QUIC Stream Resets with Partial Delivery
draft-ietf-quic-reliable-stream-reset-06

QUIC                                                          M. Seemann
Internet-Draft                                                          
Intended status: Standards Track                         奥一穂 (K. Oku)
Expires: 1 September 2024                                         Fastly
                                                        29 February 2024

                QUIC Stream Resets with Partial Delivery
                draft-ietf-quic-reliable-stream-reset-06

Abstract

   QUIC defines a RESET_STREAM frame to abort sending on a stream.  When
   a sender resets a stream, it also stops retransmitting STREAM frames
   for this stream in the event of packet loss.  On the receiving side,
   there is no guarantee that any data sent on that stream is delivered.

   This document defines a new QUIC frame, the RESET_STREAM_AT frame,
   that allows resetting a stream, while guaranteeing delivery of stream
   data up to a certain byte offset.

About This Document

   This note is to be removed before publishing as an RFC.

   The latest revision of this draft can be found at
   https://quicwg.github.io/reliable-stream-reset/draft-ietf-quic-
   reliable-stream-reset.html.  Status information for this document may
   be found at https://datatracker.ietf.org/doc/draft-ietf-quic-
   reliable-stream-reset/.

   Discussion of this document takes place on the QUIC Working Group
   mailing list (mailto:quic@ietf.org), which is archived at
   https://mailarchive.ietf.org/arch/browse/quic/.  Subscribe at
   https://www.ietf.org/mailman/listinfo/quic/.

   Source for this draft and an issue tracker can be found at
   https://github.com/quicwg/reliable-stream-reset.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions and Definitions . . . . . . . . . . . . . . . . .   3
   3.  Negotiating Extension Use . . . . . . . . . . . . . . . . . .   3
   4.  RESET_STREAM_AT Frame . . . . . . . . . . . . . . . . . . . .   4
   5.  Resetting Streams . . . . . . . . . . . . . . . . . . . . . .   5
     5.1.  Multiple RESET_STREAM_AT / RESET_STREAM frames  . . . . .   5
     5.2.  Stream States . . . . . . . . . . . . . . . . . . . . . .   6
   6.  Implementation Guidance . . . . . . . . . . . . . . . . . . .   7
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
     8.1.  QUIC Transport Parameter  . . . . . . . . . . . . . . . .   7
     8.2.  QUIC Frame Types  . . . . . . . . . . . . . . . . . . . .   8
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   8
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   QUIC version 1 ([RFC9000]) allows streams to be reset.  When a stream
   is reset, the sender doesn't retransmit stream data for the
   respective stream.  On the receiving side, the QUIC stack is free to
   surface the stream reset to the application immediately, without
   providing any stream data it has received for that stream.

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   Some applications running on top of QUIC use bytes at the beginning
   of the stream to communicate critical information related to that
   stream.  For example, WebTransport ([WEBTRANSPORT]) uses a variable-
   length encoded integer to associate a stream with a particular
   WebTransport session.

   Since QUIC does not provide guaranteed delivery of steam data for
   reset streams, it is possible that a receiver is unable to read
   critical information.  In the example above, a reset stream can cause
   the receiver to fail to associate incoming streams with their
   respective subcomponent of the application.  Therefore, it is
   desirable that the receiver can rely on the delivery of critical
   information to applications, even if the QUIC stream is reset before
   data is read by the application.

   Another use case is relaying data from an external data source.  When
   a relay is sending data being read from an external source and
   encounters an error, it might want to use a stream reset to signal
   that error, while at the same time guaranteeing that all data
   received from the source is delivered to the peer.

   This document extends QUIC with a variant of stream resets that
   reliably delivers the beginning of a stream up to a sender-specified
   offset, communicated using the RESET_STREAM_AT frame.  It can be
   considered a form of range-based partial reliability.  As a variant
   of reset, application protocols continue to treat this stream
   function as an abrupt termination; see Section 2.4 of [RFC9000].

2.  Conventions and Definitions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

3.  Negotiating Extension Use

   Endpoints advertise their support of the extension described in this
   document by sending the reliable_stream_reset (0x17f7586d2cb571)
   transport parameter (Section 7.4 of [RFC9000]) with an empty value.
   An implementation that understands this transport parameter MUST
   treat the receipt of a non-empty value as a connection error of type
   TRANSPORT_PARAMETER_ERROR.

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   When using 0-RTT, both endpoints MUST remember the value of this
   transport parameter.  This allows use of this extension in 0-RTT
   packets.  When the server accepts 0-RTT data, the server MUST NOT
   disable this extension on the resumed connection.

4.  RESET_STREAM_AT Frame

   Conceptually, the RESET_STREAM_AT frame is a RESET_STREAM frame with
   an added Reliable Size field.

   RESET_STREAM_AT Frame {
     Type (i) = 0x24,
     Stream ID (i),
     Application Protocol Error Code (i),
     Final Size (i),
     Reliable Size (i),
   }

                   Figure 1: RESET_STREAM_AT Frame Format

   The RESET_STREAM_AT frame contains the following fields:

   Stream ID:  A variable-length integer encoding of the stream ID of
      the stream being terminated.

   Application Protocol Error Code:  A variable-length integer
      containing the application protocol error code (Section 20.2 of
      [RFC9000]) that indicates why the stream is being closed.

   Final Size:  A variable-length integer indicating the final size of
      the stream by the sender, in units of bytes; see Section 4.5 of
      [RFC9000].

   Reliable Size:  A variable-length integer indicating the amount of
      data that needs to be delivered to the application even though the
      stream is reset.

   If the Reliable Size is larger than the Final Size, the receiver MUST
   close the connection with a connection error of type
   FRAME_ENCODING_ERROR.

   RESET_STREAM_AT frames are ack-eliciting, and MUST only be sent in
   the application data packet number space.  When lost, they MUST be
   retransmitted, unless the stream state has transitioned to "Data
   Recvd" or "Reset Recvd" due to transmission and acknowledgement of
   other frames (see Section 5.1).

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5.  Resetting Streams

   A sender that wants to reset a stream but also deliver some bytes to
   the receiver sends a RESET_STREAM_AT frame with the Reliable Size
   field specifying the amount of data to be delivered.

   When using a RESET_STREAM_AT frame, the initiator MUST guarantee
   reliable delivery of stream data of at least Reliable Size bytes.  If
   STREAM frames containing data up to that byte offset are lost, the
   initiator MUST retransmit this data, as described in Section 13.3 of
   [RFC9000].  Data sent beyond that byte offset SHOULD NOT be
   retransmitted.

   As described in Section 3.2 of [RFC9000], a stream reset signal might
   be suppressed or withheld, and the same applies to a stream reset
   signal carried in a RESET_STREAM_AT frame.  Similarly, the Reliable
   Size of the RESET_STREAM_AT frame does not prevent a QUIC stack from
   delivering data beyond the specified offset to the receiving
   application.

   Note that a Reliable Size value of zero is valid.  A RESET_STREAM_AT
   frame with this value is logically equivalent to a RESET_STREAM frame
   (Section 3.2 of [RFC9000]).  When resetting a stream without the
   intent to deliver any data to the receiver, the sender MAY use either
   RESET_STREAM or RESET_STREAM_AT with a Reliable Size of zero.

5.1.  Multiple RESET_STREAM_AT / RESET_STREAM frames

   The initiator MAY send multiple RESET_STREAM_AT frames for the same
   stream in order to reduce the Reliable Size.  It MAY also send a
   RESET_STREAM frame, which is equivalent to sending a RESET_STREAM_AT
   frame with a Reliable Size of 0.  When reducing the Reliable Size,
   the sender MUST retransmit the RESET_STREAM_AT frame carrying the
   smallest Reliable Size as well as stream data up to that size, until
   all acknowledgements for the stream data and the RESET_STREAM_AT
   frame are received.

   When sending multiple RESET_STREAM_AT or RESET_STREAM frames for the
   same stream, the initiator MUST NOT increase the Reliable Size.

   When receiving a RESET_STREAM_AT frame with a lower Reliable Size,
   the receiver only needs to provide data up the lower Reliable Size to
   the application.  It MUST NOT expect the sender to deliver any data
   beyond that byte offset.

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   Reordering of packets might lead to a RESET_STREAM_AT frame with a
   higher Reliable Size being received after a RESET_STREAM_AT frame
   with a lower Reliable Size.  The receiver MUST ignore any
   RESET_STREAM_AT frame that increases the Reliable Size.

   When sending another RESET_STREAM_AT, RESET_STREAM or STREAM frame
   carrying a FIN bit for the same stream, the initiator MUST NOT change
   the Application Error Code or the Final Size.  If the receiver
   detects a change in those fields, it MUST close the connection with a
   connection error of type STREAM_STATE_ERROR.

   While multiple RESET_STREAM_AT frames can reduce Reliable Size, some
   applications might need to ensure that a minimum amount of data is
   always delivered on a stream.  Application protocols can establish
   rules for streams that ensure that Reliable Size is not reduced below
   a certain threshold if that is necessary to ensure correct operation
   of the protocol.

5.2.  Stream States

   In terms of stream state transitions (Section 3 of [RFC9000]), the
   effect of a RESET_STREAM_AT frame is equivalent to that of the FIN
   bit.  Both the RESET_STREAM_AT frame and the FIN bit on a STREAM
   frame serve the same role: signaling the amount of data to be
   delivered.

   On the sending side, when the first RESET_STREAM_AT frame is sent,
   the sending part of the stream enters the "Data Sent" state.  Once
   the RESET_STREAM_AT frame carrying the smallest Reliable Size and all
   stream data up to that byte offset have been acknowledged, the
   sending part of the stream enters the "Data Recvd" state.  The
   transition from "Data Sent" to "Data Recvd" happens immediately if
   the application resets a stream and all bytes up to the specified
   Reliable Size have already been sent and acknowledged.  Conversely,
   the transition might take multiple network roundtrips or require
   additional flow control credit issued by the receiver.

   On the receiving side, when a RESET_STREAM_AT frame is received, the
   receiving part of the stream enters the "Size Known" state.  Once all
   data up to the smallest Reliable Size have been received, it enters
   the "Data Recvd" state.  Similarly to the sending side, transition
   from "Size Known" to "Data Recvd" might happen immediately or involve
   issuance of additional flow control credit.

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6.  Implementation Guidance

   In terms of transport machinery, the RESET_STREAM_AT frame is more
   akin to the FIN bit than to the RESET_STREAM frame (see Section 5.2).
   By sending a RESET_STREAM_AT frame, the sender commits to delivering
   all bytes up to the Reliable Size.

   To the endpoints, the main differences from closing a stream by using
   the FIN bit are:

   *  the offset up to which the sender commits to sending might be
      smaller than Final Size,

   *  this offset might get reduced by subsequent RESET_STREAM_AT
      frames, and

   *  the closure is accompanied by an error code.

7.  Security Considerations

   As the RESET_STREAM_AT frame is an extension to the stream machinery
   defined in QUIC version 1, the security considerations of [RFC9000]
   apply accordingly.  Specifically, given that RESET_STREAM_AT frames
   indicate the offset up to which data is reliably transmitted,
   endpoints SHOULD remain vigilant against resource commitment and
   exhaustion attacks even after sending or receiving RESET_STREAM_AT
   frames, until the stream reaches the terminal state.

8.  IANA Considerations

8.1.  QUIC Transport Parameter

   This document registers the reliable_stream_reset transport parameter
   in the "QUIC Transport Parameters" registry established in
   Section 22.3 of [RFC9000].  The following fields are registered:

   Value:  0x17f7586d2cb571

   Parameter Name:  reliable_stream_reset

   Status:  Provisional (note that, prior to publication, the value will
      be replaced by a new value lower than 64)

   Specification:  This document

   Change Controller:  IETF (iesg@ietf.org)

   Contact:  QUIC Working Group (quic@ietf.org)

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8.2.  QUIC Frame Types

   This document registers one new value in the "QUIC Frame Types"
   registry established in Section 22.4 of [RFC9000].  The following
   fields are registered:

   Value:  0x24

   Frame Type Name:  RESET_STREAM_AT

   Status:  Provisional (will become Permanent once this document is
      approved)

   Specification:  This document

   Change Controller:  IETF (iesg@ietf.org)

   Contact:  QUIC Working Group (quic@ietf.org)

9.  References

9.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/rfc/rfc2119>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.

   [RFC9000]  Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based
              Multiplexed and Secure Transport", RFC 9000,
              DOI 10.17487/RFC9000, May 2021,
              <https://www.rfc-editor.org/rfc/rfc9000>.

9.2.  Informative References

   [WEBTRANSPORT]
              Frindell, A., Kinnear, E., and V. Vasiliev, "WebTransport
              over HTTP/3", Work in Progress, Internet-Draft, draft-
              ietf-webtrans-http3-08, 23 October 2023,
              <https://datatracker.ietf.org/doc/html/draft-ietf-
              webtrans-http3-08>.

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Acknowledgments

   TODO acknowledge.

Authors' Addresses

   Marten Seemann
   Email: martenseemann@gmail.com

   Kazuho Oku
   Fastly
   Email: kazuhooku@gmail.com

   Additional contact information:

      奥一穂
      Fastly

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