Firefall Guid System

Source: https://gist.github.com/SilentCLD/881839a9f45578f1618db012fc789a71

// Mostly speculation:
// There are three types of GUIDs, starting with:
// 1. Anything that isn't listed below (0x20, 0x1E, 0x0A, 0x46 etc)
// 2. 0x7F
// 3. 0xFF
//
// The first are v2 Guids, they appeared some time before 03/11/14 and conform to the structure below.
//
// The second are v1 Guids, they were the original implementation* and the structure is currently unknown.
//   It's possible they were converted from another system and given the 0x7F range to not conflict with v2
//
// The third are also v2 Guids but are used for map entities which only need a unique identifier for the current map session/shard (NPCs, Deployables, Map markers etc).
//   Map Guids will always start with 0xFF and will _not_ have the timestamp bits set

//
// Guid V2 Structure - Variation of MySQL UUID_SHORT()
// ServerId  = Region + sql node cluster id? (1 byte)
// Timestamp = Server boot time in Unix seconds shifted to the right by 8 bits (3 bytes)
// Counter   = Auto increment counter shifted to the left by 8 bits (3 bytes)
// Type      = Entity type id (1 byte)

//
// A Guid can be split in to two sections, High and Low
// Using the following player Guid as an example: 0x1F54FA9E_38037701
// The High part signifies where and roughly when a Guid was created - This can be initialized on startup of the application lifetime
// The Low part signifies the partial ID and Type of entity - This must be created for each entity
// If stored this way it may simplify full Guid creation
// ulong full = ((ulong)hi << 32) | ((ulong)lo);

//
// Notes:
// The Counter can be stored in memory - it doesn't need to persist between reboots as we also rely on Timestamp for uniqueness
//
// The Counter has an auto increment value of 100, this isn't strictly meaningful but may have been used to more easily create the Low part
//
// When 32bit Unix overflows in 2038 this should still continue working for another ~68 years as it will wrap around
//
// It is possible for a collision to occur if the server starts, generates a Guid, restarts then generates another straight away
//   as we lose 256 seconds (4 minutes) of precision with the Timestamp shift.
//   It would be best to use the start time of the system rather than the application.
//
// Account/Mail ids are distributed as a uint32 (3 byte Counter, 1 byte Type)

//
// Examples of Guids
//
// 0x7F3CB864AB349201 - v1 Player
// 0x7FB962A3946C4101 - v1 Player
// 0x205456D420319F01 - v2 Player
// 0x1F54FA9E38037701 - v2 Player
// (Types missing)
// 0xFF000000000F0100 - v2 Map POI
// 0xFF00000000009600 - v2 Health pickup
// 0xFF00000000009A00 - v2 New You
// 0x0B56AA25E40391FD - v2 Item
// 0x0A56A7B5DC2C5AFD - v2 Item


//
// Example of parsing and generating a Guid
//
EntityGuid parsed = EntityGuid.Parse(0x1F54FA9E38037701);
EntityGuid generated = new(31, 1425710592, 3670903, 0x01);

Console.WriteLine( "        ServerId   Counter    Type           Timestamp                     Full");
Console.WriteLine($"Parsed   : {parsed.ServerId}      {parsed.Counter}    0x{parsed.Type:X2}    {DateTimeOffset.FromUnixTimeSeconds(parsed.Timestamp)}    0x{parsed.Full:X16}");
Console.WriteLine($"Generated: {generated.ServerId}      {generated.Counter}    0x{generated.Type:X2}    {DateTimeOffset.FromUnixTimeSeconds(generated.Timestamp)}    0x{generated.Full:X16}");

// Output:
//
//         ServerId   Counter    Type           Timestamp                     Full
// Parsed   : 31      3670903    0x01    07/03/2015 06:43:12 +00:00    0x1F54FA9E38037701
// Generated: 31      3670903    0x01    07/03/2015 06:43:12 +00:00    0x1F54FA9E38037701

public readonly struct EntityGuid
{
    public ulong Full => (ulong)((ulong)ServerId << 56) +
                         ((ulong)((Timestamp >> 8) & 0x00FFFFFF) << 32) +
                         (Counter << 8) +
                         Type;

    public byte ServerId { get; private init; }
    public uint Timestamp { get; private init; }
    public uint Counter { get; private init; }
    public byte Type { get; private init; }

    public EntityGuid(byte serverId, uint timestamp, uint counter, byte type)
    {
        ServerId = serverId;
        Timestamp = timestamp;
        Counter = counter;
        Type = type;
    }

    public static EntityGuid Parse(ulong guid)
    {
        EntityGuid entityGuid = new()
        {
            ServerId = (byte)(guid >> 56),
            Timestamp = (uint)(((guid >> 32) & 0x00FFFFFF) << 8),
            Counter = (uint)((guid & 0xFFFFFF00) >> 8),
            Type = (byte)(guid & 0xFF),
        };

        return entityGuid;
    }
}

Type (typecode)

When guids are used in network messages, the type used is often defined in an enum present in the game client identifying different kinds of network views. For reference, see this list from client 1962..

But guids are also used for things that do not have a network view (like Armies) and in scenarios outside the network protocol (like WebAPI requests). For example, when the client sends a request to the WebAPI route that includes a Character, it uses 0xFE as the type.

The following is our hypothetical list of these:

0xFB - Instance/World/Zone
0xFC - Army
0xFD - Item
0xFE - Character