feat: Add RemoteAddr to SMTPSession (#548)

Signed-off-by: James Hillyerd <james@hillyerd.com>

pkg/extension/event/events.go

@@ -50,6 +50,7 @@ type SMTPResponse struct {
 
 // SMTPSession captures SMTP `MAIL FROM` & `RCPT TO` values prior to mail DATA being received.
 type SMTPSession struct {
-	From *mail.Address
-	To   []*mail.Address
+	From       *mail.Address
+	To         []*mail.Address
+	RemoteAddr string
 }

pkg/extension/luahost/bind_smtpsession.go

@@ -47,20 +47,22 @@ func checkSMTPSession(ls *lua.LState, pos int) *event.SMTPSession {
 // Gets a field value from SMTPSession user object.  This emulates a Lua table,
 // allowing `msg.subject` instead of a Lua object syntax of `msg:subject()`.
 func smtpSessionIndex(ls *lua.LState) int {
-	m := checkSMTPSession(ls, 1)
+	session := checkSMTPSession(ls, 1)
 	field := ls.CheckString(2)
 
 	// Push the requested field's value onto the stack.
 	switch field {
 	case "from":
-		ls.Push(wrapMailAddress(ls, m.From))
+		ls.Push(wrapMailAddress(ls, session.From))
 	case "to":
 		lt := &lua.LTable{}
-		for _, v := range m.To {
+		for _, v := range session.To {
 			addr := v
 			lt.Append(wrapMailAddress(ls, addr))
 		}
 		ls.Push(lt)
+	case "remote_addr":
+		ls.Push(lua.LString(session.RemoteAddr))
 	default:
 		// Unknown field.
 		ls.Push(lua.LNil)

pkg/extension/luahost/bind_smtpsession_test.go

@@ -16,23 +16,26 @@ func TestSMTPSessionGetters(t *testing.T) {
 			{Name: "name2", Address: "addr2"},
 			{Name: "name3", Address: "addr3"},
 		},
+		RemoteAddr: "1.2.3.4",
 	}
 	script := `
-		assert(msg, "msg should not be nil")
+		assert(session, "session should not be nil")
 
-		assert_eq(msg.from.name, "name1", "from.name")
-		assert_eq(msg.from.address, "addr1", "from.address")
+		assert_eq(session.from.name, "name1", "from.name")
+		assert_eq(session.from.address, "addr1", "from.address")
 
-		assert_eq(#msg.to, 2, "#msg.to")
-		assert_eq(msg.to[1].name, "name2", "to[1].name")
-		assert_eq(msg.to[1].address, "addr2", "to[1].address")
-		assert_eq(msg.to[2].name, "name3", "to[2].name")
-		assert_eq(msg.to[2].address, "addr3", "to[2].address")
+		assert_eq(#session.to, 2, "#session.to")
+		assert_eq(session.to[1].name, "name2", "to[1].name")
+		assert_eq(session.to[1].address, "addr2", "to[1].address")
+		assert_eq(session.to[2].name, "name3", "to[2].name")
+		assert_eq(session.to[2].address, "addr3", "to[2].address")
+
+		assert_eq(session.remote_addr, "1.2.3.4")
 	`
 
 	ls, _ := test.NewLuaState()
 	registerSMTPSessionType(ls)
 	registerMailAddressType(ls)
-	ls.SetGlobal("msg", wrapSMTPSession(ls, want))
+	ls.SetGlobal("session", wrapSMTPSession(ls, want))
 	require.NoError(t, ls.DoString(script))
 }

pkg/server/smtp/handler.go

@@ -116,7 +116,11 @@ type Session struct {
 // NewSession creates a new Session for the given connection
 func NewSession(server *Server, id int, conn net.Conn, logger zerolog.Logger) *Session {
 	reader := bufio.NewReader(conn)
-	host, _, _ := net.SplitHostPort(conn.RemoteAddr().String())
+
+	remoteHost := conn.RemoteAddr().String()
+	if host, _, err := net.SplitHostPort(remoteHost); err == nil {
+		remoteHost = host
+	}
 
 	session := &Session{
 		Server:     server,
@@ -124,7 +128,7 @@ func NewSession(server *Server, id int, conn net.Conn, logger zerolog.Logger) *S
 		conn:       conn,
 		state:      GREET,
 		reader:     reader,
-		remoteHost: host,
+		remoteHost: remoteHost,
 		recipients: make([]*policy.Recipient, 0),
 		logger:     logger,
 		debug:      server.config.Debug,
@@ -454,9 +458,14 @@ func (s *Session) parseMailFromCmd(arg string) {
 		return
 	}
 
+	// Add from to extSession for inspection.
+	extSession := s.extSession()
+	addrCopy := origin.Address
+	extSession.From = &addrCopy
+
 	// Process through extensions.
 	extAction := event.ActionDefer
-	extResult := s.extHost.Events.BeforeMailFromAccepted.Emit(&event.SMTPSession{From: &origin.Address})
+	extResult := s.extHost.Events.BeforeMailFromAccepted.Emit(extSession)
 	if extResult != nil {
 		extAction = extResult.Action
 	}
@@ -711,7 +720,11 @@ func (s *Session) ooSeq(cmd string) {
 
 // extSession builds an SMTPSession for extensions.
 func (s *Session) extSession() *event.SMTPSession {
-	from := s.from.Address
+	var from *mail.Address
+	if s.from != nil {
+		addr := s.from.Address
+		from = &addr
+	}
 	to := make([]*mail.Address, 0, len(s.recipients))
 	for _, recip := range s.recipients {
 		addr := recip.Address
@@ -719,7 +732,8 @@ func (s *Session) extSession() *event.SMTPSession {
 	}
 
 	return &event.SMTPSession{
-		From: &from,
-		To:   to,
+		From:       from,
+		To:         to,
+		RemoteAddr: s.remoteHost,
 	}
 }

pkg/server/smtp/handler_test.go

@@ -408,6 +408,7 @@ func TestBeforeMailFromAcceptedEventEmitted(t *testing.T) {
 
 	assert.NotNil(t, got, "BeforeMailListener did not receive Address")
 	assert.Equal(t, "john@gmail.com", got.From.Address, "Address had wrong value")
+	assert.Equal(t, "pipe", got.RemoteAddr, "RemoteAddr had wrong value")
 }
 
 // Test "MAIL FROM" acts on BeforeMailFromAccepted event result.
@@ -492,6 +493,7 @@ func TestBeforeRcptToAcceptedSingleEventEmitted(t *testing.T) {
 	require.NotNil(t, got, "BeforeRcptToListener did not receive SMTPSession")
 	require.NotNil(t, got.From)
 	require.NotNil(t, got.To)
+	assert.Equal(t, "pipe", got.RemoteAddr, "RemoteAddr had wrong value")
 	assert.Equal(t, "john@gmail.com", got.From.Address)
 	assert.Len(t, got.To, 1)
 	assert.Equal(t, "user@gmail.com", got.To[0].Address)