Linux [KAG Classic] Juxta++ - Advanced Server Modding for Classic

What is Juxta++
Juxta++ is a library made by rzaleu and myself, which enhances the functionality of KAG Classic, on server side.
It works by hooking the functions of the server, and makes it possible to do almost anything.
If you've already heard of KScript, think of this as a way more advanced version of it.

What can I do with it
A lot of things! Juxta++ comes along with a Lua scripting interface, providing an access to the functions and events.
For example, you can place blocks, get/set players position, get/set their health, resources, bombs arrows, spawn any item (bomb, arrow), spawn entities, and much more, check out the source code!
If you're a modder, you're going to love it.

Edit: list of functions compiled by TropicalMurloc

Spoiler: list of functions

List (ID) ActorTypes
PLAYER = 1
UNKNOWN_2 = 2
UNKNOWN_3 = 3
UNKNOWN_4 = 4
UNKNOWN_5 = 5
UNKNOWN_6 = 6
UNKNOWN_7 = 7
UNKNOWN_8 = 8
UNKNOWN_9 = 9
UNKNOWN_10 = 10
UNKNOWN_11 = 11
UNKNOWN_12 = 12
RUNNER = 13
EGG = 14
UNKNOWN_15 = 15
ZOMBIE = 16
UNKNOWN_17 = 17
LANTERN = 18
BOULDER = 19
======
List ID Block
AIR = 0
BEDROCK = 106
DIRT = 16
DIRT_BACK = 32
GOLD = 80
ROCK = 96
THICK_ROCK = 208
TREE = 119
RUBBLE = 155
LADDER = 144
CASTLE_WALL = 48
CASTLE_BACK = 64
GOLD_BULLION = 160
BLUE_DOOR = 128
RED_DOOR = 130
BLUE_BRIDGE = 176
RED_BRIDGE = 178
SPIKES = 167
WORKSHOP = 146
WOODEN_WALL = 196
WOODEN_BACK = 205
======
List ID Team
SPECTATOR", 200
======
List ID Keys
UP = 0
DOWN = 1
LEFT = 2
RIGHT = 3
ACTION = 4
ACTION2 = 5
ZOOMIN = 6//not working
ZOOMOUT = 7//not working
USE = 8
CHANGE = 9
DROP = 10
TAUNTS = 11//not working
BUBBLES = 12//not working
MENU = 13//not working
PARTY = 14//not working
======
List "Plugin" [ex: plugin.GetName()]
GetName
GetPath
Call
======
List "Juxta" [ex: Juxta.GetVersion()]
GetVersion
======
List "Actor" [ex: Actor.GetID()]
GetID
GetType
GetPlayer
======
List "Blob" [ex: Blob.GetFactoryName()]
GetFactoryName
GetConfigFileName
GetID
GetType
GetTeam
GetX
GetY
SetPosition
GetHealth
SetHealth
GetPlayer
IsFacingLeft
Kill
======
List "Egg" [ex: Egg.Kill()]
Kill
======
List "Player" [ex: Player.GetID()]
GetID
GetBlob
GetName
GetClantag
GetCharacterName
GetSeclevID
IsBot
GetClass
GetSex
GetNetworkID //Not Work
GetHost
GetIP
GetPosition //Not Work
GetX
GetY
GetVelX
GetVelY
GetMouseX
GetMouseY
GetIdleTime
GetHealth
GetDefaultHealth
GetBombs
GetArrows
GetWood
GetStone
GetGold
GetCoins
GetScore
======
SetClantag
SetName
SetPosition
SetVelocity
SetTeam
SetHealth
SetDefaultHealth
SetBombs
SetArrows
SetWood
SetStone
SetGold
SetCoins
SetScore
======
Kill
Kick
Freeze
Unfreeze
Mute
Unmute
Ban
SendMessage
======
IsPlaying
IsDead
IsCrouching
IsJumping
IsShielding
IsShieldingUp
IsShieldingDown
IsShieldingSide
IsFrozen
======
HasFeature
HasCommand
======
SetBoolean
SetNumber
SetString
SetTable
======
GetBoolean
GetNumber
GetString
GetTable
======
ChangeTeam
SetClass
GetSex
SetSex
GetSpecialColor
SetSpecialColor
GetHead
SetHead
======
IsKeyDown
WasKeyPressed
WasKeyReleased
ShootArrow
======
MountPlayer
MountBlob
UnMountPlayer
UnMountBlob
======
List "KAG" [ex: KAG.ChangeMAp()]
ChangeMap
ChangeMapPNG
GetTile
GetMapWidth
GetMapHeight
SetTile
CreateChatCommand
CreateRoomCommand
GetPlayers //Not Work
GetPlayersBySeclev //Not Work
GetPlayerByID
GetPlayerByName
GetPlayerByPartialName
GetPlayerByIndex"
GetPlayersCount
GetBlobByID
GetBlobByIndex
GetBlobsCount
GetEggByID
GetEggByIndex
GetEggsCount
SendRcon
NextMap
RestartMap
SaveMap
TriggerAutoBalance
SetDayTime
GetDayTime
GetUnitsLeft
IsWarmup
SpawnEgg
SpawnBomb
SpawnBot
SpawnBlob
SendMessage
GetBuildVersion
GetVersion
Break
======

What else does it do
In addition to the modding possibilities, it also fixes a bunch of server sided bugs.
We've already patched the following hacks: editor hack, speedhack, fast attack hack, builder range hack, moving when being frozen.

Where do I get it
Link to the github repository: https://github.com/master4523/juxtapp
The library only works on Linux based systems (tested on Ubuntu and Debian).
There's no plan to make it compatible with Windows/OSX for now.

Who made this?
This software is a collaboration between rzaleu and master4523.
Kudos to Konfitur and Chidori for helping us with testing!

I can't run it / I found a bug!
Feel free to reply here or send me a PM with the issue

 

It's nice that you're adding features, but the fact is that this counts as a "hack" as you're injecting third party code (via a Linux shared object) into the KAG binary itself. You probably also had to reverse engineer the KAG server to make this.

It doesn't help that you're not providing the source code (which you kind of can't since it'd publicly expose how KAG works internally) but because you're not we have no way of knowing what other stuff you code might do and whether or not it may be malicious, either deliberate (trying to escalate privileges or report home sensitive data) or not (excessive resource consumption).

I'm not sure how well this would sit with the kag devs. Did you consult @Geti when you made this?

 

He did. My feelings on these kind of "contributions" to the game are quite reserved, on one hand I honestly do not care at all about classic, and all the serverside "hacks" I've seen so far have been with positive intent; on the other I really wish the amount of energy put into these kind of projects was put into modding the release version of KAG instead of classic.

The latter is significantly more motivating to me "cracking down" on this kind of thing than the former; hacks for classic are nothing new and not something we can really stop either way, there's not a good way to detect these from a connecting client.

Incidentally, the reverse engineering side of how I believe all of these hacks work is hardly hard to do or "secret", and the way KAG works with relation to these hacks isn't very different to a lot of other games (update function gets called every so often; hook your code in there). A lot of the early scripting stuff worked through the TCPR channels, I wouldn't be surprised if this one in particular hooked the engine side functions directly though - that said I haven't looked into it :)

Either way, I'm not planning on cracking down on this kind of serverside "for the community" hacking. I need to talk with MM to see if he has any reservations but I don't think he cares much about classic either.

Seriously though guys, its a bit of a punch in the gut that you build a whole separate modding system on top of the old game, rather than using the modding system we built for you in the new one.

 

I agree with what Geti said:

Other than that I don't care and I admire the time and patience put into a project like this. Although you could have migrated classic as a mod in KAG in the same amount of time probably.

 

Re: legality
Technically the way it works can be considered as hacking, and I wouldn't have released it on the forums without the permission of Geti/MM. Turns out they're kind enough to tolerate this (actually they probably don't care :^) )

Re: malicious
I personally have nothing against releasing the source code for this, but it's not my decision. I'd have to ask KAG devs to review the code and I'm not sure they would allow it, since they're using the same base for the Steam release.
For the time being, I guess you can only take my word for it.
@jrgp if you want a copy of the source code I'll gladly send one to you

Re: y u do dis
For the same reason people make unofficial patches for abandonned games. It's just a hobby, I like challenges and I've learned a lot of things by making this.
The main strength of KAG has always been the fact that you can mod the hell out of it, that's what the devs did on the Steam release, and I'm just trying to show how far we can get with Classic, even with a dropped support.
In the end, I probably do it because... I can?

Again, if you have any questions, do not hesitate

 

Cool story, bro. Guess what? I don't care. Not my fault if your life sucks.

 

New update!

Changelog 1.0.1:
[lib][added] config file (juxtapp_config.cfg)
[kag][added] movement speedhack detection (please report any false positive)
[lua][modified]OnPlayerRespawn now takes two additional parameters: x and y pos of the respawn point
[lib][fixed] now prints in the console the name of the player who tried using editor hack, before kicking him
[lua][fixed] the output of print() is now correctly redirected to the server console (and saved in the server logs)
[lua][fixed] KAG.SendRcon crashes the server with script commands like addBot
[lib][fixed] using the command /plugins reloads every plugins before printing them

The default ban length for speedhacking is set to 15 minutes, you can change it in juxtapp_config.cfg (you can also disable it, if ... you like speedhackers)
Juxta++ is set to restart the server at the end of the round if an update has been downloaded. You can also disable that behavior in the config file.

 

New update!
Changelog 1.0.2:
[lib][added] fast attack hack detection (please report any false positive)
[lib][added] detection for builder range hack (place/destroy blocks with no distance limit)
[lib][added] attempt to fix tcpr spam attack
[lib][added] new chat command: /commands (prints all the chat commands registered by the plugins)
[lua][added] two new functions: KAG.GetMapWidth and KAG.GetMapHeight, to get the map size
[lua][modified] OnMapReceiveTile now takes three additional parameters: x, y, and block id
[lib][modified] optimized Lua plugins calls, better performances
[lua][fixed] server crash when using KAG.SpawnBlob, KAG.SpawnBot or KAG.SpawnEgg
[lib][fixed] speedhack detection now won't be triggered if the player has the seclev feature "speedkick_immunity"
[lib][removed] old debug message related speedhack detection