+/*
+ * Copyright (c) 2013-2014 Cisco Systems, Inc. and others. All rights reserved.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v1.0 which accompanies this distribution,
+ * and is available at http://www.eclipse.org/legal/epl-v10.html
+ */
+
+package org.opendaylight.controller.liblldp;
+
+import java.util.Arrays;
+import java.util.Map;
+import java.util.Map.Entry;
+
+import org.apache.commons.lang3.tuple.Pair;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Abstract class which represents the generic network packet object It provides
+ * the basic methods which are common for all the packets, like serialize and
+ * deserialize
+ */
+
+public abstract class Packet {
+ protected static final Logger logger = LoggerFactory
+ .getLogger(Packet.class);
+ // Access level granted to this packet
+ protected boolean writeAccess;
+ // When deserialized from wire, packet could result corrupted
+ protected boolean corrupted;
+ // The packet that encapsulate this packet
+ protected Packet parent;
+ // The packet encapsulated by this packet
+ protected Packet payload;
+ // The unparsed raw payload carried by this packet
+ protected byte[] rawPayload;
+ // Bit coordinates of packet header fields
+ protected Map<String, Pair<Integer, Integer>> hdrFieldCoordMap;
+ // Header fields values: Map<FieldName,Value>
+ protected Map<String, byte[]> hdrFieldsMap;
+ // The class of the encapsulated packet object
+ protected Class<? extends Packet> payloadClass;
+
+ public Packet() {
+ writeAccess = false;
+ corrupted = false;
+ }
+
+ public Packet(boolean writeAccess) {
+ this.writeAccess = writeAccess;
+ corrupted = false;
+ }
+
+ public Packet getParent() {
+ return parent;
+ }
+
+ public Packet getPayload() {
+ return payload;
+ }
+
+ public void setParent(Packet parent) {
+ this.parent = parent;
+ }
+
+ public void setPayload(Packet payload) {
+ this.payload = payload;
+ }
+
+ public void setHeaderField(String headerField, byte[] readValue) {
+ hdrFieldsMap.put(headerField, readValue);
+ }
+
+ /**
+ * This method deserializes the data bits obtained from the wire into the
+ * respective header and payload which are of type Packet
+ *
+ * @param byte[] data - data from wire to deserialize
+ * @param int bitOffset bit position where packet header starts in data
+ * array
+ * @param int size of packet in bits
+ * @return Packet
+ * @throws PacketException
+ */
+ public Packet deserialize(byte[] data, int bitOffset, int size)
+ throws PacketException {
+
+ // Deserialize the header fields one by one
+ int startOffset = 0, numBits = 0;
+ for (Entry<String, Pair<Integer, Integer>> pairs : hdrFieldCoordMap
+ .entrySet()) {
+ String hdrField = pairs.getKey();
+ startOffset = bitOffset + this.getfieldOffset(hdrField);
+ numBits = this.getfieldnumBits(hdrField);
+
+ byte[] hdrFieldBytes = null;
+ try {
+ hdrFieldBytes = BitBufferHelper.getBits(data, startOffset,
+ numBits);
+ } catch (BufferException e) {
+ throw new PacketException(e.getMessage());
+ }
+
+ /*
+ * Store the raw read value, checks the payload type and set the
+ * payloadClass accordingly
+ */
+ this.setHeaderField(hdrField, hdrFieldBytes);
+
+ if (logger.isTraceEnabled()) {
+ logger.trace("{}: {}: {} (offset {} bitsize {})",
+ new Object[] { this.getClass().getSimpleName(), hdrField,
+ HexEncode.bytesToHexString(hdrFieldBytes),
+ startOffset, numBits });
+ }
+ }
+
+ // Deserialize the payload now
+ int payloadStart = startOffset + numBits;
+ int payloadSize = data.length * NetUtils.NumBitsInAByte - payloadStart;
+
+ if (payloadClass != null) {
+ try {
+ payload = payloadClass.newInstance();
+ } catch (Exception e) {
+ throw new RuntimeException(
+ "Error parsing payload for Ethernet packet", e);
+ }
+ payload.deserialize(data, payloadStart, payloadSize);
+ payload.setParent(this);
+ } else {
+ /*
+ * The payload class was not set, it means no class for parsing
+ * this payload is present. Let's store the raw payload if any.
+ */
+ int start = payloadStart / NetUtils.NumBitsInAByte;
+ int stop = start + payloadSize / NetUtils.NumBitsInAByte;
+ rawPayload = Arrays.copyOfRange(data, start, stop);
+ }
+
+
+ // Take care of computation that can be done only after deserialization
+ postDeserializeCustomOperation(data, payloadStart - getHeaderSize());
+
+ return this;
+ }
+
+ /**
+ * This method serializes the header and payload from the respective
+ * packet class, into a single stream of bytes to be sent on the wire
+ *
+ * @return The byte array representing the serialized Packet
+ * @throws PacketException
+ */
+ public byte[] serialize() throws PacketException {
+
+ // Acquire or compute the serialized payload
+ byte[] payloadBytes = null;
+ if (payload != null) {
+ payloadBytes = payload.serialize();
+ } else if (rawPayload != null) {
+ payloadBytes = rawPayload;
+ }
+ int payloadSize = (payloadBytes == null) ? 0 : payloadBytes.length;
+
+ // Allocate the buffer to contain the full (header + payload) packet
+ int headerSize = this.getHeaderSize() / NetUtils.NumBitsInAByte;
+ byte packetBytes[] = new byte[headerSize + payloadSize];
+ if (payloadBytes != null) {
+ System.arraycopy(payloadBytes, 0, packetBytes, headerSize, payloadSize);
+ }
+
+ // Serialize this packet header, field by field
+ for (Map.Entry<String, Pair<Integer, Integer>> pairs : hdrFieldCoordMap
+ .entrySet()) {
+ String field = pairs.getKey();
+ byte[] fieldBytes = hdrFieldsMap.get(field);
+ // Let's skip optional fields when not set
+ if (fieldBytes != null) {
+ try {
+ BitBufferHelper.setBytes(packetBytes, fieldBytes,
+ getfieldOffset(field), getfieldnumBits(field));
+ } catch (BufferException e) {
+ throw new PacketException(e.getMessage());
+ }
+ }
+ }
+
+ // Perform post serialize operations (like checksum computation)
+ postSerializeCustomOperation(packetBytes);
+
+ if (logger.isTraceEnabled()) {
+ logger.trace("{}: {}", this.getClass().getSimpleName(),
+ HexEncode.bytesToHexString(packetBytes));
+ }
+
+ return packetBytes;
+ }
+
+ /**
+ * This method gets called at the end of the serialization process It is
+ * intended for the child packets to insert some custom data into the output
+ * byte stream which cannot be done or cannot be done efficiently during the
+ * normal Packet.serialize() path. An example is the checksum computation
+ * for IPv4
+ *
+ * @param byte[] - serialized bytes
+ * @throws PacketException
+ */
+ protected void postSerializeCustomOperation(byte[] myBytes)
+ throws PacketException {
+ // no op
+ }
+
+ /**
+ * This method re-computes the checksum of the bits received on the wire and
+ * validates it with the checksum in the bits received Since the computation
+ * of checksum varies based on the protocol, this method is overridden.
+ * Currently only IPv4 and ICMP do checksum computation and validation. TCP
+ * and UDP need to implement these if required.
+ *
+ * @param byte[] data The byte stream representing the Ethernet frame
+ * @param int startBitOffset The bit offset from where the byte array corresponding to this Packet starts in the frame
+ * @throws PacketException
+ */
+ protected void postDeserializeCustomOperation(byte[] data, int startBitOffset)
+ throws PacketException {
+ // no op
+ }
+
+ /**
+ * Gets the header length in bits
+ *
+ * @return int the header length in bits
+ */
+ public int getHeaderSize() {
+ int size = 0;
+ /*
+ * We need to iterate over the fields that were read in the frame
+ * (hdrFieldsMap) not all the possible ones described in
+ * hdrFieldCoordMap. For ex, 802.1Q may or may not be there
+ */
+ for (Map.Entry<String, byte[]> fieldEntry : hdrFieldsMap.entrySet()) {
+ if (fieldEntry.getValue() != null) {
+ String field = fieldEntry.getKey();
+ size += getfieldnumBits(field);
+ }
+ }
+ return size;
+ }
+
+ /**
+ * This method fetches the start bit offset for header field specified by
+ * 'fieldname'. The offset is present in the hdrFieldCoordMap of the
+ * respective packet class
+ *
+ * @param String
+ * fieldName
+ * @return Integer - startOffset of the requested field
+ */
+ public int getfieldOffset(String fieldName) {
+ return hdrFieldCoordMap.get(fieldName).getLeft();
+ }
+
+ /**
+ * This method fetches the number of bits for header field specified by
+ * 'fieldname'. The numBits are present in the hdrFieldCoordMap of the
+ * respective packet class
+ *
+ * @param String
+ * fieldName
+ * @return Integer - number of bits of the requested field
+ */
+ public int getfieldnumBits(String fieldName) {
+ return hdrFieldCoordMap.get(fieldName).getRight();
+ }
+
+ @Override
+ public String toString() {
+ StringBuilder ret = new StringBuilder();
+ ret.append(this.getClass().getSimpleName());
+ ret.append(": [");
+ for (String field : hdrFieldCoordMap.keySet()) {
+ byte[] value = hdrFieldsMap.get(field);
+ ret.append(field);
+ ret.append(": ");
+ ret.append(HexEncode.bytesToHexString(value));
+ ret.append(", ");
+ }
+ ret.replace(ret.length()-2, ret.length()-1, "]");
+ return ret.toString();
+ }
+
+ /**
+ * Returns the raw payload carried by this packet in case payload was not
+ * parsed. Caller can call this function in case the getPaylod() returns null.
+ *
+ * @return The raw payload if not parsable as an array of bytes, null otherwise
+ */
+ public byte[] getRawPayload() {
+ return rawPayload;
+ }
+
+ /**
+ * Set a raw payload in the packet class
+ *
+ * @param payload The raw payload as byte array
+ */
+ public void setRawPayload(byte[] payload) {
+ this.rawPayload = Arrays.copyOf(payload, payload.length);
+ }
+
+ /**
+ * Return whether the deserialized packet is to be considered corrupted.
+ * This is the case when the checksum computed after reconstructing the
+ * packet received from wire is not equal to the checksum read from the
+ * stream. For the Packet class which do not have a checksum field, this
+ * function will always return false.
+ *
+ *
+ * @return true if the deserialized packet's recomputed checksum is not
+ * equal to the packet carried checksum
+ */
+ public boolean isCorrupted() {
+ return corrupted;
+ }
+
+ @Override
+ public int hashCode() {
+ final int prime = 31;
+ int result = super.hashCode();
+ result = prime * result
+ + ((this.hdrFieldsMap == null) ? 0 : hdrFieldsMap.hashCode());
+ return result;
+ }
+
+ @Override
+ public boolean equals(Object obj) {
+ if (this == obj) {
+ return true;
+ }
+ if (getClass() != obj.getClass()) {
+ return false;
+ }
+ Packet other = (Packet) obj;
+ if (hdrFieldsMap == other.hdrFieldsMap) {
+ return true;
+ }
+ if (hdrFieldsMap == null || other.hdrFieldsMap == null) {
+ return false;
+ }
+ if (hdrFieldsMap != null && other.hdrFieldsMap != null) {
+ for (String field : hdrFieldsMap.keySet()) {
+ if (!Arrays.equals(hdrFieldsMap.get(field), other.hdrFieldsMap.get(field))) {
+ return false;
+ }
+ }
+ } else {
+ return false;
+ }
+ return true;
+ }
+}
Code Review / controller.git / blobdiff