Add JSON RPC batch support

http://www.jsonrpc.org/specification#batch

rpc/http.go

 package rpc
 
 import (
+	"encoding/json"
+	"io/ioutil"
 	"net/http"
 
 	"github.com/ethereum/go-ethereum/logger"
@@ -16,54 +18,71 @@ const (
 
 // JSONRPC returns a handler that implements the Ethereum JSON-RPC API.
 func JSONRPC(pipe *xeth.XEth, dataDir string) http.Handler {
-	var json JsonWrapper
+	var jsw JsonWrapper
 	api := NewEthereumApi(pipe, dataDir)
 
 	return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
+		// TODO this needs to be configurable
 		w.Header().Set("Access-Control-Allow-Origin", "*")
 
-		rpchttplogger.DebugDetailln("Handling request")
-
+		// Limit request size to resist DoS
 		if req.ContentLength > maxSizeReqLength {
 			jsonerr := &RpcErrorObject{-32700, "Request too large"}
-			json.Send(w, &RpcErrorResponse{JsonRpc: jsonrpcver, ID: nil, Error: jsonerr})
+			jsw.Send(w, &RpcErrorResponse{JsonRpc: jsonrpcver, ID: nil, Error: jsonerr})
 			return
 		}
 
-		reqParsed, reqerr := json.ParseRequestBody(req)
-		switch reqerr.(type) {
-		case nil:
-			break
-		case *DecodeParamError, *InsufficientParamsError, *ValidationError:
-			jsonerr := &RpcErrorObject{-32602, reqerr.Error()}
-			json.Send(w, &RpcErrorResponse{JsonRpc: jsonrpcver, ID: nil, Error: jsonerr})
-			return
-		default:
-			jsonerr := &RpcErrorObject{-32700, "Could not parse request"}
-			json.Send(w, &RpcErrorResponse{JsonRpc: jsonrpcver, ID: nil, Error: jsonerr})
-			return
+		defer req.Body.Close()
+		body, err := ioutil.ReadAll(req.Body)
+		if err != nil {
+			jsonerr := &RpcErrorObject{-32700, "Could not read request body"}
+			jsw.Send(w, &RpcErrorResponse{JsonRpc: jsonrpcver, ID: nil, Error: jsonerr})
 		}
 
-		var response interface{}
-		reserr := api.GetRequestReply(&reqParsed, &response)
-		switch reserr.(type) {
-		case nil:
-			break
-		case *NotImplementedError:
-			jsonerr := &RpcErrorObject{-32601, reserr.Error()}
-			json.Send(w, &RpcErrorResponse{JsonRpc: jsonrpcver, ID: reqParsed.ID, Error: jsonerr})
+		// Try to parse the request as a single
+		var reqSingle RpcRequest
+		if err := json.Unmarshal(body, &reqSingle); err == nil {
+			response := RpcResponse(api, &reqSingle)
+			jsw.Send(w, &response)
 			return
-		case *DecodeParamError, *InsufficientParamsError, *ValidationError:
-			jsonerr := &RpcErrorObject{-32602, reserr.Error()}
-			json.Send(w, &RpcErrorResponse{JsonRpc: jsonrpcver, ID: reqParsed.ID, Error: jsonerr})
-			return
-		default:
-			jsonerr := &RpcErrorObject{-32603, reserr.Error()}
-			json.Send(w, &RpcErrorResponse{JsonRpc: jsonrpcver, ID: reqParsed.ID, Error: jsonerr})
+		}
+
+		// Try to parse the request to batch
+		var reqBatch []RpcRequest
+		if err := json.Unmarshal(body, &reqBatch); err == nil {
+			// Build response batch
+			resBatch := make([]*interface{}, len(reqBatch))
+			for i, request := range reqBatch {
+				response := RpcResponse(api, &request)
+				resBatch[i] = response
+			}
+			jsw.Send(w, resBatch)
 			return
 		}
 
-		rpchttplogger.DebugDetailf("Generated response: %T %s", response, response)
-		json.Send(w, &RpcSuccessResponse{JsonRpc: jsonrpcver, ID: reqParsed.ID, Result: response})
+		// Not a batch or single request, error
+		jsonerr := &RpcErrorObject{-32600, "Could not decode request"}
+		jsw.Send(w, &RpcErrorResponse{JsonRpc: jsonrpcver, ID: nil, Error: jsonerr})
 	})
 }
+
+func RpcResponse(api *EthereumApi, request *RpcRequest) *interface{} {
+	var reply, response interface{}
+	reserr := api.GetRequestReply(request, &reply)
+	switch reserr.(type) {
+	case nil:
+		response = &RpcSuccessResponse{JsonRpc: jsonrpcver, ID: request.ID, Result: reply}
+	case *NotImplementedError:
+		jsonerr := &RpcErrorObject{-32601, reserr.Error()}
+		response = &RpcErrorResponse{JsonRpc: jsonrpcver, ID: request.ID, Error: jsonerr}
+	case *DecodeParamError, *InsufficientParamsError, *ValidationError:
+		jsonerr := &RpcErrorObject{-32602, reserr.Error()}
+		response = &RpcErrorResponse{JsonRpc: jsonrpcver, ID: request.ID, Error: jsonerr}
+	default:
+		jsonerr := &RpcErrorObject{-32603, reserr.Error()}
+		response = &RpcErrorResponse{JsonRpc: jsonrpcver, ID: request.ID, Error: jsonerr}
+	}
+
+	rpchttplogger.DebugDetailf("Generated response: %T %s", response, response)
+	return &response
+}

rpc/util.go

@@ -21,7 +21,7 @@ import (
 	"fmt"
 	"io"
 	"math/big"
-	"net/http"
+	// "net/http"
 	"reflect"
 	"time"
 
@@ -106,24 +106,6 @@ func (self JsonWrapper) Send(writer io.Writer, v interface{}) (n int, err error)
 	return writer.Write(payload)
 }
 
-func (self JsonWrapper) ParseRequestBody(req *http.Request) (RpcRequest, error) {
-	var reqParsed RpcRequest
-
-	// Convert JSON to native types
-	d := json.NewDecoder(req.Body)
-	defer req.Body.Close()
-	err := d.Decode(&reqParsed)
-
-	if err != nil {
-		rpclogger.Errorln("Error decoding JSON: ", err)
-		return reqParsed, err
-	}
-
-	rpclogger.DebugDetailf("Parsed request: %s", reqParsed)
-
-	return reqParsed, nil
-}
-
 func toHex(b []byte) string {
 	hex := common.Bytes2Hex(b)
 	// Prefer output of "0x0" instead of "0x"