This proxy parses Minecraft alpha network communication between the client and a Survial Multiplayer server, enabling easy manipulation of packets in order to exploit the extent to which the server trusts the client.
Run the proxy giving the server's hostname and port as separate commandline arguments:
./proxy example.com 1234
If you omit the port, it will default to 25565, minecraft's default port. The
proxy will listen on port 25565, so that you can use the minecraft client to
connect to the system running the proxy, e.g. localhost:25565 or ::1 for
short.
The proxy will then establish a connection to the server and transparently pass on packets in either direction. stdout will display the current buffer size if it rises beyond some threshold, so if you observe this number continuously growing, chances are something was parsed incorrectly and the proxy lost track of packet boundaries.
The proxy is not configurable, its behavious is hardcoded.
From the server it will intercept all the server time updates and rewrite them so that it is constantly early morning and appropriately bright.
From the client, it will intercept the new slash commands /send, /return
and/take.
/send and /return will prefix "Packet" to the rest of the line
and parse it as per the haskell Read instances of the involved types. /send
will send the result onwards to the server, /return will return the packet
right back to the client.
/take will parse the rest of the line as an item id (see, for example, this
list) and optionally a quantity, and then return a packet to the
client indicating that such an item acquisition just happened. Note that a
quantity of -1 will provide a stack of seemingly infinite quantity, but the
stack will disappear when you punch a player or mob with it.
All the protocol know-how comes from here and transitively from
#mcc, and from badgering fry when that was not enough.
Haskell is pretty cool, and playing around with all the crazy scaffolding that comes with it was pretty much the motivation for this project. This whole project does not actually do all that much, but it does it in a very elaborate and personally satisfying way. If someone comes up with other cool hacks for this proxy (dumping world data to a singleplayer savegame? Chatlogs, chatbots?), I would love to hear about it.
I kind of hope that someone who goes through the trouble of checking out code from github and piping it through ghc is above the sort of dumb schemes to ruin your own fun and that of others that spawning a million blocks of tnt on other people's servers enables. Your call.