1 |
=head1 NAME |
2 |
|
3 |
Convert::BER::XS - I<very> low level BER en-/decoding |
4 |
|
5 |
=head1 SYNOPSIS |
6 |
|
7 |
use Convert::BER::XS ':all'; |
8 |
|
9 |
my $ber = ber_decode $buf, $Convert::BER::XS::SNMP_PROFILE |
10 |
or die "unable to decode SNMP message"; |
11 |
|
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# The above results in a data structure consisting of |
13 |
# (class, tag, # constructed, data) |
14 |
# tuples. Below is such a message, SNMPv1 trap |
15 |
# with a Cisco mac change notification. |
16 |
# Did you know that Cisco is in the news almost |
17 |
# every week because of some backdoor password |
18 |
# or other extremely stupid security bug? |
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|
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[ ASN_UNIVERSAL, ASN_SEQUENCE, 1, |
21 |
[ |
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[ ASN_UNIVERSAL, ASN_INTEGER32, 0, 0 ], # snmp version 1 |
23 |
[ ASN_UNIVERSAL, 4, 0, "public" ], # community |
24 |
[ ASN_CONTEXT, 4, 1, # CHOICE, constructed - trap PDU |
25 |
[ |
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 |
28 |
[ ASN_UNIVERSAL, ASN_INTEGER32, 0, 6 ], # generic trap |
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[ ASN_UNIVERSAL, ASN_INTEGER32, 0, 1 ], # specific trap |
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[ ASN_APPLICATION, SNMP_TIMETICKS, 0, 1817903850 ], # SNMP TimeTicks |
31 |
[ ASN_UNIVERSAL, ASN_SEQUENCE, 1, # the varbindlist |
32 |
[ |
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[ ASN_UNIVERSAL, ASN_SEQUENCE, 1, # a single varbind, "key value" pair |
34 |
[ |
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[ 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 |
37 |
] |
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] |
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], |
40 |
... |
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|
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# let's decode it a bit with some helper functions |
43 |
|
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my $msg = ber_is_seq $ber |
45 |
or die "SNMP message does not start with a sequence"; |
46 |
|
47 |
ber_is $msg->[0], ASN_UNIVERSAL, ASN_INTEGER32, 0 |
48 |
or die "SNMP message does not start with snmp version\n"; |
49 |
|
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# message is SNMP v1 or v2c? |
51 |
if ($msg->[0][BER_DATA] == 0 || $msg->[0][BER_DATA] == 1) { |
52 |
|
53 |
# message is v1 trap? |
54 |
if (ber_is $msg->[2], ASN_CONTEXT, 4, 1) { |
55 |
my $trap = $msg->[2][BER_DATA]; |
56 |
|
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# check whether trap is a cisco mac notification mac changed message |
58 |
if ( |
59 |
(ber_is_oid $trap->[0], "1.3.6.1.4.1.9.9.215.2") # cmnInterfaceObjects |
60 |
and (ber_is_i32 $trap->[2], 6) |
61 |
and (ber_is_i32 $trap->[3], 1) # mac changed msg |
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) { |
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... and so on |
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|
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# finally, let's encode it again and hope it results in the same bit pattern |
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|
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my $buf = ber_encode $ber, $Convert::BER::XS::SNMP_PROFILE; |
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|
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=head1 DESCRIPTION |
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|
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WARNING: Before release 1.0, the API is not considered stable in any way. |
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|
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This module implements a I<very> low level BER/DER en-/decoder. |
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|
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It is tuned for low memory and high speed, while still maintaining some |
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level of user-friendlyness. |
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|
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=head2 EXPORT TAGS AND CONSTANTS |
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|
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By default this module doesn't export any symbols, but if you don't want |
81 |
to break your keyboard, editor or eyesight with extremely long names, I |
82 |
recommend importing the C<:all> tag. Still, you can selectively import |
83 |
things. |
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|
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=over |
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|
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=item C<:all> |
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|
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All of the below. Really. Recommended for at least first steps, or if you |
90 |
don't care about a few kilobytes of wasted memory (and namespace). |
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|
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=item C<:const> |
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|
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All of the strictly ASN.1-related constants defined by this module, the |
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same as C<:const_asn :const_index>. Notably, this does not contain |
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C<:const_ber_type> and C<:const_snmp>. |
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|
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A good set to get everything you need to decode and match BER data would be |
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C<:decode :const>. |
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|
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=item C<:const_index> |
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|
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The BER tuple array index constants: |
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|
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BER_CLASS BER_TAG BER_CONSTRUCTED BER_DATA |
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|
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=item C<:const_asn> |
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|
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ASN class values (these are C<0>, C<1>, C<2> and C<3>, respectively - |
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exactly thw two topmost bits from the identifier octet shifted 6 bits to |
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the right): |
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|
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ASN_UNIVERSAL ASN_APPLICATION ASN_CONTEXT ASN_PRIVATE |
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|
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ASN tag values (some of which are aliases, such as C<ASN_OID>). Their |
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numerical value corresponds exactly to the numbers used in BER/X.690. |
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|
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ASN_BOOLEAN ASN_INTEGER32 ASN_BIT_STRING ASN_OCTET_STRING ASN_NULL ASN_OBJECT_IDENTIFIER |
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ASN_OBJECT_DESCRIPTOR ASN_OID ASN_EXTERNAL ASN_REAL ASN_SEQUENCE ASN_ENUMERATED |
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ASN_EMBEDDED_PDV ASN_UTF8_STRING ASN_RELATIVE_OID ASN_SET ASN_NUMERIC_STRING |
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ASN_PRINTABLE_STRING ASN_TELETEX_STRING ASN_T61_STRING ASN_VIDEOTEX_STRING ASN_IA5_STRING |
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ASN_ASCII_STRING ASN_UTC_TIME ASN_GENERALIZED_TIME ASN_GRAPHIC_STRING ASN_VISIBLE_STRING |
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ASN_ISO646_STRING ASN_GENERAL_STRING ASN_UNIVERSAL_STRING ASN_CHARACTER_STRING ASN_BMP_STRING |
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|
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=item C<:const_ber_type> |
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|
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The BER type constants, explained in the PROFILES section. |
128 |
|
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BER_TYPE_BYTES BER_TYPE_UTF8 BER_TYPE_UCS2 BER_TYPE_UCS4 BER_TYPE_INT |
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BER_TYPE_OID BER_TYPE_RELOID BER_TYPE_NULL BER_TYPE_BOOL BER_TYPE_REAL |
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BER_TYPE_IPADDRESS BER_TYPE_CROAK |
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|
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=item C<:const_snmp> |
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|
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Constants only relevant to SNMP. These are the tag values used by SNMP in |
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the C<ASN_APPLICATION> namespace and have the exact numerical value as in |
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BER/RFC 2578. |
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|
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SNMP_IPADDRESS SNMP_COUNTER32 SNMP_UNSIGNED32 SNMP_TIMETICKS SNMP_OPAQUE SNMP_COUNTER64 |
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|
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=item C<:decode> |
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|
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C<ber_decode> and the match helper functions: |
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|
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ber_decode ber_is ber_is_seq ber_is_i32 ber_is_oid |
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|
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=item C<:encode> |
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|
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C<ber_encode> and the construction helper functions: |
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|
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ber_encode ber_i32 |
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|
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=back |
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|
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=head2 ASN.1/BER/DER/... BASICS |
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|
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ASN.1 is a strange language that can be used to describe protocols and |
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data structures. It supports various mappings to JSON, XML, but most |
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importantly, to a various binary encodings such as BER, that is the topic |
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of this module, and is used in SNMP or LDAP for example. |
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|
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While ASN.1 defines a schema that is useful to interpret encoded data, |
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the BER encoding is actually somewhat self-describing: you might not know |
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whether something is a string or a number or a sequence or something else, |
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but you can nevertheless decode the overall structure, even if you end up |
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with just a binary blob for the actual value. |
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|
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This works because BER values are tagged with a type and a namespace, |
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and also have a flag that says whether a value consists of subvalues (is |
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"constructed") or not (is "primitive"). |
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|
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Tags are simple integers, and ASN.1 defines a somewhat weird assortment of |
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those - for example, you have 32 bit signed integers and 16(!) different |
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string types, but there is no Unsigned32 type for example. Different |
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applications work around this in different ways, for example, SNMP defines |
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application-specific Gauge32, Counter32 and Unsigned32, which are mapped |
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to two different tags: you can distinguish between Counter32 and the |
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others, but not between Gause32 and Unsigned32, without the ASN.1 schema. |
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|
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Ugh. |
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|
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=head2 DECODED BER REPRESENTATION |
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|
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This module represents every BER value as a 4-element tuple (actually an |
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array-reference): |
186 |
|
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[CLASS, TAG, CONSTRUCTED, DATA] |
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|
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For example: |
190 |
|
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[ASN_UNIVERSAL, ASN_INTEGER32, 0, 177] # the integer 177 |
192 |
[ASN_UNIVERSAL, ASN_OCTET_STRING, 0, "john"] # the string "john" |
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[ASN_UNIVERSAL, ASN_OID, 0, "1.3.6.133"] # some OID |
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[ASN_UNIVERSAL, ASN_SEQUENCE, 1, [ [ASN_UNIVERSAL... # a sequence |
195 |
|
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To avoid non-descriptive hardcoded array index numbers, this module |
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defines symbolic constants to access these members: C<BER_CLASS>, |
198 |
C<BER_TAG>, C<BER_CONSTRUCTED> and C<BER_DATA>. |
199 |
|
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Also, the first three members are integers with a little caveat: for |
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performance reasons, these are readonly and shared, so you must not modify |
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them (increment, assign to them etc.) in any way. You may modify the |
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I<DATA> member, and you may re-assign the array itself, e.g.: |
204 |
|
205 |
$ber = ber_decode $binbuf; |
206 |
|
207 |
# the following is NOT legal: |
208 |
$ber->[BER_CLASS] = ASN_PRIVATE; # ERROR, CLASS/TAG/CONSTRUCTED are READ ONLY(!) |
209 |
|
210 |
# but all of the following are fine: |
211 |
$ber->[BER_DATA] = "string"; |
212 |
$ber->[BER_DATA] = [ASN_UNIVERSAL, ASN_INTEGER32, 0, 123]; |
213 |
@$ber = (ASN_APPLICATION, SNMP_TIMETICKS, 0, 1000); |
214 |
|
215 |
I<CLASS> is something like a namespace for I<TAG>s - there is the |
216 |
C<ASN_UNIVERSAL> namespace which defines tags common to all ASN.1 |
217 |
implementations, the C<ASN_APPLICATION> namespace which defines tags for |
218 |
specific applications (for example, the SNMP C<Unsigned32> type is in this |
219 |
namespace), a special-purpose context namespace (C<ASN_CONTEXT>, used e.g. |
220 |
for C<CHOICE>) and a private namespace (C<ASN_PRIVATE>). |
221 |
|
222 |
The meaning of the I<TAG> depends on the namespace, and defines a |
223 |
(partial) interpretation of the data value. For example, SNMP defines |
224 |
extra tags in the C<ASN_APPLICATION> namespace, and to take full advantage |
225 |
of these, you need to tell this module how to handle those via profiles. |
226 |
|
227 |
The most common tags in the C<ASN_UNIVERSAL> namespace are |
228 |
C<ASN_INTEGER32>, C<ASN_BIT_STRING>, C<ASN_NULL>, C<ASN_OCTET_STRING>, |
229 |
C<ASN_OBJECT_IDENTIFIER>, C<ASN_SEQUENCE>, C<ASN_SET> and |
230 |
C<ASN_IA5_STRING>. |
231 |
|
232 |
The most common tags in SNMP's C<ASN_APPLICATION> namespace are |
233 |
C<SNMP_COUNTER32>, C<SNMP_UNSIGNED32>, C<SNMP_TIMETICKS> and |
234 |
C<SNMP_COUNTER64>. |
235 |
|
236 |
The I<CONSTRUCTED> flag is really just a boolean - if it is false, |
237 |
the value is "primitive" and contains no subvalues, kind of like a |
238 |
non-reference perl scalar. If it is true, then the value is "constructed" |
239 |
which just means it contains a list of subvalues which this module will |
240 |
en-/decode as BER tuples themselves. |
241 |
|
242 |
The I<DATA> value is either a reference to an array of further tuples (if |
243 |
the value is I<CONSTRUCTED>), some decoded representation of the value, |
244 |
if this module knows how to decode it (e.g. for the integer types above) |
245 |
or a binary string with the raw octets if this module doesn't know how to |
246 |
interpret the namespace/tag. |
247 |
|
248 |
Thus, you can always decode a BER data structure and at worst you get a |
249 |
string in place of some nice decoded value. |
250 |
|
251 |
See the SYNOPSIS for an example of such an encoded tuple representation. |
252 |
|
253 |
=head2 DECODING AND ENCODING |
254 |
|
255 |
=over |
256 |
|
257 |
=item $tuple = ber_decoded $bindata[, $profile] |
258 |
|
259 |
Decodes binary BER data in C<$bindata> and returns the resulting BER |
260 |
tuple. Croaks on any decoding error, so the returned C<$tuple> is always |
261 |
valid. |
262 |
|
263 |
How tags are interpreted is defined by the second argument, which must |
264 |
be a C<Convert::BER::XS::Profile> object. If it is missing, the default |
265 |
profile will be used (C<$Convert::BER::XS::DEFAULT_PROFILE>). |
266 |
|
267 |
In addition to rolling your own, this module provides a |
268 |
C<$Convert::BER::XS::SNMP_PROFILE> that knows about the additional SNMP |
269 |
types. |
270 |
|
271 |
=item $bindata = ber_encode $tuple[, $profile] |
272 |
|
273 |
Encodes the BER tuple into a BER/DER data structure. AS with |
274 |
Cyber_decode>, an optional profile can be given. |
275 |
|
276 |
=back |
277 |
|
278 |
=head2 HELPER FUNCTIONS |
279 |
|
280 |
Working with a 4-tuple for every value can be annoying. Or, rather, I<is> |
281 |
annoying. To reduce this a bit, this module defines a number of helper |
282 |
functions, both to match BER tuples and to construct BER tuples: |
283 |
|
284 |
=head3 MATCH HELPERS |
285 |
|
286 |
These functions accept a BER tuple as first argument and either partially |
287 |
or fully match it. They often come in two forms, one which exactly matches |
288 |
a value, and one which only matches the type and returns the value. |
289 |
|
290 |
They do check whether valid tuples are passed in and croak otherwise. As |
291 |
a ease-of-use exception, they usually also accept C<undef> instead of a |
292 |
tuple reference, in which case they silently fail to match. |
293 |
|
294 |
=over |
295 |
|
296 |
=item $bool = ber_is $tuple, $class, $tag, $constructed, $data |
297 |
|
298 |
This takes a BER C<$tuple> and matches its elements against the provided |
299 |
values, all of which are optional - values that are either missing or |
300 |
C<undef> will be ignored, the others will be matched exactly (e.g. as if |
301 |
you used C<==> or C<eq> (for C<$data>)). |
302 |
|
303 |
Some examples: |
304 |
|
305 |
ber_is $tuple, ASN_UNIVERSAL, ASN_SEQUENCE, 1 |
306 |
orf die "tuple is not an ASN SEQUENCE"; |
307 |
|
308 |
ber_is $tuple, ASN_UNIVERSAL, ASN_NULL |
309 |
or die "tuple is not an ASN NULL value"; |
310 |
|
311 |
ber_is $tuple, ASN_UNIVERSAL, ASN_INTEGER32, 0, 50 |
312 |
or die "BER integer must be 50"; |
313 |
|
314 |
=item $seq = ber_is_seq $tuple |
315 |
|
316 |
Returns the sequence members (the array of subvalues) if the C<$tuple> is |
317 |
an ASN SEQUENCE, i.e. the C<BER_DATA> member. If the C<$tuple> is not a |
318 |
sequence it returns C<undef>. For example, SNMP version 1/2c/3 packets all |
319 |
consist of an outer SEQUENCE value: |
320 |
|
321 |
my $ber = ber_decode $snmp_data; |
322 |
|
323 |
my $snmp = ber_is_seq $ber |
324 |
or die "SNMP packet invalid: does not start with SEQUENCE"; |
325 |
|
326 |
# now we know $snmp is a sequence, so decode the SNMP version |
327 |
|
328 |
my $version = ber_is_i32 $snmp->[0] |
329 |
or die "SNMP packet invalid: does not start with version number"; |
330 |
|
331 |
=item $bool = ber_is_i32 $tuple, $i32 |
332 |
|
333 |
Returns a true value if the C<$tuple> represents an ASN INTEGER32 with |
334 |
the value C<$i32>. |
335 |
|
336 |
=item $i32 = ber_is_i32 $tuple |
337 |
|
338 |
Returns true (and extracts the integer value) if the C<$tuple> is an ASN |
339 |
INTEGER32. For C<0>, this function returns a special value that is 0 but |
340 |
true. |
341 |
|
342 |
=item $bool = ber_is_oid $tuple, $oid_string |
343 |
|
344 |
Returns true if the C<$tuple> represents an ASN_OBJECT_IDENTIFIER |
345 |
that exactly matches C<$oid_string>. Example: |
346 |
|
347 |
ber_is_oid $tuple, "1.3.6.1.4" |
348 |
or die "oid must be 1.3.6.1.4"; |
349 |
|
350 |
=item $oid = ber_is_oid $tuple |
351 |
|
352 |
Returns true (and extracts the OID string) if the C<$tuple> is an ASN |
353 |
OBJECT IDENTIFIER. Otherwise, it returns C<undef>. |
354 |
|
355 |
=back |
356 |
|
357 |
=head3 CONSTRUCTION HELPERS |
358 |
|
359 |
=over |
360 |
|
361 |
=item $tuple = ber_i32 $value |
362 |
|
363 |
Constructs a new C<ASN_INTEGER32> tuple. |
364 |
|
365 |
=back |
366 |
|
367 |
=head2 RELATIONSHIP TO L<Convert::BER> and L<Convert::ASN1> |
368 |
|
369 |
This module is I<not> the XS version of L<Convert::BER>, but a different |
370 |
take at doing the same thing. I imagine this module would be a good base |
371 |
for speeding up either of these, or write a similar module, or write your |
372 |
own LDAP or SNMP module for example. |
373 |
|
374 |
=cut |
375 |
|
376 |
package Convert::BER::XS; |
377 |
|
378 |
use common::sense; |
379 |
|
380 |
use XSLoader (); |
381 |
use Exporter qw(import); |
382 |
|
383 |
our $VERSION; |
384 |
|
385 |
BEGIN { |
386 |
$VERSION = 0.8; |
387 |
XSLoader::load __PACKAGE__, $VERSION; |
388 |
} |
389 |
|
390 |
our %EXPORT_TAGS = ( |
391 |
const_index => [qw( |
392 |
BER_CLASS BER_TAG BER_CONSTRUCTED BER_DATA |
393 |
)], |
394 |
const_asn => [qw( |
395 |
ASN_BOOLEAN ASN_INTEGER32 ASN_BIT_STRING ASN_OCTET_STRING ASN_NULL ASN_OBJECT_IDENTIFIER |
396 |
ASN_OBJECT_DESCRIPTOR ASN_OID ASN_EXTERNAL ASN_REAL ASN_SEQUENCE ASN_ENUMERATED |
397 |
ASN_EMBEDDED_PDV ASN_UTF8_STRING ASN_RELATIVE_OID ASN_SET ASN_NUMERIC_STRING |
398 |
ASN_PRINTABLE_STRING ASN_TELETEX_STRING ASN_T61_STRING ASN_VIDEOTEX_STRING ASN_IA5_STRING |
399 |
ASN_ASCII_STRING ASN_UTC_TIME ASN_GENERALIZED_TIME ASN_GRAPHIC_STRING ASN_VISIBLE_STRING |
400 |
ASN_ISO646_STRING ASN_GENERAL_STRING ASN_UNIVERSAL_STRING ASN_CHARACTER_STRING ASN_BMP_STRING |
401 |
|
402 |
ASN_UNIVERSAL ASN_APPLICATION ASN_CONTEXT ASN_PRIVATE |
403 |
)], |
404 |
const_ber_type => [qw( |
405 |
BER_TYPE_BYTES BER_TYPE_UTF8 BER_TYPE_UCS2 BER_TYPE_UCS4 BER_TYPE_INT |
406 |
BER_TYPE_OID BER_TYPE_RELOID BER_TYPE_NULL BER_TYPE_BOOL BER_TYPE_REAL |
407 |
BER_TYPE_IPADDRESS BER_TYPE_CROAK |
408 |
)], |
409 |
const_snmp => [qw( |
410 |
SNMP_IPADDRESS SNMP_COUNTER32 SNMP_UNSIGNED32 SNMP_TIMETICKS SNMP_OPAQUE SNMP_COUNTER64 |
411 |
)], |
412 |
decode => [qw( |
413 |
ber_decode |
414 |
ber_is ber_is_seq ber_is_i32 ber_is_oid |
415 |
)], |
416 |
encode => [qw( |
417 |
ber_encode |
418 |
ber_i32 |
419 |
)], |
420 |
); |
421 |
|
422 |
our @EXPORT_OK = map @$_, values %EXPORT_TAGS; |
423 |
|
424 |
$EXPORT_TAGS{all} = \@EXPORT_OK; |
425 |
$EXPORT_TAGS{const} = [map @{ $EXPORT_TAGS{$_} }, qw(const_index const_asn)]; |
426 |
use Data::Dump; ddx \%EXPORT_TAGS; |
427 |
|
428 |
=head1 PROFILES |
429 |
|
430 |
While any BER data can be correctly encoded and decoded out of the box, it |
431 |
can be inconvenient to have to manually decode some values into a "better" |
432 |
format: for instance, SNMP TimeTicks values are decoded into the raw octet |
433 |
strings of their BER representation, which is quite hard to decode. With |
434 |
profiles, you can change which class/tag combinations map to which decoder |
435 |
function inside C<ber_decode> (and of course also which encoder functions |
436 |
are used in C<ber_encode>). |
437 |
|
438 |
This works by mapping specific class/tag combinations to an internal "ber |
439 |
type". |
440 |
|
441 |
The default profile supports the standard ASN.1 types, but no |
442 |
application-specific ones. This means that class/tag combinations not in |
443 |
the base set of ASN.1 are decoded into their raw octet strings. |
444 |
|
445 |
C<Convert::BER::XS> defines two profile variables you can use out of the box: |
446 |
|
447 |
=over |
448 |
|
449 |
=item C<$Convert::BER::XS::DEFAULT_PROFILE> |
450 |
|
451 |
This is the default profile, i.e. the profile that is used when no |
452 |
profile is specified for de-/encoding. |
453 |
|
454 |
You can modify it, but remember that this modifies the defaults for all |
455 |
callers that rely on the default profile. |
456 |
|
457 |
=item C<$Convert::BER::XS::SNMP_PROFILE> |
458 |
|
459 |
A profile with mappings for SNMP-specific application tags added. This is |
460 |
useful when de-/encoding SNMP data. |
461 |
|
462 |
Example: |
463 |
|
464 |
$ber = ber_decode $data, $Convert::BER::XS::SNMP_PROFILE; |
465 |
|
466 |
=back |
467 |
|
468 |
=head2 The Convert::BER::XS::Profile class |
469 |
|
470 |
=over |
471 |
|
472 |
=item $profile = new Convert::BER::XS::Profile |
473 |
|
474 |
Create a new profile. The profile will be identical to the default |
475 |
profile. |
476 |
|
477 |
=item $profile->set ($class, $tag, $type) |
478 |
|
479 |
Sets the mapping for the given C<$class>/C<$tag> combination to C<$type>, |
480 |
which must be one of the C<BER_TYPE_*> constants. |
481 |
|
482 |
Note that currently, the mapping is stored in a flat array, so large |
483 |
values of C<$tag> will consume large amounts of memory. |
484 |
|
485 |
Example: |
486 |
|
487 |
$profile = new Convert::BER::XS::Profile; |
488 |
$profile->set (ASN_APPLICATION, SNMP_COUNTER32, BER_TYPE_INT); |
489 |
$ber = ber_decode $data, $profile; |
490 |
|
491 |
=item $type = $profile->get ($class, $tag) |
492 |
|
493 |
Returns the BER type mapped to the given C<$class>/C<$tag> combination. |
494 |
|
495 |
=back |
496 |
|
497 |
=head2 BER TYPES |
498 |
|
499 |
This lists the predefined BER types - you can map any C<CLASS>/C<TAG> |
500 |
combination to any C<BER_TYPE_*>. |
501 |
|
502 |
=over |
503 |
|
504 |
=item C<BER_TYPE_BYTES> |
505 |
|
506 |
The raw octets of the value. This is the default type for unknown tags and |
507 |
de-/encodes the value as if it were an octet string, i.e. by copying the |
508 |
raw bytes. |
509 |
|
510 |
=item C<BER_TYPE_UTF8> |
511 |
|
512 |
Like C<BER_TYPE_BYTES>, but decodes the value as if it were a UTF-8 string |
513 |
(without validation!) and encodes a perl unicode string into a UTF-8 BER |
514 |
string. |
515 |
|
516 |
=item C<BER_TYPE_UCS2> |
517 |
|
518 |
Similar to C<BER_TYPE_UTF8>, but treats the BER value as UCS-2 encoded |
519 |
string. |
520 |
|
521 |
=item C<BER_TYPE_UCS4> |
522 |
|
523 |
Similar to C<BER_TYPE_UTF8>, but treats the BER value as UCS-4 encoded |
524 |
string. |
525 |
|
526 |
=item C<BER_TYPE_INT> |
527 |
|
528 |
Encodes and decodes a BER integer value to a perl integer scalar. This |
529 |
should correctly handle 64 bit signed and unsigned values. |
530 |
|
531 |
=item C<BER_TYPE_OID> |
532 |
|
533 |
Encodes and decodes an OBJECT IDENTIFIER into dotted form without leading |
534 |
dot, e.g. C<1.3.6.1.213>. |
535 |
|
536 |
=item C<BER_TYPE_RELOID> |
537 |
|
538 |
Same as C<BER_TYPE_OID> but uses relative object identifier |
539 |
encoding: ASN.1 has this hack of encoding the first two OID components |
540 |
into a single integer in a weird attempt to save an insignificant amount |
541 |
of space in an otherwise wasteful encoding, and relative OIDs are |
542 |
basically OIDs without this hack. The practical difference is that the |
543 |
second component of an OID can only have the values 1..40, while relative |
544 |
OIDs do not have this restriction. |
545 |
|
546 |
=item C<BER_TYPE_NULL> |
547 |
|
548 |
Decodes an C<ASN_NULL> value into C<undef>, and always encodes a |
549 |
C<ASN_NULL> type, regardless of the perl value. |
550 |
|
551 |
=item C<BER_TYPE_BOOL> |
552 |
|
553 |
Decodes an C<ASN_BOOLEAN> value into C<0> or C<1>, and encodes a perl |
554 |
boolean value into an C<ASN_BOOLEAN>. |
555 |
|
556 |
=item C<BER_TYPE_REAL> |
557 |
|
558 |
Decodes/encodes a BER real value. NOT IMPLEMENTED. |
559 |
|
560 |
=item C<BER_TYPE_IPADDRESS> |
561 |
|
562 |
Decodes/encodes a four byte string into an IPv4 dotted-quad address string |
563 |
in Perl. Given the obsolete nature of this type, this is a low-effort |
564 |
implementation that simply uses C<sprintf> and C<sscanf>-style conversion, |
565 |
so it won't handle all string forms supported by C<inet_aton> for example. |
566 |
|
567 |
=item C<BER_TYPE_CROAK> |
568 |
|
569 |
Always croaks when encountered during encoding or decoding - the |
570 |
default behaviour when encountering an unknown type is to treat it as |
571 |
C<BER_TYPE_BYTES>. When you don't want that but instead prefer a hard |
572 |
error for some types, then C<BER_TYPE_CROAK> is for you. |
573 |
|
574 |
=back |
575 |
|
576 |
=cut |
577 |
|
578 |
our $DEFAULT_PROFILE = new Convert::BER::XS::Profile; |
579 |
our $SNMP_PROFILE = new Convert::BER::XS::Profile; |
580 |
|
581 |
# additional SNMP application types |
582 |
$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_IPADDRESS , BER_TYPE_IPADDRESS); |
583 |
$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_COUNTER32 , BER_TYPE_INT); |
584 |
$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_UNSIGNED32, BER_TYPE_INT); |
585 |
$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_TIMETICKS , BER_TYPE_INT); |
586 |
$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_OPAQUE , BER_TYPE_IPADDRESS); |
587 |
$SNMP_PROFILE->set (ASN_APPLICATION, SNMP_COUNTER64 , BER_TYPE_INT); |
588 |
|
589 |
$DEFAULT_PROFILE->_set_default; |
590 |
|
591 |
1; |
592 |
|
593 |
=head2 LIMITATIONS/NOTES |
594 |
|
595 |
This module can only en-/decode 64 bit signed and unsigned integers, and |
596 |
only when your perl supports those. |
597 |
|
598 |
This module does not generally care about ranges, i.e. it will happily |
599 |
de-/encode 64 bit integers into an C<ASN_INTEGER32> value, or a negative |
600 |
number into an C<SNMP_COUNTER64>. |
601 |
|
602 |
OBJECT IDENTIFIEERs cannot have unlimited length, although the limit is |
603 |
much larger than e.g. the one imposed by SNMP or other protocols,a nd is |
604 |
about 4kB. |
605 |
|
606 |
REAL values are not supported and will currently croak. |
607 |
|
608 |
This module has undergone little to no testing so far. |
609 |
|
610 |
=head2 ITHREADS SUPPORT |
611 |
|
612 |
This module is unlikely to work when the (officially discouraged) ithreads |
613 |
are in use. |
614 |
|
615 |
=head1 AUTHOR |
616 |
|
617 |
Marc Lehmann <schmorp@schmorp.de> |
618 |
http://software.schmorp.de/pkg/Convert-BER-XS |
619 |
|
620 |
=cut |
621 |
|