feat(Core/Packets): Port packet handling from TrinityCore (#5617)

* feat(Core/Packets): Port packet handling from TrinityCore

* 1

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* 3

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* #3670

* 3

* 1

* codestyle

* fix msvc warnings

src/common/Utilities/MessageBuffer.h

@@ -0,0 +1,128 @@
+/*
+ * Copyright (C) 2016+ AzerothCore <www.azerothcore.org>, released under GNU AGPL v3 license: https://github.com/azerothcore/azerothcore-wotlk/blob/master/LICENSE-AGPL3
+ * Copyright (C) 2021+ WarheadCore <https://github.com/WarheadCore>
+ */
+
+#ifndef __MESSAGEBUFFER_H_
+#define __MESSAGEBUFFER_H_
+
+#include "Define.h"
+#include <vector>
+#include <cstring>
+
+class MessageBuffer
+{
+    using size_type = std::vector<uint8>::size_type;
+
+public:
+    MessageBuffer() : _wpos(0), _rpos(0), _storage()
+    {
+        _storage.resize(4096);
+    }
+
+    explicit MessageBuffer(std::size_t initialSize) : _wpos(0), _rpos(0), _storage()
+    {
+        _storage.resize(initialSize);
+    }
+
+    MessageBuffer(MessageBuffer const& right) :
+        _wpos(right._wpos), _rpos(right._rpos), _storage(right._storage) { }
+
+    MessageBuffer(MessageBuffer&& right) noexcept :
+        _wpos(right._wpos), _rpos(right._rpos), _storage(right.Move()) { }
+
+    void Reset()
+    {
+        _wpos = 0;
+        _rpos = 0;
+    }
+
+    void Resize(size_type bytes)
+    {
+        _storage.resize(bytes);
+    }
+
+    uint8* GetBasePointer() { return _storage.data(); }
+    uint8* GetReadPointer() { return GetBasePointer() + _rpos; }
+    uint8* GetWritePointer() { return GetBasePointer() + _wpos; }
+
+    void ReadCompleted(size_type bytes) { _rpos += bytes; }
+    void WriteCompleted(size_type bytes) { _wpos += bytes; }
+
+    [[nodiscard]] size_type GetActiveSize() const { return _wpos - _rpos; }
+    [[nodiscard]] size_type GetRemainingSpace() const { return _storage.size() - _wpos; }
+    [[nodiscard]] size_type GetBufferSize() const { return _storage.size(); }
+
+    // Discards inactive data
+    void Normalize()
+    {
+        if (_rpos)
+        {
+            if (_rpos != _wpos)
+            {
+                memmove(GetBasePointer(), GetReadPointer(), GetActiveSize());
+            }
+
+            _wpos -= _rpos;
+            _rpos = 0;
+        }
+    }
+
+    // Ensures there's "some" free space, make sure to call Normalize() before this
+    void EnsureFreeSpace()
+    {
+        // resize buffer if it's already full
+        if (GetRemainingSpace() == 0)
+        {
+            _storage.resize(_storage.size() * 3 / 2);
+        }
+    }
+
+    void Write(void const* data, std::size_t size)
+    {
+        if (size)
+        {
+            memcpy(GetWritePointer(), data, size);
+            WriteCompleted(size);
+        }
+    }
+
+    std::vector<uint8>&& Move()
+    {
+        _wpos = 0;
+        _rpos = 0;
+
+        return std::move(_storage);
+    }
+
+    MessageBuffer& operator=(MessageBuffer const& right)
+    {
+        if (this != &right)
+        {
+            _wpos = right._wpos;
+            _rpos = right._rpos;
+            _storage = right._storage;
+        }
+
+        return *this;
+    }
+
+    MessageBuffer& operator=(MessageBuffer&& right) noexcept
+    {
+        if (this != &right)
+        {
+            _wpos = right._wpos;
+            _rpos = right._rpos;
+            _storage = right.Move();
+        }
+
+        return *this;
+    }
+
+private:
+    size_type _wpos;
+    size_type _rpos;
+    std::vector<uint8> _storage;
+};
+
+#endif /* __MESSAGEBUFFER_H_ */