Module: Sisimai::RFC2045

Defined in:
lib/sisimai/rfc2045.rb

Overview

Sisimai::RFC2045 is a MIME Utilities for Sisimai.

Class Method Summary collapse

Class Method Details

.boundary(argv0 = '', start = -1)) ⇒ String

Get a boundary string

Parameters:

  • argv0 (String) (defaults to: '') —

    The value of Content-Type header

  • start (Integer) (defaults to: -1)) —

    -1: boundary string itself 0: Start of boundary 1: End of boundary

Returns:

  • (String) —

    Boundary string



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# File 'lib/sisimai/rfc2045.rb', line 127

def boundary(argv0 = '', start = -1)
  return "" if argv0.empty?
  btext = parameter(argv0, 'boundary')
  return '' if btext.empty?

  # Content-Type: multipart/mixed; boundary=Apple-Mail-5--931376066
  # Content-Type: multipart/report; report-type=delivery-status;
  #    boundary="n6H9lKZh014511.1247824040/mx.example.jp"
  btext = '--' + btext if start > -1
  btext = btext + '--' if start >  0
  return btext
end

.decodeB(argv0 = nil) ⇒ String

Decode MIME BASE64 Encoded string

Parameters:

  • argv0 (String) (defaults to: nil) —

    MIME Encoded text

Returns:

  • (String) —

    MIME-Decoded text



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# File 'lib/sisimai/rfc2045.rb', line 88

def decodeB(argv0 = nil)
  return "" if argv0.nil? || argv0.empty?

  p = nil
  if cv = argv0.match(%r|([+/\=0-9A-Za-z\r\n]+)|) then p = Base64.decode64(cv[1]) end
  return p ? p.scrub('?') : ""
end

.decodeH(argvs = []) ⇒ String

Decode MIME-Encoded string in an email header

Parameters:

  • argvs (Array) (defaults to: []) —

    An array including MIME-Encoded text

Returns:

  • (String) —

    MIME-Decoded text



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# File 'lib/sisimai/rfc2045.rb', line 36

def decodeH(argvs = [])
  ctxcharset = nil
  qbencoding = nil
  textblocks = []

  while e = argvs.shift do
    # Check and decode each element
    e = e.strip.delete('"')

    if self.is_encoded(e)
      # MIME Encoded string like "=?utf-8?B?55m954yr44Gr44KD44KT44GT?="
      next unless cv = e.match(/\A(.*)=[?]([-_0-9A-Za-z]+)[?]([BbQq])[?](.+)[?]=?(.*)\z/)

      ctxcharset ||= cv[2]
      qbencoding ||= cv[3]
      notdecoded   = cv[4]

      textblocks << cv[1]
      textblocks << if qbencoding.upcase == 'B'
                        Base64.decode64(notdecoded)
                      else
                        notdecoded.unpack('M').first
                      end
      textblocks[-1].gsub!(/\r\n/, '')
      textblocks << cv[5]
    else
      textblocks << if textblocks.empty? then e else " #{e}" end
    end
  end
  return '' if textblocks.empty?

  p = textblocks.join('')
  if ctxcharset && qbencoding
    # utf8 => UTF-8
    ctxcharset = 'UTF-8' if ctxcharset.casecmp('UTF8') == 0

    if ctxcharset.casecmp('UTF-8') != 0
      # Characterset is not UTF-8
      begin
        p = p.encode!('UTF-8', ctxcharset)
      rescue
        p = 'FAILED TO CONVERT THE SUBJECT'
      end
    end
  end
  q = p.dup
  return q.force_encoding('UTF-8').scrub('?')
end

.decodeQ(argv0 = nil) ⇒ String

Decode MIME Quoted-Printable Encoded string

Parameters:

  • argv0 (String) (defaults to: nil) —

    MIME Encoded text

Returns:

  • (String) —

    MIME Decoded text



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# File 'lib/sisimai/rfc2045.rb', line 99

def decodeQ(argv0 = nil)
  return "" if argv0.nil? || argv0.empty?
  return argv0.unpack('M').first.scrub('?')
end

.haircut(block = '', heads = false) ⇒ Array

Cut header fields except Content-Type, Content-Transfer-Encoding from multipart/* block

Parameters:

  • block (String) (defaults to: '') —

    multipart/* block text

  • heads (Boolean) (defaults to: false) —

    true = Returns only Content-(Type|Transfer-Encoding) headers

Returns:

  • (Array) —

    Two headers and body part of multipart/* block

Since:

  • v5.0.0



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# File 'lib/sisimai/rfc2045.rb', line 145

def haircut(block = '', heads = false)
  return nil if block.empty?

  (upperchunk, lowerchunk) = block.split("\n\n", 2)
  return ['', ''] if upperchunk.nil? || upperchunk.empty? || lowerchunk.nil?
  return ['', ''] if upperchunk.index('Content-Type').nil?

  headerpart = ['', ''] # ["text/plain; charset=iso-2022-jp; ...", "quoted-printable"]
  multipart1 = []       # [headerpart, "body"]

  upperchunk.split("\n").each do |e|
    # Remove fields except Content-Type:, and Content-Transfer-Encoding: in each part of 
    # multipart/* block such as the following:
    #   Date: Thu, 29 Apr 2018 22:22:22 +0900
    #   MIME-Version: 1.0
    #   Message-ID: ...
    #   Content-Transfer-Encoding: quoted-printable
    #   Content-Type: text/plain; charset=us-ascii
    if e.index('Content-Type:') == 0
      # Content-Type: ***
      v = e.split(' ', 2)[-1]
      headerpart[0] = v.index('boundary=') ? v : v.downcase

    elsif e.index('Content-Transfer-Encoding:') == 0
      # Content-Transfer-Encoding: ***
      headerpart[1] = e.split(' ', 2)[-1].downcase

    elsif e.index('boundary=') || e.index('charset=')
      # "Content-Type" field has boundary="..." or charset="utf-8"
      next if headerpart[0].empty?
      headerpart[0] += " #{e}"
      headerpart[0]  = headerpart[0].gsub(/\s\s+/, ' ')
    end
  end
  return headerpart if heads

  mediatypev = headerpart[0].downcase
  ctencoding = headerpart[1]
  multipart1 = headerpart << ''

  while true do
    # Check the upper block: Make a body part at the 2nd element of multipart1
    multipart1[2] = sprintf("Content-Type: %s\n", headerpart[0])

    # Do not append Content-Transfer-Encoding: header when the part is the original message:
    # Content-Type is message/rfc822 or text/rfc822-headers, or message/delivery-status, or
    # message/feedback-report
    break if mediatypev.index('/rfc822')
    break if mediatypev.index('/delivery-status')
    break if mediatypev.index('/feedback-report')
    break if ctencoding.empty?

    multipart1[2] += sprintf("Content-Transfer-Encoding: %s\n", ctencoding)
    break
  end

  while true do
    # Append LF before the lower chunk into the 2nd element of multipart1
    break if lowerchunk.empty?
    break if lowerchunk[0, 1] == "\n"

    multipart1[2] += "\n"
    break
  end
  multipart1[2] += lowerchunk
  return multipart1
end

.is_encoded(argv1) ⇒ Boolean

Check that the argument is MIME-Encoded string or not

Parameters:

  • argvs (String) —

    String to be checked

Returns:

  • (Boolean) —

    false: Not MIME encoded string, true: MIME encoded string



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# File 'lib/sisimai/rfc2045.rb', line 11

def is_encoded(argv1)
  return false if argv1.nil? || argv1.empty?

  text1 = argv1.delete('"')
  mime1 = false
  piece = []

  if text1.include?(' ')
    # Multiple MIME-Encoded strings in a line
    piece = text1.split(' ')
  else
    piece << text1
  end

  while e = piece.shift do
    # Check all the string in the array
    next unless e =~ /[ \t]*=[?][-_0-9A-Za-z]+[?][BbQq][?].+[?]=?[ \t]*/
    mime1 = true
  end
  return mime1
end

.levelout(argv0 = '', argv1 = '') ⇒ Array

Split argv1: multipart/* blocks by a boundary string in argv0

Parameters:

  • argv0 (String) (defaults to: '') —

    The value of Content-Type header

  • argv1 (String) (defaults to: '') —

    A pointer to multipart/* message blocks

Returns:

  • (Array) —

    List of each part of multipart/*

Since:

  • v5.0.0



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# File 'lib/sisimai/rfc2045.rb', line 218

def levelout(argv0 = '', argv1 = '')
  return [] if argv0.empty?
  return [] if argv1.empty?

  boundary01 = boundary(argv0, 0); return [] if boundary01.empty?
  multiparts = argv1.split(Regexp.new(Regexp.escape(boundary01) + "\n"))
  partstable = []

  # Remove empty or useless preamble and epilogue of multipart/* block
  multiparts.shift if multiparts[0].size < 8
  return []        if multiparts.empty?
  multiparts.pop   if multiparts.size > 2 && multiparts[-1].size < 8

  while e = multiparts.shift do
    # Check each part and breaks up internal multipart/* block
    f = haircut(e)
    if f[0].index('multipart/')
      # There is nested multipart/* block
      boundary02 = boundary(f[0], -1); next if boundary02.empty?
      bodyinside = f[-1].split("\n\n", 2)[-1]
      next if bodyinside.size < 9 || bodyinside.index(boundary02).nil?

      v = levelout(f[0], bodyinside)
      partstable += v if v.size > 0
    else
      # The part is not a multipart/* block
      b = f[-1].size > 0 ? f[-1] : e
      v = [f[0], f[1], f[0].size > 0 ? b.split("\n\n", 2)[-1] : b]
      partstable << v
    end
  end
  return [] if partstable.empty?

  # Remove $boundary01.'--' and strings from the boundary to the end of the body part.
  boundary01.chomp!
  b = partstable[-1][2]
  p = b.index(boundary01 + '--')
  b[p, b.size] = "" if p

  return partstable
end

.makeflat(argv0 = '', argv1 = '') ⇒ String

Make flat multipart/* part blocks and decode

Parameters:

  • argv0 (String) (defaults to: '') —

    The value of Content-Type header

  • argv1 (String) (defaults to: '') —

    A pointer to multipart/* message blocks

Returns:



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# File 'lib/sisimai/rfc2045.rb', line 264

def makeflat(argv0 = '', argv1 = '')
  return "" if argv0.nil? || argv1.nil?
  return "" if argv0.downcase.index('multipart/') == false || argv0.downcase.index('boundary=') == false

  # Some bounce messages include lower-cased "content-type:" field such as the followings:
  #   - content-type: message/delivery-status        => Content-Type: message/delivery-status
  #   - content-transfer-encoding: quoted-printable  => Content-Transfer-Encoding: quoted-printable
  #   - CHARSET=, BOUNDARY=                          => charset-, boundary=
  #   - message/xdelivery-status                     => message/delivery-status
  iso2022set = %r/charset=["']?(iso-2022-[-a-z0-9]+)['"]?\b/
  multiparts = levelout(argv0, argv1)
  flattenout = ''
  delimiters = ["/delivery-status", "/rfc822", "/feedback-report", "/partial"]

  while e = multiparts.shift do
    # Pick only the following parts Sisimai::Lhost will use, and decode each part
    #   - text/plain, text/rfc822-headers
    #   - message/delivery-status, message/rfc822, message/partial, message/feedback-report
    istexthtml = false
    mediatypev = parameter(e[0]); mediatypev = "text/plain" if mediatypev.empty?
    next if mediatypev.start_with?('text/', 'message/') == false

    if mediatypev == 'text/html'
      # Skip text/html part when the value of Content-Type: header in an internal part of
      # multipart/* includes multipart/alternative;
      next if argv0.index('multipart/alternative')
      istexthtml = true
    end

    ctencoding = e[1]
    bodyinside = e[2]
    bodystring = ''

    if ctencoding.size > 0
      # Check the value of Content-Transfer-Encoding: header
      if ctencoding == 'base64'
        # Content-Transfer-Encoding: base64
        bodystring = decodeB(bodyinside) || ''
        dontappend = false; while first10 = bodystring[0,10] do
          # Don't pick the decoded part as an error message when the part is
          # - BASE64 encoded.
          # - the value of the charset is not utf-8.
          # - NOT a plain text.
          break if     Sisimai::String.aligned(e[0], ['charset', '=', 'utf-8'])
          break unless first10 =~ /[\x00-\x08\x0E-\x1F\x7F-]/
          dontappend = true; break
        end
        next if dontappend

      elsif ctencoding == 'quoted-printable'
        # Content-Transfer-Encoding: quoted-printable
        bodystring = decodeQ(bodyinside) || ''

      elsif ctencoding == '7bit'
        # Content-Transfer-Encoding: 7bit
        if cv = e[0].downcase.match(iso2022set)
          # Content-Type: text/plain; charset=ISO-2022-JP
          bodystring = Sisimai::String.to_utf8(bodyinside, cv[1])
        else
          # No "charset" parameter in the value of Content-Type: header
          bodystring = bodyinside
        end
      else
        # Content-Transfer-Encoding: 8bit, binary, and so on
        bodystring = bodyinside
      end

      if istexthtml
        # Try to delete HTML tags inside of text/html part whenever possible
        bodystring = Sisimai::String.to_plain(bodystring)
      end
      next if bodystring.empty?

      # The body string will be encoded to UTF-8 forcely and call String#scrub method to avoid
      # the following errors:
      #   - incompatible character encodings: ASCII-8BIT and UTF-8
      #   - invalid byte sequence in UTF-8
      if bodystring.encoding.to_s != 'UTF-8'
        # ASCII-8BIT or other 8bit encodings
        ctxcharset = parameter(e[0], 'charset')
        if ctxcharset.empty?
          # The part which has no "charset" parameter causes an ArgumentError: invalid byte
          # sequence in UTF-8 so String#scrub should be called
          bodystring.scrub!('?')
        else
          # ISO-8859-1, GB2312, and so on
          bodystring = Sisimai::String.to_utf8(bodystring, ctxcharset)
        end
        bodystring += "\n\n"
      end

      bodystring.gsub!(/\r\n/, "\n") if bodystring.include?("\r\n") # Convert CRLF to LF

    else
      # There is no Content-Transfer-Encoding header in the part
      be = bodyinside.encoding.to_s
      bodyinside  = Sisimai::String.to_utf8(bodyinside, be) if be != 'UTF-8' 
      bodystring += bodyinside
    end

    if delimiters.any? { |a| mediatypev.include?(a) }
      # Add Content-Type: header of each part (will be used as a delimiter at Sisimai::Lhost)
      # into the body inside when the value of Content-Type: field is message/delivery-status,
      # message/rfc822, or text/rfc822-headers
      bodystring = sprintf("Content-Type: %s\n%s", mediatypev, bodystring)
    end

    # Append "\n" when the last character of $bodystring is not LF
    bodystring += "\n\n" if bodystring[-2, 2] != "\n\n"
    flattenout += bodystring
  end

  return flattenout
end

.parameter(argv0 = '', argv1 = '') ⇒ String

Find a value of specified field name from Content-Type: header

Parameters:

  • argv0 (String) (defaults to: '') —

    The value of Content-Type: header

  • argv1 (String) (defaults to: '') —

    Lower-cased attribute name of the parameter

Returns:

  • (String) —

    The value of the parameter

Since:

  • v5.0.0



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# File 'lib/sisimai/rfc2045.rb', line 109

def parameter(argv0 = '', argv1 = '')
  return "" if argv0.empty?
  parameterq = argv1.size > 0 ? argv1 + '=' : ''
  paramindex = argv1.size > 0 ? argv0.index(parameterq) : 0; return '' if paramindex.nil?

  # Find the value of the parameter name specified in argv1
  foundtoken = argv0[paramindex + parameterq.size, argv0.size].split(';', 2)[0] || ''
  foundtoken = foundtoken.downcase if argv1 != 'boundary'
  foundtoken = foundtoken.delete('"').delete("'")
  return foundtoken
end