GODT-1187: Remove IMAP/SMTP blocking when no internet.

internal/serverutil/controller.go

@@ -0,0 +1,117 @@
+// Copyright (c) 2021 Proton Technologies AG
+//
+// This file is part of ProtonMail Bridge.
+//
+// ProtonMail Bridge is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// ProtonMail Bridge is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with ProtonMail Bridge.  If not, see <https://www.gnu.org/licenses/>.
+
+package serverutil
+
+import (
+	"crypto/tls"
+	"fmt"
+	"net"
+
+	"github.com/ProtonMail/proton-bridge/internal/events"
+	"github.com/ProtonMail/proton-bridge/pkg/listener"
+	"github.com/sirupsen/logrus"
+)
+
+// Controller will make sure that server is listening and serving and if needed
+// users are disconnected.
+type Controller interface {
+	ListenAndServe()
+	Close()
+}
+
+// NewController return simple server controller.
+func NewController(s Server, l listener.Listener) Controller {
+	log := logrus.WithField("pkg", "serverutil").WithField("protocol", s.Protocol())
+	c := &controller{
+		server:               s,
+		signals:              l,
+		log:                  log,
+		closeDisconnectUsers: make(chan void),
+	}
+
+	if s.DebugServer() {
+		fmt.Println("THE LOG WILL CONTAIN **DECRYPTED** MESSAGE DATA")
+		log.Warning("================================================")
+		log.Warning("THIS LOG WILL CONTAIN **DECRYPTED** MESSAGE DATA")
+		log.Warning("================================================")
+	}
+
+	return c
+}
+
+type void struct{}
+
+type controller struct {
+	server  Server
+	signals listener.Listener
+	log     *logrus.Entry
+
+	closeDisconnectUsers chan void
+}
+
+func (c *controller) Close() {
+	c.closeDisconnectUsers <- void{}
+	if err := c.server.StopServe(); err != nil {
+		c.log.WithError(err).Error("Issue when closing server")
+	}
+}
+
+// ListenAndServe starts the server and keeps it on based on internet
+// availability. It also monitors and disconnect users if requested.
+func (c *controller) ListenAndServe() {
+	go monitorDisconnectedUsers(c.server, c.signals, c.closeDisconnectUsers)
+
+	defer c.server.HandlePanic()
+
+	l := c.log.WithField("useSSL", c.server.UseSSL()).
+		WithField("address", c.server.Address())
+
+	var listener net.Listener
+	var err error
+
+	if c.server.UseSSL() {
+		listener, err = tls.Listen("tcp", c.server.Address(), c.server.TLSConfig())
+	} else {
+		listener, err = net.Listen("tcp", c.server.Address())
+	}
+
+	if err != nil {
+		l.WithError(err).Error("Cannot start listner.")
+		c.signals.Emit(events.ErrorEvent, string(c.server.Protocol())+" failed: "+err.Error())
+		return
+	}
+
+	// When starting the Bridge, we don't want to retry to notify user
+	// quickly about the issue. Very probably retry will not help anyway.
+	l.Info("Starting server")
+	err = c.server.Serve(&connListener{listener, c.server})
+	l.WithError(err).Debug("GoSMTP not serving")
+}
+
+func monitorDisconnectedUsers(s Server, l listener.Listener, done <-chan void) {
+	ch := make(chan string)
+	l.Add(events.CloseConnectionEvent, ch)
+	for {
+		select {
+		case <-done:
+			return
+		case address := <-ch:
+			s.DisconnectUser(address)
+		}
+	}
+}