Thanks for your feedback about the extended errors draft. Below are responses to some of your previously raised points in email to dnsop:
8.2 Stephane Bortzmeyer ~~~~~~~~~~~~~~~~~~~~~~~ At the IETF 104 hackathon in Prague, Vladimír Čunát and myself implemented it in the Knot resolver [https://www.knot-resolver.cz/]. You can see the result in the git merge request [https://gitlab.labs.nic.cz/knot/knot-resolver/merge_requests/794] (branch extended_error [https://gitlab.labs.nic.cz/knot/knot-resolver/tree/extended_error]). 8.2.1 DONE > 4.1.5. SERVFAIL Extended DNS Error Code 5 - DNSSEC Indeterminate ------------------------------------------------------------------------------ > The resolver attempted to perform DNSSEC validation, but > validation ended in the Indeterminate state. The R flag should > not be set. Isn't there an error here? 4.1 is the section for NOERROR. What should be returned for DNSSEC Indeterminate? NOERROR or SERVFAIL? (In the first case, change the text, in the second, move this paragraph to 4.2.) Now, implementation experience. We tested with Wireshark and dig (did not try to develop a client using the extended error code, just the server). As expected, producing extended error codes is quite simple and the draft is clear. The camel will be happy. + Response: With the recent removal of the RCODE binding, I think this problem goes away. Correct? 8.2.2 DONE The biggest issue is of course to find out what to put in the extended --------------------------------------------------------------------------------- error code. On some resolvers (at least on Knot), the place where the error is noticed can be quite far from the place where the answer is built, with its EDNS options. In practice, we had to add data to the request object, for the extended error information to be carried to the module that emits the extended error code EDNS option. So, the real difficulty is not in the draft, but in knowing and understanding your resolver. + Response: As agreed to in IETF105, we've removed the RCODE binding. Some details: 8.2.3 NOCHANGE * no resolver will use all the response-code/info-codes because some ----------------------------------------------------------------------------------- are never reached for this resolver, or are mixed with other issues. Generic errors (such as "SERVFAIL Extended DNS Error Code 1 - DNSSEC Bogus") are useful for when you cannot reliably find the problem. + Response: I'm not sure what change you're suggesting. Removal of the binding may help, and I don't think there is an expectation that every implementation should be able to return every code. I'd expect the union of all implementations to find the ability to return each code, but not each implementation itself? 8.2.4 DONE * the draft is silent about the laying out of bits in info-code. Not ------------------------------------------------------------------------------- many IETF protocols have an integer field which is larger than a byte but not byte-aligned. + Response: Good point; added encoding rules (MSB) 8.2.5 NOCHANGE * the draft has a passing mention that multiple extended error options ------------------------------------------------------------------------------------- are allowed but I don't see how it could be used by the poor client trying to figure out what happened. I suggest to disallow it. + Response: Most clients should be logging the resulting findings, or displaying them maybe. We don't expect this option to be used for anything other than debugging, especially because its not authenticated. The client also has to be prepared to accept multiple options anyway, as not doing so is equally as problematic (IE, assuming no one will send you more than one option is a sure path to crashing or other problem) 8.2.6 NOCHANGE * the draft has (rightly so) two info-codes for NXDOMAIN/Blocked and ----------------------------------------------------------------------------------- NXDOMAIN/Censored but Knot cannot use it currently since the policy module (written in Lua) has no way today to be configured to express the difference. Not a problem in the draft but it will be probably a common case that the resolver cannot make use of *all* codes. + Response: Yep, per above I suspect different implementations may need to return different codes based on their implementation needs. The point is to turn the right code to help users/debuggers. 8.2.7 NOCHANGE Let's end with a few examples: --------------------------------------------- 4.2.2. SERVFAIL Extended DNS Error Code 2 - Signature Expired % dig @::1 -p 9053 A servfail.nl ... ;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 12100 ;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1 ;; OPT PSEUDOSECTION: EDNS: version: 0, flags: do; udp: 4096 ; OPT=65500: 00 00 20 02 44 4e 53 53 45 43 20 65 78 70 69 72 65 64 20 ; 73 69 67 6e 61 74 75 72 65 73 (".. .DNSSEC expired signatures") ... 4.2.7. SERVFAIL Extended DNS Error Code 7 - No Reachable Authority % dig @::1 -p 9053 A brk.internautique.fr ... ;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 38620 ;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1 ;; OPT PSEUDOSECTION: EDNS: version: 0, flags: do; udp: 4096 ; OPT=65500: 80 00 20 07 6e 6f 20 4e 53 20 77 69 74 68 20 61 6e 20 61 ; 64 64 72 65 73 73 (".. .no NS with an address") ... (Not an ideal message but this is quite generic code in Knot.) 4.5.1. NXDOMAIN Extended DNS Error Code 1 - Blocked % dig @::1 -p 9053 A googleanalytics.com ... ;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 1189 ;; flags: qr aa rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 2 ;; OPT PSEUDOSECTION: EDNS: version: 0, flags: do; udp: 4096 ; OPT=65500: 80 00 30 01 4e 6f 20 74 72 61 63 6b 69 6e 67 ("..0.No ; tracking") ; QUESTION SECTION: googleanalytics.com. IN A ;; AUTHORITY SECTION: googleanalytics.com. 10800 IN SOA googleanalytics.com. nobody.invalid. ( 1 ; serial 3600 ; refresh (1 hour) 1200 ; retry (20 minutes) 604800 ; expire (1 week) 10800 ; minimum (3 hours) ) ;; ADDITIONAL SECTION: explanation.invalid. 10800 IN TXT "No tracking" -- Wes Hardaker USC/ISI _______________________________________________ DNSOP mailing list [email protected] https://www.ietf.org/mailman/listinfo/dnsop
