asn1streamparser.java

java 文件下载器。可自定义

// Decompiled by Jad v1.5.8e2. Copyright 2001 Pavel Kouznetsov.
// Jad home page: http://kpdus.tripod.com/jad.html
// Decompiler options: packimports(3) fieldsfirst ansi space 
// Source File Name:   ASN1StreamParser.java

package org.bouncycastle.asn1;

import java.io.*;

// Referenced classes of package org.bouncycastle.asn1:
//			ASN1EncodableVector, ASN1InputStream, ASN1ObjectParser, BERNull, 
//			BEROctetStringParser, BERSequenceParser, BERSetParser, BERTaggedObjectParser, 
//			DERInteger, DERNull, DERObjectIdentifier, DEROctetString, 
//			DERSequence, DERSet, DefiniteLengthInputStream, IndefiniteLengthInputStream, 
//			DEREncodable

public class ASN1StreamParser
{

	InputStream _in;
	private int _limit;
	private boolean _eofFound;

	public ASN1StreamParser(InputStream in)
	{
		this(in, 0x7fffffff);
	}

	public ASN1StreamParser(InputStream in, int limit)
	{
		_in = in;
		_limit = limit;
	}

	public ASN1StreamParser(byte encoding[])
	{
		this(((InputStream) (new ByteArrayInputStream(encoding))), encoding.length);
	}

	InputStream getParentStream()
	{
		return _in;
	}

	private int readLength()
		throws IOException
	{
		int length = _in.read();
		if (length < 0)
			throw new EOFException("EOF found when length expected");
		if (length == 128)
			return -1;
		if (length > 127)
		{
			int size = length & 0x7f;
			if (size > 4)
				throw new IOException("DER length more than 4 bytes");
			length = 0;
			for (int i = 0; i < size; i++)
			{
				int next = _in.read();
				if (next < 0)
					throw new EOFException("EOF found reading length");
				length = (length << 8) + next;
			}

			if (length < 0)
				throw new IOException("corrupted stream - negative length found");
			if (length >= _limit)
				throw new IOException("corrupted stream - out of bounds length found");
		}
		return length;
	}

	public DEREncodable readObject()
		throws IOException
	{
		int tag = _in.read();
		if (tag == -1)
			if (_eofFound)
			{
				throw new EOFException("attempt to read past end of file.");
			} else
			{
				_eofFound = true;
				return null;
			}
		set00Check(false);
		int baseTagNo = tag & 0xffffffdf;
		int tagNo = baseTagNo;
		if ((tag & 0x80) != 0)
		{
			tagNo = tag & 0x1f;
			if (tagNo == 31)
			{
				tagNo = 0;
				int b;
				for (b = _in.read(); b >= 0 && (b & 0x80) != 0; b = _in.read())
				{
					tagNo |= b & 0x7f;
					tagNo <<= 7;
				}

				if (b < 0)
				{
					_eofFound = true;
					throw new EOFException("EOF encountered inside tag value.");
				}
				tagNo |= b & 0x7f;
			}
		}
		int length = readLength();
		if (length < 0)
		{
			IndefiniteLengthInputStream indIn = new IndefiniteLengthInputStream(_in);
			switch (baseTagNo)
			{
			case 5: // '\005'
				while (indIn.read() >= 0) ;
				return BERNull.INSTANCE;

			case 4: // '\004'
				return new BEROctetStringParser(new ASN1ObjectParser(tag, tagNo, indIn));

			case 16: // '\020'
				return new BERSequenceParser(new ASN1ObjectParser(tag, tagNo, indIn));

			case 17: // '\021'
				return new BERSetParser(new ASN1ObjectParser(tag, tagNo, indIn));
			}
			return new BERTaggedObjectParser(tag, tagNo, indIn);
		}
		DefiniteLengthInputStream defIn = new DefiniteLengthInputStream(_in, length);
		switch (baseTagNo)
		{
		case 2: // '\002'
			return new DERInteger(defIn.toByteArray());

		case 5: // '\005'
			defIn.toByteArray();
			return DERNull.INSTANCE;

		case 6: // '\006'
			return new DERObjectIdentifier(defIn.toByteArray());

		case 4: // '\004'
			return new DEROctetString(defIn.toByteArray());

		case 16: // '\020'
			return (new DERSequence(loadVector(defIn, length))).parser();

		case 17: // '\021'
			return (new DERSet(loadVector(defIn, length))).parser();

		case 3: // '\003'
		case 7: // '\007'
		case 8: // '\b'
		case 9: // '\t'
		case 10: // '\n'
		case 11: // '\013'
		case 12: // '\f'
		case 13: // '\r'
		case 14: // '\016'
		case 15: // '\017'
		default:
			return new BERTaggedObjectParser(tag, tagNo, defIn);
		}
	}

	private void set00Check(boolean enabled)
	{
		if (_in instanceof IndefiniteLengthInputStream)
			((IndefiniteLengthInputStream)_in).setEofOn00(enabled);
	}

	private ASN1EncodableVector loadVector(InputStream in, int length)
		throws IOException
	{
		ASN1InputStream aIn = new ASN1InputStream(in, length);
		ASN1EncodableVector v = new ASN1EncodableVector();
		DERObject obj;
		while ((obj = aIn.readObject()) != null) 
			v.add(obj);
		return v;
	}
}