fix(p2p): connection cleanup — 4 fixes for stale/dead connections

PRD 4: Disable IPv6 direct dial/accept temporarily. IPv6 QUIC
handshakes succeed but connections die immediately on datagram
send ("connection lost"). IPv4 candidates work reliably. IPv6
candidates still gathered but filtered at dial time.

PRD 1: Close losing transport after Phase 6 negotiation. The
non-selected transport now gets an explicit QUIC close frame
instead of silently dropping after 30s idle timeout. Prevents
phantom connections from polluting future accept() calls.

PRD 2: Harden accept loop with max 3 stale retries. Stale
connections are explicitly closed (conn.close) and counted.
After 3 stale connections, the accept loop aborts instead of
spinning until the race timeout.

PRD 3: Resource cleanup — close old IPv6 endpoint before
creating a new one in place_call/answer_call. Add Drop impl
to CallEngine so tasks are signalled to stop on ungraceful
shutdown.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
This commit is contained in:
Siavash Sameni
2026-04-12 15:11:50 +04:00
parent 4d66d3769d
commit 29cd23fe39
3 changed files with 70 additions and 45 deletions

View File

@@ -192,43 +192,38 @@ pub async fn race(
}
};
let ep_for_fut = ep.clone();
let v6_ep_for_accept = ipv6_endpoint.clone();
// Phase 7: IPv6 accept temporarily disabled (same reason
// as dial — IPv6 connections die on datagram send).
// Accept on IPv4 shared endpoint only.
let _v6_ep_unused = ipv6_endpoint.clone();
direct_fut = Box::pin(async move {
// Accept loop: retry if we get a stale/closed
// connection from a previous call. Between rapid
// successive calls, quinn's accept queue may
// contain connections that the peer has already
// dropped. Verify the connection is alive via
// max_datagram_size() before returning it.
// connection from a previous call. Max 3 retries
// to avoid spinning until the race timeout.
const MAX_STALE: usize = 3;
let mut stale_count: usize = 0;
loop {
let conn = match &v6_ep_for_accept {
Some(v6_ep) => {
tokio::select! {
v4 = wzp_transport::accept(&ep_for_fut) => {
v4.map_err(|e| anyhow::anyhow!("v4 accept: {e}"))?
}
v6 = wzp_transport::accept(v6_ep) => {
v6.map_err(|e| anyhow::anyhow!("v6 accept: {e}"))?
}
}
}
None => {
wzp_transport::accept(&ep_for_fut)
.await
.map_err(|e| anyhow::anyhow!("direct accept: {e}"))?
}
};
let conn = wzp_transport::accept(&ep_for_fut)
.await
.map_err(|e| anyhow::anyhow!("direct accept: {e}"))?;
// Validate the connection is alive. A stale
// connection from a previous call will report
// close_reason = Some(...) immediately.
if let Some(reason) = conn.close_reason() {
// Explicitly close so the peer gets a
// close frame instead of idle timeout.
conn.close(0u32.into(), b"stale");
stale_count += 1;
tracing::warn!(
remote = %conn.remote_address(),
stable_id = conn.stable_id(),
stale_count,
?reason,
"dual_path: A-role skipping stale connection, re-accepting"
"dual_path: A-role skipping stale connection"
);
if stale_count >= MAX_STALE {
return Err(anyhow::anyhow!(
"A-role: {stale_count} stale connections, aborting"
));
}
continue;
}
@@ -274,7 +269,7 @@ pub async fn race(
}
};
let ep_for_fut = ep.clone();
let v6_ep_for_dial = ipv6_endpoint.clone();
let _v6_ep_for_dial = ipv6_endpoint.clone();
let dial_order = peer_candidates.dial_order();
let sni = call_sni.clone();
direct_fut = Box::pin(async move {
@@ -297,21 +292,22 @@ pub async fn race(
// Phase 7: route each candidate to the
// endpoint matching its address family.
let candidate = *candidate;
let ep = if candidate.is_ipv6() {
match &v6_ep_for_dial {
Some(v6) => v6.clone(),
None => {
tracing::debug!(
%candidate,
candidate_idx = idx,
"dual_path: skipping IPv6 candidate, no v6 endpoint"
);
continue;
}
}
} else {
ep_for_fut.clone()
};
// Phase 7: IPv6 dials temporarily disabled.
// IPv6 QUIC handshakes succeed but the
// connection dies immediately on datagram
// send ("connection lost"). Root cause is
// likely router-level IPv6 UDP filtering.
// Re-enable once IPv6 datagram delivery is
// verified on target networks.
if candidate.is_ipv6() {
tracing::debug!(
%candidate,
candidate_idx = idx,
"dual_path: skipping IPv6 candidate (disabled)"
);
continue;
}
let ep = ep_for_fut.clone();
let client_cfg = wzp_transport::client_config();
let sni = sni.clone();
set.spawn(async move {

View File

@@ -1493,3 +1493,12 @@ impl CallEngine {
}
}
}
impl Drop for CallEngine {
fn drop(&mut self) {
// Safety net: if stop() was never called (crash, app
// backgrounding), signal tasks to exit so they don't
// spin on a dropped transport.
self.running.store(false, Ordering::SeqCst);
}
}

View File

@@ -544,8 +544,21 @@ async fn connect(
// it for participant authentication.
is_direct_p2p_agreed = use_direct;
if use_direct {
// Close losing relay transport so the
// relay sees a clean disconnect instead
// of waiting 30s for idle timeout.
if let Some(loser) = race_result.relay_transport.as_ref() {
loser.connection().close(0u32.into(), b"not-selected");
}
race_result.direct_transport
} else {
// Close losing direct transport so the
// peer's endpoint doesn't retain a
// phantom connection that pollutes
// future accept() calls.
if let Some(loser) = race_result.direct_transport.as_ref() {
loser.connection().close(0u32.into(), b"not-selected");
}
race_result.relay_transport
}
}
@@ -1358,7 +1371,11 @@ async fn place_call(
.map(|la| la.port())
.unwrap_or(0);
// Phase 7: create IPv6 endpoint, trying same port as v4
// Phase 7: create IPv6 endpoint, trying same port as v4.
// Close any leftover from a previous call first.
if let Some(old) = sig.ipv6_endpoint.take() {
old.close(0u32.into(), b"new-call");
}
let (sc, _) = wzp_transport::server_config();
let v6_ep = wzp_transport::create_ipv6_endpoint(v4_port, Some(sc)).ok();
let v6_port = v6_ep.as_ref()
@@ -1477,7 +1494,10 @@ async fn answer_call(
.map(|la| la.port())
.unwrap_or(0);
// Phase 7: create IPv6 endpoint
// Phase 7: create IPv6 endpoint. Close leftover first.
if let Some(old) = sig.ipv6_endpoint.take() {
old.close(0u32.into(), b"new-call");
}
let (sc, _) = wzp_transport::server_config();
let v6_ep = wzp_transport::create_ipv6_endpoint(v4_port, Some(sc)).ok();
let v6_port = v6_ep.as_ref()