Upgrade to latest go-smtp

internal/smtp/backend.go

@@ -27,6 +27,7 @@ import (
 	"github.com/ProtonMail/proton-bridge/pkg/confirmer"
 	"github.com/ProtonMail/proton-bridge/pkg/listener"
 	goSMTPBackend "github.com/emersion/go-smtp"
+	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
 )
 
@@ -70,7 +71,7 @@ func newSMTPBackend(
 }
 
 // Login authenticates a user.
-func (sb *smtpBackend) Login(username, password string) (goSMTPBackend.User, error) {
+func (sb *smtpBackend) Login(_ *goSMTPBackend.ConnectionState, username, password string) (goSMTPBackend.Session, error) {
 	// Called from go-smtp in goroutines - we need to handle panics for each function.
 	defer sb.panicHandler.HandlePanic()
 	username = strings.ToLower(username)
@@ -97,7 +98,14 @@ func (sb *smtpBackend) Login(username, password string) (goSMTPBackend.User, err
 	if user.IsCombinedAddressMode() {
 		addressID = ""
 	}
-	return newSMTPUser(sb.panicHandler, sb.eventListener, sb, user, addressID)
+	return newSMTPUser(sb.panicHandler, sb.eventListener, sb, user, username, addressID)
+}
+
+func (sb *smtpBackend) AnonymousLogin(_ *goSMTPBackend.ConnectionState) (goSMTPBackend.Session, error) {
+	// Called from go-smtp in goroutines - we need to handle panics for each function.
+	defer sb.panicHandler.HandlePanic()
+
+	return nil, errors.New("anonymous login not supported")
 }
 
 func (sb *smtpBackend) shouldReportOutgoingNoEnc() bool {

internal/smtp/server.go

@@ -51,12 +51,12 @@ func NewSMTPServer(debug bool, port int, useSSL bool, tls *tls.Config, smtpBacke
 
 	s.EnableAuth(sasl.Login, func(conn *goSMTP.Conn) sasl.Server {
 		return sasl.NewLoginServer(func(address, password string) error {
-			user, err := conn.Server().Backend.Login(address, password)
+			user, err := conn.Server().Backend.Login(nil, address, password)
 			if err != nil {
 				return err
 			}
 
-			conn.SetUser(user)
+			conn.SetSession(user)
 			return nil
 		})
 	})
@@ -85,14 +85,16 @@ func (s *smtpServer) ListenAndServe() {
 		l.Error("SMTP failed: ", err)
 		return
 	}
-	defer s.server.Close()
+	defer s.server.Close() //nolint[errcheck]
 
 	l.Info("SMTP server stopped")
 }
 
 // Stops the server.
 func (s *smtpServer) Close() {
-	s.server.Close()
+	if err := s.server.Close(); err != nil {
+		log.WithError(err).Error("Failed to close the connection")
+	}
 }
 
 func (s *smtpServer) monitorDisconnectedUsers() {
@@ -102,9 +104,11 @@ func (s *smtpServer) monitorDisconnectedUsers() {
 	for address := range ch {
 		log.Info("Disconnecting all open SMTP connections for ", address)
 		disconnectUser := func(conn *goSMTP.Conn) {
-			connUser := conn.User()
+			connUser := conn.Session()
 			if connUser != nil {
-				_ = conn.Close()
+				if err := conn.Close(); err != nil {
+					log.WithError(err).Error("Failed to close the connection")
+				}
 			}
 		}
 		s.server.ForEachConn(disconnectUser)

internal/smtp/user.go

@@ -44,7 +44,11 @@ type smtpUser struct {
 	backend       *smtpBackend
 	user          bridgeUser
 	storeUser     storeUserProvider
+	username      string
 	addressID     string
+
+	from string
+	to   []string
 }
 
 // newSMTPUser returns struct implementing go-smtp/session interface.
@@ -53,8 +57,9 @@ func newSMTPUser(
 	eventListener listener.Listener,
 	smtpBackend *smtpBackend,
 	user bridgeUser,
+	username string,
 	addressID string,
-) (goSMTPBackend.User, error) {
+) (goSMTPBackend.Session, error) {
 	storeUser := user.GetStore()
 	if storeUser == nil {
 		return nil, errors.New("user database is not initialized")
@@ -66,6 +71,7 @@ func newSMTPUser(
 		backend:       smtpBackend,
 		user:          user,
 		storeUser:     storeUser,
+		username:      username,
 		addressID:     addressID,
 	}, nil
 }
@@ -145,6 +151,55 @@ func (su *smtpUser) getAPIKeyData(recipient string) (apiKeys []pmapi.PublicKey,
 	return su.client().GetPublicKeysForEmail(recipient)
 }
 
+// Discard currently processed message.
+func (su *smtpUser) Reset() {
+	log.Trace("Resetting the session")
+	su.from = ""
+	su.to = []string{}
+}
+
+// Set return path for currently processed message.
+func (su *smtpUser) Mail(from string, opts goSMTPBackend.MailOptions) error {
+	log.WithField("from", from).WithField("opts", opts).Trace("Setting mail from")
+
+	// REQUIRETLS and SMTPUTF8 have to be announced to be used by client.
+	// Bridge does not use those extensions so this should not happen.
+	if opts.RequireTLS {
+		return errors.New("REQUIRETLS extension is not supported")
+	}
+	if opts.UTF8 {
+		return errors.New("SMTPUTF8 extension is not supported")
+	}
+
+	if opts.Auth != nil && *opts.Auth != "" && *opts.Auth != su.username {
+		return errors.New("changing identity is not supported")
+	}
+
+	su.from = from
+	return nil
+}
+
+// Add recipient for currently processed message.
+func (su *smtpUser) Rcpt(to string) error {
+	log.WithField("to", to).Trace("Adding recipient")
+	if to != "" {
+		su.to = append(su.to, to)
+	}
+	return nil
+}
+
+// Set currently processed message contents and send it.
+func (su *smtpUser) Data(r io.Reader) error {
+	log.Trace("Sending the message")
+	if su.from == "" {
+		return errors.New("missing sender")
+	}
+	if len(su.to) == 0 {
+		return errors.New("missing recipient")
+	}
+	return su.Send(su.from, su.to, r)
+}
+
 // Send sends an email from the given address to the given addresses with the given body.
 func (su *smtpUser) Send(from string, to []string, messageReader io.Reader) (err error) { //nolint[funlen]
 	// Called from go-smtp in goroutines - we need to handle panics for each function.