rpc: implement full bi-directional communication (#18471)

New APIs added:

    client.RegisterName(namespace, service) // makes service available to server
    client.Notify(ctx, method, args...)     // sends a notification
    ClientFromContext(ctx)                  // to get a client in handler method

This is essentially a rewrite of the server-side code. JSON-RPC
processing code is now the same on both server and client side. Many
minor issues were fixed in the process and there is a new test suite for
JSON-RPC spec compliance (and non-compliance in some cases).

List of behavior changes:

- Method handlers are now called with a per-request context instead of a
  per-connection context. The context is canceled right after the method
  returns.
- Subscription error channels are always closed when the connection
  ends. There is no need to also wait on the Notifier's Closed channel
  to detect whether the subscription has ended.
- Client now omits "params" instead of sending "params": null when there
  are no arguments to a call. The previous behavior was not compliant
  with the spec. The server still accepts "params": null.
- Floating point numbers are allowed as "id". The spec doesn't allow
  them, but we handle request "id" as json.RawMessage and guarantee that
  the same number will be sent back.
- Logging is improved significantly. There is now a message at DEBUG
  level for each RPC call served.

rpc/client.go

@@ -18,17 +18,13 @@ package rpc
 
 import (
 	"bytes"
-	"container/list"
 	"context"
 	"encoding/json"
 	"errors"
 	"fmt"
-	"net"
 	"net/url"
 	"reflect"
 	"strconv"
-	"strings"
-	"sync"
 	"sync/atomic"
 	"time"
 
@@ -39,13 +35,14 @@ var (
 	ErrClientQuit                = errors.New("client is closed")
 	ErrNoResult                  = errors.New("no result in JSON-RPC response")
 	ErrSubscriptionQueueOverflow = errors.New("subscription queue overflow")
+	errClientReconnected         = errors.New("client reconnected")
+	errDead                      = errors.New("connection lost")
 )
 
 const (
 	// Timeouts
 	tcpKeepAliveInterval = 30 * time.Second
-	defaultDialTimeout   = 10 * time.Second // used when dialing if the context has no deadline
-	defaultWriteTimeout  = 10 * time.Second // used for calls if the context has no deadline
+	defaultDialTimeout   = 10 * time.Second // used if context has no deadline
 	subscribeTimeout     = 5 * time.Second  // overall timeout eth_subscribe, rpc_modules calls
 )
 
@@ -76,56 +73,57 @@ type BatchElem struct {
 	Error error
 }
 
-// A value of this type can a JSON-RPC request, notification, successful response or
-// error response. Which one it is depends on the fields.
-type jsonrpcMessage struct {
-	Version string          `json:"jsonrpc"`
-	ID      json.RawMessage `json:"id,omitempty"`
-	Method  string          `json:"method,omitempty"`
-	Params  json.RawMessage `json:"params,omitempty"`
-	Error   *jsonError      `json:"error,omitempty"`
-	Result  json.RawMessage `json:"result,omitempty"`
-}
+// Client represents a connection to an RPC server.
+type Client struct {
+	idgen    func() ID // for subscriptions
+	isHTTP   bool
+	services *serviceRegistry
 
-func (msg *jsonrpcMessage) isNotification() bool {
-	return msg.ID == nil && msg.Method != ""
-}
+	idCounter uint32
 
-func (msg *jsonrpcMessage) isResponse() bool {
-	return msg.hasValidID() && msg.Method == "" && len(msg.Params) == 0
-}
+	// This function, if non-nil, is called when the connection is lost.
+	reconnectFunc reconnectFunc
+
+	// writeConn is used for writing to the connection on the caller's goroutine. It should
+	// only be accessed outside of dispatch, with the write lock held. The write lock is
+	// taken by sending on requestOp and released by sending on sendDone.
+	writeConn jsonWriter
 
-func (msg *jsonrpcMessage) hasValidID() bool {
-	return len(msg.ID) > 0 && msg.ID[0] != '{' && msg.ID[0] != '['
+	// for dispatch
+	close       chan struct{}
+	closing     chan struct{}    // closed when client is quitting
+	didClose    chan struct{}    // closed when client quits
+	reconnected chan ServerCodec // where write/reconnect sends the new connection
+	readOp      chan readOp      // read messages
+	readErr     chan error       // errors from read
+	reqInit     chan *requestOp  // register response IDs, takes write lock
+	reqSent     chan error       // signals write completion, releases write lock
+	reqTimeout  chan *requestOp  // removes response IDs when call timeout expires
 }
 
-func (msg *jsonrpcMessage) String() string {
-	b, _ := json.Marshal(msg)
-	return string(b)
+type reconnectFunc func(ctx context.Context) (ServerCodec, error)
+
+type clientContextKey struct{}
+
+type clientConn struct {
+	codec   ServerCodec
+	handler *handler
 }
 
-// Client represents a connection to an RPC server.
-type Client struct {
-	idCounter   uint32
-	connectFunc func(ctx context.Context) (net.Conn, error)
-	isHTTP      bool
+func (c *Client) newClientConn(conn ServerCodec) *clientConn {
+	ctx := context.WithValue(context.Background(), clientContextKey{}, c)
+	handler := newHandler(ctx, conn, c.idgen, c.services)
+	return &clientConn{conn, handler}
+}
 
-	// writeConn is only safe to access outside dispatch, with the
-	// write lock held. The write lock is taken by sending on
-	// requestOp and released by sending on sendDone.
-	writeConn net.Conn
+func (cc *clientConn) close(err error, inflightReq *requestOp) {
+	cc.handler.close(err, inflightReq)
+	cc.codec.Close()
+}
 
-	// for dispatch
-	close       chan struct{}
-	closing     chan struct{}                  // closed when client is quitting
-	didClose    chan struct{}                  // closed when client quits
-	reconnected chan net.Conn                  // where write/reconnect sends the new connection
-	readErr     chan error                     // errors from read
-	readResp    chan []*jsonrpcMessage         // valid messages from read
-	requestOp   chan *requestOp                // for registering response IDs
-	sendDone    chan error                     // signals write completion, releases write lock
-	respWait    map[string]*requestOp          // active requests
-	subs        map[string]*ClientSubscription // active subscriptions
+type readOp struct {
+	msgs  []*jsonrpcMessage
+	batch bool
 }
 
 type requestOp struct {
@@ -135,9 +133,14 @@ type requestOp struct {
 	sub  *ClientSubscription  // only set for EthSubscribe requests
 }
 
-func (op *requestOp) wait(ctx context.Context) (*jsonrpcMessage, error) {
+func (op *requestOp) wait(ctx context.Context, c *Client) (*jsonrpcMessage, error) {
 	select {
 	case <-ctx.Done():
+		// Send the timeout to dispatch so it can remove the request IDs.
+		select {
+		case c.reqTimeout <- op:
+		case <-c.closing:
+		}
 		return nil, ctx.Err()
 	case resp := <-op.resp:
 		return resp, op.err
@@ -181,36 +184,57 @@ func DialContext(ctx context.Context, rawurl string) (*Client, error) {
 	}
 }
 
-func newClient(initctx context.Context, connectFunc func(context.Context) (net.Conn, error)) (*Client, error) {
-	conn, err := connectFunc(initctx)
+// Client retrieves the client from the context, if any. This can be used to perform
+// 'reverse calls' in a handler method.
+func ClientFromContext(ctx context.Context) (*Client, bool) {
+	client, ok := ctx.Value(clientContextKey{}).(*Client)
+	return client, ok
+}
+
+func newClient(initctx context.Context, connect reconnectFunc) (*Client, error) {
+	conn, err := connect(initctx)
 	if err != nil {
 		return nil, err
 	}
+	c := initClient(conn, randomIDGenerator(), new(serviceRegistry))
+	c.reconnectFunc = connect
+	return c, nil
+}
+
+func initClient(conn ServerCodec, idgen func() ID, services *serviceRegistry) *Client {
 	_, isHTTP := conn.(*httpConn)
 	c := &Client{
-		writeConn:   conn,
+		idgen:       idgen,
 		isHTTP:      isHTTP,
-		connectFunc: connectFunc,
+		services:    services,
+		writeConn:   conn,
 		close:       make(chan struct{}),
 		closing:     make(chan struct{}),
 		didClose:    make(chan struct{}),
-		reconnected: make(chan net.Conn),
+		reconnected: make(chan ServerCodec),
+		readOp:      make(chan readOp),
 		readErr:     make(chan error),
-		readResp:    make(chan []*jsonrpcMessage),
-		requestOp:   make(chan *requestOp),
-		sendDone:    make(chan error, 1),
-		respWait:    make(map[string]*requestOp),
-		subs:        make(map[string]*ClientSubscription),
+		reqInit:     make(chan *requestOp),
+		reqSent:     make(chan error, 1),
+		reqTimeout:  make(chan *requestOp),
 	}
 	if !isHTTP {
 		go c.dispatch(conn)
 	}
-	return c, nil
+	return c
+}
+
+// RegisterName creates a service for the given receiver type under the given name. When no
+// methods on the given receiver match the criteria to be either a RPC method or a
+// subscription an error is returned. Otherwise a new service is created and added to the
+// service collection this client provides to the server.
+func (c *Client) RegisterName(name string, receiver interface{}) error {
+	return c.services.registerName(name, receiver)
 }
 
 func (c *Client) nextID() json.RawMessage {
 	id := atomic.AddUint32(&c.idCounter, 1)
-	return []byte(strconv.FormatUint(uint64(id), 10))
+	return strconv.AppendUint(nil, uint64(id), 10)
 }
 
 // SupportedModules calls the rpc_modules method, retrieving the list of
@@ -267,7 +291,7 @@ func (c *Client) CallContext(ctx context.Context, result interface{}, method str
 	}
 
 	// dispatch has accepted the request and will close the channel when it quits.
-	switch resp, err := op.wait(ctx); {
+	switch resp, err := op.wait(ctx, c); {
 	case err != nil:
 		return err
 	case resp.Error != nil:
@@ -325,7 +349,7 @@ func (c *Client) BatchCallContext(ctx context.Context, b []BatchElem) error {
 	// Wait for all responses to come back.
 	for n := 0; n < len(b) && err == nil; n++ {
 		var resp *jsonrpcMessage
-		resp, err = op.wait(ctx)
+		resp, err = op.wait(ctx, c)
 		if err != nil {
 			break
 		}
@@ -352,6 +376,22 @@ func (c *Client) BatchCallContext(ctx context.Context, b []BatchElem) error {
 	return err
 }
 
+// Notify sends a notification, i.e. a method call that doesn't expect a response.
+func (c *Client) Notify(ctx context.Context, method string, args ...interface{}) error {
+	op := new(requestOp)
+	msg, err := c.newMessage(method, args...)
+	if err != nil {
+		return err
+	}
+	msg.ID = nil
+
+	if c.isHTTP {
+		return c.sendHTTP(ctx, op, msg)
+	} else {
+		return c.send(ctx, op, msg)
+	}
+}
+
 // EthSubscribe registers a subscripion under the "eth" namespace.
 func (c *Client) EthSubscribe(ctx context.Context, channel interface{}, args ...interface{}) (*ClientSubscription, error) {
 	return c.Subscribe(ctx, "eth", channel, args...)
@@ -402,30 +442,30 @@ func (c *Client) Subscribe(ctx context.Context, namespace string, channel interf
 	if err := c.send(ctx, op, msg); err != nil {
 		return nil, err
 	}
-	if _, err := op.wait(ctx); err != nil {
+	if _, err := op.wait(ctx, c); err != nil {
 		return nil, err
 	}
 	return op.sub, nil
 }
 
 func (c *Client) newMessage(method string, paramsIn ...interface{}) (*jsonrpcMessage, error) {
-	params, err := json.Marshal(paramsIn)
-	if err != nil {
-		return nil, err
+	msg := &jsonrpcMessage{Version: vsn, ID: c.nextID(), Method: method}
+	if paramsIn != nil { // prevent sending "params":null
+		var err error
+		if msg.Params, err = json.Marshal(paramsIn); err != nil {
+			return nil, err
+		}
 	}
-	return &jsonrpcMessage{Version: "2.0", ID: c.nextID(), Method: method, Params: params}, nil
+	return msg, nil
 }
 
 // send registers op with the dispatch loop, then sends msg on the connection.
 // if sending fails, op is deregistered.
 func (c *Client) send(ctx context.Context, op *requestOp, msg interface{}) error {
 	select {
-	case c.requestOp <- op:
-		log.Trace("", "msg", log.Lazy{Fn: func() string {
-			return fmt.Sprint("sending ", msg)
-		}})
+	case c.reqInit <- op:
 		err := c.write(ctx, msg)
-		c.sendDone <- err
+		c.reqSent <- err
 		return err
 	case <-ctx.Done():
 		// This can happen if the client is overloaded or unable to keep up with
@@ -433,25 +473,17 @@ func (c *Client) send(ctx context.Context, op *requestOp, msg interface{}) error
 		return ctx.Err()
 	case <-c.closing:
 		return ErrClientQuit
-	case <-c.didClose:
-		return ErrClientQuit
 	}
 }
 
 func (c *Client) write(ctx context.Context, msg interface{}) error {
-	deadline, ok := ctx.Deadline()
-	if !ok {
-		deadline = time.Now().Add(defaultWriteTimeout)
-	}
 	// The previous write failed. Try to establish a new connection.
 	if c.writeConn == nil {
 		if err := c.reconnect(ctx); err != nil {
 			return err
 		}
 	}
-	c.writeConn.SetWriteDeadline(deadline)
-	err := json.NewEncoder(c.writeConn).Encode(msg)
-	c.writeConn.SetWriteDeadline(time.Time{})
+	err := c.writeConn.Write(ctx, msg)
 	if err != nil {
 		c.writeConn = nil
 	}
@@ -459,9 +491,18 @@ func (c *Client) write(ctx context.Context, msg interface{}) error {
 }
 
 func (c *Client) reconnect(ctx context.Context) error {
-	newconn, err := c.connectFunc(ctx)
+	if c.reconnectFunc == nil {
+		return errDead
+	}
+
+	if _, ok := ctx.Deadline(); !ok {
+		var cancel func()
+		ctx, cancel = context.WithTimeout(ctx, defaultDialTimeout)
+		defer cancel()
+	}
+	newconn, err := c.reconnectFunc(ctx)
 	if err != nil {
-		log.Trace(fmt.Sprintf("reconnect failed: %v", err))
+		log.Trace("RPC client reconnect failed", "err", err)
 		return err
 	}
 	select {
@@ -477,322 +518,107 @@ func (c *Client) reconnect(ctx context.Context) error {
 // dispatch is the main loop of the client.
 // It sends read messages to waiting calls to Call and BatchCall
 // and subscription notifications to registered subscriptions.
-func (c *Client) dispatch(conn net.Conn) {
-	// Spawn the initial read loop.
-	go c.read(conn)
-
+func (c *Client) dispatch(codec ServerCodec) {
 	var (
-		lastOp        *requestOp    // tracks last send operation
-		requestOpLock = c.requestOp // nil while the send lock is held
-		reading       = true        // if true, a read loop is running
+		lastOp      *requestOp  // tracks last send operation
+		reqInitLock = c.reqInit // nil while the send lock is held
+		conn        = c.newClientConn(codec)
+		reading     = true
 	)
-	defer close(c.didClose)
 	defer func() {
 		close(c.closing)
-		c.closeRequestOps(ErrClientQuit)
-		conn.Close()
 		if reading {
-			// Empty read channels until read is dead.
-			for {
-				select {
-				case <-c.readResp:
-				case <-c.readErr:
-					return
-				}
-			}
+			conn.close(ErrClientQuit, nil)
+			c.drainRead()
 		}
+		close(c.didClose)
 	}()
 
+	// Spawn the initial read loop.
+	go c.read(codec)
+
 	for {
 		select {
 		case <-c.close:
 			return
 
-		// Read path.
-		case batch := <-c.readResp:
-			for _, msg := range batch {
-				switch {
-				case msg.isNotification():
-					log.Trace("", "msg", log.Lazy{Fn: func() string {
-						return fmt.Sprint("<-readResp: notification ", msg)
-					}})
-					c.handleNotification(msg)
-				case msg.isResponse():
-					log.Trace("", "msg", log.Lazy{Fn: func() string {
-						return fmt.Sprint("<-readResp: response ", msg)
-					}})
-					c.handleResponse(msg)
-				default:
-					log.Debug("", "msg", log.Lazy{Fn: func() string {
-						return fmt.Sprint("<-readResp: dropping weird message", msg)
-					}})
-					// TODO: maybe close
-				}
+		// Read path:
+		case op := <-c.readOp:
+			if op.batch {
+				conn.handler.handleBatch(op.msgs)
+			} else {
+				conn.handler.handleMsg(op.msgs[0])
 			}
 
 		case err := <-c.readErr:
-			log.Debug("<-readErr", "err", err)
-			c.closeRequestOps(err)
-			conn.Close()
+			conn.handler.log.Debug("RPC connection read error", "err", err)
+			conn.close(err, lastOp)
 			reading = false
 
-		case newconn := <-c.reconnected:
-			log.Debug("<-reconnected", "reading", reading, "remote", conn.RemoteAddr())
+		// Reconnect:
+		case newcodec := <-c.reconnected:
+			log.Debug("RPC client reconnected", "reading", reading, "conn", newcodec.RemoteAddr())
 			if reading {
-				// Wait for the previous read loop to exit. This is a rare case.
-				conn.Close()
-				<-c.readErr
+				// Wait for the previous read loop to exit. This is a rare case which
+				// happens if this loop isn't notified in time after the connection breaks.
+				// In those cases the caller will notice first and reconnect. Closing the
+				// handler terminates all waiting requests (closing op.resp) except for
+				// lastOp, which will be transferred to the new handler.
+				conn.close(errClientReconnected, lastOp)
+				c.drainRead()
 			}
-			go c.read(newconn)
+			go c.read(newcodec)
 			reading = true
-			conn = newconn
-
-		// Send path.
-		case op := <-requestOpLock:
-			// Stop listening for further send ops until the current one is done.
-			requestOpLock = nil
+			conn = c.newClientConn(newcodec)
+			// Re-register the in-flight request on the new handler
+			// because that's where it will be sent.
+			conn.handler.addRequestOp(lastOp)
+
+		// Send path:
+		case op := <-reqInitLock:
+			// Stop listening for further requests until the current one has been sent.
+			reqInitLock = nil
 			lastOp = op
-			for _, id := range op.ids {
-				c.respWait[string(id)] = op
-			}
+			conn.handler.addRequestOp(op)
 
-		case err := <-c.sendDone:
+		case err := <-c.reqSent:
 			if err != nil {
-				// Remove response handlers for the last send. We remove those here
-				// because the error is already handled in Call or BatchCall. When the
-				// read loop goes down, it will signal all other current operations.
-				for _, id := range lastOp.ids {
-					delete(c.respWait, string(id))
-				}
+				// Remove response handlers for the last send. When the read loop
+				// goes down, it will signal all other current operations.
+				conn.handler.removeRequestOp(lastOp)
 			}
-			// Listen for send ops again.
-			requestOpLock = c.requestOp
+			// Let the next request in.
+			reqInitLock = c.reqInit
 			lastOp = nil
-		}
-	}
-}
-
-// closeRequestOps unblocks pending send ops and active subscriptions.
-func (c *Client) closeRequestOps(err error) {
-	didClose := make(map[*requestOp]bool)
 
-	for id, op := range c.respWait {
-		// Remove the op so that later calls will not close op.resp again.
-		delete(c.respWait, id)
-
-		if !didClose[op] {
-			op.err = err
-			close(op.resp)
-			didClose[op] = true
+		case op := <-c.reqTimeout:
+			conn.handler.removeRequestOp(op)
 		}
 	}
-	for id, sub := range c.subs {
-		delete(c.subs, id)
-		sub.quitWithError(err, false)
-	}
-}
-
-func (c *Client) handleNotification(msg *jsonrpcMessage) {
-	if !strings.HasSuffix(msg.Method, notificationMethodSuffix) {
-		log.Debug("dropping non-subscription message", "msg", msg)
-		return
-	}
-	var subResult struct {
-		ID     string          `json:"subscription"`
-		Result json.RawMessage `json:"result"`
-	}
-	if err := json.Unmarshal(msg.Params, &subResult); err != nil {
-		log.Debug("dropping invalid subscription message", "msg", msg)
-		return
-	}
-	if c.subs[subResult.ID] != nil {
-		c.subs[subResult.ID].deliver(subResult.Result)
-	}
-}
-
-func (c *Client) handleResponse(msg *jsonrpcMessage) {
-	op := c.respWait[string(msg.ID)]
-	if op == nil {
-		log.Debug("unsolicited response", "msg", msg)
-		return
-	}
-	delete(c.respWait, string(msg.ID))
-	// For normal responses, just forward the reply to Call/BatchCall.
-	if op.sub == nil {
-		op.resp <- msg
-		return
-	}
-	// For subscription responses, start the subscription if the server
-	// indicates success. EthSubscribe gets unblocked in either case through
-	// the op.resp channel.
-	defer close(op.resp)
-	if msg.Error != nil {
-		op.err = msg.Error
-		return
-	}
-	if op.err = json.Unmarshal(msg.Result, &op.sub.subid); op.err == nil {
-		go op.sub.start()
-		c.subs[op.sub.subid] = op.sub
-	}
 }
 
-// Reading happens on a dedicated goroutine.
-
-func (c *Client) read(conn net.Conn) error {
-	var (
-		buf json.RawMessage
-		dec = json.NewDecoder(conn)
-	)
-	readMessage := func() (rs []*jsonrpcMessage, err error) {
-		buf = buf[:0]
-		if err = dec.Decode(&buf); err != nil {
-			return nil, err
-		}
-		if isBatch(buf) {
-			err = json.Unmarshal(buf, &rs)
-		} else {
-			rs = make([]*jsonrpcMessage, 1)
-			err = json.Unmarshal(buf, &rs[0])
-		}
-		return rs, err
-	}
-
+// drainRead drops read messages until an error occurs.
+func (c *Client) drainRead() {
 	for {
-		resp, err := readMessage()
-		if err != nil {
-			c.readErr <- err
-			return err
-		}
-		c.readResp <- resp
-	}
-}
-
-// Subscriptions.
-
-// A ClientSubscription represents a subscription established through EthSubscribe.
-type ClientSubscription struct {
-	client    *Client
-	etype     reflect.Type
-	channel   reflect.Value
-	namespace string
-	subid     string
-	in        chan json.RawMessage
-
-	quitOnce sync.Once     // ensures quit is closed once
-	quit     chan struct{} // quit is closed when the subscription exits
-	errOnce  sync.Once     // ensures err is closed once
-	err      chan error
-}
-
-func newClientSubscription(c *Client, namespace string, channel reflect.Value) *ClientSubscription {
-	sub := &ClientSubscription{
-		client:    c,
-		namespace: namespace,
-		etype:     channel.Type().Elem(),
-		channel:   channel,
-		quit:      make(chan struct{}),
-		err:       make(chan error, 1),
-		in:        make(chan json.RawMessage),
-	}
-	return sub
-}
-
-// Err returns the subscription error channel. The intended use of Err is to schedule
-// resubscription when the client connection is closed unexpectedly.
-//
-// The error channel receives a value when the subscription has ended due
-// to an error. The received error is nil if Close has been called
-// on the underlying client and no other error has occurred.
-//
-// The error channel is closed when Unsubscribe is called on the subscription.
-func (sub *ClientSubscription) Err() <-chan error {
-	return sub.err
-}
-
-// 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.errOnce.Do(func() { close(sub.err) })
-}
-
-func (sub *ClientSubscription) quitWithError(err error, unsubscribeServer bool) {
-	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
-		// unblocks deliver.
-		close(sub.quit)
-		if unsubscribeServer {
-			sub.requestUnsubscribe()
-		}
-		if err != nil {
-			if err == ErrClientQuit {
-				err = nil // Adhere to subscription semantics.
-			}
-			sub.err <- err
+		select {
+		case <-c.readOp:
+		case <-c.readErr:
+			return
 		}
-	})
-}
-
-func (sub *ClientSubscription) deliver(result json.RawMessage) (ok bool) {
-	select {
-	case sub.in <- result:
-		return true
-	case <-sub.quit:
-		return false
 	}
 }
 
-func (sub *ClientSubscription) start() {
-	sub.quitWithError(sub.forward())
-}
-
-func (sub *ClientSubscription) forward() (err error, unsubscribeServer bool) {
-	cases := []reflect.SelectCase{
-		{Dir: reflect.SelectRecv, Chan: reflect.ValueOf(sub.quit)},
-		{Dir: reflect.SelectRecv, Chan: reflect.ValueOf(sub.in)},
-		{Dir: reflect.SelectSend, Chan: sub.channel},
-	}
-	buffer := list.New()
-	defer buffer.Init()
+// read decodes RPC messages from a codec, feeding them into dispatch.
+func (c *Client) read(codec ServerCodec) {
 	for {
-		var chosen int
-		var recv reflect.Value
-		if buffer.Len() == 0 {
-			// Idle, omit send case.
-			chosen, recv, _ = reflect.Select(cases[:2])
-		} else {
-			// Non-empty buffer, send the first queued item.
-			cases[2].Send = reflect.ValueOf(buffer.Front().Value)
-			chosen, recv, _ = reflect.Select(cases)
+		msgs, batch, err := codec.Read()
+		if _, ok := err.(*json.SyntaxError); ok {
+			codec.Write(context.Background(), errorMessage(&parseError{err.Error()}))
 		}
-
-		switch chosen {
-		case 0: // <-sub.quit
-			return nil, false
-		case 1: // <-sub.in
-			val, err := sub.unmarshal(recv.Interface().(json.RawMessage))
-			if err != nil {
-				return err, true
-			}
-			if buffer.Len() == maxClientSubscriptionBuffer {
-				return ErrSubscriptionQueueOverflow, true
-			}
-			buffer.PushBack(val)
-		case 2: // sub.channel<-
-			cases[2].Send = reflect.Value{} // Don't hold onto the value.
-			buffer.Remove(buffer.Front())
+		if err != nil {
+			c.readErr <- err
+			return
 		}
+		c.readOp <- readOp{msgs, batch}
 	}
 }
-
-func (sub *ClientSubscription) unmarshal(result json.RawMessage) (interface{}, error) {
-	val := reflect.New(sub.etype)
-	err := json.Unmarshal(result, val.Interface())
-	return val.Elem().Interface(), err
-}
-
-func (sub *ClientSubscription) requestUnsubscribe() error {
-	var result interface{}
-	return sub.client.Call(&result, sub.namespace+unsubscribeMethodSuffix, sub.subid)
-}

rpc/client_test.go

@@ -35,13 +35,13 @@ import (
 )
 
 func TestClientRequest(t *testing.T) {
-	server := newTestServer("service", new(Service))
+	server := newTestServer()
 	defer server.Stop()
 	client := DialInProc(server)
 	defer client.Close()
 
 	var resp Result
-	if err := client.Call(&resp, "service_echo", "hello", 10, &Args{"world"}); err != nil {
+	if err := client.Call(&resp, "test_echo", "hello", 10, &Args{"world"}); err != nil {
 		t.Fatal(err)
 	}
 	if !reflect.DeepEqual(resp, Result{"hello", 10, &Args{"world"}}) {
@@ -50,19 +50,19 @@ func TestClientRequest(t *testing.T) {
 }
 
 func TestClientBatchRequest(t *testing.T) {
-	server := newTestServer("service", new(Service))
+	server := newTestServer()
 	defer server.Stop()
 	client := DialInProc(server)
 	defer client.Close()
 
 	batch := []BatchElem{
 		{
-			Method: "service_echo",
+			Method: "test_echo",
 			Args:   []interface{}{"hello", 10, &Args{"world"}},
 			Result: new(Result),
 		},
 		{
-			Method: "service_echo",
+			Method: "test_echo",
 			Args:   []interface{}{"hello2", 11, &Args{"world"}},
 			Result: new(Result),
 		},
@@ -77,12 +77,12 @@ func TestClientBatchRequest(t *testing.T) {
 	}
 	wantResult := []BatchElem{
 		{
-			Method: "service_echo",
+			Method: "test_echo",
 			Args:   []interface{}{"hello", 10, &Args{"world"}},
 			Result: &Result{"hello", 10, &Args{"world"}},
 		},
 		{
-			Method: "service_echo",
+			Method: "test_echo",
 			Args:   []interface{}{"hello2", 11, &Args{"world"}},
 			Result: &Result{"hello2", 11, &Args{"world"}},
 		},
@@ -90,7 +90,7 @@ func TestClientBatchRequest(t *testing.T) {
 			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"},
+			Error:  &jsonError{Code: -32601, Message: "the method no_such_method does not exist/is not available"},
 		},
 	}
 	if !reflect.DeepEqual(batch, wantResult) {
@@ -98,6 +98,17 @@ func TestClientBatchRequest(t *testing.T) {
 	}
 }
 
+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, &Args{"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) }
@@ -106,7 +117,12 @@ 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) {
-	server := newTestServer("service", new(Service))
+	// 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
@@ -142,11 +158,6 @@ func testClientCancel(transport string, t *testing.T) {
 		panic("unknown transport: " + transport)
 	}
 
-	// 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()
-
 	// The actual test starts here.
 	var (
 		wg       sync.WaitGroup
@@ -174,7 +185,8 @@ func testClientCancel(transport string, t *testing.T) {
 			}
 			// Now perform a call with the context.
 			// The key thing here is that no call will ever complete successfully.
-			err := client.CallContext(ctx, nil, "service_sleep", 2*maxContextCancelTimeout)
+			sleepTime := maxContextCancelTimeout + 20*time.Millisecond
+			err := client.CallContext(ctx, nil, "test_sleep", sleepTime)
 			if err != nil {
 				log.Debug(fmt.Sprint("got expected error:", err))
 			} else {
@@ -191,7 +203,7 @@ func testClientCancel(transport string, t *testing.T) {
 }
 
 func TestClientSubscribeInvalidArg(t *testing.T) {
-	server := newTestServer("service", new(Service))
+	server := newTestServer()
 	defer server.Stop()
 	client := DialInProc(server)
 	defer client.Close()
@@ -221,46 +233,14 @@ func TestClientSubscribeInvalidArg(t *testing.T) {
 }
 
 func TestClientSubscribe(t *testing.T) {
-	server := newTestServer("eth", new(NotificationTestService))
-	defer server.Stop()
-	client := DialInProc(server)
-	defer client.Close()
-
-	nc := make(chan int)
-	count := 10
-	sub, err := client.EthSubscribe(context.Background(), 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")
-	}
-}
-
-func TestClientSubscribeCustomNamespace(t *testing.T) {
-	namespace := "custom"
-	server := newTestServer(namespace, new(NotificationTestService))
+	server := newTestServer()
 	defer server.Stop()
 	client := DialInProc(server)
 	defer client.Close()
 
 	nc := make(chan int)
 	count := 10
-	sub, err := client.Subscribe(context.Background(), namespace, nc, "someSubscription", count, 0)
+	sub, err := client.Subscribe(context.Background(), "nftest", nc, "someSubscription", count, 0)
 	if err != nil {
 		t.Fatal("can't subscribe:", err)
 	}
@@ -283,14 +263,17 @@ func TestClientSubscribeCustomNamespace(t *testing.T) {
 	}
 }
 
-// In this test, the connection drops while EthSubscribe is
-// waiting for a response.
+// In this test, the connection drops while Subscribe is waiting for a response.
 func TestClientSubscribeClose(t *testing.T) {
-	service := &NotificationTestService{
+	server := newTestServer()
+	service := &notificationTestService{
 		gotHangSubscriptionReq:  make(chan struct{}),
 		unblockHangSubscription: make(chan struct{}),
 	}
-	server := newTestServer("eth", service)
+	if err := server.RegisterName("nftest2", service); err != nil {
+		t.Fatal(err)
+	}
+
 	defer server.Stop()
 	client := DialInProc(server)
 	defer client.Close()
@@ -302,7 +285,7 @@ func TestClientSubscribeClose(t *testing.T) {
 		err  error
 	)
 	go func() {
-		sub, err = client.EthSubscribe(context.Background(), nc, "hangSubscription", 999)
+		sub, err = client.Subscribe(context.Background(), "nftest2", nc, "hangSubscription", 999)
 		errc <- err
 	}()
 
@@ -313,27 +296,26 @@ func TestClientSubscribeClose(t *testing.T) {
 	select {
 	case err := <-errc:
 		if err == nil {
-			t.Errorf("EthSubscribe returned nil error after Close")
+			t.Errorf("Subscribe returned nil error after Close")
 		}
 		if sub != nil {
-			t.Error("EthSubscribe returned non-nil subscription after Close")
+			t.Error("Subscribe returned non-nil subscription after Close")
 		}
 	case <-time.After(1 * time.Second):
-		t.Fatalf("EthSubscribe did not return within 1s after Close")
+		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) {
-	service := &NotificationTestService{}
-	server := newTestServer("eth", service)
+	server := newTestServer()
 	defer server.Stop()
 
 	for i := 0; i < 20; i++ {
 		client := DialInProc(server)
 		nc := make(chan int)
-		sub, err := client.EthSubscribe(context.Background(), nc, "someSubscription", 3, 1)
+		sub, err := client.Subscribe(context.Background(), "nftest", nc, "someSubscription", 3, 1)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -350,7 +332,7 @@ func TestClientCloseUnsubscribeRace(t *testing.T) {
 // 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("eth", new(NotificationTestService))
+	server := newTestServer()
 	defer server.Stop()
 
 	doTest := func(count int, wantError bool) {
@@ -362,7 +344,7 @@ func TestClientNotificationStorm(t *testing.T) {
 		// Subscribe on the server. It will start sending many notifications
 		// very quickly.
 		nc := make(chan int)
-		sub, err := client.EthSubscribe(ctx, nc, "someSubscription", count, 0)
+		sub, err := client.Subscribe(ctx, "nftest", nc, "someSubscription", count, 0)
 		if err != nil {
 			t.Fatal("can't subscribe:", err)
 		}
@@ -384,7 +366,7 @@ func TestClientNotificationStorm(t *testing.T) {
 				return
 			}
 			var r int
-			err := client.CallContext(ctx, &r, "eth_echo", i)
+			err := client.CallContext(ctx, &r, "nftest_echo", i)
 			if err != nil {
 				if !wantError {
 					t.Fatalf("(%d/%d) call error: %v", i, count, err)
@@ -399,7 +381,7 @@ func TestClientNotificationStorm(t *testing.T) {
 }
 
 func TestClientHTTP(t *testing.T) {
-	server := newTestServer("service", new(Service))
+	server := newTestServer()
 	defer server.Stop()
 
 	client, hs := httpTestClient(server, "http", nil)
@@ -416,7 +398,7 @@ func TestClientHTTP(t *testing.T) {
 	for i := range results {
 		i := i
 		go func() {
-			errc <- client.Call(&results[i], "service_echo",
+			errc <- client.Call(&results[i], "test_echo",
 				wantResult.String, wantResult.Int, wantResult.Args)
 		}()
 	}
@@ -445,16 +427,16 @@ func TestClientHTTP(t *testing.T) {
 
 func TestClientReconnect(t *testing.T) {
 	startServer := func(addr string) (*Server, net.Listener) {
-		srv := newTestServer("service", new(Service))
+		srv := newTestServer()
 		l, err := net.Listen("tcp", addr)
 		if err != nil {
-			t.Fatal(err)
+			t.Fatal("can't listen:", err)
 		}
 		go http.Serve(l, srv.WebsocketHandler([]string{"*"}))
 		return srv, l
 	}
 
-	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	ctx, cancel := context.WithTimeout(context.Background(), 12*time.Second)
 	defer cancel()
 
 	// Start a server and corresponding client.
@@ -466,21 +448,22 @@ func TestClientReconnect(t *testing.T) {
 
 	// Perform a call. This should work because the server is up.
 	var resp Result
-	if err := client.CallContext(ctx, &resp, "service_echo", "", 1, nil); err != nil {
+	if err := client.CallContext(ctx, &resp, "test_echo", "", 1, nil); err != nil {
 		t.Fatal(err)
 	}
 
-	// Shut down the server and try calling again. It shouldn't work.
+	// Shut down the server and allow for some cool down time so we can listen on the same
+	// address again.
 	l1.Close()
 	s1.Stop()
-	if err := client.CallContext(ctx, &resp, "service_echo", "", 2, nil); err == nil {
+	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)
 	}
 
-	// Allow for some cool down time so we can listen on the same address again.
-	time.Sleep(2 * time.Second)
-
 	// 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())
@@ -493,7 +476,7 @@ func TestClientReconnect(t *testing.T) {
 		go func() {
 			<-start
 			var resp Result
-			errors <- client.CallContext(ctx, &resp, "service_echo", "", 3, nil)
+			errors <- client.CallContext(ctx, &resp, "test_echo", "", 3, nil)
 		}()
 	}
 	close(start)
@@ -503,20 +486,12 @@ func TestClientReconnect(t *testing.T) {
 			errcount++
 		}
 	}
-	t.Log("err:", err)
+	t.Logf("%d errors, last error: %v", errcount, err)
 	if errcount > 1 {
 		t.Errorf("expected one error after disconnect, got %d", errcount)
 	}
 }
 
-func newTestServer(serviceName string, service interface{}) *Server {
-	server := NewServer()
-	if err := server.RegisterName(serviceName, service); err != nil {
-		panic(err)
-	}
-	return server
-}
-
 func httpTestClient(srv *Server, transport string, fl *flakeyListener) (*Client, *httptest.Server) {
 	// Create the HTTP server.
 	var hs *httptest.Server

rpc/doc.go

@@ -15,43 +15,49 @@
 // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
 
 /*
-Package rpc provides access to the exported methods of an object across a network
-or other I/O connection. After creating a server instance objects can be registered,
-making it visible from the outside. Exported methods that follow specific
-conventions can be called remotely. It also has support for the publish/subscribe
-pattern.
+
+Package rpc implements bi-directional JSON-RPC 2.0 on multiple transports.
+
+It provides access to the exported methods of an object across a network or other I/O
+connection. After creating a server or client instance, objects can be registered to make
+them visible as 'services'. Exported methods that follow specific conventions can be
+called remotely. It also has support for the publish/subscribe pattern.
+
+RPC Methods
 
 Methods that satisfy the following criteria are made available for remote access:
- - object must be exported
+
  - 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:
+
  func (s *CalcService) Add(a, b int) (int, error)
 
-When the returned error isn't nil the returned integer is ignored and the error is
-sent back to the client. Otherwise the returned integer is sent back to the client.
+When the returned error isn't nil the returned integer is ignored and the error is sent
+back to the client. Otherwise the returned integer is sent back to the client.
 
-Optional arguments are supported by accepting pointer values as arguments. E.g.
-if we want to do the addition in an optional finite field we can accept a mod
-argument as pointer value.
+Optional arguments are supported by accepting pointer values as arguments. E.g. if we want
+to do the addition in an optional finite field we can accept a mod argument as pointer
+value.
 
- func (s *CalService) Add(a, b int, mod *int) (int, error)
+ func (s *CalcService) Add(a, b int, mod *int) (int, error)
 
-This RPC method can be called with 2 integers and a null value as third argument.
-In that case the mod argument will be nil. Or it can be called with 3 integers,
-in that case mod will be pointing to the given third argument. Since the optional
-argument is the last argument the RPC package will also accept 2 integers as
-arguments. It will pass the mod argument as nil to the RPC method.
+This RPC method can be called with 2 integers and a null value as third argument. In that
+case the mod argument will be nil. Or it can be called with 3 integers, in that case mod
+will be pointing to the given third argument. Since the optional argument is the last
+argument the RPC package will also accept 2 integers as arguments. It will pass the mod
+argument as nil to the RPC method.
 
-The server offers the ServeCodec method which accepts a ServerCodec instance. It will
-read requests from the codec, process the request and sends the response back to the
-client using the codec. The server can execute requests concurrently. Responses
-can be sent back to the client out of order.
+The server offers the ServeCodec method which accepts a ServerCodec instance. It will read
+requests from the codec, process the request and sends the response back to the client
+using the codec. The server can execute requests concurrently. Responses can be sent back
+to the client out of order.
 
 An example server which uses the JSON codec:
+
  type CalculatorService struct {}
 
  func (s *CalculatorService) Add(a, b int) int {
@@ -73,26 +79,40 @@ An example server which uses the JSON codec:
  for {
 	c, _ := l.AcceptUnix()
 	codec := v2.NewJSONCodec(c)
-	go server.ServeCodec(codec)
+	go server.ServeCodec(codec, 0)
  }
 
+Subscriptions
+
 The package also supports the publish subscribe pattern through the use of subscriptions.
-A method that is considered eligible for notifications must satisfy the following criteria:
- - object must be exported
+A method that is considered eligible for notifications must satisfy the following
+criteria:
+
  - method must be exported
  - first method argument type must be context.Context
  - method argument(s) must be exported or builtin types
- - method must return the tuple Subscription, error
+ - method must have return types (rpc.Subscription, error)
 
 An example method:
- func (s *BlockChainService) NewBlocks(ctx context.Context) (Subscription, error) {
+
+ func (s *BlockChainService) NewBlocks(ctx context.Context) (rpc.Subscription, error) {
  	...
  }
 
-Subscriptions are deleted when:
- - the user sends an unsubscribe request
- - the connection which was used to create the subscription is closed. This can be initiated
-   by the client and server. The server will close the connection on a write error or when
-   the queue of buffered notifications gets too big.
+When the service containing the subscription method is registered to the server, for
+example under the "blockchain" namespace, a subscription is created by calling the
+"blockchain_subscribe" method.
+
+Subscriptions are deleted when the user sends an unsubscribe request or when the
+connection which was used to create the subscription is closed. This can be initiated by
+the client and server. The server will close the connection for any write error.
+
+For more information about subscriptions, see https://github.com/ethereum/go-ethereum/wiki/RPC-PUB-SUB.
+
+Reverse Calls
+
+In any method handler, an instance of rpc.Client can be accessed through the
+ClientFromContext method. Using this client instance, server-to-client method calls can be
+performed on the RPC connection.
 */
 package rpc

rpc/errors.go

@@ -18,18 +18,31 @@ package rpc
 
 import "fmt"
 
-// request is for an unknown service
-type methodNotFoundError struct {
-	service string
-	method  string
-}
+const defaultErrorCode = -32000
+
+type methodNotFoundError struct{ method string }
 
 func (e *methodNotFoundError) ErrorCode() int { return -32601 }
 
 func (e *methodNotFoundError) Error() string {
-	return fmt.Sprintf("The method %s%s%s does not exist/is not available", e.service, serviceMethodSeparator, e.method)
+	return fmt.Sprintf("the method %s does not exist/is not available", e.method)
+}
+
+type subscriptionNotFoundError struct{ namespace, subscription string }
+
+func (e *subscriptionNotFoundError) ErrorCode() int { return -32601 }
+
+func (e *subscriptionNotFoundError) Error() string {
+	return fmt.Sprintf("no %q subscription in %s namespace", e.subscription, e.namespace)
 }
 
+// Invalid JSON was received by the server.
+type parseError struct{ message string }
+
+func (e *parseError) ErrorCode() int { return -32700 }
+
+func (e *parseError) Error() string { return e.message }
+
 // received message isn't a valid request
 type invalidRequestError struct{ message string }
 
@@ -50,17 +63,3 @@ type invalidParamsError struct{ message string }
 func (e *invalidParamsError) ErrorCode() int { return -32602 }
 
 func (e *invalidParamsError) Error() string { return e.message }
-
-// logic error, callback returned an error
-type callbackError struct{ message string }
-
-func (e *callbackError) ErrorCode() int { return -32000 }
-
-func (e *callbackError) Error() string { return e.message }
-
-// issued when a request is received after the server is issued to stop.
-type shutdownError struct{}
-
-func (e *shutdownError) ErrorCode() int { return -32000 }
-
-func (e *shutdownError) Error() string { return "server is shutting down" }

rpc/handler.go

@@ -0,0 +1,397 @@
+// Copyright 2018 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 <http://www.gnu.org/licenses/>.
+
+package rpc
+
+import (
+	"context"
+	"encoding/json"
+	"reflect"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/ethereum/go-ethereum/log"
+)
+
+// handler handles JSON-RPC messages. There is one handler per connection. Note that
+// handler is not safe for concurrent use. Message handling never blocks indefinitely
+// because RPCs are processed on background goroutines launched by handler.
+//
+// The entry points for incoming messages are:
+//
+//    h.handleMsg(message)
+//    h.handleBatch(message)
+//
+// Outgoing calls use the requestOp struct. Register the request before sending it
+// on the connection:
+//
+//    op := &requestOp{ids: ...}
+//    h.addRequestOp(op)
+//
+// Now send the request, then wait for the reply to be delivered through handleMsg:
+//
+//    if err := op.wait(...); err != nil {
+//        h.removeRequestOp(op) // timeout, etc.
+//    }
+//
+type handler struct {
+	reg            *serviceRegistry
+	unsubscribeCb  *callback
+	idgen          func() ID                      // subscription ID generator
+	respWait       map[string]*requestOp          // active client requests
+	clientSubs     map[string]*ClientSubscription // active client subscriptions
+	callWG         sync.WaitGroup                 // pending call goroutines
+	rootCtx        context.Context                // canceled by close()
+	cancelRoot     func()                         // cancel function for rootCtx
+	conn           jsonWriter                     // where responses will be sent
+	log            log.Logger
+	allowSubscribe bool
+
+	subLock    sync.Mutex
+	serverSubs map[ID]*Subscription
+}
+
+type callProc struct {
+	ctx       context.Context
+	notifiers []*Notifier
+}
+
+func newHandler(connCtx context.Context, conn jsonWriter, idgen func() ID, reg *serviceRegistry) *handler {
+	rootCtx, cancelRoot := context.WithCancel(connCtx)
+	h := &handler{
+		reg:            reg,
+		idgen:          idgen,
+		conn:           conn,
+		respWait:       make(map[string]*requestOp),
+		clientSubs:     make(map[string]*ClientSubscription),
+		rootCtx:        rootCtx,
+		cancelRoot:     cancelRoot,
+		allowSubscribe: true,
+		serverSubs:     make(map[ID]*Subscription),
+		log:            log.Root(),
+	}
+	if conn.RemoteAddr() != "" {
+		h.log = h.log.New("conn", conn.RemoteAddr())
+	}
+	h.unsubscribeCb = newCallback(reflect.Value{}, reflect.ValueOf(h.unsubscribe))
+	return h
+}
+
+// handleBatch executes all messages in a batch and returns the responses.
+func (h *handler) handleBatch(msgs []*jsonrpcMessage) {
+	// Emit error response for empty batches:
+	if len(msgs) == 0 {
+		h.startCallProc(func(cp *callProc) {
+			h.conn.Write(cp.ctx, errorMessage(&invalidRequestError{"empty batch"}))
+		})
+		return
+	}
+
+	// Handle non-call messages first:
+	calls := make([]*jsonrpcMessage, 0, len(msgs))
+	for _, msg := range msgs {
+		if handled := h.handleImmediate(msg); !handled {
+			calls = append(calls, msg)
+		}
+	}
+	if len(calls) == 0 {
+		return
+	}
+	// Process calls on a goroutine because they may block indefinitely:
+	h.startCallProc(func(cp *callProc) {
+		answers := make([]*jsonrpcMessage, 0, len(msgs))
+		for _, msg := range calls {
+			if answer := h.handleCallMsg(cp, msg); answer != nil {
+				answers = append(answers, answer)
+			}
+		}
+		h.addSubscriptions(cp.notifiers)
+		if len(answers) > 0 {
+			h.conn.Write(cp.ctx, answers)
+		}
+		for _, n := range cp.notifiers {
+			n.activate()
+		}
+	})
+}
+
+// handleMsg handles a single message.
+func (h *handler) handleMsg(msg *jsonrpcMessage) {
+	if ok := h.handleImmediate(msg); ok {
+		return
+	}
+	h.startCallProc(func(cp *callProc) {
+		answer := h.handleCallMsg(cp, msg)
+		h.addSubscriptions(cp.notifiers)
+		if answer != nil {
+			h.conn.Write(cp.ctx, answer)
+		}
+		for _, n := range cp.notifiers {
+			n.activate()
+		}
+	})
+}
+
+// close cancels all requests except for inflightReq and waits for
+// call goroutines to shut down.
+func (h *handler) close(err error, inflightReq *requestOp) {
+	h.cancelAllRequests(err, inflightReq)
+	h.cancelRoot()
+	h.callWG.Wait()
+	h.cancelServerSubscriptions(err)
+}
+
+// addRequestOp registers a request operation.
+func (h *handler) addRequestOp(op *requestOp) {
+	for _, id := range op.ids {
+		h.respWait[string(id)] = op
+	}
+}
+
+// removeRequestOps stops waiting for the given request IDs.
+func (h *handler) removeRequestOp(op *requestOp) {
+	for _, id := range op.ids {
+		delete(h.respWait, string(id))
+	}
+}
+
+// cancelAllRequests unblocks and removes pending requests and active subscriptions.
+func (h *handler) cancelAllRequests(err error, inflightReq *requestOp) {
+	didClose := make(map[*requestOp]bool)
+	if inflightReq != nil {
+		didClose[inflightReq] = true
+	}
+
+	for id, op := range h.respWait {
+		// Remove the op so that later calls will not close op.resp again.
+		delete(h.respWait, id)
+
+		if !didClose[op] {
+			op.err = err
+			close(op.resp)
+			didClose[op] = true
+		}
+	}
+	for id, sub := range h.clientSubs {
+		delete(h.clientSubs, id)
+		sub.quitWithError(err, false)
+	}
+}
+
+func (h *handler) addSubscriptions(nn []*Notifier) {
+	h.subLock.Lock()
+	defer h.subLock.Unlock()
+
+	for _, n := range nn {
+		if sub := n.takeSubscription(); sub != nil {
+			h.serverSubs[sub.ID] = sub
+		}
+	}
+}
+
+// cancelServerSubscriptions removes all subscriptions and closes their error channels.
+func (h *handler) cancelServerSubscriptions(err error) {
+	h.subLock.Lock()
+	defer h.subLock.Unlock()
+
+	for id, s := range h.serverSubs {
+		s.err <- err
+		close(s.err)
+		delete(h.serverSubs, id)
+	}
+}
+
+// startCallProc runs fn in a new goroutine and starts tracking it in the h.calls wait group.
+func (h *handler) startCallProc(fn func(*callProc)) {
+	h.callWG.Add(1)
+	go func() {
+		ctx, cancel := context.WithCancel(h.rootCtx)
+		defer h.callWG.Done()
+		defer cancel()
+		fn(&callProc{ctx: ctx})
+	}()
+}
+
+// handleImmediate executes non-call messages. It returns false if the message is a
+// call or requires a reply.
+func (h *handler) handleImmediate(msg *jsonrpcMessage) bool {
+	start := time.Now()
+	switch {
+	case msg.isNotification():
+		if strings.HasSuffix(msg.Method, notificationMethodSuffix) {
+			h.handleSubscriptionResult(msg)
+			return true
+		}
+		return false
+	case msg.isResponse():
+		h.handleResponse(msg)
+		h.log.Trace("Handled RPC response", "reqid", idForLog{msg.ID}, "t", time.Since(start))
+		return true
+	default:
+		return false
+	}
+}
+
+// handleSubscriptionResult processes subscription notifications.
+func (h *handler) handleSubscriptionResult(msg *jsonrpcMessage) {
+	var result subscriptionResult
+	if err := json.Unmarshal(msg.Params, &result); err != nil {
+		h.log.Debug("Dropping invalid subscription message")
+		return
+	}
+	if h.clientSubs[result.ID] != nil {
+		h.clientSubs[result.ID].deliver(result.Result)
+	}
+}
+
+// handleResponse processes method call responses.
+func (h *handler) handleResponse(msg *jsonrpcMessage) {
+	op := h.respWait[string(msg.ID)]
+	if op == nil {
+		h.log.Debug("Unsolicited RPC response", "reqid", idForLog{msg.ID})
+		return
+	}
+	delete(h.respWait, string(msg.ID))
+	// For normal responses, just forward the reply to Call/BatchCall.
+	if op.sub == nil {
+		op.resp <- msg
+		return
+	}
+	// For subscription responses, start the subscription if the server
+	// indicates success. EthSubscribe gets unblocked in either case through
+	// the op.resp channel.
+	defer close(op.resp)
+	if msg.Error != nil {
+		op.err = msg.Error
+		return
+	}
+	if op.err = json.Unmarshal(msg.Result, &op.sub.subid); op.err == nil {
+		go op.sub.start()
+		h.clientSubs[op.sub.subid] = op.sub
+	}
+}
+
+// handleCallMsg executes a call message and returns the answer.
+func (h *handler) handleCallMsg(ctx *callProc, msg *jsonrpcMessage) *jsonrpcMessage {
+	start := time.Now()
+	switch {
+	case msg.isNotification():
+		h.handleCall(ctx, msg)
+		h.log.Debug("Served "+msg.Method, "t", time.Since(start))
+		return nil
+	case msg.isCall():
+		resp := h.handleCall(ctx, msg)
+		if resp.Error != nil {
+			h.log.Info("Served "+msg.Method, "reqid", idForLog{msg.ID}, "t", time.Since(start), "err", resp.Error.Message)
+		} else {
+			h.log.Debug("Served "+msg.Method, "reqid", idForLog{msg.ID}, "t", time.Since(start))
+		}
+		return resp
+	case msg.hasValidID():
+		return msg.errorResponse(&invalidRequestError{"invalid request"})
+	default:
+		return errorMessage(&invalidRequestError{"invalid request"})
+	}
+}
+
+// handleCall processes method calls.
+func (h *handler) handleCall(cp *callProc, msg *jsonrpcMessage) *jsonrpcMessage {
+	if msg.isSubscribe() {
+		return h.handleSubscribe(cp, msg)
+	}
+	var callb *callback
+	if msg.isUnsubscribe() {
+		callb = h.unsubscribeCb
+	} else {
+		callb = h.reg.callback(msg.Method)
+	}
+	if callb == nil {
+		return msg.errorResponse(&methodNotFoundError{method: msg.Method})
+	}
+	args, err := parsePositionalArguments(msg.Params, callb.argTypes)
+	if err != nil {
+		return msg.errorResponse(&invalidParamsError{err.Error()})
+	}
+
+	return h.runMethod(cp.ctx, msg, callb, args)
+}
+
+// handleSubscribe processes *_subscribe method calls.
+func (h *handler) handleSubscribe(cp *callProc, msg *jsonrpcMessage) *jsonrpcMessage {
+	if !h.allowSubscribe {
+		return msg.errorResponse(ErrNotificationsUnsupported)
+	}
+
+	// Subscription method name is first argument.
+	name, err := parseSubscriptionName(msg.Params)
+	if err != nil {
+		return msg.errorResponse(&invalidParamsError{err.Error()})
+	}
+	namespace := msg.namespace()
+	callb := h.reg.subscription(namespace, name)
+	if callb == nil {
+		return msg.errorResponse(&subscriptionNotFoundError{namespace, name})
+	}
+
+	// Parse subscription name arg too, but remove it before calling the callback.
+	argTypes := append([]reflect.Type{stringType}, callb.argTypes...)
+	args, err := parsePositionalArguments(msg.Params, argTypes)
+	if err != nil {
+		return msg.errorResponse(&invalidParamsError{err.Error()})
+	}
+	args = args[1:]
+
+	// Install notifier in context so the subscription handler can find it.
+	n := &Notifier{h: h, namespace: namespace}
+	cp.notifiers = append(cp.notifiers, n)
+	ctx := context.WithValue(cp.ctx, notifierKey{}, n)
+
+	return h.runMethod(ctx, msg, callb, args)
+}
+
+// runMethod runs the Go callback for an RPC method.
+func (h *handler) runMethod(ctx context.Context, msg *jsonrpcMessage, callb *callback, args []reflect.Value) *jsonrpcMessage {
+	result, err := callb.call(ctx, msg.Method, args)
+	if err != nil {
+		return msg.errorResponse(err)
+	}
+	return msg.response(result)
+}
+
+// unsubscribe is the callback function for all *_unsubscribe calls.
+func (h *handler) unsubscribe(ctx context.Context, id ID) (bool, error) {
+	h.subLock.Lock()
+	defer h.subLock.Unlock()
+
+	s := h.serverSubs[id]
+	if s == nil {
+		return false, ErrSubscriptionNotFound
+	}
+	close(s.err)
+	delete(h.serverSubs, id)
+	return true, nil
+}
+
+type idForLog struct{ json.RawMessage }
+
+func (id idForLog) String() string {
+	if s, err := strconv.Unquote(string(id.RawMessage)); err == nil {
+		return s
+	}
+	return string(id.RawMessage)
+}

rpc/http.go

@@ -37,38 +37,39 @@ import (
 
 const (
 	maxRequestContentLength = 1024 * 512
+	contentType             = "application/json"
 )
 
-var (
-	// https://www.jsonrpc.org/historical/json-rpc-over-http.html#id13
-	acceptedContentTypes = []string{"application/json", "application/json-rpc", "application/jsonrequest"}
-	contentType          = acceptedContentTypes[0]
-	nullAddr, _          = net.ResolveTCPAddr("tcp", "127.0.0.1:0")
-)
+// https://www.jsonrpc.org/historical/json-rpc-over-http.html#id13
+var acceptedContentTypes = []string{contentType, "application/json-rpc", "application/jsonrequest"}
 
 type httpConn struct {
 	client    *http.Client
 	req       *http.Request
 	closeOnce sync.Once
-	closed    chan struct{}
+	closed    chan interface{}
 }
 
 // httpConn is treated specially by Client.
-func (hc *httpConn) LocalAddr() net.Addr              { return nullAddr }
-func (hc *httpConn) RemoteAddr() net.Addr             { return nullAddr }
-func (hc *httpConn) SetReadDeadline(time.Time) error  { return nil }
-func (hc *httpConn) SetWriteDeadline(time.Time) error { return nil }
-func (hc *httpConn) SetDeadline(time.Time) error      { return nil }
-func (hc *httpConn) Write([]byte) (int, error)        { panic("Write called") }
-
-func (hc *httpConn) Read(b []byte) (int, error) {
+func (hc *httpConn) Write(context.Context, interface{}) error {
+	panic("Write called on httpConn")
+}
+
+func (hc *httpConn) RemoteAddr() string {
+	return hc.req.URL.String()
+}
+
+func (hc *httpConn) Read() ([]*jsonrpcMessage, bool, error) {
 	<-hc.closed
-	return 0, io.EOF
+	return nil, false, io.EOF
 }
 
-func (hc *httpConn) Close() error {
+func (hc *httpConn) Close() {
 	hc.closeOnce.Do(func() { close(hc.closed) })
-	return nil
+}
+
+func (hc *httpConn) Closed() <-chan interface{} {
+	return hc.closed
 }
 
 // HTTPTimeouts represents the configuration params for the HTTP RPC server.
@@ -114,8 +115,8 @@ func DialHTTPWithClient(endpoint string, client *http.Client) (*Client, error) {
 	req.Header.Set("Accept", contentType)
 
 	initctx := context.Background()
-	return newClient(initctx, func(context.Context) (net.Conn, error) {
-		return &httpConn{client: client, req: req, closed: make(chan struct{})}, nil
+	return newClient(initctx, func(context.Context) (ServerCodec, error) {
+		return &httpConn{client: client, req: req, closed: make(chan interface{})}, nil
 	})
 }
 
@@ -184,17 +185,30 @@ func (hc *httpConn) doRequest(ctx context.Context, msg interface{}) (io.ReadClos
 	return resp.Body, nil
 }
 
-// httpReadWriteNopCloser wraps a io.Reader and io.Writer with a NOP Close method.
-type httpReadWriteNopCloser struct {
+// httpServerConn turns a HTTP connection into a Conn.
+type httpServerConn struct {
 	io.Reader
 	io.Writer
+	r *http.Request
 }
 
-// Close does nothing and returns always nil
-func (t *httpReadWriteNopCloser) Close() error {
-	return nil
+func newHTTPServerConn(r *http.Request, w http.ResponseWriter) ServerCodec {
+	body := io.LimitReader(r.Body, maxRequestContentLength)
+	conn := &httpServerConn{Reader: body, Writer: w, r: r}
+	return NewJSONCodec(conn)
 }
 
+// Close does nothing and always returns nil.
+func (t *httpServerConn) Close() error { return nil }
+
+// RemoteAddr returns the peer address of the underlying connection.
+func (t *httpServerConn) RemoteAddr() string {
+	return t.r.RemoteAddr
+}
+
+// SetWriteDeadline does nothing and always returns nil.
+func (t *httpServerConn) SetWriteDeadline(time.Time) error { return nil }
+
 // NewHTTPServer creates a new HTTP RPC server around an API provider.
 //
 // Deprecated: Server implements http.Handler
@@ -226,7 +240,7 @@ func NewHTTPServer(cors []string, vhosts []string, timeouts HTTPTimeouts, srv ht
 }
 
 // ServeHTTP serves JSON-RPC requests over HTTP.
-func (srv *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	// Permit dumb empty requests for remote health-checks (AWS)
 	if r.Method == http.MethodGet && r.ContentLength == 0 && r.URL.RawQuery == "" {
 		return
@@ -249,12 +263,10 @@ func (srv *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		ctx = context.WithValue(ctx, "Origin", origin)
 	}
 
-	body := io.LimitReader(r.Body, maxRequestContentLength)
-	codec := NewJSONCodec(&httpReadWriteNopCloser{body, w})
-	defer codec.Close()
-
 	w.Header().Set("content-type", contentType)
-	srv.ServeSingleRequest(ctx, codec, OptionMethodInvocation)
+	codec := newHTTPServerConn(r, w)
+	defer codec.Close()
+	s.serveSingleRequest(ctx, codec)
 }
 
 // validateRequest returns a non-zero response code and error message if the

rpc/inproc.go

@@ -24,10 +24,10 @@ import (
 // DialInProc attaches an in-process connection to the given RPC server.
 func DialInProc(handler *Server) *Client {
 	initctx := context.Background()
-	c, _ := newClient(initctx, func(context.Context) (net.Conn, error) {
+	c, _ := newClient(initctx, func(context.Context) (ServerCodec, error) {
 		p1, p2 := net.Pipe()
 		go handler.ServeCodec(NewJSONCodec(p1), OptionMethodInvocation|OptionSubscriptions)
-		return p2, nil
+		return NewJSONCodec(p2), nil
 	})
 	return c
 }

rpc/ipc.go

@@ -25,17 +25,17 @@ import (
 )
 
 // ServeListener accepts connections on l, serving JSON-RPC on them.
-func (srv *Server) ServeListener(l net.Listener) error {
+func (s *Server) ServeListener(l net.Listener) error {
 	for {
 		conn, err := l.Accept()
 		if netutil.IsTemporaryError(err) {
-			log.Warn("IPC accept error", "err", err)
+			log.Warn("RPC accept error", "err", err)
 			continue
 		} else if err != nil {
 			return err
 		}
-		log.Trace("IPC accepted connection")
-		go srv.ServeCodec(NewJSONCodec(conn), OptionMethodInvocation|OptionSubscriptions)
+		log.Trace("Accepted RPC connection", "conn", conn.RemoteAddr())
+		go s.ServeCodec(NewJSONCodec(conn), OptionMethodInvocation|OptionSubscriptions)
 	}
 }
 
@@ -46,7 +46,11 @@ func (srv *Server) ServeListener(l net.Listener) error {
 // The context is used for the initial connection establishment. It does not
 // affect subsequent interactions with the client.
 func DialIPC(ctx context.Context, endpoint string) (*Client, error) {
-	return newClient(ctx, func(ctx context.Context) (net.Conn, error) {
-		return newIPCConnection(ctx, endpoint)
+	return newClient(ctx, func(ctx context.Context) (ServerCodec, error) {
+		conn, err := newIPCConnection(ctx, endpoint)
+		if err != nil {
+			return nil, err
+		}
+		return NewJSONCodec(conn), err
 	})
 }

rpc/json.go

@@ -18,71 +18,110 @@ package rpc
 
 import (
 	"bytes"
+	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"reflect"
-	"strconv"
 	"strings"
 	"sync"
-
-	"github.com/ethereum/go-ethereum/log"
+	"time"
 )
 
 const (
-	jsonrpcVersion           = "2.0"
+	vsn                      = "2.0"
 	serviceMethodSeparator   = "_"
 	subscribeMethodSuffix    = "_subscribe"
 	unsubscribeMethodSuffix  = "_unsubscribe"
 	notificationMethodSuffix = "_subscription"
+
+	defaultWriteTimeout = 10 * time.Second // used if context has no deadline
 )
 
-type jsonRequest struct {
-	Method  string          `json:"method"`
-	Version string          `json:"jsonrpc"`
-	Id      json.RawMessage `json:"id,omitempty"`
-	Payload json.RawMessage `json:"params,omitempty"`
+var null = json.RawMessage("null")
+
+type subscriptionResult struct {
+	ID     string          `json:"subscription"`
+	Result json.RawMessage `json:"result,omitempty"`
 }
 
-type jsonSuccessResponse struct {
-	Version string      `json:"jsonrpc"`
-	Id      interface{} `json:"id,omitempty"`
-	Result  interface{} `json:"result"`
+// A value of this type can a JSON-RPC request, notification, successful response or
+// error response. Which one it is depends on the fields.
+type jsonrpcMessage struct {
+	Version string          `json:"jsonrpc,omitempty"`
+	ID      json.RawMessage `json:"id,omitempty"`
+	Method  string          `json:"method,omitempty"`
+	Params  json.RawMessage `json:"params,omitempty"`
+	Error   *jsonError      `json:"error,omitempty"`
+	Result  json.RawMessage `json:"result,omitempty"`
 }
 
-type jsonError struct {
-	Code    int         `json:"code"`
-	Message string      `json:"message"`
-	Data    interface{} `json:"data,omitempty"`
+func (msg *jsonrpcMessage) isNotification() bool {
+	return msg.ID == nil && msg.Method != ""
 }
 
-type jsonErrResponse struct {
-	Version string      `json:"jsonrpc"`
-	Id      interface{} `json:"id,omitempty"`
-	Error   jsonError   `json:"error"`
+func (msg *jsonrpcMessage) isCall() bool {
+	return msg.hasValidID() && msg.Method != ""
 }
 
-type jsonSubscription struct {
-	Subscription string      `json:"subscription"`
-	Result       interface{} `json:"result,omitempty"`
+func (msg *jsonrpcMessage) isResponse() bool {
+	return msg.hasValidID() && msg.Method == "" && msg.Params == nil && (msg.Result != nil || msg.Error != nil)
 }
 
-type jsonNotification struct {
-	Version string           `json:"jsonrpc"`
-	Method  string           `json:"method"`
-	Params  jsonSubscription `json:"params"`
+func (msg *jsonrpcMessage) hasValidID() bool {
+	return len(msg.ID) > 0 && msg.ID[0] != '{' && msg.ID[0] != '['
 }
 
-// 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 {
-	closer sync.Once                 // close closed channel once
-	closed chan interface{}          // closed on Close
-	decMu  sync.Mutex                // guards the decoder
-	decode func(v interface{}) error // decoder to allow multiple transports
-	encMu  sync.Mutex                // guards the encoder
-	encode func(v interface{}) error // encoder to allow multiple transports
-	rw     io.ReadWriteCloser        // connection
+func (msg *jsonrpcMessage) isSubscribe() bool {
+	return strings.HasSuffix(msg.Method, subscribeMethodSuffix)
+}
+
+func (msg *jsonrpcMessage) isUnsubscribe() bool {
+	return strings.HasSuffix(msg.Method, unsubscribeMethodSuffix)
+}
+
+func (msg *jsonrpcMessage) namespace() string {
+	elem := strings.SplitN(msg.Method, serviceMethodSeparator, 2)
+	return elem[0]
+}
+
+func (msg *jsonrpcMessage) String() string {
+	b, _ := json.Marshal(msg)
+	return string(b)
+}
+
+func (msg *jsonrpcMessage) errorResponse(err error) *jsonrpcMessage {
+	resp := errorMessage(err)
+	resp.ID = msg.ID
+	return resp
+}
+
+func (msg *jsonrpcMessage) response(result interface{}) *jsonrpcMessage {
+	enc, err := json.Marshal(result)
+	if err != nil {
+		// TODO: wrap with 'internal server error'
+		return msg.errorResponse(err)
+	}
+	return &jsonrpcMessage{Version: vsn, ID: msg.ID, Result: enc}
+}
+
+func errorMessage(err error) *jsonrpcMessage {
+	msg := &jsonrpcMessage{Version: vsn, ID: null, Error: &jsonError{
+		Code:    defaultErrorCode,
+		Message: err.Error(),
+	}}
+	ec, ok := err.(Error)
+	if ok {
+		msg.Error.Code = ec.ErrorCode()
+	}
+	return msg
+}
+
+type jsonError struct {
+	Code    int         `json:"code"`
+	Message string      `json:"message"`
+	Data    interface{} `json:"data,omitempty"`
 }
 
 func (err *jsonError) Error() string {
@@ -96,268 +135,196 @@ func (err *jsonError) ErrorCode() int {
 	return err.Code
 }
 
+// Conn is a subset of the methods of net.Conn which are sufficient for ServerCodec.
+type Conn interface {
+	io.ReadWriteCloser
+	SetWriteDeadline(time.Time) error
+}
+
+// ConnRemoteAddr wraps the RemoteAddr operation, which returns a description
+// of the peer address of a connection. If a Conn also implements ConnRemoteAddr, this
+// description is used in log messages.
+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 {
+	remoteAddr string
+	closer     sync.Once                 // close closed channel once
+	closed     chan interface{}          // closed on Close
+	decode     func(v interface{}) error // decoder to allow multiple transports
+	encMu      sync.Mutex                // guards the encoder
+	encode     func(v interface{}) error // encoder to allow multiple transports
+	conn       Conn
+}
+
 // NewCodec creates a new RPC server codec with support for JSON-RPC 2.0 based
 // on explicitly given encoding and decoding methods.
-func NewCodec(rwc io.ReadWriteCloser, encode, decode func(v interface{}) error) ServerCodec {
-	return &jsonCodec{
+func NewCodec(conn Conn, encode, decode func(v interface{}) error) ServerCodec {
+	codec := &jsonCodec{
 		closed: make(chan interface{}),
 		encode: encode,
 		decode: decode,
-		rw:     rwc,
+		conn:   conn,
 	}
+	if ra, ok := conn.(ConnRemoteAddr); ok {
+		codec.remoteAddr = ra.RemoteAddr()
+	}
+	return codec
 }
 
 // NewJSONCodec creates a new RPC server codec with support for JSON-RPC 2.0.
-func NewJSONCodec(rwc io.ReadWriteCloser) ServerCodec {
-	enc := json.NewEncoder(rwc)
-	dec := json.NewDecoder(rwc)
+func NewJSONCodec(conn Conn) ServerCodec {
+	enc := json.NewEncoder(conn)
+	dec := json.NewDecoder(conn)
 	dec.UseNumber()
+	return NewCodec(conn, enc.Encode, dec.Decode)
+}
 
-	return &jsonCodec{
-		closed: make(chan interface{}),
-		encode: enc.Encode,
-		decode: dec.Decode,
-		rw:     rwc,
-	}
+func (c *jsonCodec) RemoteAddr() string {
+	return c.remoteAddr
 }
 
-// isBatch returns true when the first non-whitespace characters is '['
-func isBatch(msg json.RawMessage) bool {
-	for _, c := range msg {
-		// skip insignificant whitespace (http://www.ietf.org/rfc/rfc4627.txt)
-		if c == 0x20 || c == 0x09 || c == 0x0a || c == 0x0d {
-			continue
-		}
-		return c == '['
+func (c *jsonCodec) Read() (msg []*jsonrpcMessage, batch bool, err error) {
+	// Decode the next JSON object in the input stream.
+	// This verifies basic syntax, etc.
+	var rawmsg json.RawMessage
+	if err := c.decode(&rawmsg); err != nil {
+		return nil, false, err
 	}
-	return false
+	msg, batch = parseMessage(rawmsg)
+	return msg, batch, nil
 }
 
-// ReadRequestHeaders will read new requests without parsing the arguments. It will
-// return a collection of requests, an indication if these requests are in batch
-// form or an error when the incoming message could not be read/parsed.
-func (c *jsonCodec) ReadRequestHeaders() ([]rpcRequest, bool, Error) {
-	c.decMu.Lock()
-	defer c.decMu.Unlock()
+// Write sends a message to client.
+func (c *jsonCodec) Write(ctx context.Context, v interface{}) error {
+	c.encMu.Lock()
+	defer c.encMu.Unlock()
 
-	var incomingMsg json.RawMessage
-	if err := c.decode(&incomingMsg); err != nil {
-		return nil, false, &invalidRequestError{err.Error()}
-	}
-	if isBatch(incomingMsg) {
-		return parseBatchRequest(incomingMsg)
+	deadline, ok := ctx.Deadline()
+	if !ok {
+		deadline = time.Now().Add(defaultWriteTimeout)
 	}
-	return parseRequest(incomingMsg)
+	c.conn.SetWriteDeadline(deadline)
+	return c.encode(v)
 }
 
-// checkReqId returns an error when the given reqId isn't valid for RPC method calls.
-// valid id's are strings, numbers or null
-func checkReqId(reqId json.RawMessage) error {
-	if len(reqId) == 0 {
-		return fmt.Errorf("missing request id")
-	}
-	if _, err := strconv.ParseFloat(string(reqId), 64); err == nil {
-		return nil
-	}
-	var str string
-	if err := json.Unmarshal(reqId, &str); err == nil {
-		return nil
-	}
-	return fmt.Errorf("invalid request id")
+// Close the underlying connection
+func (c *jsonCodec) Close() {
+	c.closer.Do(func() {
+		close(c.closed)
+		c.conn.Close()
+	})
 }
 
-// parseRequest will parse a single request from the given RawMessage. It will return
-// the parsed request, an indication if the request was a batch or an error when
-// the request could not be parsed.
-func parseRequest(incomingMsg json.RawMessage) ([]rpcRequest, bool, Error) {
-	var in jsonRequest
-	if err := json.Unmarshal(incomingMsg, &in); err != nil {
-		return nil, false, &invalidMessageError{err.Error()}
-	}
-
-	if err := checkReqId(in.Id); err != nil {
-		return nil, false, &invalidMessageError{err.Error()}
-	}
-
-	// subscribe are special, they will always use `subscribeMethod` as first param in the payload
-	if strings.HasSuffix(in.Method, subscribeMethodSuffix) {
-		reqs := []rpcRequest{{id: &in.Id, isPubSub: true}}
-		if len(in.Payload) > 0 {
-			// first param must be subscription name
-			var subscribeMethod [1]string
-			if err := json.Unmarshal(in.Payload, &subscribeMethod); err != nil {
-				log.Debug(fmt.Sprintf("Unable to parse subscription method: %v\n", err))
-				return nil, false, &invalidRequestError{"Unable to parse subscription request"}
-			}
-
-			reqs[0].service, reqs[0].method = strings.TrimSuffix(in.Method, subscribeMethodSuffix), subscribeMethod[0]
-			reqs[0].params = in.Payload
-			return reqs, false, nil
-		}
-		return nil, false, &invalidRequestError{"Unable to parse subscription request"}
-	}
-
-	if strings.HasSuffix(in.Method, unsubscribeMethodSuffix) {
-		return []rpcRequest{{id: &in.Id, isPubSub: true,
-			method: in.Method, params: in.Payload}}, false, nil
-	}
+// Closed returns a channel which will be closed when Close is called
+func (c *jsonCodec) Closed() <-chan interface{} {
+	return c.closed
+}
 
-	elems := strings.Split(in.Method, serviceMethodSeparator)
-	if len(elems) != 2 {
-		return nil, false, &methodNotFoundError{in.Method, ""}
+// parseMessage parses raw bytes as a (batch of) JSON-RPC message(s). There are no error
+// checks in this function because the raw message has already been syntax-checked when it
+// is called. Any non-JSON-RPC messages in the input return the zero value of
+// jsonrpcMessage.
+func parseMessage(raw json.RawMessage) ([]*jsonrpcMessage, bool) {
+	if !isBatch(raw) {
+		msgs := []*jsonrpcMessage{{}}
+		json.Unmarshal(raw, &msgs[0])
+		return msgs, false
 	}
-
-	// regular RPC call
-	if len(in.Payload) == 0 {
-		return []rpcRequest{{service: elems[0], method: elems[1], id: &in.Id}}, false, nil
+	dec := json.NewDecoder(bytes.NewReader(raw))
+	dec.Token() // skip '['
+	var msgs []*jsonrpcMessage
+	for dec.More() {
+		msgs = append(msgs, new(jsonrpcMessage))
+		dec.Decode(&msgs[len(msgs)-1])
 	}
-
-	return []rpcRequest{{service: elems[0], method: elems[1], id: &in.Id, params: in.Payload}}, false, nil
+	return msgs, true
 }
 
-// parseBatchRequest will parse a batch request into a collection of requests from the given RawMessage, an indication
-// if the request was a batch or an error when the request could not be read.
-func parseBatchRequest(incomingMsg json.RawMessage) ([]rpcRequest, bool, Error) {
-	var in []jsonRequest
-	if err := json.Unmarshal(incomingMsg, &in); err != nil {
-		return nil, false, &invalidMessageError{err.Error()}
-	}
-
-	requests := make([]rpcRequest, len(in))
-	for i, r := range in {
-		if err := checkReqId(r.Id); err != nil {
-			return nil, false, &invalidMessageError{err.Error()}
-		}
-
-		id := &in[i].Id
-
-		// subscribe are special, they will always use `subscriptionMethod` as first param in the payload
-		if strings.HasSuffix(r.Method, subscribeMethodSuffix) {
-			requests[i] = rpcRequest{id: id, isPubSub: true}
-			if len(r.Payload) > 0 {
-				// first param must be subscription name
-				var subscribeMethod [1]string
-				if err := json.Unmarshal(r.Payload, &subscribeMethod); err != nil {
-					log.Debug(fmt.Sprintf("Unable to parse subscription method: %v\n", err))
-					return nil, false, &invalidRequestError{"Unable to parse subscription request"}
-				}
-
-				requests[i].service, requests[i].method = strings.TrimSuffix(r.Method, subscribeMethodSuffix), subscribeMethod[0]
-				requests[i].params = r.Payload
-				continue
-			}
-
-			return nil, true, &invalidRequestError{"Unable to parse (un)subscribe request arguments"}
-		}
-
-		if strings.HasSuffix(r.Method, unsubscribeMethodSuffix) {
-			requests[i] = rpcRequest{id: id, isPubSub: true, method: r.Method, params: r.Payload}
+// isBatch returns true when the first non-whitespace characters is '['
+func isBatch(raw json.RawMessage) bool {
+	for _, c := range raw {
+		// skip insignificant whitespace (http://www.ietf.org/rfc/rfc4627.txt)
+		if c == 0x20 || c == 0x09 || c == 0x0a || c == 0x0d {
 			continue
 		}
-
-		if len(r.Payload) == 0 {
-			requests[i] = rpcRequest{id: id, params: nil}
-		} else {
-			requests[i] = rpcRequest{id: id, params: r.Payload}
-		}
-		if elem := strings.Split(r.Method, serviceMethodSeparator); len(elem) == 2 {
-			requests[i].service, requests[i].method = elem[0], elem[1]
-		} else {
-			requests[i].err = &methodNotFoundError{r.Method, ""}
-		}
-	}
-
-	return requests, true, nil
-}
-
-// ParseRequestArguments tries to parse the given params (json.RawMessage) with the given
-// types. It returns the parsed values or an error when the parsing failed.
-func (c *jsonCodec) ParseRequestArguments(argTypes []reflect.Type, params interface{}) ([]reflect.Value, Error) {
-	if args, ok := params.(json.RawMessage); !ok {
-		return nil, &invalidParamsError{"Invalid params supplied"}
-	} else {
-		return parsePositionalArguments(args, argTypes)
+		return c == '['
 	}
+	return false
 }
 
 // parsePositionalArguments tries to parse the given args to an array of values with the
 // given types. It returns the parsed values or an error when the args could not be
 // parsed. Missing optional arguments are returned as reflect.Zero values.
-func parsePositionalArguments(rawArgs json.RawMessage, types []reflect.Type) ([]reflect.Value, Error) {
-	// Read beginning of the args array.
+func parsePositionalArguments(rawArgs json.RawMessage, types []reflect.Type) ([]reflect.Value, error) {
 	dec := json.NewDecoder(bytes.NewReader(rawArgs))
-	if tok, _ := dec.Token(); tok != json.Delim('[') {
-		return nil, &invalidParamsError{"non-array args"}
+	var args []reflect.Value
+	tok, err := dec.Token()
+	switch {
+	case err == io.EOF || tok == nil && err == nil:
+		// "params" is optional and may be empty. Also allow "params":null even though it's
+		// not in the spec because our own client used to send it.
+	case err != nil:
+		return nil, err
+	case tok == json.Delim('['):
+		// Read argument array.
+		if args, err = parseArgumentArray(dec, types); err != nil {
+			return nil, err
+		}
+	default:
+		return nil, errors.New("non-array args")
 	}
-	// Read args.
+	// Set any missing args to nil.
+	for i := len(args); i < len(types); i++ {
+		if types[i].Kind() != reflect.Ptr {
+			return nil, fmt.Errorf("missing value for required argument %d", i)
+		}
+		args = append(args, reflect.Zero(types[i]))
+	}
+	return args, nil
+}
+
+func parseArgumentArray(dec *json.Decoder, types []reflect.Type) ([]reflect.Value, error) {
 	args := make([]reflect.Value, 0, len(types))
 	for i := 0; dec.More(); i++ {
 		if i >= len(types) {
-			return nil, &invalidParamsError{fmt.Sprintf("too many arguments, want at most %d", len(types))}
+			return args, fmt.Errorf("too many arguments, want at most %d", len(types))
 		}
 		argval := reflect.New(types[i])
 		if err := dec.Decode(argval.Interface()); err != nil {
-			return nil, &invalidParamsError{fmt.Sprintf("invalid argument %d: %v", i, err)}
+			return args, fmt.Errorf("invalid argument %d: %v", i, err)
 		}
 		if argval.IsNil() && types[i].Kind() != reflect.Ptr {
-			return nil, &invalidParamsError{fmt.Sprintf("missing value for required argument %d", i)}
+			return args, fmt.Errorf("missing value for required argument %d", i)
 		}
 		args = append(args, argval.Elem())
 	}
 	// Read end of args array.
-	if _, err := dec.Token(); err != nil {
-		return nil, &invalidParamsError{err.Error()}
-	}
-	// Set any missing args to nil.
-	for i := len(args); i < len(types); i++ {
-		if types[i].Kind() != reflect.Ptr {
-			return nil, &invalidParamsError{fmt.Sprintf("missing value for required argument %d", i)}
-		}
-		args = append(args, reflect.Zero(types[i]))
-	}
-	return args, nil
-}
-
-// CreateResponse will create a JSON-RPC success response with the given id and reply as result.
-func (c *jsonCodec) CreateResponse(id interface{}, reply interface{}) interface{} {
-	return &jsonSuccessResponse{Version: jsonrpcVersion, Id: id, Result: reply}
-}
-
-// CreateErrorResponse will create a JSON-RPC error response with the given id and error.
-func (c *jsonCodec) CreateErrorResponse(id interface{}, err Error) interface{} {
-	return &jsonErrResponse{Version: jsonrpcVersion, Id: id, Error: jsonError{Code: err.ErrorCode(), Message: err.Error()}}
-}
-
-// CreateErrorResponseWithInfo will create a JSON-RPC error response with the given id and error.
-// info is optional and contains additional information about the error. When an empty string is passed it is ignored.
-func (c *jsonCodec) CreateErrorResponseWithInfo(id interface{}, err Error, info interface{}) interface{} {
-	return &jsonErrResponse{Version: jsonrpcVersion, Id: id,
-		Error: jsonError{Code: err.ErrorCode(), Message: err.Error(), Data: info}}
-}
-
-// CreateNotification will create a JSON-RPC notification with the given subscription id and event as params.
-func (c *jsonCodec) CreateNotification(subid, namespace string, event interface{}) interface{} {
-	return &jsonNotification{Version: jsonrpcVersion, Method: namespace + notificationMethodSuffix,
-		Params: jsonSubscription{Subscription: subid, Result: event}}
-}
-
-// Write message to client
-func (c *jsonCodec) Write(res interface{}) error {
-	c.encMu.Lock()
-	defer c.encMu.Unlock()
-
-	return c.encode(res)
+	_, err := dec.Token()
+	return args, err
 }
 
-// Close the underlying connection
-func (c *jsonCodec) Close() {
-	c.closer.Do(func() {
-		close(c.closed)
-		c.rw.Close()
-	})
-}
-
-// Closed returns a channel which will be closed when Close is called
-func (c *jsonCodec) Closed() <-chan interface{} {
-	return c.closed
+// parseSubscriptionName extracts the subscription name from an encoded argument array.
+func parseSubscriptionName(rawArgs json.RawMessage) (string, error) {
+	dec := json.NewDecoder(bytes.NewReader(rawArgs))
+	if tok, _ := dec.Token(); tok != json.Delim('[') {
+		return "", errors.New("non-array args")
+	}
+	v, _ := dec.Token()
+	method, ok := v.(string)
+	if !ok {
+		return "", errors.New("expected subscription name as first argument")
+	}
+	return method, nil
 }

rpc/json_test.go

@@ -1,178 +0,0 @@
-// Copyright 2015 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 <http://www.gnu.org/licenses/>.
-
-package rpc
-
-import (
-	"bufio"
-	"bytes"
-	"encoding/json"
-	"reflect"
-	"strconv"
-	"testing"
-)
-
-type RWC struct {
-	*bufio.ReadWriter
-}
-
-func (rwc *RWC) Close() error {
-	return nil
-}
-
-func TestJSONRequestParsing(t *testing.T) {
-	server := NewServer()
-	service := new(Service)
-
-	if err := server.RegisterName("calc", service); err != nil {
-		t.Fatalf("%v", err)
-	}
-
-	req := bytes.NewBufferString(`{"id": 1234, "jsonrpc": "2.0", "method": "calc_add", "params": [11, 22]}`)
-	var str string
-	reply := bytes.NewBufferString(str)
-	rw := &RWC{bufio.NewReadWriter(bufio.NewReader(req), bufio.NewWriter(reply))}
-
-	codec := NewJSONCodec(rw)
-
-	requests, batch, err := codec.ReadRequestHeaders()
-	if err != nil {
-		t.Fatalf("%v", err)
-	}
-
-	if batch {
-		t.Fatalf("Request isn't a batch")
-	}
-
-	if len(requests) != 1 {
-		t.Fatalf("Expected 1 request but got %d requests - %v", len(requests), requests)
-	}
-
-	if requests[0].service != "calc" {
-		t.Fatalf("Expected service 'calc' but got '%s'", requests[0].service)
-	}
-
-	if requests[0].method != "add" {
-		t.Fatalf("Expected method 'Add' but got '%s'", requests[0].method)
-	}
-
-	if rawId, ok := requests[0].id.(*json.RawMessage); ok {
-		id, e := strconv.ParseInt(string(*rawId), 0, 64)
-		if e != nil {
-			t.Fatalf("%v", e)
-		}
-		if id != 1234 {
-			t.Fatalf("Expected id 1234 but got %d", id)
-		}
-	} else {
-		t.Fatalf("invalid request, expected *json.RawMesage got %T", requests[0].id)
-	}
-
-	var arg int
-	args := []reflect.Type{reflect.TypeOf(arg), reflect.TypeOf(arg)}
-
-	v, err := codec.ParseRequestArguments(args, requests[0].params)
-	if err != nil {
-		t.Fatalf("%v", err)
-	}
-
-	if len(v) != 2 {
-		t.Fatalf("Expected 2 argument values, got %d", len(v))
-	}
-
-	if v[0].Int() != 11 || v[1].Int() != 22 {
-		t.Fatalf("expected %d == 11 && %d == 22", v[0].Int(), v[1].Int())
-	}
-}
-
-func TestJSONRequestParamsParsing(t *testing.T) {
-
-	var (
-		stringT = reflect.TypeOf("")
-		intT    = reflect.TypeOf(0)
-		intPtrT = reflect.TypeOf(new(int))
-
-		stringV = reflect.ValueOf("abc")
-		i       = 1
-		intV    = reflect.ValueOf(i)
-		intPtrV = reflect.ValueOf(&i)
-	)
-
-	var validTests = []struct {
-		input    string
-		argTypes []reflect.Type
-		expected []reflect.Value
-	}{
-		{`[]`, []reflect.Type{}, []reflect.Value{}},
-		{`[]`, []reflect.Type{intPtrT}, []reflect.Value{intPtrV}},
-		{`[1]`, []reflect.Type{intT}, []reflect.Value{intV}},
-		{`[1,"abc"]`, []reflect.Type{intT, stringT}, []reflect.Value{intV, stringV}},
-		{`[null]`, []reflect.Type{intPtrT}, []reflect.Value{intPtrV}},
-		{`[null,"abc"]`, []reflect.Type{intPtrT, stringT, intPtrT}, []reflect.Value{intPtrV, stringV, intPtrV}},
-		{`[null,"abc",null]`, []reflect.Type{intPtrT, stringT, intPtrT}, []reflect.Value{intPtrV, stringV, intPtrV}},
-	}
-
-	codec := jsonCodec{}
-
-	for _, test := range validTests {
-		params := (json.RawMessage)([]byte(test.input))
-		args, err := codec.ParseRequestArguments(test.argTypes, params)
-
-		if err != nil {
-			t.Fatal(err)
-		}
-
-		var match []interface{}
-		json.Unmarshal([]byte(test.input), &match)
-
-		if len(args) != len(test.argTypes) {
-			t.Fatalf("expected %d parsed args, got %d", len(test.argTypes), len(args))
-		}
-
-		for i, arg := range args {
-			expected := test.expected[i]
-
-			if arg.Kind() != expected.Kind() {
-				t.Errorf("expected type for param %d in %s", i, test.input)
-			}
-
-			if arg.Kind() == reflect.Int && arg.Int() != expected.Int() {
-				t.Errorf("expected int(%d), got int(%d) in %s", expected.Int(), arg.Int(), test.input)
-			}
-
-			if arg.Kind() == reflect.String && arg.String() != expected.String() {
-				t.Errorf("expected string(%s), got string(%s) in %s", expected.String(), arg.String(), test.input)
-			}
-		}
-	}
-
-	var invalidTests = []struct {
-		input    string
-		argTypes []reflect.Type
-	}{
-		{`[]`, []reflect.Type{intT}},
-		{`[null]`, []reflect.Type{intT}},
-		{`[1]`, []reflect.Type{stringT}},
-		{`[1,2]`, []reflect.Type{stringT}},
-		{`["abc", null]`, []reflect.Type{stringT, intT}},
-	}
-
-	for i, test := range invalidTests {
-		if _, err := codec.ParseRequestArguments(test.argTypes, test.input); err == nil {
-			t.Errorf("expected test %d - %s to fail", i, test.input)
-		}
-	}
-}

rpc/server.go

@@ -18,11 +18,7 @@ package rpc
 
 import (
 	"context"
-	"fmt"
-	"reflect"
-	"runtime"
-	"strings"
-	"sync"
+	"io"
 	"sync/atomic"
 
 	mapset "github.com/deckarep/golang-set"
@@ -31,7 +27,9 @@ import (
 
 const MetadataApi = "rpc"
 
-// CodecOption specifies which type of messages this codec supports
+// CodecOption specifies which type of messages a codec supports.
+//
+// Deprecated: this option is no longer honored by Server.
 type CodecOption int
 
 const (
@@ -42,194 +40,87 @@ const (
 	OptionSubscriptions = 1 << iota // support pub sub
 )
 
-// NewServer will create a new server instance with no registered handlers.
-func NewServer() *Server {
-	server := &Server{
-		services: make(serviceRegistry),
-		codecs:   mapset.NewSet(),
-		run:      1,
-	}
+// Server is an RPC server.
+type Server struct {
+	services serviceRegistry
+	idgen    func() ID
+	run      int32
+	codecs   mapset.Set
+}
 
-	// register a default service which will provide meta information about the RPC service such as the services and
-	// methods it offers.
+// NewServer creates a new server instance with no registered handlers.
+func NewServer() *Server {
+	server := &Server{idgen: randomIDGenerator(), codecs: mapset.NewSet(), run: 1}
+	// Register the default service providing meta information about the RPC service such
+	// as the services and methods it offers.
 	rpcService := &RPCService{server}
 	server.RegisterName(MetadataApi, rpcService)
-
 	return server
 }
 
-// RPCService gives meta information about the server.
-// e.g. gives information about the loaded modules.
-type RPCService struct {
-	server *Server
-}
-
-// Modules returns the list of RPC services with their version number
-func (s *RPCService) Modules() map[string]string {
-	modules := make(map[string]string)
-	for name := range s.server.services {
-		modules[name] = "1.0"
-	}
-	return modules
+// RegisterName creates a service for the given receiver type under the given name. When no
+// methods on the given receiver match the criteria to be either a RPC method or a
+// subscription an error is returned. Otherwise a new service is created and added to the
+// service collection this server provides to clients.
+func (s *Server) RegisterName(name string, receiver interface{}) error {
+	return s.services.registerName(name, receiver)
 }
 
-// RegisterName will create a service for the given rcvr type under the given name. When no methods on the given rcvr
-// match the criteria to be either a RPC method or a subscription an error is returned. Otherwise a new service is
-// created and added to the service collection this server instance serves.
-func (s *Server) RegisterName(name string, rcvr interface{}) error {
-	if s.services == nil {
-		s.services = make(serviceRegistry)
-	}
-
-	svc := new(service)
-	svc.typ = reflect.TypeOf(rcvr)
-	rcvrVal := reflect.ValueOf(rcvr)
-
-	if name == "" {
-		return fmt.Errorf("no service name for type %s", svc.typ.String())
-	}
-	if !isExported(reflect.Indirect(rcvrVal).Type().Name()) {
-		return fmt.Errorf("%s is not exported", reflect.Indirect(rcvrVal).Type().Name())
-	}
-
-	methods, subscriptions := suitableCallbacks(rcvrVal, svc.typ)
+// ServeCodec reads incoming requests from codec, calls the appropriate callback and writes
+// the response back using the given codec. It will block until the codec is closed or the
+// server is stopped. In either case the codec is closed.
+//
+// Note that codec options are no longer supported.
+func (s *Server) ServeCodec(codec ServerCodec, options CodecOption) {
+	defer codec.Close()
 
-	if len(methods) == 0 && len(subscriptions) == 0 {
-		return fmt.Errorf("Service %T doesn't have any suitable methods/subscriptions to expose", rcvr)
+	// Don't serve if server is stopped.
+	if atomic.LoadInt32(&s.run) == 0 {
+		return
 	}
 
-	// already a previous service register under given name, merge methods/subscriptions
-	if regsvc, present := s.services[name]; present {
-		for _, m := range methods {
-			regsvc.callbacks[formatName(m.method.Name)] = m
-		}
-		for _, s := range subscriptions {
-			regsvc.subscriptions[formatName(s.method.Name)] = s
-		}
-		return nil
-	}
-
-	svc.name = name
-	svc.callbacks, svc.subscriptions = methods, subscriptions
+	// Add the codec to the set so it can be closed by Stop.
+	s.codecs.Add(codec)
+	defer s.codecs.Remove(codec)
 
-	s.services[svc.name] = svc
-	return nil
+	c := initClient(codec, s.idgen, &s.services)
+	<-codec.Closed()
+	c.Close()
 }
 
-// serveRequest will reads requests from the codec, calls the RPC callback and
-// writes the response to the given codec.
-//
-// If singleShot is true it will process a single request, otherwise it will handle
-// requests until the codec returns an error when reading a request (in most cases
-// an EOF). It executes requests in parallel when singleShot is false.
-func (s *Server) serveRequest(ctx context.Context, codec ServerCodec, singleShot bool, options CodecOption) error {
-	var pend sync.WaitGroup
-
-	defer func() {
-		if err := recover(); err != nil {
-			const size = 64 << 10
-			buf := make([]byte, size)
-			buf = buf[:runtime.Stack(buf, false)]
-			log.Error(string(buf))
-		}
-		s.codecsMu.Lock()
-		s.codecs.Remove(codec)
-		s.codecsMu.Unlock()
-	}()
-
-	//	ctx, cancel := context.WithCancel(context.Background())
-	ctx, cancel := context.WithCancel(ctx)
-	defer cancel()
-
-	// if the codec supports notification include a notifier that callbacks can use
-	// to send notification to clients. It is tied to the codec/connection. If the
-	// connection is closed the notifier will stop and cancels all active subscriptions.
-	if options&OptionSubscriptions == OptionSubscriptions {
-		ctx = context.WithValue(ctx, notifierKey{}, newNotifier(codec))
-	}
-	s.codecsMu.Lock()
-	if atomic.LoadInt32(&s.run) != 1 { // server stopped
-		s.codecsMu.Unlock()
-		return &shutdownError{}
+// serveSingleRequest reads and processes a single RPC request from the given codec. This
+// is used to serve HTTP connections. Subscriptions and reverse calls are not allowed in
+// this mode.
+func (s *Server) serveSingleRequest(ctx context.Context, codec ServerCodec) {
+	// Don't serve if server is stopped.
+	if atomic.LoadInt32(&s.run) == 0 {
+		return
 	}
-	s.codecs.Add(codec)
-	s.codecsMu.Unlock()
 
-	// test if the server is ordered to stop
-	for atomic.LoadInt32(&s.run) == 1 {
-		reqs, batch, err := s.readRequest(codec)
-		if err != nil {
-			// If a parsing error occurred, send an error
-			if err.Error() != "EOF" {
-				log.Debug(fmt.Sprintf("read error %v\n", err))
-				codec.Write(codec.CreateErrorResponse(nil, err))
-			}
-			// Error or end of stream, wait for requests and tear down
-			pend.Wait()
-			return nil
-		}
+	h := newHandler(ctx, codec, s.idgen, &s.services)
+	h.allowSubscribe = false
+	defer h.close(io.EOF, nil)
 
-		// check if server is ordered to shutdown and return an error
-		// telling the client that his request failed.
-		if atomic.LoadInt32(&s.run) != 1 {
-			err = &shutdownError{}
-			if batch {
-				resps := make([]interface{}, len(reqs))
-				for i, r := range reqs {
-					resps[i] = codec.CreateErrorResponse(&r.id, err)
-				}
-				codec.Write(resps)
-			} else {
-				codec.Write(codec.CreateErrorResponse(&reqs[0].id, err))
-			}
-			return nil
-		}
-		// If a single shot request is executing, run and return immediately
-		if singleShot {
-			if batch {
-				s.execBatch(ctx, codec, reqs)
-			} else {
-				s.exec(ctx, codec, reqs[0])
-			}
-			return nil
+	reqs, batch, err := codec.Read()
+	if err != nil {
+		if err != io.EOF {
+			codec.Write(ctx, errorMessage(&invalidMessageError{"parse error"}))
 		}
-		// For multi-shot connections, start a goroutine to serve and loop back
-		pend.Add(1)
-
-		go func(reqs []*serverRequest, batch bool) {
-			defer pend.Done()
-			if batch {
-				s.execBatch(ctx, codec, reqs)
-			} else {
-				s.exec(ctx, codec, reqs[0])
-			}
-		}(reqs, batch)
+		return
+	}
+	if batch {
+		h.handleBatch(reqs)
+	} else {
+		h.handleMsg(reqs[0])
 	}
-	return nil
-}
-
-// ServeCodec reads incoming requests from codec, calls the appropriate callback and writes the
-// response back using the given codec. It will block until the codec is closed or the server is
-// stopped. In either case the codec is closed.
-func (s *Server) ServeCodec(codec ServerCodec, options CodecOption) {
-	defer codec.Close()
-	s.serveRequest(context.Background(), codec, false, options)
-}
-
-// ServeSingleRequest reads and processes a single RPC request from the given codec. It will not
-// close the codec unless a non-recoverable error has occurred. Note, this method will return after
-// a single request has been processed!
-func (s *Server) ServeSingleRequest(ctx context.Context, codec ServerCodec, options CodecOption) {
-	s.serveRequest(ctx, codec, true, options)
 }
 
-// Stop will stop reading new requests, wait for stopPendingRequestTimeout to allow pending requests to finish,
-// close all codecs which will cancel pending requests/subscriptions.
+// Stop stops reading new requests, waits for stopPendingRequestTimeout to allow pending
+// requests to finish, then closes all codecs which will cancel pending requests and
+// subscriptions.
 func (s *Server) Stop() {
 	if atomic.CompareAndSwapInt32(&s.run, 1, 0) {
-		log.Debug("RPC Server shutdown initiatied")
-		s.codecsMu.Lock()
-		defer s.codecsMu.Unlock()
+		log.Debug("RPC server shutting down")
 		s.codecs.Each(func(c interface{}) bool {
 			c.(ServerCodec).Close()
 			return true
@@ -237,206 +128,20 @@ func (s *Server) Stop() {
 	}
 }
 
-// createSubscription will call the subscription callback and returns the subscription id or error.
-func (s *Server) createSubscription(ctx context.Context, c ServerCodec, req *serverRequest) (ID, error) {
-	// subscription have as first argument the context following optional arguments
-	args := []reflect.Value{req.callb.rcvr, reflect.ValueOf(ctx)}
-	args = append(args, req.args...)
-	reply := req.callb.method.Func.Call(args)
-
-	if !reply[1].IsNil() { // subscription creation failed
-		return "", reply[1].Interface().(error)
-	}
-
-	return reply[0].Interface().(*Subscription).ID, nil
-}
-
-// handle executes a request and returns the response from the callback.
-func (s *Server) handle(ctx context.Context, codec ServerCodec, req *serverRequest) (interface{}, func()) {
-	if req.err != nil {
-		return codec.CreateErrorResponse(&req.id, req.err), nil
-	}
-
-	if req.isUnsubscribe { // cancel subscription, first param must be the subscription id
-		if len(req.args) >= 1 && req.args[0].Kind() == reflect.String {
-			notifier, supported := NotifierFromContext(ctx)
-			if !supported { // interface doesn't support subscriptions (e.g. http)
-				return codec.CreateErrorResponse(&req.id, &callbackError{ErrNotificationsUnsupported.Error()}), nil
-			}
-
-			subid := ID(req.args[0].String())
-			if err := notifier.unsubscribe(subid); err != nil {
-				return codec.CreateErrorResponse(&req.id, &callbackError{err.Error()}), nil
-			}
-
-			return codec.CreateResponse(req.id, true), nil
-		}
-		return codec.CreateErrorResponse(&req.id, &invalidParamsError{"Expected subscription id as first argument"}), nil
-	}
-
-	if req.callb.isSubscribe {
-		subid, err := s.createSubscription(ctx, codec, req)
-		if err != nil {
-			return codec.CreateErrorResponse(&req.id, &callbackError{err.Error()}), nil
-		}
-
-		// active the subscription after the sub id was successfully sent to the client
-		activateSub := func() {
-			notifier, _ := NotifierFromContext(ctx)
-			notifier.activate(subid, req.svcname)
-		}
-
-		return codec.CreateResponse(req.id, subid), activateSub
-	}
-
-	// regular RPC call, prepare arguments
-	if len(req.args) != len(req.callb.argTypes) {
-		rpcErr := &invalidParamsError{fmt.Sprintf("%s%s%s expects %d parameters, got %d",
-			req.svcname, serviceMethodSeparator, req.callb.method.Name,
-			len(req.callb.argTypes), len(req.args))}
-		return codec.CreateErrorResponse(&req.id, rpcErr), nil
-	}
-
-	arguments := []reflect.Value{req.callb.rcvr}
-	if req.callb.hasCtx {
-		arguments = append(arguments, reflect.ValueOf(ctx))
-	}
-	if len(req.args) > 0 {
-		arguments = append(arguments, req.args...)
-	}
-
-	// execute RPC method and return result
-	reply := req.callb.method.Func.Call(arguments)
-	if len(reply) == 0 {
-		return codec.CreateResponse(req.id, nil), nil
-	}
-	if req.callb.errPos >= 0 { // test if method returned an error
-		if !reply[req.callb.errPos].IsNil() {
-			e := reply[req.callb.errPos].Interface().(error)
-			res := codec.CreateErrorResponse(&req.id, &callbackError{e.Error()})
-			return res, nil
-		}
-	}
-	return codec.CreateResponse(req.id, reply[0].Interface()), nil
-}
-
-// exec executes the given request and writes the result back using the codec.
-func (s *Server) exec(ctx context.Context, codec ServerCodec, req *serverRequest) {
-	var response interface{}
-	var callback func()
-	if req.err != nil {
-		response = codec.CreateErrorResponse(&req.id, req.err)
-	} else {
-		response, callback = s.handle(ctx, codec, req)
-	}
-
-	if err := codec.Write(response); err != nil {
-		log.Error(fmt.Sprintf("%v\n", err))
-		codec.Close()
-	}
-
-	// when request was a subscribe request this allows these subscriptions to be actived
-	if callback != nil {
-		callback()
-	}
-}
-
-// execBatch executes the given requests and writes the result back using the codec.
-// It will only write the response back when the last request is processed.
-func (s *Server) execBatch(ctx context.Context, codec ServerCodec, requests []*serverRequest) {
-	responses := make([]interface{}, len(requests))
-	var callbacks []func()
-	for i, req := range requests {
-		if req.err != nil {
-			responses[i] = codec.CreateErrorResponse(&req.id, req.err)
-		} else {
-			var callback func()
-			if responses[i], callback = s.handle(ctx, codec, req); callback != nil {
-				callbacks = append(callbacks, callback)
-			}
-		}
-	}
-
-	if err := codec.Write(responses); err != nil {
-		log.Error(fmt.Sprintf("%v\n", err))
-		codec.Close()
-	}
-
-	// when request holds one of more subscribe requests this allows these subscriptions to be activated
-	for _, c := range callbacks {
-		c()
-	}
+// RPCService gives meta information about the server.
+// e.g. gives information about the loaded modules.
+type RPCService struct {
+	server *Server
 }
 
-// readRequest requests the next (batch) request from the codec. It will return the collection
-// of requests, an indication if the request was a batch, the invalid request identifier and an
-// error when the request could not be read/parsed.
-func (s *Server) readRequest(codec ServerCodec) ([]*serverRequest, bool, Error) {
-	reqs, batch, err := codec.ReadRequestHeaders()
-	if err != nil {
-		return nil, batch, err
-	}
-
-	requests := make([]*serverRequest, len(reqs))
-
-	// verify requests
-	for i, r := range reqs {
-		var ok bool
-		var svc *service
-
-		if r.err != nil {
-			requests[i] = &serverRequest{id: r.id, err: r.err}
-			continue
-		}
-
-		if r.isPubSub && strings.HasSuffix(r.method, unsubscribeMethodSuffix) {
-			requests[i] = &serverRequest{id: r.id, isUnsubscribe: true}
-			argTypes := []reflect.Type{reflect.TypeOf("")} // expect subscription id as first arg
-			if args, err := codec.ParseRequestArguments(argTypes, r.params); err == nil {
-				requests[i].args = args
-			} else {
-				requests[i].err = &invalidParamsError{err.Error()}
-			}
-			continue
-		}
-
-		if svc, ok = s.services[r.service]; !ok { // rpc method isn't available
-			requests[i] = &serverRequest{id: r.id, err: &methodNotFoundError{r.service, r.method}}
-			continue
-		}
-
-		if r.isPubSub { // eth_subscribe, r.method contains the subscription method name
-			if callb, ok := svc.subscriptions[r.method]; ok {
-				requests[i] = &serverRequest{id: r.id, svcname: svc.name, callb: callb}
-				if r.params != nil && len(callb.argTypes) > 0 {
-					argTypes := []reflect.Type{reflect.TypeOf("")}
-					argTypes = append(argTypes, callb.argTypes...)
-					if args, err := codec.ParseRequestArguments(argTypes, r.params); err == nil {
-						requests[i].args = args[1:] // first one is service.method name which isn't an actual argument
-					} else {
-						requests[i].err = &invalidParamsError{err.Error()}
-					}
-				}
-			} else {
-				requests[i] = &serverRequest{id: r.id, err: &methodNotFoundError{r.service, r.method}}
-			}
-			continue
-		}
-
-		if callb, ok := svc.callbacks[r.method]; ok { // lookup RPC method
-			requests[i] = &serverRequest{id: r.id, svcname: svc.name, callb: callb}
-			if r.params != nil && len(callb.argTypes) > 0 {
-				if args, err := codec.ParseRequestArguments(callb.argTypes, r.params); err == nil {
-					requests[i].args = args
-				} else {
-					requests[i].err = &invalidParamsError{err.Error()}
-				}
-			}
-			continue
-		}
+// Modules returns the list of RPC services with their version number
+func (s *RPCService) Modules() map[string]string {
+	s.server.services.mu.Lock()
+	defer s.server.services.mu.Unlock()
 
-		requests[i] = &serverRequest{id: r.id, err: &methodNotFoundError{r.service, r.method}}
+	modules := make(map[string]string)
+	for name := range s.server.services.services {
+		modules[name] = "1.0"
 	}
-
-	return requests, batch, nil
+	return modules
 }

rpc/server_test.go

@@ -17,146 +17,136 @@
 package rpc
 
 import (
-	"context"
-	"encoding/json"
+	"bufio"
+	"bytes"
+	"io"
+	"io/ioutil"
 	"net"
-	"reflect"
+	"path/filepath"
+	"strings"
 	"testing"
 	"time"
 )
 
-type Service struct{}
-
-type Args struct {
-	S string
-}
-
-func (s *Service) NoArgsRets() {
-}
-
-type Result struct {
-	String string
-	Int    int
-	Args   *Args
-}
-
-func (s *Service) Echo(str string, i int, args *Args) Result {
-	return Result{str, i, args}
-}
-
-func (s *Service) EchoWithCtx(ctx context.Context, str string, i int, args *Args) Result {
-	return Result{str, i, args}
-}
-
-func (s *Service) Sleep(ctx context.Context, duration time.Duration) {
-	select {
-	case <-time.After(duration):
-	case <-ctx.Done():
-	}
-}
-
-func (s *Service) Rets() (string, error) {
-	return "", nil
-}
-
-func (s *Service) InvalidRets1() (error, string) {
-	return nil, ""
-}
-
-func (s *Service) InvalidRets2() (string, string) {
-	return "", ""
-}
-
-func (s *Service) InvalidRets3() (string, string, error) {
-	return "", "", nil
-}
-
-func (s *Service) Subscription(ctx context.Context) (*Subscription, error) {
-	return nil, nil
-}
-
 func TestServerRegisterName(t *testing.T) {
 	server := NewServer()
-	service := new(Service)
+	service := new(testService)
 
-	if err := server.RegisterName("calc", service); err != nil {
+	if err := server.RegisterName("test", service); err != nil {
 		t.Fatalf("%v", err)
 	}
 
-	if len(server.services) != 2 {
-		t.Fatalf("Expected 2 service entries, got %d", len(server.services))
+	if len(server.services.services) != 2 {
+		t.Fatalf("Expected 2 service entries, got %d", len(server.services.services))
 	}
 
-	svc, ok := server.services["calc"]
+	svc, ok := server.services.services["test"]
 	if !ok {
 		t.Fatalf("Expected service calc to be registered")
 	}
 
-	if len(svc.callbacks) != 5 {
-		t.Errorf("Expected 5 callbacks for service 'calc', got %d", len(svc.callbacks))
-	}
-
-	if len(svc.subscriptions) != 1 {
-		t.Errorf("Expected 1 subscription for service 'calc', got %d", len(svc.subscriptions))
+	wantCallbacks := 7
+	if len(svc.callbacks) != wantCallbacks {
+		t.Errorf("Expected %d callbacks for service 'service', got %d", wantCallbacks, len(svc.callbacks))
 	}
 }
 
-func testServerMethodExecution(t *testing.T, method string) {
-	server := NewServer()
-	service := new(Service)
-
-	if err := server.RegisterName("test", service); err != nil {
-		t.Fatalf("%v", err)
+func TestServer(t *testing.T) {
+	files, err := ioutil.ReadDir("testdata")
+	if err != nil {
+		t.Fatal("where'd my testdata go?")
 	}
+	for _, f := range files {
+		if f.IsDir() || strings.HasPrefix(f.Name(), ".") {
+			continue
+		}
+		path := filepath.Join("testdata", f.Name())
+		name := strings.TrimSuffix(f.Name(), filepath.Ext(f.Name()))
+		t.Run(name, func(t *testing.T) {
+			runTestScript(t, path)
+		})
+	}
+}
 
-	stringArg := "string arg"
-	intArg := 1122
-	argsArg := &Args{"abcde"}
-	params := []interface{}{stringArg, intArg, argsArg}
-
-	request := map[string]interface{}{
-		"id":      12345,
-		"method":  "test_" + method,
-		"version": "2.0",
-		"params":  params,
+func runTestScript(t *testing.T, file string) {
+	server := newTestServer()
+	content, err := ioutil.ReadFile(file)
+	if err != nil {
+		t.Fatal(err)
 	}
 
 	clientConn, serverConn := net.Pipe()
 	defer clientConn.Close()
-
-	go server.ServeCodec(NewJSONCodec(serverConn), OptionMethodInvocation)
-
-	out := json.NewEncoder(clientConn)
-	in := json.NewDecoder(clientConn)
-
-	if err := out.Encode(request); err != nil {
-		t.Fatal(err)
+	go server.ServeCodec(NewJSONCodec(serverConn), OptionMethodInvocation|OptionSubscriptions)
+	readbuf := bufio.NewReader(clientConn)
+	for _, line := range strings.Split(string(content), "\n") {
+		line = strings.TrimSpace(line)
+		switch {
+		case len(line) == 0 || strings.HasPrefix(line, "//"):
+			// skip comments, blank lines
+			continue
+		case strings.HasPrefix(line, "--> "):
+			t.Log(line)
+			// write to connection
+			clientConn.SetWriteDeadline(time.Now().Add(5 * time.Second))
+			if _, err := io.WriteString(clientConn, line[4:]+"\n"); err != nil {
+				t.Fatalf("write error: %v", err)
+			}
+		case strings.HasPrefix(line, "<-- "):
+			t.Log(line)
+			want := line[4:]
+			// read line from connection and compare text
+			clientConn.SetReadDeadline(time.Now().Add(5 * time.Second))
+			sent, err := readbuf.ReadString('\n')
+			if err != nil {
+				t.Fatalf("read error: %v", err)
+			}
+			sent = strings.TrimRight(sent, "\r\n")
+			if sent != want {
+				t.Errorf("wrong line from server\ngot:  %s\nwant: %s", sent, want)
+			}
+		default:
+			panic("invalid line in test script: " + line)
+		}
 	}
+}
 
-	response := jsonSuccessResponse{Result: &Result{}}
-	if err := in.Decode(&response); err != nil {
-		t.Fatal(err)
-	}
+// This test checks that responses are delivered for very short-lived connections that
+// only carry a single request.
+func TestServerShortLivedConn(t *testing.T) {
+	server := newTestServer()
+	defer server.Stop()
 
-	if result, ok := response.Result.(*Result); ok {
-		if result.String != stringArg {
-			t.Errorf("expected %s, got : %s\n", stringArg, result.String)
+	listener, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatal("can't listen:", err)
+	}
+	defer listener.Close()
+	go server.ServeListener(listener)
+
+	var (
+		request  = `{"jsonrpc":"2.0","id":1,"method":"rpc_modules"}` + "\n"
+		wantResp = `{"jsonrpc":"2.0","id":1,"result":{"nftest":"1.0","rpc":"1.0","test":"1.0"}}` + "\n"
+		deadline = time.Now().Add(10 * time.Second)
+	)
+	for i := 0; i < 20; i++ {
+		conn, err := net.Dial("tcp", listener.Addr().String())
+		if err != nil {
+			t.Fatal("can't dial:", err)
 		}
-		if result.Int != intArg {
-			t.Errorf("expected %d, got %d\n", intArg, result.Int)
+		defer conn.Close()
+		conn.SetDeadline(deadline)
+		// Write the request, then half-close the connection so the server stops reading.
+		conn.Write([]byte(request))
+		conn.(*net.TCPConn).CloseWrite()
+		// Now try to get the response.
+		buf := make([]byte, 2000)
+		n, err := conn.Read(buf)
+		if err != nil {
+			t.Fatal("read error:", err)
 		}
-		if !reflect.DeepEqual(result.Args, argsArg) {
-			t.Errorf("expected %v, got %v\n", argsArg, result)
+		if !bytes.Equal(buf[:n], []byte(wantResp)) {
+			t.Fatalf("wrong response: %s", buf[:n])
 		}
-	} else {
-		t.Fatalf("invalid response: expected *Result - got: %T", response.Result)
 	}
 }
-
-func TestServerMethodExecution(t *testing.T) {
-	testServerMethodExecution(t, "echo")
-}
-
-func TestServerMethodWithCtx(t *testing.T) {
-	testServerMethodExecution(t, "echoWithCtx")
-}

rpc/service.go

@@ -0,0 +1,285 @@
+// Copyright 2015 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 <http://www.gnu.org/licenses/>.
+
+package rpc
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"reflect"
+	"runtime"
+	"strings"
+	"sync"
+	"unicode"
+	"unicode/utf8"
+
+	"github.com/ethereum/go-ethereum/log"
+)
+
+var (
+	contextType      = reflect.TypeOf((*context.Context)(nil)).Elem()
+	errorType        = reflect.TypeOf((*error)(nil)).Elem()
+	subscriptionType = reflect.TypeOf(Subscription{})
+	stringType       = reflect.TypeOf("")
+)
+
+type serviceRegistry struct {
+	mu       sync.Mutex
+	services map[string]service
+}
+
+// service represents a registered object.
+type service struct {
+	name          string               // name for service
+	callbacks     map[string]*callback // registered handlers
+	subscriptions map[string]*callback // available subscriptions/notifications
+}
+
+// callback is a method callback which was registered in the server
+type callback struct {
+	fn          reflect.Value  // the function
+	rcvr        reflect.Value  // receiver object of method, set if fn is method
+	argTypes    []reflect.Type // input argument types
+	hasCtx      bool           // method's first argument is a context (not included in argTypes)
+	errPos      int            // err return idx, of -1 when method cannot return error
+	isSubscribe bool           // true if this is a subscription callback
+}
+
+func (r *serviceRegistry) registerName(name string, rcvr interface{}) error {
+	rcvrVal := reflect.ValueOf(rcvr)
+	if name == "" {
+		return fmt.Errorf("no service name for type %s", rcvrVal.Type().String())
+	}
+	callbacks := suitableCallbacks(rcvrVal)
+	if len(callbacks) == 0 {
+		return fmt.Errorf("service %T doesn't have any suitable methods/subscriptions to expose", rcvr)
+	}
+
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	if r.services == nil {
+		r.services = make(map[string]service)
+	}
+	svc, ok := r.services[name]
+	if !ok {
+		svc = service{
+			name:          name,
+			callbacks:     make(map[string]*callback),
+			subscriptions: make(map[string]*callback),
+		}
+		r.services[name] = svc
+	}
+	for name, cb := range callbacks {
+		if cb.isSubscribe {
+			svc.subscriptions[name] = cb
+		} else {
+			svc.callbacks[name] = cb
+		}
+	}
+	return nil
+}
+
+// callback returns the callback corresponding to the given RPC method name.
+func (r *serviceRegistry) callback(method string) *callback {
+	elem := strings.SplitN(method, serviceMethodSeparator, 2)
+	if len(elem) != 2 {
+		return nil
+	}
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	return r.services[elem[0]].callbacks[elem[1]]
+}
+
+// subscription returns a subscription callback in the given service.
+func (r *serviceRegistry) subscription(service, name string) *callback {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	return r.services[service].subscriptions[name]
+}
+
+// suitableCallbacks iterates over the methods of the given type. It determines if a method
+// satisfies the criteria for a RPC callback or a subscription callback and adds it to the
+// collection of callbacks. See server documentation for a summary of these criteria.
+func suitableCallbacks(receiver reflect.Value) map[string]*callback {
+	typ := receiver.Type()
+	callbacks := make(map[string]*callback)
+	for m := 0; m < typ.NumMethod(); m++ {
+		method := typ.Method(m)
+		if method.PkgPath != "" {
+			continue // method not exported
+		}
+		cb := newCallback(receiver, method.Func)
+		if cb == nil {
+			continue // function invalid
+		}
+		name := formatName(method.Name)
+		callbacks[name] = cb
+	}
+	return callbacks
+}
+
+// newCallback turns fn (a function) into a callback object. It returns nil if the function
+// is unsuitable as an RPC callback.
+func newCallback(receiver, fn reflect.Value) *callback {
+	fntype := fn.Type()
+	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) {
+		return nil
+	}
+	// If an error is returned, it must be the last returned value.
+	switch {
+	case len(outs) == 1 && isErrorType(outs[0]):
+		c.errPos = 0
+	case len(outs) == 2:
+		if isErrorType(outs[0]) || !isErrorType(outs[1]) {
+			return nil
+		}
+		c.errPos = 1
+	}
+	return c
+}
+
+// makeArgTypes composes the argTypes list.
+func (c *callback) makeArgTypes() {
+	fntype := c.fn.Type()
+	// Skip receiver and context.Context parameter (if present).
+	firstArg := 0
+	if c.rcvr.IsValid() {
+		firstArg++
+	}
+	if fntype.NumIn() > firstArg && fntype.In(firstArg) == contextType {
+		c.hasCtx = true
+		firstArg++
+	}
+	// Add all remaining parameters.
+	c.argTypes = make([]reflect.Type, fntype.NumIn()-firstArg)
+	for i := firstArg; i < fntype.NumIn(); i++ {
+		c.argTypes[i-firstArg] = fntype.In(i)
+	}
+}
+
+// call invokes the callback.
+func (c *callback) call(ctx context.Context, method string, args []reflect.Value) (res interface{}, errRes error) {
+	// Create the argument slice.
+	fullargs := make([]reflect.Value, 0, 2+len(args))
+	if c.rcvr.IsValid() {
+		fullargs = append(fullargs, c.rcvr)
+	}
+	if c.hasCtx {
+		fullargs = append(fullargs, reflect.ValueOf(ctx))
+	}
+	fullargs = append(fullargs, args...)
+
+	// Catch panic while running the callback.
+	defer func() {
+		if err := recover(); err != nil {
+			const size = 64 << 10
+			buf := make([]byte, size)
+			buf = buf[:runtime.Stack(buf, false)]
+			log.Error("RPC method " + method + " crashed: " + fmt.Sprintf("%v\n%s", err, buf))
+			errRes = errors.New("method handler crashed")
+		}
+	}()
+	// Run the callback.
+	results := c.fn.Call(fullargs)
+	if len(results) == 0 {
+		return nil, nil
+	}
+	if c.errPos >= 0 && !results[c.errPos].IsNil() {
+		// Method has returned non-nil error value.
+		err := results[c.errPos].Interface().(error)
+		return reflect.Value{}, err
+	}
+	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 {
+		t = t.Elem()
+	}
+	return t == contextType
+}
+
+// Does t satisfy the error interface?
+func isErrorType(t reflect.Type) bool {
+	for t.Kind() == reflect.Ptr {
+		t = t.Elem()
+	}
+	return t.Implements(errorType)
+}
+
+// Is t Subscription or *Subscription?
+func isSubscriptionType(t reflect.Type) bool {
+	for t.Kind() == reflect.Ptr {
+		t = t.Elem()
+	}
+	return t == subscriptionType
+}
+
+// isPubSub tests whether the given method has as as first argument a context.Context and
+// returns the pair (Subscription, error).
+func isPubSub(methodType reflect.Type) bool {
+	// numIn(0) is the receiver type
+	if methodType.NumIn() < 2 || methodType.NumOut() != 2 {
+		return false
+	}
+	return isContextType(methodType.In(1)) &&
+		isSubscriptionType(methodType.Out(0)) &&
+		isErrorType(methodType.Out(1))
+}
+
+// formatName converts to first character of name to lowercase.
+func formatName(name string) string {
+	ret := []rune(name)
+	if len(ret) > 0 {
+		ret[0] = unicode.ToLower(ret[0])
+	}
+	return string(ret)
+}

rpc/stdio.go

@@ -26,8 +26,8 @@ import (
 
 // DialStdIO creates a client on stdin/stdout.
 func DialStdIO(ctx context.Context) (*Client, error) {
-	return newClient(ctx, func(_ context.Context) (net.Conn, error) {
-		return stdioConn{}, nil
+	return newClient(ctx, func(_ context.Context) (ServerCodec, error) {
+		return NewJSONCodec(stdioConn{}), nil
 	})
 }
 
@@ -45,20 +45,8 @@ func (io stdioConn) Close() error {
 	return nil
 }
 
-func (io stdioConn) LocalAddr() net.Addr {
-	return &net.UnixAddr{Name: "stdio", Net: "stdio"}
-}
-
-func (io stdioConn) RemoteAddr() net.Addr {
-	return &net.UnixAddr{Name: "stdio", Net: "stdio"}
-}
-
-func (io stdioConn) SetDeadline(t time.Time) error {
-	return &net.OpError{Op: "set", Net: "stdio", Source: nil, Addr: nil, Err: errors.New("deadline not supported")}
-}
-
-func (io stdioConn) SetReadDeadline(t time.Time) error {
-	return &net.OpError{Op: "set", Net: "stdio", Source: nil, Addr: nil, Err: errors.New("deadline not supported")}
+func (io stdioConn) RemoteAddr() string {
+	return "/dev/stdin"
 }
 
 func (io stdioConn) SetWriteDeadline(t time.Time) error {

rpc/subscription.go

@@ -17,9 +17,19 @@
 package rpc
 
 import (
+	"bufio"
+	"container/list"
 	"context"
+	crand "crypto/rand"
+	"encoding/binary"
+	"encoding/hex"
+	"encoding/json"
 	"errors"
+	"math/rand"
+	"reflect"
+	"strings"
 	"sync"
+	"time"
 )
 
 var (
@@ -29,121 +39,289 @@ var (
 	ErrSubscriptionNotFound = errors.New("subscription not found")
 )
 
+var globalGen = randomIDGenerator()
+
 // ID defines a pseudo random number that is used to identify RPC subscriptions.
 type ID string
 
-// a Subscription is created by a notifier and tight to that notifier. The client can use
-// this subscription to wait for an unsubscribe request for the client, see Err().
-type Subscription struct {
-	ID        ID
-	namespace string
-	err       chan error // closed on unsubscribe
+// NewID returns a new, random ID.
+func NewID() ID {
+	return globalGen()
 }
 
-// Err returns a channel that is closed when the client send an unsubscribe request.
-func (s *Subscription) Err() <-chan error {
-	return s.err
+// randomIDGenerator returns a function generates a random IDs.
+func randomIDGenerator() func() ID {
+	seed, err := binary.ReadVarint(bufio.NewReader(crand.Reader))
+	if err != nil {
+		seed = int64(time.Now().Nanosecond())
+	}
+	var (
+		mu  sync.Mutex
+		rng = rand.New(rand.NewSource(seed))
+	)
+	return func() ID {
+		mu.Lock()
+		defer mu.Unlock()
+		id := make([]byte, 16)
+		rng.Read(id)
+		return encodeID(id)
+	}
 }
 
-// notifierKey is used to store a notifier within the connection context.
-type notifierKey struct{}
-
-// Notifier is tight to a RPC connection that supports subscriptions.
-// Server callbacks use the notifier to send notifications.
-type Notifier struct {
-	codec    ServerCodec
-	subMu    sync.Mutex
-	active   map[ID]*Subscription
-	inactive map[ID]*Subscription
-	buffer   map[ID][]interface{} // unsent notifications of inactive subscriptions
-}
-
-// newNotifier creates a new notifier that can be used to send subscription
-// notifications to the client.
-func newNotifier(codec ServerCodec) *Notifier {
-	return &Notifier{
-		codec:    codec,
-		active:   make(map[ID]*Subscription),
-		inactive: make(map[ID]*Subscription),
-		buffer:   make(map[ID][]interface{}),
+func encodeID(b []byte) ID {
+	id := hex.EncodeToString(b)
+	id = strings.TrimLeft(id, "0")
+	if id == "" {
+		id = "0" // ID's are RPC quantities, no leading zero's and 0 is 0x0.
 	}
+	return ID("0x" + id)
 }
 
+type notifierKey struct{}
+
 // NotifierFromContext returns the Notifier value stored in ctx, if any.
 func NotifierFromContext(ctx context.Context) (*Notifier, bool) {
 	n, ok := ctx.Value(notifierKey{}).(*Notifier)
 	return n, ok
 }
 
+// Notifier is tied to a RPC connection that supports subscriptions.
+// Server callbacks use the notifier to send notifications.
+type Notifier struct {
+	h         *handler
+	namespace string
+
+	mu           sync.Mutex
+	sub          *Subscription
+	buffer       []json.RawMessage
+	callReturned bool
+	activated    bool
+}
+
 // CreateSubscription returns a new subscription that is coupled to the
 // RPC connection. By default subscriptions are inactive and notifications
 // are dropped until the subscription is marked as active. This is done
 // by the RPC server after the subscription ID is send to the client.
 func (n *Notifier) CreateSubscription() *Subscription {
-	s := &Subscription{ID: NewID(), err: make(chan error)}
-	n.subMu.Lock()
-	n.inactive[s.ID] = s
-	n.subMu.Unlock()
-	return s
+	n.mu.Lock()
+	defer n.mu.Unlock()
+
+	if n.sub != nil {
+		panic("can't create multiple subscriptions with Notifier")
+	} else if n.callReturned {
+		panic("can't create subscription after subscribe call has returned")
+	}
+	n.sub = &Subscription{ID: n.h.idgen(), namespace: n.namespace, err: make(chan error, 1)}
+	return n.sub
 }
 
 // Notify sends a notification to the client with the given data as payload.
 // If an error occurs the RPC connection is closed and the error is returned.
 func (n *Notifier) Notify(id ID, data interface{}) error {
-	n.subMu.Lock()
-	defer n.subMu.Unlock()
+	enc, err := json.Marshal(data)
+	if err != nil {
+		return err
+	}
 
-	if sub, active := n.active[id]; active {
-		n.send(sub, data)
-	} else {
-		n.buffer[id] = append(n.buffer[id], data)
+	n.mu.Lock()
+	defer n.mu.Unlock()
+
+	if n.sub == nil {
+		panic("can't Notify before subscription is created")
+	} else if n.sub.ID != id {
+		panic("Notify with wrong ID")
+	}
+	if n.activated {
+		return n.send(n.sub, enc)
 	}
+	n.buffer = append(n.buffer, enc)
 	return nil
 }
 
-func (n *Notifier) send(sub *Subscription, data interface{}) error {
-	notification := n.codec.CreateNotification(string(sub.ID), sub.namespace, data)
-	err := n.codec.Write(notification)
-	if err != nil {
-		n.codec.Close()
+// Closed returns a channel that is closed when the RPC connection is closed.
+// Deprecated: use subscription error channel
+func (n *Notifier) Closed() <-chan interface{} {
+	return n.h.conn.Closed()
+}
+
+// takeSubscription returns the subscription (if one has been created). No subscription can
+// be created after this call.
+func (n *Notifier) takeSubscription() *Subscription {
+	n.mu.Lock()
+	defer n.mu.Unlock()
+	n.callReturned = true
+	return n.sub
+}
+
+// acticate is called after the subscription ID was sent to client. Notifications are
+// buffered before activation. This prevents notifications being sent to the client before
+// the subscription ID is sent to the client.
+func (n *Notifier) activate() error {
+	n.mu.Lock()
+	defer n.mu.Unlock()
+
+	for _, data := range n.buffer {
+		if err := n.send(n.sub, data); err != nil {
+			return err
+		}
 	}
-	return err
+	n.activated = true
+	return nil
 }
 
-// Closed returns a channel that is closed when the RPC connection is closed.
-func (n *Notifier) Closed() <-chan interface{} {
-	return n.codec.Closed()
-}
-
-// unsubscribe a subscription.
-// If the subscription could not be found ErrSubscriptionNotFound is returned.
-func (n *Notifier) unsubscribe(id ID) error {
-	n.subMu.Lock()
-	defer n.subMu.Unlock()
-	if s, found := n.active[id]; found {
-		close(s.err)
-		delete(n.active, id)
-		return nil
+func (n *Notifier) send(sub *Subscription, data json.RawMessage) error {
+	params, _ := json.Marshal(&subscriptionResult{ID: string(sub.ID), Result: data})
+	ctx := context.Background()
+	return n.h.conn.Write(ctx, &jsonrpcMessage{
+		Version: vsn,
+		Method:  n.namespace + notificationMethodSuffix,
+		Params:  params,
+	})
+}
+
+// A Subscription is created by a notifier and tight to that notifier. The client can use
+// this subscription to wait for an unsubscribe request for the client, see Err().
+type Subscription struct {
+	ID        ID
+	namespace string
+	err       chan error // closed on unsubscribe
+}
+
+// Err returns a channel that is closed when the client send an unsubscribe request.
+func (s *Subscription) Err() <-chan error {
+	return s.err
+}
+
+// MarshalJSON marshals a subscription as its ID.
+func (s *Subscription) MarshalJSON() ([]byte, error) {
+	return json.Marshal(s.ID)
+}
+
+// ClientSubscription is a subscription established through the Client's Subscribe or
+// EthSubscribe methods.
+type ClientSubscription struct {
+	client    *Client
+	etype     reflect.Type
+	channel   reflect.Value
+	namespace string
+	subid     string
+	in        chan json.RawMessage
+
+	quitOnce sync.Once     // ensures quit is closed once
+	quit     chan struct{} // quit is closed when the subscription exits
+	errOnce  sync.Once     // ensures err is closed once
+	err      chan error
+}
+
+func newClientSubscription(c *Client, namespace string, channel reflect.Value) *ClientSubscription {
+	sub := &ClientSubscription{
+		client:    c,
+		namespace: namespace,
+		etype:     channel.Type().Elem(),
+		channel:   channel,
+		quit:      make(chan struct{}),
+		err:       make(chan error, 1),
+		in:        make(chan json.RawMessage),
 	}
-	return ErrSubscriptionNotFound
-}
-
-// activate enables a subscription. Until a subscription is enabled all
-// notifications are dropped. This method is called by the RPC server after
-// the subscription ID was sent to client. This prevents notifications being
-// send to the client before the subscription ID is send to the client.
-func (n *Notifier) activate(id ID, namespace string) {
-	n.subMu.Lock()
-	defer n.subMu.Unlock()
-
-	if sub, found := n.inactive[id]; found {
-		sub.namespace = namespace
-		n.active[id] = sub
-		delete(n.inactive, id)
-		// Send buffered notifications.
-		for _, data := range n.buffer[id] {
-			n.send(sub, data)
+	return sub
+}
+
+// Err returns the subscription error channel. The intended use of Err is to schedule
+// resubscription when the client connection is closed unexpectedly.
+//
+// The error channel receives a value when the subscription has ended due
+// to an error. The received error is nil if Close has been called
+// on the underlying client and no other error has occurred.
+//
+// The error channel is closed when Unsubscribe is called on the subscription.
+func (sub *ClientSubscription) Err() <-chan error {
+	return sub.err
+}
+
+// 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.errOnce.Do(func() { close(sub.err) })
+}
+
+func (sub *ClientSubscription) quitWithError(err error, unsubscribeServer bool) {
+	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
+		// unblocks deliver.
+		close(sub.quit)
+		if unsubscribeServer {
+			sub.requestUnsubscribe()
+		}
+		if err != nil {
+			if err == ErrClientQuit {
+				err = nil // Adhere to subscription semantics.
+			}
+			sub.err <- err
 		}
-		delete(n.buffer, id)
+	})
+}
+
+func (sub *ClientSubscription) deliver(result json.RawMessage) (ok bool) {
+	select {
+	case sub.in <- result:
+		return true
+	case <-sub.quit:
+		return false
 	}
 }
+
+func (sub *ClientSubscription) start() {
+	sub.quitWithError(sub.forward())
+}
+
+func (sub *ClientSubscription) forward() (err error, unsubscribeServer bool) {
+	cases := []reflect.SelectCase{
+		{Dir: reflect.SelectRecv, Chan: reflect.ValueOf(sub.quit)},
+		{Dir: reflect.SelectRecv, Chan: reflect.ValueOf(sub.in)},
+		{Dir: reflect.SelectSend, Chan: sub.channel},
+	}
+	buffer := list.New()
+	defer buffer.Init()
+	for {
+		var chosen int
+		var recv reflect.Value
+		if buffer.Len() == 0 {
+			// Idle, omit send case.
+			chosen, recv, _ = reflect.Select(cases[:2])
+		} else {
+			// Non-empty buffer, send the first queued item.
+			cases[2].Send = reflect.ValueOf(buffer.Front().Value)
+			chosen, recv, _ = reflect.Select(cases)
+		}
+
+		switch chosen {
+		case 0: // <-sub.quit
+			return nil, false
+		case 1: // <-sub.in
+			val, err := sub.unmarshal(recv.Interface().(json.RawMessage))
+			if err != nil {
+				return err, true
+			}
+			if buffer.Len() == maxClientSubscriptionBuffer {
+				return ErrSubscriptionQueueOverflow, true
+			}
+			buffer.PushBack(val)
+		case 2: // sub.channel<-
+			cases[2].Send = reflect.Value{} // Don't hold onto the value.
+			buffer.Remove(buffer.Front())
+		}
+	}
+}
+
+func (sub *ClientSubscription) unmarshal(result json.RawMessage) (interface{}, error) {
+	val := reflect.New(sub.etype)
+	err := json.Unmarshal(result, val.Interface())
+	return val.Elem().Interface(), err
+}
+
+func (sub *ClientSubscription) requestUnsubscribe() error {
+	var result interface{}
+	return sub.client.Call(&result, sub.namespace+unsubscribeMethodSuffix, sub.subid)
+}

rpc/subscription_test.go

@@ -17,232 +17,62 @@
 package rpc
 
 import (
-	"context"
 	"encoding/json"
 	"fmt"
 	"net"
-	"sync"
+	"strings"
 	"testing"
 	"time"
 )
 
-type NotificationTestService struct {
-	mu                      sync.Mutex
-	unsubscribed            chan string
-	gotHangSubscriptionReq  chan struct{}
-	unblockHangSubscription chan struct{}
-}
-
-func (s *NotificationTestService) Echo(i int) int {
-	return i
-}
-
-func (s *NotificationTestService) Unsubscribe(subid string) {
-	if s.unsubscribed != nil {
-		s.unsubscribed <- subid
-	}
-}
-
-func (s *NotificationTestService) SomeSubscription(ctx context.Context, n, val int) (*Subscription, error) {
-	notifier, supported := NotifierFromContext(ctx)
-	if !supported {
-		return nil, ErrNotificationsUnsupported
-	}
-
-	// by explicitly creating an subscription we make sure that the subscription id is send back to the client
-	// before the first subscription.Notify is called. Otherwise the events might be send before the response
-	// for the eth_subscribe method.
-	subscription := notifier.CreateSubscription()
-
-	go func() {
-		// test expects n events, if we begin sending event immediately some events
-		// will probably be dropped since the subscription ID might not be send to
-		// the client.
-		for i := 0; i < n; i++ {
-			if err := notifier.Notify(subscription.ID, val+i); err != nil {
-				return
-			}
-		}
-
-		select {
-		case <-notifier.Closed():
-		case <-subscription.Err():
-		}
-		if s.unsubscribed != nil {
-			s.unsubscribed <- string(subscription.ID)
-		}
-	}()
-
-	return subscription, nil
-}
-
-// HangSubscription blocks on s.unblockHangSubscription before
-// sending anything.
-func (s *NotificationTestService) HangSubscription(ctx context.Context, val int) (*Subscription, error) {
-	notifier, supported := NotifierFromContext(ctx)
-	if !supported {
-		return nil, ErrNotificationsUnsupported
-	}
-
-	s.gotHangSubscriptionReq <- struct{}{}
-	<-s.unblockHangSubscription
-	subscription := notifier.CreateSubscription()
-
-	go func() {
-		notifier.Notify(subscription.ID, val)
-	}()
-	return subscription, nil
-}
-
-func TestNotifications(t *testing.T) {
-	server := NewServer()
-	service := &NotificationTestService{unsubscribed: make(chan string)}
-
-	if err := server.RegisterName("eth", service); err != nil {
-		t.Fatalf("unable to register test service %v", err)
-	}
-
-	clientConn, serverConn := net.Pipe()
-
-	go server.ServeCodec(NewJSONCodec(serverConn), OptionMethodInvocation|OptionSubscriptions)
-
-	out := json.NewEncoder(clientConn)
-	in := json.NewDecoder(clientConn)
-
-	n := 5
-	val := 12345
-	request := map[string]interface{}{
-		"id":      1,
-		"method":  "eth_subscribe",
-		"version": "2.0",
-		"params":  []interface{}{"someSubscription", n, val},
-	}
-
-	// create subscription
-	if err := out.Encode(request); err != nil {
-		t.Fatal(err)
-	}
-
-	var subid string
-	response := jsonSuccessResponse{Result: subid}
-	if err := in.Decode(&response); err != nil {
-		t.Fatal(err)
-	}
-
-	var ok bool
-	if _, ok = response.Result.(string); !ok {
-		t.Fatalf("expected subscription id, got %T", response.Result)
-	}
-
-	for i := 0; i < n; i++ {
-		var notification jsonNotification
-		if err := in.Decode(&notification); err != nil {
-			t.Fatalf("%v", err)
-		}
-
-		if int(notification.Params.Result.(float64)) != val+i {
-			t.Fatalf("expected %d, got %d", val+i, notification.Params.Result)
-		}
-	}
-
-	clientConn.Close() // causes notification unsubscribe callback to be called
-	select {
-	case <-service.unsubscribed:
-	case <-time.After(1 * time.Second):
-		t.Fatal("Unsubscribe not called after one second")
-	}
-}
-
-func waitForMessages(t *testing.T, in *json.Decoder, successes chan<- jsonSuccessResponse,
-	failures chan<- jsonErrResponse, notifications chan<- jsonNotification, errors chan<- error) {
-
-	// read and parse server messages
-	for {
-		var rmsg json.RawMessage
-		if err := in.Decode(&rmsg); err != nil {
-			return
+func TestNewID(t *testing.T) {
+	hexchars := "0123456789ABCDEFabcdef"
+	for i := 0; i < 100; i++ {
+		id := string(NewID())
+		if !strings.HasPrefix(id, "0x") {
+			t.Fatalf("invalid ID prefix, want '0x...', got %s", id)
 		}
 
-		var responses []map[string]interface{}
-		if rmsg[0] == '[' {
-			if err := json.Unmarshal(rmsg, &responses); err != nil {
-				errors <- fmt.Errorf("Received invalid message: %s", rmsg)
-				return
-			}
-		} else {
-			var msg map[string]interface{}
-			if err := json.Unmarshal(rmsg, &msg); err != nil {
-				errors <- fmt.Errorf("Received invalid message: %s", rmsg)
-				return
-			}
-			responses = append(responses, msg)
+		id = id[2:]
+		if len(id) == 0 || len(id) > 32 {
+			t.Fatalf("invalid ID length, want len(id) > 0 && len(id) <= 32), got %d", len(id))
 		}
 
-		for _, msg := range responses {
-			// determine what kind of msg was received and broadcast
-			// it to over the corresponding channel
-			if _, found := msg["result"]; found {
-				successes <- jsonSuccessResponse{
-					Version: msg["jsonrpc"].(string),
-					Id:      msg["id"],
-					Result:  msg["result"],
-				}
-				continue
-			}
-			if _, found := msg["error"]; found {
-				params := msg["params"].(map[string]interface{})
-				failures <- jsonErrResponse{
-					Version: msg["jsonrpc"].(string),
-					Id:      msg["id"],
-					Error:   jsonError{int(params["subscription"].(float64)), params["message"].(string), params["data"]},
-				}
-				continue
+		for i := 0; i < len(id); i++ {
+			if strings.IndexByte(hexchars, id[i]) == -1 {
+				t.Fatalf("unexpected byte, want any valid hex char, got %c", id[i])
 			}
-			if _, found := msg["params"]; found {
-				params := msg["params"].(map[string]interface{})
-				notifications <- jsonNotification{
-					Version: msg["jsonrpc"].(string),
-					Method:  msg["method"].(string),
-					Params:  jsonSubscription{params["subscription"].(string), params["result"]},
-				}
-				continue
-			}
-			errors <- fmt.Errorf("Received invalid message: %s", msg)
 		}
 	}
 }
 
-// TestSubscriptionMultipleNamespaces ensures that subscriptions can exists
-// for multiple different namespaces.
-func TestSubscriptionMultipleNamespaces(t *testing.T) {
+func TestSubscriptions(t *testing.T) {
 	var (
 		namespaces        = []string{"eth", "shh", "bzz"}
-		service           = NotificationTestService{}
-		subCount          = len(namespaces) * 2
+		service           = &notificationTestService{}
+		subCount          = len(namespaces)
 		notificationCount = 3
 
 		server                 = NewServer()
 		clientConn, serverConn = net.Pipe()
 		out                    = json.NewEncoder(clientConn)
 		in                     = json.NewDecoder(clientConn)
-		successes              = make(chan jsonSuccessResponse)
-		failures               = make(chan jsonErrResponse)
-		notifications          = make(chan jsonNotification)
-		errors                 = make(chan error, 10)
+		successes              = make(chan subConfirmation)
+		notifications          = make(chan subscriptionResult)
+		errors                 = make(chan error, subCount*notificationCount+1)
 	)
 
 	// setup and start server
 	for _, namespace := range namespaces {
-		if err := server.RegisterName(namespace, &service); err != nil {
+		if err := server.RegisterName(namespace, service); err != nil {
 			t.Fatalf("unable to register test service %v", err)
 		}
 	}
-
 	go server.ServeCodec(NewJSONCodec(serverConn), OptionMethodInvocation|OptionSubscriptions)
 	defer server.Stop()
 
 	// wait for message and write them to the given channels
-	go waitForMessages(t, in, successes, failures, notifications, errors)
+	go waitForMessages(in, successes, notifications, errors)
 
 	// create subscriptions one by one
 	for i, namespace := range namespaces {
@@ -252,27 +82,11 @@ func TestSubscriptionMultipleNamespaces(t *testing.T) {
 			"version": "2.0",
 			"params":  []interface{}{"someSubscription", notificationCount, i},
 		}
-
 		if err := out.Encode(&request); err != nil {
 			t.Fatalf("Could not create subscription: %v", err)
 		}
 	}
 
-	// create all subscriptions in 1 batch
-	var requests []interface{}
-	for i, namespace := range namespaces {
-		requests = append(requests, map[string]interface{}{
-			"id":      i,
-			"method":  fmt.Sprintf("%s_subscribe", namespace),
-			"version": "2.0",
-			"params":  []interface{}{"someSubscription", notificationCount, i},
-		})
-	}
-
-	if err := out.Encode(&requests); err != nil {
-		t.Fatalf("Could not create subscription in batch form: %v", err)
-	}
-
 	timeout := time.After(30 * time.Second)
 	subids := make(map[string]string, subCount)
 	count := make(map[string]int, subCount)
@@ -285,17 +99,14 @@ func TestSubscriptionMultipleNamespaces(t *testing.T) {
 		}
 		return done
 	}
-
 	for !allReceived() {
 		select {
-		case suc := <-successes: // subscription created
-			subids[namespaces[int(suc.Id.(float64))]] = suc.Result.(string)
+		case confirmation := <-successes: // subscription created
+			subids[namespaces[confirmation.reqid]] = string(confirmation.subid)
 		case notification := <-notifications:
-			count[notification.Params.Subscription]++
+			count[notification.ID]++
 		case err := <-errors:
 			t.Fatal(err)
-		case failure := <-failures:
-			t.Errorf("received error: %v", failure.Error)
 		case <-timeout:
 			for _, namespace := range namespaces {
 				subid, found := subids[namespace]
@@ -311,3 +122,85 @@ func TestSubscriptionMultipleNamespaces(t *testing.T) {
 		}
 	}
 }
+
+// This test checks that unsubscribing works.
+func TestServerUnsubscribe(t *testing.T) {
+	// Start the server.
+	server := newTestServer()
+	service := &notificationTestService{unsubscribed: make(chan string)}
+	server.RegisterName("nftest2", service)
+	p1, p2 := net.Pipe()
+	go server.ServeCodec(NewJSONCodec(p1), OptionMethodInvocation|OptionSubscriptions)
+
+	p2.SetDeadline(time.Now().Add(10 * time.Second))
+
+	// Subscribe.
+	p2.Write([]byte(`{"jsonrpc":"2.0","id":1,"method":"nftest2_subscribe","params":["someSubscription",0,10]}`))
+
+	// Handle received messages.
+	resps := make(chan subConfirmation)
+	notifications := make(chan subscriptionResult)
+	errors := make(chan error)
+	go waitForMessages(json.NewDecoder(p2), resps, notifications, errors)
+
+	// Receive the subscription ID.
+	var sub subConfirmation
+	select {
+	case sub = <-resps:
+	case err := <-errors:
+		t.Fatal(err)
+	}
+
+	// Unsubscribe and check that it is handled on the server side.
+	p2.Write([]byte(`{"jsonrpc":"2.0","method":"nftest2_unsubscribe","params":["` + sub.subid + `"]}`))
+	for {
+		select {
+		case id := <-service.unsubscribed:
+			if id != string(sub.subid) {
+				t.Errorf("wrong subscription ID unsubscribed")
+			}
+			return
+		case err := <-errors:
+			t.Fatal(err)
+		case <-notifications:
+			// drop notifications
+		}
+	}
+}
+
+type subConfirmation struct {
+	reqid int
+	subid ID
+}
+
+func waitForMessages(in *json.Decoder, successes chan subConfirmation, notifications chan subscriptionResult, errors chan error) {
+	for {
+		var msg jsonrpcMessage
+		if err := in.Decode(&msg); err != nil {
+			errors <- fmt.Errorf("decode error: %v", err)
+			return
+		}
+		switch {
+		case msg.isNotification():
+			var res subscriptionResult
+			if err := json.Unmarshal(msg.Params, &res); err != nil {
+				errors <- fmt.Errorf("invalid subscription result: %v", err)
+			} else {
+				notifications <- res
+			}
+		case msg.isResponse():
+			var c subConfirmation
+			if msg.Error != nil {
+				errors <- msg.Error
+			} else if err := json.Unmarshal(msg.Result, &c.subid); err != nil {
+				errors <- fmt.Errorf("invalid response: %v", err)
+			} else {
+				json.Unmarshal(msg.ID, &c.reqid)
+				successes <- c
+			}
+		default:
+			errors <- fmt.Errorf("unrecognized message: %v", msg)
+			return
+		}
+	}
+}

rpc/testdata/invalid-badid.js

@@ -0,0 +1,7 @@
+// This test checks processing of messages with invalid ID.
+
+--> {"id":[],"method":"test_foo"}
+<-- {"jsonrpc":"2.0","id":null,"error":{"code":-32600,"message":"invalid request"}}
+
+--> {"id":{},"method":"test_foo"}
+<-- {"jsonrpc":"2.0","id":null,"error":{"code":-32600,"message":"invalid request"}}

rpc/testdata/invalid-batch.js

@@ -0,0 +1,14 @@
+// This test checks the behavior of batches with invalid elements.
+// Empty batches are not allowed. Batches may contain junk.
+
+--> []
+<-- {"jsonrpc":"2.0","id":null,"error":{"code":-32600,"message":"empty batch"}}
+
+--> [1]
+<-- [{"jsonrpc":"2.0","id":null,"error":{"code":-32600,"message":"invalid request"}}]
+
+--> [1,2,3]
+<-- [{"jsonrpc":"2.0","id":null,"error":{"code":-32600,"message":"invalid request"}},{"jsonrpc":"2.0","id":null,"error":{"code":-32600,"message":"invalid request"}},{"jsonrpc":"2.0","id":null,"error":{"code":-32600,"message":"invalid request"}}]
+
+--> [{"jsonrpc":"2.0","id":1,"method":"test_echo","params":["foo",1]},55,{"jsonrpc":"2.0","id":2,"method":"unknown_method"},{"foo":"bar"}]
+<-- [{"jsonrpc":"2.0","id":1,"result":{"String":"foo","Int":1,"Args":null}},{"jsonrpc":"2.0","id":null,"error":{"code":-32600,"message":"invalid request"}},{"jsonrpc":"2.0","id":2,"error":{"code":-32601,"message":"the method unknown_method does not exist/is not available"}},{"jsonrpc":"2.0","id":null,"error":{"code":-32600,"message":"invalid request"}}]

rpc/testdata/invalid-idonly.js

@@ -0,0 +1,7 @@
+// This test checks processing of messages that contain just the ID and nothing else.
+
+--> {"id":1}
+<-- {"jsonrpc":"2.0","id":1,"error":{"code":-32600,"message":"invalid request"}}
+
+--> {"jsonrpc":"2.0","id":1}
+<-- {"jsonrpc":"2.0","id":1,"error":{"code":-32600,"message":"invalid request"}}

rpc/testdata/invalid-nonobj.js

@@ -0,0 +1,4 @@
+// This test checks behavior for invalid requests.
+
+--> 1
+<-- {"jsonrpc":"2.0","id":null,"error":{"code":-32600,"message":"invalid request"}}

rpc/testdata/invalid-syntax.json

@@ -0,0 +1,5 @@
+// This test checks that an error is written for invalid JSON requests.
+
+--> 'f
+<-- {"jsonrpc":"2.0","id":null,"error":{"code":-32700,"message":"invalid character '\\'' looking for beginning of value"}}
+

rpc/testdata/reqresp-batch.js

@@ -0,0 +1,8 @@
+// There is no response for all-notification batches.
+
+--> [{"jsonrpc":"2.0","method":"test_echo","params":["x",99]}]
+
+// This test checks regular batch calls.
+
+--> [{"jsonrpc":"2.0","id":2,"method":"test_echo","params":[]}, {"jsonrpc":"2.0","id": 3,"method":"test_echo","params":["x",3]}]
+<-- [{"jsonrpc":"2.0","id":2,"error":{"code":-32602,"message":"missing value for required argument 0"}},{"jsonrpc":"2.0","id":3,"result":{"String":"x","Int":3,"Args":null}}]

rpc/testdata/reqresp-echo.js

@@ -0,0 +1,16 @@
+// This test calls the test_echo method.
+
+--> {"jsonrpc": "2.0", "id": 2, "method": "test_echo", "params": []}
+<-- {"jsonrpc":"2.0","id":2,"error":{"code":-32602,"message":"missing value for required argument 0"}}
+
+--> {"jsonrpc": "2.0", "id": 2, "method": "test_echo", "params": ["x"]}
+<-- {"jsonrpc":"2.0","id":2,"error":{"code":-32602,"message":"missing value for required argument 1"}}
+
+--> {"jsonrpc": "2.0", "id": 2, "method": "test_echo", "params": ["x", 3]}
+<-- {"jsonrpc":"2.0","id":2,"result":{"String":"x","Int":3,"Args":null}}
+
+--> {"jsonrpc": "2.0", "id": 2, "method": "test_echo", "params": ["x", 3, {"S": "foo"}]}
+<-- {"jsonrpc":"2.0","id":2,"result":{"String":"x","Int":3,"Args":{"S":"foo"}}}
+
+--> {"jsonrpc": "2.0", "id": 2, "method": "test_echoWithCtx", "params": ["x", 3, {"S": "foo"}]}
+<-- {"jsonrpc":"2.0","id":2,"result":{"String":"x","Int":3,"Args":{"S":"foo"}}}

rpc/testdata/reqresp-namedparam.js

@@ -0,0 +1,5 @@
+// This test checks that an error response is sent for calls
+// with named parameters. 
+
+--> {"jsonrpc":"2.0","method":"test_echo","params":{"int":23},"id":3}
+<-- {"jsonrpc":"2.0","id":3,"error":{"code":-32602,"message":"non-array args"}}

rpc/testdata/reqresp-noargsrets.js

@@ -0,0 +1,4 @@
+// This test calls the test_noArgsRets method.
+
+--> {"jsonrpc": "2.0", "id": "foo", "method": "test_noArgsRets", "params": []}
+<-- {"jsonrpc":"2.0","id":"foo","result":null}

rpc/testdata/reqresp-nomethod.js

@@ -0,0 +1,4 @@
+// This test calls a method that doesn't exist.
+
+--> {"jsonrpc": "2.0", "id": 2, "method": "invalid_method", "params": [2, 3]}
+<-- {"jsonrpc":"2.0","id":2,"error":{"code":-32601,"message":"the method invalid_method does not exist/is not available"}}

rpc/testdata/reqresp-noparam.js

@@ -0,0 +1,4 @@
+// This test checks that calls with no parameters work.
+
+--> {"jsonrpc":"2.0","method":"test_noArgsRets","id":3}
+<-- {"jsonrpc":"2.0","id":3,"result":null}

rpc/testdata/reqresp-paramsnull.js

@@ -0,0 +1,4 @@
+// This test checks that calls with "params":null work.
+
+--> {"jsonrpc":"2.0","method":"test_noArgsRets","params":null,"id":3}
+<-- {"jsonrpc":"2.0","id":3,"result":null}

rpc/testdata/revcall.js

@@ -0,0 +1,6 @@
+// This test checks reverse calls.
+
+--> {"jsonrpc":"2.0","id":2,"method":"test_callMeBack","params":["foo",[1]]}
+<-- {"jsonrpc":"2.0","id":1,"method":"foo","params":[1]}
+--> {"jsonrpc":"2.0","id":1,"result":"my result"}
+<-- {"jsonrpc":"2.0","id":2,"result":"my result"}

rpc/testdata/revcall2.js

@@ -0,0 +1,7 @@
+// This test checks reverse calls.
+
+--> {"jsonrpc":"2.0","id":2,"method":"test_callMeBackLater","params":["foo",[1]]}
+<-- {"jsonrpc":"2.0","id":2,"result":null}
+<-- {"jsonrpc":"2.0","id":1,"method":"foo","params":[1]}
+--> {"jsonrpc":"2.0","id":1,"result":"my result"}
+

rpc/testdata/subscription.js

@@ -0,0 +1,12 @@
+// This test checks basic subscription support.
+
+--> {"jsonrpc":"2.0","id":1,"method":"nftest_subscribe","params":["someSubscription",5,1]}
+<-- {"jsonrpc":"2.0","id":1,"result":"0x1"}
+<-- {"jsonrpc":"2.0","method":"nftest_subscription","params":{"subscription":"0x1","result":1}}
+<-- {"jsonrpc":"2.0","method":"nftest_subscription","params":{"subscription":"0x1","result":2}}
+<-- {"jsonrpc":"2.0","method":"nftest_subscription","params":{"subscription":"0x1","result":3}}
+<-- {"jsonrpc":"2.0","method":"nftest_subscription","params":{"subscription":"0x1","result":4}}
+<-- {"jsonrpc":"2.0","method":"nftest_subscription","params":{"subscription":"0x1","result":5}}
+
+--> {"jsonrpc":"2.0","id":2,"method":"nftest_echo","params":[11]}
+<-- {"jsonrpc":"2.0","id":2,"result":11}

rpc/testservice_test.go

@@ -0,0 +1,180 @@
+// Copyright 2018 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 <http://www.gnu.org/licenses/>.
+
+package rpc
+
+import (
+	"context"
+	"encoding/binary"
+	"errors"
+	"sync"
+	"time"
+)
+
+func newTestServer() *Server {
+	server := NewServer()
+	server.idgen = sequentialIDGenerator()
+	if err := server.RegisterName("test", new(testService)); err != nil {
+		panic(err)
+	}
+	if err := server.RegisterName("nftest", new(notificationTestService)); err != nil {
+		panic(err)
+	}
+	return server
+}
+
+func sequentialIDGenerator() func() ID {
+	var (
+		mu      sync.Mutex
+		counter uint64
+	)
+	return func() ID {
+		mu.Lock()
+		defer mu.Unlock()
+		counter++
+		id := make([]byte, 8)
+		binary.BigEndian.PutUint64(id, counter)
+		return encodeID(id)
+	}
+}
+
+type testService struct{}
+
+type Args struct {
+	S string
+}
+
+type Result struct {
+	String string
+	Int    int
+	Args   *Args
+}
+
+func (s *testService) NoArgsRets() {}
+
+func (s *testService) Echo(str string, i int, args *Args) Result {
+	return Result{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) Sleep(ctx context.Context, duration time.Duration) {
+	time.Sleep(duration)
+}
+
+func (s *testService) Rets() (string, error) {
+	return "", nil
+}
+
+func (s *testService) InvalidRets1() (error, string) {
+	return nil, ""
+}
+
+func (s *testService) InvalidRets2() (string, string) {
+	return "", ""
+}
+
+func (s *testService) InvalidRets3() (string, string, error) {
+	return "", "", nil
+}
+
+func (s *testService) CallMeBack(ctx context.Context, method string, args []interface{}) (interface{}, error) {
+	c, ok := ClientFromContext(ctx)
+	if !ok {
+		return nil, errors.New("no client")
+	}
+	var result interface{}
+	err := c.Call(&result, method, args...)
+	return result, err
+}
+
+func (s *testService) CallMeBackLater(ctx context.Context, method string, args []interface{}) error {
+	c, ok := ClientFromContext(ctx)
+	if !ok {
+		return errors.New("no client")
+	}
+	go func() {
+		<-ctx.Done()
+		var result interface{}
+		c.Call(&result, method, args...)
+	}()
+	return nil
+}
+
+func (s *testService) Subscription(ctx context.Context) (*Subscription, error) {
+	return nil, nil
+}
+
+type notificationTestService struct {
+	unsubscribed            chan string
+	gotHangSubscriptionReq  chan struct{}
+	unblockHangSubscription chan struct{}
+}
+
+func (s *notificationTestService) Echo(i int) int {
+	return i
+}
+
+func (s *notificationTestService) Unsubscribe(subid string) {
+	if s.unsubscribed != nil {
+		s.unsubscribed <- subid
+	}
+}
+
+func (s *notificationTestService) SomeSubscription(ctx context.Context, n, val int) (*Subscription, error) {
+	notifier, supported := NotifierFromContext(ctx)
+	if !supported {
+		return nil, ErrNotificationsUnsupported
+	}
+
+	// By explicitly creating an subscription we make sure that the subscription id is send
+	// back to the client before the first subscription.Notify is called. Otherwise the
+	// events might be send before the response for the *_subscribe method.
+	subscription := notifier.CreateSubscription()
+	go func() {
+		for i := 0; i < n; i++ {
+			if err := notifier.Notify(subscription.ID, val+i); err != nil {
+				return
+			}
+		}
+		select {
+		case <-notifier.Closed():
+		case <-subscription.Err():
+		}
+		if s.unsubscribed != nil {
+			s.unsubscribed <- string(subscription.ID)
+		}
+	}()
+	return subscription, nil
+}
+
+// HangSubscription blocks on s.unblockHangSubscription before sending anything.
+func (s *notificationTestService) HangSubscription(ctx context.Context, val int) (*Subscription, error) {
+	notifier, supported := NotifierFromContext(ctx)
+	if !supported {
+		return nil, ErrNotificationsUnsupported
+	}
+	s.gotHangSubscriptionReq <- struct{}{}
+	<-s.unblockHangSubscription
+	subscription := notifier.CreateSubscription()
+
+	go func() {
+		notifier.Notify(subscription.ID, val)
+	}()
+	return subscription, nil
+}

rpc/types.go

@@ -17,13 +17,11 @@
 package rpc
 
 import (
+	"context"
 	"fmt"
 	"math"
-	"reflect"
 	"strings"
-	"sync"
 
-	mapset "github.com/deckarep/golang-set"
 	"github.com/ethereum/go-ethereum/common/hexutil"
 )
 
@@ -35,57 +33,6 @@ type API struct {
 	Public    bool        // indication if the methods must be considered safe for public use
 }
 
-// callback is a method callback which was registered in the server
-type callback struct {
-	rcvr        reflect.Value  // receiver of method
-	method      reflect.Method // callback
-	argTypes    []reflect.Type // input argument types
-	hasCtx      bool           // method's first argument is a context (not included in argTypes)
-	errPos      int            // err return idx, of -1 when method cannot return error
-	isSubscribe bool           // indication if the callback is a subscription
-}
-
-// service represents a registered object
-type service struct {
-	name          string        // name for service
-	typ           reflect.Type  // receiver type
-	callbacks     callbacks     // registered handlers
-	subscriptions subscriptions // available subscriptions/notifications
-}
-
-// serverRequest is an incoming request
-type serverRequest struct {
-	id            interface{}
-	svcname       string
-	callb         *callback
-	args          []reflect.Value
-	isUnsubscribe bool
-	err           Error
-}
-
-type serviceRegistry map[string]*service // collection of services
-type callbacks map[string]*callback      // collection of RPC callbacks
-type subscriptions map[string]*callback  // collection of subscription callbacks
-
-// Server represents a RPC server
-type Server struct {
-	services serviceRegistry
-
-	run      int32
-	codecsMu sync.Mutex
-	codecs   mapset.Set
-}
-
-// rpcRequest represents a raw incoming RPC request
-type rpcRequest struct {
-	service  string
-	method   string
-	id       interface{}
-	isPubSub bool
-	params   interface{}
-	err      Error // invalid batch element
-}
-
 // Error wraps RPC errors, which contain an error code in addition to the message.
 type Error interface {
 	Error() string  // returns the message
@@ -96,24 +43,19 @@ type Error interface {
 // a RPC session. Implementations must be go-routine safe since the codec can be called in
 // multiple go-routines concurrently.
 type ServerCodec interface {
-	// Read next request
-	ReadRequestHeaders() ([]rpcRequest, bool, Error)
-	// Parse request argument to the given types
-	ParseRequestArguments(argTypes []reflect.Type, params interface{}) ([]reflect.Value, Error)
-	// Assemble success response, expects response id and payload
-	CreateResponse(id interface{}, reply interface{}) interface{}
-	// Assemble error response, expects response id and error
-	CreateErrorResponse(id interface{}, err Error) interface{}
-	// Assemble error response with extra information about the error through info
-	CreateErrorResponseWithInfo(id interface{}, err Error, info interface{}) interface{}
-	// Create notification response
-	CreateNotification(id, namespace string, event interface{}) interface{}
-	// Write msg to client.
-	Write(msg interface{}) error
-	// Close underlying data stream
+	Read() (msgs []*jsonrpcMessage, isBatch bool, err error)
 	Close()
-	// Closed when underlying connection is closed
+	jsonWriter
+}
+
+// jsonWriter can write JSON messages to its underlying connection.
+// Implementations must be safe for concurrent use.
+type jsonWriter interface {
+	Write(context.Context, interface{}) error
+	// Closed returns a channel which is closed when the connection is closed.
 	Closed() <-chan interface{}
+	// RemoteAddr returns the peer address of the connection.
+	RemoteAddr() string
 }
 
 type BlockNumber int64

rpc/utils.go

@@ -1,226 +0,0 @@
-// Copyright 2015 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 <http://www.gnu.org/licenses/>.
-
-package rpc
-
-import (
-	"bufio"
-	"context"
-	crand "crypto/rand"
-	"encoding/binary"
-	"encoding/hex"
-	"math/rand"
-	"reflect"
-	"strings"
-	"sync"
-	"time"
-	"unicode"
-	"unicode/utf8"
-)
-
-var (
-	subscriptionIDGenMu sync.Mutex
-	subscriptionIDGen   = idGenerator()
-)
-
-// Is this an exported - upper case - name?
-func isExported(name string) bool {
-	rune, _ := utf8.DecodeRuneInString(name)
-	return unicode.IsUpper(rune)
-}
-
-// Is this type exported or a builtin?
-func isExportedOrBuiltinType(t reflect.Type) bool {
-	for t.Kind() == reflect.Ptr {
-		t = t.Elem()
-	}
-	// PkgPath will be non-empty even for an exported type,
-	// so we need to check the type name as well.
-	return isExported(t.Name()) || t.PkgPath() == ""
-}
-
-var contextType = reflect.TypeOf((*context.Context)(nil)).Elem()
-
-// isContextType returns an indication if the given t is of context.Context or *context.Context type
-func isContextType(t reflect.Type) bool {
-	for t.Kind() == reflect.Ptr {
-		t = t.Elem()
-	}
-	return t == contextType
-}
-
-var errorType = reflect.TypeOf((*error)(nil)).Elem()
-
-// Implements this type the error interface
-func isErrorType(t reflect.Type) bool {
-	for t.Kind() == reflect.Ptr {
-		t = t.Elem()
-	}
-	return t.Implements(errorType)
-}
-
-var subscriptionType = reflect.TypeOf((*Subscription)(nil)).Elem()
-
-// isSubscriptionType returns an indication if the given t is of Subscription or *Subscription type
-func isSubscriptionType(t reflect.Type) bool {
-	for t.Kind() == reflect.Ptr {
-		t = t.Elem()
-	}
-	return t == subscriptionType
-}
-
-// isPubSub tests whether the given method has as as first argument a context.Context
-// and returns the pair (Subscription, error)
-func isPubSub(methodType reflect.Type) bool {
-	// numIn(0) is the receiver type
-	if methodType.NumIn() < 2 || methodType.NumOut() != 2 {
-		return false
-	}
-
-	return isContextType(methodType.In(1)) &&
-		isSubscriptionType(methodType.Out(0)) &&
-		isErrorType(methodType.Out(1))
-}
-
-// formatName will convert to first character to lower case
-func formatName(name string) string {
-	ret := []rune(name)
-	if len(ret) > 0 {
-		ret[0] = unicode.ToLower(ret[0])
-	}
-	return string(ret)
-}
-
-// suitableCallbacks iterates over the methods of the given type. It will determine if a method satisfies the criteria
-// for a RPC callback or a subscription callback and adds it to the collection of callbacks or subscriptions. See server
-// documentation for a summary of these criteria.
-func suitableCallbacks(rcvr reflect.Value, typ reflect.Type) (callbacks, subscriptions) {
-	callbacks := make(callbacks)
-	subscriptions := make(subscriptions)
-
-METHODS:
-	for m := 0; m < typ.NumMethod(); m++ {
-		method := typ.Method(m)
-		mtype := method.Type
-		mname := formatName(method.Name)
-		if method.PkgPath != "" { // method must be exported
-			continue
-		}
-
-		var h callback
-		h.isSubscribe = isPubSub(mtype)
-		h.rcvr = rcvr
-		h.method = method
-		h.errPos = -1
-
-		firstArg := 1
-		numIn := mtype.NumIn()
-		if numIn >= 2 && mtype.In(1) == contextType {
-			h.hasCtx = true
-			firstArg = 2
-		}
-
-		if h.isSubscribe {
-			h.argTypes = make([]reflect.Type, numIn-firstArg) // skip rcvr type
-			for i := firstArg; i < numIn; i++ {
-				argType := mtype.In(i)
-				if isExportedOrBuiltinType(argType) {
-					h.argTypes[i-firstArg] = argType
-				} else {
-					continue METHODS
-				}
-			}
-
-			subscriptions[mname] = &h
-			continue METHODS
-		}
-
-		// determine method arguments, ignore first arg since it's the receiver type
-		// Arguments must be exported or builtin types
-		h.argTypes = make([]reflect.Type, numIn-firstArg)
-		for i := firstArg; i < numIn; i++ {
-			argType := mtype.In(i)
-			if !isExportedOrBuiltinType(argType) {
-				continue METHODS
-			}
-			h.argTypes[i-firstArg] = argType
-		}
-
-		// check that all returned values are exported or builtin types
-		for i := 0; i < mtype.NumOut(); i++ {
-			if !isExportedOrBuiltinType(mtype.Out(i)) {
-				continue METHODS
-			}
-		}
-
-		// when a method returns an error it must be the last returned value
-		h.errPos = -1
-		for i := 0; i < mtype.NumOut(); i++ {
-			if isErrorType(mtype.Out(i)) {
-				h.errPos = i
-				break
-			}
-		}
-
-		if h.errPos >= 0 && h.errPos != mtype.NumOut()-1 {
-			continue METHODS
-		}
-
-		switch mtype.NumOut() {
-		case 0, 1, 2:
-			if mtype.NumOut() == 2 && h.errPos == -1 { // method must one return value and 1 error
-				continue METHODS
-			}
-			callbacks[mname] = &h
-		}
-	}
-
-	return callbacks, subscriptions
-}
-
-// idGenerator helper utility that generates a (pseudo) random sequence of
-// bytes that are used to generate identifiers.
-func idGenerator() *rand.Rand {
-	if seed, err := binary.ReadVarint(bufio.NewReader(crand.Reader)); err == nil {
-		return rand.New(rand.NewSource(seed))
-	}
-	return rand.New(rand.NewSource(int64(time.Now().Nanosecond())))
-}
-
-// NewID generates a identifier that can be used as an identifier in the RPC interface.
-// e.g. filter and subscription identifier.
-func NewID() ID {
-	subscriptionIDGenMu.Lock()
-	defer subscriptionIDGenMu.Unlock()
-
-	id := make([]byte, 16)
-	for i := 0; i < len(id); i += 7 {
-		val := subscriptionIDGen.Int63()
-		for j := 0; i+j < len(id) && j < 7; j++ {
-			id[i+j] = byte(val)
-			val >>= 8
-		}
-	}
-
-	rpcId := hex.EncodeToString(id)
-	// rpc ID's are RPC quantities, no leading zero's and 0 is 0x0
-	rpcId = strings.TrimLeft(rpcId, "0")
-	if rpcId == "" {
-		rpcId = "0"
-	}
-
-	return ID("0x" + rpcId)
-}

rpc/utils_test.go

@@ -1,43 +0,0 @@
-// 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 <http://www.gnu.org/licenses/>.
-
-package rpc
-
-import (
-	"strings"
-	"testing"
-)
-
-func TestNewID(t *testing.T) {
-	hexchars := "0123456789ABCDEFabcdef"
-	for i := 0; i < 100; i++ {
-		id := string(NewID())
-		if !strings.HasPrefix(id, "0x") {
-			t.Fatalf("invalid ID prefix, want '0x...', got %s", id)
-		}
-
-		id = id[2:]
-		if len(id) == 0 || len(id) > 32 {
-			t.Fatalf("invalid ID length, want len(id) > 0 && len(id) <= 32), got %d", len(id))
-		}
-
-		for i := 0; i < len(id); i++ {
-			if strings.IndexByte(hexchars, id[i]) == -1 {
-				t.Fatalf("unexpected byte, want any valid hex char, got %c", id[i])
-			}
-		}
-	}
-}

rpc/websocket.go

@@ -22,6 +22,7 @@ import (
 	"crypto/tls"
 	"encoding/base64"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"net"
 	"net/http"
@@ -56,24 +57,39 @@ var websocketJSONCodec = websocket.Codec{
 //
 // allowedOrigins should be a comma-separated list of allowed origin URLs.
 // To allow connections with any origin, pass "*".
-func (srv *Server) WebsocketHandler(allowedOrigins []string) http.Handler {
+func (s *Server) WebsocketHandler(allowedOrigins []string) http.Handler {
 	return websocket.Server{
 		Handshake: wsHandshakeValidator(allowedOrigins),
 		Handler: func(conn *websocket.Conn) {
-			// Create a custom encode/decode pair to enforce payload size and number encoding
-			conn.MaxPayloadBytes = maxRequestContentLength
-
-			encoder := func(v interface{}) error {
-				return websocketJSONCodec.Send(conn, v)
-			}
-			decoder := func(v interface{}) error {
-				return websocketJSONCodec.Receive(conn, v)
-			}
-			srv.ServeCodec(NewCodec(conn, encoder, decoder), OptionMethodInvocation|OptionSubscriptions)
+			codec := newWebsocketCodec(conn)
+			s.ServeCodec(codec, OptionMethodInvocation|OptionSubscriptions)
 		},
 	}
 }
 
+func newWebsocketCodec(conn *websocket.Conn) ServerCodec {
+	// Create a custom encode/decode pair to enforce payload size and number encoding
+	conn.MaxPayloadBytes = maxRequestContentLength
+	encoder := func(v interface{}) error {
+		return websocketJSONCodec.Send(conn, v)
+	}
+	decoder := func(v interface{}) error {
+		return websocketJSONCodec.Receive(conn, v)
+	}
+	rpcconn := Conn(conn)
+	if conn.IsServerConn() {
+		// Override remote address with the actual socket address because
+		// package websocket crashes if there is no request origin.
+		addr := conn.Request().RemoteAddr
+		if wsaddr := conn.RemoteAddr().(*websocket.Addr); wsaddr.URL != nil {
+			// Add origin if present.
+			addr += "(" + wsaddr.URL.String() + ")"
+		}
+		rpcconn = connWithRemoteAddr{conn, addr}
+	}
+	return NewCodec(rpcconn, encoder, decoder)
+}
+
 // NewWSServer creates a new websocket RPC server around an API provider.
 //
 // Deprecated: use Server.WebsocketHandler
@@ -105,15 +121,16 @@ func wsHandshakeValidator(allowedOrigins []string) func(*websocket.Config, *http
 		}
 	}
 
-	log.Debug(fmt.Sprintf("Allowed origin(s) for WS RPC interface %v\n", origins.ToSlice()))
+	log.Debug(fmt.Sprintf("Allowed origin(s) for WS RPC interface %v", origins.ToSlice()))
 
 	f := func(cfg *websocket.Config, req *http.Request) error {
+		// Verify origin against whitelist.
 		origin := strings.ToLower(req.Header.Get("Origin"))
 		if allowAllOrigins || origins.Contains(origin) {
 			return nil
 		}
-		log.Warn(fmt.Sprintf("origin '%s' not allowed on WS-RPC interface\n", origin))
-		return fmt.Errorf("origin %s not allowed", origin)
+		log.Warn("Rejected WebSocket connection", "origin", origin)
+		return errors.New("origin not allowed")
 	}
 
 	return f
@@ -155,8 +172,12 @@ func DialWebsocket(ctx context.Context, endpoint, origin string) (*Client, error
 		return nil, err
 	}
 
-	return newClient(ctx, func(ctx context.Context) (net.Conn, error) {
-		return wsDialContext(ctx, config)
+	return newClient(ctx, func(ctx context.Context) (ServerCodec, error) {
+		conn, err := wsDialContext(ctx, config)
+		if err != nil {
+			return nil, err
+		}
+		return newWebsocketCodec(conn), nil
 	})
 }