# flare.quic

> A module of flare_mlake's API.

``flare.quic`` — sans-I/O QUIC v1 codec primitives (RFC 9000).

This package ships the *codec* layer of QUIC: pure byte-in /
byte-out parsers and emitters for the wire format, plus pure
state machines and congestion-controller helpers that operate
on owned value-typed state. It contains no socket I/O and no
TLS handshake. Every public type's contract is "give me bytes,
get back a typed value (and optionally error context); give me
a typed value, get back bytes".

The codec layer is the load-bearing foundation that downstream
modules (the QUIC reactor + datagram pump, the TLS handshake
adapter that drives the CRYPTO frames) will build on top of.
Shipping the codec layer first lets us cross-validate against
reference fixtures before committing to a particular reactor /
TLS design.

Public re-exports:

- :mod:`.varint` — variable-length integer codec
  (RFC 9000 §16): :class:`Varint`, :func:`encode_varint`,
  :func:`decode_varint`, :func:`varint_encoded_length`,
  :data:`VARINT_MAX`.
- :mod:`.packet` — long / short header codec
  (RFC 9000 §17): :class:`ConnectionId`, :class:`LongHeader`,
  :class:`ShortHeader`, :class:`InitialExtras`, the
  ``PACKET_TYPE_*`` constants, and their byte-level helpers.
- :mod:`.frame` — all 22 RFC 9000 §19 transport frames as typed
  payload structs plus :trait:`FrameHandler` +
  :func:`parse_frame_into[H]` for zero-carrier dispatch, and
  per-type ``encode_*`` writers that append to a caller-owned
  ``mut out: List[UInt8]``.
- :mod:`.transport_params` — RFC 9000 §18 transport-parameter
  codec: :class:`TransportParameters`,
  :func:`encode_transport_parameters`,
  :func:`decode_transport_parameters`, and the ``TP_ID_*``
  constants for every parameter the codec carries.
- :mod:`.state` — RFC 9000 §3 / §13 sans-I/O connection +
  stream state machines: :class:`Connection`, :class:`Stream`,
  :func:`handle_frame_buf`, :func:`mark_handshake_complete`,
  :func:`is_idle_timeout_expired`, :func:`connection_close`,
  the per-typed-payload ``apply_*`` helpers, and the
  ``CONN_STATE_*`` / ``STREAM_STATE_*`` constants.
- :mod:`.crypto` — sans-I/O QUIC v1 crypto math
  (RFC 9001 §5 + RFC 5869 + RFC 8446 §7.1): HKDF-Extract,
  HKDF-Expand, HKDF-Expand-Label, RFC 9001 §5.2 initial-
  secret derivation, plus the :trait:`QuicCrypto` AEAD
  trait surface that the QUIC server reactor binds against.
  :class:`OpenSslQuicCrypto` is the shipped backend;
  :class:`StubQuicCrypto` remains as a typed sentinel that
  raises, so tests can pin the trait boundary without
  linking OpenSSL.
- :mod:`.cc` — RFC 9002 §7 congestion control: the
  :trait:`CongestionController` contract plus :class:`RenoController`
  (RFC 9002 NewReno) and :class:`CubicController` (RFC 9438 CUBIC with
  RFC 9406 HyStart++), selected by :class:`CcChoice`. The
  loss-recovery bookkeeping in ``_loss_recovery`` drives a controller
  on every ACK / loss.