001/*
002 * Copyright (C) 2009 The Guava Authors
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
017package com.google.common.net;
018
019import com.google.common.annotations.Beta;
020
021import java.net.InetAddress;
022import java.text.ParseException;
023
024import 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
051public 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   * invalid, 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    // TODO(user): different lenient and strict versions of this?
105    final InternetDomainName domain = InternetDomainName.fromLenient(specifier);
106
107    if (domain.hasPublicSuffix()) {
108      return new HostSpecifier(domain.name());
109    }
110
111    throw new IllegalArgumentException(
112        "Domain name does not have a recognized public suffix: " + specifier);
113  }
114
115  /**
116   * Attempts to return a {@code HostSpecifier} for the given string, throwing
117   * an exception if parsing fails. Always use this method in preference to
118   * {@link #fromValid(String)} for a specifier that is not already known to be
119   * valid.
120   *
121   * @throws ParseException if the specifier is not valid.
122   */
123  public static HostSpecifier from(String specifier)
124      throws ParseException {
125    try {
126      return fromValid(specifier);
127    } catch (IllegalArgumentException e) {
128      // Since the IAE can originate at several different points inside
129      // fromValid(), we implement this method in terms of that one rather
130      // than the reverse.
131
132      ParseException parseException =
133          new ParseException("Invalid host specifier: " + specifier, 0);
134      parseException.initCause(e);
135      throw parseException;
136    }
137  }
138
139  /**
140   * Determines whether {@code specifier} represents a valid
141   * {@link HostSpecifier} as described in the documentation for
142   * {@link #fromValid(String)}.
143   */
144  public static boolean isValid(String specifier) {
145    try {
146      fromValid(specifier);
147      return true;
148    } catch (IllegalArgumentException e) {
149      return false;
150    }
151  }
152
153  @Override
154  public boolean equals(@Nullable Object other) {
155    if (this == other) {
156      return true;
157    }
158
159    if (other instanceof HostSpecifier) {
160      final HostSpecifier that = (HostSpecifier) other;
161      return this.canonicalForm.equals(that.canonicalForm);
162    }
163
164    return false;
165  }
166
167  @Override
168  public int hashCode() {
169    return canonicalForm.hashCode();
170  }
171
172  /**
173   * Returns a string representation of the host specifier suitable for
174   * inclusion in a URI.  If the host specifier is a domain name, the
175   * string will be normalized to all lower case.  If the specifier was
176   * an IPv6 address without brackets, brackets are added so that the
177   * result will be usable in the host part of a URI.
178   */
179  @Override
180  public String toString() {
181    return canonicalForm;
182  }
183}