draft-ietf-cbor-cddl-more-control-03.txt		draft-ietf-cbor-cddl-more-control-04.txt
	Network Working Group C. Bormann		Network Working Group C. Bormann
	Internet-Draft Universität Bremen TZI		Internet-Draft Universität Bremen TZI
	Intended status: Standards Track 26 February 2024		Intended status: Standards Track 28 March 2024
	Expires: 29 August 2024		Expires: 29 September 2024
	More Control Operators for CDDL		More Control Operators for CDDL
	draft-ietf-cbor-cddl-more-control-03		draft-ietf-cbor-cddl-more-control-04
	Abstract		Abstract
	The Concise Data Definition Language (CDDL), standardized in RFC		The Concise Data Definition Language (CDDL), standardized in RFC
	8610, provides "control operators" as its main language extension		8610, provides "control operators" as its main language extension
	point. RFCs have added to this extension point both in an		point. RFCs have added to this extension point both in an
	application-specific and a more general way.		application-specific and a more general way.
	The present document defines a number of additional generally		The present document defines a number of additional generally
	applicable control operators for text conversion (Bytes, Integers,		applicable control operators for text conversion (Bytes, Integers,
	JSON, Printf-style formatting), operations on text, and deterministic		JSON, Printf-style formatting) and for an operation on text.
	encoding.
	About This Document		About This Document
	This note is to be removed before publishing as an RFC.		This note is to be removed before publishing as an RFC.
	The latest revision of this draft can be found at https://cbor-		The latest revision of this draft can be found at https://cbor-
	wg.github.io/cddl-more-control/. Status information for this		wg.github.io/cddl-more-control/. Status information for this
	document may be found at https://datatracker.ietf.org/doc/draft-ietf-		document may be found at https://datatracker.ietf.org/doc/draft-ietf-
	cbor-cddl-more-control/.		cbor-cddl-more-control/.
	skipping to change at page 2, line 10 ¶		skipping to change at page 2, line 10 ¶
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute		Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-		working documents as Internet-Drafts. The list of current Internet-
	Drafts is at https://datatracker.ietf.org/drafts/current/.		Drafts is at https://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		Internet-Drafts are draft documents valid for a maximum of six months
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference		time. It is inappropriate to use Internet-Drafts as reference
	material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
	This Internet-Draft will expire on 29 August 2024.		This Internet-Draft will expire on 29 September 2024.
	Copyright Notice		Copyright Notice
	Copyright (c) 2024 IETF Trust and the persons identified as the		Copyright (c) 2024 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents (https://trustee.ietf.org/		Provisions Relating to IETF Documents (https://trustee.ietf.org/
	license-info) in effect on the date of publication of this document.		license-info) in effect on the date of publication of this document.
	Please review these documents carefully, as they describe your rights		Please review these documents carefully, as they describe your rights
	and restrictions with respect to this document. Code Components		and restrictions with respect to this document. Code Components
	extracted from this document must include Revised BSD License text as		extracted from this document must include Revised BSD License text as
	described in Section 4.e of the Trust Legal Provisions and are		described in Section 4.e of the Trust Legal Provisions and are
	provided without warranty as described in the Revised BSD License.		provided without warranty as described in the Revised BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
	1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4		1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
	2. Text Conversion . . . . . . . . . . . . . . . . . . . . . . . 4		2. Text Conversion . . . . . . . . . . . . . . . . . . . . . . . 4
	2.1. Byte Strings: Base16 (Hex), Base32, Base45, Base64 . . . 4		2.1. Byte Strings: Base16 (Hex), Base32, Base45, Base64 . . . 4
	2.2. Numbers . . . . . . . . . . . . . . . . . . . . . . . . . 6		2.2. Numbers . . . . . . . . . . . . . . . . . . . . . . . . . 6
	2.3. Printf-style Formatting . . . . . . . . . . . . . . . . . 6		2.3. Printf-style Formatting . . . . . . . . . . . . . . . . . 6
	2.4. JSON Values . . . . . . . . . . . . . . . . . . . . . . . 7		2.4. JSON Values . . . . . . . . . . . . . . . . . . . . . . . 7
	3. Text Processing . . . . . . . . . . . . . . . . . . . . . . . 8		3. Text Processing . . . . . . . . . . . . . . . . . . . . . . . 8
	3.1. Join . . . . . . . . . . . . . . . . . . . . . . . . . . 8		3.1. Join . . . . . . . . . . . . . . . . . . . . . . . . . . 8
	4. Deterministic Encoding . . . . . . . . . . . . . . . . . . . 8		4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
	5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9		5. Implementation Status . . . . . . . . . . . . . . . . . . . . 9
	6. Implementation Status . . . . . . . . . . . . . . . . . . . . 10		6. Security considerations . . . . . . . . . . . . . . . . . . . 9
	7. Security considerations . . . . . . . . . . . . . . . . . . . 11		7. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
	8. References . . . . . . . . . . . . . . . . . . . . . . . . . 11		7.1. Normative References . . . . . . . . . . . . . . . . . . 10
	8.1. Normative References . . . . . . . . . . . . . . . . . . 11		7.2. Informative References . . . . . . . . . . . . . . . . . 11
	8.2. Informative References . . . . . . . . . . . . . . . . . 12		Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 11
	Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 12		Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 12
	Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 13
	1. Introduction		1. Introduction
	The Concise Data Definition Language (CDDL), standardized in		The Concise Data Definition Language (CDDL), standardized in
	[RFC8610], provides "control operators" as its main language		[RFC8610], provides "control operators" as its main language
	extension point (Section 3.8 of [RFC8610]). RFCs have added to this		extension point (Section 3.8 of [RFC8610]). RFCs have added to this
	extension point both in an application-specific [RFC9090] and a more		extension point both in an application-specific [RFC9090] and a more
	general [RFC9165] way.		general [RFC9165] way.
	The present document defines a number of additional generally		The present document defines a number of additional generally
	skipping to change at page 3, line 42 ¶		skipping to change at page 3, line 34 ¶
	| | numbers |		| | numbers |
	+---------------+---------------------------------------+		+---------------+---------------------------------------+
	| .printf | Printf-formatted text representation |		| .printf | Printf-formatted text representation |
	| | of data items |		| | of data items |
	+---------------+---------------------------------------+		+---------------+---------------------------------------+
	| .json | Text representation of JSON values |		| .json | Text representation of JSON values |
	+---------------+---------------------------------------+		+---------------+---------------------------------------+
	| .join | Building text from array of |		| .join | Building text from array of |
	| | components |		| | components |
	+---------------+---------------------------------------+		+---------------+---------------------------------------+
	| .cbordet, | deterministically encoded CBOR data |
	| .cborseqdet | items, CBOR sequences |
	+---------------+---------------------------------------+
	Table 1: New control operators in this document		Table 1: New control operators in this document
	1.1. Terminology		1.1. Terminology
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and		"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
	"OPTIONAL" in this document are to be interpreted as described in		"OPTIONAL" in this document are to be interpreted as described in
	BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all		BCP 14 [BCP14] when, and only when, they appear in all capitals, as
	capitals, as shown here.		shown here.
	Regular expressions mentioned in the text are as defined in		Regular expressions mentioned in the text are as defined in
	[RFC9485].		[RFC9485].
	This specification uses terminology from [RFC8610]. In particular,		This specification uses terminology from [RFC8610]. In particular,
	with respect to control operators, "target" refers to the left-hand		with respect to control operators, "target" refers to the left-hand
	side operand, and "controller" to the right-hand side operand.		side operand, and "controller" to the right-hand side operand.
	"Tool" refers to tools along the lines of that described in		"Tool" refers to tools along the lines of that described in
	Appendix F of [RFC8610]. Note also that the data model underlying		Appendix F of [RFC8610]. Note also that the data model underlying
	CDDL provides for text strings as well as byte strings as two		CDDL provides for text strings as well as byte strings as two
	skipping to change at page 6, line 5 ¶		skipping to change at page 6, line 5 ¶
	The additional designation "sloppy" indicates that the text string is		The additional designation "sloppy" indicates that the text string is
	not validated for any additional bits being zero, in variance to what		not validated for any additional bits being zero, in variance to what
	is specified in the paragraph behind table 1 in Section 4 of		is specified in the paragraph behind table 1 in Section 4 of
	[RFC4648]. Note that the present specification is opinionated again		[RFC4648]. Note that the present specification is opinionated again
	in not specifying a sloppy variant of base32 or base32/hex, as no		in not specifying a sloppy variant of base32 or base32/hex, as no
	legacy use of sloppy base32(/hex) was known at the time of writing.		legacy use of sloppy base32(/hex) was known at the time of writing.
	Base45 is known to be suboptimal for use in environments with limited		Base45 is known to be suboptimal for use in environments with limited
	data transparency (such as URLs), but is included because of its		data transparency (such as URLs), but is included because of its
	close relationship to QR codes and its wide use in health informatics		close relationship to QR codes and its wide use in health informatics
	(note that base45 is at least strongly specified not to allow sloppy		(note that base45 is strongly specified not to allow sloppy forms of
	forms of encoding).		encoding).
	2.2. Numbers		2.2. Numbers
	+==========+=================+===========+		+==========+=================+===========+
	| name | meaning | reference |		| name | meaning | reference |
	+==========+=================+===========+		+==========+=================+===========+
	| .decimal | Decimal Integer | --- |		| .decimal | Decimal Integer | --- |
	+----------+-----------------+-----------+		+----------+-----------------+-----------+
	Table 3: Control Operator for Text		Table 3: Control Operator for Text
	skipping to change at page 8, line 4 ¶		skipping to change at page 8, line 4 ¶
	+=======+=========+===========+		+=======+=========+===========+
	| .json | JSON | [STD90] |		| .json | JSON | [STD90] |
	+-------+---------+-----------+		+-------+---------+-----------+
	Table 5: Control Operator		Table 5: Control Operator
	for Text Conversion of JSON		for Text Conversion of JSON
	values		values
	embedded-claims = text .json claims		embedded-claims = text .json claims
	claims = {iss: text, exp: text}		claims = {iss: text, exp: text}
	Note that a .jsonseq is not provided, as no use case is known yet.		Note that a .jsonseq is not provided for [RFC7464], as no use case
			for inclusion in CDDL is known yet.
	There is no way to constrain the use of blank space in data items to		There is no way to constrain the use of blank space in data items to
	be validated; variants (e.g, not providing for any blank space) could		be validated; variants (e.g, not providing for any blank space) could
	be defined.		be defined.
	3. Text Processing		3. Text Processing
	3.1. Join		3.1. Join
	Often, text strings need to be constructed out of parts that can best		Often, text strings need to be constructed out of parts that can best
	be modeled as an array.		be modeled as an array.
	skipping to change at page 8, line 35 ¶		skipping to change at page 8, line 37 ¶
	In general, this control operator is hard to validate as it would		In general, this control operator is hard to validate as it would
	require full parser functionality. It is therefore recommended to		require full parser functionality. It is therefore recommended to
	only use it in simple cases, and leave full parsing to ABNF (see		only use it in simple cases, and leave full parsing to ABNF (see
	Section 3 of [RFC9165]) or similar.		Section 3 of [RFC9165]) or similar.
	legacy-ip-address = text .join [bytetext, ".", bytetext,		legacy-ip-address = text .join [bytetext, ".", bytetext,
	".", bytetext, ".", bytetext]		".", bytetext, ".", bytetext]
	bytetext = text .decimal byte		bytetext = text .decimal byte
	byte = 0..255		byte = 0..255
	4. Deterministic Encoding		4. IANA Considerations
	[RFC8610] and [RFC8742] specify the control operators .cbor and
	.cborseq to indicate that the value of a byte string should be an
	encoded CBOR data item or a CBOR sequence.
	This specification provides complementary control operators .cbordet
	and .cborseqdet that indicate that these data items/sequences need to
	be encoded in accordance to Sections 4.2.1 and 4.2.2 of RFC 8949
	[STD94].
	+=============+=========================+===========+
	| name | meaning | reference |
	+=============+=========================+===========+
	| .cbordet | deterministically | [RFC8610] |
	| | encoded CBOR data item | |
	+-------------+-------------------------+-----------+
	| .cborseqdet | CBOR sequence made from | [RFC8742] |
	| | deterministically | |
	| | encoded CBOR data items | |
	+-------------+-------------------------+-----------+
	Table 7: Control Operator for Deterministically
	Encoded Data Items and Sequences
	Note that considerations of deterministic representation at the
	application level can often be expressed in the CDDL definition of
	the right-hand side and then do not need additional control
	operators.
	5. IANA Considerations
	// RFC Editor: please replace RFC-XXXX with the RFC number of this		// RFC Editor: please replace RFC-XXXX with the RFC number of this
	// RFC and remove this note.		// RFC and remove this note.
	This document requests IANA to register the contents of Table 8 into		This document requests IANA to register the contents of Table 7 into
	the registry "CDDL Control Operators" of [IANA.cddl]:		the registry "CDDL Control Operators" of [IANA.cddl]:
	+==============+============+		+==============+============+
	| Name | Reference |		| Name | Reference |
	+==============+============+		+==============+============+
	| .b64u | [RFC-XXXX] |		| .b64u | [RFC-XXXX] |
	+--------------+------------+		+--------------+------------+
	| .b64u-sloppy | [RFC-XXXX] |		| .b64u-sloppy | [RFC-XXXX] |
	+--------------+------------+		+--------------+------------+
	| .b64c | [RFC-XXXX] |		| .b64c | [RFC-XXXX] |
	skipping to change at page 10, line 36 ¶		skipping to change at page 9, line 36 ¶
	| .hexuc | [RFC-XXXX] |		| .hexuc | [RFC-XXXX] |
	+--------------+------------+		+--------------+------------+
	| .decimal | [RFC-XXXX] |		| .decimal | [RFC-XXXX] |
	+--------------+------------+		+--------------+------------+
	| .printf | [RFC-XXXX] |		| .printf | [RFC-XXXX] |
	+--------------+------------+		+--------------+------------+
	| .json | [RFC-XXXX] |		| .json | [RFC-XXXX] |
	+--------------+------------+		+--------------+------------+
	| .join | [RFC-XXXX] |		| .join | [RFC-XXXX] |
	+--------------+------------+		+--------------+------------+
	| .cbordet | [RFC-XXXX] |
	+--------------+------------+
	| .cborseqdet | [RFC-XXXX] |
	+--------------+------------+
	Table 8: New control		Table 7: New control
	operators to be		operators to be
	registered		registered
	6. Implementation Status		5. Implementation Status
	This section is to be removed before publishing as an RFC.		This section is to be removed before publishing as an RFC.
	In the CDDL tool described in Appendix F of [RFC8610], the control		In the CDDL tool described in Appendix F of [RFC8610], the control
	operators defined in the present revision of this specification are		operators defined in the present revision of this specification are
	implemented as of version 0.10.4.		implemented as of version 0.10.4.
	7. Security considerations		6. Security considerations
	The security considerations of [RFC8610] apply.		The security considerations of [RFC8610] apply.
	8. References		7. References
	8.1. Normative References		7.1. Normative References
			[BCP14] Best Current Practice 14,
			<https://www.rfc-editor.org/info/bcp14>.
			At the time of writing, this BCP comprises the following:
			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/info/rfc2119>.
			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/info/rfc8174>.
	[C] International Organization for Standardization,		[C] International Organization for Standardization,
	"Information technology — Programming languages — C",		"Information technology — Programming languages — C",
	Fourth Edition, ISO/IEC 9899:2018, June 2018,		Fourth Edition, ISO/IEC 9899:2018, June 2018,
	<https://www.iso.org/standard/74528.html>. Technically		<https://www.iso.org/standard/74528.html>. Technically
	equivalent specification text is available at		equivalent specification text is available at
	https://web.archive.org/web/20181230041359if_/		https://web.archive.org/web/20181230041359if_/
	http://www.open- std.org/jtc1/sc22/wg14/www/abq/		http://www.open- std.org/jtc1/sc22/wg14/www/abq/
	c17_updated_proposed_fdis.pdf		c17_updated_proposed_fdis.pdf
	(https://web.archive.org/web/20181230041359if_/		(https://web.archive.org/web/20181230041359if_/
	http://www.open- std.org/jtc1/sc22/wg14/www/abq/		http://www.open- std.org/jtc1/sc22/wg14/www/abq/
	c17_updated_proposed_fdis.pdf)		c17_updated_proposed_fdis.pdf)
	[IANA.cddl]		[IANA.cddl]
	IANA, "Concise Data Definition Language (CDDL)",		IANA, "Concise Data Definition Language (CDDL)",
	<https://www.iana.org/assignments/cddl>.		<https://www.iana.org/assignments/cddl>.
	[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>.
	[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data		[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
	Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,		Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,
	<https://www.rfc-editor.org/rfc/rfc4648>.		<https://www.rfc-editor.org/rfc/rfc4648>.
	[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		[RFC8610] Birkholz, H., Vigano, C., and C. Bormann, "Concise Data
	Definition Language (CDDL): A Notational Convention to		Definition Language (CDDL): A Notational Convention to
	Express Concise Binary Object Representation (CBOR) and		Express Concise Binary Object Representation (CBOR) and
	JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610,		JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610,
	June 2019, <https://www.rfc-editor.org/rfc/rfc8610>.		June 2019, <https://www.rfc-editor.org/rfc/rfc8610>.
	[RFC8742] Bormann, C., "Concise Binary Object Representation (CBOR)
	Sequences", RFC 8742, DOI 10.17487/RFC8742, February 2020,
	<https://www.rfc-editor.org/rfc/rfc8742>.
	[RFC9165] Bormann, C., "Additional Control Operators for the Concise		[RFC9165] Bormann, C., "Additional Control Operators for the Concise
	Data Definition Language (CDDL)", RFC 9165,		Data Definition Language (CDDL)", RFC 9165,
	DOI 10.17487/RFC9165, December 2021,		DOI 10.17487/RFC9165, December 2021,
	<https://www.rfc-editor.org/rfc/rfc9165>.		<https://www.rfc-editor.org/rfc/rfc9165>.
	[RFC9285] Fältström, P., Ljunggren, F., and D.W. van Gulik, "The		[RFC9285] Fältström, P., Ljunggren, F., and D.W. van Gulik, "The
	Base45 Data Encoding", RFC 9285, DOI 10.17487/RFC9285,		Base45 Data Encoding", RFC 9285, DOI 10.17487/RFC9285,
	August 2022, <https://www.rfc-editor.org/rfc/rfc9285>.		August 2022, <https://www.rfc-editor.org/rfc/rfc9285>.
	[RFC9485] Bormann, C. and T. Bray, "I-Regexp: An Interoperable		[RFC9485] Bormann, C. and T. Bray, "I-Regexp: An Interoperable
	skipping to change at page 12, line 37 ¶		skipping to change at page 11, line 32 ¶
	[STD94] Internet Standard 94,		[STD94] Internet Standard 94,
	<https://www.rfc-editor.org/info/std94>.		<https://www.rfc-editor.org/info/std94>.
	At the time of writing, this STD comprises the following:		At the time of writing, this STD comprises the following:
	Bormann, C. and P. Hoffman, "Concise Binary Object		Bormann, C. and P. Hoffman, "Concise Binary Object
	Representation (CBOR)", STD 94, RFC 8949,		Representation (CBOR)", STD 94, RFC 8949,
	DOI 10.17487/RFC8949, December 2020,		DOI 10.17487/RFC8949, December 2020,
	<https://www.rfc-editor.org/info/rfc8949>.		<https://www.rfc-editor.org/info/rfc8949>.
	8.2. Informative References		7.2. Informative References
			[RFC7464] Williams, N., "JavaScript Object Notation (JSON) Text
			Sequences", RFC 7464, DOI 10.17487/RFC7464, February 2015,
			<https://www.rfc-editor.org/rfc/rfc7464>.
	[RFC7951] Lhotka, L., "JSON Encoding of Data Modeled with YANG",		[RFC7951] Lhotka, L., "JSON Encoding of Data Modeled with YANG",
	RFC 7951, DOI 10.17487/RFC7951, August 2016,		RFC 7951, DOI 10.17487/RFC7951, August 2016,
	<https://www.rfc-editor.org/rfc/rfc7951>.		<https://www.rfc-editor.org/rfc/rfc7951>.
	[RFC9090] Bormann, C., "Concise Binary Object Representation (CBOR)		[RFC9090] Bormann, C., "Concise Binary Object Representation (CBOR)
	Tags for Object Identifiers", RFC 9090,		Tags for Object Identifiers", RFC 9090,
	DOI 10.17487/RFC9090, July 2021,		DOI 10.17487/RFC9090, July 2021,
	<https://www.rfc-editor.org/rfc/rfc9090>.		<https://www.rfc-editor.org/rfc/rfc9090>.
End of changes. 22 change blocks.
	80 lines changed or deleted		47 lines changed or added
This html diff was produced by rfcdiff 1.45. The latest version is available from http://tools.ietf.org/tools/rfcdiff/