Removed MD5 for creating Message-IDs and rewrote MessageIdSupplier lo…

…gic (#52)

CHANGELOG.md

@@ -9,6 +9,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Add poolMaxIdleTime configuration option to TCP appenders
   [\#49](https://github.com/osiegmar/logback-gelf/pull/49)
 
+### Changed
+- Removed MD5 for creating Message-IDs and rewrote MessageIdSupplier logic (#52)
+  [\#52](https://github.com/osiegmar/logback-gelf/issues/52)
+
 ## [3.0.0] - 2020-03-15
 ### Added
 - Allow encoder subclasses to customize the message before it is converted to String.

src/main/java/de/siegmar/logbackgelf/GelfUdpChunker.java

@@ -93,7 +93,7 @@ class GelfUdpChunker {
         this.maxChunkPayloadSize = mcs - HEADER_LENGTH;
     }
 
-    private static ByteBuffer buildChunk(final byte[] messageId, final byte[] message,
+    private static ByteBuffer buildChunk(final long messageId, final byte[] message,
                                          final byte chunkCount, final byte chunkNo,
                                          final int maxChunkPayloadSize) {
 
@@ -106,7 +106,7 @@ private static ByteBuffer buildChunk(final byte[] messageId, final byte[] messag
         byteBuffer.put(CHUNKED_GELF_HEADER);
 
         // Message ID 8 bytes
-        byteBuffer.put(messageId);
+        byteBuffer.putLong(messageId);
 
         // Sequence number 1 byte
         byteBuffer.put(chunkNo);
@@ -131,7 +131,7 @@ private final class ChunkIterator implements Iterator<ByteBuffer> {
         private final byte[] message;
         private final int chunkSize;
         private final byte chunkCount;
-        private final byte[] messageId;
+        private final long messageId;
 
         private byte chunkIdx;
 
@@ -156,7 +156,7 @@ private ChunkIterator(final byte[] message) {
             this.chunkSize = localChunkSize;
             this.chunkCount = (byte) localChunkCount;
 
-            messageId = localChunkCount > 1 ? messageIdSupplier.get() : null;
+            messageId = localChunkCount > 1 ? messageIdSupplier.get() : 0;
         }
 
         private int calcChunkCount(final byte[] msg, final int cs) {

src/main/java/de/siegmar/logbackgelf/MessageIdSupplier.java

@@ -19,55 +19,29 @@
 
 package de.siegmar.logbackgelf;
 
-import java.net.InetAddress;
-import java.net.UnknownHostException;
-import java.nio.ByteBuffer;
-import java.security.MessageDigest;
-import java.security.NoSuchAlgorithmException;
-import java.util.Arrays;
 import java.util.Random;
 
+/**
+ * Supplier implementation for GELF message IDs as used for UDP chunks. Unfortunately the GELF
+ * protocol limits the message id length to 8 bytes thus an UUID cannot be used (16 bytes).
+ */
 public class MessageIdSupplier {
 
-    protected static final int MESSAGE_ID_LENGTH = 8;
-    protected static final int LONG_LENGTH = 8;
-    private byte[] machinePart;
-
-    public MessageIdSupplier() {
-        try {
-            machinePart = InetAddress.getLocalHost().getAddress();
-        } catch (final UnknownHostException e) {
-            machinePart = new byte[LONG_LENGTH];
-            new Random().nextBytes(machinePart);
-        }
-    }
-
-    protected byte[] getMachinePart() {
-        return Arrays.copyOf(machinePart, machinePart.length);
-    }
-
-    protected void setMachinePart(final byte[] machinePart) {
-        this.machinePart = Arrays.copyOf(machinePart, machinePart.length);
-    }
+    // static random to keep Spotbugs happy
+    private static final Random RANDOM = new Random();
+    private int machinePart = RANDOM.nextInt();
 
-    public byte[] get() {
-        return Arrays.copyOf(buildMessageId(), MESSAGE_ID_LENGTH);
+    public int getMachinePart() {
+        return machinePart;
     }
 
-    protected byte[] buildMessageId() {
-        final ByteBuffer bb = ByteBuffer.allocate(machinePart.length + LONG_LENGTH);
-        bb.put(machinePart);
-        bb.putLong(System.nanoTime());
-        bb.flip();
-        return md5(bb.array());
+    public void setMachinePart(final int machinePart) {
+        this.machinePart = machinePart;
     }
 
-    protected static byte[] md5(final byte[] data) {
-        try {
-            return MessageDigest.getInstance("MD5").digest(data);
-        } catch (final NoSuchAlgorithmException e) {
-            throw new IllegalStateException(e);
-        }
+    @SuppressWarnings("checkstyle:magicnumber")
+    public Long get() {
+        return (long) machinePart << 32 | System.nanoTime() & 0xffffffffL;
     }
 
 }

src/test/java/de/siegmar/logbackgelf/MessageIdSupplierTest.java

@@ -19,23 +19,18 @@
 
 package de.siegmar.logbackgelf;
 
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertFalse;
-
-import java.util.Arrays;
+import static org.junit.jupiter.api.Assertions.assertNotEquals;
 
 import org.junit.jupiter.api.Test;
 
 public class MessageIdSupplierTest {
 
-    private static final int GELF_UDP_MESSAGE_ID_LENGTH = 8;
-    private MessageIdSupplier messageIdSupplier = new MessageIdSupplier();
+    private final MessageIdSupplier messageIdSupplier = new MessageIdSupplier();
 
     @Test
     public void test() {
-        final byte[] bytes = messageIdSupplier.get();
-        assertEquals(GELF_UDP_MESSAGE_ID_LENGTH, bytes.length);
-        assertFalse(Arrays.equals(bytes, messageIdSupplier.get()));
+        final Long messageId = messageIdSupplier.get();
+        assertNotEquals(messageId, messageIdSupplier.get());
     }
 
 }