draft-ietf-dnssd-srp-09.txt		draft-ietf-dnssd-srp-10.txt
	Internet Engineering Task Force T. Lemon		Internet Engineering Task Force T. Lemon
	Internet-Draft S. Cheshire		Internet-Draft S. Cheshire
	Intended status: Standards Track Apple Inc.		Intended status: Standards Track Apple Inc.
	Expires: 15 July 2021 11 January 2021		Expires: 13 January 2022 12 July 2021
	Service Registration Protocol for DNS-Based Service Discovery		Service Registration Protocol for DNS-Based Service Discovery
	draft-ietf-dnssd-srp-09		draft-ietf-dnssd-srp-10
	Abstract		Abstract
	The Service Registration Protocol for DNS-Based Service Discovery		The Service Registration Protocol for DNS-Based Service Discovery
	uses the standard DNS Update mechanism to enable DNS-Based Service		uses the standard DNS Update mechanism to enable DNS-Based Service
	Discovery using only unicast packets. This makes it possible to		Discovery using only unicast packets. This makes it possible to
	deploy DNS Service Discovery without multicast, which greatly		deploy DNS Service Discovery without multicast, which greatly
	improves scalability and improves performance on networks where		improves scalability and improves performance on networks where
	multicast service is not an optimal choice, particularly 802.11		multicast service is not an optimal choice, particularly 802.11
	(Wi-Fi) and 802.15.4 (IoT) networks. DNS-SD Service registration		(Wi-Fi) and 802.15.4 (IoT) networks. DNS-SD Service registration
	skipping to change at page 1, line 38 ¶		skipping to change at page 1, line 38 ¶
	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 15 July 2021.		This Internet-Draft will expire on 13 January 2022.
	Copyright Notice		Copyright Notice
	Copyright (c) 2021 IETF Trust and the persons identified as the		Copyright (c) 2021 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
	skipping to change at page 6, line 39 ¶		skipping to change at page 6, line 39 ¶
	that typically use Constrained-Node Networks may have very limited		that typically use Constrained-Node Networks may have very limited
	battery power. The series of DNS lookups required to discover an SRP		battery power. The series of DNS lookups required to discover an SRP
	server and then communicate with it will increase the power required		server and then communicate with it will increase the power required
	to advertise a service; for low-power devices, the additional		to advertise a service; for low-power devices, the additional
	flexibility this provides does not justify the additional use of		flexibility this provides does not justify the additional use of
	power. It is also fairly typical of such networks that some network		power. It is also fairly typical of such networks that some network
	service information is obtained as part of the process of joining the		service information is obtained as part of the process of joining the
	network, and so this can be relied upon to provide nodes with the		network, and so this can be relied upon to provide nodes with the
	information they need.		information they need.
	Networks that are not constrained networks can more complicated		Networks that are not constrained networks can have more complicated
	topologies at the Internet layer. Nodes connected to such networks		topologies at the Internet layer. Nodes connected to such networks
	can be assumed to be able to do DNSSD service registration domain		can be assumed to be able to do DNSSD service registration domain
	discovery. Such networks are generally able to provide registration		discovery. Such networks are generally able to provide registration
	domain discovery and routing. By requiring the use of TCP, the		domain discovery and routing. By requiring the use of TCP, the
	possibility of off-network spoofing is eliminated.		possibility of off-network spoofing is eliminated.
	2.2. Protocol Details		2.2. Protocol Details
	We will discuss several parts to this process: how to know what to		We will discuss several parts to this process: how to know what to
	publish, how to know where to publish it (under what name), how to		publish, how to know where to publish it (under what name), how to
	skipping to change at page 14, line 38 ¶		skipping to change at page 14, line 38 ¶
	sign the message,		sign the message,
	* there is a Service Instance Name Instruction in the SRP update for		* there is a Service Instance Name Instruction in the SRP update for
	which the SRV RR that is added points to the hostname being		which the SRV RR that is added points to the hostname being
	updated by this update.		updated by this update.
	* Host Description updates do not modify any other records.		* Host Description updates do not modify any other records.
	2.3.2. Valid SRP Update Requirements		2.3.2. Valid SRP Update Requirements
	An SRP Update MUST include zero or more Service Discovery		An SRP Update MUST include zero or more Service Discovery
	instructions. For each Service Discovery instruction, there MUST be		instructions. For each Service Discovery instruction, there MUST be
	at least one Service Description instruction. For each Service		at least one Service Description instruction. Note that in the case
	Description instruction there MUST be at least one Service Discovery		of SRP subtypes Section 7.1 of [RFC6763], it's quite possible that
	instruction with its service instance name as the target of its PTR		two Service Discovery instructions might reference the same Service
	record. There MUST be exactly one Host Description Instruction.		Description instruction. For each Service Description instruction
	Every Service Description instruction must have that Host Description		there MUST be at least one Service Discovery instruction with its
	instruction as the target of its SRV record. A DNS Update that does		service instance name as the target of its PTR record. There MUST be
	not meet these constraints is not an SRP update.		exactly one Host Description Instruction. Every Service Description
			instruction must have that Host Description instruction as the target
			of its SRV record. A DNS Update that does not meet these constraints
			is not an SRP update.
	A DNS Update that contains any additional adds or deletes that cannot		A DNS Update that contains any additional adds or deletes that cannot
	be identified as Service Discovery, Service Description or Host		be identified as Service Discovery, Service Description or Host
	Description instructions is not an SRP update. A DNS update that		Description instructions is not an SRP update. A DNS update that
	contains any prerequisites is not an SRP update. Such messages		contains any prerequisites is not an SRP update. Such messages
	should either be processed as regular RFC2136 updates, including		should either be processed as regular RFC2136 updates, including
	access control checks and constraint checks, if supported, or else		access control checks and constraint checks, if supported, or else
	rejected with RCODE=REFUSED.		rejected with RCODE=REFUSED.
	In addition, in order for an update to be a valid SRP update, the		In addition, in order for an update to be a valid SRP update, the
	skipping to change at page 24, line 46 ¶		skipping to change at page 24, line 46 ¶
	doing a nice developmental edit, Tim Wattenberg for doing a SRP		doing a nice developmental edit, Tim Wattenberg for doing a SRP
	client proof-of-concept implementation at the Montreal Hackathon at		client proof-of-concept implementation at the Montreal Hackathon at
	IETF 102, and Tom Pusateri for reviewing during the hackathon and		IETF 102, and Tom Pusateri for reviewing during the hackathon and
	afterwards.		afterwards.
	12. Normative References		12. Normative References
	[I-D.sekar-dns-ul]		[I-D.sekar-dns-ul]
	Cheshire, S. and T. Lemon, "Dynamic DNS Update Leases",		Cheshire, S. and T. Lemon, "Dynamic DNS Update Leases",
	Work in Progress, Internet-Draft, draft-sekar-dns-ul-02, 2		Work in Progress, Internet-Draft, draft-sekar-dns-ul-02, 2
	August 2018,		August 2018, <https://datatracker.ietf.org/doc/html/draft-
	<https://tools.ietf.org/html/draft-sekar-dns-ul-02>.		sekar-dns-ul-02>.
	[RFC2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor		[RFC2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
	Extensions", RFC 2132, DOI 10.17487/RFC2132, March 1997,		Extensions", RFC 2132, DOI 10.17487/RFC2132, March 1997,
	<https://www.rfc-editor.org/info/rfc2132>.		<https://www.rfc-editor.org/info/rfc2132>.
	[RFC2136] Vixie, P., Ed., Thomson, S., Rekhter, Y., and J. Bound,		[RFC2136] Vixie, P., Ed., Thomson, S., Rekhter, Y., and J. Bound,
	"Dynamic Updates in the Domain Name System (DNS UPDATE)",		"Dynamic Updates in the Domain Name System (DNS UPDATE)",
	RFC 2136, DOI 10.17487/RFC2136, April 1997,		RFC 2136, DOI 10.17487/RFC2136, April 1997,
	<https://www.rfc-editor.org/info/rfc2136>.		<https://www.rfc-editor.org/info/rfc2136>.
	skipping to change at page 27, line 18 ¶		skipping to change at page 27, line 18 ¶
	RFC 8415, DOI 10.17487/RFC8415, November 2018,		RFC 8415, DOI 10.17487/RFC8415, November 2018,
	<https://www.rfc-editor.org/info/rfc8415>.		<https://www.rfc-editor.org/info/rfc8415>.
	[RFC8766] Cheshire, S., "Discovery Proxy for Multicast DNS-Based		[RFC8766] Cheshire, S., "Discovery Proxy for Multicast DNS-Based
	Service Discovery", RFC 8766, DOI 10.17487/RFC8766, June		Service Discovery", RFC 8766, DOI 10.17487/RFC8766, June
	2020, <https://www.rfc-editor.org/info/rfc8766>.		2020, <https://www.rfc-editor.org/info/rfc8766>.
	[I-D.cheshire-dnssd-roadmap]		[I-D.cheshire-dnssd-roadmap]
	Cheshire, S., "Service Discovery Road Map", Work in		Cheshire, S., "Service Discovery Road Map", Work in
	Progress, Internet-Draft, draft-cheshire-dnssd-roadmap-03,		Progress, Internet-Draft, draft-cheshire-dnssd-roadmap-03,
	23 October 2018, <https://tools.ietf.org/html/draft-		23 October 2018, <https://datatracker.ietf.org/doc/html/
	cheshire-dnssd-roadmap-03>.		draft-cheshire-dnssd-roadmap-03>.
	[I-D.cheshire-edns0-owner-option]		[I-D.cheshire-edns0-owner-option]
	Cheshire, S. and M. Krochmal, "EDNS0 OWNER Option", Work		Cheshire, S. and M. Krochmal, "EDNS0 OWNER Option", Work
	in Progress, Internet-Draft, draft-cheshire-edns0-owner-		in Progress, Internet-Draft, draft-cheshire-edns0-owner-
	option-01, 3 July 2017, <https://tools.ietf.org/html/		option-01, 3 July 2017,
	draft-cheshire-edns0-owner-option-01>.		<https://datatracker.ietf.org/doc/html/draft-cheshire-
			edns0-owner-option-01>.
	[I-D.sctl-advertising-proxy]		[I-D.sctl-advertising-proxy]
	Cheshire, S. and T. Lemon, "Advertising Proxy for DNS-SD		Cheshire, S. and T. Lemon, "Advertising Proxy for DNS-SD
	Service Registration Protocol", Work in Progress,		Service Registration Protocol", Work in Progress,
	Internet-Draft, draft-sctl-advertising-proxy-00, 13 July		Internet-Draft, draft-sctl-advertising-proxy-01, 22
	2020, <https://tools.ietf.org/html/draft-sctl-advertising-		February 2021, <https://datatracker.ietf.org/doc/html/
	proxy-00>.		draft-sctl-advertising-proxy-01>.
	[ZC] Cheshire, S. and D.H. Steinberg, "Zero Configuration		[ZC] Cheshire, S. and D.H. Steinberg, "Zero Configuration
	Networking: The Definitive Guide", O'Reilly Media, Inc. ,		Networking: The Definitive Guide", O'Reilly Media, Inc. ,
	ISBN 0-596-10100-7, December 2005.		ISBN 0-596-10100-7, December 2005.
	Appendix A. Testing using standard RFC2136-compliant servers		Appendix A. Testing using standard RFC2136-compliant servers
	It may be useful to set up a DNS server for testing that does not		It may be useful to set up a DNS server for testing that does not
	implement SRP. This can be done by configuring the server to listen		implement SRP. This can be done by configuring the server to listen
	on the anycast address, or advertising it in the		on the anycast address, or advertising it in the
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