package p2p import ( "bytes" "crypto/ecdsa" "crypto/rand" "errors" "fmt" "net" "sync" "time" "github.com/ethereum/go-ethereum/logger" "github.com/ethereum/go-ethereum/logger/glog" "github.com/ethereum/go-ethereum/p2p/discover" "github.com/ethereum/go-ethereum/p2p/nat" "github.com/ethereum/go-ethereum/rlp" ) const ( defaultDialTimeout = 10 * time.Second refreshPeersInterval = 30 * time.Second trustedPeerCheckInterval = 15 * time.Second // This is the maximum number of inbound connection // that are allowed to linger between 'accepted' and // 'added as peer'. maxAcceptConns = 50 // total timeout for encryption handshake and protocol // handshake in both directions. handshakeTimeout = 5 * time.Second // maximum time allowed for reading a complete message. // this is effectively the amount of time a connection can be idle. frameReadTimeout = 1 * time.Minute // maximum amount of time allowed for writing a complete message. frameWriteTimeout = 5 * time.Second ) var srvjslog = logger.NewJsonLogger() // 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 common.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 // Trusted nodes are used as privileged connections which are always accepted // and also always maintained. TrustedNodes []*discover.Node // NodeDatabase is the path to the database containing the previously seen // live nodes in the network. NodeDatabase string // Protocols should contain the protocols supported // by the server. Matching protocols are launched for // each peer. Protocols []Protocol // 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. setupFunc newPeerHook ourHandshake *protoHandshake lock sync.RWMutex // protects running, peers and the trust fields running bool peers map[discover.NodeID]*Peer trusts map[discover.NodeID]*discover.Node // Map of currently trusted remote nodes trustDial chan *discover.Node // Dial request channel reserved for the trusted nodes ntab *discover.Table listener net.Listener quit chan struct{} loopWG sync.WaitGroup // {dial,listen,nat}Loop peerWG sync.WaitGroup // active peer goroutines } type setupFunc func(net.Conn, *ecdsa.PrivateKey, *protoHandshake, *discover.Node, bool, map[discover.NodeID]bool) (*conn, 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 } // AddPeer connects to the given node and maintains the connection until the // server is shut down. If the connection fails for any reason, the server will // attempt to reconnect the peer. func (srv *Server) AddPeer(node *discover.Node) { srv.lock.Lock() defer srv.lock.Unlock() srv.trusts[node.ID] = node } // 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{}) error { return srv.BroadcastLimited(protocol, code, func(i float64) float64 { return i }, data) } // BroadcastsRange an RLP-encoded message to a random set of peers using the limit function to limit the amount // of peers. func (srv *Server) BroadcastLimited(protocol string, code uint64, limit func(float64) float64, data interface{}) error { var payload []byte if data != nil { var err error payload, err = rlp.EncodeToBytes(data) if err != nil { return err } } srv.lock.RLock() defer srv.lock.RUnlock() i, max := 0, int(limit(float64(len(srv.peers)))) for _, peer := range srv.peers { if i >= max { break } 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) i++ } } return nil } // 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") } glog.V(logger.Info).Infoln("Starting Server") // static 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) // Create the current trust map, and the associated dialing channel srv.trusts = make(map[discover.NodeID]*discover.Node) for _, node := range srv.TrustedNodes { srv.trusts[node.ID] = node } srv.trustDial = make(chan *discover.Node) if srv.setupFunc == nil { srv.setupFunc = setupConn } // node table ntab, err := discover.ListenUDP(srv.PrivateKey, srv.ListenAddr, srv.NAT, srv.NodeDatabase) if err != nil { return err } srv.ntab = ntab // handshake srv.ourHandshake = &protoHandshake{Version: baseProtocolVersion, Name: srv.Name, ID: ntab.Self().ID} for _, p := range srv.Protocols { srv.ourHandshake.Caps = append(srv.ourHandshake.Caps, p.cap()) } // listen/dial if srv.ListenAddr != "" { if err := srv.startListening(); err != nil { return err } } 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 == "" { glog.V(logger.Warn).Infoln("I will be kind-of useless, neither dialing nor listening.") } // maintain the trusted peers go srv.trustedNodesLoop() 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() glog.V(logger.Info).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. srv.lock.Lock() for _, peer := range srv.peers { peer.Disconnect(DiscQuitting) } srv.lock.Unlock() srv.peerWG.Wait() } // Self returns the local node's endpoint information. func (srv *Server) Self() *discover.Node { srv.lock.RLock() defer srv.lock.RUnlock() if !srv.running { return &discover.Node{IP: net.ParseIP("0.0.0.0")} } return srv.ntab.Self() } // main loop for adding connections via listening func (srv *Server) listenLoop() { defer srv.loopWG.Done() // This channel acts as a semaphore limiting // active inbound connections that are lingering pre-handshake. // If all slots are taken, no further connections are accepted. slots := make(chan struct{}, maxAcceptConns) for i := 0; i < maxAcceptConns; i++ { slots <- struct{}{} } glog.V(logger.Info).Infoln("Listening on", srv.listener.Addr()) for { <-slots conn, err := srv.listener.Accept() if err != nil { return } glog.V(logger.Debug).Infof("Accepted conn %v\n", conn.RemoteAddr()) srv.peerWG.Add(1) go func() { srv.startPeer(conn, nil) slots <- struct{}{} }() } } // trustedNodesLoop is responsible for periodically checking that trusted // connections are actually live, and requests dialing if not. func (srv *Server) trustedNodesLoop() { tick := time.Tick(trustedPeerCheckInterval) for { select { case <-srv.quit: return case <-tick: // Collect all the non-connected trusted nodes needed := []*discover.Node{} srv.lock.RLock() for id, node := range srv.trusts { if _, ok := srv.peers[id]; !ok { needed = append(needed, node) } } srv.lock.RUnlock() // Try to dial each of them (don't hang if server terminates) for _, node := range needed { glog.V(logger.Debug).Infof("Dialing trusted peer %v", node) select { case srv.trustDial <- node: case <-srv.quit: return } } } } } func (srv *Server) dialLoop() { var ( dialed = make(chan *discover.Node) dialing = make(map[discover.NodeID]bool) findresults = make(chan []*discover.Node) refresh = time.NewTimer(0) ) defer srv.loopWG.Done() defer refresh.Stop() // TODO: maybe limit number of active dials dial := func(dest *discover.Node) { // Don't dial nodes that would fail the checks in addPeer. // This is important because the connection handshake is a lot // of work and we'd rather avoid doing that work for peers // that can't be added. srv.lock.RLock() ok, _ := srv.checkPeer(dest.ID) srv.lock.RUnlock() if !ok || dialing[dest.ID] { return } dialing[dest.ID] = true srv.peerWG.Add(1) go func() { srv.dialNode(dest) dialed <- dest }() } srv.ntab.Bootstrap(srv.BootstrapNodes) for { select { case <-refresh.C: // Grab some nodes to connect to if we're not at capacity. srv.lock.RLock() needpeers := len(srv.peers) < srv.MaxPeers srv.lock.RUnlock() if needpeers { go func() { var target discover.NodeID rand.Read(target[:]) findresults <- srv.ntab.Lookup(target) }() } else { // Make sure we check again if the peer count falls // below MaxPeers. refresh.Reset(refreshPeersInterval) } case dest := <-srv.trustDial: dial(dest) case dests := <-findresults: for _, dest := range dests { dial(dest) } refresh.Reset(refreshPeersInterval) case dest := <-dialed: delete(dialing, dest.ID) if len(dialing) == 0 { // Check again immediately after dialing all current candidates. refresh.Reset(0) } 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} glog.V(logger.Debug).Infof("Dialing %v\n", dest) conn, err := srv.Dialer.Dial("tcp", addr.String()) if err != nil { // dialLoop adds to the wait group counter when launching // dialNode, so we need to count it down again. startPeer also // does that when an error occurs. srv.peerWG.Done() glog.V(logger.Detail).Infof("dial error: %v", err) return } srv.startPeer(conn, dest) } func (srv *Server) startPeer(fd net.Conn, dest *discover.Node) { // TODO: handle/store session token // Run setupFunc, which should create an authenticated connection // and run the capability exchange. Note that any early error // returns during that exchange need to call peerWG.Done because // the callers of startPeer added the peer to the wait group already. fd.SetDeadline(time.Now().Add(handshakeTimeout)) // Check capacity and trust list srv.lock.RLock() atcap := len(srv.peers) == srv.MaxPeers trust := make(map[discover.NodeID]bool) for id, _ := range srv.trusts { trust[id] = true } srv.lock.RUnlock() conn, err := srv.setupFunc(fd, srv.PrivateKey, srv.ourHandshake, dest, atcap, trust) if err != nil { fd.Close() glog.V(logger.Debug).Infof("Handshake with %v failed: %v", fd.RemoteAddr(), err) srv.peerWG.Done() return } conn.MsgReadWriter = &netWrapper{ wrapped: conn.MsgReadWriter, conn: fd, rtimeout: frameReadTimeout, wtimeout: frameWriteTimeout, } p := newPeer(fd, conn, srv.Protocols) if ok, reason := srv.addPeer(conn.ID, p); !ok { glog.V(logger.Detail).Infof("Not adding %v (%v)\n", p, reason) p.politeDisconnect(reason) srv.peerWG.Done() return } // The handshakes are done and it passed all checks. // Spawn the Peer loops. go srv.runPeer(p) } func (srv *Server) runPeer(p *Peer) { glog.V(logger.Debug).Infof("Added %v\n", p) srvjslog.LogJson(&logger.P2PConnected{ RemoteId: p.ID().String(), RemoteAddress: p.RemoteAddr().String(), RemoteVersionString: p.Name(), NumConnections: srv.PeerCount(), }) if srv.newPeerHook != nil { srv.newPeerHook(p) } discreason := p.run() srv.removePeer(p) glog.V(logger.Debug).Infof("Removed %v (%v)\n", p, discreason) srvjslog.LogJson(&logger.P2PDisconnected{ RemoteId: p.ID().String(), NumConnections: srv.PeerCount(), }) } func (srv *Server) addPeer(id discover.NodeID, p *Peer) (bool, DiscReason) { srv.lock.Lock() defer srv.lock.Unlock() if ok, reason := srv.checkPeer(id); !ok { return false, reason } srv.peers[id] = p return true, 0 } // checkPeer verifies whether a peer looks promising and should be allowed/kept // in the pool, or if it's of no use. func (srv *Server) checkPeer(id discover.NodeID) (bool, DiscReason) { // First up, figure out if the peer is trusted _, trusted := srv.trusts[id] // Make sure the peer passes all required checks switch { case !srv.running: return false, DiscQuitting case !trusted && len(srv.peers) >= srv.MaxPeers: return false, DiscTooManyPeers case srv.peers[id] != nil: return false, DiscAlreadyConnected case id == srv.ntab.Self().ID: return false, DiscSelf default: return true, 0 } } func (srv *Server) removePeer(p *Peer) { srv.lock.Lock() delete(srv.peers, p.ID()) srv.lock.Unlock() srv.peerWG.Done() }