From 434ddca4792e01967fd3993ecb3b9662605a6786 Mon Sep 17 00:00:00 2001
From: "fox.cpp" <fox.cpp@disroot.org>
Date: Sun, 21 Jan 2024 14:16:31 +0300
Subject: [PATCH] Parse DATA\r\n\r\n.\r\n as \r\n\r\n message

---
 data.go        |  4 ++++
 server_test.go | 39 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 43 insertions(+)

diff --git a/data.go b/data.go
index 4456774..7ee8dbc 100644
--- a/data.go
+++ b/data.go
@@ -106,6 +106,10 @@ func (r *dataReader) Read(b []byte) (n int, err error) {
 				r.state = stateDot
 				continue
 			}
+			if c == '\r' {
+				r.state = stateCR
+				break
+			}
 			r.state = stateData
 		case stateDot:
 			if c == '\r' {
diff --git a/server_test.go b/server_test.go
index cc6543b..f814407 100644
--- a/server_test.go
+++ b/server_test.go
@@ -636,6 +636,45 @@ func TestServer_LFDotLF(t *testing.T) {
 	}
 }
 
+func TestServer_EmptyMessage(t *testing.T) {
+	be, s, c, scanner := testServerAuthenticated(t)
+	defer s.Close()
+	defer c.Close()
+
+	io.WriteString(c, "MAIL FROM:<root@nsa.gov>\r\n")
+	scanner.Scan()
+	if !strings.HasPrefix(scanner.Text(), "250 ") {
+		t.Fatal("Invalid MAIL response:", scanner.Text())
+	}
+
+	io.WriteString(c, "RCPT TO:<root@gchq.gov.uk>\r\n")
+	scanner.Scan()
+	if !strings.HasPrefix(scanner.Text(), "250 ") {
+		t.Fatal("Invalid RCPT response:", scanner.Text())
+	}
+
+	io.WriteString(c, "DATA\r\n")
+	scanner.Scan()
+	if !strings.HasPrefix(scanner.Text(), "354 ") {
+		t.Fatal("Invalid DATA response:", scanner.Text())
+	}
+
+	io.WriteString(c, "\r\n\r\n.\r\n")
+	scanner.Scan()
+	if !strings.HasPrefix(scanner.Text(), "250 ") {
+		t.Fatal("Invalid DATA response:", scanner.Text())
+	}
+
+	if len(be.messages) != 1 || len(be.anonmsgs) != 0 {
+		t.Fatal("Invalid number of sent messages:", be.messages, be.anonmsgs)
+	}
+
+	msg := be.messages[0]
+	if string(msg.Data) != "\r\n\r\n" {
+		t.Fatal("Invalid mail data:", string(msg.Data), msg.Data)
+	}
+}
+
 func TestServer_authDisabled(t *testing.T) {
 	_, s, c, scanner, caps := testServerEhlo(t, authDisabled)
 	defer s.Close()