ipn/ipnlocal: do not initialize peer api listeners when shutting down

Updates tailscale/corp#4824

Signed-off-by: Maisem Ali <maisem@tailscale.com>

ipn/ipnlocal/local.go

@@ -123,6 +123,7 @@ type LocalBackend struct {
 	varRoot               string // or empty if SetVarRoot never called
 	sshAtomicBool         syncs.AtomicBool
 	sshServer             SSHServer // or nil
+	shutdownCalled        bool      // if Shutdown has been called
 
 	filterAtomic            atomic.Value // of *filter.Filter
 	containsViaIPFuncAtomic atomic.Value // of func(netaddr.IP) bool
@@ -343,6 +344,7 @@ func (b *LocalBackend) onHealthChange(sys health.Subsystem, err error) {
 // can no longer be used after Shutdown returns.
 func (b *LocalBackend) Shutdown() {
 	b.mu.Lock()
+	b.shutdownCalled = true
 	cc := b.cc
 	b.closePeerAPIListenersLocked()
 	b.mu.Unlock()
@@ -2341,6 +2343,9 @@ func (b *LocalBackend) closePeerAPIListenersLocked() {
 func (b *LocalBackend) initPeerAPIListener() {
 	b.mu.Lock()
 	defer b.mu.Unlock()
+	if b.shutdownCalled {
+		return
+	}
 
 	if b.netMap == nil {
 		// We're called from authReconfig which checks that

ipn/ipnlocal/peerapi.go

@@ -1104,7 +1104,7 @@ func (fl *fakePeerAPIListener) Close() error {
 
 func (fl *fakePeerAPIListener) Accept() (net.Conn, error) {
 	<-fl.closed
-	return nil, io.EOF
+	return nil, net.ErrClosed
 }
 
 func (fl *fakePeerAPIListener) Addr() net.Addr { return fl.addr }