Am 2024-01-30 23:56, schrieb Jonas Vautherin via Postfix-users:
...
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Somehow the date first appears as "Fri, 05 Jan 2024 16:48:38 -0500",
and then as
"Fri, 5 Jan 2024 16:48:37 -0500 (EST)". Note that the '0' was replaced
by a
white space, ending up with two white spaces between "Fri," and "5
Jan". If this
is a valid date format, then I need to contribute a fix in isync. But
is it
valid?
I tried to find the specifications for a date, and ended up on RFC5322
[2],
which defines:
```
date-time = [ day-of-week "," ] date time [CFWS]
```
To me, this looks like only one white space is allowed between `[
day-of-week
"," ]` and `date`.
No, that is a wrong interpretation: day-of-week, ",", date, time, CFWS
are all syntatic tokens and [] means optional. The blanks between the
tokens do not belong to the syntax. If you generate a date-time with all
optional fields it would be
day-of-week,datetimeCFWS
without any blanks. Blanks could only be there if the tokens itself
include blank(s).
Therefore you have to look for the definition of each token. In this
case the definition of date is relevant:
date = day month year
This means date is build of three tokens: day, month, year. Let's look
at day:
day = ([FWS] 1*2DIGIT FWS) / obs-day
This says a day can consist of one or two digits preceded by an optional
folding white space (FWS):
FWS = ([*WSP CRLF] 1*WSP) / obs-FWS
A FWS can be a single WSP or a folded line.
Therefore the date "Fri, 5 Jan 2024 16:48:37 -0500 (EST)" is
syntactically incorrect, because there can be only one blank between ","
and "5", not two by the syntax of RFC 5322. However, if you look at the
obs-*** definitions, they allow multiple WSPs which should not be
generated by new software. But a parser should be able to handle
multiple blanks.
Hope this helps.
Michael
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