Turning off IMAP server while no connection

internal/app/base/base.go

@@ -156,7 +156,14 @@ func New( // nolint[funlen]
 		return nil, err
 	}
 
-	cm := pmapi.NewClientManager(pmapi.GetAPIConfig(configName, constants.Version))
+	apiConfig := pmapi.GetAPIConfig(configName, constants.Version)
+	apiConfig.NoConnectionHandler = func() {
+		eventListener.Emit(events.InternetOffEvent, "")
+	}
+	apiConfig.ConnectionHandler = func() {
+		eventListener.Emit(events.InternetOnEvent, "")
+	}
+	cm := pmapi.NewClientManager(apiConfig)
 	cm.SetRoundTripper(pmapi.GetRoundTripper(cm, listener))
 	cm.SetCookieJar(jar)
 	sentryReporter.SetUserAgentProvider(cm)

internal/imap/server.go

@@ -47,6 +47,8 @@ type imapServer struct {
 	eventListener listener.Listener
 	debugClient   bool
 	debugServer   bool
+
+	on bool
 }
 
 // NewIMAPServer constructs a new IMAP server configured with the given options.
@@ -106,6 +108,19 @@ func NewIMAPServer(debugClient, debugServer bool, port int, tls *tls.Config, ima
 // Starts the server.
 func (s *imapServer) ListenAndServe() {
 	go s.monitorDisconnectedUsers()
+	go s.monitorInternetConnection()
+
+	s.listenAndServe()
+}
+
+func (s *imapServer) listenAndServe() {
+	if s.on {
+		return
+	}
+	s.on = true
+	defer func() {
+		s.on = false
+	}()
 
 	log.Info("IMAP server listening at ", s.server.Addr)
 	l, err := net.Listen("tcp", s.server.Addr)
@@ -136,6 +151,24 @@ func (s *imapServer) Close() {
 	}
 }
 
+func (s *imapServer) monitorInternetConnection() {
+	on := make(chan string)
+	s.eventListener.Add(events.InternetOnEvent, on)
+	off := make(chan string)
+	s.eventListener.Add(events.InternetOffEvent, off)
+
+	go func() {
+		for range on {
+			s.listenAndServe()
+		}
+	}()
+	go func() {
+		for range off {
+			s.Close()
+		}
+	}()
+}
+
 func (s *imapServer) monitorDisconnectedUsers() {
 	ch := make(chan string)
 	s.eventListener.Add(events.CloseConnectionEvent, ch)

pkg/pmapi/client.go

@@ -102,6 +102,9 @@ type ClientConfig struct {
 	// MinBytesPerSecond specifies minimum Bytes per second or the request will be canceled.
 	// Zero means no limitation.
 	MinBytesPerSecond int64
+
+	NoConnectionHandler func()
+	ConnectionHandler   func()
 }
 
 // client is a client of the protonmail API. It implements the Client interface.

pkg/pmapi/dialer_proxy.go

@@ -37,7 +37,17 @@ func NewProxyTLSDialer(dialer TLSDialer, cm *ClientManager) *ProxyTLSDialer {
 }
 
 // DialTLS dials the given network/address. If it fails, it retries using a proxy.
-func (d *ProxyTLSDialer) DialTLS(network, address string) (conn net.Conn, err error) {
+func (d *ProxyTLSDialer) DialTLS(network, address string) (net.Conn, error) {
+	conn, err := d.dialTLS(network, address)
+	if err != nil {
+		d.cm.config.NoConnectionHandler()
+	} else {
+		d.cm.config.ConnectionHandler()
+	}
+	return conn, err
+}
+
+func (d *ProxyTLSDialer) dialTLS(network, address string) (conn net.Conn, err error) {
 	if conn, err = d.dialer.DialTLS(network, address); err == nil {
 		return
 	}