draft-ietf-httpbis-p5-range-26.txt   draft-ietf-httpbis-p5-range-latest.txt 
HTTPbis Working Group R. Fielding, Ed. HTTPbis Working Group R. Fielding, Ed.
Internet-Draft Adobe Internet-Draft Adobe
Obsoletes: 2616 (if approved) Y. Lafon, Ed. Obsoletes: 2616 (if approved) Y. Lafon, Ed.
Intended status: Standards Track W3C Intended status: Standards Track W3C
Expires: August 10, 2014 J. Reschke, Ed. Expires: December 3, 2014 J. Reschke, Ed.
greenbytes greenbytes
February 6, 2014 June 2014
Hypertext Transfer Protocol (HTTP/1.1): Range Requests Hypertext Transfer Protocol (HTTP/1.1): Range Requests
draft-ietf-httpbis-p5-range-26 draft-ietf-httpbis-p5-range-latest
Abstract Abstract
The Hypertext Transfer Protocol (HTTP) is a stateless application- The Hypertext Transfer Protocol (HTTP) is a stateless application-
level protocol for distributed, collaborative, hypertext information level protocol for distributed, collaborative, hypertext information
systems. This document defines range requests and the rules for systems. This document defines range requests and the rules for
constructing and combining responses to those requests. constructing and combining responses to those requests.
Editorial Note (To be removed by RFC Editor) Editorial Note (To be removed by RFC Editor)
Discussion of this draft takes place on the HTTPBIS working group Discussion of this draft takes place on the HTTPBIS working group
mailing list (ietf-http-wg@w3.org), which is archived at mailing list (ietf-http-wg@w3.org), which is archived at
<http://lists.w3.org/Archives/Public/ietf-http-wg/>. <http://lists.w3.org/Archives/Public/ietf-http-wg/>.
The current issues list is at The current issues list is at
<http://tools.ietf.org/wg/httpbis/trac/report/3> and related <http://tools.ietf.org/wg/httpbis/trac/report/3> and related
documents (including fancy diffs) can be found at documents (including fancy diffs) can be found at
<http://tools.ietf.org/wg/httpbis/>. <http://tools.ietf.org/wg/httpbis/>.
The changes in this draft are summarized in Appendix E.2. _This is a temporary document for the purpose of tracking the
editorial changes made during the AUTH48 (RFC publication) phase._
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 3, 2014.
This Internet-Draft will expire on August 10, 2014.
Copyright Notice Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 3, line 31 skipping to change at page 3, line 31
4.4. 416 Range Not Satisfiable . . . . . . . . . . . . . . . . 15 4.4. 416 Range Not Satisfiable . . . . . . . . . . . . . . . . 15
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
5.1. Range Unit Registry . . . . . . . . . . . . . . . . . . . 15 5.1. Range Unit Registry . . . . . . . . . . . . . . . . . . . 15
5.1.1. Procedure . . . . . . . . . . . . . . . . . . . . . . 15 5.1.1. Procedure . . . . . . . . . . . . . . . . . . . . . . 15
5.1.2. Registrations . . . . . . . . . . . . . . . . . . . . 16 5.1.2. Registrations . . . . . . . . . . . . . . . . . . . . 16
5.2. Status Code Registration . . . . . . . . . . . . . . . . . 16 5.2. Status Code Registration . . . . . . . . . . . . . . . . . 16
5.3. Header Field Registration . . . . . . . . . . . . . . . . 16 5.3. Header Field Registration . . . . . . . . . . . . . . . . 16
5.4. Internet Media Type Registration . . . . . . . . . . . . . 17 5.4. Internet Media Type Registration . . . . . . . . . . . . . 17
5.4.1. Internet Media Type multipart/byteranges . . . . . . . 17 5.4.1. Internet Media Type multipart/byteranges . . . . . . . 17
6. Security Considerations . . . . . . . . . . . . . . . . . . . 18 6. Security Considerations . . . . . . . . . . . . . . . . . . . 18
6.1. Denial of Service Attacks using Range . . . . . . . . . . 18 6.1. Denial-of-Service Attacks Using Range . . . . . . . . . . 18
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 18 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 18
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 19 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 19
8.1. Normative References . . . . . . . . . . . . . . . . . . . 19 8.1. Normative References . . . . . . . . . . . . . . . . . . . 19
8.2. Informative References . . . . . . . . . . . . . . . . . . 19 8.2. Informative References . . . . . . . . . . . . . . . . . . 19
Appendix A. Internet Media Type multipart/byteranges . . . . . . 20 Appendix A. Internet Media Type multipart/byteranges . . . . . . 20
Appendix B. Changes from RFC 2616 . . . . . . . . . . . . . . . . 21 Appendix B. Changes from RFC 2616 . . . . . . . . . . . . . . . . 21
Appendix C. Imported ABNF . . . . . . . . . . . . . . . . . . . . 21 Appendix C. Imported ABNF . . . . . . . . . . . . . . . . . . . . 21
Appendix D. Collected ABNF . . . . . . . . . . . . . . . . . . . 21 Appendix D. Collected ABNF . . . . . . . . . . . . . . . . . . . 21
Appendix E. Change Log (to be removed by RFC Editor before
publication) . . . . . . . . . . . . . . . . . . . . 23
E.1. Since draft-ietf-httpbis-p5-range-24 . . . . . . . . . . . 23
E.2. Since draft-ietf-httpbis-p5-range-25 . . . . . . . . . . . 23
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
1. Introduction 1. Introduction
Hypertext Transfer Protocol (HTTP) clients often encounter Hypertext Transfer Protocol (HTTP) clients often encounter
interrupted data transfers as a result of canceled requests or interrupted data transfers as a result of canceled requests or
dropped connections. When a client has stored a partial dropped connections. When a client has stored a partial
representation, it is desirable to request the remainder of that representation, it is desirable to request the remainder of that
representation in a subsequent request rather than transfer the representation in a subsequent request rather than transfer the
entire representation. Likewise, devices with limited local storage entire representation. Likewise, devices with limited local storage
skipping to change at page 4, line 37 skipping to change at page 4, line 37
extensible range types, this specification only defines requests for extensible range types, this specification only defines requests for
byte ranges. byte ranges.
1.1. Conformance and Error Handling 1.1. Conformance and Error Handling
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
Conformance criteria and considerations regarding error handling are Conformance criteria and considerations regarding error handling are
defined in Section 2.5 of [Part1]. defined in Section 2.5 of [RFC7230].
1.2. Syntax Notation 1.2. Syntax Notation
This specification uses the Augmented Backus-Naur Form (ABNF) This specification uses the Augmented Backus-Naur Form (ABNF)
notation of [RFC5234] with a list extension, defined in Section 7 of notation of [RFC5234] with a list extension, defined in Section 7 of
[Part1], that allows for compact definition of comma-separated lists [RFC7230], that allows for compact definition of comma-separated
using a '#' operator (similar to how the '*' operator indicates lists using a '#' operator (similar to how the '*' operator indicates
repetition). Appendix C describes rules imported from other repetition). Appendix C describes rules imported from other
documents. Appendix D shows the collected grammar with all list documents. Appendix D shows the collected grammar with all list
operators expanded to standard ABNF notation. operators expanded to standard ABNF notation.
2. Range Units 2. Range Units
A representation can be partitioned into subranges according to A representation can be partitioned into subranges according to
various structural units, depending on the structure inherent in the various structural units, depending on the structure inherent in the
representation's media type. This "range unit" is used in the representation's media type. This "range unit" is used in the
Accept-Ranges (Section 2.3) response header field to advertise Accept-Ranges (Section 2.3) response header field to advertise
skipping to change at page 5, line 17 skipping to change at page 5, line 17
field to delineate the parts of a representation that are requested, field to delineate the parts of a representation that are requested,
and the Content-Range (Section 4.2) payload header field to describe and the Content-Range (Section 4.2) payload header field to describe
which part of a representation is being transferred. which part of a representation is being transferred.
range-unit = bytes-unit / other-range-unit range-unit = bytes-unit / other-range-unit
2.1. Byte Ranges 2.1. Byte Ranges
Since representation data is transferred in payloads as a sequence of Since representation data is transferred in payloads as a sequence of
octets, a byte range is a meaningful substructure for any octets, a byte range is a meaningful substructure for any
representation transferable over HTTP (Section 3 of [Part2]). The representation transferable over HTTP (Section 3 of [RFC7231]). The
"bytes" range unit is defined for expressing subranges of the data's "bytes" range unit is defined for expressing subranges of the data's
octet sequence. octet sequence.
bytes-unit = "bytes" bytes-unit = "bytes"
A byte range request can specify a single range of bytes, or a set of A byte-range request can specify a single range of bytes or a set of
ranges within a single representation. ranges within a single representation.
byte-ranges-specifier = bytes-unit "=" byte-range-set byte-ranges-specifier = bytes-unit "=" byte-range-set
byte-range-set = 1#( byte-range-spec / suffix-byte-range-spec ) byte-range-set = 1#( byte-range-spec / suffix-byte-range-spec )
byte-range-spec = first-byte-pos "-" [ last-byte-pos ] byte-range-spec = first-byte-pos "-" [ last-byte-pos ]
first-byte-pos = 1*DIGIT first-byte-pos = 1*DIGIT
last-byte-pos = 1*DIGIT last-byte-pos = 1*DIGIT
The first-byte-pos value in a byte-range-spec gives the byte-offset The first-byte-pos value in a byte-range-spec gives the byte-offset
of the first byte in a range. The last-byte-pos value gives the of the first byte in a range. The last-byte-pos value gives the
skipping to change at page 6, line 45 skipping to change at page 6, line 45
bytes=500-600,601-999 bytes=500-600,601-999
bytes=500-700,601-999 bytes=500-700,601-999
If a valid byte-range-set includes at least one byte-range-spec with If a valid byte-range-set includes at least one byte-range-spec with
a first-byte-pos that is less than the current length of the a first-byte-pos that is less than the current length of the
representation, or at least one suffix-byte-range-spec with a non- representation, or at least one suffix-byte-range-spec with a non-
zero suffix-length, then the byte-range-set is satisfiable. zero suffix-length, then the byte-range-set is satisfiable.
Otherwise, the byte-range-set is unsatisfiable. Otherwise, the byte-range-set is unsatisfiable.
In the byte range syntax, first-byte-pos, last-byte-pos, and suffix- In the byte-range syntax, first-byte-pos, last-byte-pos, and suffix-
length are expressed as decimal number of octets. Since there is no length are expressed as decimal number of octets. Since there is no
predefined limit to the length of a payload, recipients MUST predefined limit to the length of a payload, recipients MUST
anticipate potentially large decimal numerals and prevent parsing anticipate potentially large decimal numerals and prevent parsing
errors due to integer conversion overflows. errors due to integer conversion overflows.
2.2. Other Range Units 2.2. Other Range Units
Range units are intended to be extensible. New range units ought to Range units are intended to be extensible. New range units ought to
be registered with IANA, as defined in Section 5.1. be registered with IANA, as defined in Section 5.1.
skipping to change at page 8, line 15 skipping to change at page 8, line 15
than GET. than GET.
An origin server MUST ignore a Range header field that contains a An origin server MUST ignore a Range header field that contains a
range unit it does not understand. A proxy MAY discard a Range range unit it does not understand. A proxy MAY discard a Range
header field that contains a range unit it does not understand. header field that contains a range unit it does not understand.
A server that supports range requests MAY ignore or reject a Range A server that supports range requests MAY ignore or reject a Range
header field that consists of more than two overlapping ranges, or a header field that consists of more than two overlapping ranges, or a
set of many small ranges that are not listed in ascending order, set of many small ranges that are not listed in ascending order,
since both are indications of either a broken client or a deliberate since both are indications of either a broken client or a deliberate
denial of service attack (Section 6.1). A client SHOULD NOT request denial-of-service attack (Section 6.1). A client SHOULD NOT request
multiple ranges that are inherently less efficient to process and multiple ranges that are inherently less efficient to process and
transfer than a single range that encompasses the same data. transfer than a single range that encompasses the same data.
A client that is requesting multiple ranges SHOULD list those ranges A client that is requesting multiple ranges SHOULD list those ranges
in ascending order (the order in which they would typically be in ascending order (the order in which they would typically be
received in a complete representation) unless there is a specific received in a complete representation) unless there is a specific
need to request a later part earlier. For example, a user agent need to request a later part earlier. For example, a user agent
processing a large representation with an internal catalog of parts processing a large representation with an internal catalog of parts
might need to request later parts first, particularly if the might need to request later parts first, particularly if the
representation consists of pages stored in reverse order and the user representation consists of pages stored in reverse order and the user
agent wishes to transfer one page at a time. agent wishes to transfer one page at a time.
The Range header field is evaluated after evaluating the precondition The Range header field is evaluated after evaluating the precondition
header fields defined in [Part4], and only if the result in absence header fields defined in [RFC7232], and only if the result in absence
of the Range header field would be a 200 (OK) response. In other of the Range header field would be a 200 (OK) response. In other
words, Range is ignored when a conditional GET would result in a 304 words, Range is ignored when a conditional GET would result in a 304
(Not Modified) response. (Not Modified) response.
The If-Range header field (Section 3.2) can be used as a precondition The If-Range header field (Section 3.2) can be used as a precondition
to applying the Range header field. to applying the Range header field.
If all of the preconditions are true, the server supports the Range If all of the preconditions are true, the server supports the Range
header field for the target resource, and the specified range(s) are header field for the target resource, and the specified range(s) are
valid and satisfiable (as defined in Section 2.1), the server SHOULD valid and satisfiable (as defined in Section 2.1), the server SHOULD
skipping to change at page 9, line 16 skipping to change at page 9, line 16
If a client has a partial copy of a representation and wishes to have If a client has a partial copy of a representation and wishes to have
an up-to-date copy of the entire representation, it could use the an up-to-date copy of the entire representation, it could use the
Range header field with a conditional GET (using either or both of Range header field with a conditional GET (using either or both of
If-Unmodified-Since and If-Match.) However, if the precondition If-Unmodified-Since and If-Match.) However, if the precondition
fails because the representation has been modified, the client would fails because the representation has been modified, the client would
then have to make a second request to obtain the entire current then have to make a second request to obtain the entire current
representation. representation.
The "If-Range" header field allows a client to "short-circuit" the The "If-Range" header field allows a client to "short-circuit" the
second request. Informally, its meaning is: if the representation is second request. Informally, its meaning is as follows: if the
unchanged, send me the part(s) that I am requesting in Range; representation is unchanged, send me the part(s) that I am requesting
otherwise, send me the entire representation. in Range; otherwise, send me the entire representation.
If-Range = entity-tag / HTTP-date If-Range = entity-tag / HTTP-date
A client MUST NOT generate an If-Range header field in a request that A client MUST NOT generate an If-Range header field in a request that
does not contain a Range header field. A server MUST ignore an If- does not contain a Range header field. A server MUST ignore an If-
Range header field received in a request that does not contain a Range header field received in a request that does not contain a
Range header field. An origin server MUST ignore an If-Range header Range header field. An origin server MUST ignore an If-Range header
field received in a request for a target resource that does not field received in a request for a target resource that does not
support Range requests. support Range requests.
A client MUST NOT generate an If-Range header field containing an A client MUST NOT generate an If-Range header field containing an
entity-tag that is marked as weak. A client MUST NOT generate an If- entity-tag that is marked as weak. A client MUST NOT generate an If-
Range header field containing an HTTP-date unless the client has no Range header field containing an HTTP-date unless the client has no
entity-tag for the corresponding representation and the date is a entity-tag for the corresponding representation and the date is a
strong validator in the sense defined by Section 2.2.2 of [Part4]. strong validator in the sense defined by Section 2.2.2 of [RFC7232].
A server that evaluates an If-Range precondition MUST use the strong A server that evaluates an If-Range precondition MUST use the strong
comparison function when comparing entity-tags (Section 2.3.2 of comparison function when comparing entity-tags (Section 2.3.2 of
[Part4]) and MUST evaluate the condition as false if an HTTP-date [RFC7232]) and MUST evaluate the condition as false if an HTTP-date
validator is provided that is not a strong validator in the sense validator is provided that is not a strong validator in the sense
defined by Section 2.2.2 of [Part4]. A valid entity-tag can be defined by Section 2.2.2 of [RFC7232]. A valid entity-tag can be
distinguished from a valid HTTP-date by examining the first two distinguished from a valid HTTP-date by examining the first two
characters for a DQUOTE. characters for a DQUOTE.
If the validator given in the If-Range header field matches the If the validator given in the If-Range header field matches the
current validator for the selected representation of the target current validator for the selected representation of the target
resource, then the server SHOULD process the Range header field as resource, then the server SHOULD process the Range header field as
requested. If the validator does not match, the server MUST ignore requested. If the validator does not match, the server MUST ignore
the Range header field. Note that this comparison by exact match, the Range header field. Note that this comparison by exact match,
including when the validator is an HTTP-date, differs from the including when the validator is an HTTP-date, differs from the
"earlier than or equal to" comparison used when evaluating an If- "earlier than or equal to" comparison used when evaluating an If-
skipping to change at page 10, line 33 skipping to change at page 10, line 33
Content-Range: bytes 21010-47021/47022 Content-Range: bytes 21010-47021/47022
Content-Length: 26012 Content-Length: 26012
Content-Type: image/gif Content-Type: image/gif
... 26012 bytes of partial image data ... ... 26012 bytes of partial image data ...
If multiple parts are being transferred, the server generating the If multiple parts are being transferred, the server generating the
206 response MUST generate a "multipart/byteranges" payload, as 206 response MUST generate a "multipart/byteranges" payload, as
defined in Appendix A, and a Content-Type header field containing the defined in Appendix A, and a Content-Type header field containing the
multipart/byteranges media type and its required boundary parameter. multipart/byteranges media type and its required boundary parameter.
To avoid confusion with single part responses, a server MUST NOT To avoid confusion with single-part responses, a server MUST NOT
generate a Content-Range header field in the HTTP header section of a generate a Content-Range header field in the HTTP header section of a
multiple part response (this field will be sent in each part multiple part response (this field will be sent in each part
instead). instead).
Within the header area of each body part in the multipart payload, Within the header area of each body part in the multipart payload,
the server MUST generate a Content-Range header field corresponding the server MUST generate a Content-Range header field corresponding
to the range being enclosed in that body part. If the selected to the range being enclosed in that body part. If the selected
representation would have had a Content-Type header field in a 200 representation would have had a Content-Type header field in a 200
(OK) response, the server SHOULD generate that same Content-Type (OK) response, the server SHOULD generate that same Content-Type
field in the header area of each body part. For example: field in the header area of each body part. For example:
skipping to change at page 12, line 20 skipping to change at page 12, line 20
If a 206 is generated in response to a request with an If-Range If a 206 is generated in response to a request with an If-Range
header field, the sender SHOULD NOT generate other representation header field, the sender SHOULD NOT generate other representation
header fields beyond those required above, because the client is header fields beyond those required above, because the client is
understood to already have a prior response containing those header understood to already have a prior response containing those header
fields. Otherwise, the sender MUST generate all of the fields. Otherwise, the sender MUST generate all of the
representation header fields that would have been sent in a 200 (OK) representation header fields that would have been sent in a 200 (OK)
response to the same request. response to the same request.
A 206 response is cacheable by default; i.e., unless otherwise A 206 response is cacheable by default; i.e., unless otherwise
indicated by explicit cache controls (see Section 4.2.2 of [Part6]). indicated by explicit cache controls (see Section 4.2.2 of
[RFC7234]).
4.2. Content-Range 4.2. Content-Range
The "Content-Range" header field is sent in a single part 206 The "Content-Range" header field is sent in a single part 206
(Partial Content) response to indicate the partial range of the (Partial Content) response to indicate the partial range of the
selected representation enclosed as the message payload, sent in each selected representation enclosed as the message payload, sent in each
part of a multipart 206 response to indicate the range enclosed part of a multipart 206 response to indicate the range enclosed
within each body part, and sent in 416 (Range Not Satisfiable) within each body part, and sent in 416 (Range Not Satisfiable)
responses to provide information about the selected representation. responses to provide information about the selected representation.
skipping to change at page 13, line 27 skipping to change at page 13, line 29
Content-Range: bytes 42-1233/* Content-Range: bytes 42-1233/*
A Content-Range field value is invalid if it contains a byte-range- A Content-Range field value is invalid if it contains a byte-range-
resp that has a last-byte-pos value less than its first-byte-pos resp that has a last-byte-pos value less than its first-byte-pos
value, or a complete-length value less than or equal to its last- value, or a complete-length value less than or equal to its last-
byte-pos value. The recipient of an invalid Content-Range MUST NOT byte-pos value. The recipient of an invalid Content-Range MUST NOT
attempt to recombine the received content with a stored attempt to recombine the received content with a stored
representation. representation.
A server generating a 416 (Range Not Satisfiable) response to a byte A server generating a 416 (Range Not Satisfiable) response to a byte-
range request SHOULD send a Content-Range header field with an range request SHOULD send a Content-Range header field with an
unsatisfied-range value, as in the following example: unsatisfied-range value, as in the following example:
Content-Range: bytes */1234 Content-Range: bytes */1234
The complete-length in a 416 response indicates the current length of The complete-length in a 416 response indicates the current length of
the selected representation. the selected representation.
The "Content-Range" header field has no meaning for status codes that The Content-Range header field has no meaning for status codes that
do not explicitly describe its semantic. For this specification, do not explicitly describe its semantic. For this specification,
only the 206 (Partial Content) and 416 (Range Not Satisfiable) status only the 206 (Partial Content) and 416 (Range Not Satisfiable) status
codes describe a meaning for Content-Range. codes describe a meaning for Content-Range.
The following are examples of Content-Range values in which the The following are examples of Content-Range values in which the
selected representation contains a total of 1234 bytes: selected representation contains a total of 1234 bytes:
o The first 500 bytes: o The first 500 bytes:
Content-Range: bytes 0-499/1234 Content-Range: bytes 0-499/1234
skipping to change at page 14, line 20 skipping to change at page 14, line 20
Content-Range: bytes 734-1233/1234 Content-Range: bytes 734-1233/1234
4.3. Combining Ranges 4.3. Combining Ranges
A response might transfer only a subrange of a representation if the A response might transfer only a subrange of a representation if the
connection closed prematurely or if the request used one or more connection closed prematurely or if the request used one or more
Range specifications. After several such transfers, a client might Range specifications. After several such transfers, a client might
have received several ranges of the same representation. These have received several ranges of the same representation. These
ranges can only be safely combined if they all have in common the ranges can only be safely combined if they all have in common the
same strong validator (Section 2.1 of [Part4]). same strong validator (Section 2.1 of [RFC7232]).
A client that has received multiple partial responses to GET requests A client that has received multiple partial responses to GET requests
on a target resource MAY combine those responses into a larger on a target resource MAY combine those responses into a larger
continuous range if they share the same strong validator. continuous range if they share the same strong validator.
If the most recent response is an incomplete 200 (OK) response, then If the most recent response is an incomplete 200 (OK) response, then
the header fields of that response are used for any combined response the header fields of that response are used for any combined response
and replace those of the matching stored responses. and replace those of the matching stored responses.
If the most recent response is a 206 (Partial Content) response and If the most recent response is a 206 (Partial Content) response and
skipping to change at page 15, line 16 skipping to change at page 15, line 16
The 416 (Range Not Satisfiable) status code indicates that none of The 416 (Range Not Satisfiable) status code indicates that none of
the ranges in the request's Range header field (Section 3.1) overlap the ranges in the request's Range header field (Section 3.1) overlap
the current extent of the selected resource or that the set of ranges the current extent of the selected resource or that the set of ranges
requested has been rejected due to invalid ranges or an excessive requested has been rejected due to invalid ranges or an excessive
request of small or overlapping ranges. request of small or overlapping ranges.
For byte ranges, failing to overlap the current extent means that the For byte ranges, failing to overlap the current extent means that the
first-byte-pos of all of the byte-range-spec values were greater than first-byte-pos of all of the byte-range-spec values were greater than
the current length of the selected representation. When this status the current length of the selected representation. When this status
code is generated in response to a byte range request, the sender code is generated in response to a byte-range request, the sender
SHOULD generate a Content-Range header field specifying the current SHOULD generate a Content-Range header field specifying the current
length of the selected representation (Section 4.2). length of the selected representation (Section 4.2).
For example: For example:
HTTP/1.1 416 Range Not Satisfiable HTTP/1.1 416 Range Not Satisfiable
Date: Fri, 20 Jan 2012 15:41:54 GMT Date: Fri, 20 Jan 2012 15:41:54 GMT
Content-Range: bytes */47022 Content-Range: bytes */47022
Note: Because servers are free to ignore Range, many Note: Because servers are free to ignore Range, many
skipping to change at page 15, line 40 skipping to change at page 15, line 40
task (albeit less efficiently) and partly because clients might task (albeit less efficiently) and partly because clients might
not stop making an invalid partial request until they have not stop making an invalid partial request until they have
received a complete representation. Thus, clients cannot depend received a complete representation. Thus, clients cannot depend
on receiving a 416 (Range Not Satisfiable) response even when it on receiving a 416 (Range Not Satisfiable) response even when it
is most appropriate. is most appropriate.
5. IANA Considerations 5. IANA Considerations
5.1. Range Unit Registry 5.1. Range Unit Registry
The HTTP Range Unit Registry defines the name space for the range The "HTTP Range Unit Registry" defines the namespace for the range
unit names and refers to their corresponding specifications. The unit names and refers to their corresponding specifications. The
registry will be created and maintained at (the suggested URI) registry has been created and is now maintained at
<http://www.iana.org/assignments/http-parameters>. <http://www.iana.org/assignments/http-parameters>.
5.1.1. Procedure 5.1.1. Procedure
Registration of an HTTP Range Unit MUST include the following fields: Registration of an HTTP Range Unit MUST include the following fields:
o Name o Name
o Description o Description
o Pointer to specification text o Pointer to specification text
Values to be added to this name space require IETF Review (see Values to be added to this namespace require IETF Review (see
[RFC5226], Section 4.1). [RFC5226], Section 4.1).
5.1.2. Registrations 5.1.2. Registrations
The initial HTTP Range Unit Registry shall contain the registrations The initial range unit registry contains the registrations below:
below:
+-------------+---------------------------------------+-------------+ +-------------+---------------------------------------+-------------+
| Range Unit | Description | Reference | | Range Unit | Description | Reference |
| Name | | | | Name | | |
+-------------+---------------------------------------+-------------+ +-------------+---------------------------------------+-------------+
| bytes | a range of octets | Section 2.1 | | bytes | a range of octets | Section 2.1 |
| none | reserved as keyword, indicating no | Section 2.3 | | none | reserved as keyword, indicating no | Section 2.3 |
| | ranges are supported | | | | ranges are supported | |
+-------------+---------------------------------------+-------------+ +-------------+---------------------------------------+-------------+
The change controller is: "IETF (iesg@ietf.org) - Internet The change controller is: "IETF (iesg@ietf.org) - Internet
Engineering Task Force". Engineering Task Force".
5.2. Status Code Registration 5.2. Status Code Registration
The HTTP Status Code Registry located at The "Hypertext Transfer Protocol (HTTP) Status Code Registry" located
<http://www.iana.org/assignments/http-status-codes> shall be updated at <http://www.iana.org/assignments/http-status-codes> has been
with the registrations below: updated to include the registrations below:
+-------+-----------------------+-------------+ +-------+-----------------------+-------------+
| Value | Description | Reference | | Value | Description | Reference |
+-------+-----------------------+-------------+ +-------+-----------------------+-------------+
| 206 | Partial Content | Section 4.1 | | 206 | Partial Content | Section 4.1 |
| 416 | Range Not Satisfiable | Section 4.4 | | 416 | Range Not Satisfiable | Section 4.4 |
+-------+-----------------------+-------------+ +-------+-----------------------+-------------+
5.3. Header Field Registration 5.3. Header Field Registration
HTTP header fields are registered within the Message Header Field HTTP header fields are registered within the "Message Headers"
Registry maintained at <http://www.iana.org/assignments/ registry maintained at
message-headers/message-header-index.html>. <http://www.iana.org/assignments/message-headers/>.
This document defines the following HTTP header fields, so their This document defines the following HTTP header fields, so their
associated registry entries shall be updated according to the associated registry entries have been updated according to the
permanent registrations below (see [BCP90]): permanent registrations below (see [BCP90]):
+-------------------+----------+----------+-------------+ +-------------------+----------+----------+-------------+
| Header Field Name | Protocol | Status | Reference | | Header Field Name | Protocol | Status | Reference |
+-------------------+----------+----------+-------------+ +-------------------+----------+----------+-------------+
| Accept-Ranges | http | standard | Section 2.3 | | Accept-Ranges | http | standard | Section 2.3 |
| Content-Range | http | standard | Section 4.2 | | Content-Range | http | standard | Section 4.2 |
| If-Range | http | standard | Section 3.2 | | If-Range | http | standard | Section 3.2 |
| Range | http | standard | Section 3.1 | | Range | http | standard | Section 3.1 |
+-------------------+----------+----------+-------------+ +-------------------+----------+----------+-------------+
The change controller is: "IETF (iesg@ietf.org) - Internet The change controller is: "IETF (iesg@ietf.org) - Internet
Engineering Task Force". Engineering Task Force".
5.4. Internet Media Type Registration 5.4. Internet Media Type Registration
IANA maintains the registry of Internet media types [BCP13] at IANA maintains the registry of Internet media types [BCP13] at
<http://www.iana.org/assignments/media-types>. <http://www.iana.org/assignments/media-types>.
This document serves as the specification for the Internet media type This document serves as the specification for the Internet media type
"multipart/byteranges". The following is to be registered with IANA. "multipart/byteranges". The following has been registered with IANA.
5.4.1. Internet Media Type multipart/byteranges 5.4.1. Internet Media Type multipart/byteranges
Type name: multipart Type name: multipart
Subtype name: byteranges Subtype name: byteranges
Required parameters: boundary Required parameters: boundary
Optional parameters: N/A Optional parameters: N/A
skipping to change at page 18, line 14 skipping to change at page 18, line 14
Deprecated alias names for this type: N/A Deprecated alias names for this type: N/A
Magic number(s): N/A Magic number(s): N/A
File extension(s): N/A File extension(s): N/A
Macintosh file type code(s): N/A Macintosh file type code(s): N/A
Person and email address to contact for further information: See Person and email address to contact for further information: See
Authors Section. Authors' Addresses section.
Intended usage: COMMON Intended usage: COMMON
Restrictions on usage: N/A Restrictions on usage: N/A
Author: See Authors Section. Author: See Authors' Addresses section.
Change controller: IESG Change controller: IESG
6. Security Considerations 6. Security Considerations
This section is meant to inform developers, information providers, This section is meant to inform developers, information providers,
and users of known security concerns specific to the HTTP range and users of known security concerns specific to the HTTP range
request mechanisms. More general security considerations are request mechanisms. More general security considerations are
addressed in HTTP messaging [Part1] and semantics [Part2]. addressed in HTTP messaging [RFC7230] and semantics [RFC7231].
6.1. Denial of Service Attacks using Range 6.1. Denial-of-Service Attacks Using Range
Unconstrained multiple range requests are susceptible to denial of Unconstrained multiple range requests are susceptible to denial-of-
service attacks because the effort required to request many service attacks because the effort required to request many
overlapping ranges of the same data is tiny compared to the time, overlapping ranges of the same data is tiny compared to the time,
memory, and bandwidth consumed by attempting to serve the requested memory, and bandwidth consumed by attempting to serve the requested
data in many parts. Servers ought to ignore, coalesce, or reject data in many parts. Servers ought to ignore, coalesce, or reject
egregious range requests, such as requests for more than two egregious range requests, such as requests for more than two
overlapping ranges or for many small ranges in a single set, overlapping ranges or for many small ranges in a single set,
particularly when the ranges are requested out of order for no particularly when the ranges are requested out of order for no
apparent reason. Multipart range requests are not designed to apparent reason. Multipart range requests are not designed to
support random access. support random access.
7. Acknowledgments 7. Acknowledgments
See Section 10 of [Part1]. See Section 10 of [RFC7230].
8. References 8. References
8.1. Normative References 8.1. Normative References
[Part1] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing",
draft-ietf-httpbis-p1-messaging-26 (work in progress),
February 2014.
[Part2] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Semantics and Content",
draft-ietf-httpbis-p2-semantics-26 (work in progress),
February 2014.
[Part4] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Conditional Requests",
draft-ietf-httpbis-p4-conditional-26 (work in progress),
February 2014.
[Part6] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "Hypertext Transfer Protocol (HTTP/1.1): Caching",
draft-ietf-httpbis-p6-cache-26 (work in progress),
February 2014.
[RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail [RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part Two: Media Types", RFC 2046, Extensions (MIME) Part Two: Media Types", RFC 2046,
November 1996. November 1996.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax [RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008. Specifications: ABNF", STD 68, RFC 5234, January 2008.
[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing",
draft-ietf-httpbis-p1-messaging-latest (work in progress),
June 2014.
[RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Semantics and Content",
draft-ietf-httpbis-p2-semantics-latest (work in progress),
June 2014.
[RFC7232] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Conditional Requests",
draft-ietf-httpbis-p4-conditional-latest (work in
progress), June 2014.
[RFC7234] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "Hypertext Transfer Protocol (HTTP/1.1): Caching",
draft-ietf-httpbis-p6-cache-latest (work in progress),
June 2014.
8.2. Informative References 8.2. Informative References
[BCP13] Freed, N., Klensin, J., and T. Hansen, "Media Type [BCP13] Freed, N., Klensin, J., and T. Hansen, "Media Type
Specifications and Registration Procedures", BCP 13, Specifications and Registration Procedures", BCP 13,
RFC 6838, January 2013. RFC 6838, January 2013.
[BCP90] Klyne, G., Nottingham, M., and J. Mogul, "Registration [BCP90] Klyne, G., Nottingham, M., and J. Mogul, "Registration
Procedures for Message Header Fields", BCP 90, RFC 3864, Procedures for Message Header Fields", BCP 90, RFC 3864,
September 2004. September 2004.
skipping to change at page 21, line 33 skipping to change at page 21, line 33
The following core rules are included by reference, as defined in The following core rules are included by reference, as defined in
Appendix B.1 of [RFC5234]: ALPHA (letters), CR (carriage return), Appendix B.1 of [RFC5234]: ALPHA (letters), CR (carriage return),
CRLF (CR LF), CTL (controls), DIGIT (decimal 0-9), DQUOTE (double CRLF (CR LF), CTL (controls), DIGIT (decimal 0-9), DQUOTE (double
quote), HEXDIG (hexadecimal 0-9/A-F/a-f), LF (line feed), OCTET (any quote), HEXDIG (hexadecimal 0-9/A-F/a-f), LF (line feed), OCTET (any
8-bit sequence of data), SP (space), and VCHAR (any visible US-ASCII 8-bit sequence of data), SP (space), and VCHAR (any visible US-ASCII
character). character).
Note that all rules derived from token are to be compared case- Note that all rules derived from token are to be compared case-
insensitively, like range-unit and acceptable-ranges. insensitively, like range-unit and acceptable-ranges.
The rules below are defined in [Part1]: The rules below are defined in [RFC7230]:
OWS = <OWS, defined in [Part1], Section 3.2.3> OWS = <OWS, see [RFC7230], Section 3.2.3>
token = <token, defined in [Part1], Section 3.2.6> token = <token, see [RFC7230], Section 3.2.6>
The rules below are defined in other parts: The rules below are defined in other parts:
HTTP-date = <HTTP-date, defined in [Part2], Section 7.1.1.1> HTTP-date = <HTTP-date, see [RFC7231], Section 7.1.1.1>
entity-tag = <entity-tag, defined in [Part4], Section 2.3> entity-tag = <entity-tag, see [RFC7232], Section 2.3>
Appendix D. Collected ABNF Appendix D. Collected ABNF
In the collected ABNF below, list rules are expanded as per Section In the collected ABNF below, list rules are expanded as per Section
1.2 of [Part1]. 1.2 of [RFC7230].
Accept-Ranges = acceptable-ranges Accept-Ranges = acceptable-ranges
Content-Range = byte-content-range / other-content-range Content-Range = byte-content-range / other-content-range
HTTP-date = <HTTP-date, defined in [Part2], Section 7.1.1.1> HTTP-date = <HTTP-date, see [RFC7231], Section 7.1.1.1>
If-Range = entity-tag / HTTP-date If-Range = entity-tag / HTTP-date
OWS = <OWS, defined in [Part1], Section 3.2.3> OWS = <OWS, see [RFC7230], Section 3.2.3>
Range = byte-ranges-specifier / other-ranges-specifier Range = byte-ranges-specifier / other-ranges-specifier
acceptable-ranges = ( *( "," OWS ) range-unit *( OWS "," [ OWS acceptable-ranges = ( *( "," OWS ) range-unit *( OWS "," [ OWS
range-unit ] ) ) / "none" range-unit ] ) ) / "none"
byte-content-range = bytes-unit SP ( byte-range-resp / byte-content-range = bytes-unit SP ( byte-range-resp /
unsatisfied-range ) unsatisfied-range )
byte-range = first-byte-pos "-" last-byte-pos byte-range = first-byte-pos "-" last-byte-pos
byte-range-resp = byte-range "/" ( complete-length / "*" ) byte-range-resp = byte-range "/" ( complete-length / "*" )
byte-range-set = *( "," OWS ) ( byte-range-spec / byte-range-set = *( "," OWS ) ( byte-range-spec /
suffix-byte-range-spec ) *( OWS "," [ OWS ( byte-range-spec / suffix-byte-range-spec ) *( OWS "," [ OWS ( byte-range-spec /
suffix-byte-range-spec ) ] ) suffix-byte-range-spec ) ] )
byte-range-spec = first-byte-pos "-" [ last-byte-pos ] byte-range-spec = first-byte-pos "-" [ last-byte-pos ]
byte-ranges-specifier = bytes-unit "=" byte-range-set byte-ranges-specifier = bytes-unit "=" byte-range-set
bytes-unit = "bytes" bytes-unit = "bytes"
complete-length = 1*DIGIT complete-length = 1*DIGIT
entity-tag = <entity-tag, defined in [Part4], Section 2.3> entity-tag = <entity-tag, see [RFC7232], Section 2.3>
first-byte-pos = 1*DIGIT first-byte-pos = 1*DIGIT
last-byte-pos = 1*DIGIT last-byte-pos = 1*DIGIT
other-content-range = other-range-unit SP other-range-resp other-content-range = other-range-unit SP other-range-resp
other-range-resp = *CHAR other-range-resp = *CHAR
other-range-set = 1*VCHAR other-range-set = 1*VCHAR
other-range-unit = token other-range-unit = token
other-ranges-specifier = other-range-unit "=" other-range-set other-ranges-specifier = other-range-unit "=" other-range-set
range-unit = bytes-unit / other-range-unit range-unit = bytes-unit / other-range-unit
suffix-byte-range-spec = "-" suffix-length suffix-byte-range-spec = "-" suffix-length
suffix-length = 1*DIGIT suffix-length = 1*DIGIT
token = <token, defined in [Part1], Section 3.2.6> token = <token, see [RFC7230], Section 3.2.6>
unsatisfied-range = "*/" complete-length unsatisfied-range = "*/" complete-length
Appendix E. Change Log (to be removed by RFC Editor before publication)
Changes up to the IETF Last Call draft are summarized in <http://
tools.ietf.org/html/draft-ietf-httpbis-p5-range-24#appendix-E>.
E.1. Since draft-ietf-httpbis-p5-range-24
Closed issues:
o <http://tools.ietf.org/wg/httpbis/trac/ticket/506>: "APPSDIR
review of draft-ietf-httpbis-p5-range-24"
o <http://tools.ietf.org/wg/httpbis/trac/ticket/507>: "integer value
parsing"
o <http://tools.ietf.org/wg/httpbis/trac/ticket/508>: "broken
sentence in description of 206"
E.2. Since draft-ietf-httpbis-p5-range-25
Closed issues:
o <http://tools.ietf.org/wg/httpbis/trac/ticket/526>: "check media
type registration templates"
o <http://tools.ietf.org/wg/httpbis/trac/ticket/527>: "use of CHAR
for other-range-set"
o <http://tools.ietf.org/wg/httpbis/trac/ticket/538>: "add
'stateless' to Abstract"
o <http://tools.ietf.org/wg/httpbis/trac/ticket/542>: "improve
introduction of list rule"
o <http://tools.ietf.org/wg/httpbis/trac/ticket/549>: "augment
security considerations with pointers to current research"
Index Index
2 2
206 Partial Content (status code) 10 206 Partial Content (status code) 10
4 4
416 Range Not Satisfiable (status code) 15 416 Range Not Satisfiable (status code) 15
A A
Accept-Ranges header field 7 Accept-Ranges header field 7
 End of changes. 49 change blocks. 
117 lines changed or deleted 76 lines changed or added

This html diff was produced by rfcdiff 1.38. The latest version is available from http://tools.ietf.org/tools/rfcdiff/