Add headers to SMTP client to prevent being tagged as spam (#970)

changelog/unreleased/smtp-headers.md

@@ -0,0 +1,6 @@
+Enhancement: Add required headers to SMTP client to prevent being tagged as spam
+
+Mails being sent through the client, specially through unauthenticated SMTP were
+being tagged as spam due to missing headers.
+
+https://github.com/cs3org/reva/pull/970

docs/content/en/docs/config/packages/smtpclient/_index.md

@@ -0,0 +1,58 @@
+---
+title: "smtpclient"
+linkTitle: "smtpclient"
+weight: 10
+description: >
+  Configuration for the smtpclient service
+---
+
+# _struct: SMTPCredentials_
+
+{{% dir name="sender_mail" type="string" default="" %}}
+The email to be used to send mails. [[Ref]](https://github.com/cs3org/reva/tree/master/pkg/smtpclient/smtpclient.go#L36)
+{{< highlight toml >}}
+[smtpclient]
+sender_mail = ""
+{{< /highlight >}}
+{{% /dir %}}
+
+{{% dir name="sender_password" type="string" default="" %}}
+The sender's password. [[Ref]](https://github.com/cs3org/reva/tree/master/pkg/smtpclient/smtpclient.go#L37)
+{{< highlight toml >}}
+[smtpclient]
+sender_password = ""
+{{< /highlight >}}
+{{% /dir %}}
+
+{{% dir name="smtp_server" type="string" default="" %}}
+The hostname of the SMTP server. [[Ref]](https://github.com/cs3org/reva/tree/master/pkg/smtpclient/smtpclient.go#L38)
+{{< highlight toml >}}
+[smtpclient]
+smtp_server = ""
+{{< /highlight >}}
+{{% /dir %}}
+
+{{% dir name="smtp_port" type="int" default=587 %}}
+The port on which the SMTP daemon is running. [[Ref]](https://github.com/cs3org/reva/tree/master/pkg/smtpclient/smtpclient.go#L39)
+{{< highlight toml >}}
+[smtpclient]
+smtp_port = 587
+{{< /highlight >}}
+{{% /dir %}}
+
+{{% dir name="disable_auth" type="bool" default=false %}}
+Whether to disable SMTP auth. [[Ref]](https://github.com/cs3org/reva/tree/master/pkg/smtpclient/smtpclient.go#L40)
+{{< highlight toml >}}
+[smtpclient]
+disable_auth = false
+{{< /highlight >}}
+{{% /dir %}}
+
+{{% dir name="local_name" type="string" default="" %}}
+The host name to be used for unauthenticated SMTP. [[Ref]](https://github.com/cs3org/reva/tree/master/pkg/smtpclient/smtpclient.go#L41)
+{{< highlight toml >}}
+[smtpclient]
+local_name = ""
+{{< /highlight >}}
+{{% /dir %}}
+

internal/http/services/ocmd/invites.go

@@ -23,7 +23,6 @@ import (
 	"errors"
 	"fmt"
 	"net/http"
-	"os"
 
 	userpb "github.com/cs3org/go-cs3apis/cs3/identity/user/v1beta1"
 	invitepb "github.com/cs3org/go-cs3apis/cs3/ocm/invite/v1beta1"
@@ -44,10 +43,7 @@ type invitesHandler struct {
 
 func (h *invitesHandler) init(c *Config) {
 	h.gatewayAddr = c.GatewaySvc
-	h.smtpCredentials = c.SMTPCredentials
-	if h.smtpCredentials != nil && !h.smtpCredentials.DisableAuth && h.smtpCredentials.SenderPassword == "" {
-		h.smtpCredentials.SenderPassword = os.Getenv("REVA_OCMD_SMTP_SENDER_PASSWORD")
-	}
+	h.smtpCredentials = smtpclient.NewSMTPCredentials(c.SMTPCredentials)
 }
 
 func (h *invitesHandler) Handler() http.Handler {

pkg/smtpclient/smtpclient.go

@@ -20,38 +20,74 @@ package smtpclient
 
 import (
 	"bytes"
+	"encoding/base64"
 	"fmt"
 	"net/smtp"
+	"os"
+	"strings"
+	"time"
 
+	"github.com/google/uuid"
 	"github.com/pkg/errors"
 )
 
 // SMTPCredentials stores the credentials required to connect to an SMTP server.
 type SMTPCredentials struct {
-	SenderMail     string `mapstructure:"sender_mail"`
-	SenderPassword string `mapstructure:"sender_password"`
-	SMTPServer     string `mapstructure:"smtp_server"`
-	SMTPPort       int    `mapstructure:"smtp_port"`
-	DisableAuth    bool   `mapstructure:"disable_auth"`
+	SenderMail     string `mapstructure:"sender_mail" docs:";The email to be used to send mails."`
+	SenderPassword string `mapstructure:"sender_password" docs:";The sender's password."`
+	SMTPServer     string `mapstructure:"smtp_server" docs:";The hostname of the SMTP server."`
+	SMTPPort       int    `mapstructure:"smtp_port" docs:"587;The port on which the SMTP daemon is running."`
+	DisableAuth    bool   `mapstructure:"disable_auth" docs:"false;Whether to disable SMTP auth."`
+	LocalName      string `mapstructure:"local_name" docs:";The host name to be used for unauthenticated SMTP."`
+}
+
+// NewSMTPCredentials creates a new SMTPCredentials object with the details of the passed object with sane defaults.
+func NewSMTPCredentials(c *SMTPCredentials) *SMTPCredentials {
+	creds := c
+
+	if creds.SMTPPort == 0 {
+		creds.SMTPPort = 587
+	}
+	if !creds.DisableAuth && creds.SenderPassword == "" {
+		creds.SenderPassword = os.Getenv("REVA_SMTP_SENDER_PASSWORD")
+	}
+	if creds.LocalName == "" {
+		tokens := strings.Split(creds.SenderMail, "@")
+		creds.LocalName = tokens[len(tokens)-1]
+	}
+	return creds
 }
 
 // SendMail allows sending mails using a set of client credentials.
 func (creds *SMTPCredentials) SendMail(recipient, subject, body string) error {
+
+	headers := map[string]string{
+		"From":                      creds.SenderMail,
+		"To":                        recipient,
+		"Subject":                   subject,
+		"Date":                      time.Now().Format(time.RFC1123Z),
+		"Message-ID":                uuid.New().String(),
+		"MIME-Version":              "1.0",
+		"Content-Type":              "text/plain; charset=\"utf-8\"",
+		"Content-Transfer-Encoding": "base64",
+	}
+
+	message := ""
+	for k, v := range headers {
+		message += fmt.Sprintf("%s: %s\r\n", k, v)
+	}
+	message += "\r\n" + base64.StdEncoding.EncodeToString([]byte(body))
+
 	if creds.DisableAuth {
-		return creds.sendMailSMTP(recipient, subject, body)
+		return creds.sendMailSMTP(recipient, subject, message)
 	}
-	return creds.sendMailAuthSMTP(recipient, subject, body)
+	return creds.sendMailAuthSMTP(recipient, subject, message)
 }
 
-func (creds *SMTPCredentials) sendMailAuthSMTP(recipient, subject, body string) error {
+func (creds *SMTPCredentials) sendMailAuthSMTP(recipient, subject, message string) error {
 
 	auth := smtp.PlainAuth("", creds.SenderMail, creds.SenderPassword, creds.SMTPServer)
 
-	message := "From: " + creds.SenderMail + "\n" +
-		"To: " + recipient + "\n" +
-		"Subject: " + subject + "\n\n" +
-		body
-
 	err := smtp.SendMail(
 		fmt.Sprintf("%s:%d", creds.SMTPServer, creds.SMTPPort),
 		auth,
@@ -67,14 +103,17 @@ func (creds *SMTPCredentials) sendMailAuthSMTP(recipient, subject, body string)
 	return nil
 }
 
-func (creds *SMTPCredentials) sendMailSMTP(recipient, subject, body string) error {
+func (creds *SMTPCredentials) sendMailSMTP(recipient, subject, message string) error {
 
 	c, err := smtp.Dial(fmt.Sprintf("%s:%d", creds.SMTPServer, creds.SMTPPort))
 	if err != nil {
 		return err
 	}
 	defer c.Close()
 
+	if err = c.Hello(creds.LocalName); err != nil {
+		return err
+	}
 	if err = c.Mail(creds.SenderMail); err != nil {
 		return err
 	}
@@ -88,12 +127,7 @@ func (creds *SMTPCredentials) sendMailSMTP(recipient, subject, body string) erro
 	}
 	defer wc.Close()
 
-	message := "From: " + creds.SenderMail + "\n" +
-		"To: " + recipient + "\n" +
-		"Subject: " + subject + "\n\n" +
-		body
 	buf := bytes.NewBufferString(message)
-
 	if _, err = buf.WriteTo(wc); err != nil {
 		return err
 	}