Network Working Group J. R. Combs, Ed. Internet-Draft Plex Updates: 7233 September 21, 2015 (if approved) Intended status: Standards Track Expires: March 24, 2016 HTTP/1.1: Range Responses of Indeterminate Length draft-combs-http-indeterminate-range-02 Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on March 24, 2016. Copyright Notice Copyright (c) 2015 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Combs Expires March 24, 2016 [Page 1] Internet-Draft HTTP/1.1 Extended Range Requests September 2015 Abstract The Hypertext Transfer Protocol (HTTP) is an application-level protocol for distributed, collaborative, hypermedia information systems. HTTP has been in use by the World Wide Web global information initiative since 1990. This document updates RFC 7233, Part 5 of the eight-part specification that defines the protocol referred to as "HTTP/1.1". Part 5 defines range-specific requests and the rules for constructing and combining responses to those requests. This document improves support for responding to range requests for resources of indeterminate size. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Header Field Definitions . . . . . . . . . . . . . . . . . . . 3 2.1. Accept-Indefinite-Ranges . . . . . . . . . . . . . . . . . 3 2.2. Content-Range . . . . . . . . . . . . . . . . . . . . . . 3 3. Security Considerations . . . . . . . . . . . . . . . . . . . 5 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 4.1. Header Field Registration . . . . . . . . . . . . . . . . 5 5. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 5 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 6.1. Normative References . . . . . . . . . . . . . . . . . . . 6 6.2. Informative References . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 Combs Expires March 24, 2016 [Page 2] Internet-Draft HTTP/1.1 Extended Range Requests September 2015 1. Introduction This document will define changes to [RFC7233] HTTP/1.1 designed to allow range requests to be used to retrieve parts of resources whose lengths are unknown at the time of the first request. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. 2. Header Field Definitions This section defines the syntax and semantics of all standard HTTP/1.1 header fields. For entity-header fields, both sender and recipient refer to either the client or the server, depending on who sends and who receives the entity. 2.1. Accept-Indefinite-Ranges The Accept-Indefinite-Ranges request-header field allows the client to indicate its acceptance of indefinite-sized range requests for a resource: Accept-Indefinite-Ranges = "Accept-Indefinite-Ranges" ":" "1" Servers MUST NOT generate indefinite-sized byte-range replies without having received this header, with the value "1", for the resource involved. 2.2. Content-Range The Content-Range entity-header is sent with a partial entity-body to specify where in the full entity-body the partial body should be applied. This section updates Section 4.2 of [RFC7233]. Content-Range = byte-content-range / other-content-range byte-content-range = bytes-unit SP ( byte-range-resp / unsatisfied-range ) byte-range-resp = byte-range "/" ( complete-length / "*" ) byte-range = first-byte-pos "-" (last-byte-pos / "*" ) unsatisfied-range = "*/" ( complete-length / "*" ) complete-length = 1*DIGIT other-content-range = other-range-unit SP other-range-resp other-range-resp = *CHAR Combs Expires March 24, 2016 [Page 3] Internet-Draft HTTP/1.1 Extended Range Requests September 2015 For byte ranges, a sender SHOULD indicate the complete length of the representation from which the range has been extracted, unless the complete length is unknown or difficult to determine. An asterisk character ("*") in place of the complete-length indicates that the representation length was unknown when the header field was generated. An asterisk character in place of the last-byte-pos indicates that the response length was unknown when the header was generated, and that the entire requested range of the resource will be sent. An asterisk character may be used in place of the last-byte-pos ONLY if the Accept-Indefinite-Ranges header was sent, and requires use of the RFC 7230 Chunked Transfer-Encoding The following example illustrates when the complete length of the selected representation is known by the sender to be 1234 bytes: Content-Range: bytes 42-1233/1234 and this second example illustrates when the complete length is unknown: Content-Range: bytes 42-1233/* OR Content-Range: bytes 42-*/* (if the Accept-Indefinite-Ranges request header was sent) Request and response range values for an example use-case, in which a growing media file is streamed to the client: Client requests the whole stream: Range: 0- Server begins a response of unknown size: bytes 0-*/* User seeks in the stream; client closes previous connection and requests the seek offset (possibly repeating multiple times to find the desired offset): Range: 32768- Server begins a response of unknown size, at the requested offset: bytes 32768-*/* Combs Expires March 24, 2016 [Page 4] Internet-Draft HTTP/1.1 Extended Range Requests September 2015 3. Security Considerations No additional security considerations have been identified beyond those applicable to HTTP range requests in general [RFC7233]. 4. IANA Considerations 4.1. Header Field Registration HTTP header fields are registered within the "Message Headers" registry maintained at . This document defines or updates the following HTTP header fields, so their associated registry entries shall be updated according to the permanent registrations below (see [BCP90]): +--------------------------+----------+----------+-------------+ | Header Field Name | Protocol | Status | Reference | +--------------------------+----------+----------+-------------+ | Accept-Indefinite-Ranges | http | standard | Section 2.1 | | Content-Range | http | standard | Section 2.2 | +--------------------------+----------+----------+-------------+ The change controller is: "IETF (iesg@ietf.org) - Internet Engineering Task Force". 5. Acknowledgments Parts of this document are based on [RFC7233] and its drafts. Combs Expires March 24, 2016 [Page 5] Internet-Draft HTTP/1.1 Extended Range Requests September 2015 6. References 6.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC7233] Fielding, R., Ed., Lafon, Y., Ed., and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Range Requests", RFC 7233, June 2014. 6.2. Informative References [BCP90] Klyne, G., Nottingham, M., and J. Mogul, "Registration Procedures for Message Header Fields", BCP 90, RFC 3864, September 2004. Authors' Addresses J. Rodger Combs (editor) Plex, Inc. Email: rodger@plex.tv Combs Expires March 24, 2016 [Page 6]