… | |
… | |
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 (class, tag, |
12 | # The above results in a data structure consisting of |
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13 | # (class, tag, # constructed, data) |
13 | # constructed, data) tuples. Below is such a message, SNMPv1 trap |
14 | # tuples. Below is such a message, SNMPv1 trap |
14 | # with a Cisco mac change notification. |
15 | # with a Cisco mac change notification. |
15 | # Did you know that Cisco is in the news almost every week because |
16 | # Did you know that Cisco is in the news almost |
|
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17 | # every week because of some backdoor password |
16 | # of some backdoor password or other extremely stupid security bug? |
18 | # or other extremely stupid security bug? |
17 | |
19 | |
18 | [ ASN_UNIVERSAL, ASN_SEQUENCE, 1, |
20 | [ ASN_UNIVERSAL, ASN_SEQUENCE, 1, |
19 | [ |
21 | [ |
20 | [ ASN_UNIVERSAL, ASN_INTEGER32, 0, 0 ], # snmp version 1 |
22 | [ ASN_UNIVERSAL, ASN_INTEGER, 0, 0 ], # snmp version 1 |
21 | [ ASN_UNIVERSAL, 4, 0, "public" ], # community |
23 | [ ASN_UNIVERSAL, 4, 0, "public" ], # community |
22 | [ ASN_CONTEXT, 4, 1, # CHOICE, constructed - trap PDU |
24 | [ ASN_CONTEXT, 4, 1, # CHOICE, constructed - trap PDU |
23 | [ |
25 | [ |
24 | [ 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 |
25 | [ 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 |
26 | [ ASN_UNIVERSAL, ASN_INTEGER32, 0, 6 ], # generic trap |
28 | [ ASN_UNIVERSAL, ASN_INTEGER, 0, 6 ], # generic trap |
27 | [ ASN_UNIVERSAL, ASN_INTEGER32, 0, 1 ], # specific trap |
29 | [ ASN_UNIVERSAL, ASN_INTEGER, 0, 1 ], # specific trap |
28 | [ ASN_APPLICATION, ASN_TIMETICKS, 0, 1817903850 ], # SNMP TimeTicks |
30 | [ ASN_APPLICATION, SNMP_TIMETICKS, 0, 1817903850 ], # SNMP TimeTicks |
29 | [ ASN_UNIVERSAL, ASN_SEQUENCE, 1, # the varbindlist |
31 | [ ASN_UNIVERSAL, ASN_SEQUENCE, 1, # the varbindlist |
30 | [ |
32 | [ |
31 | [ ASN_UNIVERSAL, ASN_SEQUENCE, 1, # a single varbind, "key value" pair |
33 | [ ASN_UNIVERSAL, ASN_SEQUENCE, 1, # a single varbind, "key value" pair |
32 | [ |
34 | [ |
33 | [ 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" ], |
… | |
… | |
40 | # let's decode it a bit with some helper functions |
42 | # let's decode it a bit with some helper functions |
41 | |
43 | |
42 | my $msg = ber_is_seq $ber |
44 | my $msg = ber_is_seq $ber |
43 | or die "SNMP message does not start with a sequence"; |
45 | or die "SNMP message does not start with a sequence"; |
44 | |
46 | |
45 | ber_is $msg->[0], ASN_UNIVERSAL, ASN_INTEGER32, 0 |
47 | ber_is $msg->[0], ASN_UNIVERSAL, ASN_INTEGER, 0 |
46 | or die "SNMP message does not start with snmp version\n"; |
48 | or die "SNMP message does not start with snmp version\n"; |
47 | |
49 | |
48 | # message is SNMP v1 or v2c? |
50 | # message is SNMP v1 or v2c? |
49 | if ($msg->[0][BER_DATA] == 0 || $msg->[0][BER_DATA] == 1) { |
51 | if ($msg->[0][BER_DATA] == 0 || $msg->[0][BER_DATA] == 1) { |
50 | |
52 | |
… | |
… | |
53 | my $trap = $msg->[2][BER_DATA]; |
55 | my $trap = $msg->[2][BER_DATA]; |
54 | |
56 | |
55 | # check whether trap is a cisco mac notification mac changed message |
57 | # check whether trap is a cisco mac notification mac changed message |
56 | if ( |
58 | if ( |
57 | (ber_is_oid $trap->[0], "1.3.6.1.4.1.9.9.215.2") # cmnInterfaceObjects |
59 | (ber_is_oid $trap->[0], "1.3.6.1.4.1.9.9.215.2") # cmnInterfaceObjects |
58 | and (ber_is_i32 $trap->[2], 6) |
60 | and (ber_is_int $trap->[2], 6) |
59 | and (ber_is_i32 $trap->[3], 1) # mac changed msg |
61 | and (ber_is_int $trap->[3], 1) # mac changed msg |
60 | ) { |
62 | ) { |
61 | ... and so on |
63 | ... and so on |
62 | |
64 | |
63 | # finally, let's encode it again and hope it results in the same bit pattern |
65 | # finally, let's encode it again and hope it results in the same bit pattern |
64 | |
66 | |
65 | my $buf = ber_encode $ber; |
67 | my $buf = ber_encode $ber, $Convert::BER::XS::SNMP_PROFILE; |
66 | |
68 | |
67 | =head1 DESCRIPTION |
69 | =head1 DESCRIPTION |
68 | |
70 | |
69 | WARNING: Before release 1.0, the API is not considered stable in any way. |
71 | WARNING: Before release 1.0, the API is not considered stable in any way. |
70 | |
72 | |
71 | This module implements a I<very> low level BER/DER en-/decoder. |
73 | This module implements a I<very> low level BER/DER en-/decoder. |
72 | |
74 | |
73 | If is tuned for low memory and high speed, while still maintaining some |
75 | It is tuned for low memory and high speed, while still maintaining some |
74 | level of user-friendlyness. |
76 | level of user-friendlyness. |
75 | |
77 | |
76 | Currently, not much is documented, as this is an initial release to |
78 | =head2 EXPORT TAGS AND CONSTANTS |
77 | reserve CPAN namespace, stay tuned for a few days. |
79 | |
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80 | By default this module doesn't export any symbols, but if you don't want |
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81 | to break your keyboard, editor or eyesight with extremely long names, I |
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82 | recommend importing the C<:all> tag. Still, you can selectively import |
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83 | things. |
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84 | |
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85 | =over |
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86 | |
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87 | =item C<:all> |
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88 | |
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89 | All of the below. Really. Recommended for at least first steps, or if you |
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90 | don't care about a few kilobytes of wasted memory (and namespace). |
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91 | |
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92 | =item C<:const> |
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93 | |
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94 | All of the strictly ASN.1-related constants defined by this module, the |
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95 | same as C<:const_asn :const_index>. Notably, this does not contain |
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96 | C<:const_ber_type> and C<:const_snmp>. |
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97 | |
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98 | A good set to get everything you need to decode and match BER data would be |
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99 | C<:decode :const>. |
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100 | |
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101 | =item C<:const_index> |
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102 | |
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103 | The BER tuple array index constants: |
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104 | |
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105 | BER_CLASS BER_TAG BER_CONSTRUCTED BER_DATA |
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106 | |
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107 | =item C<:const_asn> |
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108 | |
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109 | ASN class values (these are C<0>, C<1>, C<2> and C<3>, respectively - |
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110 | exactly thw two topmost bits from the identifier octet shifted 6 bits to |
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111 | the right): |
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112 | |
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113 | ASN_UNIVERSAL ASN_APPLICATION ASN_CONTEXT ASN_PRIVATE |
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114 | |
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115 | ASN tag values (some of which are aliases, such as C<ASN_OID>). Their |
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116 | numerical value corresponds exactly to the numbers used in BER/X.690. |
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117 | |
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118 | ASN_BOOLEAN ASN_INTEGER ASN_BIT_STRING ASN_OCTET_STRING ASN_NULL ASN_OBJECT_IDENTIFIER |
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119 | ASN_OBJECT_DESCRIPTOR ASN_OID ASN_EXTERNAL ASN_REAL ASN_SEQUENCE ASN_ENUMERATED |
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120 | ASN_EMBEDDED_PDV ASN_UTF8_STRING ASN_RELATIVE_OID ASN_SET ASN_NUMERIC_STRING |
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121 | ASN_PRINTABLE_STRING ASN_TELETEX_STRING ASN_T61_STRING ASN_VIDEOTEX_STRING ASN_IA5_STRING |
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122 | ASN_ASCII_STRING ASN_UTC_TIME ASN_GENERALIZED_TIME ASN_GRAPHIC_STRING ASN_VISIBLE_STRING |
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123 | ASN_ISO646_STRING ASN_GENERAL_STRING ASN_UNIVERSAL_STRING ASN_CHARACTER_STRING ASN_BMP_STRING |
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124 | |
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125 | =item C<:const_ber_type> |
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126 | |
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127 | The BER type constants, explained in the PROFILES section. |
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128 | |
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129 | BER_TYPE_BYTES BER_TYPE_UTF8 BER_TYPE_UCS2 BER_TYPE_UCS4 BER_TYPE_INT |
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130 | BER_TYPE_OID BER_TYPE_RELOID BER_TYPE_NULL BER_TYPE_BOOL BER_TYPE_REAL |
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131 | BER_TYPE_IPADDRESS BER_TYPE_CROAK |
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132 | |
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133 | =item C<:const_snmp> |
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134 | |
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135 | Constants only relevant to SNMP. These are the tag values used by SNMP in |
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136 | the C<ASN_APPLICATION> namespace and have the exact numerical value as in |
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137 | BER/RFC 2578. |
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138 | |
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139 | SNMP_IPADDRESS SNMP_COUNTER32 SNMP_UNSIGNED32 SNMP_TIMETICKS SNMP_OPAQUE SNMP_COUNTER64 |
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140 | |
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141 | =item C<:decode> |
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142 | |
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143 | C<ber_decode> and the match helper functions: |
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144 | |
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145 | ber_decode ber_is ber_is_seq ber_is_int ber_is_oid |
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146 | |
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147 | =item C<:encode> |
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148 | |
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149 | C<ber_encode> and the construction helper functions: |
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150 | |
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151 | ber_encode ber_int |
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152 | |
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153 | =back |
78 | |
154 | |
79 | =head2 ASN.1/BER/DER/... BASICS |
155 | =head2 ASN.1/BER/DER/... BASICS |
80 | |
156 | |
81 | ASN.1 is a strange language that can be sed to describe protocols and |
157 | ASN.1 is a strange language that can be used to describe protocols and |
82 | data structures. It supports various mappings to JSON, XML, but most |
158 | data structures. It supports various mappings to JSON, XML, but most |
83 | importantly, to a various binary encodings such as BER, that is the topic |
159 | importantly, to a various binary encodings such as BER, that is the topic |
84 | of this module, and is used in SNMP or LDAP for example. |
160 | of this module, and is used in SNMP or LDAP for example. |
85 | |
161 | |
86 | While ASN.1 defines a schema that is useful to interpret encoded data, |
162 | While ASN.1 defines a schema that is useful to interpret encoded data, |
… | |
… | |
88 | whether something is a string or a number or a sequence or something else, |
164 | whether something is a string or a number or a sequence or something else, |
89 | but you can nevertheless decode the overall structure, even if you end up |
165 | but you can nevertheless decode the overall structure, even if you end up |
90 | with just a binary blob for the actual value. |
166 | with just a binary blob for the actual value. |
91 | |
167 | |
92 | This works because BER values are tagged with a type and a namespace, |
168 | This works because BER values are tagged with a type and a namespace, |
93 | and also have a flag that says whther a value consists of subvalues (is |
169 | and also have a flag that says whether a value consists of subvalues (is |
94 | "constructed") or not (is "primitive"). |
170 | "constructed") or not (is "primitive"). |
95 | |
171 | |
96 | Tags are simple integers, and ASN.1 defines a somewhat weird assortment of |
172 | Tags are simple integers, and ASN.1 defines a somewhat weird assortment |
97 | those - for example, you have 32 bit signed integers and 16(!) different |
173 | of those - for example, you have one integers and 16(!) different |
98 | string types, but there is no unsigned32 type for example. Different |
174 | string types, but there is no Unsigned32 type for example. Different |
99 | applications work around this in different ways, for example, SNMP defines |
175 | applications work around this in different ways, for example, SNMP defines |
100 | application-specific Gauge32, Counter32 and Unsigned32, which are mapped |
176 | application-specific Gauge32, Counter32 and Unsigned32, which are mapped |
101 | to two different tags: you can distinguish between Counter32 and the |
177 | to two different tags: you can distinguish between Counter32 and the |
102 | others, but not between Gause32 and Unsigned32, without the ASN.1 schema. |
178 | others, but not between Gause32 and Unsigned32, without the ASN.1 schema. |
103 | |
179 | |
… | |
… | |
108 | This module represents every BER value as a 4-element tuple (actually an |
184 | This module represents every BER value as a 4-element tuple (actually an |
109 | array-reference): |
185 | array-reference): |
110 | |
186 | |
111 | [CLASS, TAG, CONSTRUCTED, DATA] |
187 | [CLASS, TAG, CONSTRUCTED, DATA] |
112 | |
188 | |
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189 | For example: |
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190 | |
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191 | [ASN_UNIVERSAL, ASN_INTEGER, 0, 177] # the integer 177 |
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192 | [ASN_UNIVERSAL, ASN_OCTET_STRING, 0, "john"] # the string "john" |
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193 | [ASN_UNIVERSAL, ASN_OID, 0, "1.3.6.133"] # some OID |
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194 | [ASN_UNIVERSAL, ASN_SEQUENCE, 1, [ [ASN_UNIVERSAL... # a sequence |
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195 | |
113 | To avoid non-descriptive hardcoded array index numbers, this module |
196 | To avoid non-descriptive hardcoded array index numbers, this module |
114 | defines symbolic constants to access these members: C<BER_CLASS>, |
197 | defines symbolic constants to access these members: C<BER_CLASS>, |
115 | C<BER_TAG>, C<BER_CONSTRUCTED> and C<BER_DATA>. |
198 | C<BER_TAG>, C<BER_CONSTRUCTED> and C<BER_DATA>. |
116 | |
199 | |
117 | Also, the first three members are integers with a little caveat: for |
200 | Also, the first three members are integers with a little caveat: for |
… | |
… | |
124 | # the following is NOT legal: |
207 | # the following is NOT legal: |
125 | $ber->[BER_CLASS] = ASN_PRIVATE; # ERROR, CLASS/TAG/CONSTRUCTED are READ ONLY(!) |
208 | $ber->[BER_CLASS] = ASN_PRIVATE; # ERROR, CLASS/TAG/CONSTRUCTED are READ ONLY(!) |
126 | |
209 | |
127 | # but all of the following are fine: |
210 | # but all of the following are fine: |
128 | $ber->[BER_DATA] = "string"; |
211 | $ber->[BER_DATA] = "string"; |
129 | $ber->[BER_DATA] = [ASN_UNIVERSAL, ASN_INTEGER32, 0, 123]; |
212 | $ber->[BER_DATA] = [ASN_UNIVERSAL, ASN_INTEGER, 0, 123]; |
130 | @$ber = (ASN_APPLICATION, SNMP_TIMETICKS, 0, 1000); |
213 | @$ber = (ASN_APPLICATION, SNMP_TIMETICKS, 0, 1000); |
131 | |
214 | |
132 | I<CLASS> is something like a namespace for I<TAG>s - there is the |
215 | I<CLASS> is something like a namespace for I<TAG>s - there is the |
133 | C<ASN_UNIVERSAL> namespace which defines tags common to all ASN.1 |
216 | C<ASN_UNIVERSAL> namespace which defines tags common to all ASN.1 |
134 | implementations, the C<ASN_APPLICATION> namespace which defines tags for |
217 | implementations, the C<ASN_APPLICATION> namespace which defines tags for |
135 | specific applications (for example, the SNMP C<Unsigned32> type is in this |
218 | specific applications (for example, the SNMP C<Unsigned32> type is in this |
136 | namespace), a special-purpose context namespace (C<ASN_CONTEXT>, used e.g. |
219 | namespace), a special-purpose context namespace (C<ASN_CONTEXT>, used e.g. |
137 | for C<CHOICE>) and a private namespace (C<ASN_PRIVATE>). |
220 | for C<CHOICE>) and a private namespace (C<ASN_PRIVATE>). |
138 | |
221 | |
139 | The meaning of the I<TAG> depends on the namespace, and defines a |
222 | The meaning of the I<TAG> depends on the namespace, and defines a |
140 | (partial) interpretation of the data value. For example, right now, SNMP |
223 | (partial) interpretation of the data value. For example, SNMP defines |
141 | application namespace knowledge ix hardcoded into this module, so it |
224 | extra tags in the C<ASN_APPLICATION> namespace, and to take full advantage |
142 | knows that SNMP C<Unsigned32> values need to be decoded into actual perl |
225 | of these, you need to tell this module how to handle those via profiles. |
143 | integers. |
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144 | |
226 | |
145 | The most common tags in the C<ASN_UNIVERSAL> namespace are |
227 | The most common tags in the C<ASN_UNIVERSAL> namespace are |
146 | C<ASN_INTEGER32>, C<ASN_BIT_STRING>, C<ASN_NULL>, C<ASN_OCTET_STRING>, |
228 | C<ASN_INTEGER>, C<ASN_BIT_STRING>, C<ASN_NULL>, C<ASN_OCTET_STRING>, |
147 | C<ASN_OBJECT_IDENTIFIER>, C<ASN_SEQUENCE>, C<ASN_SET> and |
229 | C<ASN_OBJECT_IDENTIFIER>, C<ASN_SEQUENCE>, C<ASN_SET> and |
148 | C<ASN_IA5_STRING>. |
230 | C<ASN_IA5_STRING>. |
149 | |
231 | |
150 | The most common tags in SNMP's C<ASN_APPLICATION> namespace |
232 | The most common tags in SNMP's C<ASN_APPLICATION> namespace are |
151 | are C<SNMP_IPADDRESS>, C<SNMP_COUNTER32>, C<SNMP_UNSIGNED32>, |
233 | C<SNMP_COUNTER32>, C<SNMP_UNSIGNED32>, C<SNMP_TIMETICKS> and |
152 | C<SNMP_TIMETICKS>, C<SNMP_OPAQUE> and C<SNMP_COUNTER64>. |
234 | C<SNMP_COUNTER64>. |
153 | |
235 | |
154 | The I<CONSTRUCTED> flag is really just a boolean - if it is false, the |
236 | The I<CONSTRUCTED> flag is really just a boolean - if it is false, |
155 | the value is "primitive" and contains no subvalues, kind of like a |
237 | the value is "primitive" and contains no subvalues, kind of like a |
156 | non-reference perl scalar. IF it is true, then the value is "constructed" |
238 | non-reference perl scalar. If it is true, then the value is "constructed" |
157 | which just means it contains a list of subvalues which this module will |
239 | which just means it contains a list of subvalues which this module will |
158 | en-/decode as BER tuples themselves. |
240 | en-/decode as BER tuples themselves. |
159 | |
241 | |
160 | The I<DATA> value is either a reference to an array of further tuples (if |
242 | The I<DATA> value is either a reference to an array of further tuples (if |
161 | the value is I<CONSTRUCTED>), some decoded representation of the value, |
243 | the value is I<CONSTRUCTED>), some decoded representation of the value, |
… | |
… | |
170 | |
252 | |
171 | =head2 DECODING AND ENCODING |
253 | =head2 DECODING AND ENCODING |
172 | |
254 | |
173 | =over |
255 | =over |
174 | |
256 | |
175 | =item $tuple = ber_decoded $bindata |
257 | =item $tuple = ber_decoded $bindata[, $profile] |
176 | |
258 | |
177 | Decodes binary BER data in C<$bindata> and returns the resulting BER |
259 | Decodes binary BER data in C<$bindata> and returns the resulting BER |
178 | tuple. Croaks on any decoding error, so the returned C<$tuple> is always |
260 | tuple. Croaks on any decoding error, so the returned C<$tuple> is always |
179 | valid. |
261 | valid. |
180 | |
262 | |
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263 | How tags are interpreted is defined by the second argument, which must |
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264 | be a C<Convert::BER::XS::Profile> object. If it is missing, the default |
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265 | profile will be used (C<$Convert::BER::XS::DEFAULT_PROFILE>). |
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266 | |
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267 | In addition to rolling your own, this module provides a |
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268 | C<$Convert::BER::XS::SNMP_PROFILE> that knows about the additional SNMP |
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269 | types. |
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270 | |
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271 | Example: decode a BER blob using the default profile - SNMP values will be |
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272 | decided as raw strings. |
|
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273 | |
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274 | $tuple = ber_decode $data; |
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275 | |
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276 | Example: as above, but use the provided SNMP profile. |
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277 | |
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278 | $tuple = ber_encode $data, $Convert::BER::XS::SNMP_PROFILE; |
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279 | |
181 | =item $bindata = ber_encode $tuple |
280 | =item $bindata = ber_encode $tuple[, $profile] |
182 | |
281 | |
183 | Encodes the BER tuple into a BER/DER data structure. |
282 | Encodes the BER tuple into a BER/DER data structure. AS with |
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283 | Cyber_decode>, an optional profile can be given. |
184 | |
284 | |
185 | =back |
285 | =back |
186 | |
286 | |
187 | =head2 HELPER FUNCTIONS |
287 | =head2 HELPER FUNCTIONS |
188 | |
288 | |
189 | Working with a 4-tuple for every value can be annoying. Or, rather, I<is> |
289 | Working with a 4-tuple for every value can be annoying. Or, rather, I<is> |
190 | annoying. To reduce this a bit, this module defines a number of helper |
290 | annoying. To reduce this a bit, this module defines a number of helper |
191 | functions, both to match BER tuples and to conmstruct BER tuples: |
291 | functions, both to match BER tuples and to construct BER tuples: |
192 | |
292 | |
193 | =head3 MATCH HELPERS |
293 | =head3 MATCH HELPERS |
194 | |
294 | |
195 | Thse functions accept a BER tuple as first argument and either paertially |
295 | These functions accept a BER tuple as first argument and either partially |
196 | or fully match it. They often come in two forms, one which exactly matches |
296 | or fully match it. They often come in two forms, one which exactly matches |
197 | a value, and one which only matches the type and returns the value. |
297 | a value, and one which only matches the type and returns the value. |
198 | |
298 | |
199 | They do check whether valid tuples are passed in and croak otherwise. As |
299 | They do check whether valid tuples are passed in and croak otherwise. As |
200 | a ease-of-use exception, they usually also accept C<undef> instead of a |
300 | a ease-of-use exception, they usually also accept C<undef> instead of a |
201 | tuple reference. in which case they silently fail to match. |
301 | tuple reference, in which case they silently fail to match. |
202 | |
302 | |
203 | =over |
303 | =over |
204 | |
304 | |
205 | =item $bool = ber_is $tuple, $class, $tag, $constructed, $data |
305 | =item $bool = ber_is $tuple, $class, $tag, $constructed, $data |
206 | |
306 | |
207 | This takes a BER C<$tuple> and matches its elements agains the privded |
307 | This takes a BER C<$tuple> and matches its elements against the provided |
208 | values, all of which are optional - values that are either missing or |
308 | values, all of which are optional - values that are either missing or |
209 | C<undef> will be ignored, the others will be matched exactly (e.g. as if |
309 | C<undef> will be ignored, the others will be matched exactly (e.g. as if |
210 | you used C<==> or C<eq> (for C<$data>)). |
310 | you used C<==> or C<eq> (for C<$data>)). |
211 | |
311 | |
212 | Some examples: |
312 | Some examples: |
… | |
… | |
215 | orf die "tuple is not an ASN SEQUENCE"; |
315 | orf die "tuple is not an ASN SEQUENCE"; |
216 | |
316 | |
217 | ber_is $tuple, ASN_UNIVERSAL, ASN_NULL |
317 | ber_is $tuple, ASN_UNIVERSAL, ASN_NULL |
218 | or die "tuple is not an ASN NULL value"; |
318 | or die "tuple is not an ASN NULL value"; |
219 | |
319 | |
220 | ber_is $tuple, ASN_UNIVERSAL, ASN_INTEGER32, 0, 50 |
320 | ber_is $tuple, ASN_UNIVERSAL, ASN_INTEGER, 0, 50 |
221 | or die "BER integer must be 50"; |
321 | or die "BER integer must be 50"; |
222 | |
322 | |
223 | =item $seq = ber_is_seq $tuple |
323 | =item $seq = ber_is_seq $tuple |
224 | |
324 | |
225 | Returns the sequence members (the array of subvalues) if the C<$tuple> is |
325 | Returns the sequence members (the array of subvalues) if the C<$tuple> is |
… | |
… | |
232 | my $snmp = ber_is_seq $ber |
332 | my $snmp = ber_is_seq $ber |
233 | or die "SNMP packet invalid: does not start with SEQUENCE"; |
333 | or die "SNMP packet invalid: does not start with SEQUENCE"; |
234 | |
334 | |
235 | # now we know $snmp is a sequence, so decode the SNMP version |
335 | # now we know $snmp is a sequence, so decode the SNMP version |
236 | |
336 | |
237 | my $version = ber_is_i32 $snmp->[0] |
337 | my $version = ber_is_int $snmp->[0] |
238 | or die "SNMP packet invalid: does not start with version number"; |
338 | or die "SNMP packet invalid: does not start with version number"; |
239 | |
339 | |
240 | =item $bool = ber_is_i32 $tuple, $i32 |
340 | =item $bool = ber_is_int $tuple, $int |
241 | |
341 | |
242 | Returns a true value if the C<$tuple> represents an ASN INTEGER32 with |
342 | Returns a true value if the C<$tuple> represents an ASN INTEGER with |
243 | the value C<$i32>. |
343 | the value C<$int>. |
244 | |
344 | |
245 | =item $i32 = ber_is_i32 $tuple |
345 | =item $int = ber_is_int $tuple |
246 | |
346 | |
247 | Returns true (and extracts the integer value) if the C<$tuple> is an ASN |
347 | Returns true (and extracts the integer value) if the C<$tuple> is an |
248 | INTEGER32. For C<0>, this function returns a special value that is 0 but |
348 | C<ASN_INTEGER>. For C<0>, this function returns a special value that is 0 |
249 | true. |
349 | but true. |
250 | |
350 | |
251 | =item $bool = ber_is_oid $tuple, $oid_string |
351 | =item $bool = ber_is_oid $tuple, $oid_string |
252 | |
352 | |
253 | Returns true if the C<$tuple> represents an ASN_OBJECT_IDENTIFIER |
353 | Returns true if the C<$tuple> represents an ASN_OBJECT_IDENTIFIER |
254 | that exactly matches C<$oid_string>. Example: |
354 | that exactly matches C<$oid_string>. Example: |
… | |
… | |
265 | |
365 | |
266 | =head3 CONSTRUCTION HELPERS |
366 | =head3 CONSTRUCTION HELPERS |
267 | |
367 | |
268 | =over |
368 | =over |
269 | |
369 | |
270 | =item $tuple = ber_i32 $value |
370 | =item $tuple = ber_int $value |
271 | |
371 | |
272 | Constructs a new C<ASN_INTEGER32> tuple. |
372 | Constructs a new C<ASN_INTEGER> tuple. |
273 | |
373 | |
274 | =back |
374 | =back |
275 | |
375 | |
276 | =head2 RELATIONSHIP TO L<Convert::BER> and L<Convert::ASN1> |
376 | =head2 RELATIONSHIP TO L<Convert::BER> and L<Convert::ASN1> |
277 | |
377 | |
… | |
… | |
287 | use common::sense; |
387 | use common::sense; |
288 | |
388 | |
289 | use XSLoader (); |
389 | use XSLoader (); |
290 | use Exporter qw(import); |
390 | use Exporter qw(import); |
291 | |
391 | |
292 | our $VERSION = 0.2; |
392 | our $VERSION; |
293 | |
393 | |
|
|
394 | BEGIN { |
|
|
395 | $VERSION = 0.8; |
294 | XSLoader::load __PACKAGE__, $VERSION; |
396 | XSLoader::load __PACKAGE__, $VERSION; |
|
|
397 | } |
295 | |
398 | |
296 | our %EXPORT_TAGS = ( |
399 | our %EXPORT_TAGS = ( |
297 | const => [qw( |
400 | const_index => [qw( |
298 | BER_CLASS BER_TAG BER_CONSTRUCTED BER_DATA |
401 | BER_CLASS BER_TAG BER_CONSTRUCTED BER_DATA |
299 | |
402 | )], |
|
|
403 | const_asn => [qw( |
300 | ASN_BOOLEAN ASN_INTEGER32 ASN_BIT_STRING ASN_OCTET_STRING ASN_NULL ASN_OBJECT_IDENTIFIER ASN_TAG_BER ASN_TAG_MASK |
404 | ASN_BOOLEAN ASN_INTEGER ASN_BIT_STRING ASN_OCTET_STRING ASN_NULL ASN_OBJECT_IDENTIFIER |
301 | ASN_CONSTRUCTED ASN_UNIVERSAL ASN_APPLICATION ASN_CONTEXT ASN_PRIVATE ASN_CLASS_MASK ASN_CLASS_SHIFT |
405 | ASN_OBJECT_DESCRIPTOR ASN_OID ASN_EXTERNAL ASN_REAL ASN_SEQUENCE ASN_ENUMERATED |
302 | ASN_SEQUENCE |
406 | ASN_EMBEDDED_PDV ASN_UTF8_STRING ASN_RELATIVE_OID ASN_SET ASN_NUMERIC_STRING |
303 | |
407 | ASN_PRINTABLE_STRING ASN_TELETEX_STRING ASN_T61_STRING ASN_VIDEOTEX_STRING ASN_IA5_STRING |
|
|
408 | ASN_ASCII_STRING ASN_UTC_TIME ASN_GENERALIZED_TIME ASN_GRAPHIC_STRING ASN_VISIBLE_STRING |
|
|
409 | ASN_ISO646_STRING ASN_GENERAL_STRING ASN_UNIVERSAL_STRING ASN_CHARACTER_STRING ASN_BMP_STRING |
|
|
410 | |
|
|
411 | ASN_UNIVERSAL ASN_APPLICATION ASN_CONTEXT ASN_PRIVATE |
|
|
412 | )], |
|
|
413 | const_ber_type => [qw( |
|
|
414 | BER_TYPE_BYTES BER_TYPE_UTF8 BER_TYPE_UCS2 BER_TYPE_UCS4 BER_TYPE_INT |
|
|
415 | BER_TYPE_OID BER_TYPE_RELOID BER_TYPE_NULL BER_TYPE_BOOL BER_TYPE_REAL |
|
|
416 | BER_TYPE_IPADDRESS BER_TYPE_CROAK |
|
|
417 | )], |
|
|
418 | const_snmp => [qw( |
304 | SNMP_IPADDRESS SNMP_COUNTER32 SNMP_UNSIGNED32 SNMP_TIMETICKS SNMP_OPAQUE SNMP_COUNTER64 |
419 | SNMP_IPADDRESS SNMP_COUNTER32 SNMP_UNSIGNED32 SNMP_TIMETICKS SNMP_OPAQUE SNMP_COUNTER64 |
305 | )], |
420 | )], |
|
|
421 | decode => [qw( |
|
|
422 | ber_decode |
|
|
423 | ber_is ber_is_seq ber_is_int ber_is_oid |
|
|
424 | )], |
306 | encode => [qw( |
425 | encode => [qw( |
307 | ber_decode |
|
|
308 | ber_is ber_is_seq ber_is_i32 ber_is_oid |
|
|
309 | )], |
|
|
310 | decode => [qw( |
|
|
311 | ber_encode |
426 | ber_encode |
|
|
427 | ber_int |
312 | )], |
428 | )], |
313 | ); |
429 | ); |
314 | |
430 | |
315 | our @EXPORT_OK = map @$_, values %EXPORT_TAGS; |
431 | our @EXPORT_OK = map @$_, values %EXPORT_TAGS; |
316 | |
432 | |
317 | $EXPORT_TAGS{all} = \@EXPORT_OK; |
433 | $EXPORT_TAGS{all} = \@EXPORT_OK; |
|
|
434 | $EXPORT_TAGS{const} = [map @{ $EXPORT_TAGS{$_} }, qw(const_index const_asn)]; |
|
|
435 | use Data::Dump; ddx \%EXPORT_TAGS; |
|
|
436 | |
|
|
437 | =head1 PROFILES |
|
|
438 | |
|
|
439 | While any BER data can be correctly encoded and decoded out of the box, it |
|
|
440 | can be inconvenient to have to manually decode some values into a "better" |
|
|
441 | format: for instance, SNMP TimeTicks values are decoded into the raw octet |
|
|
442 | strings of their BER representation, which is quite hard to decode. With |
|
|
443 | profiles, you can change which class/tag combinations map to which decoder |
|
|
444 | function inside C<ber_decode> (and of course also which encoder functions |
|
|
445 | are used in C<ber_encode>). |
|
|
446 | |
|
|
447 | This works by mapping specific class/tag combinations to an internal "ber |
|
|
448 | type". |
|
|
449 | |
|
|
450 | The default profile supports the standard ASN.1 types, but no |
|
|
451 | application-specific ones. This means that class/tag combinations not in |
|
|
452 | the base set of ASN.1 are decoded into their raw octet strings. |
|
|
453 | |
|
|
454 | C<Convert::BER::XS> defines two profile variables you can use out of the box: |
|
|
455 | |
|
|
456 | =over |
|
|
457 | |
|
|
458 | =item C<$Convert::BER::XS::DEFAULT_PROFILE> |
|
|
459 | |
|
|
460 | This is the default profile, i.e. the profile that is used when no |
|
|
461 | profile is specified for de-/encoding. |
|
|
462 | |
|
|
463 | You can modify it, but remember that this modifies the defaults for all |
|
|
464 | callers that rely on the default profile. |
|
|
465 | |
|
|
466 | =item C<$Convert::BER::XS::SNMP_PROFILE> |
|
|
467 | |
|
|
468 | A profile with mappings for SNMP-specific application tags added. This is |
|
|
469 | useful when de-/encoding SNMP data. |
|
|
470 | |
|
|
471 | Example: |
|
|
472 | |
|
|
473 | $ber = ber_decode $data, $Convert::BER::XS::SNMP_PROFILE; |
|
|
474 | |
|
|
475 | =back |
|
|
476 | |
|
|
477 | =head2 The Convert::BER::XS::Profile class |
|
|
478 | |
|
|
479 | =over |
|
|
480 | |
|
|
481 | =item $profile = new Convert::BER::XS::Profile |
|
|
482 | |
|
|
483 | Create a new profile. The profile will be identical to the default |
|
|
484 | profile. |
|
|
485 | |
|
|
486 | =item $profile->set ($class, $tag, $type) |
|
|
487 | |
|
|
488 | Sets the mapping for the given C<$class>/C<$tag> combination to C<$type>, |
|
|
489 | which must be one of the C<BER_TYPE_*> constants. |
|
|
490 | |
|
|
491 | Note that currently, the mapping is stored in a flat array, so large |
|
|
492 | values of C<$tag> will consume large amounts of memory. |
|
|
493 | |
|
|
494 | Example: |
|
|
495 | |
|
|
496 | $profile = new Convert::BER::XS::Profile; |
|
|
497 | $profile->set (ASN_APPLICATION, SNMP_COUNTER32, BER_TYPE_INT); |
|
|
498 | $ber = ber_decode $data, $profile; |
|
|
499 | |
|
|
500 | =item $type = $profile->get ($class, $tag) |
|
|
501 | |
|
|
502 | Returns the BER type mapped to the given C<$class>/C<$tag> combination. |
|
|
503 | |
|
|
504 | =back |
|
|
505 | |
|
|
506 | =head2 BER TYPES |
|
|
507 | |
|
|
508 | This lists the predefined BER types - you can map any C<CLASS>/C<TAG> |
|
|
509 | combination to any C<BER_TYPE_*>. |
|
|
510 | |
|
|
511 | =over |
|
|
512 | |
|
|
513 | =item C<BER_TYPE_BYTES> |
|
|
514 | |
|
|
515 | The raw octets of the value. This is the default type for unknown tags and |
|
|
516 | de-/encodes the value as if it were an octet string, i.e. by copying the |
|
|
517 | raw bytes. |
|
|
518 | |
|
|
519 | =item C<BER_TYPE_UTF8> |
|
|
520 | |
|
|
521 | Like C<BER_TYPE_BYTES>, but decodes the value as if it were a UTF-8 string |
|
|
522 | (without validation!) and encodes a perl unicode string into a UTF-8 BER |
|
|
523 | string. |
|
|
524 | |
|
|
525 | =item C<BER_TYPE_UCS2> |
|
|
526 | |
|
|
527 | Similar to C<BER_TYPE_UTF8>, but treats the BER value as UCS-2 encoded |
|
|
528 | string. |
|
|
529 | |
|
|
530 | =item C<BER_TYPE_UCS4> |
|
|
531 | |
|
|
532 | Similar to C<BER_TYPE_UTF8>, but treats the BER value as UCS-4 encoded |
|
|
533 | string. |
|
|
534 | |
|
|
535 | =item C<BER_TYPE_INT> |
|
|
536 | |
|
|
537 | Encodes and decodes a BER integer value to a perl integer scalar. This |
|
|
538 | should correctly handle 64 bit signed and unsigned values. |
|
|
539 | |
|
|
540 | =item C<BER_TYPE_OID> |
|
|
541 | |
|
|
542 | Encodes and decodes an OBJECT IDENTIFIER into dotted form without leading |
|
|
543 | dot, e.g. C<1.3.6.1.213>. |
|
|
544 | |
|
|
545 | =item C<BER_TYPE_RELOID> |
|
|
546 | |
|
|
547 | Same as C<BER_TYPE_OID> but uses relative object identifier |
|
|
548 | encoding: ASN.1 has this hack of encoding the first two OID components |
|
|
549 | into a single integer in a weird attempt to save an insignificant amount |
|
|
550 | of space in an otherwise wasteful encoding, and relative OIDs are |
|
|
551 | basically OIDs without this hack. The practical difference is that the |
|
|
552 | second component of an OID can only have the values 1..40, while relative |
|
|
553 | OIDs do not have this restriction. |
|
|
554 | |
|
|
555 | =item C<BER_TYPE_NULL> |
|
|
556 | |
|
|
557 | Decodes an C<ASN_NULL> value into C<undef>, and always encodes a |
|
|
558 | C<ASN_NULL> type, regardless of the perl value. |
|
|
559 | |
|
|
560 | =item C<BER_TYPE_BOOL> |
|
|
561 | |
|
|
562 | Decodes an C<ASN_BOOLEAN> value into C<0> or C<1>, and encodes a perl |
|
|
563 | boolean value into an C<ASN_BOOLEAN>. |
|
|
564 | |
|
|
565 | =item C<BER_TYPE_REAL> |
|
|
566 | |
|
|
567 | Decodes/encodes a BER real value. NOT IMPLEMENTED. |
|
|
568 | |
|
|
569 | =item C<BER_TYPE_IPADDRESS> |
|
|
570 | |
|
|
571 | Decodes/encodes a four byte string into an IPv4 dotted-quad address string |
|
|
572 | in Perl. Given the obsolete nature of this type, this is a low-effort |
|
|
573 | implementation that simply uses C<sprintf> and C<sscanf>-style conversion, |
|
|
574 | so it won't handle all string forms supported by C<inet_aton> for example. |
|
|
575 | |
|
|
576 | =item C<BER_TYPE_CROAK> |
|
|
577 | |
|
|
578 | Always croaks when encountered during encoding or decoding - the |
|
|
579 | default behaviour when encountering an unknown type is to treat it as |
|
|
580 | C<BER_TYPE_BYTES>. When you don't want that but instead prefer a hard |
|
|
581 | error for some types, then C<BER_TYPE_CROAK> is for you. |
|
|
582 | |
|
|
583 | =back |
|
|
584 | |
|
|
585 | =cut |
|
|
586 | |
|
|
587 | our $DEFAULT_PROFILE = new Convert::BER::XS::Profile; |
|
|
588 | our $SNMP_PROFILE = new Convert::BER::XS::Profile; |
|
|
589 | |
|
|
590 | # additional SNMP application types |
|
|
591 | $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_IPADDRESS , BER_TYPE_IPADDRESS); |
|
|
592 | $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_COUNTER32 , BER_TYPE_INT); |
|
|
593 | $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_UNSIGNED32, BER_TYPE_INT); |
|
|
594 | $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_TIMETICKS , BER_TYPE_INT); |
|
|
595 | $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_OPAQUE , BER_TYPE_IPADDRESS); |
|
|
596 | $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_COUNTER64 , BER_TYPE_INT); |
|
|
597 | |
|
|
598 | $DEFAULT_PROFILE->_set_default; |
318 | |
599 | |
319 | 1; |
600 | 1; |
320 | |
601 | |
321 | =head2 BUGS / SHORTCOMINGs |
602 | =head2 LIMITATIONS/NOTES |
322 | |
603 | |
323 | This module does have a number of SNMPisms hardcoded, such as the SNMP |
604 | This module can only en-/decode 64 bit signed and unsigned integers, and |
324 | tags for Unsigned32 and so on. More configurability is needed, and, if |
605 | only when your perl supports those. |
325 | ever implemented, will come in a form similar to how L<JSON::XS> and |
606 | |
326 | L<CBOR::XS> respresent things, namely with an object-oriented interface. |
607 | This module does not generally care about ranges, i.e. it will happily |
|
|
608 | de-/encode 64 bit integers into an C<ASN_INTEGER> value, or a negative |
|
|
609 | number into an C<SNMP_COUNTER64>. |
|
|
610 | |
|
|
611 | OBJECT IDENTIFIEERs cannot have unlimited length, although the limit is |
|
|
612 | much larger than e.g. the one imposed by SNMP or other protocols,a nd is |
|
|
613 | about 4kB. |
|
|
614 | |
|
|
615 | REAL values are not supported and will currently croak. |
|
|
616 | |
|
|
617 | This module has undergone little to no testing so far. |
|
|
618 | |
|
|
619 | =head2 ITHREADS SUPPORT |
|
|
620 | |
|
|
621 | This module is unlikely to work when the (officially discouraged) ithreads |
|
|
622 | are in use. |
327 | |
623 | |
328 | =head1 AUTHOR |
624 | =head1 AUTHOR |
329 | |
625 | |
330 | Marc Lehmann <schmorp@schmorp.de> |
626 | Marc Lehmann <schmorp@schmorp.de> |
331 | http://software.schmorp.de/pkg/Convert-BER-XS |
627 | http://software.schmorp.de/pkg/Convert-BER-XS |