tubemail

Tube Mail Network

Once connected, you get a fully meshed network to throw around some Buffers. TLS-secured of course. The - I think - coolest feature is that peers will find each other automagically. Without any central instance. Without an IP address list of the other peers. Just kick off a new peer and it will become a member of the mesh.

Hot and fresh in Version 2.0.0: Even more robust discovery of other peers! Peers now exchange their lists of connected neighbours. This eliminate the need for a discovery service that finds all other peers. No problems, if it misses some one ...

Example

Install tubemail and tubemail-mdns.

npm install -g tubemail tubemail-mdns

Create some certificates and keys:

mkdir example
cd example
cat > config.sh <<EOF
COUNTRY="VA"
STATE="Fairyland"
LOCALITY="Rainbow"
EOF
createHood hood
createPeer hood peer1
createPeer hood peer2

Create scripts for the peers in the same directory:

// peer1.js
const fs = require('fs');
const tubemail = require('tubemail');

const toBuffer = (obj) => Buffer.from(obj.toString());

tubemail({
	key: fs.readFileSync('./hood.peer1.key'),
	cert: fs.readFileSync('./hood.peer1.crt'),
	ca: fs.readFileSync('./hood.crt'),
	discovery: require('tubemail-mdns');
}).then((hood) => {
	// Send the current time every second
	setInterval(() => hood.send(toBuffer(new Date())), 1000);

	// Say hello to new neighs
	hood.on('foundNeigh', (n) => n.send(toBuffer(`Hello ${n.info.subject.commonName}!`)));
});

// peer2.js
const fs = require('fs');
const tubemail = require('tubemail');

const toBuffer = (obj) => Buffer.from(obj.toString());

tubemail({
	key: fs.readFileSync('./hood.peer2.key'),
	cert: fs.readFileSync('./hood.peer2.crt'),
	ca: fs.readFileSync('./hood.crt'),
	discovery: require('tubemail-mdns')
}).then((hood) => {
	hood.on('message', (msg) => console.log(msg.toString()));
});

Start the scripts. It doesn't matter if they are started on the same machine or on a different machine on the same network! :)

API

const tubemail = require('tubemail');
tubemail.join(opts).then((hood) => {...});

Joins / create a new hood. opts is an object:

• ca: Hood's certificate. Required.
• key: Peer's private key. Required.
• cert: Peer's certificate. Required.
• port: The port to listen on. Default: {from: 4816, to: 4819}. It can be of type:
  • Number: Listen on the specified port.
  • Array: A list of ports. Tube Mail will select a free one.
  • Object: A port range. First port is specified by item from, last one by item to.
• discovery: A discovery service or an Array of discovery services. The service can been a Function or an Object. If the service is an Object, it must contain the items host and port pointing to another instance of Tube Mail. If the discovery service is a Function, it is a factory. The factory's interface: (hood, newPeer) => stopDiscovery:
  • hood: The hood's instance. Important object items:
    • port: The actual port this peer is listening on.
    • fingerprint: The hood's fingerprint for finding other peers. All peers using the same hood certificate will receive the same fingerprint to search for.
    • id: The peer's local randomly generated ID.
  • newPeer: A callback function that shall be called if discovery discovered a new peer. It awaits one object with the items host and port. I think you know what to fill in ;)
  • stopDiscovery: If this is a function, it will be called by Tube Mail once discovery shall be stopped. The function may return a Promise that is fulfilled once the service is fully shut down.
• reconnectInterval: A time in ms. If a connection to a neighbour is lost, try to reconnect in the given interval. Default: 120 * 1000
• reconnectTimeout: A time in ms. If the connection to a lost neighbour cannot be reestablished during the given timeout, give up. Default: 7 * 24 * 60 * 60 * 1000

You do not have to implement the discovery by yourself if you don't want to. Check out:

• tubemail-mdns: Discovers other peers on the local network using mDNS / DNS-SD.
• tubemail-dht: (Ab)uses the Bittorrent DHT for discovering peers on the internet. TBH: This feels a little bit magical :) Don't forget to forward the ports if you are forced to have your peer behind some evil NAT.

Resolved hood is an instance of Hood.

Class: Hood

Property: port

The actual port Tube Mail is listening on for incoming connections. This is quite handy if you specified several listen ports.

Property: fingerprint

The hood's fingerprint that is used to identify other peers belonging to the same hood.

Property: info

All information hold by the local peer's certificate. This is useful for obtaining the local common name: hood.info.subject.commonName.

Property: id

The local ID. It will be generated on startup and is random.

Some additional facts: The ID uniquely identifies an instance of Tube Mail. Its main purpose is to determine who has to connect to whom: The connected peer always has the higher ID compared to the connecting peer. If the handshake figures out that the oppsite is the case the connection attempt is aborted. Thereupon, the connected peer becomes the connecting peer and establishes a connection. This rule ensures that only one connection is established between two peers.

Property: neighbours

An array to the Neighbour instances of all connected neighbours.

Event: discovery

hood.on('discovery', (peer) => {...});

Is fired every time the discovery service discovered an unknown peer. The object peer holds the information of that peer and has at least the properties host and port.

Tubemail internally ensures that the potential neighbour is connected.

Event: foundNeigh

hood.on('foundNeigh', (neigh) => {...});

Will be emitted if a new connection as been successfully established to neigh.

Event: lostNeigh

hood.on('lostNeigh', (neigh) => {...});

Will be emitted if neigh disappeared.

Event: message

hood.on('message', (message, neigh) => {...});

Will be fired if a message has been received form neigh. message is always a Buffer.

Event: goodbye

hood.on('goodbye', () => {...});

Once we have left the hood (i.e. stopped discovery, disconnected from all neighbours and closed the port), the goodbye event will be fired.

Method: send

hood.send(message).then(() => {...});

Broadcast message to all connected neighbours. message must be a Buffer. Resolves once message has been sent to all neighbours.

Method: leave

hood.leave().then(() => {...});

Shutdown Tube Mail. Will resolve once the listening socket and connections have been closed.

Method: getNeigh

const neigh = hood.getNeigh(info);

Lookup a neighbour that matches the given info. info has the following attributes:

• host: The neighbour's IP address
• port: The neighbour's listen port
• id: The neighbour's ID

Every given attribute has to match.

Class: Neighbour

Property: host

The remote IP address of our neighbour.

Property: port

The remote port we are connected to.

Property: listenPort

The port the neighbour is listening on to new connections. This port differs from port if this is an inbound connection.

Property: direction

A string with the following possible values indication the connection type:

• 'in': inbound connection
• 'out': outbound connection

Property: info

Information contained by the remote peer's certificate. This is handy for identifying the neighbour by reading neigh.info.subject.commonName.

Property: id

The remote ID. This one is (or: should be) random.

Event: message

neigh.on('message', (message) => {...});

Will be fired if a message has been received form neigh. messageis always a Buffer.

Event: goodbye

neigh.on('goodbye', () => {...});

Tube Mail neighbours are kind neighbours. They always say goodbye if they are leaving.

Method: send

neigh.send(message).then(() => {...});

Send message to neigh. message must be a Buffer. Resolves when message has drained.

Debugging

If you are experiencing unexpected behaviour and wonder why other peers aren't connecting, you can make Tube Mail more verbose and report changes of the internal state machine by setting this environment variable:

export NODE_DEBUG=tubemail-hood,tubemail-connection,tubemail-neigh