com.google.common.net.InternetDomainName Maven / Gradle / Ivy
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/*
* Copyright (C) 2009 The Guava Authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.common.net;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;
import com.google.common.annotations.Beta;
import com.google.common.annotations.GwtCompatible;
import com.google.common.base.Ascii;
import com.google.common.base.CharMatcher;
import com.google.common.base.Joiner;
import com.google.common.base.Splitter;
import com.google.common.collect.ImmutableList;
import com.google.thirdparty.publicsuffix.PublicSuffixPatterns;
import java.util.List;
import javax.annotation.Nullable;
/**
* An immutable well-formed internet domain name, such as {@code com} or {@code
* foo.co.uk}. Only syntactic analysis is performed; no DNS lookups or other
* network interactions take place. Thus there is no guarantee that the domain
* actually exists on the internet.
*
* One common use of this class is to determine whether a given string is
* likely to represent an addressable domain on the web -- that is, for a
* candidate string {@code "xxx"}, might browsing to {@code "http://xxx/"}
* result in a webpage being displayed? In the past, this test was frequently
* done by determining whether the domain ended with a {@linkplain
* #isPublicSuffix() public suffix} but was not itself a public suffix. However,
* this test is no longer accurate. There are many domains which are both public
* suffixes and addressable as hosts; {@code "uk.com"} is one example. As a
* result, the only useful test to determine if a domain is a plausible web host
* is {@link #hasPublicSuffix()}. This will return {@code true} for many domains
* which (currently) are not hosts, such as {@code "com"}, but given that any
* public suffix may become a host without warning, it is better to err on the
* side of permissiveness and thus avoid spurious rejection of valid sites.
*
*
During construction, names are normalized in two ways:
*
* - ASCII uppercase characters are converted to lowercase.
*
- Unicode dot separators other than the ASCII period ({@code '.'}) are
* converted to the ASCII period.
*
* The normalized values will be returned from {@link #toString()} and
* {@link #parts()}, and will be reflected in the result of
* {@link #equals(Object)}.
*
*
* Internationalized domain names such as {@code 网络.cn} are supported, as
* are the equivalent IDNA
* Punycode-encoded versions.
*
* @author Craig Berry
* @since 5.0
*/
@Beta
@GwtCompatible
public final class InternetDomainName {
private static final CharMatcher DOTS_MATCHER =
CharMatcher.anyOf(".\u3002\uFF0E\uFF61");
private static final Splitter DOT_SPLITTER = Splitter.on('.');
private static final Joiner DOT_JOINER = Joiner.on('.');
/**
* Value of {@link #publicSuffixIndex} which indicates that no public suffix
* was found.
*/
private static final int NO_PUBLIC_SUFFIX_FOUND = -1;
private static final String DOT_REGEX = "\\.";
/**
* Maximum parts (labels) in a domain name. This value arises from
* the 255-octet limit described in
* RFC 2181 part 11 with
* the fact that the encoding of each part occupies at least two bytes
* (dot plus label externally, length byte plus label internally). Thus, if
* all labels have the minimum size of one byte, 127 of them will fit.
*/
private static final int MAX_PARTS = 127;
/**
* Maximum length of a full domain name, including separators, and
* leaving room for the root label. See
* RFC 2181 part 11.
*/
private static final int MAX_LENGTH = 253;
/**
* Maximum size of a single part of a domain name. See
* RFC 2181 part 11.
*/
private static final int MAX_DOMAIN_PART_LENGTH = 63;
/**
* The full domain name, converted to lower case.
*/
private final String name;
/**
* The parts of the domain name, converted to lower case.
*/
private final ImmutableList parts;
/**
* The index in the {@link #parts()} list at which the public suffix begins.
* For example, for the domain name {@code www.google.co.uk}, the value would
* be 2 (the index of the {@code co} part). The value is negative
* (specifically, {@link #NO_PUBLIC_SUFFIX_FOUND}) if no public suffix was
* found.
*/
private final int publicSuffixIndex;
/**
* Constructor used to implement {@link #from(String)}, and from subclasses.
*/
InternetDomainName(String name) {
// Normalize:
// * ASCII characters to lowercase
// * All dot-like characters to '.'
// * Strip trailing '.'
name = Ascii.toLowerCase(DOTS_MATCHER.replaceFrom(name, '.'));
if (name.endsWith(".")) {
name = name.substring(0, name.length() - 1);
}
checkArgument(name.length() <= MAX_LENGTH,
"Domain name too long: '%s':", name);
this.name = name;
this.parts = ImmutableList.copyOf(DOT_SPLITTER.split(name));
checkArgument(parts.size() <= MAX_PARTS,
"Domain has too many parts: '%s'", name);
checkArgument(validateSyntax(parts), "Not a valid domain name: '%s'", name);
this.publicSuffixIndex = findPublicSuffix();
}
/**
* Returns the index of the leftmost part of the public suffix, or -1 if not
* found. Note that the value defined as the "public suffix" may not be a
* public suffix according to {@link #isPublicSuffix()} if the domain ends
* with an excluded domain pattern such as {@code "nhs.uk"}.
*/
private int findPublicSuffix() {
final int partsSize = parts.size();
for (int i = 0; i < partsSize; i++) {
String ancestorName = DOT_JOINER.join(parts.subList(i, partsSize));
if (PublicSuffixPatterns.EXACT.containsKey(ancestorName)) {
return i;
}
// Excluded domains (e.g. !nhs.uk) use the next highest
// domain as the effective public suffix (e.g. uk).
if (PublicSuffixPatterns.EXCLUDED.containsKey(ancestorName)) {
return i + 1;
}
if (matchesWildcardPublicSuffix(ancestorName)) {
return i;
}
}
return NO_PUBLIC_SUFFIX_FOUND;
}
/**
* Returns an instance of {@link InternetDomainName} after lenient
* validation. Specifically, validation against RFC 3490
* ("Internationalizing Domain Names in Applications") is skipped, while
* validation against RFC 1035 is relaxed in
* the following ways:
*
* - Any part containing non-ASCII characters is considered valid.
*
- Underscores ('_') are permitted wherever dashes ('-') are permitted.
*
- Parts other than the final part may start with a digit.
*
*
*
* @param domain A domain name (not IP address)
* @throws IllegalArgumentException if {@code name} is not syntactically valid
* according to {@link #isValid}
* @since 10.0 (previously named {@code fromLenient})
*/
public static InternetDomainName from(String domain) {
return new InternetDomainName(checkNotNull(domain));
}
/**
* Validation method used by {@from} to ensure that the domain name is
* syntactically valid according to RFC 1035.
*
* @return Is the domain name syntactically valid?
*/
private static boolean validateSyntax(List parts) {
final int lastIndex = parts.size() - 1;
// Validate the last part specially, as it has different syntax rules.
if (!validatePart(parts.get(lastIndex), true)) {
return false;
}
for (int i = 0; i < lastIndex; i++) {
String part = parts.get(i);
if (!validatePart(part, false)) {
return false;
}
}
return true;
}
private static final CharMatcher DASH_MATCHER = CharMatcher.anyOf("-_");
private static final CharMatcher PART_CHAR_MATCHER =
CharMatcher.JAVA_LETTER_OR_DIGIT.or(DASH_MATCHER);
/**
* Helper method for {@link #validateSyntax(List)}. Validates that one part of
* a domain name is valid.
*
* @param part The domain name part to be validated
* @param isFinalPart Is this the final (rightmost) domain part?
* @return Whether the part is valid
*/
private static boolean validatePart(String part, boolean isFinalPart) {
// These tests could be collapsed into one big boolean expression, but
// they have been left as independent tests for clarity.
if (part.length() < 1 || part.length() > MAX_DOMAIN_PART_LENGTH) {
return false;
}
/*
* GWT claims to support java.lang.Character's char-classification methods,
* but it actually only works for ASCII. So for now, assume any non-ASCII
* characters are valid. The only place this seems to be documented is here:
* http://osdir.com/ml/GoogleWebToolkitContributors/2010-03/msg00178.html
*
* ASCII characters in the part are expected to be valid per RFC 1035,
* with underscore also being allowed due to widespread practice.
*/
String asciiChars = CharMatcher.ASCII.retainFrom(part);
if (!PART_CHAR_MATCHER.matchesAllOf(asciiChars)) {
return false;
}
// No initial or final dashes or underscores.
if (DASH_MATCHER.matches(part.charAt(0))
|| DASH_MATCHER.matches(part.charAt(part.length() - 1))) {
return false;
}
/*
* Note that we allow (in contravention of a strict interpretation of the
* relevant RFCs) domain parts other than the last may begin with a digit
* (for example, "3com.com"). It's important to disallow an initial digit in
* the last part; it's the only thing that stops an IPv4 numeric address
* like 127.0.0.1 from looking like a valid domain name.
*/
if (isFinalPart && CharMatcher.DIGIT.matches(part.charAt(0))) {
return false;
}
return true;
}
/**
* Returns the individual components of this domain name, normalized to all
* lower case. For example, for the domain name {@code mail.google.com}, this
* method returns the list {@code ["mail", "google", "com"]}.
*/
public ImmutableList parts() {
return parts;
}
/**
* Indicates whether this domain name represents a public suffix, as
* defined by the Mozilla Foundation's
* Public Suffix List (PSL). A public
* suffix is one under which Internet users can directly register names, such
* as {@code com}, {@code co.uk} or {@code pvt.k12.wy.us}. Examples of domain
* names that are not public suffixes include {@code google}, {@code
* google.com} and {@code foo.co.uk}.
*
* @return {@code true} if this domain name appears exactly on the public
* suffix list
* @since 6.0
*/
public boolean isPublicSuffix() {
return publicSuffixIndex == 0;
}
/**
* Indicates whether this domain name ends in a {@linkplain #isPublicSuffix()
* public suffix}, including if it is a public suffix itself. For example,
* returns {@code true} for {@code www.google.com}, {@code foo.co.uk} and
* {@code com}, but not for {@code google} or {@code google.foo}. This is
* the recommended method for determining whether a domain is potentially an
* addressable host.
*
* @since 6.0
*/
public boolean hasPublicSuffix() {
return publicSuffixIndex != NO_PUBLIC_SUFFIX_FOUND;
}
/**
* Returns the {@linkplain #isPublicSuffix() public suffix} portion of the
* domain name, or {@code null} if no public suffix is present.
*
* @since 6.0
*/
public InternetDomainName publicSuffix() {
return hasPublicSuffix() ? ancestor(publicSuffixIndex) : null;
}
/**
* Indicates whether this domain name ends in a {@linkplain #isPublicSuffix()
* public suffix}, while not being a public suffix itself. For example,
* returns {@code true} for {@code www.google.com}, {@code foo.co.uk} and
* {@code bar.ca.us}, but not for {@code google}, {@code com}, or {@code
* google.foo}.
*
* Warning: a {@code false} result from this method does not imply
* that the domain does not represent an addressable host, as many public
* suffixes are also addressable hosts. Use {@link #hasPublicSuffix()} for
* that test.
*
*
This method can be used to determine whether it will probably be
* possible to set cookies on the domain, though even that depends on
* individual browsers' implementations of cookie controls. See
* RFC 2109 for details.
*
* @since 6.0
*/
public boolean isUnderPublicSuffix() {
return publicSuffixIndex > 0;
}
/**
* Indicates whether this domain name is composed of exactly one subdomain
* component followed by a {@linkplain #isPublicSuffix() public suffix}. For
* example, returns {@code true} for {@code google.com} and {@code foo.co.uk},
* but not for {@code www.google.com} or {@code co.uk}.
*
*
Warning: A {@code true} result from this method does not imply
* that the domain is at the highest level which is addressable as a host, as
* many public suffixes are also addressable hosts. For example, the domain
* {@code bar.uk.com} has a public suffix of {@code uk.com}, so it would
* return {@code true} from this method. But {@code uk.com} is itself an
* addressable host.
*
*
This method can be used to determine whether a domain is probably the
* highest level for which cookies may be set, though even that depends on
* individual browsers' implementations of cookie controls. See
* RFC 2109 for details.
*
* @since 6.0
*/
public boolean isTopPrivateDomain() {
return publicSuffixIndex == 1;
}
/**
* Returns the portion of this domain name that is one level beneath the
* public suffix. For example, for {@code x.adwords.google.co.uk} it returns
* {@code google.co.uk}, since {@code co.uk} is a public suffix.
*
*
If {@link #isTopPrivateDomain()} is true, the current domain name
* instance is returned.
*
*
This method should not be used to determine the topmost parent domain
* which is addressable as a host, as many public suffixes are also
* addressable hosts. For example, the domain {@code foo.bar.uk.com} has
* a public suffix of {@code uk.com}, so it would return {@code bar.uk.com}
* from this method. But {@code uk.com} is itself an addressable host.
*
*
This method can be used to determine the probable highest level parent
* domain for which cookies may be set, though even that depends on individual
* browsers' implementations of cookie controls.
*
* @throws IllegalStateException if this domain does not end with a
* public suffix
* @since 6.0
*/
public InternetDomainName topPrivateDomain() {
if (isTopPrivateDomain()) {
return this;
}
checkState(isUnderPublicSuffix(), "Not under a public suffix: %s", name);
return ancestor(publicSuffixIndex - 1);
}
/**
* Indicates whether this domain is composed of two or more parts.
*/
public boolean hasParent() {
return parts.size() > 1;
}
/**
* Returns an {@code InternetDomainName} that is the immediate ancestor of
* this one; that is, the current domain with the leftmost part removed. For
* example, the parent of {@code www.google.com} is {@code google.com}.
*
* @throws IllegalStateException if the domain has no parent, as determined
* by {@link #hasParent}
*/
public InternetDomainName parent() {
checkState(hasParent(), "Domain '%s' has no parent", name);
return ancestor(1);
}
/**
* Returns the ancestor of the current domain at the given number of levels
* "higher" (rightward) in the subdomain list. The number of levels must be
* non-negative, and less than {@code N-1}, where {@code N} is the number of
* parts in the domain.
*
*
TODO: Reasonable candidate for addition to public API.
*/
private InternetDomainName ancestor(int levels) {
return from(DOT_JOINER.join(parts.subList(levels, parts.size())));
}
/**
* Creates and returns a new {@code InternetDomainName} by prepending the
* argument and a dot to the current name. For example, {@code
* InternetDomainName.from("foo.com").child("www.bar")} returns a new
* {@code InternetDomainName} with the value {@code www.bar.foo.com}. Only
* lenient validation is performed, as described {@link #from(String) here}.
*
* @throws NullPointerException if leftParts is null
* @throws IllegalArgumentException if the resulting name is not valid
*/
public InternetDomainName child(String leftParts) {
return from(checkNotNull(leftParts) + "." + name);
}
/**
* Indicates whether the argument is a syntactically valid domain name using
* lenient validation. Specifically, validation against RFC 3490
* ("Internationalizing Domain Names in Applications") is skipped.
*
*
The following two code snippets are equivalent:
*
*
{@code
* domainName = InternetDomainName.isValid(name)
* ? InternetDomainName.from(name)
* : DEFAULT_DOMAIN;}
*
* {@code
* try {
* domainName = InternetDomainName.from(name);
* } catch (IllegalArgumentException e) {
* domainName = DEFAULT_DOMAIN;
* }}
*
* @since 8.0 (previously named {@code isValidLenient})
*/
public static boolean isValid(String name) {
try {
from(name);
return true;
} catch (IllegalArgumentException e) {
return false;
}
}
/**
* Does the domain name match one of the "wildcard" patterns (e.g.
* {@code "*.ar"})?
*/
private static boolean matchesWildcardPublicSuffix(String domain) {
final String[] pieces = domain.split(DOT_REGEX, 2);
return pieces.length == 2 && PublicSuffixPatterns.UNDER.containsKey(pieces[1]);
}
/**
* Returns the domain name, normalized to all lower case.
*/
@Override
public String toString() {
return name;
}
/**
* Equality testing is based on the text supplied by the caller,
* after normalization as described in the class documentation. For
* example, a non-ASCII Unicode domain name and the Punycode version
* of the same domain name would not be considered equal.
*
*/
@Override
public boolean equals(@Nullable Object object) {
if (object == this) {
return true;
}
if (object instanceof InternetDomainName) {
InternetDomainName that = (InternetDomainName) object;
return this.name.equals(that.name);
}
return false;
}
@Override
public int hashCode() {
return name.hashCode();
}
}