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Module: Net::IMAP::StringPrep

Overview

Regexps and utility methods for implementing stringprep profiles. The StringPrep algorithm is defined by RFC-3454. Each codepoint table defined in the RFC-3454 appendices is matched by a Regexp defined in this module.

Class Method Summary

Class Method Details

.[](table)

Returns a Regexp matching the given table name.

[ GitHub ] 

  


# File 'lib/net/imap/stringprep.rb', line 49



def self.[](table)
  Tables::REGEXPS.fetch(table)
end


  








  

    .check_bidi!(string, c_8: false, profile: nil)   (mod_func)
  



  

    

Checks that string obeys all of the “Bidirectional Characters” requirements in RFC-3454, §6:


  • 

    The characters in StringPrep MUST be prohibited
    

  • 

    If a string contains any RandALCat character, the string MUST NOT contain any LCat character.
    

  • 

    If a string contains any RandALCat character, a RandALCat character MUST be the first character of the string, and a RandALCat character MUST be the last character of the string.
    




This is usually combined with #check_prohibited!, so table “C.8” is only checked when c_8: true.



Raises either StringPrep::ProhibitedCodepoint or StringPrep::BidiStringError unless all requirements are met.  profile is an optional string which will be added to any exception that is raised (it does not affect behavior).


  



  [ GitHub ]


  

  


# File 'lib/net/imap/stringprep.rb', line 144



def check_bidi!(string, c_8: false, profile: nil)
  check_prohibited!(string, "C.8", profile: profile) if c_8
  if Tables::BIDI_FAILS_REQ2.match?(string)
    raise BidiStringError.new(
      Tables::BIDI_DESC_REQ2, string: string, profile: profile,
    )
  elsif Tables::BIDI_FAILS_REQ3.match?(string)
    raise BidiStringError.new(
      Tables::BIDI_DESC_REQ3, string: string, profile: profile,
    )
  end
end


  








  

    .check_prohibited!(string, *tables, bidi: false, unassigned: "A.1", stored: false, profile: nil)   (mod_func)
  



  

    

Checks string for any codepoint in tables. Raises a StringPrep::ProhibitedCodepoint describing the first matching table.



Also checks bidirectional characters, when bidi: true, which may raise a StringPrep::BidiStringError.



profile is an optional string which will be added to any exception that is raised (it does not affect behavior).


  



  [ GitHub ]


  

  


# File 'lib/net/imap/stringprep.rb', line 104



def check_prohibited!(string,
                      *tables,
                      bidi: false,
                      unassigned: "A.1",
                      stored: false,
                      profile: nil)
  tables  = Tables::TITLES.keys.grep(/^C/) if tables.empty?
  tables |= [unassigned] if stored
  tables |= %w[C.8] if bidi
  table   = tables.find {|t|
    case t
    when String then Tables::REGEXPS.fetch(t).match?(string)
    when Regexp then t.match?(string)
    else raise ArgumentError, "only table names and regexps can be checked"
    end
  }
  if table
    raise ProhibitedCodepoint.new(
      table, string: string, profile: profile
    )
  end
  check_bidi!(string, profile: profile) if bidi
end


  








  

    .map_tables!(string, *tables)   (mod_func)
  

  [ GitHub ]


  

  


# File 'lib/net/imap/stringprep.rb', line 88



def map_tables!(string, *tables)
  tables.each do |table|
    regexp, replacements = Tables::MAPPINGS.fetch(table)
    string.gsub!(regexp, replacements)
  end
  string
end


  








  

    .stringprep(string, maps:, normalization:, prohibited:, **opts)   (mod_func)
  



  

    

  1. 

    Map – For each character in the input, check if it has a mapping and, if so, replace it with its mapping.  This is described in section 3.
    

  2. 

    Normalize – Possibly normalize the result of step 1 using Unicode normalization.  This is described in section 4.
    

  3. 

    Prohibit – Check for any characters that are not allowed in the output.  If any are found, return an error.  This is described in section 5.
    

  4. 

    Check bidi – Possibly check for right-to-left characters, and if any are found, make sure that the whole string satisfies the requirements for bidirectional strings.  If the string does not satisfy the requirements for bidirectional strings, return an error.  This is described in section 6.
    




The above steps MUST be performed in the order given to comply with this specification.




  



  [ GitHub ]


  

  


# File 'lib/net/imap/stringprep.rb', line 76



def stringprep(string,
               maps:,
               normalization:,
               prohibited:,
               **opts)
  string = string.encode("UTF-8") # also dups (and raises invalid encoding)
  map_tables!(string, *maps)                     if maps
  string.unicode_normalize!(normalization)       if normalization
  check_prohibited!(string, *prohibited, **opts) if prohibited
  string
end