    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      https://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.validator.routines;
    018
    019import java.io.Serializable;
    020import java.util.regex.Matcher;
    021import java.util.regex.Pattern;
    022
    023/**
    024 * <p>Perform email validations.</p>
    025 * <p>
    026 * Based on a script by <a href="mailto:stamhankar@hotmail.com">Sandeep V. Tamhankar</a>
    027 * https://javascript.internet.com
    028 * </p>
    029 * <p>
    030 * This implementation is not guaranteed to catch all possible errors in an email address.
    031 * </p>.
    032 *
    033 * @since 1.4
    034 */
    035public class EmailValidator implements Serializable {
    036
    037    private static final long serialVersionUID = 1705927040799295880L;
    038
    039    private static final String SPECIAL_CHARS = "\\p{Cntrl}\\(\\)<>@,;:'\\\\\\\"\\.\\[\\]";
    040    private static final String VALID_CHARS = "(\\\\.)|[^\\s" + SPECIAL_CHARS + "]";
    041    private static final String QUOTED_USER = "(\"(\\\\\"|[^\"])*\")";
    042    private static final String WORD = "((" + VALID_CHARS + "|')+|" + QUOTED_USER + ")";
    043
    044    private static final String EMAIL_REGEX = "^(.+)@(\\S+)$";
    045    private static final String IP_DOMAIN_REGEX = "^\\[(.*)\\]$";
    046    private static final String USER_REGEX = "^" + WORD + "(\\." + WORD + ")*$";
    047
    048    private static final Pattern EMAIL_PATTERN = Pattern.compile(EMAIL_REGEX);
    049    private static final Pattern IP_DOMAIN_PATTERN = Pattern.compile(IP_DOMAIN_REGEX);
    050    private static final Pattern USER_PATTERN = Pattern.compile(USER_REGEX);
    051
    052    private static final int MAX_USERNAME_LEN = 64;
    053
    054    /**
    055     * Singleton instance of this class, which
    056     *  doesn't consider local addresses as valid.
    057     */
    058    private static final EmailValidator EMAIL_VALIDATOR = new EmailValidator(false, false);
    059
    060    /**
    061     * Singleton instance of this class, which
    062     *  doesn't consider local addresses as valid.
    063     */
    064    private static final EmailValidator EMAIL_VALIDATOR_WITH_TLD = new EmailValidator(false, true);
    065
    066    /**
    067     * Singleton instance of this class, which does
    068     *  consider local addresses valid.
    069     */
    070    private static final EmailValidator EMAIL_VALIDATOR_WITH_LOCAL = new EmailValidator(true, false);
    071
    072    /**
    073     * Singleton instance of this class, which does
    074     *  consider local addresses valid.
    075     */
    076    private static final EmailValidator EMAIL_VALIDATOR_WITH_LOCAL_WITH_TLD = new EmailValidator(true, true);
    077
    078    /**
    079     * Returns the Singleton instance of this validator.
    080     *
    081     * @return singleton instance of this validator.
    082     */
    083    public static EmailValidator getInstance() {
    084        return EMAIL_VALIDATOR;
    085    }
    086
    087    /**
    088     * Returns the Singleton instance of this validator,
    089     *  with local validation as required.
    090     *
    091     * @param allowLocal Should local addresses be considered valid?
    092     * @return singleton instance of this validator
    093     */
    094    public static EmailValidator getInstance(final boolean allowLocal) {
    095        return getInstance(allowLocal, false);
    096    }
    097
    098    /**
    099     * Returns the Singleton instance of this validator, with local validation as required.
    100     *
    101     * @param allowLocal Should local addresses be considered valid?
    102     * @param allowTld   Should TLDs be allowed?
    103     * @return singleton instance of this validator
    104     */
    105    public static EmailValidator getInstance(final boolean allowLocal, final boolean allowTld) {
    106        if (allowLocal) {
    107            if (allowTld) {
    108                return EMAIL_VALIDATOR_WITH_LOCAL_WITH_TLD;
    109            }
    110            return EMAIL_VALIDATOR_WITH_LOCAL;
    111        }
    112        if (allowTld) {
    113            return EMAIL_VALIDATOR_WITH_TLD;
    114        }
    115        return EMAIL_VALIDATOR;
    116    }
    117
    118    /**
    119     * Whether to allow TLDs.
    120     */
    121    private final boolean allowTld;
    122
    123    /**
    124     * The domain validator.
    125     */
    126    private final DomainValidator domainValidator;
    127
    128    /**
    129     * Protected constructor for subclasses to use.
    130     *
    131     * @param allowLocal Should local addresses be considered valid?
    132     */
    133    protected EmailValidator(final boolean allowLocal) {
    134        this(allowLocal, false);
    135    }
    136
    137    /**
    138     * Protected constructor for subclasses to use.
    139     *
    140     * @param allowLocal Should local addresses be considered valid?
    141     * @param allowTld Should TLDs be allowed?
    142     */
    143    protected EmailValidator(final boolean allowLocal, final boolean allowTld) {
    144        this.allowTld = allowTld;
    145        this.domainValidator = DomainValidator.getInstance(allowLocal);
    146    }
    147
    148    /**
    149     * constructor for creating instances with the specified domainValidator
    150     *
    151     * @param allowLocal Should local addresses be considered valid?
    152     * @param allowTld Should TLDs be allowed?
    153     * @param domainValidator allow override of the DomainValidator.
    154     * The instance must have the same allowLocal setting.
    155     * @since 1.7
    156     */
    157    public EmailValidator(final boolean allowLocal, final boolean allowTld, final DomainValidator domainValidator) {
    158        this.allowTld = allowTld;
    159        if (domainValidator == null) {
    160            throw new IllegalArgumentException("DomainValidator cannot be null");
    161        }
    162        if (domainValidator.isAllowLocal() != allowLocal) {
    163            throw new IllegalArgumentException("DomainValidator must agree with allowLocal setting");
    164        }
    165        this.domainValidator = domainValidator;
    166    }
    167
    168    /**
    169     * <p>Checks if a field has a valid e-mail address.</p>
    170     *
    171     * @param email The value validation is being performed on.  A {@code null}
    172     *              value is considered invalid.
    173     * @return true if the email address is valid.
    174     */
    175    public boolean isValid(final String email) {
    176        if (email == null || email.endsWith(".")) { // check this first - it's cheap!
    177            return false;
    178        }
    179        // Check the whole email address structure
    180        final Matcher emailMatcher = EMAIL_PATTERN.matcher(email);
    181        if (!emailMatcher.matches()) {
    182            return false;
    183        }
    184        if (!isValidUser(emailMatcher.group(1))) {
    185            return false;
    186        }
    187        if (!isValidDomain(emailMatcher.group(2))) {
    188            return false;
    189        }
    190        return true;
    191    }
    192
    193    /**
    194     * Returns true if the domain component of an email address is valid.
    195     *
    196     * @param domain being validated, may be in IDN format
    197     * @return true if the email address's domain is valid.
    198     */
    199    protected boolean isValidDomain(final String domain) {
    200        // see if domain is an IP address in brackets
    201        final Matcher ipDomainMatcher = IP_DOMAIN_PATTERN.matcher(domain);
    202
    203        if (ipDomainMatcher.matches()) {
    204            final InetAddressValidator inetAddressValidator =
    205                    InetAddressValidator.getInstance();
    206            return inetAddressValidator.isValid(ipDomainMatcher.group(1));
    207        }
    208        // Domain is symbolic name
    209        if (allowTld) {
    210            return domainValidator.isValid(domain) || !domain.startsWith(".") && domainValidator.isValidTld(domain);
    211        }
    212        return domainValidator.isValid(domain);
    213    }
    214
    215    /**
    216     * Returns true if the user component of an email address is valid.
    217     *
    218     * @param user being validated
    219     * @return true if the username is valid.
    220     */
    221    protected boolean isValidUser(final String user) {
    222
    223        if (user == null || user.length() > MAX_USERNAME_LEN) {
    224            return false;
    225        }
    226
    227        return USER_PATTERN.matcher(user).matches();
    228    }
    229
    230}