Add --interface flag for choosing which network interface to listen on (

#81) * Add --interface flag * Fix default networkInterface
bradleyjkemp · Mar 3, 2020 · 2efa4b2 · 2efa4b2
1 parent eff327c
commit 2efa4b2
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Showing 3 changed files with 16 additions and 10 deletions.
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,7 +1,8 @@
 # Changelog
 
-## Unreleased changes
+## [v0.2.5](https://github.com/bradleyjkemp/grpc-tools/releases/tag/v0.2.5)
 * Added grpc-proxy options `WithServerOptions` and `WithDialOptions`, deprecated `WithOptions` [#71](https://github.com/bradleyjkemp/grpc-tools/pull/71).
+* Added a new command-line option, `--interface` to allow choosing which network interface `grpc-proxy` listens on [#81](https://github.com/bradleyjkemp/grpc-tools/pull/81).
 
 ## [v0.2.4](https://github.com/bradleyjkemp/grpc-tools/releases/tag/v0.2.4)
 * Added a new command-line option, `--tls_secrets_file`, to write the [TLS master secrets file](https://developer.mozilla.org/en-US/docs/Mozilla/Projects/NSS/Key_Log_Format) to the specified path. This can be used later with different application, such as Wireshark, to decrypt the gRPC traffic  [#63](https://github.com/bradleyjkemp/grpc-tools/pull/63).

diff --git a/grpc-proxy/config.go b/grpc-proxy/config.go
@@ -73,6 +73,7 @@ func WithDialer(dialer ContextDialer) Configurator {
 }
 
 var (
+	fNetworkInterface  string
 	fPort              int
 	fCertFile          string
 	fKeyFile           string
@@ -84,6 +85,7 @@ var (
 
 // Must be called before flag.Parse() if using the DefaultFlags option
 func RegisterDefaultFlags() {
+	flag.StringVar(&fNetworkInterface, "interface", "localhost", "Network interface to listen on. By default listens on the localhost interface.")
 	flag.IntVar(&fPort, "port", 0, "Port to listen on.")
 	flag.StringVar(&fCertFile, "cert", "", "Certificate file to use for serving using TLS. By default the current directory will be scanned for mkcert certificates to use.")
 	flag.StringVar(&fKeyFile, "key", "", "Key file to use for serving using TLS. By default the current directory will be scanned for mkcert keys to use.")
@@ -96,6 +98,7 @@ func RegisterDefaultFlags() {
 // This must be used after a call to flag.Parse()
 func DefaultFlags() Configurator {
 	return func(s *server) {
+		s.networkInterface = fNetworkInterface
 		s.port = fPort
 		s.certFile = fCertFile
 		s.keyFile = fKeyFile

diff --git a/grpc-proxy/proxy.go b/grpc-proxy/proxy.go
@@ -32,11 +32,12 @@ type server struct {
 	grpcServer    *grpc.Server
 	logger        logrus.FieldLogger
 
-	port     int
-	certFile string
-	keyFile  string
-	x509Cert *x509.Certificate
-	tlsCert  tls.Certificate
+	networkInterface string
+	port             int
+	certFile         string
+	keyFile          string
+	x509Cert         *x509.Certificate
+	tlsCert          tls.Certificate
 
 	destination string
 	connPool    *internal.ConnPool
@@ -53,8 +54,9 @@ type server struct {
 func New(configurators ...Configurator) (*server, error) {
 	logger := logrus.New()
 	s := &server{
-		logger: logger,
-		dialer: proxydialer.NewProxyDialer(httpproxy.FromEnvironment().ProxyFunc()),
+		logger:           logger,
+		dialer:           proxydialer.NewProxyDialer(httpproxy.FromEnvironment().ProxyFunc()),
+		networkInterface: "localhost", // default to just localhost if no other interface is chosen
 	}
 	s.serverOptions = []grpc.ServerOption{
 		grpc.CustomCodec(codec.NoopCodec{}),        // Allows for passing raw []byte messages around
@@ -103,9 +105,9 @@ func New(configurators ...Configurator) (*server, error) {
 
 func (s *server) Start() error {
 	var err error
-	s.listener, err = net.Listen("tcp", fmt.Sprintf("localhost:%d", s.port))
+	s.listener, err = net.Listen("tcp", fmt.Sprintf("%s:%d", s.networkInterface, s.port))
 	if err != nil {
-		return fmt.Errorf("failed to listen on port (%d): %v", s.port, err)
+		return fmt.Errorf("failed to listen on interface (%s:%d): %v", s.networkInterface, s.port, err)
 	}
 	s.logger.Infof("Listening on %s", s.listener.Addr())
 	if s.x509Cert != nil {