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>

api/handler/cloudevents/cloudevents.go

@@ -12,7 +12,7 @@ import (
 )
 
 type event struct {
-	options handler.Options
+	opts handler.Options
 }
 
 var (
@@ -58,10 +58,17 @@ func evRoute(ns, p string) (string, string) {
 }
 
 func (e *event) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	bsize := handler.DefaultMaxRecvSize
+	if e.opts.MaxRecvSize > 0 {
+		bsize = e.opts.MaxRecvSize
+	}
+
+	r.Body = http.MaxBytesReader(w, r.Body, bsize)
+
 	// request to topic:event
 	// create event
 	// publish to topic
-	topic, _ := evRoute(e.options.Namespace, r.URL.Path)
+	topic, _ := evRoute(e.opts.Namespace, r.URL.Path)
 
 	// create event
 	ev, err := FromRequest(r)
@@ -71,7 +78,7 @@ func (e *event) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	}
 
 	// get client
-	c := e.options.Service.Client()
+	c := e.opts.Service.Client()
 
 	// create publication
 	p := c.NewMessage(topic, ev)
@@ -89,6 +96,6 @@ func (e *event) String() string {
 
 func NewHandler(opts ...handler.Option) handler.Handler {
 	return &event{
-		options: handler.NewOptions(opts...),
+		opts: handler.NewOptions(opts...),
 	}
 }

api/handler/cloudevents/event.go

@@ -24,7 +24,6 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"io/ioutil"
 	"mime"
 	"net/http"
 	"strings"
@@ -32,9 +31,14 @@ import (
 	"unicode"
 
 	"github.com/google/uuid"
+	"github.com/oxtoacart/bpool"
 	validator "gopkg.in/go-playground/validator.v9"
 )
 
+var (
+	bufferPool = bpool.NewSizedBufferPool(1024, 8)
+)
+
 const (
 	// TransformationVersion is indicative of the revision of how Event Gateway transforms a request into CloudEvents format.
 	TransformationVersion = "0.1"
@@ -97,10 +101,12 @@ func FromRequest(r *http.Request) (*Event, error) {
 	// Read request body
 	body := []byte{}
 	if r.Body != nil {
-		body, err = ioutil.ReadAll(r.Body)
-		if err != nil {
+		buf := bufferPool.Get()
+		defer bufferPool.Put(buf)
+		if _, err := buf.ReadFrom(r.Body); err != nil {
 			return nil, err
 		}
+		body = buf.Bytes()
 	}
 
 	var event *Event