Internet DRAFT - draft-lenders-dns-cbor
draft-lenders-dns-cbor
CBOR M. S. Lenders
Internet-Draft FU Berlin
Intended status: Standards Track C. Bormann
Expires: 14 September 2023 Universität Bremen TZI
T. C. Schmidt
HAW Hamburg
M. Wählisch
FU Berlin
13 March 2023
A Concise Binary Object Representation (CBOR) of DNS Messages
draft-lenders-dns-cbor-02
Abstract
This document specifies a compressed data format of DNS messages
using the Concise Binary Object Representation [RFC8949]. The
primary purpose is to keep DNS messages small in constrained
networks.
About This Document
This note is to be removed before publishing as an RFC.
The latest revision of this draft can be found at https://anr-bmbf-
pivot.github.io/draft-lenders-dns-cbor/draft-lenders-dns-cbor.html.
Status information for this document may be found at
https://datatracker.ietf.org/doc/draft-lenders-dns-cbor/.
Discussion of this document takes place on the CBOR Working Group
mailing list (mailto:cbor@ietf.org), which is archived at
https://mailarchive.ietf.org/arch/browse/cbor/. Subscribe at
https://www.ietf.org/mailman/listinfo/cbor/.
Source for this draft and an issue tracker can be found at
https://github.com/anr-bmbf-pivot/draft-lenders-dns-cbor.
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 https://datatracker.ietf.org/drafts/current/.
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Internet-Drafts are draft documents valid for a maximum of six months
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This Internet-Draft will expire on 14 September 2023.
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document authors. All rights reserved.
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. CBOR Representations (application/dns+cbor) . . . . . . . . . 4
3.1. Domain Name Representation . . . . . . . . . . . . . . . 4
3.2. Standard DNS Resource Records (RRs) . . . . . . . . . . . 4
3.3. DNS Queries . . . . . . . . . . . . . . . . . . . . . . . 6
3.4. DNS Responses . . . . . . . . . . . . . . . . . . . . . . 7
3.5. EDNS(0) . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.6. Name and Address Compression with Packed CBOR . . . . . . 9
3.6.1. Table Setup . . . . . . . . . . . . . . . . . . . . . 11
4. Security Considerations . . . . . . . . . . . . . . . . . . . 11
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
5.1. Media Type Registration . . . . . . . . . . . . . . . . . 12
5.1.1. "application/dns+cbor" . . . . . . . . . . . . . . . 12
5.2. CoAP Content-Format Registration . . . . . . . . . . . . 13
5.2.1. "application/dns-cbor" . . . . . . . . . . . . . . . 13
5.2.2. "application/dns+cbor;packed=1" . . . . . . . . . . . 13
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
6.1. Normative References . . . . . . . . . . . . . . . . . . 13
6.2. Informative References . . . . . . . . . . . . . . . . . 14
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 15
A.1. DNS Queries . . . . . . . . . . . . . . . . . . . . . . . 15
A.2. DNS Responses . . . . . . . . . . . . . . . . . . . . . . 16
Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 17
B.1. Since [draft-lenders-dns-cbor-01] . . . . . . . . . . . . 17
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B.2. Since draft-lenders-dns-cbor-00 . . . . . . . . . . . . . 17
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18
1. Introduction
In constrained networks [RFC7228], the link layer may restrict the
payload sizes to only a few hundreds bytes. Encrypted DNS
resolution, such as DNS over HTTPS (DoH) [RFC8484] or DNS over CoAP
(DoC) [I-D.ietf-core-dns-over-coap], may lead to DNS message sizes
that exceed this limit, even when implementing header compression
such as 6LoWPAN IPHC [RFC6282] or SCHC [RFC8724], [RFC8824].
Although adoption layers such as 6LoWPAN [RFC4944] or SCHC [RFC8724]
offer fragmentation to comply with small MTUs, fragmentation should
be avoided in constrained networks, because fragmentation combined
with high packet loss multiplies the loss. As such, a compression
format for DNS messages is needed.
This document specifies a compressed data format for DNS messages.
DNS messages are encoded in Concise Binary Object Representation
(CBOR) [RFC8949] and, additionally, unnecessary or redundant
information is removed. To use the outcome of this specification in
DoH and DoC, this document also specifies a Media Type header for DoH
and a Content-Format option for DoC.
2. Terminology
CBOR types (unsigned integer, byte string, text string, arrays, etc.)
are used as defined in [RFC8949].
TBD DNS server and client.
A DNS query is a message that queries DNS information from an
upstream DNS resolver.
The term "constrained networks" is used as defined in [RFC7228].
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
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3. CBOR Representations (application/dns+cbor)
To keep overhead minimal, a DNS message is represented as CBOR
arrays. All CBOR items used in this specification are of definite
length. CBOR arrays that do not follow the length definitions of
this or follow-up specifications, MUST be silently ignored. It is
assumed that DNS query and DNS response are distinguished message
types and that the query can be mapped to the response by the
transport protocol of choice. To define the representation of binary
objects we use the Concise Data Definition Language (CDDL) [RFC8610].
If, for any reason, a DNS message is not representable in the CBOR
format specified in this document, a fallback to the another DNS
message format, e.g., the classic DNS wire format, MUST always be
possible.
3.1. Domain Name Representation
Domain names are represented in their commonly known string format
(e.g., "example.org", see Section 2.3.1 in [RFC1035]) and in IDNA
encoding [RFC5890] as a text string. For the purpose of this
document, domain names remain case-insensitive as specified in
[RFC1035].
The representation of a domain name is defined in Figure 1.
domain-name = tstr .regexp "([^.]+\.)*[^.]+"
Figure 1: Domain Name Definition
3.2. Standard DNS Resource Records (RRs)
DNS resource records are encoded either in their binary form as a
byte string or as CBOR arrays containing 2 to 5 entries in the
following order:
1. An optional name (as text string, see Section 3.1),
2. A TTL (as unsigned integer),
3. An optional record type (as unsigned integer),
4. An optional record class (as unsigned integer), and lastly
5. A record data entry (as unsigned integer, negative integer, byte
string, or text string).
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If the first item of the resource record is a text string, it is its
name. If the name is elided, the name is derived from the question
section of the message. For responses, the question section is
either taken from the query (see Section 3.3) or provided with the
response see Section 3.4. The query may be derived from the
transport context.
If the record type is elided, the record type from the question is
assumed. If record class is elided, the record class from the
question is assumed. When a record class is required, the record
type MUST also be provided.
The byte format of the record data as a byte string follows the wire
format as specified in Section 3.3 [RFC1035] (or other specifications
of the respective record type). Note that this format does not
include the RDLENGTH field from [RFC1035] as this value is encoded in
the length field of the CBOR byte string.
If the record data represents a domain name (e.g., for CNAME or PTR
records), the record data MAY be represented as a text string as
specified in Section 3.1. This can save 1 byte of data, because the
byte representation of DNS names requires both an additional byte to
define the length of the first name component and well as a zero byte
at the end of the name. With CBOR on the other hand only 1 byte is
required to define type and length of the text string up until a
string length of 23 characters. Likewise, if the record data is
purely a numerical value, it can be expressed as either an unsigned
or negative integer.
The representation of a DNS resource records is defined in Figure 2.
type-spec = (
record-type: uint,
? record-class: uint,
)
rr = (
? name: domain-name,
ttl: uint,
? type-spec,
rdata: int / bstr / domain-name,
)
dns-rr = [rr] / bstr
Figure 2: DNS Resource Record Definition
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3.3. DNS Queries
DNS queries are encoded as CBOR arrays containing up to 5 entries in
the following order:
1. An optional transaction ID (as unsigned integer),
2. An optional flag field (as unsigned integer),
3. The question section (as array),
4. An optional authority section (as array), and
5. An optional additional section (as array)
If the first item of the query is an array, it is the question
section, if it is an unsigned integer, it is the transaction ID. If
the transaction ID is present and followed by another unsigned
integer, that item is a flag field and maps to the header flags in
[RFC1035] and the "DNS Header Flags" IANA registry including the QR
flag and the Opcode. It MUST be lesser than 2^16.
If the transaction ID is elided, the value 0 is assumed, same for the
flags. The transaction ID MUST be included and set to an
unpredictable value lesser than 2^32, if the DNS transport can not
ensure the prevention of DNS response spoofing. An example for such
a transport is unencrypted DoC (see [I-D.ietf-core-dns-over-coap],
Section 6).
The question section is encoded as a CBOR array containing up to 3
entries:
1. The queried name (as text string, see Section 3.1),
2. An optional record type (as unsigned integer), and
3. An optional record class (as unsigned integer)
If the record type is elided, record type AAAA as specified in
[RFC3596] is assumed. If the record class is elided, record class IN
as specified in [RFC1035] is assumed. When a record class is
required, the record type MUST also be provided.
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The remainder of the query is either empty or MUST consist of up to
two arrays. The first array, if present, encodes the authority
section of the query as an array of DNS resource records (see
Section 3.2) The second array, if present, encodes the additional
section of the query as an array of DNS resource records (see
Section 3.2)
The representation of a DNS query is defined in Figure 3.
query-id-flags = (
id: uint .default 0,
? flags: uint .default 0,
)
question-section = (
name: domain-name,
? type-spec,
)
extra-sections = (
? authority: [+ dns-rr],
additional: [+ dns-rr],
)
query-sections = (
? query-id-flags,
[question-section],
? extra-sections,
)
dns-query = [query-sections]
Figure 3: DNS Query Definition
3.4. DNS Responses
DNS responses are encoded as a CBOR array containing up to 7 entries.
1. An optional transaction ID (as unsigned integer),
2. An optional flag field (as unsigned integer),
3. An optional question section (as array, encoded as described in
Section 3.3)
4. The answer section (as array),
5. An optional authority section (as array), and
6. An optional additional section (as array)
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If the CBOR array is a response to a query that contains a
transaction ID, it MUST be included and set to the corresponding
value present in the query. If it is not included, the transaction
ID is implied to be 0.
If the CBOR array is a response to a query for which the flags
indicate that flags are set in the response, they MUST be set
accordingly and thus included in the response. If the flags are not
included, the flags are implied to be 0x8000 (everything unset except
for the QR flag).
If the response includes only 1 array, this is the DNS answer section
represented as an array of one or more DNS Resource Records (see
Section 3.2).
If the response includes 2 arrays, the first entry is a question
section and the second entry is an answer section. The question
section is encoded like as specified in Section 3.3, the answer
section is represented as an array of one or more DNS Resource
Records (see Section 3.2).
If the response includes 3 arrays, the first section is a question
section, the second an answer section, and the third an additional
section (TBD: back choice to favor additional section by empirical
data). Again, the question section is encoded like a DNS query as
specified in Section 3.3 and both answer and additional sections are
represented each as an array of one or more DNS Resource Records (see
Section 3.2).
If the response includes 4 arrays, the first section is a question
section, the second an answer section, the third an authority
section, and the fourth an additional section (TBD: back by empirical
data). They follow the specification of 3 arrays in the answer. The
authority section is also represented as an array of one or more DNS
Resource Records (see Section 3.2).
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response-id-flags = (
id: uint .default 0,
? flags: uint .default 0x8000,
)
response-sections = ((
? response-id-flags,
answer: [+ dns-rr],
) // (
? response-id-flags,
question: [question-section],
answer: [+ dns-rr],
? extra-sections,
))
dns-response = [response-sections]
Figure 4: DNS Response Definition
3.5. EDNS(0)
TBD, do we need special formatting here?
3.6. Name and Address Compression with Packed CBOR
If both DNS server and client support packed CBOR
[I-D.ietf-cbor-packed], it MAY be used for name and address
compression in DNS responses.
A DNS client uses media type "application/dns+cbor;packed=1" to
negotiate (see, e.g., [RFC9110] or [RFC7252], Section 5.5.4) with the
DNS server if the server supports packed CBOR. If it does, it MAY
request the response to be in packed CBOR (media type "applicaton/
dns+cbor;packed=1"). The server then SHOULD reply with the response
in packed CBOR.
The representation of DNS responses in packed CBOR differs, in that
responses are now represented as a CBOR array of two arrays. The
first array is a packing table that is used both as shared item table
and argument table (see [I-D.ietf-cbor-packed], Section 2.1), the
second is the compressed response.
The representation of a packed DNS response is defined in Figure 5.
compr-dns-response = any /TBD; how to express packed CBOR in CDDL?/
packed-dns-response = [[pack-table], compr-dns-response]
pack-table = any
Figure 5: Definition of DNS messages in packed CBOR
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If an index in the packing table is referenced with shared item
reference ([I-D.ietf-cbor-packed], Section 2.2) a decoder uses the
packing table as a shared item table. If an index in the packing
table is referenced as an argument ([I-D.ietf-cbor-packed], Sections
2.3 and 4), a decoder uses the packing table as an argument table.
Discussion TBD:
* For queries, as they are only one question, i.e. at most one value
of each at most, compression is not necessary.
* Address and name compression are mostly about affix compression
(i.e. straight/inverse referencing)
==> For occasions were value is the affix (e.g., "example.org" in
ANY example in Appendix A.2) use shared item referencing to
argument table to safe bytes (no extra shared item table, no,
e.g., 216(""), just simple(0))
- *Example:* Using Basic Packed CBOR ([I-D.ietf-cbor-packed],
section 3.1):
o 131 bytes (Basic Packed CBOR)
o 200 bytes (plain CBOR, see Appendix A.2)
o 194 bytes (wire-format)
113(
[
["_coap._udp.local", "example.org", 3600, 28, 2],
[h'20010db800000000000000000000', simple(1)],
[
[simple(1), 12, 1],
[[simple(1), simple(0)]],
[
[simple(1), simple(4), 217("ns1.")],
[simple(1), simple(4), 217("ns2.")]
],
[
[simple(0), simple(1), simple(3), 6(h'0001')],
[simple(0), simple(1), simple(3), 6(h'0002')],
[217("ns1."), simple(1), simple(3), 6(h'0035')],
[217("ns2."), simple(1), simple(3), 6(h'3535')]
]
]
]
)
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vs. application/dns+cbor;packed=1 (shared and argument table as
one) 126 bytes:
[
[
h'20010db800000000000000000000',
"_coap._udp.local" "example.org", 3600, 28, 2
],
[
[simple(2), 12, 1],
[[simple(3), simple(1)]],
[
[simple(2), simple(5), 218("ns1.")],
[simple(2), simple(5), 218("ns2.")]
],
[
[simple(1), simple(3), simple(4), 6(h'0001')],
[simple(1), simple(3), simple(4), 6(h'0002')],
[218("ns1."), simple(3), simple(4), 6(h'0035')],
[218("ns2."), simple(3), simple(4), 6(h'3535')]
]
]
]
3.6.1. Table Setup
TBD How to construct the packing table, here's a sketch:
* Find most often used prefix and values
- Probably some threshold needed, to prevent, e.g., 1 byte
prefixes filling valuable table space
* Sort descending by number of occurrences and length
- Long prefixes should take precedence for index 0 for Tag 6
usage
4. Security Considerations
TODO Security
5. IANA Considerations
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5.1. Media Type Registration
This document registers a media type for the serialization format of
DNS messages in CBOR. It follows the procedures specified in
[RFC6838].
5.1.1. "application/dns+cbor"
Type name: application
Subtype name: dns+cbor
Required parameters: None
Optional parameters: packed
Encoding considerations: Must be encoded as using [RFC8949]. See
[TBD-this-spec] for details.
Security considerations: See Section 4 of this draft
Interoperability considerations: TBD
Published specification: [TBD-this-spec]
Applications that use this media type: TBD DNS over X systems
Fragment Identifier Considerations: TBD
Additional information:
Deprecated alias names for this type: N/A
Magic number(s): N/A
File extension(s): dnsc
Macintosh file type code(s): none
Person & email address to contact for further information: Martine S.
Lenders m.lenders@fu-berlin.de (mailto:m.lenders@fu-berlin.de)
Intended usage: COMMON
Restrictions on Usage: None?
Author: Martine S. Lenders m.lenders@fu-berlin.de
(mailto:m.lenders@fu-berlin.de)
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Change controller: Martine S. Lenders m.lenders@fu-berlin.de
(mailto:m.lenders@fu-berlin.de)
Provisional registrations? No
5.2. CoAP Content-Format Registration
IANA is requested to assign CoAP Content-Format ID for the new DNS
message media types in the "CoAP Content-Formats" sub-registry,
within the "CoRE Parameters" registry [RFC7252], corresponding the
"application/dns+cbor" media type specified in Section 5.1:
5.2.1. "application/dns-cbor"
Media-Type: application/dns+cbor
Encoding: -
Id: TBD
Reference: [TBD-this-spec]
5.2.2. "application/dns+cbor;packed=1"
Media-Type: application/dns+cbor;packed=1
Encoding: -
Id: TBD
Reference: [TBD-this-spec]
6. References
6.1. Normative References
[I-D.ietf-cbor-packed]
Bormann, C., "Packed CBOR", Work in Progress, Internet-
Draft, draft-ietf-cbor-packed-08, 23 January 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-cbor-
packed-08>.
[RFC1035] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,
November 1987, <https://www.rfc-editor.org/rfc/rfc1035>.
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[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/rfc/rfc2119>.
[RFC3596] Thomson, S., Huitema, C., Ksinant, V., and M. Souissi,
"DNS Extensions to Support IP Version 6", STD 88,
RFC 3596, DOI 10.17487/RFC3596, October 2003,
<https://www.rfc-editor.org/rfc/rfc3596>.
[RFC5890] Klensin, J., "Internationalized Domain Names for
Applications (IDNA): Definitions and Document Framework",
RFC 5890, DOI 10.17487/RFC5890, August 2010,
<https://www.rfc-editor.org/rfc/rfc5890>.
[RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type
Specifications and Registration Procedures", BCP 13,
RFC 6838, DOI 10.17487/RFC6838, January 2013,
<https://www.rfc-editor.org/rfc/rfc6838>.
[RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained
Application Protocol (CoAP)", RFC 7252,
DOI 10.17487/RFC7252, June 2014,
<https://www.rfc-editor.org/rfc/rfc7252>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.
[RFC8610] Birkholz, H., Vigano, C., and C. Bormann, "Concise Data
Definition Language (CDDL): A Notational Convention to
Express Concise Binary Object Representation (CBOR) and
JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610,
June 2019, <https://www.rfc-editor.org/rfc/rfc8610>.
[RFC8949] Bormann, C. and P. Hoffman, "Concise Binary Object
Representation (CBOR)", STD 94, RFC 8949,
DOI 10.17487/RFC8949, December 2020,
<https://www.rfc-editor.org/rfc/rfc8949>.
6.2. Informative References
[I-D.ietf-core-dns-over-coap]
Lenders, M. S., Amsüss, C., Gündoğan, C., Schmidt, T. C.,
and M. Wählisch, "DNS over CoAP (DoC)", Work in Progress,
Internet-Draft, draft-ietf-core-dns-over-coap-01, 24
October 2022, <https://datatracker.ietf.org/doc/html/
draft-ietf-core-dns-over-coap-01>.
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[RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler,
"Transmission of IPv6 Packets over IEEE 802.15.4
Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007,
<https://www.rfc-editor.org/rfc/rfc4944>.
[RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6
Datagrams over IEEE 802.15.4-Based Networks", RFC 6282,
DOI 10.17487/RFC6282, September 2011,
<https://www.rfc-editor.org/rfc/rfc6282>.
[RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for
Constrained-Node Networks", RFC 7228,
DOI 10.17487/RFC7228, May 2014,
<https://www.rfc-editor.org/rfc/rfc7228>.
[RFC8484] Hoffman, P. and P. McManus, "DNS Queries over HTTPS
(DoH)", RFC 8484, DOI 10.17487/RFC8484, October 2018,
<https://www.rfc-editor.org/rfc/rfc8484>.
[RFC8724] Minaburo, A., Toutain, L., Gomez, C., Barthel, D., and JC.
Zuniga, "SCHC: Generic Framework for Static Context Header
Compression and Fragmentation", RFC 8724,
DOI 10.17487/RFC8724, April 2020,
<https://www.rfc-editor.org/rfc/rfc8724>.
[RFC8824] Minaburo, A., Toutain, L., and R. Andreasen, "Static
Context Header Compression (SCHC) for the Constrained
Application Protocol (CoAP)", RFC 8824,
DOI 10.17487/RFC8824, June 2021,
<https://www.rfc-editor.org/rfc/rfc8824>.
[RFC9110] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "HTTP Semantics", STD 97, RFC 9110,
DOI 10.17487/RFC9110, June 2022,
<https://www.rfc-editor.org/rfc/rfc9110>.
Appendix A. Examples
A.1. DNS Queries
A DNS query of the record AAAA in class IN for name "example.org" is
represented in CBOR extended diagnostic notation (EDN) (see Section 8
in [RFC8949] and Appendix G in [RFC8610]) as follows:
[["example.org"]]
A query of an A record for the same name is represented as
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[["example.org", 1]]
A query of ANY record for that name is represented as
[["example.org", 255, 255]]
A.2. DNS Responses
The responses to the examples provided in Appendix A.1 are shown
below. We use the CBOR extended diagnostic notation (EDN) (see
Section 8 in [RFC8949] and Appendix G in [RFC8610]).
To represent an AAAA record with TTL 300 seconds for the IPv6 address
2001:db8::1, a minimal response to ["example.org"] could be
[[[300, h'20010db8000000000000000000000001']]]
In this case, the name is derived from the query.
If the name or the context is required, the following response would
also be valid:
[[["example.org", 300, h'20010db8000000000000000000000001']]]
If the query can not be mapped to the response for some reason, a
response would look like:
[["example.org"], [[300, h'20010db8000000000000000000000001']]]
To represent a minimal response of an A record with TTL 3600 seconds
for the IPv4 address 192.0.2.1, a minimal response to ["example.org",
1] could be
[[300, h'c0000201']]
Note that here also the 1 of record type A can be elided, as this
record type is specified in the question section.
Lastly, a response to ["example.org", 255, 255] could be
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[
["example.org", 12, 1],
[[3600, "_coap._udp.local"]],
[
[3600, 2, "ns1.example.org"],
[3600, 2, "ns2.example.org"]
],
[
[
"_coap._udp.local", 3600, 28,
h'20010db8000000000000000000000001'
],
[
"_coap._udp.local", 3600, 28,
h'20010db8000000000000000000000002'
],
[
"ns1.example.org", 3600, 28,
h'20010db8000000000000000000000035'
],
[
"ns2.example.org", 3600, 28,
h'20010db8000000000000000000003535'
]
]
]
This one advertises two local CoAP servers (identified by service
name _coap._udp.local) at 2001:db8::1 and 2001:db8::2 and two
nameservers for the example.org domain, ns1.example.org at
2001:db8::35 and ns2.example.org at 2001.db8::3535. Each of the
transmitted records has a TTL of 3600 seconds.
Appendix B. Change Log
B.1. Since [draft-lenders-dns-cbor-01]
* Update definitions to accommodate for TID and flags, as well as
more sections in query
* Clarify fallback to wire-format
B.2. Since draft-lenders-dns-cbor-00
(https://datatracker.ietf.org/doc/html/draft-lenders-dns-cbor-00)
* Add support for DNS transaction IDs
* Name and Address compression utilizing CBOR-packed
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* Minor fixes to CBOR EDN and CDDL
Acknowledgments
TODO acknowledge.
* Carsten Bormann
Authors' Addresses
Martine Sophie Lenders
Freie Universität Berlin
Email: m.lenders@fu-berlin.de
Carsten Bormann
Universität Bremen TZI
Email: cabo@tzi.org
Thomas C. Schmidt
HAW Hamburg
Email: t.schmidt@haw-hamburg.de
Matthias Wählisch
Freie Universität Berlin
Email: m.waehlisch@fu-berlin.de
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