wgengine: fix link monitor / magicsock Start race
Fixes
@@ -84,6 +84,7 @@ type userspaceEngine struct {
wgLogger *wglog.Logger //a wireguard-go logging wrapper
reqCh chan struct{}
waitCh chan struct{} // chan is closed when first Close call completes; contrast with closing bool
+ magicConnStarted chan struct{} // chan is closed after magicConn.Start
timeNow func() mono.Time
tundev *tstun.Wrapper
wgdev *device.Device
@@ -256,6 +257,7 @@ func NewUserspaceEngine(logf logger.Logf, conf Config) (_ Engine, reterr error)
tundev: tsTUNDev,
router: conf.Router,
confListenPort: conf.ListenPort,
+ magicConnStarted: make(chan struct{}),
}
e.isLocalAddr.Store(tsaddr.NewContainsIPFunc(nil))
e.isDNSIPOverTailscale.Store(tsaddr.NewContainsIPFunc(nil))
@@ -371,7 +373,7 @@ func NewUserspaceEngine(logf logger.Logf, conf Config) (_ Engine, reterr error)
// It's a little pointless to apply no-op settings here (they
// should already be empty?), but it at least exercises the
- // router implementation early on the machine.
+ // router implementation early on.
e.logf("Clearing router settings...")
if err := e.router.Set(nil); err != nil {
return nil, err
@@ -380,6 +382,7 @@ func NewUserspaceEngine(logf logger.Logf, conf Config) (_ Engine, reterr error)
e.linkMon.Start()
e.logf("Starting magicsock...")
e.magicConn.Start()
+ close(e.magicConnStarted)
go e.pollResolver()
@@ -1092,6 +1095,10 @@ func (e *userspaceEngine) LinkChange(_ bool) {
}
func (e *userspaceEngine) linkChange(changed bool, cur *interfaces.State) {
+ // Issue 2733: wait for e.magicConn to be started; there's two tiny
+ // windows at startup where this callback can be run before Start
+ <-e.magicConnStarted
+
up := cur.AnyInterfaceUp()
if !up {
e.logf("LinkChange: all links down; pausing: %v", cur)
