private void FillCryptoOverflowWithExcess(byte[] buffer, int start, int initialCount, int extendedCount)
{
//If the original count asked for is not the same as the blocksize adjusted count
//we need to buffer the extra bytes
if (initialCount != extendedCount)
{
int overflowSize = extendedCount - initialCount;
int readIndex = CryptoBlockOverflow.Length - overflowSize;
//We should read the overflow into starting index OverflowLength - overflowSize index and not starting at 0
//This allows us to know how many and what index to starting reading at all at the same time
BufferUtil.QuickUnsafeCopy(buffer, start + (extendedCount - overflowSize), CryptoBlockOverflow, readIndex, overflowSize);
CryptoBlockOverflowReadIndex = readIndex;
}
}
public override async Task WriteAsync(byte[] bytes, int offset, int count)
{
if (offset < 0)
{
throw new ArgumentOutOfRangeException(nameof(offset));
}
if (count < 0)
{
throw new ArgumentOutOfRangeException(nameof(count));
}
int blocksizeAdjustedCount = ConvertToBlocksizeCount(count);
if (count == blocksizeAdjustedCount)
{
await DecoratedClient.WriteAsync(EncryptionServiceProvider.Crypt(bytes, offset, count), offset, count)
.ConfigureAwait(false);
}
else
{
//Lock because we use the crypto buffer for this
using (await WriteBuffer.BufferLock.LockAsync().ConfigureAwait(false))
{
try
{
//We copy to the thread local buffer so we can use it as an extended buffer by "neededBytes" many more bytes.
//So the buffer is very large but we'll tell it to write bytes.length + neededBytes.
BufferUtil.QuickUnsafeCopy(bytes, offset, WriteBuffer.Buffer, 0, count); //dont copy full array, might only need less with count
}
catch (Exception e)
{
throw new InvalidOperationException($"Failed to copy bytes to crypto buffer. Bytes Length: {bytes.Length} Offset: {offset} Count: {count} BlocksizeAdjustedCount: {blocksizeAdjustedCount}", e);
}
EncryptionServiceProvider.Crypt(WriteBuffer.Buffer, 0, blocksizeAdjustedCount);
//recurr to write the bytes with the now properly sized buffer.
await DecoratedClient.WriteAsync(WriteBuffer.Buffer, 0, blocksizeAdjustedCount)
.ConfigureAwait(false);
}
}
}
/// <inheritdoc />
public override async Task WriteAsync(byte[] bytes, int offset, int count)
{
if (count < 0)
{
throw new ArgumentOutOfRangeException(nameof(count));
}
//If we have more bytes than we require buffering till
//we should just write
//We have to lock to prevent anything from touching the combined or buffer inbetween
using (await BufferedData.BufferLock.LockAsync().ConfigureAwait(false))
using (await CombinedBuffer.BufferLock.LockAsync().ConfigureAwait(false))
{
if (count > BufferedData.Buffer.Length && CurrentIndex == -1)
{
await DecoratedClient.WriteAsync(bytes, offset, count)
.ConfigureAwait(false);
}
else if (count + CurrentIndex + 1 > BufferedData.Buffer.Length && CurrentIndex != -1)
{
//TODO: Do this somehow without copying
BufferUtil.QuickUnsafeCopy(BufferedData.Buffer, 0, CombinedBuffer.Buffer, 0, CurrentIndex + 1);
BufferUtil.QuickUnsafeCopy(bytes, offset, CombinedBuffer.Buffer, CurrentIndex + 1, count);
await DecoratedClient.WriteAsync(CombinedBuffer.Buffer, 0, count + CurrentIndex + 1)
.ConfigureAwait(false);
CurrentIndex = -1;
}
else
{
//At this point we know that the buffer isn't large enough to write so we need to buffer it
BufferUtil.QuickUnsafeCopy(bytes, offset, BufferedData.Buffer, CurrentIndex + 1, count);
CurrentIndex += count;
}
}
}
//TODO: Refactor this
/// <summary>
/// Reads asyncronously <see cref="count"/> many bytes from the reader.
/// </summary>
/// <param name="buffer">The buffer to store the bytes into.</param>
/// <param name="start">The start position in the buffer to start reading into.</param>
/// <param name="count">How many bytes to read.</param>
/// <param name="token">The cancel token to check during the async operation.</param>
/// <returns>A future for the read bytes.</returns>
public override async Task <int> ReadAsync(byte[] buffer, int start, int count, CancellationToken token)
{
if (buffer == null)
{
throw new ArgumentNullException(nameof(buffer));
}
if (start < 0)
{
throw new ArgumentOutOfRangeException(nameof(start));
}
if (count < 0)
{
throw new ArgumentOutOfRangeException(nameof(count), $"Cannot read less than 0 bytes. Can't read: {count} many bytes");
}
//We read this outside of the lock to reduce locking time
//If the above caller requested an invalid count of bytes to read
//We should try to correct for it and read afew more bytes.
int extendedCount = ConvertToBlocksizeCount(count);
if (token.IsCancellationRequested)
{
return(0);
}
//TODO: Optimize for when the buffer is large enough. Right now it does needless BlockCopy even if there is room in the buffer
//We should lock incase there are multiple calls
using (await ReadBuffer.BufferLock.LockAsync(token).ConfigureAwait(false))
{
int cryptoOverflowSize = CryptoBlockOverflow.Length - CryptoBlockOverflowReadIndex;
//If the overflow size is the exact size asked for then
//we don't need to do anything but copy the buffer and return
if (cryptoOverflowSize >= count)
{
//Read from the crypto overflow and move the read index forward
BufferUtil.QuickUnsafeCopy(CryptoBlockOverflow, CryptoBlockOverflowReadIndex, buffer, start, count);
CryptoBlockOverflowReadIndex = CryptoBlockOverflowReadIndex + count;
return(count);
}
else if (cryptoOverflowSize == 0)
{
//Since the buffer MAY be large enough we check to avoid a potential BlockCopy
if (buffer.Length > extendedCount)
{
//Since the provider may not give a buffer large enough we should use the crypto buffer
bool result = await ReadAndDecrypt(buffer, start, token, extendedCount)
.ConfigureAwait(false);
//if the read/decrypt failed then return 0
if (!result)
{
return(0);
}
FillCryptoOverflowWithExcess(buffer, 0, count, extendedCount);
}
else
{
//Since the provider may not give a buffer large enough we should use the crypto buffer
bool result = await ReadAndDecrypt(ReadBuffer.Buffer, 0, token, extendedCount)
.ConfigureAwait(false);
//if the read/decrypt failed then return 0
if (!result)
{
return(0);
}
//Now we must BlockCopy the requested amount into the buffer
BufferUtil.QuickUnsafeCopy(ReadBuffer.Buffer, 0, buffer, start, count);
FillCryptoOverflowWithExcess(ReadBuffer.Buffer, 0, count, extendedCount);
}
}
else if (cryptoOverflowSize < count)
{
BufferUtil.QuickUnsafeCopy(CryptoBlockOverflow, CryptoBlockOverflowReadIndex, buffer, start, cryptoOverflowSize);
CryptoBlockOverflowReadIndex = CryptoBlockOverflow.Length; //set it to last index so we know we have no overflow anymore
//Recompute the extended count, since we read some of the cryptooverflow it will have changed potentially
int newCount = count - cryptoOverflowSize;
extendedCount = ConvertToBlocksizeCount(newCount);
//We can't directly read this into the buffer provided
//it may not be large enough to handle the blocksize shift
//So we must read with the cryptobuffer and then blockcopy the result
if (buffer.Length > extendedCount + start + cryptoOverflowSize)
{
//Read into buffer starting at the start requested + the overflow size
bool result = await ReadAndDecrypt(buffer, start + cryptoOverflowSize, token, extendedCount)
.ConfigureAwait(false);
//if the read/decrypt failed then return 0
if (!result)
{
return(0);
}
FillCryptoOverflowWithExcess(buffer, start + cryptoOverflowSize, newCount, extendedCount);
}
else
{
//Read into buffer starting at the start requested + the overflow size
bool result = await ReadAndDecrypt(ReadBuffer.Buffer, 0, token, extendedCount)
.ConfigureAwait(false);
//if the read/decrypt failed then return 0
if (!result)
{
return(0);
}
//Now we must BlockCopy the requested amount into the buffer
BufferUtil.QuickUnsafeCopy(ReadBuffer.Buffer, 0, buffer, start + cryptoOverflowSize, newCount);
FillCryptoOverflowWithExcess(ReadBuffer.Buffer, 0, newCount, extendedCount);
}
}
}
//never return the extended count, callers above shouldn't have to deal
//with more than they asked for
return(count);
}