Jonathan Hart | 2a65575 | 2015-04-07 16:46:33 -0700 | [diff] [blame] | 1 | /* |
Brian O'Connor | 5ab426f | 2016-04-09 01:19:45 -0700 | [diff] [blame] | 2 | * Copyright 2015-present Open Networking Laboratory |
Jonathan Hart | 2a65575 | 2015-04-07 16:46:33 -0700 | [diff] [blame] | 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | package org.onlab.packet; |
| 18 | |
| 19 | import static com.google.common.base.Preconditions.checkNotNull; |
| 20 | |
| 21 | /** |
| 22 | * Utilities for working with packet headers. |
| 23 | */ |
| 24 | public final class PacketUtils { |
| 25 | |
| 26 | private PacketUtils() { |
| 27 | } |
| 28 | |
| 29 | /** |
| 30 | * Check the length of the input buffer is appropriate given the offset and |
| 31 | * length parameters. |
| 32 | * |
| 33 | * @param byteLength length of the input buffer array |
| 34 | * @param offset offset given to begin reading bytes from |
| 35 | * @param length length given to read up until |
| 36 | * @throws DeserializationException if the input parameters don't match up (i.e |
| 37 | * we can't read that many bytes from the buffer at the given offest) |
| 38 | */ |
| 39 | public static void checkBufferLength(int byteLength, int offset, int length) |
| 40 | throws DeserializationException { |
| 41 | boolean ok = (offset >= 0 && offset < byteLength); |
| 42 | ok = ok & (length >= 0 && offset + length <= byteLength); |
| 43 | |
| 44 | if (!ok) { |
| 45 | throw new DeserializationException("Unable to read " + length + " bytes from a " |
| 46 | + byteLength + " byte array starting at offset " + offset); |
| 47 | } |
| 48 | } |
| 49 | |
| 50 | /** |
| 51 | * Check that there are enough bytes in the buffer to read some number of |
| 52 | * bytes that we need to read a full header. |
| 53 | * |
| 54 | * @param givenLength given size of the buffer |
| 55 | * @param requiredLength number of bytes we need to read some header fully |
| 56 | * @throws DeserializationException if there aren't enough bytes |
| 57 | */ |
| 58 | public static void checkHeaderLength(int givenLength, int requiredLength) |
| 59 | throws DeserializationException { |
| 60 | if (requiredLength > givenLength) { |
| 61 | throw new DeserializationException(requiredLength |
| 62 | + " bytes are needed to continue deserialization, however only " |
| 63 | + givenLength + " remain in buffer"); |
| 64 | } |
| 65 | } |
| 66 | |
| 67 | /** |
| 68 | * Check the input parameters are sane and there's enough bytes to read |
| 69 | * the required length. |
| 70 | * |
| 71 | * @param data input byte buffer |
| 72 | * @param offset offset of the start of the header |
| 73 | * @param length length given to deserialize the header |
| 74 | * @param requiredLength length needed to deserialize header |
| 75 | * @throws DeserializationException if we're unable to deserialize the |
| 76 | * packet based on the input parameters |
| 77 | */ |
| 78 | public static void checkInput(byte[] data, int offset, int length, int requiredLength) |
| 79 | throws DeserializationException { |
| 80 | checkNotNull(data); |
| 81 | checkBufferLength(data.length, offset, length); |
| 82 | checkHeaderLength(length, requiredLength); |
| 83 | } |
| 84 | } |