draft-ietf-quic-transport-02.txt   draft-ietf-quic-transport-03.txt 
QUIC J. Iyengar, Ed. QUIC J. Iyengar, Ed.
Internet-Draft Google Internet-Draft Google
Intended status: Standards Track M. Thomson, Ed. Intended status: Standards Track M. Thomson, Ed.
Expires: September 14, 2017 Mozilla Expires: November 22, 2017 Mozilla
March 13, 2017 May 21, 2017
QUIC: A UDP-Based Multiplexed and Secure Transport QUIC: A UDP-Based Multiplexed and Secure Transport
draft-ietf-quic-transport-02 draft-ietf-quic-transport-03
Abstract Abstract
This document defines the core of the QUIC transport protocol. This This document defines the core of the QUIC transport protocol. This
document describes connection establishment, packet format, document describes connection establishment, packet format,
multiplexing and reliability. Accompanying documents describe the multiplexing and reliability. Accompanying documents describe the
cryptographic handshake and loss detection. cryptographic handshake and loss detection.
Note to Readers Note to Readers
skipping to change at page 1, line 44 skipping to change at page 1, line 44
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 September 14, 2017. This Internet-Draft will expire on November 22, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 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
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Conventions and Definitions . . . . . . . . . . . . . . . . . 4 2. Conventions and Definitions . . . . . . . . . . . . . . . . . 5
2.1. Notational Conventions . . . . . . . . . . . . . . . . . 5 2.1. Notational Conventions . . . . . . . . . . . . . . . . . 5
3. A QUIC Overview . . . . . . . . . . . . . . . . . . . . . . . 5 3. A QUIC Overview . . . . . . . . . . . . . . . . . . . . . . . 6
3.1. Low-Latency Connection Establishment . . . . . . . . . . 6 3.1. Low-Latency Connection Establishment . . . . . . . . . . 6
3.2. Stream Multiplexing . . . . . . . . . . . . . . . . . . . 6 3.2. Stream Multiplexing . . . . . . . . . . . . . . . . . . . 6
3.3. Rich Signaling for Congestion Control and Loss Recovery . 6 3.3. Rich Signaling for Congestion Control and Loss Recovery . 7
3.4. Stream and Connection Flow Control . . . . . . . . . . . 6 3.4. Stream and Connection Flow Control . . . . . . . . . . . 7
3.5. Authenticated and Encrypted Header and Payload . . . . . 7 3.5. Authenticated and Encrypted Header and Payload . . . . . 7
3.6. Connection Migration and Resilience to NAT Rebinding . . 7 3.6. Connection Migration and Resilience to NAT Rebinding . . 8
3.7. Version Negotiation . . . . . . . . . . . . . . . . . . . 8 3.7. Version Negotiation . . . . . . . . . . . . . . . . . . . 8
4. Versions . . . . . . . . . . . . . . . . . . . . . . . . . . 8 4. Versions . . . . . . . . . . . . . . . . . . . . . . . . . . 8
5. Packet Types and Formats . . . . . . . . . . . . . . . . . . 8 5. Packet Types and Formats . . . . . . . . . . . . . . . . . . 9
5.1. Long Header . . . . . . . . . . . . . . . . . . . . . . . 9 5.1. Long Header . . . . . . . . . . . . . . . . . . . . . . . 9
5.2. Short Header . . . . . . . . . . . . . . . . . . . . . . 11 5.2. Short Header . . . . . . . . . . . . . . . . . . . . . . 11
5.3. Version Negotiation Packet . . . . . . . . . . . . . . . 12 5.3. Version Negotiation Packet . . . . . . . . . . . . . . . 13
5.4. Cleartext Packets . . . . . . . . . . . . . . . . . . . . 13 5.4. Cleartext Packets . . . . . . . . . . . . . . . . . . . . 14
5.5. Encrypted Packets . . . . . . . . . . . . . . . . . . . . 14 5.4.1. Client Initial Packet . . . . . . . . . . . . . . . . 14
5.6. Public Reset Packet . . . . . . . . . . . . . . . . . . . 15 5.4.2. Server Stateless Retry Packet . . . . . . . . . . . . 15
5.6.1. Public Reset Proof . . . . . . . . . . . . . . . . . 15 5.4.3. Server Cleartext Packet . . . . . . . . . . . . . . . 15
5.7. Connection ID . . . . . . . . . . . . . . . . . . . . . . 16 5.4.4. Client Cleartext Packet . . . . . . . . . . . . . . . 16
5.8. Packet Numbers . . . . . . . . . . . . . . . . . . . . . 16 5.5. Protected Packets . . . . . . . . . . . . . . . . . . . . 16
5.8.1. Initial Packet Number . . . . . . . . . . . . . . . . 17 5.6. Public Reset Packet . . . . . . . . . . . . . . . . . . . 17
5.9. Handling Packets from Different Versions . . . . . . . . 17 5.6.1. Public Reset Proof . . . . . . . . . . . . . . . . . 18
6. Frames and Frame Types . . . . . . . . . . . . . . . . . . . 18 5.7. Connection ID . . . . . . . . . . . . . . . . . . . . . . 18
7. Life of a Connection . . . . . . . . . . . . . . . . . . . . 19 5.8. Packet Numbers . . . . . . . . . . . . . . . . . . . . . 18
7.1. Version Negotiation . . . . . . . . . . . . . . . . . . . 19 5.8.1. Initial Packet Number . . . . . . . . . . . . . . . . 19
7.1.1. Using Reserved Versions . . . . . . . . . . . . . . . 20 5.9. Handling Packets from Different Versions . . . . . . . . 20
7.2. Cryptographic and Transport Handshake . . . . . . . . . . 21 6. Frames and Frame Types . . . . . . . . . . . . . . . . . . . 20
7.3. Transport Parameters . . . . . . . . . . . . . . . . . . 22 7. Life of a Connection . . . . . . . . . . . . . . . . . . . . 22
7.3.1. Transport Parameter Definitions . . . . . . . . . . . 24 7.1. Version Negotiation . . . . . . . . . . . . . . . . . . . 23
7.3.2. Values of Transport Parameters for 0-RTT . . . . . . 24 7.1.1. Using Reserved Versions . . . . . . . . . . . . . . . 24
7.3.3. New Transport Parameters . . . . . . . . . . . . . . 25 7.2. Cryptographic and Transport Handshake . . . . . . . . . . 24
7.3.4. Version Negotiation Validation . . . . . . . . . . . 25 7.3. Transport Parameters . . . . . . . . . . . . . . . . . . 25
7.4. Proof of Source Address Ownership . . . . . . . . . . . . 27 7.3.1. Transport Parameter Definitions . . . . . . . . . . . 27
7.4.1. Client Address Validation Procedure . . . . . . . . . 27 7.3.2. Values of Transport Parameters for 0-RTT . . . . . . 27
7.4.2. Address Validation on Session Resumption . . . . . . 28 7.3.3. New Transport Parameters . . . . . . . . . . . . . . 28
7.4.3. Address Validation Token Integrity . . . . . . . . . 29 7.3.4. Version Negotiation Validation . . . . . . . . . . . 28
7.5. Connection Migration . . . . . . . . . . . . . . . . . . 29 7.4. Stateless Retries . . . . . . . . . . . . . . . . . . . . 29
7.6. Connection Termination . . . . . . . . . . . . . . . . . 30 7.5. Proof of Source Address Ownership . . . . . . . . . . . . 30
8. Frame Types and Formats . . . . . . . . . . . . . . . . . . . 31 7.5.1. Client Address Validation Procedure . . . . . . . . . 31
8.1. STREAM Frame . . . . . . . . . . . . . . . . . . . . . . 31 7.5.2. Address Validation on Session Resumption . . . . . . 31
8.2. ACK Frame . . . . . . . . . . . . . . . . . . . . . . . . 32 7.5.3. Address Validation Token Integrity . . . . . . . . . 32
8.2.1. ACK Block Section . . . . . . . . . . . . . . . . . . 34 7.6. Connection Migration . . . . . . . . . . . . . . . . . . 32
8.2.2. Timestamp Section . . . . . . . . . . . . . . . . . . 35 7.6.1. Privacy Implications of Connection Migration . . . . 33
8.2.3. ACK Frames and Packet Protection . . . . . . . . . . 37 7.6.2. Address Validation for Migrated Connections . . . . . 34
8.3. WINDOW_UPDATE Frame . . . . . . . . . . . . . . . . . . . 38 7.7. Connection Termination . . . . . . . . . . . . . . . . . 34
8.4. BLOCKED Frame . . . . . . . . . . . . . . . . . . . . . . 39 8. Frame Types and Formats . . . . . . . . . . . . . . . . . . . 35
8.5. RST_STREAM Frame . . . . . . . . . . . . . . . . . . . . 39 8.1. STREAM Frame . . . . . . . . . . . . . . . . . . . . . . 35
8.6. PADDING Frame . . . . . . . . . . . . . . . . . . . . . . 40 8.2. ACK Frame . . . . . . . . . . . . . . . . . . . . . . . . 37
8.7. PING frame . . . . . . . . . . . . . . . . . . . . . . . 40 8.2.1. ACK Block Section . . . . . . . . . . . . . . . . . . 39
8.8. CONNECTION_CLOSE frame . . . . . . . . . . . . . . . . . 40 8.2.2. Timestamp Section . . . . . . . . . . . . . . . . . . 40
8.9. GOAWAY Frame . . . . . . . . . . . . . . . . . . . . . . 41 8.2.3. ACK Frames and Packet Protection . . . . . . . . . . 41
9. Packetization and Reliability . . . . . . . . . . . . . . . . 42 8.3. MAX_DATA Frame . . . . . . . . . . . . . . . . . . . . . 42
9.1. Special Considerations for PMTU Discovery . . . . . . . . 44 8.4. MAX_STREAM_DATA Frame . . . . . . . . . . . . . . . . . . 43
10. Streams: QUIC's Data Structuring Abstraction . . . . . . . . 45 8.5. MAX_STREAM_ID Frame . . . . . . . . . . . . . . . . . . . 44
10.1. Life of a Stream . . . . . . . . . . . . . . . . . . . . 45 8.6. BLOCKED Frame . . . . . . . . . . . . . . . . . . . . . . 44
10.1.1. idle . . . . . . . . . . . . . . . . . . . . . . . . 47 8.7. STREAM_BLOCKED Frame . . . . . . . . . . . . . . . . . . 44
10.1.2. open . . . . . . . . . . . . . . . . . . . . . . . . 47 8.8. STREAM_ID_NEEDED Frame . . . . . . . . . . . . . . . . . 45
10.1.3. half-closed (local) . . . . . . . . . . . . . . . . 48 8.9. RST_STREAM Frame . . . . . . . . . . . . . . . . . . . . 45
10.1.4. half-closed (remote) . . . . . . . . . . . . . . . . 48 8.10. PADDING Frame . . . . . . . . . . . . . . . . . . . . . . 46
10.1.5. closed . . . . . . . . . . . . . . . . . . . . . . . 48 8.11. PING frame . . . . . . . . . . . . . . . . . . . . . . . 46
10.2. Stream Identifiers . . . . . . . . . . . . . . . . . . . 50 8.12. NEW_CONNECTION_ID Frame . . . . . . . . . . . . . . . . . 46
10.3. Stream Concurrency . . . . . . . . . . . . . . . . . . . 50 8.13. CONNECTION_CLOSE frame . . . . . . . . . . . . . . . . . 47
10.4. Sending and Receiving Data . . . . . . . . . . . . . . . 51 8.14. GOAWAY Frame . . . . . . . . . . . . . . . . . . . . . . 48
10.5. Stream Prioritization . . . . . . . . . . . . . . . . . 51 9. Packetization and Reliability . . . . . . . . . . . . . . . . 49
11. Flow Control . . . . . . . . . . . . . . . . . . . . . . . . 52 9.1. Special Considerations for PMTU Discovery . . . . . . . . 51
11.1. Edge Cases and Other Considerations . . . . . . . . . . 54 10. Streams: QUIC's Data Structuring Abstraction . . . . . . . . 51
11.1.1. Mid-stream RST_STREAM . . . . . . . . . . . . . . . 54 10.1. Stream Identifiers . . . . . . . . . . . . . . . . . . . 52
11.1.2. Response to a RST_STREAM . . . . . . . . . . . . . . 54 10.2. Life of a Stream . . . . . . . . . . . . . . . . . . . . 52
11.1.3. Offset Increment . . . . . . . . . . . . . . . . . . 54 10.2.1. idle . . . . . . . . . . . . . . . . . . . . . . . . 54
11.1.4. BLOCKED frames . . . . . . . . . . . . . . . . . . . 55 10.2.2. open . . . . . . . . . . . . . . . . . . . . . . . . 54
12. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 55 10.2.3. half-closed (local) . . . . . . . . . . . . . . . . 55
12.1. Connection Errors . . . . . . . . . . . . . . . . . . . 55 10.2.4. half-closed (remote) . . . . . . . . . . . . . . . . 55
12.2. Stream Errors . . . . . . . . . . . . . . . . . . . . . 56 10.2.5. closed . . . . . . . . . . . . . . . . . . . . . . . 56
12.3. Error Codes . . . . . . . . . . . . . . . . . . . . . . 56 10.3. Stream Concurrency . . . . . . . . . . . . . . . . . . . 56
13. Security and Privacy Considerations . . . . . . . . . . . . . 60 10.4. Sending and Receiving Data . . . . . . . . . . . . . . . 57
13.1. Spoofed ACK Attack . . . . . . . . . . . . . . . . . . . 60 10.5. Stream Prioritization . . . . . . . . . . . . . . . . . 57
14. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 61 11. Flow Control . . . . . . . . . . . . . . . . . . . . . . . . 58
14.1. QUIC Transport Parameter Registry . . . . . . . . . . . 61 11.1. Edge Cases and Other Considerations . . . . . . . . . . 59
15. References . . . . . . . . . . . . . . . . . . . . . . . . . 62 11.1.1. Response to a RST_STREAM . . . . . . . . . . . . . . 60
15.1. Normative References . . . . . . . . . . . . . . . . . . 62 11.1.2. Data Limit Increments . . . . . . . . . . . . . . . 60
15.2. Informative References . . . . . . . . . . . . . . . . . 63 11.2. Stream Limit Increment . . . . . . . . . . . . . . . . . 61
15.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 64 11.2.1. Blocking on Flow Control . . . . . . . . . . . . . . 61
Appendix A. Contributors . . . . . . . . . . . . . . . . . . . . 64 11.3. Stream Final Offset . . . . . . . . . . . . . . . . . . 61
Appendix B. Acknowledgments . . . . . . . . . . . . . . . . . . 64 12. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 62
Appendix C. Change Log . . . . . . . . . . . . . . . . . . . . . 64 12.1. Connection Errors . . . . . . . . . . . . . . . . . . . 62
C.1. Since draft-ietf-quic-transport-01: . . . . . . . . . . . 64 12.2. Stream Errors . . . . . . . . . . . . . . . . . . . . . 63
C.2. Since draft-ietf-quic-transport-00: . . . . . . . . . . . 66 12.3. Error Codes . . . . . . . . . . . . . . . . . . . . . . 63
C.3. Since draft-hamilton-quic-transport-protocol-01: . . . . 67 13. Security and Privacy Considerations . . . . . . . . . . . . . 67
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 67 13.1. Spoofed ACK Attack . . . . . . . . . . . . . . . . . . . 67
13.2. Slowloris Attacks . . . . . . . . . . . . . . . . . . . 68
13.3. Stream Fragmentation and Reassembly Attacks . . . . . . 68
13.4. Stream Commitment Attack . . . . . . . . . . . . . . . . 68
14. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 69
14.1. QUIC Transport Parameter Registry . . . . . . . . . . . 69
15. References . . . . . . . . . . . . . . . . . . . . . . . . . 70
15.1. Normative References . . . . . . . . . . . . . . . . . . 70
15.2. Informative References . . . . . . . . . . . . . . . . . 71
15.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Appendix A. Contributors . . . . . . . . . . . . . . . . . . . . 72
Appendix B. Acknowledgments . . . . . . . . . . . . . . . . . . 72
Appendix C. Change Log . . . . . . . . . . . . . . . . . . . . . 72
C.1. Since draft-ietf-quic-transport-02 . . . . . . . . . . . 72
C.2. Since draft-ietf-quic-transport-01 . . . . . . . . . . . 73
C.3. Since draft-ietf-quic-transport-00 . . . . . . . . . . . 75
C.4. Since draft-hamilton-quic-transport-protocol-01 . . . . . 76
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 76
1. Introduction 1. Introduction
QUIC is a multiplexed and secure transport protocol that runs on top QUIC is a multiplexed and secure transport protocol that runs on top
of UDP. QUIC aims to provide a flexible set of features that allow of UDP. QUIC aims to provide a flexible set of features that allow
it to be a general-purpose transport for multiple applications. it to be a general-purpose transport for multiple applications.
QUIC implements techniques learned from experience with TCP, SCTP and QUIC implements techniques learned from experience with TCP, SCTP and
other transport protocols. Using UDP as the substrate, QUIC seeks to other transport protocols. Using UDP as the substrate, QUIC seeks to
be compatible with legacy clients and middleboxes. QUIC be compatible with legacy clients and middleboxes. QUIC
skipping to change at page 6, line 12 skipping to change at page 6, line 31
o Version negotiation o Version negotiation
3.1. Low-Latency Connection Establishment 3.1. Low-Latency Connection Establishment
QUIC relies on a combined cryptographic and transport handshake for QUIC relies on a combined cryptographic and transport handshake for
setting up a secure transport connection. QUIC connections are setting up a secure transport connection. QUIC connections are
expected to commonly use 0-RTT handshakes, meaning that for most QUIC expected to commonly use 0-RTT handshakes, meaning that for most QUIC
connections, data can be sent immediately following the client connections, data can be sent immediately following the client
handshake packet, without waiting for a reply from the server. QUIC handshake packet, without waiting for a reply from the server. QUIC
provides a dedicated stream (Stream ID 1) to be used for performing provides a dedicated stream (Stream ID 0) to be used for performing
the cryptographic handshake and QUIC options negotiation. The format the cryptographic handshake and QUIC options negotiation. The format
of the QUIC options and parameters used during negotiation are of the QUIC options and parameters used during negotiation are
described in this document, but the handshake protocol that runs on described in this document, but the handshake protocol that runs on
Stream ID 1 is described in the accompanying cryptographic handshake Stream ID 0 is described in the accompanying cryptographic handshake
draft [QUIC-TLS]. draft [QUIC-TLS].
3.2. Stream Multiplexing 3.2. Stream Multiplexing
When application messages are transported over TCP, independent When application messages are transported over TCP, independent
application messages can suffer from head-of-line blocking. When an application messages can suffer from head-of-line blocking. When an
application multiplexes many streams atop TCP's single-bytestream application multiplexes many streams atop TCP's single-bytestream
abstraction, a loss of a TCP segment results in blocking of all abstraction, a loss of a TCP segment results in blocking of all
subsequent segments until a retransmission arrives, irrespective of subsequent segments until a retransmission arrives, irrespective of
the application streams that are encapsulated in subsequent segments. the application streams that are encapsulated in subsequent segments.
skipping to change at page 6, line 49 skipping to change at page 7, line 23
ambiguity problem. QUIC acknowledgments also explicitly encode the ambiguity problem. QUIC acknowledgments also explicitly encode the
delay between the receipt of a packet and its acknowledgment being delay between the receipt of a packet and its acknowledgment being
sent, and together with the monotonically-increasing packet numbers, sent, and together with the monotonically-increasing packet numbers,
this allows for precise network roundtrip-time (RTT) calculation. this allows for precise network roundtrip-time (RTT) calculation.
QUIC's ACK frames support up to 256 ACK blocks, so QUIC is more QUIC's ACK frames support up to 256 ACK blocks, so QUIC is more
resilient to reordering than TCP with SACK support, as well as able resilient to reordering than TCP with SACK support, as well as able
to keep more bytes on the wire when there is reordering or loss. to keep more bytes on the wire when there is reordering or loss.
3.4. Stream and Connection Flow Control 3.4. Stream and Connection Flow Control
QUIC implements stream- and connection-level flow control, closely QUIC implements stream- and connection-level flow control. At a high
following HTTP/2's flow control mechanisms. At a high level, a QUIC level, a QUIC receiver advertises the maximum amount of data that it
receiver advertises the absolute byte offset within each stream up to is willing to receive on each stream. As data is sent, received, and
which the receiver is willing to receive data. As data is sent, delivered on a particular stream, the receiver sends MAX_STREAM_DATA
received, and delivered on a particular stream, the receiver sends frames that increase the advertised limit for that stream, allowing
WINDOW_UPDATE frames that increase the advertised offset limit for the peer to send more data on that stream.
that stream, allowing the peer to send more data on that stream. In
addition to this stream-level flow control, QUIC implements In addition to this stream-level flow control, QUIC implements
connection-level flow control to limit the aggregate buffer that a connection-level flow control to limit the aggregate buffer that a
QUIC receiver is willing to allocate to all streams on a connection. QUIC receiver is willing to allocate to all streams on a connection.
Connection-level flow control works in the same way as stream-level Connection-level flow control works in the same way as stream-level
flow control, but the bytes delivered and highest received offset are flow control, but the bytes delivered and the limits are aggregated
all aggregates across all streams. across all streams.
3.5. Authenticated and Encrypted Header and Payload 3.5. Authenticated and Encrypted Header and Payload
TCP headers appear in plaintext on the wire and are not TCP headers appear in plaintext on the wire and are not
authenticated, causing a plethora of injection and header authenticated, causing a plethora of injection and header
manipulation issues for TCP, such as receive-window manipulation and manipulation issues for TCP, such as receive-window manipulation and
sequence-number overwriting. While some of these are mechanisms used sequence-number overwriting. While some of these are mechanisms used
by middleboxes to improve TCP performance, others are active attacks. by middleboxes to improve TCP performance, others are active attacks.
Even "performance-enhancing" middleboxes that routinely interpose on Even "performance-enhancing" middleboxes that routinely interpose on
the transport state machine end up limiting the evolvability of the the transport state machine end up limiting the evolvability of the
skipping to change at page 8, line 19 skipping to change at page 8, line 39
described in Section 7.1. described in Section 7.1.
4. Versions 4. Versions
QUIC versions are identified using a 32-bit value. QUIC versions are identified using a 32-bit value.
The version 0x00000000 is reserved to represent an invalid version. The version 0x00000000 is reserved to represent an invalid version.
This version of the specification is identified by the number This version of the specification is identified by the number
0x00000001. 0x00000001.
Version 0x000000001 of QUIC uses TLS as a cryptographic handshake
protocol, as described in [QUIC-TLS].
Versions with the most significant 16 bits of the version number Versions with the most significant 16 bits of the version number
cleared are reserved for use in future IETF consensus documents. cleared are reserved for use in future IETF consensus documents.
Versions that follow the pattern 0x?a?a?a?a are reserved for use in Versions that follow the pattern 0x?a?a?a?a are reserved for use in
forcing version negotiation to be exercised. That is, any version forcing version negotiation to be exercised. That is, any version
number where the low four bits of all octets is 1010 (in binary). A number where the low four bits of all octets is 1010 (in binary). A
client or server MAY advertise support for any of these reserved client or server MAY advertise support for any of these reserved
versions. versions.
Reserved version numbers will probably never represent a real Reserved version numbers will probably never represent a real
skipping to change at page 10, line 20 skipping to change at page 11, line 7
Version: Octets 13 to 16 contain the selected protocol version. Version: Octets 13 to 16 contain the selected protocol version.
This field indicates which version of QUIC is in use and This field indicates which version of QUIC is in use and
determines how the rest of the protocol fields are interpreted. determines how the rest of the protocol fields are interpreted.
Payload: Octets from 17 onwards (the rest of QUIC packet) are the Payload: Octets from 17 onwards (the rest of QUIC packet) are the
payload of the packet. payload of the packet.
The following packet types are defined: The following packet types are defined:
+------+-------------------------------+-------------+ +------+-------------------------------+---------------+
| Type | Name | Section | | Type | Name | Section |
+------+-------------------------------+-------------+ +------+-------------------------------+---------------+
| 01 | Version Negotiation | Section 5.3 | | 01 | Version Negotiation | Section 5.3 |
| | | | | | | |
| 02 | Client Cleartext | Section 5.4 | | 02 | Client Initial | Section 5.4.1 |
| | | | | | | |
| 03 | Non-Final Server Cleartext | Section 5.4 | | 03 | Server Stateless Retry | Section 5.4.2 |
| | | | | | | |
| 04 | Final Server Cleartext | Section 5.4 | | 04 | Server Cleartext | Section 5.4.3 |
| | | | | | | |
| 05 | 0-RTT Encrypted | Section 5.5 | | 05 | Client Cleartext | Section 5.4.4 |
| | | | | | | |
| 06 | 1-RTT Encrypted (key phase 0) | Section 5.5 | | 06 | 0-RTT Protected | Section 5.5 |
| | | | | | | |
| 07 | 1-RTT Encrypted (key phase 1) | Section 5.5 | | 07 | 1-RTT Protected (key phase 0) | Section 5.5 |
| | | | | | | |
| 08 | Public Reset | Section 5.6 | | 08 | 1-RTT Protected (key phase 1) | Section 5.5 |
+------+-------------------------------+-------------+ | | | |
| 09 | Public Reset | Section 5.6 |
+------+-------------------------------+---------------+
Table 1: Long Header Packet Types Table 1: Long Header Packet Types
The header form, packet type, connection ID, packet number and The header form, packet type, connection ID, packet number and
version fields of a long header packet are version-independent. The version fields of a long header packet are version-independent. The
types of packets defined in Table 1 are version-specific. See types of packets defined in Table 1 are version-specific. See
Section 5.9 for details on how packets from different versions of Section 5.9 for details on how packets from different versions of
QUIC are interpreted. QUIC are interpreted.
(TODO: Should the list of packet types be version-independent?) (TODO: Should the list of packet types be version-independent?)
The interpretation of the fields and the payload are specific to a The interpretation of the fields and the payload are specific to a
version and packet type. Type-specific semantics for this version version and packet type. Type-specific semantics for this version
are described in Section 5.3, Section 5.6, Section 5.4, and are described in the following sections.
Section 5.5.
5.2. Short Header 5.2. Short Header
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|0|C|K| Type (5)| |0|C|K| Type (5)|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ [Connection ID (64)] + + [Connection ID (64)] +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Packet Number (8/16/32) ... | Packet Number (8/16/32) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Encrypted Payload (*) ... | Protected Payload (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Short Header Format Figure 2: Short Header Format
The short header can be used after the version and 1-RTT keys are The short header can be used after the version and 1-RTT keys are
negotiated. This header form has the following fields: negotiated. This header form has the following fields:
Header Form: The most significant bit (0x80) of the first octet of a Header Form: The most significant bit (0x80) of the first octet of a
packet is the header form. This bit is set to 0 for the short packet is the header form. This bit is set to 0 for the short
header. header.
skipping to change at page 12, line 9 skipping to change at page 12, line 49
for short packets. for short packets.
Connection ID: If the Connection ID Flag is set, a connection ID Connection ID: If the Connection ID Flag is set, a connection ID
occupies octets 1 through 8 of the packet. See Section 5.7 for occupies octets 1 through 8 of the packet. See Section 5.7 for
more details. more details.
Packet Number: The length of the packet number field depends on the Packet Number: The length of the packet number field depends on the
packet type. This field can be 1, 2 or 4 octets long depending on packet type. This field can be 1, 2 or 4 octets long depending on
the short packet type. the short packet type.
Encrypted Payload: Packets with a short header always include a Protected Payload: Packets with a short header always include a
1-RTT protected payload. 1-RTT protected payload.
The packet type in a short header currently determines only the size The packet type in a short header currently determines only the size
of the packet number field. Additional types can be used to signal of the packet number field. Additional types can be used to signal
the presence of other fields. the presence of other fields.
+------+--------------------+ +------+--------------------+
| Type | Packet Number Size | | Type | Packet Number Size |
+------+--------------------+ +------+--------------------+
| 01 | 1 octet | | 01 | 1 octet |
skipping to change at page 12, line 35 skipping to change at page 13, line 28
Table 2: Short Header Packet Types Table 2: Short Header Packet Types
The header form, connection ID flag and connection ID of a short The header form, connection ID flag and connection ID of a short
header packet are version-independent. The remaining fields are header packet are version-independent. The remaining fields are
specific to the selected QUIC version. See Section 5.9 for details specific to the selected QUIC version. See Section 5.9 for details
on how packets from different versions of QUIC are interpreted. on how packets from different versions of QUIC are interpreted.
5.3. Version Negotiation Packet 5.3. Version Negotiation Packet
A Version Negotiation packet is sent only by servers and is a A Version Negotiation packet has long headers with a type value of
response to a client packet of an unsupported version. It uses a 0x01 and is sent only by servers. The Version Negotiation packet is
long header and contains: a response to a client packet that contains a version that is not
supported by the server.
o Octet 0: 0x81
o Octets 1-8: Connection ID (echoed)
o Octets 9-12: Packet Number (echoed)
o Octets 13-16: Version (echoed) The connection ID field contains a server-selected connection ID that
the client MUST use for subsequent packets, see Section 5.7.
o Octets 17+: Payload The packet number and version fields echo corresponding values from
the triggering client packet. This allows clients some assurance
that the server received the packet and that the Version Negotiation
packet was not carried in a packet with a spoofed source address.
The payload of the Version Negotiation packet is a list of 32-bit The payload of the Version Negotiation packet is a list of 32-bit
versions which the server supports, as shown below. versions which the server supports, as shown below.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Supported Version 1 (32) ... | Supported Version 1 (32) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| [Supported Version 2 (32)] ... | [Supported Version 2 (32)] ...
skipping to change at page 13, line 24 skipping to change at page 14, line 24
| [Supported Version N (32)] ... | [Supported Version N (32)] ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Version Negotiation Packet Figure 3: Version Negotiation Packet
See Section 7.1 for a description of the version negotiation process. See Section 7.1 for a description of the version negotiation process.
5.4. Cleartext Packets 5.4. Cleartext Packets
Cleartext packets are sent during the handshake prior to key Cleartext packets are sent during the handshake prior to key
negotiation. A Client Cleartext packet contains: negotiation.
o Octet 0: 0x82 All cleartext packets contain the current QUIC version in the version
field.
o Octets 1-8: Connection ID (initial) The payload of cleartext packets also includes an integrity check,
which is described in [QUIC-TLS].
o Octets 9-12: Packet number 5.4.1. Client Initial Packet
o Octets 13-16: Version The Client Initial packet uses long headers with a type value of
0x02. It carries the first cryptographic handshake message sent by
the client.
o Octets 17+: Payload The client populates the connection ID field with randomly selected
values, unless it has received a packet from the server. If the
client has received a packet from the server, the connection ID field
uses the value provided by the server.
Non-Final Server Cleartext packets contain: The packet number used for Client Initial packets is initialized with
a random value each time the new contents are created for the packet.
Retransmissions of the packet contents increment the packet number by
one, see (Section 5.8).
o Octet 0: 0x83 The payload of a Client Initial packet consists of a STREAM frame (or
frames) for stream 0 containing a cryptographic handshake message,
plus any PADDING frames necessary to ensure that the packet is at
least the minimum size (see Section 9). This stream frame always
starts at an offset of 0 (see Section 7.4).
o Octets 1-8: Connection ID (echoed) The client uses the Client Initial Packet type for any packet that
contains an initial cryptographic handshake message. This includes
all cases where a new packet containing the initial cryptographic
message needs to be created, this includes the packets sent after
receiving a Version Negotiation (Section 5.3) or Server Stateless
Retry packet (Section 5.4.2).
o Octets 9-12: Packet Number 5.4.2. Server Stateless Retry Packet
o Octets 13-16: Version A Server Stateless Retry packet uses long headers with a type value
of 0x03. It carries cryptographic handshake messages and
acknowledgments. It is used by a server that wishes to perform a
stateless retry (see Section 7.4).
o Octets 17+: Payload The connection ID field in a Server Stateless Retry packet contains a
server selected value, see Section 5.7.
Final Server Cleartext packets contains: The packet number field echoes the packet number of the triggering
client packet. This allows a client to verify that the server
received its packet.
o Octet 0: 0x84 After receiving a Server Stateless Retry packet, the client uses a
new Client Initial packet containing the next cryptographic handshake
message. The client retains the state of its cryptographic
handshake, but discards all transport state. In effect, the next
cryptographic handshake message is sent on a new connection. The new
Client Initial packet is sent in a packet with a newly randomized
packet number and starting at a stream offset of 0.
o Octets 1-8: Connection ID (final) Continuing the cryptographic handshake is necessary to ensure that an
o Octets 9-12: Packet Number attacker cannot force a downgrade of any cryptographic parameters.
In addition to continuing the cryptographic handshake, the client
MUST remember the results of any version negotiation that occurred
(see Section 7.1). The client MAY also retain any observed RTT or
congestion state that it has accumulated for the flow, but other
transport state MUST be discarded.
o Octets 13-16: Version The payload of the Server Stateless Retry packet contains STREAM
frames and could contain PADDING and ACK frames. A server can only
send a single Server Stateless Retry packet in response to each
Client Initial packet that is receives.
o Octets 17+: Payload 5.4.3. Server Cleartext Packet
The client MUST choose a random 64-bit value and use it as the A Server Cleartext packet uses long headers with a type value of
initial Connection ID in all packets until the server replies with 0x04. It is used to carry acknowledgments and cryptographic
the final Connection ID. The server echoes the client's Connection handshake messages from the server.
ID in Non-Final Server Cleartext packets. The first Final Server
Cleartext and all subsequent packets MUST use the final Connection
ID, as described in Section 5.7.
The payload of a Cleartext packet consists of a sequence of frames, The connection ID field in a Server Cleartext packet contains a
as described in Section 6. connection ID that is chosen by the server (see Section 5.7).
(TODO: Add hash before frames.) The first Server Cleartext packet contains a randomized packet
number. This value is increased for each subsequent packet sent by
the server as described in Section 5.8.
5.5. Encrypted Packets The payload of this packet contains STREAM frames and could contain
PADDING and ACK frames.
Packets encrypted with either 0-RTT or 1-RTT keys may be sent with 5.4.4. Client Cleartext Packet
long headers. Different packet types explicitly indicate the
encryption level for ease of decryption. These packets contain:
o Octet 0: 0x85, 0x86 or 0x87 A Client Cleartext packet uses long headers with a type value of
0x05, and is sent when the client has received a Server Cleartext
packet from the server.
o Octets 1-8: Connection ID (initial or final) The connection ID field in a Client Cleartext packet contains a
server-selected connection ID, see Section 5.7.
o Octets 9-12: Packet Number The Client Cleartext packet includes a packet number that is one
higher than the last Client Initial, 0-RTT Protected or Client
Cleartext packet that was sent. The packet number is incremented for
each subsequent packet, see Section 5.8.
o Octets 13-16: Version The payload of this packet contains STREAM frames and could contain
PADDING and ACK frames.
o Octets 17+: Encrypted Payload 5.5. Protected Packets
A first octet of 0x85 indicates a 0-RTT packet. After the 1-RTT keys Packets that are protected with 0-RTT keys are sent with long
are established, key phases are used by the QUIC packet protection to headers. Packets that are protected with 1-RTT keys MAY be sent with
identify the correct packet protection keys. The initial key phase long headers. The different packet types explicitly indicate the
is 0. See [QUIC-TLS] for more details. encryption level and therefore the keys that are used to remove
packet protection.
The encrypted payload is both authenticated and encrypted using Packets protected with 0-RTT keys use a type value of 0x06. The
packet protection keys. [QUIC-TLS] describes packet protection in connection ID field for a 0-RTT packet is selected by the client.
detail. After decryption, the plaintext consists of a sequence of
frames, as described in Section 6. The client can send 0-RTT packets after having received a packet from
the server if that packet does not complete the handshake. Even if
the client receives a different connection ID from the server, it
MUST NOT update the connection ID it uses for 0-RTT packets. This
enables consistent routing for all 0-RTT packets.
Packets protected with 1-RTT keys that use long headers use a type
value of 0x07 for key phase 0 and 0x08 for key phase 1; see
[QUIC-TLS] for more details on the use of key phases. The connection
ID field for these packet types MUST contain the value selected by
the server, see Section 5.7.
The version field for protected packets is the current QUIC version.
The packet number field contains a packet number, which increases
with each packet sent, see Section 5.8 for details.
The payload is protected using authenticated encryption. [QUIC-TLS]
describes packet protection in detail. After decryption, the
plaintext consists of a sequence of frames, as described in
Section 6.
5.6. Public Reset Packet 5.6. Public Reset Packet
A Public Reset packet is only sent by servers and is used to abruptly A Public Reset packet is only sent by servers and is used to abruptly
terminate communications. Public Reset is provided as an option of terminate communications. Public Reset is provided as an option of
last resort for a server that does not have access to the state of a last resort for a server that does not have access to the state of a
connection. This is intended for use by a server that has lost state connection. This is intended for use by a server that has lost state
(for example, through a crash or outage). A server that wishes to (for example, through a crash or outage). A server that wishes to
communicate a fatal connection error MUST use a CONNECTION_CLOSE communicate a fatal connection error MUST use a CONNECTION_CLOSE
frame if it has sufficient state to do so. frame if it has sufficient state to do so.
A Public Reset packet contains: A Public Reset packet uses long headers with a type value of 0x09.
o Octet 0: 0x88
o Octets 1-8: Echoed data (octets 1-8 of received packet)
o Octets 9-12: Echoed data (octets 9-12 of received packet)
o Octets 13-16: Version
o Octets 17+: Public Reset Proof The connection ID and packet number of fields together contain octets
1 through 12 from the packet that triggered the reset. For a client
that sends a connection ID on every packet, the Connection ID field
is simply an echo of the client's Connection ID, and the Packet
Number field includes an echo of the client's packet number.
Depending on the client's packet number length it might also include
0, 2, or 3 additional octets from the protected payload of the client
packet.
For a client that sends a connection ID on every packet, the The version field contains the current QUIC version.
Connection ID field is simply an echo of the initial Connection ID,
and the Packet Number field includes an echo of the client's packet
number (and, depending on the client's packet number length, 0, 2, or
3 additional octets from the client's packet).
A Public Reset packet sent by a server indicates that it does not A Public Reset packet sent by a server indicates that it does not
have the state necessary to continue with a connection. In this have the state necessary to continue with a connection. In this
case, the server will include the fields that prove that it case, the server will include the fields that prove that it
originally participated in the connection (see Section 5.6.1 for originally participated in the connection (see Section 5.6.1 for
details). details).
Upon receipt of a Public Reset packet that contains a valid proof, a Upon receipt of a Public Reset packet that contains a valid proof, a
client MUST tear down state associated with the connection. The client MUST tear down state associated with the connection. The
client MUST then cease sending packets on the connection and SHOULD client MUST then cease sending packets on the connection and SHOULD
skipping to change at page 16, line 14 skipping to change at page 18, line 18
5.7. Connection ID 5.7. Connection ID
QUIC connections are identified by their 64-bit Connection ID. All QUIC connections are identified by their 64-bit Connection ID. All
long headers contain a Connection ID. Short headers indicate the long headers contain a Connection ID. Short headers indicate the
presence of a Connection ID using the CONNECTION_ID flag. When presence of a Connection ID using the CONNECTION_ID flag. When
present, the Connection ID is in the same location in all packet present, the Connection ID is in the same location in all packet
headers, making it straightforward for middleboxes, such as load headers, making it straightforward for middleboxes, such as load
balancers, to locate and use it. balancers, to locate and use it.
When a connection is initiated, the client MUST choose a random value The client MUST choose a random connection ID and use it in Client
and use it as the initial Connection ID until the final value is Initial packets (Section 5.4.1). If the client has received any
available. The initial Connection ID is a suggestion to the server. packet from the server, it uses the connection ID it received from
The server echoes this value in all packets until the handshake is the server.
successful (see [QUIC-TLS]). On a successful handshake, the server
MUST select the final Connection ID for the connection and use it in
Final Server Cleartext packets. This final Connection ID MAY be the
one proposed by the client or MAY be a new server-selected value.
All subsequent packets from the server MUST contain this value. On
handshake completion, the client MUST switch to using the final
Connection ID for all subsequent packets.
Thus, all Client Cleartext packets, 0-RTT Encrypted packets, and Non- When the server receives a Client Initial packet, it chooses a new
Final Server Cleartext packets MUST use the client's randomly- value for the connection ID and sends that in its response. The
generated initial Connection ID. Final Server Cleartext packets, server MUST send a new connection ID in any packet that is sent in
1-RTT Encrypted packets, and all short-header packets MUST use the response to a Client Initial packet. This includes Version
final Connection ID. Negotiation (Section 5.3), Server Stateless Retry (Section 5.4.2),
and the first Server Cleartext packet (Section 5.4.3). The server
MAY choose to use the value that the client initially selects.
A server MUST NOT propose a different connection ID in response to a
Client Cleartext packet (Section 5.4.4). A Client Cleartext packet
is only sent after the server has committed to maintaining connection
state.
5.8. Packet Numbers 5.8. Packet Numbers
The packet number is a 64-bit unsigned number and is used as part of The packet number is a 64-bit unsigned number and is used as part of
a cryptographic nonce for packet encryption. Each endpoint maintains a cryptographic nonce for packet encryption. Each endpoint maintains
a separate packet number for sending and receiving. The packet a separate packet number for sending and receiving. The packet
number for sending MUST increase by at least one after sending any number for sending MUST increase by at least one after sending any
packet. packet, unless otherwise specified (see Section 5.8.1).
A QUIC endpoint MUST NOT reuse a packet number within the same A QUIC endpoint MUST NOT reuse a packet number within the same
connection (that is, under the same cryptographic keys). If the connection (that is, under the same cryptographic keys). If the
packet number for sending reaches 2^64 - 1, the sender MUST close the packet number for sending reaches 2^64 - 1, the sender MUST close the
connection by sending a CONNECTION_CLOSE frame with the error code connection by sending a CONNECTION_CLOSE frame with the error code
QUIC_SEQUENCE_NUMBER_LIMIT_REACHED (connection termination is QUIC_SEQUENCE_NUMBER_LIMIT_REACHED (connection termination is
described in Section 7.6.) described in Section 7.7.)
To reduce the number of bits required to represent the packet number To reduce the number of bits required to represent the packet number
over the wire, only the least significant bits of the packet number over the wire, only the least significant bits of the packet number
are transmitted over the wire, up to 32 bits. The actual packet are transmitted over the wire, up to 32 bits. The actual packet
number for each packet is reconstructed at the receiver based on the number for each packet is reconstructed at the receiver based on the
largest packet number received on a successfully authenticated largest packet number received on a successfully authenticated
packet. packet.
A packet number is decoded by finding the packet number value that is A packet number is decoded by finding the packet number value that is
closest to the next expected packet. The next expected packet is the closest to the next expected packet. The next expected packet is the
skipping to change at page 17, line 29 skipping to change at page 19, line 33
As a result, the size of the packet number encoding is at least one As a result, the size of the packet number encoding is at least one
more than the base 2 logarithm of the number of contiguous more than the base 2 logarithm of the number of contiguous
unacknowledged packet numbers, including the new packet. unacknowledged packet numbers, including the new packet.
For example, if an endpoint has received an acknowledgment for packet For example, if an endpoint has received an acknowledgment for packet
0x6afa2f, sending a packet with a number of 0x6b4264 requires a 0x6afa2f, sending a packet with a number of 0x6b4264 requires a
16-bit or larger packet number encoding; whereas a 32-bit packet 16-bit or larger packet number encoding; whereas a 32-bit packet
number is needed to send a packet with a number of 0x6bc107. number is needed to send a packet with a number of 0x6bc107.
Version Negotiation (Section 5.3), Server Stateless Retry
(Section 5.4.2), and Public Reset (Section 5.6) packets have special
rules for populating the packet number field.
5.8.1. Initial Packet Number 5.8.1. Initial Packet Number
The initial value for packet number MUST be a 31-bit random number. The initial value for packet number MUST be selected from an uniform
That is, the value is selected from an uniform random distribution random distribution between 0 and 2^31-1. That is, the lower 31 bits
between 0 and 2^31-1. [RFC4086] provides guidance on the generation of the packet number are randomized. [RFC4086] provides guidance on
of random values. the generation of random values.
The first set of packets sent by an endpoint MUST include the low The first set of packets sent by an endpoint MUST include the low
32-bits of the packet number. Once any packet has been acknowledged, 32-bits of the packet number. Once any packet has been acknowledged,
subsequent packets can use a shorter packet number encoding. subsequent packets can use a shorter packet number encoding.
A client that receives a Version Negotiation (Section 5.3) or Server
Stateless Retry packet (Section 5.4.2) MUST generate a new initial
packet number. This ensures that the first transmission attempt for
a Client Initial packet (Section 5.4.1) always contains a randomized
packet number, but packets that contain retransmissions increment the
packet number.
A client MUST NOT generate a new initial packet number if it discards
the server packet. This might happen if the information the client
retransmits its Client Initial packet.
5.9. Handling Packets from Different Versions 5.9. Handling Packets from Different Versions
Between different versions the following things are guaranteed to Between different versions the following things are guaranteed to
remain constant: remain constant:
o the location of the header form flag, o the location of the header form flag,
o the location of the Connection ID flag in short headers, o the location of the Connection ID flag in short headers,
o the location and size of the Connection ID field in both header o the location and size of the Connection ID field in both header
skipping to change at page 18, line 4 skipping to change at page 20, line 24
remain constant: remain constant:
o the location of the header form flag, o the location of the header form flag,
o the location of the Connection ID flag in short headers, o the location of the Connection ID flag in short headers,
o the location and size of the Connection ID field in both header o the location and size of the Connection ID field in both header
forms, forms,
o the location and size of the Version field in long headers, and o the location and size of the Version field in long headers, and
o the location and size of the Packet Number field in long headers. o the location and size of the Packet Number field in long headers.
Implementations MUST assume that an unsupported version uses an Implementations MUST assume that an unsupported version uses an
unknown packet format. All other fields MUST be ignored when unknown packet format. All other fields MUST be ignored when
processing a packet that contains an unsupported version. processing a packet that contains an unsupported version.
6. Frames and Frame Types 6. Frames and Frame Types
The payload of cleartext packets and the plaintext after decryption The payload of cleartext packets and the plaintext after decryption
of encrypted payloads consists of a sequence of frames, as shown in of protected payloads consists of a sequence of frames, as shown in
Figure 4. Figure 4.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Frame 1 (*) ... | Frame 1 (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Frame 2 (*) ... | Frame 2 (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
... ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Frame N (*) ... | Frame N (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Contents of Encrypted Payload Figure 4: Contents of Protected Payload
Encrypted payloads MUST contain at least one frame, and MAY contain Protected payloads MUST contain at least one frame, and MAY contain
multiple frames and multiple frame types. multiple frames and multiple frame types.
Frames MUST fit within a single QUIC packet and MUST NOT span a QUIC Frames MUST fit within a single QUIC packet and MUST NOT span a QUIC
packet boundary. Each frame begins with a Frame Type byte, packet boundary. Each frame begins with a Frame Type byte,
indicating its type, followed by additional type-dependent fields: indicating its type, followed by additional type-dependent fields:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type (8) | Type-Dependent Fields (*) ... | Type (8) | Type-Dependent Fields (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: Generic Frame Layout Figure 5: Generic Frame Layout
Frame types are listed in Table 3. Note that the Frame Type byte in Frame types are listed in Table 3. Note that the Frame Type byte in
STREAM and ACK frames is used to carry other frame-specific flags. STREAM and ACK frames is used to carry other frame-specific flags.
For all other frames, the Frame Type byte simply identifies the For all other frames, the Frame Type byte simply identifies the
frame. These frames are explained in more detail as they are frame. These frames are explained in more detail as they are
referenced later in the document. referenced later in the document.
+------------------+------------------+-------------+ +-------------+-------------------+--------------+
| Type-field value | Frame type | Definition | | Type Value | Frame Type Name | Definition |
+------------------+------------------+-------------+ +-------------+-------------------+--------------+
| 0x00 | PADDING | Section 8.6 | | 0x00 | PADDING | Section 8.10 |
| | | | | | | |
| 0x01 | RST_STREAM | Section 8.5 | | 0x01 | RST_STREAM | Section 8.9 |
| | | | | | | |
| 0x02 | CONNECTION_CLOSE | Section 8.8 | | 0x02 | CONNECTION_CLOSE | Section 8.13 |
| | | | | | | |
| 0x03 | GOAWAY | Section 8.9 | | 0x03 | GOAWAY | Section 8.14 |
| | | | | | | |
| 0x04 | WINDOW_UPDATE | Section 8.3 | | 0x04 | MAX_DATA | Section 8.3 |
| | | | | | | |
| 0x05 | BLOCKED | Section 8.4 | | 0x05 | MAX_STREAM_DATA | Section 8.4 |
| | | | | | | |
| 0x07 | PING | Section 8.7 | | 0x06 | MAX_STREAM_ID | Section 8.5 |
| | | | | | | |
| 0x40 - 0x7f | ACK | Section 8.2 | | 0x07 | PING | Section 8.11 |
| | | | | | | |
| 0x80 - 0xff | STREAM | Section 8.1 | | 0x08 | BLOCKED | Section 8.6 |
+------------------+------------------+-------------+ | | | |
| 0x09 | STREAM_BLOCKED | Section 8.7 |
| | | |
| 0x0a | STREAM_ID_NEEDED | Section 8.8 |
| | | |
| 0x0b | NEW_CONNECTION_ID | Section 8.12 |
| | | |
| 0xa0 - 0xbf | ACK | Section 8.2 |
| | | |
| 0xc0 - 0xff | STREAM | Section 8.1 |
+-------------+-------------------+--------------+
Table 3: Frame Types Table 3: Frame Types
7. Life of a Connection 7. Life of a Connection
A QUIC connection is a single conversation between two QUIC A QUIC connection is a single conversation between two QUIC
endpoints. QUIC's connection establishment intertwines version endpoints. QUIC's connection establishment intertwines version
negotiation with the cryptographic and transport handshakes to reduce negotiation with the cryptographic and transport handshakes to reduce
connection establishment latency, as described in Section 7.2. Once connection establishment latency, as described in Section 7.2. Once
established, a connection may migrate to a different IP or port at established, a connection may migrate to a different IP or port at
either endpoint, due to NAT rebinding or mobility, as described in either endpoint, due to NAT rebinding or mobility, as described in
Section 7.5. Finally a connection may be terminated by either Section 7.6. Finally a connection may be terminated by either
endpoint, as described in Section 7.6. endpoint, as described in Section 7.7.
7.1. Version Negotiation 7.1. Version Negotiation
QUIC's connection establishment begins with version negotiation, QUIC's connection establishment begins with version negotiation,
since all communication between the endpoints, including packet and since all communication between the endpoints, including packet and
frame formats, relies on the two endpoints agreeing on a version. frame formats, relies on the two endpoints agreeing on a version.
A QUIC connection begins with a client sending a handshake packet. A QUIC connection begins with a client sending a handshake packet.
The details of the handshake mechanisms are described in Section 7.2, The details of the handshake mechanisms are described in Section 7.2,
but all of the initial packets sent from the client to the server but all of the initial packets sent from the client to the server
MUST use the long header format and MUST specify the version of the MUST use the long header format and MUST specify the version of the
protocol being used. protocol being used.
When the server receives a packet from a client with the long header When the server receives a packet from a client with the long header
format, it compares the client's version to the versions it supports. format, it compares the client's version to the versions it supports.
If the version selected by the client is not acceptable to the If the version selected by the client is not acceptable to the
server, the server discards the incoming packet and responds with a server, the server discards the incoming packet and responds with a
Version Negotiation packet (Section 5.3). This includes a list of Version Negotiation packet (Section 5.3). This includes a list of
versions that the server will accept. A server MUST send a Version versions that the server will accept.
Negotiation packet for every packet that it receives with an
unacceptable version. A server sends a Version Negotiation packet for every packet that it
receives with an unacceptable version. This allows a server to
process packets with unsupported versions without retaining state.
Though either the initial client packet or the version negotiation
packet that is sent in response could be lost, the client will send
new packets until it successfully receives a response.
If the packet contains a version that is acceptable to the server, If the packet contains a version that is acceptable to the server,
the server proceeds with the handshake (Section 7.2). This commits the server proceeds with the handshake (Section 7.2). This commits
the server to the version that the client selected. the server to the version that the client selected.
When the client receives a Version Negotiation packet from the When the client receives a Version Negotiation packet from the
server, it should select an acceptable protocol version. If the server, it should select an acceptable protocol version. If the
server lists an acceptable version, the client selects that version server lists an acceptable version, the client selects that version
and reattempts to create a connection using that version. Though the and reattempts to create a connection using that version. Though the
contents of a packet might not change in response to version contents of a packet might not change in response to version
skipping to change at page 20, line 35 skipping to change at page 23, line 52
every packet it sends. Packets MUST continue to use long headers and every packet it sends. Packets MUST continue to use long headers and
MUST include the new negotiated protocol version. MUST include the new negotiated protocol version.
The client MUST use the long header format and include its selected The client MUST use the long header format and include its selected
version on all packets until it has 1-RTT keys and it has received a version on all packets until it has 1-RTT keys and it has received a
packet from the server which is not a Version Negotiation packet. packet from the server which is not a Version Negotiation packet.
A client MUST NOT change the version it uses unless it is in response A client MUST NOT change the version it uses unless it is in response
to a Version Negotiation packet from the server. Once a client to a Version Negotiation packet from the server. Once a client
receives a packet from the server which is not a Version Negotiation receives a packet from the server which is not a Version Negotiation
packet, it MUST ignore Version Negotiation packets on the same packet, it MUST ignore other Version Negotiation packets on the same
connection. connection. Similarly, a client MUST ignore a Version Negotiation
packet if it has already received and acted on a Version Negotiation
packet.
A client MUST ignore a Version Negotiation packet that lists the
client's chosen version.
Version negotiation uses unprotected data. The result of the Version negotiation uses unprotected data. The result of the
negotiation MUST be revalidated as part of the cryptographic negotiation MUST be revalidated as part of the cryptographic
handshake (see Section 7.3.4). handshake (see Section 7.3.4).
7.1.1. Using Reserved Versions 7.1.1. Using Reserved Versions
For a server to use a new version in the future, clients must For a server to use a new version in the future, clients must
correctly handle unsupported versions. To help ensure this, a server correctly handle unsupported versions. To help ensure this, a server
SHOULD include a reserved version (see Section 4) while generating a SHOULD include a reserved version (see Section 4) while generating a
skipping to change at page 21, line 20 skipping to change at page 24, line 42
A pseudorandom function that takes client address information (IP and A pseudorandom function that takes client address information (IP and
port) and the client selected version as input would ensure that port) and the client selected version as input would ensure that
there is sufficient variability in the values that a server uses. there is sufficient variability in the values that a server uses.
A client MAY send a packet using a reserved version number. This can A client MAY send a packet using a reserved version number. This can
be used to solicit a list of supported versions from a server. be used to solicit a list of supported versions from a server.
7.2. Cryptographic and Transport Handshake 7.2. Cryptographic and Transport Handshake
QUIC relies on a combined cryptographic and transport handshake to QUIC relies on a combined cryptographic and transport handshake to
minimize connection establishment latency. QUIC allocates stream 1 minimize connection establishment latency. QUIC allocates stream 0
for the cryptographic handshake. This version of QUIC uses TLS 1.3 for the cryptographic handshake. Version 0x00000001 of QUIC uses TLS
[QUIC-TLS]. 1.3 as described in [QUIC-TLS]; a different QUIC version number could
indicate that a different cryptographic handshake protocol is in use.
QUIC provides this stream with reliable, ordered delivery of data. QUIC provides this stream with reliable, ordered delivery of data.
In return, the cryptographic handshake provides QUIC with: In return, the cryptographic handshake provides QUIC with:
o authenticated key exchange, where o authenticated key exchange, where
* a server is always authenticated, * a server is always authenticated,
* a client is optionally authenticated, * a client is optionally authenticated,
* every connection produces distinct and unrelated keys, * every connection produces distinct and unrelated keys,
* keying material is usable for packet protection for both 0-RTT * keying material is usable for packet protection for both 0-RTT
and 1-RTT packets, and and 1-RTT packets, and
* 1-RTT keys have forward secrecy * 1-RTT keys have forward secrecy
skipping to change at page 21, line 51 skipping to change at page 25, line 26
Section 7.3) Section 7.3)
o authenticated confirmation of version negotiation (see o authenticated confirmation of version negotiation (see
Section 7.3.4) Section 7.3.4)
o authenticated negotiation of an application protocol (TLS uses o authenticated negotiation of an application protocol (TLS uses
ALPN [RFC7301] for this purpose) ALPN [RFC7301] for this purpose)
o for the server, the ability to carry data that provides assurance o for the server, the ability to carry data that provides assurance
that the client can receive packets that are addressed with the that the client can receive packets that are addressed with the
transport address that is claimed by the client (see Section 7.4) transport address that is claimed by the client (see Section 7.5)
The initial cryptographic handshake message MUST be sent in a single The initial cryptographic handshake message MUST be sent in a single
packet. Any second attempt that is triggered by address validation packet. Any second attempt that is triggered by address validation
MUST also be sent within a single packet. This avoids having to MUST also be sent within a single packet. This avoids having to
reassemble a message from multiple packets. Reassembling messages reassemble a message from multiple packets. Reassembling messages
requires that a server maintain state prior to establishing a requires that a server maintain state prior to establishing a
connection, exposing the server to a denial of service risk. connection, exposing the server to a denial of service risk.
The first client packet of the cryptographic handshake protocol MUST The first client packet of the cryptographic handshake protocol MUST
fit within a 1280 octet QUIC packet. This includes overheads that fit within a 1232 octet QUIC packet payload. This includes overheads
reduce the space available to the cryptographic handshake protocol. that reduce the space available to the cryptographic handshake
protocol.
Details of how TLS is integrated with QUIC is provided in more detail Details of how TLS is integrated with QUIC is provided in more detail
in [QUIC-TLS]. in [QUIC-TLS].
7.3. Transport Parameters 7.3. Transport Parameters
During connection establishment, both endpoints make authenticated During connection establishment, both endpoints make authenticated
declarations of their transport parameters. These declarations are declarations of their transport parameters. These declarations are
made unilaterally by each endpoint. Endpoints are required to comply made unilaterally by each endpoint. Endpoints are required to comply
with the restrictions implied by these parameters; the description of with the restrictions implied by these parameters; the description of
each parameter includes rules for its handling. each parameter includes rules for its handling.
The format of the transport parameters is the TransportParameters The format of the transport parameters is the TransportParameters
struct from Figure 6. This is described using the presentation struct from Figure 6. This is described using the presentation
language from Section 3 of [I-D.ietf-tls-tls13]. language from Section 3 of [I-D.ietf-tls-tls13].
uint32 QuicVersion; uint32 QuicVersion;
enum { enum {
stream_fc_offset(0), initial_max_stream_data(0),
connection_fc_offset(1), initial_max_data(1),
concurrent_streams(2), initial_max_stream_id(2),
idle_timeout(3), idle_timeout(3),
truncate_connection_id(4), truncate_connection_id(4),
(65535) (65535)
} TransportParameterId; } TransportParameterId;
struct { struct {
TransportParameterId parameter; TransportParameterId parameter;
opaque value<0..2^16-1>; opaque value<0..2^16-1>;
} TransportParameter; } TransportParameter;
skipping to change at page 24, line 10 skipping to change at page 27, line 10
properly complete. properly complete.
Definitions for each of the defined transport parameters are included Definitions for each of the defined transport parameters are included
in Section 7.3.1. in Section 7.3.1.
7.3.1. Transport Parameter Definitions 7.3.1. Transport Parameter Definitions
An endpoint MUST include the following parameters in its encoded An endpoint MUST include the following parameters in its encoded
TransportParameters: TransportParameters:
stream_fc_offset (0x0000): The initial stream level flow control initial_max_stream_data (0x0000): The initial stream maximum data
offset parameter is encoded as an unsigned 32-bit integer in units parameter contains the initial value for the maximum data that can
of octets. The sender of this parameter indicates that the flow be sent on any newly created stream. This parameter is encoded as
control offset for all stream data sent toward it is this value. an unsigned 32-bit integer in units of octets. This is equivalent
to an implicit MAX_STREAM_DATA frame (Section 8.4) being sent on
all streams immediately after opening.
connection_fc_offset (0x0001): The connection level flow control initial_max_data (0x0001): The initial maximum data parameter
offset parameter contains the initial connection flow control contains the initial value for the maximum amount of data that can
window encoded as an unsigned 32-bit integer in units of 1024 be sent on the connection. This parameter is encoded as an
octets. That is, the value here is multiplied by 1024 to unsigned 32-bit integer in units of 1024 octets. That is, the
determine the actual flow control offset. The sender of this value here is multiplied by 1024 to determine the actual maximum
parameter sets the byte offset for connection level flow control value. This is equivalent to sending a MAX_DATA (Section 8.3) for
to this value. This is equivalent to sending a WINDOW_UPDATE the connection immediately after completing the handshake.
(Section 8.3) for the connection immediately after completing the
handshake.
concurrent_streams (0x0002): The maximum number of concurrent initial_max_stream_id (0x0002): The initial maximum stream ID
streams parameter is encoded as an unsigned 32-bit integer. parameter contains the initial maximum stream number the peer may
initiate, encoded as an unsigned 32-bit integer. This is
equivalent to sending a MAX_STREAM_ID (Section 8.5) immediately
after completing the handshake.
idle_timeout (0x0003): The idle timeout is a value in seconds that idle_timeout (0x0003): The idle timeout is a value in seconds that
is encoded as an unsigned 16-bit integer. The maximum value is is encoded as an unsigned 16-bit integer. The maximum value is
600 seconds (10 minutes). 600 seconds (10 minutes).
An endpoint MAY use the following transport parameters: An endpoint MAY use the following transport parameters:
truncate_connection_id (0x0004): The truncated connection identifier truncate_connection_id (0x0004): The truncated connection identifier
parameter indicates that packets sent to the peer can omit the parameter indicates that packets sent to the peer can omit the
connection ID. This can be used by an endpoint where the 5-tuple connection ID. This can be used by an endpoint where the 5-tuple
is sufficient to identify a connection. This parameter is zero is sufficient to identify a connection. This parameter is zero
length. Omitting the parameter indicates that the endpoint relies length. Omitting the parameter indicates that the endpoint relies
on the connection ID being present in every packet. on the connection ID being present in every packet.
7.3.2. Values of Transport Parameters for 0-RTT 7.3.2. Values of Transport Parameters for 0-RTT
Transport parameters from the server SHOULD be remembered by the Transport parameters from the server MUST be remembered by the client
client for use with 0-RTT data. A client that doesn't remember for use with 0-RTT data. If the TLS NewSessionTicket message
values from a previous connection can instead assume the following includes the quic_transport_parameters extension, then those values
values: stream_fc_offset (65535), connection_fc_offset (65535), are used for the server values when establishing a new connection
concurrent_streams (10), idle_timeout (600), truncate_connection_id using that ticket. Otherwise, the transport parameters that the
(absent). server advertises during connection establishment are used.
If assumed values change as a result of completing the handshake, the
client is expected to respect the new values. This introduces some
potential problems, particularly with respect to transport parameters
that establish limits:
o A client might exceed a newly declared connection or stream flow A server can remember the transport parameters that it advertised, or
control limit with 0-RTT data. If this occurs, the client ceases store an integrity-protected copy of the values in the ticket and
transmission as though the flow control limit was reached. Once recover the information when accepting 0-RTT data. A server uses the
WINDOW_UPDATE frames indicating an increase to the affected flow transport parameters in determining whether to accept 0-RTT data.
control offsets is received, the client can recommence sending.
o Similarly, a client might exceed the concurrent stream limit A server MAY accept 0-RTT and subsequently provide different values
declared by the server. A client MUST reset any streams that for transport parameters for use in the new connection. If 0-RTT
exceed this limit. A server SHOULD reset any streams it cannot data is accepted by the server, the server MUST NOT reduce any limits
handle with a code that allows the client to retry any application or alter any values that might be violated by the client with its
action bound to those streams. 0-RTT data. In particular, a server that accepts 0-RTT data MUST NOT
set values for initial_max_data or initial_max_stream_data that are
smaller than the remembered value of those parameters. Similarly, a
server MUST NOT reduce the value of initial_max_stream_id.
A server MAY close a connection if remembered or assumed 0-RTT A server MUST reject 0-RTT data or even abort a handshake if the
transport parameters cannot be supported, using an error code that is implied values for transport parameters cannot be supported.
appropriate to the specific condition. For example, a
QUIC_FLOW_CONTROL_RECEIVED_TOO_MUCH_DATA might be used to indicate
that exceeding flow control limits caused the error. A client that
has a connection closed due to an error condition SHOULD NOT attempt
0-RTT when attempting to create a new connection.
7.3.3. New Transport Parameters 7.3.3. New Transport Parameters
New transport parameters can be used to negotiate new protocol New transport parameters can be used to negotiate new protocol
behavior. An endpoint MUST ignore transport parameters that it does behavior. An endpoint MUST ignore transport parameters that it does
not support. Absence of a transport parameter therefore disables any not support. Absence of a transport parameter therefore disables any
optional protocol feature that is negotiated using the parameter. optional protocol feature that is negotiated using the parameter.
The definition of a transport parameter SHOULD include a default
value that a client can use when establishing a new connection. If
no default is specified, the value can be assumed to be absent when
attempting 0-RTT.
New transport parameters can be registered according to the rules in New transport parameters can be registered according to the rules in
Section 14.1. Section 14.1.
7.3.4. Version Negotiation Validation 7.3.4. Version Negotiation Validation
The transport parameters include three fields that encode version The transport parameters include three fields that encode version
information. These retroactively authenticate the version information. These retroactively authenticate the version
negotiation (see Section 7.1) that is performed prior to the negotiation (see Section 7.1) that is performed prior to the
cryptographic handshake. cryptographic handshake.
skipping to change at page 27, line 5 skipping to change at page 29, line 42
the supported_versions list and - if version negotiation was the supported_versions list and - if version negotiation was
performed - that it would have selected the negotiated version. A performed - that it would have selected the negotiated version. A
client MUST terminate the connection with a client MUST terminate the connection with a
QUIC_VERSION_NEGOTIATION_MISMATCH error code if the QUIC_VERSION_NEGOTIATION_MISMATCH error code if the
negotiated_version value is not included in the supported_versions negotiated_version value is not included in the supported_versions
list. A client MUST terminate with a list. A client MUST terminate with a
QUIC_VERSION_NEGOTIATION_MISMATCH error code if version negotiation QUIC_VERSION_NEGOTIATION_MISMATCH error code if version negotiation
occurred but it would have selected a different version based on the occurred but it would have selected a different version based on the
value of the supported_versions list. value of the supported_versions list.
7.4. Proof of Source Address Ownership 7.4. Stateless Retries
A server can process an initial cryptographic handshake messages from
a client without committing any state. This allows a server to
perform address validation (Section 7.5, or to defer connection
establishment costs.
A server that generates a response to an initial packet without
retaining connection state MUST use the Server Stateless Retry packet
(Section 5.4.2). This packet causes a client to reset its transport
state and to continue the connection attempt with new connection
state while maintaining the state of the cryptographic handshake.
A server MUST NOT send multiple Server Stateless Retry packets in
response to a client handshake packet. Thus, any cryptographic
handshake message that is sent MUST fit within a single packet.
In TLS, the Server Stateless Retry packet type is used to carry the
HelloRetryRequest message.
7.5. Proof of Source Address Ownership
Transport protocols commonly spend a round trip checking that a Transport protocols commonly spend a round trip checking that a
client owns the transport address (IP and port) that it claims. client owns the transport address (IP and port) that it claims.
Verifying that a client can receive packets sent to its claimed Verifying that a client can receive packets sent to its claimed
transport address protects against spoofing of this information by transport address protects against spoofing of this information by
malicious clients. malicious clients.
This technique is used primarily to avoid QUIC from being used for This technique is used primarily to avoid QUIC from being used for
traffic amplification attack. In such an attack, a packet is sent to traffic amplification attack. In such an attack, a packet is sent to
a server with spoofed source address information that identifies a a server with spoofed source address information that identifies a
victim. If a server generates more or larger packets in response to victim. If a server generates more or larger packets in response to
that packet, the attacker can use the server to send more data toward that packet, the attacker can use the server to send more data toward
the victim than it would be able to send on its own. the victim than it would be able to send on its own.
Several methods are used in QUIC to mitigate this attack. Firstly, Several methods are used in QUIC to mitigate this attack. Firstly,
the initial handshake packet from a client is padded to at least 1280 the initial handshake packet is padded to at least 1280 octets. This
octets. This allows a server to send a similar amount of data allows a server to send a similar amount of data without risking
without risking causing an amplication attack toward an unproven causing an amplification attack toward an unproven remote address.
remote address.
A server eventually confirms that a client has received its messages A server eventually confirms that a client has received its messages
when the cryptographic handshake successfully completes. This might when the cryptographic handshake successfully completes. This might
be insufficient, either because the server wishes to avoid the be insufficient, either because the server wishes to avoid the
computational cost of completing the handshake, or it might be that computational cost of completing the handshake, or it might be that
the size of the packets that are sent during the handshake is too the size of the packets that are sent during the handshake is too
large. This is especially important for 0-RTT, where the server large. This is especially important for 0-RTT, where the server
might wish to provide application data traffic - such as a response might wish to provide application data traffic - such as a response
to a request - in response to the data carried in the early data from to a request - in response to the data carried in the early data from
the client. the client.
To send additional data prior to completing the cryptographic To send additional data prior to completing the cryptographic
handshake, the server then needs to validate that the client owns the handshake, the server then needs to validate that the client owns the
address that it claims. address that it claims.
Source address validation is therefore performed during the Source address validation is therefore performed during the
establishment of a connection. TLS provides the tools that support establishment of a connection. TLS provides the tools that support
the feature, but basic validation is performed by the core transport the feature, but basic validation is performed by the core transport
protocol. protocol.
7.4.1. Client Address Validation Procedure 7.5.1. Client Address Validation Procedure
QUIC uses token-based address validation. Any time the server wishes QUIC uses token-based address validation. Any time the server wishes
to validate a client address, it provides the client with a token. to validate a client address, it provides the client with a token.
As long as the token cannot be easily guessed (see Section 7.4.3), if As long as the token cannot be easily guessed (see Section 7.5.3), if
the client is able to return that token, it proves to the server that the client is able to return that token, it proves to the server that
it received the token. it received the token.
During the processing of the cryptographic handshake messages from a During the processing of the cryptographic handshake messages from a
client, TLS will request that QUIC make a decision about whether to client, TLS will request that QUIC make a decision about whether to
proceed based on the information it has. TLS will provide QUIC with proceed based on the information it has. TLS will provide QUIC with
any token that was provided by the client. For an initial packet, any token that was provided by the client. For an initial packet,
QUIC can decide to abort the connection, allow it to proceed, or QUIC can decide to abort the connection, allow it to proceed, or
request address validation. request address validation.
skipping to change at page 28, line 34 skipping to change at page 31, line 42
asks QUIC a second time whether the token is acceptable. In asks QUIC a second time whether the token is acceptable. In
response, QUIC can either abort the connection or permit it to response, QUIC can either abort the connection or permit it to
proceed. proceed.
A connection MAY be accepted without address validation - or with A connection MAY be accepted without address validation - or with
only limited validation - but a server SHOULD limit the data it sends only limited validation - but a server SHOULD limit the data it sends
toward an unvalidated address. Successful completion of the toward an unvalidated address. Successful completion of the
cryptographic handshake implicitly provides proof that the client has cryptographic handshake implicitly provides proof that the client has
received packets from the server. received packets from the server.
7.4.2. Address Validation on Session Resumption 7.5.2. Address Validation on Session Resumption
A server MAY provide clients with an address validation token during A server MAY provide clients with an address validation token during
one connection that can be used on a subsequent connection. Address one connection that can be used on a subsequent connection. Address
validation is especially important with 0-RTT because a server validation is especially important with 0-RTT because a server
potentially sends a significant amount of data to a client in potentially sends a significant amount of data to a client in
response to 0-RTT data. response to 0-RTT data.
A different type of token is needed when resuming. Unlike the token A different type of token is needed when resuming. Unlike the token
that is created during a handshake, there might be some time between that is created during a handshake, there might be some time between
when the token is created and when the token is subsequently used. when the token is created and when the token is subsequently used.
skipping to change at page 28, line 45 skipping to change at page 32, line 4
A server MAY provide clients with an address validation token during A server MAY provide clients with an address validation token during
one connection that can be used on a subsequent connection. Address one connection that can be used on a subsequent connection. Address
validation is especially important with 0-RTT because a server validation is especially important with 0-RTT because a server
potentially sends a significant amount of data to a client in potentially sends a significant amount of data to a client in
response to 0-RTT data. response to 0-RTT data.
A different type of token is needed when resuming. Unlike the token A different type of token is needed when resuming. Unlike the token
that is created during a handshake, there might be some time between that is created during a handshake, there might be some time between
when the token is created and when the token is subsequently used. when the token is created and when the token is subsequently used.
Thus, a resumption token SHOULD include an expiration time. It is Thus, a resumption token SHOULD include an expiration time. It is
also unlikely that the client port number is the same on two also unlikely that the client port number is the same on two
different connections; validating the port is therefore unlikely to different connections; validating the port is therefore unlikely to
be successful. be successful.
This token can be provided to the cryptographic handshake immediately This token can be provided to the cryptographic handshake immediately
after establishing a connection. QUIC might also generate an updated after establishing a connection. QUIC might also generate an updated
token if significant time passes or the client address changes for token if significant time passes or the client address changes for
any reason (see Section 7.5). The cryptographic handshake is any reason (see Section 7.6). The cryptographic handshake is
responsible for providing the client with the token. In TLS the responsible for providing the client with the token. In TLS the
token is included in the ticket that is used for resumption and token is included in the ticket that is used for resumption and
0-RTT, which is carried in a NewSessionTicket message. 0-RTT, which is carried in a NewSessionTicket message.
7.4.3. Address Validation Token Integrity 7.5.3. Address Validation Token Integrity
An address validation token MUST be difficult to guess. Including a An address validation token MUST be difficult to guess. Including a
large enough random value in the token would be sufficient, but this large enough random value in the token would be sufficient, but this
depends on the server remembering the value it sends to clients. depends on the server remembering the value it sends to clients.
A token-based scheme allows the server to offload any state A token-based scheme allows the server to offload any state
associated with validation to the client. For this design to work, associated with validation to the client. For this design to work,
the token MUST be covered by integrity protection against the token MUST be covered by integrity protection against
modification or falsification by clients. Without integrity modification or falsification by clients. Without integrity
protection, malicious clients could generate or guess values for protection, malicious clients could generate or guess values for
skipping to change at page 29, line 33 skipping to change at page 32, line 42
In TLS the address validation token is often bundled with the In TLS the address validation token is often bundled with the
information that TLS requires, such as the resumption secret. In information that TLS requires, such as the resumption secret. In
this case, adding integrity protection can be delegated to the this case, adding integrity protection can be delegated to the
cryptographic handshake protocol, avoiding redundant protection. If cryptographic handshake protocol, avoiding redundant protection. If
integrity protection is delegated to the cryptographic handshake, an integrity protection is delegated to the cryptographic handshake, an
integrity failure will result in immediate cryptographic handshake integrity failure will result in immediate cryptographic handshake
failure. If integrity protection is performed by QUIC, QUIC MUST failure. If integrity protection is performed by QUIC, QUIC MUST
abort the connection if the integrity check fails with a abort the connection if the integrity check fails with a
QUIC_ADDRESS_VALIDATION_FAILURE error code. QUIC_ADDRESS_VALIDATION_FAILURE error code.
7.5. Connection Migration 7.6. Connection Migration
QUIC connections are identified by their 64-bit Connection ID. QUIC connections are identified by their 64-bit Connection ID.
QUIC's consistent connection ID allows connections to survive changes QUIC's consistent connection ID allows connections to survive changes
to the client's IP and/or port, such as those caused by client or to the client's IP and/or port, such as those caused by client or
server migrating to a new network. QUIC also provides automatic server migrating to a new network. Connection migration allows a
cryptographic verification of a client which has changed its IP client to retain any shared state with a connection when they move
address because the client continues to use the same session key for networks. This includes state that can be hard to recover such as
encrypting and decrypting packets. outstanding requests, which might otherwise be lost with no easy way
to retry them.
DISCUSS: Simultaneous migration. Is this reasonable? 7.6.1. Privacy Implications of Connection Migration
TODO: Perhaps move mitigation techniques from Security Considerations Using a stable connection ID on multiple network paths allows a
here. passive observer to correlate activity between those paths. A client
that moves between networks might not wish to have their activity
correlated by any entity other than a server. The NEW_CONNECTION_ID
message can be sent by a server to provide an unlinkable connection
ID for use in case the client wishes to explicitly break linkability
between two points of network attachment.
7.6. Connection Termination A client which wishes to break linkability upon changing networks
MUST use the NEW_CONNECTION_ID as well as incrementing the packet
sequence number by an externally unpredictable value computed as
described in Section 7.6.1.1. Packet number gaps are cumulative. A
client might skip connection IDs, but it MUST ensure that it applies
the associated packet number gaps in addition to the packet number
gap associated with the connection ID that it does use.
A client might need to send packets on multiple networks without
receiving any response from the server. To ensure that the client is
not linkable across each of these changes, a new connection ID and
packet number gap are needed for each network. To support this, a
server sends multiple NEW_CONNECTION_ID messages. Each
NEW_CONNECTION_ID is marked with a sequence number. Connection IDs
MUST be used in the order in which they are numbered.
A server that receives a packet that is marked with a new connection
ID recovers the packet number by adding the cumulative packet number
gap to its expected packet number. A server SHOULD discard packets
that contain a smaller gap than it advertised.
For instance, a server might provide a packet number gap of 7
associated with a new connection ID. If the server received packet
10 using the previous connection ID, it should expect packets on the
new connection ID to start at 18. A packet with the new connection
ID and a packet number of 17 is discarded as being in error.
7.6.1.1. Packet Number Gap
In order to avoid linkage, the packet number gap MUST be externally
indistinguishable from random. The packet number gap for a
connection ID with sequence number is computed by encoding the
sequence number as a 32-bit integer in big-endian format, and then
computing:
Gap = HKDF-Expand-Label(packet_number_secret,
"QUIC packet sequence gap", sequence, 4)
The output of HKDF-Expand-Label is interpreted as a big-endian
number. "packet_number_secret" is derived from the TLS key exchange,
as described in [QUIC-TLS] Section 5.6.
7.6.2. Address Validation for Migrated Connections
TODO: see issue #161
7.7. Connection Termination
Connections should remain open until they become idle for a pre- Connections should remain open until they become idle for a pre-
negotiated period of time. A QUIC connection, once established, can negotiated period of time. A QUIC connection, once established, can
be terminated in one of three ways: be terminated in one of three ways:
1. Explicit Shutdown: An endpoint sends a CONNECTION_CLOSE frame to 1. Explicit Shutdown: An endpoint sends a CONNECTION_CLOSE frame to
initiate a connection termination. An endpoint may send a GOAWAY initiate a connection termination. An endpoint may send a GOAWAY
frame to the peer prior to a CONNECTION_CLOSE to indicate that frame to the peer prior to a CONNECTION_CLOSE to indicate that
the connection will soon be terminated. A GOAWAY frame signals the connection will soon be terminated. A GOAWAY frame signals
to the peer that any active streams will continue to be to the peer that any active streams will continue to be
processed, but the sender of the GOAWAY will not initiate any processed, but the sender of the GOAWAY will not initiate any
additional streams and will not accept any new incoming streams. additional streams and will not accept any new incoming streams.
On termination of the active streams, a CONNECTION_CLOSE may be On termination of the active streams, a CONNECTION_CLOSE may be
sent. If an endpoint sends a CONNECTION_CLOSE frame while sent. If an endpoint sends a CONNECTION_CLOSE frame while
unterminated streams are active (no FIN bit or RST_STREAM frames unterminated streams are active (no FIN bit or RST_STREAM frames
have been sent or received for one or more streams), then the have been sent or received for one or more streams), then the
peer must assume that the streams were incomplete and were peer must assume that the streams were incomplete and were
abnormally terminated. abnormally terminated.
2. Implicit Shutdown: The default idle timeout for a QUIC connection 2. Implicit Shutdown: The default idle timeout is a required
is 30 seconds, and is a required parameter in connection parameter in connection negotiation. The maximum is 10 minutes.
negotiation. The maximum is 10 minutes. If there is no network If there is no network activity for the duration of the idle
activity for the duration of the idle timeout, the connection is timeout, the connection is closed. By default a CONNECTION_CLOSE
closed. By default a CONNECTION_CLOSE frame will be sent. A frame will be sent. A silent close option can be enabled when it
silent close option can be enabled when it is expensive to send is expensive to send an explicit close, such as mobile networks
an explicit close, such as mobile networks that must wake up the that must wake up the radio.
radio.
3. Abrupt Shutdown: An endpoint may send a Public Reset packet at 3. Abrupt Shutdown: An endpoint may send a Public Reset packet at
any time during the connection to abruptly terminate an active any time during the connection to abruptly terminate an active
connection. A Public Reset packet SHOULD only be used as a final connection. A Public Reset packet SHOULD only be used as a final
recourse. Commonly, a public reset is expected to be sent when a recourse. Commonly, a public reset is expected to be sent when a
packet on an established connection is received by an endpoint packet on an established connection is received by an endpoint
that is unable decrypt the packet. For instance, if a server that is unable decrypt the packet. For instance, if a server
reboots mid-connection and loses any cryptographic state reboots mid-connection and loses any cryptographic state
associated with open connections, and then receives a packet on associated with open connections, and then receives a packet on
an open connection, it should send a Public Reset packet in an open connection, it should send a Public Reset packet in
skipping to change at page 31, line 16 skipping to change at page 35, line 20
As described in Section 6, Regular packets contain one or more As described in Section 6, Regular packets contain one or more
frames. We now describe the various QUIC frame types that can be frames. We now describe the various QUIC frame types that can be
present in a Regular packet. The use of these frames and various present in a Regular packet. The use of these frames and various
frame header bits are described in subsequent sections. frame header bits are described in subsequent sections.
8.1. STREAM Frame 8.1. STREAM Frame
STREAM frames implicitly create a stream and carry stream data. The STREAM frames implicitly create a stream and carry stream data. The
type byte for a STREAM frame contains embedded flags, and is type byte for a STREAM frame contains embedded flags, and is
formatted as "1FDOOOSS". These bits are parsed as follows: formatted as "11FDOOSS". These bits are parsed as follows:
o The leftmost bit must be set to 1, indicating that this is a o The first two bits must be set to 11, indicating that this is a
STREAM frame. STREAM frame.
o "F" is the FIN bit, which is used for stream termination. o "F" is the FIN bit, which is used for stream termination.
o The "D" bit indicates whether a Data Length field is present in o The "D" bit indicates whether a Data Length field is present in
the STREAM header. When set to 0, this field indicates that the the STREAM header. When set to 0, this field indicates that the
Stream Data field extends to the end of the packet. When set to Stream Data field extends to the end of the packet. When set to
1, this field indicates that Data Length field contains the length 1, this field indicates that Data Length field contains the length
(in bytes) of the Stream Data field. The option to omit the (in bytes) of the Stream Data field. The option to omit the
length should only be used when the packet is a "full-sized" length should only be used when the packet is a "full-sized"
packet, to avoid the risk of corruption via padding. packet, to avoid the risk of corruption via padding.
o The "OOO" bits encode the length of the Offset header field as 0, o The "OO" bits encode the length of the Offset header field as 0,
16, 24, 32, 40, 48, 56, or 64 bits long. 16, 32, or 64 bits long.
o The "SS" bits encode the length of the Stream ID header field as o The "SS" bits encode the length of the Stream ID header field as
8, 16, 24, or 32 bits. (DISCUSS: Consider making this 8, 16, 32, 8, 16, 24, or 32 bits.
64.)
A STREAM frame is shown below. A STREAM frame is shown below.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| [Data Length (16)] | | [Data Length (16)] |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Stream ID (8/16/24/32) ... | Stream ID (8/16/24/32) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Offset (0/16/24/32/40/48/56/64) ... | Offset (0/16/32/64) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Stream Data (*) ... | Stream Data (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: STREAM Frame Format Figure 7: STREAM Frame Format
The STREAM frame contains the following fields: The STREAM frame contains the following fields:
Data Length: An optional 16-bit unsigned number specifying the Data Length: An optional 16-bit unsigned number specifying the
length of the Stream Data field in this STREAM frame. This field length of the Stream Data field in this STREAM frame. This field
is present when the "D" bit is set to 1. is present when the "D" bit is set to 1.
Stream ID: A variable-sized unsigned ID unique to this stream. Stream ID: The stream ID of the stream (see Section 10.1).
Offset: A variable-sized unsigned number specifying the byte offset Offset: A variable-sized unsigned number specifying the byte offset
in the stream for the data in this STREAM frame. The first byte in the stream for the data in this STREAM frame. When the offset
in the stream has an offset of 0. The largest offset delivered on length is 0, the offset is 0. The first byte in the stream has an
a stream - the sum of the re-constructed offset and data length - offset of 0. The largest offset delivered on a stream - the sum
MUST be less than 2^64. of the re-constructed offset and data length - MUST be less than
2^64.
Stream Data: The bytes from the designated stream to be delivered. Stream Data: The bytes from the designated stream to be delivered.
A STREAM frame MUST have either non-zero data length or the FIN bit A STREAM frame MUST have either non-zero data length or the FIN bit
set. set. When the FIN flag is sent on an empty STREAM frame, the offset
in the STREAM frame MUST be one greater than the last data byte sent
on this stream.
Stream multiplexing is achieved by interleaving STREAM frames from Stream multiplexing is achieved by interleaving STREAM frames from
multiple streams into one or more QUIC packets. A single QUIC packet multiple streams into one or more QUIC packets. A single QUIC packet
MAY bundle STREAM frames from multiple streams. MAY bundle STREAM frames from multiple streams.
Implementation note: One of the benefits of QUIC is avoidance of Implementation note: One of the benefits of QUIC is avoidance of
head-of-line blocking across multiple streams. When a packet loss head-of-line blocking across multiple streams. When a packet loss
occurs, only streams with data in that packet are blocked waiting for occurs, only streams with data in that packet are blocked waiting for
a retransmission to be received, while other streams can continue a retransmission to be received, while other streams can continue
making progress. Note that when data from multiple streams is making progress. Note that when data from multiple streams is
skipping to change at page 32, line 48 skipping to change at page 37, line 17
8.2. ACK Frame 8.2. ACK Frame
Receivers send ACK frames to inform senders which packets they have Receivers send ACK frames to inform senders which packets they have
received and processed, as well as which packets are considered received and processed, as well as which packets are considered
missing. The ACK frame contains between 1 and 256 ACK blocks. ACK missing. The ACK frame contains between 1 and 256 ACK blocks. ACK
blocks are ranges of acknowledged packets. blocks are ranges of acknowledged packets.
To limit ACK blocks to those that have not yet been received by the To limit ACK blocks to those that have not yet been received by the
sender, the receiver SHOULD track which ACK frames have been sender, the receiver SHOULD track which ACK frames have been
acknowledged by its peer. Once an ACK frame has been acknowledged, acknowledged by its peer. Once an ACK frame has been acknowledged,
the packets it acknowledges SHOULD not be acknowledged again. To the packets it acknowledges SHOULD not be acknowledged again.
handle cases where the receiver is only sending ACK frames, and hence
will not receive acknowledgments for its packets, it MAY send a PING A receiver that is only sending ACK frames will not receive
frame at most once per RTT to explicitly request acknowledgment. acknowledgments for its packets. Sending an occasional MAX_DATA or
MAX_STREAM_DATA frame as data is received will ensure that
acknowledgements are generated by a peer. Otherwise, an endpoint MAY
send a PING frame once per RTT to solicit an acknowledgment.
To limit receiver state or the size of ACK frames, a receiver MAY To limit receiver state or the size of ACK frames, a receiver MAY
limit the number of ACK blocks it sends. A receiver can do this even limit the number of ACK blocks it sends. A receiver can do this even
without receiving acknowledgment of its ACK frames, with the without receiving acknowledgment of its ACK frames, with the
knowledge this could cause the sender to unnecessarily retransmit knowledge this could cause the sender to unnecessarily retransmit
some data. some data. When this is necessary, the receiver SHOULD acknowledge
newly received packets and stop acknowledging packets received in the
past.
Unlike TCP SACKs, QUIC ACK blocks are cumulative and therefore Unlike TCP SACKs, QUIC ACK blocks are cumulative and therefore
irrevocable. Once a packet has been acknowledged, even if it does irrevocable. Once a packet has been acknowledged, even if it does
not appear in a future ACK frame, it is assumed to be acknowledged. not appear in a future ACK frame, it is assumed to be acknowledged.
QUIC ACK frames contain a timestamp section with up to 255 QUIC ACK frames contain a timestamp section with up to 255
timestamps. Timestamps enable better congestion control, but are not timestamps. Timestamps enable better congestion control, but are not
required for correct loss recovery, and old timestamps are less required for correct loss recovery, and old timestamps are less
valuable, so it is not guaranteed every timestamp will be received by valuable, so it is not guaranteed every timestamp will be received by
the sender. A receiver SHOULD send a timestamp exactly once for each the sender. A receiver SHOULD send a timestamp exactly once for each
received packet containing retransmittable frames. A receiver MAY received packet containing retransmittable frames. A receiver MAY
send timestamps for non-retransmittable packets. send timestamps for non-retransmittable packets. A receiver MUST not
send timestamps in unprotected packets.
A sender MAY intentionally skip packet numbers to introduce entropy A sender MAY intentionally skip packet numbers to introduce entropy
into the connection, to avoid opportunistic acknowledgement attacks. into the connection, to avoid opportunistic acknowledgement attacks.
The sender MUST close the connection if an unsent packet number is The sender MUST close the connection if an unsent packet number is
acknowledged. The format of the ACK frame is efficient at expressing acknowledged. The format of the ACK frame is efficient at expressing
blocks of missing packets; skipping packet numbers between 1 and 255 blocks of missing packets; skipping packet numbers between 1 and 255
effectively provides up to 8 bits of efficient entropy on demand, effectively provides up to 8 bits of efficient entropy on demand,
which should be adequate protection against most opportunistic which should be adequate protection against most opportunistic
acknowledgement attacks. acknowledgement attacks.
The type byte for a ACK frame contains embedded flags, and is The type byte for a ACK frame contains embedded flags, and is
formatted as "01NULLMM". These bits are parsed as follows: formatted as "101NLLMM". These bits are parsed as follows:
o The first two bits must be set to 01 indicating that this is an o The first three bits must be set to 101 indicating that this is an
ACK frame. ACK frame.
o The "N" bit indicates whether the frame has more than 1 range of o The "N" bit indicates whether the frame has more than 1 range of
acknowledged packets (i.e., whether the ACK Block Section contains acknowledged packets (i.e., whether the ACK Block Section contains
a Num Blocks field). a Num Blocks field).
o The "U" bit is unused and MUST be set to zero.
o The two "LL" bits encode the length of the Largest Acknowledged o The two "LL" bits encode the length of the Largest Acknowledged
field as 1, 2, 4, or 6 bytes long. field as 1, 2, 4, or 6 bytes long.
o The two "MM" bits encode the length of the ACK Block Length fields o The two "MM" bits encode the length of the ACK Block Length fields
as 1, 2, 4, or 6 bytes long. as 1, 2, 4, or 6 bytes long.
An ACK frame is shown below. An ACK frame is shown below.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
skipping to change at page 38, line 16 skipping to change at page 42, line 26
protection keys. protection keys.
For instance, a server acknowledges a TLS ClientHello in the packet For instance, a server acknowledges a TLS ClientHello in the packet
that carries the TLS ServerHello; similarly, a client can acknowledge that carries the TLS ServerHello; similarly, a client can acknowledge
a TLS HelloRetryRequest in the packet containing a second TLS a TLS HelloRetryRequest in the packet containing a second TLS
ClientHello. The complete set of server handshake messages (TLS ClientHello. The complete set of server handshake messages (TLS
ServerHello through to Finished) might be acknowledged by a client in ServerHello through to Finished) might be acknowledged by a client in
protected packets, because it is certain that the server is able to protected packets, because it is certain that the server is able to
decipher the packet. decipher the packet.
8.3. WINDOW_UPDATE Frame 8.3. MAX_DATA Frame
The WINDOW_UPDATE frame (type=0x04) informs the peer of an increase The MAX_DATA frame (type=0x04) is used in flow control to inform the
in an endpoint's flow control receive window for either a single peer of the maximum amount of data that can be sent on the connection
stream, or the entire connection as a whole. as a whole.
The frame is as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ Maximum Data (64) +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The fields in the MAX_DATA frame are as follows:
Maximum Data: A 64-bit unsigned integer indicating the maximum
amount of data that can be sent on the entire connection, in units
of 1024 octets. That is, the updated connection-level data limit
is determined by multiplying the encoded value by 1024.
All data sent in STREAM frames counts toward this limit, with the
exception of data on stream 0. The sum of the largest received
offsets on all streams - including closed streams, but excluding
stream 0 - MUST NOT exceed the value advertised by a receiver. An
endpoint MUST terminate a connection with a
QUIC_FLOW_CONTROL_RECEIVED_TOO_MUCH_DATA error if it receives more
data than the maximum data value that it has sent, unless this is a
result of a change in the initial limits (see Section 7.3.2).
8.4. MAX_STREAM_DATA Frame
The MAX_STREAM_DATA frame (type=0x05) is used in flow control to
inform a peer of the maximum amount of data that can be sent on a
stream.
The frame is as follows: The frame is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Stream ID (32) | | Stream ID (32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ Flow Control Offset (64) + + Maximum Stream Data (64) +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The fields in the WINDOW_UPDATE frame are as follows: The fields in the MAX_STREAM_DATA frame are as follows:
Stream ID: ID of the stream whose flow control windows is being Stream ID: The stream ID of the stream that is affected.
updated, or 0 to specify the connection-level flow control window.
Flow Control Offset: A 64-bit unsigned integer indicating the flow Maximum Stream Data: A 64-bit unsigned integer indicating the
control offset for the given stream (for a stream ID other than 0) maximum amount of data that can be sent on the identified stream,
or the entire connection. in units of octets.
The flow control offset is expressed in units of octets for When counting data toward this limit, an endpoint accounts for the
individual streams (for stream identifiers other than 0). largest received offset of data that is sent or received on the
stream. Loss or reordering can mean that the largest received offset
on a stream can be greater than the total size of data received on
that stream. Receiving STREAM frames might not increase the largest
received offset.
The connection-level flow control offset is expressed in units of The data sent on a stream MUST NOT exceed the largest maximum stream
1024 octets (for a stream identifier of 0). That is, the connection- data value advertised by the receiver. An endpoint MUST terminate a
level flow control offset is determined by multiplying the encoded connection with a QUIC_FLOW_CONTROL_RECEIVED_TOO_MUCH_DATA error if
value by 1024. it receives more data than the largest maximum stream data that it
has sent for the affected stream, unless this is a result of a change
in the initial limits (see Section 7.3.2).
An endpoint accounts for the maximum offset of data that is sent or 8.5. MAX_STREAM_ID Frame
received on a stream. Loss or reordering can mean that the maximum
offset is greater than the total size of data received on a stream.
Similarly, receiving STREAM frames might not increase the maximum
offset on a stream. A STREAM frame with a FIN bit set or RST_STREAM
causes the final offset for a stream to be fixed.
The maximum data offset on a stream MUST NOT exceed the stream flow The MAX_STREAM_ID frame (type=0x06) informs the peer of the maximum
control offset advertised by the receiver. The sum of the maximum stream ID that they are permitted to open.
data offsets of all streams (including closed streams) MUST NOT
exceed the connection flow control offset advertised by the receiver. The frame is as follows:
An endpoint MUST terminate a connection with a
QUIC_FLOW_CONTROL_RECEIVED_TOO_MUCH_DATA error if it receives more 0 1 2 3
data than the largest flow control offset that it has sent, unless 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
this is a result of a change in the initial offsets (see +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Maximum Stream ID (32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The fields in the MAX_STREAM_ID frame are as follows:
Maximum Stream ID: ID of the maximum peer-initiated stream ID for
the connection.
Loss or reordering can mean that a MAX_STREAM_ID frame can be
received which states a lower stream limit than the client has
previously received. MAX_STREAM_ID frames which do not increase the
maximum stream ID MUST be ignored.
A peer MUST NOT initiate a stream with a higher stream ID than the
greatest maximum stream ID it has received. An endpoint MUST
terminate a connection with a QUIC_TOO_MANY_OPEN_STREAMS error if a
peer initiates a stream with a higher stream ID than it has sent,
unless this is a result of a change in the initial limits (see
Section 7.3.2). Section 7.3.2).
8.4. BLOCKED Frame 8.6. BLOCKED Frame
A sender sends a BLOCKED frame (type=0x05) when it is ready to send A sender sends a BLOCKED frame (type=0x08) when it wishes to send
data (and has data to send), but is currently flow control blocked. data, but is unable to due to connection-level flow control (see
BLOCKED frames are purely informational frames, but extremely useful Section 11.2.1). BLOCKED frames can be used as input to tuning of
for debugging purposes. A receiver of a BLOCKED frame should simply flow control algorithms (see Section 11.1.2).
discard it (after possibly printing a helpful log message). The
frame is as follows: The BLOCKED frame does not contain a payload.
8.7. STREAM_BLOCKED Frame
A sender sends a STREAM_BLOCKED frame (type=0x09) when it wishes to
send data, but is unable to due to stream-level flow control. This
frame is analogous to BLOCKED (Section 8.6).
The STREAM_BLOCKED frame is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Stream ID (32) | | Stream ID (32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The BLOCKED frame contains a single field: The STREAM_BLOCKED frame contains a single field:
Stream ID: A 32-bit unsigned number indicating the stream which is Stream ID: A 32-bit unsigned number indicating the stream which is
flow control blocked. A non-zero Stream ID field specifies the flow control blocked.
stream that is flow control blocked. When zero, the Stream ID
field indicates that the connection is flow control blocked.
8.5. RST_STREAM Frame An endpoint MAY send a STREAM_BLOCKED frame for a stream that exceeds
the maximum stream ID set by its peer (see Section 8.5). This does
not open the stream, but informs the peer that a new stream was
needed, but the stream limit prevented the creation of the stream.
8.8. STREAM_ID_NEEDED Frame
A sender sends a STREAM_ID_NEEDED frame (type=0x0a) when it wishes to
open a stream, but is unable to due to the maximum stream ID limit.
The STREAM_ID_NEEDED frame does not contain a payload.
8.9. RST_STREAM Frame
An endpoint may use a RST_STREAM frame (type=0x01) to abruptly An endpoint may use a RST_STREAM frame (type=0x01) to abruptly
terminate a stream. The frame is as follows: terminate a stream.
After sending a RST_STREAM, an endpoint ceases transmission of STREAM
frames on the identified stream. A receiver of RST_STREAM can
discard any data that it already received on that stream. An
endpoint sends a RST_STREAM in response to a RST_STREAM unless the
stream is already closed.
The RST_STREAM frame is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Error Code (32) | | Error Code (32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Stream ID (32) | | Stream ID (32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ Final Offset (64) + + Final Offset (64) +
skipping to change at page 40, line 16 skipping to change at page 46, line 4
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Error Code (32) | | Error Code (32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Stream ID (32) | | Stream ID (32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+ Final Offset (64) + + Final Offset (64) +
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The fields are: The fields are:
Error code: A 32-bit error code which indicates why the stream is Error code: A 32-bit error code which indicates why the stream is
being closed. being closed.
Stream ID: The 32-bit Stream ID of the stream being terminated. Stream ID: The 32-bit Stream ID of the stream being terminated.
Final offset: A 64-bit unsigned integer indicating the absolute byte Final offset: A 64-bit unsigned integer indicating the absolute byte
offset of the end of data written on this stream by the RST_STREAM offset of the end of data written on this stream by the RST_STREAM
sender. sender.
8.6. PADDING Frame 8.10. PADDING Frame
The PADDING frame (type=0x00) has no semantic value. PADDING frames The PADDING frame (type=0x00) has no semantic value. PADDING frames
can be used to increase the size of a packet. Padding can be used to can be used to increase the size of a packet. Padding can be used to
increase an initial client packet to the minimum required size, or to increase an initial client packet to the minimum required size, or to
provide protection against traffic analysis for protected packets. provide protection against traffic analysis for protected packets.
A PADDING frame has no content. That is, a PADDING frame consists of A PADDING frame has no content. That is, a PADDING frame consists of
the single octet that identifies the frame as a PADDING frame. the single octet that identifies the frame as a PADDING frame.
8.7. PING frame 8.11. PING frame
Endpoints can use PING frames (type=0x07) to verify that their peers Endpoints can use PING frames (type=0x07) to verify that their peers
are still alive or to check reachability to the peer. The PING frame are still alive or to check reachability to the peer. The PING frame
contains no additional fields. The receiver of a PING frame simply contains no additional fields. The receiver of a PING frame simply
needs to acknowledge the packet containing this frame. The PING needs to acknowledge the packet containing this frame. The PING
frame SHOULD be used to keep a connection alive when a stream is frame SHOULD be used to keep a connection alive when a stream is
open. The default is to send a PING frame after 15 seconds of open. The default is to send a PING frame after 15 seconds of
quiescence. A PING frame has no additional fields. quiescence. A PING frame has no additional fields.
8.8. CONNECTION_CLOSE frame 8.12. NEW_CONNECTION_ID Frame
A server sends a NEW_CONNECTION_ID to provide the client with
alternative connection IDs that can be used to break linkability when
migrating connections (see Section 7.6.1).
The NEW_CONNECTION_ID is as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence (16) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ Connection ID (64) +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The fields are:
Sequence: A 16-bit sequence number. This value starts at 0 and
increases by 1 for each connection ID that is provided by the
server. The sequence value can wrap; the value 65535 is followed
by 0. When wrapping the sequence field, the server MUST ensure
that a value with the same sequence has been received and
acknowledged by the client. The connection ID that is assigned
during the handshake is assumed to have a sequence of 65535.
Connection ID: A 64-bit connection ID.
8.13. CONNECTION_CLOSE frame
An endpoint sends a CONNECTION_CLOSE frame (type=0x02) to notify its An endpoint sends a CONNECTION_CLOSE frame (type=0x02) to notify its
peer that the connection is being closed. If there are open streams peer that the connection is being closed. If there are open streams
that haven't been explicitly closed, they are implicitly closed when that haven't been explicitly closed, they are implicitly closed when
the connection is closed. (Ideally, a GOAWAY frame would be sent the connection is closed. (Ideally, a GOAWAY frame would be sent
with enough time that all streams are torn down.) The frame is as with enough time that all streams are torn down.) The frame is as
follows: follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
skipping to change at page 41, line 22 skipping to change at page 47, line 39
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reason Phrase Length (16) | [Reason Phrase (*)] ... | Reason Phrase Length (16) | [Reason Phrase (*)] ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The fields of a CONNECTION_CLOSE frame are as follows: The fields of a CONNECTION_CLOSE frame are as follows:
Error Code: A 32-bit error code which indicates the reason for Error Code: A 32-bit error code which indicates the reason for
closing this connection. closing this connection.
Reason Phrase Length: A 16-bit unsigned number specifying the length Reason Phrase Length: A 16-bit unsigned number specifying the length
of the reason phrase. This may be zero if the sender chooses to of the reason phrase. Note that a CONNECTION_CLOSE frame cannot
not give details beyond the Error Code. be split between packets, so in practice any limits on packet size
will also limit the space available for a reason phrase.
Reason Phrase: An optional human-readable explanation for why the Reason Phrase: A human-readable explanation for why the connection
connection was closed. was closed. This can be zero length if the sender chooses to not
give details beyond the Error Code. This SHOULD be a UTF-8
encoded string [RFC3629].
8.9. GOAWAY Frame 8.14. GOAWAY Frame
An endpoint uses a GOAWAY frame (type=0x03) to initiate a graceful An endpoint uses a GOAWAY frame (type=0x03) to initiate a graceful
shutdown of a connection. The endpoints will continue to use any shutdown of a connection. The endpoints will continue to use any
active streams, but the sender of the GOAWAY will not initiate or active streams, but the sender of the GOAWAY will not initiate or
accept any additional streams beyond those indicated. The GOAWAY accept any additional streams beyond those indicated. The GOAWAY
frame is as follows: frame is as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 42, line 34 skipping to change at page 49, line 9
In addition to initiating a graceful shutdown of a connection, GOAWAY In addition to initiating a graceful shutdown of a connection, GOAWAY
MAY be sent immediately prior to sending a CONNECTION_CLOSE frame MAY be sent immediately prior to sending a CONNECTION_CLOSE frame
that is sent as a result of detecting a fatal error. Higher-numbered that is sent as a result of detecting a fatal error. Higher-numbered
streams than those indicated in the GOAWAY frame can then be retried. streams than those indicated in the GOAWAY frame can then be retried.
9. Packetization and Reliability 9. Packetization and Reliability
The Path Maximum Transmission Unit (PTMU) is the maximum size of the The Path Maximum Transmission Unit (PTMU) is the maximum size of the
entire IP header, UDP header, and UDP payload. The UDP payload entire IP header, UDP header, and UDP payload. The UDP payload
includes the QUIC public header, encrypted payload, and any includes the QUIC public header, protected payload, and any
authentication fields. authentication fields.
All QUIC packets SHOULD be sized to fit within the estimated PMTU to All QUIC packets SHOULD be sized to fit within the estimated PMTU to
avoid IP fragmentation or packet drops. To optimize bandwidth avoid IP fragmentation or packet drops. To optimize bandwidth
efficiency, endpoints SHOULD use Packetization Layer PMTU Discovery efficiency, endpoints SHOULD use Packetization Layer PMTU Discovery
([RFC4821]) and MAY use PMTU Discovery ([RFC1191], [RFC1981]) for ([RFC4821]) and MAY use PMTU Discovery ([RFC1191], [RFC1981]) for
detecting the PMTU, setting the PMTU appropriately, and storing the detecting the PMTU, setting the PMTU appropriately, and storing the
result of previous PMTU determinations. result of previous PMTU determinations.
In the absence of these mechanisms, QUIC endpoints SHOULD NOT send IP In the absence of these mechanisms, QUIC endpoints SHOULD NOT send IP
packets larger than 1280 octets. Assuming the minimum IP header packets larger than 1280 octets. Assuming the minimum IP header
size, this results in a UDP payload length of 1232 octets for IPv6 size, this results in a QUIC packet size of 1232 octets for IPv6 and
and 1252 octets for IPv4. 1252 octets for IPv4.
QUIC endpoints that implement any kind of PMTU discovery SHOULD QUIC endpoints that implement any kind of PMTU discovery SHOULD
maintain an estimate for each combination of local and remote IP maintain an estimate for each combination of local and remote IP
addresses (as each pairing could have a different maximum MTU in the addresses (as each pairing could have a different maximum MTU in the
path). path).
QUIC depends on the network path supporting a MTU of at least 1280 QUIC depends on the network path supporting a MTU of at least 1280
octets. This is the IPv6 minimum and therefore also supported by octets. This is the IPv6 minimum and therefore also supported by
most modern IPv4 networks. An endpoint MUST NOT reduce their MTU most modern IPv4 networks. An endpoint MUST NOT reduce their MTU
below this number, even if it receives signals that indicate a below this number, even if it receives signals that indicate a
smaller limit might exist. smaller limit might exist.
Clients MUST ensure that the first packet in a connection, and any Clients MUST ensure that the first packet in a connection, and any
retransmissions of those octets, has a total size (including IP and retransmissions of those octets, has a QUIC packet size of least 1232
UDP headers) of at least 1280 bytes. This might require inclusion of octets for an IPv6 packet and 1252 octets for an IPv4 packet. In the
PADDING frames. It is RECOMMENDED that a packet be padded to exactly absence of extensions to the IP header, padding to exactly these
1280 octets unless the client has a reasonable assurance that the values will result in an IP packet that is 1280 octets.
PMTU is larger. Sending a packet of this size ensures that the
network path supports an MTU of this size and helps mitigate
amplification attacks caused by server responses toward an unverified
client address.
Servers MUST reject the first plaintext packet received from a client The initial client packet SHOULD be padded to exactly these values
if it its total size is less than 1280 octets, to mitigate unless the client has a reasonable assurance that the PMTU is larger.
amplification attacks. Sending a packet of this size ensures that the network path supports
an MTU of this size and helps reduce the amplitude of amplification
attacks caused by server responses toward an unverified client
address.
Servers MUST ignore an initial plaintext packet from a client if its
total size is less than 1232 octets for IPv6 or 1252 octets for IPv4.
If a QUIC endpoint determines that the PMTU between any pair of local If a QUIC endpoint determines that the PMTU between any pair of local
and remote IP addresses has fallen below 1280 octets, it MUST and remote IP addresses has fallen below 1280 octets, it MUST
immediately cease sending QUIC packets between those IP addresses. immediately cease sending QUIC packets on the affected path. This
This may result in abrupt termination of the connection if all pairs could result in termination of the connection if an alternative path
are affected. In this case, an endpoint SHOULD send a Public Reset cannot be found.
packet to indicate the failure. The application SHOULD attempt to
use TLS over TCP instead.
A sender bundles one or more frames in a Regular QUIC packet (see A sender bundles one or more frames in a Regular QUIC packet (see
Section 6). Section 6).
A sender SHOULD minimize per-packet bandwidth and computational costs A sender SHOULD minimize per-packet bandwidth and computational costs
by bundling as many frames as possible within a QUIC packet. A by bundling as many frames as possible within a QUIC packet. A
sender MAY wait for a short period of time to bundle multiple frames sender MAY wait for a short period of time to bundle multiple frames
before sending a packet that is not maximally packed, to avoid before sending a packet that is not maximally packed, to avoid
sending out large numbers of small packets. An implementation may sending out large numbers of small packets. An implementation may
use heuristics about expected application sending behavior to use heuristics about expected application sending behavior to
skipping to change at page 44, line 42 skipping to change at page 51, line 17
To avoid creating an indefinite feedback loop, an endpoint MUST NOT To avoid creating an indefinite feedback loop, an endpoint MUST NOT
generate an ACK frame in response to a packet containing only ACK or generate an ACK frame in response to a packet containing only ACK or
PADDING frames. PADDING frames.
Strategies and implications of the frequency of generating Strategies and implications of the frequency of generating
acknowledgments are discussed in more detail in [QUIC-RECOVERY]. acknowledgments are discussed in more detail in [QUIC-RECOVERY].
9.1. Special Considerations for PMTU Discovery 9.1. Special Considerations for PMTU Discovery
Traditional ICMP-based path MTU discovery in IPv4 ([RFC1191] is Traditional ICMP-based path MTU discovery in IPv4 [RFC1191] is
potentially vulnerable to off-path attacks that successfully guess potentially vulnerable to off-path attacks that successfully guess
the IP/port 4-tuple and reduce the MTU to a bandwidth-inefficient the IP/port 4-tuple and reduce the MTU to a bandwidth-inefficient
value. TCP connections mitigate this risk by using the (at minimum) value. TCP connections mitigate this risk by using the (at minimum)
8 bytes of transport header echoed in the ICMP message to validate 8 bytes of transport header echoed in the ICMP message to validate
the TCP sequence number as valid for the current connection. the TCP sequence number as valid for the current connection.
However, as QUIC operates over UDP, in IPv4 the echoed information However, as QUIC operates over UDP, in IPv4 the echoed information
could consist only of the IP and UDP headers, which usually has could consist only of the IP and UDP headers, which usually has
insufficient entropy to mitigate off-path attacks. insufficient entropy to mitigate off-path attacks.
As a result, endpoints that implement PMTUD in IPv4 SHOULD take steps As a result, endpoints that implement PMTUD in IPv4 SHOULD take steps
skipping to change at page 45, line 40 skipping to change at page 52, line 15
Data that is received on a stream is delivered in order within that Data that is received on a stream is delivered in order within that
stream, but there is no particular delivery order across streams. stream, but there is no particular delivery order across streams.
Transmit ordering among streams is left to the implementation. Transmit ordering among streams is left to the implementation.
The creation and destruction of streams are expected to have minimal The creation and destruction of streams are expected to have minimal
bandwidth and computational cost. A single STREAM frame may create, bandwidth and computational cost. A single STREAM frame may create,
carry data for, and terminate a stream, or a stream may last the carry data for, and terminate a stream, or a stream may last the
entire duration of a connection. entire duration of a connection.
Streams are individually flow controlled, allowing an endpoint to Streams are individually flow controlled, allowing an endpoint to
limit memory commitment and to apply back pressure. limit memory commitment and to apply back pressure. The creation of
streams is also flow controlled, with each peer declaring the maximum
stream ID it is willing to accept at a given time.
An alternative view of QUIC streams is as an elastic "message" An alternative view of QUIC streams is as an elastic "message"
abstraction, similar to the way ephemeral streams are used in SST abstraction, similar to the way ephemeral streams are used in SST
[SST], which may be a more appealing description for some [SST], which may be a more appealing description for some
applications. applications.
10.1. Life of a Stream 10.1. Stream Identifiers
Streams are identified by an unsigned 32-bit integer, referred to as
the Stream ID. To avoid Stream ID collision, clients initiate
streams using odd-numbered Stream IDs; streams initiated by the
server use even-numbered Stream IDs.
Stream ID 0 (0x0) is reserved for the cryptographic handshake.
Stream 0 MUST NOT be used for application data, and is the first
client-initiated stream.
A QUIC endpoint cannot reuse a Stream ID. Streams MUST be created in
sequential order. Open streams can be used in any order. Streams
that are used out of order result in lower-numbered streams in the
same direction being counted as open.
Stream IDs are usually encoded as a 32-bit integer, though the STREAM
frame (Section 8.1) permits a shorter encoding when the leading bits
of the stream ID are zero.
10.2. Life of a Stream
The semantics of QUIC streams is based on HTTP/2 streams, and the The semantics of QUIC streams is based on HTTP/2 streams, and the
lifecycle of a QUIC stream therefore closely follows that of an lifecycle of a QUIC stream therefore closely follows that of an
HTTP/2 stream [RFC7540], with some differences to accommodate the HTTP/2 stream [RFC7540], with some differences to accommodate the
possibility of out-of-order delivery due to the use of multiple possibility of out-of-order delivery due to the use of multiple
streams in QUIC. The lifecycle of a QUIC stream is shown in the streams in QUIC. The lifecycle of a QUIC stream is shown in the
following figure and described below. following figure and described below.
+--------+ +--------+
| | recv RST | | send RST
| idle | ,-------------| idle |---------------.
| | / | | \
+--------+ | +--------+ |
| | | |
| send data/ | send STREAM / recv STREAM |
| recv data/ | | |
| recv higher stream | v |
| | recv FIN/ +--------+ send FIN/ |
v | recv RST | | send RST |
+--------+ | ,---------| open |-----------. |
recv FIN | | send FIN | / | | \ |
,---------| open |-----------. v v +--------+ v v
/ | | \ +----------+ +----------+
v +--------+ v | half | | half |
+----------+ | +----------+ | closed | | closed |
| half | | | half | | (remote) | | (local) |
| closed | | send RST/ | closed | +----------+ +----------+
| (remote) | | recv RST | (local) | | |
+----------+ | +----------+ | send FIN/ +--------+ recv FIN/ |
| | | \ send RST | | recv RST /
| send FIN/ | recv FIN/ | `----------->| closed |<-------------'
| send RST/ v send RST/ |
| recv RST +--------+ recv RST |
`------------->| |<---------------'
| closed |
| | | |
+--------+ +--------+
send: endpoint sends this frame send: endpoint sends this frame
recv: endpoint receives this frame recv: endpoint receives this frame
data: application data in a STREAM frame STREAM: a STREAM frame
FIN: FIN flag in a STREAM frame FIN: FIN flag in a STREAM frame
RST: RST_STREAM frame RST: RST_STREAM frame
Figure 11: Lifecycle of a stream Figure 11: Lifecycle of a stream
Note that this diagram shows stream state transitions and the frames Note that this diagram shows stream state transitions and the frames
and flags that affect those transitions only. For the purpose of and flags that affect those transitions only. For the purpose of
state transitions, the FIN flag is processed as a separate event to state transitions, the FIN flag is processed as a separate event to
the frame that bears it; a STREAM frame with the FIN flag set can the frame that bears it; a STREAM frame with the FIN flag set can
cause two state transitions. When the FIN flag is sent on an empty cause two state transitions.
STREAM frame, the offset in the STREAM frame MUST be one greater than
the last data byte sent on this stream.
The recipient of a frame which changes stream state will have a The recipient of a frame which changes stream state will have a
delayed view of the state of a stream while the frame is in transit. delayed view of the state of a stream while the frame is in transit.
Endpoints do not coordinate the creation of streams; they are created Endpoints do not coordinate the creation of streams; they are created
unilaterally by either endpoint. The negative consequences of a unilaterally by either endpoint. Endpoints can use acknowledgments
mismatch in states are limited to the "closed" state after sending to understand the peer's subjective view of stream state at any given
RST_STREAM, where frames might be received for some time after time.
closing. Endpoints can use acknowledgments to understand the peer's
subjective view of stream state at any given time.
Streams have the following states: In the absence of more specific guidance elsewhere in this document,
implementations SHOULD treat the receipt of a frame that is not
expressly permitted in the description of a state as a connection
error (see Section 12).
10.1.1. idle 10.2.1. idle
All streams start in the "idle" state. All streams start in the "idle" state.
The following transitions are valid from this state: The following transitions are valid from this state:
Sending or receiving a STREAM frame causes the stream to become Sending or receiving a STREAM frame causes the identified stream to
"open". The stream identifier is selected as described in become "open". The stream identifier for a new stream is selected as
Section 10.2. The same STREAM frame can also cause a stream to described in Section 10.1. The same STREAM frame can also cause a
immediately become "half-closed". stream to immediately become "half-closed" if the FIN flag is set.
Receiving a STREAM frame on a peer-initiated stream (that is, a Receiving a STREAM frame on a peer-initiated stream (that is, a
packet sent by a server on an even-numbered stream or a client packet packet sent by a server on an even-numbered stream or a client packet
on an odd-numbered stream) also causes all lower-numbered "idle" on an odd-numbered stream) also causes all lower-numbered "idle"
streams in the same direction to become "open". This could occur if streams in the same direction to become "open". This could occur if
a peer begins sending on streams in a different order to their a peer begins sending on streams in a different order to their
creation, or it could happen if packets are lost or reordered in creation, or it could happen if packets are lost or reordered in
transit. transit.
Receiving any frame other than STREAM or RST_STREAM on a stream in A RST_STREAM frame on an "idle" stream causes the stream to become
this state MUST be treated as a connection error (Section 12) of type "half-closed". Sending a RST_STREAM frame causes the stream to
YYYY. become "half-closed (local)"; receiving RST_STREAM causes the stream
to become "half-closed (remote)".
10.1.2. open An endpoint might receive MAX_STREAM_DATA frames on peer-initiated
streams that are "idle" if there is loss or reordering of packets.
Receiving any frame other than STREAM, MAX_STREAM_DATA,
STREAM_BLOCKED, or RST_STREAM on a stream in this state MUST be
treated as a connection error (Section 12) of type YYYY.
An endpoint MUST NOT send a STREAM or RST_STREAM frame for a stream
ID that is higher than the peers advertised maximum stream ID (see
Section 8.5).
10.2.2. open
A stream in the "open" state may be used by both peers to send frames A stream in the "open" state may be used by both peers to send frames
of any type. In this state, a sending peer must observe the flow- of any type. In this state, endpoints can send MAX_STREAM_DATA and
control limit advertised by its receiving peer (Section 11). MUST observe the value advertised by its receiving peer (see
Section 11).
From this state, either endpoint can send a frame with the FIN flag From this state, either endpoint can send a frame with the FIN flag
set, which causes the stream to transition into one of the "half- set, which causes the stream to transition into one of the "half-
closed" states. An endpoint sending an FIN flag causes the stream closed" states. An endpoint sending an FIN flag causes the stream
state to become "half-closed (local)". An endpoint receiving a FIN state to become "half-closed (local)". An endpoint receiving a FIN
flag causes the stream state to become "half-closed (remote)" once flag causes the stream state to become "half-closed (remote)" once
all preceding data has arrived. The receiving endpoint MUST NOT all preceding data has arrived. The receiving endpoint MUST NOT
consider the stream state to have changed until all data has arrived. consider the stream state to have changed until all data has arrived.
Either endpoint can send a RST_STREAM frame from this state, causing A RST_STREAM frame on an "open" stream causes the stream to become
it to transition immediately to "closed". "half-closed". Sending a RST_STREAM frame causes the stream to
become "half-closed (local)"; receiving RST_STREAM causes the stream
to become "half-closed (remote)".
10.1.3. half-closed (local) Any frame type that mentions a stream ID can be sent in this state.
A stream that is in the "half-closed (local)" state MUST NOT be used 10.2.3. half-closed (local)
for sending STREAM frames; WINDOW_UPDATE and RST_STREAM MAY be sent
in this state.
A stream transitions from this state to "closed" when a STREAM frame A stream that is in the "half-closed (local)" state MUST NOT be used
that contains a FIN flag is received and all prior data has arrived, for sending on new STREAM frames. Retransmission of data that has
or when either peer sends a RST_STREAM frame. already been sent on STREAM frames is permitted. An endpoint MAY
also send MAX_STREAM_DATA and RST_STREAM in this state.
An endpoint that closes a stream MUST NOT send data beyond the final An endpoint that closes a stream MUST NOT send data beyond the final
offset that it has chosen, see Section 10.1.5 for details. offset that it has chosen, see Section 10.2.5 for details.
An endpoint can receive any type of frame in this state. Providing
flow-control credit using WINDOW_UPDATE frames is necessary to
continue receiving flow-controlled frames. In this state, a receiver
MAY ignore WINDOW_UPDATE frames for this stream, which might arrive
for a short period after a frame bearing the FIN flag is sent.
10.1.4. half-closed (remote)
A stream that is "half-closed (remote)" is no longer being used by
the peer to send any data. In this state, a sender is no longer
obligated to maintain a receiver stream-level flow-control window.
A stream that is in the "half-closed (remote)" state will have a
final offset for received data, see Section 10.1.5 for details.
A stream in this state can be used by the endpoint to send frames of
any type. In this state, the endpoint continues to observe
advertised stream-level and connection-level flow-control limits
(Section 11).
A stream can transition from this state to "closed" by sending a
frame that contains a FIN flag or when either peer sends a RST_STREAM
frame.
10.1.5. closed A stream transitions from this state to "closed" when a STREAM frame
that contains a FIN flag is received and all prior data has arrived,
or when a RST_STREAM frame is received.
The "closed" state is the terminal state. An endpoint can receive any frame that mentions a stream ID in this
state. Providing flow-control credit using MAX_STREAM_DATA frames is
necessary to continue receiving flow-controlled frames. In this
state, a receiver MAY ignore MAX_STREAM_DATA frames for this stream,
which might arrive for a short period after a frame bearing the FIN
flag is sent.
An endpoint will learn the final offset of the data it receives on a 10.2.4. half-closed (remote)
stream when it enters the "half-closed (remote)" or "closed" state.
The final offset is carried explicitly in the RST_STREAM frame;
otherwise, the final offset is the offset of the end of the data
carried in STREAM frame marked with a FIN flag.
An endpoint MUST NOT send data on a stream at or beyond the final A stream is "half-closed (remote)" when the stream is no longer being
offset. used by the peer to send any data. An endpoint will have either
received all data that a peer has sent or will have received a
RST_STREAM frame and discarded any received data.
Once a final offset for a stream is known, it cannot change. If a Once all data has been either received or discarded, a sender is no
RST_STREAM or STREAM frame causes the final offset to change for a longer obligated to update the maximum received data for the
stream, an endpoint SHOULD respond with a connection.
QUIC_STREAM_DATA_AFTER_TERMINATION error (see Section 12). A
receiver SHOULD treat receipt of data at or beyond the final offset
as a QUIC_STREAM_DATA_AFTER_TERMINATION error. Generating these
errors is not mandatory, but only because requiring that an endpoint
generate these errors also means that the endpoint needs to maintain
the final offset state for closed streams, which could mean a
significant state commitment.
An endpoint that receives a RST_STREAM frame (and which has not sent An endpoint that receives a RST_STREAM frame (and which has not sent
a FIN or a RST_STREAM) MUST immediately respond with a RST_STREAM a FIN or a RST_STREAM) MUST immediately respond with a RST_STREAM
frame, and MUST NOT send any more data on the stream. This endpoint frame, and MUST NOT send any more data on the stream.
may continue receiving frames for the stream on which a RST_STREAM is
received.
If this state is reached as a result of sending a RST_STREAM frame,
the peer that receives the RST_STREAM frame might have already sent -
or enqueued for sending - frames on the stream that cannot be
withdrawn. An endpoint MUST ignore frames that it receives on closed
streams after it has sent a RST_STREAM frame. An endpoint MAY choose
to limit the period over which it ignores frames and treat frames
that arrive after this time as being in error.
STREAM frames received after sending RST_STREAM are counted toward
the connection and stream flow-control windows. Even though these
frames might be ignored, because they are sent before their sender
receives the RST_STREAM, the sender will consider the frames to count
against its flow-control windows.
In the absence of more specific guidance elsewhere in this document, Due to reordering, an endpoint could continue receiving frames for
implementations SHOULD treat the receipt of a frame that is not the stream even after the stream is closed for sending. Frames
expressly permitted in the description of a state as a connection received after a peer closes a stream SHOULD be discarded. An
error (Section 12). Frames of unknown types are ignored. endpoint MAY choose to limit the period over which it ignores frames
and treat frames that arrive after this time as being in error.
(TODO: QUIC_STREAM_NO_ERROR is a special case. Write it up.) An endpoint will know the final offset of the data it receives on a
stream when it reaches the "half-closed (remote)" state, see
Section 11.3 for details.
10.2. Stream Identifiers A stream in this state can be used by the endpoint to send any frame
that mentions a stream ID. In this state, the endpoint MUST observe
advertised stream and connection data limits (see Section 11).
Streams are identified by an unsigned 32-bit integer, referred to as A stream can transition from this state to "closed" by completing
the StreamID. To avoid StreamID collision, clients MUST initiate transmission of all data. This includes sending all data carried in
streams usinge odd-numbered StreamIDs; streams initiated by the STREAM frames up including the terminal STREAM frame that contains a
server MUST use even-numbered StreamIDs. FIN flag and receiving acknowledgment from the peer for all data.
A StreamID of zero (0x0) is reserved and used for connection-level A stream becomes "closed" when the endpoint sends and receives
flow control frames (Section 11); the StreamID of zero cannot be used acknowledgment of a RST_STREAM frame.
to establish a new stream.
StreamID 1 (0x1) is reserved for the cryptographic handshake. 10.2.5. closed
StreamID 1 MUST NOT be used for application data, and MUST be the
first client-initiated stream.
A QUIC endpoint cannot reuse a StreamID on a given connection. The "closed" state is the terminal state for a stream.
Streams MUST be created in sequential order. Open streams can be
used in any order. Streams that are used out of order result in
lower-numbered streams in the same direction being counted as open.
All streams, including stream 1, count toward this limit. Thus, a Once a stream reaches this state, no frames can be sent that mention
concurrent stream limit of 0 will cause a connection to be unusable. the stream. Reordering might cause frames to be received after
Application protocols that use QUIC might require a certain minimum closing, see Section 10.2.4.
number of streams to function correctly. If a peer advertises an
concurrent stream limit (concurrent_streams) that is too small for
the selected application protocol to function, an endpoint MUST
terminate the connection with an error of type
QUIC_TOO_MANY_OPEN_STREAMS (Section 12).
10.3. Stream Concurrency 10.3. Stream Concurrency
An endpoint limits the number of concurrently active incoming streams An endpoint limits the number of concurrently active incoming streams
by setting the concurrent stream limit (see Section 7.3.1) in the by adjusting the maximum stream ID. An initial value is set in the
transport parameters. The maximum concurrent streams setting is transport parameters (see Section 7.3.1) and is subsequently
specific to each endpoint and applies only to the peer that receives increased by MAX_STREAM_ID frames (see Section 8.5).
the setting. That is, clients specify the maximum number of
concurrent streams the server can initiate, and servers specify the
maximum number of concurrent streams the client can initiate.
Streams that are in the "open" state or in either of the "half-
closed" states count toward the maximum number of streams that an
endpoint is permitted to open. Streams in any of these three states
count toward the limit advertised in the concurrent stream limit.
A recently closed stream MUST also be considered to count toward this The maximum stream ID is specific to each endpoint and applies only
limit until packets containing all frames required to close the to the peer that receives the setting. That is, clients specify the
stream have been acknowledged. For a stream which closed cleanly, maximum stream ID the server can initiate, and servers specify the
this means all STREAM frames have been acknowledged; for a stream maximum stream ID the client can initiate. Each endpoint may respond
which closed abruptly, this means the RST_STREAM frame has been on streams initiated by the other peer, regardless of whether it is
acknowledged. permitted to initiated new streams.
Endpoints MUST NOT exceed the limit set by their peer. An endpoint Endpoints MUST NOT exceed the limit set by their peer. An endpoint
that receives a STREAM frame that causes its advertised concurrent that receives a STREAM frame with an ID greater than the limit it has
stream limit to be exceeded MUST treat this as a stream error of type sent MUST treat this as a stream error of type
QUIC_TOO_MANY_OPEN_STREAMS (Section 12). QUIC_TOO_MANY_OPEN_STREAMS (Section 12), unless this is a result of a
change in the initial offsets (see Section 7.3.2).
A receiver MUST NOT renege on an advertisement; that is, once a
receiver advertises a stream ID via a MAX_STREAM_ID frame, it MUST
NOT subsequently advertise a smaller maximum ID. A sender may
receive MAX_STREAM_ID frames out of order; a sender MUST therefore
ignore any MAX_STREAM_ID that does not increase the maximum.
10.4. Sending and Receiving Data 10.4. Sending and Receiving Data
Once a stream is created, endpoints may use the stream to send and Once a stream is created, endpoints may use the stream to send and
receive data. Each endpoint may send a series of STREAM frames receive data. Each endpoint may send a series of STREAM frames
encapsulating data on a stream until the stream is terminated in that encapsulating data on a stream until the stream is terminated in that
direction. Streams are an ordered byte-stream abstraction, and they direction. Streams are an ordered byte-stream abstraction, and they
have no other structure within them. STREAM frame boundaries are not have no other structure within them. STREAM frame boundaries are not
expected to be preserved in retransmissions from the sender or during expected to be preserved in retransmissions from the sender or during
delivery to the application at the receiver. delivery to the application at the receiver.
skipping to change at page 51, line 32 skipping to change at page 57, line 37
When new data is to be sent on a stream, a sender MUST set the When new data is to be sent on a stream, a sender MUST set the
encapsulating STREAM frame's offset field to the stream offset of the encapsulating STREAM frame's offset field to the stream offset of the
first byte of this new data. The first byte of data that is sent on first byte of this new data. The first byte of data that is sent on
a stream has the stream offset 0. The largest offset delivered on a a stream has the stream offset 0. The largest offset delivered on a
stream MUST be less than 2^64. A receiver MUST ensure that received stream MUST be less than 2^64. A receiver MUST ensure that received
stream data is delivered to the application as an ordered byte- stream data is delivered to the application as an ordered byte-
stream. Data received out of order MUST be buffered for later stream. Data received out of order MUST be buffered for later
delivery, as long as it is not in violation of the receiver's flow delivery, as long as it is not in violation of the receiver's flow
control limits. control limits.
The cryptographic handshake stream, Stream 1, MUST NOT be subject to An endpoint MUST NOT send data on any stream without ensuring that it
congestion control or connection-level flow control, but MUST be is within the data limits set by its peer. The cryptographic
subject to stream-level flow control. An endpoint MUST NOT send data handshake stream, Stream 0, is exempt from the connection-level data
on any other stream without consulting the congestion controller and limits established by MAX_DATA. Stream 0 is still subject to stream-
the flow controller. level data limits and MAX_STREAM_DATA.
Flow control is described in detail in Section 11, and congestion Flow control is described in detail in Section 11, and congestion
control is described in the companion document [QUIC-RECOVERY]. control is described in the companion document [QUIC-RECOVERY].
10.5. Stream Prioritization 10.5. Stream Prioritization
Stream multiplexing has a significant effect on application Stream multiplexing has a significant effect on application
performance if resources allocated to streams are correctly performance if resources allocated to streams are correctly
prioritized. Experience with other multiplexed protocols, such as prioritized. Experience with other multiplexed protocols, such as
HTTP/2 [RFC7540], shows that effective prioritization strategies have HTTP/2 [RFC7540], shows that effective prioritization strategies have
a significant positive impact on performance. a significant positive impact on performance.
QUIC does not provide frames for exchanging priotization information. QUIC does not provide frames for exchanging prioritization
Instead it relies on receiving priority information from the information. Instead it relies on receiving priority information
application that uses QUIC. Protocols that use QUIC are able to from the application that uses QUIC. Protocols that use QUIC are
define any prioritization scheme that suits their application able to define any prioritization scheme that suits their application
semantics. A protocol might define explicit messages for signaling semantics. A protocol might define explicit messages for signaling
priority, such as those defined in HTTP/2; it could define rules that priority, such as those defined in HTTP/2; it could define rules that
allow an endpoint to determine priority based on context; or it could allow an endpoint to determine priority based on context; or it could
leave the determination to the application. leave the determination to the application.
A QUIC implementation SHOULD provide ways in which an application can A QUIC implementation SHOULD provide ways in which an application can
indicate the relative priority of streams. When deciding which indicate the relative priority of streams. When deciding which
streams to dedicate resources to, QUIC SHOULD use the information streams to dedicate resources to, QUIC SHOULD use the information
provided by the application. Failure to account for priority of provided by the application. Failure to account for priority of
streams can result in suboptimal performance. streams can result in suboptimal performance.
skipping to change at page 52, line 26 skipping to change at page 58, line 30
Stream priority is most relevant when deciding which stream data will Stream priority is most relevant when deciding which stream data will
be transmitted. Often, there will be limits on what can be be transmitted. Often, there will be limits on what can be
transmitted as a result of connection flow control or the current transmitted as a result of connection flow control or the current
congestion controller state. congestion controller state.
Giving preference to the transmission of its own management frames Giving preference to the transmission of its own management frames
ensures that the protocol functions efficiently. That is, ensures that the protocol functions efficiently. That is,
prioritizing frames other than STREAM frames ensures that loss prioritizing frames other than STREAM frames ensures that loss
recovery, congestion control, and flow control operate effectively. recovery, congestion control, and flow control operate effectively.
Stream 1 MUST be prioritized over other streams prior to the Stream 0 MUST be prioritized over other streams prior to the
completion of the cryptographic handshake. This includes the completion of the cryptographic handshake. This includes the
retransmission of the second flight of client handshake messages, retransmission of the second flight of client handshake messages,
that is, the TLS Finished and any client authentication messages. that is, the TLS Finished and any client authentication messages.
STREAM frames that are determined to be lost SHOULD be retransmitted STREAM frames that are determined to be lost SHOULD be retransmitted
before sending new data, unless application priorities indicate before sending new data, unless application priorities indicate
otherwise. Retransmitting lost STREAM frames can fill in gaps, which otherwise. Retransmitting lost STREAM frames can fill in gaps, which
allows the peer to consume already received data and free up flow allows the peer to consume already received data and free up flow
control window. control window.
skipping to change at page 53, line 7 skipping to change at page 59, line 9
QUIC employs a credit-based flow-control scheme similar to HTTP/2's QUIC employs a credit-based flow-control scheme similar to HTTP/2's
flow control [RFC7540]. A receiver advertises the number of octets flow control [RFC7540]. A receiver advertises the number of octets
it is prepared to receive on a given stream and for the entire it is prepared to receive on a given stream and for the entire
connection. This leads to two levels of flow control in QUIC: (i) connection. This leads to two levels of flow control in QUIC: (i)
Connection flow control, which prevents senders from exceeding a Connection flow control, which prevents senders from exceeding a
receiver's buffer capacity for the connection, and (ii) Stream flow receiver's buffer capacity for the connection, and (ii) Stream flow
control, which prevents a single stream from consuming the entire control, which prevents a single stream from consuming the entire
receive buffer for a connection. receive buffer for a connection.
A receiver sends WINDOW_UPDATE frames to the sender to advertise A receiver sends MAX_DATA or MAX_STREAM_DATA frames to the sender to
additional credit by sending the absolute byte offset in the stream advertise additional credit by sending the absolute byte offset in
or in the connection which it is willing to receive. the connection or stream which it is willing to receive.
The initial flow control credit is 65536 bytes for both the stream
and connection flow controllers.
A receiver MAY advertise a larger offset at any point in the A receiver MAY advertise a larger offset at any point by sending
connection by sending a WINDOW_UPDATE frame. A receiver MUST NOT MAX_DATA or MAX_STREAM_DATA frames. A receiver MUST NOT renege on an
renege on an advertisement; that is, once a receiver advertises an advertisement; that is, once a receiver advertises an offset, it MUST
offset via a WINDOW_UPDATE frame, it MUST NOT subsequently advertise NOT subsequently advertise a smaller offset. A sender could receive
a smaller offset. A sender may receive WINDOW_UPDATE frames out of MAX_DATA or MAX_STREAM_DATA frames out of order; a sender MUST
order; a sender MUST therefore ignore any WINDOW_UPDATE that does not therefore ignore any flow control offset that does not move the
move the window forward. window forward.
A receiver MUST close the connection with a A receiver MUST close the connection with a
QUIC_FLOW_CONTROL_RECEIVED_TOO_MUCH_DATA error (Section 12) if the QUIC_FLOW_CONTROL_RECEIVED_TOO_MUCH_DATA error (Section 12) if the
peer violates the advertised stream or connection flow control peer violates the advertised connection or stream data limits.
windows.
A sender MUST send BLOCKED frames to indicate it has data to write A sender MUST send BLOCKED frames to indicate it has data to write
but is blocked by lack of connection or stream flow control credit. but is blocked by lack of connection or stream flow control credit.
BLOCKED frames are expected to be sent infrequently in common cases, BLOCKED frames are expected to be sent infrequently in common cases,
but they are considered useful for debugging and monitoring purposes. but they are considered useful for debugging and monitoring purposes.
A receiver advertises credit for a stream by sending a WINDOW_UPDATE A receiver advertises credit for a stream by sending a
frame with the StreamID set appropriately. A receiver may use the MAX_STREAM_DATA frame with the Stream ID set appropriately. A
current offset of data consumed to determine the flow control offset receiver could use the current offset of data consumed to determine
to be advertised. A receiver MAY send copies of a WINDOW_UPDATE the flow control offset to be advertised. A receiver MAY send
frame in multiple packets in order to make sure that the sender MAX_STREAM_DATA frames in multiple packets in order to make sure that
receives it before running out of flow control credit, even if one of the sender receives an update before running out of flow control
the packets is lost. credit, even if one of the packets is lost.
Connection flow control is a limit to the total bytes of stream data Connection flow control is a limit to the total bytes of stream data
sent in STREAM frames on all streams contributing to connection flow sent in STREAM frames on all streams. A receiver advertises credit
control. A receiver advertises credit for a connection by sending a for a connection by sending a MAX_DATA frame. A receiver maintains a
WINDOW_UPDATE frame with the StreamID set to zero (0x00). A receiver cumulative sum of bytes received on all streams, which are used to
maintains a cumulative sum of bytes received on all streams check for flow control violations. A receiver might use a sum of
contributing to connection-level flow control, to check for flow bytes consumed on all contributing streams to determine the maximum
control violations. A receiver may maintain a cumulative sum of data limit to be advertised.
bytes consumed on all contributing streams to determine the
connection-level flow control offset to be advertised.
11.1. Edge Cases and Other Considerations 11.1. Edge Cases and Other Considerations
There are some edge cases which must be considered when dealing with There are some edge cases which must be considered when dealing with
stream and connection level flow control. Given enough time, both stream and connection level flow control. Given enough time, both
endpoints must agree on flow control state. If one end believes it endpoints must agree on flow control state. If one end believes it
can send more than the other end is willing to receive, the can send more than the other end is willing to receive, the
connection will be torn down when too much data arrives. Conversely connection will be torn down when too much data arrives.
if a sender believes it is blocked, while endpoint B expects more
data can be received, then the connection can be in a deadlock, with
the sender waiting for a WINDOW_UPDATE which will never come.
11.1.1. Mid-stream RST_STREAM Conversely if a sender believes it is blocked, while endpoint B
expects more data can be received, then the connection can be in a
deadlock, with the sender waiting for a MAX_DATA or MAX_STREAM_DATA
frame which will never come.
On receipt of a RST_STREAM frame, an endpoint will tear down state On receipt of a RST_STREAM frame, an endpoint will tear down state
for the matching stream and ignore further data arriving on that for the matching stream and ignore further data arriving on that
stream. This could result in the endpoints getting out of sync, stream. This could result in the endpoints getting out of sync,
since the RST_STREAM frame may have arrived out of order and there since the RST_STREAM frame may have arrived out of order and there
may be further bytes in flight. The data sender would have counted may be further bytes in flight. The data sender would have counted
the data against its connection level flow control budget, but a the data against its connection level flow control budget, but a
receiver that has not received these bytes would not know to include receiver that has not received these bytes would not know to include
them as well. The receiver must learn the number of bytes that were them as well. The receiver must learn the number of bytes that were
sent on the stream to make the same adjustment in its connection flow sent on the stream to make the same adjustment in its connection flow
controller. controller.
To avoid this de-synchronization, a RST_STREAM sender MUST include To avoid this de-synchronization, a RST_STREAM sender MUST include
the final byte offset sent on the stream in the RST_STREAM frame. On the final byte offset sent on the stream in the RST_STREAM frame. On
receiving a RST_STREAM frame, a receiver definitively knows how many receiving a RST_STREAM frame, a receiver definitively knows how many
bytes were sent on that stream before the RST_STREAM frame, and the bytes were sent on that stream before the RST_STREAM frame, and the
receiver MUST use the final offset to account for all bytes sent on receiver MUST use the final offset to account for all bytes sent on
the stream in its connection level flow controller. the stream in its connection level flow controller.
11.1.2. Response to a RST_STREAM 11.1.1. Response to a RST_STREAM
Since streams are bidirectional, a sender of a RST_STREAM needs to Since streams are bidirectional, a sender of a RST_STREAM needs to
know how many bytes the peer has sent on the stream. If an endpoint know how many bytes the peer has sent on the stream. If an endpoint
receives a RST_STREAM frame and has sent neither a FIN nor a receives a RST_STREAM frame and has sent neither a FIN nor a
RST_STREAM, it MUST send a RST_STREAM in response, bearing the offset RST_STREAM, it MUST send a RST_STREAM in response, bearing the offset
of the last byte sent on this stream as the final offset. of the last byte sent on this stream as the final offset.
11.1.3. Offset Increment 11.1.2. Data Limit Increments
This document leaves when and how many bytes to advertise in a This document leaves when and how many bytes to advertise in a
WINDOW_UPDATE to the implementation, but offers a few considerations. MAX_DATA or MAX_STREAM_DATA to implementations, but offers a few
WINDOW_UPDATE frames constitute overhead, and therefore, sending a considerations. These frames contribute to connection overhead.
WINDOW_UPDATE with small offset increments is undesirable. At the Therefore frequently sending frames with small changes is
same time, sending WINDOW_UPDATES with large offset increments undesirable. At the same time, infrequent updates require larger
requires the sender to commit to that amount of buffer. increments to limits if blocking is to be avoided. Thus, larger
updates require a receiver to commit to larger resource commitments.
Thus there is a tradeoff between resource commitment and overhead
when determining how large a limit is advertised.
Implementations must find the correct tradeoff between these sides to A receiver MAY use an autotuning mechanism to tune the frequency and
determine how large an offset increment to send in a WINDOW_UPDATE. amount that it increases data limits based on a roundtrip time
estimate and the rate at which the receiving application consumes
data, similar to common TCP implementations.
A receiver MAY use an autotuning mechanism to tune the size of the 11.2. Stream Limit Increment
offset increment to advertise based on a roundtrip time estimate and
the rate at which the receiving application consumes data, similar to
common TCP implementations.
11.1.4. BLOCKED frames As with flow control, this document leaves when and how many streams
to make available to a peer via MAX_STREAM_ID to implementations, but
offers a few considerations. MAX_STREAM_ID frames constitute minimal
overhead, while withholding MAX_STREAM_ID frames can prevent the peer
from using the available parallelism.
If a sender does not receive a WINDOW_UPDATE frame when it has run Implementations will likely want to increase the maximum stream ID as
out of flow control credit, the sender will be blocked and MUST send peer-initiated streams close. A receiver MAY also advance the
a BLOCKED frame. A BLOCKED frame is expected to be useful for maximum stream ID based on current activity, system conditions, and
debugging at the receiver. A receiver SHOULD NOT wait for a BLOCKED other environmental factors.
frame before sending a WINDOW_UPDATE, since doing so will cause at
least one roundtrip of quiescence. For smooth operation of the 11.2.1. Blocking on Flow Control
congestion controller, it is generally considered best to not let the
sender go into quiescence if avoidable. To avoid blocking a sender, If a sender does not receive a MAX_DATA or MAX_STREAM_DATA frame when
and to reasonably account for the possibiity of loss, a receiver it has run out of flow control credit, the sender will be blocked and
should send a WINDOW_UPDATE frame at least two roundtrips before it MUST send a BLOCKED or STREAM_BLOCKED frame. These frames are
expects the sender to get blocked. expected to be useful for debugging at the receiver; they do not
require any other action. A receiver SHOULD NOT wait for a BLOCKED
or STREAM_BLOCKED frame before sending MAX_DATA or MAX_STREAM_DATA,
since doing so will mean that a sender is unable to send for an
entire round trip.
For smooth operation of the congestion controller, it is generally
considered best to not let the sender go into quiescence if
avoidable. To avoid blocking a sender, and to reasonably account for
the possibiity of loss, a receiver should send a MAX_DATA or
MAX_STREAM_DATA frame at least two roundtrips before it expects the
sender to get blocked.
A sender sends a single BLOCKED or STREAM_BLOCKED frame only once
when it reaches a data limit. A sender MUST NOT send multiple
BLOCKED or STREAM_BLOCKED frames for the same data limit, unless the
original frame is determined to be lost. Another BLOCKED or
STREAM_BLOCKED frame can be sent after the data limit is increased.
11.3. Stream Final Offset
The final offset is the count of the number of octets that are
transmitted on a stream. For a stream that is reset, the final
offset is carried explicitly in the RST_STREAM frame. Otherwise, the
final offset is the offset of the end of the data carried in STREAM
frame marked with a FIN flag.
An endpoint will know the final offset for a stream when the stream
enters the "half-closed (remote)" state. However, if there is
reordering or loss, an endpoint might learn the final offset prior to
entering this state if it is carried on a STREAM frame.
An endpoint MUST NOT send data on a stream at or beyond the final
offset.
Once a final offset for a stream is known, it cannot change. If a
RST_STREAM or STREAM frame causes the final offset to change for a
stream, an endpoint SHOULD respond with a
QUIC_STREAM_DATA_AFTER_TERMINATION error (see Section 12). A
receiver SHOULD treat receipt of data at or beyond the final offset
as a QUIC_STREAM_DATA_AFTER_TERMINATION error, even after a stream is
closed. Generating these errors is not mandatory, but only because
requiring that an endpoint generate these errors also means that the
endpoint needs to maintain the final offset state for closed streams,
which could mean a significant state commitment.
12. Error Handling 12. Error Handling
An endpoint that detects an error SHOULD signal the existence of that An endpoint that detects an error SHOULD signal the existence of that
error to its peer. Errors can affect an entire connection (see error to its peer. Errors can affect an entire connection (see
Section 12.1), or a single stream (see Section 12.2). Section 12.1), or a single stream (see Section 12.2).
The most appropriate error code (Section 12.3) SHOULD be included in The most appropriate error code (Section 12.3) SHOULD be included in
the frame that signals the error. Where this specification the frame that signals the error. Where this specification
identifies error conditions, it also identifies the error code that identifies error conditions, it also identifies the error code that
skipping to change at page 55, line 48 skipping to change at page 62, line 45
Public Reset is not suitable for any error that can be signaled with Public Reset is not suitable for any error that can be signaled with
a CONNECTION_CLOSE or RST_STREAM frame. Public Reset MUST NOT be a CONNECTION_CLOSE or RST_STREAM frame. Public Reset MUST NOT be
sent by an endpoint that has the state necessary to send a frame on sent by an endpoint that has the state necessary to send a frame on
the connection. the connection.
12.1. Connection Errors 12.1. Connection Errors
Errors that result in the connection being unusable, such as an Errors that result in the connection being unusable, such as an
obvious violation of protocol semantics or corruption of state that obvious violation of protocol semantics or corruption of state that
affects an entire connection, MUST be signaled using a affects an entire connection, MUST be signaled using a
CONNECTION_CLOSE frame (Section 8.8). An endpoint MAY close the CONNECTION_CLOSE frame (Section 8.13). An endpoint MAY close the
connection in this manner, even if the error only affects a single connection in this manner, even if the error only affects a single
stream. stream.
A CONNECTION_CLOSE frame could be sent in a packet that is lost. An A CONNECTION_CLOSE frame could be sent in a packet that is lost. An
endpoint SHOULD be prepared to retransmit a packet containing a endpoint SHOULD be prepared to retransmit a packet containing a
CONNECTION_CLOSE frame if it receives more packets on a terminated CONNECTION_CLOSE frame if it receives more packets on a terminated
connection. Limiting the number of retransmissions and the time over connection. Limiting the number of retransmissions and the time over
which this final packet is sent limits the effort expended on which this final packet is sent limits the effort expended on
terminated connections. terminated connections.
An endpoint that chooses not to retransmit packets containing An endpoint that chooses not to retransmit packets containing
CONNECTION_CLOSE risks a peer missing the first such packet. The CONNECTION_CLOSE risks a peer missing the first such packet. The
only mechanism available to an endpoint that continues to receive only mechanism available to an endpoint that continues to receive
data for a terminated connection is to send a Public Reset packet. data for a terminated connection is to send a Public Reset packet.
12.2. Stream Errors 12.2. Stream Errors
If the error affects a single stream, but otherwise leaves the If the error affects a single stream, but otherwise leaves the
connection in a recoverable state, the endpoint can sent a RST_STREAM connection in a recoverable state, the endpoint can sent a RST_STREAM
frame (Section 8.5) with an appropriate error code to terminate just frame (Section 8.9) with an appropriate error code to terminate just
the affected stream. the affected stream.
Stream 1 is critical to the functioning of the entire connection. If Stream 0 is critical to the functioning of the entire connection. If
stream 1 is closed with either a RST_STREAM or STREAM frame bearing stream 0 is closed with either a RST_STREAM or STREAM frame bearing
the FIN flag, an endpoint MUST generate a connection error of type the FIN flag, an endpoint MUST generate a connection error of type
QUIC_CLOSED_CRITICAL_STREAM. QUIC_CLOSED_CRITICAL_STREAM.
Some application protocols make other streams critical to that Some application protocols make other streams critical to that
protocol. An application protocol does not need to inform the protocol. An application protocol does not need to inform the
transport that a stream is critical; it can instead generate transport that a stream is critical; it can instead generate
appropriate errors in response to being notified that the critical appropriate errors in response to being notified that the critical
stream is closed. stream is closed.
An endpoint MAY send a RST_STREAM frame in the same packet as a An endpoint MAY send a RST_STREAM frame in the same packet as a
skipping to change at page 60, line 52 skipping to change at page 67, line 50
space. In the non-attack scenario, the client will send an ACK frame space. In the non-attack scenario, the client will send an ACK frame
with the larger value for largest acknowledged. In the attack with the larger value for largest acknowledged. In the attack
scenario, the attacker could acknowledge a packet in the gap. If the scenario, the attacker could acknowledge a packet in the gap. If the
server sees an acknowledgment for a packet that was never sent, the server sees an acknowledgment for a packet that was never sent, the
connection can be aborted. connection can be aborted.
The second mitigation is that the server can require that The second mitigation is that the server can require that
acknowledgments for sent packets match the encryption level of the acknowledgments for sent packets match the encryption level of the
sent packet. This mitigation is useful if the connection has an sent packet. This mitigation is useful if the connection has an
ephemeral forward-secure key that is generated and used for every new ephemeral forward-secure key that is generated and used for every new
connection. If a packet sent is encrypted with a forward-secure key, connection. If a packet sent is protected with a forward-secure key,
then any acknowledgments that are received for them MUST also be then any acknowledgments that are received for them MUST also be
forward-secure encrypted. Since the attacker will not have the forward-secure protected. Since the attacker will not have the
forward secure key, the attacker will not be able to generate forward secure key, the attacker will not be able to generate
forward-secure encrypted packets with ACK frames. forward-secure protected packets with ACK frames.
13.2. Slowloris Attacks
The attacks commonly known as Slowloris [SLOWLORIS] try to keep many
connections to the target endpoint open and hold them open as long as
possible. These attacks can be executed against a QUIC endpoint by
generating the minimum amount of activity necessary to avoid being
closed for inactivity. This might involve sending small amounts of
data, gradually opening flow control windows in order to control the
sender rate, or manufacturing ACK frames that simulate a high loss
rate.
QUIC deployments SHOULD provide mitigations for the Slowloris
attacks, such as increasing the maximum number of clients the server
will allow, limiting the number of connections a single IP address is
allowed to make, imposing restrictions on the minimum transfer speed
a connection is allowed to have, and restricting the length of time
an endpoint is allowed to stay connected.
13.3. Stream Fragmentation and Reassembly Attacks
An adversarial endpoint might intentionally fragment the data on
stream buffers in order to cause disproportionate memory commitment.
An adversarial endpoint could open a stream and send some STREAM
frames containing arbitrary fragments of the stream content.
The attack is mitigated if flow control windows correspond to
available memory. However, some receivers will over-commit memory
and advertise flow control offsets in the aggregate that exceed
actual available memory. The over-commitment strategy can lead to
better performance when endpoints are well behaved, but renders
endpoints vulnerable to the stream fragmentation attack.
QUIC deployments SHOULD provide mitigations against the stream
fragmentation attack. Mitigations could consist of avoiding over-
committing memory, delaying reassembly of STREAM frames, implementing
heuristics based on the age and duration of reassembly holes, or some
combination.
13.4. Stream Commitment Attack
An adversarial endpoint can open lots of streams, exhausting state on
an endpoint. The adversarial endpoint could repeat the process on a
large number of connections, in a manner similar to SYN flooding
attacks in TCP.
Normally, clients will open streams sequentially, as explained in
Section 10.1. However, when several streams are initiated at short
intervals, transmission error may cause STREAM DATA frames opening
streams to be received out of sequence. A receiver is obligated to
open intervening streams if a higher-numbered stream ID is received.
Thus, on a new connection, opening stream 2000001 opens 1 million
streams, as required by the specification.
The number of active streams is limited by the concurrent stream
limit transport parameter, as explained in Section 10.3. If chosen
judisciously, this limit mitigates the effect of the stream
commitment attack. However, setting the limit too low could affect
performance when applications expect to open large number of streams.
14. IANA Considerations 14. IANA Considerations
14.1. QUIC Transport Parameter Registry 14.1. QUIC Transport Parameter Registry
IANA [SHALL add/has added] a registry for "QUIC Transport Parameters" IANA [SHALL add/has added] a registry for "QUIC Transport Parameters"
under a "QUIC Protocol" heading. under a "QUIC Protocol" heading.
The "QUIC Transport Parameters" registry governs a 16-bit space. The "QUIC Transport Parameters" registry governs a 16-bit space.
This space is split into two spaces that are governed by different This space is split into two spaces that are governed by different
skipping to change at page 62, line 5 skipping to change at page 70, line 5
the value. the value.
The nominated expert(s) verify that a specification exists and is The nominated expert(s) verify that a specification exists and is
readily accessible. The expert(s) are encouraged to be biased readily accessible. The expert(s) are encouraged to be biased
towards approving registrations unless they are abusive, frivolous, towards approving registrations unless they are abusive, frivolous,
or actively harmful (not merely aesthetically displeasing, or or actively harmful (not merely aesthetically displeasing, or
architecturally dubious). architecturally dubious).
The initial contents of this registry are shown in Table 4. The initial contents of this registry are shown in Table 4.
+--------+------------------------+---------------+ +--------+-------------------------+---------------+
| Value | Parameter Name | Specification | | Value | Parameter Name | Specification |
+--------+------------------------+---------------+ +--------+-------------------------+---------------+
| 0x0000 | stream_fc_offset | Section 7.3.1 | | 0x0000 | initial_max_stream_data | Section 7.3.1 |
| | | | | | | |
| 0x0001 | connection_fc_offset | Section 7.3.1 | | 0x0001 | initial_max_data | Section 7.3.1 |
| | | | | | | |
| 0x0002 | concurrent_streams | Section 7.3.1 | | 0x0002 | initial_max_stream_id | Section 7.3.1 |
| | | | | | | |
| 0x0003 | idle_timeout | Section 7.3.1 | | 0x0003 | idle_timeout | Section 7.3.1 |
| | | | | | | |
| 0x0004 | truncate_connection_id | Section 7.3.1 | | 0x0004 | truncate_connection_id | Section 7.3.1 |
+--------+------------------------+---------------+ +--------+-------------------------+---------------+
Table 4: Initial QUIC Transport Parameters Entries Table 4: Initial QUIC Transport Parameters Entries
15. References 15. References
15.1. Normative References 15.1. Normative References
[I-D.ietf-tls-tls13] [I-D.ietf-tls-tls13]
Rescorla, E., "The Transport Layer Security (TLS) Protocol Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", draft-ietf-tls-tls13-19 (work in progress), Version 1.3", draft-ietf-tls-tls13-20 (work in progress),
March 2017. April 2017.
[QUIC-RECOVERY] [QUIC-RECOVERY]
Iyengar, J., Ed. and I. Swett, Ed., "QUIC Loss Detection Iyengar, J., Ed. and I. Swett, Ed., "QUIC Loss Detection
and Congestion Control". and Congestion Control", draft-ietf-quic-recovery (work in
progress), May 2017.
[QUIC-TLS] [QUIC-TLS]
Thomson, M., Ed. and S. Turner, Ed., "Using Transport Thomson, M., Ed. and S. Turner, Ed., "Using Transport
Layer Security (TLS) to Secure QUIC". Layer Security (TLS) to Secure QUIC", draft-ietf-quic-tls
(work in progress), May 2017.
[RFC1191] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191, [RFC1191] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191,
DOI 10.17487/RFC1191, November 1990, DOI 10.17487/RFC1191, November 1990,
<http://www.rfc-editor.org/info/rfc1191>. <http://www.rfc-editor.org/info/rfc1191>.
[RFC1981] McCann, J., Deering, S., and J. Mogul, "Path MTU Discovery [RFC1981] McCann, J., Deering, S., and J. Mogul, "Path MTU Discovery
for IP version 6", RFC 1981, DOI 10.17487/RFC1981, August for IP version 6", RFC 1981, DOI 10.17487/RFC1981, August
1996, <http://www.rfc-editor.org/info/rfc1981>. 1996, <http://www.rfc-editor.org/info/rfc1981>.
[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, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <http://www.rfc-editor.org/info/rfc2119>.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November
2003, <http://www.rfc-editor.org/info/rfc3629>.
[RFC4821] Mathis, M. and J. Heffner, "Packetization Layer Path MTU [RFC4821] Mathis, M. and J. Heffner, "Packetization Layer Path MTU
Discovery", RFC 4821, DOI 10.17487/RFC4821, March 2007, Discovery", RFC 4821, DOI 10.17487/RFC4821, March 2007,
<http://www.rfc-editor.org/info/rfc4821>. <http://www.rfc-editor.org/info/rfc4821>.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226, IANA Considerations Section in RFCs", BCP 26, RFC 5226,
DOI 10.17487/RFC5226, May 2008, DOI 10.17487/RFC5226, May 2008,
<http://www.rfc-editor.org/info/rfc5226>. <http://www.rfc-editor.org/info/rfc5226>.
15.2. Informative References 15.2. Informative References
skipping to change at page 63, line 44 skipping to change at page 71, line 48
[RFC7301] Friedl, S., Popov, A., Langley, A., and E. Stephan, [RFC7301] Friedl, S., Popov, A., Langley, A., and E. Stephan,
"Transport Layer Security (TLS) Application-Layer Protocol "Transport Layer Security (TLS) Application-Layer Protocol
Negotiation Extension", RFC 7301, DOI 10.17487/RFC7301, Negotiation Extension", RFC 7301, DOI 10.17487/RFC7301,
July 2014, <http://www.rfc-editor.org/info/rfc7301>. July 2014, <http://www.rfc-editor.org/info/rfc7301>.
[RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext [RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
Transfer Protocol Version 2 (HTTP/2)", RFC 7540, Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
DOI 10.17487/RFC7540, May 2015, DOI 10.17487/RFC7540, May 2015,
<http://www.rfc-editor.org/info/rfc7540>. <http://www.rfc-editor.org/info/rfc7540>.
[SST] Ford, B., "Structured Streams: A New Transport [SLOWLORIS]
Abstraction", DOI 10.1145/1282427.1282421, ACM RSnake Hansen, R., "Welcome to Slowloris...", June 2009,
SIGCOMM Computer Communication Review Volume 37 Issue 4, <https://web.archive.org/web/20150315054838/
October 2007. http://ha.ckers.org/slowloris/>.
[SST] Ford, B., "Structured streams", ACM SIGCOMM Computer
Communication Review Vol. 37, pp. 361,
DOI 10.1145/1282427.1282421, October 2007.
15.3. URIs 15.3. URIs
[1] https://github.com/quicwg/base-drafts/wiki/QUIC-Versions [1] https://github.com/quicwg/base-drafts/wiki/QUIC-Versions
Appendix A. Contributors Appendix A. Contributors
The original authors of this specification were Ryan Hamilton, Jana The original authors of this specification were Ryan Hamilton, Jana
Iyengar, Ian Swett, and Alyssa Wilk. Iyengar, Ian Swett, and Alyssa Wilk.
skipping to change at page 64, line 40 skipping to change at page 72, line 44
discussions and public ones on the quic@ietf.org and proto- discussions and public ones on the quic@ietf.org and proto-
quic@chromium.org mailing lists. Our thanks to all. quic@chromium.org mailing lists. Our thanks to all.
Appendix C. Change Log Appendix C. Change Log
*RFC Editor's Note:* Please remove this section prior to *RFC Editor's Note:* Please remove this section prior to
publication of a final version of this document. publication of a final version of this document.
Issue and pull request numbers are listed with a leading octothorp. Issue and pull request numbers are listed with a leading octothorp.
C.1. Since draft-ietf-quic-transport-01: C.1. Since draft-ietf-quic-transport-02
o The size of the initial packet payload has a fixed minimum (#267,
#472)
o Define when Version Negotiation packets are ignored (#284, #294,
#241, #143, #474)
o The 64-bit FNV-1a algorithm is used for integrity protection of
unprotected packets (#167, #480, #481, #517)
o Rework initial packet types to change how the connection ID is
chosen (#482, #442, #493)
o No timestamps are forbidden in unprotected packets (#542, #429)
o Cryptographic handshake is now on stream 0 (#456)
o Remove congestion control exemption for cryptographic handshake
(#248, #476)
o Version 1 of QUIC uses TLS; a new version is needed to use a
different handshake protocol (#516)
o STREAM frames have a reduced number of offset lengths (#543, #430)
o Split some frames into separate connection- and stream- level
frames (#443)
* WINDOW_UPDATE split into MAX_DATA and MAX_STREAM_DATA (#450)
* BLOCKED split to match WINDOW_UPDATE split (#454)
* Define STREAM_ID_NEEDED frame (#455)
o A NEW_CONNECTION_ID frame supports connection migration without
linkability (#232, #491, #496)
o Transport parameters for 0-RTT are retained from a previous
connection (#512)
* A client in 0-RTT no longer required to reset excess streams
(#425, #479)
o Expanded security considerations (#440, #444, #445, #448)
C.2. Since draft-ietf-quic-transport-01
o Defined short and long packet headers (#40, #148, #361) o Defined short and long packet headers (#40, #148, #361)
o Defined a versioning scheme and stable fields (#51, #361) o Defined a versioning scheme and stable fields (#51, #361)
o Define reserved version values for "greasing" negotiation (#112, o Define reserved version values for "greasing" negotiation (#112,
#278) #278)
o The initial packet number is randomized (#35, #283) o The initial packet number is randomized (#35, #283)
o Narrow the packet number encoding range requirement (#67, #286, o Narrow the packet number encoding range requirement (#67, #286,
#299, #323, #356) #299, #323, #356)
o Defined client address validation (#52, #118, #120, #275) o Defined client address validation (#52, #118, #120, #275)
o Define transport parameters as a TLS extension (#122) o Define transport parameters as a TLS extension (#49, #122)
o SCUP and COPT parameters are no longer valid (#116, #117) o SCUP and COPT parameters are no longer valid (#116, #117)
o Transport parameters for 0-RTT are either remembered from before, o Transport parameters for 0-RTT are either remembered from before,
or assume default values (#126) or assume default values (#126)
o The server chooses connection IDs in its final flight (#119, #349, o The server chooses connection IDs in its final flight (#119, #349,
#361) #361)
o The server echoes the Connection ID and packet number fields when o The server echoes the Connection ID and packet number fields when
sending a Version Negotiation packet (#133, #295, #244) sending a Version Negotiation packet (#133, #295, #244)
o Definied a minimum packet size for the initial handshake packet o Defined a minimum packet size for the initial handshake packet
from the client (#69, #136, #139, #164) from the client (#69, #136, #139, #164)
o Path MTU Discovery (#64, #106) o Path MTU Discovery (#64, #106)
o The initial handshake packet from the client needs to fit in a o The initial handshake packet from the client needs to fit in a
single packet (#338) single packet (#338)
o Forbid acknowledgment of packets containing only ACK and PADDING o Forbid acknowledgment of packets containing only ACK and PADDING
(#291) (#291)
skipping to change at page 66, line 10 skipping to change at page 75, line 10
o Forbid the use of Public Reset where CONNECTION_CLOSE is possible o Forbid the use of Public Reset where CONNECTION_CLOSE is possible
(#289) (#289)
o Define packet protection rules (#336) o Define packet protection rules (#336)
o Require that stream be entirely delivered or reset, including o Require that stream be entirely delivered or reset, including
acknowledgment of all STREAM frames or the RST_STREAM, before it acknowledgment of all STREAM frames or the RST_STREAM, before it
closes (#381) closes (#381)
o Remove stream reservation from state machine (#174, #280) o Remove stream reservation from state machine (#174, #280)
o Only stream 0 does not contributing to connection-level flow o Only stream 1 does not contribute to connection-level flow control
control (#204) (#204)
o Stream 1 counts towards the maximum concurrent stream limit (#201, o Stream 1 counts towards the maximum concurrent stream limit (#201,
#282) #282)
o Remove connection-level flow control exclusion for some streams o Remove connection-level flow control exclusion for some streams
(except 1) (#246) (except 1) (#246)
o RST_STREAM affects connection-level flow control (#162, #163) o RST_STREAM affects connection-level flow control (#162, #163)
o Flow control accounting uses the maximum data offset on each o Flow control accounting uses the maximum data offset on each
skipping to change at page 66, line 39 skipping to change at page 75, line 39
o Remove error code and reason phrase from GOAWAY (#352, #355) o Remove error code and reason phrase from GOAWAY (#352, #355)
o GOAWAY includes a final stream number for both directions (#347) o GOAWAY includes a final stream number for both directions (#347)
o Error codes for RST_STREAM and CONNECTION_CLOSE are now at a o Error codes for RST_STREAM and CONNECTION_CLOSE are now at a
consistent offset (#249) consistent offset (#249)
o Defined priority as the responsibility of the application protocol o Defined priority as the responsibility of the application protocol
(#104, #303) (#104, #303)
C.2. Since draft-ietf-quic-transport-00: C.3. Since draft-ietf-quic-transport-00
o Replaced DIVERSIFICATION_NONCE flag with KEY_PHASE flag o Replaced DIVERSIFICATION_NONCE flag with KEY_PHASE flag
o Defined versioning o Defined versioning
o Reworked description of packet and frame layout o Reworked description of packet and frame layout
o Error code space is divided into regions for each component o Error code space is divided into regions for each component
o Use big endian for all numeric values o Use big endian for all numeric values
C.3. Since draft-hamilton-quic-transport-protocol-01: C.4. Since draft-hamilton-quic-transport-protocol-01
o Adopted as base for draft-ietf-quic-tls. o Adopted as base for draft-ietf-quic-tls
o Updated authors/editors list. o Updated authors/editors list
o Added IANA Considerations section. o Added IANA Considerations section
o Moved Contributors and Acknowledgments to appendices. o Moved Contributors and Acknowledgments to appendices
Authors' Addresses Authors' Addresses
Jana Iyengar (editor) Jana Iyengar (editor)
Google Google
Email: jri@google.com Email: jri@google.com
Martin Thomson (editor) Martin Thomson (editor)
Mozilla Mozilla
 End of changes. 213 change blocks. 
705 lines changed or deleted 1135 lines changed or added

This html diff was produced by rfcdiff 1.45. The latest version is available from http://tools.ietf.org/tools/rfcdiff/