[MM-53057] Disallow malformed channel names for DMs (#24404)

server/public/model/bot_test.go

@@ -676,7 +676,7 @@ func TestIsBotChannel(t *testing.T) {
 		{
 			Name: "a direct channel with another user",
 			Channel: &Channel{
-				Name: "user1__user2",
+				Name: GetDMNameFromIds("user1", "user2"),
 				Type: ChannelTypeDirect,
 			},
 			Expected: false,
@@ -684,7 +684,7 @@ func TestIsBotChannel(t *testing.T) {
 		{
 			Name: "a direct channel with the name containing the bot's ID first",
 			Channel: &Channel{
-				Name: "botUserID__user2",
+				Name: GetDMNameFromIds("botUserID", "user2"),
 				Type: ChannelTypeDirect,
 			},
 			Expected: true,
@@ -692,7 +692,7 @@ func TestIsBotChannel(t *testing.T) {
 		{
 			Name: "a direct channel with the name containing the bot's ID second",
 			Channel: &Channel{
-				Name: "user1__botUserID",
+				Name: GetDMNameFromIds("user1", "botUserID"),
 				Type: ChannelTypeDirect,
 			},
 			Expected: true,

server/public/model/channel.go

@@ -339,6 +339,9 @@ func (o *Channel) GetOtherUserIdForDM(userId string) string {
 	}
 
 	userIds := strings.Split(o.Name, "__")
+	if len(userIds) != 2 {
+		return ""
+	}
 
 	var otherUserId string