rpc: remove 'exported or builtin' restriction for parameters (#20332)

* rpc: remove 'exported or builtin' restriction for parameters

There is no technial reason for this restriction because package reflect
can create values of any type. Requiring parameters and return values to
be exported causes a lot of noise in package exports.

* rpc: fix staticcheck warnings

rpc/client_test.go

@@ -40,11 +40,11 @@ func TestClientRequest(t *testing.T) {
 	client := DialInProc(server)
 	defer client.Close()
 
-	var resp Result
-	if err := client.Call(&resp, "test_echo", "hello", 10, &Args{"world"}); err != nil {
+	var resp echoResult
+	if err := client.Call(&resp, "test_echo", "hello", 10, &echoArgs{"world"}); err != nil {
 		t.Fatal(err)
 	}
-	if !reflect.DeepEqual(resp, Result{"hello", 10, &Args{"world"}}) {
+	if !reflect.DeepEqual(resp, echoResult{"hello", 10, &echoArgs{"world"}}) {
 		t.Errorf("incorrect result %#v", resp)
 	}
 }
@@ -58,13 +58,13 @@ func TestClientBatchRequest(t *testing.T) {
 	batch := []BatchElem{
 		{
 			Method: "test_echo",
-			Args:   []interface{}{"hello", 10, &Args{"world"}},
-			Result: new(Result),
+			Args:   []interface{}{"hello", 10, &echoArgs{"world"}},
+			Result: new(echoResult),
 		},
 		{
 			Method: "test_echo",
-			Args:   []interface{}{"hello2", 11, &Args{"world"}},
-			Result: new(Result),
+			Args:   []interface{}{"hello2", 11, &echoArgs{"world"}},
+			Result: new(echoResult),
 		},
 		{
 			Method: "no_such_method",
@@ -78,13 +78,13 @@ func TestClientBatchRequest(t *testing.T) {
 	wantResult := []BatchElem{
 		{
 			Method: "test_echo",
-			Args:   []interface{}{"hello", 10, &Args{"world"}},
-			Result: &Result{"hello", 10, &Args{"world"}},
+			Args:   []interface{}{"hello", 10, &echoArgs{"world"}},
+			Result: &echoResult{"hello", 10, &echoArgs{"world"}},
 		},
 		{
 			Method: "test_echo",
-			Args:   []interface{}{"hello2", 11, &Args{"world"}},
-			Result: &Result{"hello2", 11, &Args{"world"}},
+			Args:   []interface{}{"hello2", 11, &echoArgs{"world"}},
+			Result: &echoResult{"hello2", 11, &echoArgs{"world"}},
 		},
 		{
 			Method: "no_such_method",
@@ -104,7 +104,7 @@ func TestClientNotify(t *testing.T) {
 	client := DialInProc(server)
 	defer client.Close()
 
-	if err := client.Notify(context.Background(), "test_echo", "hello", 10, &Args{"world"}); err != nil {
+	if err := client.Notify(context.Background(), "test_echo", "hello", 10, &echoArgs{"world"}); err != nil {
 		t.Fatal(err)
 	}
 }
@@ -393,9 +393,9 @@ func TestClientHTTP(t *testing.T) {
 
 	// Launch concurrent requests.
 	var (
-		results    = make([]Result, 100)
+		results    = make([]echoResult, 100)
 		errc       = make(chan error)
-		wantResult = Result{"a", 1, new(Args)}
+		wantResult = echoResult{"a", 1, new(echoArgs)}
 	)
 	defer client.Close()
 	for i := range results {
@@ -450,7 +450,7 @@ func TestClientReconnect(t *testing.T) {
 	}
 
 	// Perform a call. This should work because the server is up.
-	var resp Result
+	var resp echoResult
 	if err := client.CallContext(ctx, &resp, "test_echo", "", 1, nil); err != nil {
 		t.Fatal(err)
 	}
@@ -478,7 +478,7 @@ func TestClientReconnect(t *testing.T) {
 	for i := 0; i < cap(errors); i++ {
 		go func() {
 			<-start
-			var resp Result
+			var resp echoResult
 			errors <- client.CallContext(ctx, &resp, "test_echo", "", 3, nil)
 		}()
 	}

rpc/doc.go

@@ -29,8 +29,6 @@ Methods that satisfy the following criteria are made available for remote access
 
  - method must be exported
  - method returns 0, 1 (response or error) or 2 (response and error) values
- - method argument(s) must be exported or builtin types
- - method returned value(s) must be exported or builtin types
 
 An example method:
 
@@ -74,13 +72,8 @@ An example server which uses the JSON codec:
  calculator := new(CalculatorService)
  server := NewServer()
  server.RegisterName("calculator", calculator)
-
  l, _ := net.ListenUnix("unix", &net.UnixAddr{Net: "unix", Name: "/tmp/calculator.sock"})
- for {
-	c, _ := l.AcceptUnix()
-	codec := v2.NewJSONCodec(c)
-	go server.ServeCodec(codec, 0)
- }
+ server.ServeListener(l)
 
 Subscriptions
 
@@ -90,7 +83,6 @@ criteria:
 
  - method must be exported
  - first method argument type must be context.Context
- - method argument(s) must be exported or builtin types
  - method must have return types (rpc.Subscription, error)
 
 An example method:

rpc/handler.go

@@ -189,7 +189,7 @@ func (h *handler) cancelAllRequests(err error, inflightReq *requestOp) {
 	}
 	for id, sub := range h.clientSubs {
 		delete(h.clientSubs, id)
-		sub.quitWithError(err, false)
+		sub.quitWithError(false, err)
 	}
 }
 

rpc/json.go

@@ -153,14 +153,6 @@ type ConnRemoteAddr interface {
 	RemoteAddr() string
 }
 
-// connWithRemoteAddr overrides the remote address of a connection.
-type connWithRemoteAddr struct {
-	Conn
-	addr string
-}
-
-func (c connWithRemoteAddr) RemoteAddr() string { return c.addr }
-
 // jsonCodec reads and writes JSON-RPC messages to the underlying connection. It also has
 // support for parsing arguments and serializing (result) objects.
 type jsonCodec struct {

rpc/service.go

@@ -25,7 +25,6 @@ import (
 	"strings"
 	"sync"
 	"unicode"
-	"unicode/utf8"
 
 	"github.com/ethereum/go-ethereum/log"
 )
@@ -139,16 +138,14 @@ func newCallback(receiver, fn reflect.Value) *callback {
 	c := &callback{fn: fn, rcvr: receiver, errPos: -1, isSubscribe: isPubSub(fntype)}
 	// Determine parameter types. They must all be exported or builtin types.
 	c.makeArgTypes()
-	if !allExportedOrBuiltin(c.argTypes) {
-		return nil
-	}
+
 	// Verify return types. The function must return at most one error
 	// and/or one other non-error value.
 	outs := make([]reflect.Type, fntype.NumOut())
 	for i := 0; i < fntype.NumOut(); i++ {
 		outs[i] = fntype.Out(i)
 	}
-	if len(outs) > 2 || !allExportedOrBuiltin(outs) {
+	if len(outs) > 2 {
 		return nil
 	}
 	// If an error is returned, it must be the last returned value.
@@ -218,27 +215,6 @@ func (c *callback) call(ctx context.Context, method string, args []reflect.Value
 	return results[0].Interface(), nil
 }
 
-// Is this an exported - upper case - name?
-func isExported(name string) bool {
-	rune, _ := utf8.DecodeRuneInString(name)
-	return unicode.IsUpper(rune)
-}
-
-// Are all those types exported or built-in?
-func allExportedOrBuiltin(types []reflect.Type) bool {
-	for _, typ := range types {
-		for typ.Kind() == reflect.Ptr {
-			typ = typ.Elem()
-		}
-		// PkgPath will be non-empty even for an exported type,
-		// so we need to check the type name as well.
-		if !isExported(typ.Name()) && typ.PkgPath() != "" {
-			return false
-		}
-	}
-	return true
-}
-
 // Is t context.Context or *context.Context?
 func isContextType(t reflect.Type) bool {
 	for t.Kind() == reflect.Ptr {

rpc/subscription.go

@@ -241,11 +241,11 @@ func (sub *ClientSubscription) Err() <-chan error {
 // Unsubscribe unsubscribes the notification and closes the error channel.
 // It can safely be called more than once.
 func (sub *ClientSubscription) Unsubscribe() {
-	sub.quitWithError(nil, true)
+	sub.quitWithError(true, nil)
 	sub.errOnce.Do(func() { close(sub.err) })
 }
 
-func (sub *ClientSubscription) quitWithError(err error, unsubscribeServer bool) {
+func (sub *ClientSubscription) quitWithError(unsubscribeServer bool, err error) {
 	sub.quitOnce.Do(func() {
 		// The dispatch loop won't be able to execute the unsubscribe call
 		// if it is blocked on deliver. Close sub.quit first because it
@@ -276,7 +276,7 @@ func (sub *ClientSubscription) start() {
 	sub.quitWithError(sub.forward())
 }
 
-func (sub *ClientSubscription) forward() (err error, unsubscribeServer bool) {
+func (sub *ClientSubscription) forward() (unsubscribeServer bool, err error) {
 	cases := []reflect.SelectCase{
 		{Dir: reflect.SelectRecv, Chan: reflect.ValueOf(sub.quit)},
 		{Dir: reflect.SelectRecv, Chan: reflect.ValueOf(sub.in)},
@@ -298,14 +298,14 @@ func (sub *ClientSubscription) forward() (err error, unsubscribeServer bool) {
 
 		switch chosen {
 		case 0: // <-sub.quit
-			return nil, false
+			return false, nil
 		case 1: // <-sub.in
 			val, err := sub.unmarshal(recv.Interface().(json.RawMessage))
 			if err != nil {
-				return err, true
+				return true, err
 			}
 			if buffer.Len() == maxClientSubscriptionBuffer {
-				return ErrSubscriptionQueueOverflow, true
+				return true, ErrSubscriptionQueueOverflow
 			}
 			buffer.PushBack(val)
 		case 2: // sub.channel<-

rpc/testservice_test.go

@@ -53,24 +53,24 @@ func sequentialIDGenerator() func() ID {
 
 type testService struct{}
 
-type Args struct {
+type echoArgs struct {
 	S string
 }
 
-type Result struct {
+type echoResult struct {
 	String string
 	Int    int
-	Args   *Args
+	Args   *echoArgs
 }
 
 func (s *testService) NoArgsRets() {}
 
-func (s *testService) Echo(str string, i int, args *Args) Result {
-	return Result{str, i, args}
+func (s *testService) Echo(str string, i int, args *echoArgs) echoResult {
+	return echoResult{str, i, args}
 }
 
-func (s *testService) EchoWithCtx(ctx context.Context, str string, i int, args *Args) Result {
-	return Result{str, i, args}
+func (s *testService) EchoWithCtx(ctx context.Context, str string, i int, args *echoArgs) echoResult {
+	return echoResult{str, i, args}
 }
 
 func (s *testService) Sleep(ctx context.Context, duration time.Duration) {
@@ -81,6 +81,7 @@ func (s *testService) Rets() (string, error) {
 	return "", nil
 }
 
+//lint:ignore ST1008 returns error first on purpose.
 func (s *testService) InvalidRets1() (error, string) {
 	return nil, ""
 }

rpc/types.go

@@ -97,9 +97,8 @@ func (bn *BlockNumber) UnmarshalJSON(data []byte) error {
 		return err
 	}
 	if blckNum > math.MaxInt64 {
-		return fmt.Errorf("Blocknumber too high")
+		return fmt.Errorf("block number larger than int64")
 	}
-
 	*bn = BlockNumber(blckNum)
 	return nil
 }

rpc/websocket_test.go

@@ -96,7 +96,7 @@ func TestWebsocketLargeCall(t *testing.T) {
 	defer client.Close()
 
 	// This call sends slightly less than the limit and should work.
-	var result Result
+	var result echoResult
 	arg := strings.Repeat("x", maxRequestContentLength-200)
 	if err := client.Call(&result, "test_echo", arg, 1); err != nil {
 		t.Fatalf("valid call didn't work: %v", err)