Date: Wed, 30 Aug 2000 05:30:00 +0200 From: Bjoern Fischer <bfischer@Techfak.Uni-Bielefeld.DE> To: Vinod Mukkamala <vmukkama@gmu.edu> Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: socket option IP_MULTICAST_LOOP has no effect? Message-ID: <20000830052959.C873@frolic.no-support.loc> In-Reply-To: <Pine.OSF.4.21.0008291552210.5932-100000@osf1.gmu.edu>; from vmukkama@gmu.edu on Tue, Aug 29, 2000 at 03:56:25PM -0400 References: <Pine.OSF.4.21.0008291552210.5932-100000@osf1.gmu.edu>
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On Tue, Aug 29, 2000 at 03:56:25PM -0400, Vinod Mukkamala wrote:
> For some reason setsockopt function takes in the a address of a char
> as the 4th argument only.
[code example typos corrected]
>=20
> int tmp =3D 0; // to disable loop back
> setsockopt(s,
> IPPROTO_IP,
> IP_MULTICAST_LOOP,
> (char *)&tmp,
> sizeof(tmp));
>=20
> and it didn't work...=20
>=20
> but=20
>=20
> char tmp =3D 0; // to disable loop back
> setsockopt(s,
> IPPROTO_IP,
> IP_MULTICAST_LOOP,
> (char *)&tmp,
> sizeof(tmp));
>=20
> works perfectly fine.=20
Thank you a lot for your help, I will try this as soon as possible,
but there's something weird:
case IP_MULTICAST_LOOP:
/*
* Set the loopback flag for outgoing multicast packets.
* Must be zero or one. The original multicast API required a
* char argument, which is inconsistent with the rest
* of the socket API. We allow either a char or an int.
*/
if (sopt->sopt_valsize =3D=3D 1) {
u_char loop;
error =3D sooptcopyin(sopt, &loop, 1, 1);
if (error)
break;
imo->imo_multicast_loop =3D !!loop;
} else {
u_int loop;
error =3D sooptcopyin(sopt, &loop, sizeof loop,
sizeof loop);
if (error)
break;
imo->imo_multicast_loop =3D !!loop;
}
break;
This piece of code is out of FreeBSD 4-STABLE's kernel source.
As you see it should deal with both: ints *and* chars. The
code seems to be correct, so I wonder why it's not working
with ints.
Bj=F6rn Fischer
--=20
-----BEGIN GEEK CODE BLOCK-----
GCS d--(+) s++: a- C+++(-) UB++++OSI++++$ P+++(-) L---(++) !E W- N+ o>+
K- !w !O !M !V PS++ PE- PGP++ t+++ !5 X++ tv- b+++ D++ G e+ h-- y+=20
------END GEEK CODE BLOCK------
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