
236 354
237 # 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
238 356
239 my $version = ber_is_i32 $snmp->[0] 357 my $version = ber_is_int $snmp->[0]
240 or die "SNMP packet invalid: does not start with version number"; 358 or die "SNMP packet invalid: does not start with version number";
241 359
242=item $bool = ber_is_i32 $tuple, $i32 360=item $bool = ber_is_int $tuple, $int
243 361
244Returns a true value if the C<$tuple> represents an ASN INTEGER32 with 362Returns a true value if the C<$tuple> represents an ASN INTEGER with
245the value C<$i32>. 363the value C<$int>.
246 364
247=item $i32 = ber_is_i32 $tuple 365=item $int = ber_is_int $tuple
248 366
249Returns true (and extracts the integer value) if the C<$tuple> is an ASN 367Returns true (and extracts the integer value) if the C<$tuple> is an
250INTEGER32. 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
251true. 369but true.
252 370
253=item $bool = ber_is_oid $tuple, $oid_string 371=item $bool = ber_is_oid $tuple, $oid_string
254 372
255Returns true if the C<$tuple> represents an ASN_OBJECT_IDENTIFIER 373Returns true if the C<$tuple> represents an ASN_OBJECT_IDENTIFIER
256that exactly matches C<$oid_string>. Example: 374that exactly matches C<$oid_string>. Example:
267 385
268=head3 CONSTRUCTION HELPERS 386=head3 CONSTRUCTION HELPERS
269 387
270=over 388=over
271 389
272=item $tuple = ber_i32 $value 390=item $tuple = ber_int $value
273 391
274Constructs a new C<ASN_INTEGER32> tuple. 392Constructs a new C<ASN_INTEGER> tuple.
275 393
276=back 394=back
277 395
278=head2 RELATIONSHIP TO L<Convert::BER> and L<Convert::ASN1> 396=head2 RELATIONSHIP TO L<Convert::BER> and L<Convert::ASN1>
279 397
289use common::sense; 407use common::sense;
290 408
291use XSLoader (); 409use XSLoader ();
292use Exporter qw(import); 410use Exporter qw(import);
293 411
412use Carp ();
413
294our $VERSION; 414our $VERSION;
295 415
296BEGIN { 416BEGIN {
297 $VERSION = 0.7; 417 $VERSION = 1.21;
298 XSLoader::load __PACKAGE__, $VERSION; 418 XSLoader::load __PACKAGE__, $VERSION;
299} 419}
300 420
301our %EXPORT_TAGS = ( 421our %EXPORT_TAGS = (
302 const => [qw( 422 const_index => [qw(
303 BER_CLASS BER_TAG BER_CONSTRUCTED BER_DATA 423 BER_CLASS BER_TAG BER_FLAGS BER_DATA
304 424 )],
425 const_asn_class => [qw(
426 ASN_UNIVERSAL ASN_APPLICATION ASN_CONTEXT ASN_PRIVATE
427 )],
428 const_asn_tag => [qw(
305 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
306 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
307 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
308 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
309 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
310 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
311 435 )],
312 ASN_UNIVERSAL ASN_APPLICATION ASN_CONTEXT ASN_PRIVATE 436 const_ber_type => [qw(
313
314 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
315 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
316 BER_TYPE_IPADDRESS BER_TYPE_CROAK 439 BER_TYPE_IPADDRESS BER_TYPE_CROAK
317 )], 440 )],
318 const_snmp => [qw( 441 const_snmp => [qw(
319 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
444 )],
445 decode => [qw(
446 ber_decode ber_decode_prefix
447 ber_is ber_is_seq ber_is_int ber_is_oid
448 ber_dump
320 )], 449 )],
321 encode => [qw( 450 encode => [qw(
322 ber_decode
323 ber_is ber_is_seq ber_is_i32 ber_is_oid
324 )],
325 decode => [qw(
326 ber_encode 451 ber_encode
327 ber_i32 452 ber_int
328 )], 453 )],
329); 454);
330 455
331our @EXPORT_OK = map @$_, values %EXPORT_TAGS; 456our @EXPORT_OK = map @$_, values %EXPORT_TAGS;
332 457
333$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)];
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, $_[2];
617}
334 618
335=head1 PROFILES 619=head1 PROFILES
336 620
337While any BER data can be correctly encoded and decoded out of the box, it 621While any BER data can be correctly encoded and decoded out of the box, it
338can be inconvenient to have to manually decode some values into a "better" 622can be inconvenient to have to manually decode some values into a "better"
347 631
348The default profile supports the standard ASN.1 types, but no 632The default profile supports the standard ASN.1 types, but no
349application-specific ones. This means that class/tag combinations not in 633application-specific ones. This means that class/tag combinations not in
350the base set of ASN.1 are decoded into their raw octet strings. 634the base set of ASN.1 are decoded into their raw octet strings.
351 635
352C<Convert::BER::XS> defines two profile variables you cna use out of the box: 636C<Convert::BER::XS> defines two profile variables you can use out of the box:
353 637
354=over 638=over
355 639
356=item C<$Convert::BER::XS::DEFAULT_PROFILE> 640=item C<$Convert::BER::XS::DEFAULT_PROFILE>
357 641
358This is the default profile, i.e. the profile that is used when no 642This is the default profile, i.e. the profile that is used when no
359profile is specified for de-/encoding. 643profile is specified for de-/encoding.
360 644
361You cna modify it, but remember that this modifies the defaults for all 645You can modify it, but remember that this modifies the defaults for all
362callers that rely on the defauit profile. 646callers that rely on the default profile.
363 647
364=item C<$Convert::BER::XS::SNMP_PROFILE> 648=item C<$Convert::BER::XS::SNMP_PROFILE>
365 649
366A profile with mappings for SNMP-specific application tags added. This is 650A profile with mappings for SNMP-specific application tags added. This is
367useful when de-/encoding SNMP data. 651useful when de-/encoding SNMP data.
368 652
369Example: 653Example:
654
370 $ber = ber_decode $data, $Convert::BER::XS::SNMP_PROFILE; 655 $ber = ber_decode $data, $Convert::BER::XS::SNMP_PROFILE;
371 656
372=back 657=back
373 658
374=head2 The Convert::BER::XS::Profile class 659=head2 The Convert::BER::XS::Profile class
387 672
388Note that currently, the mapping is stored in a flat array, so large 673Note that currently, the mapping is stored in a flat array, so large
389values of C<$tag> will consume large amounts of memory. 674values of C<$tag> will consume large amounts of memory.
390 675
391Example: 676Example:
677
392 $profile = new Convert::BER::XS::Profile; 678 $profile = new Convert::BER::XS::Profile;
393 $profile->set (ASN_APPLICATION, SNMP_COUNTER32, BER_TYPE_INT); 679 $profile->set (ASN_APPLICATION, SNMP_COUNTER32, BER_TYPE_INT);
394 $ber = ber_decode $data, $profile; 680 $ber = ber_decode $data, $profile;
395 681
396=item $type = $profile->get ($class, $tag) 682=item $type = $profile->get ($class, $tag)
397 683
398Returns the BER type mapped to the given C<$class>/C<$tag> combination. 684Returns the BER type mapped to the given C<$class>/C<$tag> combination.
399 685
400=back 686=back
401 687
402=head2 BER TYPES 688=head2 BER Types
403 689
404This lists the predefined BER types - you can map any C<CLASS>/C<TAG> 690This lists the predefined BER types. BER types are formatters used
405combination 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.
406 694
407=over 695=over
408 696
409=item C<BER_TYPE_BYTES> 697=item C<BER_TYPE_BYTES>
410 698
438Encodes and decodes an OBJECT IDENTIFIER into dotted form without leading 726Encodes and decodes an OBJECT IDENTIFIER into dotted form without leading
439dot, e.g. C<1.3.6.1.213>. 727dot, e.g. C<1.3.6.1.213>.
440 728
441=item C<BER_TYPE_RELOID> 729=item C<BER_TYPE_RELOID>
442 730
443Same as C<BER_TYPE_OID> but uses relative OID encoding: ASN.1 has this 731Same as C<BER_TYPE_OID> but uses relative object identifier
444hack of encoding the first two OID components into a single integer in a 732encoding: ASN.1 uses some hack encoding of the first two OID components
445weird attempt to save an insignificant amount of space in an otherwise 733into a single integer in a weird attempt to save an insignificant amount
446wasteful encoding, and relative OIDs are basically OIDs without this 734of space in an otherwise wasteful encoding, and relative OIDs are
447hack. The practical difference is that the second component of an OID 735basically OIDs without this hack. The practical difference is that the
448can only have the values 1..40, while relative OIDs do not have this 736second component of an OID can only have the values 1..40, while relative
449restriction. 737OIDs do not have this restriction.
450 738
451=item C<BER_TYPE_NULL> 739=item C<BER_TYPE_NULL>
452 740
453Decodes an C<ASN_NULL> value into C<undef>, and always encodes a 741Decodes an C<ASN_NULL> value into C<undef>, and always encodes a
454C<ASN_NULL> type, regardless of the perl value. 742C<ASN_NULL> type, regardless of the perl value.
462 750
463Decodes/encodes a BER real value. NOT IMPLEMENTED. 751Decodes/encodes a BER real value. NOT IMPLEMENTED.
464 752
465=item C<BER_TYPE_IPADDRESS> 753=item C<BER_TYPE_IPADDRESS>
466 754
467Decodes/encodes a four byte string into an IOv4 dotted-quad address string 755Decodes/encodes a four byte string into an IPv4 dotted-quad address string
468in perl. Given ther obsolete nature of this type, this is a low-effort 756in Perl. Given the obsolete nature of this type, this is a low-effort
469implementation that simply uses C<sprintf> and C<sscanf>-style conversion, 757implementation that simply uses C<sprintf> and C<sscanf>-style conversion,
470so it won't handle all string forms supported by C<inet_aton>. 758so it won't handle all string forms supported by C<inet_aton> for example.
471 759
472=item C<BER_TYPE_CROAK> 760=item C<BER_TYPE_CROAK>
473 761
474Always croaks when encountered during encoding or decoding - the 762Always croaks when encountered during encoding or decoding - the
475default behaviour when encountering an unknown type is to treat it as 763default behaviour when encountering an unknown type is to treat it as
476C<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
477error for some types, then CyBER_TYPE_CROAK> is for you. 765error for some types, then C<BER_TYPE_CROAK> is for you.
478 766
479=back 767=back
480 768
481=cut 769=head2 Example Profile
482 770
483our $DEFAULT_PROFILE = new Convert::BER::XS::Profile; 771The following creates a profile suitable for SNMP - it's exactly identical
772to the C<$Convert::BER::XS::SNMP_PROFILE> profile.
773
484our $SNMP_PROFILE = new Convert::BER::XS::Profile; 774 our $SNMP_PROFILE = new Convert::BER::XS::Profile;
485 775
486$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_IPADDRESS , BER_TYPE_IPADDRESS); 776 $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_IPADDRESS , BER_TYPE_IPADDRESS);
487$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_COUNTER32 , BER_TYPE_INT); 777 $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_COUNTER32 , BER_TYPE_INT);
488$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_UNSIGNED32, BER_TYPE_INT); 778 $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_UNSIGNED32, BER_TYPE_INT);
489$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_TIMETICKS , BER_TYPE_INT); 779 $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_TIMETICKS , BER_TYPE_INT);
490$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_OPAQUE , BER_TYPE_IPADDRESS); 780 $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_OPAQUE , BER_TYPE_BYTES);
491$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_COUNTER64 , BER_TYPE_INT); 781 $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_COUNTER64 , BER_TYPE_INT);
492 782
493$DEFAULT_PROFILE->_set_default;
494
4951;
496
497=head2 LIMITATIONS 783=head2 LIMITATIONS/NOTES
498 784
499This module can only en-/decode 64 bit signed and unsigned integers, and 785This module can only en-/decode 64 bit signed and unsigned
500only 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>).
501 789
790This module does not generally care about ranges, i.e. it will happily
791de-/encode 64 bit integers into an C<SNMP_UNSIGNED32> value, or a negative
792number into an C<SNMP_COUNTER64>.
793
502OBJECT IDENTIFIEERS cannot have unlimited length, although the limit is 794OBJECT IDENTIFIEERs cannot have unlimited length, although the limit is
503much larger than e.g. the one imposed by SNMP or other protocols. 795much larger than e.g. the one imposed by SNMP or other protocols, and is
796about 4kB.
504 797
505REAL values are not supported and will croak. 798Constructed strings are decoded just fine, but there should be a way to
799join them for convenience.
506 800
507This 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.
803
804=head2 ITHREADS SUPPORT
805
806This module is unlikely to work in any other than the loading thread when
807the (officially discouraged) ithreads are in use.
508 808
509=head1 AUTHOR 809=head1 AUTHOR
510 810
511 Marc Lehmann <schmorp@schmorp.de> 811 Marc Lehmann <schmorp@schmorp.de>
512 http://software.schmorp.de/pkg/Convert-BER-XS 812 http://software.schmorp.de/pkg/Convert-BER-XS
513 813
514=cut 814=cut
515 815
8161;
817

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