api/handler: use http.MaxBytesReader and buffer pool (#1415)

* api/handler: use http.MaxBytesReader

protect api handlers from OOM cases

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

rpc.go

@@ -4,7 +4,6 @@ package rpc
 import (
 	"encoding/json"
 	"io"
-	"io/ioutil"
 	"net/http"
 	"strconv"
 	"strings"
@@ -22,6 +21,7 @@ import (
 	"github.com/micro/go-micro/v2/logger"
 	"github.com/micro/go-micro/v2/registry"
 	"github.com/micro/go-micro/v2/util/ctx"
+	"github.com/oxtoacart/bpool"
 )
 
 const (
@@ -45,6 +45,8 @@ var (
 		"application/proto-rpc",
 		"application/octet-stream",
 	}
+
+	bufferPool = bpool.NewSizedBufferPool(1024, 8)
 )
 
 type rpcHandler struct {
@@ -69,6 +71,13 @@ func strategy(services []*registry.Service) selector.Strategy {
 }
 
 func (h *rpcHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	bsize := handler.DefaultMaxRecvSize
+	if h.opts.MaxRecvSize > 0 {
+		bsize = h.opts.MaxRecvSize
+	}
+
+	r.Body = http.MaxBytesReader(w, r.Body, bsize)
+
 	defer r.Body.Close()
 	var service *api.Service
 
@@ -240,8 +249,8 @@ func requestPayload(r *http.Request) ([]byte, error) {
 		if err := c.ReadBody(&raw); err != nil {
 			return nil, err
 		}
-		b, _ := raw.Marshal()
-		return b, nil
+		b, err := raw.Marshal()
+		return b, err
 	case strings.Contains(ct, "application/www-x-form-urlencoded"):
 		r.ParseForm()
 
@@ -252,8 +261,8 @@ func requestPayload(r *http.Request) ([]byte, error) {
 		}
 
 		// marshal
-		b, _ := json.Marshal(vals)
-		return b, nil
+		b, err := json.Marshal(vals)
+		return b, err
 		// TODO: application/grpc
 	}
 
@@ -265,7 +274,12 @@ func requestPayload(r *http.Request) ([]byte, error) {
 			return qson.ToJSON(r.URL.RawQuery)
 		}
 	case "PATCH", "POST":
-		return ioutil.ReadAll(r.Body)
+		buf := bufferPool.Get()
+		defer bufferPool.Put(buf)
+		if _, err := buf.ReadFrom(r.Body); err != nil {
+			return nil, err
+		}
+		return buf.Bytes(), nil
 	}
 
 	return []byte{}, nil