/*

 * 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,

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

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package sun.security.ssl;

import java.io.*;

import java.util.*;

import javax.net.ssl.SSLException;

/**

 * A list of CipherSuites. Also maintains the lists of supported and

 * default ciphersuites and supports I/O from handshake streams.

 *

 * Instances of this class are immutable.

 *

 */

final class CipherSuiteList {

    // lists of supported and default enabled ciphersuites

    // created on demand

    private static CipherSuiteList supportedSuites, defaultSuites;

    private final Collection<CipherSuite> cipherSuites;

    private String[] suiteNames;

    // flag indicating whether this list contains any ECC ciphersuites.

    // null if not yet checked.

    private volatile Boolean containsEC;

    // for use by buildAvailableCache() and

    // Handshaker.getKickstartMessage() only

    CipherSuiteList(Collection<CipherSuite> cipherSuites) {

        this.cipherSuites = cipherSuites;

    }

    /**

     * Create a CipherSuiteList with a single element.

     */

    CipherSuiteList(CipherSuite suite) {

        cipherSuites = new ArrayList<CipherSuite>(1);

        cipherSuites.add(suite);

    }

    /**

     * Construct a CipherSuiteList from a array of names. We don't bother

     * to eliminate duplicates.

     *

     * @exception IllegalArgumentException if the array or any of its elements

     * is null or if the ciphersuite name is unrecognized or unsupported

     * using currently installed providers.

     */

    CipherSuiteList(String[] names) {

        if (names == null) {

            throw new IllegalArgumentException("CipherSuites may not be null");

        }

        cipherSuites = new ArrayList<CipherSuite>(names.length);

        // refresh available cache once if a CipherSuite is not available

        // (maybe new JCE providers have been installed)

        boolean refreshed = false;

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

            String suiteName = names[i];

            CipherSuite suite = CipherSuite.valueOf(suiteName);

            if (suite.isAvailable() == false) {

                if (refreshed == false) {

                    // clear the cache so that the isAvailable() call below

                    // does a full check

                    clearAvailableCache();

                    refreshed = true;

                }

                // still missing?

                if (suite.isAvailable() == false) {

                    throw new IllegalArgumentException("Cannot support "

                        + suiteName + " with currently installed providers");

                }

            }

            cipherSuites.add(suite);

        }

    }

    /**

     * Read a CipherSuiteList from a HandshakeInStream in V3 ClientHello

     * format. Does not check if the listed ciphersuites are known or

     * supported.

     */

    CipherSuiteList(HandshakeInStream in) throws IOException {

        byte[] bytes = in.getBytes16();

        if ((bytes.length & 1) != 0) {

            throw new SSLException("Invalid ClientHello message");

        }

        cipherSuites = new ArrayList<CipherSuite>(bytes.length >> 1);

        for (int i = 0; i < bytes.length; i += 2) {

            cipherSuites.add(CipherSuite.valueOf(bytes[i], bytes[i+1]));

        }

    }

    /**

     * Return whether this list contains the given CipherSuite.

     */

    boolean contains(CipherSuite suite) {

        return cipherSuites.contains(suite);

    }

    // Return whether this list contains any ECC ciphersuites

    boolean containsEC() {

        if (containsEC == null) {

            for (CipherSuite c : cipherSuites) {

                switch (c.keyExchange) {

                case K_ECDH_ECDSA:

                case K_ECDH_RSA:

                case K_ECDHE_ECDSA:

                case K_ECDHE_RSA:

                case K_ECDH_ANON:

                    containsEC = true;

                    return true;

                default:

                    break;

                }

            }

            containsEC = false;

        }

        return containsEC;

    }

    /**

     * Return an Iterator for the CipherSuites in this list.

     */

    Iterator<CipherSuite> iterator() {

        return cipherSuites.iterator();

    }

    /**

     * Return a reference to the internal Collection of CipherSuites.

     * The Collection MUST NOT be modified.

     */

    Collection<CipherSuite> collection() {

        return cipherSuites;

    }

    /**

     * Return the number of CipherSuites in this list.

     */

    int size() {

        return cipherSuites.size();

    }

    /**

     * Return an array with the names of the CipherSuites in this list.

     */

    synchronized String[] toStringArray() {

        if (suiteNames == null) {

            suiteNames = new String[cipherSuites.size()];

            int i = 0;

            for (CipherSuite c : cipherSuites) {

                suiteNames[i++] = c.name;

            }

        }

        return suiteNames.clone();

    }

    public String toString() {

        return cipherSuites.toString();

    }

    /**

     * Write this list to an HandshakeOutStream in V3 ClientHello format.

     */

    void send(HandshakeOutStream s) throws IOException {

        byte[] suiteBytes = new byte[cipherSuites.size() * 2];

        int i = 0;

        for (CipherSuite c : cipherSuites) {

            suiteBytes[i] = (byte)(c.id >> 8);

            suiteBytes[i+1] = (byte)c.id;

            i += 2;

        }

        s.putBytes16(suiteBytes);

    }

    /**

     * Clear cache of available ciphersuites. If we support all ciphers

     * internally, there is no need to clear the cache and calling this

     * method has no effect.

     */

    static synchronized void clearAvailableCache() {

        if (CipherSuite.DYNAMIC_AVAILABILITY) {

            supportedSuites = null;

            defaultSuites = null;

            CipherSuite.BulkCipher.clearAvailableCache();

            JsseJce.clearEcAvailable();

        }

    }

    /**

     * Return the list of all available CipherSuites with a priority of

     * minPriority or above.

     * Should be called with the Class lock held.

     */

    private static CipherSuiteList buildAvailableCache(int minPriority) {

        // SortedSet automatically arranges ciphersuites in default

        // preference order

        Set<CipherSuite> cipherSuites = new TreeSet<>();

        Collection<CipherSuite> allowedCipherSuites =

                                    CipherSuite.allowedCipherSuites();

        for (CipherSuite c : allowedCipherSuites) {

            if ((c.allowed == false) || (c.priority < minPriority)) {

                continue;

            }

            if (c.isAvailable()) {

                cipherSuites.add(c);

            }

        }

        return new CipherSuiteList(cipherSuites);

    }

    /**

     * Return supported CipherSuites in preference order.

     */

    static synchronized CipherSuiteList getSupported() {

        if (supportedSuites == null) {

            supportedSuites =

                buildAvailableCache(CipherSuite.SUPPORTED_SUITES_PRIORITY);

        }

        return supportedSuites;

    }

    /**

     * Return default enabled CipherSuites in preference order.

     */

    static synchronized CipherSuiteList getDefault() {

        if (defaultSuites == null) {

            defaultSuites =

                buildAvailableCache(CipherSuite.DEFAULT_SUITES_PRIORITY);

        }

        return defaultSuites;

    }

}