Use minimal Project Zomboid RCON protocol client

src/Beetlejuice.csproj

@@ -11,7 +11,6 @@
     <StripSymbols>true</StripSymbols>
   </PropertyGroup>
   <ItemGroup>
-    <PackageReference Include="CoreRCON" Version="5.4.2" />
     <PackageReference Include="Microsoft.Extensions.Hosting" Version="10.0.3" />
     <PackageReference Include="NetCord.Hosting" Version="1.0.0-beta.18" />
     <PackageReference Include="NetCord.Hosting.Services" Version="1.0.0-beta.18" />

src/Program.cs

@@ -1,6 +1,8 @@
+using System.Buffers.Binary;
 using System.Net;
+using System.Net.Sockets;
+using System.Text;
 using System.Text.RegularExpressions;
-using CoreRCON;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
 using NetCord;
@@ -53,10 +55,38 @@ string Whitelist(ApplicationCommandContext c, string discordId, bool add)
 async Task<string> Command(string command, bool allowDisconnect = false)
 {
     var address = (await Dns.GetHostAddressesAsync(Env("RCON_HOST", "zomboid"))).First(x => x.AddressFamily == System.Net.Sockets.AddressFamily.InterNetwork);
-    using var rcon = new RCON(address, ushort.Parse(Env("RCON_PORT", "27015")), rconPassword, strictCommandPacketIdMatching: false);
+    using var timeout = new CancellationTokenSource(10_000);
-    await rcon.ConnectAsync();
+    using var tcp = new TcpClient();
-    try { return await rcon.SendCommandAsync(command); }
+    await tcp.ConnectAsync(address, int.Parse(Env("RCON_PORT", "27015")), timeout.Token);
-    catch when (allowDisconnect && !rcon.Connected) { return ""; }
+    await using var stream = tcp.GetStream();
+    async Task Write(int id, int type, string body)
+    {
+        byte[] text = Encoding.UTF8.GetBytes(body), packet = new byte[text.Length + 14];
+        BinaryPrimitives.WriteInt32LittleEndian(packet, packet.Length - 4);
+        BinaryPrimitives.WriteInt32LittleEndian(packet.AsSpan(4), id);
+        BinaryPrimitives.WriteInt32LittleEndian(packet.AsSpan(8), type);
+        text.CopyTo(packet, 12);
+        await stream.WriteAsync(packet, timeout.Token);
+    }
+    async Task<(int Id, int Type, string Body)> Read()
+    {
+        byte[] header = new byte[4];
+        await stream.ReadExactlyAsync(header, timeout.Token);
+        int length = BinaryPrimitives.ReadInt32LittleEndian(header);
+        if (length is < 10 or > 1_048_576) throw new InvalidDataException("Invalid RCON packet");
+        byte[] packet = new byte[length];
+        await stream.ReadExactlyAsync(packet, timeout.Token);
+        return (BinaryPrimitives.ReadInt32LittleEndian(packet), BinaryPrimitives.ReadInt32LittleEndian(packet.AsSpan(4)),
+            Encoding.UTF8.GetString(packet, 8, length - 10));
+    }
+    await Write(1, 3, rconPassword);
+    (int Id, int Type, string Body) response;
+    do response = await Read(); while (response.Type != 2);
+    if (response.Id != 1) throw new UnauthorizedAccessException("RCON authentication failed");
+    await Write(2, 2, command);
+    try { do response = await Read(); while (response.Id != 2); return response.Body; }
+    catch (EndOfStreamException) when (allowDisconnect) { return ""; }
+    catch (IOException) when (allowDisconnect) { return ""; }
 }
 async Task<(int Count, string[] Names)> Players()
 {