draft-ietf-sipcore-locparam-06.txt   rfc8787.txt 
SIPCORE J. Winterbottom Internet Engineering Task Force (IETF) J. Winterbottom
Internet-Draft Winterb Consulting Services Request for Comments: 8787 Winterb Consulting Services
Updates: 6442 (if approved) R. Jesske Updates: 6442 R. Jesske
Intended status: Standards Track Deutsche Telekom Category: Standards Track Deutsche Telekom
Expires: August 17, 2020 B. Chatras ISSN: 2070-1721 B. Chatras
Orange Labs Orange Labs
A. Hutton A. Hutton
Atos Atos
February 14, 2020 May 2020
Location Source Parameter for the SIP Geolocation Header Field Location Source Parameter for the SIP Geolocation Header Field
draft-ietf-sipcore-locparam-06
Abstract Abstract
There are some circumstances where a Geolocation header field may There are some circumstances where a Geolocation header field may
contain more than one locationValue. Knowing the identity of the contain more than one locationValue. Knowing the identity of the
node adding the locationValue allows the recipient more freedom in node adding the locationValue allows the recipient more freedom in
selecting the value to look at first rather than relying solely on selecting the value to look at first rather than relying solely on
the order of the locationValues. This document defines the "loc-src" the order of the locationValues. This document defines the "loc-src"
parameter so that the entity adding the locationValue to Geolocation parameter so that the entity adding the locationValue to the
header field can identify itself using its hostname. This document Geolocation header field can identify itself using its hostname.
updates RFC 6442. This document updates RFC 6442.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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Internet-Drafts are draft documents valid for a maximum of six months This document is a product of the Internet Engineering Task Force
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Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on August 17, 2020. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8787.
Copyright Notice Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the Copyright (c) 2020 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 Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology
3. Rationale . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Rationale
4. Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Mechanism
5. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 5. Example
6. Privacy Considerations . . . . . . . . . . . . . . . . . . . 6 6. Privacy Considerations
7. Security Considerations . . . . . . . . . . . . . . . . . . . 6 7. Security Considerations
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 8. IANA Considerations
8.1. Registration of loc-src parameter for Geolocation header 8.1. Registration of "loc-src" Parameter for Geolocation Header
field . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Field
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7 9. References
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 9.1. Normative References
10.1. Normative References . . . . . . . . . . . . . . . . . . 7 9.2. Informative References
10.2. Informative References . . . . . . . . . . . . . . . . . 8 Acknowledgements
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 Authors' Addresses
1. Introduction 1. Introduction
The SIP Geolocation specification [RFC6442] describes the The SIP Geolocation specification [RFC6442] describes the
"Geolocation" SIP header field which is used to indicate that the SIP "Geolocation" SIP header field, which is used to indicate that the
message is conveying location information. [RFC6442] specifies that SIP message is conveying location information. [RFC6442] specifies
SIP intermediaries should not add locationValues to a SIP request that SIP intermediaries should not add locationValues to a SIP
that already contains locationValue. [RFC6442] also states that if a request that already contains a locationValue. [RFC6442] also states
SIP intermediary adds location it is fully responsible for addressing that if a SIP intermediary adds location, it is fully responsible for
the concerns of any 424 (Bad Location Information) SIP response it addressing the concerns of any 424 (Bad Location Information) SIP
receives. However, some communications architectures, such as 3GPP response it receives. However, some communications architectures,
[TS23-167] and ETSI [M493], prefer to use information provided by such as 3GPP [TS23-167] and ETSI [M493], prefer to use information
edge proxies or acquired through the use of core-network nodes, provided by edge proxies or acquired through the use of core-network
before using information provided solely by user equipment (UE). nodes before using information provided solely by user equipment
These solutions don't preclude the use of UE-provided location but (UE). These solutions don't preclude the use of UE-provided location
require a means of being able to distinguish the identity of the node but require a means of being able to distinguish the identity of the
adding the locationValue to the SIP message from that provided by the node adding the locationValue to the SIP message from that provided
UE. by the UE.
[RFC6442] stipulates that the order of locationValues in the [RFC6442] stipulates that the order of locationValues in the
Geolocation header field is the same as the order in which they were Geolocation header field is the same as the order in which they were
added to the header field. Whilst this order provides guidance to added to the header field. Whilst this order provides guidance to
the recipient as to which values were added to the message earlier in the recipient as to which values were added to the message earlier in
the communication chain, it does not identify which node added the the communication chain, it does not identify which node added the
locationValue. Knowing the identity of the entity that added the locationValue. Knowing the identity of the entity that added the
location to the message allows the recipient to choose which location location to the message allows the recipient to choose which location
to consider first rather than relying solely on the order of the to consider first rather than relying solely on the order of the
locationValues in the Geolocation header field. locationValues in the Geolocation header field.
This document extends the Geolocation header field of [RFC6442], by This document extends the Geolocation header field of [RFC6442] by
allowing an entity adding the locationValue to identify itself using allowing an entity adding the locationValue to identify itself using
a hostname. This is done by defining a new geoloc-param header field a hostname. This is done by defining a new geoloc-param header field
parameter, "loc-src". How the entity adding the locationValue to the parameter, "loc-src". How the entity adding the locationValue to the
header field obtains the location information is out of scope of this header field obtains the location information is out of scope of this
document. Please note that the "loc-src" parameter field does not document. Please note that the "loc-src" parameter field does not
alter the subject of the locationValue. alter the subject of the locationValue.
2. Terminology 2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in
14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
3. Rationale 3. Rationale
The primary intent of the "loc-src" parameter in this specification The primary intent of the "loc-src" parameter in this specification
is for use in emergency calling. There are various architectures is for use in emergency calling. There are various architectures
defined for providing emergency calling using SIP-based messaging. defined for providing emergency calling using SIP-based messaging.
Each has its own characteristics with corresponding pros and cons. Each has its own characteristics with corresponding pros and cons.
All of them allow the UE to provide location information; however, All of them allow the UE to provide location information; however,
many also attach other sources of location information to support many also attach other sources of location information to support
veracity checks, provide backup information, or to be used as the veracity checks, to provide backup information, or to be used as the
primary location. primary location.
This document does not comment on these various architectures or on This document does not comment on these various architectures or on
the rationale for including multiple locationValues. It does the rationale for including multiple locationValues. It does
recognize that these architectures exist and that there is a need to recognize that these architectures exist and that there is a need to
identify the entity adding the location information. identify the entity adding the location information.
The "loc-src" parameter adds the location source generating the The "loc-src" parameter adds the location source generating the
locationValue to allow recipients to make informed decisions about locationValue to allow recipients to make informed decisions about
which of multiple values to use. which of the multiple values to use.
The "loc-src" parameter is applicable within a single private The "loc-src" parameter is applicable within a single private
administrative domain or between different administrative domains administrative domain or between different administrative domains
where there is a trust relationship between the domains. Thus it is where there is a trust relationship between the domains. Thus, it is
intended to use this parameter only in trust domains where Spec(T) as intended to use this parameter only in trust domains where Spec(T) as
described in [RFC3325] exists. described in [RFC3325] exists.
The "loc-src" parameter is not included in a SIP message sent to The "loc-src" parameter is not included in a SIP message sent to
another network if there is no trust relationship. The "loc-src" another network if there is no trust relationship. The "loc-src"
parameter is not applicable if the administrative domain manages parameter is not applicable if the administrative domain manages
emergency calls in a way that does not require any generation of the emergency calls in a way that does not require any generation of the
location. location.
The functional architecture to support emergency caller location The functional architecture to support emergency caller location
skipping to change at page 5, line 6 skipping to change at line 161
4. Mechanism 4. Mechanism
The mechanism adds a geoloc-param parameter to the locationValue The mechanism adds a geoloc-param parameter to the locationValue
defined in [RFC6442] that identifies the hostname of the entity defined in [RFC6442] that identifies the hostname of the entity
adding the locationValue to the Geolocation header field. The adding the locationValue to the Geolocation header field. The
Augmented BNF (ABNF) [RFC5234] for this parameter is shown in Augmented BNF (ABNF) [RFC5234] for this parameter is shown in
Figure 1. Figure 1.
location-source = "loc-src" EQUAL hostname location-source = "loc-src" EQUAL hostname
hostname = <defined in RFC3261> hostname = <defined in RFC 3261>
Figure 1: Location Source Figure 1: Location Source
Only a fully qualified host name is valid. The syntax does not Only a fully qualified host name is valid. The syntax does not
support IP addresses, and if an entity conforming to this support IP addresses, and if an entity conforming to this
specification receives a Geolocation header field with a "loc-src" specification receives a Geolocation header field with a "loc-src"
parameter containing an IP address, it MUST remove the parameter. parameter containing an IP address, it MUST remove the parameter.
A SIP intermediary conformant to this specification adding a A SIP intermediary conformant to this specification adding a
locationValue to a Geolocation header field SHOULD also add a "loc- locationValue to a Geolocation header field SHOULD also add a "loc-
src" header field parameter so that it is clearly identified as the src" header field parameter so that it is clearly identified as the
node adding the location. A User Agent (UA) MUST NOT insert a "loc- node adding the location. A User Agent (UA) MUST NOT insert a "loc-
src" header field parameter. If a SIP intermediary receives a src" header field parameter. If a SIP intermediary receives a
message from an untrusted source with the "loc-src" parameter set message from an untrusted source with the "loc-src" parameter set,
then it MUST remove the "loc-src" parameter before passing the then it MUST remove the "loc-src" parameter before passing the
message into a trusted network. message into a trusted network.
5. Example 5. Example
The following example shows a SIP INVITE message containing a The following example shows a SIP INVITE message containing a
Geolocation header field with two locationValues. The first Geolocation header field with two locationValues. The first
locationValue points to a PIDF-LO in the SIP body using a content- locationValue points to a Presence Information Data Format Location
indirection (cid:) URI per [RFC4483] and this is provided by the UE. Object (PIDF-LO) in the SIP body using a content-indirection (cid:)
The second locationValue is an https URI provided by a SIP URI per [RFC4483], and this is provided by the UE. The second
intermediary which identifies itself using the "loc-src" parameter. locationValue is an https URI provided by a SIP intermediary, which
identifies itself using the "loc-src" parameter.
INVITE sip:bob@biloxi.example.com SIP/2.0 INVITE sip:bob@biloxi.example.com SIP/2.0
Via: SIP/2.0/TLS pc33.atlanta.example.com;branch=z9hG4bK74bf9 Via: SIP/2.0/TLS pc33.atlanta.example.com;branch=z9hG4bK74bf9
Max-Forwards: 70 Max-Forwards: 70
To: Bob <sip:bob@biloxi.example.com> To: Bob <sip:bob@biloxi.example.com>
From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl From: Alice <sip:alice@atlanta.example.com>;tag=9fxced76sl
Call-ID: 3848276298220188511@atlanta.example.com Call-ID: 3848276298220188511@atlanta.example.com
Geolocation: <cid:target123@atlanta.example.com>, Geolocation: <cid:target123@atlanta.example.com>,
<https://lis.example.com:8222/y77syc7cuecbh>; <https://lis.example.com:8222/y77syc7cuecbh>;
loc-src=edgeproxy.example.com loc-src=edgeproxy.example.com
Geolocation-Routing: yes Geolocation-Routing: yes
Accept: application/sdp, application/pidf+xml Accept: application/sdp, application/pidf+xml
CSeq: 31862 INVITE CSeq: 31862 INVITE
Contact: <sip:alice@atlanta.example.com> Contact: <sip:alice@atlanta.example.com>
Content-Type: multipart/mixed; boundary=boundary1 Content-Type: multipart/mixed; boundary=boundary1
Content-Length: ... Content-Length: ...
Figure 2: Example Location Request (in trust domain) Figure 2: Example Location Request (in Trust Domain)
6. Privacy Considerations 6. Privacy Considerations
This document doesn't change any of the privacy considerations This document doesn't change any of the privacy considerations
described in [RFC6442]. While the addition of the "loc-src" described in [RFC6442]. While the addition of the "loc-src"
parameter identifies the entity that added the location in the parameter identifies the entity that added the location in the
signaling path, this addition provides little more exposure than signaling path, this addition provides little more exposure than
adding a proxy identity to the Record-Route header field (privacy adding a proxy identity to the Record-Route header field (privacy
defined in [RFC3323]). defined in [RFC3323]).
7. Security Considerations 7. Security Considerations
This document introduces the ability of a SIP intermediary to insert This document introduces the ability of a SIP intermediary to insert
a host name indicating that they added the specific locationValue to a host name indicating that they added the specific locationValue to
the Geolocation header field. The intent is for this field to be the Geolocation header field. The intent is for this field to be
used by the location recipient in the event that the SIP message used by the location recipient in the event that the SIP message
contains multiple locationValues. As a consequence this parameter contains multiple locationValues. As a consequence, this parameter
should only be used by the location recipient in a trusted network. should only be used by the location recipient in a trusted network.
Adding this parameter in an untrusted network serves solely to give Adding this parameter in an untrusted network serves solely to give
location information to untrusted parties, and is NOT RECOMMENDED. location information to untrusted parties and is NOT RECOMMENDED.
As already stated in [RFC6442], securing the location hop-by-hop, As already stated in [RFC6442], securing the location hop by hop,
using TLS, protects the message from eavesdropping and modification using TLS, protects the message from eavesdropping and modification
in transit, but exposes the information to all SIP intermediaries on in transit but exposes the information to all SIP intermediaries on
the path as well as the endpoint. The "loc-src" parameter is the path as well as the endpoint. The "loc-src" parameter is
applicable within a single private administrative domain or between applicable within a single private administrative domain or between
different administrative domains where there is a relationship different administrative domains where there is a relationship
between the domains. If such trust relationship is not given, it is between the domains. If such a trust relationship is not given, it
strongly recommended to delete the location information. is strongly recommended to delete the location information.
The use of this parameter is not restricted to a specific The use of this parameter is not restricted to a specific
architecture but using multiple locations and loc-src may end in architecture, but using multiple locations and loc-src may end in
compatibility issues. [RFC6442] already addresses the issue of compatibility issues. [RFC6442] already addresses the issue of
multiple locations. To avoid problems of a possible corruption of multiple locations. To avoid problems of a possible corruption of
the location information including the "loc-src" parameter when using the location information including the "loc-src" parameter when using
a untrusted relationship, it is strongly recommended to delete an untrusted relationship, it is strongly recommended to delete
location information when passed to another domain out of the trust location information when passed to another domain out of the trust
domain. domain.
8. IANA Considerations 8. IANA Considerations
8.1. Registration of loc-src parameter for Geolocation header field 8.1. Registration of "loc-src" Parameter for Geolocation Header Field
The IANA is asked to add a new SIP header field parameter for the IANA has added a new SIP header field parameter for the Geolocation
Geolocation header field in the "Header Field Parameters and header field in the "Header Field Parameters and Parameter Values"
Parameter Values" subregistry (created by [RFC3968]) of the "Session subregistry (created by [RFC3968]) of the "Session Initiation
Initiation Protocol (SIP) Parameters" registry found at Protocol (SIP) Parameters" registry found at
https://www.iana.org/assignments/sip-parameters/. <https://www.iana.org/assignments/sip-parameters/>.
Header Field: Geolocation Header Field: Geolocation
Parameter Name: loc-src Parameter Name: loc-src
Predefined Values: No Predefined Values: No
Reference: this RFC Reference: RFC 8787
9. Acknowledgements
The authors would like to thank Dale Worley, Christer Holmberg and
Jean Mahoney for their extensive review of the draft. The authors
would like to acknowledge the constructive feedback provided by Paul
Kyzivat and Robert Sparks.
10. References 9. References
10.1. Normative References 9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC3323] Peterson, J., "A Privacy Mechanism for the Session [RFC3323] Peterson, J., "A Privacy Mechanism for the Session
Initiation Protocol (SIP)", RFC 3323, Initiation Protocol (SIP)", RFC 3323,
DOI 10.17487/RFC3323, November 2002, DOI 10.17487/RFC3323, November 2002,
<https://www.rfc-editor.org/info/rfc3323>. <https://www.rfc-editor.org/info/rfc3323>.
skipping to change at page 8, line 14 skipping to change at line 303
[RFC6442] Polk, J., Rosen, B., and J. Peterson, "Location Conveyance [RFC6442] Polk, J., Rosen, B., and J. Peterson, "Location Conveyance
for the Session Initiation Protocol", RFC 6442, for the Session Initiation Protocol", RFC 6442,
DOI 10.17487/RFC6442, December 2011, DOI 10.17487/RFC6442, December 2011,
<https://www.rfc-editor.org/info/rfc6442>. <https://www.rfc-editor.org/info/rfc6442>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
10.2. Informative References 9.2. Informative References
[M493] European Telecommunications Standards Institute, [M493] European Telecommunications Standards Institute,
"Functional architecture to support European requirements "Functional architecture to support European requirements
on emergency caller location determination and transport", on emergency caller location determination and transport",
ES 203 178, V 1.1.1, February 2015. ES 203 178, V 1.1.1, February 2015.
[RFC4483] Burger, E., Ed., "A Mechanism for Content Indirection in [RFC4483] Burger, E., Ed., "A Mechanism for Content Indirection in
Session Initiation Protocol (SIP) Messages", RFC 4483, Session Initiation Protocol (SIP) Messages", RFC 4483,
DOI 10.17487/RFC4483, May 2006, DOI 10.17487/RFC4483, May 2006,
<https://www.rfc-editor.org/info/rfc4483>. <https://www.rfc-editor.org/info/rfc4483>.
[TS23-167] [TS23-167] 3rd Generation Partnership Project, "Technical
3rd Generation Partnership Project, "3rd Generation Specification Group Services and System Aspects; IP
Partnership Project; Technical Specification Group Multimedia Subsystem (IMS) emergency sessions", TS 23.167,
Services and System Aspects; IP Multimedia Subsystem (IMS) V12.1.0, March 2015.
emergency sessions", TS 23.167, V 12.1.0, March 2015.
Acknowledgements
The authors would like to thank Dale Worley, Christer Holmberg, and
Jean Mahoney for their extensive review of this document. The
authors would like to acknowledge the constructive feedback provided
by Paul Kyzivat and Robert Sparks.
Authors' Addresses Authors' Addresses
James Winterbottom James Winterbottom
Winterb Consulting Services Winterb Consulting Services
Gwynneville, NSW 2500 Gwynneville NSW 2500
AU Australia
Phone: +61 448 266004 Phone: +61 448 266004
Email: a.james.winterbottom@gmail.com Email: a.james.winterbottom@gmail.com
Roland Jesske Roland Jesske
Deutsche Telekom Deutsche Telekom
Heinrich-Hertz Str, 3-7 Heinrich-Hertz Str, 3-7
Darmstadt 64295 64295 Darmstadt
Germany Germany
Email: r.jesske@telekom.de Email: r.jesske@telekom.de
URI: www.telekom.de URI: www.telekom.de
Bruno Chatras Bruno Chatras
Orange Labs Orange Labs
44, avenue de la Republique 44, avenue de la Republique
Chatillon F-92320 F-92320 Chatillon
France France
Email: bruno.chatras@orange.com Email: bruno.chatras@orange.com
Andrew Hutton Andrew Hutton
Atos Atos
Mid City Place Mid City Place
London WC1V 6EA London
UK WC1V 6EA
United Kingdom
Email: andrew.hutton@atos.net Email: andrew.hutton@atos.net
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