There is a trade dupe now that it's brought up that I patched nearly two years ago but it's not done that way either. Drop dupe has been disproven anyway long long ago. Of course I didn't test this but using knowledge of how the source works I can make a reasonable guess that the fix didn't do much, if anything. In that case the items in the trade would be gone whereas if the save actually wasn't there disconnect would be called and the trade would be cancelled and the items would be given before saveToDB is called.

I would say saving there would result in more problems in case you were trading and the user dced (not server crash). In order for the data that was saved to show up real time in game, the inventory would have to be loaded again, which is not likely done (would be impractical too). Saving prevents rollback dupes and that's about all.ДЇor the trade, saving will only prevent rollback duping for the same reason given above. What I did before to dupe on my server for fun was abuse this fact. That method saves your current information to the database and has nothing to do with the current state of your character since you would have to reload the inventory items to see the changes to the database. Saving would not make the items not spawn and even if the argument was it would check the items if it existed or not, this is not actually what saveToDB does. Theoretically items should spawn when the packets are sent. Let's say someone used those two packets to dupe by dropping items or something. Now let me elaborate on why your fix wouldn't do anything. There is no way to dupe this because you would have to go through the entire trading process again (create room/invite player, set items, confirm trade, exit). When the person accepts the trade, the person obtains the item. The bottom line is you lose the item so you should not be able to add it again. There should be checks already there to see if you have the item or not before adding and even if there isn't, it would probably give a null pointer anyway. You add items by sending a specific packet to add items to the window. You add items to the window, and you lose the items. Now let me explain to you how the trade actually works here when you add items. Send change map packet to enter cash shop (which saves your character) I'm assuming it's v83 because the player interaction packet opcode is 0x7B which is the other one.Д 0 - Mode (Create, so this is sent when you start interaction)Д 0 - Forgot but irrelevant since it isn't handledДў.

So there you go for the first one.ДЇrom Moople, it says it's the one that is sent from changing maps (v83) and two bytes is for entering cash shop or something. Also that first method up there is only used when items are being dropped so there cannot be any other cases. I can't think of another way you could dupe here without doing dropping an item you don't have. Sending a packet again will not drop the item if you do not possess another one. First, you cannot duplicate items by dropping them.

Maplestory private server v83 dupe hack