[NOD-134] Don't connect to an address from the same 16 CIDR (#423)

* [NOD-134] Don't connect to an address from the same 16 CIDR

* [NOD-134] Rename outboundPeerConnected variables

* [NOD-134] Change newConnMtx to newConnReqMtx

connmgr/connmanager.go

@@ -178,6 +178,8 @@ type ConnManager struct {
 	start        int32
 	stop         int32
 
+	newConnReqMtx sync.Mutex
+
 	cfg            Config
 	wg             sync.WaitGroup
 	failedAttempts uint64
@@ -270,7 +272,7 @@ out:
 				delete(pending, connReq.id)
 
 				if cm.cfg.OnConnection != nil {
-					go cm.cfg.OnConnection(connReq, msg.conn)
+					cm.cfg.OnConnection(connReq, msg.conn)
 				}
 
 			case handleDisconnected:
@@ -359,6 +361,8 @@ out:
 // NewConnReq creates a new connection request and connects to the
 // corresponding address.
 func (cm *ConnManager) NewConnReq() {
+	cm.newConnReqMtx.Lock()
+	defer cm.newConnReqMtx.Unlock()
 	if atomic.LoadInt32(&cm.stop) != 0 {
 		return
 	}

server/p2p/p2p.go

@@ -137,6 +137,11 @@ type relayMsg struct {
 	data    interface{}
 }
 
+type outboundPeerConnectedMsg struct {
+	connReq *connmgr.ConnReq
+	conn    net.Conn
+}
+
 // updatePeerHeightsMsg is a message sent from the blockmanager to the server
 // after a new block has been accepted. The purpose of the message is to update
 // the heights of peers that were known to announce the block before we
@@ -266,6 +271,7 @@ type Server struct {
 	newPeers              chan *Peer
 	donePeers             chan *Peer
 	banPeers              chan *Peer
+	newOutboundConnection chan *outboundPeerConnectedMsg
 	Query                 chan interface{}
 	relayInv              chan relayMsg
 	broadcast             chan broadcastMsg
@@ -695,7 +701,6 @@ func (s *Server) handleAddPeerMsg(state *peerState, sp *Peer) bool {
 	if sp.Inbound() {
 		state.inboundPeers[sp.ID()] = sp
 	} else {
-		state.outboundGroups[addrmgr.GroupKey(sp.NA())]++
 		if sp.persistent {
 			state.persistentPeers[sp.ID()] = sp
 		} else {
@@ -1110,21 +1115,22 @@ func (s *Server) inboundPeerConnected(conn net.Conn) {
 // peer instance, associates it with the relevant state such as the connection
 // request instance and the connection itself, and finally notifies the address
 // manager of the attempt.
-func (s *Server) outboundPeerConnected(c *connmgr.ConnReq, conn net.Conn) {
+func (s *Server) outboundPeerConnected(state *peerState, msg *outboundPeerConnectedMsg) {
-	sp := newServerPeer(s, c.Permanent)
+	sp := newServerPeer(s, msg.connReq.Permanent)
-	p, err := peer.NewOutboundPeer(newPeerConfig(sp), c.Addr.String())
+	outboundPeer, err := peer.NewOutboundPeer(newPeerConfig(sp), msg.connReq.Addr.String())
 	if err != nil {
-		srvrLog.Debugf("Cannot create outbound peer %s: %s", c.Addr, err)
+		srvrLog.Debugf("Cannot create outbound peer %s: %s", msg.connReq.Addr, err)
-		s.connManager.Disconnect(c.ID())
+		s.connManager.Disconnect(msg.connReq.ID())
 	}
-	sp.Peer = p
+	sp.Peer = outboundPeer
-	sp.connReq = c
+	sp.connReq = msg.connReq
-	sp.isWhitelisted = isWhitelisted(conn.RemoteAddr())
+	sp.isWhitelisted = isWhitelisted(msg.conn.RemoteAddr())
-	sp.AssociateConnection(conn)
+	sp.AssociateConnection(msg.conn)
 	spawn(func() {
 		s.peerDoneHandler(sp)
 	})
 	s.addrManager.Attempt(sp.NA())
+	state.outboundGroups[addrmgr.GroupKey(sp.NA())]++
 }
 
 // peerDoneHandler handles peer disconnects by notifiying the server that it's
@@ -1226,6 +1232,9 @@ out:
 				return true
 			})
 			break out
+
+		case opcMsg := <-s.newOutboundConnection:
+			s.outboundPeerConnected(state, opcMsg)
 		}
 	}
 
@@ -1601,6 +1610,7 @@ func NewServer(listenAddrs []string, db database.DB, dagParams *dagconfig.Params
 		broadcast:             make(chan broadcastMsg, config.MainConfig().MaxPeers),
 		quit:                  make(chan struct{}),
 		modifyRebroadcastInv:  make(chan interface{}),
+		newOutboundConnection: make(chan *outboundPeerConnectedMsg),
 		nat:                   nat,
 		db:                    db,
 		TimeSource:            blockdag.NewMedianTime(),
@@ -1757,7 +1767,6 @@ func NewServer(listenAddrs []string, db database.DB, dagParams *dagconfig.Params
 				addrString := addrmgr.NetAddressKey(addr.NetAddress())
 				return addrStringToNetAddr(addrString)
 			}
-
 			return nil, errors.New("no valid connect address")
 		}
 	}
@@ -1773,7 +1782,12 @@ func NewServer(listenAddrs []string, db database.DB, dagParams *dagconfig.Params
 		RetryDuration:  connectionRetryInterval,
 		TargetOutbound: uint32(targetOutbound),
 		Dial:           serverutils.BTCDDial,
-		OnConnection:   s.outboundPeerConnected,
+		OnConnection: func(c *connmgr.ConnReq, conn net.Conn) {
+			s.newOutboundConnection <- &outboundPeerConnectedMsg{
+				connReq: c,
+				conn:    conn,
+			}
+		},
 		GetNewAddress: newAddressFunc,
 	})
 	if err != nil {