draft-ietf-shim6-multihome-shim-api-14.txt   draft-ietf-shim6-multihome-shim-api-15.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: February 20, 2011 UC3M Expires: May 3, 2011 UC3M
K. Slavov K. Slavov
S. Sugimoto, Ed. S. Sugimoto, Ed.
Ericsson Ericsson
August 19, 2010 October 30, 2010
Socket Application Program Interface (API) for Multihoming Shim Socket Application Program Interface (API) for Multihoming Shim
draft-ietf-shim6-multihome-shim-api-14 draft-ietf-shim6-multihome-shim-api-15
Abstract Abstract
This document specifies sockets API extensions for the multihoming This document specifies sockets API extensions for the multihoming
shim layer. The API aims to enable interactions between applications shim layer. The API aims to enable interactions between applications
and the multihoming shim layer for advanced locator management, and and the multihoming shim layer for advanced locator management, and
access to information about failure detection and path exploration. access to information about failure detection and path exploration.
This document is based on an assumption that a multihomed host is This document is based on an assumption that a multihomed host is
equipped with a conceptual sub-layer (hereafter "shim") inside the IP equipped with a conceptual sub-layer (hereafter "shim") inside the IP
layer that maintains mappings between identifiers and locators. layer that maintains mappings between identifiers and locators.
Examples of the shim are SHIM6 and HIP. 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 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
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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.
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Table of Contents This document may contain material from IETF Documents or IETF
Contributions published or made publicly available before November
10, 2008. The person(s) controlling the copyright in some of this
material may not have granted the IETF Trust the right to allow
modifications of such material outside the IETF Standards Process.
Without obtaining an adequate license from the person(s) controlling
the copyright in such materials, this document may not be modified
outside the IETF Standards Process, and derivative works of it may
not be created outside the IETF Standards Process, except to format
it for publication as an RFC or to translate it into languages other
than English.
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 Table of Contents
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. System Overview . . . . . . . . . . . . . . . . . . . . . . . 6
4. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 7
5. Socket Options for Multihoming Shim Sub-layer . . . . . . . . 9
5.1. SHIM_ASSOCIATED . . . . . . . . . . . . . . . . . . . . . 12
5.2. SHIM_DONTSHIM . . . . . . . . . . . . . . . . . . . . . . 13
5.3. SHIM_HOT_STANDBY . . . . . . . . . . . . . . . . . . . . 14
5.4. SHIM_LOC_LOCAL_PREF . . . . . . . . . . . . . . . . . . . 15
5.5. SHIM_LOC_PEER_PREF . . . . . . . . . . . . . . . . . . . 16
5.6. SHIM_LOC_LOCAL_RECV . . . . . . . . . . . . . . . . . . . 17
5.7. SHIM_LOC_PEER_RECV . . . . . . . . . . . . . . . . . . . 18
5.8. SHIM_LOC_LOCAL_SEND . . . . . . . . . . . . . . . . . . . 18
5.9. SHIM_LOC_PEER_SEND . . . . . . . . . . . . . . . . . . . 20
5.10. SHIM_LOCLIST_LOCAL . . . . . . . . . . . . . . . . . . . 20
5.11. SHIM_LOCLIST_PEER . . . . . . . . . . . . . . . . . . . . 23
5.12. SHIM_APP_TIMEOUT . . . . . . . . . . . . . . . . . . . . 23
5.13. SHIM_PATHEXPLORE . . . . . . . . . . . . . . . . . . . . 24
5.14. SHIM_DEFERRED_CONTEXT_SETUP . . . . . . . . . . . . . . . 25
5.15. Applicability . . . . . . . . . . . . . . . . . . . . . . 26
5.16. Error Handling . . . . . . . . . . . . . . . . . . . . . 26
6. Ancillary Data for Multihoming Shim Sub-layer . . . . . . . . 26
6.1. Get Locator from Incoming Packet . . . . . . . . . . . . 27
6.2. Set Locator for Outgoing Packet . . . . . . . . . . . . . 28
6.3. Notification from Application to Multihoming Shim
Sub-layer . . . . . . . . . . . . . . . . . . . . . . . . 28
6.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 28
7. Data Structures . . . . . . . . . . . . . . . . . . . . . . . 29
7.1. Placeholder for Locator Information . . . . . . . . . . . 29
7.1.1. Handling Locator behind NAT . . . . . . . . . . . . . 30
7.2. Path Exploration Parameter . . . . . . . . . . . . . . . 31 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5
7.3. Feedback Information . . . . . . . . . . . . . . . . . . 32 2. Requirements Language . . . . . . . . . . . . . . . . . . . . 6
8. System Requirements . . . . . . . . . . . . . . . . . . . . . 33 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6
9. Relation to Existing Sockets API Extensions . . . . . . . . . 33 4. System Overview . . . . . . . . . . . . . . . . . . . . . . . 8
10. Operational Considerations . . . . . . . . . . . . . . . . . . 33 5. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 9
10.1. Conflict Resolution . . . . . . . . . . . . . . . . . . . 34 6. Socket Options for Multihoming Shim Sub-layer . . . . . . . . 10
10.2. Incompatiblility between IPv4 and IPv6 . . . . . . . . . 34 6.1. SHIM_ASSOCIATED . . . . . . . . . . . . . . . . . . . . . 14
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 35 6.2. SHIM_DONTSHIM . . . . . . . . . . . . . . . . . . . . . . 15
12. Protocol Constants and Variables . . . . . . . . . . . . . . . 35 6.3. SHIM_HOT_STANDBY . . . . . . . . . . . . . . . . . . . . 16
13. Security Considerations . . . . . . . . . . . . . . . . . . . 35 6.4. SHIM_LOC_LOCAL_PREF . . . . . . . . . . . . . . . . . . . 17
13.1. Treatment of Unknown Locator . . . . . . . . . . . . . . 35 6.5. SHIM_LOC_PEER_PREF . . . . . . . . . . . . . . . . . . . 18
13.1.1. Treatment of Unknown Source Locator . . . . . . . . . 35 6.6. SHIM_LOC_LOCAL_RECV . . . . . . . . . . . . . . . . . . . 19
13.1.2. Treatment of Unknown Destination Locator . . . . . . . 36 6.7. SHIM_LOC_PEER_RECV . . . . . . . . . . . . . . . . . . . 20
14. Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 6.8. SHIM_LOC_LOCAL_SEND . . . . . . . . . . . . . . . . . . . 20
14.1. Changes from version 00 to version 01 . . . . . . . . . . 36 6.9. SHIM_LOC_PEER_SEND . . . . . . . . . . . . . . . . . . . 22
14.2. Changes from version 01 to version 02 . . . . . . . . . . 36 6.10. SHIM_LOCLIST_LOCAL . . . . . . . . . . . . . . . . . . . 23
14.3. Changes from version 02 to version 03 . . . . . . . . . . 36 6.11. SHIM_LOCLIST_PEER . . . . . . . . . . . . . . . . . . . . 25
14.4. Changes from version 03 to version 04 . . . . . . . . . . 36 6.12. SHIM_APP_TIMEOUT . . . . . . . . . . . . . . . . . . . . 25
14.5. Changes from version 04 to version 05 . . . . . . . . . . 37 6.13. SHIM_PATHEXPLORE . . . . . . . . . . . . . . . . . . . . 26
14.6. Changes from version 05 to version 06 . . . . . . . . . . 37 6.14. SHIM_DEFERRED_CONTEXT_SETUP . . . . . . . . . . . . . . . 27
14.7. Changes from version 06 to version 07 . . . . . . . . . . 37 6.15. Applicability . . . . . . . . . . . . . . . . . . . . . . 28
14.8. Changes from version 07 to version 08 . . . . . . . . . . 37 6.16. Error Handling . . . . . . . . . . . . . . . . . . . . . 28
14.9. Changes from version 08 to version 09 . . . . . . . . . . 37 7. Ancillary Data for Multihoming Shim Sub-layer . . . . . . . . 28
14.10. Changes from version 09 to version 10 . . . . . . . . . . 37 7.1. Get Locator from Incoming Packet . . . . . . . . . . . . 30
14.11. Changes from version 10 to version 11 . . . . . . . . . . 37 7.2. Set Locator for Outgoing Packet . . . . . . . . . . . . . 30
14.12. Changes from version 11 to version 12 . . . . . . . . . . 37 7.3. Notification from Application to Multihoming Shim
14.13. Changes from version 12 to version 13 . . . . . . . . . . 38 Sub-layer . . . . . . . . . . . . . . . . . . . . . . . . 30
14.14. Changes from version 13 to version 14 . . . . . . . . . . 38 7.4. Applicability . . . . . . . . . . . . . . . . . . . . . . 31
15. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 38 8. Data Structures . . . . . . . . . . . . . . . . . . . . . . . 31
16. References . . . . . . . . . . . . . . . . . . . . . . . . . . 38 8.1. Placeholder for Locator Information . . . . . . . . . . . 31
16.1. Normative References . . . . . . . . . . . . . . . . . . 38 8.1.1. Handling Locator behind NAT . . . . . . . . . . . . . 33
16.2. Informative References . . . . . . . . . . . . . . . . . 39 8.2. Path Exploration Parameter . . . . . . . . . . . . . . . 33
Appendix A. Context Forking . . . . . . . . . . . . . . . . . . . 40 8.3. Feedback Information . . . . . . . . . . . . . . . . . . 34
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 41 9. System Requirements . . . . . . . . . . . . . . . . . . . . . 35
10. Relation to Existing Sockets API Extensions . . . . . . . . . 35
11. Operational Considerations . . . . . . . . . . . . . . . . . . 36
11.1. Conflict Resolution . . . . . . . . . . . . . . . . . . . 36
11.2. Incompatibility between IPv4 and IPv6 . . . . . . . . . . 37
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 37
13. Protocol Constants and Variables . . . . . . . . . . . . . . . 37
14. Security Considerations . . . . . . . . . . . . . . . . . . . 37
14.1. Treatment of Unknown Locator . . . . . . . . . . . . . . 37
14.1.1. Treatment of Unknown Source Locator . . . . . . . . . 38
14.1.2. Treatment of Unknown Destination Locator . . . . . . . 38
15. Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
15.1. Changes from version 00 to version 01 . . . . . . . . . . 38
15.2. Changes from version 01 to version 02 . . . . . . . . . . 39
15.3. Changes from version 02 to version 03 . . . . . . . . . . 39
15.4. Changes from version 03 to version 04 . . . . . . . . . . 39
15.5. Changes from version 04 to version 05 . . . . . . . . . . 39
15.6. Changes from version 05 to version 06 . . . . . . . . . . 39
15.7. Changes from version 06 to version 07 . . . . . . . . . . 39
15.8. Changes from version 07 to version 08 . . . . . . . . . . 39
15.9. Changes from version 08 to version 09 . . . . . . . . . . 39
15.10. Changes from version 09 to version 10 . . . . . . . . . . 40
15.11. Changes from version 10 to version 11 . . . . . . . . . . 40
15.12. Changes from version 11 to version 12 . . . . . . . . . . 40
15.13. Changes from version 12 to version 13 . . . . . . . . . . 40
15.14. Changes from version 13 to version 14 . . . . . . . . . . 40
15.15. Changes from version 14 to version 15 . . . . . . . . . . 40
16. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 40
17. References . . . . . . . . . . . . . . . . . . . . . . . . . . 41
17.1. Normative References . . . . . . . . . . . . . . . . . . 41
17.2. Informative References . . . . . . . . . . . . . . . . . 41
Appendix A. Context Forking . . . . . . . . . . . . . . . . . . . 42
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 44
1. Introduction 1. Introduction
This document defines socket API extensions by which upper layer This document defines socket API extensions by which upper layer
protocols may be informed about and control the way in which a protocols may be informed about and control the way in which a
multihoming shim sub-layer in the IP layer manages the dynamic choice multihoming shim sub-layer in the IP layer manages the dynamic choice
of locators. Initially it applies to SHIM6 and HIP, but it is of locators. Initially it applies to SHIM6 and HIP, but it is
defined generically. defined generically.
The role of the multihoming shim sub-layer (hereafter called "shim The role of the multihoming shim sub-layer (hereafter called "shim
sub-layer" in this document) is to avoid impacts to upper layer sub-layer" in this document) is to avoid impacts to upper layer
protocols which may be caused when the endhost changes its attachment protocols which may be caused when the endhost changes its attachment
point to the Internet, for instance, in the case of rehoming event point to the Internet, for instance, in the case of rehoming event
under the multihomed environment. The key design of the shim sub- under the multihomed environment. There is, however, a need for API
layer is to treat identifier and locator separately. Identifiers are in the cases where 1) the upper layer protocol is particularly
presented to upper layer protocols and used as communication sensitive to impacts, or 2) the upper layer protocol wants to benefit
endpoints. Locators represent toplogical location of endhosts and from better knowledge of what is going on underneath.
are used to route packet from the source to the destiantion. The
shim sub-layer maintains mapping of identifiers and locators.
Note that the shim sub-layer may conflict with other multihoming There are various kinds of technologies that aim to solve the same
mechanisms such as SCTP and multipath issue, the multihoming issue. Note that there will be conflict when
TCP[I-D.ietf-shim6-applicability]. To avoid any conflict, only one more than one shim sub-layer is active at the same time. The
of SHIM6 and HIP should be in use. assumption made in this document is that there is only a single shim
sub-layer (HIP or SHIM6) activated on the system.
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 in the Posix standard [POSIX]. The API specifies how to
ancillary data (aka cmsg) to access the locator information with use 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 signed 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.
The target readers of this document are application programmers who The target readers of this document are application programmers who
develop application software which may benefit greatly from develop application software which may benefit greatly from
multihomed environments. In addition, this document aims to provide multihomed environments. In addition, this document aims to provide
necessary information for developers of shim protocols to implement necessary information for developers of shim protocols to implement
API for enabling advanced locator management. API for enabling advanced locator management.
2. Terminology 2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
3. Terminology
This section provides terminology used in this document. Basically This section provides terminology used in this document. Basically
most of the terms used in this document are taken from the following most of the terms used in this document are taken from the following
documents: documents:
o SHIM6 Protocol Specification[RFC5533] o SHIM6 Protocol Specification[RFC5533]
o HIP Architecture[RFC4423] o HIP Architecture[RFC4423]
o Reachability Protocol (REAP)[RFC5534] o Reachability Protocol (REAP)[RFC5534]
In this document, the term "IP" refers to both IPv4 and IPv6, unless In this document, the term "IP" refers to both IPv4 and IPv6, unless
the protocol version is specifically mentioned. The following are the protocol version is specifically mentioned. The following are
definitions of terms frequently used in this document: definitions of terms frequently used in this document:
o Endpoint identifier (EID) - The identifier used by the application o Endpoint identifier (EID) - The identifier used by the application
to specify the endpoint of a given communication. Applications to specify the endpoint of a given communication. Applications
may handle EIDs in various ways such as long-lived connections, may handle EIDs in various ways such as long-lived connections,
callbacks, and referrals[I-D.ietf-shim6-app-refer]. callbacks, and referrals[I-D.ietf-shim6-app-refer].
* In the case of SHIM6, an identifier called a ULID serves as an * In the case of SHIM6, an identifier called a ULID (Upper Layer
EID. A ULID is chosen from locators available on the host. Identifier) serves as an EID. A ULID is chosen from locators
available on the host.
* In the case of HIP, an identifier called a Host Identifier * In the case of HIP, an identifier called a Host Identifier
serves as an EID. A Host Identifier is derived from the public serves as an EID. A Host Identifier is derived from the public
key of a given host. For the sake of backward compatibility key of a given host. For the sake of backward compatibility
with the sockets API, the Host Identifier is represented in a with the sockets API, the Host Identifier is represented in a
form of hash of public key. form of hash of public key.
* Note that the EID appears in the standard socket API as an * Note that the EID appears in the standard socket API as an
address, and does not appear in the extensions defined in this address, and does not appear in the extensions defined in this
document, which only concern locators. document, which only concern locators.
o Locator - The IP address actually used to deliver IP packets. o Locator - The IP address actually used to deliver IP packets.
Locators are present in the source and destination fields of the Locators are present in the source and destination fields of the
IP header of a packet on the wire. IP header of a packet on the wire. Locator discussed in this
document could be either an IPv4 address or an IPv6 address. Note
that HIP can handle both IPv4 and IPv6 locators, whereas SHIM6 can
handle only IPv6 locators. For the HIP case, locator can be a
private IPv4 address when the host is behind a NAT. Section
Section 8.1.1 gives detailed description about handling of locator
behind NAT.
* List of locators - A list of locators associated with an EID. * List of locators - A list of locators associated with an EID.
There are two lists of locators stored in a given context. One There are two lists of locators stored in a given context. One
is associated with the local EID and the other is associated is associated with the local EID and the other is associated
with the remote EID. As defined in [RFC5533], the list of with the remote EID. As defined in [RFC5533], the list of
locators associated with an EID 'A' is denoted as Ls(A). locators associated with an EID 'A' is denoted as Ls(A).
* Preferred locator - The (source/destination) locator currently * Preferred locator - The (source/destination) locator currently
used to send packets within a given context. As defined in used to send packets within a given context.
[RFC5533], the preferred locator of a host 'A' is denoted as
Lp(A).
* Unknown locator - Any locator that does not appear in the * Unknown locator - Any locator that does not appear in the
locator list of the shim context associated with the socket. locator list of the shim context associated with the socket.
When there is no shim context associated with the socket, any When there is no shim context associated with the socket, any
source and/or destination locator requested by the application source and/or destination locator requested by the application
is considered to be unknown locator. is considered to be unknown locator.
* Valid locator - A valid locator means that the locator is
considered to be valid in the security sense. More
specifically, the validity indicates whether the locator is
part of a HBA set.
* Verified locator - A verified locator means that the locator is
considered to be reachable according to the result of REAP
return routability check. Note that the verification applies
only to peer's locator.
o Shim - The conceptual sub-layer inside the IP layer which o Shim - The conceptual sub-layer inside the IP layer which
maintains mappings between EIDs and locators. An EID can be maintains mappings between EIDs and locators. An EID can be
associated with more than one locator at a time when the host is associated with more than one locator at a time when the host is
multihomed. The term 'shim' does not refer to a specific protocol multihomed. The term 'shim' does not refer to a specific protocol
but refers to the conceptual sub-layer inside the IP layer. but refers to the conceptual sub-layer inside the IP layer.
o Identifier/locator adaptation - The adaptation performed at the o Identifier/locator adaptation - The adaptation performed at the
shim sub-layer which may end up re-writing the source and/or shim sub-layer which may end up re-writing the source and/or
destination addresses of an IP packet. In the outbound packet destination addresses of an IP packet. In the outbound packet
processing, the EID pair is converted to the associated locator processing, the EID pair is converted to the associated locator
pair. In the inbound packet processing, the locator pair is pair. In the inbound packet processing, the locator pair is
skipping to change at page 6, line 38 skipping to change at page 8, line 10
"working" if the packet can safely travel from the source to the "working" if the packet can safely travel from the source to the
destination where the packet contains the first address from the destination where the packet contains the first address from the
pair as the source address and the second address from the pair as pair as the source address and the second address from the pair as
the destination address. If reachability is confirmed in both the destination address. If reachability is confirmed in both
directions, the address pair is considered to be working bi- directions, the address pair is considered to be working bi-
directionally. directionally.
o Reachability protocol (REAP) - The protocol for detecting failure o Reachability protocol (REAP) - The protocol for detecting failure
and exploring reachability in a multihomed environment. REAP is and exploring reachability in a multihomed environment. REAP is
defined in [RFC5534]. defined in [RFC5534].
3. System Overview 4. System Overview
Figure 1 illustrates the system overview. The shim sub-layer and Figure 1 illustrates the system overview. The shim sub-layer and
REAP component exist inside the IP layer. Applications use the REAP component exist inside the IP layer. Applications use the
sockets API defined in this document to interface with the shim sub- sockets API defined in this document to interface with the shim sub-
layer and the transport layer for locator management, failure layer and the transport layer for locator management, failure
detection, and path exploration. detection, and path exploration.
It may also be possible that the shim sub-layer interacts with the It may also be possible that the shim sub-layer interacts with the
transport layer, however, such an interaction is outside the scope of transport layer, however, such an interaction is outside the scope of
this document. this document.
skipping to change at page 7, line 29 skipping to change at page 9, line 5
| +-----------------------------+ +----------+ | | +-----------------------------+ +----------+ |
| ^ ^ | | ^ ^ |
+-----------------------|----------------------|----------+ +-----------------------|----------------------|----------+
v v v v
+------------------------------------------+ +------------------------------------------+
| Link Layer | | Link Layer |
+------------------------------------------+ +------------------------------------------+
Figure 1: System overview Figure 1: System overview
4. Requirements 5. Requirements
The following is a list of requirements from applications: The following is a list of requirements from applications:
o Turn on/off shim. An application should be able to request to o Turn on/off shim. An application should be able to request to
turn on or turn off the multihoming support by the shim layer: turn on or turn off the multihoming support by the shim layer:
* Apply shim. The application should be able to explicitly * Apply shim. The application should be able to explicitly
request the shim sub-layer to apply multihoming support. request the shim sub-layer to apply multihoming support.
* Don't apply shim. The application should be able to request * Don't apply shim. The application should be able to request
the shim sub-layer not to apply the multihoming support but to the shim sub-layer not to apply the multihoming support but to
apply normal IP processing at the IP layer. apply normal IP processing at the IP layer.
* Note that this function is also required by other types of * Note that this function is also required by other types of
multihoming mechanisms such as SCTP and multipath TCP to avoid multihoming mechanisms such as SCTP and multipath TCP to avoid
potential conflict with the shim sub-layer. potential conflict with the shim sub-layer.
o Locator management. o Locator management.
* It should be possible to set preferred source and/or * It should be possible to set preferred source and/or
destination locator within a given context: Lp(local) and/or destination locator within a given context.
Lp(remote).
* It should be possible to get preferred source and/or * It should be possible to get preferred source and/or
destination locator within a given context: Lp(local) and/or destination locator within a given context.
Lp(remote).
* It should be possible to set a list of source and/or * It should be possible to set a list of source and/or
destination locators within a given context: Ls(local) and destination locators within a given context: Ls(local) and
Ls(remote). Ls(remote).
* It should be possible to get a list of source and/or * It should be possible to get a list of source and/or
destination locators within a given context: Ls(local) and destination locators within a given context: Ls(local) and
Ls(remote). Ls(remote).
o Notification from applications to the shim sub-layer about the o Notification from applications to the shim sub-layer about the
status of the communication. The notification occurs in an event- status of the communication. The notification occurs in an event-
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 feedback or negative feedback to the shim sub-
layer. Note that these feedbacks are mentioned in [RFC5534]: layer. Note that these feedback 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 feedback 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 feedback 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. The REAP module may be triggered by these negative the peer. The REAP module may be triggered by these negative
feedbacks and invoke the path exploration procedure. feedback 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 4 skipping to change at page 10, line 22
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 know if the shim-sublayer supports o Applications should be able to know if the shim-sublayer supports
deferred context setup or not. deferred context setup or not.
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 6. 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.
Table 1 shows a list of the socket options that are specific to the Table 1 shows a list of the socket options that are specific to the
shim sub-layer. An application may use these socket options for a shim sub-layer. All of these socket options are defined at the level
given socket either by the getsockopt() system call or by the SOL_SHIM. When an application uses one of the socket options by
setsockopt() system call. All of these socket options are defined at getsockopt() or setsockopt(), the second argument must be set as
level SOL_SHIM. SOL_SHIM.
The first column of Table 1 gives the name of the option. The second The first column of Table 1 gives the name of the option. The second
and third columns indicate whether the option can be handled by the and third columns indicate whether the option can be handled by the
getsockopt() system call and/or by the setsockopt() system call. The getsockopt() system call and/or by the setsockopt() system call. The
fourth column provides a brief description of the socket option. The fourth column provides a brief description of the socket option. The
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 (0 or | |
| | | | 1) which | |
| | | | indicates | | | | | | indicates | |
| | | | whether the | | | | | | whether the | |
| | | | socket is | | | | | | socket is | |
| | | | associated with | | | | | | associated (1) | |
| | | | any shim | | | | | | with any shim | |
| | | | context or not. | | | | | | context or not | |
| | | | (0). | |
| 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 | |
| | | | support by the | | | | | | support by the | |
| | | | shim sub-layer | | | | | | shim sub-layer | |
| | | | or not. | | | | | | or not. | |
| SHIM_HOT_STANDBY | o | o | Get or set the | int | | SHIM_HOT_STANDBY | o | o | Get or set the | int |
| | | | parameter to | | | | | | parameter to | |
| | | | request the | | | | | | request the | |
| | | | shim sub-layer | | | | | | shim sub-layer | |
| | | | to prepare a | | | | | | to prepare a | |
| | | | hot-standby | | | | | | hot-standby | |
| | | | connection. | | | | | | connection. | |
| SHIM_LOC_LOCAL_PREF | o | o | Get or set the | *1 | | SHIM_LOC_LOCAL_PREF | o | o | Get or set the | Note |
| | | | preferred | | | | | | preferred | 1 |
| | | | locator on the | | | | | | locator on the | |
| | | | local side for | | | | | | local side for | |
| | | | the context | | | | | | the context | |
| | | | associated with | | | | | | associated with | |
| | | | the socket. | | | | | | the socket. | |
| SHIM_LOC_PEER_PREF | o | o | Get or set the | *1 | | SHIM_LOC_PEER_PREF | o | o | Get or set the | Note |
| | | | preferred | | | | | | preferred | 1 |
| | | | locator on the | | | | | | locator on the | |
| | | | remote side for | | | | | | remote side for | |
| | | | the context | | | | | | the context | |
| | | | associated with | | | | | | associated with | |
| | | | the socket. | | | | | | the socket. | |
| SHIM_LOC_LOCAL_RECV | o | o | Get or set the | int | | SHIM_LOC_LOCAL_RECV | o | o | Request the | int |
| | | | parameter which | |
| | | | is used to | |
| | | | request the | |
| | | | shim sub-layer | | | | | | shim sub-layer | |
| | | | to store the | | | | | | to store the | |
| | | | destination | | | | | | destination | |
| | | | locator of the | | | | | | locator of the | |
| | | | received IP | | | | | | received IP | |
| | | | packet. | | | | | | packet in an | |
| SHIM_LOC_PEER_RECV | o | o | Get or set the | int | | | | | ancillary data | |
| | | | parameter which | | | | | | object. | |
| | | | is used to | | | SHIM_LOC_PEER_RECV | o | o | Request the | int |
| | | | 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 in an | |
| SHIM_LOC_LOCAL_SEND | o | o | Get or set the | *1 | | | | | ancillary data | |
| | | | source locator | | | | | | object. | |
| SHIM_LOC_LOCAL_SEND | o | o | Get or set the | Note |
| | | | source locator | 1 |
| | | | of outgoing IP | | | | | | of outgoing IP | |
| | | | packets. | | | | | | packets. | |
| SHIM_LOC_PEER_SEND | o | o | Get or set the | *1 | | SHIM_LOC_PEER_SEND | o | o | Get or set the | Note |
| | | | destination | | | | | | destination | 1 |
| | | | locator of | | | | | | locator of | |
| | | | outgoing IP | | | | | | outgoing IP | |
| | | | packets. | | | | | | packets. | |
| SHIM_LOCLIST_LOCAL | o | o | Get or set the | *2 | | SHIM_LOCLIST_LOCAL | o | o | Get or set the | Note |
| | | | list of | | | | | | list of | 2 |
| | | | locators | | | | | | locators | |
| | | | associated with | | | | | | associated with | |
| | | | the local EID. | | | | | | the local EID. | |
| SHIM_LOCLIST_PEER | o | o | Get or set the | *2 | | SHIM_LOCLIST_PEER | o | o | Get or set the | Note |
| | | | list of | | | | | | list of | 2 |
| | | | 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 | | | | | | Send Timeout | |
| | | | for detecting | | | | | | value of the | |
| | | | failure. | | | | | | REAP protocol. | |
| SHIM_PATHEXPLORE | o | o | Get or set | *3 | | SHIM_PATHEXPLORE | o | o | Get or set | Note |
| | | | parameters for | | | | | | parameters for | 3 |
| | | | path | | | | | | path | |
| | | | exploration and | | | | | | exploration and | |
| | | | failure | | | | | | failure | |
| | | | detection. | | | | | | detection. | |
| SHIM_CONTEXT_DEFERRED_SETUP | o | | Get 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. Note 1: Pointer to a shim_locator which is defined in Section 8.
*2: Pointer to an array of shim_locator. Note 2: Pointer to an array of shim_locator.
*3: Pointer to a shim_pathexplore which is defined in Section 7. Note 3: Pointer to a shim_pathexplore which is defined in Section 8.
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 12, line 43 skipping to change at page 14, line 33
| | IPv4 | | IPv6 | | | | IPv4 | | IPv6 | |
| +------+ +------+ | | +------+ +------+ |
| | | | | | | |
+------------------|----------|-----------------+ +------------------|----------|-----------------+
| | | |
IPv4 IPv6 IPv4 IPv6
Datagram Datagram Datagram Datagram
Figure 2: System model of sockets API with shim sub-layer Figure 2: System model of sockets API with shim sub-layer
5.1. SHIM_ASSOCIATED 6.1. SHIM_ASSOCIATED
The SHIM_ASSOCIATED option is used to check whether the socket is The SHIM_ASSOCIATED option is used to check whether the socket is
associated with any shim context or not. associated with any shim context or not.
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
skipping to change at page 13, line 30 skipping to change at page 15, line 18
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:
int optval; int optval;
int optlen = sizeof(optval); int optlen = sizeof(optval);
getsockopt(fd, SOL_SHIM, SHIM_ASSOCIATED, &optval, &optlen); getsockopt(fd, SOL_SHIM, SHIM_ASSOCIATED, &optval, &optlen);
5.2. SHIM_DONTSHIM 6.2. SHIM_DONTSHIM
The SHIM_DONTSHIM option is used to request the shim layer not to The SHIM_DONTSHIM option is used to request the shim layer not to
provide the multihoming support for the communication established provide the multihoming support for the communication established
over the socket. over the socket.
The data type of the option value is an integer, and it takes 0 or 1. The data type of the option value is an integer, and it takes 0 or 1.
An option value 0 means that the shim sub-layer is employed if An option value 0 means that the shim sub-layer is employed if
available. An option value 1 means that the application does not available. An option value 1 means that the application does not
want the shim sub-layer to provide the multihoming support for the want the shim sub-layer to provide the multihoming support for the
communication established over the socket. communication established over the socket.
skipping to change at page 14, line 20 skipping to change at page 16, line 12
For example, the application can check the option value as follows: For example, the application can check the option value as follows:
int optval; int optval;
int len; int len;
len = sizeof(optval); len = sizeof(optval);
getsockopt(fd, SOL_SHIM, SHIM_DONTSHIM, &optval, &len); getsockopt(fd, SOL_SHIM, SHIM_DONTSHIM, &optval, &len);
5.3. SHIM_HOT_STANDBY 6.3. SHIM_HOT_STANDBY
The SHIM_HOT_STANDBY option is used to control the shim sub-layer The SHIM_HOT_STANDBY option is used to control the shim sub-layer
whether to employ a hot-standby connection for the socket or not. A whether to employ a hot-standby connection for the socket or not. A
hot-standby connection is an alternative working locator pair to the hot-standby connection is an alternative working locator pair to the
current locator pair. This option is effective only when there is a current locator pair. This option is effective only when there is a
shim context associated with the socket. shim context associated with the socket.
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().
skipping to change at page 15, line 12 skipping to change at page 17, line 4
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_LOC_LOCAL_PREF 6.4. SHIM_LOC_LOCAL_PREF
The SHIM_LOC_LOCAL_PREF option is used to get or set preference for a 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 source locator for outbound traffic within a given context. This
option is effective only when there is a shim context associated with option is effective only when there is a shim context associated with
the socket. the socket.
The preference of a locator is defined by a combination of priority The preference of a locator is defined by a combination of priority
and weight as per DNS SRV[RFC2782]. Note that the SHIM6 base and weight as per DNS SRV[RFC2782]. Note that the SHIM6 base
protocol defines preference of locator in the same way. protocol defines preference of locator in the same way.
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 8.
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 updates 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 application needs to get or set preference for each address, one
by one.
When the application specifies the socket option to an unconnected When the application specifies the socket option to an unconnected
socket, an error code EOPNOTSUPP is returned to the application. socket, an error code EOPNOTSUPP is returned to the application.
When there is no shim context associated with the socket, an error When there is no shim context associated with the socket, an error
code ENOENT is returned to the application. 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 fails. 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
skipping to change at page 16, line 31 skipping to change at page 18, line 31
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);
5.5. SHIM_LOC_PEER_PREF 6.5. SHIM_LOC_PEER_PREF
The SHIM_LOC_PEER_PREF option is used to get or set preference of a The SHIM_LOC_PEER_PREF option is used to get or set preference of a
destination locator for outbound traffic within a given context. destination locator for outbound traffic within a given context.
This option is effective only when there is a shim context associated This option is effective only when there is a shim context associated
with the socket. with the socket.
As defined earlier, the preference of a locator is defined by a As defined earlier, the preference of a locator is defined by a
combination of priority and weight as per DNS SRV[RFC2782]. When combination of priority and weight as per DNS SRV[RFC2782]. When
there are more than one candidate destination locators, the shim sub- there are more than one candidate destination locators, the shim sub-
layer makes selection based on the priority and weight specified for layer makes selection based on the priority and weight specified for
each locator. 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 8.
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().
When the application specifies the socket option to an unconnected When the application specifies the socket option to an unconnected
socket, an error code EOPNOTSUPP is returned to the application. socket, an error code EOPNOTSUPP is returned to the application.
When there is no shim context associated with the socket, an error When there is no shim context associated with the socket, an error
code ENOENT is returned to the application. 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.
An error EUNREACHABLELOCATOR is returned when the requested locator
is determined to be not reachable according to a reachability check.
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.
5.6. SHIM_LOC_LOCAL_RECV 6.6. 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(). This an ancillary data object which can be accessed by recvmsg(). This
option is effective only when there is a shim context associated with option is effective only when there is a shim context associated 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 7 for the procedure to access locator information stored
in the ancillary data objects. in the ancillary data objects.
When the application specifies the socket option to an unconnected When the application specifies the socket option to an unconnected
socket, an error code EOPNOTSUPP is returned to the application. socket, an error code EOPNOTSUPP is returned to the application.
When there is no shim context associated with the socket, an error When there is no shim context associated with the socket, an error
code ENOENT is returned to the application. 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.
skipping to change at page 18, line 15 skipping to change at page 20, line 21
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);
5.7. SHIM_LOC_PEER_RECV 6.7. 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(). 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 7 for the procedure to access locator information stored
in the ancillary data objects. in the ancillary data objects.
When the application specifies the socket option to an unconnected When the application specifies the socket option to an unconnected
socket, an error code EOPNOTSUPP is returned to the application. socket, an error code EOPNOTSUPP is returned to the application.
When there is no shim context associated with the socket, an error When there is no shim context associated with the socket, an error
code ENOENT is returned to the application. 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.
5.8. SHIM_LOC_LOCAL_SEND 6.8. 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. This option is effective only when there is be sent from the socket. This option is effective only when 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 locator which is stored in a shim_locator data structure. When a
a zero-filled locator is specified, pre-existing setting of local 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().
When the application specifies the socket option to an unconnected When the application specifies the socket option to an unconnected
socket, an error code EOPNOTSUPP is returned to the application. socket, an error code EOPNOTSUPP is returned to the application.
When there is no shim context associated with the socket, an error When there is no shim context associated with the socket, an error
code ENOENT is returned to the application. code ENOENT is returned to the application.
skipping to change at page 19, line 43 skipping to change at page 21, line 48
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_prio = 0; locator.lc_prio = 0;
locator.lc_weight = 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 designated 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 */
5.9. SHIM_LOC_PEER_SEND 6.9. 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. This option is effective only when there to be sent from the socket. This option is effective 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 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 locator which is stored in a shim_locator data structure. When a
a zero-filled locator is specified, pre-existing setting of remote 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().
The difference between the SHIM_LOC_PEER_SEND option and the
SHIM_LOC_PEER_PREF option is that the former guarantee the use of
requested locator when applicable whereas the latter does not.
When the application specifies the socket option to an unconnected When the application specifies the socket option to an unconnected
socket, an error code EOPNOTSUPP is returned to the application. socket, an error code EOPNOTSUPP is returned to the application.
When there is no shim context associated with the socket, an error When there is no shim context associated with the socket, an error
code ENOENT is returned to the application. code ENOENT is returned to the application.
An error EINVALIDLOCATOR when invalid an locator is specified. An error EINVALIDLOCATOR is returned when the validation of the
requested locator fails.
An error EUNVERIFIEDLOCATOR is returned when reachability for the
requested locator has not been verified yet.
An error EUNREACHABLELOCATOR is returned when the requested locator
is determined to be not reachable according to a reachability check.
The usage of the option is the same as that of SHIM_LOC_LOCAL_SEND The usage of the option is the same as that of SHIM_LOC_LOCAL_SEND
option. option.
5.10. SHIM_LOCLIST_LOCAL 6.10. 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. This option is effective only when there is a shim context socket. This option is effective only when there is a shim 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 8 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 to by the optval argument should be the size of the buffer pointed to by the optval argument should be
large enough to store an array of locator information. The number of large enough to store an array of locator information. The number of
the 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 to by the optval argument should contain an array of locator pointed to by the optval argument should contain an array of locator
skipping to change at page 21, line 22 skipping to change at page 23, line 41
An error EINVALIDLOCATOR is returned when the validation of any of An error EINVALIDLOCATOR is returned when the validation of any of
the specified locators failed. 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), or when the size of 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 buffer provided by the application is not large enough to store
the locator list provided by the shim sub-layer. 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.
Note that IPv4 locator can be handled by HIP and not by SHIM6.
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 */
skipping to change at page 23, line 5 skipping to change at page 25, line 5
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 */
... ...
5.11. SHIM_LOCLIST_PEER 6.11. 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. This option is effective only when there is a shim context socket. This option is effective only when there is a shim 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 8 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 to by the optval argument should be the size of the buffer pointed to by the optval argument should be
large enough to store an array of locator information. The number of large enough to store an array of locator information. The number of
the 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 to by the optval argument should contain an array of locator pointed to by the optval argument should contain an array of locator
skipping to change at page 23, line 35 skipping to change at page 25, line 35
When the application specifies the socket option to an unconnected When the application specifies the socket option to an unconnected
socket, an error code EOPNOTSUPP is returned to the application. socket, an error code EOPNOTSUPP is returned to the application.
When there is no shim context associated with the socket, an error When there is no shim context associated with the socket, an error
code ENOENT is returned to the application. code ENOENT is returned to the application.
An error EINVALIDLOCATOR is returned when the validation of any of An error EINVALIDLOCATOR is returned when the validation of any of
the specified locators failed. the specified locators failed.
An error EUNVERIFIEDLOCATOR is returned when reachability for the
requested locator has not been verified yet.
An error EUNREACHABLELOCATOR is returned when the requested locator
is determined to be not reachable according to a reachability check.
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), or when the size of 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 buffer provided by the application is not large enough to store
the locator list provided by the shim sub-layer. 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.
5.12. SHIM_APP_TIMEOUT 6.12. SHIM_APP_TIMEOUT
The SHIM_APP_TIMEOUT option is used to get or set the Send Timeout The SHIM_APP_TIMEOUT option is used to get or set the Send Timeout
value of the REAP protocol. This option is effective only when there value of the REAP protocol[RFC5534]. This option is effective only
is a shim context associated with the socket. when there 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]
When the application specifies the socket option to an unconnected When the application specifies the socket option to an unconnected
socket, an error code EOPNOTSUPP is returned to the application. socket, an error code EOPNOTSUPP is returned to the application.
When there is no shim context associated with the socket, an error When there is no shim context associated with the socket, an error
code ENOENT is returned to the application. code ENOENT is returned to the application.
When there is no REAP protocol instance on the system, an error code
EOPNOTSUPP 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));
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 6.13. SHIM_PATHEXPLORE
The application may use this socket option to get or set parameters The application may use this socket option to get or set parameters
concerning path exploration. Path exploration is a procedure to find concerning path exploration. Path exploration is a procedure to find
an alternative locator pair to the current locator pair. As the REAP an alternative locator pair to the current locator pair. As the REAP
specification defines, a peer may send Probe messages to find an specification defines, a peer may send Probe messages to find an
alternative locator pair. alternative locator pair.
This option is effective only when there is a shim context associated This option is effective only when there is a shim context associated
with the socket. 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
set of information for path exploration is stored. The data set of information for path exploration is stored. The data
structure is defined in Section 7. structure is defined in Section 8.
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.
When the application specifies the socket option to an unconnected When the application specifies the socket option to an unconnected
socket, an error code EOPNOTSUPP is returned to the application. socket, an error code EOPNOTSUPP is returned to the application.
When there is no shim context associated with the socket, an error When there is no shim context associated with the socket, an error
code ENOENT is returned to the application. code ENOENT is returned to the application.
skipping to change at page 25, line 30 skipping to change at page 27, line 38
For example, an application can get parameters for path exploration For example, an application can get parameters for path exploration
by using the socket option as follows. by using the socket option as follows.
struct shim6_pathexplore pe; struct shim6_pathexplore pe;
int len; int len;
len = sizeof(pe); len = sizeof(pe);
getsockopt(fd, SOL_SHIM, SHIM_PATHEXPLORE, &pe, &len); getsockopt(fd, SOL_SHIM, SHIM_PATHEXPLORE, &pe, &len);
5.14. SHIM_DEFERRED_CONTEXT_SETUP 6.14. SHIM_DEFERRED_CONTEXT_SETUP
The SHIM_DEFERRED_CONTEXT_SETUP option is used to check whether The SHIM_DEFERRED_CONTEXT_SETUP option is used to check whether
deferred context setup is possible or not. Deferred context setup deferred context setup is possible or not. Deferred context setup
means 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). The option value 1 means that the shim should be binary (0 or 1). The option value 1 means that the shim
skipping to change at page 26, line 13 skipping to change at page 28, line 17
is possible or not as follows: 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 6.15. Applicability
All the socket options defined in this section except for the All the socket options defined in this section except for the
SHIM_DONTSHIM option are applicable to applications that use SHIM_DONTSHIM option are applicable to applications that use
connected sockets. connected sockets.
All the socket options defined in this section except for the All the socket options defined in this section except for the
SHIM_ASSOCIATED, SHIM_DONTSHIM and SHIM_CONTEXT_DEFERRED_SETUP SHIM_ASSOCIATED, SHIM_DONTSHIM and SHIM_CONTEXT_DEFERRED_SETUP
options are effective only when there is a shim context associated options are effective only when there is a shim context associated
with the socket. with the socket.
5.16. Error Handling 6.16. 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:
EINVALIDLOCATOR EINVALIDLOCATOR
This indicates that at least one of the necessary validations This indicates that the locator is not part of the HBA
inside the shim sub-layer for the specified locator has failed. set[RFC5535] within the shim context associated with the socket.
In case of SHIM6, there are two kinds of verifications required EUNVERIFIEDLOCATOR
for security reasons prior to sending an IP packet to the peer's This indicates that the reachability of the locator has not been
new locator; one is the return routability (check if the peer is confirmed. This error is applicable to only peer's locator.
actually willing to receive data with the specified locator) and EUNREACHABLELOCATOR
the other one is the verification based on crypto identifier This indicates that the locator is not reachable according to the
mechanisms [RFC3972], [RFC5535]. result of the reachability check. This error is applicable to
only peer's locator.
6. Ancillary Data for Multihoming Shim Sub-layer 7. Ancillary Data for Multihoming Shim Sub-layer
This section provides definitions of ancillary data to be used for This section provides definitions of ancillary data to be used for
locator management and notification from/to the shim sub-layer to/ locator management and notification from/to the shim sub-layer to/
from application. from application.
When the application performs locator management by sendmsg() or When the application performs locator management by sendmsg() or
recvmsg(), a member of the msghdr structure (given in Figure 3) recvmsg(), a member of the msghdr structure (given in Figure 3)
called msg_control holds a pointer to the buffer in which one ore called msg_control holds a pointer to the buffer in which one ore
more shim specific ancillary data objects may be stored. An more shim specific ancillary data objects may be stored. An
ancillary data object can store a single locator. It should be ancillary data object can store a single locator. It should be
skipping to change at page 27, line 33 skipping to change at page 29, line 39
than a locator. SHIM_LOC_PEER_RECV should be used to get the locator than a locator. SHIM_LOC_PEER_RECV should be used to get the locator
of the peer node. of the peer node.
Table 2 is a list of the shim specific ancillary data which can be Table 2 is a list of the shim specific ancillary data which can be
used for locator management by recvmsg() or sendmsg(). In any case, used for locator management by recvmsg() or sendmsg(). In any case,
the value of cmsg_level must be set as SOL_SHIM. the value of cmsg_level must be set as SOL_SHIM.
+---------------------+-----------+-----------+-----------------+ +---------------------+-----------+-----------+-----------------+
| cmsg_type | sendmsg() | recvmsg() | cmsg_data[] | | cmsg_type | sendmsg() | recvmsg() | cmsg_data[] |
+---------------------+-----------+-----------+-----------------+ +---------------------+-----------+-----------+-----------------+
| SHIM_LOC_LOCAL_RECV | | o | *1 | | SHIM_LOC_LOCAL_RECV | | o | Note 1 |
| SHIM_LOC_PEER_RECV | | o | *1 | | SHIM_LOC_PEER_RECV | | o | Note 1 |
| SHIM_LOC_LOCAL_SEND | o | | *1 | | SHIM_LOC_LOCAL_SEND | o | | Note 1 |
| SHIM_LOC_PEER_SEND | o | | *1 | | SHIM_LOC_PEER_SEND | o | | Note 1 |
| SHIM_FEEDBACK | o | | shim_feedback{} | | SHIM_FEEDBACK | o | | shim_feedback{} |
+---------------------+-----------+-----------+-----------------+ +---------------------+-----------+-----------+-----------------+
Table 2: Shim specific ancillary data Table 2: Shim specific ancillary data
*1: cmsg_data[] includes a single sockaddr_in{} or sockaddr_in6{} and Note 1: cmsg_data[] within msg_control includes a single
padding if necessary sockaddr_in{} or sockaddr_in6{} and padding if necessary
6.1. Get Locator from Incoming Packet 7.1. 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 When there is no shim context associated with the socket, the shim
sub-layer MUST return zero-filled locator information to the sub-layer MUST return zero-filled locator information to the
application. application.
6.2. Set Locator for Outgoing Packet 7.2. 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. If the locators to be used for the communication over the socket. If the
specified locator pair is verified, the shim sub-layer overrides the specified locator pair is verified, the shim sub-layer overrides the
locator(s) of the outgoing IP packet. Note that the effect is locator(s) of the outgoing IP packet. Note that the effect is
limited to the datagram transmitted by the sendmsg(). limited to the datagram transmitted by the sendmsg().
When there is no shim context associated with the socket, an error When there is no shim context associated with the socket, an error
code ENOENT is returned to the application. code ENOENT is returned to the application.
An error code EINVALIDLOCATOR is returned when validation of the An error code EINVALIDLOCATOR is returned when validation of the
specified locator fails. specified locator fails.
6.3. Notification from Application to Multihoming Shim Sub-layer An error EUNVERIFIEDLOCATOR is returned when reachability for the
requested locator has not been verified yet. The application is
recommended to use another destination locator until the reachability
check for the requested locator is done.
An application may provide feedbacks to the shim sub-layer about the An error EUNREACHABLELOCATOR is returned when the requested locator
communication status. Such feedbacks are particularly useful for the is determined to be not reachable according to a reachability check.
shim sub-layer in the absence of REAP mechanism to monitor the The application is recommended to use another destination locator
reachability status of the currently used locator pair in a given when receiving the error.
shim context.
7.3. Notification from Application to Multihoming Shim Sub-layer
An application may provide feedback to the shim sub-layer about the
communication status. Such feedback are useful for the shim sub-
layer to monitor the reachability status of the currently used
locator pair in a given 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.
When there is no shim context associated with the socket, an error When there is no shim context associated with the socket, an error
code ENOENT is returned to the application. code ENOENT is returned to the application.
See Section 7.3 for details of the data structure to be used. See Section 8.3 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. Applicability 7.4. Applicability
All the ancillary data for the shim sub-layer is applicable to All the ancillary data for the shim sub-layer is applicable to
connected sockets. connected sockets.
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 8. Data Structures
This section data structures for the shim sub-layer. These data This section gives data structures for the shim sub-layer. These
structures are either used as a parameter for setsockopt() or data 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 6) 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 7).
7.1. Placeholder for Locator Information 8.1. Placeholder for Locator Information
As defined in Section 5, the SHIM_LOC_*_PREF, SHIM_LOC_*_SEND, and As defined in Section 6, the SHIM_LOC_*_PREF, SHIM_LOC_*_SEND, and
SHIM_LOCLIST_* socket options need to handle one or more locator SHIM_LOCLIST_* socket options need to handle one or more locator
information. Locator information includes not only the locator information. Locator information includes not only the locator
itself but also additional information about the locator which is itself but also additional information about the locator which is
useful for locator management. A new data structure is defined to useful for locator management. A new data structure 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 {
skipping to change at page 30, line 16 skipping to change at page 32, line 33
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_prio lc_prio
The priority of the locator. The range is 0-65535. The lowest The priority of the locator. The range is 0-65535. The lowest
priority value means the highest priority. priority value means the highest priority.
lc_weight lc_weight
The weight value indicates a relative weight for locators with the The weight value indicates a relative weight for locators with the
same priority value. The range is 0-65535. same priority value. The range is 0-65535. A locator with higher
weight value is prioritized over the other locators with lower
weight values.
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 is only used in a read (getsockopt())
(getsockopt()) operation. 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 lc_flags
Each bit of the flags represents a specific characteristics of the Each bit of the flags represents a specific characteristics of the
locator. Hash Based Address (HBA) is defined as 0x01. locator. Hash Based Address (HBA) is defined as 0x01.
Cryptographically Generated Address (CGA) is defined as 0x02. Cryptographically Generated Address (CGA) is defined as 0x02.
7.1.1. Handling Locator behind NAT 8.1.1. 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[RFC5770]. Note also that the locator
that the locator behind NAT is not necessarily an IPv4 address but it behind NAT is not necessarily an IPv4 address but it can be an IPv6
can be an IPv6 address. Below is an example where the application address. Below is an example where the application sets a UDP
sets a UDP encapsulation interface as a source locator when sending encapsulation interface as a source locator when sending IP packets.
IP packets.
struct shim_locator locator; struct shim_locator locator;
struct in6_addr ia6; struct in6_addr ia6;
/* 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 */
skipping to change at page 31, line 29 skipping to change at page 33, line 41
locator.lc_weight = 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 8.2. Path Exploration Parameter
As defined in Section 5, SHIM_PATHEXPLORE allows application to set As defined in Section 6, SHIM_PATHEXPLORE allows application to set
or read the parameters for path exploration and failure detection. A or read the parameters for path exploration and failure detection. A
new data structure called shim_pathexplore is defined to store the new data structure called shim_pathexplore is defined to store the
necessary parameters. Figure 6 illustrates the data structure. The necessary parameters. Figure 6 illustrates the data structure. The
data structure can be passed to getsockopt() or setsockopt() as an data structure can be passed to getsockopt() or setsockopt() as an
argument. argument.
struct shim_pathexplore { struct shim_pathexplore {
uint8_t pe_probenum; /* # of initial probe */ uint8_t pe_probenum; /* # of initial probes */
uint8_t pe_keepaliveto; /* Keepalive Timeout */ uint8_t pe_keepaliveto; /* Keepalive Timeout */
uint16_t pe_initprobeto; /* Initial Probe Timeout */ uint16_t pe_initprobeto; /* Initial Probe Timeout */
uint32_t pe_reserved; /* reserved */ uint32_t pe_reserved; /* reserved */
}; };
Figure 6: path explore structure Figure 6: path explore structure
pe_probenum pe_probenum
Indicates the number of initial probe messages to be sent. Indicates the number of initial probe messages to be sent.
Default value of this parameter should follow what is specified in Default value of this parameter should follow what is specified in
skipping to change at page 32, line 22 skipping to change at page 34, line 35
pe_initprobeto pe_initprobeto
Indicates retransmission timer of REAP Probe message in Indicates retransmission timer of REAP Probe message in
milliseconds. Note that this timer is applied before exponential milliseconds. Note that this timer is applied before exponential
back-off is started. A REAP Probe message for the same locator back-off is started. A REAP Probe message for the same locator
pair may be retransmitted. Default value of this parameter should pair may be retransmitted. Default value of this parameter should
follow what is specified in [RFC5534]. follow what is specified in [RFC5534].
pe_reserved pe_reserved
A reserved field for future extension. By default, the field A reserved field for future extension. By default, the field
should be initialized to zero. should be initialized to zero.
7.3. Feedback Information 8.3. Feedback Information
As mentioned in Section 6.3, applications can inform the shim sub- As mentioned in Section 7.3, applications can inform the shim sub-
layer about the status of unicast reachability of the locator pair layer about the status of unicast reachability of the locator pair
currently in use. The feedback information can be handled by using currently in use. The feedback information can be handled by using
ancillary data called SHIM_FEEDBACK. A new data structure named ancillary data called SHIM_FEEDBACK. A new data structure named
shim_feedback is illustrated in Figure 7. shim_feedback is illustrated in Figure 7.
struct shim_feedback { struct shim_feedback {
uint8_t fb_direction; /* direction of traffic */ uint8_t fb_direction; /* direction of traffic */
uint8_t fb_indicator; /* indicator (1-3) */ uint8_t fb_indicator; /* indicator (1-3) */
uint16_t fb_reserved; /* reserved */ uint16_t fb_reserved; /* reserved */
}; };
skipping to change at page 33, line 4 skipping to change at page 35, line 20
A value indicating the degree of satisfaction of a unidirectional A value indicating the degree of satisfaction of a unidirectional
reachability for a given locator pair. reachability for a given locator pair.
* 0: Default value. Whenever this value is specified the * 0: Default value. Whenever this value is specified the
feedback information must not be processed by the shim sub- feedback information must not be processed by the shim sub-
layer. layer.
* 1: Unable to connect. There is no unidirectional reachability * 1: Unable to connect. There is no unidirectional reachability
between the locator pair in question. between the locator pair in question.
* 2: Unsatisfactory. The application is not satisfied with the * 2: Unsatisfactory. The application is not satisfied with the
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 9. System Requirements
As addressed in Section 5, most of the socket options and ancillary As addressed in Section 6, most of the socket options and ancillary
data defined in this document are applicable to connected sockets. data defined in this document are applicable to connected sockets.
It is assumed that the kernel is capable of maintaining the It is assumed that the kernel is capable of maintaining the
association between a connected socket and a shim context. This association between a connected socket and a shim context. This
requirement is considered to be reasonable because a pair of source requirement is considered to be reasonable because a pair of source
and destination IP addresses is bound to a connected socket. and destination IP addresses is bound to a connected socket.
9. Relation to Existing Sockets API Extensions 10. 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 6, 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_SEND and SHIM_LOC_PEER_SEND 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
the communication endpoints which is represented by a pair of IP the communication endpoints which is represented by a pair of IP
address and port number assigned to the socket. getsockname() gives address and port number assigned to the socket. getsockname() gives
IP address and port number assigned to the socket on the local side, IP address and port number assigned to the socket on the local side,
and getpeername() gives IP address and port number of the peer side. and getpeername() gives IP address and port number of the peer side.
10. Operational Considerations 11. Operational Considerations
This section gives operational considerations of the sockets API This section gives operational considerations of the sockets API
defined in this document. defined in this document.
10.1. Conflict Resolution 11.1. Conflict Resolution
There may be a conflicting situation when different applications There may be a conflicting situation when different applications
specify difference preference for the same shim context. For specify difference preference for the same shim context. For
instance, application A and B may establish communication with the instance, application A and B may establish communication with the
same EID pair while both applications have different preference in same EID pair while both applications have different preference in
their choice of local locator. The notion of context forking in their choice of local locator. The notion of context forking in
SHIM6 can resolve the conflicting situation. SHIM6 can resolve the conflicting situation.
Socket options defined in Section 5 may cause conflicting situation Socket options defined in Section 6 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. context.
skipping to change at page 34, line 39 skipping to change at page 37, line 5
layer SHOULD supersede the request made by SHIM_LOC_*_SEND over the layer SHOULD supersede the request made by SHIM_LOC_*_SEND over the
preference specified by SHIM_LOC_*_PREF. preference specified by SHIM_LOC_*_PREF.
When the peer provides preferences of the locators (e.g., a SHIM6 When the peer provides preferences of the locators (e.g., a SHIM6
peer may send a locator with a Locator Preferences Option) which peer may send a locator with a Locator Preferences Option) which
conflict with preference specified by the applications either by conflict with preference specified by the applications either by
SHIM_LOC_PEER_SEND or SHIM_LOC_PEER_PREF, the shim sub-layer SHOULD SHIM_LOC_PEER_SEND or SHIM_LOC_PEER_PREF, the shim sub-layer SHOULD
supersede the preference made by the application over the preference supersede the preference made by the application over the preference
specified by the peer. specified by the peer.
10.2. Incompatiblility between IPv4 and IPv6 11.2. Incompatibility 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 techniques in other protocol conversion techniques
[RFC2765][I-D.ietf-behave-v6v4-xlate]. [RFC2765][I-D.ietf-behave-v6v4-xlate].
As studied in the previous works on protocol As studied in the previous works on protocol
conversion[RFC2765][I-D.ietf-behave-v6v4-xlate], some of the features conversion[RFC2765][I-D.ietf-behave-v6v4-xlate], some of the features
(IPv6 routing headers, hop-by-hop extension headers, and destination (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 outside the scope of this document to describe how
such erroneous cases. the shim sub-layer should behave in such erroneous cases.
11. IANA Considerations 12. IANA Considerations
This document contains no IANA consideration. There is no IANA considerations for the socket options (SHIM_*), the
ancillary data, and the socket level (SOL_SHIM) that are defined in
this document. All the numbers concerned are not under the control
of IETF or IANA but they are platform-specific.
12. Protocol Constants and Variables 13. Protocol Constants and Variables
This section defines protocol constants and variables. This section defines protocol constants and variables.
SHIM_MAX_LOCATORS The maximum number of the locators to be included SHIM_MAX_LOCATORS The maximum number of the locators to be included
in a locator list. 32. in a locator list. The value is set to 32.
13. Security Considerations 14. Security Considerations
This section gives security considerations of the API defined in this This section gives security considerations of the API defined in this
document. document.
13.1. Treatment of Unknown Locator 14.1. Treatment of Unknown Locator
When sending IP packets, application may request use of unknown When sending IP packets, application may request use of unknown
locator for the source and/or destination locators. Note that locator for the source and/or destination locators. Note that
treatment of unknown locator can be a subject of security treatment of unknown locator can be a subject of security
considerations because use of invalid source and/or destination considerations because use of invalid source and/or destination
locator may cause redirection attack. locator may cause redirection attack.
13.1.1. Treatment of Unknown Source Locator 14.1.1. Treatment of Unknown Source Locator
The shim sub-layer checks if the requested locator is available on The shim sub-layer checks if the requested locator is available on
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_LOCLIST_LOCAL o SHIM_LOCLIST_LOCAL
13.1.2. Treatment of Unknown Destination Locator 14.1.2. 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 layer MUST
MUST reject the request for using unknown destination locator. reject the request for using an 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 layer MUST reject
accept the request for using unknown destination locator. the request for using an unknown destination locator. There is,
however, an exceptional case where the HIP layer SHOULD accept the
request provided that the HIP association is in an UNASSOCIATED
state. Details of locator handling in HIP is described in section
4.6 of [I-D.ietf-hip-native-api].
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_LOCLIST_PEER o SHIM_LOCLIST_PEER
14. Changes 15. Changes
14.1. Changes from version 00 to version 01 15.1. 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.
o Deprecate SHIM_IF_RECV and SHIM_IF_SEND socket options. o Deprecate SHIM_IF_RECV and SHIM_IF_SEND socket options.
o Give default value and how to disable given socket option. o Give default value and how to disable given socket option.
14.2. Changes from version 01 to version 02 15.2. Changes from version 01 to version 02
o Add section describing context forking. o Add section describing context forking.
o Rephrase conclusion section. o Rephrase conclusion section.
o Separate normative references from informative references. o Separate normative references from informative references.
o Remove texts from discussion section that are not relevant to the o Remove texts from discussion section that are not relevant to the
contents of the document. contents of the document.
o Add section describing change history (this section). o Add section describing change history (this section).
14.3. Changes from version 02 to version 03 15.3. Changes from version 02 to version 03
o Add an Appendix section describing the issue of context forking. o Add an Appendix section describing the issue of context forking.
14.4. Changes from version 03 to version 04 15.4. Changes from version 03 to version 04
o Updated reference. o Updated reference.
o Correct typo and grammatical errors. o Correct typo and grammatical errors.
14.5. Changes from version 04 to version 05 15.5. Changes from version 04 to version 05
o Added definition of SHIM_FEEDBACK ancillary data. o Added definition of SHIM_FEEDBACK ancillary data.
o Added an example of code using the SHIM_LOCLIST_LOCAL o Added an example of code using the SHIM_LOCLIST_LOCAL
o Added SHIM_LOC_LOCAL_SEND and SHIM_LOC_PEER_SEND socket options. o Added SHIM_LOC_LOCAL_SEND and SHIM_LOC_PEER_SEND socket options.
14.6. Changes from version 05 to version 06 15.6. Changes from version 05 to version 06
o Updated references. o Updated references.
14.7. Changes from version 06 to version 07 15.7. Changes from version 06 to version 07
o Resolved editorial issues. o Resolved editorial issues.
14.8. Changes from version 07 to version 08 15.8. Changes from version 07 to version 08
No changes are made except for updates of the references. No changes are made except for updates of the references.
14.9. Changes from version 08 to version 09 15.9. Changes from version 08 to version 09
o Updated texts for Section 1 and Section 5 according to the o Updated texts for Section 1 and Section 5 according to the
comments provided by Samu Varjonen. comments provided by Samu Varjonen.
o Made it clear that downgrading the multihoming shim support (i.e., o Made it clear that downgrading the multihoming shim support (i.e.,
specifying value 1 with the SHIM_DONTSHIM socket option) is only specifying value 1 with the SHIM_DONTSHIM socket option) is only
allowed before the socket is connected. allowed before the socket is connected.
o Updated locator information (shim_locator{}) so that it can o Updated locator information (shim_locator{}) so that it can
contain a locator behind NAT. contain a locator behind NAT.
14.10. Changes from version 09 to version 10 15.10. Changes from version 09 to version 10
o Addressed applicability of socket options and ancillary data for o Addressed applicability of socket options and ancillary data for
the shim sub-layer. the shim sub-layer.
o Addressed system requirements. o Addressed system requirements.
o Removed unnecessary description about deprecated socket option o Removed unnecessary description about deprecated socket option
(SHIM_IF_RECV). (SHIM_IF_RECV).
14.11. Changes from version 10 to version 11 15.11. 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 15.12. Changes from version 11 to version 12
o Reflected comments from Brian Karpenter. o Reflected comments from Brian Karpenter.
o Reflected comments from Michael Scharf. o Reflected comments from Michael Scharf.
14.13. Changes from version 12 to version 13 15.13. Changes from version 12 to version 13
o Reflected comments from Sebastien Barre. o Reflected comments from Sebastien Barre.
o Removed the description about the notification from the shim sub- o Removed the description about the notification from the shim sub-
layer to applications. layer to applications.
o Narrowed down the scope of the applicability of the socket options o Narrowed down the scope of the applicability of the socket options
and the ancillary data. and the ancillary data.
14.14. Changes from version 13 to version 14 15.14. Changes from version 13 to version 14
o No change was made. The draft was re-submitted to avoid o No change was made. The draft was re-submitted to avoid
expiration. expiration.
15. Acknowledgments 15.15. Changes from version 14 to version 15
o Addressed the difference between SHIM_LOC_PEER_SEND and
SHIM_LOC_PEER_PREF.
o Made clear distinction between validation of locator and
verification of locator, and introduced two errors:
EUNVERIFIEDLOCATOR and EUNREACHABLELOCATOR.
o Addressed exceptional case for HIP in handling of unknown
destination locator.
16. 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 helpful Authors sincerely thank to the following people for their helpful
comments to the document: Samu Varjonen, Dmitriy Kuptsov, Brian comments to the document: Samu Varjonen, Dmitriy Kuptsov, Brian
Carpenter, Michael Scharf, and Sebastien Barre Carpenter, Michael Scharf, and Sebastien Barre
16. References 17. References
16.1. Normative References 17.1. 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.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3542] Stevens, W., Thomas, M., Nordmark, E., and T. Jinmei, [RFC3542] Stevens, W., Thomas, M., Nordmark, E., and T. Jinmei,
"Advanced Sockets Application Program Interface (API) for "Advanced Sockets Application Program Interface (API) for
IPv6", RFC 3542, May 2003. IPv6", RFC 3542, May 2003.
[RFC4423] Moskowitz, R. and P. Nikander, "Host Identity Protocol [RFC4423] Moskowitz, R. and P. Nikander, "Host Identity Protocol
(HIP) Architecture", RFC 4423, May 2006. (HIP) Architecture", RFC 4423, May 2006.
[RFC5533] Bagnulo, M. and E. Nordmark, "Level 3 multihoming shim [RFC5533] Nordmark, E. and M. Bagnulo, "Shim6: Level 3 Multihoming
protocol", RFC 5533, June 2009. Shim Protocol for IPv6", RFC 5533, June 2009.
[RFC5534] Arkko, J. and I. Beijnum, "Failure Detection and Locator [RFC5534] Arkko, J. and I. van Beijnum, "Failure Detection and
Pair Exploration Protocol for IPv6 Multihoming", RFC 5534, Locator Pair Exploration Protocol for IPv6 Multihoming",
June 2009. RFC 5534, June 2009.
16.2. Informative References 17.2. Informative References
[I-D.ietf-behave-v6v4-xlate] [I-D.ietf-behave-v6v4-xlate]
Li, X., Bao, C., and F. Baker, "IP/ICMP Translation Li, X., Bao, C., and F. Baker, "IP/ICMP Translation
Algorithm", draft-ietf-behave-v6v4-xlate-21 (work in Algorithm", draft-ietf-behave-v6v4-xlate-23 (work in
progress), August 2010. progress), September 2010.
[I-D.ietf-hip-nat-traversal] [I-D.ietf-hip-native-api]
Komu, M., Henderson, T., Tschofenig, H., Melen, J., and A. Komu, M. and T. Henderson, "Basic Socket Interface
Keranen, "Basic HIP Extensions for Traversal of Network Extensions for Host Identity Protocol (HIP)",
Address Translators", Internet draft-ietf-hip-native-api-12 (work in progress),
Draft draft-ietf-hip-nat-traversal-09, October 2009. January 2010.
[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]
Abley, J., Bagnulo, M., and A. Garcia-Martinez,
"Applicability Statement for the Level 3 Multihoming Shim
Protocol (Shim6)", draft-ietf-shim6-applicability-05 (work
in progress), February 2010.
[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 [RFC2782] Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for
specifying the location of services (DNS SRV)", RFC 2782, specifying the location of services (DNS SRV)", RFC 2782,
February 2000. February 2000.
[RFC3972] Aura, T., "Cryptographically Generated Addresses (CGA)",
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.
[RFC5770] Komu, M., Henderson, T., Tschofenig, H., Melen, J., and A.
Keranen, "Basic Host Identity Protocol (HIP) Extensions
for Traversal of Network Address Translators", RFC 5770,
April 2010.
Appendix A. Context Forking Appendix A. Context Forking
In this section, an issue concerning context forking and its relation In this section, an issue concerning context forking and its relation
to the multihoming shim API are discussed. to the multihoming shim API are discussed.
SHIM6 supports a notion of context forking. A peer may decide to SHIM6 supports a notion of context forking. A peer may decide to
fork a context for certain reason (e.g. upper layer protocol prefers fork a context for certain reason (e.g. upper layer protocol prefers
to use different locator pair than the one defined in available to use different locator pair than the one defined in available
context). The procedure of forking context is done similar to the context). The procedure of forking context is done similar to the
normal context establishment, performing the 4-way message exchange. normal context establishment, performing the 4-way message exchange.
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