Bugs in UDP-MIB and TCP-MIB (was: RE: MIB DOctor review of: draft-ietf-ipv6-inet-tunnel-mib-01.txt)

["C. M. Heard" <heard@pobox.com>]

On Thu, 12 Aug 2004, Dave Thaler wrote:
> >   3. According to RFC3291, if the address is unknown, then the
> >      value should be the zero-length octet string
> 
> My reading of 3291 is that the zero-length octet string is only used if 
> the InetAddressType is unknown.

http://www1.ietf.org/internet-drafts/draft-ietf-ops-rfc3291bis-05.txt
says something a little bit different -- an InetAddressType object
must assume the value unknown(0) if the corresponding InetAddress
object has zero length, but the reverse is not necessarily true,
per the following excerpt from the InetAddressType DESCRIPTION clause:

   unknown(0)  An unknown address type. This value MUST
               be used if the value of the corresponding
               InetAddress object is a zero-length string.
               It may also be used to indicate an IP address
               which is not in one of the formats defined
               below.

> If the type is known to be IPv4 or IPv6, then the zero-length
> octet string is not used.

That, however, is certainly true.


> [... ] The new UDP MIB says [ ... ] (and the TCP MIB has
> similar text):
>       an application which is willing to accept only IPv4
>       or only IPv6 datagrams is represented by a
>       udpEndpointLocalAddressType of the appropriate
>       address type, and udpEndpointLocalAddress of ''h (a
>       zero-length octet-string).
> 
> However, from RFC 3291 (unchanged in draft-ietf-ops-rfc3291bis-05.txt), 
> the definition of the InetAddressType says
>          ipv4(1)     An IPv4 address as defined by the
>                      InetAddressIPv4 textual convention.
> 
>          ipv6(2)     A global IPv6 address as defined by the
>                      InetAddressIPv6 textual convention.
> 
> And the SYNTAX clauses of those are:
> InetAddressIPv4 ::= TEXTUAL-CONVENTION
>     SYNTAX       OCTET STRING (SIZE (4))
> 
> InetAddressIPv6 ::= TEXTUAL-CONVENTION
>     SYNTAX       OCTET STRING (SIZE (16))
> 
> Since the 0-length string is not legal in those SYNTAX clauses,
> my reading is that the UDP-MIB (which is in IETF last call) 
> and TCP-MIB (which is in the RFC editors queue)
> interpretation is not legal, and the existing TUNNEL-MIB 
> interpretation is correct.
> 
> Or am I missing something?

IMHO, you are not.  I think that both of those documents need to be
corrected.  Fortunately, they are both blocked waiting for 3291bis,
since it is a normative reference in both.

I guess we would be covered by a Last Call comment on the UDP-MIB,
but we will have to ask for help from Bert and Margaret for the
TCP-MIB.

Mike