From 2a1a8af1f6a7393fdd66f0d7ca3a10edd8bdc1f3 Mon Sep 17 00:00:00 2001
From: Jakub Sobolewski <jakub.sobolewski@softwareag.com>
Date: Wed, 10 Jul 2024 13:37:16 +0200
Subject: [PATCH] GH-1630: Fix TlvEncoder - date (TIME) should be encoded like
 integer.

---
 .../eclipse/leshan/core/tlv/TlvEncoder.java   | 17 ++++-
 .../leshan/core/tlv/TlvEncoderTest.java       | 73 +++++++++++++++++--
 2 files changed, 81 insertions(+), 9 deletions(-)

diff --git a/leshan-lwm2m-core/src/main/java/org/eclipse/leshan/core/tlv/TlvEncoder.java b/leshan-lwm2m-core/src/main/java/org/eclipse/leshan/core/tlv/TlvEncoder.java
index 1b3f4b77dd..90e5e93bff 100644
--- a/leshan-lwm2m-core/src/main/java/org/eclipse/leshan/core/tlv/TlvEncoder.java
+++ b/leshan-lwm2m-core/src/main/java/org/eclipse/leshan/core/tlv/TlvEncoder.java
@@ -113,8 +113,21 @@ public static byte[] encodeString(String value) {
      * Encodes a date value.
      */
     public static byte[] encodeDate(Date value) {
-        ByteBuffer tBuf = ByteBuffer.allocate(4);
-        tBuf.putInt((int) (value.getTime() / 1000L));
+        ByteBuffer tBuf;
+        long lValue = value.getTime() / 1000L;
+        if (lValue <= Byte.MAX_VALUE && lValue >= Byte.MIN_VALUE) {
+            tBuf = ByteBuffer.allocate(1);
+            tBuf.put((byte) lValue);
+        } else if (lValue <= Short.MAX_VALUE && lValue >= Short.MIN_VALUE) {
+            tBuf = ByteBuffer.allocate(2);
+            tBuf.putShort((short) lValue);
+        } else if (lValue <= Integer.MAX_VALUE && lValue >= Integer.MIN_VALUE) {
+            tBuf = ByteBuffer.allocate(4);
+            tBuf.putInt((int) lValue);
+        } else {
+            tBuf = ByteBuffer.allocate(8);
+            tBuf.putLong(lValue);
+        }
         return tBuf.array();
     }
 
diff --git a/leshan-lwm2m-core/src/test/java/org/eclipse/leshan/core/tlv/TlvEncoderTest.java b/leshan-lwm2m-core/src/test/java/org/eclipse/leshan/core/tlv/TlvEncoderTest.java
index 944da7a38d..ac6c19b335 100644
--- a/leshan-lwm2m-core/src/test/java/org/eclipse/leshan/core/tlv/TlvEncoderTest.java
+++ b/leshan-lwm2m-core/src/test/java/org/eclipse/leshan/core/tlv/TlvEncoderTest.java
@@ -19,7 +19,10 @@
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
 import java.nio.ByteBuffer;
+import java.time.ZoneId;
+import java.util.Calendar;
 import java.util.Date;
+import java.util.TimeZone;
 
 import org.eclipse.leshan.core.tlv.Tlv.TlvType;
 import org.junit.jupiter.api.Test;
@@ -57,15 +60,71 @@ public void encode_long() {
         assertEquals(0, bb.remaining());
     }
 
-    @Test
-    public void encode_date() {
-        long timestamp = System.currentTimeMillis();
-        byte[] encoded = TlvEncoder.encodeDate(new Date(timestamp));
+    private void shouldEncodeDateAsNumberOfBytes(long utcTimeInSeconds, int expectedNumberOfBytes) throws TlvException {
+        Calendar cal = Calendar.getInstance(TimeZone.getTimeZone(ZoneId.of("UTC")));
+        cal.setTimeInMillis(utcTimeInSeconds * 1000);
 
-        // check value
+        // encode
+        byte[] encoded = TlvEncoder.encodeDate(cal.getTime());
+
+        // check byte array value
         ByteBuffer bb = ByteBuffer.wrap(encoded);
-        assertEquals((int) (timestamp / 1000), bb.getInt());
-        assertEquals(0, bb.remaining());
+        if (expectedNumberOfBytes == 1) {
+            assertEquals((byte) (cal.getTimeInMillis() / 1000), bb.get());
+            assertEquals(0, bb.remaining());
+        } else if (expectedNumberOfBytes == 2) {
+            assertEquals((short) (cal.getTimeInMillis() / 1000), bb.getShort());
+            assertEquals(0, bb.remaining());
+        } else if (expectedNumberOfBytes == 4) {
+            assertEquals((int) (cal.getTimeInMillis() / 1000), bb.getInt());
+            assertEquals(0, bb.remaining());
+        } else {
+            assertEquals(cal.getTimeInMillis() / 1000, bb.getLong());
+            assertEquals(0, bb.remaining());
+        }
+
+        // confirm decoded value
+        Date date = TlvDecoder.decodeDate(encoded);
+        assertEquals(cal.getTimeInMillis(), date.getTime());
+    }
+
+    @Test
+    public void encode_date_byte() throws TlvException {
+        shouldEncodeDateAsNumberOfBytes(Byte.MAX_VALUE, 1);
+        shouldEncodeDateAsNumberOfBytes(Byte.MIN_VALUE, 1);
+        shouldEncodeDateAsNumberOfBytes(0, 1);
+        shouldEncodeDateAsNumberOfBytes(100, 1);
+        shouldEncodeDateAsNumberOfBytes(-100, 1);
+    }
+
+    @Test
+    public void encode_date_short() throws TlvException {
+        shouldEncodeDateAsNumberOfBytes(Byte.MAX_VALUE + 1, 2);
+        shouldEncodeDateAsNumberOfBytes(Byte.MIN_VALUE - 1, 2);
+        shouldEncodeDateAsNumberOfBytes(Short.MAX_VALUE, 2);
+        shouldEncodeDateAsNumberOfBytes(Short.MIN_VALUE, 2);
+        shouldEncodeDateAsNumberOfBytes(32000, 2);
+        shouldEncodeDateAsNumberOfBytes(-32000, 2);
+    }
+
+    @Test
+    public void encode_date_int() throws TlvException {
+        shouldEncodeDateAsNumberOfBytes(Short.MAX_VALUE + 1, 4);
+        shouldEncodeDateAsNumberOfBytes(Short.MIN_VALUE - 1, 4);
+        shouldEncodeDateAsNumberOfBytes(Integer.MAX_VALUE, 4);
+        shouldEncodeDateAsNumberOfBytes(Integer.MIN_VALUE, 4);
+        shouldEncodeDateAsNumberOfBytes(Integer.MAX_VALUE - 100, 4);
+        shouldEncodeDateAsNumberOfBytes(Integer.MIN_VALUE + 100, 4);
+    }
+
+    @Test
+    public void encode_date_long() throws TlvException {
+        shouldEncodeDateAsNumberOfBytes((long) Integer.MAX_VALUE + 1, 8);
+        shouldEncodeDateAsNumberOfBytes((long) Integer.MIN_VALUE - 1, 8);
+        shouldEncodeDateAsNumberOfBytes(Long.MAX_VALUE / 1000, 8);
+        shouldEncodeDateAsNumberOfBytes(Long.MIN_VALUE / 1000, 8);
+        shouldEncodeDateAsNumberOfBytes(Long.MAX_VALUE / 1000 - 100, 8);
+        shouldEncodeDateAsNumberOfBytes(Long.MIN_VALUE / 1000 + 100, 8);
     }
 
     @Test