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

internal/serverutil/listener.go

@@ -0,0 +1,59 @@
+// 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 (
+	"io"
+	"net"
+
+	"github.com/sirupsen/logrus"
+)
+
+// connListener sets debug loggers on server containing fields with local
+// and remote addresses right after new connection is accepted.
+type connListener struct {
+	net.Listener
+
+	server Server
+}
+
+func (l *connListener) Accept() (net.Conn, error) {
+	conn, err := l.Listener.Accept()
+
+	if err == nil && (l.server.DebugServer() || l.server.DebugClient()) {
+		debugLog := logrus.WithField("pkg", l.server.Protocol())
+		if addr := conn.LocalAddr(); addr != nil {
+			debugLog = debugLog.WithField("loc", addr.String())
+		}
+		if addr := conn.RemoteAddr(); addr != nil {
+			debugLog = debugLog.WithField("rem", addr.String())
+		}
+
+		var localDebug, remoteDebug io.Writer
+		if l.server.DebugServer() {
+			localDebug = debugLog.WithField("comm", "server").WriterLevel(logrus.DebugLevel)
+		}
+		if l.server.DebugClient() {
+			remoteDebug = debugLog.WithField("comm", "client").WriterLevel(logrus.DebugLevel)
+		}
+
+		l.server.SetLoggers(localDebug, remoteDebug)
+	}
+
+	return conn, err
+}