225 lines
7.9 KiB
Ruby
225 lines
7.9 KiB
Ruby
module Net
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module BER
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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 = Net::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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:context_specific => {
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:primitive => {
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10 => :integer
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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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# here we'll create two different procs, one for 1.8 and one for 1.9
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# the reason being getc doesn't return a byte value in 1.9, so we need to
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# get the byte code out of the 1.9 encoded string
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if RUBY_VERSION =~ /^1\.9/
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fetch_byte = Proc.new { getc.bytes.first }
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elsif RUBY_VERSION =~ /^1\.8/
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fetch_byte = Proc.new { getc }
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end
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id = fetch_byte.call 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 = fetch_byte.call
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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
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end
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end |