Attempts to explain the new netcode of the game, new packets and how mods can use them.
 
 

Introduction

This guide is an attempt at document the netcode of Quake Enhanced for the purpose of modding and source ports adding compatibility.
 
 
There’s no guarantee about the information in this guide being 100% correct or complete.
 
 
The guide will be updated as new information comes in.
 
 
 

Overview

The 2021 Re-Release netcode is based off the existing Netquake netcode. It extends it further with more packets and functionality and adds a layer of encryption.
 
 
Quake netcode uses UDP for communication. The packets are wrapped around DTLS 1.2 for encryption and security. A PSK (Pre-Shared Key) is used for authentication between server and client. The game uses OpenSSL implementation of DTLS.
 
 
 

Data Types

Quake netcode uses a bunch of datatypes.
 
 

Function call	Type	Size in bytes	Callable from QC	Comments
WriteChar	char	1	Yes
WriteByte	byte	1	Yes
WriteShort	short	2	Yes
WriteLong	int	4	Yes
WriteFloat	float	4	No
WriteDouble	double	8	No
WriteString	C-style string	1+	Yes	Repeats chars until the byte 0 is found
WriteCoord	float	4	Yes
WriteAngle	byte	1	Yes	Converts a float using the following formula: ((int)f*256/360) & 255
WriteEntity	short	2	Yes	Writes out the entity index

 
 
 

Packets – Client to Server

Packet	Byte value	Description
CLC_BAD	0
CLC_NOP	1
CLC_DISCONNECT	2
CLC_MOVE	3
CLC_STRINGCMD	4
CLC_UNKNOWN1	5	Appears to be sent every frame
CLC_UNKNOWN2	6

 
 
 

Packets – Server to Client

Packet	Byte value	Description
SVC_BAD	0
SVC_NOP	1	Used as a heartbeat
SVC_DISCONNECT	2	Sent when the server is closing the connection
SVC_UPDATESTAT	3
SVC_VERSION	4
SVC_SETVIEW	5	Tell the client to attach the camera to a specific entity
SVC_SOUND	6
SVC_TIME	7
SVC_PRINT	8	Print something
SVC_STUFFTEXT	9	Print on the top-left of the screen
SVC_SETANGLE	10
SVC_SERVERINFO	11	Contains information about map, maxplayers, which files to precache, and so on
SVC_LIGHTSTYLE	12
SVC_UPDATENAME	13	Sets a player name on the scoreboard
SVC_UPDATEFRAGS	14	Sets a player frags on the scoreboard
SVC_CLIENTDATA	15
SVC_STOPSOUND	16
SVC_UPDATECOLORS	17
SVC_PARTICLE	18	Creates a particle emission effect
SVC_DAMAGE	19
SVC_SPAWNSTATIC	20
SVC_SPAWNBASELINE	22
SVC_TEMPENTITY	23
SVC_SETPAUSE	24
SVC_SIGNONNUM	25
SVC_CENTERPRINT	26	Prints something in the middle of the screen
SVC_KILLEDMONSTER	27
SVC_FOUNDSECRET	28
SVC_SPAWNSTATICSOUND	29
SVC_INTERMISSION	30
SVC_FINALE	31
SVC_CDTRACK	32
SVC_SELLSCREEN	33
SVC_CUTSCENE	34
SVC_SKYBOX	37
SVC_BOTCHAT	38	Displays a text message in chat as coming from a player.
SVC_SPAWNEDMONSTER	39
SVC_BONUSFLASH	40
SVC_FOG	41
SVC_SPAWNBASELINE2	42
SVC_SPAWNSTATIC2	43
SVC_SPAWNSTATICSOUND2	44
SVC_SETVIEWS	45
SVC_UPDATEPING	46
SVC_UPDATESOCIAL	47
SVC_UPDATEPLINFO	48
SVC_RAWPRINT	49
SVC_SERVERVARS	50
SVC_SEQ	51
SVC_ACHIEVEMENT	52
SVC_CHAT	53	Prints a message in the chat
SVC_LEVELCOMPLETED	54	Probably used for achievements
SVC_BACKTOLOBBY	55	Tells the client that they should go back to the lobby screen
SVC_LOCALSOUND	56	Plays a sound that is only heard by the client

 
 
 

SVC_*: A-Z

SVC_BOTCHAT

 
This packet tells the client to display a chat message as coming from a specific player id.
 
 

Offset	Call	Name
0	WriteByte	Packet Id
1	WriteByte	Player Id
2	WriteShort	String count
4	WriteString	String 1
…	WriteString	String …

 
Example
 
 

WriteByte(MSG_ALL,SVC_BOTCHAT);
WriteByte(MSG_ALL,0); // Player 0, the host.
WriteShort(MSG_ALL,1); // How many strings are present
WriteString(MSG_ALL,"Someone is talking for me!");

 
 
With string replacement
 
 

WriteByte(MSG_ALL,SVC_BOTCHAT);
WriteByte(MSG_ALL,0); // Player 0, the host.
WriteShort(MSG_ALL,2); // How many strings are present
WriteString(MSG_ALL,"My name is {}");
WriteString(MSG_ALL,"JPiolho");

 
 

 
 

SVC_CENTERPRINT

 
This packet tells the client to print text in the middle of the screen. It supports string replacements.
 
 

Offset	Call	Name
0	WriteByte	Packet ID
1	WriteShort	String count
3	WriteString	String 1
…	WriteString	String …

 
Default center print
 
 

WriteByte(MSG_ALL,SVC_CENTERPRINT);
WriteShort(MSG_ALL,1); // Number of strings that will follow
WriteString(MSG_ALL,"Hello world");

 
 
With string replacement
 
 

WriteByte(MSG_ALL,SVC_CENTERPRINT);
WriteShort(MSG_ALL,2); // Number of strings that will follow
WriteString(MSG_ALL,"Welcome to the game, {}");
WriteString(MSG_ALL,"JPiolho");

 
 

 
 

SVC_CHAT

 
This packet tells the client to print text in chat. It appears to only work in single player games.
 
Unlike SVC_BOTCHAT, you have full control over the name of the person plus you can specify some colors.
 
 
Available name colors: White (0), Red (1), Light Blue (2), Yellow (3)
 
Available message colors: White (0), Light blue (1)
 
 

Offset	Call	Name
0	WriteByte	Packet ID
1	WriteByte	Name color (0-3)
2	WriteByte	Message color (0-1)
3	WriteString	Name
…	WriteString	Message

 
Default center print
 
 

WriteByte(MSG_ALL,53); // SVC_CHAT
WriteByte(MSG_ALL,0); // Name color (0-3)
WriteByte(MSG_ALL,0); // Message Color (0-1)
WriteString(MSG_ALL,"Name"); // Name
WriteString(MSG_ALL,"Color 0"); // Message

 
 

 
 

SVC_UPDATENAME

 
This packet tells the client to update a player’s name in the scoreboard
 
 

Offset	Call	Name
0	WriteByte	Packet Id
1	WriteByte	Player Id
2	WriteString	Player name

 
Example
 
 

WriteByte(MSG_ALL,SVC_UPDATENAME);
WriteByte(MSG_ALL,0); // Player 0, the host.
WriteString(MSG_ALL,"Nobody"); // Set player name to 'Nobody'

 
 
 

Entity packet

This documentation is very incomplete
 
 
The entity packet is a bit special. It needs to be sent every frame to the players so that they know it exists. It also specifies all the attributes the client needs in order to display it on the client-side. Things like position, angles, model, solidness, etc…
 
 
Instead of having a regular numeric packet id, it relies on the bit 7 of the packet id being set. All the other bits in the byte are used as flags. The size of this packet is highly variable as it depends on the flags that are set.
 
 
Start by having a packet id of 128 and then adding different flags that you want.
 
 
The packet starts with a flag bitmap of 1 or more bytes. These indicate which entity properties are being sent. After the flag bitmap, the entity id is sent. After this, all the data that was specified in the flag bitmap is sent (in a specific order).
 
 
Byte Flagmap 1
 

Bit	Name
0	More flag bytes
1	Origin X
2	Origin Y
3	Origin Z
4	Angle Y
5	No lerp
6	Frame
7	Entity packet signal (always set to 1)

 
If “More flag bytes” bit was set, then the following packet follows:
 
Byte flagmap 2
 

Bit	Name
0	Angle X
1	Angle Z
2	Model Index
3	Color map
4	Skin
5	Effects
6	Is it a long entity?
8	More flag bytes

 
If “More flag bytes” bit was set, then the following packet follows:
 
Byte flagmap 3
 

Bit	Name
0	Alpha
1	Unsure – Frame
2	Unsure – Model Index
3	Unsure – When the next think will happen
4
5	Unsure – Origin Offset
6	Solid
7	More flag bytes

 
If “More flag bytes” bit was set, then the following packet follows:
 
Byte flagmap 4
 

Bit	Name
0	Unsure – Flags
1	Unsure – Health
2	Unsure – Model Index
3
4
5
6
7

 
The Entity Id follows. If “Long Entity” bit was set, the entity Id is sent as a Short (2 bytes). If not set then it’s sent as a byte (1 byte).
 
 
Now all the information that was specified in the flagmap is sent, in the following order:
 

Call	If bit is set	Name	Comment
WriteByte	Byte 2, bit 2	Model Index
WriteByte	Byte 1, bit 6	Frame
WriteByte	Byte 2, bit 3	Colormap
WriteByte	Byte 2, bit 4	Skin
WriteByte	Byte 2, bit 5	Effects
WriteFloat	Byte 1, bit 1	Origin X	If byte 3 bit 5 is set, then the call is WriteShort
WriteByte	Byte 2, bit 0	Angle X
WriteFloat	Byte 1, bit 2	Origin Y	If byte 3 bit 5 is set, then the call is WriteShort
WriteByte	Byte 1, bit 4	Angle Y
WriteFloat	Byte 1, bit 3	Origin Z	If byte 3 bit 5 is set, then the call is WriteShort
WriteByte	Byte 2, bit 1	Angle Z
WriteByte	Byte 3, bit 0	Alpha
WriteByte	Byte 3, bit 1	Frame
WriteByte	Byte 3, bit 2	Model Index
WriteByte	Byte 3, bit 3	Next Think
WriteByte	Byte 3, bit 6	Solid
Unknown	Byte 4, bit 0	Flags	Appears to send multiple values
Unknown	Byte 4, bit 1	Healths	Appears to send multiple values
Unknown	Byte 4, bit 2	Model Indexes	Appears to send multiple values

 
Example in QuakeC
 
 

 local float firstBits;
 local float secondBits;
 local float thirdBits;

 firstBits |= 1; // More bytes

 firstBits |= 1 << 1; // Origin 1
 firstBits |= 1 << 2; // Origin 2
 firstBits |= 1 << 3; // Origin 3
 firstBits |= 1 << 4; // Angle 2
 firstBits |= 1 << 6; // Frame

 secondBits |= (1 << 8) >> 8; // Angle 1
 secondBits |= (1 << 9) >> 8; // Angle 3
 secondBits |= (1 << 10) >> 8; // Model Index
 secondBits |= (1 << 11) >> 8; // Colormap
 secondBits |= (1 << 12) >> 8; // Skin
 secondBits |= (1 << 13) >> 8; // Effects
 secondBits |= (1 << 14) >> 8; // Long Entity
 secondBits |= (1 << 15) >> 8; // More bytes

 thirdBits |= (1 << 16) >> 16; // Alpha
 thirdBits |= (1 << 22) >> 16; // Solid

 msg_entity = self;
 WriteByte(MSG_ONE,firstBits | 128); // Packet Type

 // Send all the values
 if(firstBits & 1)
 WriteByte(MSG_ONE,secondBits);
 if(secondBits & 128)
 WriteByte(MSG_ONE,thirdBits);
 
 WriteShort(MSG_ONE,1500 + pNumber); // Entity ID

 WriteByte(MSG_ONE,modelindex_player);
 WriteByte(MSG_ONE,p.frame); 
 WriteByte(MSG_ONE,p.colormap);
 WriteByte(MSG_ONE,p.skin);
 WriteByte(MSG_ONE,p.effects);
 WriteCoord(MSG_ONE,p.origin_x);
 WriteAngle(MSG_ONE,p.angles_x);
 WriteCoord(MSG_ONE,p.origin_y);
 WriteAngle(MSG_ONE,p.angles_y);
 WriteCoord(MSG_ONE,p.origin_z);
 WriteAngle(MSG_ONE,p.angles_z);
 WriteByte(MSG_ONE,120);
 WriteByte(MSG_ONE,SOLID_NOT);

 
 

 
 
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