/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you 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 org.apache.shiro.realm.ldap;
  
  import org.apache.shiro.util.StringUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import javax.naming.AuthenticationException;
  import javax.naming.Context;
  import javax.naming.NamingException;
  import javax.naming.ldap.InitialLdapContext;
  import javax.naming.ldap.LdapContext;
  import java.util.HashMap;
  import java.util.Hashtable;
  import java.util.Map;
  
  /**
   * {@link LdapContextFactory} implementation using the default Sun/Oracle JNDI Ldap API, utilizing JNDI
   * environment properties and an {@link javax.naming.InitialContext}.
   * <h2>Configuration</h2>
   * This class basically wraps a default template JNDI environment properties Map.  This properties map is the base
   * configuration template used to acquire JNDI {@link LdapContext} connections at runtime.  The
   * {@link #getLdapContext(Object, Object)} method implementation merges this default template with other properties
   * accessible at runtime only (for example per-method principals and credentials).  The constructed runtime map is the
   * one used to acquire the {@link LdapContext}.
   * <p/>
   * The template can be configured directly via the {@link #getEnvironment()}/{@link #setEnvironment(java.util.Map)}
   * properties directly if necessary, but it is usually more convenient to use the supporting wrapper get/set methods
   * for various environment properties.  These wrapper methods interact with the environment
   * template on your behalf, leaving your configuration cleaner and easier to understand.
   * <p/>
   * For example, consider the following two identical configurations:
   * <pre>
   * [main]
   * ldapRealm = org.apache.shiro.realm.ldap.DefaultLdapRealm
   * ldapRealm.contextFactory.url = ldap://localhost:389
   * ldapRealm.contextFactory.authenticationMechanism = DIGEST-MD5
   * </pre>
   * and
   * <pre>
   * [main]
   * ldapRealm = org.apache.shiro.realm.ldap.DefaultLdapRealm
   * ldapRealm.contextFactory.environment[java.naming.provider.url] = ldap://localhost:389
   * ldapRealm.contextFactory.environment[java.naming.security.authentication] = DIGEST-MD5
   * </pre>
   * As you can see, the 2nd configuration block is a little more difficult to read and also requires knowledge
   * of the underlying JNDI Context property keys.  The first is easier to read and understand.
   * <p/>
   * Note that occasionally it will be necessary to use the latter configuration style to set environment properties
   * where no corresponding wrapper method exists.  In this case, the hybrid approach is still a little easier to read.
   * For example:
   * <pre>
   * [main]
   * ldapRealm = org.apache.shiro.realm.ldap.DefaultLdapRealm
   * ldapRealm.contextFactory.url = ldap://localhost:389
   * ldapRealm.contextFactory.authenticationMechanism = DIGEST-MD5
   * ldapRealm.contextFactory.environment[some.other.obscure.jndi.key] = some value
   * </pre>
   *
   * @since 1.1
   */
  public class JndiLdapContextFactory implements LdapContextFactory {
  
      /*-------------------------------------------
       |             C O N S T A N T S            |
       ===========================================*/
      /**
       * The Sun LDAP property used to enable connection pooling.  This is used in the default implementation
       * to enable LDAP connection pooling.
       */
      protected static final String SUN_CONNECTION_POOLING_PROPERTY = "com.sun.jndi.ldap.connect.pool";
      protected static final String DEFAULT_CONTEXT_FACTORY_CLASS_NAME = "com.sun.jndi.ldap.LdapCtxFactory";
      protected static final String SIMPLE_AUTHENTICATION_MECHANISM_NAME = "simple";
      protected static final String DEFAULT_REFERRAL = "follow";
  
      private static final Logger log = LoggerFactory.getLogger(JndiLdapContextFactory.class);
  
      /*-------------------------------------------
       |    I N S T A N C E   V A R I A B L E S   |
       ============================================*/
      private Map<String, Object> environment;
      private boolean poolingEnabled;
     private String systemPassword;
     private String systemUsername;
 
     /*-------------------------------------------
      |         C O N S T R U C T O R S          |
      ===========================================*/
 
     /**
      * Default no-argument constructor that initializes the backing {@link #getEnvironment() environment template} with
      * the {@link #setContextFactoryClassName(String) contextFactoryClassName} equal to
      * {@code com.sun.jndi.ldap.LdapCtxFactory} (the Sun/Oracle default) and the default
      * {@link #setReferral(String) referral} behavior to {@code follow}.
      */
     public JndiLdapContextFactory() {
         this.environment = new HashMap<String, Object>();
         setContextFactoryClassName(DEFAULT_CONTEXT_FACTORY_CLASS_NAME);
         setReferral(DEFAULT_REFERRAL);
         poolingEnabled = true;
     }
 
     /*-------------------------------------------
      |  A C C E S S O R S / M O D I F I E R S   |
      ===========================================*/
 
     /**
      * Sets the type of LDAP authentication mechanism to use when connecting to the LDAP server.
      * This is a wrapper method for setting the JNDI {@link #getEnvironment() environment template}'s
      * {@link Context#SECURITY_AUTHENTICATION} property.
      * <p/>
      * "none" (i.e. anonymous) and "simple" authentications are supported automatically and don't need to be configured
      * via this property.  However, if you require a different mechanism, such as a SASL or External mechanism, you
      * must configure that explicitly via this property.  See the
      * <a href="http://download-llnw.oracle.com/javase/tutorial/jndi/ldap/auth_mechs.html">JNDI LDAP
      * Authentication Mechanisms</a> for more information.
      *
      * @param authenticationMechanism the type of LDAP authentication to perform.
      * @see <a href="http://download-llnw.oracle.com/javase/tutorial/jndi/ldap/auth_mechs.html">
      *      http://download-llnw.oracle.com/javase/tutorial/jndi/ldap/auth_mechs.html</a>
      */
     public void setAuthenticationMechanism(String authenticationMechanism) {
         setEnvironmentProperty(Context.SECURITY_AUTHENTICATION, authenticationMechanism);
     }
 
     /**
      * Returns the type of LDAP authentication mechanism to use when connecting to the LDAP server.
      * This is a wrapper method for getting the JNDI {@link #getEnvironment() environment template}'s
      * {@link Context#SECURITY_AUTHENTICATION} property.
      * <p/>
      * If this property remains un-configured (i.e. {@code null} indicating the
      * {@link #setAuthenticationMechanism(String)} method wasn't used), this indicates that the default JNDI
      * "none" (anonymous) and "simple" authentications are supported automatically.  Any non-null value returned
      * represents an explicitly configured mechanism (e.g. a SASL or external mechanism). See the
      * <a href="http://download-llnw.oracle.com/javase/tutorial/jndi/ldap/auth_mechs.html">JNDI LDAP
      * Authentication Mechanisms</a> for more information.
      *
      * @return the type of LDAP authentication mechanism to use when connecting to the LDAP server.
      * @see <a href="http://download-llnw.oracle.com/javase/tutorial/jndi/ldap/auth_mechs.html">
      *      http://download-llnw.oracle.com/javase/tutorial/jndi/ldap/auth_mechs.html</a>
      */
     public String getAuthenticationMechanism() {
         return (String) getEnvironmentProperty(Context.SECURITY_AUTHENTICATION);
     }
 
     /**
      * The name of the ContextFactory class to use. This defaults to the SUN LDAP JNDI implementation
      * but can be overridden to use custom LDAP factories.
      * <p/>
      * This is a wrapper method for setting the JNDI environment's {@link Context#INITIAL_CONTEXT_FACTORY} property.
      *
      * @param contextFactoryClassName the context factory that should be used.
      */
     public void setContextFactoryClassName(String contextFactoryClassName) {
         setEnvironmentProperty(Context.INITIAL_CONTEXT_FACTORY, contextFactoryClassName);
     }
 
     /**
      * Sets the name of the ContextFactory class to use. This defaults to the SUN LDAP JNDI implementation
      * but can be overridden to use custom LDAP factories.
      * <p/>
      * This is a wrapper method for getting the JNDI environment's {@link Context#INITIAL_CONTEXT_FACTORY} property.
      *
      * @return the name of the ContextFactory class to use.
      */
     public String getContextFactoryClassName() {
         return (String) getEnvironmentProperty(Context.INITIAL_CONTEXT_FACTORY);
     }
 
     /**
      * Returns the base JNDI environment template to use when acquiring an LDAP connection (an {@link LdapContext}).
      * This property is the base configuration template to use for all connections.  This template is then
      * merged with appropriate runtime values as necessary in the
      * {@link #getLdapContext(Object, Object)} implementation.  The merged environment instance is what is used to
      * acquire the {@link LdapContext} at runtime.
      * <p/>
      * Most other get/set methods in this class act as thin proxy wrappers that interact with this property.  The
      * benefit of using them is you have an easier-to-use configuration mechanism compared to setting map properties
      * based on JNDI context keys.
      *
      * @return the base JNDI environment template to use when acquiring an LDAP connection (an {@link LdapContext})
      */
     public Map getEnvironment() {
         return this.environment;
     }
 
     /**
      * Sets the base JNDI environment template to use when acquiring LDAP connections.  It is typically more common
      * to use the other get/set methods in this class to set individual environment settings rather than use
      * this method, but it is available for advanced users that want full control over the base JNDI environment
      * settings.
      * <p/>
      * Note that this template only represents the base/default environment settings.  It is then merged with
      * appropriate runtime values as necessary in the {@link #getLdapContext(Object, Object)} implementation.
      * The merged environment instance is what is used to acquire the connection ({@link LdapContext}) at runtime.
      *
      * @param env the base JNDI environment template to use when acquiring LDAP connections.
      */
     @SuppressWarnings({"unchecked"})
     public void setEnvironment(Map env) {
         this.environment = env;
     }
 
     /**
      * Returns the environment property value bound under the specified key.
      *
      * @param name the name of the environment property
      * @return the property value or {@code null} if the value has not been set.
      */
     private Object getEnvironmentProperty(String name) {
         return this.environment.get(name);
     }
 
     /**
      * Will apply the value to the environment attribute if and only if the value is not null or empty.  If it is
      * null or empty, the corresponding environment attribute will be removed.
      *
      * @param name  the environment property key
      * @param value the environment property value.  A null/empty value will trigger removal.
      */
     private void setEnvironmentProperty(String name, String value) {
         if (StringUtils.hasText(value)) {
             this.environment.put(name, value);
         } else {
             this.environment.remove(name);
         }
     }
 
     /**
      * Returns whether or not connection pooling should be used when possible and appropriate.  This property is NOT
      * backed by the {@link #getEnvironment() environment template} like most other properties in this class.  It
      * is a flag to indicate that pooling is preferred.  The default value is {@code true}.
      * <p/>
      * However, pooling will only actually be enabled if this property is {@code true} <em>and</em> the connection
      * being created is for the {@link #getSystemUsername() systemUsername} user.  Connection pooling is not used for
      * general authentication attempts by application end-users because the probability of re-use for that same
      * user-specific connection after an authentication attempt is extremely low.
      * <p/>
      * If this attribute is {@code true} and it has been determined that the connection is being made with the
      * {@link #getSystemUsername() systemUsername}, the
      * {@link #getLdapContext(Object, Object)} implementation will set the Sun/Oracle-specific
      * {@code com.sun.jndi.ldap.connect.pool} environment property to &quot;{@code true}&quot;.  This means setting
      * this property is only likely to work if using the Sun/Oracle default context factory class (i.e. not using
      * a custom {@link #getContextFactoryClassName() contextFactoryClassName}).
      *
      * @return whether or not connection pooling should be used when possible and appropriate
      */
     public boolean isPoolingEnabled() {
         return poolingEnabled;
     }
 
     /**
      * Sets whether or not connection pooling should be used when possible and appropriate.  This property is NOT
      * a wrapper to the {@link #getEnvironment() environment template} like most other properties in this class.  It
      * is a flag to indicate that pooling is preferred.  The default value is {@code true}.
      * <p/>
      * However, pooling will only actually be enabled if this property is {@code true} <em>and</em> the connection
      * being created is for the {@link #getSystemUsername() systemUsername} user.  Connection pooling is not used for
      * general authentication attempts by application end-users because the probability of re-use for that same
      * user-specific connection after an authentication attempt is extremely low.
      * <p/>
      * If this attribute is {@code true} and it has been determined that the connection is being made with the
      * {@link #getSystemUsername() systemUsername}, the
      * {@link #getLdapContext(Object, Object)} implementation will set the Sun/Oracle-specific
      * {@code com.sun.jndi.ldap.connect.pool} environment property to &quot;{@code true}&quot;.  This means setting
      * this property is only likely to work if using the Sun/Oracle default context factory class (i.e. not using
      * a custom {@link #getContextFactoryClassName() contextFactoryClassName}).
      *
      * @param poolingEnabled whether or not connection pooling should be used when possible and appropriate
      */
     public void setPoolingEnabled(boolean poolingEnabled) {
         this.poolingEnabled = poolingEnabled;
     }
 
     /**
      * Sets the LDAP referral behavior when creating a connection.  Defaults to {@code follow}.  See the Sun/Oracle LDAP
      * <a href="http://java.sun.com/products/jndi/tutorial/ldap/referral/jndi.html">referral documentation</a> for more.
      *
      * @param referral the referral property.
      * @see <a href="http://java.sun.com/products/jndi/tutorial/ldap/referral/jndi.html">Referrals in JNDI</a>
      */
     public void setReferral(String referral) {
         setEnvironmentProperty(Context.REFERRAL, referral);
     }
 
     /**
      * Returns the LDAP referral behavior when creating a connection.  Defaults to {@code follow}.
      * See the Sun/Oracle LDAP
      * <a href="http://java.sun.com/products/jndi/tutorial/ldap/referral/jndi.html">referral documentation</a> for more.
      *
      * @return the LDAP referral behavior when creating a connection.
      * @see <a href="http://java.sun.com/products/jndi/tutorial/ldap/referral/jndi.html">Referrals in JNDI</a>
      */
     public String getReferral() {
         return (String) getEnvironmentProperty(Context.REFERRAL);
     }
 
     /**
      * The LDAP url to connect to. (e.g. ldap://&lt;ldapDirectoryHostname&gt;:&lt;port&gt;).  This must be configured.
      *
      * @param url the LDAP url to connect to. (e.g. ldap://&lt;ldapDirectoryHostname&gt;:&lt;port&gt;)
      */
     public void setUrl(String url) {
         setEnvironmentProperty(Context.PROVIDER_URL, url);
     }
 
     /**
      * Returns the LDAP url to connect to. (e.g. ldap://&lt;ldapDirectoryHostname&gt;:&lt;port&gt;).
      * This must be configured.
      *
      * @return the LDAP url to connect to. (e.g. ldap://&lt;ldapDirectoryHostname&gt;:&lt;port&gt;)
      */
     public String getUrl() {
         return (String) getEnvironmentProperty(Context.PROVIDER_URL);
     }
 
     /**
      * Sets the password of the {@link #setSystemUsername(String) systemUsername} that will be used when creating an
      * LDAP connection used for authorization queries.
      * <p/>
      * Note that setting this property is not required if the calling LDAP Realm does not perform authorization
      * checks.
      *
      * @param systemPassword the password of the {@link #setSystemUsername(String) systemUsername} that will be used
      *                       when creating an LDAP connection used for authorization queries.
      */
     public void setSystemPassword(String systemPassword) {
         this.systemPassword = systemPassword;
     }
 
     /**
      * Returns the password of the {@link #setSystemUsername(String) systemUsername} that will be used when creating an
      * LDAP connection used for authorization queries.
      * <p/>
      * Note that setting this property is not required if the calling LDAP Realm does not perform authorization
      * checks.
      *
      * @return the password of the {@link #setSystemUsername(String) systemUsername} that will be used when creating an
      *         LDAP connection used for authorization queries.
      */
     public String getSystemPassword() {
         return this.systemPassword;
     }
 
     /**
      * Sets the system username that will be used when creating an LDAP connection used for authorization queries.
      * The user must have the ability to query for authorization data for any application user.
      * <p/>
      * Note that setting this property is not required if the calling LDAP Realm does not perform authorization
      * checks.
      *
      * @param systemUsername the system username that will be used when creating an LDAP connection used for
      *                       authorization queries.
      */
     public void setSystemUsername(String systemUsername) {
         this.systemUsername = systemUsername;
     }
 
     /**
      * Returns the system username that will be used when creating an LDAP connection used for authorization queries.
      * The user must have the ability to query for authorization data for any application user.
      * <p/>
      * Note that setting this property is not required if the calling LDAP Realm does not perform authorization
      * checks.
      *
      * @return the system username that will be used when creating an LDAP connection used for authorization queries.
      */
     public String getSystemUsername() {
         return systemUsername;
     }
 
     /*--------------------------------------------
     |               M E T H O D S               |
     ============================================*/
 
     /**
      * This implementation delegates to {@link #getLdapContext(Object, Object)} using the
      * {@link #getSystemUsername() systemUsername} and {@link #getSystemPassword() systemPassword} properties as
      * arguments.
      *
      * @return the system LdapContext
      * @throws NamingException if there is a problem connecting to the LDAP directory
      */
     public LdapContext getSystemLdapContext() throws NamingException {
         return getLdapContext((Object)getSystemUsername(), getSystemPassword());
     }
 
     /**
      * Deprecated - use {@link #getLdapContext(Object, Object)} instead.  This will be removed before Apache Shiro 2.0.
      *
      * @param username the username to use when creating the connection.
      * @param password the password to use when creating the connection.
      * @return a {@code LdapContext} bound using the given username and password.
      * @throws javax.naming.NamingException if there is an error creating the context.
      * @deprecated the {@link #getLdapContext(Object, Object)} method should be used in all cases to ensure more than
      *             String principals and credentials can be used.  Shiro no longer calls this method - it will be
      *             removed before the 2.0 release.
      */
     @Deprecated
     public LdapContext getLdapContext(String username, String password) throws NamingException {
         return getLdapContext((Object) username, password);
     }
 
     /**
      * Returns {@code true} if LDAP connection pooling should be used when acquiring a connection based on the specified
      * account principal, {@code false} otherwise.
      * <p/>
      * This implementation returns {@code true} only if {@link #isPoolingEnabled()} and the principal equals the
      * {@link #getSystemUsername()}.  The reasoning behind this is that connection pooling is not desirable for
      * general authentication attempts by application end-users because the probability of re-use for that same
      * user-specific connection after an authentication attempt is extremely low.
      *
      * @param principal the principal under which the connection will be made
      * @return {@code true} if LDAP connection pooling should be used when acquiring a connection based on the specified
      *         account principal, {@code false} otherwise.
      */
     protected boolean isPoolingConnections(Object principal) {
         return isPoolingEnabled() && principal != null && principal.equals(getSystemUsername());
     }
 
     /**
      * This implementation returns an LdapContext based on the configured JNDI/LDAP environment configuration.
      * The environnmet (Map) used at runtime is created by merging the default/configured
      * {@link #getEnvironment() environment template} with some runtime values as necessary (e.g. a principal and
      * credential available at runtime only).
      * <p/>
      * After the merged Map instance is created, the LdapContext connection is
      * {@link #createLdapContext(java.util.Hashtable) created} and returned.
      *
      * @param principal   the principal to use when acquiring a connection to the LDAP directory
      * @param credentials the credentials (password, X.509 certificate, etc) to use when acquiring a connection to the
      *                    LDAP directory
      * @return the acquired {@code LdapContext} connection bound using the specified principal and credentials.
      * @throws NamingException
      * @throws IllegalStateException
      */
     public LdapContext getLdapContext(Object principal, Object credentials) throws NamingException,
             IllegalStateException {
 
         String url = getUrl();
         if (url == null) {
             throw new IllegalStateException("An LDAP URL must be specified of the form ldap://<hostname>:<port>");
         }
 
         //copy the environment template into the runtime instance that will be further edited based on
         //the method arguments and other class attributes.
         Hashtable<String, Object> env = new Hashtable<String, Object>(this.environment);
 
         Object authcMech = getAuthenticationMechanism();
         if (authcMech == null && (principal != null || credentials != null)) {
             //authenticationMechanism has not been set, but either a principal and/or credentials were
             //supplied, indicating that at least a 'simple' authentication attempt is indeed occurring - the Shiro
             //end-user just didn't configure it explicitly.  So we set it to be 'simple' here as a convenience;
             //the Sun provider implementation already does this same logic, but by repeating that logic here, we ensure
             //this convenience exists regardless of provider implementation):
             env.put(Context.SECURITY_AUTHENTICATION, SIMPLE_AUTHENTICATION_MECHANISM_NAME);
         }
         if (principal != null) {
             env.put(Context.SECURITY_PRINCIPAL, principal);
         }
         if (credentials != null) {
             env.put(Context.SECURITY_CREDENTIALS, credentials);
         }
 
         boolean pooling = isPoolingConnections(principal);
         if (pooling) {
             env.put(SUN_CONNECTION_POOLING_PROPERTY, "true");
         }
 
         if (log.isDebugEnabled()) {
             log.debug("Initializing LDAP context using URL [{}] and principal [{}] with pooling {}",
                     new Object[]{url, principal, (pooling ? "enabled" : "disabled")});
         }
 
         // validate the config before creating the context
         validateAuthenticationInfo(env);
 
         return createLdapContext(env);
     }
 
     /**
      * Creates and returns a new {@link javax.naming.ldap.InitialLdapContext} instance.  This method exists primarily
      * to support testing where a mock LdapContext can be returned instead of actually creating a connection, but
      * subclasses are free to provide a different implementation if necessary.
      *
      * @param env the JNDI environment settings used to create the LDAP connection
      * @return an LdapConnection
      * @throws NamingException if a problem occurs creating the connection
      */
     protected LdapContext createLdapContext(Hashtable env) throws NamingException {
         return new InitialLdapContext(env, null);
     }
 
 
     /**
      * Validates the configuration in the JNDI <code>environment</code> settings and throws an exception if a problem
      * exists.
      * <p/>
      * This implementation will throw a {@link AuthenticationException} if the authentication mechanism is set to
      * 'simple', the principal is non-empty, and the credentials are empty (as per
      * <a href="http://tools.ietf.org/html/rfc4513#section-5.1.2">rfc4513 section-5.1.2</a>).
      *
      * @param environment the JNDI environment settings to be validated
      * @throws AuthenticationException if a configuration problem is detected
      */
     protected void validateAuthenticationInfo(Hashtable<String, Object> environment)
         throws AuthenticationException
     {
         // validate when using Simple auth both principal and credentials are set
         if(SIMPLE_AUTHENTICATION_MECHANISM_NAME.equals(environment.get(Context.SECURITY_AUTHENTICATION))) {
 
             // only validate credentials if we have a non-empty principal
             if( environment.get(Context.SECURITY_PRINCIPAL) != null &&
                 StringUtils.hasText( String.valueOf( environment.get(Context.SECURITY_PRINCIPAL) ))) {
 
                 Object credentials = environment.get(Context.SECURITY_CREDENTIALS);
 
                 // from the FAQ, we need to check for empty credentials:
                 // http://docs.oracle.com/javase/tutorial/jndi/ldap/faq.html
                 if( credentials == null ||
                     (credentials instanceof byte[] && ((byte[])credentials).length <= 0) || // empty byte[]
                     (credentials instanceof char[] && ((char[])credentials).length <= 0) || // empty char[]
                     (String.class.isInstance(credentials) && !StringUtils.hasText(String.valueOf(credentials)))) {
 
                     throw new javax.naming.AuthenticationException("LDAP Simple authentication requires both a "
                                                                        + "principal and credentials.");
                 }
             }
         }
     }
 
 }