Support for base64 encoded emails

docs/releases.md

@@ -4,6 +4,10 @@ and the [ntfy Android app](https://github.com/binwiederhier/ntfy-android/release
 
 ## ntfy server v2.0.2 (UNRELEASED)
 
+**Bug fixes + maintenance:**
+
+* Support for base64 encoded emails ([#610](https://github.com/binwiederhier/ntfy/issues/610), thanks to [@Robert-litts](https://github.com/Robert-litts))
+
 **Additional languages:**
 
 * Arabic (thanks to [@ButterflyOfFire](https://hosted.weblate.org/user/ButterflyOfFire/))

server/smtp_server.go

@@ -2,6 +2,7 @@ package server
 
 import (
 	"bytes"
+	"encoding/base64"
 	"errors"
 	"fmt"
 	"github.com/emersion/go-smtp"
@@ -204,28 +205,20 @@ func (s *smtpSession) withFailCount(fn func() error) error {
 
 func readMailBody(msg *mail.Message) (string, error) {
 	if msg.Header.Get("Content-Type") == "" {
-		return readPlainTextMailBody(msg)
+		return readPlainTextMailBody(msg.Body, msg.Header.Get("Content-Transfer-Encoding"))
 	}
 	contentType, params, err := mime.ParseMediaType(msg.Header.Get("Content-Type"))
 	if err != nil {
 		return "", err
 	}
-	if contentType == "text/plain" {
+	if strings.ToLower(contentType) == "text/plain" {
-		return readPlainTextMailBody(msg)
+		return readPlainTextMailBody(msg.Body, msg.Header.Get("Content-Transfer-Encoding"))
-	} else if strings.HasPrefix(contentType, "multipart/") {
+	} else if strings.HasPrefix(strings.ToLower(contentType), "multipart/") {
 		return readMultipartMailBody(msg, params)
 	}
 	return "", errUnsupportedContentType
 }
 
-func readPlainTextMailBody(msg *mail.Message) (string, error) {
-	body, err := io.ReadAll(msg.Body)
-	if err != nil {
-		return "", err
-	}
-	return string(body), nil
-}
-
 func readMultipartMailBody(msg *mail.Message, params map[string]string) (string, error) {
 	mr := multipart.NewReader(msg.Body, params["boundary"])
 	for {
@@ -236,14 +229,20 @@ func readMultipartMailBody(msg *mail.Message, params map[string]string) (string,
 		partContentType, _, err := mime.ParseMediaType(part.Header.Get("Content-Type"))
 		if err != nil {
 			return "", err
-		}
+		} else if strings.ToLower(partContentType) != "text/plain" {
-		if partContentType != "text/plain" {
 			continue
 		}
-		body, err := io.ReadAll(part)
+		return readPlainTextMailBody(part, part.Header.Get("Content-Transfer-Encoding"))
-		if err != nil {
-			return "", err
-		}
-		return string(body), nil
 	}
 }
+
+func readPlainTextMailBody(reader io.Reader, transferEncoding string) (string, error) {
+	if strings.ToLower(transferEncoding) == "base64" {
+		reader = base64.NewDecoder(base64.StdEncoding, reader)
+	}
+	body, err := io.ReadAll(reader)
+	if err != nil {
+		return "", err
+	}
+	return string(body), nil
+}

server/smtp_server_test.go

@@ -348,6 +348,97 @@ what's up
 	writeAndReadUntilLine(t, email, c, scanner, "451 4.0.0 invalid address")
 }
 
+func TestSmtpBackend_Base64Body(t *testing.T) {
+	email := `EHLO example.com
+MAIL FROM: test@mydomain.me
+RCPT TO: ntfy-mytopic@ntfy.sh
+DATA
+Content-Type: multipart/mixed; boundary="===============2138658284696597373=="
+MIME-Version: 1.0
+Subject: TrueNAS truenas.local: TrueNAS Test Message hostname: truenas.local
+From: =?utf-8?q?Robbie?= <test@mydomain.me>
+To: test@mydomain.me
+Date: Thu, 16 Feb 2023 01:04:00 -0000
+Message-ID: <truenas-20230216.010400.344514.b'8jfL'@truenas.local>
+
+This is a multi-part message in MIME format.
+--===============2138658284696597373==
+Content-Type: text/plain; charset="utf-8"
+MIME-Version: 1.0
+Content-Transfer-Encoding: base64
+
+VGhpcyBpcyBhIHRlc3QgbWVzc2FnZSBmcm9tIFRydWVOQVMgQ09SRS4=
+
+--===============2138658284696597373==
+Content-Type: text/html; charset="utf-8"
+MIME-Version: 1.0
+Content-Transfer-Encoding: base64
+
+PCFET0NUWVBFIEhUTUwgUFVCTElDICItLy9XM0MvL0RURCBIVE1MIDQuMCBUcmFuc2l0aW9uYWwv
+L0VOIj4KClRoaXMgaXMgYSB0ZXN0IG1lc3NhZ2UgZnJvbSBUcnVlTkFTIENPUkUuCg==
+
+--===============2138658284696597373==--
+.
+`
+	s, c, _, scanner := newTestSMTPServer(t, func(w http.ResponseWriter, r *http.Request) {
+		require.Equal(t, "/mytopic", r.URL.Path)
+		require.Equal(t, "TrueNAS truenas.local: TrueNAS Test Message hostname: truenas.local", r.Header.Get("Title"))
+		require.Equal(t, "This is a test message from TrueNAS CORE.", readAll(t, r.Body))
+	})
+	defer s.Close()
+	defer c.Close()
+	writeAndReadUntilLine(t, email, c, scanner, "250 2.0.0 OK: queued")
+}
+
+/*
+	func TestSmtpBackend_NestedMultipartBase64(t *testing.T) {
+		email := `EHLO example.com
+
+MAIL FROM: test@mydomain.me
+RCPT TO: ntfy-mytopic@ntfy.sh
+DATA
+Content-Type: multipart/mixed; boundary="===============2138658284696597373=="
+MIME-Version: 1.0
+Subject: TrueNAS truenas.local: TrueNAS Test Message hostname: truenas.local
+From: =?utf-8?q?Robbie?= <test@mydomain.me>
+To: test@mydomain.me
+Date: Thu, 16 Feb 2023 01:04:00 -0000
+Message-ID: <truenas-20230216.010400.344514.b'8jfL'@truenas.local>
+
+This is a multi-part message in MIME format.
+--===============2138658284696597373==
+Content-Type: multipart/alternative; boundary="===============2233989480071754745=="
+MIME-Version: 1.0
+
+--===============2233989480071754745==
+Content-Type: text/plain; charset="utf-8"
+MIME-Version: 1.0
+Content-Transfer-Encoding: base64
+
+VGhpcyBpcyBhIHRlc3QgbWVzc2FnZSBmcm9tIFRydWVOQVMgQ09SRS4=
+
+--===============2233989480071754745==
+Content-Type: text/html; charset="utf-8"
+MIME-Version: 1.0
+Content-Transfer-Encoding: base64
+
+PCFET0NUWVBFIEhUTUwgUFVCTElDICItLy9XM0MvL0RURCBIVE1MIDQuMCBUcmFuc2l0aW9uYWwv
+L0VOIj4KClRoaXMgaXMgYSB0ZXN0IG1lc3NhZ2UgZnJvbSBUcnVlTkFTIENPUkUuCg==
+
+--===============2233989480071754745==--
+
+--===============2138658284696597373==--
+.
+`
+
+		s, c, _, scanner := newTestSMTPServer(t, func(w http.ResponseWriter, r *http.Request) {
+			t.Fatal("This should not be called")
+		})
+		defer s.Close()
+		defer c.Close()
+		writeAndReadUntilLine(t, email, c, scanner, "451 4.0.0 invalid address")
+	}
+*/
 type smtpHandlerFunc func(http.ResponseWriter, *http.Request)
 
 func newTestSMTPServer(t *testing.T, handler smtpHandlerFunc) (s *smtp.Server, c net.Conn, conf *Config, scanner *bufio.Scanner) {