diep.io Protocol

diep.io is a small online war game featuring tanks, bullets and blobs. There are several game modes but this document only concentrates on the FFA mode.

1. Communication
2. Data types
3. Packet format
4. Packets
   1. Serverbound
   2. Clientbount

Communication

Data is transmitted through a http websocket pipe.

Data types

This game uses standard data formats. Bytes are in big endian order. The size of each type might not be constant (eg. strings, varints).

Name	Size (bytes)	Data range	Notes
uint8	1	An integer between 0 and 255	Unsigned 8-bit integer
uint16	2	An integer between 0 and 65535	Unsigned 16-bit integer
uint32	4	An integer between 0 and 4294967295	Unsigned 32-bit integer
int8	1	An integer between -128 and 127	Signed 8-bit integer
int16	2	An integer between -32768 and 32767	Signed 16-bit integer
int32	4	An integer between -2147483647 and 2147483646	Signed 32-bit integer
float32	4	A floating point number	Floating point number with 32-bit precision
float64	8	A floating point number	Floating point number with 64-bit precision
String	≥ 1	A variable-length UTF-8 string	The string ends when byte 0x00 is reached
T[i]	?	A fixed size array of a type	Arrays can contain any type of data

Packet format

Every packet begins with one byte indicating the packet ID and then the content follows. Packets can be split if they are too large but this behavior is automatically corrected by the buffer manager.

Type	Size (bytes)	Notes
Packet ID	1	There can be 256 different packets, but in practice there are only a few. Sending an unknown packet ID will immediately close the connection.
Content	≥ 0	Packets can have an empty body

Packets

Some packets might be missing and their purposes haven't been totally discovered.

Serverbound

Packets sent from the client to the server.

Recap

Packet ID	Arbitrary name	Purpose
0x00	User ID	Sent at the begining of the connection, contains the ID of the player.
0x01	Player control	Contains the location of the mouse, if the player is shooting and the state of the 4-directional keys
0x02	Start game	Contains the nickname entered by the player
0x03	Tank upgrade	Tells the server which upgrade the player wants to choose
0x04	Tank evolution	Tells the server which evolution the player wants to choose
0x05	Heartbeat	The server checks if the player is still online. This packet is sent every 0.1 second.

0x00 User ID

Field	Type	Notes
User ID	String	No maximal length specified

0x01 Player control

Field	Type	Notes
???	8 to 10 bytes	Mouse location (?)
Keys	uint8	State (pressed or released) of 5 keys encoded in bits

Codes for each key can be found in the following table. Each key state is added to the stack using the logic OR ( =| ) operator.

Key	Code (byte)	Code (binary)
Mouse left button	0x01	0b00000001
Arrow up	0x02	0b00000010
Arrow left	0x04	0b00000100
Arrow down	0x08	0b00001000
Arrow right	0x10	0b00010000

0x02 Start game

Field	Type	Notes
Nickname	String	Nicknames must be between 0 and 15 characters long

0x03 Tank upgrade

Field	Type	Notes
Upgrade ID	uint8	The upgrade level doesn't matter

Upgrades IDs can be found in the following table.

Upgrade	Code (byte)
Health regeneration	0x0e
Maximum health	0x0c
Body damage	0x0a
Bullet speed	0x08
Bullet penetration	0x06
Bullet damage	0x04
Reload	0x02
Movement speed	0x00

0x04 Tank evolution

Field	Type	Notes
Tank ID	uint8	Each tank has its own ID

Tanks IDs are as following.

Tier	Levels requiered
0	0
1	15
2	30
3	45

Tier	Tank name	Obtainable after	Code (byte)
1	Twin	Normal	0x02
1	Flank Guard	Normal	0x10
1	Machine Gun	Normal	0x0e
1	Sniper	Normal	0x0c
2	Triple Shot	Twin	0x06
2	Twin Flank	Twin OR Flank Guard	0x1a
2	Quad Tank	Twin OR Flank Guard	0x08
2	Tri Angle	Flank Guard	0x12
2	Destroyer	Machine Gun	0x14
2	Gunner	Machine Gun	0x28
2	Assassin	Sniper	0x1e
2	Overseer	Sniper	0x16
2	Hunter	Sniper	0x26
3	Triplet	Triple Shot	0x04
3	Penta Shot	Triple Shot	0x1c
3	Triple Twin	Twin Flank	0x24
3	Octo Tank	Twin Flank OR Quad Tank	0x0a
3	Booster	Tri Angle	0x2e
3	Fighter	Tri Angle	0x30
3	Hybrid	Destroyer	0x32
3	Stalker	Assassin	0x2a
3	Ranger	Assassin	0x2c
3	Manager	Overseer	0x34
3	Overlord	Overseer	0x18
3	Necromancer	Overseer	0x22

0x05 Heartbeat

This packet is empty.

Clientbound

Packets sent from the server to the client.

Recap

Packet ID	Arbitrary name	Purpose
0x00	???	???
0x02	???	Contains sometimes the shop data and the leaderboard (?)
0x04	Server location	Tells the client its location
0x05	Heartbeat	The client checks if the server is still online. This packet is sent every 0.1 second.

0x00 ???

Field	Type	Notes
Counter	uint8	Counts from 128 to 255 (?)
???	???	???

0x02 ???

Field	Type	Notes
???	???	???
Nicknames	String[10]	10 best players on the server
???	???	???
Scores	float32[10]	And their score
???	???	???

0x04 Server location

Field	Type	Notes
Location name	String	Contains informations about the server's location

0x05 Heartbeat

This packet is empty.