mirror of
https://source.quilibrium.com/quilibrium/ceremonyclient.git
synced 2024-12-27 09:05:18 +00:00
101 lines
2.8 KiB
Markdown
101 lines
2.8 KiB
Markdown
# p2p chat app with libp2p [support peer discovery using mdns]
|
|
|
|
This program demonstrates a simple p2p chat application. You will learn how to discover a peer in the network (using mdns), connect to it and open a chat stream. This example is heavily influenced by (and shamelessly copied from) `chat-with-rendezvous` example
|
|
|
|
## How to build this example?
|
|
|
|
```
|
|
go get -v -d ./...
|
|
|
|
go build
|
|
```
|
|
|
|
## Usage
|
|
|
|
Use two different terminal windows to run
|
|
|
|
```
|
|
./chat-with-mdns -port 6666
|
|
./chat-with-mdns -port 6668
|
|
```
|
|
|
|
|
|
## So how does it work?
|
|
|
|
1. **Configure a p2p host**
|
|
```go
|
|
ctx := context.Background()
|
|
|
|
// libp2p.New constructs a new libp2p Host.
|
|
// Other options can be added here.
|
|
host, err := libp2p.New()
|
|
```
|
|
[libp2p.New](https://godoc.org/github.com/libp2p/go-libp2p#New) is the constructor for libp2p node. It creates a host with given configuration.
|
|
|
|
2. **Set a default handler function for incoming connections.**
|
|
|
|
This function is called on the local peer when a remote peer initiate a connection and starts a stream with the local peer.
|
|
```go
|
|
// Set a function as stream handler.
|
|
host.SetStreamHandler("/chat/1.1.0", handleStream)
|
|
```
|
|
|
|
```handleStream``` is executed for each new stream incoming to the local peer. ```stream``` is used to exchange data between local and remote peer. This example uses non blocking functions for reading and writing from this stream.
|
|
|
|
```go
|
|
func handleStream(stream net.Stream) {
|
|
|
|
// Create a buffer stream for non blocking read and write.
|
|
rw := bufio.NewReadWriter(bufio.NewReader(stream), bufio.NewWriter(stream))
|
|
|
|
go readData(rw)
|
|
go writeData(rw)
|
|
|
|
// 'stream' will stay open until you close it (or the other side closes it).
|
|
}
|
|
```
|
|
|
|
3. **Find peers nearby using mdns**
|
|
|
|
Start [mdns discovery](https://godoc.org/github.com/libp2p/go-libp2p/p2p/discovery#NewMdnsService) service in host.
|
|
|
|
```go
|
|
ser, err := discovery.NewMdnsService(peerhost, rendezvous)
|
|
```
|
|
register [Notifee interface](https://godoc.org/github.com/libp2p/go-libp2p/p2p/discovery#Notifee) with service so that we get notified about peer discovery
|
|
|
|
```go
|
|
n := &discoveryNotifee{}
|
|
ser.RegisterNotifee(n)
|
|
```
|
|
|
|
|
|
4. **Open streams to peers found.**
|
|
|
|
Finally we open stream to the peers we found, as we find them
|
|
|
|
```go
|
|
peer := <-peerChan // will block until we discover a peer
|
|
fmt.Println("Found peer:", peer, ", connecting")
|
|
|
|
if err := host.Connect(ctx, peer); err != nil {
|
|
fmt.Println("Connection failed:", err)
|
|
}
|
|
|
|
// open a stream, this stream will be handled by handleStream other end
|
|
stream, err := host.NewStream(ctx, peer.ID, protocol.ID(cfg.ProtocolID))
|
|
|
|
if err != nil {
|
|
fmt.Println("Stream open failed", err)
|
|
} else {
|
|
rw := bufio.NewReadWriter(bufio.NewReader(stream), bufio.NewWriter(stream))
|
|
|
|
go writeData(rw)
|
|
go readData(rw)
|
|
fmt.Println("Connected to:", peer)
|
|
}
|
|
```
|
|
|
|
## Authors
|
|
1. Bineesh Lazar
|