[NopeCharon]

Summary

With the thumbnail display option enabled, the list of articles still loaded the thumbnails directly from the source, even though the article content was proxied (#200, also mentioned in #206). FreshRSS takes these thumbnails from:

• the thumbnail attribute of the entry, e.g. an item-level <media:thumbnail>
• the thumbnails of the enclosures, e.g. <media:thumbnail> inside a <media:group>, as in YouTube feeds
• the images of the content, which were already proxied

The entry_before_display hook now proxies the first two as well:

• FreshRSS stores these URLs HTML-encoded, so the new getProxyImageHtmlUri() decodes them, proxies them and encodes the result again (e.g. ?w=1&h=2, or the & of a proxy URL like the nginx example in the README)
• when the enclosures are displayed, FreshRSS appends the thumbnail to the content unless its URL is already there. So the thumbnail attribute is only proxied when the proxied URL is found in the proxied content, which is the case when the content shows the thumbnail as an image. If the content only links to the image (<a href="…">), the thumbnail keeps its original URL instead of being shown twice. When the enclosures are hidden, the thumbnail is always proxied
• the thumbnails of the enclosures are not compared to the content, so they are always proxied
• regression tests for the HTML-encoded URLs, version 1.1.1 and a changelog entry

Image enclosures used as a thumbnail when the feed has no thumbnail are not changed: proxying them would change the enclosure URLs that the APIs return.

Fixes #200

Validation

• php tests/ImageProxyTest.php on PHP 8.1 and 8.5 (44 assertions). The new test fails on main (getProxyImageHtmlUri() does not exist)
• end to end with FreshRSS edge (PHP 8.5, SQLite) and the extension enabled. I used a local feed with an item <media:thumbnail> (with & in its URL), a <media:group> thumbnail, a thumbnail that is also a body image, and a thumbnail that the body only links to. Then I fetched the normal view with the landscape thumbnails enabled:
  • on main, all four list thumbnails use the original URLs
  • with this change, the first three use the proxy and the linked one keeps its original URL. The article content is byte-for-byte the same as on main, so no image is duplicated
  • with Show enclosures disabled, all four list thumbnails use the proxy
  • with proxy_url = https://www.example.org/proxy?key=changeme&url=, scheme_include = 1 and url_encode = 0, the thumbnails are proxied and correctly encoded (&), with no duplicates
  • the RSS output (a=rss) now also proxies <media:thumbnail>, like it already proxied the description
• php-lint, phpcs, phpstan (with ../FreshRSS, on PHP 8.1 and 8.5) and markdownlint

[Alkarex]

Let's finalise #578 first