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refactor(core): peel session.rs anti-replay, perf telemetry, and seal lane into submodules

Browse Source 
session.rs (1203) sharpens down to the two hot-path state machines +
lifecycle (887): ReplayWindow + seq_of + their tests -> session/replay.rs;
the PUNKTFUNK_PERF trio PumpPerf/SealPerf/TimedCoder -> session/perf.rs;
the Phase-1.5 lane machinery SealLane/SealJob/seal_wire_slice/
TWO_LANE_MIN_PACKETS -> session/seal.rs. Facade pattern (session.rs stays
the parent file); pub use keeps session::{PumpPerf,SealPerf} stable and
lib.rs re-exports are untouched. Pure code motion + pub(super) bumps —
seal_frame_inner/poll_frame/poll_input bodies unchanged; the
wire-equivalence tests stay co-located with the seal path they pin.

196 lib tests pass, clippy --features quic --all-targets clean, fmt clean.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
This commit is contained in:
Enrico Bühler
2026-07-20 17:56:26 +02:00
parent e0a1edb9d4
commit eacaaa5cd8
4 changed files with 354 additions and 323 deletions
Download Patch File Download Diff File Expand all files Collapse all files
crates/punktfunk-core/src/session.rs
+7 -323
View File
@@ -102,160 +102,15 @@ fn stamp_received(mut f: Frame) -> Frame {
f
}
/// Wire-packet count at which a frame's sealing splits across two lanes (plan Phase 1.5):
/// below it the channel rendezvous (~µs) isn't worth it; at it the halved AES-GCM span
/// (≥ ~125 µs of ~1 µs/packet work) dwarfs the hand-off. ≈300 KB of wire, i.e. ≥150 Mbps
/// at 60 fps — small frames and the probe's ~17-packet AUs stay strictly single-lane.
const TWO_LANE_MIN_PACKETS: usize = 256;
mod perf;
mod replay;
mod seal;
/// One two-lane seal hand-off: the frame's back-half wire buffers, sealed by the worker with
/// nonces `seq_base + i` (the nonce order is deterministic per shard index, which is what
/// makes the split sound). Round-trips through the channels so the buffers return to the pool.
struct SealJob {
bufs: Vec<Vec<u8>>,
seq_base: u64,
timed: bool,
/// Worker-lane CPU ns (when `timed`) and the seal outcome, filled in by the worker.
ns: u64,
result: Result<()>,
}
pub use perf::{PumpPerf, SealPerf};
/// The persistent second seal lane: a worker thread that AES-GCM-seals the back half of a
/// large frame's packets while the send thread seals the front half. Rendezvous channels
/// (bound 1) — the send thread submits, seals its half, then waits; no per-frame spawn.
/// Dropping the struct closes the channel and the worker exits.
struct SealLane {
to_worker: std::sync::mpsc::SyncSender<SealJob>,
from_worker: std::sync::mpsc::Receiver<SealJob>,
}
impl SealLane {
fn spawn(crypto: std::sync::Arc<SessionCrypto>) -> Option<SealLane> {
let (to_worker, jobs) = std::sync::mpsc::sync_channel::<SealJob>(1);
let (done_tx, from_worker) = std::sync::mpsc::sync_channel::<SealJob>(1);
std::thread::Builder::new()
.name("punktfunk-seal2".into())
.spawn(move || {
while let Ok(mut job) = jobs.recv() {
let t0 = job.timed.then(std::time::Instant::now);
job.result = seal_wire_slice(&crypto, &mut job.bufs, job.seq_base);
if let Some(t0) = t0 {
job.ns = t0.elapsed().as_nanos() as u64;
}
if done_tx.send(job).is_err() {
break; // session gone mid-frame — nothing left to seal for
}
}
})
.ok()?;
Some(SealLane {
to_worker,
from_worker,
})
}
}
/// Seal a run of pre-written wire buffers in place: buffer `i` is `seq(8) ‖ plaintext ‖ tag
/// scratch` and seals over `[8..]` with sequence `seq_base + i` — the exact per-packet layout
/// and nonce order of the fused single-lane path. Shared by both lanes.
fn seal_wire_slice(c: &SessionCrypto, wires: &mut [Vec<u8>], seq_base: u64) -> Result<()> {
for (i, wire) in wires.iter_mut().enumerate() {
c.seal_in_place(seq_base.wrapping_add(i as u64), &mut wire[8..])?;
}
Ok(())
}
/// Accumulated client receive-path stage timings since the last [`Session::take_pump_perf`].
/// Answers "where does the pump core go" at line rate: kernel drain (`recv_ns`) vs AES-GCM
/// (`decrypt_ns`) vs reassembly+FEC (`reasm_ns`, the `Reassembler::push` round-trip including
/// shard copies and block reconstruction). 2026-07-14 sweep context: the pump pegs one core at
/// ~1.5 Gbps wire, ~85% of it userspace — this split is what Phase 2.1 (pooled reassembly) is
/// validated against.
#[derive(Debug, Default, Clone, Copy)]
pub struct PumpPerf {
/// ns inside `recv_batch` (recvmmsg / recvmsg_x), i.e. syscall + kernel copy.
pub recv_ns: u64,
/// ns inside `open_in_place` across all datagrams (AES-128-GCM + replay-window upkeep).
pub decrypt_ns: u64,
/// ns inside `Reassembler::push` (header parse, shard copy, FEC reconstruct, AU assembly).
pub reasm_ns: u64,
/// recv_batch calls (batches) and datagrams processed over the accumulation window.
pub batches: u64,
pub packets: u64,
}
/// Accumulated host send-path stage timings since the last [`Session::take_seal_perf`] (plan
/// Phase 0.4, host half). Answers "where does the send thread go" at rate: FEC parity
/// generation (`fec_ns`, inside [`ErasureCoder::encode_into`]) vs AES-GCM (`seal_ns`,
/// per-packet `seal_in_place`) vs the socket handoff (`sock_ns` — `send_gso`/`sendmmsg`
/// syscalls; the internal submit paths time it here, the paced video path folds its chunk
/// sends in via [`Session::note_sock_ns`]). The Phase 1.5 gate reads off this split: build
/// two-lane seal only if `seal_ns` exceeds ~15% of the send thread at 2 Gbps.
#[derive(Debug, Default, Clone, Copy)]
pub struct SealPerf {
/// ns inside `ErasureCoder::encode_into` (parity generation).
pub fec_ns: u64,
/// ns inside `seal_in_place` across all wire packets (AES-128-GCM).
pub seal_ns: u64,
/// ns inside `send_sealed` (socket syscalls), where the session can see it.
pub sock_ns: u64,
/// Frames sealed and wire packets sealed over the accumulation window.
pub frames: u64,
pub packets: u64,
}
/// [`ErasureCoder`] shim accumulating the time spent in `encode_into` (the send-path FEC
/// stage) — only constructed when `PUNKTFUNK_PERF` armed the session's [`SealPerf`]. The
/// counter is atomic purely to satisfy the trait's `Sync` bound; it lives on one thread.
struct TimedCoder<'a> {
inner: &'a dyn ErasureCoder,
ns: &'a std::sync::atomic::AtomicU64,
}
impl ErasureCoder for TimedCoder<'_> {
fn scheme(&self) -> crate::config::FecScheme {
self.inner.scheme()
}
fn encode(
&self,
data: &[&[u8]],
recovery_count: usize,
) -> std::result::Result<Vec<Vec<u8>>, crate::fec::FecError> {
self.inner.encode(data, recovery_count)
}
fn encode_into(
&self,
data: &[&[u8]],
recovery_count: usize,
out: &mut Vec<Vec<u8>>,
) -> std::result::Result<(), crate::fec::FecError> {
let t0 = std::time::Instant::now();
let r = self.inner.encode_into(data, recovery_count, out);
self.ns.fetch_add(
t0.elapsed().as_nanos() as u64,
std::sync::atomic::Ordering::Relaxed,
);
r
}
fn reconstruct(
&self,
data_count: usize,
recovery_count: usize,
received: &mut [Option<Vec<u8>>],
) -> std::result::Result<Vec<Vec<u8>>, crate::fec::FecError> {
self.inner.reconstruct(data_count, recovery_count, received)
}
fn reconstruct_into(
&self,
recovery_count: usize,
data: &mut [&mut [u8]],
have: &[bool],
recovery: &[(usize, &[u8])],
) -> std::result::Result<(), crate::fec::FecError> {
self.inner
.reconstruct_into(recovery_count, data, have, recovery)
}
}
use perf::TimedCoder;
use replay::{seq_of, ReplayWindow};
use seal::{seal_wire_slice, SealJob, SealLane, TWO_LANE_MIN_PACKETS};
/// Datagrams drained per `recvmmsg` syscall on the client (the reused ring's size). 128 keeps
/// the syscall rate ≤ ~3.4k/s even at the ~430k pkt/s the post-2026-07-14 receive path delivers
@@ -836,102 +691,6 @@ impl Session {
}
}
/// Extract the AEAD-authenticated 8-byte big-endian sequence prefix from a sealed wire datagram.
/// Only called on the encrypted receive path, where a preceding successful open has already
/// established `wire.len() >= 8`.
fn seq_of(wire: &[u8]) -> u64 {
u64::from_be_bytes(wire[..8].try_into().unwrap())
}
/// Depth of the anti-replay window, in sequences. The sender advances its sequence once per
/// datagram, so this must cover the reassembler's 120 ms loss window
/// ([`LOSS_WINDOW_NS`](crate::packet)) at line-rate packet rates — otherwise the replay filter
/// silently re-tightens the "late ≠ lost" fix: a Wi-Fi-retry-delayed shard the reassembler would
/// still use gets dropped here as "older than the window" first (4096 was only ~33 ms at the
/// ~125k pkt/s of a 1 Gbps stream; 32768 topped out around ~2 Gbps — which the client now
/// exceeds: the 2026-07-14 zero-copy + hardware-AES work measured ~4.8 Gbps wire ≈ 430k pkt/s
/// delivered). 131072 covers 120 ms up to ~1.09M pkt/s (≈12 Gbps wire) and is effectively
/// unbounded for the sparse input stream, while still bounding how far back a replay could
/// hide; the bitmap costs 16 KiB per session.
const REPLAY_WINDOW: u64 = 131072;
const REPLAY_WORDS: usize = (REPLAY_WINDOW / 64) as usize;
/// Sliding-window anti-replay filter over the AEAD-authenticated wire sequence. The sender counts
/// its datagrams from 0, and the protocol never legitimately re-sends a sequence (FEC recovery
/// shards get fresh ones), so a sequence seen twice is a replay. The AEAD tag already authenticates
/// the sequence — a forged one can't open — so this only has to reject *duplicates* of validly
/// sealed datagrams (and anything older than the window, which we can no longer prove is fresh).
/// Genuine reordering within the window is accepted. Bitmap-per-sequence, indexed `seq % WINDOW`.
struct ReplayWindow {
/// Highest sequence accepted so far; `seen` stays false until the first datagram.
highest: u64,
seen: bool,
/// One bit per in-window sequence in `(highest - WINDOW, highest]`.
bits: [u64; REPLAY_WORDS],
}
impl ReplayWindow {
fn new() -> ReplayWindow {
ReplayWindow {
highest: 0,
seen: false,
bits: [0; REPLAY_WORDS],
}
}
#[inline]
fn word_bit(seq: u64) -> (usize, u64) {
let idx = (seq % REPLAY_WINDOW) as usize;
(idx / 64, 1u64 << (idx % 64))
}
fn is_set(&self, seq: u64) -> bool {
let (w, b) = Self::word_bit(seq);
self.bits[w] & b != 0
}
fn set(&mut self, seq: u64) {
let (w, b) = Self::word_bit(seq);
self.bits[w] |= b;
}
fn unset(&mut self, seq: u64) {
let (w, b) = Self::word_bit(seq);
self.bits[w] &= !b;
}
/// Record `seq`, returning `true` if it's fresh (accept) or `false` if it's a replay / too old.
fn accept(&mut self, seq: u64) -> bool {
if !self.seen {
self.seen = true;
self.highest = seq;
self.set(seq);
return true;
}
if seq > self.highest {
// Advance the window. Sequences between the old and new high slide in unseen, so clear
// their (possibly stale, from a full window ago) slots — unless we jumped an entire
// window, in which case wipe the bitmap wholesale.
if seq - self.highest >= REPLAY_WINDOW {
self.bits = [0; REPLAY_WORDS];
} else {
let mut s = self.highest + 1;
while s < seq {
self.unset(s);
s += 1;
}
}
self.highest = seq;
self.set(seq);
true
} else if self.highest - seq >= REPLAY_WINDOW || self.is_set(seq) {
// Older than the window (can't prove it isn't a replay) or already seen (a duplicate) —
// either way, drop it.
false
} else {
self.set(seq); // in-window and not yet seen — a genuine reorder
true
}
}
}
#[cfg(test)]
mod wire_equivalence_tests {
use super::*;
@@ -1126,78 +885,3 @@ mod wire_equivalence_tests {
);
}
}
#[cfg(test)]
mod replay_tests {
use super::*;
#[test]
fn accepts_in_order_and_rejects_duplicates() {
let mut w = ReplayWindow::new();
for seq in 0..1000 {
assert!(w.accept(seq), "fresh in-order seq {seq} must be accepted");
}
// Every one of those is now a replay.
for seq in 0..1000 {
assert!(!w.accept(seq), "replayed seq {seq} must be rejected");
}
}
#[test]
fn accepts_reorder_within_window_once() {
let mut w = ReplayWindow::new();
assert!(w.accept(100));
// Earlier-but-in-window sequences (a genuine reorder) are accepted exactly once.
assert!(w.accept(80));
assert!(!w.accept(80), "second copy of a reordered seq is a replay");
assert!(w.accept(99));
assert!(
!w.accept(100),
"the high-water seq itself can't be replayed"
);
}
#[test]
fn rejects_older_than_window() {
let mut w = ReplayWindow::new();
assert!(w.accept(REPLAY_WINDOW * 2));
// Anything a full window or more behind the high-water mark is dropped (can't prove fresh).
assert!(!w.accept(REPLAY_WINDOW * 2 - REPLAY_WINDOW));
assert!(!w.accept(0));
// But just inside the window is still accepted.
assert!(w.accept(REPLAY_WINDOW * 2 - (REPLAY_WINDOW - 1)));
}
#[test]
fn large_forward_jump_wipes_stale_bits() {
let mut w = ReplayWindow::new();
assert!(w.accept(5));
// Jump far forward (more than a window). The slot for an old seq that aliases 5 mod WINDOW
// must read as unseen afterward, i.e. the jump cleared it — so a NEW seq there is accepted.
let far = 10 * REPLAY_WINDOW + 5;
assert!(w.accept(far));
assert!(
!w.accept(5),
"the pre-jump seq is now far older than the window"
);
// A fresh seq aliasing 5 (mod WINDOW) but inside the new window is accepted, proving the
// stale bit was cleared rather than mistaken for a replay.
assert!(w.accept(far - REPLAY_WINDOW + 1));
}
#[test]
fn first_seq_need_not_be_zero() {
// Startup loss can mean the first datagram we ever open isn't seq 0.
let mut w = ReplayWindow::new();
assert!(w.accept(42));
assert!(!w.accept(42));
assert!(w.accept(43));
}
#[test]
fn seq_of_reads_the_big_endian_prefix() {
let mut wire = 0x0102_0304_0506_0708u64.to_be_bytes().to_vec();
wire.extend_from_slice(b"ciphertext-and-tag");
assert_eq!(seq_of(&wire), 0x0102_0304_0506_0708);
}
}
crates/punktfunk-core/src/session/perf.rs
+98
View File
@@ -0,0 +1,98 @@
//! `PUNKTFUNK_PERF` stage-timing telemetry for the two hot paths: where the client pump
//! and the host send thread actually spend their time, accumulated per report window and
//! drained via [`Session::take_pump_perf`](super::Session::take_pump_perf) /
//! [`Session::take_seal_perf`](super::Session::take_seal_perf).
use crate::fec::ErasureCoder;
/// Accumulated client receive-path stage timings since the last [`Session::take_pump_perf`](super::Session::take_pump_perf).
/// Answers "where does the pump core go" at line rate: kernel drain (`recv_ns`) vs AES-GCM
/// (`decrypt_ns`) vs reassembly+FEC (`reasm_ns`, the `Reassembler::push` round-trip including
/// shard copies and block reconstruction). 2026-07-14 sweep context: the pump pegs one core at
/// ~1.5 Gbps wire, ~85% of it userspace — this split is what Phase 2.1 (pooled reassembly) is
/// validated against.
#[derive(Debug, Default, Clone, Copy)]
pub struct PumpPerf {
/// ns inside `recv_batch` (recvmmsg / recvmsg_x), i.e. syscall + kernel copy.
pub recv_ns: u64,
/// ns inside `open_in_place` across all datagrams (AES-128-GCM + replay-window upkeep).
pub decrypt_ns: u64,
/// ns inside `Reassembler::push` (header parse, shard copy, FEC reconstruct, AU assembly).
pub reasm_ns: u64,
/// recv_batch calls (batches) and datagrams processed over the accumulation window.
pub batches: u64,
pub packets: u64,
}
/// Accumulated host send-path stage timings since the last [`Session::take_seal_perf`](super::Session::take_seal_perf) (plan
/// Phase 0.4, host half). Answers "where does the send thread go" at rate: FEC parity
/// generation (`fec_ns`, inside [`ErasureCoder::encode_into`]) vs AES-GCM (`seal_ns`,
/// per-packet `seal_in_place`) vs the socket handoff (`sock_ns` — `send_gso`/`sendmmsg`
/// syscalls; the internal submit paths time it here, the paced video path folds its chunk
/// sends in via [`Session::note_sock_ns`](super::Session::note_sock_ns)). The Phase 1.5 gate reads off this split: build
/// two-lane seal only if `seal_ns` exceeds ~15% of the send thread at 2 Gbps.
#[derive(Debug, Default, Clone, Copy)]
pub struct SealPerf {
/// ns inside `ErasureCoder::encode_into` (parity generation).
pub fec_ns: u64,
/// ns inside `seal_in_place` across all wire packets (AES-128-GCM).
pub seal_ns: u64,
/// ns inside `send_sealed` (socket syscalls), where the session can see it.
pub sock_ns: u64,
/// Frames sealed and wire packets sealed over the accumulation window.
pub frames: u64,
pub packets: u64,
}
/// [`ErasureCoder`] shim accumulating the time spent in `encode_into` (the send-path FEC
/// stage) — only constructed when `PUNKTFUNK_PERF` armed the session's [`SealPerf`]. The
/// counter is atomic purely to satisfy the trait's `Sync` bound; it lives on one thread.
pub(super) struct TimedCoder<'a> {
pub(super) inner: &'a dyn ErasureCoder,
pub(super) ns: &'a std::sync::atomic::AtomicU64,
}
impl ErasureCoder for TimedCoder<'_> {
fn scheme(&self) -> crate::config::FecScheme {
self.inner.scheme()
}
fn encode(
&self,
data: &[&[u8]],
recovery_count: usize,
) -> std::result::Result<Vec<Vec<u8>>, crate::fec::FecError> {
self.inner.encode(data, recovery_count)
}
fn encode_into(
&self,
data: &[&[u8]],
recovery_count: usize,
out: &mut Vec<Vec<u8>>,
) -> std::result::Result<(), crate::fec::FecError> {
let t0 = std::time::Instant::now();
let r = self.inner.encode_into(data, recovery_count, out);
self.ns.fetch_add(
t0.elapsed().as_nanos() as u64,
std::sync::atomic::Ordering::Relaxed,
);
r
}
fn reconstruct(
&self,
data_count: usize,
recovery_count: usize,
received: &mut [Option<Vec<u8>>],
) -> std::result::Result<Vec<Vec<u8>>, crate::fec::FecError> {
self.inner.reconstruct(data_count, recovery_count, received)
}
fn reconstruct_into(
&self,
recovery_count: usize,
data: &mut [&mut [u8]],
have: &[bool],
recovery: &[(usize, &[u8])],
) -> std::result::Result<(), crate::fec::FecError> {
self.inner
.reconstruct_into(recovery_count, data, have, recovery)
}
}
crates/punktfunk-core/src/session/replay.rs
+175
View File
@@ -0,0 +1,175 @@
//! Sliding-window anti-replay filter over the AEAD-authenticated wire sequence
//! (plan §1). Applied on both encrypted receive paths —
//! [`Session::poll_frame`](super::Session::poll_frame) and
//! [`Session::poll_input`](super::Session::poll_input).
/// Extract the AEAD-authenticated 8-byte big-endian sequence prefix from a sealed wire datagram.
/// Only called on the encrypted receive path, where a preceding successful open has already
/// established `wire.len() >= 8`.
pub(super) fn seq_of(wire: &[u8]) -> u64 {
u64::from_be_bytes(wire[..8].try_into().unwrap())
}
/// Depth of the anti-replay window, in sequences. The sender advances its sequence once per
/// datagram, so this must cover the reassembler's 120 ms loss window
/// ([`LOSS_WINDOW_NS`](crate::packet)) at line-rate packet rates — otherwise the replay filter
/// silently re-tightens the "late ≠ lost" fix: a Wi-Fi-retry-delayed shard the reassembler would
/// still use gets dropped here as "older than the window" first (4096 was only ~33 ms at the
/// ~125k pkt/s of a 1 Gbps stream; 32768 topped out around ~2 Gbps — which the client now
/// exceeds: the 2026-07-14 zero-copy + hardware-AES work measured ~4.8 Gbps wire ≈ 430k pkt/s
/// delivered). 131072 covers 120 ms up to ~1.09M pkt/s (≈12 Gbps wire) and is effectively
/// unbounded for the sparse input stream, while still bounding how far back a replay could
/// hide; the bitmap costs 16 KiB per session.
const REPLAY_WINDOW: u64 = 131072;
const REPLAY_WORDS: usize = (REPLAY_WINDOW / 64) as usize;
/// Sliding-window anti-replay filter over the AEAD-authenticated wire sequence. The sender counts
/// its datagrams from 0, and the protocol never legitimately re-sends a sequence (FEC recovery
/// shards get fresh ones), so a sequence seen twice is a replay. The AEAD tag already authenticates
/// the sequence — a forged one can't open — so this only has to reject *duplicates* of validly
/// sealed datagrams (and anything older than the window, which we can no longer prove is fresh).
/// Genuine reordering within the window is accepted. Bitmap-per-sequence, indexed `seq % WINDOW`.
pub(super) struct ReplayWindow {
/// Highest sequence accepted so far; `seen` stays false until the first datagram.
highest: u64,
seen: bool,
/// One bit per in-window sequence in `(highest - WINDOW, highest]`.
bits: [u64; REPLAY_WORDS],
}
impl ReplayWindow {
pub(super) fn new() -> ReplayWindow {
ReplayWindow {
highest: 0,
seen: false,
bits: [0; REPLAY_WORDS],
}
}
#[inline]
fn word_bit(seq: u64) -> (usize, u64) {
let idx = (seq % REPLAY_WINDOW) as usize;
(idx / 64, 1u64 << (idx % 64))
}
fn is_set(&self, seq: u64) -> bool {
let (w, b) = Self::word_bit(seq);
self.bits[w] & b != 0
}
fn set(&mut self, seq: u64) {
let (w, b) = Self::word_bit(seq);
self.bits[w] |= b;
}
fn unset(&mut self, seq: u64) {
let (w, b) = Self::word_bit(seq);
self.bits[w] &= !b;
}
/// Record `seq`, returning `true` if it's fresh (accept) or `false` if it's a replay / too old.
pub(super) fn accept(&mut self, seq: u64) -> bool {
if !self.seen {
self.seen = true;
self.highest = seq;
self.set(seq);
return true;
}
if seq > self.highest {
// Advance the window. Sequences between the old and new high slide in unseen, so clear
// their (possibly stale, from a full window ago) slots — unless we jumped an entire
// window, in which case wipe the bitmap wholesale.
if seq - self.highest >= REPLAY_WINDOW {
self.bits = [0; REPLAY_WORDS];
} else {
let mut s = self.highest + 1;
while s < seq {
self.unset(s);
s += 1;
}
}
self.highest = seq;
self.set(seq);
true
} else if self.highest - seq >= REPLAY_WINDOW || self.is_set(seq) {
// Older than the window (can't prove it isn't a replay) or already seen (a duplicate) —
// either way, drop it.
false
} else {
self.set(seq); // in-window and not yet seen — a genuine reorder
true
}
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn accepts_in_order_and_rejects_duplicates() {
let mut w = ReplayWindow::new();
for seq in 0..1000 {
assert!(w.accept(seq), "fresh in-order seq {seq} must be accepted");
}
// Every one of those is now a replay.
for seq in 0..1000 {
assert!(!w.accept(seq), "replayed seq {seq} must be rejected");
}
}
#[test]
fn accepts_reorder_within_window_once() {
let mut w = ReplayWindow::new();
assert!(w.accept(100));
// Earlier-but-in-window sequences (a genuine reorder) are accepted exactly once.
assert!(w.accept(80));
assert!(!w.accept(80), "second copy of a reordered seq is a replay");
assert!(w.accept(99));
assert!(
!w.accept(100),
"the high-water seq itself can't be replayed"
);
}
#[test]
fn rejects_older_than_window() {
let mut w = ReplayWindow::new();
assert!(w.accept(REPLAY_WINDOW * 2));
// Anything a full window or more behind the high-water mark is dropped (can't prove fresh).
assert!(!w.accept(REPLAY_WINDOW * 2 - REPLAY_WINDOW));
assert!(!w.accept(0));
// But just inside the window is still accepted.
assert!(w.accept(REPLAY_WINDOW * 2 - (REPLAY_WINDOW - 1)));
}
#[test]
fn large_forward_jump_wipes_stale_bits() {
let mut w = ReplayWindow::new();
assert!(w.accept(5));
// Jump far forward (more than a window). The slot for an old seq that aliases 5 mod WINDOW
// must read as unseen afterward, i.e. the jump cleared it — so a NEW seq there is accepted.
let far = 10 * REPLAY_WINDOW + 5;
assert!(w.accept(far));
assert!(
!w.accept(5),
"the pre-jump seq is now far older than the window"
);
// A fresh seq aliasing 5 (mod WINDOW) but inside the new window is accepted, proving the
// stale bit was cleared rather than mistaken for a replay.
assert!(w.accept(far - REPLAY_WINDOW + 1));
}
#[test]
fn first_seq_need_not_be_zero() {
// Startup loss can mean the first datagram we ever open isn't seq 0.
let mut w = ReplayWindow::new();
assert!(w.accept(42));
assert!(!w.accept(42));
assert!(w.accept(43));
}
#[test]
fn seq_of_reads_the_big_endian_prefix() {
let mut wire = 0x0102_0304_0506_0708u64.to_be_bytes().to_vec();
wire.extend_from_slice(b"ciphertext-and-tag");
assert_eq!(seq_of(&wire), 0x0102_0304_0506_0708);
}
}
crates/punktfunk-core/src/session/seal.rs
+74
View File
@@ -0,0 +1,74 @@
//! The second seal lane (plan Phase 1.5): a persistent worker thread that AES-GCM-seals
//! the back half of a large frame's wire packets while the send thread seals the front.
//! [`Session`](super::Session)`::seal_frame_inner` owns the split policy; this module owns
//! the lane machinery and the shared per-slice seal loop.
use crate::crypto::SessionCrypto;
use crate::error::Result;
/// Wire-packet count at which a frame's sealing splits across two lanes (plan Phase 1.5):
/// below it the channel rendezvous (~µs) isn't worth it; at it the halved AES-GCM span
/// (≥ ~125 µs of ~1 µs/packet work) dwarfs the hand-off. ≈300 KB of wire, i.e. ≥150 Mbps
/// at 60 fps — small frames and the probe's ~17-packet AUs stay strictly single-lane.
pub(super) const TWO_LANE_MIN_PACKETS: usize = 256;
/// One two-lane seal hand-off: the frame's back-half wire buffers, sealed by the worker with
/// nonces `seq_base + i` (the nonce order is deterministic per shard index, which is what
/// makes the split sound). Round-trips through the channels so the buffers return to the pool.
pub(super) struct SealJob {
pub(super) bufs: Vec<Vec<u8>>,
pub(super) seq_base: u64,
pub(super) timed: bool,
/// Worker-lane CPU ns (when `timed`) and the seal outcome, filled in by the worker.
pub(super) ns: u64,
pub(super) result: Result<()>,
}
/// The persistent second seal lane: a worker thread that AES-GCM-seals the back half of a
/// large frame's packets while the send thread seals the front half. Rendezvous channels
/// (bound 1) — the send thread submits, seals its half, then waits; no per-frame spawn.
/// Dropping the struct closes the channel and the worker exits.
pub(super) struct SealLane {
pub(super) to_worker: std::sync::mpsc::SyncSender<SealJob>,
pub(super) from_worker: std::sync::mpsc::Receiver<SealJob>,
}
impl SealLane {
pub(super) fn spawn(crypto: std::sync::Arc<SessionCrypto>) -> Option<SealLane> {
let (to_worker, jobs) = std::sync::mpsc::sync_channel::<SealJob>(1);
let (done_tx, from_worker) = std::sync::mpsc::sync_channel::<SealJob>(1);
std::thread::Builder::new()
.name("punktfunk-seal2".into())
.spawn(move || {
while let Ok(mut job) = jobs.recv() {
let t0 = job.timed.then(std::time::Instant::now);
job.result = seal_wire_slice(&crypto, &mut job.bufs, job.seq_base);
if let Some(t0) = t0 {
job.ns = t0.elapsed().as_nanos() as u64;
}
if done_tx.send(job).is_err() {
break; // session gone mid-frame — nothing left to seal for
}
}
})
.ok()?;
Some(SealLane {
to_worker,
from_worker,
})
}
}
/// Seal a run of pre-written wire buffers in place: buffer `i` is `seq(8) ‖ plaintext ‖ tag
/// scratch` and seals over `[8..]` with sequence `seq_base + i` — the exact per-packet layout
/// and nonce order of the fused single-lane path. Shared by both lanes.
pub(super) fn seal_wire_slice(
c: &SessionCrypto,
wires: &mut [Vec<u8>],
seq_base: u64,
) -> Result<()> {
for (i, wire) in wires.iter_mut().enumerate() {
c.seal_in_place(seq_base.wrapping_add(i as u64), &mut wire[8..])?;
}
Ok(())
}