Problem with encodings about mail HOT 17 CLOSED

require 'rubygems'
require 'iconv'
require 'mail'

mail = Mail.new "To:[email protected]\nFrom: [email protected]\nSubject: =?ISO-8859-1?Q?2_=FAlt?=\n\nsome text\n\n"

p mail.subject
puts mail.subject
p Iconv.conv("iso-8859-1", "utf-8", mail.subject)
p mail.subject.unpack("U*")

$ irb
irb(main):001:0> require 'rubygems'
=> true
irb(main):002:0> require 'iconv'
=> true
irb(main):003:0> require 'mail'
=> true
irb(main):004:0> 
irb(main):005:0* mail = Mail.new "To:[email protected]\nFrom: [email protected]\nSubject: =?ISO-8859-1?Q?2_=FAlt?=\n\nsome text\n\n"
=> #<Mail::Message:70210791052740, Multipart: false, Headers: <From: [email protected]>, <To: [email protected]>, <Subject: =?ISO-8859-1?Q?2_=FAlt?=>>
irb(main):006:0> 
irb(main):007:0* p mail.subject
"2 \372lt"
=> nil
irb(main):008:0> puts mail.subject
2 ?lt
=> nil
irb(main):009:0> p Iconv.conv("iso-8859-1", "utf-8", mail.subject)
Iconv::IllegalSequence: "\372lt"
    from (irb):9:in `conv'
    from (irb):9
irb(main):010:0> p mail.subject.unpack("U*")
ArgumentError: malformed UTF-8 character (expected 5 bytes, given 3 bytes)
    from (irb):10:in `unpack'
    from (irb):10

irb(main):011:0> Mail::VERSION::STRING
=> "2.2.0"

module Mail
  class UnstructuredField
    def do_decode
      ret = value.blank? ? nil : Encodings.decode_encode(value, :decode).encode("UTF-8")
    end
  end
end

require 'mail'
Mail.new("To:[email protected]\nFrom: [email protected]\nSubject: ma=?ISO-8859-1?Q?=F1ana?=\n\nsome text\n\n").subject

module Mail
  class UnstructuredField
    def do_decode
      value.blank? ? nil : Encodings.decode_encode(value, :decode).encode("UTF-8")
    end
  end
  module Encodings
    def Encodings.value_decode(str)
      # Optimization: If there's no encoded-words in the string, just return it
      return str unless str.index("=?")
      str = str.gsub(/\?=(\s*)=\?/, '?==?') # Remove whitespaces between 'encoded-word's
      # Split on white-space boundaries with capture, so we capture the white-space as well
      str.split(/([ \t])/).map do |text|
    if text.index('=?').nil? #!= 0
      text
    else
      # Join QP encoded-words that are adjacent to avoid decoding partial chars
      text.gsub!(/\?\=\=\?.+?\?[Qq]\?/m, '') if text =~ /\?==\?/

      # Separate encoded-words with a space, so we can treat them one by one
      text.gsub!(/\?\=\=\?/, '?= =?')
      text.split(/ /).map do |word|
        word.to_str.
          gsub(/=\?.+\?[Bb]\?.+\?=/m) {|substr| b_value_decode(substr)}.
          gsub(/=\?.+\?[Qq]\?.+\?=/m) {|substr| q_value_decode(substr)}
#
#            case
#            when word.to_str =~ /=\?.+\?[Bb]\?/m
#              b_value_decode(word)
#            when text.to_str =~ /=\?.+\?[Qq]\?/m
#              q_value_decode(word)
#            else
#              word.to_str
#            end
      end
    end
      end.join("")
    end
  end
end