Improve the mock SMTP mechanism a lot

config.go

@@ -178,6 +178,7 @@ type configContact struct {
 	SMTPPassword  string `mapstructure:"smtpPassword"`
 	EmailFrom     string `mapstructure:"emailFrom"`
 	EmailTo       string `mapstructure:"emailTo"`
+	EmailSubject  string `mapstructure:"emailSubject"`
 }
 
 type configAnnouncement struct {

contact.go

@@ -5,9 +5,11 @@ import (
 	"fmt"
 	"log"
 	"net/http"
-	"net/smtp"
 	"strconv"
 	"time"
+
+	"github.com/emersion/go-sasl"
+	"github.com/emersion/go-smtp"
 )
 
 const defaultContactPath = "/contact"
@@ -82,13 +84,18 @@ func (a *goBlog) sendContactEmail(cc *configContact, body, replyTo string) error
 		_, _ = fmt.Fprintf(&email, "Reply-To: %s\n", replyTo)
 	}
 	_, _ = fmt.Fprintf(&email, "Date: %s\n", time.Now().UTC().Format(time.RFC1123Z))
-	_, _ = fmt.Fprintf(&email, "Subject: New message\n\n")
+	_, _ = fmt.Fprintf(&email, "From: %s\n", cc.EmailFrom)
+	subject := cc.EmailSubject
+	if subject == "" {
+		subject = "New contact message"
+	}
+	_, _ = fmt.Fprintf(&email, "Subject: %s\n\n", subject)
 	_, _ = fmt.Fprintf(&email, "%s\n", body)
 	// Send email using SMTP
-	auth := smtp.PlainAuth("", cc.SMTPUser, cc.SMTPPassword, cc.SMTPHost)
+	auth := sasl.NewPlainClient("", cc.SMTPUser, cc.SMTPPassword)
 	port := cc.SMTPPort
 	if port == 0 {
 		port = 587
 	}
-	return smtp.SendMail(cc.SMTPHost+":"+strconv.Itoa(port), auth, cc.EmailFrom, []string{cc.EmailTo}, email.Bytes())
+	return smtp.SendMail(cc.SMTPHost+":"+strconv.Itoa(port), auth, cc.EmailFrom, []string{cc.EmailTo}, bytes.NewReader(email.Bytes()))
 }

contact_test.go

@@ -18,8 +18,9 @@ import (
 func Test_contact(t *testing.T) {
 
 	// Start the SMTP server
-	port, rd, err := mocksmtp.StartMockSMTPServer()
+	port, rd, cancel, err := mocksmtp.StartMockSMTPServer()
 	require.NoError(t, err)
+	defer cancel()
 
 	// Init everything
 	app := &goBlog{
@@ -42,6 +43,7 @@ func Test_contact(t *testing.T) {
 						SMTPPassword: "pass",
 						EmailTo:      "to@example.org",
 						EmailFrom:    "from@example.org",
+						EmailSubject: "Neue Kontaktnachricht",
 					},
 				},
 			},
@@ -65,11 +67,16 @@ func Test_contact(t *testing.T) {
 	require.Equal(t, http.StatusOK, rec.Result().StatusCode)
 
 	// Check sent mail
-	received, err := rd()
-	require.NoError(t, err)
-	assert.Contains(t, received, "This is a test contact message")
-	assert.Contains(t, received, "test@example.net")
-	assert.Contains(t, received, "https://test.example.com")
-	assert.Contains(t, received, "Test User")
+	assert.Contains(t, rd.Usernames, "user")
+	assert.Contains(t, rd.Passwords, "pass")
+	assert.Contains(t, rd.Froms, "from@example.org")
+	assert.Contains(t, rd.Rcpts, "to@example.org")
+	if assert.Len(t, rd.Datas, 1) {
+		assert.Contains(t, string(rd.Datas[0]), "This is a test contact message")
+		assert.Contains(t, string(rd.Datas[0]), "test@example.net")
+		assert.Contains(t, string(rd.Datas[0]), "https://test.example.com")
+		assert.Contains(t, string(rd.Datas[0]), "Test User")
+		assert.Contains(t, string(rd.Datas[0]), "Neue Kontaktnachricht")
+	}
 
 }

example-config.yml

@@ -242,6 +242,7 @@ blogs:
       smtpPassword: secret # SMTP password
       emailFrom: blog@example.com # Email sender
       emailTo: mail@example.com # Email recipient
+      emailSubject: "New contact message" # (Optional) Email subject
     # Announcement
     announcement:
       text: This is an **announcement**! # Can be markdown with links etc.

go.mod

@@ -15,6 +15,8 @@ require (
 	github.com/dgraph-io/ristretto v0.1.0
 	github.com/dmulholl/mp3lib v1.0.0
 	github.com/elnormous/contenttype v1.0.0
+	github.com/emersion/go-sasl v0.0.0-20211008083017-0b9dcfb154ac
+	github.com/emersion/go-smtp v0.15.0
 	github.com/go-chi/chi/v5 v5.0.5
 	github.com/go-fed/httpsig v1.1.0
 	github.com/gorilla/handlers v1.5.1

go.sum

@@ -118,6 +118,11 @@ github.com/dustin/go-humanize v1.0.0/go.mod h1:HtrtbFcZ19U5GC7JDqmcUSB87Iq5E25Kn
 github.com/dvyukov/go-fuzz v0.0.0-20210103155950-6a8e9d1f2415/go.mod h1:11Gm+ccJnvAhCNLlf5+cS9KjtbaD5I5zaZpFMsTHWTw=
 github.com/elnormous/contenttype v1.0.0 h1:cTLou7K7uQMsPEmRiTJosAznsPcYuoBmXMrFAf86t2A=
 github.com/elnormous/contenttype v1.0.0/go.mod h1:ngVcyGGU8pnn4QJ5sL4StrNgc/wmXZXy5IQSBuHOFPg=
+github.com/emersion/go-sasl v0.0.0-20200509203442-7bfe0ed36a21/go.mod h1:iL2twTeMvZnrg54ZoPDNfJaJaqy0xIQFuBdrLsmspwQ=
+github.com/emersion/go-sasl v0.0.0-20211008083017-0b9dcfb154ac h1:tn/OQ2PmwQ0XFVgAHfjlLyqMewry25Rz7jWnVoh4Ggs=
+github.com/emersion/go-sasl v0.0.0-20211008083017-0b9dcfb154ac/go.mod h1:iL2twTeMvZnrg54ZoPDNfJaJaqy0xIQFuBdrLsmspwQ=
+github.com/emersion/go-smtp v0.15.0 h1:3+hMGMGrqP/lqd7qoxZc1hTU8LY8gHV9RFGWlqSDmP8=
+github.com/emersion/go-smtp v0.15.0/go.mod h1:qm27SGYgoIPRot6ubfQ/GpiPy/g3PaZAVRxiO/sDUgQ=
 github.com/envoyproxy/go-control-plane v0.9.0/go.mod h1:YTl/9mNaCwkRvm6d1a2C3ymFceY/DCBVvsKhRF0iEA4=
 github.com/envoyproxy/go-control-plane v0.9.1-0.20191026205805-5f8ba28d4473/go.mod h1:YTl/9mNaCwkRvm6d1a2C3ymFceY/DCBVvsKhRF0iEA4=
 github.com/envoyproxy/go-control-plane v0.9.4/go.mod h1:6rpuAdCZL397s3pYoYcLgu1mIlRU8Am5FuJP05cCM98=

pkgs/mocksmtp/backend.go

@@ -0,0 +1,68 @@
+package mocksmtp
+
+import (
+	"io"
+	"io/ioutil"
+
+	"github.com/emersion/go-smtp"
+)
+
+// ReceivedValues contains all the data received from the SMTP server
+type ReceivedValues struct {
+	Usernames []string
+	Passwords []string
+	Froms     []string
+	Rcpts     []string
+	Datas     [][]byte
+}
+
+type backend struct {
+	values *ReceivedValues
+}
+
+var _ smtp.Backend = &backend{}
+
+func (b *backend) Login(_ *smtp.ConnectionState, username, password string) (smtp.Session, error) {
+	b.values.Usernames = append(b.values.Usernames, username)
+	b.values.Passwords = append(b.values.Passwords, password)
+	return &session{
+		values: b.values,
+	}, nil
+}
+
+func (b *backend) AnonymousLogin(_ *smtp.ConnectionState) (smtp.Session, error) {
+	return &session{
+		values: b.values,
+	}, nil
+}
+
+type session struct {
+	values *ReceivedValues
+}
+
+var _ smtp.Session = &session{}
+
+func (s *session) Mail(from string, _ smtp.MailOptions) error {
+	s.values.Froms = append(s.values.Froms, from)
+	return nil
+}
+
+func (s *session) Rcpt(to string) error {
+	s.values.Rcpts = append(s.values.Rcpts, to)
+	return nil
+}
+
+func (s *session) Data(r io.Reader) error {
+	if b, err := ioutil.ReadAll(r); err != nil {
+		return err
+	} else {
+		s.values.Datas = append(s.values.Datas, b)
+	}
+	return nil
+}
+
+func (s *session) Reset() {}
+
+func (s *session) Logout() error {
+	return nil
+}

pkgs/mocksmtp/mocksmtp.go

@@ -3,116 +3,62 @@
 package mocksmtp
 
 import (
-	"bufio"
-	"bytes"
-	"fmt"
+	"log"
 	"net"
-	"net/textproto"
 	"strconv"
-)
-
-// Inspired by https://play.golang.org/p/8mfrqNVWTPK
-
-type ReceivedGetter func() (string, error)
-
-func StartMockSMTPServer() (port int, rg ReceivedGetter, err error) {
-
-	// Default server responses
-	serverResponses := []string{
-		"220 smtp.example.com Service ready",
-		"250-ELHO -> ok",
-		"250-Show Options for ESMTP",
-		"250-8BITMIME",
-		"250-SIZE",
-		"250-AUTH LOGIN PLAIN",
-		"250 HELP",
-		"235 AUTH -> ok",
-		"250 MAIL FROM -> ok",
-		"250 RCPT TO -> ok",
-		"354 DATA",
-		"250 ... -> ok",
-		"221 QUIT",
-	}
 
-	// Channel to check if error occured or done
-	var errOrDone = make(chan error)
+	"github.com/emersion/go-smtp"
+)
 
-	// Received data buffer
-	var buffer bytes.Buffer
-	bufferWriter := bufio.NewWriter(&buffer)
+// Start a mock SMTP server on a random port
+//
+// Returns:
+// port: the port the server is listening on,
+// receivedValues: struct to read the received values like username, password, data,
+// cancelFunc: function to stop the server,
+// err: something went wrong
+func StartMockSMTPServer() (port int, receivedValues *ReceivedValues, cancelFunc func(), err error) {
 
 	// Start server on random port
 	mockSmtpServer, err := net.Listen("tcp", "127.0.0.1:0")
 	if err != nil {
-		return 0, nil, err
+		return 0, nil, nil, err
 	}
 
 	// Get port from listener
 	_, portStr, err := net.SplitHostPort(mockSmtpServer.Addr().String())
 	if err != nil {
-		return 0, nil, err
+		return 0, nil, nil, err
 	}
 	port, err = strconv.Atoi(portStr)
 	if err != nil {
-		return 0, nil, err
+		return 0, nil, nil, err
 	}
 
-	// Run mock SMTP server
-	go func() {
-		defer close(errOrDone)
-		defer bufferWriter.Flush()
-		defer mockSmtpServer.Close()
-
-		conn, err := mockSmtpServer.Accept()
-		if err != nil {
-			errOrDone <- err
-			return
-		}
-		defer conn.Close()
+	// Define received values
+	receivedValues = &ReceivedValues{}
 
-		tc := textproto.NewConn(conn)
-		defer tc.Close()
+	// Init SMTP server
+	s := smtp.NewServer(&backend{
+		values: receivedValues,
+	})
+	s.Addr = mockSmtpServer.Addr().String()
+	s.Domain = "127.0.0.1"
+	s.AllowInsecureAuth = true
 
-		for _, res := range serverResponses {
-			if res == "" {
-				break
-			}
-
-			_ = tc.PrintfLine("%s", res)
-
-			if len(res) >= 4 && res[3] == '-' {
-				continue
-			}
-
-			if res == "221 QUIT" {
-				return
-			}
-
-			for {
-				msg, err := tc.ReadLine()
-				if err != nil {
-					errOrDone <- err
-					return
-				}
-
-				_, _ = fmt.Fprintf(bufferWriter, "%s\n", msg)
-
-				if res != "354 DATA" || msg == "." {
-					break
-				}
-			}
+	// Start SMTP server
+	go func() {
+		if err := s.Serve(mockSmtpServer); err != nil {
+			log.Fatal(err)
 		}
 	}()
 
-	// Define function to get received data
-	getReceivedData := func() (string, error) {
-		err, hasErr := <-errOrDone
-		if hasErr {
-			return "", err
-		}
-		return buffer.String(), nil
+	// Create cancel function
+	cancelFunc = func() {
+		_ = s.Close()
 	}
 
 	// Return port and function
-	return port, getReceivedData, nil
+	return port, receivedValues, cancelFunc, nil
+
 }

pkgs/mocksmtp/mocksmtp_test.go

@@ -11,22 +11,26 @@ import (
 
 func Test_mocksmtp(t *testing.T) {
 	// Start mock SMTP server
-	port, getRecievedData, err := StartMockSMTPServer()
+	port, rd, cancel, err := StartMockSMTPServer()
 	require.NoError(t, err)
+	defer cancel()
 
 	// Send mail
 	err = smtp.SendMail(
 		fmt.Sprintf("127.0.0.1:%d", port),
 		smtp.PlainAuth("", "user", "pass", "127.0.0.1"),
-		"admin@smtp.example.com",
-		[]string{"user@smtp.example.com"},
-		[]byte("From: admin@smtp.example.com\nTo: user@smtp.example.com\nSubject: Test\nMIME-version: 1.0\nContent-Type: text/html; charset=\"UTF-8\"\n\nThis is a test mail."),
+		"admin@example.com",
+		[]string{"user@example.com"},
+		[]byte("From: admin@example.com\nTo: user@example.com\nSubject: Test\nMIME-version: 1.0\nContent-Type: text/html; charset=\"UTF-8\"\n\nThis is a test mail."),
 	)
 	require.NoError(t, err)
 
 	// Get received data
-	recievedData, err := getRecievedData()
-	require.NoError(t, err)
-	assert.Contains(t, recievedData, "From:")
-	assert.Contains(t, recievedData, "This is a test mail")
+	assert.Contains(t, rd.Froms, "admin@example.com")
+	assert.Contains(t, rd.Rcpts, "user@example.com")
+	assert.Contains(t, rd.Usernames, "user")
+	assert.Contains(t, rd.Passwords, "pass")
+	if assert.Len(t, rd.Froms, 1) {
+		assert.Contains(t, string(rd.Datas[0]), "This is a test mail")
+	}
 }