draft-ietf-shim6-multihome-shim-api-12.txt		draft-ietf-shim6-multihome-shim-api-13.txt
	SHIM6 Working Group M. Komu		SHIM6 Working Group M. Komu
	Internet-Draft HIIT		Internet-Draft HIIT
	Intended status: Informational M. Bagnulo		Intended status: Informational M. Bagnulo
	Expires: July 13, 2010 UC3M		Expires: August 26, 2010 UC3M
	K. Slavov		K. Slavov
	S. Sugimoto, Ed.		S. Sugimoto, Ed.
	Ericsson		Ericsson
	January 9, 2010		February 22, 2010
	Socket Application Program Interface (API) for Multihoming Shim		Socket Application Program Interface (API) for Multihoming Shim
	draft-ietf-shim6-multihome-shim-api-12		draft-ietf-shim6-multihome-shim-api-13
			Abstract
			This document specifies sockets API extensions for the multihoming
			shim layer. The API aims to enable interactions between applications
			and the multihoming shim layer for advanced locator management, and
			access to information about failure detection and path exploration.
			This document is based on an assumption that a multihomed host is
			equipped with a conceptual sub-layer (hereafter "shim") inside the IP
			layer that maintains mappings between identifiers and locators.
			Examples of the shim are SHIM6 and HIP.
	Status of this Memo		Status of this Memo
	This Internet-Draft is submitted to IETF in full conformance with the		This Internet-Draft is submitted to IETF in full conformance with the
	provisions of BCP 78 and BCP 79.		provisions of BCP 78 and BCP 79.
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF), its areas, and its working groups. Note that		Task Force (IETF), its areas, and its working groups. Note that
	other groups may also distribute working documents as Internet-		other groups may also distribute working documents as Internet-
	Drafts.		Drafts.
	skipping to change at page 1, line 36		skipping to change at page 1, line 48
	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."
	The list of current Internet-Drafts can be accessed at		The list of current Internet-Drafts can be accessed at
	http://www.ietf.org/ietf/1id-abstracts.txt.		http://www.ietf.org/ietf/1id-abstracts.txt.
	The list of Internet-Draft Shadow Directories can be accessed at		The list of Internet-Draft Shadow Directories can be accessed at
	http://www.ietf.org/shadow.html.		http://www.ietf.org/shadow.html.
	This Internet-Draft will expire on July 13, 2010.		This Internet-Draft will expire on August 26, 2010.
	Copyright Notice		Copyright Notice
	Copyright (c) 2010 IETF Trust and the persons identified as the		Copyright (c) 2010 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 in effect on the date of		Provisions Relating to IETF Documents
	publication of this document (http://trustee.ietf.org/license-info).		(http://trustee.ietf.org/license-info) in effect on the date of
	Please review these documents carefully, as they describe your rights		publication of this document. Please review these documents
	and restrictions with respect to this document.		carefully, as they describe your rights and restrictions with respect
			to this document. Code Components extracted from this document must
	Abstract		include Simplified BSD License text as described in Section 4.e of
			the Trust Legal Provisions and are provided without warranty as
	This document specifies sockets API extensions for the multihoming		described in the BSD License.
	shim layer. The API aims to enable interactions between applications
	and the multihoming shim layer for advanced locator management, and
	access to information about failure detection and path exploration.
	This document is based on an assumption that a multihomed host is
	equipped with a conceptual sub-layer (hereafter "shim") inside the IP
	layer that maintains mappings between identifiers and locators.
	Examples of the shim are SHIM6 and HIP.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
	2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5		2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
	3. System Overview . . . . . . . . . . . . . . . . . . . . . . . 6		3. System Overview . . . . . . . . . . . . . . . . . . . . . . . 6
	4. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 7		4. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 7
	5. Socket Options for Multihoming Shim Sub-layer . . . . . . . . 9		5. Socket Options for Multihoming Shim Sub-layer . . . . . . . . 9
	5.1. SHIM_ASSOCIATED . . . . . . . . . . . . . . . . . . . . . 13		5.1. SHIM_ASSOCIATED . . . . . . . . . . . . . . . . . . . . . 12
	5.2. SHIM_DONTSHIM . . . . . . . . . . . . . . . . . . . . . . 14		5.2. SHIM_DONTSHIM . . . . . . . . . . . . . . . . . . . . . . 13
	5.3. SHIM_HOT_STANDBY . . . . . . . . . . . . . . . . . . . . 15		5.3. SHIM_HOT_STANDBY . . . . . . . . . . . . . . . . . . . . 14
	5.4. SHIM_PATHEXPLORE . . . . . . . . . . . . . . . . . . . . 15		5.4. SHIM_LOC_LOCAL_PREF . . . . . . . . . . . . . . . . . . . 15
	5.5. SHIM_LOC_LOCAL_PREF . . . . . . . . . . . . . . . . . . . 16		5.5. SHIM_LOC_PEER_PREF . . . . . . . . . . . . . . . . . . . 16
	5.6. SHIM_LOC_PEER_PREF . . . . . . . . . . . . . . . . . . . 17		5.6. SHIM_LOC_LOCAL_RECV . . . . . . . . . . . . . . . . . . . 17
	5.7. SHIM_LOC_LOCAL_RECV . . . . . . . . . . . . . . . . . . . 18		5.7. SHIM_LOC_PEER_RECV . . . . . . . . . . . . . . . . . . . 18
	5.8. SHIM_LOC_PEER_RECV . . . . . . . . . . . . . . . . . . . 19		5.8. SHIM_LOC_LOCAL_SEND . . . . . . . . . . . . . . . . . . . 18
	5.9. SHIM_LOC_LOCAL_SEND . . . . . . . . . . . . . . . . . . . 19		5.9. SHIM_LOC_PEER_SEND . . . . . . . . . . . . . . . . . . . 20
	5.10. SHIM_LOC_PEER_SEND . . . . . . . . . . . . . . . . . . . 21		5.10. SHIM_LOCLIST_LOCAL . . . . . . . . . . . . . . . . . . . 20
	5.11. SHIM_LOCLIST_LOCAL . . . . . . . . . . . . . . . . . . . 21		5.11. SHIM_LOCLIST_PEER . . . . . . . . . . . . . . . . . . . . 23
	5.12. SHIM_LOCLIST_PEER . . . . . . . . . . . . . . . . . . . . 23		5.12. SHIM_APP_TIMEOUT . . . . . . . . . . . . . . . . . . . . 23
	5.13. SHIM_APP_TIMEOUT . . . . . . . . . . . . . . . . . . . . 23		5.13. SHIM_PATHEXPLORE . . . . . . . . . . . . . . . . . . . . 24
	5.14. SHIM_DEFERRED_CONTEXT_SETUP . . . . . . . . . . . . . . . 24		5.14. SHIM_DEFERRED_CONTEXT_SETUP . . . . . . . . . . . . . . . 25
	5.15. Applicability . . . . . . . . . . . . . . . . . . . . . . 25		5.15. Applicability . . . . . . . . . . . . . . . . . . . . . . 26
	5.16. Error Handling . . . . . . . . . . . . . . . . . . . . . 25		5.16. Error Handling . . . . . . . . . . . . . . . . . . . . . 26
	6. Ancillary Data for Multihoming Shim Sub-layer . . . . . . . . 26		6. Ancillary Data for Multihoming Shim Sub-layer . . . . . . . . 26
	6.1. Get Locator from Incoming Packet . . . . . . . . . . . . 27		6.1. Get Locator from Incoming Packet . . . . . . . . . . . . 27
	6.2. Set Locator for Outgoing Packet . . . . . . . . . . . . . 27		6.2. Set Locator for Outgoing Packet . . . . . . . . . . . . . 28
	6.3. Notification from Application to Multihoming Shim		6.3. Notification from Application to Multihoming Shim
	Sub-layer . . . . . . . . . . . . . . . . . . . . . . . . 27		Sub-layer . . . . . . . . . . . . . . . . . . . . . . . . 28
	6.4. Notification from Multihoming Shim Sub-layer to		6.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 28
	Application . . . . . . . . . . . . . . . . . . . . . . . 28
	6.5. Applicability . . . . . . . . . . . . . . . . . . . . . . 28
	7. Data Structures . . . . . . . . . . . . . . . . . . . . . . . 29		7. Data Structures . . . . . . . . . . . . . . . . . . . . . . . 29
	7.1. Placeholder for Locator Information . . . . . . . . . . . 29		7.1. Placeholder for Locator Information . . . . . . . . . . . 29
	7.1.1. Handling Locator behind NAT . . . . . . . . . . . . . 30		7.1.1. Handling Locator behind NAT . . . . . . . . . . . . . 30
	7.2. Path Exploration Parameter . . . . . . . . . . . . . . . 31		7.2. Path Exploration Parameter . . . . . . . . . . . . . . . 31
	7.3. Feedback Information . . . . . . . . . . . . . . . . . . 32		7.3. Feedback Information . . . . . . . . . . . . . . . . . . 32
	8. System Requirements . . . . . . . . . . . . . . . . . . . . . 33		8. System Requirements . . . . . . . . . . . . . . . . . . . . . 33
	9. Relation to Existing Sockets API Extensions . . . . . . . . . 33		9. Relation to Existing Sockets API Extensions . . . . . . . . . 33
	10. Operational Considerations . . . . . . . . . . . . . . . . . . 34		10. Operational Considerations . . . . . . . . . . . . . . . . . . 33
	10.1. Conflict Resolution . . . . . . . . . . . . . . . . . . . 34		10.1. Conflict Resolution . . . . . . . . . . . . . . . . . . . 34
	10.2. Incompatiblility between IPv4 and IPv6 . . . . . . . . . 35		10.2. Incompatiblility between IPv4 and IPv6 . . . . . . . . . 34
	11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 35		11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 35
	12. Protocol Constants and Variables . . . . . . . . . . . . . . . 35		12. Protocol Constants and Variables . . . . . . . . . . . . . . . 35
	13. Security Considerations . . . . . . . . . . . . . . . . . . . 35		13. Security Considerations . . . . . . . . . . . . . . . . . . . 35
	13.1. Treatment of Unknown Locator . . . . . . . . . . . . . . 35		13.1. Treatment of Unknown Locator . . . . . . . . . . . . . . 35
	13.1.1. Treatment of Unknown Source Locator . . . . . . . . . 35		13.1.1. Treatment of Unknown Source Locator . . . . . . . . . 35
	13.1.2. Treatment of Unknown Destination Locator . . . . . . . 36		13.1.2. Treatment of Unknown Destination Locator . . . . . . . 36
	14. Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . 36		14. Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
	14.1. Changes from version 00 to version 01 . . . . . . . . . . 36		14.1. Changes from version 00 to version 01 . . . . . . . . . . 36
	14.2. Changes from version 01 to version 02 . . . . . . . . . . 36		14.2. Changes from version 01 to version 02 . . . . . . . . . . 36
	14.3. Changes from version 02 to version 03 . . . . . . . . . . 37		14.3. Changes from version 02 to version 03 . . . . . . . . . . 36
	14.4. Changes from version 03 to version 04 . . . . . . . . . . 37		14.4. Changes from version 03 to version 04 . . . . . . . . . . 36
	14.5. Changes from version 04 to version 05 . . . . . . . . . . 37		14.5. Changes from version 04 to version 05 . . . . . . . . . . 37
	14.6. Changes from version 05 to version 06 . . . . . . . . . . 37		14.6. Changes from version 05 to version 06 . . . . . . . . . . 37
	14.7. Changes from version 06 to version 07 . . . . . . . . . . 37		14.7. Changes from version 06 to version 07 . . . . . . . . . . 37
	14.8. Changes from version 07 to version 08 . . . . . . . . . . 37		14.8. Changes from version 07 to version 08 . . . . . . . . . . 37
	14.9. Changes from version 08 to version 09 . . . . . . . . . . 37		14.9. Changes from version 08 to version 09 . . . . . . . . . . 37
	14.10. Changes from version 09 to version 10 . . . . . . . . . . 37		14.10. Changes from version 09 to version 10 . . . . . . . . . . 37
	14.11. Changes from version 10 to version 11 . . . . . . . . . . 38		14.11. Changes from version 10 to version 11 . . . . . . . . . . 37
	14.12. Changes from version 11 to version 12 . . . . . . . . . . 38		14.12. Changes from version 11 to version 12 . . . . . . . . . . 37
			14.13. Changes from version 12 to version 13 . . . . . . . . . . 38
	15. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 38		15. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 38
	16. References . . . . . . . . . . . . . . . . . . . . . . . . . . 38		16. References . . . . . . . . . . . . . . . . . . . . . . . . . . 38
	16.1. Normative References . . . . . . . . . . . . . . . . . . 38		16.1. Normative References . . . . . . . . . . . . . . . . . . 38
	16.2. Informative References . . . . . . . . . . . . . . . . . 39		16.2. Informative References . . . . . . . . . . . . . . . . . 39
	Appendix A. Context Forking . . . . . . . . . . . . . . . . . . . 39		Appendix A. Context Forking . . . . . . . . . . . . . . . . . . . 39
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 41		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 41
	1. Introduction		1. Introduction
	This document defines socket API extensions by which upper layer		This document defines socket API extensions by which upper layer
	skipping to change at page 4, line 34		skipping to change at page 4, line 34
	Note that the shim sub-layer may conflict with other multihoming		Note that the shim sub-layer may conflict with other multihoming
	mechanisms such as SCTP and multipath		mechanisms such as SCTP and multipath
	TCP[I-D.ietf-shim6-applicability]. To avoid any conflict, only one		TCP[I-D.ietf-shim6-applicability]. To avoid any conflict, only one
	of SHIM6 and HIP should be in use.		of SHIM6 and HIP should be in use.
	In this document, syntax and semantics of the API are given in the		In this document, syntax and semantics of the API are given in the
	same way as the Posix standard [POSIX]. The API specifies how to use		same way as the Posix standard [POSIX]. The API specifies how to use
	ancillary data (aka cmsg) to access the locator information with		ancillary data (aka cmsg) to access the locator information with
	recvmsg() and/or sendmsg() I/O calls. The API is described in C		recvmsg() and/or sendmsg() I/O calls. The API is described in C
	language and data types are defined in the Posix format; intN_t means		language and data types are defined in the Posix format; intN_t means
	a singed integer of exactly N bits (e.g. int16_t) and uintN_t means		a signed integer of exactly N bits (e.g. int16_t) and uintN_t means
	an unsigned integer of exactly N bits (e.g. uint32_t).		an unsigned integer of exactly N bits (e.g. uint32_t).
	The distinction between "connected" sockets and "unconnected" sockets		The distinction between "connected" sockets and "unconnected" sockets
	is important when discussing the applicability of the socket API		is important when discussing the applicability of the socket API
	defined in this document. A connected socket is bound to a given		defined in this document. A connected socket is bound to a given
	peer, whereas an unconnected socket is not bound to any specific		peer, whereas an unconnected socket is not bound to any specific
	peers. A TCP socket becomes a connected socket when the TCP		peers. A TCP socket becomes a connected socket when the TCP
	connection establishment is completed. UDP sockets are unconnected,		connection establishment is completed. UDP sockets are unconnected,
	unless the application uses the connect() system call.		unless the application uses the connect() system call.
	skipping to change at page 8, line 23		skipping to change at page 8, line 23
	based manner. Applications and/or upper layer protocols may		based manner. Applications and/or upper layer protocols may
	provide positive feedbacks or negative feedbacks to the shim sub-		provide positive feedbacks or negative feedbacks to the shim sub-
	layer. Note that these feedbacks are mentioned in [RFC5534]:		layer. Note that these feedbacks are mentioned in [RFC5534]:
	* Applications and/or upper layer protocols (e.g., TCP) may		* Applications and/or upper layer protocols (e.g., TCP) may
	provide positive feedbacks to the shim sub-layer informing that		provide positive feedbacks to the shim sub-layer informing that
	the communication is going well.		the communication is going well.
	* Applications and/or upper layer protocols (e.g., TCP) may		* Applications and/or upper layer protocols (e.g., TCP) may
	provide negative feedbacks to the shim sub-layer informing that		provide negative feedbacks to the shim sub-layer informing that
	the communication status is not satisfactory. TCP may detect a		the communication status is not satisfactory. TCP may detect a
	problem when it does not receive any expected ACK message from		problem when it does not receive any expected ACK message from
	the peer. Besides, a receipt of an ICMP error message could be		the peer. The REAP module may be triggered by these negative
	a clue for the application to detect problems. The REAP module		feedbacks and invoke the path exploration procedure.
	may be triggered by these negative feedbacks and invoke the
	path exploration procedure.
	o Feedback from applications to the shim sub-layer. Applications		o Feedback from applications to the shim sub-layer. Applications
	should be able to inform the shim sub-layer of the timeout values		should be able to inform the shim sub-layer of the timeout values
	for detecting failures, sending keepalives, and starting the		for detecting failures, sending keepalives, and starting the
	exploration procedure. In particular, applications should be able		exploration procedure. In particular, applications should be able
	to suppress keepalives.		to suppress keepalives.
	o Hot-standby. Applications may request the shim sub-layer for the		o Hot-standby. Applications may request the shim sub-layer for the
	hot-standby capability. This means that, alternative paths are		hot-standby capability. This means that, alternative paths are
	known to be working in advance of a failure detection. In such a		known to be working in advance of a failure detection. In such a
	case, it is possible for the host to immediately replace the		case, it is possible for the host to immediately replace the
	current locator pair with an alternative locator pair.		current locator pair with an alternative locator pair.
	skipping to change at page 9, line 5		skipping to change at page 9, line 4
	should be able to obtain information about the locator pair which		should be able to obtain information about the locator pair which
	was actually used to send or receive the packet.		was actually used to send or receive the packet.
	* For inbound traffic, the application may be interested in the		* For inbound traffic, the application may be interested in the
	locator pair which was actually used to receive the packet.		locator pair which was actually used to receive the packet.
	* For outbound traffic, the application may be interested in the		* For outbound traffic, the application may be interested in the
	locator pair which was actually used to transmit the packet.		locator pair which was actually used to transmit the packet.
	In this way, applications may have additional control on the		In this way, applications may have additional control on the
	locator management. For example, an application becomes able to		locator management. For example, an application becomes able to
	verify if its preference for locator is actually applied to the		verify if its preference for locator is actually applied to the
	flow or not.		flow or not.
	o Applications should be able to specify if they want to defer the
	context setup, or if they want context establishment to be started		o Applications should be able to know if the shim-sublayer supports
	immediately in the case where there is no available context. A		deferred context setup or not.
	deferred context setup means that the initiation of communication
	should not be blocked to wait for completion of the context
	establishment.
	o An application should be able to know if the communication is now		o An application should be able to know if the communication is now
	being served by the shim sub-layer or not.		being served by the shim sub-layer or not.
	o An application should be able to use a common interface to access		o An application should be able to use a common interface to access
	an IPv4 locator and an IPv6 locator.		an IPv4 locator and an IPv6 locator.
	5. Socket Options for Multihoming Shim Sub-layer		5. Socket Options for Multihoming Shim Sub-layer
	In this section, socket options that are specific to the shim sub-		In this section, socket options that are specific to the shim sub-
	layer are defined.		layer are defined.
	skipping to change at page 10, line 11		skipping to change at page 9, line 37
	fifth column shows the type of data structure specified along with		fifth column shows the type of data structure specified along with
	the socket option. By default, the data structure type is an		the socket option. By default, the data structure type is an
	integer.		integer.
	+-----------------------------+-----+-----+-----------------+-------+		+-----------------------------+-----+-----+-----------------+-------+
	| optname | get | set | description | dtype |		| optname | get | set | description | dtype |
	+-----------------------------+-----+-----+-----------------+-------+		+-----------------------------+-----+-----+-----------------+-------+
	| SHIM_ASSOCIATED | o | | Get the | int |		| SHIM_ASSOCIATED | o | | Get the | int |
	| | | | parameter which | |		| | | | parameter which | |
	| | | | indicates | |		| | | | indicates | |
	| | | | whether if the | |		| | | | whether the | |
	| | | | socket is | |		| | | | socket is | |
	| | | | associated with | |		| | | | associated with | |
	| | | | any shim | |		| | | | any shim | |
	| | | | context or not. | |		| | | | context or not. | |
	| SHIM_DONTSHIM | o | o | Get or set the | int |		| SHIM_DONTSHIM | o | o | Get or set the | int |
	| | | | parameter which | |		| | | | parameter which | |
	| | | | indicates | |		| | | | indicates | |
	| | | | whether to | |		| | | | whether to | |
	| | | | employ the | |		| | | | employ the | |
	| | | | multihoming | |		| | | | multihoming | |
	skipping to change at page 11, line 23		skipping to change at page 10, line 44
	| | | | packet. | |		| | | | packet. | |
	| SHIM_LOC_PEER_RECV | o | o | Get or set the | int |		| SHIM_LOC_PEER_RECV | o | o | Get or set the | int |
	| | | | parameter which | |		| | | | parameter which | |
	| | | | is used to | |		| | | | is used to | |
	| | | | request the | |		| | | | request the | |
	| | | | shim sub-layer | |		| | | | shim sub-layer | |
	| | | | to store the | |		| | | | to store the | |
	| | | | source locator | |		| | | | source locator | |
	| | | | of the received | |		| | | | of the received | |
	| | | | IP packet. | |		| | | | IP packet. | |
	| SHIM_LOC_LOCAL_SEND | o | o | Get or set the | *2 |		| SHIM_LOC_LOCAL_SEND | o | o | Get or set the | *1 |
	| | | | source locator | |		| | | | source locator | |
	| | | | of outgoing IP | |		| | | | of outgoing IP | |
	| | | | packets. | |		| | | | packets. | |
	| SHIM_LOC_PEER_SEND | o | o | Get or set the | *2 |		| SHIM_LOC_PEER_SEND | o | o | Get or set the | *1 |
	| | | | destination | |		| | | | destination | |
	| | | | locator of | |		| | | | locator of | |
	| | | | outgoing IP | |		| | | | outgoing IP | |
	| | | | packets. | |		| | | | packets. | |
	| SHIM_LOCLIST_LOCAL | o | o | Get or set the | *3 |		| SHIM_LOCLIST_LOCAL | o | o | Get or set the | *2 |
	| | | | list of | |		| | | | list of | |
	| | | | locators | |		| | | | locators | |
	| | | | associated with | |		| | | | associated with | |
	| | | | the local EID. | |		| | | | the local EID. | |
	| SHIM_LOCLIST_PEER | o | o | Get or set the | *3 |		| SHIM_LOCLIST_PEER | o | o | Get or set the | *2 |
	| | | | list of | |		| | | | list of | |
	| | | | locators | |		| | | | locators | |
	| | | | associated with | |		| | | | associated with | |
	| | | | the peer's EID. | |		| | | | the peer's EID. | |
	| SHIM_APP_TIMEOUT | o | o | Get or set the | int |		| SHIM_APP_TIMEOUT | o | o | Get or set the | int |
	| | | | timeout value | |		| | | | timeout value | |
	| | | | for detecting | |		| | | | for detecting | |
	| | | | failure. | |		| | | | failure. | |
	| SHIM_PATHEXPLORE | o | o | Get or set | *4 |		| SHIM_PATHEXPLORE | o | o | Get or set | *3 |
	| | | | parameters for | |		| | | | parameters for | |
	| | | | path | |		| | | | path | |
	| | | | exploration and | |		| | | | exploration and | |
	| | | | failure | |		| | | | failure | |
	| | | | detection. | |		| | | | detection. | |
	| SHIM_CONTEXT_DEFERRED_SETUP | o | o | Get or set the | int |		| SHIM_CONTEXT_DEFERRED_SETUP | o | | Get the | int |
	| | | | parameter which | |		| | | | parameter which | |
	| | | | indicates | |		| | | | indicates | |
	| | | | whether | |		| | | | whether | |
	| | | | deferred | |		| | | | deferred | |
	| | | | context setup | |		| | | | context setup | |
	| | | | is supported or | |		| | | | is supported or | |
	| | | | not. | |		| | | | not. | |
	+-----------------------------+-----+-----+-----------------+-------+		+-----------------------------+-----+-----+-----------------+-------+
	Table 1: Socket options for multihoming shim sub-layer		Table 1: Socket options for multihoming shim sub-layer
	*1: Pointer to a shim_locator which is defined in Section 7.		*1: Pointer to a shim_locator which is defined in Section 7.
	*2: Pointer to shim_locator data structure.		*2: Pointer to an array of shim_locator.
	*3: Pointer to an array of shim_locator.
	*4: Pointer to a shim_pathexplore which is defined in Section 7.		*3: Pointer to a shim_pathexplore which is defined in Section 7.
	Figure 2 illustrates how the shim specific socket options fit into		Figure 2 illustrates how the shim specific socket options fit into
	the system model of socket API. The figure shows that the shim sub-		the system model of socket API. The figure shows that the shim sub-
	layer and the additional protocol components (IPv4 and IPv6) below		layer and the additional protocol components (IPv4 and IPv6) below
	the shim sub-layer are new to the system model. As previously		the shim sub-layer are new to the system model. As previously
	mentioned, all the shim specific socket options are defined at the		mentioned, all the shim specific socket options are defined at the
	SOL_SHIM level. This design choice brings the following advantages:		SOL_SHIM level. This design choice brings the following advantages:
	1. The existing sockets API continue to work at the layer above the		1. The existing sockets API continue to work at the layer above the
	shim sub-layer. That is, those legacy API handle IP addresses as		shim sub-layer. That is, those legacy API handle IP addresses as
	skipping to change at page 13, line 47		skipping to change at page 13, line 11
	This option is meaningful when the locator information of the		This option is meaningful when the locator information of the
	received IP packet does not tell whether the identifier/locator		received IP packet does not tell whether the identifier/locator
	adaptation is performed or not. Note that the EID pair and the		adaptation is performed or not. Note that the EID pair and the
	locator pair may be identical in some cases.		locator pair may be identical in some cases.
	This option can be specified by getsockopt(). Thus, the option is		This option can be specified by getsockopt(). Thus, the option is
	read-only and the result (0/1/2) is set in the option value (the		read-only and the result (0/1/2) is set in the option value (the
	fourth argument of getsockopt()).		fourth argument of getsockopt()).
			When the application specifies the socket option to an unconnected
			socket, an error code EOPNOTSUPP is returned to the application.
	The data type of the option value is an integer. The option value		The data type of the option value is an integer. The option value
	indicates the presence of shim context. A return value 1 means that		indicates the presence of shim context. A return value 1 means that
	the socket is associated with a shim context at the shim sub-layer.		the socket is associated with a shim context at the shim sub-layer.
	A return value 0 indicates that there is no shim context associated		A return value 0 indicates that there is no shim context associated
	with the socket. A return value 2 means that it is not known whether		with the socket. A return value 2 means that it is not known whether
	the socket is associated with a shim context or not, and this must be		the socket is associated with a shim context or not, and this must be
	returned only when the socket is unconnected. In other words, the		returned only when the socket is unconnected. In other words, the
	returned value must be 0 or 1 when the socket is connected.		returned value must be 0 or 1 when the socket is connected.
	For example, the option can be used by the application as follows:		For example, the option can be used by the application as follows:
	skipping to change at page 15, line 22		skipping to change at page 14, line 37
	The data type of the option value is an integer.		The data type of the option value is an integer.
	The option value can be set by setsockopt().		The option value can be set by setsockopt().
	The option value can be read by getsockopt().		The option value can be read by getsockopt().
	By default, the value is set to 0, meaning that hot-standby		By default, the value is set to 0, meaning that hot-standby
	connection is disabled.		connection is disabled.
			When the application specifies the socket option to an unconnected
			socket, an error code EOPNOTSUPP is returned to the application.
			When there is no shim context associated with the socket, an error
			code ENOENT is returned to the application.
	For example, an application can request establishment of a hot-		For example, an application can request establishment of a hot-
	standby connection by using the socket option as follows:		standby connection by using the socket option as follows:
	int optval;		int optval;
	optval = 1;		optval = 1;
	setsockopt(fd, SOL_SHIM, SHIM_HOT_STANDBY, &optval,		setsockopt(fd, SOL_SHIM, SHIM_HOT_STANDBY, &optval,
	sizeof(optval));		sizeof(optval));
	For example, an application can get the option value by using the		For example, an application can get the option value by using the
	socket option as follows:		socket option as follows:
	int optval;		int optval;
	int len;		int len;
	len = sizeof(optval);		len = sizeof(optval);
	getsockopt(fd, SOL_SHIM, SHIM_HOT_STANDBY, &optval, &len);		getsockopt(fd, SOL_SHIM, SHIM_HOT_STANDBY, &optval, &len);
	5.4. SHIM_PATHEXPLORE		5.4. SHIM_LOC_LOCAL_PREF
	The application may use this socket option to specify parameters
	concerning path exploration. Path exploration is a procedure to find
	an alternative locator pair to the current locator pair. As the REAP
	specification defines, a peer may send Probe messages to find an
	alternative locator pair.
	The option is effective only when there is a shim context associated
	with the socket.
	The data type of the option value is a pointer to the buffer where a
	set of information for path exploration is stored. The data
	structure is defined in Section 7.
	By default, the option value is set to NULL, meaning that the option
	is disabled.
	An error ENOENT is returned when there is no context associated with		The SHIM_LOC_LOCAL_PREF option is used to get or set preference for a
			source locator for outbound traffic within a given context. This
			option is effective only when there is a shim context associated with
	the socket.		the socket.
	For example, an application can set parameters for path exploration		The preference of a locator is defined by a combination of priority
	by using the socket option as follows.		and weight as per DNS SRV[RFC2782]. Note that the SHIM6 base
			protocol defines preference of locator in the same way.
	struct shim6_pathexplore pe;
	pe.pe_probenum = 4; /* times */
	pe.pe_keepaliveto = 10; /* seconds */
	pe.pe_initprobeto = 500; /* milliseconds */
	pe.pe_reserved = 0;
	setsockopt(fd, SOL_SHIM, SHIM_PATHEXPLORE, &pe, sizeof(pe));
	For example, an application can get parameters for path exploration
	by using the socket option as follows.
	struct shim6_pathexplore pe;
	int len;
	len = sizeof(pe);
	getsockopt(fd, SOL_SHIM, SHIM_PATHEXPLORE, &pe, &len);
	5.5. SHIM_LOC_LOCAL_PREF
	The SHIM_LOC_LOCAL_PREF option is used to get or set preferred
	locator on local side within a given context. Hence this option is
	effective only when there is a shim context associated with the
	socket.
	The data type of the option value is a pointer to a locator		The data type of the option value is a pointer to a locator
	information data structure which is defined in Section 7.		information data structure which is defined in Section 7.
	By default, the option value is set to NULL, meaning that the option		By default, the option value is set to NULL, meaning that the option
	is disabled.		is disabled.
	The preferred locator can be set by setsockopt(). The shim sub-layer		The preferred locator can be set by setsockopt(). The shim sub-layer
	shall verify requested locator before it updating the preferred		shall verify requested locator before it updates the preferred
	locator.		locator.
	An application can get the preferred locator by getsockopt().		An application can get the preferred locator by getsockopt().
	An error ENOENT is returned when there is no context associated with		When the application specifies the socket option to an unconnected
	the socket.		socket, an error code EOPNOTSUPP is returned to the application.
			When there is no shim context associated with the socket, an error
			code ENOENT is returned to the application.
	An error EINVALIDLOCATOR is returned when the validation of the		An error EINVALIDLOCATOR is returned when the validation of the
	specified locator failed.		specified locator fails.
	For example, an application can set the preferred locator by using		For example, an application can set the preferred locator by using
	the socket option as follows. Note that some members of the		the socket option as follows. Note that some members of the
	shim_locator (lc_ifidx and lc_flags) are ignored in the set		shim_locator (lc_ifidx and lc_flags) are ignored in the set
	operation.		operation.
	struct shim_locator lc;		struct shim_locator lc;
	struct in6_addr ip6;		struct in6_addr ip6;
	/* ...set the locator (ip6)... */		/* ...set the locator (ip6)... */
	memset(&lc, 0, sizeof(shim_locator));		memset(&lc, 0, sizeof(shim_locator));
	lc.lc_family = AF_INET6; /* IPv6 */		lc.lc_family = AF_INET6; /* IPv6 */
	lc.lc_ifidx = 0;		lc.lc_ifidx = 0;
	lc.lc_flags = 0;		lc.lc_flags = 0;
	lc.lc_preference = 255;		lc.lc_prio = 1;
	memcpy(lc.lc_addr, &ip6, sizeof(in6_addr));		lc.lc_weight = 10;
			memcpy(&lc.lc_addr, &ip6, sizeof(in6_addr));
	setsockopt(fd, SOL_SHIM, SHIM_LOC_LOCAL_PREF, &lc,		setsockopt(fd, SOL_SHIM, SHIM_LOC_LOCAL_PREF, &lc,
	sizeof(optval));		sizeof(optval));
	For example, an application can get the preferred locator by using		For example, an application can get the preferred locator by using
	the socket option as follows.		the socket option as follows.
	struct shim_locator lc;		struct shim_locator lc;
	int len;		int len;
	len = sizeof(lc);		len = sizeof(lc);
	getsockopt(fd, SOL_SHIM, SHIM_LOC_LOCAL_PREF, &lc, &len);		getsockopt(fd, SOL_SHIM, SHIM_LOC_LOCAL_PREF, &lc, &len);
	5.6. SHIM_LOC_PEER_PREF		5.5. SHIM_LOC_PEER_PREF
	The SHIM_LOC_PEER_PREF option is used to get or set preferred locator		The SHIM_LOC_PEER_PREF option is used to get or set preference of a
	on peer side within a given context. Hence this option is effective		destination locator for outbound traffic within a given context.
	only when there is a shim context associated with the socket.		This option is effective only when there is a shim context associated
			with the socket.
			As defined earlier, the preference of a locator is defined by a
			combination of priority and weight as per DNS SRV[RFC2782]. When
			there are more than one candidate destination locators, the shim sub-
			layer makes selection based on the priority and weight specified for
			each locator.
	The data type of the option value is a pointer to the locator		The data type of the option value is a pointer to the locator
	information data structure which is defined in Section 7.		information data structure which is defined in Section 7.
	By default, the option value is set to NULL, meaning that the option		By default, the option value is set to NULL, meaning that the option
	is disabled.		is disabled.
	The preferred locator can be set by setsockopt(). The shim sub-layer		The preferred locator can be set by setsockopt(). The shim sub-layer
	shall verify requested locator before it updating the preferred		shall verify requested locator before it updating the preferred
	locator.		locator.
	An application can get the preferred locator by getsockopt().		An application can get the preferred locator by getsockopt().
	An error ENOENT is returned when there is no context associated with		When the application specifies the socket option to an unconnected
	the socket.		socket, an error code EOPNOTSUPP is returned to the application.
			When there is no shim context associated with the socket, an error
			code ENOENT is returned to the application.
	An error EINVALIDLOCATOR is returned when the validation of the		An error EINVALIDLOCATOR is returned when the validation of the
	requested locator fails.		requested locator fails.
	The usage of the option is same as that of SHIM_LOC_LOCAL_PREF. Note		The usage of the option is same as that of SHIM_LOC_LOCAL_PREF. Note
	that some members of the shim_locator (lc_ifidx and lc_flags) are		that some members of the shim_locator (lc_ifidx and lc_flags) are
	ignored in the set operation.		ignored in the set operation.
	5.7. SHIM_LOC_LOCAL_RECV		5.6. SHIM_LOC_LOCAL_RECV
	The SHIM_LOC_LOCAL_RECV option can be used to request the shim sub-		The SHIM_LOC_LOCAL_RECV option can be used to request the shim sub-
	layer to store the destination locator of the received IP packet in		layer to store the destination locator of the received IP packet in
	an ancillary data object which can be accessed by recvmsg(). Hence		an ancillary data object which can be accessed by recvmsg(). This
	this option is effective only when there is a shim context associated		option is effective only when there is a shim context associated with
	with the socket.		the socket.
	The data type of the option value is integer. The option value		The data type of the option value is integer. The option value
	should be binary (0 or 1). By default, the option value is set to 0,		should be binary (0 or 1). By default, the option value is set to 0,
	meaning that the option is disabled.		meaning that the option is disabled.
	An application can set the option value by setsockopt().		An application can set the option value by setsockopt().
	An application can get the option value by getsockopt().		An application can get the option value by getsockopt().
	See Section 6 for the procedure to access locator information stored		See Section 6 for the procedure to access locator information stored
	in the ancillary data objects.		in the ancillary data objects.
	An error ENOENT is returned when there is no context associated with		When the application specifies the socket option to an unconnected
	the socket.		socket, an error code EOPNOTSUPP is returned to the application.
			When there is no shim context associated with the socket, an error
			code ENOENT is returned to the application.
	For example, an application can request the shim sub-layer to store		For example, an application can request the shim sub-layer to store
	destination locator by using the socket option as follows.		destination locator by using the socket option as follows.
	int optval;		int optval;
	optval = 1;		optval = 1;
	setsockopt(fd, SOL_SHIM, SHIM_LOC_LOCAL_RECV, &optval,		setsockopt(fd, SOL_SHIM, SHIM_LOC_LOCAL_RECV, &optval,
	sizeof(optval));		sizeof(optval));
	For example, an application can get the option value as follows.		For example, an application can get the option value as follows.
	int optval;		int optval;
	int len;		int len;
	len = sizeof(optval);		len = sizeof(optval);
	getsockopt(fd, SOL_SHIM, SHIM_LOC_LOCAL_RECV, &optval, &len);		getsockopt(fd, SOL_SHIM, SHIM_LOC_LOCAL_RECV, &optval, &len);
	5.8. SHIM_LOC_PEER_RECV		5.7. SHIM_LOC_PEER_RECV
	The SHIM_LOC_PEER_RECV option is used to request the shim sub-layer		The SHIM_LOC_PEER_RECV option is used to request the shim sub-layer
	to store the source locator of the received IP packet in an ancillary		to store the source locator of the received IP packet in an ancillary
	data object which can be accessed by recvmsg(). Hence this option is		data object which can be accessed by recvmsg(). This option is
	effective only when there is a shim context associated with the		effective only when there is a shim context associated with the
	socket.		socket.
	The data type of the option value is integer. The option value		The data type of the option value is integer. The option value
	should be binary (0 or 1). By default, the option value is set to 0,		should be binary (0 or 1). By default, the option value is set to 0,
	meaning that the option is disabled.		meaning that the option is disabled.
	The option value can be set by setsockopt().		The option value can be set by setsockopt().
	The option value can be read by getsockopt().		The option value can be read by getsockopt().
	See Section 6 for the procedure to access locator information stored		See Section 6 for the procedure to access locator information stored
	in the ancillary data objects.		in the ancillary data objects.
	An error ENOENT is returned when there is no context associated with		When the application specifies the socket option to an unconnected
	the socket.		socket, an error code EOPNOTSUPP is returned to the application.
			When there is no shim context associated with the socket, an error
			code ENOENT is returned to the application.
	The usage of the option is same as that of SHIM_LOC_LOCAL_RECV		The usage of the option is same as that of SHIM_LOC_LOCAL_RECV
	option.		option.
	5.9. SHIM_LOC_LOCAL_SEND		5.8. SHIM_LOC_LOCAL_SEND
	The SHIM_LOC_LOCAL_SEND option is used to request the shim sub-layer		The SHIM_LOC_LOCAL_SEND option is used to request the shim sub-layer
	to use a specific locator as the source locator for the IP packets to		to use a specific locator as the source locator for the IP packets to
	be sent from the socket. Hence this option is effective only when		be sent from the socket. This option is effective only when there is
	there is a shim context associated with the socket.		a shim context associated with the socket.
	The data type of option value is pointer to shim_locator data		The data type of option value is pointer to shim_locator data
	structure.		structure.
	An application can set the local locator by setsockopt() providing a		An application can set the local locator by setsockopt() providing a
	valid locator which is stored in a shim_locator data structure. When		valid locator which is stored in a shim_locator data structure. When
	a zero-filled locator is specified, pre-existing setting of local		a zero-filled locator is specified, pre-existing setting of local
	locator is inactivated.		locator is inactivated.
	An application can get the local locator by getsockopt().		An application can get the local locator by getsockopt().
	An error ENOENT is returned when there is no context associated with		When the application specifies the socket option to an unconnected
	the socket.		socket, an error code EOPNOTSUPP is returned to the application.
	An error EINVALIDLOCATOR is returned when invalid locator is		When there is no shim context associated with the socket, an error
			code ENOENT is returned to the application.
			An error EINVALIDLOCATOR is returned when an invalid locator is
	specified.		specified.
	For example, an application can request the shim sub-layer to use a		For example, an application can request the shim sub-layer to use a
	specific local locator by using the socket option as follows.		specific local locator by using the socket option as follows.
	struct shim_locator locator;		struct shim_locator locator;
	struct in6_addr ia6;		struct in6_addr ia6;
	/* an IPv6 address preferred for the source locator is copied		/* an IPv6 address preferred for the source locator is copied
	to the parameter ia6 */		to the parameter ia6 */
	memset(&locator, 0, sizeof(locator));		memset(&locator, 0, sizeof(locator));
	/* fill shim_locator data structure */		/* fill shim_locator data structure */
	locator.lc_family = AF_INET6;		locator.lc_family = AF_INET6;
	locator.lc_ifidx = 1;		locator.lc_ifidx = 1;
	locator.lc_flags = 0;		locator.lc_flags = 0;
	locator.lc_preference = 0;		locator.lc_prio = 0;
			locator.lc_weight = 0;
	memcpy(&locator.lc_addr, &ia6, sizeof(ia6));		memcpy(&locator.lc_addr, &ia6, sizeof(ia6));
	setsockopt(fd, SOL_SHIM, SHIM_LOC_LOCAL_SEND, &locator,		setsockopt(fd, SOL_SHIM, SHIM_LOC_LOCAL_SEND, &locator,
	sizeof(locator));		sizeof(locator));
	For example, an application can get the preferred local locator by		For example, an application can get the preferred local locator by
	using the socket option as follows.		using the socket option as follows.
	struct shim_locator locator;		struct shim_locator locator;
	memset(&locator, 0, sizeof(locator));		memset(&locator, 0, sizeof(locator));
	getsockopt(fd, SOL_SHIM, SHIM_LOC_LOCAL_SEND, &locator,		getsockopt(fd, SOL_SHIM, SHIM_LOC_LOCAL_SEND, &locator,
	sizeof(locator));		sizeof(locator));
	/* check locator */		/* check locator */
	5.10. SHIM_LOC_PEER_SEND		5.9. SHIM_LOC_PEER_SEND
	The SHIM_LOC_PEER_SEND option is used to request the shim sub-layer		The SHIM_LOC_PEER_SEND option is used to request the shim sub-layer
	to use a specific locator for the destination locator of IP packets		to use a specific locator for the destination locator of IP packets
	to be sent from the socket. Hence this option is effective only when		to be sent from the socket. This option is effective only when there
	there is a shim context associated with the socket.		is a shim context associated with the socket.
	The data type of the option value is a pointer to shim_locator data		The data type of the option value is a pointer to shim_locator data
	structure.		structure.
	An application can set the remote locator by setsockopt() providing a		An application can set the remote locator by setsockopt() providing a
	valid locator which is stored in a shim_locator data structure. When		valid locator which is stored in a shim_locator data structure. When
	a zero-filled locator is specified, pre-existing setting of remote		a zero-filled locator is specified, pre-existing setting of remote
	locator is inactivated.		locator is inactivated.
	An application can get the specified remote locator by getsockopt().		An application can get the specified remote locator by getsockopt().
	An error ENOENT is returned when there is no context associated with		When the application specifies the socket option to an unconnected
	the socket.		socket, an error code EOPNOTSUPP is returned to the application.
	An error EINVALIDLOCATOR when invalid locator is specified.		When there is no shim context associated with the socket, an error
			code ENOENT is returned to the application.
	The usage of the option is as the same as that of SHIM_LOC_LOCAL_SEND		An error EINVALIDLOCATOR when invalid an locator is specified.
			The usage of the option is the same as that of SHIM_LOC_LOCAL_SEND
	option.		option.
	5.11. SHIM_LOCLIST_LOCAL		5.10. SHIM_LOCLIST_LOCAL
	The SHIM_LOCLIST_LOCAL option is used to get or set the locator list		The SHIM_LOCLIST_LOCAL option is used to get or set the locator list
	associated with the local EID of the shim context associated with the		associated with the local EID of the shim context associated with the
	socket. Hence this option is effective only when there is a shim		socket. This option is effective only when there is a shim context
	context associated with the socket.		associated with the socket.
	The data type of the option value is a pointer to the buffer in which		The data type of the option value is a pointer to the buffer in which
	a locator list is stored. See Section 7 for the data structure for		a locator list is stored. See Section 7 for the data structure for
	storing the locator information. By default, the option value is set		storing the locator information. By default, the option value is set
	to NULL, meaning that the option is disabled.		to NULL, meaning that the option is disabled.
	An application can get the locator list by getsockopt(). Note that		An application can get the locator list by getsockopt(). Note that
	the size of the buffer pointed by optval argument should be large		the size of the buffer pointed to by the optval argument should be
	enough to store an array of locator information. The number of the		large enough to store an array of locator information. The number of
	locator information is not known beforehand.		the locator information is not known beforehand.
	The local locator list can be set by setsockopt(). The buffer		The local locator list can be set by setsockopt(). The buffer
	pointed by optval argument should contain an array of locator list.		pointed to by the optval argument should contain an array of locator
			structures.
	An error ENOENT is returned when there is no context associated with		When the application specifies the socket option to an unconnected
	the socket.		socket, an error code EOPNOTSUPP is returned to the application.
	An error EINVALIDLOCATOR is returned when the validation of the		When there is no shim context associated with the socket, an error
	specified locator failed.		code ENOENT is returned to the application.
			An error EINVALIDLOCATOR is returned when the validation of any of
			the specified locators failed.
	An error ETOOMANYLOCATORS is returned when the number of locators		An error ETOOMANYLOCATORS is returned when the number of locators
	specified exceeds the limit (SHIM_MAX_LOCATORS).		specified exceeds the limit (SHIM_MAX_LOCATORS), or when the size of
			the buffer provided by the application is not large enough to store
			the locator list provided by the shim sub-layer.
	For example, an application can set a list of locators to be		For example, an application can set a list of locators to be
	associated with the local EID by using the socket option as follows:		associated with the local EID by using the socket option as follows:
	struct shim_locator locators[SHIM_MAX_LOCATORS];		struct shim_locator locators[SHIM_MAX_LOCATORS];
	struct sockaddr_in *sin;		struct sockaddr_in *sin;
	struct sockaddr_in6 *sin6;		struct sockaddr_in6 *sin6;
	memset(locators, 0, sizeof(locators));		memset(locators, 0, sizeof(locators));
	...		...
	/* obtain local IP addresses from local interfaces */		/* obtain local IP addresses from local interfaces */
	...		...
	/* first locator (an IPv6 address) */		/* first locator (an IPv6 address) */
	locators[0].lc_family = AF_INET6;		locators[0].lc_family = AF_INET6;
	locators[0].lc_ifidx = 0;		locators[0].lc_ifidx = 0;
	locators[0].lc_flags = 0;		locators[0].lc_flags = 0;
	locators[0].lc_preference = 1;		locators[0].lc_prio = 1;
			locators[0].lc_weight = 0;
	memcpy(&locators[0].lc_addr, &sa6->sin6_addr,		memcpy(&locators[0].lc_addr, &sa6->sin6_addr,
	sizeof(sa6->sin6_addr));		sizeof(sa6->sin6_addr));
	...		...
	/* second locator (an IPv4 address) */		/* second locator (an IPv4 address) */
	locators[1].lc_family = AF_INET;		locators[1].lc_family = AF_INET;
	locators[1].lc_ifidx = 0;		locators[1].lc_ifidx = 0;
	locators[1].lc_flags = 0;		locators[1].lc_flags = 0;
	locators[1].lc_preference = 0;		locators[1].lc_prio = 0;
			locators[1].lc_weight = 0;
	memcpy(&locators[1].lc_addr, &sa->sin_addr,		memcpy(&locators[1].lc_addr, &sa->sin_addr,
	sizeof(sa->sin_addr));		sizeof(sa->sin_addr));
	setsockopt(fd, SOL_SHIM, SHIM_LOCLIST_LOCAL, locators,		setsockopt(fd, SOL_SHIM, SHIM_LOCLIST_LOCAL, locators,
	sizeof(locators));		sizeof(locators));
	For example, an application can get a list of locators that are		For example, an application can get a list of locators that are
	associated with the local EID by using the socket option as follows.		associated with the local EID by using the socket option as follows.
	struct shim_locator locators[SHIM_MAX_LOCATORS];		struct shim_locator locators[SHIM_MAX_LOCATORS];
	memset(locators, 0, sizeof(locators));		memset(locators, 0, sizeof(locators));
	getsockopt(fd, SOL_SHIM, SHIM_LOC_LOCAL_RECV, locators,		getsockopt(fd, SOL_SHIM, SHIM_LOC_LOCAL_RECV, locators,
	sizeof(locators));		sizeof(locators));
	/* parse locators */		/* parse locators */
	...		...
	5.12. SHIM_LOCLIST_PEER		5.11. SHIM_LOCLIST_PEER
	The SHIM_LOCLIST_PEER option is used to get or set the locator list		The SHIM_LOCLIST_PEER option is used to get or set the locator list
	associated with the peer EID of the shim context associated with the		associated with the peer EID of the shim context associated with the
	socket. Hence this option is effective only when there is a shim		socket. This option is effective only when there is a shim context
	context associated with the socket.		associated with the socket.
	The data type of the option value is a pointer to the buffer where a		The data type of the option value is a pointer to the buffer where a
	locator list is stored. See Section 7 for the data structure for		locator list is stored. See Section 7 for the data structure for
	storing the locator information. By default, the option value is set		storing the locator information. By default, the option value is set
	to NULL, meaning that the option is disabled.		to NULL, meaning that the option is disabled.
	An application can get the locator list by getsockopt(). Note that		An application can get the locator list by getsockopt(). Note that
	the size of the buffer pointed by optval argument should be large		the size of the buffer pointed to by the optval argument should be
	enough to store an array of locator information. The number of the		large enough to store an array of locator information. The number of
	locator information is not known beforehand.		the locator information is not known beforehand.
	An application can set the locator list by setsockopt(). The buffer		An application can set the locator list by setsockopt(). The buffer
	pointed by optval argument should contain an array of locator list.		pointed to by the optval argument should contain an array of locator
			list.
	An error ENOENT is returned when there is no context associated with		When the application specifies the socket option to an unconnected
	the socket.		socket, an error code EOPNOTSUPP is returned to the application.
	An error EINVALIDLOCATOR is returned when the validation of the		When there is no shim context associated with the socket, an error
	specified locator failed.		code ENOENT is returned to the application.
			An error EINVALIDLOCATOR is returned when the validation of any of
			the specified locators failed.
	An error ETOOMANYLOCATORS is returned when the number of locators		An error ETOOMANYLOCATORS is returned when the number of locators
	specified exceeds the limit (SHIM_MAX_LOCATORS).		specified exceeds the limit (SHIM_MAX_LOCATORS), or when the size of
			the buffer provided by the application is not large enough to store
			the locator list provided by the shim sub-layer.
	The usage of the option is same as that of SHIM_LOCLIST_LOCAL.		The usage of the option is same as that of SHIM_LOCLIST_LOCAL.
	5.13. SHIM_APP_TIMEOUT		5.12. SHIM_APP_TIMEOUT
	The SHIM_APP_TIMEOUT option is used to get or set the timeout value		The SHIM_APP_TIMEOUT option is used to get or set the Send Timeout
	for application to detect failure. Hence this option is effective		value of the REAP protocol. This option is effective only when there
	only when there is a shim context associated with the socket.		is a shim context associated with the socket.
	The data type of the option value is an integer. The value indicates		The data type of the option value is an integer. The value indicates
	the period of timeout in seconds to send a REAP Keepalive message		the period of timeout in seconds to send a REAP Keepalive message
	since the last outbound traffic. By default, the option value is set		since the last outbound traffic. By default, the option value is set
	to 0, meaning that the option is disabled. When the option is		to 0, meaning that the option is disabled. When the option is
	disabled, the REAP mechanism follows its default value of Send		disabled, the REAP mechanism follows its default value of Send
	Timeout value as specified in [RFC5534]		Timeout value as specified in [RFC5534]
	If the timeout value specified is longer than the Send Timeout		When the application specifies the socket option to an unconnected
	configured in the REAP component, the REAP Keepalive message should		socket, an error code EOPNOTSUPP is returned to the application.
	be suppressed.
	An error ENOENT is returned when there is no context associated with		When there is no shim context associated with the socket, an error
	the socket.		code ENOENT is returned to the application.
	For example, an application can set the timeout value by using the		For example, an application can set the timeout value by using the
	socket option as follows.		socket option as follows.
	int optval;		int optval;
	optval = 15; /* 15 seconds */		optval = 15; /* 15 seconds */
	setsockopt(fd, SOL_SHIM, SHIM_APP_TIMEOUT, &optval,		setsockopt(fd, SOL_SHIM, SHIM_APP_TIMEOUT, &optval,
	sizeof(optval));		sizeof(optval));
	skipping to change at page 24, line 39		skipping to change at page 24, line 32
	For example, an application can get the timeout value by using the		For example, an application can get the timeout value by using the
	socket option as follows.		socket option as follows.
	int optval;		int optval;
	int len;		int len;
	len = sizeof(optval);		len = sizeof(optval);
	getsockopt(fd, SOL_SHIM, SHIM_APP_TIMEOUT, &optval, &len);		getsockopt(fd, SOL_SHIM, SHIM_APP_TIMEOUT, &optval, &len);
			5.13. SHIM_PATHEXPLORE
			The application may use this socket option to get or set parameters
			concerning path exploration. Path exploration is a procedure to find
			an alternative locator pair to the current locator pair. As the REAP
			specification defines, a peer may send Probe messages to find an
			alternative locator pair.
			This option is effective only when there is a shim context associated
			with the socket.
			The data type of the option value is a pointer to the buffer where a
			set of information for path exploration is stored. The data
			structure is defined in Section 7.
			By default, the option value is set to NULL, meaning that the option
			is disabled.
			When the application specifies the socket option to an unconnected
			socket, an error code EOPNOTSUPP is returned to the application.
			When there is no shim context associated with the socket, an error
			code ENOENT is returned to the application.
			For example, an application can set parameters for path exploration
			by using the socket option as follows.
			struct shim6_pathexplore pe;
			pe.pe_probenum = 4; /* times */
			pe.pe_keepaliveto = 10; /* seconds */
			pe.pe_initprobeto = 500; /* milliseconds */
			pe.pe_reserved = 0;
			setsockopt(fd, SOL_SHIM, SHIM_PATHEXPLORE, &pe, sizeof(pe));
			For example, an application can get parameters for path exploration
			by using the socket option as follows.
			struct shim6_pathexplore pe;
			int len;
			len = sizeof(pe);
			getsockopt(fd, SOL_SHIM, SHIM_PATHEXPLORE, &pe, &len);
	5.14. SHIM_DEFERRED_CONTEXT_SETUP		5.14. SHIM_DEFERRED_CONTEXT_SETUP
	The SHIM_DEFERRED_CONTEXT_SETUP option is used to specify whether to		The SHIM_DEFERRED_CONTEXT_SETUP option is used to check whether
	enable deferred context setup or not. Deferred context setup means		deferred context setup is possible or not. Deferred context setup
	that the context is established in parallel with the data		means that the context is established in parallel with the data
	communication. Note that SHIM6 supports deferred context setup and		communication. Note that SHIM6 supports deferred context setup and
	HIP does not because EIDs in HIP (i.e., Host Identifiers) are non-		HIP does not because EIDs in HIP (i.e., Host Identifiers) are non-
	routable.		routable.
	The data type for the option value is an integer. The option value		The data type for the option value is an integer. The option value
	should be binary (0 or 1). By default, the value is set to 1,		should be binary (0 or 1). The option value 1 means that the shim
	meaning that the context setup is deferred. In order to disable the		sub-layer supports deferred context setup.
	option, the application should call setsockopt() with option value
	set to 0.
	Note that HIP does not support deferred context setup, by default.
	When the application requests to enable deferred context setup in
	case of HIP, it may mean that the application allows the system to
	start TCP handshake even when there is no IPsec security association
	with the peer. Such a usage of the SHIM_DEFERRED_CONTEXT_SETUP
	option should be considered as experimental and left for further
	study.
	For example, an application can disable the deferred context setup by
	using the socket option as follows:
	int optval;
	optval = 0;
	setsockopt(fd, SOL_SHIM, SHIM_DEFERRED_CONTEXT_SETUP,		When the application specifies the socket option to an unconnected
	&optval, sizeof(optval));		socket, an error code EOPNOTSUPP is returned to the application.
	For example, an application can get the option value as follows.		For example, an application can check whether deferred context setup
			is possible or not as follows:
	int optval;		int optval;
	int len;		int len;
	len = sizeof(optval);		len = sizeof(optval);
	getsockopt(fd, SOL_SHIM, SHIM_DEFERRED_CONTEXT_SETUP,		getsockopt(fd, SOL_SHIM, SHIM_DEFERRED_CONTEXT_SETUP,
	&optval, &len);		&optval, &len);
	5.15. Applicability		5.15. Applicability
	All the socket options for the shim sub-layer except for		All the socket options defined in this section except for the
	SHIM_HOT_STANDBY are applicable to both connected and unconnected		SHIM_DONTSHIM option are applicable to applications that use
	sockets. SHIM_HOT_STANDBY socket option is applicable only to		connected sockets.
	connected sockets. This is because the shim sub-layer cannot
	initiate context establishment to create a hot standby connection		All the socket options defined in this section except for the
	when the peer's IP address is not known until the application writes		SHIM_ASSOCIATED, SHIM_DONTSHIM and SHIM_CONTEXT_DEFERRED_SETUP
	data to the unconnected socket.		options are effective only when there is a shim context associated
			with the socket.
	5.16. Error Handling		5.16. Error Handling
	If successful, getsockopt() and setsockopt() return 0; otherwise, the		If successful, getsockopt() and setsockopt() return 0; otherwise, the
	functions return -1 and set errno to indicate an error.		functions return -1 and set errno to indicate an error.
	The following are new error values defined for some shim specific		The following are new error values defined for some shim specific
	socket options indicating that the getsockopt() or setsockopt()		socket options indicating that the getsockopt() or setsockopt()
	finished incompletely:		finished incompletely:
	skipping to change at page 27, line 28		skipping to change at page 28, line 5
	padding if necessary		padding if necessary
	6.1. Get Locator from Incoming Packet		6.1. Get Locator from Incoming Packet
	An application can get locator information from the received IP		An application can get locator information from the received IP
	packet by specifying the shim specific socket options for the socket.		packet by specifying the shim specific socket options for the socket.
	When SHIM_LOC_LOCAL_RECV and/or SHIM_LOC_PEER_RECV socket options are		When SHIM_LOC_LOCAL_RECV and/or SHIM_LOC_PEER_RECV socket options are
	set, the application can retrieve local and/or remote locator from		set, the application can retrieve local and/or remote locator from
	the ancillary data.		the ancillary data.
			When there is no shim context associated with the socket, the shim
			sub-layer MUST return zero-filled locator information to the
			application.
	6.2. Set Locator for Outgoing Packet		6.2. Set Locator for Outgoing Packet
	An application can specify the locators to be used for transmitting		An application can specify the locators to be used for transmitting
	an IP packet by sendmsg(). When the ancillary data of cmsg_type		an IP packet by sendmsg(). When the ancillary data of cmsg_type
	SHIM_LOC_LOCAL_SEND and/or SHIM_LOC_PEER_SEND are specified, the		SHIM_LOC_LOCAL_SEND and/or SHIM_LOC_PEER_SEND are specified, the
	application can explicitly specify the source and/or the destination		application can explicitly specify the source and/or the destination
	locators to be used for the communication over the socket.		locators to be used for the communication over the socket. If the
			specified locator pair is verified, the shim sub-layer overrides the
	Note that the effect is limited to the datagram transmitted by the		locator(s) of the outgoing IP packet. Note that the effect is
	sendmsg().		limited to the datagram transmitted by the sendmsg().
	If the specified locator pair is verified, the shim sub-layer		When there is no shim context associated with the socket, an error
	overrides the locators of the IP packet.		code ENOENT is returned to the application.
	An error EINVALIDLOCATOR is returned when validation of the specified		An error code EINVALIDLOCATOR is returned when validation of the
	locator failed.		specified locator fails.
	6.3. Notification from Application to Multihoming Shim Sub-layer		6.3. Notification from Application to Multihoming Shim Sub-layer
	An application may provide feedbacks to the shim sub-layer about the		An application may provide feedbacks to the shim sub-layer about the
	communication status. Such feedbacks are particularly useful for the		communication status. Such feedbacks are particularly useful for the
	shim sub-layer in the absence of REAP mechanism to monitor the		shim sub-layer in the absence of REAP mechanism to monitor the
	reachability status of the currently used locator pair in a given		reachability status of the currently used locator pair in a given
	shim context.		shim context.
	The notification can be made by sendmsg() specifying a new ancillary		The notification can be made by sendmsg() specifying a new ancillary
	data called SHIM_FEEDBACK. The ancillary data can be handled by		data called SHIM_FEEDBACK. The ancillary data can be handled by
	specifying SHIM_FEEDBACK option in cmsg_type.		specifying SHIM_FEEDBACK option in cmsg_type.
	An error ENOENT is returned when there is no context associated with		When there is no shim context associated with the socket, an error
	the socket.		code ENOENT is returned to the application.
	See Section 7.3 for details of the data structure to be used.		See Section 7.3 for details of the data structure to be used.
	It is outside the scope of this document how the shim sub-layer would		It is outside the scope of this document how the shim sub-layer would
	react when a feedback is provided by an application.		react when a feedback is provided by an application.
	6.4. Notification from Multihoming Shim Sub-layer to Application		6.4. Applicability
	The shim sub-layer MAY provide notification about a locator change
	within a multihome shim context to applications that have concern
	with the context. Such a notification may be useful, for example,
	for an application which is sensitive to the characteristics of the
	current path. A locator change is caused when either of local or
	peer's locator (or both) is changed. Note that locators discussed
	here are the ones that appear in the IP packet header, and not the
	ones that are included in the locator list. A locator change may
	take place asynchronously.
	The notification is handled as an out-of-band data by the
	application.
	1. Application calls the select() system call by setting non-NULL
	value for the fourth argument.
	2. When there is a notification, the application reads out-of-band
	data from the socket by calling recvmsg().
	3. The application checks the flag in the msghdr (msg_flags) to see
	if there is any notification about locator change delivered. If
	the MSG_SHIM_LOCATOR_CHANGE flag is set, application parses the
	chain of control message to read a pair of ancillary data objects
	which contains the source locator and the destination locator.
	Note that the direction of locator change is distinguished by the
	value of cmsg_type; SHIM_LOC_*_RECV is used for inbound locator
	change, and SHIM_LOC_*_SEND is used for outbound locator change.
	There is no restriction in terms of applicability of the notification
	about locator change. The notification can be delivered to any type
	of socket (connected or unconnected, stream-oriented or datagram-
	oriented).
	6.5. Applicability
	All the ancillary data for the shim sub-layer is applicable to both		All the ancillary data for the shim sub-layer is applicable to
	connected and unconnected sockets.		connected sockets.
	A care is needed when the SHIM_LOC_*_RECV socket option is used for		Care is needed when the SHIM_LOC_*_RECV socket option is used for
	stream-oriented sockets (e.g., TCP sockets) because there is no one-		stream-oriented sockets (e.g., TCP sockets) because there is no one-
	to-one mapping between a single send or receive operation and the		to-one mapping between a single send or receive operation and the
	data (e.g., a TCP segment) being received. In other words, there is		data (e.g., a TCP segment) being received. In other words, there is
	no gurantee that the locator(s) set in the SHIM_LOC_*_RECV ancillary		no gurantee that the locator(s) set in the SHIM_LOC_*_RECV ancillary
	data is identical to the locator(s) that appear in the IP packets		data is identical to the locator(s) that appear in the IP packets
	received. The shim sub-layer SHOULD provide the latest locator		received. The shim sub-layer SHOULD provide the latest locator
	information to the application in response to the SHIM_LOC_*_RECV		information to the application in response to the SHIM_LOC_*_RECV
	socket option.		socket option.
	7. Data Structures		7. Data Structures
	This section data structures for the shim sub-layer. These data		This section data structures for the shim sub-layer. These data
	structures are either used as a parameter for setsockopt() or		structures are either used as a parameter for setsockopt() or
	getsockopt() (as mentioned in Section 5) or as a parameter for		getsockopt() (as mentioned in Section 5) or as a parameter for
	ancillary data to be processed by sendmsg() or recvmsg() (as		ancillary data to be processed by sendmsg() or recvmsg() (as
	mentioned in Section 6).		mentioned in Section 6).
	7.1. Placeholder for Locator Information		7.1. Placeholder for Locator Information
	As defined in Section 5, the SHIM_LOC_LOCAL_PREF, SHIM_LOC_PEER_PREF,		As defined in Section 5, the SHIM_LOC_*_PREF, SHIM_LOC_*_SEND, and
	SHIM_LOCLIST_LOCAL, and SHIM_LOCLIST_PEER socket options need to		SHIM_LOCLIST_* socket options need to handle one or more locator
	handle one or more locator information. Locator information includes		information. Locator information includes not only the locator
	not only the locator itself but also additional information about the		itself but also additional information about the locator which is
	locator which is useful for locator management. A new data structure		useful for locator management. A new data structure is defined to
	is defined to serve as a placeholder for the locator information.		serve as a placeholder for the locator information.
	Figure 4 illustrates the data structure called shim_locator which		Figure 4 illustrates the data structure called shim_locator which
	stores a locator information.		stores a locator information.
	struct shim_locator {		struct shim_locator {
	uint8_t lc_family; /* address family */		uint8_t lc_family; /* address family */
	uint8_t lc_proto; /* protocol */		uint8_t lc_proto; /* protocol */
	uint16_t lc_port; /* port number */		uint16_t lc_port; /* port number */
	uint16_t lc_flags; /* flags */		uint16_t lc_prio; /* preference value */
	uint16_t lc_pref; /* preference value */		uint16_t lc_weight; /* weight */
	uint32_t lc_ifidx; /* interface index */		uint32_t lc_ifidx; /* interface index */
	struct in6_addr lc_addr; /* address */		struct in6_addr lc_addr; /* address */
			uint16_t lc_flags; /* flags */
	};		};
	Figure 4: shim locator structure		Figure 4: shim locator structure
	lc_family		lc_family
	Address family of the locator (e.g. AF_INET, AF_INET6). It is		Address family of the locator (e.g. AF_INET, AF_INET6). It is
	required that the parameter contains non-zero value indicating the		required that the parameter contains non-zero value indicating the
	exact address family of the locator.		exact address family of the locator.
	lc_proto		lc_proto
	Internet Protocol number for the protocol which is used to handle		Internet Protocol number for the protocol which is used to handle
	locator behind NAT. Typically, this value is set as UDP (17) when		locator behind NAT. Typically, this value is set as UDP (17) when
	the locator is a UDP encapsulation interface.		the locator is a UDP encapsulation interface.
	lc_port		lc_port
	Port number which is used for handling locator behind NAT.		Port number which is used for handling locator behind NAT.
	lc_flags		lc_prio
	Each bit of the flags represents a specific characteristics of the		The priority of the locator. The range is 0-65535. The lowest
	locator. Hash Based Address (HBA) is defined as 0x01.		priority value means the highest priority.
	Cryptographically Generated Address (CGA) is defined as 0x02.		lc_weight
	lc_pref		The weight value indicates a relative weight for locators with the
	Preference of the locator. The preference is represented by an		same priority value. The range is 0-65535.
	integer.
	lc_ifidx		lc_ifidx
	Interface index of the network interface to which the locator is		Interface index of the network interface to which the locator is
	assigned. This field should be valid only in a read		assigned. This field should be valid only in a read
	(getsockopt()) operation.		(getsockopt()) operation.
	lc_addr		lc_addr
	Contains the locator. In the case where a locator whose size is		Contains the locator. In the case where a locator whose size is
	smaller than 16 bytes, an encoding rule should be provided for		smaller than 16 bytes, an encoding rule should be provided for
	each locator of a given address family. For instance, in case of		each locator of a given address family. For instance, in case of
	AF_INET (IPv4), the locator should be in the format of an IPv4-		AF_INET (IPv4), the locator should be in the format of an IPv4-
	mapped IPv6 address as defined in [RFC4291].		mapped IPv6 address as defined in [RFC4291].
			lc_flags
			Each bit of the flags represents a specific characteristics of the
			locator. Hash Based Address (HBA) is defined as 0x01.
			Cryptographically Generated Address (CGA) is defined as 0x02.
	7.1.1. Handling Locator behind NAT		7.1.1. Handling Locator behind NAT
	Note that the locator information MAY contain a locator behind a		Note that the locator information MAY contain a locator behind a
	Network Address Translator (NAT). Such a situation may arise when		Network Address Translator (NAT). Such a situation may arise when
	the host is behind the NAT and uses a local address as a source		the host is behind the NAT and uses a local address as a source
	locator to communicate with the peer. Note that a NAT traversal		locator to communicate with the peer. Note that a NAT traversal
	mechanism for HIP is defined, which allows HIP host to tunnel control		mechanism for HIP is defined, which allows HIP host to tunnel control
	and data traffic over UDP[I-D.ietf-hip-nat-traversal]. Note also		and data traffic over UDP[I-D.ietf-hip-nat-traversal]. Note also
	that the locator behind NAT is not necessarily an IPv4 address but it		that the locator behind NAT is not necessarily an IPv4 address but it
	skipping to change at page 31, line 18		skipping to change at page 31, line 18
	/* copy the private IPv4 address to the ia6 as an IPv4-mapped		/* copy the private IPv4 address to the ia6 as an IPv4-mapped
	IPv6 address */		IPv6 address */
	memset(&locator, 0, sizeof(locator));		memset(&locator, 0, sizeof(locator));
	/* fill shim_locator data structure */		/* fill shim_locator data structure */
	locator.lc_family = AF_INET;		locator.lc_family = AF_INET;
	locator.lc_proto = IPPROTO_UDP;		locator.lc_proto = IPPROTO_UDP;
	locator.lc_port = 50500;		locator.lc_port = 50500;
	locator.lc_flags = 0;		locator.lc_flags = 0;
	locator.lc_pref = 0;		locator.lc_prio = 0;
			locator.lc_weight = 0;
	locator.lc_ifidx = 3;		locator.lc_ifidx = 3;
	memcpy(&locator.lc_addr, &ia6, sizeof(ia6));		memcpy(&locator.lc_addr, &ia6, sizeof(ia6));
	setsockopt(fd, SOL_SHIM, SHIM_LOC_LOCAL_SEND, &locator,		setsockopt(fd, SOL_SHIM, SHIM_LOC_LOCAL_SEND, &locator,
	sizeof(locator));		sizeof(locator));
	Figure 5: Handling locator behind NAT		Figure 5: Handling locator behind NAT
	7.2. Path Exploration Parameter		7.2. Path Exploration Parameter
	skipping to change at page 33, line 12		skipping to change at page 33, line 12
	unidirectional reachability between the locator pair in		unidirectional reachability between the locator pair in
	question.		question.
	* 3: Satisfactory. There is satisfactory unidirectional		* 3: Satisfactory. There is satisfactory unidirectional
	reachability between the locator pair in question.		reachability between the locator pair in question.
	reserved		reserved
	Reserved field. Must be ignored by the receiver.		Reserved field. Must be ignored by the receiver.
	8. System Requirements		8. System Requirements
	This section gives system requirements posed by the sockets API		As addressed in Section 5, most of the socket options and ancillary
	defined in this document. There exist requirements for the system		data defined in this document are applicable to connected sockets.
	(kernel) to maintain the association between sockets and shim		It is assumed that the kernel is capable of maintaining the
	contexts.		association between a connected socket and a shim context. This
			requirement is considered to be reasonable because a pair of source
	As addressed in Section 5, all the socket options and ancillary data		and destination IP addresses is bound to a connected socket.
	defined in this document except for the SHIM_HOT_STANDBY socket
	option are applicable to both connected and unconnected sockets.
	There are less system requirements to enable support for applications
	that use connected sockets. This is because the kernel can maintain
	the association between a connected socket and a shim context in a
	static manner because a connected socket is bound to a source and
	destination IP addresses (identifiers). The kernel should be able to
	identify shim context associated with a connected socket by searching
	shim context keyed by the pair of source and destination identifiers.
	However, this is not the case for unnconnected sockets. The kernel
	needs to dynamically resolve association between an unconnected
	socket and a shim context, if any, upon packet processing. As to
	outbound packet processing, the kernel needs to check if there is any
	shim context whose EID pair matches with the source and destination
	IP addresses of the user data originating from an unconnected socket.
	If a matching context is found, the shim sub-layer performs packet
	processing taking the application's preference into account. Note
	that the shim sub-layer should be able to backtrack the socket from
	which the user data was originated. As to inbound packet processing,
	the shim sub-layer needs to check not only the IP header but also the
	transport layer protocol header to resolve the destination socket.
	If the destination socket is resolved and it contains any values
	concerning the shim sub-layer socket options, the shim sub-layer
	processes the IP packet as requested (e.g., set locator information
	of received packet in the ancillary data).
	9. Relation to Existing Sockets API Extensions		9. Relation to Existing Sockets API Extensions
	This section explains relation between the sockets API defined in		This section explains relation between the sockets API defined in
	this document and the existing sockets API extensions.		this document and the existing sockets API extensions.
	As mentioned in Section 5, the basic assumption is that the existing		As mentioned in Section 5, the basic assumption is that the existing
	sockets API continues to work above the shim sub-layer. This means		sockets API continues to work above the shim sub-layer. This means
	that, the existing sockets API deals with identifiers, and the		that, the existing sockets API deals with identifiers, and the
	sockets API defined in this document deals with locators.		sockets API defined in this document deals with locators.
	SHIM_LOC_LOCAL_PREF and SHIM_LOC_PEER_PREF socket options are		SHIM_LOC_LOCAL_SEND and SHIM_LOC_PEER_SEND socket options are
	semantically similar to the IPV6_PKTINFO socket API in the sense that		semantically similar to the IPV6_PKTINFO socket API in the sense that
	both provide a means for application to set the source IP address of		both provide a means for application to set the source IP address of
	outbound IP packets.		outbound IP packets.
	SHIM_LOC_LOCAL_RECV and SHIM_LOC_PEER_RECV socket options are		SHIM_LOC_LOCAL_RECV and SHIM_LOC_PEER_RECV socket options are
	semantically similar to the IP_RECVDSTADDR and IPV6_PKTINFO socket		semantically similar to the IP_RECVDSTADDR and IPV6_PKTINFO socket
	APIs in the sense that both provides a means for application to get		APIs in the sense that both provides a means for application to get
	the source and/or destination IP address of inbound IP packets.		the source and/or destination IP address of inbound IP packets.
	getsockname() and getpeername() enable application to get 'name' of		getsockname() and getpeername() enable application to get 'name' of
	skipping to change at page 34, line 48		skipping to change at page 34, line 24
	Socket options defined in Section 5 may cause conflicting situation		Socket options defined in Section 5 may cause conflicting situation
	when the target context is shared by multiple applications. In such		when the target context is shared by multiple applications. In such
	a case, the socket handler should inform the shim sub-layer that		a case, the socket handler should inform the shim sub-layer that
	context forking is required. In SHIM6, when a context is forked, an		context forking is required. In SHIM6, when a context is forked, an
	unique identifier called Forked Instance Identifier (FII) is assigned		unique identifier called Forked Instance Identifier (FII) is assigned
	to the newly forked context. The forked context is then exclusively		to the newly forked context. The forked context is then exclusively
	associated with the socket through which non-default preference value		associated with the socket through which non-default preference value
	was specified. The forked context is maintained by the shim sub-		was specified. The forked context is maintained by the shim sub-
	layer during the lifetime of associated socket instance. When the		layer during the lifetime of associated socket instance. When the
	socket is closed, the shim sub-layer SHOULD delete associated		socket is closed, the shim sub-layer SHOULD delete associated
	context. When a forked context is torn down, the SHIM6
	implementation should notify the peer about the deletion of forked
	context.		context.
			When the application specifies SHIM_LOC_*_SEND specifying a different
			source or destination locator which does not have the highest
			priority and weight specified by the SHIM_LOC_*_PREF, the shim sub-
			layer SHOULD supersede the request made by SHIM_LOC_*_SEND over the
			preference specified by SHIM_LOC_*_PREF.
			When the peer provides preferences of the locators (e.g., a SHIM6
			peer may send a locator with a Locator Preferences Option) which
			conflict with preference specified by the applications either by
			SHIM_LOC_PEER_SEND or SHIM_LOC_PEER_PREF, the shim sub-layer SHOULD
			supersede the preference made by the application over the preference
			specified by the peer.
	10.2. Incompatiblility between IPv4 and IPv6		10.2. Incompatiblility between IPv4 and IPv6
	The shim sub-layer performs identifier/locator adaptation.		The shim sub-layer performs identifier/locator adaptation.
	Therefore, in some cases, the whole IP header can be replaced with		Therefore, in some cases, the whole IP header can be replaced with
	new IP header of a different address family (e.g. conversion from		new IP header of a different address family (e.g. conversion from
	IPv4 to IPv6 or vice versa). Hence, there is an issue how to make		IPv4 to IPv6 or vice versa). Hence, there is an issue how to make
	the conversion with minimum impact. Note that this issue is common		the conversion with minimum impact. Note that this issue is common
	in other protocol conversion such as SIIT[RFC2765].		in other protocol conversion techniques
			[RFC2765][I-D.ietf-behave-v6v4-xlate].
	As addressed in the SIIT specification, some of the features (IPv6		As studied in the previous works on protocol
	routing headers, hop-by-hop extension headers, or destination		conversion[RFC2765][I-D.ietf-behave-v6v4-xlate], some of the features
			(IPv6 routing headers, hop-by-hop extension headers, and destination
	headers) from IPv6 are not convertible to IPv4. In addition, notion		headers) from IPv6 are not convertible to IPv4. In addition, notion
	of source routing is not exactly the same in IPv4 and IPv6. This		of source routing is not exactly the same in IPv4 and IPv6. This
	means that an error may occur during the conversion of identifier and		means that an error may occur during the conversion of identifier and
	locator. It is ffs exactly how the shim sub-layer should behave in		locator. It is ffs exactly how the shim sub-layer should behave in
	such erroneous cases.		such erroneous cases.
	11. IANA Considerations		11. IANA Considerations
	This document contains no IANA consideration.		This document contains no IANA consideration.
	skipping to change at page 36, line 12		skipping to change at page 35, line 45
	any of the local interface. If not, the shim sub-layer MUST reject		any of the local interface. If not, the shim sub-layer MUST reject
	the request and return an error message with the EINVALIDLOCATOR code		the request and return an error message with the EINVALIDLOCATOR code
	to the application. If the locator is confirmed to be available, the		to the application. If the locator is confirmed to be available, the
	shim sub-layer SHOULD initiate the procedure to update the locator		shim sub-layer SHOULD initiate the procedure to update the locator
	list.		list.
	Use of the following socket options and ancillary data may require		Use of the following socket options and ancillary data may require
	treatment of unknown source locator:		treatment of unknown source locator:
	o SHIM_LOC_LOCAL_SEND		o SHIM_LOC_LOCAL_SEND
	o SHIM_LOC_LOCAL_PREF		o SHIM_LOC_LOCAL_PREF
	o SHIM_LOC_LIST_LOCAL		o SHIM_LOCLIST_LOCAL
	13.1.2. Treatment of Unknown Destination Locator		13.1.2. Treatment of Unknown Destination Locator
	If the shim sub-layer turns out to be SHIM6, the SHIM6 implementation		If the shim sub-layer turns out to be SHIM6, the SHIM6 implementation
	MUST reject the request for using unknown destination locator.		MUST reject the request for using unknown destination locator.
	If the shim sub-layer turns out to be HIP, the HIP implementation MAY		If the shim sub-layer turns out to be HIP, the HIP implementation MAY
	accept the request for using unknown destination locator.		accept the request for using unknown destination locator.
	Use of the following socket options and ancillary data may require		Use of the following socket options and ancillary data may require
	treatment of unknown destination locator:		treatment of unknown destination locator:
	o SHIM_LOC_PEER_SEND		o SHIM_LOC_PEER_SEND
	o SHIM_LOC_PEER_PREF		o SHIM_LOC_PEER_PREF
	o SHIM_LOC_LIST_PEER		o SHIM_LOCLIST_PEER
	14. Changes		14. Changes
	14.1. Changes from version 00 to version 01		14.1. Changes from version 00 to version 01
	o Define shim_locator{} data type which is a placeholder for		o Define shim_locator{} data type which is a placeholder for
	locator.		locator.
	o Define shim_pathexplore{} data type in which a set of REAP		o Define shim_pathexplore{} data type in which a set of REAP
	parameters are stored.		parameters are stored.
	o Remove descriptions about "stickiness" of socket options.		o Remove descriptions about "stickiness" of socket options.
	skipping to change at page 38, line 14		skipping to change at page 38, line 4
	14.11. Changes from version 10 to version 11		14.11. Changes from version 10 to version 11
	o Added short descriptions about connected sockets and unconnected		o Added short descriptions about connected sockets and unconnected
	sockets.		sockets.
	o Relaxed applicability of the socket options.		o Relaxed applicability of the socket options.
	o Relaxed applicability of the ancillary data.		o Relaxed applicability of the ancillary data.
	o Added notification about locator change.		o Added notification about locator change.
	14.12. Changes from version 11 to version 12		14.12. Changes from version 11 to version 12
			o Reflected comments from Brian Karpenter.
			o Reflected comments from Michael Scharf.
	o Reflected comments from Brian Karpenter		14.13. Changes from version 12 to version 13
	o Reflected comments from Michael Scharf
			o Reflected comments from Sebastien Barre.
			o Removed the description about the notification from the shim sub-
			layer to applications.
			o Narrowed down the scope of the applicability of the socket options
			and the ancillary data.
	15. Acknowledgments		15. Acknowledgments
	Authors would like to thank Jari Arkko who participated in the		Authors would like to thank Jari Arkko who participated in the
	discussion that lead to the first version of this document, and		discussion that lead to the first version of this document, and
	Tatuya Jinmei who thoroughly reviewed the early version of this draft		Tatuya Jinmei who thoroughly reviewed the early version of this draft
	and provided detailed comments on sockets API related issues. Thomas		and provided detailed comments on sockets API related issues. Thomas
	Henderson provided valuable comments especially from HIP		Henderson provided valuable comments especially from HIP
	perspectives.		perspectives.
	Authors sincerely thank to the following people for their help to		Authors sincerely thank to the following people for their helpful
	improve this document: Samu Varjonen and Dmitriy Kuptsov.		comments to the document: Samu Varjonen, Dmitriy Kuptsov, Brian
			Carpenter, Michael Scharf, and Sebastien Barre
	16. References		16. References
	16.1. Normative References		16.1. Normative References
	[POSIX] "IEEE Std. 1003.1-2001 Standard for Information Technology		[POSIX] "IEEE Std. 1003.1-2001 Standard for Information Technology
	-- Portable Operating System Interface (POSIX). Open group		-- Portable Operating System Interface (POSIX). Open group
	Technical Standard: Base Specifications, Issue 6,		Technical Standard: Base Specifications, Issue 6,
	http://www.opengroup.org/austin", December 2001.		http://www.opengroup.org/austin", December 2001.
	skipping to change at page 39, line 8		skipping to change at page 39, line 7
	[RFC5533] Bagnulo, M. and E. Nordmark, "Level 3 multihoming shim		[RFC5533] Bagnulo, M. and E. Nordmark, "Level 3 multihoming shim
	protocol", RFC 5533, June 2009.		protocol", RFC 5533, June 2009.
	[RFC5534] Arkko, J. and I. Beijnum, "Failure Detection and Locator		[RFC5534] Arkko, J. and I. Beijnum, "Failure Detection and Locator
	Pair Exploration Protocol for IPv6 Multihoming", RFC 5534,		Pair Exploration Protocol for IPv6 Multihoming", RFC 5534,
	June 2009.		June 2009.
	16.2. Informative References		16.2. Informative References
			[I-D.ietf-behave-v6v4-xlate]
			Li, X., Bao, C., and F. Baker, "IP/ICMP Translation
			Algorithm", draft-ietf-behave-v6v4-xlate-05 (work in
			progress), December 2009.
	[I-D.ietf-hip-nat-traversal]		[I-D.ietf-hip-nat-traversal]
	Komu, M., Henderson, T., Tschofenig, H., Melen, J., and A.		Komu, M., Henderson, T., Tschofenig, H., Melen, J., and A.
	Keranen, "Basic HIP Extensions for Traversal of Network		Keranen, "Basic HIP Extensions for Traversal of Network
	Address Translators", Internet		Address Translators", Internet
	Draft draft-ietf-hip-nat-traversal-09, October 2009.		Draft draft-ietf-hip-nat-traversal-09, October 2009.
	[I-D.ietf-shim6-app-refer]		[I-D.ietf-shim6-app-refer]
	Nordmark, E., "Shim6 Application Referral Issues",		Nordmark, E., "Shim6 Application Referral Issues",
	draft-ietf-shim6-app-refer-00 (work in progress),		draft-ietf-shim6-app-refer-00 (work in progress),
	July 2005.		July 2005.
	[I-D.ietf-shim6-applicability]		[I-D.ietf-shim6-applicability]
	Abley, J., Bagnulo, M., and A. Garcia-Martinez,		Abley, J., Bagnulo, M., and A. Garcia-Martinez,
	"Applicability Statement for the Level 3 Multihoming Shim		"Applicability Statement for the Level 3 Multihoming Shim
	Protocol (Shim6)", draft-ietf-shim6-applicability-04 (work		Protocol (Shim6)", draft-ietf-shim6-applicability-04 (work
	in progress), November 2009.		in progress), November 2009.
	[RFC2765] Nordmark, E., "Stateless IP/ICMP Translation Algorithm		[RFC2765] Nordmark, E., "Stateless IP/ICMP Translation Algorithm
	(SIIT)", RFC 2765, February 2000.		(SIIT)", RFC 2765, February 2000.
			[RFC2782] Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for
			specifying the location of services (DNS SRV)", RFC 2782,
			February 2000.
	[RFC3972] Aura, T., "Cryptographically Generated Addresses (CGA)",		[RFC3972] Aura, T., "Cryptographically Generated Addresses (CGA)",
	RFC 3972, March 2005.		RFC 3972, March 2005.
	[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing		[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
	Architecture", RFC 4291, February 2006.		Architecture", RFC 4291, February 2006.
	[RFC5535] Bagnulo, M., "Hash Based Addresses (HBA)", RFC 5535,		[RFC5535] Bagnulo, M., "Hash Based Addresses (HBA)", RFC 5535,
	June 2009.		June 2009.
	Appendix A. Context Forking		Appendix A. Context Forking
End of changes. 106 change blocks.
	324 lines changed or deleted		343 lines changed or added
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