Overwrite authority if creds servername is specified

clientconn.go

@@ -322,11 +322,16 @@ func DialContext(ctx context.Context, target string, opts ...DialOption) (conn *
 	if ok {
 		go cc.lbWatcher()
 	}
-	colonPos := strings.LastIndex(target, ":")
-	if colonPos == -1 {
-		colonPos = len(target)
+	creds := cc.dopts.copts.TransportCredentials
+	if creds != nil && creds.Info().ServerName != "" {
+		cc.authority = creds.Info().ServerName
+	} else {
+		colonPos := strings.LastIndex(target, ":")
+		if colonPos == -1 {
+			colonPos = len(target)
+		}
+		cc.authority = target[:colonPos]
 	}
-	cc.authority = target[:colonPos]
 	return cc, nil
 }
 

clientconn_test.go

@@ -65,15 +65,31 @@ func TestTLSDialTimeout(t *testing.T) {
 		conn.Close()
 	}
 	if err != ErrClientConnTimeout {
-		t.Fatalf("grpc.Dial(_, _) = %v, %v, want %v", conn, err, ErrClientConnTimeout)
+		t.Fatalf("Dial(_, _) = %v, %v, want %v", conn, err, ErrClientConnTimeout)
+	}
+}
+
+func TestTLSServerNameOverwrite(t *testing.T) {
+	overwriteServerName := "over.write.server.name"
+	creds, err := credentials.NewClientTLSFromFile(tlsDir+"ca.pem", overwriteServerName)
+	if err != nil {
+		t.Fatalf("Failed to create credentials %v", err)
+	}
+	conn, err := Dial("Non-Existent.Server:80", WithTransportCredentials(creds), WithTimeout(time.Millisecond))
+	if err != nil {
+		t.Fatalf("Dial(_, _) = _, %v, want _, <nil>", err)
+	}
+	conn.Close()
+	if conn.authority != overwriteServerName {
+		t.Fatalf("%v.authority = %v, want %v", conn, conn.authority, overwriteServerName)
 	}
 }
 
 func TestDialContextCancel(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())
 	cancel()
 	if _, err := DialContext(ctx, "Non-Existent.Server:80", WithBlock(), WithInsecure()); err != context.Canceled {
-		t.Fatalf("grpc.DialContext(%v, _) = _, %v, want _, %v", ctx, err, context.Canceled)
+		t.Fatalf("DialContext(%v, _) = _, %v, want _, %v", ctx, err, context.Canceled)
 	}
 }
 

credentials/credentials.go

@@ -72,14 +72,16 @@ type PerRPCCredentials interface {
 }
 
 // ProtocolInfo provides information regarding the gRPC wire protocol version,
-// security protocol, security protocol version in use, etc.
+// security protocol, security protocol version in use, server name, etc.
 type ProtocolInfo struct {
 	// ProtocolVersion is the gRPC wire protocol version.
 	ProtocolVersion string
 	// SecurityProtocol is the security protocol in use.
 	SecurityProtocol string
 	// SecurityVersion is the security protocol version.
 	SecurityVersion string
+	// ServerName is the user-configured server name.
+	ServerName string
 }
 
 // AuthInfo defines the common interface for the auth information the users are interested in.
@@ -130,6 +132,7 @@ func (c tlsCreds) Info() ProtocolInfo {
 	return ProtocolInfo{
 		SecurityProtocol: "tls",
 		SecurityVersion:  "1.2",
+		ServerName:       c.config.ServerName,
 	}
 }
 
@@ -187,12 +190,16 @@ func NewTLS(c *tls.Config) TransportCredentials {
 }
 
 // NewClientTLSFromCert constructs a TLS from the input certificate for client.
-func NewClientTLSFromCert(cp *x509.CertPool, serverName string) TransportCredentials {
-	return NewTLS(&tls.Config{ServerName: serverName, RootCAs: cp})
+// serverNameOverwrite is for testing only. If set to a non empty string,
+// it will overwrite the virtual host name of authority (e.g. :authority header field) in requests.
+func NewClientTLSFromCert(cp *x509.CertPool, serverNameOverwrite string) TransportCredentials {
+	return NewTLS(&tls.Config{ServerName: serverNameOverwrite, RootCAs: cp})
 }
 
 // NewClientTLSFromFile constructs a TLS from the input certificate file for client.
-func NewClientTLSFromFile(certFile, serverName string) (TransportCredentials, error) {
+// serverNameOverwrite is for testing only. If set to a non empty string,
+// it will overwrite the virtual host name of authority (e.g. :authority header field) in requests.
+func NewClientTLSFromFile(certFile, serverNameOverwrite string) (TransportCredentials, error) {
 	b, err := ioutil.ReadFile(certFile)
 	if err != nil {
 		return nil, err
@@ -201,7 +208,7 @@ func NewClientTLSFromFile(certFile, serverName string) (TransportCredentials, er
 	if !cp.AppendCertsFromPEM(b) {
 		return nil, fmt.Errorf("credentials: failed to append certificates")
 	}
-	return NewTLS(&tls.Config{ServerName: serverName, RootCAs: cp}), nil
+	return NewTLS(&tls.Config{ServerName: serverNameOverwrite, RootCAs: cp}), nil
 }
 
 // NewServerTLSFromCert constructs a TLS from the input certificate for server.