ipv6: Move ipv6_find_hdr() out of Netfilter code.
Open vSwitch will soon also use ipv6_find_hdr() so this moves it
out of Netfilter-specific code into a more common location.
Signed-off-by: Jesse Gross <jesse@nicira.com>
diff --git a/net/ipv6/exthdrs_core.c b/net/ipv6/exthdrs_core.c
index f73d59a..8ea253a 100644
--- a/net/ipv6/exthdrs_core.c
+++ b/net/ipv6/exthdrs_core.c
@@ -111,3 +111,106 @@
return start;
}
EXPORT_SYMBOL(ipv6_skip_exthdr);
+
+/*
+ * find the offset to specified header or the protocol number of last header
+ * if target < 0. "last header" is transport protocol header, ESP, or
+ * "No next header".
+ *
+ * Note that *offset is used as input/output parameter. an if it is not zero,
+ * then it must be a valid offset to an inner IPv6 header. This can be used
+ * to explore inner IPv6 header, eg. ICMPv6 error messages.
+ *
+ * If target header is found, its offset is set in *offset and return protocol
+ * number. Otherwise, return -1.
+ *
+ * If the first fragment doesn't contain the final protocol header or
+ * NEXTHDR_NONE it is considered invalid.
+ *
+ * Note that non-1st fragment is special case that "the protocol number
+ * of last header" is "next header" field in Fragment header. In this case,
+ * *offset is meaningless and fragment offset is stored in *fragoff if fragoff
+ * isn't NULL.
+ *
+ * if flags is not NULL and it's a fragment, then the frag flag IP6_FH_F_FRAG
+ * will be set. If it's an AH header, the IP6_FH_F_AUTH flag is set and
+ * target < 0, then this function will stop at the AH header.
+ */
+int ipv6_find_hdr(const struct sk_buff *skb, unsigned int *offset,
+ int target, unsigned short *fragoff, int *flags)
+{
+ unsigned int start = skb_network_offset(skb) + sizeof(struct ipv6hdr);
+ u8 nexthdr = ipv6_hdr(skb)->nexthdr;
+ unsigned int len;
+
+ if (fragoff)
+ *fragoff = 0;
+
+ if (*offset) {
+ struct ipv6hdr _ip6, *ip6;
+
+ ip6 = skb_header_pointer(skb, *offset, sizeof(_ip6), &_ip6);
+ if (!ip6 || (ip6->version != 6)) {
+ printk(KERN_ERR "IPv6 header not found\n");
+ return -EBADMSG;
+ }
+ start = *offset + sizeof(struct ipv6hdr);
+ nexthdr = ip6->nexthdr;
+ }
+ len = skb->len - start;
+
+ while (nexthdr != target) {
+ struct ipv6_opt_hdr _hdr, *hp;
+ unsigned int hdrlen;
+
+ if ((!ipv6_ext_hdr(nexthdr)) || nexthdr == NEXTHDR_NONE) {
+ if (target < 0)
+ break;
+ return -ENOENT;
+ }
+
+ hp = skb_header_pointer(skb, start, sizeof(_hdr), &_hdr);
+ if (hp == NULL)
+ return -EBADMSG;
+ if (nexthdr == NEXTHDR_FRAGMENT) {
+ unsigned short _frag_off;
+ __be16 *fp;
+
+ if (flags) /* Indicate that this is a fragment */
+ *flags |= IP6_FH_F_FRAG;
+ fp = skb_header_pointer(skb,
+ start+offsetof(struct frag_hdr,
+ frag_off),
+ sizeof(_frag_off),
+ &_frag_off);
+ if (fp == NULL)
+ return -EBADMSG;
+
+ _frag_off = ntohs(*fp) & ~0x7;
+ if (_frag_off) {
+ if (target < 0 &&
+ ((!ipv6_ext_hdr(hp->nexthdr)) ||
+ hp->nexthdr == NEXTHDR_NONE)) {
+ if (fragoff)
+ *fragoff = _frag_off;
+ return hp->nexthdr;
+ }
+ return -ENOENT;
+ }
+ hdrlen = 8;
+ } else if (nexthdr == NEXTHDR_AUTH) {
+ if (flags && (*flags & IP6_FH_F_AUTH) && (target < 0))
+ break;
+ hdrlen = (hp->hdrlen + 2) << 2;
+ } else
+ hdrlen = ipv6_optlen(hp);
+
+ nexthdr = hp->nexthdr;
+ len -= hdrlen;
+ start += hdrlen;
+ }
+
+ *offset = start;
+ return nexthdr;
+}
+EXPORT_SYMBOL(ipv6_find_hdr);