## Demo 1: DHT for Connecting Peers & Sharing Content (Go and JS nodes)
## Decentralized messaging network that anyone can broadcast/subscribe messages anonymously.
**Directory**: `content-dht-provide-find`
Anonymity is achieved by implementing Dandelion protocol on top of libp2p's pub/sub module, dandelion is a privacy preserving protocol to make message sender anonymous, it has 2 phases, the first phase is stem phase, where messages go through a psuedo-random path, the second phase is fluffing, when the message reaches the last node(randomly chosen), the message is diffused to its surrounding peers, so the third party observer cannot track back the node original node who send the message, because the message is relayed through an anonymous graph.
Message broadcasting is implemented by libp2p floodsub.
**What it demonstrates:** A new DHT is created by the Go program `dht-interop`. In a separate terminal or machine, a Node.js program connects to this DHT. One connected, each verifies that it can find the other's content via the DHT.
`-b` means bootstrap mode. In this example, the go program is always the bootstrap node, so `-b` is always required. (***TODO***: eliminate this superfluous option)
Note that the node ID of `dht-interop` is always `Qm...6aJ9oRuEzWa` because it is being read in from `../util/private_key.bin.bootstrapper.Wa` (a private key marshalled to X.509 generated by the program `util/private-key-gen`). This is to keep the peer id of the bootstrap server stable across invocations.
**Second terminal:** run the command printed out by dht-interop, replacing 127.0.0.1 with the IP of the server where dht-interop is listening. Example:
@ -49,66 +28,4 @@ The bootstrapper creates a new libp2p node, subscribes to the shared topic strin
(Note that the node ID of `pubsub-interop` is going to be `Qm...6aJ9oRuEzWa`. Node IDs in libp2p are just public keys, and the public key `Qm...6aJ9oRuEzWa` is derived from the private key file `../util/private_key.bin.bootstrapper.Wa`. That file is just an X.509 keypair generated by the included program `util/private-key-gen`). We use fixed public/private keypairs for each node in this example to keep things simple.)
**Second terminal**: Create a go peer to connect to bootstrapper and publish on the topic
```
cd pubsub
./pubsub-interop ../util/private_key.bin.peer.Sk
```
This peer, which is not in bootstrapper mode, creates a node, subscribes to the shared topic string, spawns the same go routine, and then loops forever requesting user input and publishing each line to the topic.
**Third terminal**: Create a JS peer to connect to bootstrap and publish on topic
This JS peer will accept lines of text typed on stdin, and publish them on the PubSub topic.
(Note that the JS peer generates a new identity (public/private keypair) each time, and prints its public key to stdout. This is a deficiency in the demo; to be consistent with the Go code it should accept a private key on the CLI.)
**Fourth terminal**: Creates a Rust peer to connect to the bootstrap node and then subscribe and publish on the topic:
```
cd pubsub/rust
cargo run
```
The Rust peer starts up, listens on port 6002, and then dials the boostrap peer. (TODO: rust-libp2p#471) It is now subscribed to the same topic as the other peers.
If you return to the second, third or fourth terminals and type a message, the bootstrapper and the other 2 peers will all print your message.
**Conclusion**
You now have a chat app on a private libp2p network where each node can exchange messages using PubSub.
## Debugging Notes
**JS** To see debug messages from the Node.js program, use the `DEBUG` environment variable:
Rai Yang
5 years ago
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