On 21.3.2017 20:34, Jan Komissar (jkomissa) wrote: > Hi, > > I have one comment for this draft. In Section 3.3 Message Format, I would > prefer that if a Session Signaling message is received where any of the > section count fields are not zero, the receiver MUST respond with an error > code, e.g. FORMERR, but MUST NOT terminate the connection. My reason is that > in order to ignore any non-zero count fields, the receiving software must > have code to walk all the sections and this code would effectively be > useless, but would still have to be properly maintained. The soft error > response is required to make it possible for a future client to probe servers > for support for a future Session Signaling based feature that uses the RR > sections.
(Jan, thank you for reminding me to review this version!) Other people already commented on semantics so I will focus on message format: My attempts to find reasoning for the new TLV format in archives did not yield an elaborate explanation. Assuming I did not miss anything, it seems to me that the current TLV format (placed outside of standard DNS RR) is going to require brand new code and logic and makes imlementation harder than necessary. Every DNS server and resolver already has own code to parse DNS RRs do various operations with them but this could cannot be reused for the current TLV format. It would be much easier to implement if we had new RRs like (e.g.) "SSOP" and "SSMOD" and placed them inside additional section. We could get the same semantics by creating a DNS message with all sections empty except "SS*" RRs in additional section. Overhead on wire is negligible and it makes implementation much easier and safer (because the normal RR handling code is battle-tested already). For these reasons I propose to move to standard RR format to enable code re-use. Thank you for considering this. Petr Špaček @ CZ.NIC > Jan. > > > On 3/13/17, 7:44 PM, "DNSOP on behalf of internet-dra...@ietf.org" > <dnsop-boun...@ietf.org on behalf of internet-dra...@ietf.org> wrote: > > > A New Internet-Draft is available from the on-line Internet-Drafts > directories. > This draft is a work item of the Domain Name System Operations of the > IETF. > > Title : DNS Session Signaling > Authors : Ray Bellis > Stuart Cheshire > John Dickinson > Sara Dickinson > Allison Mankin > Tom Pusateri > Filename : draft-ietf-dnsop-session-signal-02.txt > Pages : 25 > Date : 2017-03-13 > > Abstract: > The EDNS(0) Extension Mechanism for DNS is explicitly defined to only > have "per-message" semantics. This document defines a new Session > Signaling Opcode used to communicate persistent "per-session" > operations, expressed using type-length-value (TLV) syntax, and > defines an initial set of TLVs used to manage session timeouts and > termination. > > > The IETF datatracker status page for this draft is: > https://datatracker.ietf.org/doc/draft-ietf-dnsop-session-signal/ > > There's also a htmlized version available at: > https://tools.ietf.org/html/draft-ietf-dnsop-session-signal-02 > > A diff from the previous version is available at: > https://www.ietf.org/rfcdiff?url2=draft-ietf-dnsop-session-signal-02 > > > Please note that it may take a couple of minutes from the time of > submission > until the htmlized version and diff are available at tools.ietf.org. > > Internet-Drafts are also available by anonymous FTP at: > ftp://ftp.ietf.org/internet-drafts/ _______________________________________________ DNSOP mailing list DNSOP@ietf.org https://www.ietf.org/mailman/listinfo/dnsop
