1 files changed, 84 insertions, 0 deletions
diff --git a/framework/src/onos/utils/misc/src/main/java/org/onlab/packet/PacketUtils.java b/framework/src/onos/utils/misc/src/main/java/org/onlab/packet/PacketUtils.java
new file mode 100644
index 00000000..c3bede2f
--- /dev/null
+++ b/framework/src/onos/utils/misc/src/main/java/org/onlab/packet/PacketUtils.java
@@ -0,0 +1,84 @@
+/*
+ * Copyright 2015 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onlab.packet;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+/**
+ * Utilities for working with packet headers.
+ */
+public final class PacketUtils {
+
+    private PacketUtils() {
+    }
+
+    /**
+     * Check the length of the input buffer is appropriate given the offset and
+     * length parameters.
+     *
+     * @param byteLength length of the input buffer array
+     * @param offset offset given to begin reading bytes from
+     * @param length length given to read up until
+     * @throws DeserializationException if the input parameters don't match up (i.e
+     * we can't read that many bytes from the buffer at the given offest)
+     */
+    public static void checkBufferLength(int byteLength, int offset, int length)
+            throws DeserializationException {
+        boolean ok = (offset >= 0 && offset < byteLength);
+        ok = ok & (length >= 0 && offset + length <= byteLength);
+
+        if (!ok) {
+            throw new DeserializationException("Unable to read " + length + " bytes from a "
+                + byteLength + " byte array starting at offset " + offset);
+        }
+    }
+
+    /**
+     * Check that there are enough bytes in the buffer to read some number of
+     * bytes that we need to read a full header.
+     *
+     * @param givenLength given size of the buffer
+     * @param requiredLength number of bytes we need to read some header fully
+     * @throws DeserializationException if there aren't enough bytes
+     */
+    public static void checkHeaderLength(int givenLength, int requiredLength)
+            throws DeserializationException {
+        if (requiredLength > givenLength) {
+            throw new DeserializationException(requiredLength
+                + " bytes are needed to continue deserialization, however only "
+                + givenLength + " remain in buffer");
+        }
+    }
+
+    /**
+     * Check the input parameters are sane and there's enough bytes to read
+     * the required length.
+     *
+     * @param data input byte buffer
+     * @param offset offset of the start of the header
+     * @param length length given to deserialize the header
+     * @param requiredLength length needed to deserialize header
+     * @throws DeserializationException if we're unable to deserialize the
+     * packet based on the input parameters
+     */
+    public static void checkInput(byte[] data, int offset, int length, int requiredLength)
+            throws DeserializationException {
+        checkNotNull(data);
+        checkBufferLength(data.length, offset, length);
+        checkHeaderLength(length, requiredLength);
+    }
+}