First draft

mobile/src/main/java/be/mygod/vpnhotspot/net/MacAddressCompat.kt

@@ -1,14 +1,17 @@
 package be.mygod.vpnhotspot.net
 
 import android.net.MacAddress
+import android.os.Parcelable
 import androidx.annotation.RequiresApi
+import kotlinx.android.parcel.Parcelize
 import java.nio.ByteBuffer
 import java.nio.ByteOrder
 
 /**
  * Compat support class for [MacAddress].
  */
-inline class MacAddressCompat(val addr: Long) {
+@Parcelize
+inline class MacAddressCompat(val addr: Long) : Parcelable {
     companion object {
         private const val ETHER_ADDR_LEN = 6
         /**
@@ -28,17 +31,44 @@ inline class MacAddressCompat(val addr: Long) {
             return addr.joinToString(":") { "%02x".format(it) }
         }
 
-        fun fromString(addr: String) = MacAddressCompat(ByteBuffer.allocate(8).run {
+        /**
+         * Creates a MacAddress from the given byte array representation.
+         * A valid byte array representation for a MacAddress is a non-null array of length 6.
+         *
+         * @param addr a byte array representation of a MAC address.
+         * @return the MacAddress corresponding to the given byte array representation.
+         * @throws IllegalArgumentException if the given byte array is not a valid representation.
+         */
+        fun fromBytes(addr: ByteArray): MacAddressCompat {
+            require(addr.size == ETHER_ADDR_LEN) { addr.joinToString() + " was not a valid MAC address" }
+            return ByteBuffer.allocate(Long.SIZE_BYTES).run {
+                put(addr)
+                rewind()
+                MacAddressCompat(long)
+            }
+        }
+        /**
+         * Creates a MacAddress from the given String representation. A valid String representation
+         * for a MacAddress is a series of 6 values in the range [0,ff] printed in hexadecimal
+         * and joined by ':' characters.
+         *
+         * @param addr a String representation of a MAC address.
+         * @return the MacAddress corresponding to the given String representation.
+         * @throws IllegalArgumentException if the given String is not a valid representation.
+         */
+        fun fromString(addr: String) = ByteBuffer.allocate(Long.SIZE_BYTES).run {
             order(ByteOrder.LITTLE_ENDIAN)
-            mark()
             try {
                 put(addr.split(':').map { Integer.parseInt(it, 16).toByte() }.toByteArray())
             } catch (e: NumberFormatException) {
                 throw IllegalArgumentException(e)
             }
-            reset()
-            long
-        })
+            rewind()
+            MacAddressCompat(long)
+        }
+
+        @RequiresApi(28)
+        fun MacAddress.toCompat() = fromBytes(toByteArray())
     }
 
     fun toList() = ByteBuffer.allocate(8).run {