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Re: MIME boundary question recap

1995-02-10 16:36:01
schaefer(_at_)z-code(_dot_)com (Barton E. Schaefer) writes:
Right; that is, the lookahead problem occurs only when there are an
arbitrary number of whitespace characters following a successful prefix
match against a boundary string.  Any prefix match followed by a non-
whitespace character is clearly not a match (so perhaps metamail is
already "broken" by any interpretation).

However, if a prefix match is not permitted in the enclosing
body-part, then a prefix match followed by a non-whitespace character
(other than "--") is a syntax error.  A MIME parser is then free to
interpret the outer multipart however it wants, including parsing the
prefix match as a delimiter nonterminal and putting the non-whitespace
character in an error recovery nonterminal.

Brent Stilley <UCCXBRS(_at_)vm1(_dot_)ucc(_dot_)okstate(_dot_)edu> writes:
The only argument I can see for allowing trailing whitespace in a boundary
is the fact that they are allowed to be defined in quotes.

Both the text of 1521 section 7.2.1 and the syntax for the "boundary"
nonterminal prohibit the value of the "boundary" parameter from ending
with whitespace.

The text states that if a boundary (presumably it really means a
"delimiter" or "close-delimiter" line) appears to end with white
space, the white space must be presumed to have been added by a
gateway and must be deleted (presumably it means "must be ignored").

_.John G. Myers         Internet: jgm+(_at_)CMU(_dot_)EDU
                        LoseNet:  ...!seismo!ihnp4!!give!up

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