idnits 2.17.1 draft-geohash-hint-00.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (19 February 2021) is 1159 days in the past. Is this intentional? Checking references for intended status: Experimental ---------------------------------------------------------------------------- == Outdated reference: A later version (-08) exists of draft-ietf-httpbis-proxy-status-02 Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group T. Pauly 3 Internet-Draft Apple Inc. 4 Intended status: Experimental 19 February 2021 5 Expires: 23 August 2021 7 The Geohash HTTP Client Hint 8 draft-geohash-hint-00 10 Abstract 12 This documents defines an HTTP Client Hint for sharing a client's 13 rough location using the Geohash format. 15 Discussion Venues 17 This note is to be removed before publishing as an RFC. 19 Source for this draft and an issue tracker can be found at 20 https://github.com/tfpauly/privacy-proxy. 22 Status of This Memo 24 This Internet-Draft is submitted in full conformance with the 25 provisions of BCP 78 and BCP 79. 27 Internet-Drafts are working documents of the Internet Engineering 28 Task Force (IETF). Note that other groups may also distribute 29 working documents as Internet-Drafts. The list of current Internet- 30 Drafts is at https://datatracker.ietf.org/drafts/current/. 32 Internet-Drafts are draft documents valid for a maximum of six months 33 and may be updated, replaced, or obsoleted by other documents at any 34 time. It is inappropriate to use Internet-Drafts as reference 35 material or to cite them other than as "work in progress." 37 This Internet-Draft will expire on 23 August 2021. 39 Copyright Notice 41 Copyright (c) 2021 IETF Trust and the persons identified as the 42 document authors. All rights reserved. 44 This document is subject to BCP 78 and the IETF Trust's Legal 45 Provisions Relating to IETF Documents (https://trustee.ietf.org/ 46 license-info) in effect on the date of publication of this document. 47 Please review these documents carefully, as they describe your rights 48 and restrictions with respect to this document. Code Components 49 extracted from this document must include Simplified BSD License text 50 as described in Section 4.e of the Trust Legal Provisions and are 51 provided without warranty as described in the Simplified BSD License. 53 Table of Contents 55 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 56 1.1. Requirements . . . . . . . . . . . . . . . . . . . . . . 3 57 2. Geohash Header . . . . . . . . . . . . . . . . . . . . . . . 3 58 3. Server Behavior . . . . . . . . . . . . . . . . . . . . . . . 3 59 3.1. Proxy Behavior . . . . . . . . . . . . . . . . . . . . . 4 60 4. Security Considerations . . . . . . . . . . . . . . . . . . . 4 61 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 62 5.1. HTTP Headers . . . . . . . . . . . . . . . . . . . . . . 4 63 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 64 6.1. Normative References . . . . . . . . . . . . . . . . . . 4 65 6.2. Informative References . . . . . . . . . . . . . . . . . 5 66 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5 68 1. Introduction 70 HTTP Client Hints [RFC8942] defines a convention for HTTP headers to 71 communicate optional information from clients to servers as hints. 72 This can be done conditionally based on if a server claims supports 73 for a particular hint. 75 This document defines a client hint that can be used to send a 76 location that the client wants to use for influencing server 77 behavior. It uses the Geohash algorithm [GEOHASH] to encode latitude 78 and longitude coordinates into an alphanumeric token that can be 79 truncated to provide a less specific location. 81 This header is intended to be used to provide rough geolocation hints 82 to servers in situations where the server cannot directly ascertain 83 the location of the client. For example, a client that is accessing 84 a server through a proxy or a VPN might provide a rough hint to a 85 server when looking up information that may vary depending on 86 location. 88 This document also defines a how forward proxies can use proxy status 89 fields to inform clients about the result of their Geohash hints. 91 1.1. Requirements 93 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 94 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 95 "OPTIONAL" in this document are to be interpreted as described in 96 BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all 97 capitals, as shown here. 99 2. Geohash Header 101 The "Sec-CH-Geohash" is an Item Structured Header [RFC8941]. Its 102 value MUST be a String, and MUST have at least 1 character and no 103 more than 12 characters. The ABNF is: 105 Sec-CH-Geohash = sf-string 107 The string itself is an encoded Geohash, which uses the 32 different 108 characters from the "Geohash alphabet" [GEOHASH]. 110 The following example shows an encoding of the coordinates 111 57.64911,10.40744: 113 Sec-CH-Geohash: "u4pruydqqvj" 115 Servers that can provide different content based on Geohash hints 116 SHOULD include the headers in their "Accept-CH" list. 118 Accept-CH: Sec-CH-Geohash 120 Servers also SHOULD indicate for any cacheable content if the Geohash 121 hint will influence the cached content, using the "Vary" header. 123 Vary: Sec-CH-Geohash 125 3. Server Behavior 127 Upon receiving a Geohash Client Hint, a server can use the 128 information to influence its behavior in various ways. 130 The server can use the Geohash to determine the content of HTTP 131 responses, as a replacement for inferring location from client IP 132 addresses. 134 If the server is acting as a forward proxy, such as a CONNECT proxy, 135 it can use the Geohash to determine an appropriate geo-mapped IP 136 address to use for outbound connections, or a client subnet to 137 present in the EDNS0 Client Subnet extension for DNS queries 138 [RFC6891] [RFC7871]. 140 3.1. Proxy Behavior 142 If a proxy receiving the Geohash hint cannot respect the location 143 indicated by the hint, it SHOULD include a Proxy-Status header 144 [I-D.ietf-httpbis-proxy-status] in its response, with the "details" 145 parameter containing the string "invalid geohash". 147 Proxy-Status: ExampleProxy; details="invalid geohash" 149 4. Security Considerations 151 The use of the Geohash Client Hint MUST use the Sec- header prefix as 152 recommended in [RFC8942]. 154 Client location can be used to fingerprint and tracker users, so 155 clients MUST have a default policy around when to allow use of the 156 Geohash Client Hint, as well as a default length of Geohash. 157 Shorter, truncated Geohashes provide less specific locality. 159 Servers MUST NOT use Geohash Client Hints for making security or 160 access-control decisions, as the value can be spoofed by a client. 161 The hint is intended only for use in optimizing behavior. 163 5. IANA Considerations 165 5.1. HTTP Headers 167 This document registers the "Sec-CH-Geohash" header in the "Permanent 168 Message Header Field Names" registry 169 . 171 +----------------------+----------+--------+---------------+ 172 | Header Field Name | Protocol | Status | Reference | 173 +----------------------+----------+--------+---------------+ 174 | Sec-CH-Geohash | http | exp | This document | 175 +----------------------+----------+--------+---------------+ 177 6. References 179 6.1. Normative References 181 [I-D.ietf-httpbis-proxy-status] 182 Nottingham, M. and P. Sikora, "The Proxy-Status HTTP 183 Response Header Field", Work in Progress, Internet-Draft, 184 draft-ietf-httpbis-proxy-status-02, 11 August 2020, 185 . 188 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 189 Requirement Levels", BCP 14, RFC 2119, 190 DOI 10.17487/RFC2119, March 1997, 191 . 193 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 194 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 195 May 2017, . 197 [RFC8941] Nottingham, M. and P-H. Kamp, "Structured Field Values for 198 HTTP", RFC 8941, DOI 10.17487/RFC8941, February 2021, 199 . 201 [RFC8942] Grigorik, I. and Y. Weiss, "HTTP Client Hints", RFC 8942, 202 DOI 10.17487/RFC8942, February 2021, 203 . 205 6.2. Informative References 207 [GEOHASH] "Geohash", 2020, . 209 [RFC6891] Damas, J., Graff, M., and P. Vixie, "Extension Mechanisms 210 for DNS (EDNS(0))", STD 75, RFC 6891, 211 DOI 10.17487/RFC6891, April 2013, 212 . 214 [RFC7871] Contavalli, C., van der Gaast, W., Lawrence, D., and W. 215 Kumari, "Client Subnet in DNS Queries", RFC 7871, 216 DOI 10.17487/RFC7871, May 2016, 217 . 219 Author's Address 221 Tommy Pauly 222 Apple Inc. 223 One Apple Park Way 224 Cupertino, California 95014, 225 United States of America 227 Email: tpauly@apple.com