Alexey Melnikov wrote:
RFC 821 allowed for space characters (0x20) in local part of
email addresses, but RFC 2821 and 2821bis don't allow for that
| <quoted-string> ::= """ <qtext> """
| <qtext> ::= "\" <x> | "\" <x> <qtext> | <q> | <q> <qtext>
| <q> ::= any one of the 128 ASCII characters except <CR>, <LF>,
| quote ("), or backslash (\)
That allowed NO-WS-CTL, SP, and even NUL in a <quoted-string>
outside of a <quoted-pair>, we obviously don't want it "as is".
Quoted-string = DQUOTE *qcontent DQUOTE
qtext = NO-WS-CTL / ; Non white space controls
%d33 / ; The rest of the US-ASCII
%d35-91 / ; characters not including "\"
%d93-126 ; or the quote character
qcontent = qtext / quoted-pair
Right, no SP outside of <quoted-pair>. You can still have SP
within <quoted-pair>, at the moment (2822upd-03):
| quoted-pair = ("\" text) / obs-qp
| text = %d1-9 / ; Characters excluding CR
| %d11 / ; and LF
| %d12 /
And with <obs-qp> anything down to NUL goes :-( Fiddling with
SP is very critical, it could break RFC 2821 implementations.
Whatever 2821bis will do, that needs a fat *caveat* somewhere.
And it has to be in sync with 2822upd, we can't have different
approaches in 2821bis and 2822upd for a local part <shudder />
Prohibition of spaces in quoted parts breaks gatewaying
to/from X.400 (MIXER, RFC 2156).
RFC 2156 is still based on 822 (STD 11), it has to be updated
for future full "2821ter/2822fin" standards. In 2156 4.3.4:
| 2. If the 822.local-part uses the 822.quoted-string encoding,
| remove this quoting. If the resulting unquoted
| 822.local-part has leading space, trailing space, or two
| adjacent spaces go to stage II.
Apparently X.400 can do single embedded spaces in "stage I".
I don't see in 4.3.4 where they deal with any <quoted-pair>s,
how is that supposed to work ? There's no backslash in 3.3.3
<printablestring>, and no abbreviation in 3.4 <ps-encoded>, a
backslash might end up as "(092)".
Anyway, it is possible to use space in a <quoted-pair> on the
RFC 822 side, isn't that good enough for MIXER ? IOW, who is
planning to update their MIXER implementation for 2821/2822,
or better for 2821bis/2822upd ?
2821 and 2821bis have a clear "stay away from quoted-string"
SHOULD at the end of 4.1.2, with text indicating that this is
as near to a MUST as possible without explicitly saying so.