treat 0 max request size limit as unlimited

app/proxy/proxy.go

@@ -106,7 +106,7 @@ func (h *Http) Run(ctx context.Context) error {
 		h.headersHandler(h.ProxyHeaders),
 		h.accessLogHandler(h.AccessLog),
 		h.stdoutLogHandler(h.StdOutEnabled, logger.New(logger.Log(log.Default()), logger.Prefix("[INFO]")).Handler),
-		R.SizeLimit(h.MaxBodySize),
+		h.maxReqSizeHandler(h.MaxBodySize),
 		h.gzipHandler(),
 	)
 
@@ -335,6 +335,17 @@ func (h *Http) stdoutLogHandler(enable bool, lh func(next http.Handler) http.Han
 	}
 }
 
+func (h *Http) maxReqSizeHandler(maxSize int64) func(next http.Handler) http.Handler {
+	if maxSize <= 0 {
+		return func(next http.Handler) http.Handler {
+			return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+				next.ServeHTTP(w, r)
+			})
+		}
+	}
+	return R.SizeLimit(maxSize)
+}
+
 func (h *Http) makeHTTPServer(addr string, router http.Handler) *http.Server {
 	return &http.Server{
 		Addr:              addr,

app/proxy/proxy_test.go

@@ -1,6 +1,7 @@
 package proxy
 
 import (
+	"bytes"
 	"context"
 	"fmt"
 	"io"
@@ -248,7 +249,70 @@ func TestHttp_DoWithAssetRules(t *testing.T) {
 		assert.Equal(t, "", resp.Header.Get("h1"))
 		assert.Equal(t, "public, max-age=43200", resp.Header.Get("Cache-Control"))
 	}
+}
 
+func TestHttp_DoLimitedReq(t *testing.T) {
+	port := rand.Intn(10000) + 40000
+	h := Http{Timeouts: Timeouts{ResponseHeader: 200 * time.Millisecond}, Address: fmt.Sprintf("127.0.0.1:%d", port),
+		AccessLog: io.Discard, Signature: true, ProxyHeaders: []string{"hh1:vv1", "hh2:vv2"}, StdOutEnabled: true,
+		Reporter: &ErrorReporter{Nice: true}, MaxBodySize: 10}
+	ctx, cancel := context.WithTimeout(context.Background(), 500*time.Millisecond)
+	defer cancel()
+
+	ds := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		t.Logf("req: %v", r)
+		w.Header().Add("h1", "v1")
+		require.Equal(t, "127.0.0.1", r.Header.Get("X-Real-IP"))
+		fmt.Fprintf(w, "response %s", r.URL.String())
+	}))
+
+	svc := discovery.NewService([]discovery.Provider{
+		&provider.Static{Rules: []string{
+			"localhost,^/api/(.*)," + ds.URL + "/123/$1,",
+			"127.0.0.1,^/api/(.*)," + ds.URL + "/567/$1,",
+		},
+		}}, time.Millisecond*10)
+
+	go func() {
+		_ = svc.Run(context.Background())
+	}()
+
+	time.Sleep(50 * time.Millisecond)
+	h.Matcher, h.Metrics = svc, mgmt.NewMetrics()
+
+	go func() {
+		_ = h.Run(ctx)
+	}()
+	time.Sleep(10 * time.Millisecond)
+
+	client := http.Client{}
+
+	{
+		req, err := http.NewRequest("POST", "http://127.0.0.1:"+strconv.Itoa(port)+"/api/something", bytes.NewBufferString("abcdefg"))
+		require.NoError(t, err)
+		resp, err := client.Do(req)
+		require.NoError(t, err)
+		defer resp.Body.Close()
+		assert.Equal(t, http.StatusOK, resp.StatusCode)
+		t.Logf("%+v", resp.Header)
+
+		body, err := io.ReadAll(resp.Body)
+		require.NoError(t, err)
+		assert.Equal(t, "response /567/something", string(body))
+		assert.Equal(t, "reproxy", resp.Header.Get("App-Name"))
+		assert.Equal(t, "v1", resp.Header.Get("h1"))
+		assert.Equal(t, "vv1", resp.Header.Get("hh1"))
+		assert.Equal(t, "vv2", resp.Header.Get("hh2"))
+	}
+
+	{
+		req, err := http.NewRequest("POST", "http://127.0.0.1:"+strconv.Itoa(port)+"/api/something", bytes.NewBufferString("abcdefg1234567"))
+		require.NoError(t, err)
+		resp, err := client.Do(req)
+		require.NoError(t, err)
+		defer resp.Body.Close()
+		assert.Equal(t, http.StatusRequestEntityTooLarge, resp.StatusCode)
+	}
 }
 
 func TestHttp_toHttp(t *testing.T) {