/
dispatcher.go
464 lines (369 loc) · 10.7 KB
/
dispatcher.go
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package jsonrpc
import (
"bytes"
"encoding/json"
"errors"
"fmt"
"math"
"reflect"
"strings"
"unicode"
"github.com/hashicorp/go-hclog"
)
type serviceData struct {
sv reflect.Value
funcMap map[string]*funcData
}
type funcData struct {
inNum int
reqt []reflect.Type
fv reflect.Value
isDyn bool
}
func (f *funcData) numParams() int {
return f.inNum - 1
}
type endpoints struct {
Eth *Eth
Web3 *Web3
Net *Net
TxPool *TxPool
}
// Dispatcher handles all json rpc requests by delegating
// the execution flow to the corresponding service
type Dispatcher struct {
logger hclog.Logger
serviceMap map[string]*serviceData
filterManager *FilterManager
endpoints endpoints
chainID uint64
priceLimit uint64
jsonRPCBatchLengthLimit uint64
}
func newDispatcher(
logger hclog.Logger,
store JSONRPCStore,
chainID uint64,
priceLimit uint64,
jsonRPCBatchLengthLimit uint64,
blockRangeLimit uint64,
) *Dispatcher {
d := &Dispatcher{
logger: logger.Named("dispatcher"),
chainID: chainID,
priceLimit: priceLimit,
jsonRPCBatchLengthLimit: jsonRPCBatchLengthLimit,
}
if store != nil {
d.filterManager = NewFilterManager(logger, store, blockRangeLimit)
go d.filterManager.Run()
}
d.registerEndpoints(store)
return d
}
func (d *Dispatcher) registerEndpoints(store JSONRPCStore) {
d.endpoints.Eth = &Eth{d.logger, store, d.chainID, d.filterManager, d.priceLimit}
d.endpoints.Net = &Net{store, d.chainID}
d.endpoints.Web3 = &Web3{}
d.endpoints.TxPool = &TxPool{store}
d.registerService("eth", d.endpoints.Eth)
d.registerService("net", d.endpoints.Net)
d.registerService("web3", d.endpoints.Web3)
d.registerService("txpool", d.endpoints.TxPool)
}
func (d *Dispatcher) getFnHandler(req Request) (*serviceData, *funcData, Error) {
callName := strings.SplitN(req.Method, "_", 2)
if len(callName) != 2 {
return nil, nil, NewMethodNotFoundError(req.Method)
}
serviceName, funcName := callName[0], callName[1]
service, ok := d.serviceMap[serviceName]
if !ok {
return nil, nil, NewMethodNotFoundError(req.Method)
}
fd, ok := service.funcMap[funcName]
if !ok {
return nil, nil, NewMethodNotFoundError(req.Method)
}
return service, fd, nil
}
type wsConn interface {
WriteMessage(messageType int, data []byte) error
GetFilterID() string
SetFilterID(string)
}
// as per https://www.jsonrpc.org/specification, the `id` in JSON-RPC 2.0
// can only be a string or a non-decimal integer
func formatFilterResponse(id interface{}, resp string) (string, Error) {
switch t := id.(type) {
case string:
return fmt.Sprintf(`{"jsonrpc":"2.0","id":"%s","result":"%s"}`, t, resp), nil
case float64:
if t == math.Trunc(t) {
return fmt.Sprintf(`{"jsonrpc":"2.0","id":%d,"result":"%s"}`, int(t), resp), nil
} else {
return "", NewInvalidRequestError("Invalid json request")
}
case nil:
return fmt.Sprintf(`{"jsonrpc":"2.0","id":null,"result":"%s"}`, resp), nil
default:
return "", NewInvalidRequestError("Invalid json request")
}
}
func (d *Dispatcher) handleSubscribe(req Request, conn wsConn) (string, Error) {
var params []interface{}
if err := json.Unmarshal(req.Params, ¶ms); err != nil {
return "", NewInvalidRequestError("Invalid json request")
}
if len(params) == 0 {
return "", NewInvalidParamsError("Invalid params")
}
subscribeMethod, ok := params[0].(string)
if !ok {
return "", NewSubscriptionNotFoundError(subscribeMethod)
}
var filterID string
if subscribeMethod == "newHeads" {
filterID = d.filterManager.NewBlockFilter(conn)
} else if subscribeMethod == "logs" {
logQuery, err := decodeLogQueryFromInterface(params[1])
if err != nil {
return "", NewInternalError(err.Error())
}
filterID = d.filterManager.NewLogFilter(logQuery, conn)
} else {
return "", NewSubscriptionNotFoundError(subscribeMethod)
}
return filterID, nil
}
func (d *Dispatcher) handleUnsubscribe(req Request) (bool, Error) {
var params []interface{}
if err := json.Unmarshal(req.Params, ¶ms); err != nil {
return false, NewInvalidRequestError("Invalid json request")
}
if len(params) != 1 {
return false, NewInvalidParamsError("Invalid params")
}
filterID, ok := params[0].(string)
if !ok {
return false, NewSubscriptionNotFoundError(filterID)
}
return d.filterManager.Uninstall(filterID), nil
}
func (d *Dispatcher) RemoveFilterByWs(conn wsConn) {
d.filterManager.RemoveFilterByWs(conn)
}
func (d *Dispatcher) HandleWs(reqBody []byte, conn wsConn) ([]byte, error) {
var req Request
if err := json.Unmarshal(reqBody, &req); err != nil {
return NewRPCResponse(req.ID, "2.0", nil, NewInvalidRequestError("Invalid json request")).Bytes()
}
// if the request method is eth_subscribe we need to create a
// new filter with ws connection
if req.Method == "eth_subscribe" {
filterID, err := d.handleSubscribe(req, conn)
if err != nil {
return NewRPCResponse(req.ID, "2.0", nil, err).Bytes()
}
resp, err := formatFilterResponse(req.ID, filterID)
if err != nil {
return NewRPCResponse(req.ID, "2.0", nil, err).Bytes()
}
return []byte(resp), nil
}
if req.Method == "eth_unsubscribe" {
ok, err := d.handleUnsubscribe(req)
if err != nil {
return nil, err
}
res := "false"
if ok {
res = "true"
}
resp, err := formatFilterResponse(req.ID, res)
if err != nil {
return NewRPCResponse(req.ID, "2.0", nil, err).Bytes()
}
return []byte(resp), nil
}
// its a normal query that we handle with the dispatcher
resp, err := d.handleReq(req)
if err != nil {
return nil, err
}
return NewRPCResponse(req.ID, "2.0", resp, err).Bytes()
}
func (d *Dispatcher) Handle(reqBody []byte) ([]byte, error) {
x := bytes.TrimLeft(reqBody, " \t\r\n")
if len(x) == 0 {
return NewRPCResponse(nil, "2.0", nil, NewInvalidRequestError("Invalid json request")).Bytes()
}
if x[0] == '{' {
var req Request
if err := json.Unmarshal(reqBody, &req); err != nil {
return NewRPCResponse(nil, "2.0", nil, NewInvalidRequestError("Invalid json request")).Bytes()
}
if req.Method == "" {
return NewRPCResponse(req.ID, "2.0", nil, NewInvalidRequestError("Invalid json request")).Bytes()
}
resp, err := d.handleReq(req)
return NewRPCResponse(req.ID, "2.0", resp, err).Bytes()
}
// handle batch requests
var requests []Request
if err := json.Unmarshal(reqBody, &requests); err != nil {
return NewRPCResponse(nil, "2.0", nil, NewInvalidRequestError("Invalid json request")).Bytes()
}
// if not disabled, avoid handling long batch requests
if d.jsonRPCBatchLengthLimit != 0 &&
len(requests) > int(d.jsonRPCBatchLengthLimit) {
return NewRPCResponse(nil, "2.0", nil, NewInvalidRequestError("Batch request length too long")).Bytes()
}
responses := make([]Response, 0)
for _, req := range requests {
var response, err = d.handleReq(req)
if err != nil {
errorResponse := NewRPCResponse(req.ID, "2.0", nil, err)
responses = append(responses, errorResponse)
continue
}
resp := NewRPCResponse(req.ID, "2.0", response, nil)
responses = append(responses, resp)
}
respBytes, err := json.Marshal(responses)
if err != nil {
return NewRPCResponse(nil, "2.0", nil, NewInternalError("Internal error")).Bytes()
}
return respBytes, nil
}
func (d *Dispatcher) handleReq(req Request) ([]byte, Error) {
d.logger.Debug("request", "method", req.Method, "id", req.ID)
service, fd, ferr := d.getFnHandler(req)
if ferr != nil {
return nil, ferr
}
inArgs := make([]reflect.Value, fd.inNum)
inArgs[0] = service.sv
inputs := make([]interface{}, fd.numParams())
for i := 0; i < fd.inNum-1; i++ {
val := reflect.New(fd.reqt[i+1])
inputs[i] = val.Interface()
inArgs[i+1] = val.Elem()
}
if fd.numParams() > 0 {
if err := json.Unmarshal(req.Params, &inputs); err != nil {
return nil, NewInvalidParamsError("Invalid Params")
}
}
output := fd.fv.Call(inArgs)
if err := getError(output[1]); err != nil {
d.logInternalError(req.Method, err)
return nil, NewInvalidRequestError(err.Error())
}
var (
data []byte
err error
)
if res := output[0].Interface(); res != nil {
data, err = json.Marshal(res)
if err != nil {
d.logInternalError(req.Method, err)
return nil, NewInternalError("Internal error")
}
}
return data, nil
}
func (d *Dispatcher) logInternalError(method string, err error) {
d.logger.Error("failed to dispatch", "method", method, "err", err)
}
func (d *Dispatcher) registerService(serviceName string, service interface{}) {
if d.serviceMap == nil {
d.serviceMap = map[string]*serviceData{}
}
if serviceName == "" {
panic("jsonrpc: serviceName cannot be empty")
}
st := reflect.TypeOf(service)
if st.Kind() == reflect.Struct {
panic(fmt.Sprintf("jsonrpc: service '%s' must be a pointer to struct", serviceName))
}
funcMap := make(map[string]*funcData)
for i := 0; i < st.NumMethod(); i++ {
mv := st.Method(i)
if mv.PkgPath != "" {
// skip unexported methods
continue
}
name := lowerCaseFirst(mv.Name)
funcName := serviceName + "_" + name
fd := &funcData{
fv: mv.Func,
}
var err error
if fd.inNum, fd.reqt, err = validateFunc(funcName, fd.fv, true); err != nil {
panic(fmt.Sprintf("jsonrpc: %s", err))
}
// check if last item is a pointer
if fd.numParams() != 0 {
last := fd.reqt[fd.numParams()]
if last.Kind() == reflect.Ptr {
fd.isDyn = true
}
}
funcMap[name] = fd
}
d.serviceMap[serviceName] = &serviceData{
sv: reflect.ValueOf(service),
funcMap: funcMap,
}
}
func validateFunc(funcName string, fv reflect.Value, _ bool) (inNum int, reqt []reflect.Type, err error) {
if funcName == "" {
err = fmt.Errorf("funcName cannot be empty")
return
}
ft := fv.Type()
if ft.Kind() != reflect.Func {
err = fmt.Errorf("function '%s' must be a function instead of %s", funcName, ft)
return
}
inNum = ft.NumIn()
if outNum := ft.NumOut(); ft.NumOut() != 2 {
err = fmt.Errorf("unexpected number of output arguments in the function '%s': %d. Expected 2", funcName, outNum)
return
}
if !isErrorType(ft.Out(1)) {
err = fmt.Errorf(
"unexpected type for the second return value of the function '%s': '%s'. Expected '%s'",
funcName,
ft.Out(1),
errt,
)
return
}
reqt = make([]reflect.Type, inNum)
for i := 0; i < inNum; i++ {
reqt[i] = ft.In(i)
}
return
}
var errt = reflect.TypeOf((*error)(nil)).Elem()
func isErrorType(t reflect.Type) bool {
return t.Implements(errt)
}
func getError(v reflect.Value) error {
if v.IsNil() {
return nil
}
extractedErr, ok := v.Interface().(error)
if !ok {
return errors.New("invalid type assertion, unable to extract error")
}
return extractedErr
}
func lowerCaseFirst(str string) string {
for i, v := range str {
return string(unicode.ToLower(v)) + str[i+1:]
}
return ""
}