526 lines
14 KiB
Ruby
526 lines
14 KiB
Ruby
# $Id$
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#
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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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#
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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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#
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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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#
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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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#
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#
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module Net
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module BER
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class BerError < Exception; 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
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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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end
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end
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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 {|tclass,tclasses|
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tagclass = {:universal=>0, :application=>64, :context_specific=>128, :private=>192} [tclass]
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tclasses.each {|codingtype,codings|
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encoding = {:primitive=>0, :constructed=>32} [codingtype]
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codings.each {|tag,objtype|
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out[tagclass + encoding + tag] = objtype
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}
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}
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}
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out
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end
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# This module is for mixing into IO and IO-like objects.
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module BERParser
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# The order of these follows the class-codes in BER.
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# Maybe this should have been a hash.
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TagClasses = [:universal, :application, :context_specific, :private]
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BuiltinSyntax = BER.compile_syntax( {
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:universal => {
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:primitive => {
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1 => :boolean,
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2 => :integer,
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4 => :string,
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5 => :null,
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6 => :oid,
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10 => :integer,
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13 => :string # (relative OID)
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},
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:constructed => {
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16 => :array,
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17 => :array
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}
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}
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})
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#
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# read_ber
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# TODO: clean this up so it works properly with partial
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# packets coming from streams that don't block when
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# we ask for more data (like StringIOs). At it is,
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# this can throw TypeErrors and other nasties.
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#--
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# BEWARE, this violates DRY and is largely equal in functionality to
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# read_ber_from_string. Eventually that method may subsume the functionality
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# of this one.
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#
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def read_ber syntax=nil
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# don't bother with this line, since IO#getc by definition returns nil on eof.
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#return nil if eof?
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id = getc or return nil # don't trash this value, we'll use it later
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#tag = id & 31
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#tag < 31 or raise BerError.new( "unsupported tag encoding: #{id}" )
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#tagclass = TagClasses[ id >> 6 ]
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#encoding = (id & 0x20 != 0) ? :constructed : :primitive
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n = getc
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lengthlength,contentlength = if n <= 127
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[1,n]
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else
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# Replaced the inject because it profiles hot.
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#j = (0...(n & 127)).inject(0) {|mem,x| mem = (mem << 8) + getc}
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j = 0
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read( n & 127 ).each_byte {|n1| j = (j << 8) + n1}
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[1 + (n & 127), j]
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end
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newobj = read contentlength
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# This exceptionally clever and clear bit of code is verrrry slow.
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objtype = (syntax && syntax[id]) || BuiltinSyntax[id]
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# == is expensive so sort this if/else so the common cases are at the top.
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obj = if objtype == :string
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#(newobj || "").dup
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s = BerIdentifiedString.new( newobj || "" )
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s.ber_identifier = id
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s
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elsif objtype == :integer
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j = 0
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newobj.each_byte {|b| j = (j << 8) + b}
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j
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elsif objtype == :oid
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# cf X.690 pgh 8.19 for an explanation of this algorithm.
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# Potentially not good enough. We may need a BerIdentifiedOid
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# as a subclass of BerIdentifiedArray, to get the ber identifier
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# and also a to_s method that produces the familiar dotted notation.
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oid = newobj.unpack("w*")
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f = oid.shift
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g = if f < 40
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[0, f]
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elsif f < 80
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[1, f-40]
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else
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[2, f-80] # f-80 can easily be > 80. What a weird optimization.
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end
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oid.unshift g.last
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oid.unshift g.first
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oid
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elsif objtype == :array
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#seq = []
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seq = BerIdentifiedArray.new
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seq.ber_identifier = id
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sio = StringIO.new( newobj || "" )
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# Interpret the subobject, but note how the loop
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# is built: nil ends the loop, but false (a valid
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# BER value) does not!
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while (e = sio.read_ber(syntax)) != nil
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seq << e
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end
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seq
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elsif objtype == :boolean
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newobj != "\000"
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elsif objtype == :null
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n = BerIdentifiedNull.new
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n.ber_identifier = id
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n
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else
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#raise BerError.new( "unsupported object type: class=#{tagclass}, encoding=#{encoding}, tag=#{tag}" )
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raise BerError.new( "unsupported object type: id=#{id}" )
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end
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# Add the identifier bits into the object if it's a String or an Array.
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# We can't add extra stuff to Fixnums and booleans, not that it makes much sense anyway.
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# Replaced this mechanism with subclasses because the instance_eval profiled too hot.
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#obj and ([String,Array].include? obj.class) and obj.instance_eval "def ber_identifier; #{id}; end"
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#obj.ber_identifier = id if obj.respond_to?(:ber_identifier)
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obj
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end
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#--
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# Violates DRY! This replicates the functionality of #read_ber.
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# Eventually this method may replace that one.
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# This version of #read_ber behaves properly in the face of incomplete
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# data packets. If a full BER object is detected, we return an array containing
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# the detected object and the number of bytes consumed from the string.
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# If we don't detect a complete packet, return nil.
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#
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# Observe that weirdly we recursively call the original #read_ber in here.
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# That needs to be fixed if we ever obsolete the original method in favor of this one.
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def read_ber_from_string str, syntax=nil
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id = str[0] or return nil
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n = str[1] or return nil
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n_consumed = 2
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lengthlength,contentlength = if n <= 127
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[1,n]
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else
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n1 = n & 127
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return nil unless str.length >= (n_consumed + n1)
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j = 0
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n1.times {
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j = (j << 8) + str[n_consumed]
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n_consumed += 1
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}
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[1 + (n1), j]
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end
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return nil unless str.length >= (n_consumed + contentlength)
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newobj = str[n_consumed...(n_consumed + contentlength)]
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n_consumed += contentlength
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objtype = (syntax && syntax[id]) || BuiltinSyntax[id]
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# == is expensive so sort this if/else so the common cases are at the top.
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obj = if objtype == :array
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seq = BerIdentifiedArray.new
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seq.ber_identifier = id
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sio = StringIO.new( newobj || "" )
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# Interpret the subobject, but note how the loop
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# is built: nil ends the loop, but false (a valid
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# BER value) does not!
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# Also, we can use the standard read_ber method because
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# we know for sure we have enough data. (Although this
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# might be faster than the standard method.)
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while (e = sio.read_ber(syntax)) != nil
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seq << e
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end
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seq
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elsif objtype == :string
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s = BerIdentifiedString.new( newobj || "" )
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s.ber_identifier = id
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s
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elsif objtype == :integer
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j = 0
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newobj.each_byte {|b| j = (j << 8) + b}
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j
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elsif objtype == :oid
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# cf X.690 pgh 8.19 for an explanation of this algorithm.
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# Potentially not good enough. We may need a BerIdentifiedOid
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# as a subclass of BerIdentifiedArray, to get the ber identifier
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# and also a to_s method that produces the familiar dotted notation.
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oid = newobj.unpack("w*")
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f = oid.shift
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g = if f < 40
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[0,f]
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elsif f < 80
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[1, f-40]
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else
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[2, f-80] # f-80 can easily be > 80. What a weird optimization.
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end
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oid.unshift g.last
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oid.unshift g.first
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oid
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elsif objtype == :boolean
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newobj != "\000"
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elsif objtype == :null
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n = BerIdentifiedNull.new
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n.ber_identifier = id
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n
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else
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raise BerError.new( "unsupported object type: id=#{id}" )
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end
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[obj, n_consumed]
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end
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end # module BERParser
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end # module BER
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end # module Net
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class IO
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include Net::BER::BERParser
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end
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require "stringio"
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class StringIO
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include Net::BER::BERParser
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end
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begin
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require 'openssl'
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class OpenSSL::SSL::SSLSocket
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include Net::BER::BERParser
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end
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rescue LoadError
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# Ignore LoadError.
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# DON'T ignore NameError, which means the SSLSocket class
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# is somehow unavailable on this implementation of Ruby's openssl.
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# This may be WRONG, however, because we don't yet know how Ruby's
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# openssl behaves on machines with no OpenSSL library. I suppose
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# it's possible they do not fail to require 'openssl' but do not
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# create the classes. So this code is provisional.
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# Also, you might think that OpenSSL::SSL::SSLSocket inherits from
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# IO so we'd pick it up above. But you'd be wrong.
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end
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class String
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include Net::BER::BERParser
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def read_ber syntax=nil
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StringIO.new(self).read_ber(syntax)
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end
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def read_ber! syntax=nil
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obj,n_consumed = read_ber_from_string(self, syntax)
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if n_consumed
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self.slice!(0...n_consumed)
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obj
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else
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nil
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end
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end
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end
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#----------------------------------------------
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class FalseClass
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#
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# to_ber
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#
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def to_ber
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"\001\001\000"
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end
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end
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class TrueClass
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#
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# to_ber
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#
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def to_ber
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"\001\001\001"
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end
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end
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class Fixnum
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#
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# to_ber
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#
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def to_ber
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"\002" + to_ber_internal
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end
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#
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# to_ber_enumerated
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#
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def to_ber_enumerated
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"\012" + to_ber_internal
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end
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#
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# to_ber_length_encoding
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#
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def to_ber_length_encoding
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if self <= 127
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[self].pack('C')
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else
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i = [self].pack('N').sub(/^[\0]+/,"")
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[0x80 + i.length].pack('C') + i
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end
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end
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# Generate a BER-encoding for an application-defined INTEGER.
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# Example: SNMP's Counter, Gauge, and TimeTick types.
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#
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def to_ber_application tag
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[0x40 + tag].pack("C") + to_ber_internal
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end
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#--
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# Called internally to BER-encode the length and content bytes of a Fixnum.
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# The caller will prepend the tag byte.
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def to_ber_internal
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# PLEASE optimize this code path. It's awfully ugly and probably slow.
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# It also doesn't understand negative numbers yet.
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raise Net::BER::BerError.new( "range error in fixnum" ) unless self >= 0
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z = [self].pack("N")
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zlen = if self < 0x80
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1
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elsif self < 0x8000
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2
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elsif self < 0x800000
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3
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else
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4
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end
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[zlen].pack("C") + z[0-zlen,zlen]
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end
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private :to_ber_internal
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end # class Fixnum
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class Bignum
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def to_ber
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#i = [self].pack('w')
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#i.length > 126 and raise Net::BER::BerError.new( "range error in bignum" )
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#[2, i.length].pack("CC") + i
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# Ruby represents Bignums as two's-complement numbers so we may actually be
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# good as far as representing negatives goes.
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# I'm sure this implementation can be improved performance-wise if necessary.
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# Ruby's Bignum#size returns the number of bytes in the internal representation
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# of the number, but it can and will include leading zero bytes on at least
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# some implementations. Evidently Ruby stores these as sets of quadbytes.
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# It's not illegal in BER to encode all of the leading zeroes but let's strip
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# them out anyway.
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#
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sz = self.size
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out = "\000" * sz
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(sz*8).times {|bit|
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if self[bit] == 1
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out[bit/8] += (1 << (bit % 8))
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end
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}
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while out.length > 1 and out[-1] == 0
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out.slice!(-1,1)
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end
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[2, out.length].pack("CC") + out.reverse
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end
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end
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class String
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#
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# to_ber
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# A universal octet-string is tag number 4,
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# but others are possible depending on the context, so we
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# let the caller give us one.
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# The preferred way to do this in user code is via to_ber_application_sring
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# and to_ber_contextspecific.
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#
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def to_ber code = 4
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[code].pack('C') + length.to_ber_length_encoding + self
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end
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#
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# to_ber_application_string
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#
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def to_ber_application_string code
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to_ber( 0x40 + code )
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end
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#
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# to_ber_contextspecific
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#
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def to_ber_contextspecific code
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to_ber( 0x80 + code )
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end
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end # class String
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class Array
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#
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# to_ber_appsequence
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# An application-specific sequence usually gets assigned
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# a tag that is meaningful to the particular protocol being used.
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# This is different from the universal sequence, which usually
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# gets a tag value of 16.
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# Now here's an interesting thing: We're adding the X.690
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# "application constructed" code at the top of the tag byte (0x60),
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# but some clients, notably ldapsearch, send "context-specific
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# constructed" (0xA0). The latter would appear to violate RFC-1777,
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# but what do I know? We may need to change this.
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#
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def to_ber id = 0; to_ber_seq_internal( 0x30 + id ); end
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def to_ber_set id = 0; to_ber_seq_internal( 0x31 + id ); end
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def to_ber_sequence id = 0; to_ber_seq_internal( 0x30 + id ); end
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def to_ber_appsequence id = 0; to_ber_seq_internal( 0x60 + id ); end
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def to_ber_contextspecific id = 0; to_ber_seq_internal( 0xA0 + id ); end
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def to_ber_oid
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ary = self.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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private
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def to_ber_seq_internal code
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s = self.to_s
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[code].pack('C') + s.length.to_ber_length_encoding + s
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end
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end # class Array
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