...

1 files changed, 625 insertions, 0 deletions

diff --git a/rpc/client.go b/rpc/client.go
new file mode 100644
index 0000000..1c7058b
--- /dev/null
+++ b/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"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net/url"
+	"reflect"
+	"strconv"
+	"sync/atomic"
+	"time"
+
+	"github.com/ava-labs/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.Write(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.Read()
+		if _, ok := err.(*json.SyntaxError); ok {
+			codec.Write(context.Background(), errorMessage(&parseError{err.Error()}))
+		}
+		if err != nil {
+			c.readErr <- err
+			return
+		}
+		c.readOp <- readOp{msgs, batch}
+	}
+}