Revert "node: remove unused error return from Attach (ethereum#27450)"

This reverts commit 2df602a.

cmd/faucet/faucet.go

@@ -268,7 +268,11 @@ func newFaucet(genesis *core.Genesis, port int, enodes []*enode.Node, network ui
 		}
 	}
 	// Attach to the client and retrieve and interesting metadatas
-	api := stack.Attach()
+	api, err := stack.Attach()
+	if err != nil {
+		stack.Close()
+		return nil, err
+	}
 	client := ethclient.NewClient(api)
 
 	return &faucet{

cmd/geth/consolecmd.go

@@ -75,7 +75,10 @@ func localConsole(ctx *cli.Context) error {
 	defer stack.Close()
 
 	// Attach to the newly started node and create the JavaScript console.
-	client := stack.Attach()
+	client, err := stack.Attach()
+	if err != nil {
+		return fmt.Errorf("failed to attach to the inproc geth: %v", err)
+	}
 	config := console.Config{
 		DataDir: utils.MakeDataDir(ctx),
 		DocRoot: ctx.String(utils.JSpathFlag.Name),

cmd/geth/main.go

@@ -346,7 +346,10 @@ func startNode(ctx *cli.Context, stack *node.Node, backend ethapi.Backend, isCon
 	stack.AccountManager().Subscribe(events)
 
 	// Create a client to interact with local geth node.
-	rpcClient := stack.Attach()
+	rpcClient, err := stack.Attach()
+	if err != nil {
+		utils.Fatalf("Failed to attach to self: %v", err)
+	}
 	ethClient := ethclient.NewClient(rpcClient)
 
 	go func() {

console/console_test.go

@@ -110,7 +110,10 @@ func newTester(t *testing.T, confOverride func(*ethconfig.Config)) *tester {
 	if err = stack.Start(); err != nil {
 		t.Fatalf("failed to start test stack: %v", err)
 	}
-	client := stack.Attach()
+	client, err := stack.Attach()
+	if err != nil {
+		t.Fatalf("failed to attach to node: %v", err)
+	}
 	prompter := &hookedPrompter{scheduler: make(chan string)}
 	printer := new(bytes.Buffer)
 

ethclient/ethclient_test.go

@@ -250,7 +250,7 @@ func generateTestChain() []*types.Block {
 
 func TestEthClient(t *testing.T) {
 	backend, chain := newTestBackend(t)
-	client := backend.Attach()
+	client, _ := backend.Attach()
 	defer backend.Close()
 	defer client.Close()
 

ethclient/gethclient/gethclient_test.go

@@ -94,7 +94,10 @@ func generateTestChain() (*core.Genesis, []*types.Block) {
 
 func TestGethClient(t *testing.T) {
 	backend, _ := newTestBackend(t)
-	client := backend.Attach()
+	client, err := backend.Attach()
+	if err != nil {
+		t.Fatal(err)
+	}
 	defer backend.Close()
 	defer client.Close()
 

node/node.go

@@ -616,8 +616,8 @@ func (n *Node) RegisterHandler(name, path string, handler http.Handler) {
 }
 
 // Attach creates an RPC client attached to an in-process API handler.
-func (n *Node) Attach() *rpc.Client {
-	return rpc.DialInProc(n.inprocHandler)
+func (n *Node) Attach() (*rpc.Client, error) {
+	return rpc.DialInProc(n.inprocHandler), nil
 }
 
 // RPCHandler returns the in-process RPC request handler.

p2p/simulations/adapters/inproc.go

@@ -147,7 +147,7 @@ func (s *SimAdapter) DialRPC(id enode.ID) (*rpc.Client, error) {
 	if !ok {
 		return nil, fmt.Errorf("unknown node: %s", id)
 	}
-	return node.node.Attach(), nil
+	return node.node.Attach()
 }
 
 // GetNode returns the node with the given ID if it exists
@@ -274,7 +274,10 @@ func (sn *SimNode) Start(snapshots map[string][]byte) error {
 	}
 
 	// create an in-process RPC client
-	client := sn.node.Attach()
+	client, err := sn.node.Attach()
+	if err != nil {
+		return err
+	}
 	sn.lock.Lock()
 	sn.client = client
 	sn.lock.Unlock()