/*

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * particular file as subject to the "Classpath" exception as provided

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 */

package com.sun.jndi.ldap;

import java.io.PrintStream;

import java.io.OutputStream;

import java.util.Hashtable;

import java.util.StringTokenizer;

import javax.naming.ldap.Control;

import javax.naming.NamingException;

import javax.naming.CommunicationException;

import java.security.AccessController;

import java.security.PrivilegedAction;

import com.sun.jndi.ldap.pool.PoolCleaner;

import com.sun.jndi.ldap.pool.Pool;

/**

 * Contains utilities for managing connection pools of LdapClient.

 * Contains method for

 * - checking whether attempted connection creation may be pooled

 * - creating a pooled connection

 * - closing idle connections.

 *

 * If a timeout period has been configured, then it will automatically

 * close and remove idle connections (those that have not been

 * used for the duration of the timeout period).

 *

 * @author Rosanna Lee

 */

public final class LdapPoolManager {

    private static final String DEBUG =

        "com.sun.jndi.ldap.connect.pool.debug";

    public static final boolean debug =

        "all".equalsIgnoreCase(getProperty(DEBUG, null));

    public static final boolean trace = debug ||

        "fine".equalsIgnoreCase(getProperty(DEBUG, null));

    // ---------- System properties for connection pooling

    // Authentication mechanisms of connections that may be pooled

    private static final String POOL_AUTH =

        "com.sun.jndi.ldap.connect.pool.authentication";

    // Protocol types of connections that may be pooled

    private static final String POOL_PROTOCOL =

        "com.sun.jndi.ldap.connect.pool.protocol";

    // Maximum number of identical connections per pool

    private static final String MAX_POOL_SIZE =

        "com.sun.jndi.ldap.connect.pool.maxsize";

    // Preferred number of identical connections per pool

    private static final String PREF_POOL_SIZE =

        "com.sun.jndi.ldap.connect.pool.prefsize";

    // Initial number of identical connections per pool

    private static final String INIT_POOL_SIZE =

        "com.sun.jndi.ldap.connect.pool.initsize";

    // Milliseconds to wait before closing idle connections

    private static final String POOL_TIMEOUT =

        "com.sun.jndi.ldap.connect.pool.timeout";

    // Properties for DIGEST

    private static final String SASL_CALLBACK =

        "java.naming.security.sasl.callback";

    // --------- Constants

    private static final int DEFAULT_MAX_POOL_SIZE = 0;

    private static final int DEFAULT_PREF_POOL_SIZE = 0;

    private static final int DEFAULT_INIT_POOL_SIZE = 1;

    private static final int DEFAULT_TIMEOUT = 0;    // no timeout

    private static final String DEFAULT_AUTH_MECHS = "none simple";

    private static final String DEFAULT_PROTOCOLS = "plain";

    private static final int NONE = 0;    // indices into pools

    private static final int SIMPLE = 1;

    private static final int DIGEST = 2;

    // --------- static fields

    private static final long idleTimeout;// ms to wait before closing idle conn

    private static final int maxSize;     // max num of identical conns/pool

    private static final int prefSize;    // preferred num of identical conns/pool

    private static final int initSize;    // initial num of identical conns/pool

    private static boolean supportPlainProtocol = false;

    private static boolean supportSslProtocol = false;

    // List of pools used for different auth types

    private static final Pool[] pools = new Pool[3];

    static {

        maxSize = getInteger(MAX_POOL_SIZE, DEFAULT_MAX_POOL_SIZE);

        prefSize = getInteger(PREF_POOL_SIZE, DEFAULT_PREF_POOL_SIZE);

        initSize = getInteger(INIT_POOL_SIZE, DEFAULT_INIT_POOL_SIZE);

        idleTimeout = getLong(POOL_TIMEOUT, DEFAULT_TIMEOUT);

        // Determine supported authentication mechanisms

        String str = getProperty(POOL_AUTH, DEFAULT_AUTH_MECHS);

        StringTokenizer parser = new StringTokenizer(str);

        int count = parser.countTokens();

        String mech;

        int p;

        for (int i = 0; i < count; i++) {

            mech = parser.nextToken().toLowerCase();

            if (mech.equals("anonymous")) {

                mech = "none";

            }

            p = findPool(mech);

            if (p >= 0 && pools[p] == null) {

                pools[p] = new Pool(initSize, prefSize, maxSize);

            }

        }

        // Determine supported protocols

        str= getProperty(POOL_PROTOCOL, DEFAULT_PROTOCOLS);

        parser = new StringTokenizer(str);

        count = parser.countTokens();

        String proto;

        for (int i = 0; i < count; i++) {

            proto = parser.nextToken();

            if ("plain".equalsIgnoreCase(proto)) {

                supportPlainProtocol = true;

            } else if ("ssl".equalsIgnoreCase(proto)) {

                supportSslProtocol = true;

            } else {

                // ignore

            }

        }

        if (idleTimeout > 0) {

            // Create cleaner to expire idle connections

            new PoolCleaner(idleTimeout, pools).start();

        }

        if (debug) {

            showStats(System.err);

        }

    }

    // Cannot instantiate one of these

    private LdapPoolManager() {

    }

    /**

     * Find the index of the pool for the specified mechanism. If not

     * one of "none", "simple", "DIGEST-MD5", or "GSSAPI",

     * return -1.

     * @param mech mechanism type

     */

    private static int findPool(String mech) {

        if ("none".equalsIgnoreCase(mech)) {

            return NONE;

        } else if ("simple".equalsIgnoreCase(mech)) {

            return SIMPLE;

        } else if ("digest-md5".equalsIgnoreCase(mech)) {

            return DIGEST;

        }

        return -1;

    }

    /**

     * Determines whether pooling is allowed given information on how

     * the connection will be used.

     *

     * Non-configurable rejections:

     * - nonstandard socketFactory has been specified: the pool manager

     *   cannot track input or parameters used by the socket factory and

     *   thus has no way of determining whether two connection requests

     *   are equivalent. Maybe in the future it might add a list of allowed

     *   socket factories to be configured

     * - trace enabled (except when debugging)

     * - for Digest authentication, if a callback handler has been specified:

     *  the pool manager cannot track input collected by the handler

     *  and thus has no way of determining whether two connection requests are

     *  equivalent. Maybe in the future it might add a list of allowed

     *  callback handlers.

     *

     * Configurable tests:

     * - Pooling for the requested protocol (plain or ssl) is supported

     * - Pooling for the requested authentication mechanism is supported

     *

     */

    static boolean isPoolingAllowed(String socketFactory, OutputStream trace,

        String authMech, String protocol, Hashtable env)

                throws NamingException {

        if (trace != null && !debug

                // Requesting plain protocol but it is not supported

                || (protocol == null && !supportPlainProtocol)

                // Requesting ssl protocol but it is not supported

                || ("ssl".equalsIgnoreCase(protocol) && !supportSslProtocol)) {

            d("Pooling disallowed due to tracing or unsupported pooling of protocol");

            return false;

        }

        // pooling of custom socket factory is possible only if the

        // socket factory interface implements java.util.comparator

        String COMPARATOR = "java.util.Comparator";

        boolean foundSockCmp = false;

        if ((socketFactory != null) &&

             !socketFactory.equals(LdapCtx.DEFAULT_SSL_FACTORY)) {

            try {

                Class socketFactoryClass = Obj.helper.loadClass(socketFactory);

                Class[] interfaces = socketFactoryClass.getInterfaces();

                for (int i = 0; i < interfaces.length; i++) {

                    if (interfaces[i].getCanonicalName().equals(COMPARATOR)) {

                        foundSockCmp = true;

                    }

                }

            } catch (Exception e) {

                CommunicationException ce =

                    new CommunicationException("Loading the socket factory");

                ce.setRootCause(e);

                throw ce;

            }

            if (!foundSockCmp) {

                return false;

            }

        }

        // Cannot use pooling if authMech is not a supported mechs

        // Cannot use pooling if authMech contains multiple mechs

        int p = findPool(authMech);

        if (p < 0 || pools[p] == null) {

            d("authmech not found: ", authMech);

            return false;

        }

        d("using authmech: ", authMech);

        switch (p) {

        case NONE:

        case SIMPLE:

            return true;

        case DIGEST:

            // Provider won't be able to determine connection identity

            // if an alternate callback handler is used

            return (env == null || env.get(SASL_CALLBACK) == null);

        }

        return false;

    }

    /**

     * Obtains a pooled connection that either already exists or is

     * newly created using the parameters supplied. If it is newly

     * created, it needs to go through the authentication checks to

     * determine whether an LDAP bind is necessary.

     *

     * Caller needs to invoke ldapClient.authenticateCalled() to

     * determine whether ldapClient.authenticate() needs to be invoked.

     * Caller has that responsibility because caller needs to deal

     * with the LDAP bind response, which might involve referrals,

     * response controls, errors, etc. This method is responsible only

     * for establishing the connection.

     *

     * @return an LdapClient that is pooled.

     */

    static LdapClient getLdapClient(String host, int port, String socketFactory,

        int connTimeout, int readTimeout, OutputStream trace, int version,

        String authMech, Control[] ctls, String protocol, String user,

        Object passwd, Hashtable env) throws NamingException {

        // Create base identity for LdapClient

        ClientId id = null;

        Pool pool;

        int p = findPool(authMech);

        if (p < 0 || (pool=pools[p]) == null) {

            throw new IllegalArgumentException(

                "Attempting to use pooling for an unsupported mechanism: " +

                authMech);

        }

        switch (p) {

        case NONE:

            id = new ClientId(version, host, port, protocol,

                        ctls, trace, socketFactory);

            break;

        case SIMPLE:

            // Add identity information used in simple authentication

            id = new SimpleClientId(version, host, port, protocol,

                ctls, trace, socketFactory, user, passwd);

            break;

        case DIGEST:

            // Add user/passwd/realm/authzid/qop/strength/maxbuf/mutual/policy*

            id = new DigestClientId(version, host, port, protocol,

                ctls, trace, socketFactory, user, passwd, env);

            break;

        }

        return (LdapClient) pool.getPooledConnection(id, connTimeout,

            new LdapClientFactory(host, port, socketFactory, connTimeout,

                                readTimeout, trace));

    }

    public static void showStats(PrintStream out) {

        out.println("***** start *****");

        out.println("idle timeout: " + idleTimeout);

        out.println("maximum pool size: " + maxSize);

        out.println("preferred pool size: " + prefSize);

        out.println("initial pool size: " + initSize);

        out.println("protocol types: " + (supportPlainProtocol ? "plain " : "") +

            (supportSslProtocol ? "ssl" : ""));

        out.println("authentication types: " +

            (pools[NONE] != null ? "none " : "") +

            (pools[SIMPLE] != null ? "simple " : "") +

            (pools[DIGEST] != null ? "DIGEST-MD5 " : ""));

        for (int i = 0; i < pools.length; i++) {

            if (pools[i] != null) {

                out.println(

                    (i == NONE ? "anonymous pools" :

                        i == SIMPLE ? "simple auth pools" :

                        i == DIGEST ? "digest pools" : "")

                            + ":");

                pools[i].showStats(out);

            }

        }

        out.println("***** end *****");

    }

    /**

     * Closes idle connections idle since specified time.

     *

     * @param threshold Close connections idle since this time, as

     * specified in milliseconds since "the epoch".

     * @see java.util.Date

     */

    public static void expire(long threshold) {

        for (int i = 0; i < pools.length; i++) {

            if (pools[i] != null) {

                pools[i].expire(threshold);

            }

        }

    }

    private static void d(String msg) {

        if (debug) {

            System.err.println("LdapPoolManager: " + msg);

        }

    }

    private static void d(String msg, String o) {

        if (debug) {

            System.err.println("LdapPoolManager: " + msg + o);

        }

    }

    private static final String getProperty(final String propName,

        final String defVal) {

        return (String) AccessController.doPrivileged(

            new PrivilegedAction() {

            public Object run() {

                try {

                    return System.getProperty(propName, defVal);

                } catch (SecurityException e) {

                    return defVal;

                }

            }

        });

    }

    private static final int getInteger(final String propName,

        final int defVal) {

        Integer val = (Integer) AccessController.doPrivileged(

            new PrivilegedAction() {

            public Object run() {

                try {

                    return Integer.getInteger(propName, defVal);

                } catch (SecurityException e) {

                    return new Integer(defVal);

                }

            }

        });

        return val.intValue();

    }

    private static final long getLong(final String propName,

        final long defVal) {

        Long val = (Long) AccessController.doPrivileged(

            new PrivilegedAction() {

            public Object run() {

                try {

                    return Long.getLong(propName, defVal);

                } catch (SecurityException e) {

                    return new Long(defVal);

                }

            }

        });

        return val.longValue();

    }

}