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Smart Card Utils for Better Access.
/*
* This file is part of the SCUBA smart card framework.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* Copyright (C) 2009 - 2015 The SCUBA team.
*
* $Id: TLVInputStream.java 246 2015-04-09 08:13:52Z martijno $
*/
package net.sf.scuba.tlv;
import java.io.BufferedInputStream;
import java.io.ByteArrayInputStream;
import java.io.DataInputStream;
import java.io.IOException;
import java.io.InputStream;
/**
* TLV input stream.
*
* @author Martijn Oostdijk ([email protected])
*
* @version $Revision: 246 $
*/
public class TLVInputStream extends InputStream {
/* 64K ought to be enough for anybody. */
private static final int MAX_BUFFER_LENGTH = 65535; // Integer.MAX_VALUE;
private final InputStream originalInputStream;
/** Carrier. */
private DataInputStream inputStream;
private int bufferSize;
private TLVInputState state;
private TLVInputState markedState;
/**
* Constructs a new TLV stream based on another stream.
*
* @param inputStream a TLV object
*/
public TLVInputStream(InputStream inputStream) {
this.bufferSize = 0;
try {
if (inputStream instanceof BufferedInputStream || inputStream instanceof ByteArrayInputStream) {
this.bufferSize = inputStream.available();
}
} catch (IOException ioe) {
/* NOTE: if available fails, we leave buffer size at 0. */
}
this.originalInputStream = inputStream;
this.inputStream = inputStream instanceof DataInputStream ? (DataInputStream)inputStream : new DataInputStream(inputStream);
state = new TLVInputState();
markedState = null;
}
/**
* Reads a tag.
*
* @return the tag just read
*
* @throws IOException if reading goes wrong
*/
public int readTag() throws IOException {
if (!state.isAtStartOfTag() && !state.isProcessingValue()) { throw new IllegalStateException("Not at start of tag"); }
int tag = -1;
int bytesRead = 0;
try {
int b = inputStream.readUnsignedByte(); bytesRead++;
while (b == 0x00 || b == 0xFF) {
b = inputStream.readUnsignedByte(); bytesRead++; /* skip 00 and FF */
}
switch (b & 0x1F) {
case 0x1F:
tag = b; /* We store the first byte including LHS nibble */
b = inputStream.readUnsignedByte(); bytesRead++;
while ((b & 0x80) == 0x80) {
tag <<= 8;
tag |= (b & 0x7F);
b = inputStream.readUnsignedByte(); bytesRead++;
}
tag <<= 8;
tag |= (b & 0x7F);
/*
* Byte with MSB set is last byte of
* tag...
*/
break;
default:
tag = b;
break;
}
state.setTagProcessed(tag, bytesRead);
return tag;
} catch (IOException e) {
throw e;
}
}
/**
* Reads a length.
*
* @return the length just read
*
* @throws IOException if reading goes wrong
*/
public int readLength() throws IOException {
try {
if (!state.isAtStartOfLength()) { throw new IllegalStateException("Not at start of length"); }
int bytesRead = 0;
int length = 0;
int b = inputStream.readUnsignedByte(); bytesRead++;
if ((b & 0x80) == 0x00) {
/* short form */
length = b;
} else {
/* long form */
int count = b & 0x7F;
length = 0;
for (int i = 0; i < count; i++) {
b = inputStream.readUnsignedByte(); bytesRead++;
length <<= 8;
length |= b;
}
}
state.setLengthProcessed(length, bytesRead);
/* We're buffering our carrier inputstream now that we know max length */
// if (bufferSize < length && length < MAX_BUFFER_LENGTH) {
// bufferSize = length;
// this.inputStream = new DataInputStream(new BufferedInputStream(originalInputStream, bufferSize));
// }
return length;
} catch (IOException e) {
throw e;
}
}
/**
* Reads a value.
*
* @return the value just read
*
* @throws IOException if reading goes wrong
*/
public byte[] readValue() throws IOException {
try {
if (!state.isProcessingValue()) { throw new IllegalStateException("Not yet processing value!"); }
int length = state.getLength();
byte[] value = new byte[length];
inputStream.readFully(value);
state.updateValueBytesProcessed(length);
return value;
} catch (IOException e) {
throw e;
}
}
private long skipValue() throws IOException {
if (state.isAtStartOfTag()) { return 0; }
if (state.isAtStartOfLength()) { return 0; }
int bytesLeft = state.getValueBytesLeft();
return skip(bytesLeft);
}
/**
* Skips in this stream until a given tag is found (depth first).
* The stream is positioned right after the first occurrence of the tag.
*
* @param searchTag the tag to search for
*
* @throws IOException on error
*/
public void skipToTag(int searchTag) throws IOException {
while (true) {
/* Get the next tag. */
int tag = -1;
if (state.isAtStartOfTag()) {
/* Nothing. */
} else if (state.isAtStartOfLength()) {
readLength();
if (TLVUtil.isPrimitive(state.getTag())) { skipValue(); }
} else {
if (TLVUtil.isPrimitive(state.getTag())) { skipValue(); }
}
tag = readTag();
if (tag == searchTag) { return; }
if (TLVUtil.isPrimitive(tag)) {
int length = readLength();
int skippedBytes = (int)skipValue();
if (skippedBytes >= length) {
/* Now at next tag. */
continue;
} else {
/* Could only skip less than length bytes,
* we're lost, probably at EOF. */
break;
}
}
}
}
/**
* Returns an estimate of the number of bytes that can be read (or
* skipped over) from this input stream without blocking by the next
* invocation of a method for this input stream.
*
* @return a number of bytes
*
* @throws IOException if something goes wrong
*/
public int available() throws IOException {
return inputStream.available();
}
/**
* Reads the next byte of data from the input stream.
*
* @return a byte
*
* @throws IOException if reading goes wrong
*/
public int read() throws IOException {
int result = inputStream.read();
if (result < 0) { return -1; }
state.updateValueBytesProcessed(1);
return result;
}
/**
* Attempts to skip over n bytes.
*
* @return the actual number of bytes skipped
*
* @throws IOException if something goes wrong
*/
public long skip(long n) throws IOException {
if (n <= 0) { return 0; }
long result = inputStream.skip(n);
state.updateValueBytesProcessed((int)result);
return result;
}
/**
* Marks the underlying input stream if supported.
*
* @param readLimit limit for marking
*/
public synchronized void mark(int readLimit) {
inputStream.mark(readLimit);
markedState = (TLVInputState)state.clone();
}
/**
* Whether marking and resetting are supported.
* We support this whenever the underlying input stream supports it.
*
* @return whether mark and reset are supported
*/
public boolean markSupported() {
return inputStream.markSupported();
}
/**
* Resets the underlying input stream if supported.
*
* @throws IOException if something goes wrong
*/
public synchronized void reset() throws IOException {
if (!markSupported()) {
throw new IOException("mark/reset not supported");
}
inputStream.reset();
state = markedState;
markedState = null;
}
/**
* Closes this input stream.
*
* @throws IOException if something goes wrong
*/
public void close() throws IOException {
inputStream.close();
}
public String toString() {
return state.toString();
}
}
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