chore: bring examples back into repository and add tests

.gitignore

@@ -1,4 +1,2 @@
 *.swp
-examples/echo/echo
-examples/multicodecs/multicodecs
-.idea
+.idea

README.md

@@ -78,7 +78,7 @@ As new releases of go-libp2p are made available, you can upgrade your applicatio
 
 ### Examples
 
-Examples can be found in the [examples repo](https://github.com/libp2p/go-libp2p-examples).
+Examples can be found in the [examples folder](examples).
 
 ## Development
 
@@ -180,7 +180,6 @@ List of packages currently in existence for libp2p:
 | [`go-libp2p-http`](//github.com/libp2p/go-libp2p-http) | [![Travis CI](https://travis-ci.com/libp2p/go-libp2p-http.svg?branch=master)](https://travis-ci.com/libp2p/go-libp2p-http) | [![codecov](https://codecov.io/gh/libp2p/go-libp2p-http/branch/master/graph/badge.svg)](https://codecov.io/gh/libp2p/go-libp2p-http) | HTTP on top of libp2p streams |
 | **Testing and examples** |
 | [`go-libp2p-testing`](//github.com/libp2p/go-libp2p-testing) | [![Travis CI](https://travis-ci.com/libp2p/go-libp2p-testing.svg?branch=master)](https://travis-ci.com/libp2p/go-libp2p-testing) | [![codecov](https://codecov.io/gh/libp2p/go-libp2p-testing/branch/master/graph/badge.svg)](https://codecov.io/gh/libp2p/go-libp2p-testing) | a collection of testing utilities for libp2p |
-| [`go-libp2p-examples`](//github.com/libp2p/go-libp2p-examples) | [![Travis CI](https://travis-ci.com/libp2p/go-libp2p-examples.svg?branch=master)](https://travis-ci.com/libp2p/go-libp2p-examples) | [![codecov](https://codecov.io/gh/libp2p/go-libp2p-examples/branch/master/graph/badge.svg)](https://codecov.io/gh/libp2p/go-libp2p-examples) | go-libp2p examples and tutorials |
 
 # Contribute
 

examples/README.md

@@ -1,3 +1,41 @@
-# go-libp2p Examples
+# `go-libp2p` examples and tutorials
 
-The go-libp2p examples have moved to [go-libp2p-examples](https://github.com/libp2p/go-libp2p-examples).
+[![](https://img.shields.io/badge/made%20by-Protocol%20Labs-blue.svg?style=flat-square)](https://protocol.ai)
+[![](https://img.shields.io/badge/project-libp2p-yellow.svg?style=flat-square)](https://libp2p.io/)
+[![](https://img.shields.io/badge/freenode-%23libp2p-yellow.svg?style=flat-square)](http://webchat.freenode.net/?channels=%23libp2p)
+[![Discourse posts](https://img.shields.io/discourse/https/discuss.libp2p.io/posts.svg)](https://discuss.libp2p.io)
+
+In this folder, you can find a variety of examples to help you get started in using go-libp2p. Every example as a specific purpose and some of each incorporate a full tutorial that you can follow through, helping you expand your knowledge about libp2p and p2p networks in general.
+
+Let us know if you find any issue or if you want to contribute and add a new tutorial, feel welcome to submit a pr, thank you!
+
+## Examples and Tutorials
+
+- [The libp2p 'host'](./libp2p-host)
+- [Building an http proxy with libp2p](./http-proxy)
+- [An echo host](./echo)
+- [Multicodecs with protobufs](./multipro)
+- [P2P chat application](./chat)
+- [P2P chat application w/ rendezvous peer discovery](./chat-with-rendezvous)
+- [P2P chat application with peer discovery using mdns](./chat-with-mdns)
+- [A chapter based approach to building a libp2p application](./ipfs-camp-2019/) _Created for [IPFS Camp 2019](https://github.com/ipfs/camp/tree/master/CORE_AND_ELECTIVE_COURSES/CORE_COURSE_B)_
+
+For js-libp2p examples, check https://github.com/libp2p/js-libp2p/tree/master/examples
+
+## Troubleshooting
+
+When building the examples ensure you have a clean `$GOPATH`. If you have checked out and built other `libp2p` repos then you may get errors similar to the one below when building the examples. Note that the use of the `gx` package manager **is not required** to run the examples or to use `libp2p`.
+```
+$:~/go/src/github.com/libp2p/go-libp2p-examples/libp2p-host$ go build host.go
+# command-line-arguments
+./host.go:36:18: cannot use priv (type "github.com/libp2p/go-libp2p-crypto".PrivKey) as type "gx/ipfs/QmNiJiXwWE3kRhZrC5ej3kSjWHm337pYfhjLGSCDNKJP2s/go-libp2p-crypto".PrivKey in argument to libp2p.Identity:
+        "github.com/libp2p/go-libp2p-crypto".PrivKey does not implement "gx/ipfs/QmNiJiXwWE3kRhZrC5ej3kSjWHm337pYfhjLGSCDNKJP2s/go-libp2p-crypto".PrivKey (wrong type for Equals method)
+                have Equals("github.com/libp2p/go-libp2p-crypto".Key) bool
+                want Equals("gx/ipfs/QmNiJiXwWE3kRhZrC5ej3kSjWHm337pYfhjLGSCDNKJP2s/go-libp2p-crypto".Key) bool
+```
+
+To obtain a clean `$GOPATH` execute the following:
+```
+> mkdir /tmp/libp2p-examples
+> export GOPATH=/tmp/libp2p/examples
+```

examples/chat-with-mdns/.gitignore

@@ -0,0 +1 @@
+chat-with-mdns

examples/chat-with-mdns/README.md

@@ -0,0 +1,100 @@
+# 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(ctx)
+```
+[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(ctx, peerhost, time.Hour, 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 untill 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

examples/chat-with-mdns/flags.go

@@ -0,0 +1,24 @@
+package main
+
+import (
+	"flag"
+)
+
+type config struct {
+	RendezvousString string
+	ProtocolID       string
+	listenHost       string
+	listenPort       int
+}
+
+func parseFlags() *config {
+	c := &config{}
+
+	flag.StringVar(&c.RendezvousString, "rendezvous", "meetme", "Unique string to identify group of nodes. Share this with your friends to let them connect with you")
+	flag.StringVar(&c.listenHost, "host", "0.0.0.0", "The bootstrap node host listen address\n")
+	flag.StringVar(&c.ProtocolID, "pid", "/chat/1.1.0", "Sets a protocol id for stream headers")
+	flag.IntVar(&c.listenPort, "port", 4001, "node listen port")
+
+	flag.Parse()
+	return c
+}

examples/chat-with-mdns/main.go

@@ -0,0 +1,141 @@
+package main
+
+import (
+	"bufio"
+	"context"
+	"crypto/rand"
+	"flag"
+	"fmt"
+	"os"
+
+	"github.com/libp2p/go-libp2p"
+	"github.com/libp2p/go-libp2p-core/crypto"
+	"github.com/libp2p/go-libp2p-core/network"
+	"github.com/libp2p/go-libp2p-core/protocol"
+
+	"github.com/multiformats/go-multiaddr"
+)
+
+func handleStream(stream network.Stream) {
+	fmt.Println("Got a new 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).
+}
+
+func readData(rw *bufio.ReadWriter) {
+	for {
+		str, err := rw.ReadString('\n')
+		if err != nil {
+			fmt.Println("Error reading from buffer")
+			panic(err)
+		}
+
+		if str == "" {
+			return
+		}
+		if str != "\n" {
+			// Green console colour: 	\x1b[32m
+			// Reset console colour: 	\x1b[0m
+			fmt.Printf("\x1b[32m%s\x1b[0m> ", str)
+		}
+
+	}
+}
+
+func writeData(rw *bufio.ReadWriter) {
+	stdReader := bufio.NewReader(os.Stdin)
+
+	for {
+		fmt.Print("> ")
+		sendData, err := stdReader.ReadString('\n')
+		if err != nil {
+			fmt.Println("Error reading from stdin")
+			panic(err)
+		}
+
+		_, err = rw.WriteString(fmt.Sprintf("%s\n", sendData))
+		if err != nil {
+			fmt.Println("Error writing to buffer")
+			panic(err)
+		}
+		err = rw.Flush()
+		if err != nil {
+			fmt.Println("Error flushing buffer")
+			panic(err)
+		}
+	}
+}
+
+func main() {
+	help := flag.Bool("help", false, "Display Help")
+	cfg := parseFlags()
+
+	if *help {
+		fmt.Printf("Simple example for peer discovery using mDNS. mDNS is great when you have multiple peers in local LAN.")
+		fmt.Printf("Usage: \n   Run './chat-with-mdns'\nor Run './chat-with-mdns -host [host] -port [port] -rendezvous [string] -pid [proto ID]'\n")
+
+		os.Exit(0)
+	}
+
+	fmt.Printf("[*] Listening on: %s with port: %d\n", cfg.listenHost, cfg.listenPort)
+
+	ctx := context.Background()
+	r := rand.Reader
+
+	// Creates a new RSA key pair for this host.
+	prvKey, _, err := crypto.GenerateKeyPairWithReader(crypto.RSA, 2048, r)
+	if err != nil {
+		panic(err)
+	}
+
+	// 0.0.0.0 will listen on any interface device.
+	sourceMultiAddr, _ := multiaddr.NewMultiaddr(fmt.Sprintf("/ip4/%s/tcp/%d", cfg.listenHost, cfg.listenPort))
+
+	// libp2p.New constructs a new libp2p Host.
+	// Other options can be added here.
+	host, err := libp2p.New(
+		ctx,
+		libp2p.ListenAddrs(sourceMultiAddr),
+		libp2p.Identity(prvKey),
+	)
+
+	if err != nil {
+		panic(err)
+	}
+
+	// Set a function as stream handler.
+	// This function is called when a peer initiates a connection and starts a stream with this peer.
+	host.SetStreamHandler(protocol.ID(cfg.ProtocolID), handleStream)
+
+	fmt.Printf("\n[*] Your Multiaddress Is: /ip4/%s/tcp/%v/p2p/%s\n", cfg.listenHost, cfg.listenPort, host.ID().Pretty())
+
+	peerChan := initMDNS(ctx, host, cfg.RendezvousString)
+
+	peer := <-peerChan // will block untill 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)
+	}
+
+	select {} //wait here
+}

examples/chat-with-mdns/mdns.go

@@ -0,0 +1,35 @@
+package main
+
+import (
+	"context"
+	"time"
+
+	"github.com/libp2p/go-libp2p-core/host"
+	"github.com/libp2p/go-libp2p-core/peer"
+	"github.com/libp2p/go-libp2p/p2p/discovery"
+)
+
+type discoveryNotifee struct {
+	PeerChan chan peer.AddrInfo
+}
+
+//interface to be called when new  peer is found
+func (n *discoveryNotifee) HandlePeerFound(pi peer.AddrInfo) {
+	n.PeerChan <- pi
+}
+
+//Initialize the MDNS service
+func initMDNS(ctx context.Context, peerhost host.Host, rendezvous string) chan peer.AddrInfo {
+	// An hour might be a long long period in practical applications. But this is fine for us
+	ser, err := discovery.NewMdnsService(ctx, peerhost, time.Hour, rendezvous)
+	if err != nil {
+		panic(err)
+	}
+
+	//register with service so that we get notified about peer discovery
+	n := &discoveryNotifee{}
+	n.PeerChan = make(chan peer.AddrInfo)
+
+	ser.RegisterNotifee(n)
+	return n.PeerChan
+}

examples/chat-with-rendezvous/.gitignore

@@ -0,0 +1 @@
+chat-with-rendezvous