Re: A problem with RFC 6465's Uniform Format for Extension Headers

[Hagen Paul Pfeifer <[e-mail]>]

* Brian E Carpenter | 2014-02-04 10:43:40 [+1300]:

>Either solution works, but the firewall implementors might
>have a preference one way or the other. RFC 7045 says
>"Therefore, it is important that forwarding
>nodes that inspect IPv6 headers be able to parse all defined
>extension headers and deal with them appropriately,..."
>So the question is whether they would find a reserved
>range or a subtype easier to parse.

In the appendix of draft-pfeifer-6man-exthdr-res-01 I provided a patch against
Linux net-next-2.6 (see end of this email). In the end the compare do not
matter that match because one additional cmp is used which is fast.



diff --git a/net/ipv6/exthdrs_core.c b/net/ipv6/exthdrs_core.c
index 14ed0a9..d7f2e97 100644
--- a/net/ipv6/exthdrs_core.c
+++ b/net/ipv6/exthdrs_core.c
@@ -4,6 +4,9 @@
  */
 #include <net/ipv6.h>

+#define        IP6_EXTHDR_RESERVED_MIN 245
+#define        IP6_EXTHDR_RESERVED_MAX 252
+
 /*
  * find out if nxthdr is a well-known extension header or a protocol
  */
@@ -18,7 +21,8 @@ int ipv6_ext_hdr(u8 nexthdr)
                 (nexthdr == NEXTHDR_FRAGMENT)  ||
                 (nexthdr == NEXTHDR_AUTH)      ||
                 (nexthdr == NEXTHDR_NONE)      ||
-                (nexthdr == NEXTHDR_DEST);
+                (nexthdr == NEXTHDR_DEST)      ||
+                (nexthdr >= IP6_EXTHDR_RESERVED_MIN &&
+                 nexthdr <= IP6_EXTHDR_RESERVED_MAX);
 }