QUIC event definitions for qlog
draft-ietf-quic-qlog-quic-events-00

Document Type Active Internet-Draft (quic WG)
Authors Robin Marx  , Luca Niccolini  , Marten Seemann 
Last updated 2021-06-10
Replaces draft-marx-quic-qlog-quic-events
Stream Internet Engineering Task Force (IETF)
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QUIC                                                             R. Marx
Internet-Draft                                                 KU Leuven
Intended status: Standards Track                       L. Niccolini, Ed.
Expires: 12 December 2021                                       Facebook
                                                         M. Seemann, Ed.
                                                           Protocol Labs
                                                            10 June 2021

                    QUIC event definitions for qlog
                  draft-ietf-quic-qlog-quic-events-00

Abstract

   This document describes concrete qlog event definitions and their
   metadata for QUIC events.  These events can then be embedded in the
   higher level schema defined in [QLOG-MAIN].

Status of This Memo

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

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

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 12 December 2021.

Copyright Notice

   Copyright (c) 2021 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components
   extracted from this document must include Simplified BSD License text
   as described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Simplified BSD License.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Notational Conventions  . . . . . . . . . . . . . . . . .   4
   2.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . .   4
     2.1.  Links to the main schema  . . . . . . . . . . . . . . . .   4
       2.1.1.  Raw packet and frame information  . . . . . . . . . .   5
       2.1.2.  Events not belonging to a single connection . . . . .   5
   3.  QUIC event definitions  . . . . . . . . . . . . . . . . . . .   6
     3.1.  connectivity  . . . . . . . . . . . . . . . . . . . . . .   6
       3.1.1.  server_listening  . . . . . . . . . . . . . . . . . .   6
       3.1.2.  connection_started  . . . . . . . . . . . . . . . . .   7
       3.1.3.  connection_closed . . . . . . . . . . . . . . . . . .   7
       3.1.4.  connection_id_updated . . . . . . . . . . . . . . . .   8
       3.1.5.  spin_bit_updated  . . . . . . . . . . . . . . . . . .   8
       3.1.6.  connection_retried  . . . . . . . . . . . . . . . . .   9
       3.1.7.  connection_state_updated  . . . . . . . . . . . . . .   9
       3.1.8.  MIGRATION-related events  . . . . . . . . . . . . . .  11
     3.2.  security  . . . . . . . . . . . . . . . . . . . . . . . .  11
       3.2.1.  key_updated . . . . . . . . . . . . . . . . . . . . .  11
       3.2.2.  key_retired . . . . . . . . . . . . . . . . . . . . .  12
     3.3.  transport . . . . . . . . . . . . . . . . . . . . . . . .  12
       3.3.1.  version_information . . . . . . . . . . . . . . . . .  12
       3.3.2.  alpn_information  . . . . . . . . . . . . . . . . . .  13
       3.3.3.  parameters_set  . . . . . . . . . . . . . . . . . . .  14
       3.3.4.  parameters_restored . . . . . . . . . . . . . . . . .  16
       3.3.5.  packet_sent . . . . . . . . . . . . . . . . . . . . .  16
       3.3.6.  packet_received . . . . . . . . . . . . . . . . . . .  17
       3.3.7.  packet_dropped  . . . . . . . . . . . . . . . . . . .  18
       3.3.8.  packet_buffered . . . . . . . . . . . . . . . . . . .  19
       3.3.9.  packets_acked . . . . . . . . . . . . . . . . . . . .  20
       3.3.10. datagrams_sent  . . . . . . . . . . . . . . . . . . .  20
       3.3.11. datagrams_received  . . . . . . . . . . . . . . . . .  21
       3.3.12. datagram_dropped  . . . . . . . . . . . . . . . . . .  21
       3.3.13. stream_state_updated  . . . . . . . . . . . . . . . .  22
       3.3.14. frames_processed  . . . . . . . . . . . . . . . . . .  23
       3.3.15. data_moved  . . . . . . . . . . . . . . . . . . . . .  24
     3.4.  recovery  . . . . . . . . . . . . . . . . . . . . . . . .  25
       3.4.1.  parameters_set  . . . . . . . . . . . . . . . . . . .  26
       3.4.2.  metrics_updated . . . . . . . . . . . . . . . . . . .  26
       3.4.3.  congestion_state_updated  . . . . . . . . . . . . . .  27
       3.4.4.  loss_timer_updated  . . . . . . . . . . . . . . . . .  28
       3.4.5.  packet_lost . . . . . . . . . . . . . . . . . . . . .  29
       3.4.6.  marked_for_retransmit . . . . . . . . . . . . . . . .  29
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .  30
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  30
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  30
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .  30

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     6.2.  Informative References  . . . . . . . . . . . . . . . . .  31
   Appendix A.  QUIC data field definitions  . . . . . . . . . . . .  31
     A.1.  IPAddress . . . . . . . . . . . . . . . . . . . . . . . .  31
     A.2.  PacketType  . . . . . . . . . . . . . . . . . . . . . . .  31
     A.3.  PacketNumberSpace . . . . . . . . . . . . . . . . . . . .  31
     A.4.  PacketHeader  . . . . . . . . . . . . . . . . . . . . . .  31
     A.5.  Token . . . . . . . . . . . . . . . . . . . . . . . . . .  32
     A.6.  KeyType . . . . . . . . . . . . . . . . . . . . . . . . .  32
     A.7.  QUIC Frames . . . . . . . . . . . . . . . . . . . . . . .  33
       A.7.1.  PaddingFrame  . . . . . . . . . . . . . . . . . . . .  33
       A.7.2.  PingFrame . . . . . . . . . . . . . . . . . . . . . .  33
       A.7.3.  AckFrame  . . . . . . . . . . . . . . . . . . . . . .  33
       A.7.4.  ResetStreamFrame  . . . . . . . . . . . . . . . . . .  34
       A.7.5.  StopSendingFrame  . . . . . . . . . . . . . . . . . .  34
       A.7.6.  CryptoFrame . . . . . . . . . . . . . . . . . . . . .  35
       A.7.7.  NewTokenFrame . . . . . . . . . . . . . . . . . . . .  35
       A.7.8.  StreamFrame . . . . . . . . . . . . . . . . . . . . .  35
       A.7.9.  MaxDataFrame  . . . . . . . . . . . . . . . . . . . .  36
       A.7.10. MaxStreamDataFrame  . . . . . . . . . . . . . . . . .  36
       A.7.11. MaxStreamsFrame . . . . . . . . . . . . . . . . . . .  36
       A.7.12. DataBlockedFrame  . . . . . . . . . . . . . . . . . .  36
       A.7.13. StreamDataBlockedFrame  . . . . . . . . . . . . . . .  36
       A.7.14. StreamsBlockedFrame . . . . . . . . . . . . . . . . .  36
       A.7.15. NewConnectionIDFrame  . . . . . . . . . . . . . . . .  37
       A.7.16. RetireConnectionIDFrame . . . . . . . . . . . . . . .  37
       A.7.17. PathChallengeFrame  . . . . . . . . . . . . . . . . .  37
       A.7.18. PathResponseFrame . . . . . . . . . . . . . . . . . .  37
       A.7.19. ConnectionCloseFrame  . . . . . . . . . . . . . . . .  38
       A.7.20. HandshakeDoneFrame  . . . . . . . . . . . . . . . . .  38
       A.7.21. UnknownFrame  . . . . . . . . . . . . . . . . . . . .  38
       A.7.22. TransportError  . . . . . . . . . . . . . . . . . . .  38
       A.7.23. CryptoError . . . . . . . . . . . . . . . . . . . . .  39
   Appendix B.  Change Log . . . . . . . . . . . . . . . . . . . . .  39
     B.1.  Since draft-marx-qlog-event-definitions-quic-h3-02: . . .  39
     B.2.  Since draft-marx-qlog-event-definitions-quic-h3-01: . . .  40
     B.3.  Since draft-marx-qlog-event-definitions-quic-h3-00: . . .  41
   Appendix C.  Design Variations  . . . . . . . . . . . . . . . . .  41
   Appendix D.  Acknowledgements . . . . . . . . . . . . . . . . . .  42
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  42

1.  Introduction

   This document describes the values of the qlog name ("category" +
   "event") and "data" fields and their semantics for the QUIC protocol.
   This document is based on draft-34 of the QUIC I-Ds QUIC-TRANSPORT
   [QUIC-RECOVERY] [QUIC-TLS].  HTTP/3 and QPACK events are defined in a
   separate document [QLOG-H3].

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   Feedback and discussion are welcome at https://github.com/quicwg/qlog
   (https://github.com/quicwg/qlog).  Readers are advised to refer to
   the "editor's draft" at that URL for an up-to-date version of this
   document.

   Concrete examples of integrations of this schema in various
   programming languages can be found at https://github.com/quiclog/
   qlog/ (https://github.com/quiclog/qlog/).

1.1.  Notational Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

   The examples and data definitions in ths document are expressed in a
   custom data definition language, inspired by JSON and TypeScript, and
   described in [QLOG-MAIN].

2.  Overview

   This document describes the values of the qlog "name" ("category" +
   "event") and "data" fields and their semantics for the QUIC protocol.

   This document assumes the usage of the encompassing main qlog schema
   defined in [QLOG-MAIN].  Each subsection below defines a separate
   category (for example connectivity, transport, recovery) and each
   subsubsection is an event type (for example "packet_received").

   For each event type, its importance and data definition is laid out,
   often accompanied by possible values for the optional "trigger"
   field.  For the definition and semantics of "importance" and
   "trigger", see the main schema document.

   Most of the complex datastructures, enums and re-usable definitions
   are grouped together on the bottom of this document for clarity.

2.1.  Links to the main schema

   This document re-uses all the fields defined in the main qlog schema
   (e.g., name, category, type, data, group_id, protocol_type, the time-
   related fields, importance, RawInfo, etc.).

   One entry in the "protocol_type" qlog array field MUST be "QUIC" if
   events from this document are included in a qlog trace.

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   When the qlog "group_id" field is used, it is recommended to use
   QUIC's Original Destination Connection ID (ODCID, the CID chosen by
   the client when first contacting the server), as this is the only
   value that does not change over the course of the connection and can
   be used to link more advanced QUIC packets (e.g., Retry, Version
   Negotiation) to a given connection.  Similarly, the ODCID should be
   used as the qlog filename or file identifier, potentially suffixed by
   the vantagepoint type (For example, abcd1234_server.qlog would
   contain the server-side trace of the connection with ODCID abcd1234).

2.1.1.  Raw packet and frame information

   This document re-uses the definition of the RawInfo data class from
   [QLOG-MAIN].

   Note:  QUIC packets always include an AEAD authentication tag
      ("trailer") at the end.  As this tag is always the same size for a
      given connection (it depends on the used TLS cipher), this
      document does not define a separate "RawInfo:aead_tag_length"
      field here.  Instead, this field is reflected in
      "transport:parameters_set" and can be logged only once.

   Note:  As QUIC uses trailers in packets, packet header_lengths can be
      calculated as:

      header_length = length - payload_length - aead_tag_length

      For UDP datagrams, the calulation is simpler:

      header_length = length - payload_length

   Note:  In some cases, the length fields are also explicitly reflected
      inside of packet headers.  For example, the QUIC STREAM frame has
      a "length" field indicating its payload size.  Similarly, the QUIC
      Long Header has a "length" field which is equal to the payload
      length plus the packet number length.  In these cases, those
      fields are intentionally preserved in the event definitions.  Even
      though this can lead to duplicate data when the full RawInfo is
      logged, it allows a more direct mapping of the QUIC specifications
      to qlog, making it easier for users to interpret.

2.1.2.  Events not belonging to a single connection

   For several types of events, it is sometimes impossible to tie them
   to a specific conceptual QUIC connection (e.g., a packet_dropped
   event triggered because the packet has an unknown connection_id in
   the header).  Since qlog events in a trace are typically associated
   with a single connection, it is unclear how to log these events.

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   Ideally, implementers SHOULD create a separate, individual "endpoint-
   level" trace file (or group_id value), not associated with a specific
   connection (for example a "server.qlog" or group_id = "client"), and
   log all events that do not belong to a single connection to this
   grouping trace.  However, this is not always practical, depending on
   the implementation.  Because the semantics of most of these events
   are well-defined in the protocols and because they are difficult to
   mis-interpret as belonging to a connection, implementers MAY choose
   to log events not belonging to a particular connection in any other
   trace, even those strongly associated with a single connection.

   Note that this can make it difficult to match logs from different
   vantage points with each other.  For example, from the client side,
   it is easy to log connections with version negotiation or retry in
   the same trace, while on the server they would most likely be logged
   in separate traces.  Servers can take extra efforts (and keep
   additional state) to keep these events combined in a single trace
   however (for example by also matching connections on their four-tuple
   instead of just the connection ID).

3.  QUIC event definitions

   Each subheading in this section is a qlog event category, while each
   sub-subheading is a qlog event type.  Concretely, for the following
   two items, we have the category "connectivity" and event type
   "server_listening", resulting in a concatenated qlog "name" field
   value of "connectivity:server_listening".

3.1.  connectivity

3.1.1.  server_listening

   Importance: Extra

   Emitted when the server starts accepting connections.

   Data:

{
    ip_v4?: IPAddress,
    ip_v6?: IPAddress,
    port_v4?: uint32,
    port_v6?: uint32,

    retry_required?:boolean // the server will always answer client initials with a retry (no 1-RTT connection setups by choice)
}

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   Note: some QUIC stacks do not handle sockets directly and are thus
   unable to log IP and/or port information.

3.1.2.  connection_started

   Importance: Base

   Used for both attempting (client-perspective) and accepting (server-
   perspective) new connections.  Note that this event has overlap with
   connection_state_updated and this is a separate event mainly because
   of all the additional data that should be logged.

   Data:

   {
       ip_version?: "v4" | "v6",
       src_ip?: IPAddress,
       dst_ip?: IPAddress,

       protocol?: string, // transport layer protocol (default "QUIC")
       src_port?: uint32,
       dst_port?: uint32,

       src_cid?: bytes,
       dst_cid?: bytes,

   }

   Note: some QUIC stacks do not handle sockets directly and are thus
   unable to log IP and/or port information.

3.1.3.  connection_closed

   Importance: Base

   Used for logging when a connection was closed, typically when an
   error or timeout occurred.  Note that this event has overlap with
   connectivity:connection_state_updated, as well as the
   CONNECTION_CLOSE frame.  However, in practice, when analyzing large
   deployments, it can be useful to have a single event representing a
   connection_closed event, which also includes an additional reason
   field to provide additional information.  Additionally, it is useful
   to log closures due to timeouts, which are difficult to reflect using
   the other options.

   In QUIC there are two main connection-closing error categories:
   connection and application errors.  They have well-defined error
   codes and semantics.  Next to these however, there can be internal

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   errors that occur that may or may not get mapped to the official
   error codes in implementation-specific ways.  As such, multiple error
   codes can be set on the same event to reflect this.

   {
       owner?:"local"|"remote", // which side closed the connection

       connection_code?:TransportError | CryptoError | uint32,
       application_code?:ApplicationError | uint32,
       internal_code?:uint32,

       reason?:string
   }

   Triggers: * clean * handshake_timeout * idle_timeout * error // this
   is called the "immediate close" in the QUIC specification *
   stateless_reset * version_mismatch * application // for example
   HTTP/3's GOAWAY frame

3.1.4.  connection_id_updated

   Importance: Base

   This event is emitted when either party updates their current
   Connection ID.  As this typically happens only sparingly over the
   course of a connection, this event allows loggers to be more
   efficient than logging the observed CID with each packet in the
   .header field of the "packet_sent" or "packet_received" events.

   This is viewed from the perspective of the one applying the new id.
   As such, if we receive a new connection id from our peer, we will see
   the dst_ fields are set.  If we update our own connection id (e.g.,
   NEW_CONNECTION_ID frame), we log the src_ fields.

   Data:

   {
       owner: "local" | "remote",

       old?:bytes,
       new?:bytes,
   }

3.1.5.  spin_bit_updated

   Importance: Base

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   To be emitted when the spin bit changes value.  It SHOULD NOT be
   emitted if the spin bit is set without changing its value.

   Data:

   {
       state: boolean
   }

3.1.6.  connection_retried

   TODO

3.1.7.  connection_state_updated

   Importance: Base

   This event is used to track progress through QUIC's complex handshake
   and connection close procedures.  It is intended to provide
   exhaustive options to log each state individually, but also provides
   a more basic, simpler set for implementations less interested in
   tracking each smaller state transition.  As such, users should not
   expect to see -all- these states reflected in all qlogs and
   implementers should focus on support for the SimpleConnectionState
   set.

   Data: ~~~ { old?: ConnectionState | SimpleConnectionState, new:
   ConnectionState | SimpleConnectionState }

   enum ConnectionState { attempted, // initial sent/received
   peer_validated, // peer address validated by: client sent Handshake
   packet OR client used CONNID chosen by the server. transport-draft-
   32, section-8.1 handshake_started, early_write, // 1 RTT can be sent,
   but handshake isn't done yet handshake_complete, // TLS handshake
   complete: Finished received and sent. tls-draft-32, section-4.1.1
   handshake_confirmed, // HANDSHAKE_DONE sent/received (connection is
   now "active", 1RTT can be sent). tls-draft-32, section-4.1.2 closing,
   draining, // connection_close sent/received closed // draining period
   done, connection state discarded }

   enum SimpleConnectionState { attempted, handshake_started,
   handshake_confirmed, closed } ~~~

   These states correspond to the following transitions for both client
   and server:

   *Client:*

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   *  send initial

      -  state = attempted

   *  get initial

      -  state = validated _(not really "needed" at the client, but
         somewhat useful to indicate progress nonetheless)_

   *  get first Handshake packet

      -  state = handshake_started

   *  get Handshake packet containing ServerFinished

      -  state = handshake_complete

   *  send ClientFinished

      -  state = early_write (1RTT can now be sent)

   *  get HANDSHAKE_DONE

      -  state = handshake_confirmed

   *Server:*

   *  get initial

      -  state = attempted

   *  send initial _(don't think this needs a separate state, since some
      handshake will always be sent in the same flight as this?)_

   *  send handshake EE, CERT, CV, ...

      -  state = handshake_started

   *  send ServerFinished

      -  state = early_write (1RTT can now be sent)

   *  get first handshake packet / something using a server-issued CID
      of min length

      -  state = validated

   *  get handshake packet containing ClientFinished

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      -  state = handshake_complete

   *  send HANDSHAKE_DONE

      -  state = handshake_confirmed

   Note:  connection_state_changed with a new state of "attempted" is
      the same conceptual event as the connection_started event above
      from the client's perspective.  Similarly, a state of "closing" or
      "draining" corresponds to the connection_closed event.

3.1.8.  MIGRATION-related events

   e.g., path_updated

   TODO: read up on the draft how migration works and whether to best
   fit this here or in TRANSPORT TODO: integrate
   https://tools.ietf.org/html/draft-deconinck-quic-multipath-02

   For now, infer from other connectivity events and path_challenge/
   path_response frames

3.2.  security

3.2.1.  key_updated

   Importance: Base

   Note: secret_updated would be more correct, but in the draft it's
   called KEY_UPDATE, so stick with that for consistency

   Data:

   {
       key_type:KeyType,
       old?:bytes,
       new:bytes,
       generation?:uint32 // needed for 1RTT key updates
   }

   Triggers:

   *  "tls" // (e.g., initial, handshake and 0-RTT keys are generated by
      TLS)

   *  "remote_update"

   *  "local_update"

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3.2.2.  key_retired

   Importance: Base

   Data:

   {
       key_type:KeyType,
       key?:bytes,
       generation?:uint32 // needed for 1RTT key updates
   }

   Triggers:

   *  "tls" // (e.g., initial, handshake and 0-RTT keys are dropped
      implicitly)

   *  "remote_update"

   *  "local_update"

3.3.  transport

3.3.1.  version_information

   Importance: Core

   QUIC endpoints each have their own list of of QUIC versions they
   support.  The client uses the most likely version in their first
   initial.  If the server does support that version, it replies with a
   version_negotiation packet, containing supported versions.  From
   this, the client selects a version.  This event aggregates all this
   information in a single event type.  It also allows logging of
   supported versions at an endpoint without actual version negotiation
   needing to happen.

   Data:

   {
       server_versions?:Array<bytes>,
       client_versions?:Array<bytes>,
       chosen_version?:bytes
   }

   Intended use:

   *  When sending an initial, the client logs this event with
      client_versions and chosen_version set

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   *  Upon receiving a client initial with a supported version, the
      server logs this event with server_versions and chosen_version set

   *  Upon receiving a client initial with an unsupported version, the
      server logs this event with server_versions set and
      client_versions to the single-element array containing the
      client's attempted version.  The absence of chosen_version implies
      no overlap was found.

   *  Upon receiving a version negotiation packet from the server, the
      client logs this event with client_versions set and
      server_versions to the versions in the version negotiation packet
      and chosen_version to the version it will use for the next initial
      packet

3.3.2.  alpn_information

   Importance: Core

   QUIC implementations each have their own list of application level
   protocols and versions thereof they support.  The client includes a
   list of their supported options in its first initial as part of the
   TLS Application Layer Protocol Negotiation (alpn) extension.  If
   there are common option(s), the server chooses the most optimal one
   and communicates this back to the client.  If not, the connection is
   closed.

   Data:

   {
       server_alpns?:Array<string>,
       client_alpns?:Array<string>,
       chosen_alpn?:string
   }

   Intended use:

   *  When sending an initial, the client logs this event with
      client_alpns set

   *  When receiving an initial with a supported alpn, the server logs
      this event with server_alpns set, client_alpns equalling the
      client-provided list, and chosen_alpn to the value it will send
      back to the client.

   *  When receiving an initial with an alpn, the client logs this event
      with chosen_alpn to the received value.

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   *  Alternatively, a client can choose to not log the first event, but
      wait for the receipt of the server initial to log this event with
      both client_alpns and chosen_alpn set.

3.3.3.  parameters_set

   Importance: Core

   This event groups settings from several different sources (transport
   parameters, TLS ciphers, etc.) into a single event.  This is done to
   minimize the amount of events and to decouple conceptual setting
   impacts from their underlying mechanism for easier high-level
   reasoning.

   All these settings are typically set once and never change.  However,
   they are typically set at different times during the connection, so
   there will typically be several instances of this event with
   different fields set.

   Note that some settings have two variations (one set locally, one
   requested by the remote peer).  This is reflected in the "owner"
   field.  As such, this field MUST be correct for all settings included
   a single event instance.  If you need to log settings from two sides,
   you MUST emit two separate event instances.

   In the case of connection resumption and 0-RTT, some of the server's
   parameters are stored up-front at the client and used for the initial
   connection startup.  They are later updated with the server's reply.
   In these cases, utilize the separate "parameters_restored" event to
   indicate the initial values, and this event to indicate the updated
   values, as normal.

   Data:

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{
    owner?:"local" | "remote",

    resumption_allowed?:boolean, // valid session ticket was received
    early_data_enabled?:boolean, // early data extension was enabled on the TLS layer
    tls_cipher?:string, // (e.g., "AES_128_GCM_SHA256")
    aead_tag_length?:uint8, // depends on the TLS cipher, but it's easier to be explicit. Default value is 16

    // transport parameters from the TLS layer:
    original_destination_connection_id?:bytes,
    initial_source_connection_id?:bytes,
    retry_source_connection_id?:bytes,
    stateless_reset_token?:Token,
    disable_active_migration?:boolean,

    max_idle_timeout?:uint64,
    max_udp_payload_size?:uint32,
    ack_delay_exponent?:uint16,
    max_ack_delay?:uint16,
    active_connection_id_limit?:uint32,

    initial_max_data?:uint64,
    initial_max_stream_data_bidi_local?:uint64,
    initial_max_stream_data_bidi_remote?:uint64,
    initial_max_stream_data_uni?:uint64,
    initial_max_streams_bidi?:uint64,
    initial_max_streams_uni?:uint64,

    preferred_address?:PreferredAddress
}

interface PreferredAddress {
    ip_v4:IPAddress,
    ip_v6:IPAddress,

    port_v4:uint16,
    port_v6:uint16,

    connection_id:bytes,
    stateless_reset_token:Token
}

   Additionally, this event can contain any number of unspecified
   fields.  This is to reflect setting of for example unknown (greased)
   transport parameters or employed (proprietary) extensions.

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3.3.4.  parameters_restored

   Importance: Base

   When using QUIC 0-RTT, clients are expected to remember and restore
   the server's transport parameters from the previous connection.  This
   event is used to indicate which parameters were restored and to which
   values when utilizing 0-RTT.  Note that not all transport parameters
   should be restored (many are even prohibited from being re-utilized).
   The ones listed here are the ones expected to be useful for correct
   0-RTT usage.

   Data:

   {
       disable_active_migration?:boolean,

       max_idle_timeout?:uint64,
       max_udp_payload_size?:uint32,
       active_connection_id_limit?:uint32,

       initial_max_data?:uint64,
       initial_max_stream_data_bidi_local?:uint64,
       initial_max_stream_data_bidi_remote?:uint64,
       initial_max_stream_data_uni?:uint64,
       initial_max_streams_bidi?:uint64,
       initial_max_streams_uni?:uint64,
   }

   Note that, like parameters_set above, this event can contain any
   number of unspecified fields to allow for additional/custom
   parameters.

3.3.5.  packet_sent

   Importance: Core

   Data:

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{
    header:PacketHeader,

    frames?:Array<QuicFrame>, // see appendix for the definitions

    is_coalesced?:boolean, // default value is false

    retry_token?:Token, // only if header.packet_type === retry

    stateless_reset_token?:bytes, // only if header.packet_type === stateless_reset. Is always 128 bits in length.

    supported_versions:Array<bytes>, // only if header.packet_type === version_negotiation

    raw?:RawInfo,
    datagram_id?:uint32
}

   Note: We do not explicitly log the encryption_level or
   packet_number_space: the header.packet_type specifies this by
   inference (assuming correct implementation)

   Triggers:

   *  "retransmit_reordered" // draft-23 5.1.1

   *  "retransmit_timeout" // draft-23 5.1.2

   *  "pto_probe" // draft-23 5.3.1

   *  "retransmit_crypto" // draft-19 6.2

   *  "cc_bandwidth_probe" // needed for some CCs to figure out
      bandwidth allocations when there are no normal sends

   Note: for more details on "datagram_id", see Section 3.3.10.  It is
   only needed when keeping track of packet coalescing.

3.3.6.  packet_received

   Importance: Core

   Data:

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{
    header:PacketHeader,

    frames?:Array<QuicFrame>, // see appendix for the definitions

    is_coalesced?:boolean,

    retry_token?:Token, // only if header.packet_type === retry

    stateless_reset_token?:bytes, // only if header.packet_type === stateless_reset. Is always 128 bits in length.

    supported_versions:Array<bytes>, // only if header.packet_type === version_negotiation

    raw?:RawInfo,
    datagram_id?:uint32
}

   Note: We do not explicitly log the encryption_level or
   packet_number_space: the header.packet_type specifies this by
   inference (assuming correct implementation)

   Triggers:

   *  "keys_available" // if packet was buffered because it couldn't be
      decrypted before

   Note: for more details on "datagram_id", see Section 3.3.10.  It is
   only needed when keeping track of packet coalescing.

3.3.7.  packet_dropped

   Importance: Base

   This event indicates a QUIC-level packet was dropped after partial or
   no parsing.

   Data:

{
    header?:PacketHeader, // primarily packet_type should be filled here, as other fields might not be parseable

    raw?:RawInfo,
    datagram_id?:uint32
}

   For this event, the "trigger" field SHOULD be set (for example to one
   of the values below), as this helps tremendously in debugging.

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   Triggers:

   *  "key_unavailable"

   *  "unknown_connection_id"

   *  "header_parse_error"

   *  "payload_decrypt_error"

   *  "protocol_violation"

   *  "dos_prevention"

   *  "unsupported_version"

   *  "unexpected_packet"

   *  "unexpected_source_connection_id"

   *  "unexpected_version"

   *  "duplicate"

   *  "invalid_initial"

   Note: sometimes packets are dropped before they can be associated
   with a particular connection (e.g., in case of
   "unsupported_version").  This situation is discussed more in
   Section 2.1.2.

   Note: for more details on "datagram_id", see Section 3.3.10.  It is
   only needed when keeping track of packet coalescing.

3.3.8.  packet_buffered

   Importance: Base

   This event is emitted when a packet is buffered because it cannot be
   processed yet.  Typically, this is because the packet cannot be
   parsed yet, and thus we only log the full packet contents when it was
   parsed in a packet_received event.

   Data:

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{
    header?:PacketHeader, // primarily packet_type and possible packet_number should be filled here, as other elements might not be available yet

    raw?:RawInfo,
    datagram_id?:uint32
}

   Note: for more details on "datagram_id", see Section 3.3.10.  It is
   only needed when keeping track of packet coalescing.

   Triggers:

   *  "backpressure" // indicates the parser cannot keep up, temporarily
      buffers packet for later processing

   *  "keys_unavailable" // if packet cannot be decrypted because the
      proper keys were not yet available

3.3.9.  packets_acked

   Importance: Extra

   This event is emitted when a (group of) sent packet(s) is
   acknowledged by the remote peer _for the first time_. This
   information could also be deduced from the contents of received ACK
   frames.  However, ACK frames require additional processing logic to
   determine when a given packet is acknowledged for the first time, as
   QUIC uses ACK ranges which can include repeated ACKs.  Additionally,
   this event can be used by implementations that do not log frame
   contents.

   Data: ~~~ { packet_number_space?:PacketNumberSpace,

   packet_numbers?:Array<uint64> } ~~~

   Note: if packet_number_space is omitted, it assumes the default value
   of PacketNumberSpace.application_data, as this is by far the most
   prevalent packet number space a typical QUIC connection will use.

3.3.10.  datagrams_sent

   Importance: Extra

   When we pass one or more UDP-level datagrams to the socket.  This is
   useful for determining how QUIC packet buffers are drained to the OS.

   Data:

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{
    count?:uint16, // to support passing multiple at once
    raw?:Array<RawInfo>, // RawInfo:length field indicates total length of the datagrams, including UDP header length

    datagram_ids?:Array<uint32>
}

   Note: QUIC itself does not have a concept of a "datagram_id".  This
   field is a purely qlog-specific construct to allow tracking how
   multiple QUIC packets are coalesced inside of a single UDP datagram,
   which is an important optimization during the QUIC handshake.  For
   this, implementations assign a (per-endpoint) unique ID to each
   datagram and keep track of which packets were coalesced into the same
   datagram.  As packet coalescing typically only happens during the
   handshake (as it requires at least one long header packet), this can
   be done without much overhead.

3.3.11.  datagrams_received

   Importance: Extra

   When we receive one or more UDP-level datagrams from the socket.
   This is useful for determining how datagrams are passed to the user
   space stack from the OS.

   Data:

{
    count?:uint16, // to support passing multiple at once
    raw?:Array<RawInfo>, // RawInfo:length field indicates total length of the datagrams, including UDP header length

    datagram_ids?:Array<uint32>
}

   Note: for more details on "datagram_ids", see Section 3.3.10.

3.3.12.  datagram_dropped

   Importance: Extra

   When we drop a UDP-level datagram.  This is typically if it does not
   contain a valid QUIC packet (in that case, use packet_dropped
   instead).

   Data:

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   {
       raw?:RawInfo
   }

3.3.13.  stream_state_updated

   Importance: Base

   This event is emitted whenever the internal state of a QUIC stream is
   updated, as described in QUIC transport draft-23 section 3.  Most of
   this can be inferred from several types of frames going over the
   wire, but it's much easier to have explicit signals for these state
   changes.

   Data:

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{
    stream_id:uint64,
    stream_type?:"unidirectional"|"bidirectional", // mainly useful when opening the stream

    old?:StreamState,
    new:StreamState,

    stream_side?:"sending"|"receiving"
}

enum StreamState {
    // bidirectional stream states, draft-23 3.4.
    idle,
    open,
    half_closed_local,
    half_closed_remote,
    closed,

    // sending-side stream states, draft-23 3.1.
    ready,
    send,
    data_sent,
    reset_sent,
    reset_received,

    // receive-side stream states, draft-23 3.2.
    receive,
    size_known,
    data_read,
    reset_read,

    // both-side states
    data_received,

    // qlog-defined
    destroyed // memory actually freed
}

   Note: QUIC implementations SHOULD mainly log the simplified
   bidirectional (HTTP/2-alike) stream states (e.g., idle, open, closed)
   instead of the more finegrained stream states (e.g., data_sent,
   reset_received).  These latter ones are mainly for more in-depth
   debugging.  Tools SHOULD be able to deal with both types equally.

3.3.14.  frames_processed

   Importance: Extra

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   This event's main goal is to prevent a large proliferation of
   specific purpose events (e.g., packets_acknowledged,
   flow_control_updated, stream_data_received).  We want to give
   implementations the opportunity to (selectively) log this type of
   signal without having to log packet-level details (e.g., in
   packet_received).  Since for almost all cases, the effects of
   applying a frame to the internal state of an implementation can be
   inferred from that frame's contents, we aggregate these events in
   this single "frames_processed" event.

   Note: This event can be used to signal internal state change not
   resulting directly from the actual "parsing" of a frame (e.g., the
   frame could have been parsed, data put into a buffer, then later
   processed, then logged with this event).

   Note: Implementations logging "packet_received" and which include all
   of the packet's constituent frames therein, are not expected to emit
   this "frames_processed" event.  Rather, implementations not wishing
   to log full packets or that wish to explicitly convey extra
   information about when frames are processed (if not directly tied to
   their reception) can use this event.

   Note: for some events, this approach will lose some information
   (e.g., for which encryption level are packets being acknowledged?).
   If this information is important, please use the packet_received
   event instead.

   Note: in some implementations, it can be difficult to log frames
   directly, even when using packet_sent and packet_received events.
   For these cases, this event also contains the direct packet_number
   field, which can be used to more explicitly link this event to the
   packet_sent/received events.

   Data:

   {
       frames:Array<QuicFrame>, // see appendix for the definitions

       packet_number?:uint64
   }

3.3.15.  data_moved

   Importance: Base

   Used to indicate when data moves between the different layers (for
   example passing from the application protocol (e.g., HTTP) to QUIC
   stream buffers and vice versa) or between the application protocol

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   (e.g., HTTP) and the actual user application on top (for example a
   browser engine).  This helps make clear the flow of data, how long
   data remains in various buffers and the overheads introduced by
   individual layers.

   For example, this helps make clear whether received data on a QUIC
   stream is moved to the application protocol immediately (for example
   per received packet) or in larger batches (for example, all QUIC
   packets are processed first and afterwards the application layer
   reads from the streams with newly available data).  This in turn can
   help identify bottlenecks or scheduling problems.

   Data:

{
    stream_id?:uint64,
    offset?:uint64,
    length?:uint64, // byte length of the moved data

    from?:string, // typically: use either of "user","application","transport","network"
    to?:string, // typically: use either of "user","application","transport","network"

    data?:bytes // raw bytes that were transferred
}

   Note: we do not for example use a "direction" field (with values "up"
   and "down") to specify the data flow.  This is because in some
   optimized implementations, data might skip some individual layers.
   Additionally, using explicit "from" and "to" fields is more flexible
   and allows the definition of other conceptual "layers" (for example
   to indicate data from QUIC CRYPTO frames being passed to a TLS
   library ("security") or from HTTP/3 to QPACK ("qpack")).

   Note: this event type is part of the "transport" category, but really
   spans all the different layers.  This means we have a few leaky
   abstractions here (for example, the stream_id or stream offset might
   not be available at some logging points, or the raw data might not be
   in a byte-array form).  In these situations, implementers can decide
   to define new, in-context fields to aid in manual debugging.

3.4.  recovery

   Note: most of the events in this category are kept generic to support
   different recovery approaches and various congestion control
   algorithms.  Tool creators SHOULD make an effort to support and
   visualize even unknown data in these events (e.g., plot unknown
   congestion states by name on a timeline visualization).

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3.4.1.  parameters_set

   Importance: Base

   This event groups initial parameters from both loss detection and
   congestion control into a single event.  All these settings are
   typically set once and never change.  Implementation that do, for
   some reason, change these parameters during execution, MAY emit the
   parameters_set event twice.

   Data:

{
    // Loss detection, see recovery draft-23, Appendix A.2
    reordering_threshold?:uint16, // in amount of packets
    time_threshold?:float, // as RTT multiplier
    timer_granularity?:uint16, // in ms
    initial_rtt?:float, // in ms

    // congestion control, Appendix B.1.
    max_datagram_size?:uint32, // in bytes // Note: this could be updated after pmtud
    initial_congestion_window?:uint64, // in bytes
    minimum_congestion_window?:uint32, // in bytes // Note: this could change when max_datagram_size changes
    loss_reduction_factor?:float,
    persistent_congestion_threshold?:uint16 // as PTO multiplier
}

   Additionally, this event can contain any number of unspecified fields
   to support different recovery approaches.

3.4.2.  metrics_updated

   Importance: Core

   This event is emitted when one or more of the observable recovery
   metrics changes value.  This event SHOULD group all possible metric
   updates that happen at or around the same time in a single event
   (e.g., if min_rtt and smoothed_rtt change at the same time, they
   should be bundled in a single metrics_updated entry, rather than
   split out into two).  Consequently, a metrics_updated event is only
   guaranteed to contain at least one of the listed metrics.

   Data:

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{
    // Loss detection, see recovery draft-23, Appendix A.3
    min_rtt?:float, // in ms or us, depending on the overarching qlog's configuration
    smoothed_rtt?:float, // in ms or us, depending on the overarching qlog's configuration
    latest_rtt?:float, // in ms or us, depending on the overarching qlog's configuration
    rtt_variance?:float, // in ms or us, depending on the overarching qlog's configuration

    pto_count?:uint16,

    // Congestion control, Appendix B.2.
    congestion_window?:uint64, // in bytes
    bytes_in_flight?:uint64,

    ssthresh?:uint64, // in bytes

    // qlog defined
    packets_in_flight?:uint64, // sum of all packet number spaces

    pacing_rate?:uint64 // in bps
}

   Note: to make logging easier, implementations MAY log values even if
   they are the same as previously reported values (e.g., two subsequent
   METRIC_UPDATE entries can both report the exact same value for
   min_rtt).  However, applications SHOULD try to log only actual
   updates to values.

   Additionally, this event can contain any number of unspecified fields
   to support different recovery approaches.

3.4.3.  congestion_state_updated

   Importance: Base

   This event signifies when the congestion controller enters a
   significant new state and changes its behaviour.  This event's
   definition is kept generic to support different Congestion Control
   algorithms.  For example, for the algorithm defined in the Recovery
   draft ("enhanced" New Reno), the following states are defined:

   *  slow_start

   *  congestion_avoidance

   *  application_limited

   *  recovery

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   Data:

   {
       old?:string,
       new:string
   }

   The "trigger" field SHOULD be logged if there are multiple ways in
   which a state change can occur but MAY be omitted if a given state
   can only be due to a single event occuring (e.g., slow start is
   exited only when ssthresh is exceeded).

   Some triggers for ("enhanced" New Reno):

   *  persistent_congestion

   *  ECN

3.4.4.  loss_timer_updated

   Importance: Extra

   This event is emitted when a recovery loss timer changes state.  The
   three main event types are:

   *  set: the timer is set with a delta timeout for when it will
      trigger next

   *  expired: when the timer effectively expires after the delta
      timeout

   *  cancelled: when a timer is cancelled (e.g., all outstanding
      packets are acknowledged, start idle period)

   Note: to indicate an active timer's timeout update, a new "set" event
   is used.

   Data:

{
    timer_type?:"ack"|"pto", // called "mode" in draft-23 A.9.
    packet_number_space?: PacketNumberSpace,

    event_type:"set"|"expired"|"cancelled",

    delta?:float // if event_type === "set": delta time in ms or us (see configuration) from this event's timestamp until when the timer will trigger
}

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   TODO: how about CC algo's that use multiple timers?  How generic do
   these events need to be?  Just support QUIC-style recovery from the
   spec or broader?

   TODO: read up on the loss detection logic in draft-27 onward and see
   if this suffices

3.4.5.  packet_lost

   Importance: Core

   This event is emitted when a packet is deemed lost by loss detection.

   Data:

{
    header?:PacketHeader, // should include at least the packet_type and packet_number

    // not all implementations will keep track of full packets, so these are optional
    frames?:Array<QuicFrame> // see appendix for the definitions
}

   For this event, the "trigger" field SHOULD be set (for example to one
   of the values below), as this helps tremendously in debugging.

   Triggers:

   *  "reordering_threshold",

   *  "time_threshold"

   *  "pto_expired" // draft-23 section 5.3.1, MAY

3.4.6.  marked_for_retransmit

   Importance: Extra

   This event indicates which data was marked for retransmit upon
   detecing a packet loss (see packet_lost).  Similar to our reasoning
   for the "frames_processed" event, in order to keep the amount of
   different events low, we group this signal for all types of
   retransmittable data in a single event based on existing QUIC frame
   definitions.

   Implementations retransmitting full packets or frames directly can
   just log the consituent frames of the lost packet here (or do away
   with this event and use the contents of the packet_lost event
   instead).  Conversely, implementations that have more complex logic

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   (e.g., marking ranges in a stream's data buffer as in-flight), or
   that do not track sent frames in full (e.g., only stream offset +
   length), can translate their internal behaviour into the appropriate
   frame instance here even if that frame was never or will never be put
   on the wire.

   Note: much of this data can be inferred if implementations log
   packet_sent events (e.g., looking at overlapping stream data offsets
   and length, one can determine when data was retransmitted).

   Data:

   {
       frames:Array<QuicFrame>, // see appendix for the definitions
   }

4.  Security Considerations

   TBD

5.  IANA Considerations

   TBD

6.  References

6.1.  Normative References

   [QLOG-H3]  Marx, R., Ed., Niccolini, L., Ed., and M. Seemann, Ed.,
              "HTTP/3 and QPACK event definitions for qlog", Work in
              Progress, Internet-Draft, draft-ietf-quic-qlog-h3-events-
              00, <https://tools.ietf.org/html/draft-ietf-quic-qlog-h3-
              events-00>.

   [QLOG-MAIN]
              Marx, R., Ed., Niccolini, L., Ed., and M. Seemann, Ed.,
              "Main logging schema for qlog", Work in Progress,
              Internet-Draft, draft-ietf-quic-qlog-main-schema-00,
              <https://tools.ietf.org/html/draft-ietf-quic-qlog-main-
              schema-00>.

   [QUIC-RECOVERY]
              Iyengar, J., Ed. and I. Swett, Ed., "QUIC Loss Detection
              and Congestion Control", RFC 9002, DOI 10.17487/RFC9002,
              May 2021, <https://www.rfc-editor.org/rfc/rfc9002>.

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   [QUIC-TLS] Thomson, M., Ed. and S. Turner, Ed., "Using TLS to Secure
              QUIC", RFC 9001, DOI 10.17487/RFC9001, May 2021,
              <https://www.rfc-editor.org/rfc/rfc9001>.

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

6.2.  Informative References

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

Appendix A.  QUIC data field definitions

A.1.  IPAddress

class IPAddress : string | bytes;

// an IPAddress can either be a "human readable" form (e.g., "127.0.0.1" for v4 or "2001:0db8:85a3:0000:0000:8a2e:0370:7334" for v6) or use a raw byte-form (as the string forms can be ambiguous)

A.2.  PacketType

   enum PacketType {
       initial,
       handshake,
       zerortt = "0RTT",
       onertt = "1RTT",
       retry,
       version_negotiation,
       stateless_reset,
       unknown
   }

A.3.  PacketNumberSpace

   enum PacketNumberSpace {
       initial,
       handshake,
       application_data
   }

A.4.  PacketHeader

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class PacketHeader {
    // Note: short vs long header is implicit through PacketType

    packet_type: PacketType;
    packet_number: uint64;

    flags?: uint8; // the bit flags of the packet headers (spin bit, key update bit, etc. up to and including the packet number length bits if present) interpreted as a single 8-bit integer

    token?:Token; // only if packet_type == initial

    length?: uint16, // only if packet_type == initial || handshake || 0RTT. Signifies length of the packet_number plus the payload.

    // only if present in the header
    // if correctly using transport:connection_id_updated events,
    // dcid can be skipped for 1RTT packets
    version?: bytes; // e.g., "ff00001d" for draft-29
    scil?: uint8;
    dcil?: uint8;
    scid?: bytes;
    dcid?: bytes;
}

A.5.  Token

class Token {
    type?:"retry"|"resumption"|"stateless_reset";

    length?:uint32; // byte length of the token
    data?:bytes; // raw byte value of the token

    details?:any; // decoded fields included in the token (typically: peer's IP address, creation time)
}

   The token carried in an Initial packet can either be a retry token
   from a Retry packet, a stateless reset token from a Stateless Reset
   packet or one originally provided by the server in a NEW_TOKEN frame
   used when resuming a connection (e.g., for address validation
   purposes).  Retry and resumption tokens typically contain encoded
   metadata to check the token's validity when it is used, but this
   metadata and its format is implementation specific.  For that, this
   field includes a general-purpose "details" field.

A.6.  KeyType

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   enum KeyType {
       server_initial_secret,
       client_initial_secret,

       server_handshake_secret,
       client_handshake_secret,

       server_0rtt_secret,
       client_0rtt_secret,

       server_1rtt_secret,
       client_1rtt_secret
   }

A.7.  QUIC Frames

type QuicFrame = PaddingFrame | PingFrame | AckFrame | ResetStreamFrame | StopSendingFrame | CryptoFrame | NewTokenFrame | StreamFrame | MaxDataFrame | MaxStreamDataFrame | MaxStreamsFrame | DataBlockedFrame | StreamDataBlockedFrame | StreamsBlockedFrame | NewConnectionIDFrame | RetireConnectionIDFrame | PathChallengeFrame | PathResponseFrame | ConnectionCloseFrame | HandshakeDoneFrame | UnknownFrame;

A.7.1.  PaddingFrame

   In QUIC, PADDING frames are simply identified as a single byte of
   value 0.  As such, each padding byte could be theoretically
   interpreted and logged as an individual PaddingFrame.

   However, as this leads to heavy logging overhead, implementations
   SHOULD instead emit just a single PaddingFrame and set the
   payload_length property to the amount of PADDING bytes/frames
   included in the packet.

   class PaddingFrame{
       frame_type:string = "padding";

       length?:uint32; // total frame length, including frame header
       payload_length?:uint32;
   }

A.7.2.  PingFrame

   class PingFrame{
       frame_type:string = "ping";

       length?:uint32; // total frame length, including frame header
       payload_length?:uint32;
   }

A.7.3.  AckFrame

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class AckFrame{
    frame_type:string = "ack";

    ack_delay?:float; // in ms

    // first number is "from": lowest packet number in interval
    // second number is "to": up to and including // highest packet number in interval
    // e.g., looks like [[1,2],[4,5]]
    acked_ranges?:Array<[uint64, uint64]|[uint64]>;

    // ECN (explicit congestion notification) related fields (not always present)
    ect1?:uint64;
    ect0?:uint64;
    ce?:uint64;

    length?:uint32; // total frame length, including frame header
    payload_length?:uint32;
}

   Note: the packet ranges in AckFrame.acked_ranges do not necessarily
   have to be ordered (e.g., [[5,9],[1,4]] is a valid value).

   Note: the two numbers in the packet range can be the same (e.g.,
   [120,120] means that packet with number 120 was ACKed).  However, in
   that case, implementers SHOULD log [120] instead and tools MUST be
   able to deal with both notations.

A.7.4.  ResetStreamFrame

   class ResetStreamFrame{
       frame_type:string = "reset_stream";

       stream_id:uint64;
       error_code:ApplicationError | uint32;
       final_size:uint64; // in bytes

       length?:uint32; // total frame length, including frame header
       payload_length?:uint32;
   }

A.7.5.  StopSendingFrame

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   class StopSendingFrame{
       frame_type:string = "stop_sending";

       stream_id:uint64;
       error_code:ApplicationError | uint32;

       length?:uint32; // total frame length, including frame header
       payload_length?:uint32;
   }

A.7.6.  CryptoFrame

   class CryptoFrame{
       frame_type:string = "crypto";

       offset:uint64;
       length:uint64;

       payload_length?:uint32;
   }

A.7.7.  NewTokenFrame

   class NewTokenFrame{
     frame_type:string = "new_token";

     token:Token
   }

A.7.8.  StreamFrame

class StreamFrame{
    frame_type:string = "stream";

    stream_id:uint64;

    // These two MUST always be set
    // If not present in the Frame type, log their default values
    offset:uint64;
    length:uint64;

    // this MAY be set any time, but MUST only be set if the value is "true"
    // if absent, the value MUST be assumed to be "false"
    fin?:boolean;

    raw?:bytes;
}

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A.7.9.  MaxDataFrame

   class MaxDataFrame{
     frame_type:string = "max_data";

     maximum:uint64;
   }

A.7.10.  MaxStreamDataFrame

   class MaxStreamDataFrame{
     frame_type:string = "max_stream_data";

     stream_id:uint64;
     maximum:uint64;
   }

A.7.11.  MaxStreamsFrame

   class MaxStreamsFrame{
     frame_type:string = "max_streams";

     stream_type:string = "bidirectional" | "unidirectional";
     maximum:uint64;
   }

A.7.12.  DataBlockedFrame

   class DataBlockedFrame{
     frame_type:string = "data_blocked";

     limit:uint64;
   }

A.7.13.  StreamDataBlockedFrame

   class StreamDataBlockedFrame{
     frame_type:string = "stream_data_blocked";

     stream_id:uint64;
     limit:uint64;
   }

A.7.14.  StreamsBlockedFrame

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   class StreamsBlockedFrame{
     frame_type:string = "streams_blocked";

     stream_type:string = "bidirectional" | "unidirectional";
     limit:uint64;
   }

A.7.15.  NewConnectionIDFrame

   class NewConnectionIDFrame{
     frame_type:string = "new_connection_id";

     sequence_number:uint32;
     retire_prior_to:uint32;

     connection_id_length?:uint8;
     connection_id:bytes;

     stateless_reset_token?:Token;
   }

A.7.16.  RetireConnectionIDFrame

   class RetireConnectionIDFrame{
     frame_type:string = "retire_connection_id";

     sequence_number:uint32;
   }

A.7.17.  PathChallengeFrame

   class PathChallengeFrame{
     frame_type:string = "path_challenge";

     data?:bytes; // always 64-bit
   }

A.7.18.  PathResponseFrame

   class PathResponseFrame{
     frame_type:string = "path_response";

     data?:bytes; // always 64-bit
   }

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A.7.19.  ConnectionCloseFrame

   raw_error_code is the actual, numerical code.  This is useful because
   some error types are spread out over a range of codes (e.g., QUIC's
   crypto_error).

type ErrorSpace = "transport" | "application";

class ConnectionCloseFrame{
    frame_type:string = "connection_close";

    error_space?:ErrorSpace;
    error_code?:TransportError | ApplicationError | uint32;
    raw_error_code?:uint32;
    reason?:string;

    trigger_frame_type?:uint64 | string; // For known frame types, the appropriate "frame_type" string. For unknown frame types, the hex encoded identifier value
}

A.7.20.  HandshakeDoneFrame

   class HandshakeDoneFrame{
     frame_type:string = "handshake_done";
   }

A.7.21.  UnknownFrame

   class UnknownFrame{
       frame_type:string = "unknown";
       raw_frame_type:uint64;

       raw_length?:uint32;
       raw?:bytes;
   }

A.7.22.  TransportError

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   enum TransportError {
       no_error,
       internal_error,
       connection_refused,
       flow_control_error,
       stream_limit_error,
       stream_state_error,
       final_size_error,
       frame_encoding_error,
       transport_parameter_error,
       connection_id_limit_error,
       protocol_violation,
       invalid_token,
       application_error,
       crypto_buffer_exceeded
   }

A.7.23.  CryptoError

   These errors are defined in the TLS document as "A TLS alert is
   turned into a QUIC connection error by converting the one-byte alert
   description into a QUIC error code.  The alert description is added
   to 0x100 to produce a QUIC error code from the range reserved for
   CRYPTO_ERROR."

   This approach maps badly to a pre-defined enum.  As such, we define
   the crypto_error string as having a dynamic component here, which
   should include the hex-encoded value of the TLS alert description.

   enum CryptoError {
       crypto_error_{TLS_ALERT}
   }

Appendix B.  Change Log

B.1.  Since draft-marx-qlog-event-definitions-quic-h3-02:

   *  These changes were done in preparation of the adoption of the
      drafts by the QUIC working group (#137)

   *  Split QUIC and HTTP/3 events into two separate documents

   *  Moved RawInfo, Importance, Generic events and Simulation events to
      the main schema document.

   *  Changed to/from value options of the "data_moved" event

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B.2.  Since draft-marx-qlog-event-definitions-quic-h3-01:

   Major changes:

   *  Moved data_moved from http to transport.  Also made the "from" and
      "to" fields flexible strings instead of an enum (#111,#65)

   *  Moved packet_type fields to PacketHeader.  Moved packet_size field
      out of PacketHeader to RawInfo:length (#40)

   *  Made events that need to log packet_type and packet_number use a
      header field instead of logging these fields individually

   *  Added support for logging retry, stateless reset and initial
      tokens (#94,#86,#117)

   *  Moved separate general event categories into a single category
      "generic" (#47)

   *  Added "transport:connection_closed" event (#43,#85,#78,#49)

   *  Added version_information and alpn_information events
      (#85,#75,#28)

   *  Added parameters_restored events to help clarify 0-RTT behaviour
      (#88)

   Smaller changes:

   *  Merged loss_timer events into one loss_timer_updated event

   *  Field data types are now strongly defined (#10,#39,#36,#115)

   *  Renamed qpack instruction_received and instruction_sent to
      instruction_created and instruction_parsed (#114)

   *  Updated qpack:dynamic_table_updated.update_type.  It now has the
      value "inserted" instead of "added" (#113)

   *  Updated qpack:dynamic_table_updated.  It now has an "owner" field
      to differentiate encoder vs decoder state (#112)

   *  Removed push_allowed from http:parameters_set (#110)

   *  Removed explicit trigger field indications from events, since this
      was moved to be a generic property of the "data" field (#80)

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   *  Updated transport:connection_id_updated to be more in line with
      other similar events.  Also dropped importance from Core to Base
      (#45)

   *  Added length property to PaddingFrame (#34)

   *  Added packet_number field to transport:frames_processed (#74)

   *  Added a way to generically log packet header flags (first 8 bits)
      to PacketHeader

   *  Added additional guidance on which events to log in which
      situations (#53)

   *  Added "simulation:scenario" event to help indicate simulation
      details

   *  Added "packets_acked" event (#107)

   *  Added "datagram_ids" to the datagram_X and packet_X events to
      allow tracking of coalesced QUIC packets (#91)

   *  Extended connection_state_updated with more fine-grained states
      (#49)

B.3.  Since draft-marx-qlog-event-definitions-quic-h3-00:

   *  Event and category names are now all lowercase

   *  Added many new events and their definitions

   *  "type" fields have been made more specific (especially important
      for PacketType fields, which are now called packet_type instead of
      type)

   *  Events are given an importance indicator (issue #22)

   *  Event names are more consistent and use past tense (issue #21)

   *  Triggers have been redefined as properties of the "data" field and
      updated for most events (issue #23)

Appendix C.  Design Variations

   TBD

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Appendix D.  Acknowledgements

   Much of the initial work by Robin Marx was done at Hasselt
   University.

   Thanks to Marten Seemann, Jana Iyengar, Brian Trammell, Dmitri
   Tikhonov, Stephen Petrides, Jari Arkko, Marcus Ihlar, Victor
   Vasiliev, Mirja Kuehlewind, Jeremy Laine, Kazu Yamamoto, Christian
   Huitema, and Lucas Pardue for their feedback and suggestions.

Authors' Addresses

   Robin Marx
   KU Leuven

   Email: robin.marx@kuleuven.be

   Luca Niccolini (editor)
   Facebook

   Email: lniccolini@fb.com

   Marten Seemann (editor)
   Protocol Labs

   Email: marten@protocol.ai

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