Internet-Draft HTTP Access Descriptions July 2022
Schwartz Expires 2 January 2023 [Page]
Multiplexed Application Substrate over QUIC Encryption
Intended Status:
Standards Track
B. M. Schwartz
Google LLC

HTTP Access Service Description Objects


HTTP proxies can operate several different kinds of access services. This specification provides a format for identifying a collection of such services.

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1. Introduction

In HTTP/1.1, forward proxy service was originally defined in two ways: absolute-uri request form (encrypted at most hop-by-hop), and HTTP CONNECT (potentially encrypted end-to-end). Both of these services were effectively origin-scoped: the access service was a property of the origin, not associated with any particular path.

Recently, a variety of new standardized proxy-like services have emerged for HTTP. These new services are defined by a URI template or path, allowing distinct instances of the same service type to be served by a single origin. These services include:

This specification provides a unified format for describing a collection of such access services, and a mechanism for reaching such services when the initial information contains only an HTTP origin.

2. Conventions and Definitions

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.

3. Format

An access service collection is defined by a JSON dictionary containing keys specified in the corresponding registry (Section 6). Inclusion of each key is OPTIONAL. The corresponding media type is application/access-services+json.

The "dns", "udp", and "ip" keys are each defined to hold a JSON dictionary containing the key "template" with a value that is a URI template suitable for configuring DNS over HTTPS, CONNECT-UDP, or CONNECT-IP, respectively.

The "ohttp" key contains a dictionary with either or both of these keys:

  • "relay", containing a dictionary with a "template" key indicating the Oblivious Relay's resource mapping. The template MUST contain a "gateway_uri" variable indicating the Oblivious Gateway Resource.
  • "gateway", containing a dictionary with a "uri" key indicating the Oblivious Gateway Resource and a "key" key conveying its KeyConfig in base64.

If the Access Description is for a general-purpose proxy, all Oblivious Gateways and proxy targets (respectively) are presumed to be supported; otherwise the supported Gateways and targets must be understood from context (but see Section 4).

3.1. Examples

  "dns": {
    "template": "{?dns}",
  "udp": {
  "ip": {
    "template": "{?target,ip_proto}"
  "ohttp": {
    "relay": {
      "template": "{?gateway_uri}"
Figure 1: A proxy with UDP, IP, DNS, and Oblivious HTTP support
  "dns": {
    "template": "{?dns}",
  "ohttp": {
    "gateway": {
      "uri": "",
      "key": "(KeyConfig in Base64)"
Figure 2: An Oblivious DNS over HTTPS service

4. Discovery from an Origin

In cases where the HTTP access service is identified only by an origin (e.g. when configured as a Secure Web Proxy), operators can publish an associated access service collection at the path "/.well-known/access-services", with the Content-Type "application/access-services+json".

When the "ohttp.gateway" URI appears in an Access Description at this location, all URIs on this origin (except the Oblivious Gateway URI) are presumed to be reachable as Oblivious Targets.

Clients MAY fetch this Access Description and use the indicated services (in addition to any origin-scoped services) automatically. Clients SHOULD use the description only while it is fresh according to its HTTP cache lifetime, refreshing it as needed.

6. IANA Considerations

IANA is requested to open a Specification Required registry entitled "HTTP Access Service Descriptors", with the following initial contents:

Table 1
Key Specification
dns (This document)
udp (This document)
ip (This document)
ohttp (This document)

IANA is requested to add the following entry to the "Well-Known URIs" registry:

Table 2
URI Suffix Change Controller Reference Status Related Information
access-services IETF (This document) provisional Sub-registry at (link)

IANA is requested to add the following entry to the "application" sub-registry of the "Media Types" registry:

Table 3
Name Template Reference
access-services+json application/access-services+json (This document)
  • TODO: Full registration template for this Media Type.

7. Normative References

Pauly, T., Schinazi, D., Chernyakhovsky, A., Kuehlewind, M., and M. Westerlund, "IP Proxying Support for HTTP", Work in Progress, Internet-Draft, draft-ietf-masque-connect-ip-01, , <>.
Schinazi, D., "Proxying UDP in HTTP", Work in Progress, Internet-Draft, draft-ietf-masque-connect-udp-15, , <>.
Thomson, M. and C. A. Wood, "Oblivious HTTP", Work in Progress, Internet-Draft, draft-ietf-ohai-ohttp-01, , <>.
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <>.
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <>.
Hoffman, P. and P. McManus, "DNS Queries over HTTPS (DoH)", RFC 8484, DOI 10.17487/RFC8484, , <>.


TODO acknowledge.

Author's Address

Benjamin M. Schwartz
Google LLC