// 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/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 reqInit and released by sending on reqSent.
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",