encodings.rb

Andrey Ni, 2015-01-30 08:45

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# encoding: utf-8
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module Mail
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  # Raised when attempting to decode an unknown encoding type
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  class UnknownEncodingType < StandardError #:nodoc:
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  end
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  module Encodings
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    include Mail::Patterns
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    extend  Mail::Utilities
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    @transfer_encodings = {}
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    # Register transfer encoding
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    #
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    # Example
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    #
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    # Encodings.register "base64", Mail::Encodings::Base64
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    def Encodings.register(name, cls)
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        @transfer_encodings[get_name(name)] = cls
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    end
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    # Is the encoding we want defined?
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    #
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    # Example:
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    #
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    #  Encodings.defined?(:base64) #=> true
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    def Encodings.defined?( str )
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      @transfer_encodings.include? get_name(str)
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    end
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    # Gets a defined encoding type, QuotedPrintable or Base64 for now.
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    #
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    # Each encoding needs to be defined as a Mail::Encodings::ClassName for
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    # this to work, allows us to add other encodings in the future.
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    #
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    # Example:
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    #
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    #  Encodings.get_encoding(:base64) #=> Mail::Encodings::Base64
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    def Encodings.get_encoding( str )
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      @transfer_encodings[get_name(str)]
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    end
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    def Encodings.get_all
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      @transfer_encodings.values
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    end
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    def Encodings.get_name(enc)
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      enc = enc.to_s.gsub("-", "_").downcase
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    end
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    # Encodes a parameter value using URI Escaping, note the language field 'en' can
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    # be set using Mail::Configuration, like so:
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    #
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    #  Mail.defaults do
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    #    param_encode_language 'jp'
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    #  end
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    #
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    # The character set used for encoding will either be the value of $KCODE for
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    # Ruby < 1.9 or the encoding on the string passed in.
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    #
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    # Example:
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    #
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    #  Mail::Encodings.param_encode("This is fun") #=> "us-ascii'en'This%20is%20fun"
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    def Encodings.param_encode(str)
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      case
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      when str.ascii_only? && str =~ TOKEN_UNSAFE
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        %Q{"#{str}"}
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      when str.ascii_only?
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        str
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      else
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        RubyVer.param_encode(str)
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      end
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    end
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    # Decodes a parameter value using URI Escaping.
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    #
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    # Example:
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    #
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    #  Mail::Encodings.param_decode("This%20is%20fun", 'us-ascii') #=> "This is fun"
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    #
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    #  str = Mail::Encodings.param_decode("This%20is%20fun", 'iso-8559-1')
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    #  str.encoding #=> 'ISO-8859-1'      ## Only on Ruby 1.9
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    #  str #=> "This is fun"
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    def Encodings.param_decode(str, encoding)
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      RubyVer.param_decode(str, encoding)
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    end
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    # Decodes or encodes a string as needed for either Base64 or QP encoding types in
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    # the =?<encoding>?[QB]?<string>?=" format.
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    #
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    # The output type needs to be :decode to decode the input string or :encode to
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    # encode the input string.  The character set used for encoding will either be
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    # the value of $KCODE for Ruby < 1.9 or the encoding on the string passed in.
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    #
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    # On encoding, will only send out Base64 encoded strings.
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    def Encodings.decode_encode(str, output_type)
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      case
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      when output_type == :decode
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        Encodings.value_decode(str)
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      else
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        if str.ascii_only?
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          str
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        else
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          Encodings.b_value_encode(str, find_encoding(str))
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        end
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      end
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    end
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    # Decodes a given string as Base64 or Quoted Printable, depending on what
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    # type it is.
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    #
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    # String has to be of the format =?<encoding>?[QB]?<string>?=
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    def Encodings.value_decode(str)
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      # Optimization: If there's no encoded-words in the string, just return it
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      return str unless str =~ /\=\?[^?]+\?[QB]\?[^?]+?\?\=/xmi
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      lines = collapse_adjacent_encodings(str)
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      # Split on white-space boundaries with capture, so we capture the white-space as well
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      lines.map do |line|
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        line.split(/([ \t])/).map do |text|
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          if text.index('=?').nil?
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            text
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          else
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            # Search for occurences of quoted strings or plain strings
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            text.scan(/(                                 # Group around entire regex to include it in matches
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                        \=\?[^?]+\?([QB])\?[^?]+?\?\=    # Quoted String with subgroup for encoding method
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                        |                                # or
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                        .+?(?=\=\?|$)                    # Plain String
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                      )/xmi).map do |matches|
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              string, method = *matches
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              if    method == 'b' || method == 'B'
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                b_value_decode(string)
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              elsif method == 'q' || method == 'Q'
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                q_value_decode(string)
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              else
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                string
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              end
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            end
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          end
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        end
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      end.flatten.join("")
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    end
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    # Takes an encoded string of the format =?<encoding>?[QB]?<string>?=
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    def Encodings.unquote_and_convert_to(str, to_encoding)
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      output = value_decode( str ).to_s # output is already converted to UTF-8
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      if 'utf8' == to_encoding.to_s.downcase.gsub("-", "")
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        output
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      elsif to_encoding
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        begin
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          if RUBY_VERSION >= '1.9'
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            output.encode(to_encoding)
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          else
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            require 'iconv'
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            Iconv.iconv(to_encoding, 'UTF-8', output).first
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          end
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        rescue Iconv::IllegalSequence, Iconv::InvalidEncoding, Errno::EINVAL
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          # the 'from' parameter specifies a charset other than what the text
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          # actually is...not much we can do in this case but just return the
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          # unconverted text.
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          #
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          # Ditto if either parameter represents an unknown charset, like
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          # X-UNKNOWN.
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          output
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        end
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      else
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        output
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      end
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    end
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    def Encodings.address_encode(address, charset = 'utf-8')
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      if address.is_a?(Array)
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        # loop back through for each element
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        address.compact.map { |a| Encodings.address_encode(a, charset) }.join(", ")
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      else
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        # find any word boundary that is not ascii and encode it
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        encode_non_usascii(address, charset) if address
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      end
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    end
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    def Encodings.encode_non_usascii(address, charset)
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      return address if address.ascii_only? or charset.nil?
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      us_ascii = %Q{\x00-\x7f}
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      # Encode any non usascii strings embedded inside of quotes
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      address = address.gsub(/(".*?[^#{us_ascii}].*?")/) { |s| Encodings.b_value_encode(unquote(s), charset) }
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      # Then loop through all remaining items and encode as needed
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      tokens = address.split(/\s/)
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      map_with_index(tokens) do |word, i|
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        if word.ascii_only?
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          word
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        else
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          previous_non_ascii = i>0 && tokens[i-1] && !tokens[i-1].ascii_only?
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          if previous_non_ascii #why are we adding an extra space here?
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            word = " #{word}"
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          end
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          Encodings.b_value_encode(word, charset)
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        end
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      end.join(' ')
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    end
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    # Encode a string with Base64 Encoding and returns it ready to be inserted
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    # as a value for a field, that is, in the =?<charset>?B?<string>?= format
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    #
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    # Example:
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    #
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    #  Encodings.b_value_encode('This is あ string', 'UTF-8')
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    #  #=> "=?UTF-8?B?VGhpcyBpcyDjgYIgc3RyaW5n?="
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    def Encodings.b_value_encode(encoded_str, encoding = nil)
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      return encoded_str if encoded_str.to_s.ascii_only?
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      string, encoding = RubyVer.b_value_encode(encoded_str, encoding)
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      map_lines(string) do |str|
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        "=?#{encoding}?B?#{str.chomp}?="
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      end.join(" ")
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    end
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    # Encode a string with Quoted-Printable Encoding and returns it ready to be inserted
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    # as a value for a field, that is, in the =?<charset>?Q?<string>?= format
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    #
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    # Example:
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    #
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    #  Encodings.q_value_encode('This is あ string', 'UTF-8')
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    #  #=> "=?UTF-8?Q?This_is_=E3=81=82_string?="
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    def Encodings.q_value_encode(encoded_str, encoding = nil)
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      return encoded_str if encoded_str.to_s.ascii_only?
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      string, encoding = RubyVer.q_value_encode(encoded_str, encoding)
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      string.gsub!("=\r\n", '') # We already have limited the string to the length we want
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      map_lines(string) do |str|
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        "=?#{encoding}?Q?#{str.chomp.gsub(/ /, '_')}?="
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      end.join(" ")
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    end
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    private
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    # Decodes a Base64 string from the "=?UTF-8?B?VGhpcyBpcyDjgYIgc3RyaW5n?=" format
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    #
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    # Example:
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    #
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    #  Encodings.b_value_decode("=?UTF-8?B?VGhpcyBpcyDjgYIgc3RyaW5n?=")
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    #  #=> 'This is あ string'
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    def Encodings.b_value_decode(str)
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      RubyVer.b_value_decode(str)
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    end
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    # Decodes a Quoted-Printable string from the "=?UTF-8?Q?This_is_=E3=81=82_string?=" format
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    #
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    # Example:
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    #
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    #  Encodings.q_value_decode("=?UTF-8?Q?This_is_=E3=81=82_string?=")
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    #  #=> 'This is あ string'
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    def Encodings.q_value_decode(str)
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      RubyVer.q_value_decode(str)
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    end
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    def Encodings.split_encoding_from_string( str )
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      match = str.match(/\=\?([^?]+)?\?[QB]\?(.+)?\?\=/mi)
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      if match
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        match[1]
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      else
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        nil
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      end
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    end
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    def Encodings.find_encoding(str)
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      RUBY_VERSION >= '1.9' ? str.encoding : $KCODE
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    end
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    # Gets the encoding type (Q or B) from the string.
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    def Encodings.split_value_encoding_from_string(str)
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      match = str.match(/\=\?[^?]+?\?([QB])\?(.+)?\?\=/mi)
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      if match
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        match[1]
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      else
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        nil
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      end
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    end
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    # When the encoded string consists of multiple lines, lines with the same
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    # encoding (Q or B) can be joined together.
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    #
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    # String has to be of the format =?<encoding>?[QB]?<string>?=
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    def Encodings.collapse_adjacent_encodings(str)
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      lines = str.split(/(\?=)\s*(=\?)/).each_slice(2).map(&:join)
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      results = []
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      previous_encoding = nil
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      lines.each do |line|
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        encoding = split_value_encoding_from_string(line)
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        if encoding == previous_encoding
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          line = results.pop + line
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    #     line.gsub!(/\?\=\=\?.+?\?[QqBb]\?/m, '')
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        end
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        previous_encoding = encoding
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        results << line
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      end
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      results
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    end
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  end
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end