From: Simon Wunderlich <simon.wunderlich@s2003.tu-chemnitz.de>
To: The list for a Better Approach To Mobile Ad-hoc Networking
<b.a.t.m.a.n@lists.open-mesh.org>
Subject: Re: [B.A.T.M.A.N.] Weird TTL for ICMP packets
Date: Sun, 30 Oct 2011 16:36:00 +0100 [thread overview]
Message-ID: <20111030153600.GA3234@pandem0nium> (raw)
In-Reply-To: <1850275.SO2QzbpOTm@sven-laptop.home.narfation.org>
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Hi Sven,
although looking a little bit confusing, this seems to be correct. The TTL
field is used to transport the kernel modules compat version when it differs
from the one used in batctl.
Compare the batctl code (ping.c:284):
switch (icmp_packet_in.msg_type) {
[...]
case PARAMETER_PROBLEM:
printf("Error - the batman adv kernel module version (%d) differs from ours (%d)\n",
icmp_packet_in.ttl, COMPAT_VERSION);
printf("Please make sure to compatible versions!\n");
goto out;
[...]
However, I guess an explaining comment in the kernel code would not be wrong ...
Cheers
Simon
On Sun, Oct 30, 2011 at 02:31:55PM +0100, Sven Eckelmann wrote:
> Hi,
>
> just looked through some ICMP code in icmp_socket.c and found a little bit
> weird TTL:
>
> 218 if (icmp_packet->version != COMPAT_VERSION) {
> 219 icmp_packet->msg_type = PARAMETER_PROBLEM;
> 220 icmp_packet->ttl = COMPAT_VERSION;
> 221 bat_socket_add_packet(socket_client, icmp_packet,
> packet_len);
> 222 goto free_skb;
> 223 }
>
> It was introduced by dba95eb270ff9674326865a20d25921c69c04d6c. My guess is
> that TTL should be used.
>
> Kind regards,
> Sven
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next prev parent reply other threads:[~2011-10-30 15:36 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-30 13:31 [B.A.T.M.A.N.] Weird TTL for ICMP packets Sven Eckelmann
2011-10-30 15:36 ` Simon Wunderlich [this message]
2011-10-30 15:40 ` [B.A.T.M.A.N.] [PATCH] batman-adv: explain the weird " Simon Wunderlich
2011-10-30 15:57 ` Sven Eckelmann
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