Sanitize RemoteEmail user prop (#27170)

* Sanitize RemoteEmail user prop

If the server is configured to hide user emails, the "RemoteEmail"
user property will be sanitized as well, effectively hiding the real
email of remote users.

* fix merge conflict

---------

Co-authored-by: Doug Lauder <wiggin77@warpmail.net>
Co-authored-by: Mattermost Build <build@mattermost.com>

server/public/model/shared_channel.go

@@ -11,6 +11,11 @@ import (
 	"github.com/pkg/errors"
 )
 
+const (
+	UserPropsKeyRemoteUsername = "RemoteUsername"
+	UserPropsKeyRemoteEmail    = "RemoteEmail"
+)
+
 var (
 	ErrChannelAlreadyShared = errors.New("channel is already shared")
 	ErrChannelHomedOnRemote = errors.New("channel is homed on a remote cluster")

server/public/model/user.go

@@ -637,6 +637,7 @@ func (u *User) Sanitize(options map[string]bool) {
 
 	if len(options) != 0 && !options["email"] {
 		u.Email = ""
+		delete(u.Props, UserPropsKeyRemoteEmail)
 	}
 	if len(options) != 0 && !options["fullname"] {
 		u.FirstName = ""

server/public/model/user_test.go

@@ -384,3 +384,22 @@ func TestValidateCustomStatus(t *testing.T) {
 		assert.True(t, user0.ValidateCustomStatus())
 	})
 }
+
+func TestSanitizeProfile(t *testing.T) {
+	t.Run("should correctly sanitize email and remote email", func(t *testing.T) {
+		user := &User{
+			Email: "john@doe.com",
+			Props: StringMap{UserPropsKeyRemoteEmail: "remote@doe.com"},
+		}
+
+		user.SanitizeProfile(nil)
+
+		require.Equal(t, "john@doe.com", user.Email)
+		require.Equal(t, "remote@doe.com", user.Props[UserPropsKeyRemoteEmail])
+
+		user.SanitizeProfile(map[string]bool{"email": false})
+
+		require.Empty(t, user.Email)
+		require.Empty(t, user.Props[UserPropsKeyRemoteEmail])
+	})
+}