github.com/hyperledger/burrow@v0.34.5-0.20220512172541-77f09336001d/rpc/lib/server/handlers.go

package server

import (
	"bytes"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"io/ioutil"
	"net/http"
	"reflect"
	"sort"
	"strings"

	"github.com/hyperledger/burrow/logging"
	"github.com/hyperledger/burrow/rpc/lib/types"
	"github.com/pkg/errors"
)

// RegisterRPCFuncs adds a route for each function in the funcMap, as well as general jsonrpc and websocket handlers for all functions.
// "result" is the interface on which the result objects are registered, and is popualted with every RPCResponse
func RegisterRPCFuncs(mux *http.ServeMux, funcMap map[string]*RPCFunc, logger *logging.Logger) {
	// HTTP endpoints
	for funcName, rpcFunc := range funcMap {
		mux.HandleFunc("/"+funcName, makeHTTPHandler(rpcFunc, logger))
	}

	// JSONRPC endpoints
	mux.HandleFunc("/", makeJSONRPCHandler(funcMap, logger))
}

//-------------------------------------
// function introspection

// RPCFunc contains the introspected type information for a function
type RPCFunc struct {
	f        reflect.Value  // underlying rpc function
	args     []reflect.Type // type of each function arg
	returns  []reflect.Type // type of each return arg
	argNames []string       // name of each argument
	ws       bool           // websocket only
}

// NewRPCFunc wraps a function for introspection.
// f is the function, args are comma separated argument names
func NewRPCFunc(f interface{}, args string) *RPCFunc {
	return newRPCFunc(f, args, false)
}

// NewWSRPCFunc wraps a function for introspection and use in the websockets.
func NewWSRPCFunc(f interface{}, args string) *RPCFunc {
	return newRPCFunc(f, args, true)
}

func newRPCFunc(f interface{}, args string, ws bool) *RPCFunc {
	var argNames []string
	if args != "" {
		argNames = strings.Split(args, ",")
	}
	return &RPCFunc{
		f:        reflect.ValueOf(f),
		args:     funcArgTypes(f),
		returns:  funcReturnTypes(f),
		argNames: argNames,
		ws:       ws,
	}
}

// return a function's argument types
func funcArgTypes(f interface{}) []reflect.Type {
	t := reflect.TypeOf(f)
	n := t.NumIn()
	typez := make([]reflect.Type, n)
	for i := 0; i < n; i++ {
		typez[i] = t.In(i)
	}
	return typez
}

// return a function's return types
func funcReturnTypes(f interface{}) []reflect.Type {
	t := reflect.TypeOf(f)
	n := t.NumOut()
	typez := make([]reflect.Type, n)
	for i := 0; i < n; i++ {
		typez[i] = t.Out(i)
	}
	return typez
}

// function introspection
//-----------------------------------------------------------------------------
// rpc.json

// jsonrpc calls grab the given method's function info and runs reflect.Call
func makeJSONRPCHandler(funcMap map[string]*RPCFunc, logger *logging.Logger) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		b, err := ioutil.ReadAll(r.Body)
		if err != nil {
			WriteRPCResponseHTTP(w, types.RPCInvalidRequestError("", errors.Wrap(err, "Error reading request body")))
			return
		}
		// if its an empty request (like from a browser),
		// just display a list of functions
		if len(b) == 0 {
			writeListOfEndpoints(w, r, funcMap)
			return
		}

		var request types.RPCRequest
		err = json.Unmarshal(b, &request)
		if err != nil {
			WriteRPCResponseHTTP(w, types.RPCParseError("", errors.Wrap(err, "Error unmarshalling request")))
			return
		}
		// A Notification is a Request object without an "id" member.
		// The Server MUST NOT reply to a Notification, including those that are within a batch request.
		if request.ID == "" {
			logger.TraceMsg("HTTPJSONRPC received a notification, skipping... (please send a non-empty ID if you want to call a method)")
			return
		}
		if len(r.URL.Path) > 1 {
			WriteRPCResponseHTTP(w, types.RPCInvalidRequestError(request.ID, errors.Errorf("Path %s is invalid", r.URL.Path)))
			return
		}
		rpcFunc := funcMap[request.Method]
		if rpcFunc == nil || rpcFunc.ws {
			WriteRPCResponseHTTP(w, types.RPCMethodNotFoundError(request.ID))
			return
		}
		var args []reflect.Value
		if len(request.Params) > 0 {
			args, err = jsonParamsToArgsRPC(rpcFunc, request.Params)
			if err != nil {
				WriteRPCResponseHTTP(w, types.RPCInvalidParamsError(request.ID, errors.Wrap(err, "Error converting json params to arguments")))
				return
			}
		}
		returns := rpcFunc.f.Call(args)
		logger.InfoMsg("HTTP JSONRPC called", "method", request.Method, "args", args, "returns", returns)
		result, err := unreflectResult(returns)
		if err != nil {
			WriteRPCResponseHTTP(w, types.RPCInternalError(request.ID, err))
			return
		}
		WriteRPCResponseHTTP(w, types.NewRPCSuccessResponse(request.ID, result))
	}
}

func mapParamsToArgs(rpcFunc *RPCFunc, params map[string]json.RawMessage, argsOffset int) ([]reflect.Value, error) {
	values := make([]reflect.Value, len(rpcFunc.argNames))
	for i, argName := range rpcFunc.argNames {
		argType := rpcFunc.args[i+argsOffset]

		if p, ok := params[argName]; ok && p != nil && len(p) > 0 {
			val := reflect.New(argType)
			err := json.Unmarshal(p, val.Interface())
			if err != nil {
				return nil, err
			}
			values[i] = val.Elem()
		} else { // use default for that type
			values[i] = reflect.Zero(argType)
		}
	}

	return values, nil
}

func arrayParamsToArgs(rpcFunc *RPCFunc, params []json.RawMessage, argsOffset int) ([]reflect.Value, error) {
	if len(rpcFunc.argNames) != len(params) {
		return nil, errors.Errorf("Expected %v parameters (%v), got %v (%v)",
			len(rpcFunc.argNames), rpcFunc.argNames, len(params), params)
	}

	values := make([]reflect.Value, len(params))
	for i, p := range params {
		argType := rpcFunc.args[i+argsOffset]
		val := reflect.New(argType)
		err := json.Unmarshal(p, val.Interface())
		if err != nil {
			return nil, err
		}
		values[i] = val.Elem()
	}
	return values, nil
}

// `raw` is unparsed json (from json.RawMessage) encoding either a map or an array.
// `argsOffset` should be 0 for RPC calls, and 1 for WS requests, where len(rpcFunc.args) != len(rpcFunc.argNames).
//
// Example:
//   rpcFunc.args = [rpctypes.WSRPCContext string]
//   rpcFunc.argNames = ["arg"]
func jsonParamsToArgs(rpcFunc *RPCFunc, raw []byte, argsOffset int) ([]reflect.Value, error) {

	// TODO: Make more efficient, perhaps by checking the first character for '{' or '['?
	// First, try to get the map.
	var m map[string]json.RawMessage
	err := json.Unmarshal(raw, &m)
	if err == nil {
		return mapParamsToArgs(rpcFunc, m, argsOffset)
	}

	// Otherwise, try an array.
	var a []json.RawMessage
	err = json.Unmarshal(raw, &a)
	if err == nil {
		return arrayParamsToArgs(rpcFunc, a, argsOffset)
	}

	// Otherwise, bad format, we cannot parse
	return nil, errors.Errorf("Unknown type for JSON params: %v. Expected map or array", err)
}

// Convert a []interface{} OR a map[string]interface{} to properly typed values
func jsonParamsToArgsRPC(rpcFunc *RPCFunc, params json.RawMessage) ([]reflect.Value, error) {
	return jsonParamsToArgs(rpcFunc, params, 0)
}

// convert from a function name to the http handler
func makeHTTPHandler(rpcFunc *RPCFunc, logger *logging.Logger) func(http.ResponseWriter, *http.Request) {
	// Exception for websocket endpoints
	if rpcFunc.ws {
		return func(w http.ResponseWriter, r *http.Request) {
			WriteRPCResponseHTTP(w, types.RPCMethodNotFoundError(""))
		}
	}
	logger = logger.WithScope("makeHTTPHandler")
	// All other endpoints
	return func(w http.ResponseWriter, r *http.Request) {
		logger.TraceMsg("HTTP REST Handler received request", "request", r)
		args, err := httpParamsToArgs(rpcFunc, r)
		if err != nil {
			WriteRPCResponseHTTP(w, types.RPCInvalidParamsError("", errors.Wrap(err, "Error converting http params to arguments")))
			return
		}
		returns := rpcFunc.f.Call(args)
		logger.InfoMsg("HTTP REST", "method", r.URL.Path, "args", args, "returns", returns)
		result, err := unreflectResult(returns)
		if err != nil {
			WriteRPCResponseHTTP(w, types.RPCInternalError("", err))
			return
		}
		WriteRPCResponseHTTP(w, types.NewRPCSuccessResponse("", result))
	}
}

// Covert an http query to a list of properly typed values.
// To be properly decoded the arg must be a concrete type from tendermint (if its an interface).
func httpParamsToArgs(rpcFunc *RPCFunc, r *http.Request) ([]reflect.Value, error) {
	values := make([]reflect.Value, len(rpcFunc.args))

	for i, name := range rpcFunc.argNames {
		argType := rpcFunc.args[i]

		values[i] = reflect.Zero(argType) // set default for that type

		arg := GetParam(r, name)
		// log.Notice("param to arg", "argType", argType, "name", name, "arg", arg)

		if arg == "" {
			continue
		}

		v, ok, err := nonJSONToArg(argType, arg)
		if err != nil {
			return nil, err
		}
		if ok {
			values[i] = v
			continue
		}

		values[i], err = jsonStringToArg(argType, arg)
		if err != nil {
			return nil, err
		}
	}

	return values, nil
}

func jsonStringToArg(ty reflect.Type, arg string) (reflect.Value, error) {
	v := reflect.New(ty)
	err := json.Unmarshal([]byte(arg), v.Interface())
	if err != nil {
		return v, err
	}
	v = v.Elem()
	return v, nil
}

func nonJSONToArg(ty reflect.Type, arg string) (reflect.Value, bool, error) {
	expectingString := ty.Kind() == reflect.String
	expectingBytes := (ty.Kind() == reflect.Slice || ty.Kind() == reflect.Array) && ty.Elem().Kind() == reflect.Uint8

	isQuotedString := strings.HasPrefix(arg, `"`) && strings.HasSuffix(arg, `"`)

	// Throw quoted strings at JSON parser later... because it always has...
	if expectingString && !isQuotedString {
		return reflect.ValueOf(arg), true, nil
	}

	if expectingBytes {
		if isQuotedString {
			rv := reflect.New(ty)
			err := json.Unmarshal([]byte(arg), rv.Interface())
			if err != nil {
				return reflect.ValueOf(nil), false, err
			}
			return rv.Elem(), true, nil
		}
		if strings.HasPrefix(strings.ToLower(arg), "0x") {
			arg = arg[2:]
		}
		var value []byte
		value, err := hex.DecodeString(arg)
		if err != nil {
			return reflect.ValueOf(nil), false, err
		}
		if ty.Kind() == reflect.Array {
			// Gives us an empty array of the right type
			rv := reflect.New(ty).Elem()
			reflect.Copy(rv, reflect.ValueOf(value))
			return rv, true, nil
		}
		return reflect.ValueOf(value), true, nil
	}

	return reflect.ValueOf(nil), false, nil
}

// NOTE: assume returns is result struct and error. If error is not nil, return it
func unreflectResult(returns []reflect.Value) (interface{}, error) {
	errV := returns[1]
	if errV.Interface() != nil {
		return nil, errors.Errorf("%v", errV.Interface())
	}
	rv := returns[0]
	// the result is a registered interface,
	// we need a pointer to it so we can marshal with type byte
	rvp := reflect.New(rv.Type())
	rvp.Elem().Set(rv)
	return rvp.Interface(), nil
}

// writes a list of available rpc endpoints as an html page
func writeListOfEndpoints(w http.ResponseWriter, r *http.Request, funcMap map[string]*RPCFunc) {
	noArgNames := []string{}
	argNames := []string{}
	for name, funcData := range funcMap {
		if len(funcData.args) == 0 {
			noArgNames = append(noArgNames, name)
		} else {
			argNames = append(argNames, name)
		}
	}
	sort.Strings(noArgNames)
	sort.Strings(argNames)
	buf := new(bytes.Buffer)
	buf.WriteString("<html><body>")
	buf.WriteString("<br>Available endpoints:<br>")

	for _, name := range noArgNames {
		link := fmt.Sprintf("//%s/%s", r.Host, name)
		buf.WriteString(fmt.Sprintf("<a href=\"%s\">%s</a></br>", link, link))
	}

	buf.WriteString("<br>Endpoints that require arguments:<br>")
	for _, name := range argNames {
		link := fmt.Sprintf("//%s/%s?", r.Host, name)
		funcData := funcMap[name]
		for i, argName := range funcData.argNames {
			link += argName + "=_"
			if i < len(funcData.argNames)-1 {
				link += "&"
			}
		}
		buf.WriteString(fmt.Sprintf("<a href=\"%s\">%s</a></br>", link, link))
	}
	buf.WriteString("</body></html>")
	w.Header().Set("Content-Type", "text/html")
	w.WriteHeader(200)
	w.Write(buf.Bytes()) // nolint: errcheck
}