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Message-ID: <4703988B.3010904@gmail.com>
Date: Wed, 03 Oct 2007 17:26:35 +0400
From: Dmitry Baryshkov <dbaryshkov@...il.com>
To: David Stevens <dlstevens@...ibm.com>
CC: linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
netdev-owner@...r.kernel.org
Subject: Re: [PATCH] Fallback to ipv4 if we try to add join IPv4 multicast
group via ipv4-mapped address.
Hello,
David Stevens wrote:
> Dmitry,
> Good catch; a couple comments:
Thank you for the response.
>
>> struct ipv6_pinfo *np = inet6_sk(sk);
>> int err;
>> + int addr_type = ipv6_addr_type(addr);
>> +
>> + if (addr_type == IPV6_ADDR_MAPPED) {
>> + __be32 v4addr = addr->s6_addr32[3];
>> + struct ip_mreqn mreq;
>> + mreq.imr_multiaddr.s_addr = v4addr;
>> + mreq.imr_address.s_addr = INADDR_ANY;
>> + mreq.imr_ifindex = ifindex;
>> +
>> + return ip_mc_join_group(sk, &mreq);
>> + }
>
> ipv6_addr_type() returns a bitmask, so you should use:
>
> if (addr_type & IPV6_ADDR_MAPPED) {
I just c'n'pasted the code that checks for mapped addresses. In most
cases it's just ==, not bitmask operation.
>
> Also, you should have a blank line after the "mreq" declaration.
ok.
>
> Ditto for both in ipv6_mc_sock_drop().
> I don't expect the multicast source filtering interface will
> behave well for mapped addresses, either. The mapped multicast
> address won't appear to be a multicast address (and return
> error there), and all the source filters would have to be
> v4mapped addresses and modify the v4 source filters for this
> to do as you expect. So, there's more to it (and it may be a
> bit messy) to support mapped multicast addresses fully. I'll
> think about that part some more.
Didn't have time to test it throughly. I've only checked that call
succeeds and that all necessary igmp are sent. I hope, this weekend I'll
have more time to check.
--
With best wishes
Dmitry Baryshkov
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