Hi,
On Fri, Apr 22, 2016 at 02:28:16PM +0200, Alexander Aring wrote:
> On Fri, Apr 22, 2016 at 01:13:29PM +0200, smlng wrote:
...
> >
> > @Alex as you joined the discussion: I also have a question regarding the Linux side. I currently use Raspbian with shipped Linux-Kernel 4.1.19. I observed that Linux still does NS for link-local address via the nodes scoped multicast address, instead of using 6lo 'shortcut' by extracting LL/MAC-address from the link-local IP. Is this fixed in some recent version?
> >
>
> There are currently pending patches for introducing neigh_ops, which is
> a callback strucuture for send/recv NS/NA. After this is mainline it
> should be easily to change this behaviour, or? What do you think?
> See [3] - function "lowpan_ndisc_send_ns".
>
I think, I know what you mean. There is some NS with src as unspecified
addr "::" and dest is some "multicast node scope".
RFC 6775 says [0]:
An unspecified source address MUST NOT be used in NS messages.
Additional to the pending patches I added:
diff --git a/net/6lowpan/ndisc.c b/net/6lowpan/ndisc.c
index d088295..c6207cd 100644
--- a/net/6lowpan/ndisc.c
+++ b/net/6lowpan/ndisc.c
@@ -386,8 +386,11 @@ static void lowpan_ndisc_send_ns(struct net_device *dev,
saddr = &addr_buf;
}
+ /* RFC6775:
+ * An unspecified source address MUST NOT be used in NS messages.
+ */
if (ipv6_addr_any(saddr))
- inc_opt = false;
+ return;
if (inc_opt) {
optlen += ndisc_opt_addr_space(dev, dev->addr_len);
optlen += lowpan_ndisc_802154_short_addr_space(dev);
This will not sending NS with "::" addresses as source address.
However, it's a little bit ugly we should prevent to calling this
callback when source address is "::".
This patch should be fine at first but can maybe optimized in future.
---
Also for processing NS the "::" seems to be different [1], "::" seems to
valid (ARO will be ignored than but we don't support it so it's default
ignored). :-)
- Alex
[0] https://tools.ietf.org/html/rfc6775#section-5.5.1
[1] https://tools.ietf.org/html/rfc6775#section-6.5
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