Sam Roberts
4/18/2005 11:47:00 PM
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