/*

 * Copyright 1996-2006 Sun Microsystems, Inc.  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.  Sun designates this

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

 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package sun.security.util;

import java.io.*;

import java.math.BigInteger;

import java.util.Date;

/**

 * Represents a single DER-encoded value.  DER encoding rules are a subset

 * of the "Basic" Encoding Rules (BER), but they only support a single way

 * ("Definite" encoding) to encode any given value.

 *

 * <P>All DER-encoded data are triples <em>{type, length, data}</em>.  This

 * class represents such tagged values as they have been read (or constructed),

 * and provides structured access to the encoded data.

 *

 * <P>At this time, this class supports only a subset of the types of DER

 * data encodings which are defined.  That subset is sufficient for parsing

 * most X.509 certificates, and working with selected additional formats

 * (such as PKCS #10 certificate requests, and some kinds of PKCS #7 data).

 *

 * A note with respect to T61/Teletex strings: From RFC 1617, section 4.1.3

 * and RFC 3280, section 4.1.2.4., we assume that this kind of string will

 * contain ISO-8859-1 characters only.

 *

 *

 * @author David Brownell

 * @author Amit Kapoor

 * @author Hemma Prafullchandra

 */

public class DerValue {

    /** The tag class types */

    public static final byte TAG_UNIVERSAL = (byte)0x000;

    public static final byte TAG_APPLICATION = (byte)0x040;

    public static final byte TAG_CONTEXT = (byte)0x080;

    public static final byte TAG_PRIVATE = (byte)0x0c0;

    /** The DER tag of the value; one of the tag_ constants. */

    public byte                 tag;

    protected DerInputBuffer    buffer;

    /**

     * The DER-encoded data of the value.

     */

    public final DerInputStream data;

    private int                 length;

    /*

     * The type starts at the first byte of the encoding, and

     * is one of these tag_* values.  That may be all the type

     * data that is needed.

     */

    /*

     * These tags are the "universal" tags ... they mean the same

     * in all contexts.  (Mask with 0x1f -- five bits.)

     */

    /** Tag value indicating an ASN.1 "BOOLEAN" value. */

    public final static byte    tag_Boolean = 0x01;

    /** Tag value indicating an ASN.1 "INTEGER" value. */

    public final static byte    tag_Integer = 0x02;

    /** Tag value indicating an ASN.1 "BIT STRING" value. */

    public final static byte    tag_BitString = 0x03;

    /** Tag value indicating an ASN.1 "OCTET STRING" value. */

    public final static byte    tag_OctetString = 0x04;

    /** Tag value indicating an ASN.1 "NULL" value. */

    public final static byte    tag_Null = 0x05;

    /** Tag value indicating an ASN.1 "OBJECT IDENTIFIER" value. */

    public final static byte    tag_ObjectId = 0x06;

    /** Tag value including an ASN.1 "ENUMERATED" value */

    public final static byte    tag_Enumerated = 0x0A;

    /** Tag value indicating an ASN.1 "UTF8String" value. */

    public final static byte    tag_UTF8String = 0x0C;

    /** Tag value including a "printable" string */

    public final static byte    tag_PrintableString = 0x13;

    /** Tag value including a "teletype" string */

    public final static byte    tag_T61String = 0x14;

    /** Tag value including an ASCII string */

    public final static byte    tag_IA5String = 0x16;

    /** Tag value indicating an ASN.1 "UTCTime" value. */

    public final static byte    tag_UtcTime = 0x17;

    /** Tag value indicating an ASN.1 "GeneralizedTime" value. */

    public final static byte    tag_GeneralizedTime = 0x18;

    /** Tag value indicating an ASN.1 "GenerallString" value. */

    public final static byte    tag_GeneralString = 0x1B;

    /** Tag value indicating an ASN.1 "UniversalString" value. */

    public final static byte    tag_UniversalString = 0x1C;

    /** Tag value indicating an ASN.1 "BMPString" value. */

    public final static byte    tag_BMPString = 0x1E;

    // CONSTRUCTED seq/set

    /**

     * Tag value indicating an ASN.1

     * "SEQUENCE" (zero to N elements, order is significant).

     */

    public final static byte    tag_Sequence = 0x30;

    /**

     * Tag value indicating an ASN.1

     * "SEQUENCE OF" (one to N elements, order is significant).

     */

    public final static byte    tag_SequenceOf = 0x30;

    /**

     * Tag value indicating an ASN.1

     * "SET" (zero to N members, order does not matter).

     */

    public final static byte    tag_Set = 0x31;

    /**

     * Tag value indicating an ASN.1

     * "SET OF" (one to N members, order does not matter).

     */

    public final static byte    tag_SetOf = 0x31;

    /*

     * These values are the high order bits for the other kinds of tags.

     */

    /**

     * Returns true if the tag class is UNIVERSAL.

     */

    public boolean isUniversal()      { return ((tag & 0x0c0) == 0x000); }

    /**

     * Returns true if the tag class is APPLICATION.

     */

    public boolean isApplication()    { return ((tag & 0x0c0) == 0x040); }

    /**

     * Returns true iff the CONTEXT SPECIFIC bit is set in the type tag.

     * This is associated with the ASN.1 "DEFINED BY" syntax.

     */

    public boolean isContextSpecific() { return ((tag & 0x0c0) == 0x080); }

    /**

     * Returns true iff the CONTEXT SPECIFIC TAG matches the passed tag.

     */

    public boolean isContextSpecific(byte cntxtTag) {

        if (!isContextSpecific()) {

            return false;

        }

        return ((tag & 0x01f) == cntxtTag);

    }

    boolean isPrivate()        { return ((tag & 0x0c0) == 0x0c0); }

    /** Returns true iff the CONSTRUCTED bit is set in the type tag. */

    public boolean isConstructed()    { return ((tag & 0x020) == 0x020); }

    /**

     * Returns true iff the CONSTRUCTED TAG matches the passed tag.

     */

    public boolean isConstructed(byte constructedTag) {

        if (!isConstructed()) {

            return false;

        }

        return ((tag & 0x01f) == constructedTag);

    }

    /**

     * Creates a PrintableString or UTF8string DER value from a string

     */

    public DerValue(String value) throws IOException {

        boolean isPrintableString = true;

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

            if (!isPrintableStringChar(value.charAt(i))) {

                isPrintableString = false;

                break;

            }

        }

        data = init(isPrintableString ? tag_PrintableString : tag_UTF8String, value);

    }

    /**

     * Creates a string type DER value from a String object

     * @param stringTag the tag for the DER value to create

     * @param value the String object to use for the DER value

     */

    public DerValue(byte stringTag, String value) throws IOException {

        data = init(stringTag, value);

    }

    /**

     * Creates a DerValue from a tag and some DER-encoded data.

     *

     * @param tag the DER type tag

     * @param data the DER-encoded data

     */

    public DerValue(byte tag, byte[] data) {

        this.tag = tag;

        buffer = new DerInputBuffer(data.clone());

        length = data.length;

        this.data = new DerInputStream(buffer);

        this.data.mark(Integer.MAX_VALUE);

    }

    /*

     * package private

     */

    DerValue(DerInputBuffer in) throws IOException {

        // XXX must also parse BER-encoded constructed

        // values such as sequences, sets...

        tag = (byte)in.read();

        byte lenByte = (byte)in.read();

        length = DerInputStream.getLength((lenByte & 0xff), in);

        if (length == -1) {  // indefinite length encoding found

            DerInputBuffer inbuf = in.dup();

            int readLen = inbuf.available();

            int offset = 2;     // for tag and length bytes

            byte[] indefData = new byte[readLen + offset];

            indefData[0] = tag;

            indefData[1] = lenByte;

            DataInputStream dis = new DataInputStream(inbuf);

            dis.readFully(indefData, offset, readLen);

            dis.close();

            DerIndefLenConverter derIn = new DerIndefLenConverter();

            inbuf = new DerInputBuffer(derIn.convert(indefData));

            if (tag != inbuf.read())

                throw new IOException

                        ("Indefinite length encoding not supported");

            length = DerInputStream.getLength(inbuf);

            buffer = inbuf.dup();

            buffer.truncate(length);

            data = new DerInputStream(buffer);

            // indefinite form is encoded by sending a length field with a

            // length of 0. - i.e. [1000|0000].

            // the object is ended by sending two zero bytes.

            in.skip(length + offset);

        } else {

            buffer = in.dup();

            buffer.truncate(length);

            data = new DerInputStream(buffer);

            in.skip(length);

        }

    }

    /**

     * Get an ASN.1/DER encoded datum from a buffer.  The

     * entire buffer must hold exactly one datum, including

     * its tag and length.

     *

     * @param buf buffer holding a single DER-encoded datum.

     */

    public DerValue(byte[] buf) throws IOException {

        data = init(true, new ByteArrayInputStream(buf));

    }

    /**

     * Get an ASN.1/DER encoded datum from part of a buffer.

     * That part of the buffer must hold exactly one datum, including

     * its tag and length.

     *

     * @param buf the buffer

     * @param offset start point of the single DER-encoded dataum

     * @param length how many bytes are in the encoded datum

     */

    public DerValue(byte[] buf, int offset, int len) throws IOException {

        data = init(true, new ByteArrayInputStream(buf, offset, len));

    }

    /**

     * Get an ASN1/DER encoded datum from an input stream.  The

     * stream may have additional data following the encoded datum.

     * In case of indefinite length encoded datum, the input stream

     * must hold only one datum.

     *

     * @param in the input stream holding a single DER datum,

     *  which may be followed by additional data

     */

    public DerValue(InputStream in) throws IOException {

        data = init(false, in);

    }

    private DerInputStream init(byte stringTag, String value) throws IOException {

        String enc = null;

        tag = stringTag;

        switch (stringTag) {

        case tag_PrintableString:

        case tag_IA5String:

        case tag_GeneralString:

            enc = "ASCII";

            break;

        case tag_T61String:

            enc = "ISO-8859-1";

            break;

        case tag_BMPString:

            enc = "UnicodeBigUnmarked";

            break;

        case tag_UTF8String:

            enc = "UTF8";

            break;

            // TBD: Need encoder for UniversalString before it can

            // be handled.

        default:

            throw new IllegalArgumentException("Unsupported DER string type");

        }

        byte[] buf = value.getBytes(enc);

        length = buf.length;

        buffer = new DerInputBuffer(buf);

        DerInputStream result = new DerInputStream(buffer);

        result.mark(Integer.MAX_VALUE);

        return result;

    }

    /*

     * helper routine

     */

    private DerInputStream init(boolean fullyBuffered, InputStream in)

            throws IOException {

        tag = (byte)in.read();

        byte lenByte = (byte)in.read();

        length = DerInputStream.getLength((lenByte & 0xff), in);

        if (length == -1) { // indefinite length encoding found

            int readLen = in.available();

            int offset = 2;     // for tag and length bytes

            byte[] indefData = new byte[readLen + offset];

            indefData[0] = tag;

            indefData[1] = lenByte;

            DataInputStream dis = new DataInputStream(in);

            dis.readFully(indefData, offset, readLen);

            dis.close();

            DerIndefLenConverter derIn = new DerIndefLenConverter();

            in = new ByteArrayInputStream(derIn.convert(indefData));

            if (tag != in.read())

                throw new IOException

                        ("Indefinite length encoding not supported");

            length = DerInputStream.getLength(in);

        }

        if (length == 0)

            return null;

        if (fullyBuffered && in.available() != length)

            throw new IOException("extra data given to DerValue constructor");

        byte[] bytes = new byte[length];

        // n.b. readFully not needed in normal fullyBuffered case

        DataInputStream dis = new DataInputStream(in);

        dis.readFully(bytes);

        buffer = new DerInputBuffer(bytes);

        return new DerInputStream(buffer);

    }

    /**

     * Encode an ASN1/DER encoded datum onto a DER output stream.

     */

    public void encode(DerOutputStream out)

    throws IOException {

        out.write(tag);

        out.putLength(length);

        // XXX yeech, excess copies ... DerInputBuffer.write(OutStream)

        if (length > 0) {

            byte[] value = new byte[length];

            // always synchronized on data

            synchronized (data) {

                buffer.reset();

                if (buffer.read(value) != length) {

                    throw new IOException("short DER value read (encode)");

                }

                out.write(value);

            }

        }

    }

    public final DerInputStream getData() {

        return data;

    }

    public final byte getTag() {

        return tag;

    }

    /**

     * Returns an ASN.1 BOOLEAN

     *

     * @return the boolean held in this DER value

     */

    public boolean getBoolean() throws IOException {

        if (tag != tag_Boolean) {

            throw new IOException("DerValue.getBoolean, not a BOOLEAN " + tag);

        }

        if (length != 1) {

            throw new IOException("DerValue.getBoolean, invalid length "

                                        + length);

        }

        if (buffer.read() != 0) {

            return true;

        }

        return false;

    }

    /**

     * Returns an ASN.1 OBJECT IDENTIFIER.

     *

     * @return the OID held in this DER value

     */

    public ObjectIdentifier getOID() throws IOException {

        if (tag != tag_ObjectId)

            throw new IOException("DerValue.getOID, not an OID " + tag);

        return new ObjectIdentifier(buffer);

    }

    private byte[] append(byte[] a, byte[] b) {

        if (a == null)

            return b;

        byte[] ret = new byte[a.length + b.length];

        System.arraycopy(a, 0, ret, 0, a.length);

        System.arraycopy(b, 0, ret, a.length, b.length);

        return ret;

    }

    /**

     * Returns an ASN.1 OCTET STRING

     *

     * @return the octet string held in this DER value

     */

    public byte[] getOctetString() throws IOException {

        byte[] bytes;

        if (tag != tag_OctetString && !isConstructed(tag_OctetString)) {

            throw new IOException(

                "DerValue.getOctetString, not an Octet String: " + tag);

        }

        bytes = new byte[length];

        if (buffer.read(bytes) != length)

            throw new IOException("short read on DerValue buffer");

        if (isConstructed()) {

            DerInputStream in = new DerInputStream(bytes);

            bytes = null;

            while (in.available() != 0) {

                bytes = append(bytes, in.getOctetString());

            }

        }

        return bytes;

    }

    /**

     * Returns an ASN.1 INTEGER value as an integer.

     *

     * @return the integer held in this DER value.

     */

    public int getInteger() throws IOException {

        if (tag != tag_Integer) {

            throw new IOException("DerValue.getInteger, not an int " + tag);

        }

        return buffer.getInteger(data.available());

    }

    /**

     * Returns an ASN.1 INTEGER value as a BigInteger.

     *

     * @return the integer held in this DER value as a BigInteger.

     */

    public BigInteger getBigInteger() throws IOException {

        if (tag != tag_Integer)

            throw new IOException("DerValue.getBigInteger, not an int " + tag);

        return buffer.getBigInteger(data.available(), false);

    }

    /**

     * Returns an ASN.1 INTEGER value as a positive BigInteger.

     * This is just to deal with implementations that incorrectly encode

     * some values as negative.

     *

     * @return the integer held in this DER value as a BigInteger.

     */

    public BigInteger getPositiveBigInteger() throws IOException {

        if (tag != tag_Integer)

            throw new IOException("DerValue.getBigInteger, not an int " + tag);

        return buffer.getBigInteger(data.available(), true);

    }

    /**

     * Returns an ASN.1 ENUMERATED value.