From: Andrew Morton <akpm@linux-foundation.org>
To: netdev@vger.kernel.org
Cc: bugzilla-daemon@bugzilla.kernel.org,
bugme-daemon@bugzilla.kernel.org, manlidj@hotmail.com
Subject: Re: [Bugme-new] [Bug 13856] New: sk_bound_dev_if should be set for a socket when using IP_MULITCAST_IF or IP_ADD_MEMBERSHIO
Date: Wed, 29 Jul 2009 12:52:03 -0700 [thread overview]
Message-ID: <20090729125203.efbcb7ef.akpm@linux-foundation.org> (raw)
In-Reply-To: <bug-13856-10286@http.bugzilla.kernel.org/>
(switched to email. Please respond via emailed reply-to-all, not via the
bugzilla web interface).
On Tue, 28 Jul 2009 03:42:38 GMT
bugzilla-daemon@bugzilla.kernel.org wrote:
> http://bugzilla.kernel.org/show_bug.cgi?id=13856
>
> Summary: sk_bound_dev_if should be set for a socket when using
> IP_MULITCAST_IF or IP_ADD_MEMBERSHIO
> Product: Networking
> Version: 2.5
> Kernel Version: 2.6.27.7
> Platform: All
> OS/Version: Linux
> Tree: Mainline
> Status: NEW
> Severity: normal
> Priority: P1
> Component: IPV4
> AssignedTo: shemminger@linux-foundation.org
> ReportedBy: manlidj@hotmail.com
> Regression: No
>
>
> Currently there is no way to tell which interface a multicast packet arrived on
> except by using a raw socket and issuing the SO_BINDTODEVICE option which
> forces the sk_bound_dev_if for the socket to be set.
>
> Consider a multi-homed system where a service needs to listen for multicast
> SSDP messages on a number of interfaces. The system needs to know which
> interface a search message came in on in order to respond with the correct URL.
>
> The service needs to join the multicast group on all interfaces. It must bind
> on INADDR_ANY and then issue the IP_ADD_MEMBERSHIP call.
>
> 1. If it uses one socket and joins on all interfaces it will receive mulitcast
> from all interfaces but cannot tell which interface the message came in on
>
> 2. It it uses a socket per interface each bound on INADDR_ANY and issues
> IP_MULTICAST_IF. In this case any mulitcast socket, no matter what interface,
> will be forwarded to each socket because sk_bound_dev_if was not set (i.e. 0) -
> see net/ipv4/udp.c [ udp_v4_mcast_next ]
>
> Suggested solution is to set sk_bound_dev_if when IP_MULTICAST_IF is issued.
>
next parent reply other threads:[~2009-07-29 19:52 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <bug-13856-10286@http.bugzilla.kernel.org/>
2009-07-29 19:52 ` Andrew Morton [this message]
2009-07-30 0:46 ` [Bugme-new] [Bug 13856] New: sk_bound_dev_if should be set for a socket when using IP_MULITCAST_IF or IP_ADD_MEMBERSHIO John Dykstra
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