Merge pull request #284 from upperwal/master

Added example "chat" with README

examples/README.md

@@ -11,4 +11,5 @@ Let us know if you find any issue or if you want to contribute and add a new tut
 - [Building an http proxy with libp2p](./http-proxy)
 - [Protocol Multiplexing with multicodecs](./protocol-multiplexing-with-multicodecs)
 - [An echo host](./echo)
-- [Multicodecs with protobufs](./multipro)
\ No newline at end of file
+- [Multicodecs with protobufs](./multipro)
+- [P2P chat application](./chat)
\ No newline at end of file

examples/chat/README.md

+# p2p chat app with libp2p
+
+This program demonstrates a simple p2p chat application. It can work between two peers if
+1. Both have private IP address (same network).
+2. At least one of them has a public IP address.
+
+Assume if 'A' and 'B' are on different networks host 'A' may or may not have a public IP address but host 'B' has one.
+
+Usage: Run `./chat -sp <SOURCE_PORT>` on host 'B' where <SOURCE_PORT> can be any port number. Now run `./chat -d <MULTIADDR_B>` on node 'A' [`<MULTIADDR_B>` is multiaddress of host 'B' which can be obtained from host 'B' console].
+
+## Build
+
+To build the example, first run `make deps` in the root directory.
+
+```
+> make deps
+> go build ./examples/chat
+```
+
+## Usage
+
+On node 'B'
+
+```
+> ./chat -sp 3001
+Run ./chat -d /ip4/127.0.0.1/tcp/3001/ipfs/QmdXGaeGiVA745XorV1jr11RHxB9z4fqykm6xCUPX1aTJo
+
+2018/02/27 01:21:32 Got a new stream!
+> hi (received messages in green colour)
+> hello (sent messages in white colour)
+> no
+```
+
+On node 'A'. Replace 127.0.0.1 with <PUBLIC_IP> if node 'B' has one.
+
+```
+> ./chat -d /ip4/127.0.0.1/tcp/3001/ipfs/QmdXGaeGiVA745XorV1jr11RHxB9z4fqykm6xCUPX1aTJo
+Run ./chat -d /ip4/127.0.0.1/tcp/3001/ipfs/QmdXGaeGiVA745XorV1jr11RHxB9z4fqykm6xCUPX1aTJo
+
+This node's multiaddress:
+/ip4/0.0.0.0/tcp/0/ipfs/QmWVx9NwsgaVWMRHNCpesq1WQAw2T3JurjGDNeVNWifPS7
+> hi
+> hello
+```
+
+**NOTE: debug mode is enabled by default, debug mode will always generate same node id (on each node) on every execution. Disable debug using `--debug false` flag while running your executable.**
+
+## Authors
+1. Abhishek Upperwal
\ No newline at end of file

examples/chat/chat.go

+/*
+*
+* The MIT License (MIT)
+*
+* Copyright (c) 2014 Juan Batiz-Benet
+*
+* Permission is hereby granted, free of charge, to any person obtaining a copy
+* of this software and associated documentation files (the "Software"), to deal
+* in the Software without restriction, including without limitation the rights
+* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+* copies of the Software, and to permit persons to whom the Software is
+* furnished to do so, subject to the following conditions:
+*
+* The above copyright notice and this permission notice shall be included in
+* all copies or substantial portions of the Software.
+*
+* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+* THE SOFTWARE.
+*
+* This program demonstrate a simple chat application using p2p communication.
+*
+ */
+
+package main
+
+import (
+	"bufio"
+	"context"
+	"crypto/rand"
+	"flag"
+	"fmt"
+	"io"
+	"log"
+	mrand "math/rand"
+	"os"
+
+	"github.com/libp2p/go-libp2p-crypto"
+	"github.com/libp2p/go-libp2p-host"
+	"github.com/libp2p/go-libp2p-net"
+	"github.com/libp2p/go-libp2p-peer"
+	"github.com/libp2p/go-libp2p-peerstore"
+	"github.com/libp2p/go-libp2p-swarm"
+	"github.com/libp2p/go-libp2p/p2p/host/basic"
+	"github.com/multiformats/go-multiaddr"
+)
+
+/*
+* addAddrToPeerstore parses a peer multiaddress and adds
+* it to the given host's peerstore, so it knows how to
+* contact it. It returns the peer ID of the remote peer.
+* @credit examples/http-proxy/proxy.go
+ */
+func addAddrToPeerstore(h host.Host, addr string) peer.ID {
+	// The following code extracts target's the peer ID from the
+	// given multiaddress
+	ipfsaddr, err := multiaddr.NewMultiaddr(addr)
+	if err != nil {
+		log.Fatalln(err)
+	}
+	pid, err := ipfsaddr.ValueForProtocol(multiaddr.P_IPFS)
+	if err != nil {
+		log.Fatalln(err)
+	}
+
+	peerid, err := peer.IDB58Decode(pid)
+	if err != nil {
+		log.Fatalln(err)
+	}
+
+	// Decapsulate the /ipfs/<peerID> part from the target
+	// /ip4/<a.b.c.d>/ipfs/<peer> becomes /ip4/<a.b.c.d>
+	targetPeerAddr, _ := multiaddr.NewMultiaddr(
+		fmt.Sprintf("/ipfs/%s", peer.IDB58Encode(peerid)))
+	targetAddr := ipfsaddr.Decapsulate(targetPeerAddr)
+
+	// We have a peer ID and a targetAddr so we add
+	// it to the peerstore so LibP2P knows how to contact it
+	h.Peerstore().AddAddr(peerid, targetAddr, peerstore.PermanentAddrTTL)
+	return peerid
+}
+
+func handleStream(s net.Stream) {
+	log.Println("Got a new stream!")
+
+	// Create a buffer stream for non blocking read and write.
+	rw := bufio.NewReadWriter(bufio.NewReader(s), bufio.NewWriter(s))
+
+	go readData(rw)
+	go writeData(rw)
+
+	// stream 's' will stay open until you close it (or the other side closes it).
+}
+func readData(rw *bufio.ReadWriter) {
+	for {
+		str, _ := rw.ReadString('\n')
+
+		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 {
+			panic(err)
+		}
+
+		rw.WriteString(fmt.Sprintf("%s\n", sendData))
+		rw.Flush()
+	}
+
+}
+
+func main() {
+
+	sourcePort := flag.Int("sp", 0, "Source port number")
+	dest := flag.String("d", "", "Dest MultiAddr String")
+	help := flag.Bool("help", false, "Display Help")
+	debug := flag.Bool("debug", true, "Debug generated same node id on every execution.")
+
+	flag.Parse()
+
+	if *help {
+		fmt.Printf("This program demonstrates a simple p2p chat application using libp2p\n\n")
+		fmt.Printf("Usage: Run './chat -sp <SOURCE_PORT>' where <SOURCE_PORT> can be any port number. Now run './chat -d <MULTIADDR>' where <MULTIADDR> is multiaddress of previous listener host.\n")
+
+		os.Exit(0)
+	}
+
+	// If debug is enabled used constant random source else cryptographic randomness.
+	var r io.Reader
+	if *debug {
+		// Constant random source. This will always generate the same host ID on multiple execution.
+		// Don't do this in production code.
+		r = mrand.New(mrand.NewSource(int64(*sourcePort)))
+	} else {
+		r = rand.Reader
+	}
+
+	// Creates a new RSA key pair for this host
+	prvKey, pubKey, err := crypto.GenerateKeyPairWithReader(crypto.RSA, 2048, r)
+
+	if err != nil {
+		panic(err)
+	}
+
+	// Getting host ID from public key.
+	// host ID is the hash of public key
+	nodeID, _ := peer.IDFromPublicKey(pubKey)
+
+	// 0.0.0.0 will listen on any interface device
+	sourceMultiAddr, _ := multiaddr.NewMultiaddr(fmt.Sprintf("/ip4/0.0.0.0/tcp/%d", *sourcePort))
+
+	// Adding self to the peerstore.
+	ps := peerstore.NewPeerstore()
+	ps.AddPrivKey(nodeID, prvKey)
+	ps.AddPubKey(nodeID, pubKey)
+
+	// Creating a new Swarm network.
+	network, err := swarm.NewNetwork(context.Background(), []multiaddr.Multiaddr{sourceMultiAddr}, nodeID, ps, nil)
+
+	if err != nil {
+		panic(err)
+	}
+
+	// NewHost constructs a new *BasicHost and activates it by attaching its
+	// stream and connection handlers to the given inet.Network (network).
+	// Other options like NATManager can also be added here.
+	// See docs: https://godoc.org/github.com/libp2p/go-libp2p/p2p/host/basic#HostOpts
+	host := basichost.New(network)
+
+	if *dest == "" {
+		// Set a function as stream handler.
+		// This function  is called when a peer initiate a connection and starts a stream with this peer.
+		// Only applicable on the receiving side.
+		host.SetStreamHandler("/chat/1.0.0", handleStream)
+
+		fmt.Printf("Run './chat -d /ip4/127.0.0.1/tcp/%d/ipfs/%s' on another console.\n You can replace 127.0.0.1 with public IP as well.\n", *sourcePort, host.ID().Pretty())
+		fmt.Printf("\nWaiting for incoming connection\n\n")
+		// Hang forever
+		<-make(chan struct{})
+
+	} else {
+
+		// Add destination peer multiaddress in the peerstore.
+		// This will be used during connection and stream creation by libp2p.
+		peerID := addAddrToPeerstore(host, *dest)
+
+		fmt.Println("This node's multiaddress: ")
+		// IP will be 0.0.0.0 (listen on any interface) and port will be 0 (choose one for me).
+		// Although this node will not listen for any connection. It will just initiate a connect with
+		// one of its peer and use that stream to communicate.
+		fmt.Printf("%s/ipfs/%s\n", sourceMultiAddr, host.ID().Pretty())
+
+		// Start a stream with peer with peer Id: 'peerId'.
+		// Multiaddress of the destination peer is fetched from the peerstore using 'peerId'.
+		s, err := host.NewStream(context.Background(), peerID, "/chat/1.0.0")
+
+		if err != nil {
+			panic(err)
+		}
+
+		// Create a buffered stream so that read and writes are non blocking.
+		rw := bufio.NewReadWriter(bufio.NewReader(s), bufio.NewWriter(s))
+
+		// Create a thread to read and write data.
+		go writeData(rw)
+		go readData(rw)
+
+		// Hang forever.
+		select {}
+
+	}
+}