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, as mandated by
* RFC 1123.
*
*
*
* @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.javaLetterOrDigit().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();
}
}