using System;
namespace Org.BouncyCastle.Crypto.Tls{
/// <remarks>
/// A queue for bytes.
/// <p>
/// This file could be more optimized.
/// </p>
/// </remarks>
public class ByteQueue
{
/// <returns>The smallest number which can be written as 2^x which is bigger than i.</returns>
public static 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 const 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;
/// <summary>Read data from the buffer.</summary>
/// <param name="buf">The buffer where the read data will be copied to.</param>
/// <param name="offset">How many bytes to skip at the beginning of buf.</param>
/// <param name="len">How many bytes to read at all.</param>
/// <param name="skip">How many bytes from our data to skip.</param>
public void Read(
byte[] buf,
int offset,
int len,
int skip)
{
if ((available - skip) < len)
{
throw new TlsException("Not enough data to read");
}
if ((buf.Length - offset) < len)
{
throw new TlsException("Buffer size of " + buf.Length + " is too small for a read of " + len + " bytes");
}
Array.Copy(databuf, skipped + skip, buf, offset, len);
}
/// <summary>Add some data to our buffer.</summary>
/// <param name="data">A byte-array to read data from.</param>
/// <param name="offset">How many bytes to skip at the beginning of the array.</param>
/// <param name="len">How many bytes to read from the array.</param>
public void AddData(
byte[] data,
int offset,
int len)
{
if ((skipped + available + len) > databuf.Length)
{
byte[] tmp = new byte[ByteQueue.NextTwoPow(data.Length)];
Array.Copy(databuf, skipped, tmp, 0, available);
skipped = 0;
databuf = tmp;
}
Array.Copy(data, offset, databuf, skipped + available, len);
available += len;
}
/// <summary>Remove some bytes from our data from the beginning.</summary>
/// <param name="i">How many bytes to remove.</param>
public void RemoveData(
int i)
{
if (i > available)
{
throw new TlsException("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))
{
Array.Copy(databuf, skipped, databuf, 0, available);
skipped = 0;
}
}
/// <summary>The number of bytes which are available in this buffer.</summary>
public int Available
{
get { return available; }
}
}
}
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