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Revision 1.14 by root, Sat Apr 20 01:31:07 2019 UTC vs.
Revision 1.46 by root, Sun Apr 21 03:02:22 2019 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. 74WARNING: Before release 1.0, the API is not considered stable in any way.
72 75
73This module implements a I<very> low level BER/DER en-/decoder. 76This module implements a I<very> low level BER/DER en-/decoder.
74 77
75If is tuned for low memory and high speed, while still maintaining some 78It is tuned for low memory and high speed, while still maintaining some
76level of user-friendlyness. 79level of user-friendlyness.
77 80
78Currently, not much is documented, as this is an initial release to 81=head2 EXPORT TAGS AND CONSTANTS
79reserve CPAN namespace, stay tuned for a few days. 82
83By default this module doesn't export any symbols, but if you don't want
84to break your keyboard, editor or eyesight with extremely long names, I
85recommend importing the C<:all> tag. Still, you can selectively import
86things.
87
88=over
89
90=item C<:all>
91
92All of the below. Really. Recommended for at least first steps, or if you
93don't care about a few kilobytes of wasted memory (and namespace).
94
95=item C<:const>
96
97All of the strictly ASN.1-related constants defined by this module, the
98same as C<:const_asn :const_index>. Notably, this does not contain
99C<:const_ber_type> and C<:const_snmp>.
100
101A good set to get everything you need to decode and match BER data would be
102C<:decode :const>.
103
104=item C<:const_index>
105
106The BER tuple array index constants:
107
108 BER_CLASS BER_TAG BER_FLAGS BER_DATA
109
110=item C<:const_asn>
111
112ASN class values (these are C<0>, C<1>, C<2> and C<3>, respectively -
113exactly thw two topmost bits from the identifier octet shifted 6 bits to
114the right):
115
116 ASN_UNIVERSAL ASN_APPLICATION ASN_CONTEXT ASN_PRIVATE
117
118ASN tag values (some of which are aliases, such as C<ASN_OID>). Their
119numerical value corresponds exactly to the numbers used in BER/X.690.
120
121 ASN_BOOLEAN ASN_INTEGER ASN_BIT_STRING ASN_OCTET_STRING ASN_NULL ASN_OID
122 ASN_OBJECT_IDENTIFIER ASN_OBJECT_DESCRIPTOR ASN_EXTERNAL ASN_REAL ASN_SEQUENCE ASN_ENUMERATED
123 ASN_EMBEDDED_PDV ASN_UTF8_STRING ASN_RELATIVE_OID ASN_SET ASN_NUMERIC_STRING
124 ASN_PRINTABLE_STRING ASN_TELETEX_STRING ASN_T61_STRING ASN_VIDEOTEX_STRING ASN_IA5_STRING
125 ASN_ASCII_STRING ASN_UTC_TIME ASN_GENERALIZED_TIME ASN_GRAPHIC_STRING ASN_VISIBLE_STRING
126 ASN_ISO646_STRING ASN_GENERAL_STRING ASN_UNIVERSAL_STRING ASN_CHARACTER_STRING ASN_BMP_STRING
127
128=item C<:const_ber_type>
129
130The BER type constants, explained in the PROFILES section.
131
132 BER_TYPE_BYTES BER_TYPE_UTF8 BER_TYPE_UCS2 BER_TYPE_UCS4 BER_TYPE_INT
133 BER_TYPE_OID BER_TYPE_RELOID BER_TYPE_NULL BER_TYPE_BOOL BER_TYPE_REAL
134 BER_TYPE_IPADDRESS BER_TYPE_CROAK
135
136=item C<:const_snmp>
137
138Constants only relevant to SNMP. These are the tag values used by SNMP in
139the C<ASN_APPLICATION> namespace and have the exact numerical value as in
140BER/RFC 2578.
141
142 SNMP_IPADDRESS SNMP_COUNTER32 SNMP_UNSIGNED32 SNMP_GAUGE32
143 SNMP_TIMETICKS SNMP_OPAQUE SNMP_COUNTER64
144
145=item C<:decode>
146
147C<ber_decode> and the match helper functions:
148
149 ber_decode ber-decode_prefix
150 ber_is ber_is_seq ber_is_int ber_is_oid
151 ber_dump
152
153=item C<:encode>
154
155C<ber_encode> and the construction helper functions:
156
157 ber_encode
158 ber_int
159
160=back
80 161
81=head2 ASN.1/BER/DER/... BASICS 162=head2 ASN.1/BER/DER/... BASICS
82 163
83ASN.1 is a strange language that can be sed to describe protocols and 164ASN.1 is a strange language that can be used to describe protocols and
84data structures. It supports various mappings to JSON, XML, but most 165data structures. It supports various mappings to JSON, XML, but most
85importantly, to a various binary encodings such as BER, that is the topic 166importantly, to a various binary encodings such as BER, that is the topic
86of this module, and is used in SNMP or LDAP for example. 167of this module, and is used in SNMP, LDAP or X.509 for example.
87 168
88While ASN.1 defines a schema that is useful to interpret encoded data, 169While ASN.1 defines a schema that is useful to interpret encoded data,
89the BER encoding is actually somewhat self-describing: you might not know 170the 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, 171whether 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 172but you can nevertheless decode the overall structure, even if you end up
92with just a binary blob for the actual value. 173with just a binary blob for the actual value.
93 174
94This works because BER values are tagged with a type and a namespace, 175This 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 176and also have a flag that says whether a value consists of subvalues (is
96"constructed") or not (is "primitive"). 177"constructed") or not (is "primitive").
97 178
98Tags are simple integers, and ASN.1 defines a somewhat weird assortment of 179Tags are simple integers, and ASN.1 defines a somewhat weird assortment
99those - for example, you have 32 bit signed integers and 16(!) different 180of those - for example, you have one integers and 16(!) different
100string types, but there is no unsigned32 type for example. Different 181string types, but there is no Unsigned32 type for example. Different
101applications work around this in different ways, for example, SNMP defines 182applications work around this in different ways, for example, SNMP defines
102application-specific Gauge32, Counter32 and Unsigned32, which are mapped 183application-specific Gauge32, Counter32 and Unsigned32, which are mapped
103to two different tags: you can distinguish between Counter32 and the 184to two different tags: you can distinguish between Counter32 and the
104others, but not between Gause32 and Unsigned32, without the ASN.1 schema. 185others, but not between Gause32 and Unsigned32, without the ASN.1 schema.
105 186
108=head2 DECODED BER REPRESENTATION 189=head2 DECODED BER REPRESENTATION
109 190
110This module represents every BER value as a 4-element tuple (actually an 191This module represents every BER value as a 4-element tuple (actually an
111array-reference): 192array-reference):
112 193
113 [CLASS, TAG, CONSTRUCTED, DATA] 194 [CLASS, TAG, FLAGS, DATA]
195
196For example:
197
198 [ASN_UNIVERSAL, ASN_INTEGER, 0, 177] # the integer 177
199 [ASN_UNIVERSAL, ASN_OCTET_STRING, 0, "john"] # the string "john"
200 [ASN_UNIVERSAL, ASN_OID, 0, "1.3.6.133"] # some OID
201 [ASN_UNIVERSAL, ASN_SEQUENCE, 1, [ [ASN_UNIVERSAL... # a sequence
114 202
115To avoid non-descriptive hardcoded array index numbers, this module 203To avoid non-descriptive hardcoded array index numbers, this module
116defines symbolic constants to access these members: C<BER_CLASS>, 204defines symbolic constants to access these members: C<BER_CLASS>,
117C<BER_TAG>, C<BER_CONSTRUCTED> and C<BER_DATA>. 205C<BER_TAG>, C<BER_FLAGS> and C<BER_DATA>.
118 206
119Also, the first three members are integers with a little caveat: for 207Also, the first three members are integers with a little caveat: for
120performance reasons, these are readonly and shared, so you must not modify 208performance reasons, these are readonly and shared, so you must not modify
121them (increment, assign to them etc.) in any way. You may modify the 209them (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.: 210I<DATA> member, and you may re-assign the array itself, e.g.:
123 211
124 $ber = ber_decode $binbuf; 212 $ber = ber_decode $binbuf;
125 213
126 # the following is NOT legal: 214 # the following is NOT legal:
127 $ber->[BER_CLASS] = ASN_PRIVATE; # ERROR, CLASS/TAG/CONSTRUCTED are READ ONLY(!) 215 $ber->[BER_CLASS] = ASN_PRIVATE; # ERROR, CLASS/TAG/FLAGS are READ ONLY(!)
128 216
129 # but all of the following are fine: 217 # but all of the following are fine:
130 $ber->[BER_DATA] = "string"; 218 $ber->[BER_DATA] = "string";
131 $ber->[BER_DATA] = [ASN_UNIVERSAL, ASN_INTEGER32, 0, 123]; 219 $ber->[BER_DATA] = [ASN_UNIVERSAL, ASN_INTEGER, 0, 123];
132 @$ber = (ASN_APPLICATION, SNMP_TIMETICKS, 0, 1000); 220 @$ber = (ASN_APPLICATION, SNMP_TIMETICKS, 0, 1000);
133 221
134I<CLASS> is something like a namespace for I<TAG>s - there is the 222I<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 223C<ASN_UNIVERSAL> namespace which defines tags common to all ASN.1
136implementations, the C<ASN_APPLICATION> namespace which defines tags for 224implementations, the C<ASN_APPLICATION> namespace which defines tags for
137specific applications (for example, the SNMP C<Unsigned32> type is in this 225specific applications (for example, the SNMP C<Unsigned32> type is in this
138namespace), a special-purpose context namespace (C<ASN_CONTEXT>, used e.g. 226namespace), a special-purpose context namespace (C<ASN_CONTEXT>, used e.g.
139for C<CHOICE>) and a private namespace (C<ASN_PRIVATE>). 227for C<CHOICE>) and a private namespace (C<ASN_PRIVATE>).
140 228
141The meaning of the I<TAG> depends on the namespace, and defines a 229The meaning of the I<TAG> depends on the namespace, and defines a
142(partial) interpretation of the data value. For example, right now, SNMP 230(partial) interpretation of the data value. For example, SNMP defines
143application namespace knowledge ix hardcoded into this module, so it 231extra 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 232of these, you need to tell this module how to handle those via profiles.
145integers.
146 233
147The most common tags in the C<ASN_UNIVERSAL> namespace are 234The most common tags in the C<ASN_UNIVERSAL> namespace are
148C<ASN_INTEGER32>, C<ASN_BIT_STRING>, C<ASN_NULL>, C<ASN_OCTET_STRING>, 235C<ASN_INTEGER>, C<ASN_BIT_STRING>, C<ASN_NULL>, C<ASN_OCTET_STRING>,
149C<ASN_OBJECT_IDENTIFIER>, C<ASN_SEQUENCE>, C<ASN_SET> and 236C<ASN_OBJECT_IDENTIFIER>, C<ASN_SEQUENCE>, C<ASN_SET> and
150C<ASN_IA5_STRING>. 237C<ASN_IA5_STRING>.
151 238
152The most common tags in SNMP's C<ASN_APPLICATION> namespace 239The most common tags in SNMP's C<ASN_APPLICATION> namespace are
153are C<SNMP_IPADDRESS>, C<SNMP_COUNTER32>, C<SNMP_UNSIGNED32>, 240C<SNMP_COUNTER32>, C<SNMP_UNSIGNED32>, C<SNMP_TIMETICKS> and
154C<SNMP_TIMETICKS>, C<SNMP_OPAQUE> and C<SNMP_COUNTER64>. 241C<SNMP_COUNTER64>.
155 242
156The I<CONSTRUCTED> flag is really just a boolean - if it is false, the 243The 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 244get 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" 245no 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 246then the value is "constructed" which just means it contains a list of
160en-/decode as BER tuples themselves. 247subvalues which this module will en-/decode as BER tuples themselves.
161 248
162The I<DATA> value is either a reference to an array of further tuples (if 249The I<DATA> value is either a reference to an array of further tuples
163the value is I<CONSTRUCTED>), some decoded representation of the value, 250(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) 251this 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 252a binary string with the raw octets if this module doesn't know how to
166interpret the namespace/tag. 253interpret the namespace/tag.
167 254
168Thus, you can always decode a BER data structure and at worst you get a 255Thus, you can always decode a BER data structure and at worst you get a
169string in place of some nice decoded value. 256string in place of some nice decoded value.
170 257
172 259
173=head2 DECODING AND ENCODING 260=head2 DECODING AND ENCODING
174 261
175=over 262=over
176 263
177=item $tuple = ber_decoded $bindata 264=item $tuple = ber_decode $bindata[, $profile]
178 265
179Decodes binary BER data in C<$bindata> and returns the resulting BER 266Decodes binary BER data in C<$bindata> and returns the resulting BER
180tuple. Croaks on any decoding error, so the returned C<$tuple> is always 267tuple. Croaks on any decoding error, so the returned C<$tuple> is always
181valid. 268valid.
182 269
270How tags are interpreted is defined by the second argument, which must
271be a C<Convert::BER::XS::Profile> object. If it is missing, the default
272profile will be used (C<$Convert::BER::XS::DEFAULT_PROFILE>).
273
274In addition to rolling your own, this module provides a
275C<$Convert::BER::XS::SNMP_PROFILE> that knows about the additional SNMP
276types.
277
278Example: decode a BER blob using the default profile - SNMP values will be
279decided as raw strings.
280
281 $tuple = ber_decode $data;
282
283Example: as above, but use the provided SNMP profile.
284
285 $tuple = ber_encode $data, $Convert::BER::XS::SNMP_PROFILE;
286
287=item ($tuple, $bytes) = ber_decode_prefix $bindata[, $profile]
288
289Works like C<ber_decode>, except it doesn't croak when there is data after
290the BER data, but instead returns the decoded value and the number of
291bytes it decoded.
292
293This is useful when you have BER data at the start of a buffer and other
294data after, and you need to find the length.
295
296Also, since BER is self-delimited, this can be used to decode multiple BER
297values joined together.
298
183=item $bindata = ber_encode $tuple 299=item $bindata = ber_encode $tuple[, $profile]
184 300
185Encodes the BER tuple into a BER/DER data structure. 301Encodes the BER tuple into a BER/DER data structure. AS with
302Cyber_decode>, an optional profile can be given.
303
304The encoded data should be both BER and DER ("shortest form") compliant
305unless the input says otherwise (e.g. it uses constructed strings).
186 306
187=back 307=back
188 308
189=head2 HELPER FUNCTIONS 309=head2 HELPER FUNCTIONS
190 310
191Working with a 4-tuple for every value can be annoying. Or, rather, I<is> 311Working 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 312annoying. To reduce this a bit, this module defines a number of helper
193functions, both to match BER tuples and to conmstruct BER tuples: 313functions, both to match BER tuples and to construct BER tuples:
194 314
195=head3 MATCH HELPERS 315=head3 MATCH HELPERS
196 316
197Thse functions accept a BER tuple as first argument and either paertially 317These 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 318or 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. 319a value, and one which only matches the type and returns the value.
200 320
201They do check whether valid tuples are passed in and croak otherwise. As 321They 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 322a ease-of-use exception, they usually also accept C<undef> instead of a
203tuple reference. in which case they silently fail to match. 323tuple reference, in which case they silently fail to match.
204 324
205=over 325=over
206 326
207=item $bool = ber_is $tuple, $class, $tag, $constructed, $data 327=item $bool = ber_is $tuple, $class, $tag, $flags, $data
208 328
209This takes a BER C<$tuple> and matches its elements agains the privded 329This takes a BER C<$tuple> and matches its elements against the provided
210values, all of which are optional - values that are either missing or 330values, all of which are optional - values that are either missing or
211C<undef> will be ignored, the others will be matched exactly (e.g. as if 331C<undef> will be ignored, the others will be matched exactly (e.g. as if
212you used C<==> or C<eq> (for C<$data>)). 332you used C<==> or C<eq> (for C<$data>)).
213 333
214Some examples: 334Some examples:
217 orf die "tuple is not an ASN SEQUENCE"; 337 orf die "tuple is not an ASN SEQUENCE";
218 338
219 ber_is $tuple, ASN_UNIVERSAL, ASN_NULL 339 ber_is $tuple, ASN_UNIVERSAL, ASN_NULL
220 or die "tuple is not an ASN NULL value"; 340 or die "tuple is not an ASN NULL value";
221 341
222 ber_is $tuple, ASN_UNIVERSAL, ASN_INTEGER32, 0, 50 342 ber_is $tuple, ASN_UNIVERSAL, ASN_INTEGER, 0, 50
223 or die "BER integer must be 50"; 343 or die "BER integer must be 50";
224 344
225=item $seq = ber_is_seq $tuple 345=item $seq = ber_is_seq $tuple
226 346
227Returns the sequence members (the array of subvalues) if the C<$tuple> is 347Returns the sequence members (the array of subvalues) if the C<$tuple> is
234 my $snmp = ber_is_seq $ber 354 my $snmp = ber_is_seq $ber
235 or die "SNMP packet invalid: does not start with SEQUENCE"; 355 or die "SNMP packet invalid: does not start with SEQUENCE";
236 356
237 # now we know $snmp is a sequence, so decode the SNMP version 357 # now we know $snmp is a sequence, so decode the SNMP version
238 358
239 my $version = ber_is_i32 $snmp->[0] 359 my $version = ber_is_int $snmp->[0]
240 or die "SNMP packet invalid: does not start with version number"; 360 or die "SNMP packet invalid: does not start with version number";
241 361
242=item $bool = ber_is_i32 $tuple, $i32 362=item $bool = ber_is_int $tuple, $int
243 363
244Returns a true value if the C<$tuple> represents an ASN INTEGER32 with 364Returns a true value if the C<$tuple> represents an ASN INTEGER with
245the value C<$i32>. 365the value C<$int>.
246 366
247=item $i32 = ber_is_i32 $tuple 367=item $int = ber_is_int $tuple
248 368
249Returns true (and extracts the integer value) if the C<$tuple> is an ASN 369Returns 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 370C<ASN_INTEGER>. For C<0>, this function returns a special value that is 0
251true. 371but true.
252 372
253=item $bool = ber_is_oid $tuple, $oid_string 373=item $bool = ber_is_oid $tuple, $oid_string
254 374
255Returns true if the C<$tuple> represents an ASN_OBJECT_IDENTIFIER 375Returns true if the C<$tuple> represents an ASN_OBJECT_IDENTIFIER
256that exactly matches C<$oid_string>. Example: 376that exactly matches C<$oid_string>. Example:
267 387
268=head3 CONSTRUCTION HELPERS 388=head3 CONSTRUCTION HELPERS
269 389
270=over 390=over
271 391
272=item $tuple = ber_i32 $value 392=item $tuple = ber_int $value
273 393
274Constructs a new C<ASN_INTEGER32> tuple. 394Constructs a new C<ASN_INTEGER> tuple.
275 395
276=back 396=back
277 397
278=head2 RELATIONSHIP TO L<Convert::BER> and L<Convert::ASN1> 398=head2 RELATIONSHIP TO L<Convert::BER> and L<Convert::ASN1>
279 399
292use Exporter qw(import); 412use Exporter qw(import);
293 413
294our $VERSION; 414our $VERSION;
295 415
296BEGIN { 416BEGIN {
297 $VERSION = 0.7; 417 $VERSION = '1.0';
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$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_TIMETICKS , BER_TYPE_INT);
473$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_OPAQUE , BER_TYPE_IPADDRESS);
474
475=head2 DEBUGGING
476
477To aid debugging, you cna call the C<ber_dump> function to print a "nice"
478representation to STDOUT.
479
480=over
481
482=item ber_dump $tuple[, $profile[, $prefix]]
483
484In addition to specifying the BER C<$tuple> to dump, youc an also specify
485a C<$profile> and a C<$prefix> string that is printed in front of each line.
486
487If C<$profile> is C<$Convert::BER::XS::SNMP_PROFILE>, then C<ber_dump>
488will try to improve its output for SNMP data.
489
490The output usually contains three columns, the "human readable" tag, the
491BER type used to decode it, and the data value.
492
493This function is somewhat slow and uses a number of heuristics and tricks,
494so it really is only suitable for debug prints.
495
496Example output:
497
498 SEQUENCE
499 | OCTET_STRING bytes 800063784300454045045400000001
500 | OCTET_STRING bytes
501 | CONTEXT (7) bytes CONSTRUCTED
502 | | INTEGER int 1058588941
503 | | INTEGER int 0
504 | | INTEGER int 0
505 | | SEQUENCE
506 | | | SEQUENCE
507 | | | | OID oid 1.3.6.1.2.1.1.3.0
508 | | | | TIMETICKS int 638085796
509
510=back
511
512=cut
513
514# reverse enum, very slow and ugly hack
515sub _re {
516 my ($export_tag, $value) = @_;
517
518 for my $symbol (@{ $EXPORT_TAGS{$export_tag} }) {
519 $value == eval $symbol
520 and return $symbol;
521 }
522
523 "($value)"
524}
525
526$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_COUNTER64 , BER_TYPE_INT);
527
528sub _ber_dump {
529 my ($ber, $profile, $indent) = @_;
530
531 if (my $seq = ber_is_seq $ber) {
532 printf "%sSEQUENCE\n", $indent;
533 &_ber_dump ($_, $profile, "$indent| ")
534 for @$seq;
535 } else {
536 my $asn = $ber->[BER_CLASS] == ASN_UNIVERSAL;
537
538 my $class = _re const_asn_class => $ber->[BER_CLASS];
539 my $tag = $asn ? _re const_asn_tag => $ber->[BER_TAG] : $ber->[BER_TAG];
540 my $type = _re const_ber_type => $profile->get ($ber->[BER_CLASS], $ber->[BER_TAG]);
541 my $data = $ber->[BER_DATA];
542
543 if ($profile == $SNMP_PROFILE and $ber->[BER_CLASS] == ASN_APPLICATION) {
544 $tag = _re const_snmp => $ber->[BER_TAG];
545 } elsif (!$asn) {
546 $tag = "$class ($tag)";
547 }
548
549 $class =~ s/^ASN_//;
550 $tag =~ s/^(ASN_|SNMP_)//;
551 $type =~ s/^BER_TYPE_//;
552
553 if ($ber->[BER_FLAGS]) {
554 printf "$indent%-16.16s %-6.6s CONSTRUCTED\n", $tag, lc $type;
555 &_ber_dump ($_, $profile, "$indent| ")
556 for @$data;
557 } else {
558 if ($data =~ y/\x20-\x7e//c / (length $data || 1) > 0.2 or $data =~ /\x00./s) {
559 # assume binary
560 $data = unpack "H*", $data;
561 } else {
562 $data =~ s/[^\x20-\x7e]/./g;
563 $data = "\"$data\"" if $type =~ /string/i || !length $data;
564 }
565
566 substr $data, 40, 1e9, "..." if 40 < length $data;
567
568 printf "$indent%-16.16s %-6.6s %s\n", $tag, lc $type, $data;
569 }
570 }
571}
572
573sub ber_dump($;$$) {
574 _ber_dump $_[0], $_[1] || $DEFAULT_PROFILE, $_[2];
575}
334 576
335=head1 PROFILES 577=head1 PROFILES
336 578
337While any BER data can be correctly encoded and decoded out of the box, it 579While any BER data can be correctly encoded and decoded out of the box, it
338can be inconvenient to have to manually decode some values into a "better" 580can be inconvenient to have to manually decode some values into a "better"
347 589
348The default profile supports the standard ASN.1 types, but no 590The default profile supports the standard ASN.1 types, but no
349application-specific ones. This means that class/tag combinations not in 591application-specific ones. This means that class/tag combinations not in
350the base set of ASN.1 are decoded into their raw octet strings. 592the base set of ASN.1 are decoded into their raw octet strings.
351 593
352C<Convert::BER::XS> defines two profile variables you cna use out of the box: 594C<Convert::BER::XS> defines two profile variables you can use out of the box:
353 595
354=over 596=over
355 597
356=item C<$Convert::BER::XS::DEFAULT_PROFILE> 598=item C<$Convert::BER::XS::DEFAULT_PROFILE>
357 599
358This is the default profile, i.e. the profile that is used when no 600This is the default profile, i.e. the profile that is used when no
359profile is specified for de-/encoding. 601profile is specified for de-/encoding.
360 602
361You cna modify it, but remember that this modifies the defaults for all 603You can modify it, but remember that this modifies the defaults for all
362callers that rely on the defauit profile. 604callers that rely on the default profile.
363 605
364=item C<$Convert::BER::XS::SNMP_PROFILE> 606=item C<$Convert::BER::XS::SNMP_PROFILE>
365 607
366A profile with mappings for SNMP-specific application tags added. This is 608A profile with mappings for SNMP-specific application tags added. This is
367useful when de-/encoding SNMP data. 609useful when de-/encoding SNMP data.
368 610
369Example: 611Example:
612
370 $ber = ber_decode $data, $Convert::BER::XS::SNMP_PROFILE; 613 $ber = ber_decode $data, $Convert::BER::XS::SNMP_PROFILE;
371 614
372=back 615=back
373 616
374=head2 The Convert::BER::XS::Profile class 617=head2 The Convert::BER::XS::Profile class
387 630
388Note that currently, the mapping is stored in a flat array, so large 631Note that currently, the mapping is stored in a flat array, so large
389values of C<$tag> will consume large amounts of memory. 632values of C<$tag> will consume large amounts of memory.
390 633
391Example: 634Example:
635
392 $profile = new Convert::BER::XS::Profile; 636 $profile = new Convert::BER::XS::Profile;
393 $profile->set (ASN_APPLICATION, SNMP_COUNTER32, BER_TYPE_INT); 637 $profile->set (ASN_APPLICATION, SNMP_COUNTER32, BER_TYPE_INT);
394 $ber = ber_decode $data, $profile; 638 $ber = ber_decode $data, $profile;
395 639
396=item $type = $profile->get ($class, $tag) 640=item $type = $profile->get ($class, $tag)
397 641
398Returns the BER type mapped to the given C<$class>/C<$tag> combination. 642Returns the BER type mapped to the given C<$class>/C<$tag> combination.
399 643
400=back 644=back
401 645
402=head2 BER TYPES 646=head2 BER Types
403 647
404This lists the predefined BER types - you can map any C<CLASS>/C<TAG> 648This lists the predefined BER types. BER types are formatters used
405combination to any C<BER_TYPE_*>. 649internally to format and encode BER values. You can assign any C<BER_TYPE>
650to any C<CLASS>/C<TAG> combination tgo change how that tag is decoded or
651encoded.
406 652
407=over 653=over
408 654
409=item C<BER_TYPE_BYTES> 655=item C<BER_TYPE_BYTES>
410 656
438Encodes and decodes an OBJECT IDENTIFIER into dotted form without leading 684Encodes and decodes an OBJECT IDENTIFIER into dotted form without leading
439dot, e.g. C<1.3.6.1.213>. 685dot, e.g. C<1.3.6.1.213>.
440 686
441=item C<BER_TYPE_RELOID> 687=item C<BER_TYPE_RELOID>
442 688
443Same as C<BER_TYPE_OID> but uses relative OID encoding: ASN.1 has this 689Same as C<BER_TYPE_OID> but uses relative object identifier
444hack of encoding the first two OID components into a single integer in a 690encoding: ASN.1 has this hack of encoding the first two OID components
445weird attempt to save an insignificant amount of space in an otherwise 691into a single integer in a weird attempt to save an insignificant amount
446wasteful encoding, and relative OIDs are basically OIDs without this 692of space in an otherwise wasteful encoding, and relative OIDs are
447hack. The practical difference is that the second component of an OID 693basically OIDs without this hack. The practical difference is that the
448can only have the values 1..40, while relative OIDs do not have this 694second component of an OID can only have the values 1..40, while relative
449restriction. 695OIDs do not have this restriction.
450 696
451=item C<BER_TYPE_NULL> 697=item C<BER_TYPE_NULL>
452 698
453Decodes an C<ASN_NULL> value into C<undef>, and always encodes a 699Decodes an C<ASN_NULL> value into C<undef>, and always encodes a
454C<ASN_NULL> type, regardless of the perl value. 700C<ASN_NULL> type, regardless of the perl value.
462 708
463Decodes/encodes a BER real value. NOT IMPLEMENTED. 709Decodes/encodes a BER real value. NOT IMPLEMENTED.
464 710
465=item C<BER_TYPE_IPADDRESS> 711=item C<BER_TYPE_IPADDRESS>
466 712
467Decodes/encodes a four byte string into an IOv4 dotted-quad address string 713Decodes/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 714in Perl. Given the obsolete nature of this type, this is a low-effort
469implementation that simply uses C<sprintf> and C<sscanf>-style conversion, 715implementation that simply uses C<sprintf> and C<sscanf>-style conversion,
470so it won't handle all string forms supported by C<inet_aton>. 716so it won't handle all string forms supported by C<inet_aton> for example.
471 717
472=item C<BER_TYPE_CROAK> 718=item C<BER_TYPE_CROAK>
473 719
474Always croaks when encountered during encoding or decoding - the 720Always croaks when encountered during encoding or decoding - the
475default behaviour when encountering an unknown type is to treat it as 721default 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 722C<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. 723error for some types, then C<BER_TYPE_CROAK> is for you.
478 724
479=back 725=back
480 726
481=cut 727=head2 Example Profile
482 728
483our $DEFAULT_PROFILE = new Convert::BER::XS::Profile; 729The following creates a profile suitable for SNMP - it's exactly identical
730to the C<$Convert::BER::XS::SNMP_PROFILE> profile.
731
484our $SNMP_PROFILE = new Convert::BER::XS::Profile; 732 our $SNMP_PROFILE = new Convert::BER::XS::Profile;
485 733
486$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_IPADDRESS , BER_TYPE_IPADDRESS); 734 $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_IPADDRESS , BER_TYPE_IPADDRESS);
487$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_COUNTER32 , BER_TYPE_INT); 735 $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_COUNTER32 , BER_TYPE_INT);
488$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_UNSIGNED32, BER_TYPE_INT); 736 $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_UNSIGNED32, BER_TYPE_INT);
489$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_TIMETICKS , BER_TYPE_INT); 737 $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_TIMETICKS , BER_TYPE_INT);
490$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_OPAQUE , BER_TYPE_IPADDRESS); 738 $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_OPAQUE , BER_TYPE_IPADDRESS);
491$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_COUNTER64 , BER_TYPE_INT); 739 $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_COUNTER64 , BER_TYPE_INT);
492 740
493$DEFAULT_PROFILE->_set_default;
494
4951;
496
497=head2 LIMITATIONS 741=head2 LIMITATIONS/NOTES
498 742
499This module can only en-/decode 64 bit signed and unsigned integers, and 743This module can only en-/decode 64 bit signed and unsigned integers, and
500only when your perl supports those. 744only when your perl supports those. So no UUID OIDs for now.
501 745
746This module does not generally care about ranges, i.e. it will happily
747de-/encode 64 bit integers into an C<ASN_INTEGER> value, or a negative
748number into an C<SNMP_COUNTER64>.
749
502OBJECT IDENTIFIEERS cannot have unlimited length, although the limit is 750OBJECT IDENTIFIEERs cannot have unlimited length, although the limit is
503much larger than e.g. the one imposed by SNMP or other protocols. 751much larger than e.g. the one imposed by SNMP or other protocols, and is
752about 4kB.
504 753
754Indefinite length encoding is not supported.
755
756Constructed strings are decoded just fine, but there should be a way to
757join them for convenience.
758
505REAL values are not supported and will croak. 759REAL values are not supported and will currently croak.
760
761The encoder and decoder tend to accept more formats than should be
762strictly supported - security sensitive applications are strongly advised
763to review the code first.
506 764
507This module has undergone little to no testing so far. 765This module has undergone little to no testing so far.
766
767=head2 ITHREADS SUPPORT
768
769This module is unlikely to work when the (officially discouraged) ithreads
770are in use.
508 771
509=head1 AUTHOR 772=head1 AUTHOR
510 773
511 Marc Lehmann <schmorp@schmorp.de> 774 Marc Lehmann <schmorp@schmorp.de>
512 http://software.schmorp.de/pkg/Convert-BER-XS 775 http://software.schmorp.de/pkg/Convert-BER-XS
513 776
514=cut 777=cut
515 778
7791;
780

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