draft-ietf-sipcore-locparam-04.txt   draft-ietf-sipcore-locparam-05.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: April 10, 2020 B. Chatras Expires: July 31, 2020 B. Chatras
Orange Labs Orange Labs
A. Hutton A. Hutton
Atos Atos
October 8, 2019 January 28, 2020
Location Source Parameter for the SIP Geolocation Header Field Location Source Parameter for the SIP Geolocation Header Field
draft-ietf-sipcore-locparam-04 draft-ietf-sipcore-locparam-05
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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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
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Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
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time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 10, 2020. This Internet-Draft will expire on July 31, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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"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
the concerns of any 424 (Bad Location Information) SIP response it the concerns of any 424 (Bad Location Information) SIP response it
receives. However, some communications architectures, such as 3GPP receives. However, some communications architectures, such as 3GPP
[TS23-167] and ETSI [M493], prefer to use information provided by [TS23-167] and ETSI [M493], prefer to use information provided by
edge proxies or acquired through the use of core-network nodes, edge proxies or acquired through the use of core-network nodes,
before using information provided solely by user equipment (UE). before using information provided solely by user equipment (UE).
These solutions don't preclude the use of UE provided location but These solutions don't preclude the use of UE-provided location but
require a means of being able to distinguish the identity of the node require a means of being able to distinguish the identity of the node
adding the locationValue to the SIP message from that provided by the adding the locationValue to the SIP message from that provided by the
UE. 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, by allowing an This document extends the Geolocation header field of [RFC6442], by
entity adding the locationValue to identity itself using a hostname. allowing an entity adding the locationValue to identity itself using
This is done by defining a new geoloc-param header field parameter, a hostname. This is done by defining a new geoloc-param header field
"loc-src"."How the entity adding the locationValue to the header parameter, "loc-src". How the entity adding the locationValue to the
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.
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 it 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.
The "loc-src" parameter adds the location source generating the The "loc-src" parameter adds the location source generating the
locationValue to increase the trustworthiness of the location locationValue to allow recipients to make informed decisions about
information. which of 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
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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 then the parameter MUST be
removed. 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 UA MUST NOT insert a "loc-src" header node adding the location. A User Agent (UA) MUST NOT insert a "loc-
field parameter. If a SIP intermediary receives a message from an src" header field parameter. If a SIP intermediary receives a
untrusted source with the "loc-src" parameter set then it MUST remove message from an untrusted source with the "loc-src" parameter set
the "loc-src" parameter before passing the message into a trusted then it MUST remove the "loc-src" parameter before passing the
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 PIDF-LO in the SIP body using a content-
indirection (cid:) URI per [RFC4483] and this is provided by the UE. indirection (cid:) URI per [RFC4483] and this is provided by the UE.
The second locationValue is an https URI provided by a SIP The second locationValue is an https URI provided by a SIP
intermediary which identifies itself using the "loc-src" parameter. intermediary which identifies itself using the "loc-src" parameter.
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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.
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 trust relationship
between the domains. If such trust domain is not given it is between the domains. If such trust domain 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 multiples 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
multiples locations. To avoid problems with misinterpretation of the multiple locations. To avoid problems with misinterpretation of the
"loc-src" parameter, the value may be removed when passed to an other "loc-src" parameter, the value may be removed when passed to another
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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