295 lines
7.0 KiB
Ruby
295 lines
7.0 KiB
Ruby
# $Id: ber.rb 142 2006-07-26 12:20:33Z blackhedd $
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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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# 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 = {
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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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10 => :integer,
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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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def read_ber syntax=nil
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return nil if (StringIO == self.class) and eof?
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id = getc # 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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j = (0...(n & 127)).inject(0) {|mem,x| mem = (mem << 8) + getc}
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[1 + (n & 127), j]
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end
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newobj = read contentlength
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objtype = nil
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[syntax, BuiltinSyntax].each {|syn|
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if syn && (ot = syn[tagclass]) && (ot = ot[encoding]) && ot[tag]
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objtype = ot[tag]
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break
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end
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}
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obj = case objtype
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when :boolean
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newobj != "\000"
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when :string
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(newobj || "").dup
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when :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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when :array
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seq = []
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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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else
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raise BerError.new( "unsupported object type: class=#{tagclass}, encoding=#{encoding}, tag=#{tag}" )
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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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obj and ([String,Array].include? obj.class) and obj.instance_eval "def ber_identifier; #{id}; end"
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obj
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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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def read_ber syntax=nil
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StringIO.new(self).read_ber(syntax)
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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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i = [self].pack('w')
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[2, i.length].pack("CC") + i
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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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i = [self].pack('w')
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[10, i.length].pack("CC") + i
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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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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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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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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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