[cpackget] Retry download without User-Agent header

cmd/utils/utils.go

@@ -152,6 +152,16 @@ func DownloadFile(URL string, timeout int) (string, error) {
 	}
 	defer resp.Body.Close()
 
+	if resp.StatusCode == http.StatusNotFound {
+		// resend GET request without user agent header
+		req.Header.Del("User-Agent")
+		resp, err = client.Do(req)
+		if err != nil {
+			log.Error(err)
+			return "", fmt.Errorf("\"%s\": %w", URL, errs.ErrFailedDownloadingFile)
+		}
+	}
+
 	if resp.StatusCode == http.StatusForbidden {
 		cookie := resp.Header.Get("Set-Cookie")
 		if len(cookie) > 0 {

cmd/utils/utils_test.go

@@ -114,6 +114,32 @@ func TestDownloadFile(t *testing.T) {
 		assert.Equal(bytes, goodResponse)
 	})
 
+	t.Run("test download user agent not allowed", func(t *testing.T) {
+		fileName := "file.txt"
+		defer os.Remove(fileName)
+		utils.SetUserAgent("cpackget")
+		goodResponse := []byte("all good")
+		goodServer := httptest.NewServer(
+			http.HandlerFunc(
+				func(w http.ResponseWriter, r *http.Request) {
+					userAgent := r.Header.Get("User-Agent")
+					if len(userAgent) > 0 && strings.Contains(userAgent, "cpackget") {
+						w.WriteHeader(http.StatusNotFound)
+					} else {
+						fmt.Fprint(w, string(goodResponse))
+					}
+				},
+			),
+		)
+		url := goodServer.URL + "/" + fileName
+		_, err1 := utils.DownloadFile(url, 0)
+		assert.Nil(err1)
+		assert.True(utils.FileExists(fileName))
+		bytes, err2 := os.ReadFile(fileName)
+		assert.Nil(err2)
+		assert.Equal(bytes, goodResponse)
+	})
+
 	t.Run("test download set cookie", func(t *testing.T) {
 		fileName := "file.txt"
 		defer os.Remove(fileName)