smtp/smtp_test.go

@@ -1391,308 +1391,252 @@ func TestScramAuth_handleServerFirstResponse(t *testing.T) {
 			t.Errorf("expected error to be %q, got %q", expectedErr, err)
 		}
 	})
+
 }
 
-func TestCRAMMD5Auth(t *testing.T) {
+/*
-	t.Run("CRAM-MD5 on test server succeeds", func(t *testing.T) {
+
-		ctx, cancel := context.WithCancel(context.Background())
+
-		defer cancel()
+
-		PortAdder.Add(1)
+
-		serverPort := int(TestServerPortBase + PortAdder.Load())
+
-		featureSet := "250-AUTH CRAM-MD5\r\n250-8BITMIME\r\n250-DSN\r\n250 SMTPUTF8"
+
+func TestAuthSCRAMSHA1_OK(t *testing.T) {
+	hostname := "127.0.0.1"
+	port := "2585"
+
 	go func() {
-			if err := simpleSMTPServer(ctx, t, &serverProps{
+		startSMTPServer(false, hostname, port, sha1.New)
-				FeatureSet: featureSet,
+	}()
-				ListenPort: serverPort,
+	time.Sleep(time.Millisecond * 500)
-			},
+
-			); err != nil {
+	conn, err := net.Dial("tcp", fmt.Sprintf("%s:%s", hostname, port))
-				t.Errorf("failed to start test server: %s", err)
+	if err != nil {
+		t.Errorf("failed to dial server: %v", err)
+	}
+	client, err := NewClient(conn, hostname)
+	if err != nil {
+		t.Errorf("failed to create client: %v", err)
+	}
+	if err = client.Hello(hostname); err != nil {
+		t.Errorf("failed to send HELO: %v", err)
+	}
+	if err = client.Auth(ScramSHA1Auth("username", "password")); err != nil {
+		t.Errorf("failed to authenticate: %v", err)
+	}
+}
+
+func TestAuthSCRAMSHA256_OK(t *testing.T) {
+	hostname := "127.0.0.1"
+	port := "2586"
+
+	go func() {
+		startSMTPServer(false, hostname, port, sha256.New)
+	}()
+	time.Sleep(time.Millisecond * 500)
+
+	conn, err := net.Dial("tcp", fmt.Sprintf("%s:%s", hostname, port))
+	if err != nil {
+		t.Errorf("failed to dial server: %v", err)
+	}
+	client, err := NewClient(conn, hostname)
+	if err != nil {
+		t.Errorf("failed to create client: %v", err)
+	}
+	if err = client.Hello(hostname); err != nil {
+		t.Errorf("failed to send HELO: %v", err)
+	}
+	if err = client.Auth(ScramSHA256Auth("username", "password")); err != nil {
+		t.Errorf("failed to authenticate: %v", err)
+	}
+}
+
+func TestAuthSCRAMSHA1PLUS_OK(t *testing.T) {
+	hostname := "127.0.0.1"
+	port := "2590"
+
+	go func() {
+		startSMTPServer(true, hostname, port, sha1.New)
+	}()
+	time.Sleep(time.Millisecond * 500)
+
+	cert, err := tls.X509KeyPair(localhostCert, localhostKey)
+	if err != nil {
+		fmt.Printf("error creating TLS cert: %s", err)
 		return
 	}
-		}()
+	tlsConfig := tls.Config{Certificates: []tls.Certificate{cert}, InsecureSkipVerify: true}
-		time.Sleep(time.Millisecond * 30)
 
-		auth := CRAMMD5Auth("username", "password")
+	conn, err := tls.Dial("tcp", fmt.Sprintf("%s:%s", hostname, port), &tlsConfig)
-		client, err := Dial(fmt.Sprintf("%s:%d", TestServerAddr, serverPort))
 	if err != nil {
-			t.Fatalf("failed to dial to test server: %s", err)
+		t.Errorf("failed to dial server: %v", err)
 	}
-		if err = client.Auth(auth); err != nil {
+	client, err := NewClient(conn, hostname)
-			t.Errorf("failed to auth to test server: %s", err)
+	if err != nil {
+		t.Errorf("failed to create client: %v", err)
 	}
-	})
+	if err = client.Hello(hostname); err != nil {
-	t.Run("CRAM-MD5 on test server fails", func(t *testing.T) {
+		t.Errorf("failed to send HELO: %v", err)
-		ctx, cancel := context.WithCancel(context.Background())
+	}
-		defer cancel()
+
-		PortAdder.Add(1)
+	tlsConnState := conn.ConnectionState()
-		serverPort := int(TestServerPortBase + PortAdder.Load())
+	if err = client.Auth(ScramSHA1PlusAuth("username", "password", &tlsConnState)); err != nil {
-		featureSet := "250-AUTH CRAM-MD5\r\n250-8BITMIME\r\n250-DSN\r\n250 SMTPUTF8"
+		t.Errorf("failed to authenticate: %v", err)
+	}
+}
+
+func TestAuthSCRAMSHA256PLUS_OK(t *testing.T) {
+	hostname := "127.0.0.1"
+	port := "2591"
+
 	go func() {
-			if err := simpleSMTPServer(ctx, t, &serverProps{
+		startSMTPServer(true, hostname, port, sha256.New)
-				FailOnAuth: true,
+	}()
-				FeatureSet: featureSet,
+	time.Sleep(time.Millisecond * 500)
-				ListenPort: serverPort,
+
-			},
+	cert, err := tls.X509KeyPair(localhostCert, localhostKey)
-			); err != nil {
+	if err != nil {
-				t.Errorf("failed to start test server: %s", err)
+		fmt.Printf("error creating TLS cert: %s", err)
 		return
 	}
-		}()
+	tlsConfig := tls.Config{Certificates: []tls.Certificate{cert}, InsecureSkipVerify: true}
-		time.Sleep(time.Millisecond * 30)
 
-		auth := CRAMMD5Auth("username", "password")
+	conn, err := tls.Dial("tcp", fmt.Sprintf("%s:%s", hostname, port), &tlsConfig)
-		client, err := Dial(fmt.Sprintf("%s:%d", TestServerAddr, serverPort))
 	if err != nil {
-			t.Fatalf("failed to dial to test server: %s", err)
+		t.Errorf("failed to dial server: %v", err)
 	}
-		if err = client.Auth(auth); err == nil {
+	client, err := NewClient(conn, hostname)
-			t.Error("auth should fail on test server")
+	if err != nil {
+		t.Errorf("failed to create client: %v", err)
 	}
-	})
+	if err = client.Hello(hostname); err != nil {
+		t.Errorf("failed to send HELO: %v", err)
 	}
 
-func TestNewClient(t *testing.T) {
+	tlsConnState := conn.ConnectionState()
-	t.Run("new client via Dial succeeds", func(t *testing.T) {
+	if err = client.Auth(ScramSHA256PlusAuth("username", "password", &tlsConnState)); err != nil {
-		ctx, cancel := context.WithCancel(context.Background())
+		t.Errorf("failed to authenticate: %v", err)
-		defer cancel()
+	}
-		PortAdder.Add(1)
+}
-		serverPort := int(TestServerPortBase + PortAdder.Load())
+
-		featureSet := "250-8BITMIME\r\n250-DSN\r\n250 SMTPUTF8"
+func TestAuthSCRAMSHA1_fail(t *testing.T) {
+	hostname := "127.0.0.1"
+	port := "2587"
+
 	go func() {
-			if err := simpleSMTPServer(ctx, t, &serverProps{
+		startSMTPServer(false, hostname, port, sha1.New)
-				FeatureSet: featureSet,
+	}()
-				ListenPort: serverPort,
+	time.Sleep(time.Millisecond * 500)
-			},
+
-			); err != nil {
+	conn, err := net.Dial("tcp", fmt.Sprintf("%s:%s", hostname, port))
-				t.Errorf("failed to start test server: %s", err)
+	if err != nil {
+		t.Errorf("failed to dial server: %v", err)
+	}
+	client, err := NewClient(conn, hostname)
+	if err != nil {
+		t.Errorf("failed to create client: %v", err)
+	}
+	if err = client.Hello(hostname); err != nil {
+		t.Errorf("failed to send HELO: %v", err)
+	}
+	if err = client.Auth(ScramSHA1Auth("username", "invalid")); err == nil {
+		t.Errorf("expected auth error, got nil")
+	}
+}
+
+func TestAuthSCRAMSHA256_fail(t *testing.T) {
+	hostname := "127.0.0.1"
+	port := "2588"
+
+	go func() {
+		startSMTPServer(false, hostname, port, sha256.New)
+	}()
+	time.Sleep(time.Millisecond * 500)
+
+	conn, err := net.Dial("tcp", fmt.Sprintf("%s:%s", hostname, port))
+	if err != nil {
+		t.Errorf("failed to dial server: %v", err)
+	}
+	client, err := NewClient(conn, hostname)
+	if err != nil {
+		t.Errorf("failed to create client: %v", err)
+	}
+	if err = client.Hello(hostname); err != nil {
+		t.Errorf("failed to send HELO: %v", err)
+	}
+	if err = client.Auth(ScramSHA256Auth("username", "invalid")); err == nil {
+		t.Errorf("expected auth error, got nil")
+	}
+}
+
+func TestAuthSCRAMSHA1PLUS_fail(t *testing.T) {
+	hostname := "127.0.0.1"
+	port := "2592"
+
+	go func() {
+		startSMTPServer(true, hostname, port, sha1.New)
+	}()
+	time.Sleep(time.Millisecond * 500)
+
+	cert, err := tls.X509KeyPair(localhostCert, localhostKey)
+	if err != nil {
+		fmt.Printf("error creating TLS cert: %s", err)
 		return
 	}
-		}()
+	tlsConfig := tls.Config{Certificates: []tls.Certificate{cert}, InsecureSkipVerify: true}
-		time.Sleep(time.Millisecond * 30)
 
-		client, err := Dial(fmt.Sprintf("%s:%d", TestServerAddr, serverPort))
+	conn, err := tls.Dial("tcp", fmt.Sprintf("%s:%s", hostname, port), &tlsConfig)
 	if err != nil {
-			t.Errorf("failed to create client: %s", err)
+		t.Errorf("failed to dial server: %v", err)
 	}
-		if err := client.Close(); err != nil {
+	client, err := NewClient(conn, hostname)
-			t.Errorf("failed to close client: %s", err)
+	if err != nil {
+		t.Errorf("failed to create client: %v", err)
 	}
-	})
+	if err = client.Hello(hostname); err != nil {
-	t.Run("new client via Dial fails on server not started", func(t *testing.T) {
+		t.Errorf("failed to send HELO: %v", err)
-		_, err := Dial(fmt.Sprintf("%s:%d", TestServerAddr, 64000))
-		if err == nil {
-			t.Error("dial on non-existant server should fail")
 	}
-	})
+	tlsConnState := conn.ConnectionState()
-	t.Run("new client fails on server not available", func(t *testing.T) {
+	if err = client.Auth(ScramSHA1PlusAuth("username", "invalid", &tlsConnState)); err == nil {
-		ctx, cancel := context.WithCancel(context.Background())
+		t.Errorf("expected auth error, got nil")
-		defer cancel()
+	}
-		PortAdder.Add(1)
+}
-		serverPort := int(TestServerPortBase + PortAdder.Load())
+
-		featureSet := "250-8BITMIME\r\n250-DSN\r\n250 SMTPUTF8"
+func TestAuthSCRAMSHA256PLUS_fail(t *testing.T) {
+	hostname := "127.0.0.1"
+	port := "2593"
+
 	go func() {
-			if err := simpleSMTPServer(ctx, t, &serverProps{
+		startSMTPServer(true, hostname, port, sha1.New)
-				FailOnDial: true,
+	}()
-				FeatureSet: featureSet,
+	time.Sleep(time.Millisecond * 500)
-				ListenPort: serverPort,
+
-			},
+	cert, err := tls.X509KeyPair(localhostCert, localhostKey)
-			); err != nil {
+	if err != nil {
-				t.Errorf("failed to start test server: %s", err)
+		fmt.Printf("error creating TLS cert: %s", err)
 		return
 	}
-		}()
+	tlsConfig := tls.Config{Certificates: []tls.Certificate{cert}, InsecureSkipVerify: true}
-		time.Sleep(time.Millisecond * 30)
 
-		_, err := Dial(fmt.Sprintf("%s:%d", TestServerAddr, serverPort))
+	conn, err := tls.Dial("tcp", fmt.Sprintf("%s:%s", hostname, port), &tlsConfig)
-		if err == nil {
-			t.Error("connection to non-available server should fail")
-		}
-	})
-	t.Run("new client fails on faker that fails on close", func(t *testing.T) {
-		server := "442 service not available\r\n"
-		var wrote strings.Builder
-		var fake faker
-		fake.failOnClose = true
-		fake.ReadWriter = struct {
-			io.Reader
-			io.Writer
-		}{
-			strings.NewReader(server),
-			&wrote,
-		}
-		_, err := NewClient(fake, "faker.host")
-		if err == nil {
-			t.Error("connection to non-available server should fail on close")
-		}
-	})
-}
-
-func TestClient_hello(t *testing.T) {
-	t.Run("client fails on EHLO but not on HELO", func(t *testing.T) {
-		ctx, cancel := context.WithCancel(context.Background())
-		defer cancel()
-		PortAdder.Add(1)
-		serverPort := int(TestServerPortBase + PortAdder.Load())
-		featureSet := "250-8BITMIME\r\n250-DSN\r\n250 SMTPUTF8"
-		go func() {
-			if err := simpleSMTPServer(ctx, t, &serverProps{
-				FailOnEhlo: true,
-				FailOnHelo: true,
-				FeatureSet: featureSet,
-				ListenPort: serverPort,
-			},
-			); err != nil {
-				t.Errorf("failed to start test server: %s", err)
-				return
-			}
-		}()
-		time.Sleep(time.Millisecond * 30)
-
-		client, err := Dial(fmt.Sprintf("%s:%d", TestServerAddr, serverPort))
 	if err != nil {
-			t.Errorf("failed to dial to test server: %s", err)
+		t.Errorf("failed to dial server: %v", err)
 	}
-		if err = client.hello(); err == nil {
+	client, err := NewClient(conn, hostname)
-			t.Error("helo should fail on test server")
-		}
-	})
-}
-
-func TestClient_Hello(t *testing.T) {
-	t.Run("normal client HELO/EHLO", func(t *testing.T) {
-		ctx, cancel := context.WithCancel(context.Background())
-		defer cancel()
-		PortAdder.Add(1)
-		serverPort := int(TestServerPortBase + PortAdder.Load())
-		featureSet := "250-8BITMIME\r\n250-DSN\r\n250 SMTPUTF8"
-		go func() {
-			if err := simpleSMTPServer(ctx, t, &serverProps{
-				FeatureSet: featureSet,
-				ListenPort: serverPort,
-			},
-			); err != nil {
-				t.Errorf("failed to start test server: %s", err)
-				return
-			}
-		}()
-		time.Sleep(time.Millisecond * 30)
-
-		client, err := Dial(fmt.Sprintf("%s:%d", TestServerAddr, serverPort))
 	if err != nil {
-			t.Errorf("failed to dial to test server: %s", err)
+		t.Errorf("failed to create client: %v", err)
 	}
-		if err = client.Hello(TestServerAddr); err != nil {
+	if err = client.Hello(hostname); err != nil {
-			t.Errorf("failed to send HELO/EHLO to test server: %s", err)
+		t.Errorf("failed to send HELO: %v", err)
 	}
-	})
+	tlsConnState := conn.ConnectionState()
-	t.Run("client HELO/EHLO with empty name should fail", func(t *testing.T) {
+	if err = client.Auth(ScramSHA256PlusAuth("username", "invalid", &tlsConnState)); err == nil {
-		ctx, cancel := context.WithCancel(context.Background())
+		t.Errorf("expected auth error, got nil")
-		defer cancel()
-		PortAdder.Add(1)
-		serverPort := int(TestServerPortBase + PortAdder.Load())
-		featureSet := "250-8BITMIME\r\n250-DSN\r\n250 SMTPUTF8"
-		go func() {
-			if err := simpleSMTPServer(ctx, t, &serverProps{
-				FeatureSet: featureSet,
-				ListenPort: serverPort,
-			},
-			); err != nil {
-				t.Errorf("failed to start test server: %s", err)
-				return
 	}
-		}()
-		time.Sleep(time.Millisecond * 30)
-
-		client, err := Dial(fmt.Sprintf("%s:%d", TestServerAddr, serverPort))
-		if err != nil {
-			t.Errorf("failed to dial to test server: %s", err)
-		}
-		if err = client.Hello(""); err == nil {
-			t.Error("HELO/EHLO with empty name should fail")
-		}
-	})
-	t.Run("client HELO/EHLO with newline in name should fail", func(t *testing.T) {
-		ctx, cancel := context.WithCancel(context.Background())
-		defer cancel()
-		PortAdder.Add(1)
-		serverPort := int(TestServerPortBase + PortAdder.Load())
-		featureSet := "250-8BITMIME\r\n250-DSN\r\n250 SMTPUTF8"
-		go func() {
-			if err := simpleSMTPServer(ctx, t, &serverProps{
-				FeatureSet: featureSet,
-				ListenPort: serverPort,
-			},
-			); err != nil {
-				t.Errorf("failed to start test server: %s", err)
-				return
-			}
-		}()
-		time.Sleep(time.Millisecond * 30)
-
-		client, err := Dial(fmt.Sprintf("%s:%d", TestServerAddr, serverPort))
-		if err != nil {
-			t.Errorf("failed to dial to test server: %s", err)
-		}
-		if err = client.Hello(TestServerAddr + "\r\n"); err == nil {
-			t.Error("HELO/EHLO with newline should fail")
-		}
-	})
-	t.Run("client double HELO/EHLO should fail", func(t *testing.T) {
-		ctx, cancel := context.WithCancel(context.Background())
-		defer cancel()
-		PortAdder.Add(1)
-		serverPort := int(TestServerPortBase + PortAdder.Load())
-		featureSet := "250-8BITMIME\r\n250-DSN\r\n250 SMTPUTF8"
-		go func() {
-			if err := simpleSMTPServer(ctx, t, &serverProps{
-				FeatureSet: featureSet,
-				ListenPort: serverPort,
-			},
-			); err != nil {
-				t.Errorf("failed to start test server: %s", err)
-				return
-			}
-		}()
-		time.Sleep(time.Millisecond * 30)
-
-		client, err := Dial(fmt.Sprintf("%s:%d", TestServerAddr, serverPort))
-		if err != nil {
-			t.Errorf("failed to dial to test server: %s", err)
-		}
-		if err = client.Hello(TestServerAddr); err != nil {
-			t.Errorf("failed to send HELO/EHLO to test server: %s", err)
-		}
-		if err = client.Hello(TestServerAddr); err == nil {
-			t.Error("double HELO/EHLO should fail")
-		}
-	})
-}
-
-func TestClient_cmd(t *testing.T) {
-	t.Run("cmd fails on textproto cmd", func(t *testing.T) {
-		server := "220 server ready\r\n"
-		var fake faker
-		fake.failOnClose = true
-		fake.ReadWriter = struct {
-			io.Reader
-			io.Writer
-		}{
-			strings.NewReader(server),
-			&failWriter{},
-		}
-		client, err := NewClient(fake, "faker.host")
-		if err != nil {
-			t.Errorf("failed to create client: %s", err)
-		}
-		_, _, err = client.cmd(250, "HELO faker.host")
-		if err == nil {
-			t.Error("cmd should fail on textproto cmd with broken writer")
-		}
-	})
 }
 
 // Issue 17794: don't send a trailing space on AUTH command when there's no password.
-func TestClient_Auth_trimSpace(t *testing.T) {
+func TestClientAuthTrimSpace(t *testing.T) {
 	server := "220 hello world\r\n" +
 		"200 some more"
 	var wrote strings.Builder
@@ -1711,7 +1655,7 @@ func TestClient_Auth_trimSpace(t *testing.T) {
 	c.tls = true
 	c.didHello = true
 	_ = c.Auth(toServerEmptyAuth{})
-	if err = c.Close(); err != nil {
+	if err := c.Close(); err != nil {
 		t.Errorf("close failed: %s", err)
 	}
 	if got, want := wrote.String(), "AUTH FOOAUTH\r\n*\r\nQUIT\r\n"; got != want {
@@ -1719,15 +1663,19 @@ func TestClient_Auth_trimSpace(t *testing.T) {
 	}
 }
 
-/*
+// toServerEmptyAuth is an implementation of Auth that only implements
-
+// the Start method, and returns "FOOAUTH", nil, nil. Notably, it returns
-
+// zero bytes for "toServer" so we can test that we don't send spaces at
-
+// the end of the line. See TestClientAuthTrimSpace.
-
+type toServerEmptyAuth struct{}
-
-
 
+func (toServerEmptyAuth) Start(_ *ServerInfo) (proto string, toServer []byte, err error) {
+	return "FOOAUTH", nil, nil
+}
 
+func (toServerEmptyAuth) Next(_ []byte, _ bool) (toServer []byte, err error) {
+	panic("unexpected call")
+}
 
 func TestBasic(t *testing.T) {
 	server := strings.Join(strings.Split(basicServer, "\n"), "\r\n")
@@ -3210,6 +3158,46 @@ func sendMail(hostPort string) error {
 	return SendMail(hostPort, nil, from, to, []byte("Subject: test\n\nhowdy!"))
 }
 
+// localhostCert is a PEM-encoded TLS cert generated from src/crypto/tls:
+//
+//	go run generate_cert.go --rsa-bits 1024 --host 127.0.0.1,::1,example.com \
+//		--ca --start-date "Jan 1 00:00:00 1970" --duration=1000000h
+var localhostCert = []byte(`
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----`)
+
+// localhostKey is the private key for localhostCert.
+var localhostKey = []byte(testingKey(`
+-----BEGIN RSA TESTING KEY-----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+-----END RSA TESTING KEY-----`))
+
+func testingKey(s string) string { return strings.ReplaceAll(s, "TESTING KEY", "PRIVATE KEY") }
+
 var flaky = flag.Bool("flaky", false, "run known-flaky tests too")
 
 func SkipFlaky(t testing.TB, issue int) {
@@ -3219,22 +3207,271 @@ func SkipFlaky(t testing.TB, issue int) {
 	}
 }
 
+// testSCRAMSMTPServer represents a test server for SCRAM-based SMTP authentication.
+// It does not do any acutal computation of the challenges but verifies that the expected
+// fields are present. We have actual real authentication tests for all SCRAM modes in the
+// go-mail client_test.go
+type testSCRAMSMTPServer struct {
+	authMechanism string
+	nonce         string
+	hostname      string
+	port          string
+	tlsServer     bool
+	h             func() hash.Hash
+}
+
+func (s *testSCRAMSMTPServer) handleConnection(conn net.Conn) {
+	defer func() {
+		_ = conn.Close()
+	}()
+
+	reader := bufio.NewReader(conn)
+	writer := bufio.NewWriter(conn)
+	writeLine := func(data string) error {
+		_, err := writer.WriteString(data + "\r\n")
+		if err != nil {
+			return fmt.Errorf("unable to write line: %w", err)
+		}
+		return writer.Flush()
+	}
+	writeOK := func() {
+		_ = writeLine("250 2.0.0 OK")
+	}
+
+	if err := writeLine("220 go-mail test server ready ESMTP"); err != nil {
+		return
+	}
+
+	data, err := reader.ReadString('\n')
+	if err != nil {
+		return
+	}
+	data = strings.TrimSpace(data)
+	if strings.HasPrefix(data, "EHLO") {
+		_ = writeLine(fmt.Sprintf("250-%s", s.hostname))
+		_ = writeLine("250-AUTH SCRAM-SHA-1 SCRAM-SHA-256")
+		writeOK()
+	} else {
+		_ = writeLine("500 Invalid command")
+		return
+	}
+
+	for {
+		data, err = reader.ReadString('\n')
+		if err != nil {
+			fmt.Printf("failed to read data: %v", err)
+		}
+		data = strings.TrimSpace(data)
+		if strings.HasPrefix(data, "AUTH") {
+			parts := strings.Split(data, " ")
+			if len(parts) < 2 {
+				_ = writeLine("500 Syntax error")
+				return
+			}
+
+			authMechanism := parts[1]
+			if authMechanism != "SCRAM-SHA-1" && authMechanism != "SCRAM-SHA-256" &&
+				authMechanism != "SCRAM-SHA-1-PLUS" && authMechanism != "SCRAM-SHA-256-PLUS" {
+				_ = writeLine("504 Unrecognized authentication mechanism")
+				return
+			}
+			s.authMechanism = authMechanism
+			_ = writeLine("334 ")
+			s.handleSCRAMAuth(conn)
+			return
+		} else {
+			_ = writeLine("500 Invalid command")
+		}
+	}
+}
+
+func (s *testSCRAMSMTPServer) handleSCRAMAuth(conn net.Conn) {
+	reader := bufio.NewReader(conn)
+	writer := bufio.NewWriter(conn)
+	writeLine := func(data string) error {
+		_, err := writer.WriteString(data + "\r\n")
+		if err != nil {
+			return fmt.Errorf("unable to write line: %w", err)
+		}
+		return writer.Flush()
+	}
+	var authMsg string
+
+	data, err := reader.ReadString('\n')
+	if err != nil {
+		_ = writeLine("535 Authentication failed")
+		return
+	}
+	data = strings.TrimSpace(data)
+	decodedMessage, err := base64.StdEncoding.DecodeString(data)
+	if err != nil {
+		_ = writeLine("535 Authentication failed")
+		return
+	}
+	splits := strings.Split(string(decodedMessage), ",")
+	if len(splits) != 4 {
+		_ = writeLine("535 Authentication failed - expected 4 parts")
+		return
+	}
+	if !s.tlsServer && splits[0] != "n" {
+		_ = writeLine("535 Authentication failed - expected n to be in the first part")
+		return
+	}
+	if s.tlsServer && !strings.HasPrefix(splits[0], "p=") {
+		_ = writeLine("535 Authentication failed - expected p= to be in the first part")
+		return
+	}
+	if splits[2] != "n=username" {
+		_ = writeLine("535 Authentication failed - expected n=username to be in the third part")
+		return
+	}
+	if !strings.HasPrefix(splits[3], "r=") {
+		_ = writeLine("535 Authentication failed - expected r= to be in the fourth part")
+		return
+	}
+	authMsg = splits[2] + "," + splits[3]
+
+	clientNonce := s.extractNonce(string(decodedMessage))
+	if clientNonce == "" {
+		_ = writeLine("535 Authentication failed")
+		return
+	}
+
+	s.nonce = clientNonce + "server_nonce"
+	serverFirstMessage := fmt.Sprintf("r=%s,s=%s,i=4096", s.nonce,
+		base64.StdEncoding.EncodeToString([]byte("salt")))
+	_ = writeLine(fmt.Sprintf("334 %s", base64.StdEncoding.EncodeToString([]byte(serverFirstMessage))))
+	authMsg = authMsg + "," + serverFirstMessage
+
+	data, err = reader.ReadString('\n')
+	if err != nil {
+		_ = writeLine("535 Authentication failed")
+		return
+	}
+	data = strings.TrimSpace(data)
+	decodedFinalMessage, err := base64.StdEncoding.DecodeString(data)
+	if err != nil {
+		_ = writeLine("535 Authentication failed")
+		return
+	}
+	splits = strings.Split(string(decodedFinalMessage), ",")
+
+	if !s.tlsServer && splits[0] != "c=biws" {
+		_ = writeLine("535 Authentication failed - expected c=biws to be in the first part")
+		return
+	}
+	if s.tlsServer {
+		if !strings.HasPrefix(splits[0], "c=") {
+			_ = writeLine("535 Authentication failed - expected c= to be in the first part")
+			return
+		}
+		channelBind, err := base64.StdEncoding.DecodeString(splits[0][2:])
+		if err != nil {
+			_ = writeLine("535 Authentication failed - base64 channel bind is not valid - " + err.Error())
+			return
+		}
+		if !strings.HasPrefix(string(channelBind), "p=") {
+			_ = writeLine("535 Authentication failed - expected channel binding to start with p=-")
+			return
+		}
+		cbType := string(channelBind[2:])
+		if !strings.HasPrefix(cbType, "tls-unique") && !strings.HasPrefix(cbType, "tls-exporter") {
+			_ = writeLine("535 Authentication failed - expected channel binding type tls-unique or tls-exporter")
+			return
+		}
+	}
+
+	if !strings.HasPrefix(splits[1], "r=") {
+		_ = writeLine("535 Authentication failed - expected r to be in the second part")
+		return
+	}
+	if !strings.Contains(splits[1], "server_nonce") {
+		_ = writeLine("535 Authentication failed - expected server_nonce to be in the second part")
+		return
+	}
+	if !strings.HasPrefix(splits[2], "p=") {
+		_ = writeLine("535 Authentication failed - expected p to be in the third part")
+		return
+	}
+
+	authMsg = authMsg + "," + splits[0] + "," + splits[1]
+	saltedPwd := pbkdf2.Key([]byte("password"), []byte("salt"), 4096, s.h().Size(), s.h)
+	mac := hmac.New(s.h, saltedPwd)
+	mac.Write([]byte("Server Key"))
+	skey := mac.Sum(nil)
+	mac.Reset()
+
+	mac = hmac.New(s.h, skey)
+	mac.Write([]byte(authMsg))
+	ssig := mac.Sum(nil)
+	mac.Reset()
+
+	serverFinalMessage := fmt.Sprintf("v=%s", base64.StdEncoding.EncodeToString(ssig))
+	_ = writeLine(fmt.Sprintf("334 %s", base64.StdEncoding.EncodeToString([]byte(serverFinalMessage))))
+
+	_, err = reader.ReadString('\n')
+	if err != nil {
+		_ = writeLine("535 Authentication failed")
+		return
+	}
+
+	_ = writeLine("235 Authentication successful")
+}
+
+func (s *testSCRAMSMTPServer) extractNonce(message string) string {
+	parts := strings.Split(message, ",")
+	for _, part := range parts {
+		if strings.HasPrefix(part, "r=") {
+			return part[2:]
+		}
+	}
+	return ""
+}
+
+func startSMTPServer(tlsServer bool, hostname, port string, h func() hash.Hash) {
+	server := &testSCRAMSMTPServer{
+		hostname:  hostname,
+		port:      port,
+		tlsServer: tlsServer,
+		h:         h,
+	}
+	listener, err := net.Listen("tcp", fmt.Sprintf("%s:%s", hostname, port))
+	if err != nil {
+		fmt.Printf("Failed to start SMTP server: %v", err)
+	}
+	defer func() {
+		_ = listener.Close()
+	}()
+
+	cert, err := tls.X509KeyPair(localhostCert, localhostKey)
+	if err != nil {
+		fmt.Printf("error creating TLS cert: %s", err)
+		return
+	}
+	tlsConfig := tls.Config{Certificates: []tls.Certificate{cert}}
+
+	for {
+		conn, err := listener.Accept()
+		if err != nil {
+			fmt.Printf("Failed to accept connection: %v", err)
+			continue
+		}
+		if server.tlsServer {
+			conn = tls.Server(conn, &tlsConfig)
+		}
+		go server.handleConnection(conn)
+	}
+}
+
 
 */
 
 // faker is a struct embedding io.ReadWriter to simulate network connections for testing purposes.
 type faker struct {
 	io.ReadWriter
-	failOnRead  bool
-	failOnClose bool
 }
 
-func (f faker) Close() error {
+func (f faker) Close() error                     { return nil }
-	if f.failOnClose {
-		return fmt.Errorf("faker: failed to close connection")
-	}
-	return nil
-}
 func (f faker) LocalAddr() net.Addr              { return nil }
 func (f faker) RemoteAddr() net.Addr             { return nil }
 func (f faker) SetDeadline(time.Time) error      { return nil }
@@ -3249,8 +3486,6 @@ type serverProps struct {
 	FailOnAuth      bool
 	FailOnDataInit  bool
 	FailOnDataClose bool
-	FailOnDial      bool
-	FailOnEhlo      bool
 	FailOnHelo      bool
 	FailOnMailFrom  bool
 	FailOnNoop      bool
@@ -3347,10 +3582,6 @@ func handleTestServerConnection(connection net.Conn, t *testing.T, props *server
 	}
 
 	if !props.IsTLS {
-		if props.FailOnDial {
-			writeLine("421 4.4.1 Service not available")
-			return
-		}
 		writeLine("220 go-mail test server ready ESMTP")
 	}
 
@@ -3364,23 +3595,13 @@ func handleTestServerConnection(connection net.Conn, t *testing.T, props *server
 		var datastring string
 		data = strings.TrimSpace(data)
 		switch {
-		case strings.HasPrefix(data, "HELO"):
+		case strings.HasPrefix(data, "EHLO"), strings.HasPrefix(data, "HELO"):
-			if len(strings.Split(data, " ")) != 2 {
-				writeLine("501 Syntax: HELO hostname")
-				break
-			}
-			if props.FailOnHelo {
-				writeLine("500 5.5.2 Error: fail on HELO")
-				break
-			}
-			writeLine("250-localhost.localdomain\r\n" + props.FeatureSet)
-		case strings.HasPrefix(data, "EHLO"):
 			if len(strings.Split(data, " ")) != 2 {
 				writeLine("501 Syntax: EHLO hostname")
 				break
 			}
-			if props.FailOnEhlo {
+			if props.FailOnHelo {
-				writeLine("500 5.5.2 Error: fail on EHLO")
+				writeLine("500 5.5.2 Error: fail on HELO")
 				break
 			}
 			writeLine("250-localhost.localdomain\r\n" + props.FeatureSet)
@@ -3665,24 +3886,3 @@ type randReader struct{}
 func (r *randReader) Read([]byte) (int, error) {
 	return 0, errors.New("broken reader")
 }
-
-// toServerEmptyAuth is an implementation of Auth that only implements
-// the Start method, and returns "FOOAUTH", nil, nil. Notably, it returns
-// zero bytes for "toServer" so we can test that we don't send spaces at
-// the end of the line. See TestClientAuthTrimSpace.
-type toServerEmptyAuth struct{}
-
-func (toServerEmptyAuth) Start(_ *ServerInfo) (proto string, toServer []byte, err error) {
-	return "FOOAUTH", nil, nil
-}
-
-func (toServerEmptyAuth) Next(_ []byte, _ bool) (toServer []byte, err error) {
-	return nil, fmt.Errorf("unexpected call")
-}
-
-// failWriter is a struct type that implements the io.Writer interface, but always returns an error on Write.
-type failWriter struct{}
-
-func (w *failWriter) Write([]byte) (int, error) {
-	return 0, errors.New("broken writer")
-}