[gzhttp] Add supported decompress request body (#1002)

* [gzhttp] Add supported decompress request body

gzhttp/compress.go

@@ -464,6 +464,11 @@ 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 c.allowCompressedRequests && contentGzip(r) {
+				r.Header.Del(contentEncoding)
+				r.Body = &gzipReader{body: r.Body}
+			}
+
 			if acceptsGzip(r) {
 				gw := grwPool.Get().(*GzipResponseWriter)
 				*gw = GzipResponseWriter{
@@ -536,17 +541,18 @@ func (pct parsedContentType) equals(mediaType string, params map[string]string)
 
 // Used for functional configuration.
 type config struct {
-	minSize          int
-	level            int
-	writer           writer.GzipWriterFactory
-	contentTypes     func(ct string) bool
-	keepAcceptRanges bool
-	setContentType   bool
-	suffixETag       string
-	dropETag         bool
-	jitterBuffer     int
-	randomJitter     string
-	sha256Jitter     bool
+	minSize                 int
+	level                   int
+	writer                  writer.GzipWriterFactory
+	contentTypes            func(ct string) bool
+	keepAcceptRanges        bool
+	setContentType          bool
+	suffixETag              string
+	dropETag                bool
+	jitterBuffer            int
+	randomJitter            string
+	sha256Jitter            bool
+	allowCompressedRequests bool
 }
 
 func (c *config) validate() error {
@@ -579,6 +585,15 @@ func MinSize(size int) option {
 	}
 }
 
+// AllowCompressedRequests will enable or disable RFC 7694 compressed requests.
+// By default this is Disabled.
+// See https://datatracker.ietf.org/doc/html/rfc7694
+func AllowCompressedRequests(b bool) option {
+	return func(c *config) {
+		c.allowCompressedRequests = b
+	}
+}
+
 // CompressionLevel sets the compression level
 func CompressionLevel(level int) option {
 	return func(c *config) {
@@ -752,6 +767,12 @@ 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 && r.Body != nil && 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 +89,41 @@ func TestMustNewGzipHandler(t *testing.T) {
 	handler.ServeHTTP(res3, req3)
 
 	assertEqual(t, http.DetectContentType([]byte(testBody)), res3.Header().Get("Content-Type"))
+
+	// send compress request body with `AllowCompressedRequests`
+	handler = newTestHandlerLevel(testBody, AllowCompressedRequests(true))
+
+	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))
+
+	// send compress request body without `AllowCompressedRequests`
+	writerGzip = gzip.NewWriter(&b)
+	writerGzip.Write(testBody)
+	writerGzip.Close()
+
+	handler = newTestHandlerLevel(b.Bytes())
+
+	req6, _ := http.NewRequest("POST", "/whatever", &b)
+	resp6 := httptest.NewRecorder()
+	handler.ServeHTTP(resp6, req6)
+	res6 := resp6.Result()
+
+	assertEqual(t, 200, res6.StatusCode)
+	body, _ = io.ReadAll(res6.Body)
+	assertEqual(t, b.Len(), len(body))
 }
 
 func TestGzipHandlerSmallBodyNoCompression(t *testing.T) {