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Diffstat (limited to 'net/ipv6/exthdrs_core.c')
-rw-r--r--net/ipv6/exthdrs_core.c109
1 files changed, 109 insertions, 0 deletions
diff --git a/net/ipv6/exthdrs_core.c b/net/ipv6/exthdrs_core.c
new file mode 100644
index 00000000000..6dda815c013
--- /dev/null
+++ b/net/ipv6/exthdrs_core.c
@@ -0,0 +1,109 @@
+/*
+ * IPv6 library code, needed by static components when full IPv6 support is
+ * not configured or static.
+ */
+#include <net/ipv6.h>
+
+/*
+ * find out if nexthdr is a well-known extension header or a protocol
+ */
+
+int ipv6_ext_hdr(u8 nexthdr)
+{
+ /*
+ * find out if nexthdr is an extension header or a protocol
+ */
+ return ( (nexthdr == NEXTHDR_HOP) ||
+ (nexthdr == NEXTHDR_ROUTING) ||
+ (nexthdr == NEXTHDR_FRAGMENT) ||
+ (nexthdr == NEXTHDR_AUTH) ||
+ (nexthdr == NEXTHDR_NONE) ||
+ (nexthdr == NEXTHDR_DEST) );
+}
+
+/*
+ * Skip any extension headers. This is used by the ICMP module.
+ *
+ * Note that strictly speaking this conflicts with RFC 2460 4.0:
+ * ...The contents and semantics of each extension header determine whether
+ * or not to proceed to the next header. Therefore, extension headers must
+ * be processed strictly in the order they appear in the packet; a
+ * receiver must not, for example, scan through a packet looking for a
+ * particular kind of extension header and process that header prior to
+ * processing all preceding ones.
+ *
+ * We do exactly this. This is a protocol bug. We can't decide after a
+ * seeing an unknown discard-with-error flavour TLV option if it's a
+ * ICMP error message or not (errors should never be send in reply to
+ * ICMP error messages).
+ *
+ * But I see no other way to do this. This might need to be reexamined
+ * when Linux implements ESP (and maybe AUTH) headers.
+ * --AK
+ *
+ * This function parses (probably truncated) exthdr set "hdr"
+ * of length "len". "nexthdrp" initially points to some place,
+ * where type of the first header can be found.
+ *
+ * It skips all well-known exthdrs, and returns pointer to the start
+ * of unparsable area i.e. the first header with unknown type.
+ * If it is not NULL *nexthdr is updated by type/protocol of this header.
+ *
+ * NOTES: - if packet terminated with NEXTHDR_NONE it returns NULL.
+ * - it may return pointer pointing beyond end of packet,
+ * if the last recognized header is truncated in the middle.
+ * - if packet is truncated, so that all parsed headers are skipped,
+ * it returns NULL.
+ * - First fragment header is skipped, not-first ones
+ * are considered as unparsable.
+ * - ESP is unparsable for now and considered like
+ * normal payload protocol.
+ * - Note also special handling of AUTH header. Thanks to IPsec wizards.
+ *
+ * --ANK (980726)
+ */
+
+int ipv6_skip_exthdr(const struct sk_buff *skb, int start, u8 *nexthdrp, int len)
+{
+ u8 nexthdr = *nexthdrp;
+
+ while (ipv6_ext_hdr(nexthdr)) {
+ struct ipv6_opt_hdr _hdr, *hp;
+ int hdrlen;
+
+ if (len < (int)sizeof(struct ipv6_opt_hdr))
+ return -1;
+ if (nexthdr == NEXTHDR_NONE)
+ return -1;
+ hp = skb_header_pointer(skb, start, sizeof(_hdr), &_hdr);
+ if (hp == NULL)
+ BUG();
+ if (nexthdr == NEXTHDR_FRAGMENT) {
+ unsigned short _frag_off, *fp;
+ fp = skb_header_pointer(skb,
+ start+offsetof(struct frag_hdr,
+ frag_off),
+ sizeof(_frag_off),
+ &_frag_off);
+ if (fp == NULL)
+ return -1;
+
+ if (ntohs(*fp) & ~0x7)
+ break;
+ hdrlen = 8;
+ } else if (nexthdr == NEXTHDR_AUTH)
+ hdrlen = (hp->hdrlen+2)<<2;
+ else
+ hdrlen = ipv6_optlen(hp);
+
+ nexthdr = hp->nexthdr;
+ len -= hdrlen;
+ start += hdrlen;
+ }
+
+ *nexthdrp = nexthdr;
+ return start;
+}
+
+EXPORT_SYMBOL(ipv6_ext_hdr);
+EXPORT_SYMBOL(ipv6_skip_exthdr);