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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package javax.crypto;
import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.security.GeneralSecurityException;
import libcore.io.Streams;
/**
* This class wraps an {@code InputStream} and a cipher so that {@code read()}
* methods return data that are read from the underlying {@code InputStream} and
* processed by the cipher.
* <p>
* The cipher must be initialized for the requested operation before being used
* by a {@code CipherInputStream}. For example, if a cipher initialized for
* decryption is used with a {@code CipherInputStream}, the {@code
* CipherInputStream} tries to read the data an decrypt them before returning.
*/
public class CipherInputStream extends FilterInputStream {
private static final int I_BUFFER_SIZE = 20;
private final Cipher cipher;
private final byte[] inputBuffer = new byte[I_BUFFER_SIZE];
private byte[] outputBuffer;
private int outputIndex; // index of the first byte to return from outputBuffer
private int outputLength; // count of the bytes to return from outputBuffer
private boolean finished;
/**
* Creates a new {@code CipherInputStream} instance for an {@code
* InputStream} and a cipher.
*
* <p><strong>Warning:</strong> passing a null source creates an invalid
* {@code CipherInputStream}. All read operations on such a stream will
* fail.
*
* @param is
* the input stream to read data from.
* @param c
* the cipher to process the data with.
*/
public CipherInputStream(InputStream is, Cipher c) {
super(is);
this.cipher = c;
}
/**
* Creates a new {@code CipherInputStream} instance for an {@code
* InputStream} without a cipher.
* <p>
* A {@code NullCipher} is created and used to process the data.
*
* @param is
* the input stream to read data from.
*/
protected CipherInputStream(InputStream is) {
this(is, new NullCipher());
}
/**
* Reads the next byte from this cipher input stream.
*
* @return the next byte, or {@code -1} if the end of the stream is reached.
* @throws IOException
* if an error occurs.
*/
@Override
public int read() throws IOException {
if (finished) {
return (outputIndex == outputLength) ? -1 : outputBuffer[outputIndex++] & 0xFF;
}
if (outputIndex < outputLength) {
return outputBuffer[outputIndex++] & 0xFF;
}
outputIndex = 0;
outputLength = 0;
while (outputLength == 0) {
// check output size on each iteration since pending state
// in the cipher can cause this to vary from call to call
int outputSize = cipher.getOutputSize(inputBuffer.length);
if ((outputBuffer == null) || (outputBuffer.length < outputSize)) {
this.outputBuffer = new byte[outputSize];
}
int byteCount = in.read(inputBuffer);
if (byteCount == -1) {
try {
outputLength = cipher.doFinal(outputBuffer, 0);
} catch (Exception e) {
throw new IOException(e.getMessage());
}
finished = true;
break;
}
try {
outputLength = cipher.update(inputBuffer, 0, byteCount, outputBuffer, 0);
} catch (ShortBufferException e) {
throw new AssertionError(e); // should not happen since we sized with getOutputSize
}
}
return read();
}
/**
* Reads the next {@code len} bytes from this input stream into buffer
* {@code buf} starting at offset {@code off}.
* <p>
* if {@code buf} is {@code null}, the next {@code len} bytes are read and
* discarded.
*
* @return the number of bytes filled into buffer {@code buf}, or {@code -1}
* of the of the stream is reached.
* @throws IOException
* if an error occurs.
* @throws NullPointerException
* if the underlying input stream is {@code null}.
*/
@Override
public int read(byte[] buf, int off, int len) throws IOException {
if (in == null) {
throw new NullPointerException("Underlying input stream is null");
}
int i;
for (i = 0; i < len; ++i) {
int b = read();
if (b == -1) {
return (i == 0) ? -1 : i;
}
if (buf != null) {
buf[off+i] = (byte) b;
}
}
return i;
}
@Override
public long skip(long byteCount) throws IOException {
return Streams.skipByReading(this, byteCount);
}
@Override
public int available() throws IOException {
return 0;
}
/**
* Closes this {@code CipherInputStream}, also closes the underlying input
* stream and call {@code doFinal} on the cipher object.
*
* @throws IOException
* if an error occurs.
*/
@Override
public void close() throws IOException {
in.close();
try {
cipher.doFinal();
} catch (GeneralSecurityException ignore) {
//do like RI does
}
}
/**
* Returns whether this input stream supports {@code mark} and
* {@code reset}, which it does not.
*
* @return false, since this input stream does not support {@code mark} and
* {@code reset}.
*/
@Override
public boolean markSupported() {
return false;
}
}
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