Date: Wed, 24 Dec 2008 23:13:17 +0000 (UTC) From: "Bjoern A. Zeeb" <bzeeb-lists@lists.zabbadoz.net> To: Alfred Perlstein <alfred@freebsd.org> Cc: net@freebsd.org Subject: Re: ipv6 bugfix, need review. Message-ID: <20081224230540.C97918@maildrop.int.zabbadoz.net> In-Reply-To: <20081223001216.GH18389@elvis.mu.org> References: <20081223001216.GH18389@elvis.mu.org>
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On Mon, 22 Dec 2008, Alfred Perlstein wrote:
Hi,
> Hey guys, we found a bug at Juniper and it resolves an issue
> for us. I've been asked to forward this to FreeBSD, I honestly
> am not that clear on the issue so I'm hoping someone can step
> up to review this.
>
> Synopsis is:
>
> The traffic class byte is set to 0x00000000 in the header of some
> BGP packets sent between interfaces that have IPv6 addresses,
> instead of the correct setting 0xc0 (INTERNETCONTROL).
>
> Fix is small and attached. One thing I am wondering, do we
> need to check "if (inp)" ? I don't think so.
I am not that concerned about the inp at the moment; there are a few
other things:
1 FreeBSD to my knowledge has neither IPV6_GET_CLASS nor IPV6_SET_CLASS
nor IPV6_CLASS_MASK
2 To the best I can see this currently ignores the upper 4 TC bits that
go with the `version field' ("vcf"), so it's a hack good enough for
now, but not a proper fix?
3 I am assuming that we'd need to fix at least one more place.
Tha said I planned to look at the in6p_flowinfo (inp_flow) field in
the not too distant future anyway; I should perhaps combine this
looking into the entire TC thing as well.
> Index: bsd/sys/netinet/tcp_syncache.c
> ===================================================================
> RCS file: /cvs/junos-2008/bsd/sys/netinet/tcp_syncache.c,v
> retrieving revision 1.24
> diff -p -u -r1.24 tcp_syncache.c
> --- bsd/sys/netinet/tcp_syncache.c 29 Jul 2008 17:07:43 -0000 1.24
> +++ bsd/sys/netinet/tcp_syncache.c 16 Dec 2008 19:23:31 -0000
> @@ -1271,6 +1271,7 @@ syncache_respond(sc, m)
> struct inpcb *inp;
> #ifdef INET6
> struct ip6_hdr *ip6 = NULL;
> + int inp_tclass;
> #endif
> struct rt_nexthop *minmtu_nh;
> struct route_table *rtb = NULL;
> @@ -1387,6 +1388,12 @@ syncache_respond(sc, m)
> /* ip6_hlim is set after checksum */
> ip6->ip6_flow &= ~IPV6_FLOWLABEL_MASK;
> ip6->ip6_flow |= sc->sc_flowlabel;
> + /* Set the TC for IPv6 just like TOS for IPv4 */
> + ip6->ip6_flow &= ~IPV6_CLASS_MASK;
> + if (inp) {
> + inp_tclass = IPV6_GET_CLASS(inp->in6p_flowinfo);
> + ip6->ip6_flow |= IPV6_SET_CLASS(inp_tclass);
> + }
>
> th = (struct tcphdr *)(ip6 + 1);
> } else
>
>
>
--
Bjoern A. Zeeb The greatest risk is not taking one.
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