ietf-mta-filters
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Re: Matching NUL characters

2003-04-04 02:58:17

[michael(_at_)freenet-ag(_dot_)de]:

  > I suggest you propose an extension.  an implementation that follows
  > the current RFC should not be rendered incompatible.
  
  I thought about an extension, too, but what should be the result
  of the following two matches (as specified by the RFC) given
  those comparisons, if we have the header
  
    Subject: =?iso-8859-1?q?abc=00def?=
  
  and the tests:
  
    header :contains ["Subject"] ["abc"]
    header :contains ["Subject"] ["def"]
    header :matches ["Subject"] ["abc?def"]
  
  An implementation that evaluates the second or third test as false
  is broken, isn't it?

granted.  good example.

  > if you want the "\0" escape, you can't express U+ef followed by zero.
  >
  >   \uef\0 => U+ef NUL
  >
  > "\u0" is so short "\0" is superfluous.  the number of escapes
  > should be kept to a minimum.
  
  Not entirely.  RFC 3028 allows not to implement UTF-8 comparisons,
  which means the input script may be in UTF-8, but the
  implementation is not aware of that, and it makes no sense to use
  anything but ASCII characters in that case.

I don't believe this is true.  every implementation must understand
that the sequence of N octets making up one UTF-8 character is _one_
character, not N.

  That allows a simple implementation and such an implementation
  probably would not understand \u escapes, but it still requires \0
  to encode the NUL character.

I don't agree.  and I still think that to change the backslash, you
need to make an extension.

-- 
Kjetil T.                       |  read and make up your own mind
                                |  http://www.cactus48.com/truth.html

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