On Fri, Jun 22, 2018 at 01:09:14AM +1000, Mark Andrews wrote:
> > So how should the DNS cookies be implemented? IMHO if one server uses
> > https://tools.ietf.org/html/rfc7873#appendix-B.1
> > and another server uses https://tools.ietf.org/html/rfc7873#appendix-B.2,
> > then it's not interoperable.
> > Actually the upcoming Knot DNS 2.7 implemented "B.1" using Siphash instead
> > of FNV. Bind probably implemented B.2.
> > Are both implementations correct?
>
> Well you are free to inspect the code to ensure that it behaves the way
> we said it did. The code is in lib/ns/client.c:compute_cookie. Older
> branches that is bin/named/client.c:compute_cookie
Mark, can you check the code in the compute_cookie() vs. RFC 7873 section B.2?
RFC 7873 says:
hash =
HMAC-SHA256-64( Server Secret,
(Client Cookie | Nonce | Time | Client IP Address) )
compute_cookie() seems to perform:
HMAC-SHA256-64( Server Secret,
(Client Cookie | Nonce | Time | Client IP Address | Client
Cookie) )
Both process_cookie() and ns_client_addopt() use the same
compute_cookie() to generate and verify, so it would be hard to spot
this.
Mukund
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