fix: store HTTP last modified date from response header

[zl4bv]

This addresses a scenario where a server providing a feed responds with a Last-Modified header that is derived from a file modification time. A static site generator, for example, may re-create a feed file without making changes to the file contents - in particular the pubDate for any feed items. Now the mtime and Last-Modified header have a date that is newer than any pubDate elements.

If News sends a request with a If-Modified-Since header based on the older pubDate then the server will respond with 200 and send the entire feed file contents even though the feed has not logically changed. To minimise server bandwidth, ideally News sends a last modified date based on the Last-Modified header it received during the last fetch so that the server can respond with 304.

Summary

• When an HTTP Last-Modified header is present store the value from the header.

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Changelog entry added for all important changes.

[Grotax]

Hey,

I think this:

news/lib/Fetcher/FeedFetcher.php

Lines 506 to 509 in caaace3

	if ($feed->getLastModified() instanceof DateTime) {
	$newFeed->setHttpLastModified($feed->getLastModified()->format(DateTime::RSS));
	}
	$newFeed->setAdded($this->time->getTime());

can be removed then otherwise it would set the date first and then the new logic would overwrite the field again.

[zl4bv]

Apologies for the delayed response. Been on vacation and still catching up on things.

Appreciate your feedback that that line isn't needed.

[plum-pan]

Confirming this issue is fixed, user was requesting feeds from my apache server and was previously pulling a new feed every request, now they're getting 304 unless there's something new to get. 🎉

They were on alpha08 before, now alpha11. Had to get in touch to find out the old version, very glad the new one updates the user-agent too.