Source OnDataPathRekeyed from the WGWatcher's per-handshake callback
(onWGCheckSuccess), which fires only on a fresh handshake, and OnDataPathDown
from the handshake-timeout path. A fresh handshake clocks the next chained
KEM exchange pushed over the data-path UDP transport.
Learn the peer's data-path endpoint from the signalling offer/answer: its WG
overlay IP combined with the advertised pq UDP port (SetRemotePort -> AddPeer).
Registering here is safe before the tunnel is up because sends only ever fire
once it is (clocked by OnDataPathRekeyed). RemovePeer is wired at peer teardown
(engine.removePeer), not on transient disconnect.
We clock the next Offer initiation to the OnDataPathRekeyed, so we have 2 minutes
ahead of us to do our attempts and stuff before to give up.
On failure, we will know because we will not receive a new answer.. but more importantly
the wg handshake will fail :D
Define OnDataPathRekeyed event to transition from control plane path to data plane path over the WG tunnel.
Keep confirm ALWAYS on NEW established WG tunnel (posthandshake with rekeying). We keep an active method
irrelevant of the WG handshake (we might decide that the indirect wg handshake is sufficient in the future).
Optimistic commit on responder(when sending answer), while on initiator we set it on getting the answer
- Have just one manager => one lock
- Session state is needed in driver to => we have it available now.
- Isomorphically align to rosenpass components and functionality
File Role rosenpass equivalent
kem.go primitive pure X25519MLKEM768 crypto.go/handshake
message.go Offer/Answer/Confirm + Encode/Decode messages.go
manager.go Manager stateful, single lock server logic
callbacks.go WGCallbackHandler (seam output) Handler
Transport (interfaccia) seam trasporto pluggable Conn
## Describe your changes
Under lazy connections, when a routing peer goes idle its WireGuard peer
is torn down and re-created with a wake endpoint by
the activity listener, carrying only the overlay /32
(`peerCfg.AllowedIPs`). The routed subnet prefixes are dropped from
the device on the Connected→Idle transition.
They are meant to be restored by the route watcher, which reacts to the
peer's status change and calls `recalculateRoutes` →
`AddAllowedIP`. Two things prevent that from healing the peer:
- `AddAllowedIP` uses `update_only`, which is a silent no-op (no error)
when the peer does not exist. While the peer is
being torn down and re-armed with its wake endpoint, it is briefly
absent, so a re-add that lands in that window is lost.
- The allowed-IP refcounter only calls its add function on a prefix's
0→1 transition. The routed prefix stays referenced
across the idle cycle, so once the device entry is gone the refcounter
does not re-push it on its own, and nothing retries.
As a result, traffic to the routed subnet is black-holed while the peer
is idle. Because the wake endpoint only fires when a
packet matches the peer's AllowedIPs, a packet to the subnet is dropped
before reaching the wake endpoint, so it cannot
wake the peer. The peer only recovers when woken by other means (e.g. a
ping to its overlay IP).
## Approach
This change keeps the existing Connected→Idle transition as-is and
reconciles the AllowedIPs afterwards, avoiding any
additional locking on the transition path. The peer is torn down and
re-armed with its wake endpoint as today; the routed
prefixes are then re-applied from the route manager's allowed-IP
refcounter once the wake endpoint has been (re)armed.
A single add-only method, `ReconcilePeerAllowedIPs(peerKey)`, re-applies
every routed prefix currently tracked for the peer
in the refcounter (the authoritative store; it already covers static,
dynamic and dnsinterceptor routes). It runs whenever
the peer's wake endpoint is (re)created in the lazy manager — every
point where the activity listener builds it with the
overlay /32 only:
- **initial registration** (`AddPeer`, cold start): the route manager
may have already pushed the peer's routes before the
wake endpoint existed, so those `AddAllowedIP` calls no-op'd; the
reconcile installs them on the freshly created wake
endpoint.
- **the two paths into idle** (`DeactivatePeer` on a remote GOAWAY,
`onPeerInactivityTimedOut` on local inactivity): the
peer is torn down and re-armed, so the routed prefixes must be
re-applied.
In every case the routed prefixes end up on the wake endpoint, so
traffic to a routed subnet can wake the peer. Arming the
wake endpoint and reconciling are wrapped in a single
`armActivityListener` helper so the two always happen together.
New helper: `refcounter.Counter.KeysMatching(pred)` to enumerate a
peer's prefixes under the counter lock.
Note on scope: the reconcile restores what the refcounter tracks. All
routed AllowedIPs currently go through it, so this
covers the routed-prefix case; it does not attempt to reconcile
AllowedIPs installed outside the refcounter. The
Idle→Connected (wake) path does not need this: the peer is not removed
there (the listener close leaves it in place and only
the endpoint is updated), so a concurrent `AddAllowedIP` lands normally.
## Testing
Reproduced deterministically in a local dev setup (userspace client,
`NB_WG_KERNEL_DISABLED=true`, `B_LAZY_CONN_INACTIVITY_THRESHOLD=1`
inactivity threshold 1
min). A temporary 30s sleep in the tear-down → re-arm window widens the
race so the route watcher's async `AddAllowedIP`
reliably lands while the peer is absent and no-ops (the sleep is a test
aid, not part of the change):
- **without the reconcile:** after the peer goes idle, a ping to any
routed IP — both a pre-existing route and one added
during the window — black-holes; the peer never wakes.
- **with the reconcile:** the same ping wakes the peer and passes.
Added unit tests: `ReconcilePeerAllowedIPs` (re-applies all of a peer's
tracked prefixes, scoped to that peer) and
`refcounter.Counter.KeysMatching`.
Note: `netbird status -d` is not a reliable signal for this —
`AddPeerStateRoute` records the route regardless of whether
the underlying `AddAllowedIP` no-op'd, so it reflects the route
manager's intent rather than device state. The reliable
signal is functional (ping the subnet from idle).
## Checklist
- [x] Is it a bug fix
- [ ] Is a typo/documentation fix
- [ ] Is a feature enhancement
- [ ] It is a refactor
- [x] Created tests that fail without the change (unit tests for the
reconcile + `KeysMatching`)
## Documentation
- [x] Documentation is **not needed** for this change (internal client
behavior, no API / gRPC / CLI / flag change)
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<!-- This is an auto-generated comment: release notes by coderabbit.ai
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## Summary by CodeRabbit
* **Bug Fixes**
* Routed IP assignments are automatically reconciled and restored
whenever a peer’s lazy wake endpoint is armed or re-armed.
* Routed allowed IPs are re-applied after inactivity transitions and
monitoring re-initialization.
* If reconciliation can’t be performed, the client safely skips it; if
reconciliation encounters issues, failures are logged without stopping
connection monitoring.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
