Proxy post.url if it is an image (fixes #5538) (#5545)

Co-authored-by: Dessalines <[email protected]>

Author: Nutomic

crates/api_common/src/request.rs

@@ -213,6 +213,13 @@ pub async fn generate_post_link_metadata(
   let allow_sensitive = local_site_opt_to_sensitive(&local_site);
   let allow_generate_thumbnail = allow_sensitive || !post.nsfw;
 
+  // Proxy the post url itself if it is an image
+  let url = if let (true, Some(url)) = (is_image_post, post.url.clone()) {
+    Some(Some(proxy_image_link(url.into(), &context).await?))
+  } else {
+    None
+  };
+
   let image_url = if is_image_post {
     post.url
   } else {
@@ -239,6 +246,7 @@ pub async fn generate_post_link_metadata(
   };
 
   let form = PostUpdateForm {
+    url,
     embed_title: Some(metadata.opengraph_data.title),
     embed_description: Some(metadata.opengraph_data.description),
     embed_video_url: Some(metadata.opengraph_data.embed_video_url),