Subject: [pcp] unsupported version is underspecified

From: Francis Dupont <[email-masked]>
Date: Thu, 27 Oct 2011 16:36:23 +0200

In particular there is nothing in 7.3 page 21, cf:

   The PCP client receives the response and verifies that the source IP
   address and port belong to the PCP server of an outstanding PCP
   request.  It validates that the Opcode matches an outstanding PCP
   request.  Responses shorter than 24 octets, longer than 1024 octets,
   or not a multiple of 4 octets are invalid and ignored, likely causing
   the request to be re-transmitted.  The response is further matched by
   comparing fields in the response Opcode-specific data to fields in
   the request Opcode-specific data, as described by the processing for
   that Opcode.  After these matches are successful, the PCP client
   checks the Epoch field to determine if it needs to restore its state
   to the PCP server (see Section 7.5).

=> IMHO we have to insert something before the 24 length check.
Note it is enough to have 4 octets for an unsupported version error
response...

Regards

[email-masked]

PS: 7.6 pages 24 and 25 don't help as it is only about the way to
find a common version between the client and the server, and
specifies nothing about the unsupported version error response
after the 4 version octets (this is why I argue the content
should be these 4 octets).