Use httpLastModified field for If-Modified-Since header when fetching feed updates

Signed-off-by: Robert Wunderer <robert.wunderer@caprisys.at>

4 files changed, 13 insertions, 4 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 01ca3c80d..5930ea915 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@ The format is mostly based on [Keep a Changelog](https://keepachangelog.com/en/1
 ### Changed
 
 ### Fixed
+- Use httpLastModified field for If-Modified-Since header when fetching feed updates
 
 # Releases
 ## [21.1.0] - 2023-03-20
diff --git a/lib/Fetcher/FeedFetcher.php b/lib/Fetcher/FeedFetcher.php
index 8864df084..60d798889 100755
--- a/lib/Fetcher/FeedFetcher.php
+++ b/lib/Fetcher/FeedFetcher.php
@@ -114,15 +114,21 @@ class FeedFetcher implements IFeedFetcher
         string $url,
         bool $fullTextEnabled,
         ?string $user,
-        ?string $password
+        ?string $password,
+        ?string $httpLastModified
     ): array {
         $url2 = new Net_URL2($url);
         if (!is_null($user) && trim($user) !== '') {
             $url2->setUserinfo(rawurlencode($user), rawurlencode($password));
         }
+        if (!is_null($httpLastModified) && trim($httpLastModified) !== '') {
+            $lastModified = new DateTime($httpLastModified);
+        } else {
+            $lastModified = null;
+        }
         $url = $url2->getNormalizedURL();
         $this->reader->resetFilters();
-        $resource = $this->reader->read($url);
+        $resource = $this->reader->read($url, null, $lastModified);
 
         $location     = $resource->getUrl();
         $parsedFeed   = $resource->getFeed();
diff --git a/lib/Fetcher/IFeedFetcher.php b/lib/Fetcher/IFeedFetcher.php
index 45e0915f0..8729858b5 100644
--- a/lib/Fetcher/IFeedFetcher.php
+++ b/lib/Fetcher/IFeedFetcher.php
@@ -37,7 +37,8 @@ interface IFeedFetcher
         string $url,
         bool $fullTextEnabled,
         ?string $user,
-        ?string $password
+        ?string $password,
+        ?string $httpLastModified
     ): array;
 
     /**
diff --git a/lib/Service/FeedServiceV2.php b/lib/Service/FeedServiceV2.php
index 3e02b3971..3610c3e3a 100644
--- a/lib/Service/FeedServiceV2.php
+++ b/lib/Service/FeedServiceV2.php
@@ -267,7 +267,8 @@ class FeedServiceV2 extends Service
                 $location,
                 $feed->getFullTextEnabled(),
                 $feed->getBasicAuthUser(),
-                $feed->getBasicAuthPassword()
+                $feed->getBasicAuthPassword(),
+                $feed->getHttpLastModified()
             );
         } catch (ReadErrorException $ex) {
             $feed->setUpdateErrorCount($feed->getUpdateErrorCount() + 1);