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Subject: Re: [PATCH bluetooth-next 3/4] 6lowpan: add nhc module for GHC UDP
 detection
To: Alexander Aring <alex.aring@gmail.com>
References: <1442577168-23183-1-git-send-email-stefan@osg.samsung.com>
 <1442577168-23183-4-git-send-email-stefan@osg.samsung.com>
 <20150918215025.GB6872@omega>
Cc: linux-wpan@vger.kernel.org, jukka.rissanen@linux.intel.com,
	linux-bluetooth@vger.kernel.org
From: Stefan Schmidt <stefan@osg.samsung.com>
Message-ID: <5655BC7E.3060106@osg.samsung.com>
Date: Wed, 25 Nov 2015 14:49:50 +0100
MIME-Version: 1.0
In-Reply-To: <20150918215025.GB6872@omega>
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Sender: linux-wpan-owner@vger.kernel.org
List-ID: <linux-bluetooth.vger.kernel.org>

Hello.

On 18/09/15 23:50, Alexander Aring wrote:
> On Fri, Sep 18, 2015 at 01:52:47PM +0200, Stefan Schmidt wrote:
>> Signed-off-by: Stefan Schmidt <stefan@osg.samsung.com>
>> ---
>>   net/6lowpan/Kconfig       |  5 +++++
>>   net/6lowpan/Makefile      |  1 +
>>   net/6lowpan/nhc_ghc_udp.c | 27 +++++++++++++++++++++++++++
>>   3 files changed, 33 insertions(+)
>>   create mode 100644 net/6lowpan/nhc_ghc_udp.c
>>
>> diff --git a/net/6lowpan/Kconfig b/net/6lowpan/Kconfig
>> index f541f50..67a786b 100644
>> --- a/net/6lowpan/Kconfig
>> +++ b/net/6lowpan/Kconfig
>> @@ -64,4 +64,9 @@ config 6LOWPAN_GHC_EXTENSION_HEADER
>>   	default y
>>   	---help---
>>   
>> +config 6LOWPAN_GHC_UDP
>> +	tristate "GHC UDP Support"
>> +	default y
>> +	---help---
>> +
>>   endif
>> diff --git a/net/6lowpan/Makefile b/net/6lowpan/Makefile
>> index 2b42bd0..fc65efb 100644
>> --- a/net/6lowpan/Makefile
>> +++ b/net/6lowpan/Makefile
>> @@ -13,3 +13,4 @@ obj-$(CONFIG_6LOWPAN_NHC_UDP) += nhc_udp.o
>>   
>>   #rfc7400 ghcs
>>   obj-$(CONFIG_6LOWPAN_GHC_EXTENSION_HEADER) += nhc_ghc_extension_header.o
>> +obj-$(CONFIG_6LOWPAN_GHC_UDP) += nhc_ghc_udp.o
>> diff --git a/net/6lowpan/nhc_ghc_udp.c b/net/6lowpan/nhc_ghc_udp.c
>> new file mode 100644
>> index 0000000..2675683
>> --- /dev/null
>> +++ b/net/6lowpan/nhc_ghc_udp.c
>> @@ -0,0 +1,27 @@
>> +/*
>> + *	6LoWPAN UDP compression according to RFC7400
>> + *
>> + *	This program is free software; you can redistribute it and/or
>> + *	modify it under the terms of the GNU General Public License
>> + *	as published by the Free Software Foundation; either version
>> + *	2 of the License, or (at your option) any later version.
>> + */
>> +
>> +#include "nhc.h"
>> +
>> +#define LOWPAN_GHC_UDP_IDLEN	1
>> +#define LOWPAN_GHC_UDP_ID_0	0xd0
>> +#define LOWPAN_GHC_UDP_MASK_0	0xf8
>> +
>> +static void udp_ghid_setup(struct lowpan_nhc *nhc)
>> +{
>> +	nhc->id[0] = LOWPAN_GHC_UDP_ID_0;
>> +	nhc->idmask[0] = LOWPAN_GHC_UDP_MASK_0;
>> +}
>> +
>> +LOWPAN_NHC(ghc_udp, "RFC7400 UDP", NEXTHDR_HOP, 0,
> s/NEXTHDR_HOP/NEXTHDR_UDP/

Fixed in the upcoming patchset.

>
> Sadly is that we can't load two modules which contains NEXTHDR_UDP, when
> another NEXTHDR_UDP is registered. But we should support all nhcid's
> for receving side.
>
> Maybe we can simple remove the check if nexthdr for compression
> (tranmsit side) is already registered, actually this returns -EBUSY. We
> prior for compression then the first loaded module (which should have a
> compression method).

At least for GHC we will know what destinations support it once we 
support the 6LoWPAN Capability Indication Option (6CIO) over ND.

> The real solution would be some configurable netlink framework. :-)

Agreed. This is actually on my list of things to do. Juts no idea when i 
will come to it.