System.Net.Security.SslState.EnqueueOldKeyDecryptedData C# (CSharp) Method

        private Exception EnqueueOldKeyDecryptedData(byte[] buffer, int offset, int count)
        {
            lock (this)
            {
                if (_queuedReadCount + count > MaxQueuedReadBytes)
                {
                    return new IOException(SR.Format(SR.net_auth_ignored_reauth, MaxQueuedReadBytes.ToString(NumberFormatInfo.CurrentInfo)));
                }

                if (count != 0)
                {
                    // This is inefficient yet simple and that should be a rare case of receiving data encrypted with "old" key.
                    _queuedReadData = EnsureBufferSize(_queuedReadData, _queuedReadCount, _queuedReadCount + count);
                    Buffer.BlockCopy(buffer, offset, _queuedReadData, _queuedReadCount, count);
                    _queuedReadCount += count;
                    FinishHandshakeRead(LockHandshake);
                }
            }
            return null;
        }