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    1   /*
    2    * Licensed to the Apache Software Foundation (ASF) under one or more
    3    * contributor license agreements.  See the NOTICE file distributed with
    4    * this work for additional information regarding copyright ownership.
    5    * The ASF licenses this file to You under the Apache License, Version 2.0
    6    * (the "License"); you may not use this file except in compliance with
    7    * the License.  You may obtain a copy of the License at
    8    *
    9    *      http://www.apache.org/licenses/LICENSE-2.0
    10   *
    11   * Unless required by applicable law or agreed to in writing, software
    12   * distributed under the License is distributed on an "AS IS" BASIS,
    13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    14   * See the License for the specific language governing permissions and
    15   * limitations under the License.
    16   */
    17  package org.apache.commons.validator;
    18
    19  import org.apache.oro.text.perl.Perl5Util;
    20
    21  /***
    22   * <p>Perform email validations.</p>
    23   * <p>
    24   * This class is a Singleton; you can retrieve the instance via the getInstance() method.
    25   * </p>
    26   * <p>
    27   * Based on a script by <a href="mailto:stamhankar@hotmail.com">Sandeep V. Tamhankar</a>
    28   * http://javascript.internet.com
    29   * </p>
    30   * <p>
    31   * This implementation is not guaranteed to catch all possible errors in an email address.
    32   * For example, an address like nobody@noplace.somedog will pass validator, even though there
    33   * is no TLD "somedog"
    34   * </p>.
    35   *
    36   * @version $Revision: 478560 $ $Date: 2006-11-23 13:09:27 +0000 (Thu, 23 Nov 2006) $
    37   * @since Validator 1.1
    38   */
    39  public class EmailValidator {
    40
    41      private static final String SPECIAL_CHARS = "//000-//037//(//)<>@,;:'//////\"//.//[//]//177";
    42      private static final String VALID_CHARS = "[^//s" + SPECIAL_CHARS + "]";
    43      private static final String QUOTED_USER = "(\"[^\"]*\")";
    44      private static final String ATOM = VALID_CHARS + '+';
    45      private static final String WORD = "((" + VALID_CHARS + "|')+|" + QUOTED_USER + ")";
    46
    47      // Each pattern must be surrounded by /
    48      private static final String LEGAL_ASCII_PATTERN = "/^[//000-//177]+$/";
    49      private static final String EMAIL_PATTERN = "/^(.+)@(.+)$/";
    50      private static final String IP_DOMAIN_PATTERN =
    51              "/^//[(//d{1,3})[.](//d{1,3})[.](//d{1,3})[.](//d{1,3})//]$/";
    52      private static final String TLD_PATTERN = "/^([a-zA-Z]+)$/";
    53
    54      private static final String USER_PATTERN = "/^//s*" + WORD + "(//." + WORD + ")*$/";
    55      private static final String DOMAIN_PATTERN = "/^" + ATOM + "(//." + ATOM + ")*//s*$/";
    56      private static final String ATOM_PATTERN = "/(" + ATOM + ")/";
    57
    58      /***
    59       * Singleton instance of this class.
    60       */
    61      private static final EmailValidator EMAIL_VALIDATOR = new EmailValidator();
    62
    63      /***
    64       * Returns the Singleton instance of this validator.
    65       * @return singleton instance of this validator.
    66       */
    67      public static EmailValidator getInstance() {
    68          return EMAIL_VALIDATOR;
    69      }
    70
    71      /***
    72       * Protected constructor for subclasses to use.
    73       */
    74      protected EmailValidator() {
    75          super();
    76      }
    77
    78      /***
    79       * <p>Checks if a field has a valid e-mail address.</p>
    80       *
    81       * @param email The value validation is being performed on.  A <code>null</code>
    82       * value is considered invalid.
    83       * @return true if the email address is valid.
    84       */
    85      public boolean isValid(String email) {
    86          if (email == null) {
    87              return false;
    88          }
    89
    90          Perl5Util matchAsciiPat = new Perl5Util();
    91          if (!matchAsciiPat.match(LEGAL_ASCII_PATTERN, email)) {
    92              return false;
    93          }
    94
    95          email = stripComments(email);
    96
    97          // Check the whole email address structure
    98          Perl5Util emailMatcher = new Perl5Util();
    99          if (!emailMatcher.match(EMAIL_PATTERN, email)) {
    100             return false;
    101         }
    102
    103         if (email.endsWith(".")) {
    104             return false;
    105         }
    106
    107         if (!isValidUser(emailMatcher.group(1))) {
    108             return false;
    109         }
    110
    111         if (!isValidDomain(emailMatcher.group(2))) {
    112             return false;
    113         }
    114
    115         return true;
    116     }
    117
    118     /***
    119      * Returns true if the domain component of an email address is valid.
    120      * @param domain being validatied.
    121      * @return true if the email address's domain is valid.
    122      */
    123     protected boolean isValidDomain(String domain) {
    124         boolean symbolic = false;
    125         Perl5Util ipAddressMatcher = new Perl5Util();
    126
    127         if (ipAddressMatcher.match(IP_DOMAIN_PATTERN, domain)) {
    128             if (!isValidIpAddress(ipAddressMatcher)) {
    129                 return false;
    130             } else {
    131                 return true;
    132             }
    133         } else {
    134             // Domain is symbolic name
    135             Perl5Util domainMatcher = new Perl5Util();
    136             symbolic = domainMatcher.match(DOMAIN_PATTERN, domain);
    137         }
    138
    139         if (symbolic) {
    140             if (!isValidSymbolicDomain(domain)) {
    141                 return false;
    142             }
    143         } else {
    144             return false;
    145         }
    146
    147         return true;
    148     }
    149
    150     /***
    151      * Returns true if the user component of an email address is valid.
    152      * @param user being validated
    153      * @return true if the user name is valid.
    154      */
    155     protected boolean isValidUser(String user) {
    156         Perl5Util userMatcher = new Perl5Util();
    157         return userMatcher.match(USER_PATTERN, user);
    158     }
    159
    160     /***
    161      * Validates an IP address. Returns true if valid.
    162      * @param ipAddressMatcher Pattren matcher
    163      * @return true if the ip address is valid.
    164      */
    165     protected boolean isValidIpAddress(Perl5Util ipAddressMatcher) {
    166         for (int i = 1; i <= 4; i++) {
    167             String ipSegment = ipAddressMatcher.group(i);
    168             if (ipSegment == null || ipSegment.length() <= 0) {
    169                 return false;
    170             }
    171
    172             int iIpSegment = 0;
    173
    174             try {
    175                 iIpSegment = Integer.parseInt(ipSegment);
    176             } catch(NumberFormatException e) {
    177                 return false;
    178             }
    179
    180             if (iIpSegment > 255) {
    181                 return false;
    182             }
    183
    184         }
    185         return true;
    186     }
    187
    188     /***
    189      * Validates a symbolic domain name.  Returns true if it's valid.
    190      * @param domain symbolic domain name
    191      * @return true if the symbolic domain name is valid.
    192      */
    193     protected boolean isValidSymbolicDomain(String domain) {
    194         String[] domainSegment = new String[10];
    195         boolean match = true;
    196         int i = 0;
    197         Perl5Util atomMatcher = new Perl5Util();
    198         while (match) {
    199             match = atomMatcher.match(ATOM_PATTERN, domain);
    200             if (match) {
    201                 domainSegment[i] = atomMatcher.group(1);
    202                 int l = domainSegment[i].length() + 1;
    203                 domain =
    204                         (l >= domain.length())
    205                         ? ""
    206                         : domain.substring(l);
    207
    208                 i++;
    209             }
    210         }
    211
    212         int len = i;
    213
    214         // Make sure there's a host name preceding the domain.
    215         if (len < 2) {
    216             return false;
    217         }
    218
    219         // TODO: the tld should be checked against some sort of configurable
    220         // list
    221         String tld = domainSegment[len - 1];
    222         if (tld.length() > 1) {
    223             Perl5Util matchTldPat = new Perl5Util();
    224             if (!matchTldPat.match(TLD_PATTERN, tld)) {
    225                 return false;
    226             }
    227         } else {
    228             return false;
    229         }
    230
    231         return true;
    232     }
    233     /***
    234      *   Recursively remove comments, and replace with a single space.  The simpler
    235      *   regexps in the Email Addressing FAQ are imperfect - they will miss escaped
    236      *   chars in atoms, for example.
    237      *   Derived From    Mail::RFC822::Address
    238      * @param emailStr The email address
    239      * @return address with comments removed.
    240     */
    241     protected String stripComments(String emailStr)  {
    242      String input = emailStr;
    243      String result = emailStr;
    244      String commentPat = "s/^((?:[^\"////]|////.)*(?:\"(?:[^\"////]|////.)*\"(?:[^\"////]|\111111////.)*)*)//((?:[^()////]|////.)*//)/$1 /osx";
    245      Perl5Util commentMatcher = new Perl5Util();
    246      result = commentMatcher.substitute(commentPat,input);
    247      // This really needs to be =~ or Perl5Matcher comparison
    248      while (!result.equals(input)) {
    249         input = result;
    250         result = commentMatcher.substitute(commentPat,input);
    251      }
    252      return result;
    253
    254     }
    255 }