We build too many walls and not enough bridges

internal/smtp/backend.go

@@ -0,0 +1,109 @@
+// Copyright (c) 2020 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 smtp
+
+import (
+	"strings"
+	"time"
+
+	"github.com/ProtonMail/proton-bridge/internal/bridge"
+	"github.com/ProtonMail/proton-bridge/internal/preferences"
+	"github.com/ProtonMail/proton-bridge/pkg/config"
+	"github.com/ProtonMail/proton-bridge/pkg/listener"
+	goSMTPBackend "github.com/emersion/go-smtp"
+)
+
+type panicHandler interface {
+	HandlePanic()
+}
+
+type smtpBackend struct {
+	panicHandler            panicHandler
+	eventListener           listener.Listener
+	preferences             *config.Preferences
+	bridge                  bridger
+	shouldSendNoEncChannels map[string]chan bool
+	sendRecorder            *sendRecorder
+}
+
+// NewSMTPBackend returns struct implementing go-smtp/backend interface.
+func NewSMTPBackend(
+	panicHandler panicHandler,
+	eventListener listener.Listener,
+	preferences *config.Preferences,
+	bridge *bridge.Bridge,
+) *smtpBackend { //nolint[golint]
+	return newSMTPBackend(panicHandler, eventListener, preferences, newBridgeWrap(bridge))
+}
+
+func newSMTPBackend(
+	panicHandler panicHandler,
+	eventListener listener.Listener,
+	preferences *config.Preferences,
+	bridge bridger,
+) *smtpBackend {
+	return &smtpBackend{
+		panicHandler:            panicHandler,
+		eventListener:           eventListener,
+		preferences:             preferences,
+		bridge:                  bridge,
+		shouldSendNoEncChannels: make(map[string]chan bool),
+		sendRecorder:            newSendRecorder(),
+	}
+}
+
+// Login authenticates a user.
+func (sb *smtpBackend) Login(username, password string) (goSMTPBackend.User, error) {
+	// Called from go-smtp in goroutines - we need to handle panics for each function.
+	defer sb.panicHandler.HandlePanic()
+	username = strings.ToLower(username)
+
+	user, err := sb.bridge.GetUser(username)
+	if err != nil {
+		log.Warn("Cannot get user: ", err)
+		return nil, err
+	}
+	if err := user.CheckBridgeLogin(password); err != nil {
+		log.WithError(err).Error("Could not check bridge password")
+		// Apple Mail sometimes generates a lot of requests very quickly. It's good practice
+		// to have a timeout after bad logins so that we can slow those requests down a little bit.
+		time.Sleep(10 * time.Second)
+		return nil, err
+	}
+	// Client can log in only using address so we can properly close all SMTP connections.
+	addressID, err := user.GetAddressID(username)
+	if err != nil {
+		log.Error("Cannot get addressID: ", err)
+		return nil, err
+	}
+	// AddressID is only for split mode--it has to be empty for combined mode.
+	if user.IsCombinedAddressMode() {
+		addressID = ""
+	}
+	return newSMTPUser(sb.panicHandler, sb.eventListener, sb, user, addressID)
+}
+
+func (sb *smtpBackend) shouldReportOutgoingNoEnc() bool {
+	return sb.preferences.GetBool(preferences.ReportOutgoingNoEncKey)
+}
+
+func (sb *smtpBackend) ConfirmNoEncryption(messageID string, shouldSend bool) {
+	if ch, ok := sb.shouldSendNoEncChannels[messageID]; ok {
+		ch <- shouldSend
+	}
+}