Problems with INN-2.2.3 and SuSE6.4

Michael Stassen stassenm at indiana.edu
Tue Dec 12 19:18:13 UTC 2000

```
Note that the descriptions in the comments do not match the actions taken
in the code.  That is, the check for 4-digits in the if is actually a
check for 3 digits, and the ugly function in the else does not add
1900.  This should be our first clue...

I believe this is a Y2K bug introduced to fix a Y2K bug...

As I understand it, there are two separate problems to account for:

1) NNTP specifies two digits for the year (clearly a problem), but many
servers and clients ignore this and use 4 digits (sensible).  INN
should correctly handle either case.

2) A common programming mistake is (was?) to assume that tm->tm_year is
the two digit year, rather than the years since 1900.  Hence, some
programs get 100 for 2000, 101 for 2001, etc.  Arguably, INN should
handle this as well.

I believe the ugly function in the else is an attempt to apply the
"window" solution to the two-digit year problem.  That is, if \$4 is in the
range 50 to 99, we assume 19xx, but if \$4 is in the range 00 to 49, we
assume 20xx.  The formula given, however, doesn't get this right unless
yyYear = 1999.  For example, if yyYear = 2000, values of \$4 in the range
01 to 50 become 19xx and values of \$4 in the range 51 to 99 become 18xx.
Only \$4 = 00 correctly translates to 2000 when yyYear is 2000!

I suspect it would be preferable to have the code explicitly match the
intent.  Also, as a practical matter, I assume there is no reason for INN
to believe \$4 is less than 1970, so 70 might be a better window cutoff
than 50.  Assuming I've correctly diagnosed the intent, here's my
suggested replacement:

if (\$4 > 999) /* in practice, \$4 >1969 would be just as good */
{
/* \$4 is YYYY, use as is */
yyYear = \$4;
}
else if (\$4 < 70)
{
/* \$4 is YY in the range 00 to 69, assume 20xx */
yyYear = 2000 + \$4;
}
else
{
/* \$4 is either YY in the range 70 to 99, or YYY (we assume 1YY),
so add 1900 */
yyYear = 1900 + \$4;
}

Of course, this doesn't handle pathological cases (\$4 < 0 or \$4 = 765,
say), but then neither does the code to be replaced.  I assume that's
handled elsewhere?  Also, when 2070 rolls around, this code will treat 70
as 1970 instead of 2070, but the assumption of the window solution is that
by then we will either no longer be receiving 2 digit years, or we will
move the window forward (or we won't be using this code).

Michael Stassen
Support Center
University Information Technology Services
Indiana University Bloomington
stassenm at indiana.edu

On 10 Dec 2000, Russ Allbery wrote:

>
> Christian Renner <stooge at josua.ithnet.com> writes:
>
> > Any idea: is there any chance of making INN 2.2.3 or above accept news
> > that come with a date header of "8 Dec 100 21:39:00 +0100" ???
>
> Hm.  Looking at parsedate.y in 2.3, there are actually a whole bunch of
> places that should be handling this:
>
>             if (\$4 > 100) {
>                 /* assume year is YYYY format, so need not to add 1900 */
>                 yyYear = \$4;
>             } else {
>                 /* assume year is YY format, so need to add 1900 */
>                 yyYear = \$4 + (yyYear / 100 + (yyYear % 100 - \$4) / 50) * 100;
>             }
>
> I'm not sure why it's not doing what you want.  Hurm.  Although I also
> have no idea what that formula is really doing, since it's not obviously
> just adding 1900.
>
> --
> Russ Allbery (rra at stanford.edu)             <http://www.eyrie.org/~eagle/>
>
>

```

More information about the inn-workers mailing list