Module: BCodec

Defined in:
lib/bcodec.rb,
lib/bcodec/decode.rb,
lib/bcodec/encode.rb

Overview

BCodec - Ruby module to decode/encode bencoded data Copyright © 2006 Thomas <[email protected]>

This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version.

This library 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 Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

Defined Under Namespace

Classes: InvalidDataType, InvalidInteger, InvalidKey, InvalidString, UnknownData

Class Method Summary collapse

Class Method Details

.decode(io) ⇒ Object

Decodes bencoded data from an IO-like object (IO, File, StringIO or similar that has a .getc method).

Returns the decoded object which is either of these:

  • Array

  • Fixnum (or Bignum)

  • Hash

  • String



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# File 'lib/bcodec/decode.rb', line 34

def BCodec.decode(io)
  c = io.getc

  case c.chr
  when 'i'
    i = ''
    while c = io.getc
      if c.chr == 'e'
        if i.match(/^(0|-?[1-9][0-9]*)$/)
          return i.to_i
        else
          raise InvalidInteger
        end
      else
        i += c.chr
      end
    end
    raise EOFError
  when '0'..'9'
    n = c.chr
    while b = io.getc
      case b.chr
      when '0'..'9'
        n += b.chr
      when ':'
        strlen = n.to_i
        str = io.read(strlen)
        if str.length == strlen
          return str
        else
          raise EOFError
        end
      else
        raise InvalidString
      end
    end
  when 'l'
    list = []
    
    while item = decode(io)
      list.push(item)
    end

    return list
  when 'd'
    dict = {}

    while key = decode(io)
      raise InvalidKey unless key.instance_of?(String)
      val = decode(io)
      dict[key] = val
    end

    return dict
  when 'e'
    return false
  else
    raise UnknownData
  end
end

.encode(obj) ⇒ Object

Bencodes a Ruby object which must be either of these:

  • Array

  • Fixnum (or Bignum)

  • Hash

  • String

Returns the encoded object(s) as a String



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# File 'lib/bcodec/encode.rb', line 31

def BCodec.encode(obj)
  str = ""
  if obj.class == String
    str << "%d:%s" % [ obj.length, obj ]
  elsif obj.class == Fixnum or obj.class == Integer or obj.class == Bignum
    str << "i" <<  obj.to_s << "e"
  elsif obj.class == Array
    str << "l"
    obj.each { |i| str += encode(i) }
    str << "e"
  elsif obj.class == Hash
    str << "d"
    obj.sort.each do |k, v|
      raise InvalidKey unless k.instance_of?(String)
      str << encode(k)
      str << encode(v)
    end
    str << "e"
  else
    raise InvalidDataType
  end

  return str
end