Add protocol version param to HelloVerifyRequest and update DTLS handling

Author: TianMengLucky

Directory.Build.props

@@ -1,6 +1,6 @@
 <Project>
     <PropertyGroup>
-        <TargetFrameworks>net9.0;net6.0</TargetFrameworks>
+        <TargetFrameworks>net9.0;net8.0</TargetFrameworks>
         <LangVersion>latest</LangVersion>
         <Authors>Impostor,Next-Fast</Authors>
         <PackageLicenseExpression>MIT</PackageLicenseExpression>

Next.Hazel/Dtls/DtlsConnectionListener.cs

@@ -764,7 +764,7 @@ private async ValueTask<bool> HandleClientHello(PeerData peer, IPEndPoint peerAd
         }
 
         // Find an acceptable cipher suite we can use
-        var selectedCipherSuite = CipherSuite.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256;
+        const CipherSuite selectedCipherSuite = CipherSuite.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256;
         if (!clientHello.ContainsCipherSuite(CipherSuite.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) ||
             !clientHello.ContainsCurve(NamedCurve.x25519))
         {
@@ -787,7 +787,7 @@ private async ValueTask<bool> HandleClientHello(PeerData peer, IPEndPoint peerAd
                     recordProtection = peer.CurrentEpoch.RecordProtection;
                 }
 
-                await SendHelloVerifyRequest(peerAddress, outgoingSequence, record.Epoch, recordProtection);
+                await SendHelloVerifyRequest(peerAddress, outgoingSequence, record.Epoch, recordProtection, peer.ProtocolVersion);
                 return true;
             }
 
@@ -1132,7 +1132,7 @@ private async ValueTask HandleNonPeerRecord(ByteSpan message, IPEndPoint peerAdd
         if (!HelloVerifyRequest.VerifyCookie(clientHello.Cookie, peerAddress, currentCookieHmac))
             if (!HelloVerifyRequest.VerifyCookie(clientHello.Cookie, peerAddress, previousCookieHmac))
             {
-                await SendHelloVerifyRequest(peerAddress, 1, 0, NullRecordProtection.Instance);
+                await SendHelloVerifyRequest(peerAddress, 1, 0, NullRecordProtection.Instance, clientHello.ClientProtocolVersion);
                 return;
             }
 
@@ -1151,7 +1151,7 @@ private async ValueTask HandleNonPeerRecord(ByteSpan message, IPEndPoint peerAdd
 
     //Send a HelloVerifyRequest handshake message to a peer
     private ValueTask SendHelloVerifyRequest(IPEndPoint peerAddress, ulong recordSequence, ushort epoch,
-        IRecordProtection recordProtection)
+        IRecordProtection recordProtection, ProtocolVersion protocolVersion)
     {
         // Do we need to rotate the HMAC key?
         var now = DateTime.UtcNow;
@@ -1177,6 +1177,7 @@ private ValueTask SendHelloVerifyRequest(IPEndPoint peerAddress, ulong recordSeq
         var record = new Record
         {
             ContentType = ContentType.Handshake,
+            ProtocolVersion = protocolVersion,
             Epoch = epoch,
             SequenceNumber = recordSequence,
             Length = (ushort)recordProtection.GetEncryptedSize(plaintextPayloadSize)
@@ -1189,7 +1190,7 @@ private ValueTask SendHelloVerifyRequest(IPEndPoint peerAddress, ulong recordSeq
         writer = writer[Record.Size..];
         handshake.Encode(writer);
         writer = writer[Handshake.Handshake.Size..];
-        HelloVerifyRequest.Encode(writer, peerAddress, currentCookieHmac);
+        HelloVerifyRequest.Encode(writer, peerAddress, currentCookieHmac, protocolVersion);
 
         // Protect record payload
         recordProtection.EncryptServerPlaintext(

Next.Hazel/Dtls/Handshake/HelloVerifyRequest.cs

@@ -53,11 +53,12 @@ public static bool Parse(out HelloVerifyRequest result, ProtocolVersion? expecte
     /// <param name="span"></param>
     /// <param name="peerAddress">Address of the remote peer</param>
     /// <param name="hmac">Listener HMAC signature provider</param>
-    public static void Encode(ByteSpan span, EndPoint peerAddress, HMAC hmac)
+    /// <param name="protocolVersion"></param>
+    public static void Encode(ByteSpan span, EndPoint peerAddress, HMAC hmac, ProtocolVersion protocolVersion)
     {
         var cookie = ComputeAddressMac(peerAddress, hmac);
 
-        span.WriteBigEndian16((ushort)ProtocolVersion.DTLS1_2);
+        span.WriteBigEndian16((ushort)protocolVersion);
         span[2] = CookieSize;
         cookie.CopyTo(span[3..]);
     }

Next.Hazel/Dtls/Record.cs

@@ -93,9 +93,7 @@ public static bool Parse(ByteSpan span)
         if (span.Length != 1) return false;
 
         var value = (Value)span[0];
-        if (value != Value.ChangeCipherSpec) return false;
-
-        return true;
+        return value == Value.ChangeCipherSpec;
     }
 
     /// <summary>

Next.Hazel/Extensions/DefaultMessageWriterProvider.cs

@@ -0,0 +1,11 @@
+using Next.Hazel.Abstractions;
+
+namespace Next.Hazel.Extensions;
+
+public class DefaultMessageWriterProvider : IMessageWriterProvider
+{
+    public IMessageWriter Get(MessageType sendOption = MessageType.Unreliable)
+    {
+        return MessageWriter.Get(sendOption);
+    }
+}