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The core module of Pcap4J.
/*_##########################################################################
_##
_## Copyright (C) 2016-2017 Pcap4J.org
_##
_##########################################################################
*/
package org.pcap4j.packet;
import static org.pcap4j.util.ByteArrays.*;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
import org.pcap4j.util.ByteArrays;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* DNS domain name
*
*
* labels:
* 1 len 1 len
* +-------+-------+-//-+-------+-------+-------+-//-+-------+--//--+-------+
* | len | label | len | label | |len (0)|
* +-------+-------+-//-+-------+-------+-------+-//-+-------+--//--+-------+
*
* pointer:
* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
* | 1 1| OFFSET |
* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
*
*
* @see RFC 1035
* @author Kaito Yamada
* @since pcap4j 1.7.1
*/
public final class DnsDomainName implements Serializable {
/** */
private static final long serialVersionUID = -9123494137779222577L;
private static final Logger LOG = LoggerFactory.getLogger(DnsDomainName.class);
/** The root domain (zero) */
public static final DnsDomainName ROOT_DOMAIN;
static {
try {
ROOT_DOMAIN = new DnsDomainName(new byte[] {0}, 0, 1);
} catch (IllegalRawDataException e) {
throw new AssertionError("Never get here.");
}
}
private final List labels;
private final String name;
private final Short pointer;
/**
* 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 DnsDomainName object.
* @throws IllegalRawDataException if parsing the raw data fails.
*/
public static DnsDomainName newInstance(byte[] rawData, int offset, int length)
throws IllegalRawDataException {
ByteArrays.validateBounds(rawData, offset, length);
return new DnsDomainName(rawData, offset, length);
}
private DnsDomainName(byte[] rawData, int offset, int length) throws IllegalRawDataException {
this.labels = new ArrayList();
int cursor = 0;
Short foundPointer = null;
boolean terminated = false;
while (cursor < length) {
int len = rawData[offset + cursor] & 0xFF;
int flag = len & 0xC0;
if (flag == 0x00) {
if (len == 0) {
terminated = true;
break;
}
cursor++;
if (length - cursor < len) {
StringBuilder sb = new StringBuilder(200);
sb.append("The data is too short to build a DnsDomainName. data: ")
.append(ByteArrays.toHexString(rawData, " "))
.append(", offset: ")
.append(offset)
.append(", length: ")
.append(length)
.append(", cursor: ")
.append(cursor);
throw new IllegalRawDataException(sb.toString());
}
labels.add(new String(rawData, offset + cursor, len));
cursor += len;
continue;
} else if (flag == 0xC0) {
if (length - cursor < SHORT_SIZE_IN_BYTES) {
StringBuilder sb = new StringBuilder(200);
sb.append("The data is too short to build a DnsDomainName. data: ")
.append(ByteArrays.toHexString(rawData, " "))
.append(", offset: ")
.append(offset)
.append(", length: ")
.append(length)
.append(", cursor: ")
.append(cursor);
throw new IllegalRawDataException(sb.toString());
}
foundPointer = (short) (ByteArrays.getShort(rawData, offset + cursor) & 0x3FFF);
terminated = true;
break;
} else {
StringBuilder sb = new StringBuilder(200);
sb.append("A label must start with 00 or 11. data: ")
.append(ByteArrays.toHexString(rawData, " "))
.append(", offset: ")
.append(offset)
.append(", length: ")
.append(length);
throw new IllegalRawDataException(sb.toString());
}
}
this.pointer = foundPointer;
if (!terminated) {
StringBuilder sb = new StringBuilder(200);
sb.append("No null termination nor pointer. data: ")
.append(ByteArrays.toHexString(rawData, " "))
.append(", offset: ")
.append(offset)
.append(", length: ")
.append(length);
throw new IllegalRawDataException(sb.toString());
}
this.name = joinLabels(labels);
}
private DnsDomainName(Builder builder) {
if (builder == null || builder.labels == null) {
StringBuilder sb = new StringBuilder();
sb.append("builder").append(builder).append(" builder.labels: ").append(builder.labels);
throw new NullPointerException(sb.toString());
}
for (String label : builder.labels) {
if (label.getBytes().length > 63) {
throw new IllegalArgumentException(
"Length of a label must be less than 64. label: " + label);
}
}
if (builder.pointer != null && (builder.pointer & 0xC000) != 0) {
throw new IllegalArgumentException(
"(builder.pointer & 0xC000) must be zero. builder.pointer: " + builder.pointer);
}
this.labels = new ArrayList(builder.labels);
this.name = joinLabels(labels);
this.pointer = builder.pointer;
}
private String joinLabels(List lbls) {
if (lbls.size() == 0) {
return "";
}
StringBuilder sb = new StringBuilder();
Iterator iter = lbls.iterator();
while (true) {
sb.append(iter.next());
if (iter.hasNext()) {
sb.append(".");
} else {
break;
}
}
return sb.toString();
}
/** @return labels */
public List getLabels() {
return new ArrayList(labels);
}
/** @return name, which is made by joining labels with "." */
public String getName() {
return name;
}
/** @return pointer (0 - 16383 (inclusive)). May be null. */
public Short getPointer() {
return pointer;
}
/** @return pointer (0 - 16383 (inclusive)). May be null. */
public Integer getPointerAsInt() {
if (pointer != null) {
return (int) pointer;
} else {
return null;
}
}
/**
* @param headerRawData the raw data of the DNS header including this domain name.
* @return decompressed name.
* @throws IllegalRawDataException if an error occurred during decompression or circular reference
* is detected.
*/
public String decompress(byte[] headerRawData) throws IllegalRawDataException {
if (headerRawData == null) {
throw new NullPointerException("headerRawData is null.");
}
return decompress(headerRawData, new ArrayList());
}
private String decompress(byte[] headerRawData, List pointers)
throws IllegalRawDataException {
if (pointer == null) {
return name;
} else {
if (pointers.contains(pointer)) {
StringBuilder sb = new StringBuilder(200);
sb.append("Circular reference detected. data: ")
.append(ByteArrays.toHexString(headerRawData, " "))
.append(", offset: ")
.append(pointer)
.append(", name: ")
.append(name);
throw new IllegalRawDataException(sb.toString());
}
pointers.add(pointer);
StringBuilder sb = new StringBuilder();
sb.append(name)
.append(".")
.append(
new DnsDomainName(headerRawData, pointer, headerRawData.length - pointer)
.decompress(headerRawData, pointers));
return sb.toString();
}
}
/** @return a new Builder object populated with this object's fields. */
public Builder getBuilder() {
return new Builder(this);
}
/** @return the raw data. */
public byte[] getRawData() {
byte[] data = new byte[length()];
int cursor = 0;
for (String label : labels) {
byte[] labelBytes = label.getBytes();
data[cursor] = (byte) labelBytes.length;
cursor++;
System.arraycopy(labelBytes, 0, data, cursor, labelBytes.length);
cursor += labelBytes.length;
}
if (pointer != null) {
byte[] offsetBytes = ByteArrays.toByteArray(pointer);
offsetBytes[0] |= 0xC0;
System.arraycopy(offsetBytes, 0, data, cursor, offsetBytes.length);
}
return data;
}
/** @return length */
public int length() {
int len = 0;
for (String label : labels) {
len += label.length() + 1;
}
if (pointer != null) {
len += 2;
} else {
len++;
}
return len;
}
@Override
public String toString() {
if (labels.size() == 0 && pointer == null) {
return "";
}
if (pointer == null) {
return name;
} else {
StringBuilder sb = new StringBuilder();
sb.append("[name: ").append(name).append(", pointer: ").append(pointer).append("]");
return sb.toString();
}
}
/**
* Convert this object to string representation including all fields info and decompressed domain
* name.
*
* @param headerRawData the raw data of the DNS header including this domain name.
* @return string representation of this object.
*/
public String toString(byte[] headerRawData) {
if (labels.size() == 0 && pointer == null) {
return "";
}
if (pointer == null) {
return name;
} else {
String decompressedName;
try {
decompressedName = decompress(headerRawData);
} catch (IllegalRawDataException e) {
LOG.error("Error occurred during building complete name.", e);
decompressedName = "Error occurred during building complete name";
}
StringBuilder sb = new StringBuilder();
sb.append(decompressedName)
.append(" (name: ")
.append(name)
.append(", pointer: ")
.append(pointer)
.append(")");
return sb.toString();
}
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + name.hashCode();
result = prime * result + ((pointer == null) ? 0 : pointer.hashCode());
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj == null) {
return false;
}
if (getClass() != obj.getClass()) {
return false;
}
DnsDomainName other = (DnsDomainName) obj;
if (!name.equals(other.name)) {
return false;
}
if (pointer == null) {
if (other.pointer != null) {
return false;
}
} else if (!pointer.equals(other.pointer)) {
return false;
}
return true;
}
/**
* @author Kaito Yamada
* @since pcap4j 1.7.1
*/
public static final class Builder {
private List labels;
private Short pointer = null;
/** */
public Builder() {}
private Builder(DnsDomainName obj) {
this.labels = obj.labels;
this.pointer = obj.pointer;
}
/**
* @param labels labels
* @return this Builder object for method chaining.
*/
public Builder labels(List labels) {
this.labels = labels;
return this;
}
/**
* @param labels labels
* @return this Builder object for method chaining.
*/
public Builder labels(String[] labels) {
this.labels = Arrays.asList(labels);
return this;
}
/**
* @param pointer pointer
* @return this Builder object for method chaining.
*/
public Builder pointer(Short pointer) {
this.pointer = pointer;
return this;
}
/** @return a new DnsDomainName object. */
public DnsDomainName build() {
return new DnsDomainName(this);
}
}
}
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