rpc: minor cleanups to RPC PR

rpc/http.go

@@ -20,6 +20,7 @@ import (
 	"bytes"
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -151,41 +152,36 @@ func (srv *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	if r.Method == "GET" && r.ContentLength == 0 && r.URL.RawQuery == "" {
 		return
 	}
-	if responseCode, errorMessage := httpErrorResponse(r); responseCode != 0 {
-		http.Error(w, errorMessage, responseCode)
+	if code, err := validateRequest(r); err != nil {
+		http.Error(w, err.Error(), code)
 		return
 	}
-
 	// All checks passed, create a codec that reads direct from the request body
 	// untilEOF and writes the response to w and order the server to process a
 	// single request.
 	codec := NewJSONCodec(&httpReadWriteNopCloser{r.Body, w})
 	defer codec.Close()
 
-	w.Header().Set("content-type", "application/json")
+	w.Header().Set("content-type", contentType)
 	srv.ServeSingleRequest(codec, OptionMethodInvocation)
 }
 
-// Returns a non-zero response code and error message if the request is invalid.
-func httpErrorResponse(r *http.Request) (int, string) {
+// validateRequest returns a non-zero response code and error message if the
+// request is invalid.
+func validateRequest(r *http.Request) (int, error) {
 	if r.Method == "PUT" || r.Method == "DELETE" {
-		errorMessage := "method not allowed"
-		return http.StatusMethodNotAllowed, errorMessage
+		return http.StatusMethodNotAllowed, errors.New("method not allowed")
 	}
-
 	if r.ContentLength > maxHTTPRequestContentLength {
-		errorMessage := fmt.Sprintf("content length too large (%d>%d)", r.ContentLength, maxHTTPRequestContentLength)
-		return http.StatusRequestEntityTooLarge, errorMessage
+		err := fmt.Errorf("content length too large (%d>%d)", r.ContentLength, maxHTTPRequestContentLength)
+		return http.StatusRequestEntityTooLarge, err
 	}
-
-	ct := r.Header.Get("content-type")
-	mt, _, err := mime.ParseMediaType(ct)
+	mt, _, err := mime.ParseMediaType(r.Header.Get("content-type"))
 	if err != nil || mt != contentType {
-		errorMessage := fmt.Sprintf("invalid content type, only %s is supported", contentType)
-		return http.StatusUnsupportedMediaType, errorMessage
+		err := fmt.Errorf("invalid content type, only %s is supported", contentType)
+		return http.StatusUnsupportedMediaType, err
 	}
-
-	return 0, ""
+	return 0, nil
 }
 
 func newCorsHandler(srv *Server, allowedOrigins []string) http.Handler {

rpc/http_test.go

+// Copyright 2017 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 (
@@ -8,33 +24,31 @@ import (
 )
 
 func TestHTTPErrorResponseWithDelete(t *testing.T) {
-	httpErrorResponseTest(t, "DELETE", contentType, "", http.StatusMethodNotAllowed)
+	testHTTPErrorResponse(t, "DELETE", contentType, "", http.StatusMethodNotAllowed)
 }
 
 func TestHTTPErrorResponseWithPut(t *testing.T) {
-	httpErrorResponseTest(t, "PUT", contentType, "", http.StatusMethodNotAllowed)
+	testHTTPErrorResponse(t, "PUT", contentType, "", http.StatusMethodNotAllowed)
 }
 
 func TestHTTPErrorResponseWithMaxContentLength(t *testing.T) {
 	body := make([]rune, maxHTTPRequestContentLength+1, maxHTTPRequestContentLength+1)
-	httpErrorResponseTest(t,
+	testHTTPErrorResponse(t,
 		"POST", contentType, string(body), http.StatusRequestEntityTooLarge)
 }
 
 func TestHTTPErrorResponseWithEmptyContentType(t *testing.T) {
-	httpErrorResponseTest(t, "POST", "", "", http.StatusUnsupportedMediaType)
+	testHTTPErrorResponse(t, "POST", "", "", http.StatusUnsupportedMediaType)
 }
 
 func TestHTTPErrorResponseWithValidRequest(t *testing.T) {
-	httpErrorResponseTest(t, "POST", contentType, "", 0)
+	testHTTPErrorResponse(t, "POST", contentType, "", 0)
 }
 
-func httpErrorResponseTest(t *testing.T,
-	method, contentType, body string, expectedResponse int) {
-
+func testHTTPErrorResponse(t *testing.T, method, contentType, body string, expected int) {
 	request := httptest.NewRequest(method, "http://url.com", strings.NewReader(body))
 	request.Header.Set("content-type", contentType)
-	if response, _ := httpErrorResponse(request); response != expectedResponse {
-		t.Fatalf("response code should be %d not %d", expectedResponse, response)
+	if code, _ := validateRequest(request); code != expected {
+		t.Fatalf("response code should be %d not %d", expected, code)
 	}
 }