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McManus 3 Internet-Draft Mozilla 4 Updates: 6455 (if approved) May 6, 2018 5 Intended status: Standards Track 6 Expires: November 7, 2018 8 Bootstrapping WebSockets with HTTP/2 9 draft-ietf-httpbis-h2-websockets-05 11 Abstract 13 This document defines a mechanism for running the WebSocket Protocol 14 (RFC 6455) over a single stream of an HTTP/2 connection. 16 Status of This Memo 18 This Internet-Draft is submitted in full conformance with the 19 provisions of BCP 78 and BCP 79. 21 Internet-Drafts are working documents of the Internet Engineering 22 Task Force (IETF). Note that other groups may also distribute 23 working documents as Internet-Drafts. The list of current Internet- 24 Drafts is at https://datatracker.ietf.org/drafts/current/. 26 Internet-Drafts are draft documents valid for a maximum of six months 27 and may be updated, replaced, or obsoleted by other documents at any 28 time. It is inappropriate to use Internet-Drafts as reference 29 material or to cite them other than as "work in progress." 31 This Internet-Draft will expire on November 7, 2018. 33 Copyright Notice 35 Copyright (c) 2018 IETF Trust and the persons identified as the 36 document authors. All rights reserved. 38 This document is subject to BCP 78 and the IETF Trust's Legal 39 Provisions Relating to IETF Documents 40 (https://trustee.ietf.org/license-info) in effect on the date of 41 publication of this document. Please review these documents 42 carefully, as they describe your rights and restrictions with respect 43 to this document. Code Components extracted from this document must 44 include Simplified BSD License text as described in Section 4.e of 45 the Trust Legal Provisions and are provided without warranty as 46 described in the Simplified BSD License. 48 Table of Contents 50 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 51 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 52 3. The SETTINGS_ENABLE_CONNECT_PROTOCOL SETTINGS Parameter . . . 3 53 4. The Extended CONNECT Method . . . . . . . . . . . . . . . . . 3 54 5. Using Extended CONNECT To Bootstrap The WebSocket Protocol . 4 55 5.1. Example . . . . . . . . . . . . . . . . . . . . . . . . . 5 56 6. Design Considerations . . . . . . . . . . . . . . . . . . . . 5 57 7. About Intermediaries . . . . . . . . . . . . . . . . . . . . 6 58 8. Security Considerations . . . . . . . . . . . . . . . . . . . 6 59 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 60 10. Normative References . . . . . . . . . . . . . . . . . . . . 6 61 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 7 62 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7 64 1. Introduction 66 The Hypertext Transfer Protocol (HTTP) provides compatible resource- 67 level semantics across different versions but it does not offer 68 compatibility at the connection management level. Other protocols, 69 such as WebSockets, that rely on connection management details of 70 HTTP must be updated for new versions of HTTP. 72 The WebSocket Protocol [RFC6455] uses the HTTP/1.1 [RFC7230] Upgrade 73 mechanism to transition a TCP connection from HTTP into a WebSocket 74 connection. A different approach must be taken with HTTP/2 75 [RFC7540]. HTTP/2 does not allow connection-wide headers and status 76 codes such as the Upgrade and Connection request headers or the 101 77 response code due to its multiplexing nature. These are all required 78 by the [RFC6455] opening handshake. 80 Being able to bootstrap WebSockets from HTTP/2 allows one TCP 81 connection to be shared by both protocols and extends HTTP/2's more 82 efficient use of the network to WebSockets. 84 This document extends the HTTP/2 CONNECT method. The extension 85 allows the substitution of a new protocol name to connect to rather 86 than the external host normally used by CONNECT. The result is a 87 tunnel on a single HTTP/2 stream that can carry data for WebSockets 88 (or any other protocol). The other streams on the connection may 89 carry more extended CONNECT tunnels, traditional HTTP/2 data, or a 90 mixture of both. 92 This tunneled stream will be multiplexed with other regular streams 93 on the connection and enjoys the normal priority, cancellation, and 94 flow control features of HTTP/2. 96 Streams that successfully establish a WebSocket connection using a 97 tunneled stream and the modifications to the opening handshake 98 defined in this document then use the traditional WebSocket Protocol, 99 treating the stream as if were the TCP connection in that 100 specification. 102 2. Terminology 104 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 105 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 106 "OPTIONAL" in this document are to be interpreted as described in BCP 107 14 [RFC2119] [RFC8174] when, and only when, they appear in all 108 capitals, as shown here. 110 3. The SETTINGS_ENABLE_CONNECT_PROTOCOL SETTINGS Parameter 112 This document adds a new SETTINGS Parameter to those defined by 113 [RFC7540], Section 6.5.2. 115 The new parameter name is SETTINGS_ENABLE_CONNECT_PROTOCOL. The 116 value of the parameter MUST be 0 or 1. 118 Upon receipt of SETTINGS_ENABLE_CONNECT_PROTOCOL with a value of 1, a 119 client MAY use the Extended CONNECT definition of this document when 120 creating new streams. Receipt of this parameter by a server does not 121 have any impact. 123 A sender MUST NOT send a SETTINGS_ENABLE_CONNECT_PROTOCOL parameter 124 with the value of 0 after previously sending a value of 1. 126 The use of a SETTINGS Parameter to opt-in to an otherwise 127 incompatible protocol change is a use of "Extending HTTP/2" defined 128 by Section 5.5 of [RFC7540]. If a client were to use the provisions 129 of the extended CONNECT method defined in this document without first 130 receiving a SETTINGS_ENABLE_CONNECT_PROTOCOL parameter, a non- 131 supporting peer would detect a malformed request and generate a 132 stream error (Section 8.1.2.6 of [RFC7540]). 134 4. The Extended CONNECT Method 136 Usage of the CONNECT method in HTTP/2 is defined by Section 8.3 of 137 [RFC7540]. This extension modifies the method in the following ways: 139 o A new pseudo-header :protocol MAY be included on request HEADERS 140 indicating the desired protocol to be spoken on the tunnel created 141 by CONNECT. The pseudo-header is single valued and contains a 142 value from the HTTP Upgrade Token Registry defined by [RFC7230]. 144 o On requests bearing the :protocol pseudo-header, the :scheme and 145 :path pseudo-header fields MUST be included. 147 o On requests bearing the :protocol pseudo-header, the :authority 148 pseudo-header field is interpreted according to Section 8.1.2.3 of 149 [RFC7540] instead of Section 8.3 of [RFC7540]. In particular the 150 server MUST NOT make a new TCP connection to the host and port 151 indicated by the :authority. 153 Upon receiving a CONNECT request bearing the :protocol pseudo-header 154 the server establishes a tunnel to another service of the protocol 155 type indicated by the pseudo-header. This service may or may not be 156 co-located with the server. 158 5. Using Extended CONNECT To Bootstrap The WebSocket Protocol 160 The pseudo-header :protocol MUST be included in the CONNECT request 161 and it MUST have a value of "websocket" to initiate a WebSocket 162 connection on an HTTP/2 stream. Other HTTP request and response 163 headers, such as those for manipulating cookies, may be included in 164 the HEADERS with the CONNECT method as usual. This request replaces 165 the GET-based request in [RFC6455] and is used to process the 166 WebSockets opening handshake. 168 The scheme of the Target URI [RFC7230] MUST be "https" for "wss" 169 schemed WebSockets and "http" for "ws" schemed WebSockets. The 170 websocket URI is still used for proxy autoconfiguration. 172 [RFC6455] requires the use of Connection and Upgrade headers that are 173 not part of HTTP/2. They MUST NOT be included in the CONNECT request 174 defined here. 176 [RFC6455] requires the use of a Host header which is also not part of 177 HTTP/2. The Host information is conveyed as part of the :authority 178 pseudo-header which is required on every HTTP/2 transaction. 180 Implementations using this extended CONNECT to bootstrap WebSockets 181 do not do the processing of the [RFC6455] Sec-WebSocket-Key and Sec- 182 WebSocket-Accept headers as that functionality has been superseded by 183 the :protocol pseudo-header. 185 The Sec-WebSocket-Version, Origin [RFC6454], Sec-WebSocket-Protocol, 186 and Sec-WebSocket-Extensions headers are used on the CONNECT request 187 and response headers in the same way as defined in [RFC6455]. Note 188 that HTTP/1 header names were case-insensitive and HTTP/2 requires 189 they be encoded as lower case. 191 After successfully processing the opening handshake, the peers should 192 proceed with The WebSocket Protocol [RFC6455] using the HTTP/2 stream 193 from the CONNECT transaction as if it were the TCP connection 194 referred to in [RFC6455]. The state of the WebSocket connection at 195 this point is OPEN as defined by [RFC6455], Section 4.1. 197 The HTTP/2 stream closure is also analogous to the TCP connection of 198 [RFC6455]. Orderly TCP level closures are represented as END_STREAM 199 ([RFC7540], Section 6.1) flags and RST exceptions are represented 200 with the RST_STREAM ([RFC7540], Section 6.4) frame with the CANCEL 201 ([RFC7540], Section 7) error code. 203 5.1. Example 205 [[ From Client ]] [[ From Server ]] 207 SETTINGS 208 SETTINGS_ENABLE_CONNECT_[..] = 1 210 HEADERS + END_HEADERS 211 :method = CONNECT 212 :protocol = websocket 213 :scheme = https 214 :path = /chat 215 :authority = server.example.com 216 sec-websocket-protocol = chat, superchat 217 sec-websocket-extensions = permessage-deflate 218 sec-websocket-version = 13 219 origin = http://www.example.com 221 HEADERS + END_HEADERS 222 :status = 200 223 sec-websocket-protocol = chat 225 DATA 226 WebSocket Data 228 DATA + END_STREAM 229 WebSocket Data 231 DATA + END_STREAM 232 WebSocket Data 234 6. Design Considerations 236 A more native integration with HTTP/2 is certainly possible with 237 larger additions to HTTP/2. This design was selected to minimize the 238 solution complexity while still addressing the primary concern of 239 running HTTP/2 and WebSockets concurrently. 241 7. About Intermediaries 243 This document does not change how WebSockets interacts with HTTP 244 forward proxies. If a client wishing to speak WebSockets connects 245 via HTTP/2 to an HTTP proxy it should continue to use a traditional 246 (i.e. not with a :protocol pseudo-header) CONNECT to tunnel through 247 that proxy to the WebSocket server via HTTP. 249 The resulting version of HTTP on that tunnel determines whether 250 WebSockets is initiated directly or via a modified CONNECT request 251 described in this document. 253 8. Security Considerations 255 [RFC6455] ensures that non-WebSockets clients, especially 256 XMLHttpRequest based clients, cannot make a WebSocket connection. 257 Its primary mechanism for doing that is the use of Sec- prefixed 258 request headers that cannot be created by XMLHttpRequest-based 259 clients. This specification addresses that concern in two ways: 261 o The CONNECT method is prohibited from being used by XMLHttpRequest 263 o The use of a pseudo-header is something that is connection 264 specific and HTTP/2 does not ever allow to be created outside of 265 the protocol stack. 267 9. IANA Considerations 269 This document establishes an entry for the HTTP/2 Settings Registry 270 that was established by Section 11.3 of [RFC7540]. 272 Name: SETTINGS_ENABLE_CONNECT_PROTOCOL 274 Code: 0x8 276 Initial Value: 0 278 Specification: This document 280 10. Normative References 282 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 283 Requirement Levels", BCP 14, RFC 2119, 284 DOI 10.17487/RFC2119, March 1997, 285 . 287 [RFC6454] Barth, A., "The Web Origin Concept", RFC 6454, 288 DOI 10.17487/RFC6454, December 2011, 289 . 291 [RFC6455] Fette, I. and A. Melnikov, "The WebSocket Protocol", 292 RFC 6455, DOI 10.17487/RFC6455, December 2011, 293 . 295 [RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer 296 Protocol (HTTP/1.1): Message Syntax and Routing", 297 RFC 7230, DOI 10.17487/RFC7230, June 2014, 298 . 300 [RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext 301 Transfer Protocol Version 2 (HTTP/2)", RFC 7540, 302 DOI 10.17487/RFC7540, May 2015, 303 . 305 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 306 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 307 May 2017, . 309 Acknowledgments 311 The 2017 HTTP Workshop had a very productive discussion that helped 312 determine the key problem and acceptable level of solution 313 complexity. 315 Author's Address 317 Patrick McManus 318 Mozilla 320 Email: mcmanus@ducksong.com