Imported from shayanheidari01/ShineNETVPN (android/aether_core/quiche/quiche/AGENTS.md). Install upstream with npx skills add shayanheidari01/ShineNETVPN --skill quiche. Copyright stays with the author.

quiche/ — Core QUIC + HTTP/3 Library

OVERVIEW

Low-level QUIC transport and HTTP/3 in Rust. App provides IO/timers; this crate handles protocol state. Also exposes C FFI via staticlib/cdylib.

STRUCTURE

src/
  lib.rs          (9k lines) Connection struct, Config, connect()/accept() entry points
  h3/
    mod.rs        (7.5k)     HTTP/3 connection — own Error/Result types, NOT quiche::Error
    qpack/                   QPACK header compression
  recovery/
    mod.rs                   Recovery enum, RecoveryOps trait (enum_dispatch)
    congestion/              Legacy CC (Cubic, Reno, Hystart++)
    gcongestion/             Google-derived CC (BBR2) — behind `gcongestion` feature
  stream/                    Stream state machine, flow control per-stream
  tls/                       TLS backend abstraction (BoringSSL)
  crypto/                    Packet protection, key derivation
  packet.rs       (2.3k)     Packet parsing, ConnectionId, Header
  frame.rs                   QUIC frame encode/decode
  path.rs                    Multi-path state, PathEvent, migration
  pmtud.rs                   Path MTU discovery
  cid.rs                     Connection ID management
  ffi.rs          (2.3k)     C FFI — behind `ffi` feature
  transport_params.rs        QUIC transport parameter encode/decode
  flowcontrol.rs             Connection-level flow control
  ranges.rs                  ACK range tracking
  buffers.rs                 BufFactory/BufSplit/DefaultBufFactory traits and types
  range_buf.rs               RangeBuf — ordered byte buffer for stream reassembly
  dgram.rs                   DATAGRAM frame support
  rand.rs                    Random number generation
  minmax.rs                  Windowed min/max filter
  test_utils.rs              Pipe struct for in-memory QUIC pairs (pub via `internal` feature)
  tests.rs        (12k)      Integration tests
  build.rs                   Link directives + pkg-config metadata (NOTE: lives in src/, not crate root)
include/
  quiche.h        (1.2k)     C API header — mirrors ffi.rs

BoringSSL itself is built by boring-sys (no in-tree submodule).

WHERE TO LOOK

ANTI-PATTERNS

• h3::Error != quiche::Error — don't mix or convert carelessly; they have different variant sets.
• Error::Done is a success signal in many read/write loops — not a failure.
• Don't add new CC impls outside recovery/ — two parallel impls (congestion + gcongestion) already exist.
• unsafe only at FFI boundaries — tls/, crypto/, ffi.rs; don't add elsewhere.
• #[cfg(feature = "fuzzing")] disables real crypto — never accidentally gate non-test code on it.

NOTES

• build.rs is at src/build.rs (Cargo.toml: build = "src/build.rs"), not crate root. Emits link directives and, with pkg-config-meta, writes quiche.pc; BoringSSL itself is built by boring-sys.
• Single TLS backend: boringssl-boring-crate (default), via the boring/boring-sys crates.
• quiche::Error is Copy + Clone — intentional for hot-path ergonomics.
• test_utils::Pipe exposed via internal feature for downstream crate integration tests.
• Tests use rstest with #[values("cubic", "bbr2_gcongestion")] parameterization for CC coverage.
• BORING_BSSL_PATH env var (consumed by boring-sys) points at a custom BoringSSL source tree.
• Crate-type: lib + staticlib + cdylib — the latter two for C consumers.
• BufFactory trait (buffers.rs) enables zero-copy buffer creation; Connection<F> is generic over it.