quoted printable decode swallows character when having 2 quoted values

[grosser]

>> Mail.new('Subject: "Subject:=?utf-8?B?0J/QvtC80L7Qs9C40YLQtSDQstC+0YHRgdGC0LDQvdC+0LLQ?= =?utf-8?B?uNGC0Ywg0L/QsNGA0L7Qu9GM?="')['Subject'].to_s
=> "\"Subject:Помогите восстановть пароль\"" # second word ends in ть
>> Mail.new('Subject: "Subject:=?utf-8?B?0J/QvtC80L7Qs9C40YLQtSDQstC+0YHRgdGC0LDQvdC+0LLQuNGC0Ywg0L/QsNGA0L7Qu9GM?="')['Subject'].to_s
=> "\"Subject:Помогите восстановить пароль\"" # second word ends in ить

[grosser]

fix:

Mail::Encoding.prepend(Module.new {
  def collapse_adjacent_encodings(str)
    super(str.gsub(/(\=\?[^?]+\?[QB]\?)([^?]+?)\?\=\s*(\1([^?]+?)\?\=\s*)+/) do |all|
      $1 + all.scan(/\=\?[^?]+\?[QB]\?([^?]+?)\?\=/).join("") + "?="
    end)
  end
})

... this worked for a few encodings, but not with this:

=?windows-1251?B?0uXx8g==?= =?windows-1251?B?IOHo6+Xy?= =?windows-1251?B?IPE=?= =?windows-1251?B?IO3o6uDq4ug=?= =?windows-1251?B?IO/u5+3g7ej/?= =?windows-1251?B?IO/u?= =?windows-1251?B?IODt4+vo6fHq6A==?=

so no idea what to do now :(

[grosser]

ok, this works:

# https://github.com/mikel/mail/issues/741
module MultiByteB64
  def value_decode(str)
    result = super
    result.gsub!("\0", "") # = to A replacement below leaves 0 bytes
    result
  end

  # join multiple of the same encoding to avoid split-bytes issue 
  def collapse_adjacent_encodings(str)
    super(str.gsub(/(\=\?[^?]+\?([QB])\?)([^?]+?)\?\=\s*(\1([^?]+?)\?\=\s*)+/xmi) do |all|
      header = $1
      type = $2
      inner = all.scan(/\=\?[^?]+\?[QB]\?([^?]+?)\?\=/xmi).join("")
      inner.gsub!("=", "A") if type.upcase == "B"
      header + inner + "?="
    end)
  end
end
class << Mail::Encodings
  prepend MultiByteB64
end

[jeremy]

Current master:

>> Mail.new('Subject: "Subject:=?utf-8?B?0J/QvtC80L7Qs9C40YLQtSDQstC+0YHRgdGC0LDQvdC+0LLQ?= =?utf-8?B?uNGC0Ywg0L/QsNGA0L7Qu9GM?="')['Subject'].to_s
=> "\"Subject:Помогите восстанов��ть пароль\""
>> Mail.new('Subject: "Subject:=?utf-8?B?0J/QvtC80L7Qs9C40YLQtSDQstC+0YHRgdGC0LDQvdC+0LLQuNGC0Ywg0L/QsNGA0L7Qu9GM?="')['Subject'].to_s
=> "\"Subject:Помогите восстановить пароль\""