/// <summary>
        /// Pass recieved data into the packet buffer and try to parse.
        /// </summary>
        /// <param name="num_bytes">number of bytes waiting to be read</param>
        protected override void OnReceive(int num_bytes)
        {
            try
            {
                short pakSize;

                // decrypt the packet if needed
                if (IsEncrypted)
                {
                    pakSize = GetExpectedLength(true);
                }
                else
                {
                    pakSize = GetExpectedLength(false);
                }

                // we received just enough data for the full message. not too litt,e not too much
                if (pakSize + 2 == num_bytes)
                {
                    byte[] fullMessage = new byte[num_bytes];

                    Array.Copy(m_inBuf, 0, fullMessage, 0, num_bytes);

                    Array.Clear(m_inBuf, 0, pakSize + 2);

                    m_inOffset = 0;

                    // we have a full packet
                    // process it here

                    return;
                }
                // we received an excess of data
                else if (pakSize + 2 < num_bytes)
                {
                    // get only the data we need
                    byte[] fullMessage = new byte[pakSize + 2];
                    Array.Copy(m_inBuf, 0, fullMessage, 0, pakSize + 2);

                    // clear the data i just took
                    Array.Clear(m_inBuf, 0, pakSize + 2);

                    // shift the remaining data to the top
                    Array.Copy(m_inBuf, m_inOffset, m_inBuf, 0, m_inBuf.Length - m_inOffset);

                    // set the offset to the end of the data that was in excess
                    m_inOffset = num_bytes - (pakSize + 2);

                    // we have enough for a full packet
                    // segment and process

                    return;
                }
                else
                {
                    // partial packet. we don't touch the offset and just let it async read more data.

                    return;
                }
            }
            catch (InsufficientDataException e)
            {
                m_srvr.Warning(this, e);
            }
        }