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/*
* 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);
}
}
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