// 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 (
"encoding/json"
"fmt"
"io"
"reflect"
"strconv"
"strings"
"sync"
"github.com/ethereum/go-ethereum/logger"
"github.com/ethereum/go-ethereum/logger/glog"
)
const (
jsonRPCVersion = "2.0"
serviceMethodSeparator = "_"
subscribeMethod = "eth_subscribe"
unsubscribeMethod = "eth_unsubscribe"
notificationMethod = "eth_subscription"
)
// JSON-RPC request
type JSONRequest struct {
Method string `json:"method"`
Version string `json:"jsonrpc"`
Id json.RawMessage `json:"id,omitempty"`
Payload json.RawMessage `json:"params,omitempty"`
}
// JSON-RPC response
type JSONSuccessResponse struct {
Version string `json:"jsonrpc"`
Id interface{} `json:"id,omitempty"`
Result interface{} `json:"result"`
}
// JSON-RPC error object
type JSONError struct {
Code int `json:"code"`
Message string `json:"message"`
Data interface{} `json:"data,omitempty"`
}
// JSON-RPC error response
type JSONErrResponse struct {
Version string `json:"jsonrpc"`
Id interface{} `json:"id,omitempty"`
Error JSONError `json:"error"`
}
// JSON-RPC notification payload
type jsonSubscription struct {
Subscription string `json:"subscription"`
Result interface{} `json:"result,omitempty"`
}
// JSON-RPC notification
type jsonNotification struct {
Version string `json:"jsonrpc"`
Method string `json:"method"`
Params jsonSubscription `json:"params"`
}
// jsonCodec reads and writes JSON-RPC messages to the underlying connection. It
// also has support for parsing arguments and serializing (result) objects.
type jsonCodec struct {
closer sync.Once // close closed channel once
closed chan interface{} // closed on Close
decMu sync.Mutex // guards d
d *json.Decoder // decodes incoming requests
encMu sync.Mutex // guards e
e *json.Encoder // encodes responses
rw io.ReadWriteCloser // connection
}
// NewJSONCodec creates a new RPC server codec with support for JSON-RPC 2.0
func NewJSONCodec(rwc io.ReadWriteCloser) ServerCodec {
d := json.NewDecoder(rwc)
d.UseNumber()
return &jsonCodec{closed: make(chan interface{}), d: d, e: json.NewEncoder(rwc), rw: rwc}
}
// isBatch returns true when the first non-whitespace characters is '['
func isBatch(msg json.RawMessage) bool {
for _, c := range msg {
// skip insignificant whitespace (http://www.ietf.org/rfc/rfc4627.txt)
if c == 0x20 || c == 0x09 || c == 0x0a || c == 0x0d {
continue
}
return c == '['
}
return false
}
// ReadRequestHeaders will read new requests without parsing the arguments. It will
// return a collection of requests, an indication if these requests are in batch
// form or an error when the incoming message could not be read/parsed.
func (c *jsonCodec) ReadRequestHeaders() ([]rpcRequest, bool, RPCError) {
c.decMu.Lock()
defer c.decMu.Unlock()
var incomingMsg json.RawMessage
if err := c.d.Decode(&incomingMsg); err != nil {
return nil, false, &invalidRequestError{err.Error()}
}
if isBatch(incomingMsg) {
return parseBatchRequest(incomingMsg)
}
return parseRequest(incomingMsg)
}
// checkReqId returns an error when the given reqId isn't valid for RPC method calls.
// valid id's are strings, numbers or null
func checkReqId(reqId json.RawMessage) error {
if len(reqId) == 0 {
return fmt.Errorf("missing request id")
}
if _, err := strconv.ParseFloat(string(reqId), 64); err == nil {
return nil
}
var str string
if err := json.Unmarshal(reqId, &str); err == nil {
return nil
}
return fmt.Errorf("invalid request id")
}
// parseRequest will parse a single request from the given RawMessage. It will return
// the parsed request, an indication if the request was a batch or an error when
// the request could not be parsed.
func parseRequest(incomingMsg json.RawMessage) ([]rpcRequest, bool, RPCError) {
var in JSONRequest
if err := json.Unmarshal(incomingMsg, &in); err != nil {
return nil, false, &invalidMessageError{err.Error()}
}
if err := checkReqId(in.Id); err != nil {
return nil, false, &invalidMessageError{err.Error()}
}
// subscribe are special, they will always use `subscribeMethod` as first param in the payload
if in.Method == subscribeMethod {
reqs := []rpcRequest{rpcRequest{id: &in.Id, isPubSub: true}}
if len(in.Payload) > 0 {
// first param must be subscription name
var subscribeMethod [1]string
if err := json.Unmarshal(in.Payload, &subscribeMethod); err != nil {
glog.V(logger.Debug).Infof("Unable to parse subscription method: %v\n", err)
return nil, false, &invalidRequestError{"Unable to parse subscription request"}
}
// all subscriptions are made on the eth service
reqs[0].service, reqs[0].method = "eth", subscribeMethod[0]
reqs[0].params = in.Payload
return reqs, false, nil
}
return nil, false, &invalidRequestError{"Unable to parse subscription request"}
}
if in.Method == unsubscribeMethod {
return []rpcRequest{rpcRequest{id: &in.Id, isPubSub: true,
method: unsubscribeMethod, params: in.Payload}}, false, nil
}
// regular RPC call
elems := strings.Split(in.Method, serviceMethodSeparator)
if len(elems) != 2 {
return nil, false, &methodNotFoundError{in.Method, ""}
}
if len(in.Payload) == 0 {
return []rpcRequest{rpcRequest{service: elems[0], method: elems[1], id: &in.Id}}, false, nil
}
return []rpcRequest{rpcRequest{service: elems[0], method: elems[1], id: &in.Id, params: in.Payload}}, false, nil
}
// parseBatchRequest will parse a batch request into a collection of requests from the given RawMessage, an indication
// if the request was a batch or an error when the request could not be read.
func parseBatchRequest(incomingMsg json.RawMessage) ([]rpcRequest, bool, RPCError) {
var in []JSONRequest
if err := json.Unmarshal(incomingMsg, &in); err != nil {
return nil, false, &invalidMessageError{err.Error()}
}
requests := make([]rpcRequest, len(in))
for i, r := range in {
if err := checkReqId(r.Id); err != nil {
return nil, false, &invalidMessageError{err.Error()}
}
id := &in[i].Id
// subscribe are special, they will always use `subscribeMethod` as first param in the payload
if r.Method == subscribeMethod {
requests[i] = rpcRequest{id: id, isPubSub: true}
if len(r.Payload) > 0 {
// first param must be subscription name
var subscribeMethod [1]string
if err := json.Unmarshal(r.Payload, &subscribeMethod); err != nil {
glog.V(logger.Debug).Infof("Unable to parse subscription method: %v\n", err)
return nil, false, &invalidRequestError{"Unable to parse subscription request"}
}
// all subscriptions are made on the eth service
requests[i].service, requests[i].method = "eth", subscribeMethod[0]
requests[i].params = r.Payload
continue
}
return nil, true, &invalidRequestError{"Unable to parse (un)subscribe request arguments"}
}
if r.Method == unsubscribeMethod {
requests[i] = rpcRequest{id: id, isPubSub: true, method: unsubscribeMethod, params: r.Payload}
continue
}
elems := strings.Split(r.Method, serviceMethodSeparator)
if len(elems) != 2 {
return nil, true, &methodNotFoundError{r.Method, ""}
}
if len(r.Payload) == 0 {
requests[i] = rpcRequest{service: elems[0], method: elems[1], id: id, params: nil}
} else {
requests[i] = rpcRequest{service: elems[0], method: elems[1], id: id, params: r.Payload}
}
}
return requests, true, nil
}
// ParseRequestArguments tries to parse the given params (json.RawMessage) with the given types. It returns the parsed
// values or an error when the parsing failed.
func (c *jsonCodec) ParseRequestArguments(argTypes []reflect.Type, params interface{}) ([]reflect.Value, RPCError) {
if args, ok := params.(json.RawMessage); !ok {
return nil, &invalidParamsError{"Invalid params supplied"}
} else {
return parsePositionalArguments(args, argTypes)
}
}
// 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(args json.RawMessage, callbackArgs []reflect.Type) ([]reflect.Value, RPCError) {
params := make([]interface{}, 0, len(callbackArgs))
for _, t := range callbackArgs {
params = append(params, reflect.New(t).Interface())
}
if err := json.Unmarshal(args, ¶ms); err != nil {
return nil, &invalidParamsError{err.Error()}
}
if len(params) > len(callbackArgs) {
return nil, &invalidParamsError{fmt.Sprintf("too many params, want %d got %d", len(callbackArgs), len(params))}
}
// assume missing params are null values
for i := len(params); i < len(callbackArgs); i++ {
params = append(params, nil)
}
argValues := make([]reflect.Value, len(params))
for i, p := range params {
// verify that JSON null values are only supplied for optional arguments (ptr types)
if p == nil && callbackArgs[i].Kind() != reflect.Ptr {
return nil, &invalidParamsError{fmt.Sprintf("invalid or missing value for params[%d]", i)}
}
if p == nil {
argValues[i] = reflect.Zero(callbackArgs[i])
} else { // deref pointers values creates previously with reflect.New
argValues[i] = reflect.ValueOf(p).Elem()
}
}
return argValues, nil
}
// CreateResponse will create a JSON-RPC success response with the given id and reply as result.
func (c *jsonCodec) CreateResponse(id interface{}, reply interface{}) interface{} {
if isHexNum(reflect.TypeOf(reply)) {
return &JSONSuccessResponse{Version: jsonRPCVersion, Id: id, Result: fmt.Sprintf(`%#x`, reply)}
}
return &JSONSuccessResponse{Version: jsonRPCVersion, Id: id, Result: reply}
}
// CreateErrorResponse will create a JSON-RPC error response with the given id and error.
func (c *jsonCodec) CreateErrorResponse(id interface{}, err RPCError) interface{} {
return &JSONErrResponse{Version: jsonRPCVersion, Id: id, Error: JSONError{Code: err.Code(), Message: err.Error()}}
}
// CreateErrorResponseWithInfo will create a JSON-RPC error response with the given id and error.
// info is optional and contains additional information about the error. When an empty string is passed it is ignored.
func (c *jsonCodec) CreateErrorResponseWithInfo(id interface{}, err RPCError, info interface{}) interface{} {
return &JSONErrResponse{Version: jsonRPCVersion, Id: id,
Error: JSONError{Code: err.Code(), Message: err.Error(), Data: info}}
}
// CreateNotification will create a JSON-RPC notification with the given subscription id and event as params.
func (c *jsonCodec) CreateNotification(subid string, event interface{}) interface{} {
if isHexNum(reflect.TypeOf(event)) {
return &jsonNotification{Version: jsonRPCVersion, Method: notificationMethod,
Params: jsonSubscription{Subscription: subid, Result: fmt.Sprintf(`%#x`, event)}}
}
return &jsonNotification{Version: jsonRPCVersion, Method: notificationMethod,
Params: jsonSubscription{Subscription: subid, Result: event}}
}
// Write message to client
func (c *jsonCodec) Write(res interface{}) error {
c.encMu.Lock()
defer c.encMu.Unlock()
return c.e.Encode(res)
}
// Close the underlying connection
func (c *jsonCodec) Close() {
c.closer.Do(func() {
close(c.closed)
c.rw.Close()
})
}
// Closed returns a channel which will be closed when Close is called
func (c *jsonCodec) Closed() <-chan interface{} {
return c.closed
}
