ruby-net-ldap/lib/net/ber/ber_parser.rb
2010-03-15 20:16:12 -04:00

113 lines
3.3 KiB
Ruby

require 'stringio'
module Net
module BER
module BERParser
VERSION = '0.1.0'
# The order of these follows the class-codes in BER.
# Maybe this should have been a hash.
TagClasses = [:universal, :application, :context_specific, :private]
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
}
}
})
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
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
[0, f]
elsif f < 80
[1, f-40]
else
[2, f-80] # f-80 can easily be > 80. What a weird optimization.
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.new( "unsupported object type: id=#{id}" )
end
obj
end
end
end
end