Re: [PATCH] libpcap: Add datalink-type to match

[Luca Bruno <lucab () debian org>]

Guy Harris scrisse:

> From what you said there, it sounds as if Linux doesn't, in this
> case, engage in the link-layer-header-mangling it all too often does,
> and just hands a perfectly ordinary 802.15.4 header followed
> immediately by the payload to the socket, so it sounds as if
> DLT_IEEE802_15_4 is the right choice.  My concern was that somebody
> *else* doing 802.15.4 on Linux wanted a different header:

> [...]

> > > In other words, the packets are *NOT* 802.15.4-2006 packets as
> > > they appear on the air, but have had the address fields padded?
> >
> > Yes
> > > Is this on Linux?
> >
> > Yes it is on Linux. ( X86 and uClinunx ARM ). At the Moment i try
> > to get the device driver (cc2420 at the Parallel Port on PC, SPI on
> > ARM ) reliable. -
>
> although it sounds as if his 802.15.4 implementation might be
> different from the one in the mainstream kernel, and the latter might
> not pad the address fields.

Oh well, then it's a difficult story. I'm not using Linux drivers (as
in, I've no devices attached locally) but merely getting properly
remote 802.15.4 traffic on an aggregated interface on Linux.
On one hand, you're right being concerned, as I just checked and it
seems to be defined as such:
include/net/af_ieee802154.h:37: #define IEEE802154_ADDR_LEN     8
include/net/af_ieee802154.h:43: u8 hwaddr [IEEE802154_ADDR_LEN];
so well, in that case they're not going to match, and I'm definitely wrong.
On the other hand, I've standard-defined traffic which is what I
(and wireshark, and everybody else) would expect on a IEEE802154 link here.
I am not allowed to modify the packets (as they are, well, specification
compliant) but still need to correctly handle, inspect, sniff from there
and pcap-save them. 
If you're right and this patch isn't correct, how can I properly address that?

Cheers, Luca

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