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.

3 files changed, 63 insertions, 5 deletions

diff --git a/node/api.go b/node/api.go
index 570cb9d98..1b04b7093 100644
--- a/node/api.go
+++ b/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
diff --git a/node/config.go b/node/config.go
index b9b5e5b92..be9e21b4f 100644
--- a/node/config.go
+++ b/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
diff --git a/node/node.go b/node/node.go
index 86cfb29ba..6f189d8fe 100644
--- a/node/node.go
+++ b/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.