feat: Add TLS Handshake timeout support (#530)

* feat: Add TLS Handshake timeout support

Add support for configuring a timeout for TLS Handshake call via
DialTLSHandshakeTimeout DialOption. If no option is specified then the
default timeout is 10 seconds.

Also:
* Add a default connect timeout of 30 seconds matching that of net/http.

Fixes #509

redis/conn.go

@@ -75,17 +75,27 @@ type DialOption struct {
 }
 
 type dialOptions struct {
-	readTimeout  time.Duration
-	writeTimeout time.Duration
-	dialer       *net.Dialer
-	dialContext  func(ctx context.Context, network, addr string) (net.Conn, error)
-	db           int
-	username     string
-	password     string
-	clientName   string
-	useTLS       bool
-	skipVerify   bool
-	tlsConfig    *tls.Config
+	readTimeout         time.Duration
+	writeTimeout        time.Duration
+	tlsHandshakeTimeout time.Duration
+	dialer              *net.Dialer
+	dialContext         func(ctx context.Context, network, addr string) (net.Conn, error)
+	db                  int
+	username            string
+	password            string
+	clientName          string
+	useTLS              bool
+	skipVerify          bool
+	tlsConfig           *tls.Config
+}
+
+// DialTLSHandshakeTimeout specifies the maximum amount of time waiting to
+// wait for a TLS handshake. Zero means no timeout.
+// If no DialTLSHandshakeTimeout option is specified then the default is 30 seconds.
+func DialTLSHandshakeTimeout(d time.Duration) DialOption {
+	return DialOption{func(do *dialOptions) {
+		do.tlsHandshakeTimeout = d
+	}}
 }
 
 // DialReadTimeout specifies the timeout for reading a single command reply.
@@ -104,6 +114,7 @@ func DialWriteTimeout(d time.Duration) DialOption {
 
 // DialConnectTimeout specifies the timeout for connecting to the Redis server when
 // no DialNetDial option is specified.
+// If no DialConnectTimeout option is specified then the default is 30 seconds.
 func DialConnectTimeout(d time.Duration) DialOption {
 	return DialOption{func(do *dialOptions) {
 		do.dialer.Timeout = d
@@ -201,13 +212,21 @@ func Dial(network, address string, options ...DialOption) (Conn, error) {
 	return DialContext(context.Background(), network, address, options...)
 }
 
+type tlsHandshakeTimeoutError struct{}
+
+func (tlsHandshakeTimeoutError) Timeout() bool   { return true }
+func (tlsHandshakeTimeoutError) Temporary() bool { return true }
+func (tlsHandshakeTimeoutError) Error() string   { return "TLS handshake timeout" }
+
 // DialContext connects to the Redis server at the given network and
 // address using the specified options and context.
 func DialContext(ctx context.Context, network, address string, options ...DialOption) (Conn, error) {
 	do := dialOptions{
 		dialer: &net.Dialer{
+			Timeout:   time.Second * 30,
 			KeepAlive: time.Minute * 5,
 		},
+		tlsHandshakeTimeout: time.Second * 10,
 	}
 	for _, option := range options {
 		option.f(&do)
@@ -238,10 +257,22 @@ func DialContext(ctx context.Context, network, address string, options ...DialOp
 		}
 
 		tlsConn := tls.Client(netConn, tlsConfig)
-		if err := tlsConn.Handshake(); err != nil {
-			netConn.Close()
+		errc := make(chan error, 2) // buffered so we don't block timeout or Handshake
+		if d := do.tlsHandshakeTimeout; d != 0 {
+			timer := time.AfterFunc(d, func() {
+				errc <- tlsHandshakeTimeoutError{}
+			})
+			defer timer.Stop()
+		}
+		go func() {
+			errc <- tlsConn.Handshake()
+		}()
+		if err := <-errc; err != nil {
+			// Timeout or Handshake error.
+			netConn.Close() // nolint: errcheck
 			return nil, err
 		}
+
 		netConn = tlsConn
 	}
 

redis/conn_test.go

@@ -701,6 +701,45 @@ func TestDialUseTLS(t *testing.T) {
 	checkPingPong(t, &buf, c)
 }
 
+type blockedReader struct {
+	ch chan struct{}
+}
+
+func (b blockedReader) Read(p []byte) (n int, err error) {
+	<-b.ch
+	return 0, nil
+}
+
+func dialTestBlockedConn(ch chan struct{}, w io.Writer) redis.DialOption {
+	return redis.DialNetDial(func(network, addr string) (net.Conn, error) {
+		return &testConn{Reader: blockedReader{ch: ch}, Writer: w}, nil
+	})
+}
+
+func TestDialTLSHandshakeTimeout(t *testing.T) {
+	var buf bytes.Buffer
+	ch := make(chan struct{})
+	var err error
+	go func() {
+		_, err = redis.Dial("tcp", "example.com:6379",
+			redis.DialTLSConfig(&clientTLSConfig),
+			redis.DialTLSHandshakeTimeout(time.Millisecond),
+			dialTestBlockedConn(ch, &buf),
+			redis.DialUseTLS(true))
+		close(ch)
+	}()
+	select {
+	case <-time.After(time.Second):
+		t.Fatal("dial didn't timeout")
+	case <-ch:
+		if err == nil {
+			t.Fatal("dial didn't error")
+		} else if err.Error() != "TLS handshake timeout" {
+			t.Fatal("dial unexpected error:", err)
+		}
+	}
+}
+
 func TestDialTLSSKipVerify(t *testing.T) {
 	var buf bytes.Buffer
 	c, err := redis.Dial("tcp", "example.com:6379",