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 * 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
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * 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,
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 *
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package sun.security.ssl;

import java.io.*;
import java.net.*;
import java.util.Date;
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.NoSuchElementException;
import java.util.Vector;
import java.util.Locale;

import javax.net.ssl.SSLSession;
import javax.net.ssl.SSLSessionContext;
import javax.net.ssl.SSLSessionBindingListener;
import javax.net.ssl.SSLSessionBindingEvent;
import javax.net.ssl.SSLPeerUnverifiedException;
import javax.net.ssl.SSLSession;

import sun.security.util.Cache;


final class SSLSessionContextImpl implements SSLSessionContext {
    private Cache sessionCache;         // session cache, session id as key
    private Cache sessionHostPortCache; // session cache, "host:port" as key
    private int cacheLimit;             // the max cache size
    private int timeout;                // timeout in seconds

    private static final Debug debug = Debug.getInstance("ssl");

    // package private
    SSLSessionContextImpl() {
        cacheLimit = getDefaultCacheLimit();    // default cache size
        timeout = 86400;                        // default, 24 hours

        // use soft reference
        sessionCache = Cache.newSoftMemoryCache(cacheLimit, timeout);
        sessionHostPortCache = Cache.newSoftMemoryCache(cacheLimit, timeout);
    }

    
Returns the SSLSession bound to the specified session id.
/**
     * Returns the <code>SSLSession</code> bound to the specified session id.
     */
    public SSLSession getSession(byte[] sessionId) {
        if (sessionId == null) {
            throw new NullPointerException("session id cannot be null");
        }

        SSLSessionImpl sess =
                (SSLSessionImpl)sessionCache.get(new SessionId(sessionId));
        if (!isTimedout(sess)) {
            return sess;
        }

        return null;
    }

    
Returns an enumeration of the active SSL sessions.
/**
     * Returns an enumeration of the active SSL sessions.
     */
    public Enumeration<byte[]> getIds() {
        SessionCacheVisitor scVisitor = new SessionCacheVisitor();
        sessionCache.accept(scVisitor);

        return scVisitor.getSessionIds();
    }

    
Sets the timeout limit for cached SSLSession objects
Note that after reset the timeout, the cached session before
should be timed within the shorter one of the old timeout and the
new timeout.
/**
     * Sets the timeout limit for cached <code>SSLSession</code> objects
     *
     * Note that after reset the timeout, the cached session before
     * should be timed within the shorter one of the old timeout and the
     * new timeout.
     */
    public void setSessionTimeout(int seconds)
                 throws IllegalArgumentException {
        if (seconds < 0) {
            throw new IllegalArgumentException();
        }

        if (timeout != seconds) {
            sessionCache.setTimeout(seconds);
            sessionHostPortCache.setTimeout(seconds);
            timeout = seconds;
        }
    }

    
Gets the timeout limit for cached SSLSession objects
/**
     * Gets the timeout limit for cached <code>SSLSession</code> objects
     */
    public int getSessionTimeout() {
        return timeout;
    }

    
Sets the size of the cache used for storing
SSLSession objects.
/**
     * Sets the size of the cache used for storing
     * <code>SSLSession</code> objects.
     */
    public void setSessionCacheSize(int size)
                 throws IllegalArgumentException {
        if (size < 0)
            throw new IllegalArgumentException();

        if (cacheLimit != size) {
            sessionCache.setCapacity(size);
            sessionHostPortCache.setCapacity(size);
            cacheLimit = size;
        }
    }

    
Gets the size of the cache used for storing
SSLSession objects.
/**
     * Gets the size of the cache used for storing
     * <code>SSLSession</code> objects.
     */
    public int getSessionCacheSize() {
        return cacheLimit;
    }


    // package-private method, used ONLY by ServerHandshaker
    SSLSessionImpl get(byte[] id) {
        return (SSLSessionImpl)getSession(id);
    }

    // package-private method, used ONLY by ClientHandshaker
    SSLSessionImpl get(String hostname, int port) {
        /*
         * If no session caching info is available, we won't
         * get one, so exit before doing a lookup.
         */
        if (hostname == null && port == -1) {
            return null;
        }

        SSLSessionImpl sess =
            (SSLSessionImpl)sessionHostPortCache.get(getKey(hostname, port));
        if (!isTimedout(sess)) {
            return sess;
        }

        return null;
    }

    private String getKey(String hostname, int port) {
        return (hostname + ":" +
            String.valueOf(port)).toLowerCase(Locale.ENGLISH);
    }

    // cache a SSLSession
    //
    // In SunJSSE implementation, a session is created while getting a
    // client hello or a server hello message, and cached while the
    // handshaking finished.
    // Here we time the session from the time it cached instead of the
    // time it created, which is a little longer than the expected. So
    // please do check isTimedout() while getting entry from the cache.
    void put(SSLSessionImpl s) {
        sessionCache.put(s.getSessionId(), s);

        // If no hostname/port info is available, don't add this one.
        if ((s.getPeerHost() != null) && (s.getPeerPort() != -1)) {
            sessionHostPortCache.put(
                getKey(s.getPeerHost(), s.getPeerPort()), s);
        }

        s.setContext(this);
    }

    // package-private method, remove a cached SSLSession
    void remove(SessionId key) {
        SSLSessionImpl s = (SSLSessionImpl)sessionCache.get(key);
        if (s != null) {
            sessionCache.remove(key);
            sessionHostPortCache.remove(
                        getKey(s.getPeerHost(), s.getPeerPort()));
        }
    }

    private int getDefaultCacheLimit() {
        int cacheLimit = 0;
        try {
        String s = java.security.AccessController.doPrivileged(
                new java.security.PrivilegedAction<String>() {
                public String run() {
                    return System.getProperty(
                        "javax.net.ssl.sessionCacheSize");
                }
            });
            cacheLimit = (s != null) ? Integer.valueOf(s).intValue() : 0;
        } catch (Exception e) {
        }

        return (cacheLimit > 0) ? cacheLimit : 0;
    }

    boolean isTimedout(SSLSession sess) {
        if (timeout == 0) {
            return false;
        }

        if ((sess != null) && ((sess.getCreationTime() + timeout * 1000L)
                                        <= (System.currentTimeMillis()))) {
            sess.invalidate();
            return true;
        }

        return false;
    }

    final class SessionCacheVisitor
            implements sun.security.util.Cache.CacheVisitor {
        Vector<byte[]> ids = null;

        // public void visit(java.util.Map<Object, Object> map) {}
        public void visit(java.util.Map<Object, Object> map) {
            ids = new Vector<byte[]>(map.size());

            for (Object key : map.keySet()) {
                SSLSessionImpl value = (SSLSessionImpl)map.get(key);
                if (!isTimedout(value)) {
                    ids.addElement(((SessionId)key).getId());
                }
            }
        }

        public Enumeration<byte[]> getSessionIds() {
            return  ids != null ? ids.elements() :
                                  new Vector<byte[]>().elements();
        }
    }

}