aboutsummaryrefslogtreecommitdiff
path: root/rfc/rfc7233.txt
diff options
context:
space:
mode:
Diffstat (limited to 'rfc/rfc7233.txt')
-rw-r--r--rfc/rfc7233.txt1403
1 files changed, 1403 insertions, 0 deletions
diff --git a/rfc/rfc7233.txt b/rfc/rfc7233.txt
new file mode 100644
index 0000000..af212e7
--- /dev/null
+++ b/rfc/rfc7233.txt
@@ -0,0 +1,1403 @@
+
+
+
+
+
+
+Internet Engineering Task Force (IETF) R. Fielding, Ed.
+Request for Comments: 7233 Adobe
+Obsoletes: 2616 Y. Lafon, Ed.
+Category: Standards Track W3C
+ISSN: 2070-1721 J. Reschke, Ed.
+ greenbytes
+ June 2014
+
+
+ Hypertext Transfer Protocol (HTTP/1.1): Range Requests
+
+Abstract
+
+ The Hypertext Transfer Protocol (HTTP) is a stateless application-
+ level protocol for distributed, collaborative, hypertext information
+ systems. This document defines range requests and the rules for
+ constructing and combining responses to those requests.
+
+Status of This Memo
+
+ This is an Internet Standards Track document.
+
+ This document is a product of the Internet Engineering Task Force
+ (IETF). It represents the consensus of the IETF community. It has
+ received public review and has been approved for publication by the
+ Internet Engineering Steering Group (IESG). Further information on
+ Internet Standards is available in Section 2 of RFC 5741.
+
+ Information about the current status of this document, any errata,
+ and how to provide feedback on it may be obtained at
+ http://www.rfc-editor.org/info/rfc7233.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Fielding, et al. Standards Track [Page 1]
+
+RFC 7233 HTTP/1.1 Range Requests June 2014
+
+
+Copyright Notice
+
+ Copyright (c) 2014 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. Code Components extracted from this document must
+ include Simplified BSD License text as described in Section 4.e of
+ the Trust Legal Provisions and are provided without warranty as
+ described in the Simplified BSD License.
+
+ This document may contain material from IETF Documents or IETF
+ Contributions published or made publicly available before November
+ 10, 2008. The person(s) controlling the copyright in some of this
+ material may not have granted the IETF Trust the right to allow
+ modifications of such material outside the IETF Standards Process.
+ Without obtaining an adequate license from the person(s) controlling
+ the copyright in such materials, this document may not be modified
+ outside the IETF Standards Process, and derivative works of it may
+ not be created outside the IETF Standards Process, except to format
+ it for publication as an RFC or to translate it into languages other
+ than English.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Fielding, et al. Standards Track [Page 2]
+
+RFC 7233 HTTP/1.1 Range Requests June 2014
+
+
+Table of Contents
+
+ 1. Introduction ....................................................4
+ 1.1. Conformance and Error Handling .............................4
+ 1.2. Syntax Notation ............................................4
+ 2. Range Units .....................................................5
+ 2.1. Byte Ranges ................................................5
+ 2.2. Other Range Units ..........................................7
+ 2.3. Accept-Ranges ..............................................7
+ 3. Range Requests ..................................................8
+ 3.1. Range ......................................................8
+ 3.2. If-Range ...................................................9
+ 4. Responses to a Range Request ...................................10
+ 4.1. 206 Partial Content .......................................10
+ 4.2. Content-Range .............................................12
+ 4.3. Combining Ranges ..........................................14
+ 4.4. 416 Range Not Satisfiable .................................15
+ 5. IANA Considerations ............................................16
+ 5.1. Range Unit Registry .......................................16
+ 5.1.1. Procedure ..........................................16
+ 5.1.2. Registrations ......................................16
+ 5.2. Status Code Registration ..................................17
+ 5.3. Header Field Registration .................................17
+ 5.4. Internet Media Type Registration ..........................17
+ 5.4.1. Internet Media Type multipart/byteranges ...........18
+ 6. Security Considerations ........................................19
+ 6.1. Denial-of-Service Attacks Using Range .....................19
+ 7. Acknowledgments ................................................19
+ 8. References .....................................................20
+ 8.1. Normative References ......................................20
+ 8.2. Informative References ....................................20
+ Appendix A. Internet Media Type multipart/byteranges ..............21
+ Appendix B. Changes from RFC 2616 .................................22
+ Appendix C. Imported ABNF .........................................22
+ Appendix D. Collected ABNF ........................................23
+ Index .............................................................24
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Fielding, et al. Standards Track [Page 3]
+
+RFC 7233 HTTP/1.1 Range Requests June 2014
+
+
+1. Introduction
+
+ Hypertext Transfer Protocol (HTTP) clients often encounter
+ interrupted data transfers as a result of canceled requests or
+ dropped connections. When a client has stored a partial
+ representation, it is desirable to request the remainder of that
+ representation in a subsequent request rather than transfer the
+ entire representation. Likewise, devices with limited local storage
+ might benefit from being able to request only a subset of a larger
+ representation, such as a single page of a very large document, or
+ the dimensions of an embedded image.
+
+ This document defines HTTP/1.1 range requests, partial responses, and
+ the multipart/byteranges media type. Range requests are an OPTIONAL
+ feature of HTTP, designed so that recipients not implementing this
+ feature (or not supporting it for the target resource) can respond as
+ if it is a normal GET request without impacting interoperability.
+ Partial responses are indicated by a distinct status code to not be
+ mistaken for full responses by caches that might not implement the
+ feature.
+
+ Although the range request mechanism is designed to allow for
+ extensible range types, this specification only defines requests for
+ byte ranges.
+
+1.1. Conformance and Error Handling
+
+ 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].
+
+ Conformance criteria and considerations regarding error handling are
+ defined in Section 2.5 of [RFC7230].
+
+1.2. Syntax Notation
+
+ This specification uses the Augmented Backus-Naur Form (ABNF)
+ notation of [RFC5234] with a list extension, defined in Section 7 of
+ [RFC7230], that allows for compact definition of comma-separated
+ lists using a '#' operator (similar to how the '*' operator indicates
+ repetition). Appendix C describes rules imported from other
+ documents. Appendix D shows the collected grammar with all list
+ operators expanded to standard ABNF notation.
+
+
+
+
+
+
+
+
+Fielding, et al. Standards Track [Page 4]
+
+RFC 7233 HTTP/1.1 Range Requests June 2014
+
+
+2. Range Units
+
+ A representation can be partitioned into subranges according to
+ various structural units, depending on the structure inherent in the
+ representation's media type. This "range unit" is used in the
+ Accept-Ranges (Section 2.3) response header field to advertise
+ support for range requests, the Range (Section 3.1) request header
+ field to delineate the parts of a representation that are requested,
+ and the Content-Range (Section 4.2) payload header field to describe
+ which part of a representation is being transferred.
+
+ range-unit = bytes-unit / other-range-unit
+
+2.1. Byte Ranges
+
+ Since representation data is transferred in payloads as a sequence of
+ octets, a byte range is a meaningful substructure for any
+ representation transferable over HTTP (Section 3 of [RFC7231]). The
+ "bytes" range unit is defined for expressing subranges of the data's
+ octet sequence.
+
+ bytes-unit = "bytes"
+
+ A byte-range request can specify a single range of bytes or a set of
+ ranges within a single representation.
+
+ byte-ranges-specifier = bytes-unit "=" byte-range-set
+ byte-range-set = 1#( byte-range-spec / suffix-byte-range-spec )
+ byte-range-spec = first-byte-pos "-" [ last-byte-pos ]
+ first-byte-pos = 1*DIGIT
+ last-byte-pos = 1*DIGIT
+
+ 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
+ byte-offset of the last byte in the range; that is, the byte
+ positions specified are inclusive. Byte offsets start at zero.
+
+ Examples of byte-ranges-specifier values:
+
+ o The first 500 bytes (byte offsets 0-499, inclusive):
+
+ bytes=0-499
+
+ o The second 500 bytes (byte offsets 500-999, inclusive):
+
+ bytes=500-999
+
+
+
+
+
+Fielding, et al. Standards Track [Page 5]
+
+RFC 7233 HTTP/1.1 Range Requests June 2014
+
+
+ A byte-range-spec is invalid if the last-byte-pos value is present
+ and less than the first-byte-pos.
+
+ A client can limit the number of bytes requested without knowing the
+ size of the selected representation. If the last-byte-pos value is
+ absent, or if the value is greater than or equal to the current
+ length of the representation data, the byte range is interpreted as
+ the remainder of the representation (i.e., the server replaces the
+ value of last-byte-pos with a value that is one less than the current
+ length of the selected representation).
+
+ A client can request the last N bytes of the selected representation
+ using a suffix-byte-range-spec.
+
+ suffix-byte-range-spec = "-" suffix-length
+ suffix-length = 1*DIGIT
+
+ If the selected representation is shorter than the specified
+ suffix-length, the entire representation is used.
+
+ Additional examples, assuming a representation of length 10000:
+
+ o The final 500 bytes (byte offsets 9500-9999, inclusive):
+
+ bytes=-500
+
+ Or:
+
+ bytes=9500-
+
+ o The first and last bytes only (bytes 0 and 9999):
+
+ bytes=0-0,-1
+
+ o Other valid (but not canonical) specifications of the second 500
+ bytes (byte offsets 500-999, inclusive):
+
+ bytes=500-600,601-999
+ bytes=500-700,601-999
+
+ 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
+ representation, or at least one suffix-byte-range-spec with a
+ non-zero suffix-length, then the byte-range-set is satisfiable.
+ Otherwise, the byte-range-set is unsatisfiable.
+
+
+
+
+
+
+Fielding, et al. Standards Track [Page 6]
+
+RFC 7233 HTTP/1.1 Range Requests June 2014
+
+
+ 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 predefined limit to the length of a payload, recipients MUST
+ anticipate potentially large decimal numerals and prevent parsing
+ errors due to integer conversion overflows.
+
+2.2. Other Range Units
+
+ Range units are intended to be extensible. New range units ought to
+ be registered with IANA, as defined in Section 5.1.
+
+ other-range-unit = token
+
+2.3. Accept-Ranges
+
+ The "Accept-Ranges" header field allows a server to indicate that it
+ supports range requests for the target resource.
+
+ Accept-Ranges = acceptable-ranges
+ acceptable-ranges = 1#range-unit / "none"
+
+ An origin server that supports byte-range requests for a given target
+ resource MAY send
+
+ Accept-Ranges: bytes
+
+ to indicate what range units are supported. A client MAY generate
+ range requests without having received this header field for the
+ resource involved. Range units are defined in Section 2.
+
+ A server that does not support any kind of range request for the
+ target resource MAY send
+
+ Accept-Ranges: none
+
+ to advise the client not to attempt a range request.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Fielding, et al. Standards Track [Page 7]
+
+RFC 7233 HTTP/1.1 Range Requests June 2014
+
+
+3. Range Requests
+
+3.1. Range
+
+ The "Range" header field on a GET request modifies the method
+ semantics to request transfer of only one or more subranges of the
+ selected representation data, rather than the entire selected
+ representation data.
+
+ Range = byte-ranges-specifier / other-ranges-specifier
+ other-ranges-specifier = other-range-unit "=" other-range-set
+ other-range-set = 1*VCHAR
+
+ A server MAY ignore the Range header field. However, origin servers
+ and intermediate caches ought to support byte ranges when possible,
+ since Range supports efficient recovery from partially failed
+ transfers and partial retrieval of large representations. A server
+ MUST ignore a Range header field received with a request method other
+ than GET.
+
+ An origin server MUST ignore a Range header field that contains a
+ range unit it does not understand. A proxy MAY discard a Range
+ header field that contains a range unit it does not understand.
+
+ A server that supports range requests MAY ignore or reject a Range
+ header field that consists of more than two overlapping ranges, or a
+ set of many small ranges that are not listed in ascending order,
+ since both are indications of either a broken client or a deliberate
+ denial-of-service attack (Section 6.1). A client SHOULD NOT request
+ multiple ranges that are inherently less efficient to process and
+ transfer than a single range that encompasses the same data.
+
+ A client that is requesting multiple ranges SHOULD list those ranges
+ in ascending order (the order in which they would typically be
+ received in a complete representation) unless there is a specific
+ need to request a later part earlier. For example, a user agent
+ processing a large representation with an internal catalog of parts
+ might need to request later parts first, particularly if the
+ representation consists of pages stored in reverse order and the user
+ agent wishes to transfer one page at a time.
+
+ The Range header field is evaluated after evaluating the precondition
+ 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
+ words, Range is ignored when a conditional GET would result in a 304
+ (Not Modified) response.
+
+
+
+
+
+Fielding, et al. Standards Track [Page 8]
+
+RFC 7233 HTTP/1.1 Range Requests June 2014
+
+
+ The If-Range header field (Section 3.2) can be used as a precondition
+ to applying the Range header field.
+
+ If all of the preconditions are true, the server supports the Range
+ header field for the target resource, and the specified range(s) are
+ valid and satisfiable (as defined in Section 2.1), the server SHOULD
+ send a 206 (Partial Content) response with a payload containing one
+ or more partial representations that correspond to the satisfiable
+ ranges requested, as defined in Section 4.
+
+ If all of the preconditions are true, the server supports the Range
+ header field for the target resource, and the specified range(s) are
+ invalid or unsatisfiable, the server SHOULD send a 416 (Range Not
+ Satisfiable) response.
+
+3.2. If-Range
+
+ 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
+ Range header field with a conditional GET (using either or both of
+ If-Unmodified-Since and If-Match.) However, if the precondition
+ fails because the representation has been modified, the client would
+ then have to make a second request to obtain the entire current
+ representation.
+
+ The "If-Range" header field allows a client to "short-circuit" the
+ second request. Informally, its meaning is as follows: if the
+ representation is unchanged, send me the part(s) that I am requesting
+ in Range; otherwise, send me the entire representation.
+
+ If-Range = entity-tag / HTTP-date
+
+ 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-Range header field received in a request that does not contain a
+ Range header field. An origin server MUST ignore an If-Range header
+ field received in a request for a target resource that does not
+ support Range requests.
+
+ 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-Range header field containing an HTTP-date unless the client has
+ no entity-tag for the corresponding representation and the date is a
+ 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
+ comparison function when comparing entity-tags (Section 2.3.2 of
+ [RFC7232]) and MUST evaluate the condition as false if an HTTP-date
+
+
+
+Fielding, et al. Standards Track [Page 9]
+
+RFC 7233 HTTP/1.1 Range Requests June 2014
+
+
+ validator is provided that is not a strong validator in the sense
+ 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
+ characters for a DQUOTE.
+
+ If the validator given in the If-Range header field matches the
+ current validator for the selected representation of the target
+ resource, then the server SHOULD process the Range header field as
+ requested. If the validator does not match, the server MUST ignore
+ the Range header field. Note that this comparison by exact match,
+ including when the validator is an HTTP-date, differs from the
+ "earlier than or equal to" comparison used when evaluating an
+ If-Unmodified-Since conditional.
+
+4. Responses to a Range Request
+
+4.1. 206 Partial Content
+
+ The 206 (Partial Content) status code indicates that the server is
+ successfully fulfilling a range request for the target resource by
+ transferring one or more parts of the selected representation that
+ correspond to the satisfiable ranges found in the request's Range
+ header field (Section 3.1).
+
+ If a single part is being transferred, the server generating the 206
+ response MUST generate a Content-Range header field, describing what
+ range of the selected representation is enclosed, and a payload
+ consisting of the range. For example:
+
+ HTTP/1.1 206 Partial Content
+ Date: Wed, 15 Nov 1995 06:25:24 GMT
+ Last-Modified: Wed, 15 Nov 1995 04:58:08 GMT
+ Content-Range: bytes 21010-47021/47022
+ Content-Length: 26012
+ Content-Type: image/gif
+
+ ... 26012 bytes of partial image data ...
+
+ If multiple parts are being transferred, the server generating the
+ 206 response MUST generate a "multipart/byteranges" payload, as
+ defined in Appendix A, and a Content-Type header field containing the
+ multipart/byteranges media type and its required boundary parameter.
+ To avoid confusion with single-part responses, a server MUST NOT
+ generate a Content-Range header field in the HTTP header section of a
+ multiple part response (this field will be sent in each part
+ instead).
+
+
+
+
+
+Fielding, et al. Standards Track [Page 10]
+
+RFC 7233 HTTP/1.1 Range Requests June 2014
+
+
+ Within the header area of each body part in the multipart payload,
+ the server MUST generate a Content-Range header field corresponding
+ to the range being enclosed in that body part. If the selected
+ representation would have had a Content-Type header field in a 200
+ (OK) response, the server SHOULD generate that same Content-Type
+ field in the header area of each body part. For example:
+
+ HTTP/1.1 206 Partial Content
+ Date: Wed, 15 Nov 1995 06:25:24 GMT
+ Last-Modified: Wed, 15 Nov 1995 04:58:08 GMT
+ Content-Length: 1741
+ Content-Type: multipart/byteranges; boundary=THIS_STRING_SEPARATES
+
+ --THIS_STRING_SEPARATES
+ Content-Type: application/pdf
+ Content-Range: bytes 500-999/8000
+
+ ...the first range...
+ --THIS_STRING_SEPARATES
+ Content-Type: application/pdf
+ Content-Range: bytes 7000-7999/8000
+
+ ...the second range
+ --THIS_STRING_SEPARATES--
+
+ When multiple ranges are requested, a server MAY coalesce any of the
+ ranges that overlap, or that are separated by a gap that is smaller
+ than the overhead of sending multiple parts, regardless of the order
+ in which the corresponding byte-range-spec appeared in the received
+ Range header field. Since the typical overhead between parts of a
+ multipart/byteranges payload is around 80 bytes, depending on the
+ selected representation's media type and the chosen boundary
+ parameter length, it can be less efficient to transfer many small
+ disjoint parts than it is to transfer the entire selected
+ representation.
+
+ A server MUST NOT generate a multipart response to a request for a
+ single range, since a client that does not request multiple parts
+ might not support multipart responses. However, a server MAY
+ generate a multipart/byteranges payload with only a single body part
+ if multiple ranges were requested and only one range was found to be
+ satisfiable or only one range remained after coalescing. A client
+ that cannot process a multipart/byteranges response MUST NOT generate
+ a request that asks for multiple ranges.
+
+ When a multipart response payload is generated, the server SHOULD
+ send the parts in the same order that the corresponding
+ byte-range-spec appeared in the received Range header field,
+
+
+
+Fielding, et al. Standards Track [Page 11]
+
+RFC 7233 HTTP/1.1 Range Requests June 2014
+
+
+ excluding those ranges that were deemed unsatisfiable or that were
+ coalesced into other ranges. A client that receives a multipart
+ response MUST inspect the Content-Range header field present in each
+ body part in order to determine which range is contained in that body
+ part; a client cannot rely on receiving the same ranges that it
+ requested, nor the same order that it requested.
+
+ When a 206 response is generated, the server MUST generate the
+ following header fields, in addition to those required above, if the
+ field would have been sent in a 200 (OK) response to the same
+ request: Date, Cache-Control, ETag, Expires, Content-Location, and
+ Vary.
+
+ If a 206 is generated in response to a request with an If-Range
+ header field, the sender SHOULD NOT generate other representation
+ header fields beyond those required above, because the client is
+ understood to already have a prior response containing those header
+ fields. Otherwise, the sender MUST generate all of the
+ representation header fields that would have been sent in a 200 (OK)
+ response to the same request.
+
+ A 206 response is cacheable by default; i.e., unless otherwise
+ indicated by explicit cache controls (see Section 4.2.2 of
+ [RFC7234]).
+
+4.2. Content-Range
+
+ The "Content-Range" header field is sent in a single part 206
+ (Partial Content) response to indicate the partial range of the
+ selected representation enclosed as the message payload, sent in each
+ part of a multipart 206 response to indicate the range enclosed
+ within each body part, and sent in 416 (Range Not Satisfiable)
+ responses to provide information about the selected representation.
+
+ 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
+
+
+
+Fielding, et al. Standards Track [Page 12]
+
+RFC 7233 HTTP/1.1 Range Requests June 2014
+
+
+ If a 206 (Partial Content) response contains a Content-Range header
+ field with a range unit (Section 2) that the recipient does not
+ understand, the recipient MUST NOT attempt to recombine it with a
+ stored representation. A proxy that receives such a message SHOULD
+ forward it downstream.
+
+ 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.
+
+ 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/*
+
+ 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 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 attempt to recombine the received content with
+ a stored representation.
+
+ A server generating a 416 (Range Not Satisfiable) response to a
+ byte-range request SHOULD send a Content-Range header field with an
+ unsatisfied-range value, as in the following example:
+
+ Content-Range: bytes */1234
+
+ The complete-length in a 416 response indicates the current length of
+ the selected representation.
+
+ The Content-Range header field has no meaning for status codes that
+ do not explicitly describe its semantic. For this specification,
+ only the 206 (Partial Content) and 416 (Range Not Satisfiable) status
+ codes describe a meaning for Content-Range.
+
+
+
+
+
+
+
+
+Fielding, et al. Standards Track [Page 13]
+
+RFC 7233 HTTP/1.1 Range Requests June 2014
+
+
+ The following are examples of Content-Range values in which the
+ selected representation contains a total of 1234 bytes:
+
+ o The first 500 bytes:
+
+ Content-Range: bytes 0-499/1234
+
+ o The second 500 bytes:
+
+ Content-Range: bytes 500-999/1234
+
+ o All except for the first 500 bytes:
+
+ Content-Range: bytes 500-1233/1234
+
+ o The last 500 bytes:
+
+ Content-Range: bytes 734-1233/1234
+
+4.3. Combining Ranges
+
+ A response might transfer only a subrange of a representation if the
+ connection closed prematurely or if the request used one or more
+ Range specifications. After several such transfers, a client might
+ have received several ranges of the same representation. These
+ ranges can only be safely combined if they all have in common the
+ same strong validator (Section 2.1 of [RFC7232]).
+
+ A client that has received multiple partial responses to GET requests
+ on a target resource MAY combine those responses into a larger
+ continuous range if they share the same strong validator.
+
+ If the most recent response is an incomplete 200 (OK) response, then
+ the header fields of that response are used for any combined response
+ and replace those of the matching stored responses.
+
+ If the most recent response is a 206 (Partial Content) response and
+ at least one of the matching stored responses is a 200 (OK), then the
+ combined response header fields consist of the most recent 200
+ response's header fields. If all of the matching stored responses
+ are 206 responses, then the stored response with the most recent
+ header fields is used as the source of header fields for the combined
+ response, except that the client MUST use other header fields
+ provided in the new response, aside from Content-Range, to replace
+ all instances of the corresponding header fields in the stored
+ response.
+
+
+
+
+
+Fielding, et al. Standards Track [Page 14]
+
+RFC 7233 HTTP/1.1 Range Requests June 2014
+
+
+ The combined response message body consists of the union of partial
+ content ranges in the new response and each of the selected
+ responses. If the union consists of the entire range of the
+ representation, then the client MUST process the combined response as
+ if it were a complete 200 (OK) response, including a Content-Length
+ header field that reflects the complete length. Otherwise, the
+ client MUST process the set of continuous ranges as one of the
+ following: an incomplete 200 (OK) response if the combined response
+ is a prefix of the representation, a single 206 (Partial Content)
+ response containing a multipart/byteranges body, or multiple 206
+ (Partial Content) responses, each with one continuous range that is
+ indicated by a Content-Range header field.
+
+4.4. 416 Range Not Satisfiable
+
+ 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 current extent of the selected resource or that the set of ranges
+ requested has been rejected due to invalid ranges or an excessive
+ request of small or overlapping ranges.
+
+ 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
+ the current length of the selected representation. When this status
+ code is generated in response to a byte-range request, the sender
+ SHOULD generate a Content-Range header field specifying the current
+ length of the selected representation (Section 4.2).
+
+ For example:
+
+ HTTP/1.1 416 Range Not Satisfiable
+ Date: Fri, 20 Jan 2012 15:41:54 GMT
+ Content-Range: bytes */47022
+
+ Note: Because servers are free to ignore Range, many
+ implementations will simply respond with the entire selected
+ representation in a 200 (OK) response. That is partly because
+ most clients are prepared to receive a 200 (OK) to complete the
+ task (albeit less efficiently) and partly because clients might
+ not stop making an invalid partial request until they have
+ received a complete representation. Thus, clients cannot depend
+ on receiving a 416 (Range Not Satisfiable) response even when it
+ is most appropriate.
+
+
+
+
+
+
+
+
+Fielding, et al. Standards Track [Page 15]
+
+RFC 7233 HTTP/1.1 Range Requests June 2014
+
+
+5. IANA Considerations
+
+5.1. Range Unit Registry
+
+ The "HTTP Range Unit Registry" defines the namespace for the range
+ unit names and refers to their corresponding specifications. The
+ registry has been created and is now maintained at
+ <http://www.iana.org/assignments/http-parameters>.
+
+5.1.1. Procedure
+
+ Registration of an HTTP Range Unit MUST include the following fields:
+
+ o Name
+
+ o Description
+
+ o Pointer to specification text
+
+ Values to be added to this namespace require IETF Review (see
+ [RFC5226], Section 4.1).
+
+5.1.2. Registrations
+
+ The initial range unit registry contains the registrations below:
+
+ +-------------+---------------------------------------+-------------+
+ | Range Unit | Description | Reference |
+ | Name | | |
+ +-------------+---------------------------------------+-------------+
+ | bytes | a range of octets | Section 2.1 |
+ | none | reserved as keyword, indicating no | Section 2.3 |
+ | | ranges are supported | |
+ +-------------+---------------------------------------+-------------+
+
+ The change controller is: "IETF (iesg@ietf.org) - Internet
+ Engineering Task Force".
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Fielding, et al. Standards Track [Page 16]
+
+RFC 7233 HTTP/1.1 Range Requests June 2014
+
+
+5.2. Status Code Registration
+
+ The "Hypertext Transfer Protocol (HTTP) Status Code Registry" located
+ at <http://www.iana.org/assignments/http-status-codes> has been
+ updated to include the registrations below:
+
+ +-------+-----------------------+-------------+
+ | Value | Description | Reference |
+ +-------+-----------------------+-------------+
+ | 206 | Partial Content | Section 4.1 |
+ | 416 | Range Not Satisfiable | Section 4.4 |
+ +-------+-----------------------+-------------+
+
+5.3. Header Field Registration
+
+ HTTP header fields are registered within the "Message Headers"
+ registry maintained at
+ <http://www.iana.org/assignments/message-headers/>.
+
+ This document defines the following HTTP header fields, so their
+ associated registry entries have been updated according to the
+ permanent registrations below (see [BCP90]):
+
+ +-------------------+----------+----------+-------------+
+ | Header Field Name | Protocol | Status | Reference |
+ +-------------------+----------+----------+-------------+
+ | Accept-Ranges | http | standard | Section 2.3 |
+ | Content-Range | http | standard | Section 4.2 |
+ | If-Range | http | standard | Section 3.2 |
+ | Range | http | standard | Section 3.1 |
+ +-------------------+----------+----------+-------------+
+
+ The change controller is: "IETF (iesg@ietf.org) - Internet
+ Engineering Task Force".
+
+5.4. Internet Media Type Registration
+
+ IANA maintains the registry of Internet media types [BCP13] at
+ <http://www.iana.org/assignments/media-types>.
+
+ This document serves as the specification for the Internet media type
+ "multipart/byteranges". The following has been registered with IANA.
+
+
+
+
+
+
+
+
+
+Fielding, et al. Standards Track [Page 17]
+
+RFC 7233 HTTP/1.1 Range Requests June 2014
+
+
+5.4.1. Internet Media Type multipart/byteranges
+
+ Type name: multipart
+
+ Subtype name: byteranges
+
+ Required parameters: boundary
+
+ Optional parameters: N/A
+
+ Encoding considerations: only "7bit", "8bit", or "binary" are
+ permitted
+
+ Security considerations: see Section 6
+
+ Interoperability considerations: N/A
+
+ Published specification: This specification (see Appendix A).
+
+ Applications that use this media type: HTTP components supporting
+ multiple ranges in a single request.
+
+ Fragment identifier considerations: N/A
+
+ Additional information:
+
+ Deprecated alias names for this type: N/A
+
+ Magic number(s): N/A
+
+ File extension(s): N/A
+
+ Macintosh file type code(s): N/A
+
+ Person and email address to contact for further information: See
+ Authors' Addresses section.
+
+ Intended usage: COMMON
+
+ Restrictions on usage: N/A
+
+ Author: See Authors' Addresses section.
+
+ Change controller: IESG
+
+
+
+
+
+
+
+Fielding, et al. Standards Track [Page 18]
+
+RFC 7233 HTTP/1.1 Range Requests June 2014
+
+
+6. Security Considerations
+
+ This section is meant to inform developers, information providers,
+ and users of known security concerns specific to the HTTP range
+ request mechanisms. More general security considerations are
+ addressed in HTTP messaging [RFC7230] and semantics [RFC7231].
+
+6.1. Denial-of-Service Attacks Using Range
+
+ Unconstrained multiple range requests are susceptible to denial-of-
+ service attacks because the effort required to request many
+ overlapping ranges of the same data is tiny compared to the time,
+ memory, and bandwidth consumed by attempting to serve the requested
+ data in many parts. Servers ought to ignore, coalesce, or reject
+ egregious range requests, such as requests for more than two
+ overlapping ranges or for many small ranges in a single set,
+ particularly when the ranges are requested out of order for no
+ apparent reason. Multipart range requests are not designed to
+ support random access.
+
+7. Acknowledgments
+
+ See Section 10 of [RFC7230].
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Fielding, et al. Standards Track [Page 19]
+
+RFC 7233 HTTP/1.1 Range Requests June 2014
+
+
+8. References
+
+8.1. Normative References
+
+ [RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
+ Extensions (MIME) Part Two: Media Types", RFC 2046,
+ November 1996.
+
+ [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
+ Requirement Levels", BCP 14, RFC 2119, March 1997.
+
+ [RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
+ 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",
+ RFC 7230, June 2014.
+
+ [RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
+ Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
+ June 2014.
+
+ [RFC7232] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
+ Protocol (HTTP/1.1): Conditional Requests", RFC 7232,
+ June 2014.
+
+ [RFC7234] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
+ Ed., "Hypertext Transfer Protocol (HTTP/1.1): Caching",
+ RFC 7234, June 2014.
+
+8.2. Informative References
+
+ [BCP13] Freed, N., Klensin, J., and T. Hansen, "Media Type
+ Specifications and Registration Procedures", BCP 13,
+ RFC 6838, January 2013.
+
+ [BCP90] Klyne, G., Nottingham, M., and J. Mogul, "Registration
+ Procedures for Message Header Fields", BCP 90, RFC 3864,
+ September 2004.
+
+ [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
+ Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
+ Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
+
+ [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
+ IANA Considerations Section in RFCs", BCP 26, RFC 5226,
+ May 2008.
+
+
+
+
+Fielding, et al. Standards Track [Page 20]
+
+RFC 7233 HTTP/1.1 Range Requests June 2014
+
+
+Appendix A. Internet Media Type multipart/byteranges
+
+ When a 206 (Partial Content) response message includes the content of
+ multiple ranges, they are transmitted as body parts in a multipart
+ message body ([RFC2046], Section 5.1) with the media type of
+ "multipart/byteranges".
+
+ The multipart/byteranges media type includes one or more body parts,
+ each with its own Content-Type and Content-Range fields. The
+ required boundary parameter specifies the boundary string used to
+ separate each body part.
+
+ Implementation Notes:
+
+ 1. Additional CRLFs might precede the first boundary string in the
+ body.
+
+ 2. Although [RFC2046] permits the boundary string to be quoted, some
+ existing implementations handle a quoted boundary string
+ incorrectly.
+
+ 3. A number of clients and servers were coded to an early draft of
+ the byteranges specification that used a media type of multipart/
+ x-byteranges, which is almost (but not quite) compatible with
+ this type.
+
+ Despite the name, the "multipart/byteranges" media type is not
+ limited to byte ranges. The following example uses an "exampleunit"
+ range unit:
+
+ HTTP/1.1 206 Partial Content
+ Date: Tue, 14 Nov 1995 06:25:24 GMT
+ Last-Modified: Tue, 14 July 04:58:08 GMT
+ Content-Length: 2331785
+ Content-Type: multipart/byteranges; boundary=THIS_STRING_SEPARATES
+
+ --THIS_STRING_SEPARATES
+ Content-Type: video/example
+ Content-Range: exampleunit 1.2-4.3/25
+
+ ...the first range...
+ --THIS_STRING_SEPARATES
+ Content-Type: video/example
+ Content-Range: exampleunit 11.2-14.3/25
+
+ ...the second range
+ --THIS_STRING_SEPARATES--
+
+
+
+
+Fielding, et al. Standards Track [Page 21]
+
+RFC 7233 HTTP/1.1 Range Requests June 2014
+
+
+Appendix B. Changes from RFC 2616
+
+ Servers are given more leeway in how they respond to a range request,
+ in order to mitigate abuse by malicious (or just greedy) clients.
+ (Section 3.1)
+
+ A weak validator cannot be used in a 206 response. (Section 4.1)
+
+ The Content-Range header field only has meaning when the status code
+ explicitly defines its use. (Section 4.2)
+
+ This specification introduces a Range Unit Registry. (Section 5.1)
+
+ multipart/byteranges can consist of a single part. (Appendix A)
+
+Appendix C. Imported ABNF
+
+ The following core rules are included by reference, as defined in
+ Appendix B.1 of [RFC5234]: ALPHA (letters), CR (carriage return),
+ 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
+ 8-bit sequence of data), SP (space), and VCHAR (any visible US-ASCII
+ character).
+
+ Note that all rules derived from token are to be compared
+ case-insensitively, like range-unit and acceptable-ranges.
+
+ The rules below are defined in [RFC7230]:
+
+ OWS = <OWS, see [RFC7230], Section 3.2.3>
+ token = <token, see [RFC7230], Section 3.2.6>
+
+ The rules below are defined in other parts:
+
+ HTTP-date = <HTTP-date, see [RFC7231], Section 7.1.1.1>
+ entity-tag = <entity-tag, see [RFC7232], Section 2.3>
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Fielding, et al. Standards Track [Page 22]
+
+RFC 7233 HTTP/1.1 Range Requests June 2014
+
+
+Appendix D. Collected ABNF
+
+ In the collected ABNF below, list rules are expanded as per Section
+ 1.2 of [RFC7230].
+
+ Accept-Ranges = acceptable-ranges
+
+ Content-Range = byte-content-range / other-content-range
+
+ HTTP-date = <HTTP-date, see [RFC7231], Section 7.1.1.1>
+
+ If-Range = entity-tag / HTTP-date
+
+ OWS = <OWS, see [RFC7230], Section 3.2.3>
+
+ Range = byte-ranges-specifier / other-ranges-specifier
+
+ acceptable-ranges = ( *( "," OWS ) range-unit *( OWS "," [ OWS
+ range-unit ] ) ) / "none"
+
+ byte-content-range = bytes-unit SP ( byte-range-resp /
+ unsatisfied-range )
+ byte-range = first-byte-pos "-" last-byte-pos
+ byte-range-resp = byte-range "/" ( complete-length / "*" )
+ byte-range-set = *( "," OWS ) ( byte-range-spec /
+ suffix-byte-range-spec ) *( OWS "," [ OWS ( byte-range-spec /
+ suffix-byte-range-spec ) ] )
+ byte-range-spec = first-byte-pos "-" [ last-byte-pos ]
+ byte-ranges-specifier = bytes-unit "=" byte-range-set
+ bytes-unit = "bytes"
+
+ complete-length = 1*DIGIT
+
+ entity-tag = <entity-tag, see [RFC7232], Section 2.3>
+
+ first-byte-pos = 1*DIGIT
+
+ last-byte-pos = 1*DIGIT
+
+ other-content-range = other-range-unit SP other-range-resp
+ other-range-resp = *CHAR
+ other-range-set = 1*VCHAR
+ other-range-unit = token
+ other-ranges-specifier = other-range-unit "=" other-range-set
+
+ range-unit = bytes-unit / other-range-unit
+
+ suffix-byte-range-spec = "-" suffix-length
+
+
+
+Fielding, et al. Standards Track [Page 23]
+
+RFC 7233 HTTP/1.1 Range Requests June 2014
+
+
+ suffix-length = 1*DIGIT
+
+ token = <token, see [RFC7230], Section 3.2.6>
+
+ unsatisfied-range = "*/" complete-length
+
+Index
+
+ 2
+ 206 Partial Content (status code) 10
+
+ 4
+ 416 Range Not Satisfiable (status code) 15
+
+ A
+ Accept-Ranges header field 7
+
+ C
+ Content-Range header field 12
+
+ G
+ Grammar
+ Accept-Ranges 7
+ acceptable-ranges 7
+ byte-content-range 12
+ byte-range 12
+ byte-range-resp 12
+ byte-range-set 5
+ byte-range-spec 5
+ byte-ranges-specifier 5
+ bytes-unit 5
+ complete-length 12
+ Content-Range 12
+ first-byte-pos 5
+ If-Range 9
+ last-byte-pos 5
+ other-content-range 12
+ other-range-resp 12
+ other-range-unit 5, 7
+ Range 8
+ range-unit 5
+ ranges-specifier 5
+ suffix-byte-range-spec 6
+ suffix-length 6
+ unsatisfied-range 12
+
+
+
+
+
+
+Fielding, et al. Standards Track [Page 24]
+
+RFC 7233 HTTP/1.1 Range Requests June 2014
+
+
+ I
+ If-Range header field 9
+
+ M
+ Media Type
+ multipart/byteranges 18, 21
+ multipart/x-byteranges 19
+ multipart/byteranges Media Type 18, 21
+ multipart/x-byteranges Media Type 21
+
+ R
+ Range header field 8
+
+Authors' Addresses
+
+ Roy T. Fielding (editor)
+ Adobe Systems Incorporated
+ 345 Park Ave
+ San Jose, CA 95110
+ USA
+
+ EMail: fielding@gbiv.com
+ URI: http://roy.gbiv.com/
+
+
+ Yves Lafon (editor)
+ World Wide Web Consortium
+ W3C / ERCIM
+ 2004, rte des Lucioles
+ Sophia-Antipolis, AM 06902
+ France
+
+ EMail: ylafon@w3.org
+ URI: http://www.raubacapeu.net/people/yves/
+
+
+ Julian F. Reschke (editor)
+ greenbytes GmbH
+ Hafenweg 16
+ Muenster, NW 48155
+ Germany
+
+ EMail: julian.reschke@greenbytes.de
+ URI: http://greenbytes.de/tech/webdav/
+
+
+
+
+
+
+
+Fielding, et al. Standards Track [Page 25]
+
7apu2bq3rhoylwmucxizk54afw5jyda7pho4j5zdcqpwkufke7zdzwad.onion