// Copyright 2016 The go-ethereum Authors // This file is part of the go-ethereum library. // // The go-ethereum library is free software: you can redistribute it and/or modify // it under the terms of the GNU Lesser General Public License as published by // the Free Software Foundation, either version 3 of the License, or // (at your option) any later version. // // The go-ethereum library is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU Lesser General Public License for more details. // // You should have received a copy of the GNU Lesser General Public License // along with the go-ethereum library. If not, see . package rpc import ( "context" "encoding/json" "errors" "fmt" "math/rand" "net" "net/http" "net/http/httptest" "os" "reflect" "runtime" "strings" "sync" "testing" "time" "github.com/davecgh/go-spew/spew" "github.com/ethereum/go-ethereum/log" ) func TestClientRequest(t *testing.T) { server := newTestServer() defer server.Stop() client := DialInProc(server) defer client.Close() var resp echoResult if err := client.Call(&resp, "test_echo", "hello", 10, &echoArgs{"world"}); err != nil { t.Fatal(err) } if !reflect.DeepEqual(resp, echoResult{"hello", 10, &echoArgs{"world"}}) { t.Errorf("incorrect result %#v", resp) } } func TestClientResponseType(t *testing.T) { server := newTestServer() defer server.Stop() client := DialInProc(server) defer client.Close() if err := client.Call(nil, "test_echo", "hello", 10, &echoArgs{"world"}); err != nil { t.Errorf("Passing nil as result should be fine, but got an error: %v", err) } var resultVar echoResult // Note: passing the var, not a ref err := client.Call(resultVar, "test_echo", "hello", 10, &echoArgs{"world"}) if err == nil { t.Error("Passing a var as result should be an error") } } // This test checks calling a method that returns 'null'. func TestClientNullResponse(t *testing.T) { server := newTestServer() defer server.Stop() client := DialInProc(server) defer client.Close() var result json.RawMessage if err := client.Call(&result, "test_null"); err != nil { t.Fatal(err) } if result == nil { t.Fatal("Expected non-nil result") } if !reflect.DeepEqual(result, json.RawMessage("null")) { t.Errorf("Expected null, got %s", result) } } // This test checks that server-returned errors with code and data come out of Client.Call. func TestClientErrorData(t *testing.T) { server := newTestServer() defer server.Stop() client := DialInProc(server) defer client.Close() var resp interface{} err := client.Call(&resp, "test_returnError") if err == nil { t.Fatal("expected error") } // Check code. // The method handler returns an error value which implements the rpc.Error // interface, i.e. it has a custom error code. The server returns this error code. expectedCode := testError{}.ErrorCode() if e, ok := err.(Error); !ok { t.Fatalf("client did not return rpc.Error, got %#v", e) } else if e.ErrorCode() != expectedCode { t.Fatalf("wrong error code %d, want %d", e.ErrorCode(), expectedCode) } // Check data. if e, ok := err.(DataError); !ok { t.Fatalf("client did not return rpc.DataError, got %#v", e) } else if e.ErrorData() != (testError{}.ErrorData()) { t.Fatalf("wrong error data %#v, want %#v", e.ErrorData(), testError{}.ErrorData()) } } func TestClientBatchRequest(t *testing.T) { server := newTestServer() defer server.Stop() client := DialInProc(server) defer client.Close() batch := []BatchElem{ { Method: "test_echo", Args: []interface{}{"hello", 10, &echoArgs{"world"}}, Result: new(echoResult), }, { Method: "test_echo", Args: []interface{}{"hello2", 11, &echoArgs{"world"}}, Result: new(echoResult), }, { Method: "no_such_method", Args: []interface{}{1, 2, 3}, Result: new(int), }, } if err := client.BatchCall(batch); err != nil { t.Fatal(err) } wantResult := []BatchElem{ { Method: "test_echo", Args: []interface{}{"hello", 10, &echoArgs{"world"}}, Result: &echoResult{"hello", 10, &echoArgs{"world"}}, }, { Method: "test_echo", Args: []interface{}{"hello2", 11, &echoArgs{"world"}}, Result: &echoResult{"hello2", 11, &echoArgs{"world"}}, }, { Method: "no_such_method", Args: []interface{}{1, 2, 3}, Result: new(int), Error: &jsonError{Code: -32601, Message: "the method no_such_method does not exist/is not available"}, }, } if !reflect.DeepEqual(batch, wantResult) { t.Errorf("batch results mismatch:\ngot %swant %s", spew.Sdump(batch), spew.Sdump(wantResult)) } } // This checks that, for HTTP connections, the length of batch responses is validated to // match the request exactly. func TestClientBatchRequest_len(t *testing.T) { b, err := json.Marshal([]jsonrpcMessage{ {Version: "2.0", ID: json.RawMessage("1"), Result: json.RawMessage(`"0x1"`)}, {Version: "2.0", ID: json.RawMessage("2"), Result: json.RawMessage(`"0x2"`)}, }) if err != nil { t.Fatal("failed to encode jsonrpc message:", err) } s := httptest.NewServer(http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) { _, err := rw.Write(b) if err != nil { t.Error("failed to write response:", err) } })) t.Cleanup(s.Close) t.Run("too-few", func(t *testing.T) { client, err := Dial(s.URL) if err != nil { t.Fatal("failed to dial test server:", err) } defer client.Close() batch := []BatchElem{ {Method: "foo", Result: new(string)}, {Method: "bar", Result: new(string)}, {Method: "baz", Result: new(string)}, } ctx, cancelFn := context.WithTimeout(context.Background(), time.Second) defer cancelFn() if err := client.BatchCallContext(ctx, batch); err != nil { t.Fatal("error:", err) } for i, elem := range batch[:2] { if elem.Error != nil { t.Errorf("expected no error for batch element %d, got %q", i, elem.Error) } } for i, elem := range batch[2:] { if elem.Error != ErrMissingBatchResponse { t.Errorf("wrong error %q for batch element %d", elem.Error, i+2) } } }) t.Run("too-many", func(t *testing.T) { client, err := Dial(s.URL) if err != nil { t.Fatal("failed to dial test server:", err) } defer client.Close() batch := []BatchElem{ {Method: "foo", Result: new(string)}, } ctx, cancelFn := context.WithTimeout(context.Background(), time.Second) defer cancelFn() if err := client.BatchCallContext(ctx, batch); err != nil { t.Fatal("error:", err) } for i, elem := range batch[:1] { if elem.Error != nil { t.Errorf("expected no error for batch element %d, got %q", i, elem.Error) } } for i, elem := range batch[1:] { if elem.Error != ErrMissingBatchResponse { t.Errorf("wrong error %q for batch element %d", elem.Error, i+2) } } }) } // This checks that the client can handle the case where the server doesn't // respond to all requests in a batch. func TestClientBatchRequestLimit(t *testing.T) { server := newTestServer() defer server.Stop() server.SetBatchLimits(2, 100000) client := DialInProc(server) defer client.Close() batch := []BatchElem{ {Method: "foo"}, {Method: "bar"}, {Method: "baz"}, } err := client.BatchCall(batch) if err != nil { t.Fatal("unexpected error:", err) } // Check that the first response indicates an error with batch size. var err0 Error if !errors.As(batch[0].Error, &err0) { t.Log("error zero:", batch[0].Error) t.Fatalf("batch elem 0 has wrong error type: %T", batch[0].Error) } else { if err0.ErrorCode() != -32600 || err0.Error() != errMsgBatchTooLarge { t.Fatalf("wrong error on batch elem zero: %v", err0) } } // Check that remaining response batch elements are reported as absent. for i, elem := range batch[1:] { if elem.Error != ErrMissingBatchResponse { t.Fatalf("batch elem %d has unexpected error: %v", i+1, elem.Error) } } } func TestClientNotify(t *testing.T) { server := newTestServer() defer server.Stop() client := DialInProc(server) defer client.Close() if err := client.Notify(context.Background(), "test_echo", "hello", 10, &echoArgs{"world"}); err != nil { t.Fatal(err) } } // func TestClientCancelInproc(t *testing.T) { testClientCancel("inproc", t) } func TestClientCancelWebsocket(t *testing.T) { testClientCancel("ws", t) } func TestClientCancelHTTP(t *testing.T) { testClientCancel("http", t) } func TestClientCancelIPC(t *testing.T) { testClientCancel("ipc", t) } // This test checks that requests made through CallContext can be canceled by canceling // the context. func testClientCancel(transport string, t *testing.T) { // These tests take a lot of time, run them all at once. // You probably want to run with -parallel 1 or comment out // the call to t.Parallel if you enable the logging. t.Parallel() server := newTestServer() defer server.Stop() // What we want to achieve is that the context gets canceled // at various stages of request processing. The interesting cases // are: // - cancel during dial // - cancel while performing a HTTP request // - cancel while waiting for a response // // To trigger those, the times are chosen such that connections // are killed within the deadline for every other call (maxKillTimeout // is 2x maxCancelTimeout). // // Once a connection is dead, there is a fair chance it won't connect // successfully because the accept is delayed by 1s. maxContextCancelTimeout := 300 * time.Millisecond fl := &flakeyListener{ maxAcceptDelay: 1 * time.Second, maxKillTimeout: 600 * time.Millisecond, } var client *Client switch transport { case "ws", "http": c, hs := httpTestClient(server, transport, fl) defer hs.Close() client = c case "ipc": c, l := ipcTestClient(server, fl) defer l.Close() client = c default: panic("unknown transport: " + transport) } defer client.Close() // The actual test starts here. var ( wg sync.WaitGroup nreqs = 10 ncallers = 10 ) caller := func(index int) { defer wg.Done() for i := 0; i < nreqs; i++ { var ( ctx context.Context cancel func() timeout = time.Duration(rand.Int63n(int64(maxContextCancelTimeout))) ) if index < ncallers/2 { // For half of the callers, create a context without deadline // and cancel it later. ctx, cancel = context.WithCancel(context.Background()) time.AfterFunc(timeout, cancel) } else { // For the other half, create a context with a deadline instead. This is // different because the context deadline is used to set the socket write // deadline. ctx, cancel = context.WithTimeout(context.Background(), timeout) } // Now perform a call with the context. // The key thing here is that no call will ever complete successfully. err := client.CallContext(ctx, nil, "test_block") switch { case err == nil: _, hasDeadline := ctx.Deadline() t.Errorf("no error for call with %v wait time (deadline: %v)", timeout, hasDeadline) // default: // t.Logf("got expected error with %v wait time: %v", timeout, err) } cancel() } } wg.Add(ncallers) for i := 0; i < ncallers; i++ { go caller(i) } wg.Wait() } func TestClientSubscribeInvalidArg(t *testing.T) { server := newTestServer() defer server.Stop() client := DialInProc(server) defer client.Close() check := func(shouldPanic bool, arg interface{}) { defer func() { err := recover() if shouldPanic && err == nil { t.Errorf("EthSubscribe should've panicked for %#v", arg) } if !shouldPanic && err != nil { t.Errorf("EthSubscribe shouldn't have panicked for %#v", arg) buf := make([]byte, 1024*1024) buf = buf[:runtime.Stack(buf, false)] t.Error(err) t.Error(string(buf)) } }() client.EthSubscribe(context.Background(), arg, "foo_bar") } check(true, nil) check(true, 1) check(true, (chan int)(nil)) check(true, make(<-chan int)) check(false, make(chan int)) check(false, make(chan<- int)) } func TestClientSubscribe(t *testing.T) { server := newTestServer() defer server.Stop() client := DialInProc(server) defer client.Close() nc := make(chan int) count := 10 sub, err := client.Subscribe(context.Background(), "nftest", nc, "someSubscription", count, 0) if err != nil { t.Fatal("can't subscribe:", err) } for i := 0; i < count; i++ { if val := <-nc; val != i { t.Fatalf("value mismatch: got %d, want %d", val, i) } } sub.Unsubscribe() select { case v := <-nc: t.Fatal("received value after unsubscribe:", v) case err := <-sub.Err(): if err != nil { t.Fatalf("Err returned a non-nil error after explicit unsubscribe: %q", err) } case <-time.After(1 * time.Second): t.Fatalf("subscription not closed within 1s after unsubscribe") } } // In this test, the connection drops while Subscribe is waiting for a response. func TestClientSubscribeClose(t *testing.T) { server := newTestServer() service := ¬ificationTestService{ gotHangSubscriptionReq: make(chan struct{}), unblockHangSubscription: make(chan struct{}), } if err := server.RegisterName("nftest2", service); err != nil { t.Fatal(err) } defer server.Stop() client := DialInProc(server) defer client.Close() var ( nc = make(chan int) errc = make(chan error, 1) sub *ClientSubscription err error ) go func() { sub, err = client.Subscribe(context.Background(), "nftest2", nc, "hangSubscription", 999) errc <- err }() <-service.gotHangSubscriptionReq client.Close() service.unblockHangSubscription <- struct{}{} select { case err := <-errc: if err == nil { t.Errorf("Subscribe returned nil error after Close") } if sub != nil { t.Error("Subscribe returned non-nil subscription after Close") } case <-time.After(1 * time.Second): t.Fatalf("Subscribe did not return within 1s after Close") } } // This test reproduces https://github.com/ethereum/go-ethereum/issues/17837 where the // client hangs during shutdown when Unsubscribe races with Client.Close. func TestClientCloseUnsubscribeRace(t *testing.T) { server := newTestServer() defer server.Stop() for i := 0; i < 20; i++ { client := DialInProc(server) nc := make(chan int) sub, err := client.Subscribe(context.Background(), "nftest", nc, "someSubscription", 3, 1) if err != nil { t.Fatal(err) } go client.Close() go sub.Unsubscribe() select { case <-sub.Err(): case <-time.After(5 * time.Second): t.Fatal("subscription not closed within timeout") } } } // unsubscribeBlocker will wait for the quit channel to process an unsubscribe // request. type unsubscribeBlocker struct { ServerCodec quit chan struct{} } func (b *unsubscribeBlocker) readBatch() ([]*jsonrpcMessage, bool, error) { msgs, batch, err := b.ServerCodec.readBatch() for _, msg := range msgs { if msg.isUnsubscribe() { <-b.quit } } return msgs, batch, err } // TestUnsubscribeTimeout verifies that calling the client's Unsubscribe // function will eventually timeout and not block forever in case the serve does // not respond. // It reproducers the issue https://github.com/ethereum/go-ethereum/issues/30156 func TestUnsubscribeTimeout(t *testing.T) { srv := NewServer() srv.RegisterName("nftest", new(notificationTestService)) // Setup middleware to block on unsubscribe. p1, p2 := net.Pipe() blocker := &unsubscribeBlocker{ServerCodec: NewCodec(p1), quit: make(chan struct{})} defer close(blocker.quit) // Serve the middleware. go srv.ServeCodec(blocker, OptionMethodInvocation|OptionSubscriptions) defer srv.Stop() // Create the client on the other end of the pipe. cfg := new(clientConfig) client, _ := newClient(context.Background(), cfg, func(context.Context) (ServerCodec, error) { return NewCodec(p2), nil }) defer client.Close() // Start subscription. sub, err := client.Subscribe(context.Background(), "nftest", make(chan int), "someSubscription", 1, 1) if err != nil { t.Fatalf("failed to subscribe: %v", err) } // Now on a separate thread, attempt to unsubscribe. Since the middleware // won't return, the function will only return if it times out on the request. done := make(chan struct{}) go func() { sub.Unsubscribe() done <- struct{}{} }() // Wait for the timeout. If the expected time for the timeout elapses, the // test is considered failed. select { case <-done: case <-time.After(unsubscribeTimeout + 3*time.Second): t.Fatalf("Unsubscribe did not return within %s", unsubscribeTimeout) } } // unsubscribeRecorder collects the subscription IDs of *_unsubscribe calls. type unsubscribeRecorder struct { ServerCodec unsubscribes map[string]bool } func (r *unsubscribeRecorder) readBatch() ([]*jsonrpcMessage, bool, error) { if r.unsubscribes == nil { r.unsubscribes = make(map[string]bool) } msgs, batch, err := r.ServerCodec.readBatch() for _, msg := range msgs { if msg.isUnsubscribe() { var params []string if err := json.Unmarshal(msg.Params, ¶ms); err != nil { panic("unsubscribe decode error: " + err.Error()) } r.unsubscribes[params[0]] = true } } return msgs, batch, err } // This checks that Client calls the _unsubscribe method on the server when Unsubscribe is // called on a subscription. func TestClientSubscriptionUnsubscribeServer(t *testing.T) { t.Parallel() // Create the server. srv := NewServer() srv.RegisterName("nftest", new(notificationTestService)) p1, p2 := net.Pipe() recorder := &unsubscribeRecorder{ServerCodec: NewCodec(p1)} go srv.ServeCodec(recorder, OptionMethodInvocation|OptionSubscriptions) defer srv.Stop() // Create the client on the other end of the pipe. cfg := new(clientConfig) client, _ := newClient(context.Background(), cfg, func(context.Context) (ServerCodec, error) { return NewCodec(p2), nil }) defer client.Close() // Create the subscription. ch := make(chan int) sub, err := client.Subscribe(context.Background(), "nftest", ch, "someSubscription", 1, 1) if err != nil { t.Fatal(err) } // Unsubscribe and check that unsubscribe was called. sub.Unsubscribe() if !recorder.unsubscribes[sub.subid] { t.Fatal("client did not call unsubscribe method") } if _, open := <-sub.Err(); open { t.Fatal("subscription error channel not closed after unsubscribe") } } // This checks that the subscribed channel can be closed after Unsubscribe. // It is the reproducer for https://github.com/ethereum/go-ethereum/issues/22322 func TestClientSubscriptionChannelClose(t *testing.T) { t.Parallel() var ( srv = NewServer() httpsrv = httptest.NewServer(srv.WebsocketHandler(nil)) wsURL = "ws:" + strings.TrimPrefix(httpsrv.URL, "http:") ) defer srv.Stop() defer httpsrv.Close() srv.RegisterName("nftest", new(notificationTestService)) client, _ := Dial(wsURL) defer client.Close() for i := 0; i < 100; i++ { ch := make(chan int, 100) sub, err := client.Subscribe(context.Background(), "nftest", ch, "someSubscription", 100, 1) if err != nil { t.Fatal(err) } sub.Unsubscribe() close(ch) } } // This test checks that Client doesn't lock up when a single subscriber // doesn't read subscription events. func TestClientNotificationStorm(t *testing.T) { server := newTestServer() defer server.Stop() doTest := func(count int, wantError bool) { client := DialInProc(server) defer client.Close() ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second) defer cancel() // Subscribe on the server. It will start sending many notifications // very quickly. nc := make(chan int) sub, err := client.Subscribe(ctx, "nftest", nc, "someSubscription", count, 0) if err != nil { t.Fatal("can't subscribe:", err) } defer sub.Unsubscribe() // Process each notification, try to run a call in between each of them. for i := 0; i < count; i++ { select { case val := <-nc: if val != i { t.Fatalf("(%d/%d) unexpected value %d", i, count, val) } case err := <-sub.Err(): if wantError && err != ErrSubscriptionQueueOverflow { t.Fatalf("(%d/%d) got error %q, want %q", i, count, err, ErrSubscriptionQueueOverflow) } else if !wantError { t.Fatalf("(%d/%d) got unexpected error %q", i, count, err) } return } var r int err := client.CallContext(ctx, &r, "nftest_echo", i) if err != nil { if !wantError { t.Fatalf("(%d/%d) call error: %v", i, count, err) } return } } if wantError { t.Fatalf("didn't get expected error") } } doTest(8000, false) doTest(24000, true) } func TestClientSetHeader(t *testing.T) { var gotHeader bool srv := newTestServer() httpsrv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { if r.Header.Get("test") == "ok" { gotHeader = true } srv.ServeHTTP(w, r) })) defer httpsrv.Close() defer srv.Stop() client, err := Dial(httpsrv.URL) if err != nil { t.Fatal(err) } defer client.Close() client.SetHeader("test", "ok") if _, err := client.SupportedModules(); err != nil { t.Fatal(err) } if !gotHeader { t.Fatal("client did not set custom header") } // Check that Content-Type can be replaced. client.SetHeader("content-type", "application/x-garbage") _, err = client.SupportedModules() if err == nil { t.Fatal("no error for invalid content-type header") } else if !strings.Contains(err.Error(), "Unsupported Media Type") { t.Fatalf("error is not related to content-type: %q", err) } } func TestClientHTTP(t *testing.T) { server := newTestServer() defer server.Stop() client, hs := httpTestClient(server, "http", nil) defer hs.Close() defer client.Close() // Launch concurrent requests. var ( results = make([]echoResult, 100) errc = make(chan error, len(results)) wantResult = echoResult{"a", 1, new(echoArgs)} ) for i := range results { i := i go func() { errc <- client.Call(&results[i], "test_echo", wantResult.String, wantResult.Int, wantResult.Args) }() } // Wait for all of them to complete. timeout := time.NewTimer(5 * time.Second) defer timeout.Stop() for i := range results { select { case err := <-errc: if err != nil { t.Fatal(err) } case <-timeout.C: t.Fatalf("timeout (got %d/%d) results)", i+1, len(results)) } } // Check results. for i := range results { if !reflect.DeepEqual(results[i], wantResult) { t.Errorf("result %d mismatch: got %#v, want %#v", i, results[i], wantResult) } } } func TestClientReconnect(t *testing.T) { startServer := func(addr string) (*Server, net.Listener) { srv := newTestServer() l, err := net.Listen("tcp", addr) if err != nil { t.Fatal("can't listen:", err) } go http.Serve(l, srv.WebsocketHandler([]string{"*"})) return srv, l } ctx, cancel := context.WithTimeout(context.Background(), 12*time.Second) defer cancel() // Start a server and corresponding client. s1, l1 := startServer("127.0.0.1:0") client, err := DialContext(ctx, "ws://"+l1.Addr().String()) if err != nil { t.Fatal("can't dial", err) } defer client.Close() // Perform a call. This should work because the server is up. var resp echoResult if err := client.CallContext(ctx, &resp, "test_echo", "", 1, nil); err != nil { t.Fatal(err) } // Shut down the server and allow for some cool down time so we can listen on the same // address again. l1.Close() s1.Stop() time.Sleep(2 * time.Second) // Try calling again. It shouldn't work. if err := client.CallContext(ctx, &resp, "test_echo", "", 2, nil); err == nil { t.Error("successful call while the server is down") t.Logf("resp: %#v", resp) } // Start it up again and call again. The connection should be reestablished. // We spawn multiple calls here to check whether this hangs somehow. s2, l2 := startServer(l1.Addr().String()) defer l2.Close() defer s2.Stop() start := make(chan struct{}) errors := make(chan error, 20) for i := 0; i < cap(errors); i++ { go func() { <-start var resp echoResult errors <- client.CallContext(ctx, &resp, "test_echo", "", 3, nil) }() } close(start) errcount := 0 for i := 0; i < cap(errors); i++ { if err = <-errors; err != nil { errcount++ } } t.Logf("%d errors, last error: %v", errcount, err) if errcount > 1 { t.Errorf("expected one error after disconnect, got %d", errcount) } } func httpTestClient(srv *Server, transport string, fl *flakeyListener) (*Client, *httptest.Server) { // Create the HTTP server. var hs *httptest.Server switch transport { case "ws": hs = httptest.NewUnstartedServer(srv.WebsocketHandler([]string{"*"})) case "http": hs = httptest.NewUnstartedServer(srv) default: panic("unknown HTTP transport: " + transport) } // Wrap the listener if required. if fl != nil { fl.Listener = hs.Listener hs.Listener = fl } // Connect the client. hs.Start() client, err := Dial(transport + "://" + hs.Listener.Addr().String()) if err != nil { panic(err) } return client, hs } func ipcTestClient(srv *Server, fl *flakeyListener) (*Client, net.Listener) { // Listen on a random endpoint. endpoint := fmt.Sprintf("go-ethereum-test-ipc-%d-%d", os.Getpid(), rand.Int63()) if runtime.GOOS == "windows" { endpoint = `\\.\pipe\` + endpoint } else { endpoint = os.TempDir() + "/" + endpoint } l, err := ipcListen(endpoint) if err != nil { panic(err) } // Connect the listener to the server. if fl != nil { fl.Listener = l l = fl } go srv.ServeListener(l) // Connect the client. client, err := Dial(endpoint) if err != nil { panic(err) } return client, l } // flakeyListener kills accepted connections after a random timeout. type flakeyListener struct { net.Listener maxKillTimeout time.Duration maxAcceptDelay time.Duration } func (l *flakeyListener) Accept() (net.Conn, error) { delay := time.Duration(rand.Int63n(int64(l.maxAcceptDelay))) time.Sleep(delay) c, err := l.Listener.Accept() if err == nil { timeout := time.Duration(rand.Int63n(int64(l.maxKillTimeout))) time.AfterFunc(timeout, func() { log.Debug(fmt.Sprintf("killing conn %v after %v", c.LocalAddr(), timeout)) c.Close() }) } return c, err }