From: Patrick McHardy <kaber@trash.net>
To: Hans Schillstrom <hans@schillstrom.com>
Cc: pablo@netfilter.org, jengelh@medozas.de,
netfilter-devel@vger.kernel.org, netdev@vger.kernel.org,
hans.schillstrom@ericsson.com
Subject: Re: [v4 PATCH 1/2] NETFILTER module xt_hmark, new target for HASH based fwmark
Date: Thu, 01 Dec 2011 12:46:08 +0100 [thread overview]
Message-ID: <4ED76900.6000108@trash.net> (raw)
In-Reply-To: <jec613b.2c905808e36d8b8192d285d691c5499b@obelix.schillstrom.com>
On 12/01/2011 12:39 PM, Hans Schillstrom wrote:
> t: Re: [v4 PATCH 1/2] NETFILTER module xt_hmark, new target for HASH based fwmark
>> On 12/01/2011 12:05 PM, Hans Schillstrom wrote:
>>>>>> And final question, why not simply use ipv6_skip_exthdr()?
>>>>> problems with fragments...
>>>> So the probem is that it will return the transport layer protocol
>>>> header for fragments with frag_off == 0? We also have ipv6_find_hdr()
>>>> which we could modify to indicate this in the frag_off pointer.
>>> ipv6_find_hdr() will do the trick with a light modification
>>> What about a wrapper like:
>>>
>>> int __ipv6_find_hdr(const struct sk_buff *skb, unsigned int *offset,
>>> int target, unsigned short *fragoff, int *fragflg)
>>> {
>>> ...
>>> if (nexthdr == NEXTHDR_FRAGMENT) {
>>> unsigned short _frag_off;
>>> __be16 *fp;
>>>
>>> if (fragflg)
>>> fragflg = 1;
>>> fp = skb_header_pointer(skb,
>>> start+offsetof(struct frag_hdr,
>>> frag_off),
>>> sizeof(_frag_off),
>>> &_frag_off);
>>>
>>> ...
>>> }
>>>
>>> int ipv6_find_hdr(const struct sk_buff *skb, unsigned int *offset,
>>> int target, unsigned short *fragoff)
>>> {
>>> return __ipv6_find_hdr(skb, offset, terget, fragoff, NULL);
>>> }
>> Hmm that would require to change all current callers.
> Nope, ipv6_find_hdr() looks the same,
> __ipv6_find_hdr() have an extra param.
Ah, right, apparently need more coffee :)
>> I was more thinking of unconditionally setting *frag_off in case of
>> fragments, then you can initialize it to some impossible value
>> like 0xffff and determine the presence of a fragment header
>> based on its value after calling ipv6_find_hdr().
> That's another way :-)
>
> Which one do you prefer ?
You way seems cleaner to me, lets do that.
next prev parent reply other threads:[~2011-12-01 11:46 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-01 11:39 Re[2]: [v4 PATCH 1/2] NETFILTER module xt_hmark, new target for HASH based fwmark Hans Schillstrom
2011-12-01 11:46 ` Patrick McHardy [this message]
-- strict thread matches above, loose matches on Subject: below --
2011-12-01 11:05 Hans Schillstrom
2011-12-01 11:24 ` Patrick McHardy
2011-11-28 9:36 Re[2]: " Hans Schillstrom
2011-11-30 15:27 ` Patrick McHardy
2011-11-30 18:28 ` Pablo Neira Ayuso
2011-12-01 0:52 ` Hans Schillstrom
2011-11-25 9:36 [v4 PATCH 0/2] NETFILTER new target module, HMARK Hans Schillstrom
2011-11-25 9:36 ` [v4 PATCH 1/2] NETFILTER module xt_hmark, new target for HASH based fwmark Hans Schillstrom
2011-11-25 14:19 ` David Laight
2011-11-25 14:36 ` Eric Dumazet
2011-11-25 14:43 ` Eric Dumazet
2011-11-25 17:36 ` Pablo Neira Ayuso
2011-11-25 18:31 ` Jan Engelhardt
2011-11-30 15:51 ` Patrick McHardy
2011-12-01 0:25 ` Hans Schillstrom
2011-12-01 10:05 ` Patrick McHardy
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