fix(GODT-3229): escape reserved XML characters in Apple configuration profile.

internal/clientconfig/applemail.go

@@ -21,6 +21,7 @@ import (
 	"os"
 	"path/filepath"
 	"strconv"
+	"strings"
 	"time"
 
 	"github.com/ProtonMail/proton-bridge/v3/internal/useragent"
@@ -70,24 +71,24 @@ func prepareMobileConfig(
 	password []byte,
 ) *mobileconfig.Config {
 	return &mobileconfig.Config{
-		DisplayName:        username,
-		EmailAddress:       addresses,
-		AccountName:        displayName,
-		AccountDescription: username,
-		Identifier:         "protonmail " + username + strconv.FormatInt(time.Now().Unix(), 10),
+		DisplayName:        escapeXMLString(username),
+		EmailAddress:       escapeXMLString(addresses),
+		AccountName:        escapeXMLString(displayName),
+		AccountDescription: escapeXMLString(username),
+		Identifier:         escapeXMLString("protonmail " + username + strconv.FormatInt(time.Now().Unix(), 10)),
 		IMAP: &mobileconfig.IMAP{
-			Hostname: hostname,
+			Hostname: escapeXMLString(hostname),
 			Port:     imapPort,
 			TLS:      imapSSL,
-			Username: username,
-			Password: string(password),
+			Username: escapeXMLString(username),
+			Password: escapeXMLString(string(password)),
 		},
 		SMTP: &mobileconfig.SMTP{
-			Hostname: hostname,
+			Hostname: escapeXMLString(hostname),
 			Port:     smtpPort,
 			TLS:      smtpSSL,
-			Username: username,
-			Password: string(password),
+			Username: escapeXMLString(username),
+			Password: escapeXMLString(string(password)),
 		},
 	}
 }
@@ -121,3 +122,13 @@ func saveConfigTemporarily(mc *mobileconfig.Config) (fname string, err error) {
 
 	return
 }
+
+// escapeXMLString replace all occurrences of the 5 characters `&`, `<`, `>`, `"` and `'` by their respective escaped version as per the XML spec.
+// https://www.w3.org/TR/xml/#syntax
+func escapeXMLString(input string) string {
+	result := strings.ReplaceAll(input, `&`, `&amp;`)
+	result = strings.ReplaceAll(result, `<`, `&lt;`)
+	result = strings.ReplaceAll(result, `>`, `&gt;`)
+	result = strings.ReplaceAll(result, `"`, `&quot;`)
+	return strings.ReplaceAll(result, `'`, `&apos;`)
+}

internal/clientconfig/applemail_test.go

@@ -0,0 +1,38 @@
+// Copyright (c) 2024 Proton AG
+//
+// This file is part of Proton Mail Bridge.
+//
+// Proton Mail Bridge is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Proton Mail Bridge is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
+
+//go:build darwin
+
+package clientconfig
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestEscapeXMLString(t *testing.T) {
+	require.Equal(t, escapeXMLString(`abc&&''""<<>>def`), `abc&amp;&amp;&apos;&apos;&quot;&quot;&lt;&lt;&gt;&gt;def`)
+}
+
+// This test requires human interaction (user configuration profile installation prompt). It is for debugging purpose and is disabled by default.
+func _TestInstallCert(t *testing.T) { //nolint:unused
+	require.NoError(
+		t,
+		(&AppleMail{}).Configure(`127.0.0.1`, 1143, 1025, true, false, `user&>>`, `<<abc&&'"def>>`, `user&a`, []byte(`ir8R9vhdNXyB7isWzhyEkQ`)),
+	)
+}