/*

 * Copyright (c) 1996, 2013, 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

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 */

package sun.tools.jar;

import java.io.*;

import java.util.*;

import java.security.*;

import sun.net.www.MessageHeader;

import java.util.Base64;

import sun.security.pkcs.*;

import sun.security.x509.AlgorithmId;

/**

 * <p>A signature file as defined in the <a

 * href="manifest.html">Manifest and Signature Format</a>. It has

 * essentially the same structure as a Manifest file in that it is a

 * set of RFC 822 headers (sections). The first section contains meta

 * data relevant to the entire file (i.e "Signature-Version:1.0") and

 * each subsequent section contains data relevant to specific entries:

 * entry sections.

 *

 * <p>Each entry section contains the name of an entry (which must

 * have a counterpart in the manifest). Like the manifest it contains

 * a hash, the hash of the manifest section corresponding to the

 * name. Since the manifest entry contains the hash of the data, this

 * is equivalent to a signature of the data, plus the attributes of

 * the manifest entry.

 *

 * <p>This signature file format deal with PKCS7 encoded DSA signature

 * block. It should be straightforward to extent to support other

 * algorithms.

 *

 * @author      David Brown

 * @author      Benjamin Renaud */

public class SignatureFile {

    /* Are we debugging? */

    static final boolean debug = false;

    /* list of headers that all pertain to a particular file in the

     * archive */

    private Vector<MessageHeader> entries = new Vector<>();

    /* Right now we only support SHA hashes */

    static final String[] hashes = {"SHA"};

    static final void debug(String s) {

        if (debug)

            System.out.println("sig> " + s);

    }

    /*

     * The manifest we're working with.  */

    private Manifest manifest;

    /*

     * The file name for the file. This is the raw name, i.e. the

     * extention-less 8 character name (such as MYSIGN) which wil be

     * used to build the signature filename (MYSIGN.SF) and the block

     * filename (MYSIGN.DSA) */

    private String rawName;

    /* The digital signature block corresponding to this signature

     * file.  */

    private PKCS7 signatureBlock;

    /**

     * Private constructor which takes a name a given signature

     * file. The name must be extension-less and less or equal to 8

     * character in length.  */

    private SignatureFile(String name) throws JarException {

        entries = new Vector<>();

        if (name != null) {

            if (name.length() > 8 || name.indexOf('.') != -1) {

                throw new JarException("invalid file name");

            }

            rawName = name.toUpperCase(Locale.ENGLISH);

        }

    }

    /**

     * Private constructor which takes a name a given signature file

     * and a new file predicate. If it is a new file, a main header

     * will be added. */

    private SignatureFile(String name, boolean newFile)

    throws JarException {

        this(name);

        if (newFile) {

            MessageHeader globals = new MessageHeader();

            globals.set("Signature-Version", "1.0");

            entries.addElement(globals);

        }

    }

    /**

     * Constructs a new Signature file corresponding to a given

     * Manifest. All entries in the manifest are signed.

     *

     * @param manifest the manifest to use.

     *

     * @param name for this signature file. This should

     * be less than 8 characters, and without a suffix (i.e.

     * without a period in it.

     *

     * @exception JarException if an invalid name is passed in.

     */

    public SignatureFile(Manifest manifest, String name)

    throws JarException {

        this(name, true);

        this.manifest = manifest;

        Enumeration<MessageHeader> enum_ = manifest.entries();

        while (enum_.hasMoreElements()) {

            MessageHeader mh = enum_.nextElement();

            String entryName = mh.findValue("Name");

            if (entryName != null) {

                add(entryName);

            }

        }

    }

    /**

     * Constructs a new Signature file corresponding to a given

     * Manifest. Specific entries in the manifest are signed.

     *

     * @param manifest the manifest to use.

     *

     * @param entries the entries to sign.

     *

     * @param filename for this signature file. This should

     * be less than 8 characters, and without a suffix (i.e.

     * without a period in it.

     *

     * @exception JarException if an invalid name is passed in.

     */

    public SignatureFile(Manifest manifest, String[] entries,

                         String filename)

    throws JarException {

        this(filename, true);

        this.manifest = manifest;

        add(entries);

    }

    /**

     * Construct a Signature file from an input stream.

     *

     * @exception IOException if an invalid name is passed in or if a

     * stream exception occurs.

     */

    public SignatureFile(InputStream is, String filename)

    throws IOException {

        this(filename);

        while (is.available() > 0) {

            MessageHeader m = new MessageHeader(is);

            entries.addElement(m);

        }

    }

   /**

     * Construct a Signature file from an input stream.

     *

     * @exception IOException if an invalid name is passed in or if a

     * stream exception occurs.

     */

    public SignatureFile(InputStream is) throws IOException {

        this(is, null);

    }

    public SignatureFile(byte[] bytes) throws IOException {

        this(new ByteArrayInputStream(bytes));

    }

    /**

     * Returns the name of the signature file, ending with a ".SF"

     * suffix */

    public String getName() {

        return "META-INF/" + rawName + ".SF";

    }

    /**

     * Returns the name of the block file, ending with a block suffix

     * such as ".DSA". */

    public String getBlockName() {

        String suffix = "DSA";

        if (signatureBlock != null) {

            SignerInfo info = signatureBlock.getSignerInfos()[0];

            suffix = info.getDigestEncryptionAlgorithmId().getName();

            String temp = AlgorithmId.getEncAlgFromSigAlg(suffix);

            if (temp != null) suffix = temp;

        }

        return "META-INF/" + rawName + "." + suffix;

    }

    /**

     * Returns the signature block associated with this file.

     */

    public PKCS7 getBlock() {

        return signatureBlock;

    }

    /**

     * Sets the signature block associated with this file.

     */

    public void setBlock(PKCS7 block) {

        this.signatureBlock = block;

    }

    /**

     * Add a set of entries from the current manifest.

     */

    public void add(String[] entries) throws JarException {

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

            add (entries[i]);

        }

    }

    /**

     * Add a specific entry from the current manifest.

     */

    public void add(String entry) throws JarException {

        MessageHeader mh = manifest.getEntry(entry);

        if (mh == null) {

            throw new JarException("entry " + entry + " not in manifest");

        }

        MessageHeader smh;

        try {

            smh = computeEntry(mh);

        } catch (IOException e) {

            throw new JarException(e.getMessage());

        }

        entries.addElement(smh);

    }

    /**

     * Get the entry corresponding to a given name. Returns null if

     *the entry does not exist.

     */

    public MessageHeader getEntry(String name) {

        Enumeration<MessageHeader> enum_ = entries();

        while(enum_.hasMoreElements()) {

            MessageHeader mh = enum_.nextElement();

            if (name.equals(mh.findValue("Name"))) {

                return mh;

            }

        }

        return null;

    }

    /**

     * Returns the n-th entry. The global header is a entry 0.  */

    public MessageHeader entryAt(int n) {

        return entries.elementAt(n);

    }

    /**

     * Returns an enumeration of the entries.

     */

    public Enumeration<MessageHeader> entries() {

        return entries.elements();

    }

    /**

     * Given a manifest entry, computes the signature entry for this

     * manifest entry.

     */

    private MessageHeader computeEntry(MessageHeader mh) throws IOException {

        MessageHeader smh = new MessageHeader();

        String name = mh.findValue("Name");

        if (name == null) {

            return null;

        }

        smh.set("Name", name);

        try {

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

                MessageDigest dig = getDigest(hashes[i]);

                ByteArrayOutputStream baos = new ByteArrayOutputStream();

                PrintStream ps = new PrintStream(baos);

                mh.print(ps);

                byte[] headerBytes = baos.toByteArray();

                byte[] digest = dig.digest(headerBytes);

                smh.set(hashes[i] + "-Digest", Base64.getMimeEncoder().encodeToString(digest));

            }

            return smh;

        } catch (NoSuchAlgorithmException e) {

            throw new JarException(e.getMessage());

        }

    }

    private Hashtable<String, MessageDigest> digests = new Hashtable<>();

    private MessageDigest getDigest(String algorithm)

    throws NoSuchAlgorithmException {

        MessageDigest dig = digests.get(algorithm);

        if (dig == null) {

            dig = MessageDigest.getInstance(algorithm);

            digests.put(algorithm, dig);

        }

        dig.reset();

        return dig;

    }

    /**

     * Add a signature file at current position in a stream

     */

    public void stream(OutputStream os) throws IOException {

        /* the first header in the file should be the global one.

         * It should say "SignatureFile-Version: x.x"; barf if not

         */

        MessageHeader globals = entries.elementAt(0);

        if (globals.findValue("Signature-Version") == null) {

            throw new JarException("Signature file requires " +

                            "Signature-Version: 1.0 in 1st header");

        }

        PrintStream ps = new PrintStream(os);

        globals.print(ps);

        for (int i = 1; i < entries.size(); ++i) {

            MessageHeader mh = entries.elementAt(i);

            mh.print(ps);

        }

    }

}