# $Id: ber.rb 142 2006-07-26 12:20:33Z blackhedd $
#
# NET::BER
# Mixes ASN.1/BER convenience methods into several standard classes.
# Also provides BER parsing functionality.
#
#----------------------------------------------------------------------------
#
# Copyright (C) 2006 by Francis Cianfrocca. All Rights Reserved.
#
# Gmail: garbagecat10
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
#
#---------------------------------------------------------------------------
#
#
module Net
module BER
class BerError < Exception; end
# This module is for mixing into IO and IO-like objects.
module BERParser
# The order of these follows the class-codes in BER.
# Maybe this should have been a hash.
TagClasses = [:universal, :application, :context_specific, :private]
BuiltinSyntax = {
:universal => {
:primitive => {
1 => :boolean,
2 => :integer,
4 => :string,
10 => :integer,
},
:constructed => {
16 => :array,
17 => :array
}
}
}
#
# read_ber
# 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.
#
def read_ber syntax=nil
return nil if eof?
id = getc # don't trash this value, we'll use it later
tag = id & 31
tag < 31 or raise BerError.new( "unsupported tag encoding: #{id}" )
tagclass = TagClasses[ id >> 6 ]
encoding = (id & 0x20 != 0) ? :constructed : :primitive
n = getc
lengthlength,contentlength = if n <= 127
[1,n]
else
j = (0...(n & 127)).inject(0) {|mem,x| mem = (mem << 8) + getc}
[1 + (n & 127), j]
end
newobj = read contentlength
objtype = nil
[syntax, BuiltinSyntax].each {|syn|
if syn && (ot = syn[tagclass]) && (ot = ot[encoding]) && ot[tag]
objtype = ot[tag]
break
end
}
obj = case objtype
when :boolean
newobj != "\000"
when :string
(newobj || "").dup
when :integer
j = 0
newobj.each_byte {|b| j = (j << 8) + b}
j
when :array
seq = []
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
else
raise BerError.new( "unsupported object type: class=#{tagclass}, encoding=#{encoding}, tag=#{tag}" )
end
# Add the identifier bits into the object if it's a String or an Array.
# We can't add extra stuff to Fixnums and booleans, not that it makes much sense anyway.
obj and ([String,Array].include? obj.class) and obj.instance_eval "def ber_identifier; #{id}; end"
obj
end
end # module BERParser
end # module BER
end # module Net
class IO
include Net::BER::BERParser
end
require "stringio"
class StringIO
include Net::BER::BERParser
end
begin
require 'openssl'
class OpenSSL::SSL::SSLSocket
include Net::BER::BERParser
end
rescue LoadError
# Ignore LoadError.
# DON'T ignore NameError, which means the SSLSocket class
# is somehow unavailable on this implementation of Ruby's openssl.
# This may be WRONG, however, because we don't yet know how Ruby's
# openssl behaves on machines with no OpenSSL library. I suppose
# it's possible they do not fail to require 'openssl' but do not
# create the classes. So this code is provisional.
# Also, you might think that OpenSSL::SSL::SSLSocket inherits from
# IO so we'd pick it up above. But you'd be wrong.
end
class String
def read_ber syntax=nil
StringIO.new(self).read_ber(syntax)
end
end
#----------------------------------------------
class FalseClass
#
# to_ber
#
def to_ber
"\001\001\000"
end
end
class TrueClass
#
# to_ber
#
def to_ber
"\001\001\001"
end
end
class Fixnum
#
# to_ber
#
def to_ber
i = [self].pack('w')
[2, i.length].pack("CC") + i
end
#
# to_ber_enumerated
#
def to_ber_enumerated
i = [self].pack('w')
[10, i.length].pack("CC") + i
end
#
# to_ber_length_encoding
#
def to_ber_length_encoding
if self <= 127
[self].pack('C')
else
i = [self].pack('N').sub(/^[\0]+/,"")
[0x80 + i.length].pack('C') + i
end
end
end # class Fixnum
class Bignum
def to_ber
i = [self].pack('w')
i.length > 126 and raise Net::BER::BerError.new( "range error in bignum" )
[2, i.length].pack("CC") + i
end
end
class String
#
# to_ber
# A universal octet-string is tag number 4,
# but others are possible depending on the context, so we
# let the caller give us one.
# The preferred way to do this in user code is via to_ber_application_sring
# and to_ber_contextspecific.
#
def to_ber code = 4
[code].pack('C') + length.to_ber_length_encoding + self
end
#
# to_ber_application_string
#
def to_ber_application_string code
to_ber( 0x40 + code )
end
#
# to_ber_contextspecific
#
def to_ber_contextspecific code
to_ber( 0x80 + code )
end
end # class String
class Array
#
# to_ber_appsequence
# An application-specific sequence usually gets assigned
# a tag that is meaningful to the particular protocol being used.
# This is different from the universal sequence, which usually
# gets a tag value of 16.
# Now here's an interesting thing: We're adding the X.690
# "application constructed" code at the top of the tag byte (0x60),
# but some clients, notably ldapsearch, send "context-specific
# constructed" (0xA0). The latter would appear to violate RFC-1777,
# but what do I know? We may need to change this.
#
def to_ber id = 0; to_ber_seq_internal( 0x30 + id ); end
def to_ber_set id = 0; to_ber_seq_internal( 0x31 + id ); end
def to_ber_sequence id = 0; to_ber_seq_internal( 0x30 + id ); end
def to_ber_appsequence id = 0; to_ber_seq_internal( 0x60 + id ); end
def to_ber_contextspecific id = 0; to_ber_seq_internal( 0xA0 + id ); end
private
def to_ber_seq_internal code
s = self.to_s
[code].pack('C') + s.length.to_ber_length_encoding + s
end
end # class Array