Refactor DHCP to implement DHCP and DHCPv6. Implement most DHCPv6 options.

src/IPMeow.Dhcp/IPMeow.Dhcp.csproj

@@ -1,10 +1,11 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
-  <ItemGroup>
-    <ProjectReference Include="..\IPMeow.Lib\IPMeow.Lib.csproj" />
+  <ItemGroup>
+    <ProjectReference Include="..\IPMeow.Lib\IPMeow.Lib.csproj" />
   </ItemGroup>
 
   <PropertyGroup>
+    <OutputType>Exe</OutputType>
     <TargetFramework>net7.0</TargetFramework>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>

src/IPMeow.Dhcp/Program.cs

@@ -0,0 +1,16 @@
+using IPMeow.Dhcp.Server;
+using IPMeow.Dhcp.Server.Dhcp4;
+
+namespace IPMeow.Dhcp
+{
+    public static class Program
+    {
+        public static async Task Main(string[] args)
+        {
+            Console.WriteLine("Listening on DHCP...");
+            var dhcp = new DhcpServer();
+
+            await dhcp.Run();
+        }
+    }
+}

src/IPMeow.Dhcp/Server/AddressAssociation.cs

@@ -0,0 +1,15 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net;
+using System.Threading.Tasks;
+
+namespace IPMeow.Dhcp.Server;
+
+public readonly struct AddressAssociation
+{
+    public IPAddress Address { get; }
+    public int PreferredLifetime { get; }
+    public int ValidLifetime { get; }
+
+}

src/IPMeow.Dhcp/Server/Dhcp4/DhcpFields.cs

@@ -1,4 +1,4 @@
-namespace IPMeow.Dhcp.Server;
+namespace IPMeow.Dhcp.Server.Dhcp4;
 
 public enum DhcpMessageType
 {

src/IPMeow.Dhcp/Server/Dhcp4/DhcpPacket.cs

@@ -0,0 +1,135 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net;
+using System.Net.NetworkInformation;
+using System.Text;
+using System.Threading.Tasks;
+using IPMeow.Lib;
+
+namespace IPMeow.Dhcp.Server.Dhcp4;
+
+public class DhcpPacket
+{
+    public required DhcpOpType OpType { get; init; }
+    public required byte HType { get; init; }
+    public required byte HLen { get; init; }
+    public required byte Hops { get; init; }
+    public required uint Xid { get; init; }
+    public required short Seconds { get; init; }
+    public required short Flags { get; init; }
+    public required IPAddress ClientAddress { get; init; }
+    public required IPAddress YourAddress { get; init; }
+    public required IPAddress NextServerAddress { get; init; }
+    public required IPAddress RelayAgentAddress { get; init; }
+    public required byte[] ClientHWAddress { get; init; }
+    public required string ServerHostName { get; init; }
+    public required string BootFileName { get; init; }
+    public bool? IsValidated { get; set; }
+
+    public byte[] GetClientHwAddress()
+    {
+        int padLen = 16 - ClientHWAddress.Length;
+
+        if (padLen == 16)
+        {
+            return ClientHWAddress;
+        }
+
+        var buf = new byte[16];
+        ClientHWAddress.CopyTo(buf, 0);
+        return buf;
+    }
+
+    public byte[] GetSnameBytes()
+    {
+        var buf = new byte[64];
+        if (!string.IsNullOrWhiteSpace(ServerHostName))
+        {
+            Encoding.UTF8.GetBytes(ServerHostName).CopyTo(buf, 0);
+        }
+
+        return buf;
+    }
+
+    public byte[] GetBootFileBytes()
+    {
+        var buf = new byte[128];
+        if (!string.IsNullOrWhiteSpace(BootFileName))
+        {
+            Encoding.UTF8.GetBytes(BootFileName).CopyTo(buf, 0);
+        }
+
+        return buf;
+    }
+
+    public static DhcpPacket Deserialize(byte[] data)
+    {
+        BitEnumerator enu = new(data);
+
+        if (data.Length < 236 || data.Length > 576)
+        {
+            throw new ArgumentException("Invalid datagram.");
+        }
+
+        var OpType = (DhcpOpType)enu.TakeByte();
+
+        var HType = enu.TakeByte();
+        var HLen = enu.TakeByte();
+        var Hops = enu.TakeByte();
+        var Xid = enu.TakeUInt32();
+        var Seconds = enu.TakeInt16();
+        var Flags = enu.TakeInt16();
+        var ClientAddress = new IPAddress(enu.TakeBytes(4));
+        var YourAddress = new IPAddress(enu.TakeBytes(4));
+        var NextServerAddress = new IPAddress(enu.TakeBytes(4));
+        var RelayAgentAddress = new IPAddress(enu.TakeBytes(4));
+        byte[] chaddr = enu.TakeBytes(16);
+        byte[] sname = enu.TakeBytes(64);
+        byte[] file = enu.TakeBytes(128);
+
+        var BootFileName = Encoding.UTF8.GetString(file.TakeWhile(x => x != 0).ToArray());
+        var ServerHostName = Encoding.UTF8.GetString(sname.TakeWhile(x => x != 0).ToArray());
+
+        return new()
+        {
+            OpType = OpType,
+            HType = HType,
+            HLen = HLen,
+            Hops = Hops,
+            Xid = Xid,
+            Seconds = Seconds,
+            Flags = Flags,
+            ClientAddress = ClientAddress,
+            YourAddress = YourAddress,
+            NextServerAddress = NextServerAddress,
+            RelayAgentAddress = RelayAgentAddress,
+            ClientHWAddress = chaddr,
+            ServerHostName = ServerHostName,
+            BootFileName = BootFileName
+        };
+    }
+
+    public byte[] Serialize()
+    {
+        using MemoryStream buffer = new();
+        BinaryWriter writer = new(buffer);
+
+        writer.Write((byte)OpType);
+        writer.Write(HType);
+        writer.Write(HLen);
+        writer.Write(Hops);
+        writer.Write(Xid);
+        writer.Write(Seconds);
+        writer.Write(Flags);
+        writer.Write(ClientAddress.GetAddressBytes());
+        writer.Write(YourAddress.GetAddressBytes());
+        writer.Write(NextServerAddress.GetAddressBytes());
+        writer.Write(RelayAgentAddress.GetAddressBytes());
+        writer.Write(GetClientHwAddress());
+        writer.Write(GetSnameBytes());
+        writer.Write(GetBootFileBytes());
+
+        return buffer.GetBuffer();
+    }
+}

src/IPMeow.Dhcp/Server/Dhcp4/DhcpServer.cs

@@ -0,0 +1,75 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net;
+using System.Net.Sockets;
+using System.Threading.Tasks;
+
+namespace IPMeow.Dhcp.Server.Dhcp4;
+
+public class DhcpServer
+{
+    public const int clientPort = 68, serverPort = 67;
+
+    public DhcpServer()
+    {
+        _udp = new UdpClient(serverPort, AddressFamily.InterNetwork);
+    }
+
+    public async Task Run()
+    {
+        while (true)
+        {
+            await Receive();
+        }
+    }
+
+    protected async Task Receive()
+    {
+        var datagram = await _udp.ReceiveAsync();
+
+        if (datagram.Buffer.Length < 236 || datagram.Buffer.Length > 576)
+        {
+            return;
+        }
+
+        var packet = DhcpPacket.Deserialize(datagram.Buffer);
+        packet.IsValidated = ValidateIncoming(packet);
+
+        if (!packet.IsValidated.Value)
+        {
+            return;
+        }
+
+
+
+        Console.WriteLine("Solicitation: ");
+        Console.WriteLine(packet.ToString());
+    }
+
+    public bool ValidateIncoming(DhcpPacket packet)
+    {
+        if (packet.OpType != DhcpOpType.BOOTREQUEST)
+        {
+            return false;
+        }
+
+        //Discard unsupported
+        bool supported = packet.HLen == 6 && packet.HType == 1;
+
+        if (!supported)
+        {
+            return false;
+        }
+
+        if (packet.NextServerAddress != IPAddress.Any)
+        {
+            return false;
+        }
+
+
+        return true;
+    }
+
+    private readonly UdpClient _udp;
+}

src/IPMeow.Dhcp/Server/Dhcp6/DhcpFields.cs

@@ -0,0 +1,24 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace IPMeow.Dhcp.Server.Dhcp6;
+
+public enum DhcpMessageType : byte
+{
+    Invalid = 0,
+    Solicit = 1,
+    Advertise = 2,
+    Request = 3,
+    Confirm = 4,
+    Renew = 5,
+    Rebind = 6,
+    Reply = 7,
+    Release = 8,
+    Decline = 9,
+    Reconfigure = 10,
+    InfoRequest = 11,
+    RelayForw = 12,
+    RelayRepl = 13
+}

src/IPMeow.Dhcp/Server/Dhcp6/DhcpOption.cs

@@ -0,0 +1,161 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace IPMeow.Dhcp.Server.Dhcp6;
+
+public enum DhcpOptionCode : short
+{
+    ClientId = 1,
+    ServerId = 2,
+    IANonTempAssoc = 3,
+    IATempAssoc = 4,
+    IAAddr = 5,
+    OptionRequest = 6,
+    Preference = 7,
+    ElapsedTime = 8,
+    ServerUnicast = 12,
+    StatusCode = 13,
+
+
+}
+
+public interface IDhcpOption
+{
+    public DhcpOptionCode Code { get; }
+    public byte[] Data { get; set; }
+    public Type DataType { get; }
+    public abstract object GetData();
+}
+
+public class ClientIdentifierOption : IDhcpOption
+{
+    public DhcpOptionCode Code => DhcpOptionCode.ClientId;
+
+    public required byte[] Data { get; set; }
+
+    public Type DataType => typeof(Duid);
+
+    public object GetData()
+    {
+        return new Duid(Data);
+    }
+}
+
+public class ServerIdentifierOption : IDhcpOption
+{
+    public DhcpOptionCode Code => DhcpOptionCode.ServerId;
+
+    public required byte[] Data { get; set; }
+
+    public Type DataType => typeof(Duid);
+
+    public object GetData()
+    {
+        return new Duid(Data);
+    }
+}
+
+public class NonTempIdentityAssociationOption : IDhcpOption
+{
+    public DhcpOptionCode Code => DhcpOptionCode.IANonTempAssoc;
+
+    public required byte[] Data { get; set; }
+
+    public Type DataType => typeof(IdentityAssociation);
+
+    public object GetData()
+    {
+        throw new NotImplementedException();
+    }
+}
+
+public class TempIdentityAssociationOption : IDhcpOption
+{
+    public DhcpOptionCode Code => DhcpOptionCode.IATempAssoc;
+
+    public required byte[] Data { get; set; }
+
+    public Type DataType => typeof(IdentityAssociation);
+
+    public object GetData()
+    {
+        throw new NotImplementedException();
+    }
+}
+
+public class IAAddressOption : IDhcpOption
+{
+    public DhcpOptionCode Code => DhcpOptionCode.IAAddr;
+
+    public required byte[] Data { get; set; }
+
+    public Type DataType => typeof(AddressAssociation);
+
+    public object GetData()
+    {
+        throw new NotImplementedException();
+    }
+}
+
+public class OptionRequestOption : IDhcpOption
+{
+    public DhcpOptionCode Code => DhcpOptionCode.OptionRequest;
+
+    public required byte[] Data { get; set; }
+
+    public Type DataType => typeof(ICollection<DhcpOptionCode>);
+
+    public object GetData()
+    {
+        throw new NotImplementedException();
+    }
+}
+
+public class ElapsedTimeOption : IDhcpOption
+{
+    public DhcpOptionCode Code => DhcpOptionCode.ElapsedTime;
+
+    public required byte[] Data { get; set; }
+
+    public Type DataType => typeof(TimeSpan);
+
+    public object GetData()
+    {
+        return TimeSpan.FromSeconds(BitConverter.ToInt16(Data, 0));
+    }
+}
+
+public class ServerUnicastOption : IDhcpOption
+{
+    public DhcpOptionCode Code => DhcpOptionCode.ServerUnicast;
+    public required byte[] Data { get; set; }
+
+    public Type DataType => typeof(IPAddress);
+
+    public object GetData()
+    {
+        return new IPAddress(Data);
+    }
+}
+
+public class StatusCodeOption : IDhcpOption
+{
+    public DhcpOptionCode Code => DhcpOptionCode.StatusCode;
+
+    public required byte[] Data { get; set; }
+
+    public Type DataType => typeof(DhcpStatus);
+
+    public object GetData()
+    {
+        ushort code = BitConverter.ToUInt16(Data.AsSpan()[..2]);
+
+        string? message = Data.Length > 2 ? Encoding.UTF8.GetString(Data.AsSpan()[2..]) : null;
+
+        return new DhcpStatus(code, message);
+    }
+}

src/IPMeow.Dhcp/Server/Dhcp6/DhcpPacket.cs

@@ -0,0 +1,66 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+using IPMeow.Lib;
+
+namespace IPMeow.Dhcp.Server.Dhcp6;
+
+public class DhcpPacket
+{
+    public required DhcpMessageType MessageType { get; init; }
+    public required uint Xid { get; init; }
+    public ICollection<IDhcpOption> Options { get; init; } = new List<IDhcpOption>();
+
+    public static IDhcpOption GetOption(DhcpOptionCode type, byte[] data)
+    {
+        return type switch
+        {
+            DhcpOptionCode.ClientId => new ClientIdentifierOption()
+            {
+                Data = data
+            },
+            DhcpOptionCode.ServerId => throw new NotImplementedException(),
+            DhcpOptionCode.IANonTempAssoc => throw new NotImplementedException(),
+            DhcpOptionCode.IATempAssoc => throw new NotImplementedException(),
+            DhcpOptionCode.IAAddr => throw new NotImplementedException(),
+            DhcpOptionCode.OptionRequest => throw new NotImplementedException(),
+            DhcpOptionCode.Preference => throw new NotImplementedException(),
+            DhcpOptionCode.ElapsedTime => throw new NotImplementedException(),
+            DhcpOptionCode.StatusCode => throw new NotImplementedException(),
+            _ => throw new InvalidOperationException($"Invalid option type {type}")
+        };
+    }
+
+    public static DhcpPacket Deserialize(byte[] data)
+    {
+        BitEnumerator enu = new(data);
+
+        byte[] header = enu.TakeBytes(4);
+
+        DhcpMessageType MessageType = (DhcpMessageType)header[0];
+
+        uint Xid = BitConverter.ToUInt32(header, 1);
+
+        while (enu.Position < data.Length)
+        {
+            short optionCode = enu.TakeInt16();
+            short optionLen = enu.TakeInt16();
+
+            if (enu.Position + optionLen > data.Length)
+            {
+                throw new DataMisalignedException("Invalid option length.");
+            }
+
+            byte[] optionData = enu.TakeBytes(optionLen);
+
+
+        }
+
+        return new()
+        {
+            MessageType = MessageType,
+            Xid = Xid
+        };
+    }
+}

src/IPMeow.Dhcp/Server/Dhcp6/DhcpServer.cs

@@ -0,0 +1,49 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net;
+using System.Net.Sockets;
+using System.Threading.Tasks;
+using IPMeow.Dhcp.Server.Dhcp4;
+
+namespace IPMeow.Dhcp.Server.Dhcp6;
+
+public class DhcpServer : IDhcpServer, IDisposable
+{
+    public const int clientPort = 546, serverPort = 547;
+
+    public DhcpServer()
+    {
+        _listener = new(new IPEndPoint(IPAddress.Parse("ff02::1:2"), serverPort));
+        _sender = new(clientPort, AddressFamily.InterNetworkV6);
+    }
+    private UdpClient _listener, _sender;
+
+    public void Dispose()
+    {
+        GC.SuppressFinalize(this);
+        _listener.Dispose();
+        _sender.Dispose();
+    }
+
+    public async Task Run()
+    {
+        while (true)
+        {
+            await Receive();
+        }
+    }
+
+    protected async Task Receive()
+    {
+        var datagram = await _listener.ReceiveAsync();
+
+        var packet = DhcpPacket.Deserialize(datagram.Buffer);
+
+        if (packet.MessageType is DhcpMessageType.Invalid or DhcpMessageType.Solicit or DhcpMessageType.Confirm or DhcpMessageType.Rebind)
+        {
+            return;
+        }
+
+    }
+}

src/IPMeow.Dhcp/Server/Dhcp6/DhcpStatus.cs

@@ -0,0 +1,47 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace IPMeow.Dhcp.Server.Dhcp6;
+
+public struct DhcpStatus
+{
+    public DhcpStatus(ushort code, string? message)
+    {
+        Code = code;
+        Message = message;
+    }
+
+    public static DhcpStatus? TryParse(byte[] data)
+    {
+        if (data.Length < 2)
+        {
+            return null;
+        }
+
+        ushort code = BitConverter.ToUInt16(data.AsSpan()[..2]);
+        string? message = data.Length > 2 ? Encoding.UTF8.GetString(data.AsSpan()[2..]) : null;
+
+        return new(code, message);
+    }
+
+    public ushort Code { get; set; }
+    public string? Message { get; set; }
+
+    public byte[] Serialize()
+    {
+        byte[] buf = new byte[2 + Message?.Length ?? 0];
+
+        buf[0] = (byte)((Code & 0xff00) >> 8);
+        buf[1] = (byte)(Code & 0x00ff);
+
+        if (Message is not null)
+        {
+            Encoding.UTF8.GetBytes(Message).CopyTo(buf, 2);
+        }
+
+        return buf;
+    }
+}

src/IPMeow.Dhcp/Server/Dhcp6/Duid.cs

@@ -0,0 +1,26 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace IPMeow.Dhcp.Server.Dhcp6;
+
+public enum DuidType : short
+{
+    LLAddrWithTime = 1,
+    VendorUID = 2,
+    LLAddr = 3,
+    Uuid = 4
+}
+
+public readonly struct Duid
+{
+    public Duid(byte[] data)
+    {
+        Type = (DuidType)BitConverter.ToInt16(data.AsSpan()[0..2]);
+        Data = data[2..];
+    }
+
+    public DuidType Type { get; }
+    public byte[] Data { get; }
+}

src/IPMeow.Dhcp/Server/Dhcp6/IdentityAssociation.cs

@@ -0,0 +1,13 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace IPMeow.Dhcp.Server.Dhcp6;
+
+public struct IdentityAssociation
+{
+    public int IAId { get; }
+    public int TimeToRefresh { get; }
+    public int TimeToNextAdvertise { get; } //T2 in RFC8415, 21.4
+}

src/IPMeow.Dhcp/Server/DhcpPacket.cs

@@ -1,38 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Net;
-using System.Threading.Tasks;
-using IPMeow.Lib;
-
-namespace IPMeow.Dhcp.Server;
-
-public class DhcpPacket
-{
-    public DhcpPacket(byte[] data)
-    {
-        BitEnumerator enu = new(data);
-
-        DhcpOpType opType = (DhcpOpType)enu.TakeByte();
-
-        byte hType = enu.TakeByte();
-        byte hLen = enu.TakeByte();
-        byte hOps = enu.TakeByte();
-
-        uint xid = enu.TakeUInt32();
-
-        short secs = enu.TakeInt16();
-
-        short flags = enu.TakeInt16();
-
-        IPAddress ciaddr = new(enu.TakeBytes(4));
-        IPAddress yiaddr = new(enu.TakeBytes(4));
-        IPAddress siaddr = new(enu.TakeBytes(4));
-        IPAddress giaddr = new(enu.TakeBytes(4));
-
-        byte[] chaddr = enu.TakeBytes(16);
-
-        byte[] sname = enu.TakeBytes(64);
-        byte[] file = enu.TakeBytes(128);
-    }
-}

src/IPMeow.Dhcp/Server/IDhcpServer.cs

@@ -0,0 +1,11 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace IPMeow.Dhcp.Server;
+
+public interface IDhcpServer
+{
+    public Task Run();
+}