fix: correctly handle status-code 204

As the status-code 204 is part of the 2xx family, it should also be considered
successful signaling that there is no body to read.

This fixes #11755

Signed-off-by: Markus Freitag <fmarkus@mailbox.org>
Signed-off-by: Andrey Smirnov <andrey.smirnov@siderolabs.com>
(cherry picked from commit 43b5b9d)

Author: MarkusFreitag

pkg/download/download.go

@@ -262,6 +262,11 @@ func download(req *http.Request, options *downloadOptions) (data []byte, err err
 		return data, options.ErrorOnBadRequest
 	}
 
+	// 204 - StatusNoContent is also a successful response, signaling  that there is no body
+	if resp.StatusCode == http.StatusNoContent {
+		return data, options.ErrorOnEmptyResponse
+	}
+
 	if resp.StatusCode != http.StatusOK {
 		// try to read first 32 bytes of the response body
 		// to provide more context in case of error

pkg/download/download_test.go

@@ -59,6 +59,8 @@ func TestDownload(t *testing.T) {
 		case "/404":
 			w.WriteHeader(http.StatusNotFound)
 			fmt.Fprintln(w, "not found")
+		case "/204":
+			w.WriteHeader(http.StatusNoContent)
 		default:
 			w.WriteHeader(http.StatusInternalServerError)
 		}
@@ -87,6 +89,11 @@ func TestDownload(t *testing.T) {
 			path:     "/empty",
 			expected: "",
 		},
+		{
+			name:     "empty download with 204",
+			path:     "/204",
+			expected: "",
+		},
 		{
 			name:     "some data",
 			path:     "/data",
@@ -104,6 +111,12 @@ func TestDownload(t *testing.T) {
 			opts:          []download.Option{download.WithErrorOnEmptyResponse(errors.New("empty response"))},
 			expectedError: "empty response",
 		},
+		{
+			name:          "empty error by 204",
+			path:          "/204",
+			opts:          []download.Option{download.WithErrorOnEmptyResponse(errors.New("empty response"))},
+			expectedError: "empty response",
+		},
 		{
 			name:          "not found error",
 			path:          "/404",