HTTP Access Service Description Objects

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Table of Contents

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:¶

• DNS over HTTPS [RFC8484]¶
• CONNECT-UDP [I-D.draft-ietf-masque-connect-udp]¶
• CONNECT-IP [I-D.draft-ietf-masque-connect-ip]¶
• Oblivious HTTP [I-D.draft-ietf-ohai-ohttp]¶

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 "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:¶

• "proxy", containing a dictionary with a "template" key indicating the Oblivious Proxy's resource mapping. The template MUST contain a "request_uri" variable indicating the Oblivious Request Resource.¶
• "request", containing a dictionary with a "uri" key indicating the Oblivious Request Resource and a "key" key conveying its KeyConfig in base64.¶

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

{
  "dns": {
    "template": "https://doh.example.com/dns-query{?dns}",
  },
  "udp": {
    "template":
        "https://proxy.example.org/masque{?target_host,target_port}"
  },
  "ip": {
    "template": "https://proxy.example.org/masque{?target,ip_proto}"
  },
  "ohttp": {
    "proxy": {
      "template": "https://proxy.example.org/ohttp{?request_uri}"
    }
  }
}

{
  "dns": {
    "template": "https://doh.example.com/dns-query{?dns}",
  },
  "ohttp": {
    "request": {
      "uri": "https://example.com/ohttp/",
      "key": "(KeyConfig in Base64)"
    }
  }
}

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/json".¶

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

5. Security Considerations

TODO Security¶

6. IANA Considerations

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

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

Acknowledgments

TODO acknowledge.¶

Author's Address