Add extensive client tests for Mail, Verify, and Auth commands

Introduce new tests for the SMTP client covering scenarios for Mail, Verify, and Auth commands to ensure correct behavior under various conditions. Updated `simpleSMTPServer` implementation to handle more cases including VRFY and SMTPUTF8.

smtp/smtp_test.go

@@ -1867,44 +1867,408 @@ func TestClient_TLSConnectionState(t *testing.T) {
 	})
 }
 
-// Issue 17794: don't send a trailing space on AUTH command when there's no password.
+func TestClient_Verify(t *testing.T) {
-func TestClient_Auth_trimSpace(t *testing.T) {
+	t.Run("Verify on existing user succeeds", func(t *testing.T) {
-	server := "220 hello world\r\n" +
+		ctx, cancel := context.WithCancel(context.Background())
-		"200 some more"
+		defer cancel()
-	var wrote strings.Builder
+		PortAdder.Add(1)
-	var fake faker
+		serverPort := int(TestServerPortBase + PortAdder.Load())
-	fake.ReadWriter = struct {
+		featureSet := "250-STARTTLS\r\n250-8BITMIME\r\n250-DSN\r\n250 SMTPUTF8"
-		io.Reader
+		go func() {
-		io.Writer
+			if err := simpleSMTPServer(ctx, t, &serverProps{
-	}{
+				FeatureSet: featureSet,
-		strings.NewReader(server),
+				ListenPort: serverPort,
-		&wrote,
+			},
-	}
+			); err != nil {
-	c, err := NewClient(fake, "fake.host")
+				t.Errorf("failed to start test server: %s", err)
-	if err != nil {
+				return
-		t.Fatalf("NewClient: %v", err)
+			}
-	}
+		}()
-	c.tls = true
+		time.Sleep(time.Millisecond * 30)
-	c.didHello = true
+
-	_ = c.Auth(toServerEmptyAuth{})
+		client, err := Dial(fmt.Sprintf("%s:%d", TestServerAddr, serverPort))
-	if err = c.Close(); err != nil {
+		if err != nil {
-		t.Errorf("close failed: %s", err)
+			t.Errorf("failed to dial to test server: %s", err)
-	}
+		}
-	if got, want := wrote.String(), "AUTH FOOAUTH\r\n*\r\nQUIT\r\n"; got != want {
+		t.Cleanup(func() {
-		t.Errorf("wrote %q; want %q", got, want)
+			if err = client.Close(); err != nil {
-	}
+				t.Errorf("failed to close client: %s", err)
+			}
+		})
+		if err = client.Verify("toni.tester@example.com"); err != nil {
+			t.Errorf("failed to verify user: %s", err)
+		}
+	})
+	t.Run("Verify on non-existing user fails", func(t *testing.T) {
+		ctx, cancel := context.WithCancel(context.Background())
+		defer cancel()
+		PortAdder.Add(1)
+		serverPort := int(TestServerPortBase + PortAdder.Load())
+		featureSet := "250-STARTTLS\r\n250-8BITMIME\r\n250-DSN\r\n250 SMTPUTF8"
+		go func() {
+			if err := simpleSMTPServer(ctx, t, &serverProps{
+				FeatureSet:      featureSet,
+				ListenPort:      serverPort,
+				VRFYUserUnknown: true,
+			},
+			); 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.Cleanup(func() {
+			if err = client.Close(); err != nil {
+				t.Errorf("failed to close client: %s", err)
+			}
+		})
+		if err = client.Verify("toni.tester@example.com"); err == nil {
+			t.Error("verify on non-existing user should fail")
+		}
+	})
+	t.Run("Verify with newlines should fails", func(t *testing.T) {
+		ctx, cancel := context.WithCancel(context.Background())
+		defer cancel()
+		PortAdder.Add(1)
+		serverPort := int(TestServerPortBase + PortAdder.Load())
+		featureSet := "250-STARTTLS\r\n250-8BITMIME\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.Cleanup(func() {
+			if err = client.Close(); err != nil {
+				t.Errorf("failed to close client: %s", err)
+			}
+		})
+		if err = client.Verify("toni.tester@example.com\r\n"); err == nil {
+			t.Error("verify with new lines should fail")
+		}
+	})
+	t.Run("Verify should fail on HELO/EHLO", func(t *testing.T) {
+		ctx, cancel := context.WithCancel(context.Background())
+		defer cancel()
+		PortAdder.Add(1)
+		serverPort := int(TestServerPortBase + PortAdder.Load())
+		featureSet := "250-STARTTLS\r\n250-8BITMIME\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.Cleanup(func() {
+			if err = client.Close(); err != nil {
+				t.Errorf("failed to close client: %s", err)
+			}
+		})
+		if err = client.Verify("toni.tester@example.com"); err == nil {
+			t.Error("verify with new lines should fail")
+		}
+	})
+}
+
+func TestClient_Auth(t *testing.T) {
+	t.Run("Auth fails on EHLO/HELO", func(t *testing.T) {
+		ctx, cancel := context.WithCancel(context.Background())
+		defer cancel()
+		PortAdder.Add(1)
+		serverPort := int(TestServerPortBase + PortAdder.Load())
+		featureSet := "250-STARTTLS\r\n250-8BITMIME\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)
+		}
+		auth := LoginAuth("username", "password", TestServerAddr, false)
+		if err = client.Auth(auth); err == nil {
+			t.Error("auth should fail on EHLO/HELO")
+		}
+	})
+	t.Run("Auth fails on auth-start", func(t *testing.T) {
+		ctx, cancel := context.WithCancel(context.Background())
+		defer cancel()
+		PortAdder.Add(1)
+		serverPort := int(TestServerPortBase + PortAdder.Load())
+		featureSet := "250-STARTTLS\r\n250-8BITMIME\r\n250-DSN\r\n250 SMTPUTF8"
+		go func() {
+			if err := simpleSMTPServer(ctx, t, &serverProps{
+				FailOnAuth: 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)
+		}
+		auth := LoginAuth("username", "password", "not.localhost.com", false)
+		if err = client.Auth(auth); err == nil {
+			t.Error("auth should fail on auth-start, then on quit")
+		}
+		expErr := "wrong host name"
+		if !strings.EqualFold(expErr, err.Error()) {
+			t.Errorf("expected error: %q, got: %q", expErr, err.Error())
+		}
+	})
+	t.Run("Auth fails on auth-start and then on quit", func(t *testing.T) {
+		ctx, cancel := context.WithCancel(context.Background())
+		defer cancel()
+		PortAdder.Add(1)
+		serverPort := int(TestServerPortBase + PortAdder.Load())
+		featureSet := "250-STARTTLS\r\n250-8BITMIME\r\n250-DSN\r\n250 SMTPUTF8"
+		go func() {
+			if err := simpleSMTPServer(ctx, t, &serverProps{
+				FailOnAuth: true,
+				FailOnQuit: 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)
+		}
+		auth := LoginAuth("username", "password", "not.localhost.com", false)
+		if err = client.Auth(auth); err == nil {
+			t.Error("auth should fail on auth-start, then on quit")
+		}
+		expErr := "wrong host name, 500 5.1.2 Error: quit failed"
+		if !strings.EqualFold(expErr, err.Error()) {
+			t.Errorf("expected error: %q, got: %q", expErr, err.Error())
+		}
+	})
+	// Issue 17794: don't send a trailing space on AUTH command when there's no password.
+	t.Run("No trailing space on AUTH when there is no password (Issue 17794)", func(t *testing.T) {
+		server := "220 hello world\r\n" +
+			"200 some more"
+		var wrote strings.Builder
+		var fake faker
+		fake.ReadWriter = struct {
+			io.Reader
+			io.Writer
+		}{
+			strings.NewReader(server),
+			&wrote,
+		}
+		c, err := NewClient(fake, "fake.host")
+		if err != nil {
+			t.Fatalf("NewClient: %v", err)
+		}
+		c.tls = true
+		c.didHello = true
+		_ = c.Auth(toServerEmptyAuth{})
+		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 {
+			t.Errorf("wrote %q; want %q", got, want)
+		}
+	})
+}
+
+func TestClient_Mail(t *testing.T) {
+	t.Run("normal from address succeeds", func(t *testing.T) {
+		ctx, cancel := context.WithCancel(context.Background())
+		defer cancel()
+		PortAdder.Add(1)
+		serverPort := int(TestServerPortBase + PortAdder.Load())
+		featureSet := "250 STARTTLS"
+		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.Mail("valid-from@domain.tld"); err != nil {
+			t.Errorf("failed to set mail from address: %s", err)
+		}
+	})
+	t.Run("from address with new lines fails", func(t *testing.T) {
+		ctx, cancel := context.WithCancel(context.Background())
+		defer cancel()
+		PortAdder.Add(1)
+		serverPort := int(TestServerPortBase + PortAdder.Load())
+		featureSet := "250 STARTTLS"
+		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.Mail("valid-from@domain.tld\r\n"); err == nil {
+			t.Error("mail from address with new lines should fail")
+		}
+	})
+	t.Run("from address fails on EHLO/HELO", func(t *testing.T) {
+		ctx, cancel := context.WithCancel(context.Background())
+		defer cancel()
+		PortAdder.Add(1)
+		serverPort := int(TestServerPortBase + PortAdder.Load())
+		featureSet := "250 STARTTLS"
+		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)
+		}
+		if err = client.Mail("valid-from@domain.tld"); err == nil {
+			t.Error("mail from address should fail on EHLO/HELO")
+		}
+	})
+	t.Run("from address and server supports 8BITMIME", 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 STARTTLS"
+		go func() {
+			if err := simpleSMTPServer(ctx, t, &serverProps{
+				EchoCommandAsError: "MAIL FROM:",
+				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.Mail("valid-from@domain.tld"); err == nil {
+			t.Error("server should echo the command as error but didn't")
+		}
+		sent := strings.Replace(err.Error(), "500 ", "", -1)
+		expected := "MAIL FROM:<valid-from@domain.tld> BODY=8BITMIME"
+		if !strings.EqualFold(sent, expected) {
+			t.Errorf("expected mail from command to be %q, but sent %q", expected, sent)
+		}
+	})
+	t.Run("from address and server supports SMTPUTF8", func(t *testing.T) {
+		ctx, cancel := context.WithCancel(context.Background())
+		defer cancel()
+		PortAdder.Add(1)
+		serverPort := int(TestServerPortBase + PortAdder.Load())
+		featureSet := "250-SMTPUTF8\r\n250 STARTTLS"
+		go func() {
+			if err := simpleSMTPServer(ctx, t, &serverProps{
+				EchoCommandAsError: "MAIL FROM:",
+				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.Mail("valid-from@domain.tld"); err == nil {
+			t.Error("server should echo the command as error but didn't")
+		}
+		sent := strings.Replace(err.Error(), "500 ", "", -1)
+		expected := "MAIL FROM:<valid-from@domain.tld> SMTPUTF8"
+		if !strings.EqualFold(sent, expected) {
+			t.Errorf("expected mail from command to be %q, but sent %q", expected, sent)
+		}
+	})
 }
 
 /*
-
-
-
-
-
-
-
-
-
 func TestBasic(t *testing.T) {
 	server := strings.Join(strings.Split(basicServer, "\n"), "\r\n")
 	client := strings.Join(strings.Split(basicClient, "\n"), "\r\n")
@@ -3422,26 +3786,28 @@ func testingKey(s string) string { return strings.ReplaceAll(s, "TESTING KEY", "
 
 // serverProps represents the configuration properties for the SMTP server.
 type serverProps struct {
-	FailOnAuth      bool
+	EchoCommandAsError string
-	FailOnDataInit  bool
+	FailOnAuth         bool
-	FailOnDataClose bool
+	FailOnDataInit     bool
-	FailOnDial      bool
+	FailOnDataClose    bool
-	FailOnEhlo      bool
+	FailOnDial         bool
-	FailOnHelo      bool
+	FailOnEhlo         bool
-	FailOnMailFrom  bool
+	FailOnHelo         bool
-	FailOnNoop      bool
+	FailOnMailFrom     bool
-	FailOnQuit      bool
+	FailOnNoop         bool
-	FailOnReset     bool
+	FailOnQuit         bool
-	FailOnSTARTTLS  bool
+	FailOnReset        bool
-	FailTemp        bool
+	FailOnSTARTTLS     bool
-	FeatureSet      string
+	FailTemp           bool
-	ListenPort      int
+	FeatureSet         string
-	SSLListener     bool
+	ListenPort         int
-	IsSCRAMPlus     bool
+	HashFunc           func() hash.Hash
-	IsTLS           bool
+	IsSCRAMPlus        bool
-	SupportDSN      bool
+	IsTLS              bool
-	TestSCRAM       bool
+	SupportDSN         bool
-	HashFunc        func() hash.Hash
+	SSLListener        bool
+	TestSCRAM          bool
+	VRFYUserUnknown    bool
 }
 
 // simpleSMTPServer starts a simple TCP server that resonds to SMTP commands.
@@ -3540,6 +3906,9 @@ func handleTestServerConnection(connection net.Conn, t *testing.T, props *server
 		var datastring string
 		data = strings.TrimSpace(data)
 		switch {
+		case props.EchoCommandAsError != "" && strings.HasPrefix(data, props.EchoCommandAsError):
+			writeLine("500 " + data)
+			break
 		case strings.HasPrefix(data, "HELO"):
 			if len(strings.Split(data, " ")) != 2 {
 				writeLine("501 Syntax: HELO hostname")
@@ -3643,8 +4012,17 @@ func handleTestServerConnection(connection net.Conn, t *testing.T, props *server
 				break
 			}
 			writeOK()
-		case strings.EqualFold(data, "vrfy"):
+		case strings.HasPrefix(data, "VRFY"):
-			writeOK()
+			if props.VRFYUserUnknown {
+				writeLine("550 5.1.1 User unknown")
+				break
+			}
+			parts := strings.SplitN(data, " ", 2)
+			if len(parts) != 2 {
+				writeLine("500 5.0.0 Error: invalid syntax for VRFY")
+				break
+			}
+			writeLine(fmt.Sprintf("250 2.0.0 Ok: %s OK", parts[1]))
 		case strings.EqualFold(data, "rset"):
 			if props.FailOnReset {
 				writeLine("500 5.1.2 Error: reset failed")
@@ -3674,7 +4052,7 @@ func handleTestServerConnection(connection net.Conn, t *testing.T, props *server
 			props.IsTLS = true
 			handleTestServerConnection(connection, t, props)
 		default:
-			writeLine("500 5.5.2 Error: bad syntax")
+			writeLine("500 5.5.2 Error: bad syntax - " + data)
 		}
 	}
 }