draft-ietf-sipcore-locparam-05.txt   draft-ietf-sipcore-locparam-06.txt 
SIPCORE J. Winterbottom SIPCORE J. Winterbottom
Internet-Draft Winterb Consulting Services Internet-Draft Winterb Consulting Services
Updates: 6442 (if approved) R. Jesske Updates: 6442 (if approved) R. Jesske
Intended status: Standards Track Deutsche Telekom Intended status: Standards Track Deutsche Telekom
Expires: July 31, 2020 B. Chatras Expires: August 17, 2020 B. Chatras
Orange Labs Orange Labs
A. Hutton A. Hutton
Atos Atos
January 28, 2020 February 14, 2020
Location Source Parameter for the SIP Geolocation Header Field Location Source Parameter for the SIP Geolocation Header Field
draft-ietf-sipcore-locparam-05 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 Geolocation
header field can identify itself using its hostname. This document header field can identify itself using its hostname. This document
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Copyright Notice Copyright Notice
Copyright (c) 2019 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 . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Rationale . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Rationale . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . 4
5. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 5. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
6. Privacy Considerations . . . . . . . . . . . . . . . . . . . 5 6. Privacy Considerations . . . . . . . . . . . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . 6 7. Security Considerations . . . . . . . . . . . . . . . . . . . 6
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
8.1. Registration of loc-src parameter for Geolocation header 8.1. Registration of loc-src parameter for Geolocation header
field . . . . . . . . . . . . . . . . . . . . . . . . . . 6 field . . . . . . . . . . . . . . . . . . . . . . . . . . 6
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
10.1. Normative References . . . . . . . . . . . . . . . . . . 7 10.1. Normative References . . . . . . . . . . . . . . . . . . 7
10.2. Informative References . . . . . . . . . . . . . . . . . 7 10.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
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 SIP
message is conveying location information. [RFC6442] specifies that message is conveying location information. [RFC6442] specifies that
SIP intermediaries should not add locationValues to a SIP request SIP intermediaries should not add locationValues to a SIP request
that already contains locationValue. [RFC6442] also states that if a that already contains locationValue. [RFC6442] also states that if a
SIP intermediary adds location it is fully responsible for addressing SIP intermediary adds location it is fully responsible for addressing
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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 identity 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. document. Please note that the "loc-src" parameter field does not
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 BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 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 it 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, 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.
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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 described within ETSI [M493] is an The functional architecture to support emergency caller location
example of an architecture where it makes sense to use this described within ETSI [M493] is an example of an architecture where
parameter. it makes sense to use this parameter.
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 RFC3261>
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 then the parameter MUST be parameter containing an IP address, it MUST remove the parameter.
removed.
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.
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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. 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. adding a proxy identity to the Record-Route header field (privacy
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
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 trust relationship different administrative domains where there is a relationship
between the domains. If such trust domain is not given, it is between the domains. If such trust relationship is not given, it is
strongly recommended to delete the location information. 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 with misinterpretation of the multiple locations. To avoid problems of a possible corruption of
"loc-src" parameter, the value may be removed when passed to another the location information including the "loc-src" parameter when using
a untrusted relationship, it is strongly recommended to delete
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 The IANA is asked to add a new SIP header field parameter for the
Geolocation header field in the "Header Field Parameters and Geolocation header field in the "Header Field Parameters and
Parameter Values" subregistry (created by [RFC3968]) of the "Session Parameter Values" subregistry (created by [RFC3968]) of the "Session
Initiation Protocol (SIP) Parameters" registry found at Initiation Protocol (SIP) Parameters" registry found at
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10. References 10. References
10.1. Normative References 10.1. 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
Initiation Protocol (SIP)", RFC 3323,
DOI 10.17487/RFC3323, November 2002,
<https://www.rfc-editor.org/info/rfc3323>.
[RFC3325] Jennings, C., Peterson, J., and M. Watson, "Private [RFC3325] Jennings, C., Peterson, J., and M. Watson, "Private
Extensions to the Session Initiation Protocol (SIP) for Extensions to the Session Initiation Protocol (SIP) for
Asserted Identity within Trusted Networks", RFC 3325, Asserted Identity within Trusted Networks", RFC 3325,
DOI 10.17487/RFC3325, November 2002, DOI 10.17487/RFC3325, November 2002,
<https://www.rfc-editor.org/info/rfc3325>. <https://www.rfc-editor.org/info/rfc3325>.
[RFC3968] Camarillo, G., "The Internet Assigned Number Authority [RFC3968] Camarillo, G., "The Internet Assigned Number Authority
(IANA) Header Field Parameter Registry for the Session (IANA) Header Field Parameter Registry for the Session
Initiation Protocol (SIP)", BCP 98, RFC 3968, Initiation Protocol (SIP)", BCP 98, RFC 3968,
DOI 10.17487/RFC3968, December 2004, DOI 10.17487/RFC3968, December 2004,
skipping to change at page 7, line 52 skipping to change at page 8, line 19
[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 10.2. 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, Februar 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, "3rd Generation 3rd Generation Partnership Project, "3rd Generation
Partnership Project; Technical Specification Group Partnership Project; Technical Specification Group
Services and System Aspects; IP Multimedia Subsystem (IMS) Services and System Aspects; IP Multimedia Subsystem (IMS)
 End of changes. 20 change blocks. 
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