package p2p
import (
"bytes"
"crypto/ecdsa"
"errors"
"fmt"
"io"
"net"
"runtime"
"sync"
"time"
"github.com/ethereum/go-ethereum/logger"
"github.com/ethereum/go-ethereum/p2p/discover"
"github.com/ethereum/go-ethereum/p2p/nat"
)
const (
handshakeTimeout = 5 * time.Second
defaultDialTimeout = 10 * time.Second
refreshPeersInterval = 30 * time.Second
)
var srvlog = logger.NewLogger("P2P Server")
// MakeName creates a node name that follows the ethereum convention
// for such names. It adds the operation system name and Go runtime version
// the name.
func MakeName(name, version string) string {
return fmt.Sprintf("%s/v%s/%s/%s", name, version, runtime.GOOS, runtime.Version())
}
// Server manages all peer connections.
//
// The fields of Server are used as configuration parameters.
// You should set them before starting the Server. Fields may not be
// modified while the server is running.
type Server struct {
// This field must be set to a valid secp256k1 private key.
PrivateKey *ecdsa.PrivateKey
// MaxPeers is the maximum number of peers that can be
// connected. It must be greater than zero.
MaxPeers int
// Name sets the node name of this server.
// Use MakeName to create a name that follows existing conventions.
Name string
// Bootstrap nodes are used to establish connectivity
// with the rest of the network.
BootstrapNodes []*discover.Node
// Protocols should contain the protocols supported
// by the server. Matching protocols are launched for
// each peer.
Protocols []Protocol
// If Blacklist is set to a non-nil value, the given Blacklist
// is used to verify peer connections.
Blacklist Blacklist
// If ListenAddr is set to a non-nil address, the server
// will listen for incoming connections.
//
// If the port is zero, the operating system will pick a port. The
// ListenAddr field will be updated with the actual address when
// the server is started.
ListenAddr string
// If set to a non-nil value, the given NAT port mapper
// is used to make the listening port available to the
// Internet.
NAT nat.Interface
// If Dialer is set to a non-nil value, the given Dialer
// is used to dial outbound peer connections.
Dialer *net.Dialer
// If NoDial is true, the server will not dial any peers.
NoDial bool
// Hooks for testing. These are useful because we can inhibit
// the whole protocol stack.
handshakeFunc
newPeerHook
lock sync.RWMutex
running bool
listener net.Listener
peers map[discover.NodeID]*Peer
ntab *discover.Table
quit chan struct{}
loopWG sync.WaitGroup // {dial,listen,nat}Loop
peerWG sync.WaitGroup // active peer goroutines
peerConnect chan *discover.Node
}
type handshakeFunc func(io.ReadWriter, *ecdsa.PrivateKey, *discover.Node) (discover.NodeID, []byte, error)
type newPeerHook func(*Peer)
// Peers returns all connected peers.
func (srv *Server) Peers() (peers []*Peer) {
srv.lock.RLock()
defer srv.lock.RUnlock()
for _, peer := range srv.peers {
if peer != nil {
peers = append(peers, peer)
}
}
return
}
// PeerCount returns the number of connected peers.
func (srv *Server) PeerCount() int {
srv.lock.RLock()
n := len(srv.peers)
srv.lock.RUnlock()
return n
}
// SuggestPeer creates a connection to the given Node if it
// is not already connected.
func (srv *Server) SuggestPeer(n *discover.Node) {
srv.peerConnect <- n
}
// Broadcast sends an RLP-encoded message to all connected peers.
// This method is deprecated and will be removed later.
func (srv *Server) Broadcast(protocol string, code uint64, data ...interface{}) {
var payload []byte
if data != nil {
payload = encodePayload(data...)
}
srv.lock.RLock()
defer srv.lock.RUnlock()
for _, peer := range srv.peers {
if peer != nil {
var msg = Msg{Code: code}
if data != nil {
msg.Payload = bytes.NewReader(payload)
msg.Size = uint32(len(payload))
}
peer.writeProtoMsg(protocol, msg)
}
}
}
// Start starts running the server.
// Servers can be re-used and started again after stopping.
func (srv *Server) Start() (err error) {
srv.lock.Lock()
defer srv.lock.Unlock()
if srv.running {
return errors.New("server already running")
}
srvlog.Infoln("Starting Server")
// initialize all the fields
if srv.PrivateKey == nil {
return fmt.Errorf("Server.PrivateKey must be set to a non-nil key")
}
if srv.MaxPeers <= 0 {
return fmt.Errorf("Server.MaxPeers must be > 0")
}
srv.quit = make(chan struct{})
srv.peers = make(map[discover.NodeID]*Peer)
srv.peerConnect = make(chan *discover.Node)
if srv.handshakeFunc == nil {
srv.handshakeFunc = encHandshake
}
if srv.Blacklist == nil {
srv.Blacklist = NewBlacklist()
}
if srv.ListenAddr != "" {
if err := srv.startListening(); err != nil {
return err
}
}
// dial stuff
dt, err := discover.ListenUDP(srv.PrivateKey, srv.ListenAddr, srv.NAT)
if err != nil {
return err
}
srv.ntab = dt
if srv.Dialer == nil {
srv.Dialer = &net.Dialer{Timeout: defaultDialTimeout}
}
if !srv.NoDial {
srv.loopWG.Add(1)
go srv.dialLoop()
}
if srv.NoDial && srv.ListenAddr == "" {
srvlog.Warnln("I will be kind-of useless, neither dialing nor listening.")
}
srv.running = true
return nil
}
func (srv *Server) startListening() error {
listener, err := net.Listen("tcp", srv.ListenAddr)
if err != nil {
return err
}
laddr := listener.Addr().(*net.TCPAddr)
srv.ListenAddr = laddr.String()
srv.listener = listener
srv.loopWG.Add(1)
go srv.listenLoop()
if !laddr.IP.IsLoopback() && srv.NAT != nil {
srv.loopWG.Add(1)
go func() {
nat.Map(srv.NAT, srv.quit, "tcp", laddr.Port, laddr.Port, "ethereum p2p")
srv.loopWG.Done()
}()
}
return nil
}
// Stop terminates the server and all active peer connections.
// It blocks until all active connections have been closed.
func (srv *Server) Stop() {
srv.lock.Lock()
if !srv.running {
srv.lock.Unlock()
return
}
srv.running = false
srv.lock.Unlock()
srvlog.Infoln("Stopping Server")
srv.ntab.Close()
if srv.listener != nil {
// this unblocks listener Accept
srv.listener.Close()
}
close(srv.quit)
srv.loopWG.Wait()
// No new peers can be added at this point because dialLoop and
// listenLoop are down. It is safe to call peerWG.Wait because
// peerWG.Add is not called outside of those loops.
for _, peer := range srv.peers {
peer.Disconnect(DiscQuitting)
}
srv.peerWG.Wait()
}
// main loop for adding connections via listening
func (srv *Server) listenLoop() {
defer srv.loopWG.Done()
srvlog.Infoln("Listening on", srv.listener.Addr())
for {
conn, err := srv.listener.Accept()
if err != nil {
return
}
srvlog.Debugf("Accepted conn %v\n", conn.RemoteAddr())
srv.peerWG.Add(1)
go srv.startPeer(conn, nil)
}
}
func (srv *Server) dialLoop() {
defer srv.loopWG.Done()
refresh := time.NewTicker(refreshPeersInterval)
defer refresh.Stop()
srv.ntab.Bootstrap(srv.BootstrapNodes)
go srv.findPeers()
dialed := make(chan *discover.Node)
dialing := make(map[discover.NodeID]bool)
// TODO: limit number of active dials
// TODO: ensure only one findPeers goroutine is running
// TODO: pause findPeers when we're at capacity
for {
select {
case <-refresh.C:
go srv.findPeers()
case dest := <-srv.peerConnect:
srv.lock.Lock()
_, isconnected := srv.peers[dest.ID]
srv.lock.Unlock()
if isconnected || dialing[dest.ID] {
continue
}
dialing[dest.ID] = true
srv.peerWG.Add(1)
go func() {
srv.dialNode(dest)
// at this point, the peer has been added
// or discarded. either way, we're not dialing it anymore.
dialed <- dest
}()
case dest := <-dialed:
delete(dialing, dest.ID)
case <-srv.quit:
// TODO: maybe wait for active dials
return
}
}
}
func (srv *Server) dialNode(dest *discover.Node) {
addr := &net.TCPAddr{IP: dest.IP, Port: dest.TCPPort}
srvlog.Debugf("Dialing %v\n", dest)
conn, err := srv.Dialer.Dial("tcp", addr.String())
if err != nil {
srvlog.DebugDetailf("dial error: %v", err)
return
}
srv.startPeer(conn, dest)
}
func (srv *Server) findPeers() {
far := srv.ntab.Self()
for i := range far {
far[i] = ^far[i]
}
closeToSelf := srv.ntab.Lookup(srv.ntab.Self())
farFromSelf := srv.ntab.Lookup(far)
for i := 0; i < len(closeToSelf) || i < len(farFromSelf); i++ {
if i < len(closeToSelf) {
srv.peerConnect <- closeToSelf[i]
}
if i < len(farFromSelf) {
srv.peerConnect <- farFromSelf[i]
}
}
}
func (srv *Server) startPeer(conn net.Conn, dest *discover.Node) {
// TODO: handle/store session token
conn.SetDeadline(time.Now().Add(handshakeTimeout))
remoteID, _, err := srv.handshakeFunc(conn, srv.PrivateKey, dest)
if err != nil {
conn.Close()
srvlog.Debugf("Encryption Handshake with %v failed: %v", conn.RemoteAddr(), err)
return
}
ourID := srv.ntab.Self()
p := newPeer(conn, srv.Protocols, srv.Name, &ourID, &remoteID)
if ok, reason := srv.addPeer(remoteID, p); !ok {
srvlog.DebugDetailf("Not adding %v (%v)\n", p, reason)
p.politeDisconnect(reason)
return
}
srvlog.Debugf("Added %v\n", p)
if srv.newPeerHook != nil {
srv.newPeerHook(p)
}
discreason := p.run()
srv.removePeer(p)
srvlog.Debugf("Removed %v (%v)\n", p, discreason)
}
func (srv *Server) addPeer(id discover.NodeID, p *Peer) (bool, DiscReason) {
srv.lock.Lock()
defer srv.lock.Unlock()
switch {
case !srv.running:
return false, DiscQuitting
case len(srv.peers) >= srv.MaxPeers:
return false, DiscTooManyPeers
case srv.peers[id] != nil:
return false, DiscAlreadyConnected
case srv.Blacklist.Exists(id[:]):
return false, DiscUselessPeer
case id == srv.ntab.Self():
return false, DiscSelf
}
srv.peers[id] = p
return true, 0
}
func (srv *Server) removePeer(p *Peer) {
srv.lock.Lock()
delete(srv.peers, *p.remoteID)
srv.lock.Unlock()
srv.peerWG.Done()
}
type Blacklist interface {
Get([]byte) (bool, error)
Put([]byte) error
Delete([]byte) error
Exists(pubkey []byte) (ok bool)
}
type BlacklistMap struct {
blacklist map[string]bool
lock sync.RWMutex
}
func NewBlacklist() *BlacklistMap {
return &BlacklistMap{
blacklist: make(map[string]bool),
}
}
func (self *BlacklistMap) Get(pubkey []byte) (bool, error) {
self.lock.RLock()
defer self.lock.RUnlock()
v, ok := self.blacklist[string(pubkey)]
var err error
if !ok {
err = fmt.Errorf("not found")
}
return v, err
}
func (self *BlacklistMap) Exists(pubkey []byte) (ok bool) {
self.lock.RLock()
defer self.lock.RUnlock()
_, ok = self.blacklist[string(pubkey)]
return
}
func (self *BlacklistMap) Put(pubkey []byte) error {
self.lock.RLock()
defer self.lock.RUnlock()
self.blacklist[string(pubkey)] = true
return nil
}
func (self *BlacklistMap) Delete(pubkey []byte) error {
self.lock.RLock()
defer self.lock.RUnlock()
delete(self.blacklist, string(pubkey))
return nil
}
