Re: point2point network interfaces cannot receive ipv6 packets

[Takahiro HAYASHI <t.hash425%gmail.com@localhost>]

hi,

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On 2015/04/09 21:39, Justin Cormack wrote:
> On 9 April 2015 at 12:10, Kengo NAKAHARA <k-nakahara%iij.ad.jp@localhost> wrote:
> > Hi,
> >
> > On 2015/04/03 16:14, Takahiro HAYASHI wrote:
> > > It seems that IFF_POINTTOPOINT interfaces like tun and gif cannot
> > > receive ipv6 packets.
> > > This occurs on NetBSD/amd64 -current since Feb 27 2015.
> > >
> > > For example, establishing gif tunnnel between 2 hosts.
> > >
> > > [host1] <---> [host2]
> > > 192.168.0.1   192.168.0.2  ipv4 address of real interface
> > > fd00::1       fd00::2      gif address
> > >
> > > When I ping6, a host can send ICMPv6 ECHO(128), but the other host
> > > returns ICMPv6 DST_UNREACH(1) code UNREACH_ADDR(3) to pinging host.
> >
> > I think the reason of this issue is below commit:
> >      http://www.nerv.org/netbsd/?q=id:20150226T095446Z.75354d997222ae09acc944ba1c6cf573c3ea724b
> >
> > This commit changes the route entry for gif as describe below
> > ========== before ==========
> > Internet6:
> > Destination                        Gateway                        Flags    Refs      Use    Mtu Interface
> > fd00::2                            link#13                        UHL         0        0      -  lo0
> > ========== before ==========
> > ========== after ==========
> > Internet6:
> > Destination                        Gateway                        Flags    Refs      Use    Mtu Interface
> > fd00::2                            fd00::2                        UH          -        -      -  gif0
> > ========== after ==========
> >
> > This route change caused the function flow change in ip6_input(), in
> > paticular the below line
> >      http://nxr.netbsd.org/xref/src/sys/netinet6/ip6_input.c#497
> > After above commit, this statement become false, and then, the packets
> > is discarded through line#565.
> >
> > I found the above reason, however I have no idea to fix this issue...

Thank you for your analysis.
Newer netstat shows gif0 route like this:

fd00::2                            fd00::2                        UHl          -        -      -  gif0


> Could you file a PR?

I'll do.

> Justin

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