Date: Wed, 05 Feb 1997 01:49:00 +0000 From: Brian Somers <brian@awfulhak.demon.co.uk> To: "Brian Somers" <brian@utell.co.uk> Cc: "Charles Mott" <cmott@srv.net>, "Julian Elischer" <julian@whistle.com>, "Eivind Eklund" <eivind@dimaga.com>, "Ari Suutari" <ari.suutari@ps.carel.fi>, hackers@freebsd.org Subject: Re: Single socket version of natd Message-ID: <199702050149.BAA29882@awfulhak.demon.co.uk> In-Reply-To: Your message of "Tue, 04 Feb 1997 18:37:30 GMT." <199702041837.SAA02367@ui-gate.utell.co.uk>
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> I don't know specifically without checking the code, but I recall seeing a
> comment in the -current sources (I've just checked SNAP-961014, nothing
> about it there) about using the ip_sum to differentiate between incoming
> and outgoing packets..... It *WAS* commented as being a HACK :(
>
> I'll check the code out this evening when I get home (-current machine)
> and tell you.
[.....]
I was lying. There's no such comments !
Does anyone know of a reason (besides the divert(4) man page) that the
sum on incoming packets is zero'd ?
The code says:
[.....]
if (hlen == sizeof(struct ip)) {
ip->ip_sum = in_cksum_hdr(ip);
} else {
ip->ip_sum = in_cksum(m, hlen);
}
if (ip->ip_sum) {
ipstat.ips_badsum++;
goto bad;
}
[.....]
Is there any problems with changing this to
u_short sum;
.....
if (hlen == sizeof(struct ip)) {
sum = in_cksum_hdr(ip);
} else {
sum = in_cksum(m, hlen);
}
if (sum) {
ipstat.ips_badsum++;
goto bad;
}
(and updating divert(4)) ?
--
Brian <brian@awfulhak.demon.co.uk>, <brian@freebsd.org>
<http://www.awfulhak.demon.co.uk/>;
Don't _EVER_ lose your sense of humour....
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