1 | =head1 NAME |
1 | =head1 NAME |
2 | |
2 | |
3 | Convert::BER::XS - I<very> low level BER decoding |
3 | Convert::BER::XS - I<very> low level BER en-/decoding |
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 v1/v2c Message"; |
10 | or die "unable to decode SNMP message"; |
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11 | |
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12 | # The above results in a data structure consisting of |
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13 | # (class, tag, # constructed, data) |
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14 | # tuples. Below is such a message, SNMPv1 trap |
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15 | # with a Cisco mac change notification. |
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16 | # Did you know that Cisco is in the news almost |
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17 | # every week because of some backdoor password |
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18 | # or other extremely stupid security bug? |
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19 | |
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20 | [ ASN_UNIVERSAL, ASN_SEQUENCE, 1, |
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21 | [ |
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22 | [ ASN_UNIVERSAL, ASN_INTEGER32, 0, 0 ], # snmp version 1 |
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23 | [ ASN_UNIVERSAL, 4, 0, "public" ], # community |
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24 | [ ASN_CONTEXT, 4, 1, # CHOICE, constructed - trap PDU |
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25 | [ |
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26 | [ ASN_UNIVERSAL, ASN_OBJECT_IDENTIFIER, 0, "1.3.6.1.4.1.9.9.215.2" ], # enterprise oid |
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27 | [ ASN_APPLICATION, SNMP_IPADDRESS, 0, "10.0.0.1" ], # SNMP IpAddress |
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28 | [ ASN_UNIVERSAL, ASN_INTEGER32, 0, 6 ], # generic trap |
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29 | [ ASN_UNIVERSAL, ASN_INTEGER32, 0, 1 ], # specific trap |
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30 | [ ASN_APPLICATION, SNMP_TIMETICKS, 0, 1817903850 ], # SNMP TimeTicks |
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31 | [ ASN_UNIVERSAL, ASN_SEQUENCE, 1, # the varbindlist |
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32 | [ |
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33 | [ ASN_UNIVERSAL, ASN_SEQUENCE, 1, # a single varbind, "key value" pair |
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34 | [ |
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35 | [ ASN_UNIVERSAL, ASN_OBJECT_IDENTIFIER, 0, "1.3.6.1.4.1.9.9.215.1.1.8.1.2.1" ], |
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36 | [ ASN_UNIVERSAL, ASN_OCTET_STRING, 0, "...data..." # the value |
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37 | ] |
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38 | ] |
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39 | ], |
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40 | ... |
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41 | |
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42 | # let's decode it a bit with some helper functions |
11 | |
43 | |
12 | my $msg = ber_is_seq $ber |
44 | my $msg = ber_is_seq $ber |
13 | or die "SNMP message does not start with a sequence"; |
45 | or die "SNMP message does not start with a sequence"; |
14 | |
46 | |
15 | ber_is $msg->[0], ASN_UNIVERSAL, ASN_INTEGER32, 0 |
47 | ber_is $msg->[0], ASN_UNIVERSAL, ASN_INTEGER32, 0 |
16 | or die "SNMP message does not start with snmp version\n"; |
48 | or die "SNMP message does not start with snmp version\n"; |
17 | |
49 | |
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50 | # message is SNMP v1 or v2c? |
18 | if ($msg->[0][BER_DATA] == 0 || $msg->[0][BER_DATA] == 1) { |
51 | if ($msg->[0][BER_DATA] == 0 || $msg->[0][BER_DATA] == 1) { |
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52 | |
19 | # message is SNMP v1 or v2c |
53 | # message is v1 trap? |
20 | |
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21 | if (ber_is $msg->[2], ASN_CONTEXT, 4, 1) { |
54 | if (ber_is $msg->[2], ASN_CONTEXT, 4, 1) { |
22 | # message is v1 trap |
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23 | my $trap = $msg->[2][BER_DATA]; |
55 | my $trap = $msg->[2][BER_DATA]; |
24 | |
56 | |
25 | # check whether trap is a cisco mac notification mac changed message |
57 | # check whether trap is a cisco mac notification mac changed message |
26 | if ( |
58 | if ( |
27 | (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 |
28 | and (ber_is_i32 $trap->[2], 6) |
60 | and (ber_is_i32 $trap->[2], 6) |
29 | and (ber_is_i32 $trap->[3], 1) # mac changed msg |
61 | and (ber_is_i32 $trap->[3], 1) # mac changed msg |
30 | ) { |
62 | ) { |
31 | ... and so on |
63 | ... and so on |
32 | |
64 | |
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65 | # finally, let's encode it again and hope it results in the same bit pattern |
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66 | |
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67 | my $buf = ber_encode $ber, $Convert::BER::XS::SNMP_PROFILE; |
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68 | |
33 | =head1 DESCRIPTION |
69 | =head1 DESCRIPTION |
34 | |
70 | |
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71 | WARNING: Before release 1.0, the API is not considered stable in any way. |
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72 | |
35 | This module implements a I<very> low level BER/DER decoder, and in the |
73 | This module implements a I<very> low level BER/DER en-/decoder. |
36 | future, probably also an encoder (tell me if you want an encoder, this |
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37 | might speed up the process of getting one). |
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38 | |
74 | |
39 | 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 |
40 | level of user-friendlyness. |
76 | level of user-friendlyness. |
41 | |
77 | |
42 | Currently, not much is documented, as this is an initial release to |
78 | =head2 EXPORT TAGS AND CONSTANTS |
43 | 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 eyesigh with extreemly 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. Rcommended 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 stricly 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>, reespectively - |
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110 | exactly thw two topmost bits from the identifdier 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_INTEGER32 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_i32 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_i32 |
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152 | |
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153 | =back |
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154 | |
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155 | =head2 ASN.1/BER/DER/... BASICS |
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156 | |
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157 | ASN.1 is a strange language that can be used to describe protocols and |
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158 | data structures. It supports various mappings to JSON, XML, but most |
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159 | importantly, to a various binary encodings such as BER, that is the topic |
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160 | of this module, and is used in SNMP or LDAP for example. |
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161 | |
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162 | While ASN.1 defines a schema that is useful to interpret encoded data, |
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163 | the BER encoding is actually somewhat self-describing: you might not know |
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164 | whether something is a string or a number or a sequence or something else, |
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165 | but you can nevertheless decode the overall structure, even if you end up |
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166 | with just a binary blob for the actual value. |
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167 | |
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168 | This works because BER values are tagged with a type and a namespace, |
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169 | and also have a flag that says whether a value consists of subvalues (is |
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170 | "constructed") or not (is "primitive"). |
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171 | |
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172 | Tags are simple integers, and ASN.1 defines a somewhat weird assortment of |
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173 | those - for example, you have 32 bit signed integers and 16(!) different |
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174 | string types, but there is no unsigned32 type for example. Different |
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175 | applications work around this in different ways, for example, SNMP defines |
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176 | application-specific Gauge32, Counter32 and Unsigned32, which are mapped |
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177 | to two different tags: you can distinguish between Counter32 and the |
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178 | others, but not between Gause32 and Unsigned32, without the ASN.1 schema. |
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179 | |
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180 | Ugh. |
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181 | |
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182 | =head2 DECODED BER REPRESENTATION |
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183 | |
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184 | This module represents every BER value as a 4-element tuple (actually an |
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185 | array-reference): |
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186 | |
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187 | [CLASS, TAG, CONSTRUCTED, DATA] |
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188 | |
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189 | To avoid non-descriptive hardcoded array index numbers, this module |
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190 | defines symbolic constants to access these members: C<BER_CLASS>, |
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191 | C<BER_TAG>, C<BER_CONSTRUCTED> and C<BER_DATA>. |
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192 | |
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193 | Also, the first three members are integers with a little caveat: for |
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194 | performance reasons, these are readonly and shared, so you must not modify |
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195 | them (increment, assign to them etc.) in any way. You may modify the |
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196 | I<DATA> member, and you may re-assign the array itself, e.g.: |
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197 | |
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198 | $ber = ber_decode $binbuf; |
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199 | |
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200 | # the following is NOT legal: |
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201 | $ber->[BER_CLASS] = ASN_PRIVATE; # ERROR, CLASS/TAG/CONSTRUCTED are READ ONLY(!) |
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202 | |
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203 | # but all of the following are fine: |
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204 | $ber->[BER_DATA] = "string"; |
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205 | $ber->[BER_DATA] = [ASN_UNIVERSAL, ASN_INTEGER32, 0, 123]; |
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206 | @$ber = (ASN_APPLICATION, SNMP_TIMETICKS, 0, 1000); |
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207 | |
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208 | I<CLASS> is something like a namespace for I<TAG>s - there is the |
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209 | C<ASN_UNIVERSAL> namespace which defines tags common to all ASN.1 |
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210 | implementations, the C<ASN_APPLICATION> namespace which defines tags for |
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211 | specific applications (for example, the SNMP C<Unsigned32> type is in this |
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212 | namespace), a special-purpose context namespace (C<ASN_CONTEXT>, used e.g. |
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213 | for C<CHOICE>) and a private namespace (C<ASN_PRIVATE>). |
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214 | |
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215 | The meaning of the I<TAG> depends on the namespace, and defines a |
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216 | (partial) interpretation of the data value. For example, right now, SNMP |
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217 | application namespace knowledge ix hardcoded into this module, so it |
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218 | knows that SNMP C<Unsigned32> values need to be decoded into actual perl |
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219 | integers. |
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220 | |
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221 | The most common tags in the C<ASN_UNIVERSAL> namespace are |
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222 | C<ASN_INTEGER32>, C<ASN_BIT_STRING>, C<ASN_NULL>, C<ASN_OCTET_STRING>, |
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223 | C<ASN_OBJECT_IDENTIFIER>, C<ASN_SEQUENCE>, C<ASN_SET> and |
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224 | C<ASN_IA5_STRING>. |
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225 | |
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226 | The most common tags in SNMP's C<ASN_APPLICATION> namespace |
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227 | are C<SNMP_IPADDRESS>, C<SNMP_COUNTER32>, C<SNMP_UNSIGNED32>, |
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228 | C<SNMP_TIMETICKS>, C<SNMP_OPAQUE> and C<SNMP_COUNTER64>. |
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229 | |
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230 | The I<CONSTRUCTED> flag is really just a boolean - if it is false, the |
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231 | the value is "primitive" and contains no subvalues, kind of like a |
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232 | non-reference perl scalar. IF it is true, then the value is "constructed" |
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233 | which just means it contains a list of subvalues which this module will |
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234 | en-/decode as BER tuples themselves. |
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235 | |
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236 | The I<DATA> value is either a reference to an array of further tuples (if |
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237 | the value is I<CONSTRUCTED>), some decoded representation of the value, |
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238 | if this module knows how to decode it (e.g. for the integer types above) |
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239 | or a binary string with the raw octets if this module doesn't know how to |
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240 | interpret the namespace/tag. |
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241 | |
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242 | Thus, you can always decode a BER data structure and at worst you get a |
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243 | string in place of some nice decoded value. |
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244 | |
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245 | See the SYNOPSIS for an example of such an encoded tuple representation. |
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246 | |
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247 | =head2 DECODING AND ENCODING |
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248 | |
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249 | =over |
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250 | |
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251 | =item $tuple = ber_decoded $bindata |
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252 | |
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253 | Decodes binary BER data in C<$bindata> and returns the resulting BER |
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254 | tuple. Croaks on any decoding error, so the returned C<$tuple> is always |
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255 | valid. |
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256 | |
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257 | =item $bindata = ber_encode $tuple |
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258 | |
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259 | Encodes the BER tuple into a BER/DER data structure. |
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260 | |
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261 | =back |
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262 | |
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263 | =head2 HELPER FUNCTIONS |
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264 | |
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265 | Working with a 4-tuple for every value can be annoying. Or, rather, I<is> |
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266 | annoying. To reduce this a bit, this module defines a number of helper |
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267 | functions, both to match BER tuples and to conmstruct BER tuples: |
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268 | |
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269 | =head3 MATCH HELPERS |
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270 | |
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271 | Thse functions accept a BER tuple as first argument and either paertially |
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272 | or fully match it. They often come in two forms, one which exactly matches |
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273 | a value, and one which only matches the type and returns the value. |
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274 | |
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275 | They do check whether valid tuples are passed in and croak otherwise. As |
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276 | a ease-of-use exception, they usually also accept C<undef> instead of a |
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277 | tuple reference. in which case they silently fail to match. |
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278 | |
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279 | =over |
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280 | |
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281 | =item $bool = ber_is $tuple, $class, $tag, $constructed, $data |
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282 | |
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283 | This takes a BER C<$tuple> and matches its elements agains the privded |
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284 | values, all of which are optional - values that are either missing or |
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285 | C<undef> will be ignored, the others will be matched exactly (e.g. as if |
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286 | you used C<==> or C<eq> (for C<$data>)). |
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287 | |
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288 | Some examples: |
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289 | |
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290 | ber_is $tuple, ASN_UNIVERSAL, ASN_SEQUENCE, 1 |
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291 | orf die "tuple is not an ASN SEQUENCE"; |
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292 | |
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293 | ber_is $tuple, ASN_UNIVERSAL, ASN_NULL |
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294 | or die "tuple is not an ASN NULL value"; |
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295 | |
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296 | ber_is $tuple, ASN_UNIVERSAL, ASN_INTEGER32, 0, 50 |
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297 | or die "BER integer must be 50"; |
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298 | |
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299 | =item $seq = ber_is_seq $tuple |
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300 | |
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301 | Returns the sequence members (the array of subvalues) if the C<$tuple> is |
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302 | an ASN SEQUENCE, i.e. the C<BER_DATA> member. If the C<$tuple> is not a |
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303 | sequence it returns C<undef>. For example, SNMP version 1/2c/3 packets all |
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304 | consist of an outer SEQUENCE value: |
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305 | |
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306 | my $ber = ber_decode $snmp_data; |
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307 | |
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308 | my $snmp = ber_is_seq $ber |
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309 | or die "SNMP packet invalid: does not start with SEQUENCE"; |
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310 | |
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311 | # now we know $snmp is a sequence, so decode the SNMP version |
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312 | |
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313 | my $version = ber_is_i32 $snmp->[0] |
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314 | or die "SNMP packet invalid: does not start with version number"; |
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315 | |
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316 | =item $bool = ber_is_i32 $tuple, $i32 |
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317 | |
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318 | Returns a true value if the C<$tuple> represents an ASN INTEGER32 with |
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319 | the value C<$i32>. |
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320 | |
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321 | =item $i32 = ber_is_i32 $tuple |
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322 | |
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323 | Returns true (and extracts the integer value) if the C<$tuple> is an ASN |
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324 | INTEGER32. For C<0>, this function returns a special value that is 0 but |
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325 | true. |
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326 | |
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327 | =item $bool = ber_is_oid $tuple, $oid_string |
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328 | |
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329 | Returns true if the C<$tuple> represents an ASN_OBJECT_IDENTIFIER |
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330 | that exactly matches C<$oid_string>. Example: |
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331 | |
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332 | ber_is_oid $tuple, "1.3.6.1.4" |
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333 | or die "oid must be 1.3.6.1.4"; |
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334 | |
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335 | =item $oid = ber_is_oid $tuple |
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336 | |
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337 | Returns true (and extracts the OID string) if the C<$tuple> is an ASN |
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338 | OBJECT IDENTIFIER. Otherwise, it returns C<undef>. |
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339 | |
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340 | =back |
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341 | |
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342 | =head3 CONSTRUCTION HELPERS |
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343 | |
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344 | =over |
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345 | |
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346 | =item $tuple = ber_i32 $value |
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347 | |
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348 | Constructs a new C<ASN_INTEGER32> tuple. |
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349 | |
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350 | =back |
44 | |
351 | |
45 | =head2 RELATIONSHIP TO L<Convert::BER> and L<Convert::ASN1> |
352 | =head2 RELATIONSHIP TO L<Convert::BER> and L<Convert::ASN1> |
46 | |
353 | |
47 | This module is I<not> the XS version of L<Convert::BER>, but a different |
354 | This module is I<not> the XS version of L<Convert::BER>, but a different |
48 | take at doing the same thing. I imagine this module would be a good base |
355 | take at doing the same thing. I imagine this module would be a good base |
49 | for speeding up either fo these, or write a similar module, or write your |
356 | for speeding up either of these, or write a similar module, or write your |
50 | own LDAP or SNMP module for example. |
357 | own LDAP or SNMP module for example. |
51 | |
358 | |
52 | =cut |
359 | =cut |
53 | |
360 | |
54 | package Convert::BER::XS; |
361 | package Convert::BER::XS; |
… | |
… | |
56 | use common::sense; |
363 | use common::sense; |
57 | |
364 | |
58 | use XSLoader (); |
365 | use XSLoader (); |
59 | use Exporter qw(import); |
366 | use Exporter qw(import); |
60 | |
367 | |
|
|
368 | our $VERSION; |
|
|
369 | |
|
|
370 | BEGIN { |
61 | our $VERSION = '0.0'; |
371 | $VERSION = 0.8; |
62 | |
|
|
63 | XSLoader::load __PACKAGE__, $VERSION; |
372 | XSLoader::load __PACKAGE__, $VERSION; |
|
|
373 | } |
64 | |
374 | |
65 | our %EXPORT_TAGS = ( |
375 | our %EXPORT_TAGS = ( |
66 | all => [qw( |
376 | const_index => [qw( |
|
|
377 | BER_CLASS BER_TAG BER_CONSTRUCTED BER_DATA |
|
|
378 | )], |
|
|
379 | const_asn => [qw( |
|
|
380 | ASN_BOOLEAN ASN_INTEGER32 ASN_BIT_STRING ASN_OCTET_STRING ASN_NULL ASN_OBJECT_IDENTIFIER |
|
|
381 | ASN_OBJECT_DESCRIPTOR ASN_OID ASN_EXTERNAL ASN_REAL ASN_SEQUENCE ASN_ENUMERATED |
|
|
382 | ASN_EMBEDDED_PDV ASN_UTF8_STRING ASN_RELATIVE_OID ASN_SET ASN_NUMERIC_STRING |
|
|
383 | ASN_PRINTABLE_STRING ASN_TELETEX_STRING ASN_T61_STRING ASN_VIDEOTEX_STRING ASN_IA5_STRING |
|
|
384 | ASN_ASCII_STRING ASN_UTC_TIME ASN_GENERALIZED_TIME ASN_GRAPHIC_STRING ASN_VISIBLE_STRING |
|
|
385 | ASN_ISO646_STRING ASN_GENERAL_STRING ASN_UNIVERSAL_STRING ASN_CHARACTER_STRING ASN_BMP_STRING |
|
|
386 | |
|
|
387 | ASN_UNIVERSAL ASN_APPLICATION ASN_CONTEXT ASN_PRIVATE |
|
|
388 | )], |
|
|
389 | const_ber_type => [qw( |
|
|
390 | BER_TYPE_BYTES BER_TYPE_UTF8 BER_TYPE_UCS2 BER_TYPE_UCS4 BER_TYPE_INT |
|
|
391 | BER_TYPE_OID BER_TYPE_RELOID BER_TYPE_NULL BER_TYPE_BOOL BER_TYPE_REAL |
|
|
392 | BER_TYPE_IPADDRESS BER_TYPE_CROAK |
|
|
393 | )], |
|
|
394 | const_snmp => [qw( |
|
|
395 | SNMP_IPADDRESS SNMP_COUNTER32 SNMP_UNSIGNED32 SNMP_TIMETICKS SNMP_OPAQUE SNMP_COUNTER64 |
|
|
396 | )], |
|
|
397 | decode => [qw( |
67 | ber_decode |
398 | ber_decode |
68 | ber_is ber_is_seq ber_is_i32 ber_is_oid |
399 | ber_is ber_is_seq ber_is_i32 ber_is_oid |
69 | BER_CLASS BER_TAG BER_CONSTRUCTED BER_DATA |
400 | )], |
70 | ASN_BOOLEAN ASN_INTEGER32 ASN_BIT_STRING ASN_OCTET_STRING ASN_NULL ASN_OBJECT_IDENTIFIER ASN_TAG_BER ASN_TAG_MASK |
401 | encode => [qw( |
71 | ASN_CONSTRUCTED ASN_UNIVERSAL ASN_APPLICATION ASN_CONTEXT ASN_PRIVATE ASN_CLASS_MASK ASN_CLASS_SHIFT |
402 | ber_encode |
72 | ASN_SEQUENCE ASN_IPADDRESS ASN_COUNTER32 ASN_UNSIGNED32 ASN_TIMETICKS ASN_OPAQUE ASN_COUNTER64 |
403 | ber_i32 |
73 | )], |
404 | )], |
74 | ); |
405 | ); |
75 | |
406 | |
76 | our @EXPORT_OK = map @$_, values %EXPORT_TAGS; |
407 | our @EXPORT_OK = map @$_, values %EXPORT_TAGS; |
77 | |
408 | |
|
|
409 | $EXPORT_TAGS{all} = \@EXPORT_OK; |
|
|
410 | $EXPORT_TAGS{const} = [map @{ $EXPORT_TAGS{$_} }, qw(const_index const_asn)]; |
|
|
411 | use Data::Dump; ddx \%EXPORT_TAGS; |
|
|
412 | |
|
|
413 | =head1 PROFILES |
|
|
414 | |
|
|
415 | While any BER data can be correctly encoded and decoded out of the box, it |
|
|
416 | can be inconvenient to have to manually decode some values into a "better" |
|
|
417 | format: for instance, SNMP TimeTicks values are decoded into the raw octet |
|
|
418 | strings of their BER representation, which is quite hard to decode. With |
|
|
419 | profiles, you can change which class/tag combinations map to which decoder |
|
|
420 | function inside C<ber_decode> (and of course also which encoder functions |
|
|
421 | are used in C<ber_encode>). |
|
|
422 | |
|
|
423 | This works by mapping specific class/tag combinations to an internal "ber |
|
|
424 | type". |
|
|
425 | |
|
|
426 | The default profile supports the standard ASN.1 types, but no |
|
|
427 | application-specific ones. This means that class/tag combinations not in |
|
|
428 | the base set of ASN.1 are decoded into their raw octet strings. |
|
|
429 | |
|
|
430 | C<Convert::BER::XS> defines two profile variables you can use out of the box: |
|
|
431 | |
|
|
432 | =over |
|
|
433 | |
|
|
434 | =item C<$Convert::BER::XS::DEFAULT_PROFILE> |
|
|
435 | |
|
|
436 | This is the default profile, i.e. the profile that is used when no |
|
|
437 | profile is specified for de-/encoding. |
|
|
438 | |
|
|
439 | You can modify it, but remember that this modifies the defaults for all |
|
|
440 | callers that rely on the default profile. |
|
|
441 | |
|
|
442 | =item C<$Convert::BER::XS::SNMP_PROFILE> |
|
|
443 | |
|
|
444 | A profile with mappings for SNMP-specific application tags added. This is |
|
|
445 | useful when de-/encoding SNMP data. |
|
|
446 | |
|
|
447 | Example: |
|
|
448 | |
|
|
449 | $ber = ber_decode $data, $Convert::BER::XS::SNMP_PROFILE; |
|
|
450 | |
|
|
451 | =back |
|
|
452 | |
|
|
453 | =head2 The Convert::BER::XS::Profile class |
|
|
454 | |
|
|
455 | =over |
|
|
456 | |
|
|
457 | =item $profile = new Convert::BER::XS::Profile |
|
|
458 | |
|
|
459 | Create a new profile. The profile will be identical to the default |
|
|
460 | profile. |
|
|
461 | |
|
|
462 | =item $profile->set ($class, $tag, $type) |
|
|
463 | |
|
|
464 | Sets the mapping for the given C<$class>/C<$tag> combination to C<$type>, |
|
|
465 | which must be one of the C<BER_TYPE_*> constants. |
|
|
466 | |
|
|
467 | Note that currently, the mapping is stored in a flat array, so large |
|
|
468 | values of C<$tag> will consume large amounts of memory. |
|
|
469 | |
|
|
470 | Example: |
|
|
471 | |
|
|
472 | $profile = new Convert::BER::XS::Profile; |
|
|
473 | $profile->set (ASN_APPLICATION, SNMP_COUNTER32, BER_TYPE_INT); |
|
|
474 | $ber = ber_decode $data, $profile; |
|
|
475 | |
|
|
476 | =item $type = $profile->get ($class, $tag) |
|
|
477 | |
|
|
478 | Returns the BER type mapped to the given C<$class>/C<$tag> combination. |
|
|
479 | |
|
|
480 | =back |
|
|
481 | |
|
|
482 | =head2 BER TYPES |
|
|
483 | |
|
|
484 | This lists the predefined BER types - you can map any C<CLASS>/C<TAG> |
|
|
485 | combination to any C<BER_TYPE_*>. |
|
|
486 | |
|
|
487 | =over |
|
|
488 | |
|
|
489 | =item C<BER_TYPE_BYTES> |
|
|
490 | |
|
|
491 | The raw octets of the value. This is the default type for unknown tags and |
|
|
492 | de-/encodes the value as if it were an octet string, i.e. by copying the |
|
|
493 | raw bytes. |
|
|
494 | |
|
|
495 | =item C<BER_TYPE_UTF8> |
|
|
496 | |
|
|
497 | Like C<BER_TYPE_BYTES>, but decodes the value as if it were a UTF-8 string |
|
|
498 | (without validation!) and encodes a perl unicode string into a UTF-8 BER |
|
|
499 | string. |
|
|
500 | |
|
|
501 | =item C<BER_TYPE_UCS2> |
|
|
502 | |
|
|
503 | Similar to C<BER_TYPE_UTF8>, but treats the BER value as UCS-2 encoded |
|
|
504 | string. |
|
|
505 | |
|
|
506 | =item C<BER_TYPE_UCS4> |
|
|
507 | |
|
|
508 | Similar to C<BER_TYPE_UTF8>, but treats the BER value as UCS-4 encoded |
|
|
509 | string. |
|
|
510 | |
|
|
511 | =item C<BER_TYPE_INT> |
|
|
512 | |
|
|
513 | Encodes and decodes a BER integer value to a perl integer scalar. This |
|
|
514 | should correctly handle 64 bit signed and unsigned values. |
|
|
515 | |
|
|
516 | =item C<BER_TYPE_OID> |
|
|
517 | |
|
|
518 | Encodes and decodes an OBJECT IDENTIFIER into dotted form without leading |
|
|
519 | dot, e.g. C<1.3.6.1.213>. |
|
|
520 | |
|
|
521 | =item C<BER_TYPE_RELOID> |
|
|
522 | |
|
|
523 | Same as C<BER_TYPE_OID> but uses relative object identifier |
|
|
524 | encoding: ASN.1 has this hack of encoding the first two OID components |
|
|
525 | into a single integer in a weird attempt to save an insignificant amount |
|
|
526 | of space in an otherwise wasteful encoding, and relative OIDs are |
|
|
527 | basically OIDs without this hack. The practical difference is that the |
|
|
528 | second component of an OID can only have the values 1..40, while relative |
|
|
529 | OIDs do not have this restriction. |
|
|
530 | |
|
|
531 | =item C<BER_TYPE_NULL> |
|
|
532 | |
|
|
533 | Decodes an C<ASN_NULL> value into C<undef>, and always encodes a |
|
|
534 | C<ASN_NULL> type, regardless of the perl value. |
|
|
535 | |
|
|
536 | =item C<BER_TYPE_BOOL> |
|
|
537 | |
|
|
538 | Decodes an C<ASN_BOOLEAN> value into C<0> or C<1>, and encodes a perl |
|
|
539 | boolean value into an C<ASN_BOOLEAN>. |
|
|
540 | |
|
|
541 | =item C<BER_TYPE_REAL> |
|
|
542 | |
|
|
543 | Decodes/encodes a BER real value. NOT IMPLEMENTED. |
|
|
544 | |
|
|
545 | =item C<BER_TYPE_IPADDRESS> |
|
|
546 | |
|
|
547 | Decodes/encodes a four byte string into an IPv4 dotted-quad address string |
|
|
548 | in Perl. Given the obsolete nature of this type, this is a low-effort |
|
|
549 | implementation that simply uses C<sprintf> and C<sscanf>-style conversion, |
|
|
550 | so it won't handle all string forms supported by C<inet_aton> for example. |
|
|
551 | |
|
|
552 | =item C<BER_TYPE_CROAK> |
|
|
553 | |
|
|
554 | Always croaks when encountered during encoding or decoding - the |
|
|
555 | default behaviour when encountering an unknown type is to treat it as |
|
|
556 | C<BER_TYPE_BYTES>. When you don't want that but instead prefer a hard |
|
|
557 | error for some types, then C<BER_TYPE_CROAK> is for you. |
|
|
558 | |
|
|
559 | =back |
|
|
560 | |
|
|
561 | =cut |
|
|
562 | |
|
|
563 | our $DEFAULT_PROFILE = new Convert::BER::XS::Profile; |
|
|
564 | our $SNMP_PROFILE = new Convert::BER::XS::Profile; |
|
|
565 | |
|
|
566 | # additional SNMP application types |
|
|
567 | $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_IPADDRESS , BER_TYPE_IPADDRESS); |
|
|
568 | $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_COUNTER32 , BER_TYPE_INT); |
|
|
569 | $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_UNSIGNED32, BER_TYPE_INT); |
|
|
570 | $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_TIMETICKS , BER_TYPE_INT); |
|
|
571 | $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_OPAQUE , BER_TYPE_IPADDRESS); |
|
|
572 | $SNMP_PROFILE->set (ASN_APPLICATION, SNMP_COUNTER64 , BER_TYPE_INT); |
|
|
573 | |
|
|
574 | $DEFAULT_PROFILE->_set_default; |
|
|
575 | |
78 | 1; |
576 | 1; |
|
|
577 | |
|
|
578 | =head2 LIMITATIONS/NOTES |
|
|
579 | |
|
|
580 | This module can only en-/decode 64 bit signed and unsigned integers, and |
|
|
581 | only when your perl supports those. |
|
|
582 | |
|
|
583 | This module does not generally care about ranges, i.e. it will happily |
|
|
584 | de-/encode 64 bit integers into an C<ASN_INTEGER32> value, or a negative |
|
|
585 | number into an C<SNMP_COUNTER64>. |
|
|
586 | |
|
|
587 | OBJECT IDENTIFIEERs cannot have unlimited length, although the limit is |
|
|
588 | much larger than e.g. the one imposed by SNMP or other protocols,a nd is |
|
|
589 | about 4kB. |
|
|
590 | |
|
|
591 | REAL values are not supported and will currently croak. |
|
|
592 | |
|
|
593 | This module has undergone little to no testing so far. |
|
|
594 | |
|
|
595 | =head2 ITHREADS SUPPORT |
|
|
596 | |
|
|
597 | This module is unlikely to work when the (officially discouraged) ithreads |
|
|
598 | are in use. |
79 | |
599 | |
80 | =head1 AUTHOR |
600 | =head1 AUTHOR |
81 | |
601 | |
82 | Marc Lehmann <schmorp@schmorp.de> |
602 | Marc Lehmann <schmorp@schmorp.de> |
83 | http://software.schmorp.de/pkg/Convert-BER-XS |
603 | http://software.schmorp.de/pkg/Convert-BER-XS |