use tls.Conn.HandshakeContext instead of tls.Conn.Handshake (#106)

* use tls.Conn.HandshakeContext instead of tls.Conn.Handshake

* make sure that crypto/tls picks up the handshake ctx cancelation in tests

transport.go

@@ -5,7 +5,6 @@ import (
 	"crypto/tls"
 	"errors"
 	"net"
-	"sync"
 
 	ci "github.com/libp2p/go-libp2p-core/crypto"
 	"github.com/libp2p/go-libp2p-core/peer"
@@ -71,44 +70,8 @@ func (t *Transport) SecureOutbound(ctx context.Context, insecure net.Conn, p pee
 	return cs, err
 }
 
-func (t *Transport) handshake(
-	ctx context.Context,
-	tlsConn *tls.Conn,
-	keyCh <-chan ci.PubKey,
-) (sec.SecureConn, error) {
-	// There's no way to pass a context to tls.Conn.Handshake().
-	// See https://github.com/golang/go/issues/18482.
-	// Close the connection instead.
-	select {
-	case <-ctx.Done():
-		tlsConn.Close()
-	default:
-	}
-
-	done := make(chan struct{})
-	var wg sync.WaitGroup
-
-	// Ensure that we do not return before
-	// either being done or having a context
-	// cancellation.
-	defer wg.Wait()
-	defer close(done)
-
-	wg.Add(1)
-	go func() {
-		defer wg.Done()
-		select {
-		case <-done:
-		case <-ctx.Done():
-			tlsConn.Close()
-		}
-	}()
-
-	if err := tlsConn.Handshake(); err != nil {
-		// if the context was canceled, return the context error
-		if ctxErr := ctx.Err(); ctxErr != nil {
-			return nil, ctxErr
-		}
+func (t *Transport) handshake(ctx context.Context, tlsConn *tls.Conn, keyCh <-chan ci.PubKey) (sec.SecureConn, error) {
+	if err := tlsConn.HandshakeContext(ctx); err != nil {
 		return nil, err
 	}
 
@@ -122,15 +85,7 @@ func (t *Transport) handshake(
 		return nil, errors.New("go-libp2p-tls BUG: expected remote pub key to be set")
 	}
 
-	conn, err := t.setupConn(tlsConn, remotePubKey)
-	if err != nil {
-		// if the context was canceled, return the context error
-		if ctxErr := ctx.Err(); ctxErr != nil {
-			return nil, ctxErr
-		}
-		return nil, err
-	}
-	return conn, nil
+	return t.setupConn(tlsConn, remotePubKey)
 }
 
 func (t *Transport) setupConn(tlsConn *tls.Conn, remotePubKey ci.PubKey) (sec.SecureConn, error) {

transport_test.go

@@ -121,6 +121,19 @@ func TestHandshakeSucceeds(t *testing.T) {
 	})
 }
 
+// crypto/tls' cancellation logic works by spinning up a separate Go routine that watches the ctx.
+// If the ctx is canceled, it kills the handshake.
+// We need to make sure that the handshake doesn't complete before that Go routine picks up the cancellation.
+type delayedConn struct {
+	net.Conn
+	delay time.Duration
+}
+
+func (c *delayedConn) Read(b []byte) (int, error) {
+	time.Sleep(c.delay)
+	return c.Conn.Read(b)
+}
+
 func TestHandshakeConnectionCancelations(t *testing.T) {
 	_, clientKey := createPeer(t)
 	serverID, serverKey := createPeer(t)
@@ -152,7 +165,7 @@ func TestHandshakeConnectionCancelations(t *testing.T) {
 		go func() {
 			ctx, cancel := context.WithCancel(context.Background())
 			cancel()
-			_, err := serverTransport.SecureInbound(ctx, serverInsecureConn, "")
+			_, err := serverTransport.SecureInbound(ctx, &delayedConn{Conn: serverInsecureConn, delay: 5 * time.Millisecond}, "")
 			errChan <- err
 		}()
 		_, err = clientTransport.SecureOutbound(context.Background(), clientInsecureConn, serverID)