package com.google.bitcoin.bouncycastle.crypto.tls; /** * A queue for bytes. * <p/> * This file could be more optimized. * </p> */ public class ByteQueue { /** * @return The smallest number which can be written as 2^x which is * bigger than i. */ public static final int nextTwoPow(int i) { /* * This code is based of a lot of code I found on the Internet * which mostly referenced a book called "Hacking delight". * */ i |= (i >> 1); i |= (i >> 2); i |= (i >> 4); i |= (i >> 8); i |= (i >> 16); return i + 1; } /** * The initial size for our buffer. */ private static final int INITBUFSIZE = 1024; /** * The buffer where we store our data. */ private byte[] databuf = new byte[ByteQueue.INITBUFSIZE]; /** * How many bytes at the beginning of the buffer are skipped. */ private int skipped = 0; /** * How many bytes in the buffer are valid data. */ private int available = 0; /** * Read data from the buffer. * * @param buf The buffer where the read data will be copied to. * @param offset How many bytes to skip at the beginning of buf. * @param len How many bytes to read at all. * @param skip How many bytes from our data to skip. */ public void read(byte[] buf, int offset, int len, int skip) { if ((available - skip) < len) { throw new TlsRuntimeException("Not enough data to read"); } if ((buf.length - offset) < len) { throw new TlsRuntimeException("Buffer size of " + buf.length + " is too small for a read of " + len + " bytes"); } System.arraycopy(databuf, skipped + skip, buf, offset, len); return; } /** * Add some data to our buffer. * * @param data A byte-array to read data from. * @param offset How many bytes to skip at the beginning of the array. * @param len How many bytes to read from the array. */ public void addData(byte[] data, int offset, int len) { if ((skipped + available + len) > databuf.length) { byte[] tmp = new byte[ByteQueue.nextTwoPow(data.length)]; System.arraycopy(databuf, skipped, tmp, 0, available); skipped = 0; databuf = tmp; } System.arraycopy(data, offset, databuf, skipped + available, len); available += len; } /** * Remove some bytes from our data from the beginning. * * @param i How many bytes to remove. */ public void removeData(int i) { if (i > available) { throw new TlsRuntimeException("Cannot remove " + i + " bytes, only got " + available); } /* * Skip the data. */ available -= i; skipped += i; /* * If more than half of our data is skipped, we will move the data * in the buffer. */ if (skipped > (databuf.length / 2)) { System.arraycopy(databuf, skipped, databuf, 0, available); skipped = 0; } } /** * @return The number of bytes which are available in this buffer. */ public int size() { return available; } }