Added OPAQUE text encoding, using base64

.gitignore

@@ -20,6 +20,9 @@ bin/
 .idea/
 *.iml
 
+# Visual Studio Code files #
+.vscode/
+
 # Package Files #
 *.jar
 *.war

leshan-core/src/main/java/org/eclipse/leshan/core/node/codec/text/LwM2mNodeTextDecoder.java

@@ -27,6 +27,7 @@
 import org.eclipse.leshan.core.node.LwM2mSingleResource;
 import org.eclipse.leshan.core.node.ObjectLink;
 import org.eclipse.leshan.core.node.codec.CodecException;
+import org.eclipse.leshan.util.Base64;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -96,7 +97,10 @@ private static Object parseTextValue(String value, Type type, LwM2mPath path) th
                         path);
             }
         case OPAQUE:
-            // not specified
+            if (!Base64.isBase64(value)) {
+                throw new CodecException("Invalid value for opaque resource [%s], base64 expected", path);
+            }
+            return Base64.decodeBase64(value);
         default:
             throw new CodecException("Could not handle %s value with TEXT encoder for resource %s", type, path);
         }

leshan-core/src/main/java/org/eclipse/leshan/core/node/codec/text/LwM2mNodeTextEncoder.java

@@ -30,6 +30,7 @@
 import org.eclipse.leshan.core.node.ObjectLink;
 import org.eclipse.leshan.core.node.codec.CodecException;
 import org.eclipse.leshan.core.node.codec.LwM2mValueConverter;
+import org.eclipse.leshan.util.Base64;
 import org.eclipse.leshan.util.Validate;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -100,6 +101,10 @@ public void visit(LwM2mResource resource) {
                 ObjectLink objlnk = (ObjectLink) val;
                 strValue = String.valueOf(objlnk.getObjectId() + ":" + objlnk.getObjectInstanceId());
                 break;
+            case OPAQUE:
+                byte[] binaryValue = (byte[]) val;
+                strValue = Base64.encodeBase64String(binaryValue);
+                break;
             default:
                 throw new CodecException("Cannot encode %s in text format for %s", val, path);
             }

leshan-core/src/test/java/org/eclipse/leshan/core/node/codec/LwM2mNodeDecoderTest.java

@@ -225,6 +225,27 @@ public void text_battery_resource() throws CodecException {
         assertEquals(100, ((Number) resource.getValue()).intValue());
     }
 
+    @Test
+    public void text_decode_opaque_from_base64_string() throws CodecException {
+        // Using Firmware Update/Package
+        LwM2mSingleResource resource = (LwM2mSingleResource) decoder.decode("AQIDBAU=".getBytes(StandardCharsets.UTF_8),
+                ContentFormat.TEXT, new LwM2mPath(5, 0, 0), model);
+
+        byte[] expectedValue = new byte[] { 0x1, 0x2, 0x3, 0x4, 0x5 };
+
+        assertEquals(0, resource.getId());
+        assertFalse(resource.isMultiInstances());
+        assertEquals(Type.OPAQUE, resource.getType());
+        assertArrayEquals(expectedValue, ((byte[]) resource.getValue()));
+    }
+
+    @Test(expected = CodecException.class)
+    public void text_decode_should_throw_an_exception_for_invalid_base64() throws CodecException {
+        // Using Firmware Update/Package
+        decoder.decode("!,-INVALID$_'".getBytes(StandardCharsets.UTF_8),
+                ContentFormat.TEXT, new LwM2mPath(5, 0, 0), model);
+    }
+
     @Test
     public void tlv_manufacturer_resource() throws CodecException {
         String value = "MyManufacturer";

leshan-core/src/test/java/org/eclipse/leshan/core/node/codec/LwM2mNodeEncoderTest.java

@@ -89,6 +89,15 @@ public void text_encode_multiple_instances() {
                 model);
     }
 
+    @Test
+    public void text_encode_opaque_as_base64_string() {
+        byte[] opaqueValue = new byte[] { 0x1, 0x2, 0x3, 0x4, 0x5 };
+        byte[] encoded = encoder.encode(LwM2mSingleResource.newBinaryResource(0, opaqueValue), ContentFormat.TEXT,
+                new LwM2mPath("/5/0/0"), model);
+
+        Assert.assertEquals("AQIDBAU=", new String(encoded, StandardCharsets.UTF_8));
+    }
+
     // tlv content for instance 0 of device object (encoded as an array of resource TLVs)
     // Example from LWM2M spec §4.3.1
     private final static byte[] ENCODED_DEVICE_WITHOUT_INSTANCE = Hex.decodeHex(