Your write()
method calls are assuming that the entire buffer was filled by receive().
You must use the length provided with the DatagramPacket:
datagramSocket.receive(packet);
stream.write(packet.getData(), packet.getOffset(), packet.getLength());
If there is overhead in the packet, e.g. a sequence number, which there should be, you will need to adjust the offset and length accordingly.
NB TCP will ensure 'everything gets transferred and is not damaged'.