package org.bouncycastle.asn1;
import java.io.ByteArrayInputStream;
import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;
public class ASN1StreamParser
{
InputStream _in;
private int _limit;
private boolean _eofFound;
public ASN1StreamParser(
InputStream in)
{
this(in, Integer.MAX_VALUE);
}
public ASN1StreamParser(
InputStream in,
int limit)
{
this._in = in;
this._limit = limit;
}
public ASN1StreamParser(
byte[] encoding)
{
this(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 == 0x80)
{
return -1; // indefinite-length encoding
}
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) // after all we must have read at least 1 byte
{
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.");
}
_eofFound = true;
return null;
}
//
// turn of looking for "00" while we resolve the tag
//
set00Check(false);
//
// calculate tag number
//
int baseTagNo = tag & ~DERTags.CONSTRUCTED;
int tagNo = baseTagNo;
if ((tag & DERTags.TAGGED) != 0)
{
tagNo = tag & 0x1f;
//
// with tagged object tag number is bottom 5 bits, or stored at the start of the content
//
if (tagNo == 0x1f)
{
tagNo = 0;
int b = _in.read();
while ((b >= 0) && ((b & 0x80) != 0))
{
tagNo |= (b & 0x7f);
tagNo <<= 7;
b = _in.read();
}
if (b < 0)
{
_eofFound = true;
throw new EOFException("EOF encountered inside tag value.");
}
tagNo |= (b & 0x7f);
}
}
//
// calculate length
//
int length = readLength();
if (length < 0) // indefinite length
{
IndefiniteLengthInputStream indIn = new IndefiniteLengthInputStream(_in);
switch (baseTagNo)
{
case DERTags.NULL:
while (indIn.read() >= 0)
{
// make sure we skip to end of object
}
return BERNull.INSTANCE;
case DERTags.OCTET_STRING:
return new BEROctetStringParser(new ASN1ObjectParser(tag, tagNo, indIn));
case DERTags.SEQUENCE:
return new BERSequenceParser(new ASN1ObjectParser(tag, tagNo, indIn));
case DERTags.SET:
return new BERSetParser(new ASN1ObjectParser(tag, tagNo, indIn));
default:
return new BERTaggedObjectParser(tag, tagNo, indIn);
}
}
else
{
DefiniteLengthInputStream defIn = new DefiniteLengthInputStream(_in, length);
switch (baseTagNo)
{
case DERTags.INTEGER:
return new DERInteger(defIn.toByteArray());
case DERTags.NULL:
defIn.toByteArray(); // make sure we read to end of object bytes.
return DERNull.INSTANCE;
case DERTags.OBJECT_IDENTIFIER:
return new DERObjectIdentifier(defIn.toByteArray());
case DERTags.OCTET_STRING:
return new DEROctetString(defIn.toByteArray());
case DERTags.SEQUENCE:
return new DERSequence(loadVector(defIn, length)).parser();
case DERTags.SET:
return new DERSet(loadVector(defIn, length)).parser();
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;
}
}