From 4d1f248a9b263728663218a6f6473a9a03cb6e6a Mon Sep 17 00:00:00 2001
From: Piotr Kozimor <p1996k@gmail.com>
Date: Tue, 10 Aug 2021 10:41:49 +0200
Subject: [PATCH] Define Mailer interface and provide SmtpMailer implementation

---
 userapi/api/api.go        |  12 +++++
 userapi/mail/mail.go      | 102 ++++++++++++++++++++++++++++++++++++++
 userapi/mail/mail_test.go |  38 ++++++++++++++
 3 files changed, 152 insertions(+)
 create mode 100644 userapi/mail/mail.go
 create mode 100644 userapi/mail/mail_test.go

diff --git a/userapi/api/api.go b/userapi/api/api.go
index e976f0139..ee58ac007 100644
--- a/userapi/api/api.go
+++ b/userapi/api/api.go
@@ -22,6 +22,16 @@ import (
 	"github.com/matrix-org/gomatrixserverlib"
 )
 
+const (
+	// Verification is used in
+	// - https://matrix.org/docs/spec/client_server/r0.6.1#post-matrix-client-r0-account-3pid-email-requesttoken
+	// - https://matrix.org/docs/spec/client_server/r0.6.1#post-matrix-client-r0-register-email-requesttoken
+	Verification ThreepidSessionType = iota
+	// Password is used in
+	// - https://matrix.org/docs/spec/client_server/r0.6.1#post-matrix-client-r0-account-password-email-requesttoken
+	Password
+)
+
 // UserInternalAPI is the internal API for information about users and devices.
 type UserInternalAPI interface {
 	InputAccountData(ctx context.Context, req *InputAccountDataRequest, res *InputAccountDataResponse) error
@@ -365,3 +375,5 @@ type IsSessionValidatedResponse struct {
 	Validated   bool
 	ValidatedAt int
 }
+
+type ThreepidSessionType int
diff --git a/userapi/mail/mail.go b/userapi/mail/mail.go
new file mode 100644
index 000000000..33cc84f69
--- /dev/null
+++ b/userapi/mail/mail.go
@@ -0,0 +1,102 @@
+package mail
+
+import (
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"net/smtp"
+	"text/template"
+	"time"
+
+	"github.com/matrix-org/dendrite/internal"
+	"github.com/matrix-org/dendrite/setup/config"
+	"github.com/matrix-org/dendrite/userapi/api"
+)
+
+const (
+	messageIdByteLength = 48
+)
+
+type Mailer interface {
+	// Send is used in
+	// - https://matrix.org/docs/spec/client_server/r0.6.1#post-matrix-client-r0-account-3pid-email-requesttoken
+	// - https://matrix.org/docs/spec/client_server/r0.6.1#post-matrix-client-r0-register-email-requesttoken
+	// - https://matrix.org/docs/spec/client_server/r0.6.1#post-matrix-client-r0-account-password-email-requesttoken
+	Send(*Mail, api.ThreepidSessionType) error
+}
+type SmtpMailer struct {
+	conf      config.EmailConf
+	templates map[api.ThreepidSessionType]*template.Template
+}
+
+type Mail struct {
+	To    string
+	Link  string
+	Token string
+	Extra []string
+}
+
+type Substitutions struct {
+	*Mail
+	Date      string
+	MessageId string
+}
+
+func (m *SmtpMailer) Send(mail *Mail, t api.ThreepidSessionType) error {
+	return m.send(mail, m.templates[t])
+}
+
+func (m *SmtpMailer) send(mail *Mail, t *template.Template) error {
+	messageId, err := internal.GenerateBlob(messageIdByteLength)
+	if err != nil {
+		return err
+	}
+	s := Substitutions{
+		Mail:      mail,
+		Date:      time.Now().Format(time.RFC1123Z),
+		MessageId: messageId,
+	}
+	b := bytes.Buffer{}
+	err = t.Execute(&b, s)
+	if err != nil {
+		return err
+	}
+	return smtp.SendMail(
+		m.conf.Smtp.Host,
+		smtp.PlainAuth(
+			"",
+			m.conf.Smtp.User,
+			m.conf.Smtp.Password,
+			m.conf.Smtp.Host,
+		),
+		m.conf.From,
+		[]string{
+			mail.To,
+		},
+		b.Bytes(),
+	)
+}
+
+func NewMailer(c *config.UserAPI) (Mailer, error) {
+	templateRaw, err := ioutil.ReadFile(fmt.Sprintf("%s/verification.eml", c.Email.TemplatesPath))
+	if err != nil {
+		return nil, err
+	}
+	verificationT, err := template.New("verification").Parse(string(templateRaw))
+	if err != nil {
+		return nil, err
+	}
+	templateRaw, err = ioutil.ReadFile(fmt.Sprintf("%s/password.eml", c.Email.TemplatesPath))
+	if err != nil {
+		return nil, err
+	}
+	passwordT, err := template.New("password").Parse(string(templateRaw))
+	return &SmtpMailer{
+		conf: c.Email,
+		templates: map[api.ThreepidSessionType]*template.Template{
+			api.Password:     passwordT,
+			api.Verification: verificationT,
+		},
+	}, err
+
+}
diff --git a/userapi/mail/mail_test.go b/userapi/mail/mail_test.go
new file mode 100644
index 000000000..7a4d97abf
--- /dev/null
+++ b/userapi/mail/mail_test.go
@@ -0,0 +1,38 @@
+package mail
+
+import (
+	"testing"
+
+	"github.com/matrix-org/dendrite/setup/config"
+	"github.com/matrix-org/dendrite/userapi/api"
+	"github.com/matryer/is"
+)
+
+func TestSendVerification(t *testing.T) {
+	is := is.New(t)
+	dut := mustNewMailer(is)
+	err := dut.Send(
+		&Mail{
+			To:    "kevil11378@186site.com",
+			Link:  "my",
+			Token: "foo",
+			Extra: []string{
+				"bar",
+			},
+		}, api.Verification)
+	is.NoErr(err)
+}
+
+func mustNewMailer(is *is.I) Mailer {
+	mailer, err := NewMailer(&config.UserAPI{
+		Email: config.EmailConf{
+			TemplatesPath: "../../res/default",
+			From:          "test@matrix.com",
+			Smtp: config.Smtp{
+				Host: "localhost:25",
+			},
+		},
+	})
+	is.NoErr(err)
+	return mailer
+}