dnsop J. Yao Internet-Draft P. Vixie Intended status: Standards Track CNNIC-Farsight Joint Laboratory Expires: April 27, 2017 N. Kong X. Li CNNIC October 24, 2016 A DNS Query including A Main Question with Accompanying Questions draft-yao-dnsop-accompanying-questions-01 Abstract This document enables DNS initiators to send a main question accompanying with several related questions in a single DNS query, and enables DNS responders to put the answers into a single DNS response. This mechanism can reduce the number of DNS round-trips per application work-unit. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on April 27, 2017. Copyright Notice Copyright (c) 2016 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must Yao, et al. Expires April 27, 2017 [Page 1] Internet-Draft accompanying-queries October 2016 include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Mechanism for a main question with accompanying questions . . 3 4. Responder Processing . . . . . . . . . . . . . . . . . . . . 5 5. Initiator Processing . . . . . . . . . . . . . . . . . . . . 5 6. Query and Response Example . . . . . . . . . . . . . . . . . 6 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 8. Security Considerations . . . . . . . . . . . . . . . . . . . 7 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7 10. Change History . . . . . . . . . . . . . . . . . . . . . . . 7 10.1. draft-yao-dnsop-accompanying-questions: Version 00 . . . 7 10.2. draft-yao-dnsop-accompanying-questions: Version 01 . . . 7 11. Normative References . . . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 1. Introduction There are many scenarios in which an application must send several related questions to a DNS responder. For examples, when asking about a QTYPE=A RRset, a QTYPE=AAAA RRset may also be of use [RFC 5321]; When asking for some RRset of www.example.com about A and AAAA, records of a sub-domain name such as _443._tcp.www.example.com for TLSA may be of interest[RFC 6698]. Query example.com for A and AAAA Query www.example.com for A and AAAA, and _443._tcp.www.example.com for TLSA Yao, et al. Expires April 27, 2017 [Page 2] Internet-Draft accompanying-queries October 2016 This document describes a method by which DNS initiators can send a main question accompanying with several related questions in a single DNS query, and enables DNS responders place all related answers into a single DNS response. This mechanism can reduce the number of DNS round-trips per application work-unit, by carrying several related queries in a single query transaction. 2. Terminology The basic key words such as "MUST", "MUST NOT", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "MAY", and "MAYNOT" are to be interpreted as described in [RFC2119]. The basic DNS terms used in this specification are defined in the documents [RFC1034] and [RFC1035]. 3. Mechanism for a main question with accompanying questions The initiator still puts a main question into the question section of the DNS query packet, as described in [RFC1035]. Accompanying questions will be put into the variable part of an OPT RR [RFC6891]. The variable part of an OPT RR is encoded in its RDATA and is structured as the following: +0 (MSB) +1 (LSB) +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ 0: | OPTION-CODE | +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ 2: | OPTION-LENGTH | +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ 4: | | / OPTION-DATA / / / +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ OPTION-CODE (Assigned by IANA.) OPTION-LENGTH Size (in octets) of OPTION-DATA. OPTION-DATA including at most 8 accompanying questions with AQ-RCODE. Yao, et al. Expires April 27, 2017 [Page 3] Internet-Draft accompanying-queries October 2016 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ |AQ | Count | AQ-RCODE | +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ | AQ-TYPE | +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ | | / Prefix / / / +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ |AQ | Seq | AQ-RCODE | +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ | AQ-TYPE | +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ | | / Prefix / / / +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ |AQ | Seq | AQ-RCODE | +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ | AQ-TYPE | +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ | | / Prefix / / / +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ | | / ...... / / / o AQ field indicates whether this accompanying question is the first question. If it is set as 1, this question is the first question. o Count field represents the total numbers of all accompanying questions. Seq field represents the sequence number of accompanying questions from 1 to 7 There will have at most 8 accompanying questions. o AQ-RCODE field will be set to 111111110100 bits when being initialized. The AQ-RCODE with the value of 111111110100 bits means that the mechanism for accompanying has not been implemented, where "0100" in the RCODE value is "not been implemented". The AQ aware responders will put the RCODE value for the query of this question into AQ-RCODE fields. Yao, et al. Expires April 27, 2017 [Page 4] Internet-Draft accompanying-queries October 2016 o Prefix field is a substring between the main domain name of the main quesiton and the accompanying domain name of the accompanying question. That is, if the main domain name is string S and the accompanying domain name is string S1, the prefix is (S-S1). For an example, if the main domain name is example.com and the accompanying domain name is mail.example.com, the prefix is "mail.". 4. Responder Processing The AQ aware responder will check the main question first, and put the results into the DNS response packet. If the AQ OPT is present, the responder assembles the prefix with the main domain name and make it to be an accompanying question, checks the accompanying questions in order, and put the results into the DNS answer section of the response following RFC 1034; but the response code is placed in the respective AQ-RCODE field in AQ OPT of the response. The RCODE field in the DNS response header refers to the main question only. An AQ unaware responder is expected to ignore the AQ OPT of the query, and may echo the received OPT back into additional section of the response message. 5. Initiator Processing An AQ aware initiator will put the main question into the question section of the DNS query packet, and put related accompanying questions into the Accompanying Question fields of OPTION-DATA of OPT RR. AQ-RCODE value will be sent as 111111110100 bits. The AQ value should be set to 1 and Count value should be set to total number of accompanying questions, if the accompanying question is the first one; For the remain accompanying questions, the AQ value should be set to 0 and Seq value should be set to the sequence of the corresponding accompanying questions. The AQ-TYPE value should be set as the query type related accomanying questions. The Prefix should be set as the substring between the main domain name of the main quesiton and the accompanying domain name of the accompanying question. If the main domain name and the accompanying domain name are same, the Prefix should be set as all zero bits. If the initial value of the AQ-RCODE is unchanged in the response, it indicates that the responder is AQ unaware. In that case, the responder will deal with the main question only. The initiator should sent the accompanying questions one by one via the normal DNS query. In such followup related queries, AQ processing should probably not be attempted, to reduce waste of network resources. Yao, et al. Expires April 27, 2017 [Page 5] Internet-Draft accompanying-queries October 2016 6. Query and Response Example Example: one main question with 2 accompanying questions The query would look like: +---------------------------------------------------+ Header | OPCODE=SQUERY | +---------------------------------------------------+ Question | QNAME=EXAMPLE.COM., QCLASS=IN, QTYPE=A | +---------------------------------------------------+ Answer | | +---------------------------------------------------+ Authority | | +---------------------------------------------------+ Additional | | | AQ=1,Count=2,AQ-TYPE=AAAA,AQ-RCODE=111111110100, | | Prefix=0, | | AQ=0, SEQ=1,AQ-TYPE=TLSA,,AQ-RCODE=111111110100, | | Prefix=_443._tcp., | +---------------------------------------------------+ The response from AQ aware responders would be: +---------------------------------------------------+ Header | OPCODE=SQUERY, RESPONSE, AA, RCODE=NOERROR | +---------------------------------------------------+ Question | QNAME=EXAMPLE.COM., QCLASS=IN, QTYPE=A | +---------------------------------------------------+ Answer | example.com IN A 192.168.0.1 | | example.com. IN AAAA 2001:cc8::1 | | _443._tcp.example.com. IN TLSA | | ( 3 0 0 30820307308201efa003020102020... ) | +---------------------------------------------------+ Authority | | +---------------------------------------------------+ Additional | | | AQ=1, COUNT=2, AQ-TYPE=AAAA, AQ-RCODE=NOERROR, | | Prefix=0, | | AQ=0, SEQ=1, AQ-TYPE=TLSA, AQ-RCODE=NOERROR, | | Prefix=443._tcp., | +---------------------------------------------------+ The response from AQ unaware responders would be: +---------------------------------------------------+ Header | OPCODE=SQUERY, RESPONSE, AA, RCODE=NOERROR | Yao, et al. Expires April 27, 2017 [Page 6] Internet-Draft accompanying-queries October 2016 +---------------------------------------------------+ Question | QNAME=EXAMPLE.COM., QCLASS=IN, QTYPE=A | +---------------------------------------------------+ Answer | example.com IN A 192.168.0.1 | +---------------------------------------------------+ Authority | | +---------------------------------------------------+ Additional | | | AQ=1, COUNT=2, AQ-TYPE=AAAA,AQ-RCODE=111111110100,| | Prefix=0, | | AQ=0, SEQ=1, AQ-TYPE=TLSA, AQ-RCODE=111111110100, | | Prefix=443._tcp., | +---------------------------------------------------+ 7. IANA Considerations IANA should allocate DNS EDNS0 Option Codes (OPT) following this document. IANA should reserve RCODE with the value of 111111110100 bits for this document. 8. Security Considerations TBD 9. Acknowledgements The authors thank the members in DNSOP mailing list for helpful discussions, and especially thank Kazunori Fujiwara for kind comments, suggestions and improvments for the document. 10. Change History RFC Editor: Please remove this section. 10.1. draft-yao-dnsop-accompanying-questions: Version 00 o A Mechanism for DNS query including one main question with several accompanying questions 10.2. draft-yao-dnsop-accompanying-questions: Version 01 o Simpilfy the mechanism. Yao, et al. Expires April 27, 2017 [Page 7] Internet-Draft accompanying-queries October 2016 11. Normative References [RFC1034] Mockapetris, P., "Domain names - concepts and facilities", STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987, . [RFC1035] Mockapetris, P., "Domain names - implementation and specification", STD 13, RFC 1035, DOI 10.17487/RFC1035, November 1987, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC5321] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321, DOI 10.17487/RFC5321, October 2008, . [RFC6698] Hoffman, P. and J. Schlyter, "The DNS-Based Authentication of Named Entities (DANE) Transport Layer Security (TLS) Protocol: TLSA", RFC 6698, DOI 10.17487/RFC6698, August 2012, . [RFC6891] Damas, J., Graff, M., and P. Vixie, "Extension Mechanisms for DNS (EDNS(0))", STD 75, RFC 6891, DOI 10.17487/RFC6891, April 2013, . Authors' Addresses Jiankang Yao CNNIC-Farsight Joint Laboratory 4 South 4th Street,Zhongguancun,Haidian District Beijing, Beijing 100190 China Phone: +86 10 5881 3007 Email: yaojk@cnnic.cn Yao, et al. Expires April 27, 2017 [Page 8] Internet-Draft accompanying-queries October 2016 Paul Vixie CNNIC-Farsight Joint Laboratory 4 South 4th Street,Zhongguancun,Haidian District Beijing, Beijing 100190 China Phone: +1 650 489 7919 Email: vixie@fsi.io Ning Kong CNNIC 4 South 4th Street,Zhongguancun,Haidian District Beijing, Beijing 100190 China Phone: +86 10 5881 3147 Email: nkong@cnnic.cn Xiaodong Li CNNIC 4 South 4th Street,Zhongguancun,Haidian District Beijing, Beijing 100190 China Phone: +86 10 5881 3020 Email: xl@cnnic.cn Yao, et al. Expires April 27, 2017 [Page 9]