void OnRead(IAsyncResult base_ares)
        {
            ReadBufferState       rb   = (ReadBufferState)base_ares.AsyncState;
            HttpStreamAsyncResult ares = rb.Ares;

            try {
                int nread = base.EndRead(base_ares);
                decoder.Write(ares.Buffer, ares.Offset, nread);
                nread      = decoder.Read(rb.Buffer, rb.Offset, rb.Count);
                rb.Offset += nread;
                rb.Count  -= nread;
                if (rb.Count == 0 || !decoder.WantMore || nread == 0)
                {
                    no_more_data = !decoder.WantMore && nread == 0;
                    ares.Count   = rb.InitialCount - rb.Count;
                    ares.Complete();
                    return;
                }
                ares.Offset = 0;
                ares.Count  = System.Math.Min(8192, decoder.ChunkLeft + 6);
                base.BeginRead(ares.Buffer, ares.Offset, ares.Count, OnRead, rb);
            } catch (Exception e) {
                context.Connection.SendError(e.Message, 400);
                ares.Complete(e);
            }
        }
        public override IAsyncResult BeginRead(byte[] buffer, int offset, int count,
                                               AsyncCallback cback, object state)
        {
            if (disposed)
            {
                throw new ObjectDisposedException(typeof(RequestStream).ToString());
            }

            int nread = FillFromBuffer(buffer, offset, count);

            if (nread > 0 || nread == -1)
            {
                HttpStreamAsyncResult ares = new HttpStreamAsyncResult();
                ares.Buffer    = buffer;
                ares.Offset    = offset;
                ares.Count     = count;
                ares.Callback  = cback;
                ares.State     = state;
                ares.SynchRead = System.Math.Max(0, nread);
                ares.Complete();
                return(ares);
            }

            // Avoid reading past the end of the request to allow
            // for HTTP pipelining
            if (remaining_body >= 0 && count > remaining_body)
            {
                count = (int)System.Math.Min(Int32.MaxValue, remaining_body);
            }
            return(stream.BeginRead(buffer, offset, count, cback, state));
        }
        public override IAsyncResult BeginRead(byte [] buffer, int offset, int count,
                                               AsyncCallback cback, object state)
        {
            if (disposed)
            {
                throw new ObjectDisposedException(GetType().ToString());
            }

            if (buffer == null)
            {
                throw new ArgumentNullException("buffer");
            }

            int len = buffer.Length;

            if (offset < 0 || offset > len)
            {
                throw new ArgumentOutOfRangeException("offset exceeds the size of buffer");
            }

            if (count < 0 || offset > len - count)
            {
                throw new ArgumentOutOfRangeException("offset+size exceeds the size of buffer");
            }

            HttpStreamAsyncResult ares = new HttpStreamAsyncResult();

            ares.Callback = cback;
            ares.State    = state;
            if (no_more_data)
            {
                ares.Complete();
                return(ares);
            }
            int nread = decoder.Read(buffer, offset, count);

            offset += nread;
            count  -= nread;
            if (count == 0)
            {
                // got all we wanted, no need to bother the decoder yet
                ares.Count = nread;
                ares.Complete();
                return(ares);
            }
            if (!decoder.WantMore)
            {
                no_more_data = nread == 0;
                ares.Count   = nread;
                ares.Complete();
                return(ares);
            }
            ares.Buffer = new byte [8192];
            ares.Offset = 0;
            ares.Count  = 8192;
            ReadBufferState rb = new ReadBufferState(buffer, offset, count, ares);

            rb.InitialCount += nread;
            base.BeginRead(ares.Buffer, ares.Offset, ares.Count, OnRead, rb);
            return(ares);
        }