Add support for JSON-RPC batched calls (#341)

This PR introduces proper support for JSON-RPC batched requests (http://www.jsonrpc.org/specification#batch)

geth/rpc/README.md

@@ -1,5 +1,5 @@
 # rpc [![GoDoc](https://godoc.org/github.com/status-im/status-go/geth/rpc?status.png)](https://godoc.org/github.com/status-im/status-go/geth/rpc)
-rpc - JSON-RPC client with custom routing.
+Package rpc - JSON-RPC client with custom routing.
 
 Download:
 ```shell
@@ -7,7 +7,7 @@ go get github.com/status-im/status-go/geth/rpc
 ```
 
 * * *
-rpc - JSON-RPC client with custom routing.
+Package rpc - JSON-RPC client with custom routing.
 
 Package rpc implements status-go JSON-RPC client and handles
 requests to different endpoints: upstream or local node.
@@ -27,4 +27,4 @@ Note, upon creation of a new client, it ok to be offline - client will keep tryi
 
 
 * * *
-Automatically generated by [autoreadme](https://github.com/jimmyfrasche/autoreadme) on 2017.09.15
+Automatically generated by [autoreadme](https://github.com/jimmyfrasche/autoreadme) on 2017.09.18

geth/rpc/call_raw.go

@@ -3,7 +3,6 @@ package rpc
 import (
 	"context"
 	"encoding/json"
-	"errors"
 
 	gethrpc "github.com/ethereum/go-ethereum/rpc"
 	"github.com/status-im/status-go/geth/log"
@@ -26,7 +25,7 @@ var defaultMsgID = json.RawMessage(`0`)
 // returns string in JSON format with response (successul or error).
 func (c *Client) CallRaw(body string) string {
 	ctx := context.Background()
-	return c.callRawContext(ctx, body)
+	return c.callRawContext(ctx, json.RawMessage(body))
 }
 
 // jsonrpcMessage represents JSON-RPC request, notification, successful response or
@@ -57,9 +56,51 @@ type jsonError struct {
 // This is waste of CPU and memory and should be avoided if possible,
 // either by changing exported API (provide only Call, not CallRaw) or
 // refactoring go-ethereum's client to allow using raw JSON directly.
-func (c *Client) callRawContext(ctx context.Context, body string) string {
+func (c *Client) callRawContext(ctx context.Context, body json.RawMessage) string {
+	if isBatch(body) {
+		return c.callBatchMethods(ctx, body)
+	}
+
+	return c.callSingleMethod(ctx, body)
+}
+
+// callBatchMethods handles batched JSON-RPC requests, calling each of
+// individual requests one by one and constructing proper batched response.
+//
+// See http://www.jsonrpc.org/specification#batch for details.
+//
+// We can't use gethtrpc.BatchCall here, because each call should go through
+// our routing logic and router to corresponding destination.
+func (c *Client) callBatchMethods(ctx context.Context, msgs json.RawMessage) string {
+	var requests []json.RawMessage
+
+	err := json.Unmarshal(msgs, &requests)
+	if err != nil {
+		return newErrorResponse(errInvalidMessageCode, err, defaultMsgID)
+	}
+
+	// run all methods sequentially, this seems to be main
+	// objective to use batched requests.
+	// See: https://github.com/ethereum/wiki/wiki/JavaScript-API#batch-requests
+	responses := make([]json.RawMessage, len(requests))
+	for i := range requests {
+		resp := c.callSingleMethod(ctx, requests[i])
+		responses[i] = json.RawMessage(resp)
+	}
+
+	data, err := json.Marshal(responses)
+	if err != nil {
+		log.Error("Failed to marshal batch responses:", err)
+		return newErrorResponse(errInvalidMessageCode, err, defaultMsgID)
+	}
+
+	return string(data)
+}
+
+// callSingleMethod executes single JSON-RPC message and constructs proper response.
+func (c *Client) callSingleMethod(ctx context.Context, msg json.RawMessage) string {
 	// unmarshal JSON body into json-rpc request
-	method, params, id, err := methodAndParamsFromBody(body)
+	method, params, id, err := methodAndParamsFromBody(msg)
 	if err != nil {
 		return newErrorResponse(errInvalidMessageCode, err, id)
 	}
@@ -87,7 +128,7 @@ func (c *Client) callRawContext(ctx context.Context, body string) string {
 // JSON-RPC body into values ready to use with ethereum-go's
 // RPC client Call() function. A lot of empty interface usage is
 // due to the underlying code design :/
-func methodAndParamsFromBody(body string) (string, []interface{}, json.RawMessage, error) {
+func methodAndParamsFromBody(body json.RawMessage) (string, []interface{}, json.RawMessage, error) {
 	msg, err := unmarshalMessage(body)
 	if err != nil {
 		return "", nil, nil, err
@@ -105,43 +146,12 @@ func methodAndParamsFromBody(body string) (string, []interface{}, json.RawMessag
 }
 
 // unmarshalMessage tries to unmarshal JSON-RPC message.
-// somehow JSON-RPC input from web3.js can be in two forms:
+func unmarshalMessage(body json.RawMessage) (*jsonrpcMessage, error) {
-//
-// object:  {"jsonrpc":"2.0", …}
-// array:   [{"jsonrpc":"2.0", …}]
-//
-// unmarhsalMessage tries first option and in case of error,
-// tries to unmarshal it as an array.
-//
-// TODO(divan): fix the source of this error and cleanup.
-func unmarshalMessage(body string) (*jsonrpcMessage, error) {
 	var msg jsonrpcMessage
-	err := json.Unmarshal([]byte(body), &msg)
+	err := json.Unmarshal(body, &msg)
-	// check for array case
-	if e, ok := err.(*json.UnmarshalTypeError); ok {
-		if e.Value == "array" {
-			return unmarshalMessageArray(body)
-		}
-	}
 	return &msg, err
 }
 
-func unmarshalMessageArray(body string) (*jsonrpcMessage, error) {
-	var msgs []*jsonrpcMessage
-	err := json.Unmarshal([]byte(body), &msgs)
-	if err != nil {
-		return nil, err
-	}
-
-	// return first element
-	if len(msgs) == 0 {
-		return nil, errors.New("empty array")
-	} else if len(msgs) > 1 {
-		log.Warn("JSON-RPC payload has more then 1 objects", "len", len(msgs), "body", body)
-	}
-	return msgs[0], nil
-}
-
 func newSuccessResponse(result json.RawMessage, id json.RawMessage) string {
 	if id == nil {
 		id = defaultMsgID
@@ -173,3 +183,16 @@ func newErrorResponse(code int, err error, id json.RawMessage) string {
 	data, _ := json.Marshal(errMsg)
 	return string(data)
 }
+
+// isBatch returns true when the first non-whitespace characters is '['
+// code from go-ethereum's rpc client (rpc/client.go)
+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
+}

geth/rpc/call_raw_test.go

@@ -36,7 +36,7 @@ func TestNewErrorResponse(t *testing.T) {
 }
 
 func TestUnmarshalMessage(t *testing.T) {
-	body := `{"jsonrpc": "2.0", "method": "subtract", "params": {"subtrahend": 23, "minuend": 42}}`
+	body := json.RawMessage(`{"jsonrpc": "2.0", "method": "subtract", "params": {"subtrahend": 23, "minuend": 42}}`)
 	got, err := unmarshalMessage(body)
 	require.NoError(t, err)
 
@@ -51,7 +51,7 @@ func TestUnmarshalMessage(t *testing.T) {
 func TestMethodAndParamsFromBody(t *testing.T) {
 	cases := []struct {
 		name       string
-		body       string
+		body       json.RawMessage
 		params     []interface{}
 		method     string
 		id         json.RawMessage
@@ -59,7 +59,7 @@ func TestMethodAndParamsFromBody(t *testing.T) {
 	}{
 		{
 			"params_array",
-			`{"jsonrpc": "2.0", "id": 42, "method": "subtract", "params": [{"subtrahend": 23, "minuend": 42}]}`,
+			json.RawMessage(`{"jsonrpc": "2.0", "id": 42, "method": "subtract", "params": [{"subtrahend": 23, "minuend": 42}]}`),
 			[]interface{}{
 				map[string]interface{}{
 					"subtrahend": float64(23),
@@ -72,7 +72,7 @@ func TestMethodAndParamsFromBody(t *testing.T) {
 		},
 		{
 			"params_empty_array",
-			`{"jsonrpc": "2.0", "method": "test", "params": []}`,
+			json.RawMessage(`{"jsonrpc": "2.0", "method": "test", "params": []}`),
 			[]interface{}{},
 			"test",
 			nil,
@@ -80,7 +80,7 @@ func TestMethodAndParamsFromBody(t *testing.T) {
 		},
 		{
 			"params_none",
-			`{"jsonrpc": "2.0", "method": "test"}`,
+			json.RawMessage(`{"jsonrpc": "2.0", "method": "test"}`),
 			[]interface{}{},
 			"test",
 			nil,
@@ -88,7 +88,7 @@ func TestMethodAndParamsFromBody(t *testing.T) {
 		},
 		{
 			"getFilterMessage",
-			`{"jsonrpc":"2.0","id":44,"method":"shh_getFilterMessages","params":["3de6a8867aeb75be74d68478b853b4b0e063704d30f8231c45d0fcbd97af207e"]}`,
+			json.RawMessage(`{"jsonrpc":"2.0","id":44,"method":"shh_getFilterMessages","params":["3de6a8867aeb75be74d68478b853b4b0e063704d30f8231c45d0fcbd97af207e"]}`),
 			[]interface{}{string("3de6a8867aeb75be74d68478b853b4b0e063704d30f8231c45d0fcbd97af207e")},
 			"shh_getFilterMessages",
 			json.RawMessage(`44`),
@@ -96,15 +96,15 @@ func TestMethodAndParamsFromBody(t *testing.T) {
 		},
 		{
 			"getFilterMessage_array",
-			`[{"jsonrpc":"2.0","id":44,"method":"shh_getFilterMessages","params":["3de6a8867aeb75be74d68478b853b4b0e063704d30f8231c45d0fcbd97af207e"]}]`,
+			json.RawMessage(`[{"jsonrpc":"2.0","id":44,"method":"shh_getFilterMessages","params":["3de6a8867aeb75be74d68478b853b4b0e063704d30f8231c45d0fcbd97af207e"]}]`),
-			[]interface{}{string("3de6a8867aeb75be74d68478b853b4b0e063704d30f8231c45d0fcbd97af207e")},
+			[]interface{}{},
-			"shh_getFilterMessages",
+			"",
-			json.RawMessage(`44`),
+			nil,
-			false,
+			true,
 		},
 		{
 			"empty_array",
-			`[]`,
+			json.RawMessage(`[]`),
 			[]interface{}{},
 			"",
 			nil,
@@ -117,6 +117,7 @@ func TestMethodAndParamsFromBody(t *testing.T) {
 			method, params, id, err := methodAndParamsFromBody(test.body)
 			if test.shouldFail {
 				require.Error(t, err)
+				return
 			}
 			require.NoError(t, err)
 			require.Equal(t, test.method, method)
@@ -125,3 +126,21 @@ func TestMethodAndParamsFromBody(t *testing.T) {
 		})
 	}
 }
+
+func TestIsBatch(t *testing.T) {
+	cases := []struct {
+		name     string
+		body     json.RawMessage
+		expected bool
+	}{
+		{"single", json.RawMessage(`{"jsonrpc":"2.0","id":44,"method":"shh_getFilterMessages","params":["3de6a8867aeb75be74d68478b853b4b0e063704d30f8231c45d0fcbd97af207e"]}`), false},
+		{"array", json.RawMessage(`[{"jsonrpc":"2.0","id":44,"method":"shh_getFilterMessages","params":["3de6a8867aeb75be74d68478b853b4b0e063704d30f8231c45d0fcbd97af207e"]}]`), true},
+	}
+
+	for _, test := range cases {
+		t.Run(test.name, func(t *testing.T) {
+			got := isBatch(test.body)
+			require.Equal(t, test.expected, got)
+		})
+	}
+}

geth/rpc/client_test.go

@@ -209,6 +209,22 @@ func (s *RPCTestSuite) TestCallRPC() {
 				progress <- struct{}{}
 			},
 		},
+		{
+			`[{"jsonrpc":"2.0","method":"net_version","params":[],"id":67}]`,
+			func(resultJSON string) {
+				expected := `[{"jsonrpc":"2.0","id":67,"result":"4"}]`
+				s.Equal(expected, resultJSON)
+				progress <- struct{}{}
+			},
+		},
+		{
+			`[{"jsonrpc":"2.0","method":"net_version","params":[],"id":67},{"jsonrpc":"2.0","method":"web3_sha3","params":["0x68656c6c6f20776f726c64"],"id":68}]`,
+			func(resultJSON string) {
+				expected := `[{"jsonrpc":"2.0","id":67,"result":"4"},{"jsonrpc":"2.0","id":68,"result":"0x47173285a8d7341e5e972fc677286384f802f8ef42a5ec5f03bbfa254cb01fad"}]`
+				s.Equal(expected, resultJSON)
+				progress <- struct{}{}
+			},
+		},
 	}
 
 	cnt := len(rpcCalls) - 1 // send transaction blocks up until complete/discarded/times out

geth/rpc/doc.go

@@ -1,5 +1,5 @@
 /*
-rpc - JSON-RPC client with custom routing.
+Package rpc - JSON-RPC client with custom routing.
 
 Package rpc implements status-go JSON-RPC client and handles
 requests to different endpoints: upstream or local node.