Arthur,
I assume you're making use of the hack mentioned in route.c:
"... This hack is not just for fun, it allows vic, vat and friends to
work.
They bind socket to loopback, set ttl to zero and expect that it will
work."
I don't know the details of the intent for this hack, but did you
test that it won't break them?
A multicast application that relies on the (unicast) routing table
at all is broken IMHO, as is an app that sets the TTL to 0, but shouldn't
all ttl 0 packets about to be sent to the wire be dropped? Wouldn't that
be a better way to handle this case?
+-DLS
[EMAIL PROTECTED] wrote on 05/15/2007 12:56:02 PM:
> A colleague of mine found that multicasts with a ttl of 0
> can be sent on the wire. This happens if the sender doesn't
> belong to the destination multicast group.
>
> With the following the multicast ttl is respected whether
> or not the sender belongs to the destination multicast group.
>
> Signed-off-by: Arthur Kepner <[EMAIL PROTECTED]>
>
> ---
>
> net/ipv4/route.c | 3 +--
> 1 files changed, 1 insertions(+), 2 deletions(-)
>
> diff --git a/net/ipv4/route.c b/net/ipv4/route.c
> index cb76e3c..bf25cf5 100644
> --- a/net/ipv4/route.c
> +++ b/net/ipv4/route.c
> @@ -2249,8 +2249,7 @@ static inline int __mkroute_output(struct rtable
**result,
> }
> if (flags & (RTCF_BROADCAST | RTCF_MULTICAST)) {
> rth->rt_spec_dst = fl->fl4_src;
> - if (flags & RTCF_LOCAL &&
> - !(dev_out->flags & IFF_LOOPBACK)) {
> + if (!(dev_out->flags & IFF_LOOPBACK)) {
> rth->u.dst.output = ip_mc_output;
> RT_CACHE_STAT_INC(out_slow_mc);
> }
>
> --
> Arthur
>
> -
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