fix: Fixes "writing past the end of the buffer" error when calling ResetDirty() on managed network variables that are larger than 256 bytes when serialized. (#2670)

Author: ShadauxCat

com.unity.netcode.gameobjects/CHANGELOG.md

@@ -6,6 +6,12 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 
 Additional documentation and release notes are available at [Multiplayer Documentation](https://docs-multiplayer.unity3d.com).
 
+## [Unreleased]
+
+### Fixed
+
+- Fixed "writing past the end of the buffer" error when calling ResetDirty() on managed network variables that are larger than 256 bytes when serialized.
+
 ## [1.5.2] - 2023-07-24
 
 ### Added

com.unity.netcode.gameobjects/Runtime/NetworkVariable/NetworkVariable.cs

@@ -146,8 +146,11 @@ public override void ResetDirty()
             // Therefore, we set the m_PreviousValue field to a duplicate of the current
             // field, so that our next dirty check is made against the current "not dirty"
             // value.
-            m_HasPreviousValue = true;
-            NetworkVariableSerialization<T>.Serializer.Duplicate(m_InternalValue, ref m_PreviousValue);
+            if (!m_HasPreviousValue || !NetworkVariableSerialization<T>.AreEqual(ref m_InternalValue, ref m_PreviousValue))
+            {
+                m_HasPreviousValue = true;
+                NetworkVariableSerialization<T>.Serializer.Duplicate(m_InternalValue, ref m_PreviousValue);
+            }
         }
 
         /// <summary>

com.unity.netcode.gameobjects/Runtime/NetworkVariable/NetworkVariableSerialization.cs

@@ -514,7 +514,7 @@ void INetworkVariableSerializer<T>.ReadWithAllocator(FastBufferReader reader, ou
 
         public void Duplicate(in T value, ref T duplicatedValue)
         {
-            using var writer = new FastBufferWriter(256, Allocator.Temp);
+            using var writer = new FastBufferWriter(256, Allocator.Temp, int.MaxValue);
             var refValue = value;
             Write(writer, ref refValue);