RFC 8006
Content Delivery Network Interconnection (CDNI) Metadata
6. CDNI Metadata Interface
This section specifies an interface to enable a dCDN to retrieve CDNI Metadata objects from a uCDN. The interface can be used by a dCDN to retrieve CDNI Metadata objects in either of two ways: o Dynamically, as required by the dCDN to process received requests -- for example, in response to a query from a uCDN over the CDNI Request Routing Redirection interface (RI) [RFC7975] or in response to receiving a request for content from a User Agent. o In advance of being required -- for example, in the case of pre-positioned CDNI Metadata acquisition, initiated through the "CDNI Control interface / Triggers" (CI/T) interface [RFC8007]. The CDNI Metadata interface is built on the principles of HTTP web services. In particular, this means that requests and responses over the interface are built around the transfer of representations of hyperlinked resources. A resource in the context of the CDNI Metadata interface is any object in the object model (as described in Sections 3 and 4). CDNI Metadata servers (i.e., servers in the uCDN) are free to assign whatever structure they desire to the URIs for CDNI Metadata objects, and CDNI Metadata clients MUST NOT make any assumptions regarding the structure of CDNI Metadata URIs or the mapping between CDNI Metadata objects and their associated URIs. Any URIs present in the examples in this document are purely illustrative and are not intended to impose a definitive structure on CDNI Metadata interface implementations.
6.1. Transport
The CDNI Metadata interface uses HTTP as the underlying protocol transport [RFC7230]. The HTTP method in the request defines the operation the request would like to perform. A server implementation of the CDNI Metadata interface MUST support the HTTP GET and HEAD methods. The corresponding HTTP response returns the status of the operation in the HTTP status code and returns the current representation of the resource (if appropriate) in the response body. HTTP responses that contain a response body SHOULD include an entity-tag (ETag) to enable validation of cached versions of returned resources. As the CDNI Metadata interface builds on top of HTTP, CDNI Metadata server implementations MAY make use of any HTTP feature when implementing the CDNI Metadata interface; for example, a CDNI Metadata server MAY make use of HTTP's caching mechanisms to indicate that the returned response/representation can be reused without re-contacting the CDNI Metadata server.6.2. Retrieval of CDNI Metadata Resources
In the general case, a CDNI Metadata server makes CDNI Metadata objects available via unique URIs; thus, in order to retrieve CDNI Metadata, a CDNI Metadata client (i.e., a client in the dCDN) first makes an HTTP GET request for the URI of the HostIndex, which provides an array of hostnames for which the uCDN can delegate content delivery to the dCDN. In order to retrieve the CDNI Metadata for a particular request, the CDNI Metadata client processes the received HostIndex object and finds the corresponding HostMetadata entry (by matching the hostname in the request against the hostnames listed in the HostMatch objects). If the HostMetadata is linked (rather than embedded), the CDNI Metadata client then makes an HTTP GET request for the URI specified in the "href" property of the Link object, which points to the HostMetadata object itself. In order to retrieve the most specific metadata for a particular request, the CDNI Metadata client inspects the HostMetadata for references to more-specific PathMetadata objects (by matching the URI path in the request against the path-pattern property items in any PathMatch objects listed in the HostMetadata object). If a PathMetadata object is found to match (and is linked rather than embedded), the CDNI Metadata client makes another HTTP GET request for the PathMetadata. Each PathMetadata object can also include
references to additional more-specific metadata. If this is the case, the CDNI Metadata client continues requesting PathMatch and PathMetadata objects recursively. The CDNI Metadata client repeats this approach of processing metadata objects and retrieving (via HTTP GETs) any linked objects until it has all the metadata objects it requires in order to process the redirection request from the uCDN or the content request from a User Agent. In cases where a dCDN is not able to retrieve the entire set of CDNI Metadata associated with a User Agent request, or it has retrieved that metadata but it is stale according to standard HTTP caching rules and cannot be revalidated -- for example, because the uCDN is unreachable or returns an HTTP 4xx or 5xx status in response to some or all of the dCDN's CDNI Metadata requests -- the dCDN MUST NOT serve the requested content. Where a dCDN is interconnected with multiple uCDNs, the dCDN needs to determine which uCDN's CDNI Metadata interface should be used to handle a particular User Agent request. When HTTP redirection (e.g., HTTP 302 redirects) is being used between CDNs, it is expected that the dCDN will be able to determine the uCDN that redirected a particular request from information contained in the received request (e.g., via the URI). With knowledge of which uCDN routed the request, the dCDN can choose the correct uCDN from which to obtain the HostIndex. Note that the HostIndexes served by each uCDN can be unique. In the case of DNS redirection, there is not always sufficient information carried in the DNS request from User Agents to determine the uCDN that redirected a particular request (e.g., when content from a given host is redirected to a given dCDN by more than one uCDN); therefore, dCDNs will have to apply local policy when deciding which uCDN's CDNI Metadata interface to use.6.3. Bootstrapping
The URI for the HostIndex object of a given uCDN needs to be configured in the dCDN. All other objects/resources are then discoverable from the HostIndex object by following any links in the HostIndex object, and through the referenced HostMetadata and PathMetadata objects and their GenericMetadata sub-objects. Manual configuration of the URI for the HostIndex object is outside the scope of this document.
6.4. Encoding
CDNI Metadata objects MUST be encoded as I-JSON objects [RFC7493] containing a dictionary of (key,value) pairs where the keys are the property names and the values are the associated property values. The keys of the dictionary are the names of the properties associated with the object and are therefore dependent on the specific object being encoded (i.e., dependent on the CDNI Payload Type of the returned resource). Likewise, the values associated with each property (dictionary key) are dependent on the specific object being encoded (i.e., dependent on the CDNI Payload Type of the returned resource). Dictionary keys (properties) in I-JSON are case sensitive. By convention, any dictionary key (property) defined by this document (for example, the names of CDNI Metadata object properties) MUST be lowercase.6.5. Extensibility
The set of GenericMetadata objects can be extended with additional (standards-based or vendor-specific) metadata objects through the specification of new GenericMetadata objects. The GenericMetadata object defined in Section 4.1.7 specifies a type field and a type- specific value field that allow any metadata to be included in either the HostMetadata or PathMetadata arrays. As with the initial GenericMetadata types defined in Section 4.2, future GenericMetadata types MUST specify the information necessary for constructing and decoding the GenericMetadata object. Any document that defines a new GenericMetadata type MUST: 1. Register the CDNI Payload Type [RFC7736] used to identify the new GenericMetadata type being specified. 2. Define the set of properties associated with the new GenericMetadata object. GenericMetadata MUST NOT contain a property named "href" because doing so would conflict with the ability to detect Link objects (see Section 4.3.1). 3. For each property, define a name, description, type, and whether or not the property is mandatory-to-specify. 4. Describe the semantics of the new type, including its purpose, and provide a use case to which it applies, including an example encoded in I-JSON.
5. Describe the security and privacy consequences, for both the User
Agent and the CDNs, of the new GenericMetadata object.
6. Describe any relation to, conflict with, or obsolescence of other
existing CDNI Metadata objects.
Note: In the case of vendor-specific extensions, vendor-identifying
CDNI Payload Type names will decrease the possibility of
GenericMetadata type collisions. It is RECOMMENDED that any
vendor-specific extensions use vendor-identifying CDNI Payload Type
names.
6.6. Metadata Enforcement
At any given time, the set of GenericMetadata types supported by the
uCDN might not match the set of GenericMetadata types supported by
the dCDN.
In cases where a uCDN sends metadata containing a GenericMetadata
type that a dCDN does not support, the dCDN MUST enforce the
semantics of the mandatory-to-enforce property. If a dCDN does not
understand or is unable to perform the functions associated with any
mandatory-to-enforce metadata, the dCDN MUST NOT service any requests
for the corresponding content.
Note: Ideally, uCDNs would not delegate content requests to a dCDN
that does not support the mandatory-to-enforce metadata associated
with the content being requested. However, even if the uCDN has
a priori knowledge of the metadata supported by the dCDN (e.g., via
the FCI or through out-of-band negotiation between CDN operators),
metadata support can fluctuate or be inconsistent (e.g., due to
miscommunication, misconfiguration, or temporary outage). Thus, the
dCDN MUST always evaluate all metadata associated with redirection
and content requests and reject any requests where
mandatory-to-enforce metadata associated with the content cannot be
enforced.
6.7. Metadata Conflicts
It is possible that new metadata definitions will obsolete or
conflict with existing GenericMetadata (e.g., a future revision of
the CDNI Metadata interface could redefine the Auth GenericMetadata
object or a custom vendor extension could implement an alternate Auth
metadata option). If multiple metadata (e.g., MI.Auth.v2,
vendor1.Auth, and vendor2.Auth) all conflict with an existing
GenericMetadata object (i.e., MI.Auth) and all are marked as
mandatory-to-enforce, it could be ambiguous as to which metadata should be applied, especially in the case of overlapping functionality. As described in Section 3.3, metadata override only applies to metadata objects of the same exact type found in HostMetadata and nested PathMetadata structures. The CDNI Metadata interface does not support enforcement of dependencies between different GenericMetadata types. It is the responsibility of the CSP and the CDN operators to ensure that metadata assigned to a given piece of content do not conflict. Note: Because metadata is inherently ordered in HostMetadata and PathMetadata arrays, as well as in the PathMatch hierarchy, multiple conflicting metadata types MAY be used; however, metadata hierarchies SHOULD ensure that independent PathMatch root objects are used to prevent ambiguous or conflicting metadata definitions.6.8. Versioning
The version of CDNI Metadata objects is conveyed inside the CDNI Payload Type that is included in either (1) the HTTP Content-Type header (for example, "Content-Type: application/cdni; ptype=MI.HostIndex" when retrieved via a link) or (2) in the link type (Section 4.3.1), generic-metadata-type (Section 4.1.7), or auth-type (Section 4.2.7) properties in the JSON payload. The CDNI Payload Type uniquely identifies the specification defining that object, including any relation to, conflicts with, or obsolescence of other metadata. There is no explicit version mapping requirement; however, for ease of understanding, metadata creators SHOULD make new versions of metadata easily visible via the CDNI Payload Type, e.g., by appending a version string. Note: A version string is optional on the first version (e.g., MI.HostIndex) but could be added for subsequent versions (MI.HostIndex.v2, MI.HostIndex.v3, etc.). Except when referenced by a Link object, nested metadata objects (i.e., structural metadata below the HostIndex; and Source, LocationRule, TimeWindowRule, ProtocolRule, Footprint, and TimeWindow objects) can be serialized into a JSON payload without explicit CDNI Payload Type information. The type is inferred from the outer structural metadata, GenericMetadata, or Auth object CDNI Payload Type. To avoid ambiguity when revising nestable metadata objects, any outer metadata object(s) MUST be reversioned and allocated new CDNI Payload Type(s) at the same time. For example, the MI.HostIndex object defined in this document contains an array of MI.HostMatch objects, each of which in turn contains a MI.HostMetadata object. If a new MI.HostMetadata.v2 object were required, the outer MI.HostIndex and MI.HostMatch objects would need to be revised, e.g., to
MI.HostIndex.v2 and MI.HostMatch.v2, respectively. Similarly, if a new MI.TimeWindowRule.v2 object were required, the outer MI.TimeWindowACL object would need to be revised, e.g., to MI.TimeWindowACL.v2; however, the MI.TimeWindowRule.v2 object could still contain MI.TimeWindow objects, if so specified. HTTP requests sent to a metadata server SHOULD include an Accept header with the CDNI Payload Type of the expected object. Metadata clients can specify multiple CDNI Payload Types in the Accept header; for example, if a metadata client is capable of processing two different versions of the same type of object (defined by different CDNI Payload Types), it might decide to include both in the Accept header.6.9. Media Types
All CDNI Metadata objects use the media type "application/cdni". The CDNI Payload Type for each object then contains the object name of that object as defined by this document, prefixed with "MI.". Table 4 lists the CDNI Payload Types for the metadata objects (resources) specified in this document. +-----------------------+--------------------------+ | Data Object | CDNI Payload Type | +-----------------------+--------------------------+ | HostIndex | MI.HostIndex | | HostMatch | MI.HostMatch | | HostMetadata | MI.HostMetadata | | PathMatch | MI.PathMatch | | PatternMatch | MI.PatternMatch | | PathMetadata | MI.PathMetadata | | SourceMetadata | MI.SourceMetadata | | Source | MI.Source | | LocationACL | MI.LocationACL | | LocationRule | MI.LocationRule | | Footprint | MI.Footprint | | TimeWindowACL | MI.TimeWindowACL | | TimeWindowRule | MI.TimeWindowRule | | TimeWindow | MI.TimeWindow | | ProtocolACL | MI.ProtocolACL | | ProtocolRule | MI.ProtocolRule | | DeliveryAuthorization | MI.DeliveryAuthorization | | Cache | MI.Cache | | Auth | MI.Auth | | Grouping | MI.Grouping | +-----------------------+--------------------------+ Table 4: CDNI Payload Types for CDNI Metadata Objects
6.10. Complete CDNI Metadata Example
A dCDN requests the HostIndex and receives the following object with a CDNI Payload Type of "MI.HostIndex": { "hosts": [ { "host": "video.example.com", "host-metadata": { "type": "MI.HostMetadata", "href": "https://metadata.ucdn.example/host1234" } }, { "host": "images.example.com", "host-metadata": { "type": "MI.HostMetadata", "href": "https://metadata.ucdn.example/host5678" } } ] } If the incoming request has a Host header with "video.example.com", then the dCDN would fetch the HostMetadata object from "https://metadata.ucdn.example/host1234" expecting a CDNI Payload Type of "MI.HostMetadata": { "metadata": [ { "generic-metadata-type": "MI.SourceMetadata", "generic-metadata-value": { "sources": [ { "endpoint": ["acq1.ucdn.example"], "protocol": "http/1.1" }, { "endpoint": ["acq2.ucdn.example"], "protocol": "http/1.1" } ] } },
{
"generic-metadata-type": "MI.LocationACL",
"generic-metadata-value": {
"locations": [
{
"footprints": [
{
"footprint-type": "ipv4cidr",
"footprint-value": ["192.0.2.0/24"]
},
{
"footprint-type": "ipv6cidr",
"footprint-value": ["2001:db8::/32"]
},
{
"footprint-type": "countrycode",
"footprint-value": ["us"]
},
{
"footprint-type": "asn",
"footprint-value": ["as64496"]
}
],
"action": "deny"
}
]
}
},
{
"generic-metadata-type": "MI.ProtocolACL",
"generic-metadata-value": {
"protocol-acl": [
{
"protocols": [
"http/1.1"
],
"action": "allow"
}
]
}
}
],
"paths": [
{
"path-pattern": {
"pattern": "/videos/trailers/*"
},
"path-metadata": {
"type": "MI.PathMetadata",
"href": "https://metadata.ucdn.example/host1234/pathABC"
}
},
{
"path-pattern": {
"pattern": "/videos/movies/*"
},
"path-metadata": {
"type": "MI.PathMetadata",
"href": "https://metadata.ucdn.example/host1234/pathDEF"
}
}
]
}
Suppose that the path of the requested resource matches the
"/videos/movies/*" pattern; the next metadata requested would be for
"https://metadata.ucdn.example/host1234/pathDEF" with an expected
CDNI Payload Type of "MI.PathMetadata":
{
"metadata": [],
"paths": [
{
"path-pattern": {
"pattern": "/videos/movies/hd/*"
},
"path-metadata": {
"type": "MI.PathMetadata",
"href":
"https://metadata.ucdn.example/host1234/pathDEF/path123"
}
}
]
}
Finally, if the path of the requested resource also matches the
"/videos/movies/hd/*" pattern, the dCDN would also fetch the
following object from
"https://metadata.ucdn.example/host1234/pathDEF/path123" with a CDNI
Payload Type of "MI.PathMetadata":
{
"metadata": [
{
"generic-metadata-type": "MI.TimeWindowACL",
"generic-metadata-value": {
"times": [
"windows": [
{
"start": "1213948800",
"end": "1478047392"
}
],
"action": "allow"
]
}
}
]
}
The final set of metadata that applies to the requested resource
includes a SourceMetadata, a LocationACL, a ProtocolACL, and a
TimeWindowACL.
7. IANA Considerations
7.1. CDNI Payload Types
This document requests the registration of the following entries under the "CDNI Payload Types" registry hosted by IANA: +--------------------------+---------------+ | Payload Type | Specification | +--------------------------+---------------+ | MI.HostIndex | RFC 8006 | | MI.HostMatch | RFC 8006 | | MI.HostMetadata | RFC 8006 | | MI.PathMatch | RFC 8006 | | MI.PatternMatch | RFC 8006 | | MI.PathMetadata | RFC 8006 | | MI.SourceMetadata | RFC 8006 | | MI.Source | RFC 8006 | | MI.LocationACL | RFC 8006 | | MI.LocationRule | RFC 8006 | | MI.Footprint | RFC 8006 | | MI.TimeWindowACL | RFC 8006 | | MI.TimeWindowRule | RFC 8006 | | MI.TimeWindow | RFC 8006 | | MI.ProtocolACL | RFC 8006 | | MI.ProtocolRule | RFC 8006 | | MI.DeliveryAuthorization | RFC 8006 | | MI.Cache | RFC 8006 | | MI.Auth | RFC 8006 | | MI.Grouping | RFC 8006 | +--------------------------+---------------+7.1.1. CDNI MI HostIndex Payload Type
Purpose: The purpose of this Payload Type is to distinguish HostIndex MI objects (and any associated capability advertisement) Interface: MI/FCI Encoding: see Section 4.1.1
7.1.2. CDNI MI HostMatch Payload Type
Purpose: The purpose of this Payload Type is to distinguish HostMatch MI objects (and any associated capability advertisement) Interface: MI/FCI Encoding: see Section 4.1.27.1.3. CDNI MI HostMetadata Payload Type
Purpose: The purpose of this Payload Type is to distinguish HostMetadata MI objects (and any associated capability advertisement) Interface: MI/FCI Encoding: see Section 4.1.37.1.4. CDNI MI PathMatch Payload Type
Purpose: The purpose of this Payload Type is to distinguish PathMatch MI objects (and any associated capability advertisement) Interface: MI/FCI Encoding: see Section 4.1.47.1.5. CDNI MI PatternMatch Payload Type
Purpose: The purpose of this Payload Type is to distinguish PatternMatch MI objects (and any associated capability advertisement) Interface: MI/FCI Encoding: see Section 4.1.57.1.6. CDNI MI PathMetadata Payload Type
Purpose: The purpose of this Payload Type is to distinguish PathMetadata MI objects (and any associated capability advertisement) Interface: MI/FCI Encoding: see Section 4.1.6
7.1.7. CDNI MI SourceMetadata Payload Type
Purpose: The purpose of this Payload Type is to distinguish SourceMetadata MI objects (and any associated capability advertisement) Interface: MI/FCI Encoding: see Section 4.2.17.1.8. CDNI MI Source Payload Type
Purpose: The purpose of this Payload Type is to distinguish Source MI objects (and any associated capability advertisement) Interface: MI/FCI Encoding: see Section 4.2.1.17.1.9. CDNI MI LocationACL Payload Type
Purpose: The purpose of this Payload Type is to distinguish LocationACL MI objects (and any associated capability advertisement) Interface: MI/FCI Encoding: see Section 4.2.27.1.10. CDNI MI LocationRule Payload Type
Purpose: The purpose of this Payload Type is to distinguish LocationRule MI objects (and any associated capability advertisement) Interface: MI/FCI Encoding: see Section 4.2.2.17.1.11. CDNI MI Footprint Payload Type
Purpose: The purpose of this Payload Type is to distinguish Footprint MI objects (and any associated capability advertisement) Interface: MI/FCI Encoding: see Section 4.2.2.2
7.1.12. CDNI MI TimeWindowACL Payload Type
Purpose: The purpose of this Payload Type is to distinguish TimeWindowACL MI objects (and any associated capability advertisement) Interface: MI/FCI Encoding: see Section 4.2.37.1.13. CDNI MI TimeWindowRule Payload Type
Purpose: The purpose of this Payload Type is to distinguish TimeWindowRule MI objects (and any associated capability advertisement) Interface: MI/FCI Encoding: see Section 4.2.3.17.1.14. CDNI MI TimeWindow Payload Type
Purpose: The purpose of this Payload Type is to distinguish TimeWindow MI objects (and any associated capability advertisement) Interface: MI/FCI Encoding: see Section 4.2.3.27.1.15. CDNI MI ProtocolACL Payload Type
Purpose: The purpose of this Payload Type is to distinguish ProtocolACL MI objects (and any associated capability advertisement) Interface: MI/FCI Encoding: see Section 4.2.47.1.16. CDNI MI ProtocolRule Payload Type
Purpose: The purpose of this Payload Type is to distinguish ProtocolRule MI objects (and any associated capability advertisement) Interface: MI/FCI Encoding: see Section 4.2.4.1
7.1.17. CDNI MI DeliveryAuthorization Payload Type
Purpose: The purpose of this Payload Type is to distinguish DeliveryAuthorization MI objects (and any associated capability advertisement) Interface: MI/FCI Encoding: see Section 4.2.57.1.18. CDNI MI Cache Payload Type
Purpose: The purpose of this Payload Type is to distinguish Cache MI objects (and any associated capability advertisement) Interface: MI/FCI Encoding: see Section 4.2.67.1.19. CDNI MI Auth Payload Type
Purpose: The purpose of this Payload Type is to distinguish Auth MI objects (and any associated capability advertisement) Interface: MI/FCI Encoding: see Section 4.2.77.1.20. CDNI MI Grouping Payload Type
Purpose: The purpose of this Payload Type is to distinguish Grouping MI objects (and any associated capability advertisement) Interface: MI/FCI Encoding: see Section 4.2.87.2. "CDNI Metadata Footprint Types" Registry
IANA has created a new "CDNI Metadata Footprint Types" subregistry in the "Content Delivery Network Interconnection (CDNI) Parameters" registry. The "CDNI Metadata Footprint Types" namespace defines the valid Footprint object type values used by the Footprint object described in Section 4.2.2.2. Additions to the "CDNI Metadata Footprint Types" namespace conform to the Specification Required policy as defined in [RFC5226]. The Designated Expert will verify that new type definitions do not duplicate existing type definitions
and prevent gratuitous additions to the namespace. New registrations are required to provide a clear description of how to interpret new footprint types. The following table defines the initial values for the "CDNI Metadata Footprint Types" registry: +----------------+--------------------------------+---------------+ | Footprint Type | Description | Specification | +----------------+--------------------------------+---------------+ | ipv4cidr | IPv4 CIDR address block | RFC 8006 | | ipv6cidr | IPv6 CIDR address block | RFC 8006 | | asn | Autonomous System Number (ASN) | RFC 8006 | | countrycode | ISO 3166-1 alpha-2 code | RFC 8006 | +----------------+--------------------------------+---------------+7.3. "CDNI Metadata Protocol Types" Registry
IANA has created a new "CDNI Metadata Protocol Types" subregistry in the "Content Delivery Network Interconnection (CDNI) Parameters" registry. The "CDNI Metadata Protocol Types" namespace defines the valid Protocol object values (Section 4.3.2) used by the SourceMetadata and ProtocolACL objects. Additions to the Protocol namespace conform to the Specification Required policy as defined in [RFC5226], where the specification defines the Protocol Type and the protocol to which it is associated. The Designated Expert will verify that new protocol definitions do not duplicate existing protocol definitions and prevent gratuitous additions to the namespace. The following table defines the initial Protocol values corresponding to the HTTP and HTTPS protocols: +-----------+----------------------+---------------+----------------+ | Protocol | Description | Type | Protocol | | Type | | Specification | Specifications | +-----------+----------------------+---------------+----------------+ | http/1.1 | Hypertext Transfer | RFC 8006 | RFC 7230 | | | Protocol -- HTTP/1.1 | | | | | | | | | https/1.1 | HTTP/1.1 over TLS | RFC 8006 | RFC 7230, | | | | | RFC 2818 | +-----------+----------------------+---------------+----------------+
8. Security Considerations
8.1. Authentication and Integrity
A malicious metadata server, proxy server, or attacker impersonating an authentic uCDN CDNI Metadata interface without being detected could provide false metadata to a dCDN that either: o Denies service for one or more pieces of content to one or more User Agents; o Directs dCDNs to contact malicious origin servers instead of the actual origin servers, so that malware or slanderous alternate content may be substituted for legitimate content; or o Removes delivery restrictions (e.g., LocationACL, TimeWindowACL, ProtocolACL, or Auth metadata), allowing access to content that would otherwise be denied and thus possibly violating license restrictions and incurring unwarranted delivery costs. Unauthorized access to metadata could also enable a malicious metadata client to continuously issue metadata requests in order to overload a uCDN's metadata server or servers. Unauthorized access to metadata could further result in leakage of private information. A malicious metadata client could request metadata in order to gain access to origin servers, as well as information pertaining to content restrictions. An implementation of the CDNI Metadata interface MUST use mutual authentication and message authentication codes to prevent unauthorized access to, and undetected modification of, metadata (see Section 8.3).8.2. Confidentiality and Privacy
Unauthorized viewing of metadata could result in leakage of private information. Content provider origin and policy information is conveyed through the CDNI Metadata interface. A third party could intercept metadata transactions in order to gain access to origin servers, as well as information pertaining to content restrictions and usage patterns.
Note: The distribution of metadata by a uCDN to dCDNs could introduce privacy concerns for some content providers, e.g., dCDNs accepting content requests for a content provider's content might be able to obtain additional information and usage patterns relating to the users of a content provider's services. Content providers with concerns about divulging information to dCDNs can instruct their uCDN partners not to use CDNI when delivering their content. An implementation of the CDNI Metadata interface MUST use strong encryption to prevent unauthorized interception or monitoring of metadata (see Section 8.3).8.3. Securing the CDNI Metadata Interface
An implementation of the CDNI Metadata interface MUST support TLS transport as per [RFC2818] and [RFC7230]. TLS MUST be used by the server side (uCDN) and the client side (dCDN) of the CDNI Metadata interface, including authentication of the remote end, unless alternate methods are used for ensuring the security of the information in the CDNI Metadata interface requests and responses (such as setting up an IPsec tunnel between the two CDNs or using a physically secured internal network between two CDNs that are owned by the same corporate entity). The use of TLS for transport of the CDNI Metadata interface messages allows the dCDN and uCDN to authenticate each other. Once the dCDN and uCDN have mutually authenticated each other, TLS allows: o The dCDN and uCDN to authorize each other (to ensure that they are transmitting/receiving CDNI Metadata requests and responses from an authorized CDN); o CDNI Metadata interface requests and responses to be transmitted with confidentiality; and o The integrity of the CDNI Metadata interface requests and responses to be protected during the exchange. When TLS is used, the general TLS usage guidance in [RFC7525] MUST be followed.
9. References
9.1. Normative References
[ISO3166-1] The International Organization for Standardization, "Codes for the representation of names of countries and their subdivisions -- Part 1: Country codes", ISO 3166-1:2013, 2013. [POSIX] Institute of Electrical and Electronics Engineers, "Information Technology Portable Operating System Interface (POSIX) Part 1: System Application Program Interface (API) [C Language]", IEEE P1003.1, 1990. [RFC1034] Mockapetris, P., "Domain names - concepts and facilities", STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987, <http://www.rfc-editor.org/info/rfc1034>. [RFC1123] Braden, R., Ed., "Requirements for Internet Hosts - Application and Support", STD 3, RFC 1123, DOI 10.17487/RFC1123, October 1989, <http://www.rfc-editor.org/info/rfc1123>. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <http://www.rfc-editor.org/info/rfc2119>. [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, DOI 10.17487/RFC3986, January 2005, <http://www.rfc-editor.org/info/rfc3986>. [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing Architecture", RFC 4291, DOI 10.17487/RFC4291, February 2006, <http://www.rfc-editor.org/info/rfc4291>. [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 5226, DOI 10.17487/RFC5226, May 2008, <http://www.rfc-editor.org/info/rfc5226>. [RFC5890] Klensin, J., "Internationalized Domain Names for Applications (IDNA): Definitions and Document Framework", RFC 5890, DOI 10.17487/RFC5890, August 2010, <http://www.rfc-editor.org/info/rfc5890>.
[RFC5891] Klensin, J., "Internationalized Domain Names in Applications (IDNA): Protocol", RFC 5891, DOI 10.17487/RFC5891, August 2010, <http://www.rfc-editor.org/info/rfc5891>. [RFC5952] Kawamura, S. and M. Kawashima, "A Recommendation for IPv6 Address Text Representation", RFC 5952, DOI 10.17487/RFC5952, August 2010, <http://www.rfc-editor.org/info/rfc5952>. [RFC6707] Niven-Jenkins, B., Le Faucheur, F., and N. Bitar, "Content Distribution Network Interconnection (CDNI) Problem Statement", RFC 6707, DOI 10.17487/RFC6707, September 2012, <http://www.rfc-editor.org/info/rfc6707>. [RFC7230] Fielding, R., Ed., and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing", RFC 7230, DOI 10.17487/RFC7230, June 2014, <http://www.rfc-editor.org/info/rfc7230>. [RFC7493] Bray, T., Ed., "The I-JSON Message Format", RFC 7493, DOI 10.17487/RFC7493, March 2015, <http://www.rfc-editor.org/info/rfc7493>. [RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre, "Recommendations for Secure Use of Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May 2015, <http://www.rfc-editor.org/info/rfc7525>.9.2. Informative References
[CDNI-URI-SIGNING] van Brandenburg, R., Leung, K., Sorber, P., and M. Miller, "URI Signing for CDN Interconnection (CDNI)", Work in Progress, draft-ietf-cdni-uri-signing-10, October 2016. [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, DOI 10.17487/RFC2818, May 2000, <http://www.rfc-editor.org/info/rfc2818>. [RFC6793] Vohra, Q. and E. Chen, "BGP Support for Four-Octet Autonomous System (AS) Number Space", RFC 6793, DOI 10.17487/RFC6793, December 2012, <http://www.rfc-editor.org/info/rfc6793>.
[RFC7234] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Caching", RFC 7234, DOI 10.17487/RFC7234, June 2014, <http://www.rfc-editor.org/info/rfc7234>. [RFC7336] Peterson, L., Davie, B., and R. van Brandenburg, Ed., "Framework for Content Distribution Network Interconnection (CDNI)", RFC 7336, DOI 10.17487/RFC7336, August 2014, <http://www.rfc-editor.org/info/rfc7336>. [RFC7337] Leung, K., Ed., and Y. Lee, Ed., "Content Distribution Network Interconnection (CDNI) Requirements", RFC 7337, DOI 10.17487/RFC7337, August 2014, <http://www.rfc-editor.org/info/rfc7337>. [RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext Transfer Protocol Version 2 (HTTP/2)", RFC 7540, DOI 10.17487/RFC7540, May 2015, <http://www.rfc-editor.org/info/rfc7540>. [RFC7736] Ma, K., "Content Delivery Network Interconnection (CDNI) Media Type Registration", RFC 7736, DOI 10.17487/RFC7736, December 2015, <http://www.rfc-editor.org/info/rfc7736>. [RFC7975] Niven-Jenkins, B., Ed., and R. van Brandenburg, Ed., "Request Routing Redirection Interface for Content Delivery Network (CDN) Interconnection", RFC 7975, DOI 10.17487/RFC7975, October 2016, <http://www.rfc-editor.org/info/rfc7975>. [RFC8007] Murray, R. and B. Niven-Jenkins, "Content Delivery Network Interconnection (CDNI) Control Interface / Triggers", RFC 8007, DOI 10.17487/RFC8007, December 2016, <http://www.rfc-editor.org/info/rfc8007>. [RFC8008] Seedorf, J., Peterson, J., Previdi, S., van Brandenburg, R., and K. Ma, "Content Delivery Network Interconnection (CDNI) Request Routing: Footprint and Capabilities Semantics", RFC 8008, DOI 10.17487/RFC8008, December 2016, <http://www.rfc-editor.org/info/rfc8008>.
Acknowledgments
The authors would like to thank David Ferguson, Francois Le Faucheur, Jan Seedorf, and Matt Miller for their valuable comments and input to this document.Contributors
The authors would also like to thank Grant Watson and Kent Leung for their contributions to this document.
Authors' Addresses
Ben Niven-Jenkins Nokia 3 Ely Road Milton, Cambridge CB24 6DD United Kingdom Email: ben.niven-jenkins@nokia.com Rob Murray Nokia 3 Ely Road Milton, Cambridge CB24 6DD United Kingdom Email: rob.murray@nokia.com Matt Caulfield Cisco Systems 1414 Massachusetts Avenue Boxborough, MA 01719 United States of America Phone: +1-978-936-9307 Email: mcaulfie@cisco.com Kevin J. Ma Ericsson 43 Nagog Park Acton, MA 01720 United States of America Phone: +1 978-844-5100 Email: kevin.j.ma@ericsson.com