Location Source Parameter for the SIP Geolocation Header Field
updates
- rfc-6442 — Location Conveyance for the Session Initiation Protocol
Extracted elements (13)
The 'loc-src' parameter is applicable only within a single private administrative domain or between domains with a trust relationship (Spec(T) per RFC 3325). It is not included in SIP messages sent to networks lacking a trust relationship.
The primary intent of the 'loc-src' parameter is for use in emergency calling. Architectures such as 3GPP and ETSI prefer location from edge proxies or core-network nodes over UE-provided location, requiring a means to distinguish which node added each locationValue. RFC 6442 ordering alone does not identify the adding node.
Using multiple locations and loc-src may create compatibility issues. RFC 6442 already addresses the issue of multiple locations, and this extension must be used carefully to avoid corruption of location information in deployments spanning multiple trust domains.
A SIP intermediary conformant to this specification adding a locationValue to a Geolocation header field SHOULD also add a 'loc-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-src' header field parameter. Only SIP intermediaries are permitted to add this parameter.
If a SIP intermediary receives a message from an untrusted source with the 'loc-src' parameter set, it MUST remove the 'loc-src' parameter before passing the message into a trusted network.
If an entity conforming to this specification receives a Geolocation header field with a 'loc-src' parameter containing an IP address, it MUST remove the parameter.
The addition of the 'loc-src' parameter identifies the entity that added the location in the signaling path, but provides little more exposure than adding a proxy identity to the Record-Route header field. No new privacy considerations beyond those in RFC 6442 are introduced.
The 'loc-src' parameter is a new geoloc-param parameter added to the locationValue defined in RFC 6442 that identifies the hostname of the SIP intermediary adding the locationValue to the Geolocation header field. Only a fully qualified host name is valid; IP addresses are not supported.
IANA registered the 'loc-src' parameter for the Geolocation header field in the 'Header Field Parameters and Parameter Values' subregistry of the 'Session Initiation Protocol (SIP) Parameters' registry. Predefined values: No.
Securing the location hop by hop using TLS protects against eavesdropping and modification in transit, but exposes the information to all SIP intermediaries on the path and the endpoint. It is strongly recommended to delete location information including the 'loc-src' parameter when passed to another domain outside the trust domain.
The 'loc-src' parameter 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.
The ABNF for the loc-src parameter is: location-source = "loc-src" EQUAL hostname, where hostname is defined in RFC 3261. Only fully qualified hostnames are permitted; IP address syntax is not supported.