http://i3xi5qxvbrngh3g6o7czwjfxwjzigook7zxzjmgwg5b7xnjcn5hzciad.onion/proposals/348-udp-app-support.html
Each datagram within the stream would still need to be tagged with a peer address/port in some way. This approach would involve a single new type of stream, and two new messages that pertain to these mapping streams: NEW_UDP_MAPPING Always client-to-exit. Creates a new mapping, with a specified stream ID.