Kernel: Add a simple MACAddress class.

Kernel/E1000NetworkAdapter.cpp

@@ -57,7 +57,7 @@ E1000NetworkAdapter::E1000NetworkAdapter(PCI::Address pci_address, byte irq)
     detect_eeprom();
     kprintf("E1000: Has EEPROM? %u\n", m_has_eeprom);
     read_mac_address();
-    auto* mac = mac_address();
+    const auto& mac = mac_address();
     kprintf("E1000: MAC address: %b:%b:%b:%b:%b:%b\n", mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
     enable_irq();
 }

Kernel/MACAddress.h

@@ -0,0 +1,27 @@
+#pragma once
+
+#include <AK/Assertions.h>
+#include <AK/Types.h>
+#include <Kernel/StdLib.h>
+
+class MACAddress {
+public:
+    MACAddress() { }
+    MACAddress(const byte data[6])
+        : m_valid(true)
+    {
+        memcpy(m_data, data, 6);
+    }
+    ~MACAddress() { }
+
+    bool is_valid() const { return m_valid; }
+    byte operator[](int i) const
+    {
+        ASSERT(i >= 0 && i < 6);
+        return m_data[i];
+    }
+
+private:
+    byte m_data[6];
+    bool m_valid { false };
+};

Kernel/NetworkAdapter.cpp

@@ -10,7 +10,3 @@ NetworkAdapter::~NetworkAdapter()
 {
 }
 
-void NetworkAdapter::set_mac_address(const byte* mac_address)
-{
-    memcpy(m_mac_address, mac_address, 6);
-}

Kernel/NetworkAdapter.h

@@ -1,18 +1,19 @@
 #pragma once
 
 #include <AK/Types.h>
+#include <Kernel/MACAddress.h>
 
 class NetworkAdapter {
 public:
     virtual ~NetworkAdapter();
 
     virtual const char* class_name() const = 0;
-    const byte* mac_address() { return m_mac_address; }
+    MACAddress mac_address() { return m_mac_address; }
 
 protected:
     NetworkAdapter();
-    void set_mac_address(const byte*);
+    void set_mac_address(const MACAddress& mac_address) { m_mac_address = mac_address; }
 
 private:
-    byte m_mac_address[6];
+    MACAddress m_mac_address;
 };