made the ethernet header fields accessible and added some tests for e…

…thernet header

packetdumper/src/main/kotlin/com/jasonernst/packetdumper/ethernet/EthernetHeader.kt

@@ -11,9 +11,9 @@ import java.nio.ByteBuffer
  * https://en.wikipedia.org/wiki/Ethernet_frame
  */
 class EthernetHeader(
-    private var destination: MacAddress,
-    private var source: MacAddress,
-    private var type: EtherType,
+    val destination: MacAddress,
+    val source: MacAddress,
+    val type: EtherType,
 ) {
     companion object {
         const val IP4_VERSION: UByte = 4u
@@ -90,4 +90,22 @@ class EthernetHeader(
     }
 
     override fun toString(): String = "EthernetHeader(destination=$destination, source=$source, type=$type, size=${size()})"
+
+    override fun equals(other: Any?): Boolean {
+        if (this === other) return true
+        if (other !is EthernetHeader) return false
+
+        if (destination != other.destination) return false
+        if (source != other.source) return false
+        if (type != other.type) return false
+
+        return true
+    }
+
+    override fun hashCode(): Int {
+        var result = destination.hashCode()
+        result = 31 * result + source.hashCode()
+        result = 31 * result + type.hashCode()
+        return result
+    }
 }

packetdumper/src/main/kotlin/com/jasonernst/packetdumper/ethernet/MacAddress.kt

@@ -35,4 +35,17 @@ class MacAddress {
         val DUMMY_MAC_SOURCE = MacAddress("14:c0:3e:55:0b:35")
         val DUMMY_MAC_DEST = MacAddress("74:d0:2b:29:a5:18")
     }
+
+    override fun equals(other: Any?): Boolean {
+        if (this === other) return true
+        if (other == null || this::class != other::class) return false
+
+        other as MacAddress
+
+        return bytes.contentEquals(other.bytes)
+    }
+
+    override fun hashCode(): Int {
+        return bytes.contentHashCode()
+    }
 }

packetdumper/src/test/kotlin/com/jasonernst/packetdumper/ethernet/TestEthernetHeader.kt

@@ -0,0 +1,32 @@
+package com.jasonernst.packetdumper.ethernet
+
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
+import java.nio.ByteBuffer
+
+class TestEthernetHeader {
+    @Test fun serialization() {
+        val header = EthernetHeader.dummyEthernet(EtherType.IPv4)
+        val buffer = ByteBuffer.wrap(header.toBytes())
+        val parsedHeader = EthernetHeader.fromStream(buffer)
+        assertEquals(header, parsedHeader)
+        assertEquals(parsedHeader.size(), EthernetHeader.ETHERNET_HEADER_LENGTH)
+    }
+
+    @Test fun etherTypeDetection() {
+        val ipv4Buffer = ByteBuffer.allocate(1)
+        ipv4Buffer.put(0, EthernetHeader.IP4_VERSION.toByte())
+        ipv4Buffer.rewind()
+        assertEquals(EtherType.IPv4, EthernetHeader.getEtherTypeFromIPVersionByte(ipv4Buffer.get().toUByte()))
+
+        val ipv6Buffer = ByteBuffer.allocate(1)
+        ipv6Buffer.put(0, EthernetHeader.IP6_VERSION.toByte())
+        ipv6Buffer.rewind()
+        assertEquals(EtherType.IPv6, EthernetHeader.getEtherTypeFromIPVersionByte(ipv6Buffer.get().toUByte()))
+
+        val unknownBuffer = ByteBuffer.allocate(1)
+        unknownBuffer.put(0, 0.toByte())
+        unknownBuffer.rewind()
+        assertEquals(EtherType.DETECT, EthernetHeader.getEtherTypeFromIPVersionByte(unknownBuffer.get().toUByte()))
+    }
+}