cs3103-p2p

CS3103 Project

Setup and Requirements

1. Install python 3 and pip3 on your local development pc.
2. git clone the current repo
3. pip3 install virtualenv
4. source /cs3103-env/bin/activate
5. Start developing

Please start an instance of the dns server first by running python3 p2pdns.py

To start an instance of the p2p node, run: python3 p2pmain.py 127.0.X.X

If you ever download a third-party python library, remember to pip3 freeze > requirements.txt to update the dependencies list.

Testing

1. Install Vagrant and Virtualbox
2. cd to the directory
3. vagrant up and wait for it to initialise
4. vagrant ssh dns/alpha/beta/charlie/delta/echo into either vm.
5. To transfer file, run vagrant config-ssh to check the port of the vm
6. cd to parent dir and sudo scp -P <PORT> -i ./cs3103-p2p/.vagrant/machines/<VM NAME>/virtualbox/private_key -r cs3103-p2p/ [email protected]:/home/vagrant
7. Run p2pdns.py in dns vm.
8. Run p2pmain.py in the other peers

Components

P2P DNS

P2P DNS server serves as a introducer whenever a new peer wants to join the network. The information is stored in a sqlite3 db.

P2P Main

This the the main program that the user will run. It is a wrapper for P2P Client and P2P Server. P2P Client will handle the various user interactions. P2P Server will handle file uploading, file downloading and DHT queries. P2P Client will communicate with P2P Server using Unix Domain Sockets (UDS) while the communication between P2P Server of different peer will be done using standard TCP sockets.

Application layer Protocols:

The different protocols implemented provides a systematic manner for different components to communicate with each other. Furthermore, since we are using TCP Byte Stream sockets, we need a way to delimit where our messages end. Hence -- protocols.

P2P Client - P2P DNS

Requests

General Format: op [...args]\r\n

1. JOIN <peer_id> <ip-addr>

Responses

General Format:

code message content-length\r\n
dataline...\r\n
dataline...\r\n

P2P Server - P2P Server

General Format: op [...args]\r\n

Node Joining Network

1. GET_NEIGHBOURS <node_id> <node_ip_addr>
2. RET_NEIGHBOURS <predecessor_id> <predecessor_ip_addr> <successor_id> <successor_ip_addr> <next_successor_id> <next_succcessor_ip_addr>
3. UPDATE_NEXT_SUCCESSOR <next_successor_id> <next_succcessor_ip_addr>
4. UPDATE_PREDECESSOR <predecessor_id> <predecessor_ip_addr>

Requests

1. INIT_PEER_TABLE
2. LIST_ALL_FILES
3. SEARCH <filename>
4. DOWNLOAD <filename>
5. UPLOAD <filename>

Responses

General Format:

code message content-length\r\n
dataline...\r\n
dataline...\r\n

References

https://realpython.com/python-sockets/

https://pymotw.com/3/socket/uds.html