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.
> 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 ?
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