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The core module of Pcap4J.
/*_##########################################################################
_##
_## Copyright (C) 2016 Pcap4J.org
_##
_##########################################################################
*/
package org.pcap4j.packet;
import static org.pcap4j.util.ByteArrays.*;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
import org.pcap4j.packet.factory.PacketFactories;
import org.pcap4j.packet.namednumber.LlcNumber;
import org.pcap4j.util.ByteArrays;
/**
* LLC (Logical Link Control) Packet
*
* @see IEEE 802.2
* @author Kaito Yamada
* @since pcap4j 1.6.5
*/
public final class LlcPacket extends AbstractPacket {
/**
*
*/
private static final long serialVersionUID = -4394376906462242290L;
private final LlcHeader 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 LlcPacket object.
* @throws IllegalRawDataException if parsing the raw data fails.
*/
public static LlcPacket newPacket(
byte[] rawData, int offset, int length
) throws IllegalRawDataException {
ByteArrays.validateBounds(rawData, offset, length);
return new LlcPacket(rawData, offset, length);
}
private LlcPacket(
byte[] rawData, int offset, int length
) throws IllegalRawDataException {
this.header = new LlcHeader(rawData, offset, length);
int payloadLength = length - header.length();
if (payloadLength > 0) {
this.payload
= PacketFactories.getFactory(Packet.class, LlcNumber.class)
.newInstance(rawData, offset + header.length(), payloadLength, header.getDsap());
}
else {
this.payload = null;
}
}
private LlcPacket(Builder builder) {
if (
builder == null
|| builder.dsap == null
|| builder.ssap == null
|| builder.control == null
) {
StringBuilder sb = new StringBuilder();
sb.append("builder: ").append(builder)
.append(" builder.dsap: ").append(builder.dsap)
.append(" builder.ssap: ").append(builder.ssap)
.append(" builder.control: ").append(builder.control);
throw new NullPointerException(sb.toString());
}
this.payload = builder.payloadBuilder != null ? builder.payloadBuilder.build() : null;
this.header = new LlcHeader(builder);
}
@Override
public LlcHeader getHeader() {
return header;
}
@Override
public Packet getPayload() {
return payload;
}
@Override
public Builder getBuilder() {
return new Builder(this);
}
/**
* @author Kaito Yamada
* @since pcap4j 1.6.5
*/
public static final class Builder extends AbstractBuilder {
private LlcNumber dsap;
private LlcNumber ssap;
private LlcControl control;
private Packet.Builder payloadBuilder;
/**
*
*/
public Builder() {}
private Builder(LlcPacket packet) {
this.dsap = packet.header.dsap;
this.ssap = packet.header.ssap;
this.control = packet.header.control;
this.payloadBuilder = packet.payload != null ? packet.payload.getBuilder() : null;
}
/**
* @param dsap dsap
* @return this Builder object for method chaining.
*/
public Builder dsap(LlcNumber dsap) {
this.dsap = dsap;
return this;
}
/**
* @param ssap ssap
* @return this Builder object for method chaining.
*/
public Builder ssap(LlcNumber ssap) {
this.ssap = ssap;
return this;
}
/**
* @see LlcControlInformation
* @see LlcControlSupervisory
* @see LlcControlUnnumbered
* @param control control
* @return this Builder object for method chaining.
*/
public Builder control(LlcControl control) {
this.control = control;
return this;
}
@Override
public Builder payloadBuilder(Packet.Builder payloadBuilder) {
this.payloadBuilder = payloadBuilder;
return this;
}
@Override
public Packet.Builder getPayloadBuilder() {
return payloadBuilder;
}
@Override
public LlcPacket build() {
return new LlcPacket(this);
}
}
/**
*
* LLC (Logical Link Control) Header
*
*
* {@code
* 0 15
* +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
* | DSAP ( 8bits) | SSAP (8 bits) |
* +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
* | Control (8 or 16 bits) |
* +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
* }
*
*
* @see IEEE 802.2
* @author Kaito Yamada
* @since pcap4j 1.6.5
*/
public static final class LlcHeader extends AbstractHeader {
/**
*
*/
private static final long serialVersionUID = -6228127495653535606L;
private static final int DSAP_OFFSET
= 0;
private static final int DSAP_SIZE
= BYTE_SIZE_IN_BYTES;
private static final int SSAP_OFFSET
= DSAP_OFFSET + DSAP_SIZE;
private static final int SSAP_SIZE
= BYTE_SIZE_IN_BYTES;
private static final int CONTROL_OFFSET
= SSAP_OFFSET + SSAP_SIZE;
private final LlcNumber dsap;
private final LlcNumber ssap;
private final LlcControl control;
private LlcHeader(
byte[] rawData, int offset, int length
) throws IllegalRawDataException {
if (length < CONTROL_OFFSET + 1) {
StringBuilder sb = new StringBuilder(200);
sb.append("The data is too short to build an LLC header(")
.append(CONTROL_OFFSET + 1)
.append(" bytes). data: ")
.append(ByteArrays.toHexString(rawData, " "))
.append(", offset: ")
.append(offset)
.append(", length: ")
.append(length);
throw new IllegalRawDataException(sb.toString());
}
this.dsap = LlcNumber.getInstance(rawData[DSAP_OFFSET + offset]);
this.ssap = LlcNumber.getInstance(rawData[SSAP_OFFSET + offset]);
byte ctrl = rawData[CONTROL_OFFSET + offset];
if ((ctrl & 0x03) == 0x03) {
this.control = LlcControlUnnumbered.newInstance(ctrl);
}
else {
if (length < CONTROL_OFFSET + 2) {
StringBuilder sb = new StringBuilder(200);
sb.append("The data is too short to build an LLC header(")
.append(CONTROL_OFFSET + 2)
.append(" bytes). data: ")
.append(ByteArrays.toHexString(rawData, " "))
.append(", offset: ")
.append(offset)
.append(", length: ")
.append(length);
throw new IllegalRawDataException(sb.toString());
}
if ((ctrl & 0x03) == 0x01) {
this.control
= LlcControlSupervisory.newInstance(
ByteArrays.getShort(rawData, CONTROL_OFFSET + offset)
);
}
else {
this.control
= LlcControlInformation.newInstance(
ByteArrays.getShort(rawData, CONTROL_OFFSET + offset)
);
}
}
}
private LlcHeader(Builder builder) {
this.dsap = builder.dsap;
this.ssap = builder.ssap;
this.control = builder.control;
}
/**
* @return dsap
*/
public LlcNumber getDsap() {
return dsap;
}
/**
* @return ssap
*/
public LlcNumber getSsap() {
return ssap;
}
/**
* @return an instance of {@link LlcControlInformation}, {@link LlcControlSupervisory}
* or {@link LlcControlUnnumbered}.
*/
public LlcControl getControl() {
return control;
}
@Override
protected List getRawFields() {
List rawFields = new ArrayList();
rawFields.add(ByteArrays.toByteArray(dsap.value()));
rawFields.add(ByteArrays.toByteArray(ssap.value()));
rawFields.add(control.getRawData());
return rawFields;
}
@Override
protected int calcLength() {
return 2 + control.length();
}
@Override
protected String buildString() {
StringBuilder sb = new StringBuilder();
String ls = System.getProperty("line.separator");
sb.append("[Logical Link Control header (")
.append(length())
.append(" bytes)]")
.append(ls);
sb.append(" DSAP: ")
.append(dsap)
.append(ls);
sb.append(" SSAP: ")
.append(ssap)
.append(ls);
sb.append(" Control: ")
.append(control)
.append(ls);
return sb.toString();
}
@Override
public boolean equals(Object obj) {
if (obj == this) { return true; }
if (!this.getClass().isInstance(obj)) { return false; }
LlcHeader other = (LlcHeader)obj;
return
dsap.equals(other.dsap)
&& control.equals(other.control)
&& ssap.equals(other.ssap);
}
@Override
protected int calcHashCode() {
int result = 17;
result = 31 * result + dsap.hashCode();
result = 31 * result + ssap.hashCode();
result = 31 * result + control.hashCode();
return result;
}
}
/**
* The interface representing the Control field of an LLC header.
*
* @author Kaito Yamada
* @since pcap4j 1.6.5
*/
public interface LlcControl extends Serializable {
/**
*
* @return length
*/
public int length();
/**
*
* @return raw data
*/
public byte[] getRawData();
}
}
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