001 /*
002 * Copyright (C) 2009 Google Inc.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017 package com.google.common.net;
018
019 import com.google.common.annotations.Beta;
020
021 import java.net.InetAddress;
022 import java.text.ParseException;
023
024 import javax.annotation.Nullable;
025
026 /**
027 * A syntactically valid host specifier, suitable for use in a URI.
028 * This may be either a numeric IP address in IPv4 or IPv6 notation, or a
029 * domain name.
030 *
031 * <p>Because this class is intended to represent host specifiers which can
032 * reasonably be used in a URI, the domain name case is further restricted to
033 * include only those domain names which end in a recognized public suffix; see
034 * {@link InternetDomainName#isPublicSuffix()} for details.
035 *
036 * <p>Note that no network lookups are performed by any {@code HostSpecifier}
037 * methods. No attempt is made to verify that a provided specifier corresponds
038 * to a real or accessible host. Only syntactic and pattern-based checks are
039 * performed.
040 *
041 * <p>If you know that a given string represents a numeric IP address, use
042 * {@link InetAddresses} to obtain and manipulate a
043 * {@link java.net.InetAddress} instance from it rather than using this class.
044 * Similarly, if you know that a given string represents a domain name, use
045 * {@link InternetDomainName} rather than this class.
046 *
047 * @author Craig Berry
048 * @since 5
049 */
050 @Beta
051 public final class HostSpecifier {
052
053 private final String canonicalForm;
054
055 private HostSpecifier(String canonicalForm) {
056 this.canonicalForm = canonicalForm;
057 }
058
059 /**
060 * Returns a {@code HostSpecifier} built from the provided {@code specifier},
061 * which is already known to be valid. If the {@code specifier} might be
062 * valid, use {@link #from(String)} instead.
063 *
064 * <p>The specifier must be in one of these formats:
065 * <ul>
066 * <li>A domain name, like {@code google.com}
067 * <li>A IPv4 address string, like {@code 127.0.0.1}
068 * <li>An IPv6 address string with or without brackets, like
069 * {@code [2001:db8::1]} or {@code 2001:db8::1}
070 * <li>An IPv6 address string enclosed in square brackets, like
071 * {[2001:db8::1]}
072 * </ul>
073 *
074 * @throws IllegalArgumentException if the specifier is not valid.
075 */
076 public static HostSpecifier fromValid(String specifier) {
077 // First, try to interpret the specifier as an IP address. Note we build
078 // the address rather than using the .is* methods because we want to
079 // use InetAddresses.toUriString to convert the result to a string in
080 // canonical form.
081
082 InetAddress addr = null;
083
084 try {
085 addr = InetAddresses.forString(specifier);
086 } catch (IllegalArgumentException e) {
087 // It is not an IPv4 or bracketless IPv6 specifier
088 }
089
090 if (addr == null) {
091 try {
092 addr = InetAddresses.forUriString(specifier);
093 } catch (IllegalArgumentException e) {
094 // It is not a bracketed IPv6 specifier
095 }
096 }
097
098 if (addr != null) {
099 return new HostSpecifier(InetAddresses.toUriString(addr));
100 }
101
102 // It is not any kind of IP address; must be a domain name or invalid.
103
104 final InternetDomainName domain = InternetDomainName.from(specifier);
105
106 if (domain.isUnderPublicSuffix()) {
107 return new HostSpecifier(domain.name());
108 }
109
110 throw new IllegalArgumentException(
111 "Domain name not under a recognized TLD: " + specifier);
112 }
113
114 /**
115 * Attempts to return a {@code HostSpecifier} for the given string, throwing
116 * an exception if parsing fails. Always use this method in preference to
117 * {@link #fromValid(String)} for a specifier that is not already known to be
118 * valid.
119 *
120 * @throws ParseException if the specifier is not valid.
121 */
122 public static HostSpecifier from(String specifier)
123 throws ParseException {
124 try {
125 return fromValid(specifier);
126 } catch (IllegalArgumentException e) {
127 // Since the IAE can originate at several different points inside
128 // fromValid(), we implement this method in terms of that one rather
129 // than the reverse.
130
131 throw new ParseException("Invalid host specifier: " + specifier, 0);
132 }
133 }
134
135 /**
136 * Determines whether {@code specifier} represents a valid
137 * {@link HostSpecifier} as described in the documentation for
138 * {@link #fromValid(String)}.
139 */
140 public static boolean isValid(String specifier) {
141 try {
142 fromValid(specifier);
143 return true;
144 } catch (IllegalArgumentException e) {
145 return false;
146 }
147 }
148
149 @Override
150 public boolean equals(@Nullable Object other) {
151 if (this == other) {
152 return true;
153 }
154
155 if (other instanceof HostSpecifier) {
156 final HostSpecifier that = (HostSpecifier) other;
157 return this.canonicalForm.equals(that.canonicalForm);
158 }
159
160 return false;
161 }
162
163 @Override
164 public int hashCode() {
165 return canonicalForm.hashCode();
166 }
167
168 /**
169 * Returns a string representation of the host specifier suitable for
170 * inclusion in a URI. If the host specifier is a domain name, the
171 * string will be normalized to all lower case. If the specifier was
172 * an IPv6 address without brackets, brackets are added so that the
173 * result will be usable in the host part of a URI.
174 */
175 @Override
176 public String toString() {
177 return canonicalForm;
178 }
179 }