Import/Export backend prep

internal/transfer/provider_imap_utils.go

@@ -0,0 +1,236 @@
+// 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 transfer
+
+import (
+	"net"
+	"time"
+
+	imapID "github.com/ProtonMail/go-imap-id"
+	"github.com/ProtonMail/proton-bridge/pkg/pmapi"
+	"github.com/emersion/go-imap"
+	imapClient "github.com/emersion/go-imap/client"
+	sasl "github.com/emersion/go-sasl"
+	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
+)
+
+const (
+	imapDialTimeout      = 5 * time.Second
+	imapRetries          = 10
+	imapReconnectTimeout = 30 * time.Minute
+	imapReconnectSleep   = time.Minute
+)
+
+type imapErrorLogger struct {
+	log *logrus.Entry
+}
+
+func (l *imapErrorLogger) Printf(f string, v ...interface{}) {
+	l.log.Errorf(f, v...)
+}
+
+func (l *imapErrorLogger) Println(v ...interface{}) {
+	l.log.Errorln(v...)
+}
+
+type imapDebugLogger struct { //nolint[unused]
+	log *logrus.Entry
+}
+
+func (l *imapDebugLogger) Write(data []byte) (int, error) {
+	l.log.Trace(string(data))
+	return len(data), nil
+}
+
+func (p *IMAPProvider) ensureConnection(callback func() error) error {
+	var callErr error
+	for i := 1; i <= imapRetries; i++ {
+		callErr = callback()
+		if callErr == nil {
+			return nil
+		}
+
+		log.WithField("attempt", i).WithError(callErr).Warning("Call failed, trying reconnect")
+		err := p.tryReconnect()
+		if err != nil {
+			return err
+		}
+	}
+	return errors.Wrap(callErr, "too many retries")
+}
+
+func (p *IMAPProvider) tryReconnect() error {
+	start := time.Now()
+	var previousErr error
+	for {
+		if time.Since(start) > imapReconnectTimeout {
+			return previousErr
+		}
+
+		err := pmapi.CheckConnection()
+		if err != nil {
+			time.Sleep(imapReconnectSleep)
+			previousErr = err
+			continue
+		}
+
+		err = p.reauth()
+		if err != nil {
+			time.Sleep(imapReconnectSleep)
+			previousErr = err
+			continue
+		}
+
+		break
+	}
+	return nil
+}
+
+func (p *IMAPProvider) reauth() error {
+	if _, err := p.client.Capability(); err != nil {
+		state := p.client.State()
+		log.WithField("addr", p.addr).WithField("state", state).WithError(err).Debug("Reconnecting")
+		p.client = nil
+	}
+
+	return p.auth()
+}
+
+func (p *IMAPProvider) auth() error { //nolint[funlen]
+	log := log.WithField("addr", p.addr)
+
+	log.Info("Connecting to server")
+
+	if _, err := net.DialTimeout("tcp", p.addr, imapDialTimeout); err != nil {
+		return errors.Wrap(err, "failed to dial server")
+	}
+
+	client, err := imapClient.DialTLS(p.addr, nil)
+	if err != nil {
+		return errors.Wrap(err, "failed to connect to server")
+	}
+	client.ErrorLog = &imapErrorLogger{logrus.WithField("pkg", "imap-client")}
+	// Logrus have Writer helper but it fails for big messages because of
+	// bufio.MaxScanTokenSize limit.
+	// This spams a lot, uncomment once needed during development.
+	//client.SetDebug(&imapDebugLogger{logrus.WithField("pkg", "imap-client")})
+	p.client = client
+
+	log.Info("Connected")
+
+	if (p.client.State() & imap.AuthenticatedState) == imap.AuthenticatedState {
+		return nil
+	}
+
+	capability, err := p.client.Capability()
+	log.WithField("capability", capability).WithError(err).Debug("Server capability")
+	if err != nil {
+		return errors.Wrap(err, "failed to get capabilities")
+	}
+
+	// SASL AUTH PLAIN
+	if ok, _ := p.client.SupportAuth("PLAIN"); p.client.State() == imap.NotAuthenticatedState && ok {
+		log.Debug("Trying plain auth")
+		authPlain := sasl.NewPlainClient("", p.username, p.password)
+		if err = p.client.Authenticate(authPlain); err != nil {
+			return errors.Wrap(err, "plain auth failed")
+		}
+	}
+
+	// LOGIN: if the server reports the IMAP4rev1 capability then it is standards conformant and must support login.
+	if ok, _ := p.client.Support("IMAP4rev1"); p.client.State() == imap.NotAuthenticatedState && ok {
+		log.Debug("Trying login")
+		if err = p.client.Login(p.username, p.password); err != nil {
+			return errors.Wrap(err, "login failed")
+		}
+	}
+
+	if p.client.State() == imap.NotAuthenticatedState {
+		return errors.New("unknown auth method")
+	}
+
+	log.Info("Logged in")
+
+	idClient := imapID.NewClient(p.client)
+	if ok, err := idClient.SupportID(); err == nil && ok {
+		serverID, err := idClient.ID(imapID.ID{
+			imapID.FieldName:    "ImportExport",
+			imapID.FieldVersion: "beta",
+		})
+		log.WithField("ID", serverID).WithError(err).Debug("Server info")
+	}
+
+	return err
+}
+
+func (p *IMAPProvider) list() (mailboxes []*imap.MailboxInfo, err error) {
+	err = p.ensureConnection(func() error {
+		mailboxesCh := make(chan *imap.MailboxInfo)
+		doneCh := make(chan error)
+
+		go func() {
+			doneCh <- p.client.List("", "*", mailboxesCh)
+		}()
+
+		for mailbox := range mailboxesCh {
+			mailboxes = append(mailboxes, mailbox)
+		}
+
+		return <-doneCh
+	})
+	return
+}
+
+func (p *IMAPProvider) selectIn(mailboxName string) (mailbox *imap.MailboxStatus, err error) {
+	err = p.ensureConnection(func() error {
+		mailbox, err = p.client.Select(mailboxName, true)
+		return err
+	})
+	return
+}
+
+func (p *IMAPProvider) fetch(seqSet *imap.SeqSet, items []imap.FetchItem, processMessageCallback func(m *imap.Message)) error {
+	return p.fetchHelper(false, seqSet, items, processMessageCallback)
+}
+
+func (p *IMAPProvider) uidFetch(seqSet *imap.SeqSet, items []imap.FetchItem, processMessageCallback func(m *imap.Message)) error {
+	return p.fetchHelper(true, seqSet, items, processMessageCallback)
+}
+
+func (p *IMAPProvider) fetchHelper(uid bool, seqSet *imap.SeqSet, items []imap.FetchItem, processMessageCallback func(m *imap.Message)) error {
+	return p.ensureConnection(func() error {
+		messagesCh := make(chan *imap.Message)
+		doneCh := make(chan error)
+
+		go func() {
+			if uid {
+				doneCh <- p.client.UidFetch(seqSet, items, messagesCh)
+			} else {
+				doneCh <- p.client.Fetch(seqSet, items, messagesCh)
+			}
+		}()
+
+		for message := range messagesCh {
+			processMessageCallback(message)
+		}
+
+		err := <-doneCh
+		return err
+	})
+}