p2p: add network simulation framework (#14982)

This commit introduces a network simulation framework which
can be used to run simulated networks of devp2p nodes. The
intention is to use this for testing protocols, performing
benchmarks and visualising emergent network behaviour.

node/api.go

@@ -17,6 +17,7 @@
 package node
 
 import (
+	"context"
 	"fmt"
 	"strings"
 	"time"
@@ -25,6 +26,7 @@ import (
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/p2p"
 	"github.com/ethereum/go-ethereum/p2p/discover"
+	"github.com/ethereum/go-ethereum/rpc"
 	"github.com/rcrowley/go-metrics"
 )
 
@@ -73,6 +75,44 @@ func (api *PrivateAdminAPI) RemovePeer(url string) (bool, error) {
 	return true, nil
 }
 
+// PeerEvents creates an RPC subscription which receives peer events from the
+// node's p2p.Server
+func (api *PrivateAdminAPI) PeerEvents(ctx context.Context) (*rpc.Subscription, error) {
+	// Make sure the server is running, fail otherwise
+	server := api.node.Server()
+	if server == nil {
+		return nil, ErrNodeStopped
+	}
+
+	// Create the subscription
+	notifier, supported := rpc.NotifierFromContext(ctx)
+	if !supported {
+		return nil, rpc.ErrNotificationsUnsupported
+	}
+	rpcSub := notifier.CreateSubscription()
+
+	go func() {
+		events := make(chan *p2p.PeerEvent)
+		sub := server.SubscribeEvents(events)
+		defer sub.Unsubscribe()
+
+		for {
+			select {
+			case event := <-events:
+				notifier.Notify(rpcSub.ID, event)
+			case <-sub.Err():
+				return
+			case <-rpcSub.Err():
+				return
+			case <-notifier.Closed():
+				return
+			}
+		}
+	}()
+
+	return rpcSub, nil
+}
+
 // StartRPC starts the HTTP RPC API server.
 func (api *PrivateAdminAPI) StartRPC(host *string, port *int, cors *string, apis *string) (bool, error) {
 	api.node.lock.Lock()
@@ -163,7 +203,7 @@ func (api *PrivateAdminAPI) StartWS(host *string, port *int, allowedOrigins *str
 		}
 	}
 
-	if err := api.node.startWS(fmt.Sprintf("%s:%d", *host, *port), api.node.rpcAPIs, modules, origins); err != nil {
+	if err := api.node.startWS(fmt.Sprintf("%s:%d", *host, *port), api.node.rpcAPIs, modules, origins, api.node.config.WSExposeAll); err != nil {
 		return false, err
 	}
 	return true, nil

node/config.go

@@ -128,6 +128,13 @@ type Config struct {
 	// If the module list is empty, all RPC API endpoints designated public will be
 	// exposed.
 	WSModules []string `toml:",omitempty"`
+
+	// WSExposeAll exposes all API modules via the WebSocket RPC interface rather
+	// than just the public ones.
+	//
+	// *WARNING* Only set this if the node is running in a trusted network, exposing
+	// private APIs to untrusted users is a major security risk.
+	WSExposeAll bool `toml:",omitempty"`
 }
 
 // IPCEndpoint resolves an IPC endpoint based on a configured value, taking into

node/node.go

@@ -261,7 +261,7 @@ func (n *Node) startRPC(services map[reflect.Type]Service) error {
 		n.stopInProc()
 		return err
 	}
-	if err := n.startWS(n.wsEndpoint, apis, n.config.WSModules, n.config.WSOrigins); err != nil {
+	if err := n.startWS(n.wsEndpoint, apis, n.config.WSModules, n.config.WSOrigins, n.config.WSExposeAll); err != nil {
 		n.stopHTTP()
 		n.stopIPC()
 		n.stopInProc()
@@ -412,7 +412,7 @@ func (n *Node) stopHTTP() {
 }
 
 // startWS initializes and starts the websocket RPC endpoint.
-func (n *Node) startWS(endpoint string, apis []rpc.API, modules []string, wsOrigins []string) error {
+func (n *Node) startWS(endpoint string, apis []rpc.API, modules []string, wsOrigins []string, exposeAll bool) error {
 	// Short circuit if the WS endpoint isn't being exposed
 	if endpoint == "" {
 		return nil
@@ -425,7 +425,7 @@ func (n *Node) startWS(endpoint string, apis []rpc.API, modules []string, wsOrig
 	// Register all the APIs exposed by the services
 	handler := rpc.NewServer()
 	for _, api := range apis {
-		if whitelist[api.Namespace] || (len(whitelist) == 0 && api.Public) {
+		if exposeAll || whitelist[api.Namespace] || (len(whitelist) == 0 && api.Public) {
 			if err := handler.RegisterName(api.Namespace, api.Service); err != nil {
 				return err
 			}
@@ -441,7 +441,7 @@ func (n *Node) startWS(endpoint string, apis []rpc.API, modules []string, wsOrig
 		return err
 	}
 	go rpc.NewWSServer(wsOrigins, handler).Serve(listener)
-	log.Info(fmt.Sprintf("WebSocket endpoint opened: ws://%s", endpoint))
+	log.Info(fmt.Sprintf("WebSocket endpoint opened: ws://%s", listener.Addr()))
 
 	// All listeners booted successfully
 	n.wsEndpoint = endpoint
@@ -556,6 +556,17 @@ func (n *Node) Attach() (*rpc.Client, error) {
 	return rpc.DialInProc(n.inprocHandler), nil
 }
 
+// RPCHandler returns the in-process RPC request handler.
+func (n *Node) RPCHandler() (*rpc.Server, error) {
+	n.lock.RLock()
+	defer n.lock.RUnlock()
+
+	if n.inprocHandler == nil {
+		return nil, ErrNodeStopped
+	}
+	return n.inprocHandler, nil
+}
+
 // Server retrieves the currently running P2P network layer. This method is meant
 // only to inspect fields of the currently running server, life cycle management
 // should be left to this Node entity.