On Tue, 30 Jul 2002, bert hubert wrote:
> On Tue, Jul 30, 2002 at 05:31:44PM +0400, kuznet@xxxxxxxxxxxxx wrote:
>
> > Well, try to prove that corrupted packet is really received by application.
> > This is not useless work, in any case, you have to cure this place,
> > it should not abort because of invalid data. :-)
>
> We fixed the bug already :-) Signed/unsigned arithmetic problems.
Were the arithmetic problems in your code, or the kernels checksumming?
(The latter seems unlikely.)
> I have six examples in my log of PowerDNS exiting just after receiving a
> packet with a broken checksum.
Wouldn't this have also happened with valid checksums and invalid data?
This is a good time to fix your application data validity checking.
Note that some network equipment will re-write the IP checksums, just as
some equipment regenerates the link-level frame CRC. It's not
semantically correct, but claiming that such devices don't exist doesn't
make them go away.
--
Donald Becker becker@xxxxxxxxx
Scyld Computing Corporation http://www.scyld.com
410 Severn Ave. Suite 210 Second Generation Beowulf Clusters
Annapolis MD 21403 410-990-9993
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