Updated to C# 12

AMWD.Common.MessagePack/Formatters/IPAddressListFormatter.cs

@@ -0,0 +1,67 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net;
+using AMWD.Common.MessagePack.Utilities;
+
+namespace MessagePack.Formatters
+{
+	/// <summary>
+	/// Serialization of an <see cref="IPAddress"/> list to and from <see cref="MessagePack"/>.
+	/// </summary>
+	[System.Diagnostics.CodeAnalysis.ExcludeFromCodeCoverage]
+	public class IPAddressListFormatter : IMessagePackFormatter<List<IPAddress>>
+	{
+		/// <inheritdoc/>
+		public List<IPAddress> Deserialize(ref MessagePackReader reader, MessagePackSerializerOptions options)
+		{
+			if (reader.IsNil)
+				return null;
+
+			byte[] bytes = options.Resolver.GetFormatterWithVerify<byte[]>().Deserialize(ref reader, options);
+
+			// skipping the length information
+			int bytePos = sizeof(int);
+
+			var list = new List<IPAddress>();
+			while (bytePos < bytes.Length)
+			{
+				byte len = bytes.Skip(bytePos).First();
+				bytePos++;
+
+				byte[] buffer = bytes.Skip(bytePos).Take(len).ToArray();
+				bytePos += len;
+
+				list.Add(new IPAddress(buffer));
+			}
+
+			return list;
+		}
+
+		/// <inheritdoc/>
+		public void Serialize(ref MessagePackWriter writer, List<IPAddress> value, MessagePackSerializerOptions options)
+		{
+			if (value == null)
+			{
+				writer.WriteNil();
+				return;
+			}
+
+			var bytes = new List<byte>();
+
+			int length = value.Count;
+			byte[] buffer = BitConverter.GetBytes(length);
+			NetworkHelper.SwapBigEndian(buffer);
+			bytes.AddRange(buffer);
+
+			foreach (var ip in value)
+			{
+				buffer = ip.GetAddressBytes();
+				bytes.Add((byte)buffer.Length);
+				bytes.AddRange(buffer);
+			}
+
+			options.Resolver.GetFormatterWithVerify<byte[]>().Serialize(ref writer, [.. bytes], options);
+		}
+	}
+}