Reformat and documentation update of Net::BER and Net::BER::BERParser.
Austin Ziegler
parent
28d58cd581
commit
1d3817e007
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@ -25,7 +25,8 @@
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* Extended unit testing:
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* Added some unit tests for the BER core extensions.
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* Code clean-up:
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* Made the formatting of Net::LDAP code consistent across all files.
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* Made the formatting of code consistent across all files.
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* Removed Net::BER::BERParser::TagClasses as it does not appear to be used.
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* Replaced calls to #to_a with calls to Kernel#Array; since Ruby 1.8.3, the
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default #to_a implementation has been deprecated and should be replaced
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either with calls to Kernel#Array or [value].flatten(1).
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392
lib/net/ber.rb
392
lib/net/ber.rb
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@ -1,99 +1,339 @@
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# NET::BER
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# Mixes ASN.1/BER convenience methods into several standard classes.
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# Also provides BER parsing functionality.
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#
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#----------------------------------------------------------------------------
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# Mixes ASN.1/BER convenience methods into several standard classes. Also
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# provides BER parsing functionality.
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#
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#--
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# Copyright (C) 2006 by Francis Cianfrocca. All Rights Reserved.
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#
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# Gmail: garbagecat10
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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# This program is free software; you can redistribute it and/or modify it
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# under the terms of the GNU General Public License as published by the Free
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# Software Foundation; either version 2 of the License, or (at your option)
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# any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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# This program is distributed in the hope that it will be useful, but
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# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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# or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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# for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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#
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#---------------------------------------------------------------------------
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# You should have received a copy of the GNU General Public License along
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# with this program; if not, write to the Free Software Foundation, Inc., 51
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# Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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#++
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module Net
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##
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# == Basic Encoding Rules (BER) Support Module
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#
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# Much of the text below is cribbed from Wikipedia:
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# http://en.wikipedia.org/wiki/Basic_Encoding_Rules
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#
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# The ITU Specification is also worthwhile reading:
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# http://www.itu.int/ITU-T/studygroups/com17/languages/X.690-0207.pdf
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#
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# The Basic Encoding Rules were the original rules laid out by the ASN.1
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# standard for encoding abstract information into a concrete data stream.
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# The rules, collectively referred to as a transfer syntax in ASN.1
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# parlance, specify the exact octet sequences which are used to encode a
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# given data item. The syntax defines such elements as: the
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# representations for basic data types, the structure of length
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# information, and the means for defining complex or compound types based
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# on more primitive types. The BER syntax, along with two subsets of BER
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# (the Canonical Encoding Rules and the Distinguished Encoding Rules), are
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# defined by the ITU-T's X.690 standards document, which is part of the
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# ASN.1 document series.
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#
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# == Encoding
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# The BER format specifies a self-describing and self-delimiting format
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# for encoding ASN.1 data structures. Each data element is encoded as a
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# type identifier, a length description, the actual data elements, and
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# where necessary, an end-of-content marker. This format allows a receiver
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# to decode the ASN.1 information from an incomplete stream, without
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# requiring any pre-knowledge of the size, content, or semantic meaning of
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# the data.
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#
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# <Type | Length | Value [| End-of-Content]>
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#
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# == Protocol Data Units (PDU)
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# Protocols are defined with schema represented in BER, such that a PDU
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# consists of cascaded type-length-value encodings.
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#
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# === Type Tags
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# BER type tags are represented as single octets (bytes). The lower five
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# bits of the octet are tag identifier numbers and the upper three bits of
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# the octet are used to distinguish the type as native to ASN.1,
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# application-specific, context-specific, or private. See
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# Net::BER::TAG_CLASS and Net::BER::ENCODING_TYPE for more information.
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#
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# If Class is set to Universal (0b00______), the value is of a type native
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# to ASN.1 (e.g. INTEGER). The Application class (0b01______) is only
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# valid for one specific application. Context_specific (0b10______)
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# depends on the context and private (0b11_______) can be defined in
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# private specifications
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#
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# If the primitive/constructed bit is zero (0b__0_____), it specifies that
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# the value is primitive like an INTEGER. If it is one (0b__1_____), the
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# value is a constructed value that contains type-length-value encoded
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# types like a SET or a SEQUENCE.
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#
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# === Defined Universal (ASN.1 Native) Types
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# There are a number of pre-defined universal (native) types.
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#
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# <table>
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# <tr><th>Name</th><th>Primitive<br />Constructed</th><th>Number</th></tr>
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# <tr><th>EOC (End-of-Content)</th><th>P</th><td>0: 0 (0x0, 0b00000000)</td></tr>
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# <tr><th>BOOLEAN</th><th>P</th><td>1: 1 (0x01, 0b00000001)</td></tr>
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# <tr><th>INTEGER</th><th>P</th><td>2: 2 (0x02, 0b00000010)</td></tr>
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# <tr><th>BIT STRING</th><th>P</th><td>3: 3 (0x03, 0b00000011)</td></tr>
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# <tr><th>BIT STRING</th><th>C</th><td>3: 35 (0x23, 0b00100011)</td></tr>
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# <tr><th>OCTET STRING</th><th>P</th><td>4: 4 (0x04, 0b00000100)</td></tr>
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# <tr><th>OCTET STRING</th><th>C</th><td>4: 36 (0x24, 0b00100100)</td></tr>
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# <tr><th>NULL</th><th>P</th><td>5: 5 (0x05, 0b00000101)</td></tr>
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# <tr><th>OBJECT IDENTIFIER</th><th>P</th><td>6: 6 (0x06, 0b00000110)</td></tr>
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# <tr><th>Object Descriptor</th><th>P</th><td>7: 7 (0x07, 0b00000111)</td></tr>
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# <tr><th>EXTERNAL</th><th>C</th><td>8: 40 (0x28, 0b00101000)</td></tr>
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# <tr><th>REAL (float)</th><th>P</th><td>9: 9 (0x09, 0b00001001)</td></tr>
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# <tr><th>ENUMERATED</th><th>P</th><td>10: 10 (0x0a, 0b00001010)</td></tr>
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# <tr><th>EMBEDDED PDV</th><th>C</th><td>11: 43 (0x2b, 0b00101011)</td></tr>
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# <tr><th>UTF8String</th><th>P</th><td>12: 12 (0x0c, 0b00001100)</td></tr>
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# <tr><th>UTF8String</th><th>C</th><td>12: 44 (0x2c, 0b00101100)</td></tr>
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# <tr><th>RELATIVE-OID</th><th>P</th><td>13: 13 (0x0d, 0b00001101)</td></tr>
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# <tr><th>SEQUENCE and SEQUENCE OF</th><th>C</th><td>16: 48 (0x30, 0b00110000)</td></tr>
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# <tr><th>SET and SET OF</th><th>C</th><td>17: 49 (0x31, 0b00110001)</td></tr>
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# <tr><th>NumericString</th><th>P</th><td>18: 18 (0x12, 0b00010010)</td></tr>
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# <tr><th>NumericString</th><th>C</th><td>18: 50 (0x32, 0b00110010)</td></tr>
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# <tr><th>PrintableString</th><th>P</th><td>19: 19 (0x13, 0b00010011)</td></tr>
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# <tr><th>PrintableString</th><th>C</th><td>19: 51 (0x33, 0b00110011)</td></tr>
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# <tr><th>T61String</th><th>P</th><td>20: 20 (0x14, 0b00010100)</td></tr>
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# <tr><th>T61String</th><th>C</th><td>20: 52 (0x34, 0b00110100)</td></tr>
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# <tr><th>VideotexString</th><th>P</th><td>21: 21 (0x15, 0b00010101)</td></tr>
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# <tr><th>VideotexString</th><th>C</th><td>21: 53 (0x35, 0b00110101)</td></tr>
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# <tr><th>IA5String</th><th>P</th><td>22: 22 (0x16, 0b00010110)</td></tr>
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# <tr><th>IA5String</th><th>C</th><td>22: 54 (0x36, 0b00110110)</td></tr>
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# <tr><th>UTCTime</th><th>P</th><td>23: 23 (0x17, 0b00010111)</td></tr>
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# <tr><th>UTCTime</th><th>C</th><td>23: 55 (0x37, 0b00110111)</td></tr>
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# <tr><th>GeneralizedTime</th><th>P</th><td>24: 24 (0x18, 0b00011000)</td></tr>
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# <tr><th>GeneralizedTime</th><th>C</th><td>24: 56 (0x38, 0b00111000)</td></tr>
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# <tr><th>GraphicString</th><th>P</th><td>25: 25 (0x19, 0b00011001)</td></tr>
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# <tr><th>GraphicString</th><th>C</th><td>25: 57 (0x39, 0b00111001)</td></tr>
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# <tr><th>VisibleString</th><th>P</th><td>26: 26 (0x1a, 0b00011010)</td></tr>
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# <tr><th>VisibleString</th><th>C</th><td>26: 58 (0x3a, 0b00111010)</td></tr>
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# <tr><th>GeneralString</th><th>P</th><td>27: 27 (0x1b, 0b00011011)</td></tr>
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# <tr><th>GeneralString</th><th>C</th><td>27: 59 (0x3b, 0b00111011)</td></tr>
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# <tr><th>UniversalString</th><th>P</th><td>28: 28 (0x1c, 0b00011100)</td></tr>
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# <tr><th>UniversalString</th><th>C</th><td>28: 60 (0x3c, 0b00111100)</td></tr>
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# <tr><th>CHARACTER STRING</th><th>P</th><td>29: 29 (0x1d, 0b00011101)</td></tr>
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# <tr><th>CHARACTER STRING</th><th>C</th><td>29: 61 (0x3d, 0b00111101)</td></tr>
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# <tr><th>BMPString</th><th>P</th><td>30: 30 (0x1e, 0b00011110)</td></tr>
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# <tr><th>BMPString</th><th>C</th><td>30: 62 (0x3e, 0b00111110)</td></tr>
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# </table>
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module BER
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VERSION = '0.1.0'
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#--
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# This condenses our nicely self-documenting ASN hashes down
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# to an array for fast lookups.
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# Scoped to be called as a module method, but not intended for
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# user code to call.
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#
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def self.compile_syntax(syn)
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out = [nil] * 256
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syn.each do |tclass, tclasses|
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tagclass = {:universal=>0, :application=>64, :context_specific=>128, :private=>192} [tclass]
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tclasses.each do |codingtype,codings|
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encoding = {:primitive=>0, :constructed=>32} [codingtype]
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codings.each {|tag, objtype| out[tagclass + encoding + tag] = objtype }
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end
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end
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out
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end
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def to_ber
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# Provisional implementation.
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# We ASSUME that our incoming value is an array, and we
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# use the Array#to_ber_oid method defined below.
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# We probably should obsolete that method, actually, in
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# and move the code here.
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# WE ARE NOT CURRENTLY ENCODING THE BER-IDENTIFIER.
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# This implementation currently hardcodes 6, the universal OID tag.
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ary = @value.dup
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first = ary.shift
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raise Net::BER::BerError.new(" invalid OID" ) unless [0,1,2].include?(first)
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first = first * 40 + ary.shift
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ary.unshift first
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oid = ary.pack("w*")
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[6, oid.length].pack("CC") + oid
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end
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end
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end
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module Net
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module BER
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##
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# Used for BER-encoding the length and content bytes of a Fixnum integer
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# values.
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MAX_FIXNUM_SIZE = 0.size
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class BerError < StandardError; end
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class BerIdentifiedString < String
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attr_accessor :ber_identifier
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def initialize args
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super args
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end
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end
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class BerIdentifiedArray < Array
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attr_accessor :ber_identifier
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def initialize(*args)
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super
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end
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end
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class BerIdentifiedNull
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attr_accessor :ber_identifier
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def to_ber
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"\005\000"
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##
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# BER tag classes are kept in bits seven and eight of the tag type
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# octet.
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#
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# <table>
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# <tr><th>Bitmask</th><th>Definition</th></tr>
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# <tr><th><tt>0b00______</tt></th><td>Universal (ASN.1 Native) Types</td></tr>
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# <tr><th><tt>0b01______</tt></th><td>Application Types</td></tr>
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# <tr><th><tt>0b10______</tt></th><td>Context-Specific Types</td></tr>
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# <tr><th><tt>0b11______</tt></th><td>Private Types</td></tr>
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# </table>
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TAG_CLASS = {
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:universal => 0b00000000, # 0
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:application => 0b01000000, # 64
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:context_specific => 0b10000000, # 128
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:private => 0b11000000, # 192
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}
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##
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# BER encoding type is kept in bit 6 of the tag type octet.
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#
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# <table>
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# <tr><th>Bitmask</th><th>Definition</th></tr>
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# <tr><th><tt>0b__0_____</tt></th><td>Primitive</td></tr>
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# <tr><th><tt>0b__1_____</tt></th><td>Constructed</td></tr>
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# </table>
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ENCODING_TYPE = {
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:primitive => 0b00000000, # 0
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:constructed => 0b00100000, # 32
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}
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##
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# Accepts a hash of hashes describing a BER syntax and converts it into
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# a byte-keyed object for fast BER conversion lookup. The resulting
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# "compiled" syntax is used by Net::BER::BERParser.
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#
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# This method should be called only by client classes of Net::BER (e.g.,
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# Net::LDAP and Net::SNMP) and not by clients of those classes.
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#
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# The hash-based syntax uses TAG_CLASS keys that contain hashes of
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# ENCODING_TYPE keys that contain tag numbers with object type markers.
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#
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# :<TAG_CLASS> => {
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# :<ENCODING_TYPE> => {
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# <number> => <object-type>
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# },
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# },
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#
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# === Permitted Object Types
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# <tt>:string</tt>:: A string value, represented as BerIdentifiedString.
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# <tt>:integer</tt>:: An integer value, represented with Fixnum.
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# <tt>:oid</tt>:: An Object Identifier value; see X.690 section
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# 8.19. Currently represented with a standard array,
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# but may be better represented as a
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# BerIdentifiedOID object.
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# <tt>:array</tt>:: A sequence, represented as BerIdentifiedArray.
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# <tt>:boolean</tt>:: A boolean value, represented as +true+ or +false+.
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# <tt>:null</tt>:: A null value, represented as BerIdentifiedNull.
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#
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# === Example
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# Net::LDAP defines its ASN.1 BER syntax something like this:
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#
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# class Net::LDAP
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# AsnSyntax = Net::BER.compile_syntax({
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# :application => {
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# :primitive => {
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# 2 => :null,
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# },
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# :constructed => {
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# 0 => :array,
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# # ...
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# },
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# },
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# :context_specific => {
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# :primitive => {
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# 0 => :string,
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# # ...
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# },
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# :constructed => {
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# 0 => :array,
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# # ...
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# },
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# }
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# })
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# end
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#
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# NOTE:: For readability and formatting purposes, Net::LDAP and its
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# siblings actually construct their syntaxes more deliberately,
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# as shown below. Since a hash is passed in the end in any case,
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# the format does not matter.
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#
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# primitive = { 2 => :null }
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# constructed = {
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# 0 => :array,
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# # ...
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# }
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# application = {
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# :primitive => primitive,
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# :constructed => constructed
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# }
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#
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# primitive = {
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# 0 => :string,
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# # ...
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# }
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# constructed = {
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# 0 => :array,
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# # ...
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# }
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# context_specific = {
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# :primitive => primitive,
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# :constructed => constructed
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# }
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# AsnSyntax = Net::BER.compile_syntax(:application => application,
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# :context_specific => context_specific)
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def self.compile_syntax(syntax)
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# TODO 20100327 AZ: Should we be allocating an array of 256 values
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# that will either be +nil+ or an object type symbol, or should we
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# allocate an empty Hash since unknown values return +nil+ anyway?
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out = [ nil ] * 256
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syntax.each do |tag_class_id, encodings|
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tag_class = TAG_CLASS[tag_class_id]
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encodings.each do |encoding_id, classes|
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encoding = ENCODING_TYPE[encoding_id]
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object_class = tag_class + encoding
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classes.each do |number, object_type|
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out[object_class + number] = object_type
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end
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end
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end
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out
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end
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end
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end
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class Net::BER::BerError < RuntimeError; end
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##
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# An Array object with a BER identifier attached.
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class Net::BER::BerIdentifiedArray < Array
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attr_accessor :ber_identifier
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def initialize(*args)
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super
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end
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end
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##
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# A BER object identifier.
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class Net::BER::BerIdentifiedOid
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attr_accessor :ber_identifier
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def initialize(oid)
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if oid.is_a?(String)
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oid = oid.split(/\./).map {|s| s.to_i }
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end
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@value = oid
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end
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def to_ber
|
||||
to_ber_oid
|
||||
end
|
||||
|
||||
def to_ber_oid
|
||||
@value.to_ber_oid
|
||||
end
|
||||
|
||||
def to_s
|
||||
@value.join(".")
|
||||
end
|
||||
|
||||
def to_arr
|
||||
@value.dup
|
||||
end
|
||||
end
|
||||
|
||||
##
|
||||
# A String object with a BER identifier attached.
|
||||
class Net::BER::BerIdentifiedString < String
|
||||
attr_accessor :ber_identifier
|
||||
def initialize args
|
||||
super args
|
||||
end
|
||||
end
|
||||
|
||||
module Net::BER
|
||||
##
|
||||
# A BER null object.
|
||||
class BerIdentifiedNull
|
||||
attr_accessor :ber_identifier
|
||||
def to_ber
|
||||
"\005\000"
|
||||
end
|
||||
end
|
||||
|
||||
##
|
||||
# The default BerIdentifiedNull object.
|
||||
Null = Net::BER::BerIdentifiedNull.new
|
||||
end
|
||||
|
||||
require 'net/ber/core_ext'
|
||||
|
|
|
|||
|
|
@ -1,112 +1,168 @@
|
|||
require 'stringio'
|
||||
|
||||
module Net
|
||||
module BER
|
||||
module BERParser
|
||||
VERSION = '0.1.0'
|
||||
##
|
||||
# Implements Basic Encoding Rules parsing to be mixed into types as needed.
|
||||
module Net::BER::BERParser
|
||||
primitive = {
|
||||
1 => :boolean,
|
||||
2 => :integer,
|
||||
4 => :string,
|
||||
5 => :null,
|
||||
6 => :oid,
|
||||
10 => :integer,
|
||||
13 => :string # (relative OID)
|
||||
}
|
||||
constructed = {
|
||||
16 => :array,
|
||||
17 => :array
|
||||
}
|
||||
universal = { :primitive => primitive, :constructed => constructed }
|
||||
|
||||
# The order of these follows the class-codes in BER.
|
||||
# Maybe this should have been a hash.
|
||||
TagClasses = [:universal, :application, :context_specific, :private]
|
||||
primitive = { 10 => :integer }
|
||||
context = { :primitive => primitive }
|
||||
|
||||
BuiltinSyntax = Net::BER.compile_syntax( {
|
||||
:universal => {
|
||||
:primitive => {
|
||||
1 => :boolean,
|
||||
2 => :integer,
|
||||
4 => :string,
|
||||
5 => :null,
|
||||
6 => :oid,
|
||||
10 => :integer,
|
||||
13 => :string # (relative OID)
|
||||
},
|
||||
:constructed => {
|
||||
16 => :array,
|
||||
17 => :array
|
||||
}
|
||||
},
|
||||
:context_specific => {
|
||||
:primitive => {
|
||||
10 => :integer
|
||||
}
|
||||
}
|
||||
})
|
||||
# The universal, built-in ASN.1 BER syntax.
|
||||
BuiltinSyntax = Net::BER.compile_syntax(:universal => universal,
|
||||
:context_specific => context)
|
||||
|
||||
def read_ber syntax=nil
|
||||
# TODO: clean this up so it works properly with partial
|
||||
# packets coming from streams that don't block when
|
||||
# we ask for more data (like StringIOs). At it is,
|
||||
# this can throw TypeErrors and other nasties.
|
||||
|
||||
id = getbyte or return nil # don't trash this value, we'll use it later
|
||||
##
|
||||
# This is an extract of our BER object parsing to simplify our
|
||||
# understanding of how we parse basic BER object types.
|
||||
def parse_ber_object(syntax, id, data)
|
||||
# Find the object type from either the provided syntax lookup table or
|
||||
# the built-in syntax lookup table.
|
||||
#
|
||||
# This exceptionally clever bit of code is verrrry slow.
|
||||
object_type = (syntax && syntax[id]) || BuiltinSyntax[id]
|
||||
|
||||
n = getbyte
|
||||
lengthlength,contentlength = if n <= 127
|
||||
[1,n]
|
||||
else
|
||||
# Replaced the inject because it profiles hot.
|
||||
# j = (0...(n & 127)).inject(0) {|mem,x| mem = (mem << 8) + getc}
|
||||
j = 0
|
||||
read( n & 127 ).each_byte {|n1| j = (j << 8) + n1}
|
||||
[1 + (n & 127), j]
|
||||
end
|
||||
|
||||
newobj = read contentlength
|
||||
|
||||
# This exceptionally clever and clear bit of code is verrrry slow.
|
||||
objtype = (syntax && syntax[id]) || BuiltinSyntax[id]
|
||||
|
||||
# == is expensive so sort this if/else so the common cases are at the top.
|
||||
obj = if objtype == :string
|
||||
#(newobj || "").dup
|
||||
s = BerIdentifiedString.new( newobj || "" )
|
||||
s.ber_identifier = id
|
||||
s
|
||||
elsif objtype == :integer
|
||||
j = 0
|
||||
newobj.each_byte {|b| j = (j << 8) + b}
|
||||
j
|
||||
elsif objtype == :oid
|
||||
# cf X.690 pgh 8.19 for an explanation of this algorithm.
|
||||
# Potentially not good enough. We may need a BerIdentifiedOid
|
||||
# as a subclass of BerIdentifiedArray, to get the ber identifier
|
||||
# and also a to_s method that produces the familiar dotted notation.
|
||||
oid = newobj.unpack("w*")
|
||||
f = oid.shift
|
||||
g = if f < 40
|
||||
# == is expensive so sort this so the common cases are at the top.
|
||||
if object_type == :string
|
||||
s = Net::BER::BerIdentifiedString.new(data || "")
|
||||
s.ber_identifier = id
|
||||
s
|
||||
elsif object_type == :integer
|
||||
j = 0
|
||||
data.each_byte { |b| j = (j << 8) + b }
|
||||
j
|
||||
elsif object_type == :oid
|
||||
# See X.690 pgh 8.19 for an explanation of this algorithm.
|
||||
# This is potentially not good enough. We may need a
|
||||
# BerIdentifiedOid as a subclass of BerIdentifiedArray, to
|
||||
# get the ber identifier and also a to_s method that produces
|
||||
# the familiar dotted notation.
|
||||
oid = data.unpack("w*")
|
||||
f = oid.shift
|
||||
g = if f < 40
|
||||
[0, f]
|
||||
elsif f < 80
|
||||
[1, f-40]
|
||||
[1, f - 40]
|
||||
else
|
||||
[2, f-80] # f-80 can easily be > 80. What a weird optimization.
|
||||
# f - 80 can easily be > 80. What a weird optimization.
|
||||
[2, f - 80]
|
||||
end
|
||||
oid.unshift g.last
|
||||
oid.unshift g.first
|
||||
oid
|
||||
elsif objtype == :array
|
||||
#seq = []
|
||||
seq = BerIdentifiedArray.new
|
||||
seq.ber_identifier = id
|
||||
sio = StringIO.new( newobj || "" )
|
||||
# Interpret the subobject, but note how the loop
|
||||
# is built: nil ends the loop, but false (a valid
|
||||
# BER value) does not!
|
||||
while (e = sio.read_ber(syntax)) != nil
|
||||
seq << e
|
||||
end
|
||||
seq
|
||||
elsif objtype == :boolean
|
||||
newobj != "\000"
|
||||
elsif objtype == :null
|
||||
n = BerIdentifiedNull.new
|
||||
n.ber_identifier = id
|
||||
n
|
||||
else
|
||||
raise BerError, "unsupported object type: id=0x#{id.to_s(16)}"
|
||||
end
|
||||
|
||||
obj
|
||||
oid.unshift g.last
|
||||
oid.unshift g.first
|
||||
# Net::BER::BerIdentifiedOid.new(oid)
|
||||
oid
|
||||
elsif object_type == :array
|
||||
seq = Net::BER::BerIdentifiedArray.new
|
||||
seq.ber_identifier = id
|
||||
sio = StringIO.new(data || "")
|
||||
# Interpret the subobject, but note how the loop is built:
|
||||
# nil ends the loop, but false (a valid BER value) does not!
|
||||
while (e = sio.read_ber(syntax)) != nil
|
||||
seq << e
|
||||
end
|
||||
seq
|
||||
elsif object_type == :boolean
|
||||
data != "\000"
|
||||
elsif object_type == :null
|
||||
n = Net::BER::BerIdentifiedNull.new
|
||||
n.ber_identifier = id
|
||||
n
|
||||
else
|
||||
raise Net::BER::BerError, "Unsupported object type: id=#{id}"
|
||||
end
|
||||
end
|
||||
private :parse_ber_object
|
||||
|
||||
##
|
||||
# This is an extract of how our BER object length parsing is done to
|
||||
# simplify the primary call. This is defined in X.690 section 8.1.3.
|
||||
#
|
||||
# The BER length will either be a single byte or up to 126 bytes in
|
||||
# length. There is a special case of a BER length indicating that the
|
||||
# content-length is undefined and will be identified by the presence of
|
||||
# two null values (0x00 0x00).
|
||||
#
|
||||
# <table>
|
||||
# <tr>
|
||||
# <th>Range</th>
|
||||
# <th>Length</th>
|
||||
# </tr>
|
||||
# <tr>
|
||||
# <th>0x00 -- 0x7f<br />0b00000000 -- 0b01111111</th>
|
||||
# <td>0 - 127 bytes</td>
|
||||
# </tr>
|
||||
# <tr>
|
||||
# <th>0x80<br />0b10000000</th>
|
||||
# <td>Indeterminate (end-of-content marker required)</td>
|
||||
# </tr>
|
||||
# <tr>
|
||||
# <th>0x81 -- 0xfe<br />0b10000001 -- 0b11111110</th>
|
||||
# <td>1 - 126 bytes of length as an integer value</td>
|
||||
# </tr>
|
||||
# <tr>
|
||||
# <th>0xff<br />0b11111111</th>
|
||||
# <td>Illegal (reserved for future expansion)</td>
|
||||
# </tr>
|
||||
# </table>
|
||||
#
|
||||
#--
|
||||
# This has been modified from the version that was previously inside
|
||||
# #read_ber to handle both the indeterminate terminator case and the
|
||||
# invalid BER length case. Because the "lengthlength" value was not used
|
||||
# inside of #read_ber, we no longer return it.
|
||||
def read_ber_length
|
||||
n = getbyte
|
||||
|
||||
if n <= 0x7f
|
||||
n
|
||||
elsif n == 0x80
|
||||
-1
|
||||
elsif n == 0xff
|
||||
raise Net::BER::BerError, "Invalid BER length 0xFF detected."
|
||||
else
|
||||
v = 0
|
||||
read(n & 0x7f).each_byte do |b|
|
||||
v = (v << 8) + b
|
||||
end
|
||||
|
||||
v
|
||||
end
|
||||
end
|
||||
private :read_ber_length
|
||||
|
||||
##
|
||||
# Reads a BER object from the including object. Requires that #getbyte is
|
||||
# implemented on the including object and that it returns a Fixnum value.
|
||||
# Also requires #read(bytes) to work.
|
||||
#
|
||||
# This does not work with non-blocking I/O.
|
||||
def read_ber(syntax = nil)
|
||||
# TODO: clean this up so it works properly with partial packets coming
|
||||
# from streams that don't block when we ask for more data (like
|
||||
# StringIOs). At it is, this can throw TypeErrors and other nasties.
|
||||
|
||||
id = getbyte or return nil # don't trash this value, we'll use it later
|
||||
content_length = read_ber_length
|
||||
|
||||
if -1 == content_length
|
||||
raise Net::BER::BerError, "Indeterminite BER content length not implemented."
|
||||
else
|
||||
data = read(content_length)
|
||||
end
|
||||
|
||||
parse_ber_object(syntax, id, data)
|
||||
end
|
||||
end
|
||||
|
|
|
|||
Loading…
Reference in New Issue