Hi Pablo,
Pablo Neira Ayuso writes:
> On Fri, Nov 16, 2018 at 09:30:33AM +0200, Baruch Siach wrote:
>> Commit 672accf1530 (include: update kernel netfilter header files)
>> updated linux/netfilter.h and brought with it the update from kernel
>> commit a263653ed798 (netfilter: don't pull include/linux/netfilter.h
>> from netns headers). This triggers conflict of headers that is fixed in
>> kernel commit 279c6c7fa64f (api: fix compatibility of linux/in.h with
>> netinet/in.h) included in kernel version 4.2. For earlier kernel headers
>> we need a workaround that prevents the headers conflict.
>>
>> Fixes the following build failure:
>>
>> In file included from .../sysroot/usr/include/netinet/ip.h:25:0,
>> from ../include/libiptc/ipt_kernel_headers.h:8,
>> from ../include/libiptc/libiptc.h:6,
>> from libip4tc.c:29:
>> .../sysroot/usr/include/linux/in.h:26:3: error: redeclaration of enumerator ‘IPPROTO_IP’
>> IPPROTO_IP = 0, /* Dummy protocol for TCP */
>> ^
>> .../sysroot/usr/include/netinet/in.h:33:5: note: previous definition of ‘IPPROTO_IP’ was here
>> IPPROTO_IP = 0, /* Dummy protocol for TCP. */
>> ^~~~~~~~~~
>>
>> Cc: Florian Westphal <fw@xxxxxxxxx>
>> Signed-off-by: Baruch Siach <baruch@xxxxxxxxxx>
>> ---
>> include/linux/netfilter.h | 2 ++
>> 1 file changed, 2 insertions(+)
>>
>> diff --git a/include/linux/netfilter.h b/include/linux/netfilter.h
>> index c3f087ac680c..bacf8cd92116 100644
>> --- a/include/linux/netfilter.h
>> +++ b/include/linux/netfilter.h
>> @@ -3,7 +3,9 @@
>>
>> #include <linux/types.h>
>>
>> +#ifndef _NETINET_IN_H
>> #include <linux/in.h>
>> +#endif
>
> This is updating a cached copy of the kernel headers, we basically
> copy kernel headers and place in the userspace tree to make sure that
> iptables compiles standalone, without the need for kernel-headers to
> be installed in the system in order to simplify building process.
>
> I would like we don't have to modify this cached copy, so if you can
> find a way to update the userspace C files without touching the cached
> copy of the kernel header, that would be great. My concern is that
> this little tweak will go away once we update the cached copy anytime
> soon in the future.
>
> Thanks.
I can't think of any better solution.
A possible alternative would be to add '#define _LINUX_IN_H' in every
file that include netinet/in.h to suppress the kernel headern. This is a
bigger change, although is doesn't touch any cached kernel header as far
as I can see.
Do you like this solution better?
baruch
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