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The core module of Pcap4J.
/*_##########################################################################
_##
_## Copyright (C) 2012-2017 Pcap4J.org
_##
_##########################################################################
*/
package org.pcap4j.packet;
import static org.pcap4j.util.ByteArrays.*;
import java.util.ArrayList;
import java.util.List;
import org.pcap4j.packet.factory.PacketFactories;
import org.pcap4j.packet.namednumber.IcmpV4Code;
import org.pcap4j.packet.namednumber.IcmpV4Type;
import org.pcap4j.util.ByteArrays;
/**
* @author Kaito Yamada
* @since pcap4j 0.9.11
*/
public final class IcmpV4CommonPacket extends AbstractPacket {
/**
*
*/
private static final long serialVersionUID = 7643067752830062365L;
private final IcmpV4CommonHeader header;
private final Packet payload;
/**
* A static factory method.
* This method validates the arguments by {@link ByteArrays#validateBounds(byte[], int, int)},
* which may throw exceptions undocumented here.
*
* @param rawData rawData
* @param offset offset
* @param length length
* @return a new IcmpV4CommonPacket object.
* @throws IllegalRawDataException if parsing the raw data fails.
*/
public static IcmpV4CommonPacket newPacket(
byte[] rawData, int offset, int length
) throws IllegalRawDataException {
ByteArrays.validateBounds(rawData, offset, length);
return new IcmpV4CommonPacket(rawData, offset, length);
}
private IcmpV4CommonPacket(
byte[] rawData, int offset, int length
) throws IllegalRawDataException {
this.header = new IcmpV4CommonHeader(rawData, offset, length);
int payloadLength = length - header.length();
if (payloadLength > 0) {
this.payload
= PacketFactories.getFactory(Packet.class, IcmpV4Type.class)
.newInstance(rawData, offset + header.length(), payloadLength, header.getType());
}
else {
this.payload = null;
}
}
private IcmpV4CommonPacket(Builder builder) {
if (
builder == null
|| builder.type == null
|| builder.code == null
) {
StringBuilder sb = new StringBuilder();
sb.append("builder: ").append(builder)
.append(" builder.type: ").append(builder.type)
.append(" builder.code: ").append(builder.code);
throw new NullPointerException(sb.toString());
}
this.payload = builder.payloadBuilder != null ? builder.payloadBuilder.build() : null;
this.header = new IcmpV4CommonHeader(
builder,
payload != null ? payload.getRawData() : new byte[0]
);
}
@Override
public IcmpV4CommonHeader getHeader() {
return header;
}
@Override
public Packet getPayload() {
return payload;
}
@Override
public Builder getBuilder() {
return new Builder(this);
}
/**
*
* @param acceptZero acceptZero
* @return true if the packet represented by this object has a valid checksum;
* false otherwise.
*/
public boolean hasValidChecksum(boolean acceptZero) {
byte[] payloadData = payload != null ? payload.getRawData() : new byte[0];
short calculatedChecksum = header.calcChecksum(header.getRawData(), payloadData);
if (calculatedChecksum == 0) {
return true;
}
if (header.checksum == 0 && acceptZero) {
return true;
}
return false;
}
/**
* @author Kaito Yamada
* @since pcap4j 0.9.11
*/
public static final
class Builder extends AbstractBuilder
implements ChecksumBuilder {
private IcmpV4Type type;
private IcmpV4Code code;
private short checksum;
private Packet.Builder payloadBuilder;
private boolean correctChecksumAtBuild;
/**
*
*/
public Builder() {}
private Builder(IcmpV4CommonPacket packet) {
this.type = packet.header.type;
this.code = packet.header.code;
this.checksum = packet.header.checksum;
this.payloadBuilder = packet.payload != null ? packet.payload.getBuilder() : null;
}
/**
*
* @param type type
* @return this Builder object for method chaining.
*/
public Builder type(IcmpV4Type type) {
this.type = type;
return this;
}
/**
*
* @param code code
* @return this Builder object for method chaining.
*/
public Builder code(IcmpV4Code code) {
this.code = code;
return this;
}
/**
*
* @param checksum checksum
* @return this Builder object for method chaining.
*/
public Builder checksum(short checksum) {
this.checksum = checksum;
return this;
}
@Override
public Builder payloadBuilder(Packet.Builder payloadBuilder) {
this.payloadBuilder = payloadBuilder;
return this;
}
@Override
public Packet.Builder getPayloadBuilder() {
return payloadBuilder;
}
@Override
public Builder correctChecksumAtBuild(boolean correctChecksumAtBuild) {
this.correctChecksumAtBuild = correctChecksumAtBuild;
return this;
}
@Override
public IcmpV4CommonPacket build() {
return new IcmpV4CommonPacket(this);
}
}
/**
* @author Kaito Yamada
* @since pcap4j 0.9.11
*/
public static final class IcmpV4CommonHeader extends AbstractHeader {
/*
* 0 15
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Type | Code |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Checksum |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*
*/
/**
*
*/
private static final long serialVersionUID = 504881105187659087L;
private static final int TYPE_OFFSET
= 0;
private static final int TYPE_SIZE
= BYTE_SIZE_IN_BYTES;
private static final int CODE_OFFSET
= TYPE_OFFSET + TYPE_SIZE;
private static final int CODE_SIZE
= BYTE_SIZE_IN_BYTES;
private static final int CHECKSUM_OFFSET
= CODE_OFFSET + CODE_SIZE;
private static final int CHECKSUM_SIZE
= SHORT_SIZE_IN_BYTES;
private static final int ICMPV4_COMMON_HEADER_SIZE
= CHECKSUM_OFFSET + CHECKSUM_SIZE;
private final IcmpV4Type type;
private final IcmpV4Code code;
private final short checksum;
private IcmpV4CommonHeader(
byte[] rawData, int offset, int length
) throws IllegalRawDataException {
if (length < ICMPV4_COMMON_HEADER_SIZE) {
StringBuilder sb = new StringBuilder(80);
sb.append("The data is too short to build an ICMPv4 common header(")
.append(ICMPV4_COMMON_HEADER_SIZE)
.append(" bytes). data: ")
.append(ByteArrays.toHexString(rawData, " "))
.append(", offset: ")
.append(offset)
.append(", length: ")
.append(length);
throw new IllegalRawDataException(sb.toString());
}
this.type
= IcmpV4Type
.getInstance(ByteArrays.getByte(rawData, TYPE_OFFSET + offset));
this.code
= IcmpV4Code
.getInstance(type.value(), ByteArrays.getByte(rawData, CODE_OFFSET + offset));
this.checksum
= ByteArrays.getShort(rawData, CHECKSUM_OFFSET + offset);
}
private IcmpV4CommonHeader(Builder builder, byte[] payload) {
this.type = builder.type;
this.code = builder.code;
if (builder.correctChecksumAtBuild) {
if (PacketPropertiesLoader.getInstance().icmpV4CalcChecksum()) {
this.checksum = calcChecksum(buildRawData(true), payload);
}
else {
this.checksum = (short)0;
}
}
else {
this.checksum = builder.checksum;
}
}
private short calcChecksum(byte[] header, byte[] payload) {
byte[] data;
int packetLength = payload.length + length();
if ((packetLength % 2) != 0) {
data = new byte[packetLength + 1];
}
else {
data = new byte[packetLength];
}
System.arraycopy(
header, 0, data, 0, header.length
);
System.arraycopy(
payload, 0, data, header.length, payload.length
);
return ByteArrays.calcChecksum(data);
}
/**
*
* @return type
*/
public IcmpV4Type getType() {
return type;
}
/**
*
* @return code
*/
public IcmpV4Code getCode() {
return code;
}
/**
*
* @return checksum
*/
public short getChecksum() {
return checksum;
}
@Override
protected List getRawFields() {
return getRawFields(false);
}
private List getRawFields(boolean zeroInsteadOfChecksum) {
List rawFields = new ArrayList();
rawFields.add(ByteArrays.toByteArray(type.value()));
rawFields.add(ByteArrays.toByteArray(code.value()));
rawFields.add(ByteArrays.toByteArray(zeroInsteadOfChecksum ? (short) 0 : checksum));
return rawFields;
}
private byte[] buildRawData(boolean zeroInsteadOfChecksum) {
return ByteArrays.concatenate(getRawFields(zeroInsteadOfChecksum));
}
@Override
public int length() {
return ICMPV4_COMMON_HEADER_SIZE;
}
@Override
protected String buildString() {
StringBuilder sb = new StringBuilder();
String ls = System.getProperty("line.separator");
sb.append("[ICMPv4 Common Header (")
.append(length())
.append(" bytes)]")
.append(ls);
sb.append(" Type: ")
.append(type)
.append(ls);
sb.append(" Code: ")
.append(code)
.append(ls);
sb.append(" Checksum: 0x")
.append(ByteArrays.toHexString(checksum, ""))
.append(ls);
return sb.toString();
}
@Override
public boolean equals(Object obj) {
if (obj == this) { return true; }
if (!this.getClass().isInstance(obj)) { return false; }
IcmpV4CommonHeader other = (IcmpV4CommonHeader)obj;
return
checksum == other.checksum
&& type.equals(other.type)
&& code.equals(other.code);
}
@Override
protected int calcHashCode() {
int result = 17;
result = 31 * result + type.hashCode();
result = 31 * result + code.hashCode();
result = 31 * result + checksum;
return result;
}
}
}
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