From: Dr Balwinder S Dheeman <bsd.SANSPAM@...>
Date: 2005-04-19T14:14:34+09:00
Subject: Re: How do I decode strings?

On 04/19/2005 05:17 AM, Sam Roberts wrote:
> Quoting bsd.SANSPAM@cto.homelinux.net, on Tue, Apr 19, 2005 at 02:44:35AM +0900:
> 
>>Dear friends!
>>
>>Ho do I decode MIME encoded strings like 
>>"=?ISO-8859-15?Q?Jes=FAs_=C1ngel?=",  to 8 and, or 7 bit ASCII?
>>
>>I attempted to use Base64.decode_b, but the decoding is not as was expected.
> 
> 
> Yes, its not base64, its RFC2047.
> 
> Here's one way:
> 
> 
> # $Id: rfc2047.rb,v 1.4 2003/04/18 20:55:56 sam Exp $
> #
> # An implementation of RFC 2047 decoding.
> #
> # This module depends on the iconv library by Nobuyoshi Nakada, which I've 
> # heard may be distributed as a standard part of Ruby 1.8. Many thanks to him
> # for helping with building and using iconv.
> #
> # Thanks to "Josef 'Jupp' Schugt" <jupp@gmx.de> for pointing out an error with
> # stateful character sets.
> #
> # Copyright (c) Sam Roberts <sroberts@uniserve.com> 2004
> #
> # This file is distributed under the same terms as Ruby.
> 
> require 'iconv'
> 
> module Rfc2047
> 
>   WORD = %r{=\?([!#$%&'*+-/0-9A-Z\\^\`a-z{|}~]+)\?([BbQq])\?([!->@-~]+)\?=} # :nodoc:
>   WORDSEQ = %r{(#{WORD.source})\s+(?=#{WORD.source})}
> 
>   # Decodes a string, +from+, containing RFC 2047 encoded words into a target
>   # character set, +target+. See iconv_open(3) for information on the
>   # supported target encodings. If one of the encoded words cannot be
>   # converted to the target encoding, it is left in its encoded form.
>   def Rfc2047.decode_to(target, from)
>     from = from.gsub(WORDSEQ, '\1')
>     out = from.gsub(WORD) do
>       |word|
>       charset, encoding, text = $1, $2, $3
>       
>       # B64 or QP decode, as necessary:
>       case encoding
>         when 'b', 'B'
>           #puts text
>           text = text.unpack('m*')[0]
>           #puts text.dump
> 
>         when 'q', 'Q'
>           # RFC 2047 has a variant of quoted printable where a ' ' character
>           # can be represented as an '_', rather than =32, so convert
>           # any of these that we find before doing the QP decoding.
>           text = text.tr("_", " ")
>           text = text.unpack('M*')[0]
> 
>         # Don't need an else, because no other values can be matched in a
>         # WORD.
>       end
> 
>       # Convert:
>       #
>       # Remember - Iconv.open(to, from)!
>       begin
>         text = Iconv.iconv(target, charset, text).join
>         #puts text.dump
>       rescue Errno::EINVAL, Iconv::IllegalSequence
>         # Replace with the entire matched encoded word, a NOOP.
>         text = word
>       end
>     end
>   end
> end

Thanks a lot! that's what I needed :)

-- 
Dr Balwinder Singh Dheeman            Registered Linux User: #229709
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