netdev - Re: Incorrect source IP address on IGMP membership report

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Date:   Sat, 9 Dec 2017 23:20:08 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Kevin Cernekee <cernekee@...omium.org>
Cc:     netdev@...r.kernel.org
Subject: Re: Incorrect source IP address on IGMP membership report

> Hmm, RFC3376 says:
> 
> 4.2.13. IP Source Addresses for Reports
> 
>    An IGMP report is sent with a valid IP source address for the
>    destination subnet.  The 0.0.0.0 source address may be used by a
>    system that has not yet acquired an IP address.  Note that the
>    0.0.0.0 source address may simultaneously be used by multiple systems
>    on a LAN.  Routers MUST accept a report with a source address of
>    0.0.0.0.
> 
> Would it make sense to add a special case that says "zero out
> pip->saddr if the interface doesn't have any IPv4 addresses"?  e.g.

Yes, this looks O.K. for IGMPv3.

     Andrew