diff options
Diffstat (limited to 'p2p/server.go')
| -rw-r--r-- | p2p/server.go | 176 |
1 files changed, 108 insertions, 68 deletions
diff --git a/p2p/server.go b/p2p/server.go index 0a2621aa8..5cd3dc2ad 100644 --- a/p2p/server.go +++ b/p2p/server.go @@ -3,6 +3,7 @@ package p2p import ( "bytes" "crypto/ecdsa" + "crypto/rand" "errors" "fmt" "net" @@ -20,6 +21,11 @@ const ( defaultDialTimeout = 10 * time.Second refreshPeersInterval = 30 * 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 @@ -85,12 +91,12 @@ type Server struct { ourHandshake *protoHandshake - lock sync.RWMutex - running bool - listener net.Listener - peers map[discover.NodeID]*Peer + lock sync.RWMutex // protects running and peers + running bool + peers map[discover.NodeID]*Peer - ntab *discover.Table + ntab *discover.Table + listener net.Listener quit chan struct{} loopWG sync.WaitGroup // {dial,listen,nat}Loop @@ -98,7 +104,7 @@ type Server struct { peerConnect chan *discover.Node } -type setupFunc func(net.Conn, *ecdsa.PrivateKey, *protoHandshake, *discover.Node) (*conn, error) +type setupFunc func(net.Conn, *ecdsa.PrivateKey, *protoHandshake, *discover.Node, bool) (*conn, error) type newPeerHook func(*Peer) // Peers returns all connected peers. @@ -260,62 +266,94 @@ func (srv *Server) Stop() { srv.peerWG.Wait() } +// Self returns the local node's endpoint information. +func (srv *Server) Self() *discover.Node { + 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 srv.startPeer(conn, nil) + go func() { + srv.startPeer(conn, nil) + slots <- struct{}{} + }() } } 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() - 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: 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 + } - // TODO: limit number of active dials - // TODO: ensure only one findPeers goroutine is running - // TODO: pause findPeers when we're at capacity + 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: - - go srv.findPeers() + // 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) + }() + refresh.Stop() + } case dest := <-srv.peerConnect: - // avoid dialing nodes that are already connected. - // there is another check for this in addPeer, - // which runs after the handshake. - srv.lock.Lock() - _, isconnected := srv.peers[dest.ID] - srv.lock.Unlock() - if isconnected || dialing[dest.ID] || dest.ID == srv.Self().ID { - continue + dial(dest) + case dests := <-findresults: + for _, dest := range dests { + dial(dest) } - - 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 - }() - + refresh.Reset(refreshPeersInterval) case dest := <-dialed: delete(dialing, dest.ID) @@ -331,44 +369,34 @@ func (srv *Server) dialNode(dest *discover.Node) { 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) Self() *discover.Node { - return srv.ntab.Self() -} - -func (srv *Server) findPeers() { - far := srv.Self().ID - for i := range far { - far[i] = ^far[i] - } - closeToSelf := srv.ntab.Lookup(srv.Self().ID) - 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(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)) - conn, err := srv.setupFunc(fd, srv.PrivateKey, srv.ourHandshake, dest) + srv.lock.RLock() + atcap := len(srv.peers) == srv.MaxPeers + srv.lock.RUnlock() + conn, err := srv.setupFunc(fd, srv.PrivateKey, srv.ourHandshake, dest, atcap) 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, @@ -377,26 +405,30 @@ func (srv *Server) startPeer(fd net.Conn, dest *discover.Node) { 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: fmt.Sprintf("%x", conn.ID[:]), - RemoteAddress: fd.RemoteAddr().String(), - RemoteVersionString: conn.Name, + 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: fmt.Sprintf("%x", conn.ID[:]), + RemoteId: p.ID().String(), NumConnections: srv.PeerCount(), }) } @@ -404,6 +436,14 @@ func (srv *Server) startPeer(fd net.Conn, dest *discover.Node) { 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 +} + +func (srv *Server) checkPeer(id discover.NodeID) (bool, DiscReason) { switch { case !srv.running: return false, DiscQuitting @@ -413,9 +453,9 @@ func (srv *Server) addPeer(id discover.NodeID, p *Peer) (bool, DiscReason) { return false, DiscAlreadyConnected case id == srv.Self().ID: return false, DiscSelf + default: + return true, 0 } - srv.peers[id] = p - return true, 0 } func (srv *Server) removePeer(p *Peer) { |