Add support for port reuse by implementing multiplexing listener

config/configgrpc/configgrpc.go

@@ -165,6 +165,10 @@ type GRPCServerSettings struct {
 
  // Auth for this receiver
  Auth *configauth.Authentication `mapstructure:"auth,omitempty"`
+
+ // MuxListener is a multiplexing listener for the Endpoint of NetAddr. Through multiplexing,
+ // a single listener can support multiple sockets on the same port.
+ MuxListener net.Listener
 }
 
 // ToDialOptions maps configgrpc.GRPCClientSettings to a slice of dial options for gRPC
@@ -237,7 +241,44 @@ func validateBalancerName(balancerName string) bool {
 
 // ToListener returns the net.Listener constructed from the settings.
 func (gss *GRPCServerSettings) ToListener() (net.Listener, error) {
- return gss.NetAddr.Listen()
+ var addr net.Addr
+ var err error
+
+ switch gss.NetAddr.Transport {
+ case "tcp", "tcp4", "tcp6":
+ addr, err = net.ResolveTCPAddr(gss.NetAddr.Transport, gss.NetAddr.Endpoint)
+ case "udp", "udp4", "udp6":
+ addr, err = net.ResolveUDPAddr(gss.NetAddr.Transport, gss.NetAddr.Endpoint)
+ case "ip", "ip4", "ip6":
+ addr, err = net.ResolveIPAddr(gss.NetAddr.Transport, gss.NetAddr.Endpoint)
+ case "unix", "unixgram", "unixpacket":
+ addr, err = net.ResolveUnixAddr(gss.NetAddr.Transport, gss.NetAddr.Endpoint)
+ default:
+ return nil, fmt.Errorf("unknown network protocol")
+ }
+ if err != nil {
+ return nil, err
+ }
+
+ if gss.MuxListener != nil && addr.String() == gss.MuxListener.Addr().String() {
+ return gss.MuxListener, nil
+ }
+
+ // if gss.MuxListener != nil {
+ // err = gss.MuxListener.Close()
+ // if err != nil {
+ // return nil, err
+ // }
+ // }
+
+ listener, err := gss.NetAddr.Listen()
+ if err != nil {
+ return nil, err
+ }
+
+ gss.MuxListener = listener
+
+ return listener, nil
 }
 
 // ToServerOption maps configgrpc.GRPCServerSettings to a slice of server options for gRPC

config/configgrpc/configgrpc_test.go

@@ -536,3 +536,27 @@ func tempSocketName(t *testing.T) string {
  require.NoError(t, os.Remove(socket))
  return socket
 }
+
+func TestGRPCPortReuse(t *testing.T) {
+ settings := GRPCServerSettings{
+ NetAddr: confignet.NetAddr{
+ Endpoint: "localhost: 2873",
+ Transport: "tcp",
+ },
+ }
+ muxListener, err := settings.ToListener()
+ if err != nil {
+ t.Errorf("cannot initialize multiplexing listener")
+ }
+
+ for i := 0; i < 100; i++ {
+ t.Run("", func(t *testing.T) {
+ _, err := settings.ToListener()
+ if err != nil {
+ t.Error("something went wrong, port cannot be reused")
+ }
+ assert.NotNil(t, settings.MuxListener)
+ assert.Equal(t, muxListener, settings.MuxListener)
+ })
+ }
+}

config/confighttp/confighttp.go

@@ -123,15 +123,38 @@ type HTTPServerSettings struct {
  // CORS needs to be enabled first by providing a non-empty list in CorsOrigins
  // A wildcard (*) can be used to match any header.
  CorsHeaders []string `mapstructure:"cors_allowed_headers"`
+
+ // MuxListener is a multiplexing listener for the Endpoint. Through multiplexing,
+ // a single listener can support multiple sockets on the same port.
+ MuxListener net.Listener
 }
 
 // ToListener creates a net.Listener.
 func (hss *HTTPServerSettings) ToListener() (net.Listener, error) {
- listener, err := net.Listen("tcp", hss.Endpoint)
+ var listener net.Listener
+ var addr net.Addr
+ var err error
+
+ addr, err = net.ResolveTCPAddr("tcp", hss.Endpoint)
  if err != nil {
  return nil, err
  }
 
+ if hss.MuxListener != nil && addr.String() == hss.MuxListener.Addr().String() {
+ listener = hss.MuxListener
+ } else {
+ // if hss.MuxListener != nil {
+ // err = hss.MuxListener.Close()
+ // if err != nil {
+ // return nil, err
+ // }
+ // }
+ listener, err = net.Listen("tcp", hss.Endpoint)
+ if err != nil {
+ return nil, err
+ }
+ }
+
  if hss.TLSSetting != nil {
  var tlsCfg *tls.Config
  tlsCfg, err = hss.TLSSetting.LoadTLSConfig()
@@ -140,6 +163,9 @@ func (hss *HTTPServerSettings) ToListener() (net.Listener, error) {
  }
  listener = tls.NewListener(listener, tlsCfg)
  }
+
+ hss.MuxListener = listener
+
  return listener, nil
 }
 

config/confighttp/confighttp_test.go

@@ -482,3 +482,24 @@ func TestHttpHeaders(t *testing.T) {
  })
  }
 }
+
+func TestHTTPPortReuse(t *testing.T) {
+ settings := HTTPServerSettings{
+ Endpoint: "localhost: 6489",
+ }
+ muxListener, err := settings.ToListener()
+ if err != nil {
+ t.Errorf("cannot initialize multiplexing listener")
+ }
+
+ for i := 0; i < 100; i++ {
+ t.Run("", func(t *testing.T) {
+ _, err := settings.ToListener()
+ if err != nil {
+ t.Error("something went wrong, port cannot be reused")
+ }
+ assert.NotNil(t, settings.MuxListener)
+ assert.Equal(t, muxListener, settings.MuxListener)
+ })
+ }
+}