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[client] Fix peers not being notified when the relay connection drops (#7490)

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* [relay] Signal relay disconnects through the conn context

AddCloseListener deduplicated listeners by comparing
reflect.ValueOf(callback).Pointer(). For a method value that pointer is
the address of the compiler-generated wrapper, not an identity bound to
the receiver, so every peer's w.onRelayClientDisconnected compared equal.

All peers on the home relay register under the same connectionURL key, so
only the first registration survived and the rest were silently dropped.
On a relay disconnect those peers were never notified: statusRelay stayed
connected and the reconnect guard never fired. The relayed net.Conn itself
was closed by closeAllConns, so nothing leaked, but the peer state machine
did not learn about it. Foreign relays had the same defect scoped to the
peers sharing that server.

Rather than fixing the deduplication, drop the peer-level listener registry
entirely. A relayed Conn now exposes Context(), cancelled when the
connection is torn down, with a cancellation cause naming the reason. This
is the same shape quic-go uses for its Conn and Stream types, and it
removes the whole class of problems around listener identity, lifetime and
deregistration: the signal belongs to the resource instead of a side table.

WorkerRelay watches that context in a goroutine whose lifetime matches the
connection. A watcher that wakes up for a superseded connection compares
the conn pointer against the current one and returns without touching the
state machine, so a fast relay reconnect cannot have a stale watcher tear
down the connection that replaced it.

Client.SetOnDisconnectListener stays: it is server-level and drives the
reconnect guard and foreign relay eviction, unrelated to peers.

handleRelayReady also checks the conn context, closing the race where the
relay dies between OpenConn and the readiness handoff and the peer would
otherwise build a WireGuard endpoint over a dead connection.

TestNotifierDoubleAdd covered the removed mechanism and is gone.
TestForeignAutoClose asserted nothing (both branches logged); it now waits
for the relay to leave the client map and fails if it does not.

* [relay] Fix build: return the concrete conn from Client.OpenConn

OpenConn now returns *Conn, but it still went through connContainer.netConn(),
which widens to net.Conn. The helper had one caller and only existed to produce
the interface value the signature no longer wants, so return container.conn
directly and drop it.

* [relay] Assert the local-close cancellation cause explicitly

The local-close test only rejected ErrServerDisconnected, so it would also
have passed for ErrPeerDisconnected or a bare context.Canceled. closeConn
cancels with net.ErrClosed, so assert that.

* [client] Ignore relay disconnects from superseded connections

The relayed conn watcher compared the conn pointer under relayLock, released
it, and only then tore the connection down. A new offer could install its
replacement in that window, so a watcher that validated the old pointer went
on to close the proxy of the connection that had already replaced it and
report the peer as disconnected while it was up.

Move the decision to where the teardown happens. Conn records which relayed
connection the current proxy was built from, and onRelayDisconnected takes the
connection the signal belongs to and drops it under conn.mu when it is no
longer the current one. Check and effect are now in the same critical section,
so the verdict cannot go stale before it is acted on.

This also covers the proxy read loops, whose disconnect listener took no
argument and had the same defect: it now names the connection it belongs to.
The WG timeout path keeps passing nil, since it deliberately tears down
whatever is current.

* [client] Bind the relayed conn reference to the proxy swap

relayedConnRef was set at the top of the readiness path, but wgProxyRelay only
changes at the end, in setRelayedProxy. The two failure returns in between —
newProxy and ConfigureWGEndpoint — left the reference pointing at a connection
that never became active while the old proxy was still installed. A disconnect
of that old, live relay would then be dismissed as belonging to a superseded
connection and never cleaned up.

Set the reference in setRelayedProxy, next to the proxy it belongs to. Both
success paths go through it and neither failure path does, so no failure branch
has to remember to roll anything back.
This commit is contained in:
Zoltan Papp
2026-09-21 17:00:37 +02:00
committed by GitHub
parent 771d81b72a
commit bc0671fd21
6 changed files with 182 additions and 163 deletions
Download Patch File Download Diff File Expand all files Collapse all files
shared/relay/client/manager.go
+8 -74
View File
@@ -1,12 +1,9 @@
package client
import (
"container/list"
"context"
"fmt"
"net"
"net/netip"
"reflect"
"sync"
"time"
@@ -43,8 +40,6 @@ func NewRelayTrack() *RelayTrack {
}
}
type OnServerCloseListener func()
// ManagerOption configures a Manager at construction time.
type ManagerOption func(*Manager)
@@ -91,7 +86,6 @@ type Manager struct {
relayClients map[string]*RelayTrack
relayClientsMutex sync.RWMutex
onDisconnectedListeners map[string]*list.List
onReconnectedListenerFn func()
listenerLock sync.Mutex
@@ -126,10 +120,9 @@ func NewManager(ctx context.Context, serverURLs []string, peerID string, mtu uin
ConnectionTimeout: defaultConnectionTimeout,
TransportFallback: tf,
},
relayClients: make(map[string]*RelayTrack),
onDisconnectedListeners: make(map[string]*list.List),
cleanupInterval: relayCleanupInterval,
keepUnusedServerTime: keepUnusedServerTime,
relayClients: make(map[string]*RelayTrack),
cleanupInterval: relayCleanupInterval,
keepUnusedServerTime: keepUnusedServerTime,
}
for _, opt := range opts {
opt(m)
@@ -168,11 +161,11 @@ func (m *Manager) Serve() error {
// OpenConn opens a connection to the given peer key. If the peer is on the same relay server, the connection will be
// established via the relay server. If the peer is on a different relay server, the manager will establish a new
// connection to the relay server. It returns back with a net.Conn what represent the remote peer connection.
// connection to the relay server. It returns the relayed connection to the remote peer.
//
// serverIP, when valid and serverAddress is foreign, is used as a dial target if the FQDN-based dial fails.
// Ignored for the local home-server path. TLS verification still uses the FQDN via SNI.
func (m *Manager) OpenConn(ctx context.Context, serverAddress, peerKey string, serverIP netip.Addr) (net.Conn, error) {
func (m *Manager) OpenConn(ctx context.Context, serverAddress, peerKey string, serverIP netip.Addr) (*Conn, error) {
m.relayClientMu.RLock()
defer m.relayClientMu.RUnlock()
@@ -185,9 +178,7 @@ func (m *Manager) OpenConn(ctx context.Context, serverAddress, peerKey string, s
return nil, err
}
var (
netConn net.Conn
)
var netConn *Conn
if !foreign {
log.Debugf("open peer connection via permanent server: %s", peerKey)
netConn, err = m.relayClient.OpenConn(ctx, peerKey)
@@ -220,31 +211,6 @@ func (m *Manager) SetOnReconnectedListener(f func()) {
m.onReconnectedListenerFn = f
}
// AddCloseListener adds a listener to the given server instance address. The listener will be called if the connection
// closed.
func (m *Manager) AddCloseListener(serverAddress string, onClosedListener OnServerCloseListener) error {
m.relayClientMu.RLock()
defer m.relayClientMu.RUnlock()
if m.relayClient == nil {
return ErrRelayClientNotConnected
}
foreign, err := m.isForeignServer(serverAddress)
if err != nil {
return err
}
var listenerAddr string
if foreign {
listenerAddr = serverAddress
} else {
listenerAddr = m.relayClient.connectionURL
}
m.addListener(listenerAddr, onClosedListener)
return nil
}
// RelayInstanceAddress returns the address and resolved IP of the permanent relay server. It could change if the
// network connection is lost. The address is sent to the target peer to choose the common relay server for the
// communication; the IP is sent alongside so remote peers can dial directly without their own DNS lookup. Both
@@ -330,7 +296,7 @@ func (m *Manager) UpdateToken(token *relayAuth.Token) error {
return m.tokenStore.UpdateToken(token)
}
func (m *Manager) openConnVia(ctx context.Context, serverAddress, peerKey string, serverIP netip.Addr) (net.Conn, error) {
func (m *Manager) openConnVia(ctx context.Context, serverAddress, peerKey string, serverIP netip.Addr) (*Conn, error) {
// check if already has a connection to the desired relay server
m.relayClientsMutex.RLock()
rt, ok := m.relayClients[serverAddress]
@@ -383,7 +349,7 @@ func (m *Manager) openConnVia(ctx context.Context, serverAddress, peerKey string
// waiting for the dial started by another openConnVia call to finish. It waits
// on rt.ready rather than the track lock, so it neither holds nor contends the
// track lock across the dial.
func (m *Manager) openConnOnTrack(ctx context.Context, rt *RelayTrack, peerKey string) (net.Conn, error) {
func (m *Manager) openConnOnTrack(ctx context.Context, rt *RelayTrack, peerKey string) (*Conn, error) {
select {
case <-rt.ready:
case <-ctx.Done():
@@ -428,8 +394,6 @@ func (m *Manager) onServerDisconnected(serverAddress string) {
if !isHome {
m.evictForeignRelay(serverAddress)
}
m.notifyOnDisconnectListeners(serverAddress)
}
func (m *Manager) evictForeignRelay(serverAddress string) {
@@ -523,36 +487,6 @@ func (m *Manager) cleanUpUnusedRelays() {
}
}
func (m *Manager) addListener(serverAddress string, onClosedListener OnServerCloseListener) {
m.listenerLock.Lock()
defer m.listenerLock.Unlock()
l, ok := m.onDisconnectedListeners[serverAddress]
if !ok {
l = list.New()
}
for e := l.Front(); e != nil; e = e.Next() {
if reflect.ValueOf(e.Value).Pointer() == reflect.ValueOf(onClosedListener).Pointer() {
return
}
}
l.PushBack(onClosedListener)
m.onDisconnectedListeners[serverAddress] = l
}
func (m *Manager) notifyOnDisconnectListeners(serverAddress string) {
m.listenerLock.Lock()
defer m.listenerLock.Unlock()
l, ok := m.onDisconnectedListeners[serverAddress]
if !ok {
return
}
for e := l.Front(); e != nil; e = e.Next() {
go e.Value.(OnServerCloseListener)()
}
delete(m.onDisconnectedListeners, serverAddress)
}
func relayConnState(c *Client) RelayConnState {
addr, err := c.ServerInstanceURL()
if err != nil {