[gzhttp] Add supported decompress request body

gzhttp/compress.go

@@ -464,6 +464,12 @@ func NewWrapper(opts ...option) (func(http.Handler) http.HandlerFunc, error) {
 	return func(h http.Handler) http.HandlerFunc {
 		return func(w http.ResponseWriter, r *http.Request) {
 			w.Header().Add(vary, acceptEncoding)
+			if contentGzip(r) {
+				if readerGzipBody, err := gzip.NewReader(r.Body); err == nil {
+					r.Body = io.NopCloser(readerGzipBody)
+				}
+			}
+
 			if acceptsGzip(r) {
 				gw := grwPool.Get().(*GzipResponseWriter)
 				*gw = GzipResponseWriter{
@@ -752,6 +758,12 @@ func RandomJitter(n, buffer int, paranoid bool) option {
 	}
 }
 
+// contentGzip returns true if the given HTTP request indicates that it gzipped.
+func contentGzip(r *http.Request) bool {
+	// See more detail in `acceptsGzip`
+	return r.Method != http.MethodHead && parseEncodingGzip(r.Header.Get(contentEncoding)) > 0
+}
+
 // acceptsGzip returns true if the given HTTP request indicates that it will
 // accept a gzipped response.
 func acceptsGzip(r *http.Request) bool {

gzhttp/compress_test.go

@@ -89,6 +89,24 @@ func TestMustNewGzipHandler(t *testing.T) {
 	handler.ServeHTTP(res3, req3)
 
 	assertEqual(t, http.DetectContentType([]byte(testBody)), res3.Header().Get("Content-Type"))
+
+	// send compress request body
+
+	var b bytes.Buffer
+	writerGzip := gzip.NewWriter(&b)
+	writerGzip.Write(testBody)
+	writerGzip.Close()
+
+	req5, _ := http.NewRequest("POST", "/whatever", &b)
+	req5.Header.Set("Content-Encoding", "gzip")
+	resp5 := httptest.NewRecorder()
+	handler.ServeHTTP(resp5, req5)
+	res5 := resp5.Result()
+
+	assertEqual(t, 200, res5.StatusCode)
+
+	body, _ := io.ReadAll(res5.Body)
+	assertEqual(t, len(testBody), len(body))
 }
 
 func TestGzipHandlerSmallBodyNoCompression(t *testing.T) {