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whisper.go
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whisper.go
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package p2p
import (
"bufio"
"context"
"fmt"
"io"
"log"
"os"
"sync"
"github.com/libp2p/go-libp2p"
"github.com/libp2p/go-libp2p-core/crypto"
"github.com/libp2p/go-libp2p-core/host"
"github.com/libp2p/go-libp2p-core/network"
"github.com/libp2p/go-libp2p-core/peer"
"github.com/libp2p/go-libp2p-core/peerstore"
"github.com/multiformats/go-multiaddr"
)
type P2p interface {
Close()
WriteData(rw *bufio.ReadWriter)
ReadData(rw *bufio.ReadWriter)
}
type Whisper struct {
wg sync.WaitGroup
rch chan string
exitCh chan struct{}
}
func New() *Whisper {
whisper := &Whisper{
rch: make(chan string),
exitCh: make(chan struct{}),
}
return whisper
}
func (ws *Whisper) Close() {
close(ws.exitCh)
ws.wg.Wait()
log.Println("Whisper has been closed.")
}
func (ws *Whisper) HandleStream(s network.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))
ws.wg.Add(2)
go ws.ReadData(rw)
go ws.WriteData(rw)
// stream 's' will stay open until you close it (or the other side closes it).
}
func (ws *Whisper) read(rw *bufio.ReadWriter, ch chan string) {
str, _ := rw.ReadString('\n')
ch <- str
}
func (ws *Whisper) ReadData(rw *bufio.ReadWriter) {
defer ws.wg.Done()
log.Println("Read data channel start.")
for {
// TODO
go ws.read(rw, ws.rch)
select {
case <-ws.exitCh:
log.Println("Read data channel exit.")
return
case str := <-ws.rch:
if str == "" {
//return
continue
}
if str != "\n" {
// Green console colour: \x1b[32m
// Reset console colour: \x1b[0m
fmt.Printf("\x1b[32m%s\x1b[0m> ", str)
}
}
}
}
func (ws *Whisper) WriteData(rw *bufio.ReadWriter) {
defer ws.wg.Done()
stdReader := bufio.NewReader(os.Stdin)
log.Println("Write data channel start.")
for {
select {
case <-ws.exitCh:
log.Println("Write data channel exit.")
return
default:
fmt.Print("> ")
sendData, err := stdReader.ReadString('\n')
if err != nil {
log.Println(err)
return
}
rw.WriteString(fmt.Sprintf("%s\n", sendData))
rw.Flush()
}
}
}
func (ws *Whisper) Host(port int, randomness io.Reader) (host.Host, error) {
// Creates a new RSA key pair for this host.
prvKey, _, err := crypto.GenerateKeyPairWithReader(crypto.RSA, 2048, randomness)
if err != nil {
log.Println(err)
return nil, err
}
// 0.0.0.0 will listen on any interface device.
sourceMultiAddr, _ := multiaddr.NewMultiaddr(fmt.Sprintf("/ip4/0.0.0.0/tcp/%d", port))
// libp2p.New constructs a new libp2p Host.
// Other options can be added here.
return libp2p.New(
libp2p.ListenAddrs(sourceMultiAddr),
libp2p.Identity(prvKey),
)
}
func (ws *Whisper) Listen(ctx context.Context, h host.Host, streamHandler network.StreamHandler) {
// Set a function as stream handler.
// This function is called when a peer connects, and starts a stream with this protocol.
// Only applies on the receiving side.
h.SetStreamHandler("/chat/1.0.0", streamHandler)
// Let's get the actual TCP port from our listen multiaddr, in case we're using 0 (default; random available port).
var port string
for _, la := range h.Network().ListenAddresses() {
if p, err := la.ValueForProtocol(multiaddr.P_TCP); err == nil {
port = p
break
}
}
if port == "" {
log.Println("was not able to find actual local port")
return
}
log.Printf("Run './chat -d /ip4/127.0.0.1/tcp/%v/p2p/%s' on another console.\n", port, h.ID().Pretty())
log.Println("You can replace 127.0.0.1 with public IP as well.")
log.Println("Waiting for incoming connection")
log.Println()
}
func (ws *Whisper) Call(ctx context.Context, h host.Host, destination string) (*bufio.ReadWriter, error) {
log.Println("This node's multiaddresses:")
for _, la := range h.Addrs() {
log.Printf(" - %v\n", la)
}
log.Println()
// Turn the destination into a multiaddr.
maddr, err := multiaddr.NewMultiaddr(destination)
if err != nil {
log.Println(err)
return nil, err
}
// Extract the peer ID from the multiaddr.
info, err := peer.AddrInfoFromP2pAddr(maddr)
if err != nil {
log.Println(err)
return nil, err
}
// Add the destination's peer multiaddress in the peerstore.
// This will be used during connection and stream creation by libp2p.
h.Peerstore().AddAddrs(info.ID, info.Addrs, peerstore.PermanentAddrTTL)
// Start a stream with the destination.
// Multiaddress of the destination peer is fetched from the peerstore using 'peerId'.
s, err := h.NewStream(context.Background(), info.ID, "/chat/1.0.0")
if err != nil {
log.Println(err)
return nil, err
}
log.Println("Established connection to destination")
ws.HandleStream(s)
return nil, nil
}