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	ipv6: improve ipv6_find_hdr() to skip empty routing headers
This patch prepares ipv6_find_hdr() function so that it could be able to skip routing headers, where segements_left is 0. This is required to handle multiple routing header case correctly when changing IPv6 addresses. Signed-off-by: Ansis Atteka <aatteka@nicira.com> Signed-off-by: Jesse Gross <jesse@nicira.com>
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					 2 changed files with 31 additions and 10 deletions
				
			
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			@ -633,6 +633,7 @@ extern bool			ipv6_ext_hdr(u8 nexthdr);
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enum {
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	IP6_FH_F_FRAG		= (1 << 0),
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	IP6_FH_F_AUTH		= (1 << 1),
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	IP6_FH_F_SKIP_RH	= (1 << 2),
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};
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/* find specified header and get offset to it */
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			@ -132,9 +132,11 @@ EXPORT_SYMBOL(ipv6_skip_exthdr);
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 * *offset is meaningless and fragment offset is stored in *fragoff if fragoff
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 * isn't NULL.
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 *
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 * if flags is not NULL and it's a fragment, then the frag flag IP6_FH_F_FRAG
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 * will be set. If it's an AH header, the IP6_FH_F_AUTH flag is set and
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 * target < 0, then this function will stop at the AH header.
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 * if flags is not NULL and it's a fragment, then the frag flag
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 * IP6_FH_F_FRAG will be set. If it's an AH header, the
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 * IP6_FH_F_AUTH flag is set and target < 0, then this function will
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 * stop at the AH header. If IP6_FH_F_SKIP_RH flag was passed, then this
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 * function will skip all those routing headers, where segements_left was 0.
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 */
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int ipv6_find_hdr(const struct sk_buff *skb, unsigned int *offset,
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		  int target, unsigned short *fragoff, int *flags)
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			@ -142,6 +144,7 @@ int ipv6_find_hdr(const struct sk_buff *skb, unsigned int *offset,
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	unsigned int start = skb_network_offset(skb) + sizeof(struct ipv6hdr);
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	u8 nexthdr = ipv6_hdr(skb)->nexthdr;
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	unsigned int len;
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	bool found;
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	if (fragoff)
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		*fragoff = 0;
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			@ -159,9 +162,10 @@ int ipv6_find_hdr(const struct sk_buff *skb, unsigned int *offset,
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	}
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	len = skb->len - start;
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	while (nexthdr != target) {
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	do {
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		struct ipv6_opt_hdr _hdr, *hp;
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		unsigned int hdrlen;
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		found = (nexthdr == target);
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		if ((!ipv6_ext_hdr(nexthdr)) || nexthdr == NEXTHDR_NONE) {
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			if (target < 0)
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			@ -172,6 +176,20 @@ int ipv6_find_hdr(const struct sk_buff *skb, unsigned int *offset,
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		hp = skb_header_pointer(skb, start, sizeof(_hdr), &_hdr);
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		if (hp == NULL)
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			return -EBADMSG;
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		if (nexthdr == NEXTHDR_ROUTING) {
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			struct ipv6_rt_hdr _rh, *rh;
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			rh = skb_header_pointer(skb, start, sizeof(_rh),
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						&_rh);
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			if (rh == NULL)
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				return -EBADMSG;
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			if (flags && (*flags & IP6_FH_F_SKIP_RH) &&
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			    rh->segments_left == 0)
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				found = false;
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		}
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		if (nexthdr == NEXTHDR_FRAGMENT) {
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			unsigned short _frag_off;
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			__be16 *fp;
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			@ -205,10 +223,12 @@ int ipv6_find_hdr(const struct sk_buff *skb, unsigned int *offset,
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		} else
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			hdrlen = ipv6_optlen(hp);
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		if (!found) {
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			nexthdr = hp->nexthdr;
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			len -= hdrlen;
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			start += hdrlen;
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		}
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	} while (!found);
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	*offset = start;
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	return nexthdr;
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