/* $Id: AsnOutputStream.java,v 1.1 2004/01/19 02:03:49 rgrimm Exp $
*
* Copyright (c) 2000 The Cryptix Foundation Limited. All rights reserved.
*/
package cryptix.jce.provider.asn;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
/**
* Class for writing DER-encoded AsnObjects to an OutputStream.
*
* @version $Revision: 1.1 $
* @author Jeroen C. van Gelderen (gelderen@cryptix.org)
*/
public final class AsnOutputStream {
// Instance variables
//............................................................................
private final OutputStream os;
// Constructors and java.lang.Object overrides
//............................................................................
/**
* Convenience method that constructs an instance on top of an
* internal ByteArrayOutputStream.
*/
public AsnOutputStream() {
this.os = new ByteArrayOutputStream();
}
/**
* Constructs an instance on top of the given OutputStream.
*/
public AsnOutputStream(OutputStream os) {
this.os = os;
}
// Public interface
//............................................................................
/**
* Calls flush() then close() on the underlying stream. Exceptions are
* propagated up.
*
* @throws IOException
* When underlying stream does so.
*/
public void close() throws IOException {
this.os.flush();
this.os.close();
}
/**
* Calls flush() on the underlying stream. Exceptions are propagated up.
*
* @throws IOException
* When underlying stream does so.
*/
public void flush() throws IOException {
this.os.flush();
}
/**
* Writes a DER-encoded AsnObject to the underlying stream.
*/
public void write(AsnObject obj) throws IOException {
obj.encode(this);
}
/**
* Delegates to the underlying ByteArrayOutputStream if any.
*
* @throws IllegalStateException
* If the underlying stream is not a ByteArrayOutputStream.
*/
public byte[] toByteArray() {
if( !(this.os instanceof ByteArrayOutputStream) )
throw new IllegalStateException(
"Underlying stream is not instanceof ByteArrayOutputStream.");
ByteArrayOutputStream baos = (ByteArrayOutputStream)this.os;
return baos.toByteArray();
}
// AsnObject.encode(...) callbacks and helpers
//............................................................................
/**
* Returns the number of bytes writeLength() will write when called
* with the given 'len'. Yes, ASN/DER encoding sucks, don't get me started.
*/
/*package*/ int getLengthOfLength(int len) {
if( len <= 127 )
return 1;
else if( len <= 0xFF )
return 2;
else if( len <= 0xFFFF )
return 3;
else if( len <= 0xFFFFFF )
return 4;
else
return 5;
}
/*package*/ void writeByte(byte b) throws IOException {
this.os.write(b&0xFF);
}
/*package*/ void writeBytes(byte[] data) throws IOException {
this.os.write(data);
}
/**
* Write a variable length length (yuk!) as per ASN.1/DER specification.
*/
/*package*/ void writeLength(int len) throws IOException {
if(len < 0 )
throw new IllegalArgumentException("len: < 0");
// shortcut for short form
if(len <= 127) {
this.os.write( (char)len );
return;
}
// long form
int lenOfLenData = getLengthOfLength(len) - 1;
this.os.write( (byte)(lenOfLenData | 0x80) );
while( lenOfLenData-- > 0 )
this.os.write( (byte)(len >>> (lenOfLenData*8)) );
}
/*package*/ void writeType(byte type) throws IOException {
this.os.write(type);
}
}
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