adjust auto-retry, fix banned response code, rewrite email composing to enmime, add more logs

smtp/server.go

@@ -2,7 +2,6 @@ package smtp
 
 import (
 	"context"
-	"errors"
 	"io"
 	"strings"
 
@@ -14,6 +13,13 @@ import (
 	"gitlab.com/etke.cc/postmoogle/utils"
 )
 
+// ErrBanned returned to banned hosts
+var ErrBanned = &smtp.SMTPError{
+	Code:         554,
+	EnhancedCode: smtp.EnhancedCode{5, 5, 4},
+	Message:      "please, don't bother me anymore, kupo.",
+}
+
 type mailServer struct {
 	bot     matrixbot
 	log     *logger.Logger
@@ -24,17 +30,19 @@ type mailServer struct {
 func (m *mailServer) Login(state *smtp.ConnectionState, username, password string) (smtp.Session, error) {
 	m.log.Debug("Login state=%+v username=%+v", state, username)
 	if m.bot.IsBanned(state.RemoteAddr) {
-		return nil, errors.New("please, don't bother me anymore")
+		return nil, ErrBanned
 	}
 
 	if !utils.AddressValid(username) {
+		m.log.Debug("address %s is invalid", username)
 		m.bot.Ban(state.RemoteAddr)
-		return nil, errors.New("please, provide an email address")
+		return nil, ErrBanned
 	}
 
 	if !m.bot.AllowAuth(username, password) {
+		m.log.Debug("username=%s or password=<redacted> is invalid", username)
 		m.bot.Ban(state.RemoteAddr)
-		return nil, errors.New("email or password is invalid")
+		return nil, ErrBanned
 	}
 
 	return &outgoingSession{
@@ -51,7 +59,7 @@ func (m *mailServer) Login(state *smtp.ConnectionState, username, password strin
 func (m *mailServer) AnonymousLogin(state *smtp.ConnectionState) (smtp.Session, error) {
 	m.log.Debug("AnonymousLogin state=%+v", state)
 	if m.bot.IsBanned(state.RemoteAddr) {
-		return nil, errors.New("please, don't bother me anymore")
+		return nil, ErrBanned
 	}
 
 	return &incomingSession{

smtp/session.go

@@ -35,8 +35,9 @@ type incomingSession struct {
 func (s *incomingSession) Mail(from string, opts smtp.MailOptions) error {
 	sentry.GetHubFromContext(s.ctx).Scope().SetTag("from", from)
 	if !utils.AddressValid(from) {
+		s.log.Debug("address %s is invalid", from)
 		s.ban(s.addr)
-		return errors.New("please, provide email address")
+		return ErrBanned
 	}
 	s.from = from
 	s.log.Debug("mail from %s, options: %+v", from, opts)
@@ -56,20 +57,20 @@ func (s *incomingSession) Rcpt(to string) error {
 	if !domainok {
 		s.log.Debug("wrong domain of %s", to)
 		s.ban(s.addr)
-		return smtp.ErrAuthRequired
+		return ErrBanned
 	}
 
 	roomID, ok := s.getRoomID(utils.Mailbox(to))
 	if !ok {
 		s.log.Debug("mapping for %s not found", to)
 		s.ban(s.addr)
-		return smtp.ErrAuthRequired
+		return ErrBanned
 	}
 
 	validations := s.getFilters(roomID)
 	if !validateEmail(s.from, s.to, s.log, validations) {
 		s.ban(s.addr)
-		return smtp.ErrAuthRequired
+		return ErrBanned
 	}
 
 	s.log.Debug("mail to %s", to)