88 lines
2.8 KiB
Ruby
88 lines
2.8 KiB
Ruby
|
# $Id: tlv.rb 14 2008-03-02 05:42:30Z warchild $
|
||
|
|
#
|
||
|
|
# Copyright (c) 2008, Jon Hart
|
||
|
|
# All rights reserved.
|
||
|
|
#
|
||
|
|
# Redistribution and use in source and binary forms, with or without
|
||
|
|
# modification, are permitted provided that the following conditions are met:
|
||
|
|
# * Redistributions of source code must retain the above copyright
|
||
|
|
# notice, this list of conditions and the following disclaimer.
|
||
|
|
# * Redistributions in binary form must reproduce the above copyright
|
||
|
|
# notice, this list of conditions and the following disclaimer in the
|
||
|
|
# documentation and/or other materials provided with the distribution.
|
||
|
|
# * Neither the name of the <organization> nor the
|
||
|
|
# names of its contributors may be used to endorse or promote products
|
||
|
|
# derived from this software without specific prior written permission.
|
||
|
|
#
|
||
|
|
# THIS SOFTWARE IS PROVIDED BY Jon Hart ``AS IS'' AND ANY
|
||
|
|
# EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
|
||
|
|
# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
|
||
|
|
# DISCLAIMED. IN NO EVENT SHALL Jon Hart BE LIABLE FOR ANY
|
||
|
|
# DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
|
||
|
|
# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
|
||
|
|
# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
|
||
|
|
# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
||
|
|
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
|
||
|
|
# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
||
|
|
#
|
||
|
|
# Simple class for your average type, length, value datastructure.
|
||
|
|
# Everything after the TLV is stuff into +rest+
|
||
|
|
class TLV
|
||
|
|
attr_accessor :type, :length, :value, :rest
|
||
|
|
|
||
|
|
# Create a new TLV which requires +ts+ bytes for the type field
|
||
|
|
# and +ls+ bytes for the length field
|
||
|
|
def initialize(ts, ls)
|
||
|
|
@ts = ts
|
||
|
|
@ls = ls
|
||
|
|
end
|
||
|
|
|
||
|
|
# Given +data+, return the type, length, value and rest
|
||
|
|
# values as dictated by this instance.
|
||
|
|
def decode(data)
|
||
|
|
s = "#{punpack_string(@ts)}#{punpack_string(@ls)}"
|
||
|
|
type, length, tmp = data.unpack("#{s}a*")
|
||
|
|
value, rest = tmp.unpack("a#{length}a*")
|
||
|
|
[type, length, value, rest]
|
||
|
|
end
|
||
|
|
|
||
|
|
def decode!(data)
|
||
|
|
@type, @length, @value, @rest = self.decode(data)
|
||
|
|
end
|
||
|
|
|
||
|
|
# Return a string suitable for use elswhere.
|
||
|
|
def encode
|
||
|
|
s = "#{punpack_string(@ts)}#{punpack_string(@ls)}"
|
||
|
|
[@type, @length, @value].pack("#{s}a*")
|
||
|
|
end
|
||
|
|
|
||
|
|
def to_s
|
||
|
|
encode
|
||
|
|
end
|
||
|
|
|
||
|
|
def to_str
|
||
|
|
encode
|
||
|
|
end
|
||
|
|
|
||
|
|
private
|
||
|
|
# XXX: make this handle arbitrarily sized fields
|
||
|
|
def punpack_string(size)
|
||
|
|
s = ""
|
||
|
|
case size
|
||
|
|
when 1
|
||
|
|
s << "C"
|
||
|
|
when 2
|
||
|
|
s << "n"
|
||
|
|
when 4
|
||
|
|
s << "N"
|
||
|
|
else
|
||
|
|
puts "Size #{s} not supported"
|
||
|
|
exit
|
||
|
|
end
|
||
|
|
s
|
||
|
|
end
|
||
|
|
|
||
|
|
|
||
|
|
end
|
||
|
|
# vim: set ts=2 et sw=2:
|