Carries the Nym mixnet transport + single-container demo.
Forward-merge adaptation: the Nym end-to-end SOCKS5 send/recv test was
authored against master's IK FMP framing (msg1 wire size 114, version
nibble 0). next uses the XX handshake and FMP v1, so the TCP read path
rejected the test frame (UnknownVersion / HandshakeSizeMismatch),
timing the test out. Adapted build_msg1_frame to next's framing (wire
size 41, ver=1/phase=1 header byte). next-only; master keeps its IK
form.
Add an outbound-only Nym mixnet transport that tunnels FMP peer links
through a local nym-socks5-client SOCKS5 proxy into the Nym mixnet. It
structurally mirrors the Tor SOCKS5 transport (connection pool,
connect-on-send background promotion, FMP-v0 framing reused from TCP)
with the onion, inbound-listener, and control-port machinery removed.
Wires the transport through the full TransportHandle dispatch, NymConfig
(standard transport-instance pattern), and node instantiation, and
surfaces its counters in fipstop. Includes a mock SOCKS5 harness and unit
coverage for the address-parsing paths.
Also adds an isolated single-container example
(examples/sidecar-nostr-mixnet-relay/) demonstrating FIPS peering across
the mixnet end to end. No new crate dependencies: tokio_socks, socket2,
and futures are already pulled in by the Tor transport.
The inbound FilterAnnounce FPR cap rejects filters whose false-positive
rate (fill^k) exceeds the configured maximum. On the fixed 1 KB / k=5
filter, 0.05 corresponds to fill 0.549 (~1,300 reachable entries), and
the busiest nodes' aggregates were beginning to hit that ceiling as the
mesh grew. Raise the default to 0.10 (fill 0.631, ~1,630 entries) to
restore headroom toward the fixed-filter capacity limit. A saturated or
poisoned filter is ~100% FPR and remains rejected, so the antipoison
gate is not materially weakened.
Updates the config default, the config-reference and bloom-filter
design docs, and the changelog.
Ignore duplicate or counter-regressed ReceiverReports before updating
RTT, loss, goodput, or ETX, so a delayed or reordered report can no
longer poison link metrics. Compute the RTT-from-echo sample with
checked timestamp arithmetic and reject zero, negative, or out-of-range
results instead of risking wrap or underflow on untrusted wire values.
On the sender side, when receiver dwell time overflows the u16 wire
field, suppress the timestamp echo (send 0) and saturate dwell to
u16::MAX rather than truncating, so a bogus small RTT cannot be formed.
Adds duplicate, out-of-order, wrapped-add, and future-dated (checked_sub)
sample tests, asserts loss and goodput stay unchanged on a dropped
duplicate, and covers the dwell-overflow echo suppression. Documents the
behavior in the MMP design note and CHANGELOG.
Co-authored-by: Johnathan Corgan <johnathan@corganlabs.com>
Two next-line entries had been left describing states that a later commit
reverted. Collapse the XX max_peers early-gate add/remove churn into its
net final state: on the XX handshake an over-cap inbound connection is
rejected solely by the late promotion check (no early gate), logged at
debug. Replace the stale "rekey jitter disabled on next" note with the
actual state: jitter is re-enabled (REKEY_JITTER_SECS = 15) and the three
XX rekey-path divergence defects that had blocked it are fixed
(authenticated-decrypt cutover instead of bare K-bit, msg3 retransmission
with per-link rekey serialization, and a jitter-aware handle_msg3
session-age partition). Merged-in IK-line entries are left untouched.
Record the changes that landed since the last changelog update: the
dual-auto_connect traversal-session election, the FMP link-layer rekey
reliability fixes (bounded msg1 retransmission with rekey-aware
heartbeat, and authenticate-before-cutover), the in-process loopback
test transport and progress-aware convergence wait that remove CI flake
classes, the local/GitHub CI suite-parity and single-source toolchain
selection, and the packaging change shipping the config as an example
that postinst seeds when absent.
At the inbound peer cap the XX FMP handshake had two cap checks: an early
gate in handle_msg3 and the late promote_connection check. On XX the
peer's identity is not known until the third handshake message, by which
point all three messages have already crossed the wire, so the early gate
saved no wire bytes and governed exactly the same net-new-peer set as the
late check (known and pending-outbound peers return earlier via the
cross-connection paths). Remove the early gate and rely on the promotion
check, and log the resulting MaxPeersExceeded rejection at debug instead
of warn so a cap'd node under sustained inbound pressure does not emit
WARN spam for expected policy rejections.
Re-enable the two previously-ignored inbound-cap unit tests, rewritten to
drive a full XX three-message handshake and assert the path-agnostic
invariant (no promotion over cap, peer count unchanged, no
connection/link/index leak) plus the known-peer reconnect bypass.
Update the admission-cap integration suite's enforcement-event
discriminator to match: drop the removed early-gate string and count the
new debug-level promotion-cap rejection.
Store node counters in an atomic metric registry read through &self, and
introduce a shared NodeContext bundle holding the effectively-immutable
fields (config, identity, startup epoch, node profile, capability limits).
Source the immutable config and identity reads across the receive hot
path, the XX handshake/session/rekey state machines, and the discovery,
tree, bloom, retry, and lifecycle modules through the context accessors.
Includes the bloom delta/full/NACK/resize and byte-total counters in the
registry. The Node fields and the context are rebuilt in lockstep at every
mutation site.
Store node counters in an atomic metric registry read through &self, and
introduce a shared NodeContext bundle holding the effectively-immutable
fields (config, identity, startup epoch, capability limits). Source the
immutable config and identity reads across the receive hot path, the
handshake/session/mmp/encrypted state machines, and the discovery, tree,
bloom, retry, and lifecycle modules through the context accessors rather
than direct field reads. The Node fields and the context are rebuilt in
lockstep at every mutation site.
PeerRecvDrain::drop previously called std::thread::join on the worker
thread synchronously. The worker uses packet_tx.blocking_send on a
tokio mpsc Sender, which internally parks the worker via
tokio::block_on on the same current_thread runtime that drives
rx_loop. Calling join from inside remove_active_peer (which runs on
the runtime thread, the runtime's sole driver) created a circular
wait:
- rx_loop blocks in libc futex via Thread::join
- the worker being joined cannot observe the stop flag because the
runtime that polls it is the very thread now blocked joining it
- all other PeerRecvDrain workers park on the same runtime via
block_on, so a single peer's removal wedges every worker on the
daemon
The /proc snapshot from a production wedge showed exactly this
shape: 107 of 108 threads in futex_do_wait, 101 of them named
fips-peer-drain. fipsctl became unresponsive (EAGAIN on control
socket), SIGTERM was ignored, and Docker SIGKILLed the container
after the 10 s grace period. Two confirmed wedges on the public
test deployment (52 min and 23 min uptime), plus a third on the
admission-gate-Msg2-silent-drop build at 2 min 21 sec — all ending
with the identical "Peer removed and state cleaned up
tree_changed=false" final log line preceding total silence.
Fix: detach the std::thread instead of joining. The stop flag plus
self-pipe write already signal the worker to exit; the worker's
kernel-level libc::poll inside the drain loop sees the wake, checks
the flag, exits, and the OS reclaims the thread state independently
of the JoinHandle being dropped.
The trigger was statistically amplified by aggressive multi-npub-
from-one-NAT peer reconnect patterns at the moment of the 30 s
link-dead-timeout peer-removal, but not bounded to them. Any
peer whose disconnect happens with the per-peer drain worker
parked in block_on can fire the bug. The admission-gate work
that landed earlier in this branch line compressed more handshake
work per rx_loop tick, increasing the rate at which workers are
parked in block_on and so reducing time-to-wedge — but the
underlying bug pre-dated the admission gate and pre-dated this
fix branch.
The deployed wedged daemon is mitigated operationally by blocking
the trigger IP at the host firewall; this commit removes the bug
class entirely.
Bring master's runtime peer-list refresh, opt-in mDNS LAN discovery, and
the receive-path reject-reason / reloadable-config refactor into the XX
handshake integration branch. The peer-restart-epoch detection and
stale-FSP-session teardown authored against Noise IK are re-authored onto
the Noise XX rekey path: complete_rekey_msg2 now also surfaces the remote
startup epoch, and the stale session is cleared once the XX rekey
completes (after msg3 is sent). Connect-budget and path-refresh work is
threaded through the XX anonymous-discovery branch.
Bring the runtime peer-list refresh and opt-in mDNS LAN discovery work
on master into the receive-path RejectReason / reloadable-config
integration branch. Code files auto-merge clean; the only conflict is
the CHANGELOG Unreleased section, resolved as the union of both sets of
entries.
Add scoped mDNS / DNS-SD discovery for peers on the same local link,
giving sub-second pairing without a relay or NAT-traversal roundtrip.
A node advertises its npub, protocol version, and an optional network
scope over link-local multicast, and browses for matching adverts to
initiate Noise handshakes against same-LAN peers.
LAN discovery is disabled by default; operators enable it with
node.discovery.lan.enabled: true. Default-off avoids reintroducing a
per-LAN identity broadcast on nodes that have deliberately disabled
other discovery channels, and avoids any multicast surprise on upgrade.
The startup advertised-port picker now excludes bootstrap transports
and selects a non-bootstrap operational UDP transport with a stable
lowest-id selector, so the advertised port is deterministic across
restarts rather than dependent on HashMap iteration order. This
matches the per-dial transport selection used for discovered peers.
Co-authored-by: Johnathan Corgan <johnathan@corganlabs.com>
Add Node::update_peers for runtime peer-list refresh. It re-derives the
active peer connections from a new peer configuration, adding newly
configured peers and removing those no longer present, while keeping
links to peers that remain in the set rather than tearing every
connection down. The call returns an UpdatePeersOutcome summarizing the
added, removed, and retained peers.
PeerAddress gains a seen_at_ms recency field (with_seen_at_ms). Active
path selection now sorts address candidates by recency so the most
recently observed address wins when concurrent path probes race.
complete_rekey_msg2 now returns the remote peer's startup epoch
alongside the new Noise session, letting the rekey path detect a peer
restart and clear stale session state. A stale FSP session is cleared
when a peer restart is detected during FMP rekey or cross-connection
promotion, so the session-layer map no longer lingers out of sync with
the freshly promoted peer.
Per-tick work budgets bound the connection churn in a single node tick
(MAX_DISCOVERY_CONNECTS_PER_TICK, MAX_RETRY_CONNECTIONS_PER_TICK,
MAX_PARALLEL_PATH_CANDIDATES_PER_PEER); work beyond a tick's budget is
deferred to the next tick rather than discarded.
Co-authored-by: Johnathan Corgan <johnathan@corganlabs.com>
The admission-cap suite asserted IK wire sizes (inbound Msg1 len 84,
outbound Msg2 len 104) to verify the inbound max_peers cap. On the XX
handshake those sizes differ and Msg2 is always sent before identity is
known, so the IK discriminator matched nothing and the suite failed
despite the cap working correctly.
Replace the wire-size discriminator with a protocol-agnostic cap-holds
invariant: each denied peer must keep re-initiating handshakes
(sustained inbound, size-agnostic), no denied peer may be promoted to an
active session, the node must log cap-enforcement events, and the capped
node must hold exactly max_peers. Raise node-c's handshake logging to
debug in the mesh profile so the early-gate drop is visible alongside the
late-check rejection.
Also record in the changelog that for peers the node also dials, the cap
is enforced by the retained late check rather than the early msg3 drop.
Adapt the typed RejectReason coverage to the Noise XX handshake: wire the
msg1/msg2/msg3 state-machine rejection sites in handlers/handshake.rs and
the rekey-initiator outbound sites in handlers/rekey.rs, and add the
XX-specific HandshakeStats counters. The shared RejectReason scaffold and
the branch-agnostic clusters come from the merged refactor-hotpath work;
this commit carries only the next-side delta.
Introduce a typed RejectReason enum and a NodeStats::record_reject
dispatch so every receive-path rejection-and-return site bumps a
machine-readable per-subsystem counter while keeping its operator-facing
log line. The top-level variants mirror the existing NodeStats subsystem
split (Tree, Bloom, Discovery, Forwarding) and add Handshake, Session,
Mmp, and Transport categories; HandshakeStats, SessionStats, and MmpStats
are new sub-stats.
Wired clusters: tree and MMP outbound sign-failure; the FSP session
unknown-session and state-machine cluster; the Noise IK handshake
state-machine cluster (msg1/msg2); and the decode / crypto / cap /
semantic tail across bloom, discovery, forwarding, mmp, and tree. The
TreeStats::ancestry_invalid counter, present since the scaffold but never
incremented, is now bumped from the validate_semantics ancestry rejection.
Several handshake, MMP, tree, and discovery paths that previously had no
counter at all are now counted, including the send_lookup_response
no-route drop (DiscoveryStats::resp_no_route).
Existing direct counters at the bloom / discovery / forwarding sites are
retained alongside the new dispatch while the rollout is in progress (the
bloom_poison tests expect the transitional +2 delta); a later change
collapses the duplicate increment.
Add per-direction pool_inbound/pool_outbound counters to TcpStats and
TorStats, updated at every pool-insert, receive-loop-exit, transport-stop,
and send-failure removal site. Compare the max_inbound_connections cap
against pool_inbound rather than the combined pool length, so outbound
connect-on-send connections no longer consume the operator-facing inbound
budget. The configuration field name and operator semantics are preserved;
only the cap-check comparison and accounting change.
Carries the inbound max_peers admission-cap silent-drop work from
master across the IK→XX structural boundary.
On master (Noise IK), the gate fires at handle_msg1 after the peer's
identity is extracted from the IK msg1 payload, before Msg2 is built
and sent. Wire savings of Msg2 (~104 B) plus the responder crypto
per cap-denied attempt motivate the gate placement.
On next (Noise XX), peer identity is not learned until msg3, by
which point Msg1, Msg2, and Msg3 have all crossed the wire. The IK
gate's wire-savings rationale does not apply on XX. The equivalent
gate is placed in handle_msg3 after the peer's static-key + signature
verification (identity now known) and before promote_connection
(ActivePeer construction, peers_by_index insert, link transition).
The value on XX is local CPU / allocation savings and cleaner peer-
side semantics: no fake-promotion whose subsequent data frames fail
decryption on this side, replaced by a silent drop the peer's
existing auto-reconnect backoff handles cleanly.
Bypass logic is the same as the IK version: known-active peers
(reconnect / cross-connection / restart) and pending-outbound peers
skip the cap so admitting them doesn't grow peers.len(). The late
cap check inside promote_connection is intentionally retained as
defense-in-depth.
Cleanup ordering for the gate's silent-drop path corrects a latent
issue in the adjacent msg3-processing-failure path: our_index is
captured before the connection is removed so the allocator slot is
actually freed (the pre-existing path's get-after-remove returns
None, leaking the index).
The two IK-shaped unit tests at handle_msg1 are marked #[ignore] on
this branch with reason. Their wire-bytes discriminator ("Msg2 must
NOT be sent at cap") is structurally false on XX, and the XX-shaped
equivalents need full three-message-handshake test scaffolding that
isn't authored here. XX-adapted unit + integration test coverage for
the handle_msg3 gate is a follow-up.
CHANGELOG [Unreleased] entry adjusted to describe the handle_msg3
placement on this branch (preserving the master-side framing on the
mainline-merge half of the entry would have been misleading on this
branch).
Three conflicts auto-resolved: the structural handshake.rs span
(~253 lines, IK identity-tied logic discarded on this branch's XX
msg1 path), and three textual ci-local.sh conflicts (admission-cap
suite list / dispatch added alongside the existing mixed-profile
suite list / dispatch).
Move the max_peers cap check in handle_msg1 forward, from the late
check inside promote_connection (which fires after Msg2 has already
been built and put on the wire) to an early position after identity
verification but before index allocation and the Msg2 send. When the
gate fires for a net-new identity, the Msg1 is silent-dropped — no
response goes back to the peer, no AEAD compute or wire bytes are
spent.
Bypass preserved for known peers (reconnect / cross-connection): if
the sender's NodeAddr is already in self.peers, or if a pending
outbound connection is in flight to the same identity, the gate is
skipped so legitimate maintenance traffic continues to work. The
late check inside promote_connection is intentionally retained as
defense-in-depth against future call sites or a disconnect racing
between the early-gate decision and promotion.
Wire-cost rationale: a 45 s tcpdump at saturation observed ~3.6
cap-denials/s steady-state, each previously paying the full Noise IK
responder crypto + Msg2 (~104 B) on the wire before being rejected.
The bigger value is cleaner peer-side semantics — the peer no longer
sees a fake-completed handshake whose data frames subsequently fail
decryption locally.
Two new unit tests cover the cases:
- handle_msg1_silent_drops_at_cap_for_new_peer drives a wire-pumped
Msg1 from a fresh identity into a saturated node and asserts no
Msg2 reaches the sender socket. Stash-verifies as FAIL on the
pre-fix tree (Msg2 hits the wire) and PASS post-fix.
- handle_msg1_admits_existing_peer_at_cap drives a Msg1 from an
identity already in self.peers and asserts the gate does not evict
it. This is a regression check (the no-gate tree behaves the same
way here, but the test guards against an accidental future gate
that breaks known-peer admit).
Brings two structural fixes landed on maint:
- compute_mesh_size: explicit parent skip in the children loop, so the
disjoint-subtree invariant no longer depends on peer_declaration cache
freshness.
- max_peers: outbound connection-initiation gated on the cap (auto-reconnect
retries, Nostr-mediated discovery established adoption, and both sides
of the NAT-traversal punch sequence). Inbound msg1 admission gate
unchanged.
node.limits.max_peers was honored only on inbound msg1 admission
(handshake.rs handle_msg1 returns PeerLimitExceeded when peers.len
is at the cap). Four outbound initiation paths proceeded unconditionally
at capacity: auto-reconnect retries (process_pending_retries),
Nostr-mediated discovery's BootstrapEvent::Established adoption
(poll_nostr_discovery), NAT-traversal punch initiation (the outgoing
side of the offer/answer/punch sequence in the Nostr discovery
runtime), and NAT-traversal punch response (the incoming side of the
same sequence). A saturated node burned CPU, UDP probes, STUN
observations, and Nostr relay traffic on connections that the inbound
gate would reject the moment they reached msg1.
Introduce Node::outbound_admission_check (peers.len < max_peers, or
true when max_peers == 0 as the no-cap sentinel) and gate the four
paths. The discovery runtime lives in a separate task and does not
hold a Node reference; bridge via an Arc<AtomicBool> the runtime
reads and Node refreshes once per tick from outbound_admission_check.
The atomic granularity is intentionally loose: one-tick lag is
acceptable because the inbound msg1 gate continues to be the
authoritative cap, and in-flight handshakes started below the cap
are allowed to complete.
Inbound gate at handshake.rs is unchanged.
The mesh-size estimator's children loop relied on the cached
peer_declaration(parent_id).parent_id() != my_addr check to exclude
the parent. That cached view briefly disagrees with our own latest
my_declaration().parent_id() during the window between a local
parent-switch and the new parent's next inbound TreeAnnounce: the
peer-declaration cache still names us as the parent's parent, so the
parent is iterated as if it were a child and its (typically dominant)
bloom cardinality is added a second time. Symptom: estimated mesh size
displayed in fipsctl show status and fipstop nearly-but-not-exactly
doubles during tree rebalancing.
Make the invariant structural with an explicit peer_addr == parent_id
skip at the head of the children loop. Per-peer 500 ms rate-limiter
and overall recompute cadence are unchanged.
Adds a regression test that constructs the stale-peer-declaration
scenario directly and asserts the parent is not double-counted.
Closes the eventually-consistent gap in spanning-tree state
distribution. Every existing send_tree_announce_to_all call site
gates on a local state-change event (parent switch, self-root
promotion, ancestry change, peer promotion, parent loss). Once a
partition latches — for example a parent-switch announce stranded
in the brief cross-init handshake swap window, where the announce
arrives on a session-index whose decrypt-worker entry has been
unregistered — neither side's state changes again, so neither
side ever re-broadcasts. The existing 60 s check_periodic_parent_reeval
was a re-evaluation, not a re-broadcast: it short-circuited
silently on no-change. Production-side healing depended on
incidental link churn; lab harnesses with stable docker-bridge
links had no equivalent path.
Add a final else branch that fires send_tree_announce_to_all
unconditionally on the no-change path, alongside the existing
switch and self-promote arms. Receivers coalesce by sequence
comparison (ParentDeclaration::is_fresher_than) and short-circuit
at the `if !updated` gate in handle_tree_announce; same-sequence
repeats drop silently with no cascade. The per-peer 500 ms
rate-limiter is well below this 60 s cadence and does not suppress
the heartbeat broadcast.
The fix is a general protocol-robustness improvement: it addresses
any in-flight TreeAnnounce loss class, not only the specific
cross-init swap-window drop site.
testing/static/scripts/rekey-test.sh BASELINE_CONVERGENCE_TIMEOUT
60 -> 65 so a partition healed by the periodic broadcast at T+60
lands inside the convergence window. wait_for_full_baseline
early-exits on PASS, so successful reps see no extra wall-clock.
The tick body's per-peer check_* loops (heartbeats, bloom
announces, MMP reports, tree announces) called transport.send
for every active peer, which on TCP/Tor fell through to a 5 s
connect-on-send wait for any peer whose pool entry was not yet
established. That wedged the entire tick body for the full
connect_timeout_ms per unreachable peer; under post-restart
convergence on a high-peer mesh, this cascaded into multi-
second tick stalls. On master, the same mechanism also starved
the per-tick control-snapshot republish and pushed fipsctl
queries onto an mpsc fallback that was itself queued behind
the wedged rx_loop, producing the 5-second fipsctl head-of-line
pattern operators observed on loaded nodes.
Gate send_encrypted_link_message_with_ce on
transport.connection_state before the send: proceed only when
Connected; on None, kick off a non-blocking background connect
(idempotent — TransportHandle::connect dedupes against the
connecting pool and spawns the timeout-bounded TcpStream::connect
inside its own tokio task) and fail this send fast with a
clear "transport connection not ready" error. A subsequent
tick retries once the pool has an entry. The reconnect
lifecycle (check_link_heartbeats, process_pending_retries,
poll_pending_connects) is unchanged. The connect-on-send
branch in transport.send_async itself remains in place for
code paths that legitimately need synchronous connect (e.g.,
explicit operator-driven fipsctl connect).
When both peers' Nostr-mediated UDP punches complete within the
same scheduling window, each side's `BootstrapEvent::Established`
event arrives with `is_connecting_to_peer` already true: each side
received an inbound msg1 from the peer's pre-punch outbound
attempt, which created a connecting-state record. The deduplication
skip then fires on both sides, neither installs the fresh
traversal socket as canonical, and the peer-adoption budget
(45 s) expires. Cross-node wall-clock alignment of the skip log
line in observed failures was within ~1 ms — simultaneous dual-
fire under contention, the dual-initiation pattern.
Apply the deterministic NodeAddr tie-breaker already used at
`handlers/handshake.rs:269` for rekey dual-initiation and in
`peer::cross_connection_winner` for cross-connection resolution.
Smaller NodeAddr wins as adopter: enumerate the in-flight
connections whose `expected_identity` points at this peer, tear
them down via the canonical `cleanup_stale_connection` helper, and
fall through to `adopt_established_traversal`. Larger NodeAddr
loses and keeps the existing `continue` semantics; the loser's
in-flight outbound is reconciled by `handle_msg1`'s cross-
connection logic when the winner's fresh msg1 arrives over the
adopted socket.
`cleanup_stale_connection` visibility bumped from module-private
to `pub(in crate::node)` so it is callable from `lifecycle.rs`.
The defensive re-check inside `adopt_established_traversal`
itself is left as-is — after the outer cleanup the winner reaches
it with `is_connecting_to_peer == false`, so the inner skip
won't trip. The `BootstrapEvent::Failed` arm is unchanged: there
is no winning outcome on dual failure, and the existing skip +
retry-schedule semantics are correct.
An FSP session rekey could leave the two endpoints holding different
key sets for a brief window: if a handshake message was lost in
transit, one side rotated to the new keys while the other did not.
Traffic sealed in one key epoch then reached a peer still on the
other epoch and failed to decrypt, producing bursts of AEAD
decryption failures and dropped connectivity until a later rekey
cycle reconverged the pair. Choreographing the cutover order cannot
close this window: any fixed ordering still leaves a skew that
packet reordering widens.
Make rekey correctness independent of cutover timing by overlapping
the key epochs on the receive path. During a rekey transition the
receiver trial-decrypts each frame against every live session it
holds: current, the not-yet-promoted pending session, and the
draining previous session. The K-bit becomes a hint that orders the
trial-decrypt cascade rather than a hard gate, and a frame that
authenticates against the pending session is itself the cutover
signal. No rotation ordering and no packet reordering can then cause
a decryption failure.
The pre-rekey Noise session is held in the `previous` slot until the
peer has demonstrably moved off it. Its drain deadline is anchored
on the most recent frame the peer authenticated against that slot,
refreshed each time the trial-decrypt cascade lands there, rather
than on a fixed wall-clock timer started unilaterally at the local
cutover. A peer that never received the new keys keeps authenticating
against `previous` and the slot stays live; without this, a fixed
timer would erase the only key set that could decrypt the peer's
frames, producing a permanent silent decrypt failure on a live data
path. A peer that never catches up is handled by the existing FSP
session liveness path rather than by silent decrypt failure.
The lost-handshake liveness gap is closed separately by retransmitting
the third rekey handshake message until the peer is confirmed on the
new keys, with a bounded retry budget after which the rekey cycle is
cleanly abandoned and retried on the next timer.
Adds unit tests covering the trial-decrypt cascade (epoch selection,
promotion on pending decrypt, reordered old-epoch stragglers after
cutover, per-slot replay-window integrity), the msg3 retransmission
lifecycle, and the peer-progress-aware drain retirement.
Forward-merges PR #91 (off-task encrypt/decrypt worker pools, GSO,
connected UDP), the macOS #102 package-integrity fix, and the AUR
#98 fips-dns fix from master.
Six textual conflicts resolved: wire/noise imports, the K-bit-flip
and rekey-cutover handlers, ActivePeer fields, and an advert test
fixture. One semantic conflict: PR #91's worker-pool code on master
referenced FLAG_SP and MmpPeerState.spin_bit, which next removed in
4aded9a2 (spin bit superseded by the MMP receiver-report timestamp
echo; FMP flags bit 2 reclaimed). The worker acceleration and its
fmp_flags round-trip test are kept; the spin-bit references are
dropped to honor next's wire-format change.