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// SPDX-License-Identifier: BSD-3-Clause
// Copyright (c) 1999-2004 Brian Wellington ([email protected])
package org.xbill.DNS;
import java.io.IOException;
import java.io.Serializable;
import java.util.Arrays;
import lombok.extern.slf4j.Slf4j;
/**
* A representation of a domain name. It may either be absolute (fully qualified) or relative.
*
* @author Brian Wellington
*/
@Slf4j
public class Name implements Comparable, Serializable {
private static final long serialVersionUID = -6036624806201621219L;
private static final int LABEL_NORMAL = 0;
private static final int LABEL_COMPRESSION = 0xC0;
private static final int LABEL_MASK = 0xC0;
/* The name data */
private byte[] name;
/* Effectively an 8 byte array, where the bytes store per-label offsets. */
private long offsets;
/* Precomputed hashcode. */
private transient int hashcode;
/* The number of labels in this name. */
private int labels;
private static final byte[] emptyLabel = new byte[] {(byte) 0};
private static final byte[] wildLabel = new byte[] {(byte) 1, (byte) '*'};
/** The root name */
public static final Name root;
/** The root name */
public static final Name empty;
/** The maximum length of a Name */
private static final int MAXNAME = 255;
/** The maximum length of a label a Name */
private static final int MAXLABEL = 63;
/** The maximum number of cached offsets, the first offset (always zero) is not stored. */
private static final int MAXOFFSETS = 9;
/* Used to efficiently convert bytes to lowercase */
private static final byte[] lowercase = new byte[256];
/* Used in wildcard names. */
private static final Name wild;
static {
for (int i = 0; i < lowercase.length; i++) {
if (i < 'A' || i > 'Z') {
lowercase[i] = (byte) i;
} else {
lowercase[i] = (byte) (i - 'A' + 'a');
}
}
root = new Name();
root.name = emptyLabel;
root.labels = 1;
empty = new Name();
empty.name = new byte[0];
wild = new Name();
wild.name = wildLabel;
wild.labels = 1;
}
private Name() {}
private void setoffset(int n, int offset) {
if (n == 0 || n >= MAXOFFSETS) {
return;
}
int shift = 8 * (n - 1);
offsets &= ~(0xFFL << shift);
offsets |= (long) offset << shift;
}
private int offset(int n) {
if (n == 0) {
return 0;
}
if (n < 1 || n >= labels) {
throw new IllegalArgumentException("label out of range");
}
if (n < MAXOFFSETS) {
int shift = 8 * (n - 1);
return (int) (offsets >>> shift) & 0xFF;
} else {
int pos = (int) (offsets >>> (8 * (MAXOFFSETS - 2))) & 0xFF;
for (int i = MAXOFFSETS - 1; i < n; i++) {
pos += name[pos] + 1;
}
return pos;
}
}
private static void copy(Name src, Name dst) {
dst.name = src.name;
dst.offsets = src.offsets;
dst.labels = src.labels;
}
private void append(byte[] array, int arrayOffset, int numLabels) throws NameTooLongException {
int length = name == null ? 0 : name.length;
int appendLength = 0;
for (int i = 0, pos = arrayOffset; i < numLabels; i++) {
// add one byte for the label length
int len = array[pos] + 1;
pos += len;
appendLength += len;
}
int newlength = length + appendLength;
if (newlength > MAXNAME) {
throw new NameTooLongException();
}
byte[] newname;
if (name != null) {
newname = Arrays.copyOf(name, newlength);
} else {
newname = new byte[newlength];
}
System.arraycopy(array, arrayOffset, newname, length, appendLength);
name = newname;
for (int i = 0, pos = length; i < numLabels && i < MAXOFFSETS; i++) {
setoffset(labels + i, pos);
pos += newname[pos] + 1;
}
labels += numLabels;
}
private void append(char[] label, int len) throws NameTooLongException {
int destPos = prepareAppend(len);
for (int i = 0; i < len; i++) {
name[destPos + i] = (byte) label[i];
}
}
private int prepareAppend(int len) throws NameTooLongException {
int length = name == null ? 0 : name.length;
// add one byte for the label length
int newlength = length + 1 + len;
if (newlength > MAXNAME) {
throw new NameTooLongException();
}
byte[] newname;
if (name != null) {
newname = Arrays.copyOf(name, newlength);
} else {
newname = new byte[newlength];
}
newname[length] = (byte) len;
name = newname;
setoffset(labels, length);
labels++;
return length + 1;
}
private void appendFromString(String fullName, char[] label, int length)
throws TextParseException {
try {
append(label, length);
} catch (NameTooLongException e) {
throw new TextParseException(fullName, "Name too long", e);
}
}
private void appendFromString(String fullName, byte[] label, int n) throws TextParseException {
try {
append(label, 0, n);
} catch (NameTooLongException e) {
throw new TextParseException(fullName, "Name too long");
}
}
/**
* Create a new name from a string and an origin. This does not automatically make the name
* absolute; it will be absolute if it has a trailing dot or an absolute origin is appended.
*
* @param s The string to be converted
* @param origin If the name is not absolute, the origin to be appended.
* @throws TextParseException The name is invalid.
*/
public Name(String s, Name origin) throws TextParseException {
switch (s) {
case "":
throw new TextParseException("empty name");
case "@":
if (origin == null) {
copy(empty, this);
} else {
copy(origin, this);
}
return;
case ".": // full stop
copy(root, this);
return;
}
int labelstart = -1;
int pos = 0;
char[] label = new char[MAXLABEL];
boolean escaped = false;
int digits = 0;
int intval = 0;
boolean absolute = false;
for (int i = 0; i < s.length(); i++) {
char c = s.charAt(i);
if (c > 0xff) {
throw new TextParseException(s, "Illegal character in name");
}
if (escaped) {
if (c >= '0' && c <= '9' && digits < 3) {
digits++;
intval *= 10;
intval += c - '0';
if (intval > 255) {
throw new TextParseException(s, "bad escape");
}
if (digits < 3) {
continue;
}
c = (char) intval;
} else if (digits > 0 && digits < 3) {
throw new TextParseException(s, "bad escape");
}
if (pos >= MAXLABEL) {
throw new TextParseException(s, "label too long");
}
labelstart = pos;
label[pos++] = c;
escaped = false;
} else if (c == '\\') {
escaped = true;
digits = 0;
intval = 0;
} else if (c == '.') {
if (labelstart == -1) {
throw new TextParseException(s, "invalid empty label");
}
appendFromString(s, label, pos);
labelstart = -1;
pos = 0;
} else {
if (labelstart == -1) {
labelstart = i;
}
if (pos >= MAXLABEL) {
throw new TextParseException(s, "label too long");
}
label[pos++] = c;
}
}
if (digits > 0 && digits < 3 || escaped) {
throw new TextParseException(s, "bad escape");
}
if (labelstart == -1) {
appendFromString(s, emptyLabel, 1);
absolute = true;
} else {
appendFromString(s, label, pos);
}
if (origin != null && !absolute) {
appendFromString(s, origin.name, origin.labels);
}
// A relative name that is MAXNAME octets long is a strange and wonderful thing.
// Not technically in violation, but it can not be used for queries as it needs
// to be made absolute by appending at the very least the empty label at the
// end, which there is no room for. To make life easier for everyone, let's only
// allow Names that are MAXNAME long if they are absolute.
if (!absolute && length() == MAXNAME) {
throw new TextParseException(s, "Name too long");
}
}
/**
* Create a new name from a string. This does not automatically make the name absolute; it will be
* absolute if it has a trailing dot.
*
* @param s The string to be converted
* @throws TextParseException The name is invalid.
*/
public Name(String s) throws TextParseException {
this(s, null);
}
/**
* Create a new name from a string and an origin. This does not automatically make the name
* absolute; it will be absolute if it has a trailing dot or an absolute origin is appended. This
* is identical to the constructor, except that it will avoid creating new objects in some cases.
*
* @param s The string to be converted
* @param origin If the name is not absolute, the origin to be appended.
* @throws TextParseException The name is invalid.
*/
public static Name fromString(String s, Name origin) throws TextParseException {
if (s.equals("@")) {
return origin != null ? origin : empty;
} else if (s.equals(".")) {
return root;
}
return new Name(s, origin);
}
/**
* Create a new name from a string. This does not automatically make the name absolute; it will be
* absolute if it has a trailing dot. This is identical to the constructor, except that it will
* avoid creating new objects in some cases.
*
* @param s The string to be converted
* @throws TextParseException The name is invalid.
*/
public static Name fromString(String s) throws TextParseException {
return fromString(s, null);
}
/**
* Create a new name from a constant string. This should only be used when the name is known to be
* good - that is, when it is constant.
*
* @param s The string to be converted
* @throws IllegalArgumentException The name is invalid.
*/
public static Name fromConstantString(String s) {
try {
return fromString(s, null);
} catch (TextParseException e) {
throw new IllegalArgumentException("Invalid name '" + s + "'");
}
}
/**
* Create a new name from DNS a wire format message
*
* @param in A stream containing the DNS message which is currently positioned at the start of the
* name to be read.
*/
public Name(DNSInput in) throws WireParseException {
int len;
int pos;
boolean done = false;
byte[] label = new byte[MAXLABEL + 1];
boolean savedState = false;
while (!done) {
len = in.readU8();
switch (len & LABEL_MASK) {
case LABEL_NORMAL:
if (len == 0) {
append(emptyLabel, 0, 1);
done = true;
} else {
label[0] = (byte) len;
in.readByteArray(label, 1, len);
append(label, 0, 1);
}
break;
case LABEL_COMPRESSION:
pos = in.readU8();
pos += (len & ~LABEL_MASK) << 8;
log.trace("currently {}, pointer to {}", in.current(), pos);
if (pos >= in.current() - 2) {
throw new WireParseException("bad compression");
}
if (!savedState) {
in.save();
savedState = true;
}
in.jump(pos);
log.trace("current name '{}', seeking to {}", this, pos);
break;
default:
throw new WireParseException("bad label type");
}
}
if (savedState) {
in.restore();
}
}
/**
* Create a new name from DNS wire format
*
* @param b A byte array containing the wire format of the name.
*/
public Name(byte[] b) throws IOException {
this(new DNSInput(b));
}
/**
* Create a new name by removing labels from the beginning of an existing Name
*
* @param src An existing Name
* @param n The number of labels to remove from the beginning in the copy
*/
public Name(Name src, int n) {
if (n > src.labels) {
throw new IllegalArgumentException("attempted to remove too many labels");
}
if (n == src.labels) {
copy(empty, this);
return;
}
labels = src.labels - n;
name = Arrays.copyOfRange(src.name, src.offset(n), src.name.length);
int strippedBytes = src.offset(n);
for (int i = 1; i < MAXOFFSETS && i < labels; i++) {
setoffset(i, src.offset(i + n) - strippedBytes);
}
}
/**
* Creates a new name by concatenating two existing names. If the {@code prefix} name is absolute
* {@code prefix} is returned unmodified.
*
* @param prefix The prefix name. Must be relative.
* @param suffix The suffix name.
* @return The concatenated name.
* @throws NameTooLongException The name is too long.
*/
public static Name concatenate(Name prefix, Name suffix) throws NameTooLongException {
if (prefix.isAbsolute()) {
return prefix;
}
Name newname = new Name();
newname.append(prefix.name, 0, prefix.labels);
newname.append(suffix.name, 0, suffix.labels);
return newname;
}
/**
* If this name is a subdomain of origin, return a new name relative to origin with the same
* value. Otherwise, return the existing name.
*
* @param origin The origin to remove.
* @return The possibly relativized name.
*/
public Name relativize(Name origin) {
if (origin == null || !subdomain(origin)) {
return this;
}
Name newname = new Name();
int length = length() - origin.length();
newname.labels = labels - origin.labels;
newname.offsets = offsets;
newname.name = new byte[length];
System.arraycopy(name, 0, newname.name, 0, length);
return newname;
}
/**
* Generates a new Name with the first n labels replaced by a wildcard
*
* @return The wildcard name
*/
public Name wild(int n) {
if (n < 1) {
throw new IllegalArgumentException("must replace 1 or more labels");
}
try {
Name newname = new Name();
copy(wild, newname);
newname.append(name, offset(n), labels - n);
return newname;
} catch (NameTooLongException e) {
throw new IllegalStateException("Name.wild: concatenate failed");
}
}
/**
* Returns a canonicalized version of the Name (all lowercase). This may be the same name, if the
* input Name is already canonical.
*/
public Name canonicalize() {
boolean canonical = true;
for (byte b : name) {
if (lowercase[b & 0xFF] != b) {
canonical = false;
break;
}
}
if (canonical) {
return this;
}
Name newname = new Name();
newname.offsets = offsets;
newname.labels = labels;
newname.name = new byte[length()];
for (int i = 0; i < newname.name.length; i++) {
newname.name[i] = lowercase[name[i] & 0xFF];
}
return newname;
}
/**
* Generates a new Name to be used when following a DNAME.
*
* @param dname The DNAME record to follow.
* @return The constructed name or {@code null} if this Name is not a subdomain of the {@code
* dname} name.
* @throws NameTooLongException The resulting name is too long.
*/
public Name fromDNAME(DNAMERecord dname) throws NameTooLongException {
Name dnameowner = dname.getName();
Name dnametarget = dname.getTarget();
if (!subdomain(dnameowner)) {
return null;
}
int plabels = labels - dnameowner.labels;
int plength = length() - dnameowner.length();
int dlabels = dnametarget.labels;
int dlength = dnametarget.length();
if (plength + dlength > MAXNAME) {
throw new NameTooLongException();
}
Name newname = new Name();
newname.labels = plabels + dlabels;
newname.name = Arrays.copyOf(name, plength + dlength);
System.arraycopy(dnametarget.name, 0, newname.name, plength, dlength);
for (int i = 0, pos = 0; i < MAXOFFSETS && i < plabels + dlabels; i++) {
newname.setoffset(i, pos);
pos += newname.name[pos] + 1;
}
return newname;
}
/** Is this name a wildcard? */
public boolean isWild() {
if (labels == 0) {
return false;
}
return name[0] == (byte) 1 && name[1] == (byte) '*';
}
/** Is this name absolute? */
public boolean isAbsolute() {
if (labels == 0) {
return false;
}
return name[offset(labels - 1)] == 0;
}
/** The length of the name (in bytes). */
public short length() {
if (labels == 0) {
return 0;
}
return (short) (name.length);
}
/** The number of labels in the name. */
public int labels() {
return labels;
}
/** Is the current Name a subdomain of the specified name? */
public boolean subdomain(Name domain) {
int dlabels = domain.labels;
if (dlabels > labels) {
return false;
}
if (dlabels == labels) {
return equals(domain);
}
return domain.equals(name, offset(labels - dlabels));
}
private String byteString(byte[] array, int pos) {
StringBuilder sb = new StringBuilder();
int len = array[pos++];
for (int i = pos; i < pos + len; i++) {
int b = array[i] & 0xFF;
if (b <= 0x20 || b >= 0x7f) {
sb.append('\\');
if (b < 10) {
sb.append("00");
} else if (b < 100) {
sb.append('0');
}
sb.append(b);
} else if (b == '"' || b == '(' || b == ')' || b == '.' || b == ';' || b == '\\' || b == '@'
|| b == '$') {
sb.append('\\');
sb.append((char) b);
} else {
sb.append((char) b);
}
}
return sb.toString();
}
/**
* Convert a Name to a String
*
* @param omitFinalDot If true, and the name is absolute, omit the final dot.
* @return The representation of this name as a (printable) String.
*/
public String toString(boolean omitFinalDot) {
if (labels == 0) {
return "@";
} else if (labels == 1 && name[0] == 0) {
return ".";
}
StringBuilder sb = new StringBuilder();
for (int label = 0, pos = 0; label < labels; label++) {
int len = name[pos];
if (len == 0) {
if (!omitFinalDot) {
sb.append('.');
}
break;
}
if (label > 0) {
sb.append('.');
}
sb.append(byteString(name, pos));
pos += 1 + len;
}
return sb.toString();
}
/**
* Convert a Name to a String
*
* @return The representation of this name as a (printable) String.
*/
@Override
public String toString() {
return toString(false);
}
/**
* Retrieve the nth label of a Name. This makes a copy of the label; changing this does not change
* the Name. The returned byte array includes the label length as the first byte.
*
* @param n The label to be retrieved. The first label is 0.
*/
public byte[] getLabel(int n) {
int pos = offset(n);
byte len = (byte) (name[pos] + 1);
return Arrays.copyOfRange(name, pos, pos + len);
}
/**
* Convert the nth label in a Name to a String
*
* @param n The label to be converted to a (printable) String. The first label is 0.
*/
public String getLabelString(int n) {
int pos = offset(n);
return byteString(name, pos);
}
/**
* Emit a Name in DNS wire format
*
* @param out The output stream containing the DNS message.
* @param c The compression context, or null of no compression is desired.
* @throws IllegalArgumentException The name is not absolute.
*/
public void toWire(DNSOutput out, Compression c) {
if (!isAbsolute()) {
throw new IllegalArgumentException("toWire() called on non-absolute name");
}
for (int i = 0; i < labels - 1; i++) {
Name tname;
if (i == 0) {
tname = this;
} else {
tname = new Name(this, i);
}
int pos = -1;
if (c != null) {
pos = c.get(tname);
}
if (pos >= 0) {
pos |= LABEL_MASK << 8;
out.writeU16(pos);
return;
} else {
if (c != null) {
c.add(out.current(), tname);
}
int off = offset(i);
out.writeByteArray(name, off, name[off] + 1);
}
}
out.writeU8(0);
}
/**
* Emit a Name in DNS wire format
*
* @throws IllegalArgumentException The name is not absolute.
*/
public byte[] toWire() {
DNSOutput out = new DNSOutput();
toWire(out, null);
return out.toByteArray();
}
/**
* Emit a Name in canonical DNS wire format (all lowercase)
*
* @param out The output stream to which the message is written.
*/
public void toWireCanonical(DNSOutput out) {
byte[] b = toWireCanonical();
out.writeByteArray(b);
}
/**
* Emit a Name in canonical DNS wire format (all lowercase)
*
* @return The canonical form of the name.
*/
public byte[] toWireCanonical() {
if (labels == 0) {
return new byte[0];
}
byte[] b = new byte[name.length];
for (int i = 0, spos = 0, dpos = 0; i < labels; i++) {
int len = name[spos];
b[dpos++] = name[spos++];
for (int j = 0; j < len; j++) {
b[dpos++] = lowercase[name[spos++] & 0xFF];
}
}
return b;
}
/**
* Emit a Name in DNS wire format
*
* @param out The output stream containing the DNS message.
* @param c The compression context, or null of no compression is desired.
* @param canonical If true, emit the name in canonicalized form (all lowercase).
* @throws IllegalArgumentException The name is not absolute.
*/
public void toWire(DNSOutput out, Compression c, boolean canonical) {
if (canonical) {
toWireCanonical(out);
} else {
toWire(out, c);
}
}
private boolean equals(byte[] b, int bpos) {
for (int i = 0, pos = 0; i < labels; i++) {
if (name[pos] != b[bpos]) {
return false;
}
int len = name[pos++];
bpos++;
for (int j = 0; j < len; j++) {
if (lowercase[name[pos++] & 0xFF] != lowercase[b[bpos++] & 0xFF]) {
return false;
}
}
}
return true;
}
/** Are these two Names equivalent? */
@Override
public boolean equals(Object arg) {
if (arg == this) {
return true;
}
if (!(arg instanceof Name)) {
return false;
}
Name other = (Name) arg;
if (other.labels != labels) {
return false;
}
if (other.hashCode() != hashCode()) {
return false;
}
return equals(other.name, 0);
}
/** Computes a hashcode based on the value */
@Override
public int hashCode() {
if (hashcode != 0) {
return hashcode;
}
int code = 0;
for (int i = offset(0); i < name.length; i++) {
code += (code << 3) + (lowercase[name[i] & 0xFF] & 0xFF);
}
hashcode = code;
return hashcode;
}
/**
* Compares this Name to another Object.
*
* @param arg The name to be compared.
* @return The value 0 if the argument is a name equivalent to this name; a value less than 0 if
* the argument is less than this name in the canonical ordering, and a value greater than 0
* if the argument is greater than this name in the canonical ordering.
* @throws ClassCastException if the argument is not a Name.
*/
@Override
public int compareTo(Name arg) {
if (this == arg) {
return 0;
}
int alabels = arg.labels;
int compares = Math.min(labels, alabels);
for (int i = 1; i <= compares; i++) {
int start = offset(labels - i);
int astart = arg.offset(alabels - i);
int length = name[start];
int alength = arg.name[astart];
for (int j = 0; j < length && j < alength; j++) {
int n =
(lowercase[name[j + start + 1] & 0xFF] & 0xFF)
- (lowercase[arg.name[j + astart + 1] & 0xFF] & 0xFF);
if (n != 0) {
return n;
}
}
if (length != alength) {
return length - alength;
}
}
return labels - alabels;
}
}
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