include rpc from go-eth

eth/rpc/client.go

@@ -0,0 +1,625 @@
+// 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 (
+	"bytes"
+	"context"
+	"errors"
+	"fmt"
+	"github.com/goccy/go-json"
+	"net/url"
+	"reflect"
+	"strconv"
+	"sync/atomic"
+	"time"
+
+	"github.com/ethereum/go-ethereum/log"
+)
+
+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
+	defaultDialTimeout = 10 * time.Second // used if context has no deadline
+	subscribeTimeout   = 5 * time.Second  // overall timeout eth_subscribe, rpc_modules calls
+)
+
+const (
+	// Subscriptions are removed when the subscriber cannot keep up.
+	//
+	// This can be worked around by supplying a channel with sufficiently sized buffer,
+	// but this can be inconvenient and hard to explain in the docs. Another issue with
+	// buffered channels is that the buffer is static even though it might not be needed
+	// most of the time.
+	//
+	// The approach taken here is to maintain a per-subscription linked list buffer
+	// shrinks on demand. If the buffer reaches the size below, the subscription is
+	// dropped.
+	maxClientSubscriptionBuffer = 20000
+)
+
+// BatchElem is an element in a batch request.
+type BatchElem struct {
+	Method string
+	Args   []interface{}
+	// The result is unmarshaled into this field. Result must be set to a
+	// non-nil pointer value of the desired type, otherwise the response will be
+	// discarded.
+	Result interface{}
+	// Error is set if the server returns an error for this request, or if
+	// unmarshaling into Result fails. It is not set for I/O errors.
+	Error error
+}
+
+// Client represents a connection to an RPC server.
+type Client struct {
+	idgen    func() ID // for subscriptions
+	isHTTP   bool
+	services *serviceRegistry
+
+	idCounter uint32
+
+	// 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
+
+	// 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
+}
+
+type reconnectFunc func(ctx context.Context) (ServerCodec, error)
+
+type clientContextKey struct{}
+
+type clientConn struct {
+	codec   ServerCodec
+	handler *handler
+}
+
+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}
+}
+
+func (cc *clientConn) close(err error, inflightReq *requestOp) {
+	cc.handler.close(err, inflightReq)
+	cc.codec.close()
+}
+
+type readOp struct {
+	msgs  []*jsonrpcMessage
+	batch bool
+}
+
+type requestOp struct {
+	ids  []json.RawMessage
+	err  error
+	resp chan *jsonrpcMessage // receives up to len(ids) responses
+	sub  *ClientSubscription  // only set for EthSubscribe requests
+}
+
+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.
+		if !c.isHTTP {
+			select {
+			case c.reqTimeout <- op:
+			case <-c.closing:
+			}
+		}
+		return nil, ctx.Err()
+	case resp := <-op.resp:
+		return resp, op.err
+	}
+}
+
+// Dial creates a new client for the given URL.
+//
+// The currently supported URL schemes are "http", "https", "ws" and "wss". If rawurl is a
+// file name with no URL scheme, a local socket connection is established using UNIX
+// domain sockets on supported platforms and named pipes on Windows. If you want to
+// configure transport options, use DialHTTP, DialWebsocket or DialIPC instead.
+//
+// For websocket connections, the origin is set to the local host name.
+//
+// The client reconnects automatically if the connection is lost.
+func Dial(rawurl string) (*Client, error) {
+	return DialContext(context.Background(), rawurl)
+}
+
+// DialContext creates a new RPC client, just like Dial.
+//
+// The context is used to cancel or time out the initial connection establishment. It does
+// not affect subsequent interactions with the client.
+func DialContext(ctx context.Context, rawurl string) (*Client, error) {
+	u, err := url.Parse(rawurl)
+	if err != nil {
+		return nil, err
+	}
+	switch u.Scheme {
+	case "http", "https":
+		return DialHTTP(rawurl)
+	case "ws", "wss":
+		return DialWebsocket(ctx, rawurl, "")
+	case "stdio":
+		return DialStdIO(ctx)
+	case "":
+		return DialIPC(ctx, rawurl)
+	default:
+		return nil, fmt.Errorf("no known transport for URL scheme %q", u.Scheme)
+	}
+}
+
+// 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{
+		idgen:       idgen,
+		isHTTP:      isHTTP,
+		services:    services,
+		writeConn:   conn,
+		close:       make(chan struct{}),
+		closing:     make(chan struct{}),
+		didClose:    make(chan struct{}),
+		reconnected: make(chan ServerCodec),
+		readOp:      make(chan readOp),
+		readErr:     make(chan error),
+		reqInit:     make(chan *requestOp),
+		reqSent:     make(chan error, 1),
+		reqTimeout:  make(chan *requestOp),
+	}
+	if !isHTTP {
+		go c.dispatch(conn)
+	}
+	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 strconv.AppendUint(nil, uint64(id), 10)
+}
+
+// SupportedModules calls the rpc_modules method, retrieving the list of
+// APIs that are available on the server.
+func (c *Client) SupportedModules() (map[string]string, error) {
+	var result map[string]string
+	ctx, cancel := context.WithTimeout(context.Background(), subscribeTimeout)
+	defer cancel()
+	err := c.CallContext(ctx, &result, "rpc_modules")
+	return result, err
+}
+
+// Close closes the client, aborting any in-flight requests.
+func (c *Client) Close() {
+	if c.isHTTP {
+		return
+	}
+	select {
+	case c.close <- struct{}{}:
+		<-c.didClose
+	case <-c.didClose:
+	}
+}
+
+// Call performs a JSON-RPC call with the given arguments and unmarshals into
+// result if no error occurred.
+//
+// The result must be a pointer so that package json can unmarshal into it. You
+// can also pass nil, in which case the result is ignored.
+func (c *Client) Call(result interface{}, method string, args ...interface{}) error {
+	ctx := context.Background()
+	return c.CallContext(ctx, result, method, args...)
+}
+
+// CallContext performs a JSON-RPC call with the given arguments. If the context is
+// canceled before the call has successfully returned, CallContext returns immediately.
+//
+// The result must be a pointer so that package json can unmarshal into it. You
+// can also pass nil, in which case the result is ignored.
+func (c *Client) CallContext(ctx context.Context, result interface{}, method string, args ...interface{}) error {
+	msg, err := c.newMessage(method, args...)
+	if err != nil {
+		return err
+	}
+	op := &requestOp{ids: []json.RawMessage{msg.ID}, resp: make(chan *jsonrpcMessage, 1)}
+
+	if c.isHTTP {
+		err = c.sendHTTP(ctx, op, msg)
+	} else {
+		err = c.send(ctx, op, msg)
+	}
+	if err != nil {
+		return err
+	}
+
+	// dispatch has accepted the request and will close the channel when it quits.
+	switch resp, err := op.wait(ctx, c); {
+	case err != nil:
+		return err
+	case resp.Error != nil:
+		return resp.Error
+	case len(resp.Result) == 0:
+		return ErrNoResult
+	default:
+		return json.Unmarshal(resp.Result, &result)
+	}
+}
+
+// BatchCall sends all given requests as a single batch and waits for the server
+// to return a response for all of them.
+//
+// In contrast to Call, BatchCall only returns I/O errors. Any error specific to
+// a request is reported through the Error field of the corresponding BatchElem.
+//
+// Note that batch calls may not be executed atomically on the server side.
+func (c *Client) BatchCall(b []BatchElem) error {
+	ctx := context.Background()
+	return c.BatchCallContext(ctx, b)
+}
+
+// BatchCall sends all given requests as a single batch and waits for the server
+// to return a response for all of them. The wait duration is bounded by the
+// context's deadline.
+//
+// In contrast to CallContext, BatchCallContext only returns errors that have occurred
+// while sending the request. Any error specific to a request is reported through the
+// Error field of the corresponding BatchElem.
+//
+// Note that batch calls may not be executed atomically on the server side.
+func (c *Client) BatchCallContext(ctx context.Context, b []BatchElem) error {
+	msgs := make([]*jsonrpcMessage, len(b))
+	op := &requestOp{
+		ids:  make([]json.RawMessage, len(b)),
+		resp: make(chan *jsonrpcMessage, len(b)),
+	}
+	for i, elem := range b {
+		msg, err := c.newMessage(elem.Method, elem.Args...)
+		if err != nil {
+			return err
+		}
+		msgs[i] = msg
+		op.ids[i] = msg.ID
+	}
+
+	var err error
+	if c.isHTTP {
+		err = c.sendBatchHTTP(ctx, op, msgs)
+	} else {
+		err = c.send(ctx, op, msgs)
+	}
+
+	// Wait for all responses to come back.
+	for n := 0; n < len(b) && err == nil; n++ {
+		var resp *jsonrpcMessage
+		resp, err = op.wait(ctx, c)
+		if err != nil {
+			break
+		}
+		// Find the element corresponding to this response.
+		// The element is guaranteed to be present because dispatch
+		// only sends valid IDs to our channel.
+		var elem *BatchElem
+		for i := range msgs {
+			if bytes.Equal(msgs[i].ID, resp.ID) {
+				elem = &b[i]
+				break
+			}
+		}
+		if resp.Error != nil {
+			elem.Error = resp.Error
+			continue
+		}
+		if len(resp.Result) == 0 {
+			elem.Error = ErrNoResult
+			continue
+		}
+		elem.Error = json.Unmarshal(resp.Result, elem.Result)
+	}
+	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...)
+}
+
+// ShhSubscribe registers a subscripion under the "shh" namespace.
+func (c *Client) ShhSubscribe(ctx context.Context, channel interface{}, args ...interface{}) (*ClientSubscription, error) {
+	return c.Subscribe(ctx, "shh", channel, args...)
+}
+
+// Subscribe calls the "<namespace>_subscribe" method with the given arguments,
+// registering a subscription. Server notifications for the subscription are
+// sent to the given channel. The element type of the channel must match the
+// expected type of content returned by the subscription.
+//
+// The context argument cancels the RPC request that sets up the subscription but has no
+// effect on the subscription after Subscribe has returned.
+//
+// Slow subscribers will be dropped eventually. Client buffers up to 20000 notifications
+// before considering the subscriber dead. The subscription Err channel will receive
+// ErrSubscriptionQueueOverflow. Use a sufficiently large buffer on the channel or ensure
+// that the channel usually has at least one reader to prevent this issue.
+func (c *Client) Subscribe(ctx context.Context, namespace string, channel interface{}, args ...interface{}) (*ClientSubscription, error) {
+	// Check type of channel first.
+	chanVal := reflect.ValueOf(channel)
+	if chanVal.Kind() != reflect.Chan || chanVal.Type().ChanDir()&reflect.SendDir == 0 {
+		panic("first argument to Subscribe must be a writable channel")
+	}
+	if chanVal.IsNil() {
+		panic("channel given to Subscribe must not be nil")
+	}
+	if c.isHTTP {
+		return nil, ErrNotificationsUnsupported
+	}
+
+	msg, err := c.newMessage(namespace+subscribeMethodSuffix, args...)
+	if err != nil {
+		return nil, err
+	}
+	op := &requestOp{
+		ids:  []json.RawMessage{msg.ID},
+		resp: make(chan *jsonrpcMessage),
+		sub:  newClientSubscription(c, namespace, chanVal),
+	}
+
+	// Send the subscription request.
+	// The arrival and validity of the response is signaled on sub.quit.
+	if err := c.send(ctx, op, msg); err != nil {
+		return nil, err
+	}
+	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) {
+	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 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.reqInit <- op:
+		err := c.write(ctx, msg)
+		c.reqSent <- err
+		return err
+	case <-ctx.Done():
+		// This can happen if the client is overloaded or unable to keep up with
+		// subscription notifications.
+		return ctx.Err()
+	case <-c.closing:
+		return ErrClientQuit
+	}
+}
+
+func (c *Client) write(ctx context.Context, msg interface{}) error {
+	// The previous write failed. Try to establish a new connection.
+	if c.writeConn == nil {
+		if err := c.reconnect(ctx); err != nil {
+			return err
+		}
+	}
+	err := c.writeConn.writeJSON(ctx, msg)
+	if err != nil {
+		c.writeConn = nil
+	}
+	return err
+}
+
+func (c *Client) reconnect(ctx context.Context) error {
+	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("RPC client reconnect failed", "err", err)
+		return err
+	}
+	select {
+	case c.reconnected <- newconn:
+		c.writeConn = newconn
+		return nil
+	case <-c.didClose:
+		newconn.close()
+		return ErrClientQuit
+	}
+}
+
+// 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(codec ServerCodec) {
+	var (
+		lastOp      *requestOp  // tracks last send operation
+		reqInitLock = c.reqInit // nil while the send lock is held
+		conn        = c.newClientConn(codec)
+		reading     = true
+	)
+	defer func() {
+		close(c.closing)
+		if reading {
+			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 op := <-c.readOp:
+			if op.batch {
+				conn.handler.handleBatch(op.msgs)
+			} else {
+				conn.handler.handleMsg(op.msgs[0])
+			}
+
+		case err := <-c.readErr:
+			conn.handler.log.Debug("RPC connection read error", "err", err)
+			conn.close(err, lastOp)
+			reading = false
+
+		// 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 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(newcodec)
+			reading = true
+			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
+			conn.handler.addRequestOp(op)
+
+		case err := <-c.reqSent:
+			if err != nil {
+				// Remove response handlers for the last send. When the read loop
+				// goes down, it will signal all other current operations.
+				conn.handler.removeRequestOp(lastOp)
+			}
+			// Let the next request in.
+			reqInitLock = c.reqInit
+			lastOp = nil
+
+		case op := <-c.reqTimeout:
+			conn.handler.removeRequestOp(op)
+		}
+	}
+}
+
+// drainRead drops read messages until an error occurs.
+func (c *Client) drainRead() {
+	for {
+		select {
+		case <-c.readOp:
+		case <-c.readErr:
+			return
+		}
+	}
+}
+
+// read decodes RPC messages from a codec, feeding them into dispatch.
+func (c *Client) read(codec ServerCodec) {
+	for {
+		msgs, batch, err := codec.readBatch()
+		if _, ok := err.(*json.SyntaxError); ok {
+			codec.writeJSON(context.Background(), errorMessage(&parseError{err.Error()}))
+		}
+		if err != nil {
+			c.readErr <- err
+			return
+		}
+		c.readOp <- readOp{msgs, batch}
+	}
+}

eth/rpc/client_example_test.go

@@ -0,0 +1,88 @@
+// 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_test
+
+import (
+	"context"
+	"fmt"
+	"math/big"
+	"time"
+
+	"github.com/ethereum/go-ethereum/rpc"
+)
+
+// In this example, our client wishes to track the latest 'block number'
+// known to the server. The server supports two methods:
+//
+// eth_getBlockByNumber("latest", {})
+//    returns the latest block object.
+//
+// eth_subscribe("newBlocks")
+//    creates a subscription which fires block objects when new blocks arrive.
+
+type Block struct {
+	Number *big.Int
+}
+
+func ExampleClientSubscription() {
+	// Connect the client.
+	client, _ := rpc.Dial("ws://127.0.0.1:8485")
+	subch := make(chan Block)
+
+	// Ensure that subch receives the latest block.
+	go func() {
+		for i := 0; ; i++ {
+			if i > 0 {
+				time.Sleep(2 * time.Second)
+			}
+			subscribeBlocks(client, subch)
+		}
+	}()
+
+	// Print events from the subscription as they arrive.
+	for block := range subch {
+		fmt.Println("latest block:", block.Number)
+	}
+}
+
+// subscribeBlocks runs in its own goroutine and maintains
+// a subscription for new blocks.
+func subscribeBlocks(client *rpc.Client, subch chan Block) {
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+
+	// Subscribe to new blocks.
+	sub, err := client.EthSubscribe(ctx, subch, "newHeads")
+	if err != nil {
+		fmt.Println("subscribe error:", err)
+		return
+	}
+
+	// The connection is established now.
+	// Update the channel with the current block.
+	var lastBlock Block
+	if err := client.CallContext(ctx, &lastBlock, "eth_getBlockByNumber", "latest"); err != nil {
+		fmt.Println("can't get latest block:", err)
+		return
+	}
+	subch <- lastBlock
+
+	// The subscription will deliver events to the channel. Wait for the
+	// subscription to end for any reason, then loop around to re-establish
+	// the connection.
+	fmt.Println("connection lost: ", <-sub.Err())
+}

eth/rpc/client_test.go

@@ -0,0 +1,569 @@
+// 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 (
+	"context"
+	"fmt"
+	"math/rand"
+	"net"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"reflect"
+	"runtime"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/davecgh/go-spew/spew"
+	"github.com/ethereum/go-ethereum/log"
+)
+
+func TestClientRequest(t *testing.T) {
+	server := newTestServer()
+	defer server.Stop()
+	client := DialInProc(server)
+	defer client.Close()
+
+	var resp echoResult
+	if err := client.Call(&resp, "test_echo", "hello", 10, &echoArgs{"world"}); err != nil {
+		t.Fatal(err)
+	}
+	if !reflect.DeepEqual(resp, echoResult{"hello", 10, &echoArgs{"world"}}) {
+		t.Errorf("incorrect result %#v", resp)
+	}
+}
+
+func TestClientBatchRequest(t *testing.T) {
+	server := newTestServer()
+	defer server.Stop()
+	client := DialInProc(server)
+	defer client.Close()
+
+	batch := []BatchElem{
+		{
+			Method: "test_echo",
+			Args:   []interface{}{"hello", 10, &echoArgs{"world"}},
+			Result: new(echoResult),
+		},
+		{
+			Method: "test_echo",
+			Args:   []interface{}{"hello2", 11, &echoArgs{"world"}},
+			Result: new(echoResult),
+		},
+		{
+			Method: "no_such_method",
+			Args:   []interface{}{1, 2, 3},
+			Result: new(int),
+		},
+	}
+	if err := client.BatchCall(batch); err != nil {
+		t.Fatal(err)
+	}
+	wantResult := []BatchElem{
+		{
+			Method: "test_echo",
+			Args:   []interface{}{"hello", 10, &echoArgs{"world"}},
+			Result: &echoResult{"hello", 10, &echoArgs{"world"}},
+		},
+		{
+			Method: "test_echo",
+			Args:   []interface{}{"hello2", 11, &echoArgs{"world"}},
+			Result: &echoResult{"hello2", 11, &echoArgs{"world"}},
+		},
+		{
+			Method: "no_such_method",
+			Args:   []interface{}{1, 2, 3},
+			Result: new(int),
+			Error:  &jsonError{Code: -32601, Message: "the method no_such_method does not exist/is not available"},
+		},
+	}
+	if !reflect.DeepEqual(batch, wantResult) {
+		t.Errorf("batch results mismatch:\ngot %swant %s", spew.Sdump(batch), spew.Sdump(wantResult))
+	}
+}
+
+func TestClientNotify(t *testing.T) {
+	server := newTestServer()
+	defer server.Stop()
+	client := DialInProc(server)
+	defer client.Close()
+
+	if err := client.Notify(context.Background(), "test_echo", "hello", 10, &echoArgs{"world"}); err != nil {
+		t.Fatal(err)
+	}
+}
+
+// func TestClientCancelInproc(t *testing.T) { testClientCancel("inproc", t) }
+func TestClientCancelWebsocket(t *testing.T) { testClientCancel("ws", t) }
+func TestClientCancelHTTP(t *testing.T)      { testClientCancel("http", t) }
+func TestClientCancelIPC(t *testing.T)       { testClientCancel("ipc", t) }
+
+// This test checks that requests made through CallContext can be canceled by canceling
+// the context.
+func testClientCancel(transport string, t *testing.T) {
+	// These tests take a lot of time, run them all at once.
+	// You probably want to run with -parallel 1 or comment out
+	// the call to t.Parallel if you enable the logging.
+	t.Parallel()
+
+	server := newTestServer()
+	defer server.Stop()
+
+	// What we want to achieve is that the context gets canceled
+	// at various stages of request processing. The interesting cases
+	// are:
+	//  - cancel during dial
+	//  - cancel while performing a HTTP request
+	//  - cancel while waiting for a response
+	//
+	// To trigger those, the times are chosen such that connections
+	// are killed within the deadline for every other call (maxKillTimeout
+	// is 2x maxCancelTimeout).
+	//
+	// Once a connection is dead, there is a fair chance it won't connect
+	// successfully because the accept is delayed by 1s.
+	maxContextCancelTimeout := 300 * time.Millisecond
+	fl := &flakeyListener{
+		maxAcceptDelay: 1 * time.Second,
+		maxKillTimeout: 600 * time.Millisecond,
+	}
+
+	var client *Client
+	switch transport {
+	case "ws", "http":
+		c, hs := httpTestClient(server, transport, fl)
+		defer hs.Close()
+		client = c
+	case "ipc":
+		c, l := ipcTestClient(server, fl)
+		defer l.Close()
+		client = c
+	default:
+		panic("unknown transport: " + transport)
+	}
+
+	// The actual test starts here.
+	var (
+		wg       sync.WaitGroup
+		nreqs    = 10
+		ncallers = 6
+	)
+	caller := func(index int) {
+		defer wg.Done()
+		for i := 0; i < nreqs; i++ {
+			var (
+				ctx     context.Context
+				cancel  func()
+				timeout = time.Duration(rand.Int63n(int64(maxContextCancelTimeout)))
+			)
+			if index < ncallers/2 {
+				// For half of the callers, create a context without deadline
+				// and cancel it later.
+				ctx, cancel = context.WithCancel(context.Background())
+				time.AfterFunc(timeout, cancel)
+			} else {
+				// For the other half, create a context with a deadline instead. This is
+				// different because the context deadline is used to set the socket write
+				// deadline.
+				ctx, cancel = context.WithTimeout(context.Background(), timeout)
+			}
+			// Now perform a call with the context.
+			// The key thing here is that no call will ever complete successfully.
+			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 {
+				t.Errorf("no error for call with %v wait time", timeout)
+			}
+			cancel()
+		}
+	}
+	wg.Add(ncallers)
+	for i := 0; i < ncallers; i++ {
+		go caller(i)
+	}
+	wg.Wait()
+}
+
+func TestClientSubscribeInvalidArg(t *testing.T) {
+	server := newTestServer()
+	defer server.Stop()
+	client := DialInProc(server)
+	defer client.Close()
+
+	check := func(shouldPanic bool, arg interface{}) {
+		defer func() {
+			err := recover()
+			if shouldPanic && err == nil {
+				t.Errorf("EthSubscribe should've panicked for %#v", arg)
+			}
+			if !shouldPanic && err != nil {
+				t.Errorf("EthSubscribe shouldn't have panicked for %#v", arg)
+				buf := make([]byte, 1024*1024)
+				buf = buf[:runtime.Stack(buf, false)]
+				t.Error(err)
+				t.Error(string(buf))
+			}
+		}()
+		client.EthSubscribe(context.Background(), arg, "foo_bar")
+	}
+	check(true, nil)
+	check(true, 1)
+	check(true, (chan int)(nil))
+	check(true, make(<-chan int))
+	check(false, make(chan int))
+	check(false, make(chan<- int))
+}
+
+func TestClientSubscribe(t *testing.T) {
+	server := newTestServer()
+	defer server.Stop()
+	client := DialInProc(server)
+	defer client.Close()
+
+	nc := make(chan int)
+	count := 10
+	sub, err := client.Subscribe(context.Background(), "nftest", nc, "someSubscription", count, 0)
+	if err != nil {
+		t.Fatal("can't subscribe:", err)
+	}
+	for i := 0; i < count; i++ {
+		if val := <-nc; val != i {
+			t.Fatalf("value mismatch: got %d, want %d", val, i)
+		}
+	}
+
+	sub.Unsubscribe()
+	select {
+	case v := <-nc:
+		t.Fatal("received value after unsubscribe:", v)
+	case err := <-sub.Err():
+		if err != nil {
+			t.Fatalf("Err returned a non-nil error after explicit unsubscribe: %q", err)
+		}
+	case <-time.After(1 * time.Second):
+		t.Fatalf("subscription not closed within 1s after unsubscribe")
+	}
+}
+
+// In this test, the connection drops while Subscribe is waiting for a response.
+func TestClientSubscribeClose(t *testing.T) {
+	server := newTestServer()
+	service := &notificationTestService{
+		gotHangSubscriptionReq:  make(chan struct{}),
+		unblockHangSubscription: make(chan struct{}),
+	}
+	if err := server.RegisterName("nftest2", service); err != nil {
+		t.Fatal(err)
+	}
+
+	defer server.Stop()
+	client := DialInProc(server)
+	defer client.Close()
+
+	var (
+		nc   = make(chan int)
+		errc = make(chan error)
+		sub  *ClientSubscription
+		err  error
+	)
+	go func() {
+		sub, err = client.Subscribe(context.Background(), "nftest2", nc, "hangSubscription", 999)
+		errc <- err
+	}()
+
+	<-service.gotHangSubscriptionReq
+	client.Close()
+	service.unblockHangSubscription <- struct{}{}
+
+	select {
+	case err := <-errc:
+		if err == nil {
+			t.Errorf("Subscribe returned nil error after Close")
+		}
+		if sub != nil {
+			t.Error("Subscribe returned non-nil subscription after Close")
+		}
+	case <-time.After(1 * time.Second):
+		t.Fatalf("Subscribe did not return within 1s after Close")
+	}
+}
+
+// This test reproduces https://github.com/ethereum/go-ethereum/issues/17837 where the
+// client hangs during shutdown when Unsubscribe races with Client.Close.
+func TestClientCloseUnsubscribeRace(t *testing.T) {
+	server := newTestServer()
+	defer server.Stop()
+
+	for i := 0; i < 20; i++ {
+		client := DialInProc(server)
+		nc := make(chan int)
+		sub, err := client.Subscribe(context.Background(), "nftest", nc, "someSubscription", 3, 1)
+		if err != nil {
+			t.Fatal(err)
+		}
+		go client.Close()
+		go sub.Unsubscribe()
+		select {
+		case <-sub.Err():
+		case <-time.After(5 * time.Second):
+			t.Fatal("subscription not closed within timeout")
+		}
+	}
+}
+
+// This test checks that Client doesn't lock up when a single subscriber
+// doesn't read subscription events.
+func TestClientNotificationStorm(t *testing.T) {
+	server := newTestServer()
+	defer server.Stop()
+
+	doTest := func(count int, wantError bool) {
+		client := DialInProc(server)
+		defer client.Close()
+		ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+		defer cancel()
+
+		// Subscribe on the server. It will start sending many notifications
+		// very quickly.
+		nc := make(chan int)
+		sub, err := client.Subscribe(ctx, "nftest", nc, "someSubscription", count, 0)
+		if err != nil {
+			t.Fatal("can't subscribe:", err)
+		}
+		defer sub.Unsubscribe()
+
+		// Process each notification, try to run a call in between each of them.
+		for i := 0; i < count; i++ {
+			select {
+			case val := <-nc:
+				if val != i {
+					t.Fatalf("(%d/%d) unexpected value %d", i, count, val)
+				}
+			case err := <-sub.Err():
+				if wantError && err != ErrSubscriptionQueueOverflow {
+					t.Fatalf("(%d/%d) got error %q, want %q", i, count, err, ErrSubscriptionQueueOverflow)
+				} else if !wantError {
+					t.Fatalf("(%d/%d) got unexpected error %q", i, count, err)
+				}
+				return
+			}
+			var r int
+			err := client.CallContext(ctx, &r, "nftest_echo", i)
+			if err != nil {
+				if !wantError {
+					t.Fatalf("(%d/%d) call error: %v", i, count, err)
+				}
+				return
+			}
+		}
+		if wantError {
+			t.Fatalf("didn't get expected error")
+		}
+	}
+
+	doTest(8000, false)
+	doTest(23000, true)
+}
+
+func TestClientHTTP(t *testing.T) {
+	server := newTestServer()
+	defer server.Stop()
+
+	client, hs := httpTestClient(server, "http", nil)
+	defer hs.Close()
+	defer client.Close()
+
+	// Launch concurrent requests.
+	var (
+		results    = make([]echoResult, 100)
+		errc       = make(chan error)
+		wantResult = echoResult{"a", 1, new(echoArgs)}
+	)
+	defer client.Close()
+	for i := range results {
+		i := i
+		go func() {
+			errc <- client.Call(&results[i], "test_echo",
+				wantResult.String, wantResult.Int, wantResult.Args)
+		}()
+	}
+
+	// Wait for all of them to complete.
+	timeout := time.NewTimer(5 * time.Second)
+	defer timeout.Stop()
+	for i := range results {
+		select {
+		case err := <-errc:
+			if err != nil {
+				t.Fatal(err)
+			}
+		case <-timeout.C:
+			t.Fatalf("timeout (got %d/%d) results)", i+1, len(results))
+		}
+	}
+
+	// Check results.
+	for i := range results {
+		if !reflect.DeepEqual(results[i], wantResult) {
+			t.Errorf("result %d mismatch: got %#v, want %#v", i, results[i], wantResult)
+		}
+	}
+}
+
+func TestClientReconnect(t *testing.T) {
+	startServer := func(addr string) (*Server, net.Listener) {
+		srv := newTestServer()
+		l, err := net.Listen("tcp", addr)
+		if err != nil {
+			t.Fatal("can't listen:", err)
+		}
+		go http.Serve(l, srv.WebsocketHandler([]string{"*"}))
+		return srv, l
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), 12*time.Second)
+	defer cancel()
+
+	// Start a server and corresponding client.
+	s1, l1 := startServer("127.0.0.1:0")
+	client, err := DialContext(ctx, "ws://"+l1.Addr().String())
+	if err != nil {
+		t.Fatal("can't dial", err)
+	}
+
+	// Perform a call. This should work because the server is up.
+	var resp echoResult
+	if err := client.CallContext(ctx, &resp, "test_echo", "", 1, nil); err != nil {
+		t.Fatal(err)
+	}
+
+	// Shut down the server and allow for some cool down time so we can listen on the same
+	// address again.
+	l1.Close()
+	s1.Stop()
+	time.Sleep(2 * time.Second)
+
+	// Try calling again. It shouldn't work.
+	if err := client.CallContext(ctx, &resp, "test_echo", "", 2, nil); err == nil {
+		t.Error("successful call while the server is down")
+		t.Logf("resp: %#v", resp)
+	}
+
+	// Start it up again and call again. The connection should be reestablished.
+	// We spawn multiple calls here to check whether this hangs somehow.
+	s2, l2 := startServer(l1.Addr().String())
+	defer l2.Close()
+	defer s2.Stop()
+
+	start := make(chan struct{})
+	errors := make(chan error, 20)
+	for i := 0; i < cap(errors); i++ {
+		go func() {
+			<-start
+			var resp echoResult
+			errors <- client.CallContext(ctx, &resp, "test_echo", "", 3, nil)
+		}()
+	}
+	close(start)
+	errcount := 0
+	for i := 0; i < cap(errors); i++ {
+		if err = <-errors; err != nil {
+			errcount++
+		}
+	}
+	t.Logf("%d errors, last error: %v", errcount, err)
+	if errcount > 1 {
+		t.Errorf("expected one error after disconnect, got %d", errcount)
+	}
+}
+
+func httpTestClient(srv *Server, transport string, fl *flakeyListener) (*Client, *httptest.Server) {
+	// Create the HTTP server.
+	var hs *httptest.Server
+	switch transport {
+	case "ws":
+		hs = httptest.NewUnstartedServer(srv.WebsocketHandler([]string{"*"}))
+	case "http":
+		hs = httptest.NewUnstartedServer(srv)
+	default:
+		panic("unknown HTTP transport: " + transport)
+	}
+	// Wrap the listener if required.
+	if fl != nil {
+		fl.Listener = hs.Listener
+		hs.Listener = fl
+	}
+	// Connect the client.
+	hs.Start()
+	client, err := Dial(transport + "://" + hs.Listener.Addr().String())
+	if err != nil {
+		panic(err)
+	}
+	return client, hs
+}
+
+func ipcTestClient(srv *Server, fl *flakeyListener) (*Client, net.Listener) {
+	// Listen on a random endpoint.
+	endpoint := fmt.Sprintf("go-ethereum-test-ipc-%d-%d", os.Getpid(), rand.Int63())
+	if runtime.GOOS == "windows" {
+		endpoint = `\\.\pipe\` + endpoint
+	} else {
+		endpoint = os.TempDir() + "/" + endpoint
+	}
+	l, err := ipcListen(endpoint)
+	if err != nil {
+		panic(err)
+	}
+	// Connect the listener to the server.
+	if fl != nil {
+		fl.Listener = l
+		l = fl
+	}
+	go srv.ServeListener(l)
+	// Connect the client.
+	client, err := Dial(endpoint)
+	if err != nil {
+		panic(err)
+	}
+	return client, l
+}
+
+// flakeyListener kills accepted connections after a random timeout.
+type flakeyListener struct {
+	net.Listener
+	maxKillTimeout time.Duration
+	maxAcceptDelay time.Duration
+}
+
+func (l *flakeyListener) Accept() (net.Conn, error) {
+	delay := time.Duration(rand.Int63n(int64(l.maxAcceptDelay)))
+	time.Sleep(delay)
+
+	c, err := l.Listener.Accept()
+	if err == nil {
+		timeout := time.Duration(rand.Int63n(int64(l.maxKillTimeout)))
+		time.AfterFunc(timeout, func() {
+			log.Debug(fmt.Sprintf("killing conn %v after %v", c.LocalAddr(), timeout))
+			c.Close()
+		})
+	}
+	return c, err
+}

eth/rpc/constants_unix.go

@@ -0,0 +1,33 @@
+// Copyright 2019 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/>.
+
+// +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris
+
+package rpc
+
+/*
+#include <sys/un.h>
+
+int max_socket_path_size() {
+struct sockaddr_un s;
+return sizeof(s.sun_path);
+}
+*/
+import "C"
+
+var (
+	max_path_size = C.max_socket_path_size()
+)

eth/rpc/constants_unix_nocgo.go

@@ -0,0 +1,25 @@
+// Copyright 2019 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/>.
+
+// +build !cgo,!windows
+
+package rpc
+
+var (
+	//  On Linux, sun_path is 108 bytes in size
+	// see http://man7.org/linux/man-pages/man7/unix.7.html
+	max_path_size = 108
+)

eth/rpc/doc.go

@@ -0,0 +1,110 @@
+// 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 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:
+
+ - method must be exported
+ - method returns 0, 1 (response or error) or 2 (response and error) values
+
+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.
+
+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 *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.
+
+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 {
+	return a + b
+ }
+
+ func (s *CalculatorService) Div(a, b int) (int, error) {
+	if b == 0 {
+		return 0, errors.New("divide by zero")
+	}
+	return a/b, nil
+ }
+
+ calculator := new(CalculatorService)
+ server := NewServer()
+ server.RegisterName("calculator", calculator)
+ l, _ := net.ListenUnix("unix", &net.UnixAddr{Net: "unix", Name: "/tmp/calculator.sock"})
+ server.ServeListener(l)
+
+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:
+
+ - method must be exported
+ - first method argument type must be context.Context
+ - method must have return types (rpc.Subscription, error)
+
+An example method:
+
+ func (s *BlockChainService) NewBlocks(ctx context.Context) (rpc.Subscription, error) {
+ 	...
+ }
+
+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

eth/rpc/endpoints.go

@@ -0,0 +1,102 @@
+// 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 (
+	"net"
+
+	"github.com/ethereum/go-ethereum/log"
+)
+
+// StartHTTPEndpoint starts the HTTP RPC endpoint, configured with cors/vhosts/modules
+func StartHTTPEndpoint(endpoint string, apis []API, modules []string, cors []string, vhosts []string, timeouts HTTPTimeouts) (net.Listener, *Server, error) {
+	// Generate the whitelist based on the allowed modules
+	whitelist := make(map[string]bool)
+	for _, module := range modules {
+		whitelist[module] = true
+	}
+	// Register all the APIs exposed by the services
+	handler := NewServer()
+	for _, api := range apis {
+		if whitelist[api.Namespace] || (len(whitelist) == 0 && api.Public) {
+			if err := handler.RegisterName(api.Namespace, api.Service); err != nil {
+				return nil, nil, err
+			}
+			log.Debug("HTTP registered", "namespace", api.Namespace)
+		}
+	}
+	// All APIs registered, start the HTTP listener
+	var (
+		listener net.Listener
+		err      error
+	)
+	if listener, err = net.Listen("tcp", endpoint); err != nil {
+		return nil, nil, err
+	}
+	go NewHTTPServer(cors, vhosts, timeouts, handler).Serve(listener)
+	return listener, handler, err
+}
+
+// StartWSEndpoint starts a websocket endpoint
+func StartWSEndpoint(endpoint string, apis []API, modules []string, wsOrigins []string, exposeAll bool) (net.Listener, *Server, error) {
+
+	// Generate the whitelist based on the allowed modules
+	whitelist := make(map[string]bool)
+	for _, module := range modules {
+		whitelist[module] = true
+	}
+	// Register all the APIs exposed by the services
+	handler := NewServer()
+	for _, api := range apis {
+		if exposeAll || whitelist[api.Namespace] || (len(whitelist) == 0 && api.Public) {
+			if err := handler.RegisterName(api.Namespace, api.Service); err != nil {
+				return nil, nil, err
+			}
+			log.Debug("WebSocket registered", "service", api.Service, "namespace", api.Namespace)
+		}
+	}
+	// All APIs registered, start the HTTP listener
+	var (
+		listener net.Listener
+		err      error
+	)
+	if listener, err = net.Listen("tcp", endpoint); err != nil {
+		return nil, nil, err
+	}
+	go NewWSServer(wsOrigins, handler).Serve(listener)
+	return listener, handler, err
+
+}
+
+// StartIPCEndpoint starts an IPC endpoint.
+func StartIPCEndpoint(ipcEndpoint string, apis []API) (net.Listener, *Server, error) {
+	// Register all the APIs exposed by the services.
+	handler := NewServer()
+	for _, api := range apis {
+		if err := handler.RegisterName(api.Namespace, api.Service); err != nil {
+			return nil, nil, err
+		}
+		log.Debug("IPC registered", "namespace", api.Namespace)
+	}
+	// All APIs registered, start the IPC listener.
+	listener, err := ipcListen(ipcEndpoint)
+	if err != nil {
+		return nil, nil, err
+	}
+	go handler.ServeListener(listener)
+	return listener, handler, nil
+}

eth/rpc/errors.go

@@ -0,0 +1,65 @@
+// 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 "fmt"
+
+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 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 }
+
+func (e *invalidRequestError) ErrorCode() int { return -32600 }
+
+func (e *invalidRequestError) Error() string { return e.message }
+
+// received message is invalid
+type invalidMessageError struct{ message string }
+
+func (e *invalidMessageError) ErrorCode() int { return -32700 }
+
+func (e *invalidMessageError) Error() string { return e.message }
+
+// unable to decode supplied params, or an invalid number of parameters
+type invalidParamsError struct{ message string }
+
+func (e *invalidParamsError) ErrorCode() int { return -32602 }
+
+func (e *invalidParamsError) Error() string { return e.message }

eth/rpc/gzip.go

@@ -0,0 +1,66 @@
+// Copyright 2019 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 (
+	"compress/gzip"
+	"io"
+	"io/ioutil"
+	"net/http"
+	"strings"
+	"sync"
+)
+
+var gzPool = sync.Pool{
+	New: func() interface{} {
+		w := gzip.NewWriter(ioutil.Discard)
+		return w
+	},
+}
+
+type gzipResponseWriter struct {
+	io.Writer
+	http.ResponseWriter
+}
+
+func (w *gzipResponseWriter) WriteHeader(status int) {
+	w.Header().Del("Content-Length")
+	w.ResponseWriter.WriteHeader(status)
+}
+
+func (w *gzipResponseWriter) Write(b []byte) (int, error) {
+	return w.Writer.Write(b)
+}
+
+func newGzipHandler(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if !strings.Contains(r.Header.Get("Accept-Encoding"), "gzip") {
+			next.ServeHTTP(w, r)
+			return
+		}
+
+		w.Header().Set("Content-Encoding", "gzip")
+
+		gz := gzPool.Get().(*gzip.Writer)
+		defer gzPool.Put(gz)
+
+		gz.Reset(w)
+		defer gz.Close()
+
+		next.ServeHTTP(&gzipResponseWriter{ResponseWriter: w, Writer: gz}, r)
+	})
+}

eth/rpc/handler.go

@@ -0,0 +1,397 @@
+// Copyright 2019 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"
+	"github.com/goccy/go-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.writeJSON(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.writeJSON(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.writeJSON(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.callWG.Wait()
+	h.cancelRoot()
+	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(false, err)
+	}
+}
+
+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.Warn("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)
+}

eth/rpc/http.go

@@ -0,0 +1,359 @@
+// 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 (
+	"bytes"
+	"context"
+	"errors"
+	"fmt"
+	"github.com/goccy/go-json"
+	"io"
+	"io/ioutil"
+	"mime"
+	"net"
+	"net/http"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/ethereum/go-ethereum/log"
+	"github.com/rs/cors"
+)
+
+const (
+	maxRequestContentLength = 1024 * 1024 * 5
+	contentType             = "application/json"
+)
+
+// 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
+	closeCh   chan interface{}
+}
+
+// httpConn is treated specially by Client.
+func (hc *httpConn) writeJSON(context.Context, interface{}) error {
+	panic("writeJSON called on httpConn")
+}
+
+func (hc *httpConn) remoteAddr() string {
+	return hc.req.URL.String()
+}
+
+func (hc *httpConn) readBatch() ([]*jsonrpcMessage, bool, error) {
+	<-hc.closeCh
+	return nil, false, io.EOF
+}
+
+func (hc *httpConn) close() {
+	hc.closeOnce.Do(func() { close(hc.closeCh) })
+}
+
+func (hc *httpConn) closed() <-chan interface{} {
+	return hc.closeCh
+}
+
+// HTTPTimeouts represents the configuration params for the HTTP RPC server.
+type HTTPTimeouts struct {
+	// ReadTimeout is the maximum duration for reading the entire
+	// request, including the body.
+	//
+	// Because ReadTimeout does not let Handlers make per-request
+	// decisions on each request body's acceptable deadline or
+	// upload rate, most users will prefer to use
+	// ReadHeaderTimeout. It is valid to use them both.
+	ReadTimeout time.Duration
+
+	// WriteTimeout is the maximum duration before timing out
+	// writes of the response. It is reset whenever a new
+	// request's header is read. Like ReadTimeout, it does not
+	// let Handlers make decisions on a per-request basis.
+	WriteTimeout time.Duration
+
+	// IdleTimeout is the maximum amount of time to wait for the
+	// next request when keep-alives are enabled. If IdleTimeout
+	// is zero, the value of ReadTimeout is used. If both are
+	// zero, ReadHeaderTimeout is used.
+	IdleTimeout time.Duration
+}
+
+// DefaultHTTPTimeouts represents the default timeout values used if further
+// configuration is not provided.
+var DefaultHTTPTimeouts = HTTPTimeouts{
+	ReadTimeout:  30 * time.Second,
+	WriteTimeout: 30 * time.Second,
+	IdleTimeout:  120 * time.Second,
+}
+
+// DialHTTPWithClient creates a new RPC client that connects to an RPC server over HTTP
+// using the provided HTTP Client.
+func DialHTTPWithClient(endpoint string, client *http.Client) (*Client, error) {
+	req, err := http.NewRequest(http.MethodPost, endpoint, nil)
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("Content-Type", contentType)
+	req.Header.Set("Accept", contentType)
+
+	initctx := context.Background()
+	return newClient(initctx, func(context.Context) (ServerCodec, error) {
+		return &httpConn{client: client, req: req, closeCh: make(chan interface{})}, nil
+	})
+}
+
+// DialHTTP creates a new RPC client that connects to an RPC server over HTTP.
+func DialHTTP(endpoint string) (*Client, error) {
+	return DialHTTPWithClient(endpoint, new(http.Client))
+}
+
+func (c *Client) sendHTTP(ctx context.Context, op *requestOp, msg interface{}) error {
+	hc := c.writeConn.(*httpConn)
+	respBody, err := hc.doRequest(ctx, msg)
+	if respBody != nil {
+		defer respBody.Close()
+	}
+
+	if err != nil {
+		if respBody != nil {
+			buf := new(bytes.Buffer)
+			if _, err2 := buf.ReadFrom(respBody); err2 == nil {
+				return fmt.Errorf("%v %v", err, buf.String())
+			}
+		}
+		return err
+	}
+	var respmsg jsonrpcMessage
+	if err := json.NewDecoder(respBody).Decode(&respmsg); err != nil {
+		return err
+	}
+	op.resp <- &respmsg
+	return nil
+}
+
+func (c *Client) sendBatchHTTP(ctx context.Context, op *requestOp, msgs []*jsonrpcMessage) error {
+	hc := c.writeConn.(*httpConn)
+	respBody, err := hc.doRequest(ctx, msgs)
+	if err != nil {
+		return err
+	}
+	defer respBody.Close()
+	var respmsgs []jsonrpcMessage
+	if err := json.NewDecoder(respBody).Decode(&respmsgs); err != nil {
+		return err
+	}
+	for i := 0; i < len(respmsgs); i++ {
+		op.resp <- &respmsgs[i]
+	}
+	return nil
+}
+
+func (hc *httpConn) doRequest(ctx context.Context, msg interface{}) (io.ReadCloser, error) {
+	body, err := json.Marshal(msg)
+	if err != nil {
+		return nil, err
+	}
+	req := hc.req.WithContext(ctx)
+	req.Body = ioutil.NopCloser(bytes.NewReader(body))
+	req.ContentLength = int64(len(body))
+
+	resp, err := hc.client.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		return resp.Body, errors.New(resp.Status)
+	}
+	return resp.Body, nil
+}
+
+// httpServerConn turns a HTTP connection into a Conn.
+type httpServerConn struct {
+	io.Reader
+	io.Writer
+	r *http.Request
+}
+
+func newHTTPServerConn(r *http.Request, w http.ResponseWriter) ServerCodec {
+	body := io.LimitReader(r.Body, maxRequestContentLength)
+	conn := &httpServerConn{Reader: body, Writer: w, r: r}
+	return NewCodec(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
+func NewHTTPServer(cors []string, vhosts []string, timeouts HTTPTimeouts, srv http.Handler) *http.Server {
+	// Wrap the CORS-handler within a host-handler
+	handler := newCorsHandler(srv, cors)
+	handler = newVHostHandler(vhosts, handler)
+	handler = newGzipHandler(handler)
+
+	// Make sure timeout values are meaningful
+	if timeouts.ReadTimeout < time.Second {
+		log.Warn("Sanitizing invalid HTTP read timeout", "provided", timeouts.ReadTimeout, "updated", DefaultHTTPTimeouts.ReadTimeout)
+		timeouts.ReadTimeout = DefaultHTTPTimeouts.ReadTimeout
+	}
+	if timeouts.WriteTimeout < time.Second {
+		log.Warn("Sanitizing invalid HTTP write timeout", "provided", timeouts.WriteTimeout, "updated", DefaultHTTPTimeouts.WriteTimeout)
+		timeouts.WriteTimeout = DefaultHTTPTimeouts.WriteTimeout
+	}
+	if timeouts.IdleTimeout < time.Second {
+		log.Warn("Sanitizing invalid HTTP idle timeout", "provided", timeouts.IdleTimeout, "updated", DefaultHTTPTimeouts.IdleTimeout)
+		timeouts.IdleTimeout = DefaultHTTPTimeouts.IdleTimeout
+	}
+	// Bundle and start the HTTP server
+	return &http.Server{
+		Handler:      handler,
+		ReadTimeout:  timeouts.ReadTimeout,
+		WriteTimeout: timeouts.WriteTimeout,
+		IdleTimeout:  timeouts.IdleTimeout,
+	}
+}
+
+// ServeHTTP serves JSON-RPC requests over HTTP.
+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
+	}
+	if code, err := validateRequest(r); err != nil {
+		http.Error(w, err.Error(), code)
+		return
+	}
+	// All checks passed, create a codec that reads direct from the request body
+	// untilEOF and writes the response to w and order the server to process a
+	// single request.
+	ctx := r.Context()
+	ctx = context.WithValue(ctx, "remote", r.RemoteAddr)
+	ctx = context.WithValue(ctx, "scheme", r.Proto)
+	ctx = context.WithValue(ctx, "local", r.Host)
+	if ua := r.Header.Get("User-Agent"); ua != "" {
+		ctx = context.WithValue(ctx, "User-Agent", ua)
+	}
+	if origin := r.Header.Get("Origin"); origin != "" {
+		ctx = context.WithValue(ctx, "Origin", origin)
+	}
+
+	w.Header().Set("content-type", contentType)
+	codec := newHTTPServerConn(r, w)
+	defer codec.close()
+	s.serveSingleRequest(ctx, codec)
+}
+
+// validateRequest returns a non-zero response code and error message if the
+// request is invalid.
+func validateRequest(r *http.Request) (int, error) {
+	if r.Method == http.MethodPut || r.Method == http.MethodDelete {
+		return http.StatusMethodNotAllowed, errors.New("method not allowed")
+	}
+	if r.ContentLength > maxRequestContentLength {
+		err := fmt.Errorf("content length too large (%d>%d)", r.ContentLength, maxRequestContentLength)
+		return http.StatusRequestEntityTooLarge, err
+	}
+	// Allow OPTIONS (regardless of content-type)
+	if r.Method == http.MethodOptions {
+		return 0, nil
+	}
+	// Check content-type
+	if mt, _, err := mime.ParseMediaType(r.Header.Get("content-type")); err == nil {
+		for _, accepted := range acceptedContentTypes {
+			if accepted == mt {
+				return 0, nil
+			}
+		}
+	}
+	// Invalid content-type
+	err := fmt.Errorf("invalid content type, only %s is supported", contentType)
+	return http.StatusUnsupportedMediaType, err
+}
+
+func newCorsHandler(srv http.Handler, allowedOrigins []string) http.Handler {
+	// disable CORS support if user has not specified a custom CORS configuration
+	if len(allowedOrigins) == 0 {
+		return srv
+	}
+	c := cors.New(cors.Options{
+		AllowedOrigins: allowedOrigins,
+		AllowedMethods: []string{http.MethodPost, http.MethodGet},
+		MaxAge:         600,
+		AllowedHeaders: []string{"*"},
+	})
+	return c.Handler(srv)
+}
+
+// virtualHostHandler is a handler which validates the Host-header of incoming requests.
+// The virtualHostHandler can prevent DNS rebinding attacks, which do not utilize CORS-headers,
+// since they do in-domain requests against the RPC api. Instead, we can see on the Host-header
+// which domain was used, and validate that against a whitelist.
+type virtualHostHandler struct {
+	vhosts map[string]struct{}
+	next   http.Handler
+}
+
+// ServeHTTP serves JSON-RPC requests over HTTP, implements http.Handler
+func (h *virtualHostHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	// if r.Host is not set, we can continue serving since a browser would set the Host header
+	if r.Host == "" {
+		h.next.ServeHTTP(w, r)
+		return
+	}
+	host, _, err := net.SplitHostPort(r.Host)
+	if err != nil {
+		// Either invalid (too many colons) or no port specified
+		host = r.Host
+	}
+	if ipAddr := net.ParseIP(host); ipAddr != nil {
+		// It's an IP address, we can serve that
+		h.next.ServeHTTP(w, r)
+		return
+
+	}
+	// Not an ip address, but a hostname. Need to validate
+	if _, exist := h.vhosts["*"]; exist {
+		h.next.ServeHTTP(w, r)
+		return
+	}
+	if _, exist := h.vhosts[host]; exist {
+		h.next.ServeHTTP(w, r)
+		return
+	}
+	http.Error(w, "invalid host specified", http.StatusForbidden)
+}
+
+func newVHostHandler(vhosts []string, next http.Handler) http.Handler {
+	vhostMap := make(map[string]struct{})
+	for _, allowedHost := range vhosts {
+		vhostMap[strings.ToLower(allowedHost)] = struct{}{}
+	}
+	return &virtualHostHandler{vhostMap, next}
+}

eth/rpc/http_test.go

@@ -0,0 +1,54 @@
+// Copyright 2017 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 (
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+)
+
+func TestHTTPErrorResponseWithDelete(t *testing.T) {
+	testHTTPErrorResponse(t, http.MethodDelete, contentType, "", http.StatusMethodNotAllowed)
+}
+
+func TestHTTPErrorResponseWithPut(t *testing.T) {
+	testHTTPErrorResponse(t, http.MethodPut, contentType, "", http.StatusMethodNotAllowed)
+}
+
+func TestHTTPErrorResponseWithMaxContentLength(t *testing.T) {
+	body := make([]rune, maxRequestContentLength+1)
+	testHTTPErrorResponse(t,
+		http.MethodPost, contentType, string(body), http.StatusRequestEntityTooLarge)
+}
+
+func TestHTTPErrorResponseWithEmptyContentType(t *testing.T) {
+	testHTTPErrorResponse(t, http.MethodPost, "", "", http.StatusUnsupportedMediaType)
+}
+
+func TestHTTPErrorResponseWithValidRequest(t *testing.T) {
+	testHTTPErrorResponse(t, http.MethodPost, contentType, "", 0)
+}
+
+func testHTTPErrorResponse(t *testing.T, method, contentType, body string, expected int) {
+	request := httptest.NewRequest(method, "http://url.com", strings.NewReader(body))
+	request.Header.Set("content-type", contentType)
+	if code, _ := validateRequest(request); code != expected {
+		t.Fatalf("response code should be %d not %d", expected, code)
+	}
+}

eth/rpc/inproc.go

@@ -0,0 +1,33 @@
+// 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 (
+	"context"
+	"net"
+)
+
+// 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) (ServerCodec, error) {
+		p1, p2 := net.Pipe()
+		go handler.ServeCodec(NewCodec(p1), 0)
+		return NewCodec(p2), nil
+	})
+	return c
+}

eth/rpc/ipc.go

@@ -0,0 +1,56 @@
+// 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"
+	"net"
+
+	"github.com/ethereum/go-ethereum/log"
+	"github.com/ethereum/go-ethereum/p2p/netutil"
+)
+
+// ServeListener accepts connections on l, serving JSON-RPC on them.
+func (s *Server) ServeListener(l net.Listener) error {
+	for {
+		conn, err := l.Accept()
+		if netutil.IsTemporaryError(err) {
+			log.Warn("RPC accept error", "err", err)
+			continue
+		} else if err != nil {
+			return err
+		}
+		log.Trace("Accepted RPC connection", "conn", conn.RemoteAddr())
+		go s.ServeCodec(NewCodec(conn), 0)
+	}
+}
+
+// DialIPC create a new IPC client that connects to the given endpoint. On Unix it assumes
+// the endpoint is the full path to a unix socket, and Windows the endpoint is an
+// identifier for a named pipe.
+//
+// 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) (ServerCodec, error) {
+		conn, err := newIPCConnection(ctx, endpoint)
+		if err != nil {
+			return nil, err
+		}
+		return NewCodec(conn), err
+	})
+}

eth/rpc/ipc_js.go

@@ -0,0 +1,37 @@
+// 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/>.
+
+// +build js
+
+package rpc
+
+import (
+	"context"
+	"errors"
+	"net"
+)
+
+var errNotSupported = errors.New("rpc: not supported")
+
+// ipcListen will create a named pipe on the given endpoint.
+func ipcListen(endpoint string) (net.Listener, error) {
+	return nil, errNotSupported
+}
+
+// newIPCConnection will connect to a named pipe with the given endpoint as name.
+func newIPCConnection(ctx context.Context, endpoint string) (net.Conn, error) {
+	return nil, errNotSupported
+}

eth/rpc/ipc_unix.go

@@ -0,0 +1,54 @@
+// 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/>.
+
+// +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris
+
+package rpc
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"os"
+	"path/filepath"
+
+	"github.com/ethereum/go-ethereum/log"
+)
+
+// ipcListen will create a Unix socket on the given endpoint.
+func ipcListen(endpoint string) (net.Listener, error) {
+	if len(endpoint) > int(max_path_size) {
+		log.Warn(fmt.Sprintf("The ipc endpoint is longer than %d characters. ", max_path_size),
+			"endpoint", endpoint)
+	}
+
+	// Ensure the IPC path exists and remove any previous leftover
+	if err := os.MkdirAll(filepath.Dir(endpoint), 0751); err != nil {
+		return nil, err
+	}
+	os.Remove(endpoint)
+	l, err := net.Listen("unix", endpoint)
+	if err != nil {
+		return nil, err
+	}
+	os.Chmod(endpoint, 0600)
+	return l, nil
+}
+
+// newIPCConnection will connect to a Unix socket on the given endpoint.
+func newIPCConnection(ctx context.Context, endpoint string) (net.Conn, error) {
+	return new(net.Dialer).DialContext(ctx, "unix", endpoint)
+}

eth/rpc/ipc_windows.go

@@ -0,0 +1,48 @@
+// 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/>.
+
+// +build windows
+
+package rpc
+
+import (
+	"context"
+	"net"
+	"time"
+
+	"gopkg.in/natefinch/npipe.v2"
+)
+
+// This is used if the dialing context has no deadline. It is much smaller than the
+// defaultDialTimeout because named pipes are local and there is no need to wait so long.
+const defaultPipeDialTimeout = 2 * time.Second
+
+// ipcListen will create a named pipe on the given endpoint.
+func ipcListen(endpoint string) (net.Listener, error) {
+	return npipe.Listen(endpoint)
+}
+
+// newIPCConnection will connect to a named pipe with the given endpoint as name.
+func newIPCConnection(ctx context.Context, endpoint string) (net.Conn, error) {
+	timeout := defaultPipeDialTimeout
+	if deadline, ok := ctx.Deadline(); ok {
+		timeout = deadline.Sub(time.Now())
+		if timeout < 0 {
+			timeout = 0
+		}
+	}
+	return npipe.DialTimeout(endpoint, timeout)
+}

eth/rpc/json.go

@@ -0,0 +1,327 @@
+// 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 (
+	"bytes"
+	"context"
+	"errors"
+	"fmt"
+	"github.com/goccy/go-json"
+	"io"
+	"reflect"
+	"strings"
+	"sync"
+	"time"
+)
+
+const (
+	vsn                      = "2.0"
+	serviceMethodSeparator   = "_"
+	subscribeMethodSuffix    = "_subscribe"
+	unsubscribeMethodSuffix  = "_unsubscribe"
+	notificationMethodSuffix = "_subscription"
+
+	defaultWriteTimeout = 10 * time.Second // used if context has no deadline
+)
+
+var null = json.RawMessage("null")
+
+type subscriptionResult struct {
+	ID     string          `json:"subscription"`
+	Result json.RawMessage `json:"result,omitempty"`
+}
+
+// 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"`
+}
+
+func (msg *jsonrpcMessage) isNotification() bool {
+	return msg.ID == nil && msg.Method != ""
+}
+
+func (msg *jsonrpcMessage) isCall() bool {
+	return msg.hasValidID() && msg.Method != ""
+}
+
+func (msg *jsonrpcMessage) isResponse() bool {
+	return msg.hasValidID() && msg.Method == "" && msg.Params == nil && (msg.Result != nil || msg.Error != nil)
+}
+
+func (msg *jsonrpcMessage) hasValidID() bool {
+	return len(msg.ID) > 0 && msg.ID[0] != '{' && msg.ID[0] != '['
+}
+
+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 {
+	if err.Message == "" {
+		return fmt.Sprintf("json-rpc error %d", err.Code)
+	}
+	return err.Message
+}
+
+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
+}
+
+type deadlineCloser interface {
+	io.Closer
+	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
+}
+
+// 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 {
+	remote  string
+	closer  sync.Once                 // close closed channel once
+	closeCh 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    deadlineCloser
+}
+
+// NewFuncCodec creates a codec which uses the given functions to read and write. If conn
+// implements ConnRemoteAddr, log messages will use it to include the remote address of
+// the connection.
+func NewFuncCodec(conn deadlineCloser, encode, decode func(v interface{}) error) ServerCodec {
+	codec := &jsonCodec{
+		closeCh: make(chan interface{}),
+		encode:  encode,
+		decode:  decode,
+		conn:    conn,
+	}
+	if ra, ok := conn.(ConnRemoteAddr); ok {
+		codec.remote = ra.RemoteAddr()
+	}
+	return codec
+}
+
+// NewCodec creates a codec on the given connection. If conn implements ConnRemoteAddr, log
+// messages will use it to include the remote address of the connection.
+func NewCodec(conn Conn) ServerCodec {
+	enc := json.NewEncoder(conn)
+	dec := json.NewDecoder(conn)
+	dec.UseNumber()
+	return NewFuncCodec(conn, enc.Encode, dec.Decode)
+}
+
+func (c *jsonCodec) remoteAddr() string {
+	return c.remote
+}
+
+func (c *jsonCodec) readBatch() (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
+	}
+	msg, batch = parseMessage(rawmsg)
+	return msg, batch, nil
+}
+
+func (c *jsonCodec) writeJSON(ctx context.Context, v interface{}) error {
+	c.encMu.Lock()
+	defer c.encMu.Unlock()
+
+	deadline, ok := ctx.Deadline()
+	if !ok {
+		deadline = time.Now().Add(defaultWriteTimeout)
+	}
+	c.conn.SetWriteDeadline(deadline)
+	return c.encode(v)
+}
+
+func (c *jsonCodec) close() {
+	c.closer.Do(func() {
+		close(c.closeCh)
+		c.conn.Close()
+	})
+}
+
+// Closed returns a channel which will be closed when Close is called
+func (c *jsonCodec) closed() <-chan interface{} {
+	return c.closeCh
+}
+
+// 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
+	}
+	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 msgs, true
+}
+
+// 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
+		}
+		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) {
+	dec := json.NewDecoder(bytes.NewReader(rawArgs))
+	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")
+	}
+	// 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 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 args, fmt.Errorf("invalid argument %d: %v", i, err)
+		}
+		if argval.IsNil() && types[i].Kind() != reflect.Ptr {
+			return args, fmt.Errorf("missing value for required argument %d", i)
+		}
+		args = append(args, argval.Elem())
+	}
+	// Read end of args array.
+	_, err := dec.Token()
+	return args, err
+}
+
+// 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
+}

eth/rpc/server.go

@@ -0,0 +1,147 @@
+// 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"
+	"io"
+	"sync/atomic"
+
+	mapset "github.com/deckarep/golang-set"
+	"github.com/ethereum/go-ethereum/log"
+)
+
+const MetadataApi = "rpc"
+
+// CodecOption specifies which type of messages a codec supports.
+//
+// Deprecated: this option is no longer honored by Server.
+type CodecOption int
+
+const (
+	// OptionMethodInvocation is an indication that the codec supports RPC method calls
+	OptionMethodInvocation CodecOption = 1 << iota
+
+	// OptionSubscriptions is an indication that the codec suports RPC notifications
+	OptionSubscriptions = 1 << iota // support pub sub
+)
+
+// Server is an RPC server.
+type Server struct {
+	services serviceRegistry
+	idgen    func() ID
+	run      int32
+	codecs   mapset.Set
+}
+
+// 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
+}
+
+// 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)
+}
+
+// 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()
+
+	// Don't serve if server is stopped.
+	if atomic.LoadInt32(&s.run) == 0 {
+		return
+	}
+
+	// Add the codec to the set so it can be closed by Stop.
+	s.codecs.Add(codec)
+	defer s.codecs.Remove(codec)
+
+	c := initClient(codec, s.idgen, &s.services)
+	<-codec.closed()
+	c.Close()
+}
+
+// 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
+	}
+
+	h := newHandler(ctx, codec, s.idgen, &s.services)
+	h.allowSubscribe = false
+	defer h.close(io.EOF, nil)
+
+	reqs, batch, err := codec.readBatch()
+	if err != nil {
+		if err != io.EOF {
+			codec.writeJSON(ctx, errorMessage(&invalidMessageError{"parse error"}))
+		}
+		return
+	}
+	if batch {
+		h.handleBatch(reqs)
+	} else {
+		h.handleMsg(reqs[0])
+	}
+}
+
+// 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 shutting down")
+		s.codecs.Each(func(c interface{}) bool {
+			c.(ServerCodec).close()
+			return true
+		})
+	}
+}
+
+// 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 {
+	s.server.services.mu.Lock()
+	defer s.server.services.mu.Unlock()
+
+	modules := make(map[string]string)
+	for name := range s.server.services.services {
+		modules[name] = "1.0"
+	}
+	return modules
+}

eth/rpc/server_test.go

@@ -0,0 +1,152 @@
+// 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"
+	"io"
+	"io/ioutil"
+	"net"
+	"path/filepath"
+	"strings"
+	"testing"
+	"time"
+)
+
+func TestServerRegisterName(t *testing.T) {
+	server := NewServer()
+	service := new(testService)
+
+	if err := server.RegisterName("test", service); err != nil {
+		t.Fatalf("%v", err)
+	}
+
+	if len(server.services.services) != 2 {
+		t.Fatalf("Expected 2 service entries, got %d", len(server.services.services))
+	}
+
+	svc, ok := server.services.services["test"]
+	if !ok {
+		t.Fatalf("Expected service calc to be registered")
+	}
+
+	wantCallbacks := 7
+	if len(svc.callbacks) != wantCallbacks {
+		t.Errorf("Expected %d callbacks for service 'service', got %d", wantCallbacks, len(svc.callbacks))
+	}
+}
+
+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)
+		})
+	}
+}
+
+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(NewCodec(serverConn), 0)
+	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)
+		}
+	}
+}
+
+// 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()
+
+	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)
+		}
+		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 !bytes.Equal(buf[:n], []byte(wantResp)) {
+			t.Fatalf("wrong response: %s", buf[:n])
+		}
+	}
+}

eth/rpc/service.go

@@ -0,0 +1,261 @@
+// Copyright 2019 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"
+
+	"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()
+
+	// 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 {
+		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 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)
+}

eth/rpc/stdio.go

@@ -0,0 +1,66 @@
+// 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"
+	"errors"
+	"io"
+	"net"
+	"os"
+	"time"
+)
+
+// DialStdIO creates a client on stdin/stdout.
+func DialStdIO(ctx context.Context) (*Client, error) {
+	return DialIO(ctx, os.Stdin, os.Stdout)
+}
+
+// DialIO creates a client which uses the given IO channels
+func DialIO(ctx context.Context, in io.Reader, out io.Writer) (*Client, error) {
+	return newClient(ctx, func(_ context.Context) (ServerCodec, error) {
+		return NewCodec(stdioConn{
+			in:  in,
+			out: out,
+		}), nil
+	})
+}
+
+type stdioConn struct {
+	in  io.Reader
+	out io.Writer
+}
+
+func (io stdioConn) Read(b []byte) (n int, err error) {
+	return io.in.Read(b)
+}
+
+func (io stdioConn) Write(b []byte) (n int, err error) {
+	return io.out.Write(b)
+}
+
+func (io stdioConn) Close() error {
+	return nil
+}
+
+func (io stdioConn) RemoteAddr() string {
+	return "/dev/stdin"
+}
+
+func (io stdioConn) SetWriteDeadline(t time.Time) error {
+	return &net.OpError{Op: "set", Net: "stdio", Source: nil, Addr: nil, Err: errors.New("deadline not supported")}
+}

eth/rpc/subscription.go

@@ -0,0 +1,327 @@
+// 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 (
+	"bufio"
+	"container/list"
+	"context"
+	crand "crypto/rand"
+	"encoding/binary"
+	"encoding/hex"
+	"errors"
+	"github.com/goccy/go-json"
+	"math/rand"
+	"reflect"
+	"strings"
+	"sync"
+	"time"
+)
+
+var (
+	// ErrNotificationsUnsupported is returned when the connection doesn't support notifications
+	ErrNotificationsUnsupported = errors.New("notifications not supported")
+	// ErrNotificationNotFound is returned when the notification for the given id is not found
+	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
+
+// NewID returns a new, random ID.
+func NewID() ID {
+	return globalGen()
+}
+
+// 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)
+	}
+}
+
+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 {
+	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 {
+	enc, err := json.Marshal(data)
+	if err != nil {
+		return err
+	}
+
+	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
+}
+
+// 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
+		}
+	}
+	n.activated = true
+	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.writeJSON(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 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(true, nil)
+	sub.errOnce.Do(func() { close(sub.err) })
+}
+
+func (sub *ClientSubscription) quitWithError(unsubscribeServer bool, err error) {
+	sub.quitOnce.Do(func() {
+		// The dispatch loop won't be able to execute the unsubscribe call
+		// if it is blocked on deliver. Close sub.quit first because it
+		// unblocks deliver.
+		close(sub.quit)
+		if unsubscribeServer {
+			sub.requestUnsubscribe()
+		}
+		if err != nil {
+			if err == ErrClientQuit {
+				err = nil // Adhere to subscription semantics.
+			}
+			sub.err <- err
+		}
+	})
+}
+
+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() (unsubscribeServer bool, err error) {
+	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 false, nil
+		case 1: // <-sub.in
+			val, err := sub.unmarshal(recv.Interface().(json.RawMessage))
+			if err != nil {
+				return true, err
+			}
+			if buffer.Len() == maxClientSubscriptionBuffer {
+				return true, ErrSubscriptionQueueOverflow
+			}
+			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)
+}

eth/rpc/subscription_test.go

@@ -0,0 +1,206 @@
+// 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 (
+	"fmt"
+	"github.com/goccy/go-json"
+	"net"
+	"strings"
+	"testing"
+	"time"
+)
+
+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])
+			}
+		}
+	}
+}
+
+func TestSubscriptions(t *testing.T) {
+	var (
+		namespaces        = []string{"eth", "shh", "bzz"}
+		service           = &notificationTestService{}
+		subCount          = len(namespaces)
+		notificationCount = 3
+
+		server                 = NewServer()
+		clientConn, serverConn = net.Pipe()
+		out                    = json.NewEncoder(clientConn)
+		in                     = json.NewDecoder(clientConn)
+		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 {
+			t.Fatalf("unable to register test service %v", err)
+		}
+	}
+	go server.ServeCodec(NewCodec(serverConn), 0)
+	defer server.Stop()
+
+	// wait for message and write them to the given channels
+	go waitForMessages(in, successes, notifications, errors)
+
+	// create subscriptions one by one
+	for i, namespace := range namespaces {
+		request := map[string]interface{}{
+			"id":      i,
+			"method":  fmt.Sprintf("%s_subscribe", namespace),
+			"version": "2.0",
+			"params":  []interface{}{"someSubscription", notificationCount, i},
+		}
+		if err := out.Encode(&request); err != nil {
+			t.Fatalf("Could not create subscription: %v", err)
+		}
+	}
+
+	timeout := time.After(30 * time.Second)
+	subids := make(map[string]string, subCount)
+	count := make(map[string]int, subCount)
+	allReceived := func() bool {
+		done := len(count) == subCount
+		for _, c := range count {
+			if c < notificationCount {
+				done = false
+			}
+		}
+		return done
+	}
+	for !allReceived() {
+		select {
+		case confirmation := <-successes: // subscription created
+			subids[namespaces[confirmation.reqid]] = string(confirmation.subid)
+		case notification := <-notifications:
+			count[notification.ID]++
+		case err := <-errors:
+			t.Fatal(err)
+		case <-timeout:
+			for _, namespace := range namespaces {
+				subid, found := subids[namespace]
+				if !found {
+					t.Errorf("subscription for %q not created", namespace)
+					continue
+				}
+				if count, found := count[subid]; !found || count < notificationCount {
+					t.Errorf("didn't receive all notifications (%d<%d) in time for namespace %q", count, notificationCount, namespace)
+				}
+			}
+			t.Fatal("timed out")
+		}
+	}
+}
+
+// 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(NewCodec(p1), 0)
+
+	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
+		}
+	}
+}

eth/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"}}

eth/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"}}]

eth/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"}}

eth/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"}}

eth/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"}}
+

eth/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}}]

eth/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"}}}

eth/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"}}

eth/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}

eth/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"}}

eth/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}

eth/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}

eth/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"}

eth/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"}
+

eth/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}

eth/rpc/testservice_test.go

@@ -0,0 +1,181 @@
+// Copyright 2019 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 echoArgs struct {
+	S string
+}
+
+type echoResult struct {
+	String string
+	Int    int
+	Args   *echoArgs
+}
+
+func (s *testService) NoArgsRets() {}
+
+func (s *testService) Echo(str string, i int, args *echoArgs) echoResult {
+	return echoResult{str, i, args}
+}
+
+func (s *testService) EchoWithCtx(ctx context.Context, str string, i int, args *echoArgs) echoResult {
+	return echoResult{str, i, args}
+}
+
+func (s *testService) Sleep(ctx context.Context, duration time.Duration) {
+	time.Sleep(duration)
+}
+
+func (s *testService) Rets() (string, error) {
+	return "", nil
+}
+
+//lint:ignore ST1008 returns error first on purpose.
+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
+}

eth/rpc/types.go

@@ -0,0 +1,199 @@
+// 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"
+	"fmt"
+	"github.com/goccy/go-json"
+	"math"
+	"strings"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/common/hexutil"
+)
+
+// API describes the set of methods offered over the RPC interface
+type API struct {
+	Namespace string      // namespace under which the rpc methods of Service are exposed
+	Version   string      // api version for DApp's
+	Service   interface{} // receiver instance which holds the methods
+	Public    bool        // indication if the methods must be considered safe for public use
+}
+
+// Error wraps RPC errors, which contain an error code in addition to the message.
+type Error interface {
+	Error() string  // returns the message
+	ErrorCode() int // returns the code
+}
+
+// ServerCodec implements reading, parsing and writing RPC messages for the server side of
+// a RPC session. Implementations must be go-routine safe since the codec can be called in
+// multiple go-routines concurrently.
+type ServerCodec interface {
+	readBatch() (msgs []*jsonrpcMessage, isBatch bool, err error)
+	close()
+	jsonWriter
+}
+
+// jsonWriter can write JSON messages to its underlying connection.
+// Implementations must be safe for concurrent use.
+type jsonWriter interface {
+	writeJSON(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
+
+const (
+	PendingBlockNumber  = BlockNumber(-2)
+	LatestBlockNumber   = BlockNumber(-1)
+	EarliestBlockNumber = BlockNumber(0)
+)
+
+// UnmarshalJSON parses the given JSON fragment into a BlockNumber. It supports:
+// - "latest", "earliest" or "pending" as string arguments
+// - the block number
+// Returned errors:
+// - an invalid block number error when the given argument isn't a known strings
+// - an out of range error when the given block number is either too little or too large
+func (bn *BlockNumber) UnmarshalJSON(data []byte) error {
+	input := strings.TrimSpace(string(data))
+	if len(input) >= 2 && input[0] == '"' && input[len(input)-1] == '"' {
+		input = input[1 : len(input)-1]
+	}
+
+	switch input {
+	case "earliest":
+		*bn = EarliestBlockNumber
+		return nil
+	case "latest":
+		*bn = LatestBlockNumber
+		return nil
+	case "pending":
+		*bn = PendingBlockNumber
+		return nil
+	}
+
+	blckNum, err := hexutil.DecodeUint64(input)
+	if err != nil {
+		return err
+	}
+	if blckNum > math.MaxInt64 {
+		return fmt.Errorf("block number larger than int64")
+	}
+	*bn = BlockNumber(blckNum)
+	return nil
+}
+
+func (bn BlockNumber) Int64() int64 {
+	return (int64)(bn)
+}
+
+type BlockNumberOrHash struct {
+	BlockNumber      *BlockNumber `json:"blockNumber,omitempty"`
+	BlockHash        *common.Hash `json:"blockHash,omitempty"`
+	RequireCanonical bool         `json:"requireCanonical,omitempty"`
+}
+
+func (bnh *BlockNumberOrHash) UnmarshalJSON(data []byte) error {
+	type erased BlockNumberOrHash
+	e := erased{}
+	err := json.Unmarshal(data, &e)
+	if err == nil {
+		if e.BlockNumber != nil && e.BlockHash != nil {
+			return fmt.Errorf("cannot specify both BlockHash and BlockNumber, choose one or the other")
+		}
+		bnh.BlockNumber = e.BlockNumber
+		bnh.BlockHash = e.BlockHash
+		bnh.RequireCanonical = e.RequireCanonical
+		return nil
+	}
+	var input string
+	err = json.Unmarshal(data, &input)
+	if err != nil {
+		return err
+	}
+	switch input {
+	case "earliest":
+		bn := EarliestBlockNumber
+		bnh.BlockNumber = &bn
+		return nil
+	case "latest":
+		bn := LatestBlockNumber
+		bnh.BlockNumber = &bn
+		return nil
+	case "pending":
+		bn := PendingBlockNumber
+		bnh.BlockNumber = &bn
+		return nil
+	default:
+		if len(input) == 66 {
+			hash := common.Hash{}
+			err := hash.UnmarshalText([]byte(input))
+			if err != nil {
+				return err
+			}
+			bnh.BlockHash = &hash
+			return nil
+		} else {
+			blckNum, err := hexutil.DecodeUint64(input)
+			if err != nil {
+				return err
+			}
+			if blckNum > math.MaxInt64 {
+				return fmt.Errorf("blocknumber too high")
+			}
+			bn := BlockNumber(blckNum)
+			bnh.BlockNumber = &bn
+			return nil
+		}
+	}
+}
+
+func (bnh *BlockNumberOrHash) Number() (BlockNumber, bool) {
+	if bnh.BlockNumber != nil {
+		return *bnh.BlockNumber, true
+	}
+	return BlockNumber(0), false
+}
+
+func (bnh *BlockNumberOrHash) Hash() (common.Hash, bool) {
+	if bnh.BlockHash != nil {
+		return *bnh.BlockHash, true
+	}
+	return common.Hash{}, false
+}
+
+func BlockNumberOrHashWithNumber(blockNr BlockNumber) BlockNumberOrHash {
+	return BlockNumberOrHash{
+		BlockNumber:      &blockNr,
+		BlockHash:        nil,
+		RequireCanonical: false,
+	}
+}
+
+func BlockNumberOrHashWithHash(hash common.Hash, canonical bool) BlockNumberOrHash {
+	return BlockNumberOrHash{
+		BlockNumber:      nil,
+		BlockHash:        &hash,
+		RequireCanonical: canonical,
+	}
+}

eth/rpc/types_test.go

@@ -0,0 +1,124 @@
+// 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 (
+	"github.com/goccy/go-json"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/common/math"
+)
+
+func TestBlockNumberJSONUnmarshal(t *testing.T) {
+	tests := []struct {
+		input    string
+		mustFail bool
+		expected BlockNumber
+	}{
+		0:  {`"0x"`, true, BlockNumber(0)},
+		1:  {`"0x0"`, false, BlockNumber(0)},
+		2:  {`"0X1"`, false, BlockNumber(1)},
+		3:  {`"0x00"`, true, BlockNumber(0)},
+		4:  {`"0x01"`, true, BlockNumber(0)},
+		5:  {`"0x1"`, false, BlockNumber(1)},
+		6:  {`"0x12"`, false, BlockNumber(18)},
+		7:  {`"0x7fffffffffffffff"`, false, BlockNumber(math.MaxInt64)},
+		8:  {`"0x8000000000000000"`, true, BlockNumber(0)},
+		9:  {"0", true, BlockNumber(0)},
+		10: {`"ff"`, true, BlockNumber(0)},
+		11: {`"pending"`, false, PendingBlockNumber},
+		12: {`"latest"`, false, LatestBlockNumber},
+		13: {`"earliest"`, false, EarliestBlockNumber},
+		14: {`someString`, true, BlockNumber(0)},
+		15: {`""`, true, BlockNumber(0)},
+		16: {``, true, BlockNumber(0)},
+	}
+
+	for i, test := range tests {
+		var num BlockNumber
+		err := json.Unmarshal([]byte(test.input), &num)
+		if test.mustFail && err == nil {
+			t.Errorf("Test %d should fail", i)
+			continue
+		}
+		if !test.mustFail && err != nil {
+			t.Errorf("Test %d should pass but got err: %v", i, err)
+			continue
+		}
+		if num != test.expected {
+			t.Errorf("Test %d got unexpected value, want %d, got %d", i, test.expected, num)
+		}
+	}
+}
+
+func TestBlockNumberOrHash_UnmarshalJSON(t *testing.T) {
+	tests := []struct {
+		input    string
+		mustFail bool
+		expected BlockNumberOrHash
+	}{
+		0:  {`"0x"`, true, BlockNumberOrHash{}},
+		1:  {`"0x0"`, false, BlockNumberOrHashWithNumber(0)},
+		2:  {`"0X1"`, false, BlockNumberOrHashWithNumber(1)},
+		3:  {`"0x00"`, true, BlockNumberOrHash{}},
+		4:  {`"0x01"`, true, BlockNumberOrHash{}},
+		5:  {`"0x1"`, false, BlockNumberOrHashWithNumber(1)},
+		6:  {`"0x12"`, false, BlockNumberOrHashWithNumber(18)},
+		7:  {`"0x7fffffffffffffff"`, false, BlockNumberOrHashWithNumber(math.MaxInt64)},
+		8:  {`"0x8000000000000000"`, true, BlockNumberOrHash{}},
+		9:  {"0", true, BlockNumberOrHash{}},
+		10: {`"ff"`, true, BlockNumberOrHash{}},
+		11: {`"pending"`, false, BlockNumberOrHashWithNumber(PendingBlockNumber)},
+		12: {`"latest"`, false, BlockNumberOrHashWithNumber(LatestBlockNumber)},
+		13: {`"earliest"`, false, BlockNumberOrHashWithNumber(EarliestBlockNumber)},
+		14: {`someString`, true, BlockNumberOrHash{}},
+		15: {`""`, true, BlockNumberOrHash{}},
+		16: {``, true, BlockNumberOrHash{}},
+		17: {`"0x0000000000000000000000000000000000000000000000000000000000000000"`, false, BlockNumberOrHashWithHash(common.HexToHash("0x0000000000000000000000000000000000000000000000000000000000000000"), false)},
+		18: {`{"blockHash":"0x0000000000000000000000000000000000000000000000000000000000000000"}`, false, BlockNumberOrHashWithHash(common.HexToHash("0x0000000000000000000000000000000000000000000000000000000000000000"), false)},
+		19: {`{"blockHash":"0x0000000000000000000000000000000000000000000000000000000000000000","requireCanonical":false}`, false, BlockNumberOrHashWithHash(common.HexToHash("0x0000000000000000000000000000000000000000000000000000000000000000"), false)},
+		20: {`{"blockHash":"0x0000000000000000000000000000000000000000000000000000000000000000","requireCanonical":true}`, false, BlockNumberOrHashWithHash(common.HexToHash("0x0000000000000000000000000000000000000000000000000000000000000000"), true)},
+		21: {`{"blockNumber":"0x1"}`, false, BlockNumberOrHashWithNumber(1)},
+		22: {`{"blockNumber":"pending"}`, false, BlockNumberOrHashWithNumber(PendingBlockNumber)},
+		23: {`{"blockNumber":"latest"}`, false, BlockNumberOrHashWithNumber(LatestBlockNumber)},
+		24: {`{"blockNumber":"earliest"}`, false, BlockNumberOrHashWithNumber(EarliestBlockNumber)},
+		25: {`{"blockNumber":"0x1", "blockHash":"0x0000000000000000000000000000000000000000000000000000000000000000"}`, true, BlockNumberOrHash{}},
+	}
+
+	for i, test := range tests {
+		var bnh BlockNumberOrHash
+		err := json.Unmarshal([]byte(test.input), &bnh)
+		if test.mustFail && err == nil {
+			t.Errorf("Test %d should fail", i)
+			continue
+		}
+		if !test.mustFail && err != nil {
+			t.Errorf("Test %d should pass but got err: %v", i, err)
+			continue
+		}
+		hash, hashOk := bnh.Hash()
+		expectedHash, expectedHashOk := test.expected.Hash()
+		num, numOk := bnh.Number()
+		expectedNum, expectedNumOk := test.expected.Number()
+		if bnh.RequireCanonical != test.expected.RequireCanonical ||
+			hash != expectedHash || hashOk != expectedHashOk ||
+			num != expectedNum || numOk != expectedNumOk {
+			t.Errorf("Test %d got unexpected value, want %v, got %v", i, test.expected, bnh)
+		}
+	}
+}

eth/rpc/websocket.go

@@ -0,0 +1,175 @@
+// 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"
+	"encoding/base64"
+	"fmt"
+	"net/http"
+	"net/url"
+	"os"
+	"strings"
+	"sync"
+
+	mapset "github.com/deckarep/golang-set"
+	"github.com/ethereum/go-ethereum/log"
+	"github.com/gorilla/websocket"
+)
+
+const (
+	wsReadBuffer  = 1024
+	wsWriteBuffer = 1024
+)
+
+var wsBufferPool = new(sync.Pool)
+
+// NewWSServer creates a new websocket RPC server around an API provider.
+//
+// Deprecated: use Server.WebsocketHandler
+func NewWSServer(allowedOrigins []string, srv *Server) *http.Server {
+	return &http.Server{Handler: srv.WebsocketHandler(allowedOrigins)}
+}
+
+// WebsocketHandler returns a handler that serves JSON-RPC to WebSocket connections.
+//
+// allowedOrigins should be a comma-separated list of allowed origin URLs.
+// To allow connections with any origin, pass "*".
+func (s *Server) WebsocketHandler(allowedOrigins []string) http.Handler {
+	var upgrader = websocket.Upgrader{
+		ReadBufferSize:  wsReadBuffer,
+		WriteBufferSize: wsWriteBuffer,
+		WriteBufferPool: wsBufferPool,
+		CheckOrigin:     wsHandshakeValidator(allowedOrigins),
+	}
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		conn, err := upgrader.Upgrade(w, r, nil)
+		if err != nil {
+			log.Debug("WebSocket upgrade failed", "err", err)
+			return
+		}
+		codec := newWebsocketCodec(conn)
+		s.ServeCodec(codec, 0)
+	})
+}
+
+// wsHandshakeValidator returns a handler that verifies the origin during the
+// websocket upgrade process. When a '*' is specified as an allowed origins all
+// connections are accepted.
+func wsHandshakeValidator(allowedOrigins []string) func(*http.Request) bool {
+	origins := mapset.NewSet()
+	allowAllOrigins := false
+
+	for _, origin := range allowedOrigins {
+		if origin == "*" {
+			allowAllOrigins = true
+		}
+		if origin != "" {
+			origins.Add(strings.ToLower(origin))
+		}
+	}
+	// allow localhost if no allowedOrigins are specified.
+	if len(origins.ToSlice()) == 0 {
+		origins.Add("http://localhost")
+		if hostname, err := os.Hostname(); err == nil {
+			origins.Add("http://" + strings.ToLower(hostname))
+		}
+	}
+	log.Debug(fmt.Sprintf("Allowed origin(s) for WS RPC interface %v", origins.ToSlice()))
+
+	f := func(req *http.Request) bool {
+		// Skip origin verification if no Origin header is present. The origin check
+		// is supposed to protect against browser based attacks. Browsers always set
+		// Origin. Non-browser software can put anything in origin and checking it doesn't
+		// provide additional security.
+		if _, ok := req.Header["Origin"]; !ok {
+			return true
+		}
+		// Verify origin against whitelist.
+		origin := strings.ToLower(req.Header.Get("Origin"))
+		if allowAllOrigins || origins.Contains(origin) {
+			return true
+		}
+		log.Warn("Rejected WebSocket connection", "origin", origin)
+		return false
+	}
+
+	return f
+}
+
+type wsHandshakeError struct {
+	err    error
+	status string
+}
+
+func (e wsHandshakeError) Error() string {
+	s := e.err.Error()
+	if e.status != "" {
+		s += " (HTTP status " + e.status + ")"
+	}
+	return s
+}
+
+// DialWebsocket creates a new RPC client that communicates with a JSON-RPC server
+// that is listening on the given endpoint.
+//
+// The context is used for the initial connection establishment. It does not
+// affect subsequent interactions with the client.
+func DialWebsocket(ctx context.Context, endpoint, origin string) (*Client, error) {
+	endpoint, header, err := wsClientHeaders(endpoint, origin)
+	if err != nil {
+		return nil, err
+	}
+	dialer := websocket.Dialer{
+		ReadBufferSize:  wsReadBuffer,
+		WriteBufferSize: wsWriteBuffer,
+		WriteBufferPool: wsBufferPool,
+	}
+	return newClient(ctx, func(ctx context.Context) (ServerCodec, error) {
+		conn, resp, err := dialer.DialContext(ctx, endpoint, header)
+		if err != nil {
+			hErr := wsHandshakeError{err: err}
+			if resp != nil {
+				hErr.status = resp.Status
+			}
+			return nil, hErr
+		}
+		return newWebsocketCodec(conn), nil
+	})
+}
+
+func wsClientHeaders(endpoint, origin string) (string, http.Header, error) {
+	endpointURL, err := url.Parse(endpoint)
+	if err != nil {
+		return endpoint, nil, err
+	}
+	header := make(http.Header)
+	if origin != "" {
+		header.Add("origin", origin)
+	}
+	if endpointURL.User != nil {
+		b64auth := base64.StdEncoding.EncodeToString([]byte(endpointURL.User.String()))
+		header.Add("authorization", "Basic "+b64auth)
+		endpointURL.User = nil
+	}
+	return endpointURL.String(), header, nil
+}
+
+func newWebsocketCodec(conn *websocket.Conn) ServerCodec {
+	conn.SetReadLimit(maxRequestContentLength)
+	return NewFuncCodec(conn, conn.WriteJSON, conn.ReadJSON)
+}

eth/rpc/websocket_test.go

@@ -0,0 +1,259 @@
+// 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"
+	"net"
+	"net/http"
+	"net/http/httptest"
+	"reflect"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/gorilla/websocket"
+)
+
+func TestWebsocketClientHeaders(t *testing.T) {
+	t.Parallel()
+
+	endpoint, header, err := wsClientHeaders("wss://testuser:test-PASS_01@example.com:1234", "https://example.com")
+	if err != nil {
+		t.Fatalf("wsGetConfig failed: %s", err)
+	}
+	if endpoint != "wss://example.com:1234" {
+		t.Fatal("User should have been stripped from the URL")
+	}
+	if header.Get("authorization") != "Basic dGVzdHVzZXI6dGVzdC1QQVNTXzAx" {
+		t.Fatal("Basic auth header is incorrect")
+	}
+	if header.Get("origin") != "https://example.com" {
+		t.Fatal("Origin not set")
+	}
+}
+
+// This test checks that the server rejects connections from disallowed origins.
+func TestWebsocketOriginCheck(t *testing.T) {
+	t.Parallel()
+
+	var (
+		srv     = newTestServer()
+		httpsrv = httptest.NewServer(srv.WebsocketHandler([]string{"http://example.com"}))
+		wsURL   = "ws:" + strings.TrimPrefix(httpsrv.URL, "http:")
+	)
+	defer srv.Stop()
+	defer httpsrv.Close()
+
+	client, err := DialWebsocket(context.Background(), wsURL, "http://ekzample.com")
+	if err == nil {
+		client.Close()
+		t.Fatal("no error for wrong origin")
+	}
+	wantErr := wsHandshakeError{websocket.ErrBadHandshake, "403 Forbidden"}
+	if !reflect.DeepEqual(err, wantErr) {
+		t.Fatalf("wrong error for wrong origin: %q", err)
+	}
+
+	// Connections without origin header should work.
+	client, err = DialWebsocket(context.Background(), wsURL, "")
+	if err != nil {
+		t.Fatal("error for empty origin")
+	}
+	client.Close()
+}
+
+// This test checks whether calls exceeding the request size limit are rejected.
+func TestWebsocketLargeCall(t *testing.T) {
+	t.Parallel()
+
+	var (
+		srv     = newTestServer()
+		httpsrv = httptest.NewServer(srv.WebsocketHandler([]string{"*"}))
+		wsURL   = "ws:" + strings.TrimPrefix(httpsrv.URL, "http:")
+	)
+	defer srv.Stop()
+	defer httpsrv.Close()
+
+	client, err := DialWebsocket(context.Background(), wsURL, "")
+	if err != nil {
+		t.Fatalf("can't dial: %v", err)
+	}
+	defer client.Close()
+
+	// This call sends slightly less than the limit and should work.
+	var result echoResult
+	arg := strings.Repeat("x", maxRequestContentLength-200)
+	if err := client.Call(&result, "test_echo", arg, 1); err != nil {
+		t.Fatalf("valid call didn't work: %v", err)
+	}
+	if result.String != arg {
+		t.Fatal("wrong string echoed")
+	}
+
+	// This call sends twice the allowed size and shouldn't work.
+	arg = strings.Repeat("x", maxRequestContentLength*2)
+	err = client.Call(&result, "test_echo", arg)
+	if err == nil {
+		t.Fatal("no error for too large call")
+	}
+}
+
+// This test checks that client handles WebSocket ping frames correctly.
+func TestClientWebsocketPing(t *testing.T) {
+	t.Parallel()
+
+	var (
+		sendPing    = make(chan struct{})
+		server      = wsPingTestServer(t, sendPing)
+		ctx, cancel = context.WithTimeout(context.Background(), 1*time.Second)
+	)
+	defer cancel()
+	defer server.Shutdown(ctx)
+
+	client, err := DialContext(ctx, "ws://"+server.Addr)
+	if err != nil {
+		t.Fatalf("client dial error: %v", err)
+	}
+	resultChan := make(chan int)
+	sub, err := client.EthSubscribe(ctx, resultChan, "foo")
+	if err != nil {
+		t.Fatalf("client subscribe error: %v", err)
+	}
+
+	// Wait for the context's deadline to be reached before proceeding.
+	// This is important for reproducing https://github.com/ethereum/go-ethereum/issues/19798
+	<-ctx.Done()
+	close(sendPing)
+
+	// Wait for the subscription result.
+	timeout := time.NewTimer(5 * time.Second)
+	for {
+		select {
+		case err := <-sub.Err():
+			t.Error("client subscription error:", err)
+		case result := <-resultChan:
+			t.Log("client got result:", result)
+			return
+		case <-timeout.C:
+			t.Error("didn't get any result within the test timeout")
+			return
+		}
+	}
+}
+
+// wsPingTestServer runs a WebSocket server which accepts a single subscription request.
+// When a value arrives on sendPing, the server sends a ping frame, waits for a matching
+// pong and finally delivers a single subscription result.
+func wsPingTestServer(t *testing.T, sendPing <-chan struct{}) *http.Server {
+	var srv http.Server
+	shutdown := make(chan struct{})
+	srv.RegisterOnShutdown(func() {
+		close(shutdown)
+	})
+	srv.Handler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		// Upgrade to WebSocket.
+		upgrader := websocket.Upgrader{
+			CheckOrigin: func(r *http.Request) bool { return true },
+		}
+		conn, err := upgrader.Upgrade(w, r, nil)
+		if err != nil {
+			t.Errorf("server WS upgrade error: %v", err)
+			return
+		}
+		defer conn.Close()
+
+		// Handle the connection.
+		wsPingTestHandler(t, conn, shutdown, sendPing)
+	})
+
+	// Start the server.
+	listener, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatal("can't listen:", err)
+	}
+	srv.Addr = listener.Addr().String()
+	go srv.Serve(listener)
+	return &srv
+}
+
+func wsPingTestHandler(t *testing.T, conn *websocket.Conn, shutdown, sendPing <-chan struct{}) {
+	// Canned responses for the eth_subscribe call in TestClientWebsocketPing.
+	const (
+		subResp   = `{"jsonrpc":"2.0","id":1,"result":"0x00"}`
+		subNotify = `{"jsonrpc":"2.0","method":"eth_subscription","params":{"subscription":"0x00","result":1}}`
+	)
+
+	// Handle subscribe request.
+	if _, _, err := conn.ReadMessage(); err != nil {
+		t.Errorf("server read error: %v", err)
+		return
+	}
+	if err := conn.WriteMessage(websocket.TextMessage, []byte(subResp)); err != nil {
+		t.Errorf("server write error: %v", err)
+		return
+	}
+
+	// Read from the connection to process control messages.
+	var pongCh = make(chan string)
+	conn.SetPongHandler(func(d string) error {
+		t.Logf("server got pong: %q", d)
+		pongCh <- d
+		return nil
+	})
+	go func() {
+		for {
+			typ, msg, err := conn.ReadMessage()
+			if err != nil {
+				return
+			}
+			t.Logf("server got message (%d): %q", typ, msg)
+		}
+	}()
+
+	// Write messages.
+	var (
+		sendResponse <-chan time.Time
+		wantPong     string
+	)
+	for {
+		select {
+		case _, open := <-sendPing:
+			if !open {
+				sendPing = nil
+			}
+			t.Logf("server sending ping")
+			conn.WriteMessage(websocket.PingMessage, []byte("ping"))
+			wantPong = "ping"
+		case data := <-pongCh:
+			if wantPong == "" {
+				t.Errorf("unexpected pong")
+			} else if data != wantPong {
+				t.Errorf("got pong with wrong data %q", data)
+			}
+			wantPong = ""
+			sendResponse = time.NewTimer(200 * time.Millisecond).C
+		case <-sendResponse:
+			t.Logf("server sending response")
+			conn.WriteMessage(websocket.TextMessage, []byte(subNotify))
+			sendResponse = nil
+		case <-shutdown:
+			conn.Close()
+			return
+		}
+	}
+}

go.mod

@@ -17,6 +17,7 @@ require (
 	github.com/ethereum/go-ethereum v1.9.25
 	github.com/fjl/memsize v0.0.0-20180929194037-2a09253e352a // indirect
 	github.com/garslo/gogen v0.0.0-20170307003452-d6ebae628c7c // indirect
+	github.com/goccy/go-json v0.7.10 // indirect
 	github.com/golang/mock v1.4.4
 	github.com/golang/protobuf v1.4.3
 	github.com/golangci/golangci-lint v1.22.2