From 55cf75def96983ef510657b03344d3facbf6aa94 Mon Sep 17 00:00:00 2001
From: Hans-Peter Lehmann <ByteHamster@users.noreply.github.com>
Date: Thu, 28 May 2026 16:39:10 +0200
Subject: [PATCH] Add if-range header when downloading (#8491)

### Description

Add if-range header when downloading. Only resume download if the server
tells us that the file didn't change in the meantime. This can happen
especially in the presence of dynamic ad insertion.

Original idea by @bushnelb in #8441

### Checklist
<!--
To help us keep the issue tracker clean and work as efficient as
possible,
  please make sure that you have done all of the following.
You can tick the boxes below by placing an x inside the brackets like
this: [x]
-->
- [x] I have read the contribution guidelines:
https://github.com/AntennaPod/AntennaPod/blob/develop/CONTRIBUTING.md#submit-a-pull-request
- [x] I have performed a self-review of my code, going through my
changes line by line and carefully considering why this line change is
necessary
- [x] I have run the automated code checks using `./gradlew checkstyle
lint`
- [x] My code follows the style guidelines of the AntennaPod project:
https://antennapod.org/contribute/develop/app/code-style
- [x] I have mentioned the corresponding issue and the relevant keyword
(e.g., "Closes: #xy") in the description (see
https://docs.github.com/en/issues/tracking-your-work-with-issues/linking-a-pull-request-to-an-issue)
- [x] If it is a core feature, I have added automated tests

Co-authored-by: bushnelb <134662243+bushnelb@users.noreply.github.com>
---
 .../net/download/service/feed/remote/HttpDownloader.java     | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/net/download/service/src/main/java/de/danoeh/antennapod/net/download/service/feed/remote/HttpDownloader.java b/net/download/service/src/main/java/de/danoeh/antennapod/net/download/service/feed/remote/HttpDownloader.java
index 2a99c2bbb..4ce2960f3 100644
--- a/net/download/service/src/main/java/de/danoeh/antennapod/net/download/service/feed/remote/HttpDownloader.java
+++ b/net/download/service/src/main/java/de/danoeh/antennapod/net/download/service/feed/remote/HttpDownloader.java
@@ -92,6 +92,11 @@ public class HttpDownloader extends Downloader {
                 request.setSoFar(destination.length());
                 httpReq.addHeader("Range", "bytes=" + request.getSoFar() + "-");
                 Log.d(TAG, "Adding range header: " + request.getSoFar());
+                // Only continue if the etag matches, otherwise the file might have changed
+                if (!TextUtils.isEmpty(request.getLastModified())) {
+                    httpReq.addHeader("If-Range", request.getLastModified());
+                    Log.d(TAG, "Adding If-Range header: " + request.getLastModified());
+                }
             }
 
             Response response = newCall(httpReq);