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The core module of Pcap4J.
/*_##########################################################################
_##
_## Copyright (C) 2011-2019 Pcap4J.org
_##
_##########################################################################
*/
package org.pcap4j.packet;
import static org.pcap4j.util.ByteArrays.SHORT_SIZE_IN_BYTES;
import java.net.Inet4Address;
import java.net.Inet6Address;
import java.net.InetAddress;
import java.util.ArrayList;
import java.util.List;
import org.pcap4j.packet.factory.PacketFactories;
import org.pcap4j.packet.factory.PacketFactory;
import org.pcap4j.packet.namednumber.IpNumber;
import org.pcap4j.packet.namednumber.UdpPort;
import org.pcap4j.util.ByteArrays;
/**
* @author Kaito Yamada
* @since pcap4j 0.9.1
*/
public final class UdpPacket extends AbstractPacket implements TransportPacket {
/** */
private static final long serialVersionUID = 4638029542367352625L;
private final UdpHeader 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 UdpPacket object.
* @throws IllegalRawDataException if parsing the raw data fails.
*/
public static UdpPacket newPacket(byte[] rawData, int offset, int length)
throws IllegalRawDataException {
ByteArrays.validateBounds(rawData, offset, length);
return new UdpPacket(rawData, offset, length);
}
private UdpPacket(byte[] rawData, int offset, int length) throws IllegalRawDataException {
this.header = new UdpHeader(rawData, offset, length);
int payloadLength = header.getLengthAsInt() - header.length();
if (payloadLength < 0) {
throw new IllegalRawDataException(
"The value of length field seems to be wrong: " + header.getLengthAsInt());
}
if (payloadLength > length - header.length()) {
payloadLength = length - header.length();
}
if (payloadLength != 0) { // payloadLength is positive.
PacketFactory factory =
PacketFactories.getFactory(Packet.class, UdpPort.class);
Class class4UnknownPort = factory.getTargetClass();
Class class4DstPort = factory.getTargetClass(header.getDstPort());
UdpPort serverPort;
if (class4DstPort.equals(class4UnknownPort)) {
serverPort = header.getSrcPort();
} else {
serverPort = header.getDstPort();
}
this.payload =
PacketFactories.getFactory(Packet.class, UdpPort.class)
.newInstance(rawData, offset + header.length(), payloadLength, serverPort);
} else {
this.payload = null;
}
}
private UdpPacket(Builder builder) {
if (builder == null || builder.srcPort == null || builder.dstPort == null) {
StringBuilder sb = new StringBuilder();
sb.append("builder: ")
.append(builder)
.append(" builder.srcPort: ")
.append(builder.srcPort)
.append(" builder.dstPort: ")
.append(builder.dstPort);
throw new NullPointerException(sb.toString());
}
if (builder.correctChecksumAtBuild) {
if (builder.srcAddr == null || builder.dstAddr == null) {
StringBuilder sb = new StringBuilder();
sb.append("builder.srcAddr: ")
.append(builder.srcAddr)
.append(" builder.dstAddr: ")
.append(builder.dstAddr);
throw new NullPointerException(sb.toString());
}
if (!builder.srcAddr.getClass().isInstance(builder.dstAddr)) {
StringBuilder sb = new StringBuilder();
sb.append("builder.srcAddr: ")
.append(builder.srcAddr)
.append(" builder.dstAddr: ")
.append(builder.dstAddr);
throw new IllegalArgumentException(sb.toString());
}
}
this.payload = builder.payloadBuilder != null ? builder.payloadBuilder.build() : null;
this.header = new UdpHeader(builder, payload != null ? payload.getRawData() : new byte[0]);
}
@Override
public UdpHeader getHeader() {
return header;
}
@Override
public Packet getPayload() {
return payload;
}
/**
* checksum verification is necessary for IPv6(i.e. acceptZero must be false)
*
* @param srcAddr srcAddr
* @param dstAddr dstAddr
* @param acceptZero acceptZero
* @return true if the packet represented by this object has a valid checksum; false otherwise.
*/
public boolean hasValidChecksum(InetAddress srcAddr, InetAddress dstAddr, boolean acceptZero) {
if (srcAddr == null || dstAddr == null) {
StringBuilder sb = new StringBuilder();
sb.append("srcAddr: ").append(srcAddr).append(" dstAddr: ").append(dstAddr);
throw new NullPointerException(sb.toString());
}
if (!srcAddr.getClass().isInstance(dstAddr)) {
StringBuilder sb = new StringBuilder();
sb.append("srcAddr: ").append(srcAddr).append(" dstAddr: ").append(dstAddr);
throw new IllegalArgumentException(sb.toString());
}
byte[] payloadData = payload != null ? payload.getRawData() : new byte[0];
short calculatedChecksum =
header.calcChecksum(srcAddr, dstAddr, header.getRawData(), payloadData);
if (calculatedChecksum == 0) {
return true;
}
if (header.checksum == 0 && acceptZero) {
return true;
}
return false;
}
@Override
public Builder getBuilder() {
return new Builder(this);
}
/**
* @author Kaito Yamada
* @since pcap4j 0.9.1
*/
public static final class Builder extends AbstractBuilder
implements LengthBuilder, ChecksumBuilder {
private UdpPort srcPort;
private UdpPort dstPort;
private short length;
private short checksum;
private Packet.Builder payloadBuilder;
private InetAddress srcAddr;
private InetAddress dstAddr;
private boolean correctLengthAtBuild;
private boolean correctChecksumAtBuild;
/** */
public Builder() {}
/** @param packet packet */
public Builder(UdpPacket packet) {
this.srcPort = packet.header.srcPort;
this.dstPort = packet.header.dstPort;
this.length = packet.header.length;
this.checksum = packet.header.checksum;
this.payloadBuilder = packet.payload != null ? packet.payload.getBuilder() : null;
}
/**
* @param srcPort srcPort
* @return this Builder object for method chaining.
*/
public Builder srcPort(UdpPort srcPort) {
this.srcPort = srcPort;
return this;
}
/**
* @param dstPort dstPort
* @return this Builder object for method chaining.
*/
public Builder dstPort(UdpPort dstPort) {
this.dstPort = dstPort;
return this;
}
/**
* @param length length
* @return this Builder object for method chaining.
*/
public Builder length(short length) {
this.length = length;
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;
}
/**
* used for checksum calculation.
*
* @param srcAddr srcAddr
* @return this Builder object for method chaining.
*/
public Builder srcAddr(InetAddress srcAddr) {
this.srcAddr = srcAddr;
return this;
}
/**
* used for checksum calculation If the lower-layer packet is a IPv6 packet and the extension
* headers including a routing header, this parameter is that of the final destination. (i.e.
* the last element of the Routing header)
*
* @param dstAddr dstAddr
* @return this Builder object for method chaining.
*/
public Builder dstAddr(InetAddress dstAddr) {
this.dstAddr = dstAddr;
return this;
}
@Override
public Builder correctLengthAtBuild(boolean correctLengthAtBuild) {
this.correctLengthAtBuild = correctLengthAtBuild;
return this;
}
@Override
public Builder correctChecksumAtBuild(boolean correctChecksumAtBuild) {
this.correctChecksumAtBuild = correctChecksumAtBuild;
return this;
}
@Override
public UdpPacket build() {
return new UdpPacket(this);
}
}
/**
* @author Kaito Yamada
* @since pcap4j 0.9.1
*/
public static final class UdpHeader extends AbstractHeader implements TransportHeader {
/*
* 0 16 31
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Src Port | Dst Port |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Length | Checksum |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*/
/*
* IPv4 Pseudo Header
*
* 0 16 31
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Src IP Address |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Dst IP Address |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | PAD | Protocol(UDP) | Length |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*
* IPv6 Pseudo Header
*
* 0 16 31
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | |
* + +
* | |
* + Source Address +
* | |
* + +
* | |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | |
* + +
* | |
* + Destination Address +
* | |
* + +
* | |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Upper-Layer Packet Length |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | zero | Next Header |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*/
/** */
private static final long serialVersionUID = -1746545325551976324L;
private static final int SRC_PORT_OFFSET = 0;
private static final int SRC_PORT_SIZE = SHORT_SIZE_IN_BYTES;
private static final int DST_PORT_OFFSET = SRC_PORT_OFFSET + SRC_PORT_SIZE;
private static final int DST_PORT_SIZE = SHORT_SIZE_IN_BYTES;
private static final int LENGTH_OFFSET = DST_PORT_OFFSET + DST_PORT_SIZE;
private static final int LENGTH_SIZE = SHORT_SIZE_IN_BYTES;
private static final int CHECKSUM_OFFSET = LENGTH_OFFSET + LENGTH_SIZE;
private static final int CHECKSUM_SIZE = SHORT_SIZE_IN_BYTES;
private static final int UCP_HEADER_SIZE = CHECKSUM_OFFSET + CHECKSUM_SIZE;
private static final int IPV4_PSEUDO_HEADER_SIZE = 12;
private static final int IPV6_PSEUDO_HEADER_SIZE = 40;
private final UdpPort srcPort;
private final UdpPort dstPort;
private final short length;
private final short checksum;
private UdpHeader(byte[] rawData, int offset, int length) throws IllegalRawDataException {
if (length < UCP_HEADER_SIZE) {
StringBuilder sb = new StringBuilder(80);
sb.append("The data is too short to build a UDP header(")
.append(UCP_HEADER_SIZE)
.append(" bytes). data: ")
.append(ByteArrays.toHexString(rawData, " "))
.append(", offset: ")
.append(offset)
.append(", length: ")
.append(length);
throw new IllegalRawDataException(sb.toString());
}
this.srcPort = UdpPort.getInstance(ByteArrays.getShort(rawData, SRC_PORT_OFFSET + offset));
this.dstPort = UdpPort.getInstance(ByteArrays.getShort(rawData, DST_PORT_OFFSET + offset));
this.length = ByteArrays.getShort(rawData, LENGTH_OFFSET + offset);
this.checksum = ByteArrays.getShort(rawData, CHECKSUM_OFFSET + offset);
}
private UdpHeader(Builder builder, byte[] payload) {
this.srcPort = builder.srcPort;
this.dstPort = builder.dstPort;
if (builder.correctLengthAtBuild) {
this.length = (short) (payload.length + length());
} else {
this.length = builder.length;
}
if (builder.correctChecksumAtBuild) {
if ((builder.srcAddr instanceof Inet4Address
&& PacketPropertiesLoader.getInstance().udpV4CalcChecksum())
|| (builder.srcAddr instanceof Inet6Address
&& PacketPropertiesLoader.getInstance().udpV6CalcChecksum())) {
this.checksum =
calcChecksum(builder.srcAddr, builder.dstAddr, buildRawData(true), payload);
} else {
this.checksum = (short) 0;
}
} else {
this.checksum = builder.checksum;
}
}
private short calcChecksum(
InetAddress srcAddr, InetAddress dstAddr, byte[] header, byte[] payload) {
byte[] data;
int destPos;
int totalLength = payload.length + length();
boolean lowerLayerIsIpV4 = srcAddr instanceof Inet4Address;
int pseudoHeaderSize = lowerLayerIsIpV4 ? IPV4_PSEUDO_HEADER_SIZE : IPV6_PSEUDO_HEADER_SIZE;
if ((totalLength % 2) != 0) {
data = new byte[totalLength + 1 + pseudoHeaderSize];
destPos = totalLength + 1;
} else {
data = new byte[totalLength + pseudoHeaderSize];
destPos = totalLength;
}
System.arraycopy(header, 0, data, 0, header.length);
System.arraycopy(payload, 0, data, header.length, payload.length);
// pseudo header
System.arraycopy(srcAddr.getAddress(), 0, data, destPos, srcAddr.getAddress().length);
destPos += srcAddr.getAddress().length;
System.arraycopy(dstAddr.getAddress(), 0, data, destPos, dstAddr.getAddress().length);
destPos += dstAddr.getAddress().length;
if (lowerLayerIsIpV4) {
// data[destPos] = (byte)0;
destPos++;
} else {
destPos += 3;
}
data[destPos] = IpNumber.UDP.value();
destPos++;
System.arraycopy(
ByteArrays.toByteArray((short) totalLength), 0, data, destPos, SHORT_SIZE_IN_BYTES);
destPos += SHORT_SIZE_IN_BYTES;
return ByteArrays.calcChecksum(data);
}
@Override
public UdpPort getSrcPort() {
return srcPort;
}
@Override
public UdpPort getDstPort() {
return dstPort;
}
/** @return length */
public short getLength() {
return length;
}
/** @return length */
public int getLengthAsInt() {
return 0xFFFF & length;
}
/** @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(srcPort.value()));
rawFields.add(ByteArrays.toByteArray(dstPort.value()));
rawFields.add(ByteArrays.toByteArray(length));
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 UCP_HEADER_SIZE;
}
@Override
protected String buildString() {
StringBuilder sb = new StringBuilder();
String ls = System.getProperty("line.separator");
sb.append("[UDP Header (").append(length()).append(" bytes)]").append(ls);
sb.append(" Source port: ").append(getSrcPort()).append(ls);
sb.append(" Destination port: ").append(getDstPort()).append(ls);
sb.append(" Length: ").append(getLengthAsInt()).append(" [bytes]").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;
}
UdpHeader other = (UdpHeader) obj;
return checksum == other.checksum
&& length == other.length
&& srcPort.equals(other.srcPort)
&& dstPort.equals(other.dstPort);
}
@Override
protected int calcHashCode() {
int result = 17;
result = 31 * result + srcPort.hashCode();
result = 31 * result + dstPort.hashCode();
result = 31 * result + length;
result = 31 * result + checksum;
return result;
}
}
}
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