< draft-ietf-httpbis-proxy-status-05.txt		draft-ietf-httpbis-proxy-status-06.txt >
	HTTP M. Nottingham		HTTP M. Nottingham
	Internet-Draft Fastly		Internet-Draft Fastly
	Intended status: Standards Track P. Sikora		Intended status: Standards Track P. Sikora
	Expires: 29 October 2021 Google		Expires: 17 February 2022 Google
	27 April 2021		16 August 2021
	The Proxy-Status HTTP Response Header Field		The Proxy-Status HTTP Response Header Field
	draft-ietf-httpbis-proxy-status-05		draft-ietf-httpbis-proxy-status-06
	Abstract		Abstract
	This document defines the Proxy-Status HTTP field to convey the		This document defines the Proxy-Status HTTP field to convey the
	details of intermediary response handling, including generated		details of intermediary response handling, including generated
	errors.		errors.
	Note to Readers		Note to Readers
	_RFC EDITOR: please remove this section before publication_		_RFC EDITOR: please remove this section before publication_
	skipping to change at page 1, line 48 ¶		skipping to change at page 1, line 48 ¶
	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 October 2021.		This Internet-Draft will expire on 17 February 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 2, line 33 ¶		skipping to change at page 2, line 33 ¶
	2. The Proxy-Status HTTP Field . . . . . . . . . . . . . . . . . 4		2. The Proxy-Status HTTP Field . . . . . . . . . . . . . . . . . 4
	2.1. Proxy-Status Parameters . . . . . . . . . . . . . . . . . 5		2.1. Proxy-Status Parameters . . . . . . . . . . . . . . . . . 5
	2.1.1. error . . . . . . . . . . . . . . . . . . . . . . . . 5		2.1.1. error . . . . . . . . . . . . . . . . . . . . . . . . 5
	2.1.2. next-hop . . . . . . . . . . . . . . . . . . . . . . 6		2.1.2. next-hop . . . . . . . . . . . . . . . . . . . . . . 6
	2.1.3. next-protocol . . . . . . . . . . . . . . . . . . . . 7		2.1.3. next-protocol . . . . . . . . . . . . . . . . . . . . 7
	2.1.4. received-status . . . . . . . . . . . . . . . . . . . 7		2.1.4. received-status . . . . . . . . . . . . . . . . . . . 7
	2.1.5. details . . . . . . . . . . . . . . . . . . . . . . . 7		2.1.5. details . . . . . . . . . . . . . . . . . . . . . . . 7
	2.2. Defining New Proxy-Status Parameters . . . . . . . . . . 7		2.2. Defining New Proxy-Status Parameters . . . . . . . . . . 7
	2.3. Proxy Error Types . . . . . . . . . . . . . . . . . . . . 8		2.3. Proxy Error Types . . . . . . . . . . . . . . . . . . . . 8
	2.3.1. DNS Timeout . . . . . . . . . . . . . . . . . . . . . 8		2.3.1. DNS Timeout . . . . . . . . . . . . . . . . . . . . . 8
	2.3.2. DNS Error . . . . . . . . . . . . . . . . . . . . . . 8		2.3.2. DNS Error . . . . . . . . . . . . . . . . . . . . . . 9
	2.3.3. Destination Not Found . . . . . . . . . . . . . . . . 9		2.3.3. Destination Not Found . . . . . . . . . . . . . . . . 9
	2.3.4. Destination Unavailable . . . . . . . . . . . . . . . 9		2.3.4. Destination Unavailable . . . . . . . . . . . . . . . 9
	2.3.5. Destination IP Prohibited . . . . . . . . . . . . . . 9		2.3.5. Destination IP Prohibited . . . . . . . . . . . . . . 10
	2.3.6. Destination IP Unroutable . . . . . . . . . . . . . . 10		2.3.6. Destination IP Unroutable . . . . . . . . . . . . . . 10
	2.3.7. Connection Refused . . . . . . . . . . . . . . . . . 10		2.3.7. Connection Refused . . . . . . . . . . . . . . . . . 10
	2.3.8. Connection Terminated . . . . . . . . . . . . . . . . 10		2.3.8. Connection Terminated . . . . . . . . . . . . . . . . 11
	2.3.9. Connection Timeout . . . . . . . . . . . . . . . . . 10		2.3.9. Connection Timeout . . . . . . . . . . . . . . . . . 11
	2.3.10. Connection Read Timeout . . . . . . . . . . . . . . . 11		2.3.10. Connection Read Timeout . . . . . . . . . . . . . . . 11
	2.3.11. Connection Write Timeout . . . . . . . . . . . . . . 11		2.3.11. Connection Write Timeout . . . . . . . . . . . . . . 11
	2.3.12. Connection Limit Reached . . . . . . . . . . . . . . 11		2.3.12. Connection Limit Reached . . . . . . . . . . . . . . 12
	2.3.13. TLS Protocol Error . . . . . . . . . . . . . . . . . 11		2.3.13. TLS Protocol Error . . . . . . . . . . . . . . . . . 12
	2.3.14. TLS Certificate Error . . . . . . . . . . . . . . . . 12		2.3.14. TLS Certificate Error . . . . . . . . . . . . . . . . 13
	2.3.15. TLS Alert Received . . . . . . . . . . . . . . . . . 12		2.3.15. TLS Alert Received . . . . . . . . . . . . . . . . . 13
	2.3.16. HTTP Request Error . . . . . . . . . . . . . . . . . 13		2.3.16. HTTP Request Error . . . . . . . . . . . . . . . . . 13
	2.3.17. HTTP Request Denied . . . . . . . . . . . . . . . . . 13		2.3.17. HTTP Request Denied . . . . . . . . . . . . . . . . . 14
	2.3.18. HTTP Incomplete Response . . . . . . . . . . . . . . 13		2.3.18. HTTP Incomplete Response . . . . . . . . . . . . . . 14
	2.3.19. HTTP Response Header Section Too Large . . . . . . . 14		2.3.19. HTTP Response Header Section Too Large . . . . . . . 15
	2.3.20. HTTP Response Header Too Large . . . . . . . . . . . 14		2.3.20. HTTP Response Header Too Large . . . . . . . . . . . 15
	2.3.21. HTTP Response Body Too Large . . . . . . . . . . . . 14		2.3.21. HTTP Response Body Too Large . . . . . . . . . . . . 15
	2.3.22. HTTP Response Trailer Section Too Large . . . . . . . 15		2.3.22. HTTP Response Trailer Section Too Large . . . . . . . 16
	2.3.23. HTTP Response Trailer Too Large . . . . . . . . . . . 15		2.3.23. HTTP Response Trailer Too Large . . . . . . . . . . . 16
	2.3.24. HTTP Response Transfer-Coding Error . . . . . . . . . 16		2.3.24. HTTP Response Transfer-Coding Error . . . . . . . . . 17
	2.3.25. HTTP Response Content-Coding Error . . . . . . . . . 16		2.3.25. HTTP Response Content-Coding Error . . . . . . . . . 17
	2.3.26. HTTP Response Timeout . . . . . . . . . . . . . . . . 16		2.3.26. HTTP Response Timeout . . . . . . . . . . . . . . . . 18
	2.3.27. HTTP Upgrade Failed . . . . . . . . . . . . . . . . . 17		2.3.27. HTTP Upgrade Failed . . . . . . . . . . . . . . . . . 18
	2.3.28. HTTP Protocol Error . . . . . . . . . . . . . . . . . 17		2.3.28. HTTP Protocol Error . . . . . . . . . . . . . . . . . 18
	2.3.29. Proxy Internal Response . . . . . . . . . . . . . . . 17		2.3.29. Proxy Internal Response . . . . . . . . . . . . . . . 19
	2.3.30. Proxy Internal Error . . . . . . . . . . . . . . . . 17		2.3.30. Proxy Internal Error . . . . . . . . . . . . . . . . 19
	2.3.31. Proxy Configuration Error . . . . . . . . . . . . . . 18		2.3.31. Proxy Configuration Error . . . . . . . . . . . . . . 19
	2.3.32. Proxy Loop Detected . . . . . . . . . . . . . . . . . 18		2.3.32. Proxy Loop Detected . . . . . . . . . . . . . . . . . 20
	2.4. Defining New Proxy Error Types . . . . . . . . . . . . . 18		2.4. Defining New Proxy Error Types . . . . . . . . . . . . . 20
	3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19		3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21
	4. Security Considerations . . . . . . . . . . . . . . . . . . . 19		4. Security Considerations . . . . . . . . . . . . . . . . . . . 21
	5. References . . . . . . . . . . . . . . . . . . . . . . . . . 20		5. References . . . . . . . . . . . . . . . . . . . . . . . . . 21
	5.1. Normative References . . . . . . . . . . . . . . . . . . 20		5.1. Normative References . . . . . . . . . . . . . . . . . . 21
	5.2. Informative References . . . . . . . . . . . . . . . . . 20		5.2. Informative References . . . . . . . . . . . . . . . . . 22
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23
	1. Introduction		1. Introduction
	HTTP intermediaries -- including both forward proxies and gateways		HTTP intermediaries -- including both forward proxies and gateways
	(also known as "reverse proxies") -- have become an increasingly		(also known as "reverse proxies") -- have become an increasingly
	significant part of HTTP deployments. In particular, reverse proxies		significant part of HTTP deployments. In particular, reverse proxies
	and Content Delivery Networks (CDNs) form part of the critical		and Content Delivery Networks (CDNs) form part of the critical
	infrastructure of many Web sites.		infrastructure of many Web sites.
	Typically, HTTP intermediaries forward requests towards the origin		Typically, HTTP intermediaries forward requests towards the origin
	skipping to change at page 4, line 42 ¶		skipping to change at page 4, line 42 ¶
	Each member of the list represents an intermediary that has handled		Each member of the list represents an intermediary that has handled
	the response. The first member of the list represents the		the response. The first member of the list represents the
	intermediary closest to the origin server, and the last member of the		intermediary closest to the origin server, and the last member of the
	list represents the intermediary closest to the user agent.		list represents the intermediary closest to the user agent.
	For example:		For example:
	Proxy-Status: FooProxy, ExampleCDN		Proxy-Status: FooProxy, ExampleCDN
	indicates that this response was handled first by FooProxy and then		indicates that this response was handled first by FooProxy (a reverse
	ExampleCDN.		proxy adjacent to the origin server) and then ExampleCDN.
	Intermediaries determine when it is appropriate to add the Proxy-		Intermediaries determine when it is appropriate to add the Proxy-
	Status field to a response. Some might decide to append to it to all		Status field to a response. Some might decide to append to it to all
	responses, whereas others might only do so when specifically		responses, whereas others might only do so when specifically
	configured to, or when the request contains a header that activates a		configured to, or when the request contains a header that activates a
	debugging mode.		debugging mode.
	Each member of the list identifies the intermediary that inserted the		Each member of the list identifies the intermediary that inserted the
	value, and MUST have a type of either sf-string or sf-token.		value, and MUST have a type of either sf-string or sf-token.
	Depending on the deployment, this might be a product or service name		Depending on the deployment, this might be a product or service name
	skipping to change at page 7, line 12 ¶		skipping to change at page 7, line 12 ¶
	Proxy-Status: cdn.example.org; next-hop=backend.example.org		Proxy-Status: cdn.example.org; next-hop=backend.example.org
	2.1.3. next-protocol		2.1.3. next-protocol
	The "next-protocol" parameter's value indicates the ALPN protocol		The "next-protocol" parameter's value indicates the ALPN protocol
	identifier [RFC7301] used by the intermediary to connect to the next		identifier [RFC7301] used by the intermediary to connect to the next
	hop. This is only applicable when that connection was actually		hop. This is only applicable when that connection was actually
	established.		established.
	The value MUST be either an sf-token or sf-binary. If the protocol		The value MUST be either an sf-token or sf-binary, representing a TLS
	identifier is able to be expressed as an sf-token using UTF-8		Application-Layer Protocol Negotiation (ALPN) Protocol ID (see
			https://www.iana.org/assignments/tls-extensiontype-values/tls-
			extensiontype-values.xhtml#alpn-protocol-ids
			(https://www.iana.org/assignments/tls-extensiontype-values/tls-
			extensiontype-values.xhtml#alpn-protocol-ids)). If the protocol
			identifier is able to be expressed as an sf-token using ASCII
	encoding, that form MUST be used.		encoding, that form MUST be used.
	For example:		For example:
	Proxy-Status: "proxy.example.org"; next-protocol=h2		Proxy-Status: "proxy.example.org"; next-protocol=h2
	2.1.4. received-status		2.1.4. received-status
	The "received-status" parameter's value indicates the HTTP status		The "received-status" parameter's value indicates the HTTP status
	code that the intermediary received from the next hop server.		code that the intermediary received from the next hop server.
	skipping to change at page 7, line 47 ¶		skipping to change at page 8, line 5 ¶
	For example:		For example:
	Proxy-Status: ExampleProxy; error="http_protocol_error";		Proxy-Status: ExampleProxy; error="http_protocol_error";
	details="Malformed response header - space before colon"		details="Malformed response header - space before colon"
	2.2. Defining New Proxy-Status Parameters		2.2. Defining New Proxy-Status Parameters
	New Proxy-Status Parameters can be defined by registering them in the		New Proxy-Status Parameters can be defined by registering them in the
	HTTP Proxy-Status Parameters registry.		HTTP Proxy-Status Parameters registry.
	Registration requests are reviewed and approved by a Designated		Registration requests are reviewed and approved by Expert Review, as
	Expert, as per [RFC8126], Section 4.5. A specification document is		per [RFC8126], Section 4.5. A specification document is appreciated,
	appreciated, but not required.		but not required.
	The Expert(s) should consider the following factors when evaluating		The Expert(s) should consider the following factors when evaluating
	requests:		requests:
	* Community feedback		* Community feedback
	* If the value is sufficiently well-defined		* If the value is sufficiently well-defined
	* Generic parameters are preferred over vendor-specific,		* Generic parameters are preferred over vendor-specific,
	application-specific or deployment-specific values. If a generic		application-specific or deployment-specific values. If a generic
	skipping to change at page 8, line 24 ¶		skipping to change at page 8, line 31 ¶
	* Parameter names should not conflict with registered extra		* Parameter names should not conflict with registered extra
	parameters in the Proxy Error Type Registry.		parameters in the Proxy Error Type Registry.
	Registration requests should use the following template:		Registration requests should use the following template:
	* Name: [a name for the Proxy-Status Parameter that matches key]		* Name: [a name for the Proxy-Status Parameter that matches key]
	* Description: [a description of the parameter semantics and value]		* Description: [a description of the parameter semantics and value]
	* Reference: [to a specification defining this parameter]		* Reference: [to a specification defining this parameter; optional]
	See the registry at https://iana.org/assignments/http-proxy-status		See the registry at https://iana.org/assignments/http-proxy-status
	(https://iana.org/assignments/http-proxy-status) for details on where		(https://iana.org/assignments/http-proxy-status) for details on where
	to send registration requests.		to send registration requests.
	2.3. Proxy Error Types		2.3. Proxy Error Types
	This section lists the Proxy Error Types defined by this document.		This section lists the Proxy Error Types defined by this document.
	See Section 2.4 for information about defining new Proxy Error Types.		See Section 2.4 for information about defining new Proxy Error Types.
			Note that implementations might not produce all Proxy Error Types.
			The set of types below is designed to map to existing states in
			implementations, and so may not be applicable to some.
	2.3.1. DNS Timeout		2.3.1. DNS Timeout
	* Name: dns_timeout		* Name: dns_timeout
	* Description: The intermediary encountered a timeout when trying to		* Description: The intermediary encountered a timeout when trying to
	find an IP address for the next hop hostname.		find an IP address for the next hop hostname.
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 504		* Recommended HTTP status code: 504
			* Reference: [this document]
	2.3.2. DNS Error		2.3.2. DNS Error
	* Name: dns_error		* Name: dns_error
	* Description: The intermediary encountered a DNS error when trying		* Description: The intermediary encountered a DNS error when trying
	to find an IP address for the next hop hostname.		to find an IP address for the next hop hostname.
	* Extra Parameters:		* Extra Parameters:
	- rcode: A sf-string conveying the DNS RCODE that indicates the		- rcode: A sf-string conveying the DNS RCODE that indicates the
	error type. See [RFC8499], Section 3.		error type. See [RFC8499], Section 3.
	- info-code: A sf-integer conveying the Extended DNS Error Code		- info-code: A sf-integer conveying the Extended DNS Error Code
	info-code. See [RFC8914].		info-code. See [RFC8914].
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
			* Reference: [this document]
	2.3.3. Destination Not Found		2.3.3. Destination Not Found
	* Name: destination_not_found		* Name: destination_not_found
	* Description: The intermediary cannot determine the appropriate		* Description: The intermediary cannot determine the appropriate
	next hop to use for this request; for example, it may not be		next hop to use for this request; for example, it may not be
	configured. Note that this error is specific to gateways, which		configured. Note that this error is specific to gateways, which
	typically require specific configuration to identify the "backend"		typically require specific configuration to identify the "backend"
	server; forward proxies use in-band information to identify the		server; forward proxies use in-band information to identify the
	origin server.		origin server.
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 500		* Recommended HTTP status code: 500
			* Reference: [this document]
	2.3.4. Destination Unavailable		2.3.4. Destination Unavailable
	* Name: destination_unavailable		* Name: destination_unavailable
	* Description: The intermediary considers the next hop to be		* Description: The intermediary considers the next hop to be
	unavailable; e.g., recent attempts to communicate with it may have		unavailable; e.g., recent attempts to communicate with it may have
	failed, or a health check may indicate that it is down.		failed, or a health check may indicate that it is down.
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 503		* Recommended HTTP status code: 503
			* Reference: [this document]
	2.3.5. Destination IP Prohibited		2.3.5. Destination IP Prohibited
	* Name: destination_ip_prohibited		* Name: destination_ip_prohibited
	* Description: The intermediary is configured to prohibit		* Description: The intermediary is configured to prohibit
	connections to the next hop IP address.		connections to the next hop IP address.
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
			* Reference: [this document]
	2.3.6. Destination IP Unroutable		2.3.6. Destination IP Unroutable
	* Name: destination_ip_unroutable		* Name: destination_ip_unroutable
	* Description: The intermediary cannot find a route to the next hop		* Description: The intermediary cannot find a route to the next hop
	IP address.		IP address.
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
			* Reference: [this document]
	2.3.7. Connection Refused		2.3.7. Connection Refused
	* Name: connection_refused		* Name: connection_refused
	* Description: The intermediary's connection to the next hop was		* Description: The intermediary's connection to the next hop was
	refused.		refused.
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
			* Reference: [this document]
	2.3.8. Connection Terminated		2.3.8. Connection Terminated
	* Name: connection_terminated		* Name: connection_terminated
	* Description: The intermediary's connection to the next hop was		* Description: The intermediary's connection to the next hop was
	closed before complete response was received.		closed before complete response was received.
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
			* Reference: [this document]
	* Notes: Responses with this error type might not have been		* Notes: Responses with this error type might not have been
	generated by the intermediary.		generated by the intermediary.
	2.3.9. Connection Timeout		2.3.9. Connection Timeout
	* Name: connection_timeout		* Name: connection_timeout
	* Description: The intermediary's attempt to open a connection to		* Description: The intermediary's attempt to open a connection to
	the next hop timed out.		the next hop timed out.
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 504		* Recommended HTTP status code: 504
			* Reference: [this document]
	2.3.10. Connection Read Timeout		2.3.10. Connection Read Timeout
	* Name: connection_read_timeout		* Name: connection_read_timeout
	* Description: The intermediary was expecting data on a connection		* Description: The intermediary was expecting data on a connection
	(e.g., part of a response), but did not receive any new data in a		(e.g., part of a response), but did not receive any new data in a
	configured time limit.		configured time limit.
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 504		* Recommended HTTP status code: 504
			* Reference: [this document]
	* Notes: Responses with this error type might not have been		* Notes: Responses with this error type might not have been
	generated by the intermediary.		generated by the intermediary.
	2.3.11. Connection Write Timeout		2.3.11. Connection Write Timeout
	* Name: connection_write_timeout		* Name: connection_write_timeout
	* Description: The intermediary was attempting to write data to a		* Description: The intermediary was attempting to write data to a
	connection, but was not able to (e.g., because its buffers were		connection, but was not able to (e.g., because its buffers were
	full).		full).
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 504		* Recommended HTTP status code: 504
			* Reference: [this document]
	* Notes: Responses with this error type might not have been		* Notes: Responses with this error type might not have been
	generated by the intermediary.		generated by the intermediary.
	2.3.12. Connection Limit Reached		2.3.12. Connection Limit Reached
	* Name: connection_limit_reached		* Name: connection_limit_reached
	* Description: The intermediary is configured to limit the number of		* Description: The intermediary is configured to limit the number of
	connections it has to the next hop, and that limit has been		connections it has to the next hop, and that limit has been
	passed.		passed.
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 503		* Recommended HTTP status code: 503
			* Reference: [this document]
	2.3.13. TLS Protocol Error		2.3.13. TLS Protocol Error
	* Name: tls_protocol_error		* Name: tls_protocol_error
	* Description: The intermediary encountered a TLS error when		* Description: The intermediary encountered a TLS error when
	communicating with the next hop, either during handshake or		communicating with the next hop, either during handshake or
	afterwards.		afterwards.
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
			* Reference: [this document]
	* Notes: Responses with this error type might not have been		* Notes: Responses with this error type might not have been
	generated by the intermediary.		generated by the intermediary.
	Note that additional information about the error can be recorded in		Note that additional information about the error can be recorded in
	the details parameter (as is the case for all errors).		the details parameter (as is the case for all errors).
	2.3.14. TLS Certificate Error		2.3.14. TLS Certificate Error
	* Name: tls_certificate_error		* Name: tls_certificate_error
	* Description: The intermediary encountered an error when verifying		* Description: The intermediary encountered an error when verifying
	the certificate presented by the next hop.		the certificate presented by the next hop.
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
			* Reference: [this document]
	Note that additional information about the error can be recorded in		Note that additional information about the error can be recorded in
	the details parameter (as is the case for all errors).		the details parameter (as is the case for all errors).
	2.3.15. TLS Alert Received		2.3.15. TLS Alert Received
	* Name: tls_alert_received		* Name: tls_alert_received
	* Description: The intermediary received a TLS alert from the next		* Description: The intermediary received a TLS alert from the next
	hop.		hop.
	* Extra Parameters:		* Extra Parameters:
			- alert-id: an sf-integer containing the applicable value from
			the TLS Alerts registry. See {!RFC8446}}.
	- alert-message: an sf-token containing the applicable		- alert-message: an sf-token containing the applicable
	description string from the TLS Alerts registry.		description string from the TLS Alerts registry. See
			[RFC8446].
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
			* Reference: [this document]
	* Notes: Responses with this error type might not have been		* Notes: Responses with this error type might not have been
	generated by the intermediary.		generated by the intermediary.
	2.3.16. HTTP Request Error		2.3.16. HTTP Request Error
	* Name: http_request_error		* Name: http_request_error
	* Description: The intermediary is generating a client (4xx)		* Description: The intermediary is generating a client (4xx)
	response on the origin's behalf. Applicable status codes include		response on the origin's behalf. Applicable status codes include
	(but are not limited to) 400, 403, 405, 406, 408, 411, 413, 414,		(but are not limited to) 400, 403, 405, 406, 408, 411, 413, 414,
	skipping to change at page 13, line 24 ¶		skipping to change at page 14, line 15 ¶
	* Extra Parameters:		* Extra Parameters:
	- status-code: an sf-integer containing the generated status		- status-code: an sf-integer containing the generated status
	code.		code.
	- status-phrase: an sf-string containing the generated status		- status-phrase: an sf-string containing the generated status
	phrase.		phrase.
	* Recommended HTTP status code: The applicable 4xx status code		* Recommended HTTP status code: The applicable 4xx status code
			* Reference: [this document]
	* Notes: This type helps distinguish between responses generated by		* Notes: This type helps distinguish between responses generated by
	intermediaries from those generated by the origin.		intermediaries from those generated by the origin.
	2.3.17. HTTP Request Denied		2.3.17. HTTP Request Denied
	* Name: http_request_denied		* Name: http_request_denied
	* Description: The intermediary rejected the HTTP request based on		* Description: The intermediary rejected the HTTP request based on
	its configuration and/or policy settings. The request wasn't		its configuration and/or policy settings. The request wasn't
	forwarded to the next hop.		forwarded to the next hop.
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 403		* Recommended HTTP status code: 403
			* Reference: [this document]
	2.3.18. HTTP Incomplete Response		2.3.18. HTTP Incomplete Response
	* Name: http_response_incomplete		* Name: http_response_incomplete
	* Description: The intermediary received an incomplete response to		* Description: The intermediary received an incomplete response to
	the request from the next hop.		the request from the next hop.
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
			* Reference: [this document]
	* Notes: Responses with this error type might not have been		* Notes: Responses with this error type might not have been
	generated by the intermediary.		generated by the intermediary.
	2.3.19. HTTP Response Header Section Too Large		2.3.19. HTTP Response Header Section Too Large
	* Name: http_response_header_section_size		* Name: http_response_header_section_size
	* Description: The intermediary received a response to the request		* Description: The intermediary received a response to the request
	whose header section was considered too large.		whose header section was considered too large.
	* Extra Parameters:		* Extra Parameters:
	- header-section-size: an sf-integer indicating how large the		- header-section-size: an sf-integer indicating how large the
	headers received were. Note that they might not be complete;		headers received were. Note that they might not be complete;
	i.e., the intermediary may have discarded or refused additional		i.e., the intermediary may have discarded or refused additional
	data.		data.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
			* Reference: [this document]
	* Notes: Responses with this error type might not have been		* Notes: Responses with this error type might not have been
	generated by the intermediary.		generated by the intermediary.
	2.3.20. HTTP Response Header Too Large		2.3.20. HTTP Response Header Too Large
	* Name: http_response_header_size		* Name: http_response_header_size
	* Description: The intermediary received a response to the request		* Description: The intermediary received a response to the request
	containing an individual header line that was considered too		containing an individual header line that was considered too
	large.		large.
	skipping to change at page 14, line 42 ¶		skipping to change at page 15, line 44 ¶
	* Extra Parameters:		* Extra Parameters:
	- header-name: an sf-string indicating the name of the header		- header-name: an sf-string indicating the name of the header
	that triggered the error.		that triggered the error.
	- header-size: an sf-integer indicating the size of the header		- header-size: an sf-integer indicating the size of the header
	that triggered the error.		that triggered the error.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
			* Reference: [this document]
	* Notes: Responses with this error type might not have been		* Notes: Responses with this error type might not have been
	generated by the intermediary.		generated by the intermediary.
	2.3.21. HTTP Response Body Too Large		2.3.21. HTTP Response Body Too Large
	* Name: http_response_body_size		* Name: http_response_body_size
	* Description: The intermediary received a response to the request		* Description: The intermediary received a response to the request
	whose body was considered too large.		whose body was considered too large.
	* Extra Parameters:		* Extra Parameters:
	- body-size: an sf-integer indicating how large the body received		- body-size: an sf-integer indicating how large the body received
	was. Note that it may not have been complete; i.e., the		was. Note that it may not have been complete; i.e., the
	intermediary may have discarded or refused additional data.		intermediary may have discarded or refused additional data.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
			* Reference: [this document]
	* Notes: Responses with this error type might not have been		* Notes: Responses with this error type might not have been
	generated by the intermediary.		generated by the intermediary.
	2.3.22. HTTP Response Trailer Section Too Large		2.3.22. HTTP Response Trailer Section Too Large
	* Name: http_response_trailer_section_size		* Name: http_response_trailer_section_size
	* Description: The intermediary received a response to the request		* Description: The intermediary received a response to the request
	whose trailer section was considered too large.		whose trailer section was considered too large.
	* Extra Parameters:		* Extra Parameters:
	- trailer-section-size: an sf-integer indicating how large the		- trailer-section-size: an sf-integer indicating how large the
	trailers received were. Note that they might not be complete;		trailers received were. Note that they might not be complete;
	i.e., the intermediary may have discarded or refused additional		i.e., the intermediary may have discarded or refused additional
	data.		data.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
			* Reference: [this document]
	* Notes: Responses with this error type might not have been		* Notes: Responses with this error type might not have been
	generated by the intermediary.		generated by the intermediary.
	2.3.23. HTTP Response Trailer Too Large		2.3.23. HTTP Response Trailer Too Large
	* Name: http_response_trailer_size		* Name: http_response_trailer_size
	* Description: The intermediary received a response to the request		* Description: The intermediary received a response to the request
	containing an individual trailer line that was considered too		containing an individual trailer line that was considered too
	large.		large.
	skipping to change at page 15, line 51 ¶		skipping to change at page 17, line 13 ¶
	* Extra Parameters:		* Extra Parameters:
	- trailer-name: an sf-string indicating the name of the trailer		- trailer-name: an sf-string indicating the name of the trailer
	that triggered the error.		that triggered the error.
	- trailer-size: an sf-integer indicating the size of the trailer		- trailer-size: an sf-integer indicating the size of the trailer
	that triggered the error.		that triggered the error.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
			* Reference: [this document]
	* Notes: Responses with this error type might not have been		* Notes: Responses with this error type might not have been
	generated by the intermediary.		generated by the intermediary.
	2.3.24. HTTP Response Transfer-Coding Error		2.3.24. HTTP Response Transfer-Coding Error
	* Name: http_response_transfer_coding		* Name: http_response_transfer_coding
	* Description: The intermediary encountered an error decoding the		* Description: The intermediary encountered an error decoding the
	transfer-coding of the response.		transfer-coding of the response.
	* Extra Parameters:		* Extra Parameters:
	- coding: an sf-token containing the specific coding that caused		- coding: an sf-token containing the specific coding that caused
	the error.		the error.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
			* Reference: [this document]
	* Notes: Responses with this error type might not have been		* Notes: Responses with this error type might not have been
	generated by the intermediary.		generated by the intermediary.
	2.3.25. HTTP Response Content-Coding Error		2.3.25. HTTP Response Content-Coding Error
	* Name: http_response_content_coding		* Name: http_response_content_coding
	* Description: The intermediary encountered an error decoding the		* Description: The intermediary encountered an error decoding the
	content-coding of the response.		content-coding of the response.
	* Extra Parameters:		* Extra Parameters:
	- coding: an sf-token containing the specific coding that caused		- coding: an sf-token containing the specific coding that caused
	the error.		the error.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
			* Reference: [this document]
	* Notes: Responses with this error type might not have been		* Notes: Responses with this error type might not have been
	generated by the intermediary.		generated by the intermediary.
	2.3.26. HTTP Response Timeout		2.3.26. HTTP Response Timeout
	* Name: http_response_timeout		* Name: http_response_timeout
	* Description: The intermediary reached a configured time limit		* Description: The intermediary reached a configured time limit
	waiting for the complete response.		waiting for the complete response.
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 504		* Recommended HTTP status code: 504
			* Reference: [this document]
	* Notes: Responses with this error type might not have been		* Notes: Responses with this error type might not have been
	generated by the intermediary.		generated by the intermediary.
	2.3.27. HTTP Upgrade Failed		2.3.27. HTTP Upgrade Failed
	* Name: http_upgrade_failed		* Name: http_upgrade_failed
	* Description: The HTTP Upgrade between the intermediary and the		* Description: The HTTP Upgrade between the intermediary and the
	next hop failed.		next hop failed.
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
			* Reference: [this document]
	2.3.28. HTTP Protocol Error		2.3.28. HTTP Protocol Error
	* Name: http_protocol_error		* Name: http_protocol_error
	* Description: The intermediary encountered a HTTP protocol error		* Description: The intermediary encountered a HTTP protocol error
	when communicating with the next hop. This error should only be		when communicating with the next hop. This error should only be
	used when a more specific one is not defined.		used when a more specific one is not defined.
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
			* Reference: [this document]
	* Notes: Responses with this error type might not have been		* Notes: Responses with this error type might not have been
	generated by the intermediary.		generated by the intermediary.
	Note that additional information about the error can be recorded in		Note that additional information about the error can be recorded in
	the details parameter (as is the case for all errors).		the details parameter (as is the case for all errors).
	2.3.29. Proxy Internal Response		2.3.29. Proxy Internal Response
	* Name: proxy_internal_response		* Name: proxy_internal_response
	* Description: The intermediary generated the response locally,		* Description: The intermediary generated the response locally,
	without attempting to connect to the next hop (e.g. in response to		without attempting to connect to the next hop (e.g. in response to
	a request to a debug endpoint terminated at the intermediary).		a request to a debug endpoint terminated at the intermediary).
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code:		* Recommended HTTP status code: The most appropriate status code for
			the response
			* Reference: [this document]
	2.3.30. Proxy Internal Error		2.3.30. Proxy Internal Error
	* Name: proxy_internal_error		* Name: proxy_internal_error
	* Description: The intermediary encountered an internal error		* Description: The intermediary encountered an internal error
	unrelated to the origin.		unrelated to the origin.
	* Extra Parameters: None		* Extra Parameters: None
	* Recommended HTTP status code: 500		* Recommended HTTP status code: 500
			* Reference: [this document]
	Note that additional information about the error can be recorded in		Note that additional information about the error can be recorded in
	the details parameter (as is the case for all errors).		the details parameter (as is the case for all errors).
	2.3.31. Proxy Configuration Error		2.3.31. Proxy Configuration Error
	* Name: proxy_configuration_error		* Name: proxy_configuration_error
	* Description: The intermediary encountered an error regarding its		* Description: The intermediary encountered an error regarding its
	configuration.		configuration.
	* Extra Parameters: None		* Extra Parameters: None
	* Recommended HTTP status code: 500		* Recommended HTTP status code: 500
			* Reference: [this document]
	Note that additional information about the error can be recorded in		Note that additional information about the error can be recorded in
	the details parameter (as is the case for all errors).		the details parameter (as is the case for all errors).
	2.3.32. Proxy Loop Detected		2.3.32. Proxy Loop Detected
	* Name: proxy_loop_detected		* Name: proxy_loop_detected
	* Description: The intermediary tried to forward the request to		* Description: The intermediary tried to forward the request to
	itself, or a loop has been detected using different means (e.g.		itself, or a loop has been detected using different means (e.g.
	[RFC8586]).		[RFC8586]).
	* Extra Parameters: None.		* Extra Parameters: None.
	* Recommended HTTP status code: 502		* Recommended HTTP status code: 502
			* Reference: [this document]
	2.4. Defining New Proxy Error Types		2.4. Defining New Proxy Error Types
	New Proxy Error Types can be defined by registering them in the HTTP		New Proxy Error Types can be defined by registering them in the HTTP
	Proxy Error Types registry.		Proxy Error Types registry.
	Registration requests are reviewed and approved by a Designated		Registration requests are reviewed and approved by Expert Review, as
	Expert, as per [RFC8126], Section 4.5. A specification document is		per [RFC8126], Section 4.5. A specification document is appreciated,
	appreciated, but not required.		but not required.
	The Expert(s) should consider the following factors when evaluating		The Expert(s) should consider the following factors when evaluating
	requests:		requests:
	* Community feedback		* Community feedback
	* If the value is sufficiently well-defined		* If the value is sufficiently well-defined
	* Generic types are preferred over vendor-specific, application-		* Generic types are preferred over vendor-specific, application-
	specific or deployment-specific values. If a generic value cannot		specific or deployment-specific values. If a generic value cannot
	be agreed upon in the community, the types's name should be		be agreed upon in the community, the types's name should be
	correspondingly specific (e.g., with a prefix that identifies the		correspondingly specific (e.g., with a prefix that identifies the
	vendor, application or deployment).		vendor, application or deployment).
	* Extra Parameters should not conflict with registered Proxy-Status		* Extra Parameters should not conflict with registered Proxy-Status
	parameters.		parameters.
	Registration requests should use the following template:		Registration requests should use the following template:
	skipping to change at page 19, line 26 ¶		skipping to change at page 21, line 11 ¶
	* Description: [a description of the conditions that generate the		* Description: [a description of the conditions that generate the
	Proxy Error Type]		Proxy Error Type]
	* Extra Parameters: [zero or more optional parameters, along with		* Extra Parameters: [zero or more optional parameters, along with
	their allowable type(s)]		their allowable type(s)]
	* Recommended HTTP status code: [the appropriate HTTP status code		* Recommended HTTP status code: [the appropriate HTTP status code
	for this entry]		for this entry]
			* Reference: [to a specification defining this error type; optional]
	* Notes: [optional]		* Notes: [optional]
	If the Proxy Error Type might occur in responses that are not		If the Proxy Error Type might occur in responses that are not
	generated by the intermediary -- for example, when the error is		generated by the intermediary -- for example, when the error is
	detected during response content processing and a Proxy-Status		detected during response content processing and a Proxy-Status
	trailer field is appended -- that SHOULD be explained in the Notes.		trailer field is appended -- that SHOULD be explained in the Notes.
	See the registry at https://iana.org/assignments/http-proxy-status		See the registry at https://iana.org/assignments/http-proxy-status
	(https://iana.org/assignments/http-proxy-status) for details on where		(https://iana.org/assignments/http-proxy-status) for details on where
	to send registration requests.		to send registration requests.
	3. IANA Considerations		3. IANA Considerations
	Upon publication, please create the HTTP Proxy-Status Parameters		Upon publication, please create the HTTP Proxy-Status Parameters
	registry and the HTTP Proxy Error Types registry at		registry and the HTTP Proxy Error Types registry at
	https://iana.org/assignments/http-proxy-statuses		https://iana.org/assignments/http-proxy-status
	(https://iana.org/assignments/http-proxy-statuses) and populate them		(https://iana.org/assignments/http-proxy-status) and populate them
	with the types defined in Section 2.1 and Section 2.3 respectively;		with the types defined in Section 2.1 and Section 2.3 respectively;
	see Section 2.2 and Section 2.4 for its associated procedures.		see Section 2.2 and Section 2.4 for its associated procedures.
	4. Security Considerations		4. Security Considerations
	One of the primary security concerns when using Proxy-Status is		One of the primary security concerns when using Proxy-Status is
	leaking information that might aid an attacker. For example,		leaking information that might aid an attacker. For example,
	information about the intermediary's configuration and back-end		information about the intermediary's configuration and back-end
	topology can be exposed.		topology can be exposed.
	skipping to change at page 20, line 49 ¶		skipping to change at page 22, line 37 ¶
	[RFC7301] Friedl, S., Popov, A., Langley, A., and E. Stephan,		[RFC7301] Friedl, S., Popov, A., Langley, A., and E. Stephan,
	"Transport Layer Security (TLS) Application-Layer Protocol		"Transport Layer Security (TLS) Application-Layer Protocol
	Negotiation Extension", RFC 7301, DOI 10.17487/RFC7301,		Negotiation Extension", RFC 7301, DOI 10.17487/RFC7301,
	July 2014, <https://www.rfc-editor.org/rfc/rfc7301>.		July 2014, <https://www.rfc-editor.org/rfc/rfc7301>.
	[RFC8914] Kumari, W., Hunt, E., Arends, R., Hardaker, W., and D.		[RFC8914] Kumari, W., Hunt, E., Arends, R., Hardaker, W., and D.
	Lawrence, "Extended DNS Errors", RFC 8914,		Lawrence, "Extended DNS Errors", RFC 8914,
	DOI 10.17487/RFC8914, October 2020,		DOI 10.17487/RFC8914, October 2020,
	<https://www.rfc-editor.org/rfc/rfc8914>.		<https://www.rfc-editor.org/rfc/rfc8914>.
			[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
			Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
			<https://www.rfc-editor.org/rfc/rfc8446>.
	5.2. Informative References		5.2. Informative References
	[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax		[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
	Specifications: ABNF", STD 68, RFC 5234,		Specifications: ABNF", STD 68, RFC 5234,
	DOI 10.17487/RFC5234, January 2008,		DOI 10.17487/RFC5234, January 2008,
	<https://www.rfc-editor.org/rfc/rfc5234>.		<https://www.rfc-editor.org/rfc/rfc5234>.
	[RFC8586] Ludin, S., Nottingham, M., and N. Sullivan, "Loop		[RFC8586] Ludin, S., Nottingham, M., and N. Sullivan, "Loop
	Detection in Content Delivery Networks (CDNs)", RFC 8586,		Detection in Content Delivery Networks (CDNs)", RFC 8586,
	DOI 10.17487/RFC8586, April 2019,		DOI 10.17487/RFC8586, April 2019,
End of changes. 56 change blocks.
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