p2p/simulations: introduce dialBan

* refactor simulations/network connection getters
   to support avoiding simultaneous dials between two peers
   If two peers dial simultaneously, the connection will be dropped
   to help avoid that, we essentially lock the connection object
   with a timestamp which serves as a ban on dialing for
   a period of time (dialBanTimeout).

 * The connection getter InitConn can be wrapped and passed to
   the nodes via adapters.NodeConfig#Reachable field and then
   used by the respective services when they initiate connections.

   This massively stablise the emerging connectivity when running
   with hundreds of nodes bootstrapping a network

 * introduce EnableMsgEvents boolean field in NodeConfig

p2p/simulations/adapters/types.go

@@ -83,6 +83,9 @@ type NodeConfig struct {
 	// stack to encrypt communications
 	PrivateKey *ecdsa.PrivateKey
 
+	// Enable peer events for Msgs
+	EnableMsgEvents bool
+
 	// Name is a human friendly name for the node like "node01"
 	Name string
 
@@ -91,6 +94,9 @@ type NodeConfig struct {
 	// contained in SimAdapter.services, for other nodes it should be
 	// services registered by calling the RegisterService function)
 	Services []string
+
+	// function to sanction or prevent suggesting a peer
+	Reachable func(id discover.NodeID) bool
 }
 
 // nodeConfigJSON is used to encode and decode NodeConfig as JSON by encoding

p2p/simulations/network.go

@@ -22,6 +22,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"sync"
+	"time"
 
 	"github.com/ethereum/go-ethereum/event"
 	"github.com/ethereum/go-ethereum/log"
@@ -30,6 +31,8 @@ import (
 	"github.com/ethereum/go-ethereum/p2p/simulations/adapters"
 )
 
+var dialBanTimeout = 200 * time.Millisecond
+
 // NetworkConfig defines configuration options for starting a Network
 type NetworkConfig struct {
 	ID             string `json:"id"`
@@ -95,6 +98,12 @@ func (self *Network) NewNodeWithConfig(conf *adapters.NodeConfig) (*Node, error)
 		conf.PrivateKey = c.PrivateKey
 	}
 	id := conf.ID
+	if conf.Reachable == nil {
+		conf.Reachable = func(otherID discover.NodeID) bool {
+			_, err := self.InitConn(conf.ID, otherID)
+			return err == nil
+		}
+	}
 
 	// assign a name to the node if not set
 	if conf.Name == "" {
@@ -271,16 +280,10 @@ func (self *Network) Stop(id discover.NodeID) error {
 // method on the "one" node so that it connects to the "other" node
 func (self *Network) Connect(oneID, otherID discover.NodeID) error {
 	log.Debug(fmt.Sprintf("connecting %s to %s", oneID, otherID))
-	conn, err := self.GetOrCreateConn(oneID, otherID)
+	conn, err := self.InitConn(oneID, otherID)
 	if err != nil {
 		return err
 	}
-	if conn.Up {
-		return fmt.Errorf("%v and %v already connected", oneID, otherID)
-	}
-	if err := conn.nodesUp(); err != nil {
-		return err
-	}
 	client, err := conn.one.Client()
 	if err != nil {
 		return err
@@ -324,14 +327,15 @@ func (self *Network) DidConnect(one, other discover.NodeID) error {
 // DidDisconnect tracks the fact that the "one" node disconnected from the
 // "other" node
 func (self *Network) DidDisconnect(one, other discover.NodeID) error {
-	conn, err := self.GetOrCreateConn(one, other)
+	conn := self.GetConn(one, other)
-	if err != nil {
+	if conn == nil {
 		return fmt.Errorf("connection between %v and %v does not exist", one, other)
 	}
 	if !conn.Up {
 		return fmt.Errorf("%v and %v already disconnected", one, other)
 	}
 	conn.Up = false
+	conn.initiated = time.Now().Add(-dialBanTimeout)
 	self.events.Send(NewEvent(conn))
 	return nil
 }
@@ -396,10 +400,13 @@ func (self *Network) getNodeByName(name string) *Node {
 }
 
 // GetNodes returns the existing nodes
-func (self *Network) GetNodes() []*Node {
+func (self *Network) GetNodes() (nodes []*Node) {
 	self.lock.Lock()
 	defer self.lock.Unlock()
-	return self.Nodes
+	for _, node := range self.Nodes {
+		nodes = append(nodes, node)
+	}
+	return nodes
 }
 
 // GetConn returns the connection which exists between "one" and "other"
@@ -415,6 +422,10 @@ func (self *Network) GetConn(oneID, otherID discover.NodeID) *Conn {
 func (self *Network) GetOrCreateConn(oneID, otherID discover.NodeID) (*Conn, error) {
 	self.lock.Lock()
 	defer self.lock.Unlock()
+	return self.getOrCreateConn(oneID, otherID)
+}
+
+func (self *Network) getOrCreateConn(oneID, otherID discover.NodeID) (*Conn, error) {
 	if conn := self.getConn(oneID, otherID); conn != nil {
 		return conn, nil
 	}
@@ -448,6 +459,38 @@ func (self *Network) getConn(oneID, otherID discover.NodeID) *Conn {
 	return self.Conns[i]
 }
 
+// InitConn(one, other) retrieves the connectiton model for the connection between
+// peers one and other, or creates a new one if it does not exist
+// the order of nodes does not matter, i.e., Conn(i,j) == Conn(j, i)
+// it checks if the connection is already up, and if the nodes are running
+// NOTE:
+// it also checks whether there has been recent attempt to connect the peers
+// this is cheating as the simulation is used as an oracle and know about
+// remote peers attempt to connect to a node which will then not initiate the connection
+func (self *Network) InitConn(oneID, otherID discover.NodeID) (*Conn, error) {
+	self.lock.Lock()
+	defer self.lock.Unlock()
+	if oneID == otherID {
+		return nil, fmt.Errorf("refusing to connect to self %v", oneID)
+	}
+	conn, err := self.getOrCreateConn(oneID, otherID)
+	if err != nil {
+		return nil, err
+	}
+	if time.Now().Sub(conn.initiated) < dialBanTimeout {
+		return nil, fmt.Errorf("connection between %v and %v recently attempted", oneID, otherID)
+	}
+	if conn.Up {
+		return nil, fmt.Errorf("%v and %v already connected", oneID, otherID)
+	}
+	err = conn.nodesUp()
+	if err != nil {
+		return nil, fmt.Errorf("nodes not up: %v", err)
+	}
+	conn.initiated = time.Now()
+	return conn, nil
+}
+
 // Shutdown stops all nodes in the network and closes the quit channel
 func (self *Network) Shutdown() {
 	for _, node := range self.Nodes {
@@ -516,6 +559,8 @@ type Conn struct {
 
 	// Up tracks whether or not the connection is active
 	Up bool `json:"up"`
+	// Registers when the connection was grabbed to dial
+	initiated time.Time
 
 	one   *Node
 	other *Node