/*

 * Copyright (c) 2006, 2012, Oracle and/or its affiliates. All rights reserved.

 * 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.IOException;

import java.util.ArrayList;

import java.util.Collection;

import javax.net.ssl.SSLProtocolException;

/*

 * [RFC5246] The client uses the "signature_algorithms" extension to

 * indicate to the server which signature/hash algorithm pairs may be

 * used in digital signatures.  The "extension_data" field of this

 * extension contains a "supported_signature_algorithms" value.

 *

 *     enum {

 *         none(0), md5(1), sha1(2), sha224(3), sha256(4), sha384(5),

 *         sha512(6), (255)

 *     } HashAlgorithm;

 *

 *     enum { anonymous(0), rsa(1), dsa(2), ecdsa(3), (255) }

 *       SignatureAlgorithm;

 *

 *     struct {

 *           HashAlgorithm hash;

 *           SignatureAlgorithm signature;

 *     } SignatureAndHashAlgorithm;

 *

 *     SignatureAndHashAlgorithm

 *       supported_signature_algorithms<2..2^16-2>;

 */

final class SignatureAlgorithmsExtension extends HelloExtension {

    private Collection<SignatureAndHashAlgorithm> algorithms;

    private int algorithmsLen;  // length of supported_signature_algorithms

    SignatureAlgorithmsExtension(

            Collection<SignatureAndHashAlgorithm> signAlgs) {

        super(ExtensionType.EXT_SIGNATURE_ALGORITHMS);

        algorithms = new ArrayList<SignatureAndHashAlgorithm>(signAlgs);

        algorithmsLen =

            SignatureAndHashAlgorithm.sizeInRecord() * algorithms.size();

    }

    SignatureAlgorithmsExtension(HandshakeInStream s, int len)

                throws IOException {

        super(ExtensionType.EXT_SIGNATURE_ALGORITHMS);

        algorithmsLen = s.getInt16();

        if (algorithmsLen == 0 || algorithmsLen + 2 != len) {

            throw new SSLProtocolException("Invalid " + type + " extension");

        }

        algorithms = new ArrayList<SignatureAndHashAlgorithm>();

        int remains = algorithmsLen;

        int sequence = 0;

        while (remains > 1) {   // needs at least two bytes

            int hash = s.getInt8();         // hash algorithm

            int signature = s.getInt8();    // signature algorithm

            SignatureAndHashAlgorithm algorithm =

                SignatureAndHashAlgorithm.valueOf(hash, signature, ++sequence);

            algorithms.add(algorithm);

            remains -= 2;  // one byte for hash, one byte for signature

        }

        if (remains != 0) {

            throw new SSLProtocolException("Invalid server_name extension");

        }

    }

    Collection<SignatureAndHashAlgorithm> getSignAlgorithms() {

        return algorithms;

    }

    @Override

    int length() {

        return 6 + algorithmsLen;

    }

    @Override

    void send(HandshakeOutStream s) throws IOException {

        s.putInt16(type.id);

        s.putInt16(algorithmsLen + 2);

        s.putInt16(algorithmsLen);

        for (SignatureAndHashAlgorithm algorithm : algorithms) {

            s.putInt8(algorithm.getHashValue());      // HashAlgorithm

            s.putInt8(algorithm.getSignatureValue()); // SignatureAlgorithm

        }

    }

    @Override

    public String toString() {

        StringBuilder sb = new StringBuilder();

        boolean opened = false;

        for (SignatureAndHashAlgorithm signAlg : algorithms) {

            if (opened) {

                sb.append(", " + signAlg.getAlgorithmName());

            } else {

                sb.append(signAlg.getAlgorithmName());

                opened = true;

            }

        }

        return "Extension " + type + ", signature_algorithms: " + sb;

    }

}