return ErrBodylessRequest on get method etc.

rest/httpx/requests.go

@@ -83,8 +83,13 @@ func ParseHeader(headerValue string) map[string]string {
 
 // Parses the post request which contains json in body.
 func ParseJsonBody(r *http.Request, v interface{}) error {
-	var reader io.Reader
+	switch r.Method {
+	case http.MethodDelete, http.MethodPatch, http.MethodPost, http.MethodPut:
+	default:
+		return ErrBodylessRequest
+	}
 
+	var reader io.Reader
 	if withJsonBody(r) {
 		reader = io.LimitReader(r.Body, maxBodyLen)
 	} else {

rest/httpx/requests_test.go

@@ -134,6 +134,26 @@ func BenchmarkParseRaw(b *testing.B) {
 	}
 }
 
+func TestParseJsonBodyless(t *testing.T) {
+	methods := []string{
+		http.MethodConnect,
+		http.MethodGet,
+		http.MethodHead,
+		http.MethodOptions,
+		http.MethodTrace,
+	}
+
+	for _, method := range methods {
+		t.Run(method, func(t *testing.T) {
+			r, err := http.NewRequest(http.MethodGet, "http://hello.com", nil)
+			if err != nil {
+				t.Fatal(err)
+			}
+			assert.Equal(t, ErrBodylessRequest, ParseJsonBody(r, nil))
+		})
+	}
+}
+
 func BenchmarkParseAuto(b *testing.B) {
 	r, err := http.NewRequest(http.MethodGet, "http://hello.com/a?name=hello&age=18&percent=3.4", nil)
 	if err != nil {

rest/httpx/constants.go → rest/httpx/vars.go

@@ -1,5 +1,7 @@
 package httpx
 
+import "errors"
+
 const (
 	ApplicationJson = "application/json"
 	ContentEncoding = "Content-Encoding"
@@ -17,3 +19,5 @@ const (
 	CodeSignatureWrongTime
 	CodeSignatureInvalidToken
 )
+
+var ErrBodylessRequest = errors.New("not a POST|PUT|PATCH request")