Implement player abilities packet

Obsidian/Client.cs

@@ -708,6 +708,10 @@ internal async Task SendPlayerInfoAsync()
         }
 
         await QueuePacketAsync(new PlayerInfoUpdatePacket(dict));
+        await QueuePacketAsync(new PlayerAbilitiesPacket(true)
+        {
+            Abilities = Player.Abilities
+        });
     }
 
     internal void SendPacket(IClientboundPacket packet)

Obsidian/Entities/Player.cs

@@ -62,7 +62,24 @@ public sealed partial class Player : Living, IPlayer
 
     public IBlock? LastClickedBlock { get; internal set; }
 
-    public Gamemode Gamemode { get; set; }
+    public Gamemode Gamemode
+    {
+        get => gamemode;
+        set
+        {
+            gamemode = value;
+
+            Abilities = Gamemode switch
+            {
+                Gamemode.Creative => PlayerAbility.CreativeMode | PlayerAbility.AllowFlying | PlayerAbility.Invulnerable,
+                Gamemode.Spectator => PlayerAbility.AllowFlying | PlayerAbility.Invulnerable,
+                Gamemode.Survival or Gamemode.Adventure or Gamemode.Hardcore => PlayerAbility.None,
+                _ => throw new ArgumentOutOfRangeException(nameof(Gamemode), Gamemode, "Unknown gamemode.")
+            };
+        }
+    }
+
+    public PlayerAbility Abilities { get; internal set; }
 
     public IScoreboard? CurrentScoreboard { get; set; }
 
@@ -115,6 +132,8 @@ internal set
 
     public IPAddress? ClientIP => (client.RemoteEndPoint as IPEndPoint)?.Address;
 
+    private Gamemode gamemode = Gamemode.Creative;
+
     [SetsRequiredMembers]
     internal Player(Guid uuid, string username, Client client, World world)
     {

Obsidian/Net/ClientHandler.cs

@@ -44,6 +44,7 @@ public void RegisterHandlers()
         Packets.TryAdd(0x17, new SetPlayerPositionPacket());
         Packets.TryAdd(0x18, new SetPlayerPositionAndRotationPacket());
         Packets.TryAdd(0x19, new SetPlayerRotationPacket());
+        Packets.TryAdd(0x20, new PlayerAbilitiesPacket(false));
         //Packets.TryAdd(0x15, PlayerMovement);
         //Packets.TryAdd(0x16, VehicleMove);
         //Packets.TryAdd(0x17, SteerBoat);

Obsidian/Net/Packets/Play/Clientbound/PlayerAbilitiesPacket.cs

@@ -0,0 +1,67 @@
+using Obsidian.Entities;
+
+namespace Obsidian.Net.Packets.Play.Clientbound;
+
+[Flags]
+public enum PlayerAbility
+{
+    None = 0x00,
+    Invulnerable = 0x01,
+    Flying = 0x02,
+    AllowFlying = 0x04,
+    CreativeMode = 0x08
+}
+
+public class PlayerAbilitiesPacket : IClientboundPacket, IServerboundPacket
+{
+    public PlayerAbility Abilities { get; set; } = PlayerAbility.None;
+
+    public float FlyingSpeed { get; set; } = 0.05F;
+
+    public float FieldOfViewModifier { get; set; } = 0.1F;
+
+    public int Id { get; }
+
+    public PlayerAbilitiesPacket(bool toClient)
+    {
+        Id = toClient ? 0x36 : 0x20;
+    }
+
+    public void Serialize(MinecraftStream stream)
+    {
+        using var packetStream = new MinecraftStream();
+        packetStream.WriteByte((byte)Abilities);
+        packetStream.WriteFloat(FlyingSpeed);
+        packetStream.WriteFloat(FieldOfViewModifier);
+
+        stream.Lock.Wait();
+        stream.WriteVarInt(Id.GetVarIntLength() + (int)packetStream.Length);
+        stream.WriteVarInt(Id);
+        packetStream.Position = 0;
+        packetStream.CopyTo(stream);
+        stream.Lock.Release();
+    }
+
+    public void Populate(MinecraftStream stream)
+    {
+        Abilities = (PlayerAbility) stream.ReadByte();
+    }
+
+    public void Populate(byte[] data)
+    {
+        using var stream = new MinecraftStream(data);
+        Populate(stream);
+    }
+
+    public async ValueTask HandleAsync(Server server, Player player)
+    {
+        if (Abilities.HasFlag(PlayerAbility.Flying)
+            && !Abilities.HasFlag(PlayerAbility.AllowFlying)
+            && player.Gamemode is not Gamemode.Creative or Gamemode.Spectator)
+        {
+            await player.KickAsync("Cheating is not allowed!");
+        }
+
+        player.Abilities |= Abilities;
+    }
+}