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package com.lowagie.bc.asn1;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;
import java.util.Vector;
/**
* a general purpose ASN.1 decoder - note: this class differs from the
* others in that it returns null after it has read the last object in
* the stream. If an ASN.1 NULL is encountered a DER/BER Null object is
* returned.
*/
public class ASN1InputStream
extends DERInputStream
{
private DERObject END_OF_STREAM = new DERObject() {
void encode(
DEROutputStream out)
throws IOException
{
throw new IOException("Eeek!");
}
};
boolean eofFound = false;
public ASN1InputStream(
InputStream is)
{
super(is);
}
protected int readLength()
throws IOException
{
int length = read();
if (length < 0)
{
throw new IOException("EOF found when length expected");
}
if (length == 0x80)
{
return -1; // indefinite-length encoding
}
if (length > 127)
{
int size = length & 0x7f;
length = 0;
for (int i = 0; i < size; i++)
{
int next = read();
if (next < 0)
{
throw new IOException("EOF found reading length");
}
length = (length << 8) + next;
}
}
return length;
}
protected void readFully(
byte[] bytes)
throws IOException
{
int left = bytes.length;
int len;
if (left == 0)
{
return;
}
while ((len = read(bytes, bytes.length - left, left)) > 0)
{
if ((left -= len) == 0)
{
return;
}
}
if (left != 0)
{
throw new EOFException("EOF encountered in middle of object");
}
}
/**
* build an object given its tag and a byte stream to construct it
* from.
*/
protected DERObject buildObject(
int tag,
byte[] bytes)
throws IOException
{
if ((tag & APPLICATION) != 0)
{
return new DERApplicationSpecific(tag, bytes);
}
switch (tag)
{
case NULL:
return new DERNull();
case SEQUENCE | CONSTRUCTED:
ByteArrayInputStream bIn = new ByteArrayInputStream(bytes);
ASN1InputStream aIn = new ASN1InputStream(bIn);
ASN1EncodableVector v = new ASN1EncodableVector();
DERObject obj = aIn.readObject();
while (obj != null)
{
v.add(obj);
obj = aIn.readObject();
}
return new DERSequence(v);
case SET | CONSTRUCTED:
bIn = new ByteArrayInputStream(bytes);
aIn = new ASN1InputStream(bIn);
v = new ASN1EncodableVector();
obj = aIn.readObject();
while (obj != null)
{
v.add(obj);
obj = aIn.readObject();
}
return new DERSet(v);
case BOOLEAN:
return new DERBoolean(bytes);
case INTEGER:
return new DERInteger(bytes);
case ENUMERATED:
return new DEREnumerated(bytes);
case OBJECT_IDENTIFIER:
return new DERObjectIdentifier(bytes);
case BIT_STRING:
int padBits = bytes[0];
byte[] data = new byte[bytes.length - 1];
System.arraycopy(bytes, 1, data, 0, bytes.length - 1);
return new DERBitString(data, padBits);
case UTF8_STRING:
return new DERUTF8String(bytes);
case PRINTABLE_STRING:
return new DERPrintableString(bytes);
case IA5_STRING:
return new DERIA5String(bytes);
case T61_STRING:
return new DERT61String(bytes);
case VISIBLE_STRING:
return new DERVisibleString(bytes);
case GENERAL_STRING:
return new DERGeneralString(bytes);
case UNIVERSAL_STRING:
return new DERUniversalString(bytes);
case BMP_STRING:
return new DERBMPString(bytes);
case OCTET_STRING:
return new DEROctetString(bytes);
case UTC_TIME:
return new DERUTCTime(bytes);
case GENERALIZED_TIME:
return new DERGeneralizedTime(bytes);
default:
//
// with tagged object tag number is bottom 5 bits
//
if ((tag & TAGGED) != 0)
{
int tagNo = tag & 0x1f;
if (tagNo == 0x1f)
{
int idx = 0;
tagNo = 0;
while ((bytes[idx] & 0x80) != 0)
{
tagNo |= (bytes[idx++] & 0x7f);
tagNo <<= 7;
}
tagNo |= (bytes[idx] & 0x7f);
byte[] tmp = bytes;
bytes = new byte[tmp.length - (idx + 1)];
System.arraycopy(tmp, idx + 1, bytes, 0, bytes.length);
}
if (bytes.length == 0) // empty tag!
{
if ((tag & CONSTRUCTED) == 0)
{
return new DERTaggedObject(false, tagNo, new DERNull());
}
else
{
return new DERTaggedObject(false, tagNo, new DERSequence());
}
}
//
// simple type - implicit... return an octet string
//
if ((tag & CONSTRUCTED) == 0)
{
return new DERTaggedObject(false, tagNo, new DEROctetString(bytes));
}
bIn = new ByteArrayInputStream(bytes);
aIn = new ASN1InputStream(bIn);
DEREncodable dObj = aIn.readObject();
//
// explicitly tagged (probably!) - if it isn't we'd have to
// tell from the context
//
if (aIn.available() == 0)
{
return new DERTaggedObject(tagNo, dObj);
}
//
// another implicit object, we'll create a sequence...
//
v = new ASN1EncodableVector();
while (dObj != null)
{
v.add(dObj);
dObj = aIn.readObject();
}
return new DERTaggedObject(false, tagNo, new DERSequence(v));
}
return new DERUnknownTag(tag, bytes);
}
}
/**
* read a string of bytes representing an indefinite length object.
*/
private byte[] readIndefiniteLengthFully()
throws IOException
{
ByteArrayOutputStream bOut = new ByteArrayOutputStream();
int b, b1;
b1 = read();
while ((b = read()) >= 0)
{
if (b1 == 0 && b == 0)
{
break;
}
bOut.write(b1);
b1 = b;
}
return bOut.toByteArray();
}
private BERConstructedOctetString buildConstructedOctetString()
throws IOException
{
Vector octs = new Vector();
for (;;)
{
DERObject o = readObject();
if (o == END_OF_STREAM)
{
break;
}
octs.addElement(o);
}
return new BERConstructedOctetString(octs);
}
public DERObject readObject()
throws IOException
{
int tag = read();
if (tag == -1)
{
if (eofFound)
{
throw new EOFException("attempt to read past end of file.");
}
eofFound = true;
return null;
}
int length = readLength();
if (length < 0) // indefinite length method
{
switch (tag)
{
case NULL:
return new BERNull();
case SEQUENCE | CONSTRUCTED:
ASN1EncodableVector v = new ASN1EncodableVector();
for (;;)
{
DERObject obj = readObject();
if (obj == END_OF_STREAM)
{
break;
}
v.add(obj);
}
return new BERSequence(v);
case SET | CONSTRUCTED:
v = new ASN1EncodableVector();
for (;;)
{
DERObject obj = readObject();
if (obj == END_OF_STREAM)
{
break;
}
v.add(obj);
}
return new BERSet(v);
case OCTET_STRING | CONSTRUCTED:
return buildConstructedOctetString();
default:
//
// with tagged object tag number is bottom 5 bits
//
if ((tag & TAGGED) != 0)
{
int tagNo = tag & 0x1f;
if (tagNo == 0x1f)
{
int b = read();
tagNo = 0;
while ((b >= 0) && ((b & 0x80) != 0))
{
tagNo |= (b & 0x7f);
tagNo <<= 7;
b = read();
}
tagNo |= (b & 0x7f);
}
//
// simple type - implicit... return an octet string
//
if ((tag & CONSTRUCTED) == 0)
{
byte[] bytes = readIndefiniteLengthFully();
return new BERTaggedObject(false, tagNo, new DEROctetString(bytes));
}
//
// either constructed or explicitly tagged
//
DERObject dObj = readObject();
if (dObj == END_OF_STREAM) // empty tag!
{
return new DERTaggedObject(tagNo);
}
DERObject next = readObject();
//
// explicitly tagged (probably!) - if it isn't we'd have to
// tell from the context
//
if (next == END_OF_STREAM)
{
return new BERTaggedObject(tagNo, dObj);
}
//
// another implicit object, we'll create a sequence...
//
v = new ASN1EncodableVector();
v.add(dObj);
do
{
v.add(next);
next = readObject();
}
while (next != END_OF_STREAM);
return new BERTaggedObject(false, tagNo, new BERSequence(v));
}
throw new IOException("unknown BER object encountered");
}
}
else
{
if (tag == 0 && length == 0) // end of contents marker.
{
return END_OF_STREAM;
}
byte[] bytes = new byte[length];
readFully(bytes);
return buildObject(tag, bytes);
}
}
}
