webtransport: initialize the certmanager when creating the transport (#2268)

This solves a deadlock when AddCertHashes is called before Listen.
It also means that we're initializing a certmanaer even if we're only using the
WebTransport transport for dialing and not for listening, but that's a fringe
use case anyway.

p2p/transport/webtransport/transport.go

@@ -68,12 +68,9 @@ type transport struct {
 	rcmgr       network.ResourceManager
 	gater       connmgr.ConnectionGater
 
-	listenOnce       sync.Once
-	listenOnceErr    error
-	certManager      *certManager
-	certManagerReady chan struct{} // Closed when the certManager has been instantiated.
-	staticTLSConf    *tls.Config
-	tlsClientConf    *tls.Config
+	certManager   *certManager
+	staticTLSConf *tls.Config
+	tlsClientConf *tls.Config
 
 	noise *noise.Transport
 
@@ -97,21 +94,26 @@ func New(key ic.PrivKey, psk pnet.PSK, connManager *quicreuse.ConnManager, gater
 	if err != nil {
 		return nil, err
 	}
+
 	t := &transport{
-		pid:              id,
-		privKey:          key,
-		rcmgr:            rcmgr,
-		gater:            gater,
-		clock:            clock.New(),
-		connManager:      connManager,
-		conns:            map[uint64]*conn{},
-		certManagerReady: make(chan struct{}),
+		pid:         id,
+		privKey:     key,
+		rcmgr:       rcmgr,
+		gater:       gater,
+		clock:       clock.New(),
+		connManager: connManager,
+		conns:       map[uint64]*conn{},
 	}
 	for _, opt := range opts {
 		if err := opt(t); err != nil {
 			return nil, err
 		}
 	}
+	cm, err := newCertManager(key, t.clock)
+	if err != nil {
+		return nil, err
+	}
+	t.certManager = cm
 	n, err := noise.New(noise.ID, key, nil)
 	if err != nil {
 		return nil, err
@@ -297,16 +299,7 @@ func (t *transport) Listen(laddr ma.Multiaddr) (tpt.Listener, error) {
 	if !isWebTransport {
 		return nil, fmt.Errorf("cannot listen on non-WebTransport addr: %s", laddr)
 	}
-	if t.staticTLSConf == nil {
-		t.listenOnce.Do(func() {
-			t.certManager, t.listenOnceErr = newCertManager(t.privKey, t.clock)
-			close(t.certManagerReady)
-		})
-		if t.listenOnceErr != nil {
-			return nil, t.listenOnceErr
-		}
-	} else {
-		close(t.certManagerReady)
+	if t.staticTLSConf != nil {
 		return nil, errors.New("static TLS config not supported on WebTransport")
 	}
 	tlsConf := t.staticTLSConf.Clone()
@@ -333,11 +326,7 @@ func (t *transport) Proxy() bool {
 }
 
 func (t *transport) Close() error {
-	t.listenOnce.Do(func() {})
-	if t.certManager != nil {
-		return t.certManager.Close()
-	}
-	return nil
+	return t.certManager.Close()
 }
 
 func (t *transport) allowWindowIncrease(conn quic.Connection, size uint64) bool {
@@ -406,9 +395,5 @@ func (t *transport) Resolve(_ context.Context, maddr ma.Multiaddr) ([]ma.Multiad
 }
 
 func (t *transport) AddCertHashes(m ma.Multiaddr) ma.Multiaddr {
-	<-t.certManagerReady
-	if t.certManager == nil {
-		return m
-	}
 	return m.Encapsulate(t.certManager.AddrComponent())
 }