Resolve links to remote posts into local URL (#5057)

* move code to new file

* rewrite markdown links (fixes #2987)

* add missing file

* add helper fn

* also convert post.url

* simplify search.rs

* clippy

* also rewrite user/community links in markdown

* Call from apub handlers, cleanup

* no network requests in test

* clippy

* fix tests

* serial

* test

* no mut

* add api test

* fix api test

Cargo.lock

@@ -42,7 +42,7 @@ dependencies = [
  "pin-project-lite",
  "rand",
  "regex",
- "reqwest 0.12.8",
+ "reqwest 0.12.7",
  "reqwest-middleware",
  "rsa",
  "serde",
@@ -490,9 +490,9 @@ dependencies = [
 
 [[package]]
 name = "async-trait"
-version = "0.1.83"
+version = "0.1.82"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "721cae7de5c34fbb2acd27e21e6d2cf7b886dce0c27388d46c4e6c47ea4318dd"
+checksum = "a27b8a3a6e1a44fa4c8baf1f653e4172e81486d4941f2237e20dc2d0cf4ddff1"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -839,9 +839,9 @@ dependencies = [
 
 [[package]]
 name = "clap"
-version = "4.5.18"
+version = "4.5.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b0956a43b323ac1afaffc053ed5c4b7c1f1800bacd1683c353aabbb752515dd3"
+checksum = "3e5a21b8495e732f1b3c364c9949b201ca7bae518c502c80256c96ad79eaf6ac"
 dependencies = [
  "clap_builder",
  "clap_derive",
@@ -849,9 +849,9 @@ dependencies = [
 
 [[package]]
 name = "clap_builder"
-version = "4.5.18"
+version = "4.5.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4d72166dd41634086d5803a47eb71ae740e61d84709c36f3c34110173db3961b"
+checksum = "8cf2dd12af7a047ad9d6da2b6b249759a22a7abc0f474c1dae1777afa4b21a73"
 dependencies = [
  "anstream",
  "anstyle",
@@ -861,9 +861,9 @@ dependencies = [
 
 [[package]]
 name = "clap_derive"
-version = "4.5.18"
+version = "4.5.13"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4ac6a0c7b1a9e9a5186361f67dfa1b88213572f427fb9ab038efb2bd8c582dab"
+checksum = "501d359d5f3dcaf6ecdeee48833ae73ec6e42723a1e52419c79abf9507eec0a0"
 dependencies = [
  "heck 0.5.0",
  "proc-macro2",
@@ -1989,7 +1989,7 @@ dependencies = [
  "base64 0.22.1",
  "http-signature-normalization",
  "httpdate",
- "reqwest 0.12.8",
+ "reqwest 0.12.7",
  "reqwest-middleware",
  "sha2",
  "thiserror",
@@ -2514,7 +2514,7 @@ dependencies = [
  "moka",
  "pretty_assertions",
  "regex",
- "reqwest 0.12.8",
+ "reqwest 0.12.7",
  "reqwest-middleware",
  "rosetta-i18n",
  "serde",
@@ -2579,7 +2579,7 @@ dependencies = [
  "lemmy_utils",
  "moka",
  "pretty_assertions",
- "reqwest 0.12.8",
+ "reqwest 0.12.7",
  "serde",
  "serde_json",
  "serde_with",
@@ -2718,7 +2718,7 @@ dependencies = [
  "lemmy_utils",
  "mockall",
  "moka",
- "reqwest 0.12.8",
+ "reqwest 0.12.7",
  "serde_json",
  "serial_test",
  "test-context",
@@ -2745,7 +2745,7 @@ dependencies = [
  "lemmy_db_views",
  "lemmy_db_views_actor",
  "lemmy_utils",
- "reqwest 0.12.8",
+ "reqwest 0.12.7",
  "reqwest-middleware",
  "rss",
  "serde",
@@ -2778,7 +2778,7 @@ dependencies = [
  "lemmy_utils",
  "pretty_assertions",
  "prometheus",
- "reqwest 0.12.8",
+ "reqwest 0.12.7",
  "reqwest-middleware",
  "reqwest-tracing",
  "rustls 0.23.13",
@@ -2811,7 +2811,7 @@ dependencies = [
  "markdown-it",
  "pretty_assertions",
  "regex",
- "reqwest 0.12.8",
+ "reqwest 0.12.7",
  "reqwest-middleware",
  "rosetta-build",
  "rosetta-i18n",
@@ -3197,9 +3197,9 @@ dependencies = [
 
 [[package]]
 name = "mutually_exclusive_features"
-version = "0.1.0"
+version = "0.0.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e94e1e6445d314f972ff7395df2de295fe51b71821694f0b0e1e79c4f12c8577"
+checksum = "6d02c0b00610773bb7fc61d85e13d86c7858cbdf00e1a120bfc41bc055dbaa0e"
 
 [[package]]
 name = "never"
@@ -3966,9 +3966,9 @@ dependencies = [
 
 [[package]]
 name = "reqwest"
-version = "0.12.8"
+version = "0.12.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f713147fbe92361e52392c73b8c9e48c04c6625bce969ef54dc901e58e042a7b"
+checksum = "f8f4955649ef5c38cc7f9e8aa41761d48fb9677197daea9984dc54f56aad5e63"
 dependencies = [
  "async-compression",
  "base64 0.22.1",
@@ -4019,7 +4019,7 @@ dependencies = [
  "anyhow",
  "async-trait",
  "http 1.1.0",
- "reqwest 0.12.8",
+ "reqwest 0.12.7",
  "serde",
  "thiserror",
  "tower-service",
@@ -4036,7 +4036,7 @@ dependencies = [
  "getrandom",
  "http 1.1.0",
  "matchit",
- "reqwest 0.12.8",
+ "reqwest 0.12.7",
  "reqwest-middleware",
  "tracing",
 ]
@@ -4508,9 +4508,9 @@ checksum = "38b58827f4464d87d377d175e90bf58eb00fd8716ff0a62f80356b5e61555d0d"
 
 [[package]]
 name = "sitemap-rs"
-version = "0.2.2"
+version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3c4c6ab96128064ba085256d34e205153555b3803094d76e24d406c76f85a2c9"
+checksum = "88cc73a9aac975541c9054e74ceae8d8ee85edc89a322404c275c1d100fffa51"
 dependencies = [
  "chrono",
  "xml-builder",
@@ -5106,9 +5106,9 @@ dependencies = [
 
 [[package]]
 name = "tracing-actix-web"
-version = "0.7.13"
+version = "0.7.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "15bc0cd5f72e837e310f4d978a90abf202a7f7d8ef3272246bae381d0086d3bf"
+checksum = "284586dc201db407be8c9d721abad1b3a6dacbbce5cccecd4fd15a37db95ab0d"
 dependencies = [
  "actix-web",
  "mutually_exclusive_features",
@@ -5579,7 +5579,7 @@ version = "0.1.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "cf221c93e13a30d793f7645a0e7762c55d169dbb0a49671918a2319d289b10bb"
 dependencies = [
- "windows-sys 0.48.0",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]

api_tests/src/post.spec.ts

@@ -794,3 +794,29 @@ test("Fetch post with redirect", async () => {
   let gammaPost2 = await gamma.resolveObject(form);
   expect(gammaPost2.post).toBeDefined();
 });
+
+test("Rewrite markdown links", async () => {
+  const community = (await resolveBetaCommunity(beta)).community!;
+
+  // create a post
+  let postRes1 = await createPost(beta, community.community.id);
+
+  // link to this post in markdown
+  let postRes2 = await createPost(
+    beta,
+    community.community.id,
+    "https://example.com/",
+    `[link](${postRes1.post_view.post.ap_id})`,
+  );
+  console.log(postRes2.post_view.post.body);
+  expect(postRes2.post_view.post).toBeDefined();
+
+  // fetch both posts from another instance
+  const alphaPost1 = await resolvePost(alpha, postRes1.post_view.post);
+  const alphaPost2 = await resolvePost(alpha, postRes2.post_view.post);
+
+  // remote markdown link is replaced with local link
+  expect(alphaPost2.post?.post.body).toBe(
+    `[link](http://lemmy-alpha:8541/post/${alphaPost1.post?.post.id})`,
+  );
+});

crates/api_common/src/utils.rs

@@ -52,7 +52,7 @@ use lemmy_utils::{
   rate_limit::{ActionType, BucketConfig},
   settings::structs::{PictrsImageMode, Settings},
   utils::{
-    markdown::{markdown_check_for_blocked_urls, markdown_rewrite_image_links},
+    markdown::{image_links::markdown_rewrite_image_links, markdown_check_for_blocked_urls},
     slurs::{build_slur_regex, remove_slurs},
     validation::clean_urls_in_text,
   },

crates/apub/assets/lemmy/objects/group.json

@@ -3,9 +3,9 @@
   "type": "Group",
   "preferredUsername": "tenforward",
   "name": "Ten Forward",
-  "summary": "<p>Lounge and recreation facility</p>\n<hr />\n<p>Welcome to the <a href=\"https://memory-alpha.fandom.com/wiki/USS_Enterprise_(NCC-1701-D)\">Enterprise</a>!.</p>\n",
+  "summary": "<p>Lounge and recreation facility</p>\n<hr />\n<p>Welcome to the Enterprise!.</p>\n",
   "source": {
-    "content": "Lounge and recreation facility\n\n---\n\nWelcome to the [Enterprise](https://memory-alpha.fandom.com/wiki/USS_Enterprise_(NCC-1701-D))!.",
+    "content": "Lounge and recreation facility\n\n---\n\nWelcome to the Enterprise!",
     "mediaType": "text/markdown"
   },
   "sensitive": false,

crates/apub/assets/pleroma/objects/note.json

@@ -10,7 +10,7 @@
   "attachment": [],
   "attributedTo": "https://queer.hacktivis.me/users/lanodan",
   "cc": ["https://www.w3.org/ns/activitystreams#Public"],
-  "content": "<span class=\"h-card\"><a class=\"u-url mention\" data-user=\"9zkUX4o3WxGM8vGPfU\" href=\"https://pleroma.popolon.org/users/popolon\" rel=\"ugc\">@<span>popolon</span></a></span> Have what?",
+  "content": "Have what?",
   "context": "https://queer.hacktivis.me/contexts/34cba3d2-2f35-4169-aeff-56af9bfeb753",
   "conversation": "https://queer.hacktivis.me/contexts/34cba3d2-2f35-4169-aeff-56af9bfeb753",
   "id": "https://queer.hacktivis.me/objects/8d4973f4-53de-49cd-8c27-df160e16a9c2",

crates/apub/assets/pleroma/objects/person.json

@@ -41,7 +41,7 @@
     "owner": "https://queer.hacktivis.me/users/lanodan",
     "publicKeyPem": "-----BEGIN PUBLIC KEY-----\nMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAsWOgdjSMc010qvxC3njI\nXJlFWMJ5gJ8QXCW/PajYdsHPM6d+jxBNJ6zp9/tIRa2m7bWHTSkuHQ7QthOpt6vu\n+dAWpKRLS607SPLItn/qUcyXvgN+H8shfyhMxvkVs9jXdtlBsLUVE7UNpN0dxzqe\nI79QWbf7o4amgaIWGRYB+OYMnIxKt+GzIkivZdSVSYjfxNnBYkMCeUxm5EpPIxKS\nP5bBHAVRRambD5NUmyKILuC60/rYuc/C+vmgpY2HCWFS2q6o34dPr9enwL6t4b3m\nS1t/EJHk9rGaaDqSGkDEfyQI83/7SDebWKuETMKKFLZi1vMgQIFuOYCIhN6bIiZm\npQIDAQAB\n-----END PUBLIC KEY-----\n\n"
   },
-  "summary": "---<br/>Website: <a href=\"https://hacktivis.me/\">https://hacktivis.me/</a><br/>Lang: Français(natif), English(fluent), LSF(🤏~👌), русский (еле-еле), <br/>Politics: Anarchist as in DIY/DIWO, freedom of association, anti-authoritarian, anti-identitarianism<br/><br/>Pronouns: meh, pick any, have fun<br/>Timezone: Let&#39;s say Mars, I have a non-24h cycle<br/>```<br/>🦊🦄⚧🂡ⓥ :anarchy: 👿🐧 :gentoo:<br/>Pleroma maintainer (mostly backend)<br/>BadWolf developer<br/>Gentoo contributor<br/><br/>Dayjob: yogoko.fr<br/><br/>That person which uses HJKL in games<br/><br/>Just because computer bad: X5O!P%@AP[4\\PZX54(P^)7CC)7}$EICAR-STANDARD-ANTIVIRUS-TEST-FILE!$H+H*<br/><br/>banner from: <a href=\"https://soc.flyingcube.tech/objects/56f79be2-9013-4559-9826-f7dc392417db\">https://soc.flyingcube.tech/objects/56f79be2-9013-4559-9826-f7dc392417db</a><br/>Federation-bots: <a class=\"hashtag\" data-tag=\"nobot\" href=\"https://queer.hacktivis.me/tag/nobot\">#nobot</a>",
+  "summary": "---Lang: Français(natif), English(fluent), LSF(🤏~👌), русский (еле-еле), <br/>Politics: Anarchist as in DIY/DIWO, freedom of association, anti-authoritarian, anti-identitarianism<br/><br/>Pronouns: meh, pick any, have fun<br/>Timezone: Let&#39;s say Mars, I have a non-24h cycle<br/>```<br/>🦊🦄⚧🂡ⓥ :anarchy: 👿🐧 :gentoo:<br/>Pleroma maintainer (mostly backend)<br/>BadWolf developer<br/>Gentoo contributor<br/><br/>Dayjob: yogoko.fr<br/><br/>That person which uses HJKL in games<br/><br/>Just because computer bad: X5O!P%@AP[4\\PZX54(P^)7CC)7}$EICAR-STANDARD-ANTIVIRUS-TEST-FILE!$H+H*<br/><br/>banner from: <a href=\"https://soc.flyingcube.tech/objects/56f79be2-9013-4559-9826-f7dc392417db\">https://soc.flyingcube.tech/objects/56f79be2-9013-4559-9826-f7dc392417db</a><br/>Federation-bots: <a class=\"hashtag\" data-tag=\"nobot\" href=\"https://queer.hacktivis.me/tag/nobot\">#nobot</a>",
   "tag": [
     {
       "icon": {

crates/apub/src/api/resolve_object.rs

@@ -1,4 +1,5 @@
 use crate::fetcher::{
+  post_or_comment::PostOrComment,
   search::{search_query_to_object_id, search_query_to_object_id_local, SearchableObjects},
   user_or_community::UserOrCommunity,
 };
@@ -46,21 +47,22 @@ async fn convert_response(
   local_user_view: Option<LocalUserView>,
   pool: &mut DbPool<'_>,
 ) -> LemmyResult<Json<ResolveObjectResponse>> {
-  use SearchableObjects::*;
   let removed_or_deleted;
   let mut res = ResolveObjectResponse::default();
   let local_user = local_user_view.map(|l| l.local_user);
 
   match object {
-    Post(p) => {
+    SearchableObjects::PostOrComment(pc) => match *pc {
-      removed_or_deleted = p.deleted || p.removed;
+      PostOrComment::Post(p) => {
-      res.post = Some(PostView::read(pool, p.id, local_user.as_ref(), false).await?)
+        removed_or_deleted = p.deleted || p.removed;
-    }
+        res.post = Some(PostView::read(pool, p.id, local_user.as_ref(), false).await?)
-    Comment(c) => {
+      }
-      removed_or_deleted = c.deleted || c.removed;
+      PostOrComment::Comment(c) => {
-      res.comment = Some(CommentView::read(pool, c.id, local_user.as_ref()).await?)
+        removed_or_deleted = c.deleted || c.removed;
-    }
+        res.comment = Some(CommentView::read(pool, c.id, local_user.as_ref()).await?)
-    PersonOrCommunity(p) => match *p {
+      }
+    },
+    SearchableObjects::PersonOrCommunity(pc) => match *pc {
       UserOrCommunity::User(u) => {
         removed_or_deleted = u.deleted;
         res.person = Some(PersonView::read(pool, u.id).await?)

crates/apub/src/api/user_settings_backup.rs

@@ -313,7 +313,7 @@ where
 
 #[cfg(test)]
 #[expect(clippy::indexing_slicing)]
-mod tests {
+pub(crate) mod tests {
 
   use crate::api::user_settings_backup::{export_settings, import_settings};
   use activitypub_federation::config::Data;
@@ -336,7 +336,7 @@ mod tests {
   use std::time::Duration;
   use tokio::time::sleep;
 
-  async fn create_user(
+  pub(crate) async fn create_user(
     name: String,
     bio: Option<String>,
     context: &Data<LemmyContext>,

crates/apub/src/fetcher/markdown_links.rs

@@ -0,0 +1,191 @@
+use super::{search::SearchableObjects, user_or_community::UserOrCommunity};
+use crate::fetcher::post_or_comment::PostOrComment;
+use activitypub_federation::{config::Data, fetch::object_id::ObjectId};
+use lemmy_api_common::{
+  context::LemmyContext,
+  utils::{generate_local_apub_endpoint, EndpointType},
+};
+use lemmy_db_schema::{newtypes::InstanceId, source::instance::Instance};
+use lemmy_utils::{
+  error::LemmyResult,
+  utils::markdown::image_links::{markdown_find_links, markdown_handle_title},
+};
+use url::Url;
+
+pub async fn markdown_rewrite_remote_links_opt(
+  src: Option<String>,
+  context: &Data<LemmyContext>,
+) -> Option<String> {
+  match src {
+    Some(t) => Some(markdown_rewrite_remote_links(t, context).await),
+    None => None,
+  }
+}
+
+/// Goes through all remote markdown links and attempts to resolve them as Activitypub objects.
+/// If successful, the link is rewritten to a local link, so it can be viewed without leaving the
+/// local instance.
+///
+/// As it relies on ObjectId::dereference, it can only be used for incoming federated objects, not
+/// for the API.
+pub async fn markdown_rewrite_remote_links(
+  mut src: String,
+  context: &Data<LemmyContext>,
+) -> String {
+  let links_offsets = markdown_find_links(&src);
+
+  // Go through the collected links in reverse order
+  for (start, end) in links_offsets.into_iter().rev() {
+    let (url, extra) = markdown_handle_title(&src, start, end);
+
+    if let Some(local_url) = to_local_url(url, context).await {
+      let mut local_url = local_url.to_string();
+      // restore title
+      if let Some(extra) = extra {
+        local_url = format!("{local_url} {extra}");
+      }
+      src.replace_range(start..end, local_url.as_str());
+    }
+  }
+
+  src
+}
+
+pub(crate) async fn to_local_url(url: &str, context: &Data<LemmyContext>) -> Option<Url> {
+  let local_domain = &context.settings().get_protocol_and_hostname();
+  let object_id = ObjectId::<SearchableObjects>::parse(url).ok()?;
+  if object_id.inner().domain() == Some(local_domain) {
+    return None;
+  }
+  let dereferenced = object_id.dereference(context).await.ok()?;
+  match dereferenced {
+    SearchableObjects::PostOrComment(pc) => match *pc {
+      PostOrComment::Post(post) => {
+        generate_local_apub_endpoint(EndpointType::Post, &post.id.to_string(), local_domain)
+      }
+      PostOrComment::Comment(comment) => {
+        generate_local_apub_endpoint(EndpointType::Comment, &comment.id.to_string(), local_domain)
+      }
+    }
+    .ok()
+    .map(Into::into),
+    SearchableObjects::PersonOrCommunity(pc) => match *pc {
+      UserOrCommunity::User(user) => {
+        format_actor_url(&user.name, "u", user.instance_id, context).await
+      }
+      UserOrCommunity::Community(community) => {
+        format_actor_url(&community.name, "c", community.instance_id, context).await
+      }
+    }
+    .ok(),
+  }
+}
+
+async fn format_actor_url(
+  name: &str,
+  kind: &str,
+  instance_id: InstanceId,
+  context: &LemmyContext,
+) -> LemmyResult<Url> {
+  let local_protocol_and_hostname = context.settings().get_protocol_and_hostname();
+  let local_hostname = &context.settings().hostname;
+  let instance = Instance::read(&mut context.pool(), instance_id).await?;
+  let url = if &instance.domain != local_hostname {
+    format!(
+      "{local_protocol_and_hostname}/{kind}/{name}@{}",
+      instance.domain
+    )
+  } else {
+    format!("{local_protocol_and_hostname}/{kind}/{name}")
+  };
+  Ok(Url::parse(&url)?)
+}
+
+#[cfg(test)]
+mod tests {
+  use super::*;
+  use crate::api::user_settings_backup::tests::create_user;
+  use lemmy_db_schema::{
+    source::{
+      community::{Community, CommunityInsertForm},
+      post::{Post, PostInsertForm},
+    },
+    traits::Crud,
+  };
+  use pretty_assertions::assert_eq;
+  use serial_test::serial;
+
+  #[serial]
+  #[tokio::test]
+  async fn test_markdown_rewrite_remote_links() -> LemmyResult<()> {
+    let context = LemmyContext::init_test_context().await;
+    let instance = Instance::read_or_create(&mut context.pool(), "example.com".to_string()).await?;
+    let community = Community::create(
+      &mut context.pool(),
+      &CommunityInsertForm::new(
+        instance.id,
+        "my_community".to_string(),
+        "My Community".to_string(),
+        "pubkey".to_string(),
+      ),
+    )
+    .await?;
+    let user = create_user("john".to_string(), None, &context).await?;
+
+    // insert a remote post which is already fetched
+    let post_form = PostInsertForm {
+      ap_id: Some(Url::parse("https://example.com/post/123")?.into()),
+      ..PostInsertForm::new("My post".to_string(), user.person.id, community.id)
+    };
+    let post = Post::create(&mut context.pool(), &post_form).await?;
+    let markdown_local_post_url = format!("[link](https://lemmy-alpha/post/{})", post.id);
+
+    let tests: Vec<_> = vec![
+      (
+        "rewrite remote post link",
+        format!("[link]({})", post.ap_id),
+        markdown_local_post_url.as_ref(),
+      ),
+      (
+        "rewrite community link",
+        format!("[link]({})", community.actor_id),
+        "[link](https://lemmy-alpha/c/my_community@example.com)",
+      ),
+      (
+        "dont rewrite local post link",
+        "[link](https://lemmy-alpha/post/2)".to_string(),
+        "[link](https://lemmy-alpha/post/2)",
+      ),
+      (
+        "dont rewrite local community link",
+        "[link](https://lemmy-alpha/c/test)".to_string(),
+        "[link](https://lemmy-alpha/c/test)",
+      ),
+      (
+        "dont rewrite non-fediverse link",
+        "[link](https://example.com/)".to_string(),
+        "[link](https://example.com/)",
+      ),
+      (
+        "dont rewrite invalid url",
+        "[link](example-com)".to_string(),
+        "[link](example-com)",
+      ),
+    ];
+
+    let context = LemmyContext::init_test_context().await;
+    for (msg, input, expected) in &tests {
+      let result = markdown_rewrite_remote_links(input.to_string(), &context).await;
+
+      assert_eq!(
+        &result, expected,
+        "Testing {}, with original input '{}'",
+        msg, input
+      );
+    }
+
+    Instance::delete(&mut context.pool(), instance.id).await?;
+
+    Ok(())
+  }
+}

crates/apub/src/fetcher/mod.rs

@@ -10,6 +10,7 @@ use lemmy_db_schema::traits::ApubActor;
 use lemmy_db_views::structs::LocalUserView;
 use lemmy_utils::error::{LemmyError, LemmyResult};
 
+pub(crate) mod markdown_links;
 pub mod post_or_comment;
 pub mod search;
 pub mod site_or_community_or_user;

crates/apub/src/fetcher/search.rs

@@ -1,8 +1,5 @@
-use crate::{
+use super::post_or_comment::{PageOrNote, PostOrComment};
-  fetcher::user_or_community::{PersonOrGroup, UserOrCommunity},
+use crate::fetcher::user_or_community::{PersonOrGroup, UserOrCommunity};
-  objects::{comment::ApubComment, community::ApubCommunity, person::ApubPerson, post::ApubPost},
-  protocol::objects::{note::Note, page::Page},
-};
 use activitypub_federation::{
   config::Data,
   fetch::{object_id::ObjectId, webfinger::webfinger_resolve_actor},
@@ -54,16 +51,14 @@ pub(crate) async fn search_query_to_object_id_local(
 /// The types of ActivityPub objects that can be fetched directly by searching for their ID.
 #[derive(Debug)]
 pub(crate) enum SearchableObjects {
-  Post(ApubPost),
+  PostOrComment(Box<PostOrComment>),
-  Comment(ApubComment),
   PersonOrCommunity(Box<UserOrCommunity>),
 }
 
 #[derive(Deserialize)]
 #[serde(untagged)]
 pub(crate) enum SearchableKinds {
-  Page(Box<Page>),
+  PageOrNote(Box<PageOrNote>),
-  Note(Note),
   PersonOrGroup(Box<PersonOrGroup>),
 }
 
@@ -75,8 +70,7 @@ impl Object for SearchableObjects {
 
   fn last_refreshed_at(&self) -> Option<DateTime<Utc>> {
     match self {
-      SearchableObjects::Post(p) => p.last_refreshed_at(),
+      SearchableObjects::PostOrComment(p) => p.last_refreshed_at(),
-      SearchableObjects::Comment(c) => c.last_refreshed_at(),
       SearchableObjects::PersonOrCommunity(p) => p.last_refreshed_at(),
     }
   }
@@ -95,13 +89,9 @@ impl Object for SearchableObjects {
     if let Some(uc) = uc {
       return Ok(Some(SearchableObjects::PersonOrCommunity(Box::new(uc))));
     }
-    let p = ApubPost::read_from_id(object_id.clone(), context).await?;
+    let pc = PostOrComment::read_from_id(object_id.clone(), context).await?;
-    if let Some(p) = p {
+    if let Some(pc) = pc {
-      return Ok(Some(SearchableObjects::Post(p)));
+      return Ok(Some(SearchableObjects::PostOrComment(Box::new(pc))));
-    }
-    let c = ApubComment::read_from_id(object_id, context).await?;
-    if let Some(c) = c {
-      return Ok(Some(SearchableObjects::Comment(c)));
     }
     Ok(None)
   }
@@ -109,25 +99,16 @@ impl Object for SearchableObjects {
   #[tracing::instrument(skip_all)]
   async fn delete(self, data: &Data<Self::DataType>) -> LemmyResult<()> {
     match self {
-      SearchableObjects::Post(p) => p.delete(data).await,
+      SearchableObjects::PostOrComment(pc) => pc.delete(data).await,
-      SearchableObjects::Comment(c) => c.delete(data).await,
+      SearchableObjects::PersonOrCommunity(pc) => pc.delete(data).await,
-      SearchableObjects::PersonOrCommunity(pc) => match *pc {
-        UserOrCommunity::User(p) => p.delete(data).await,
-        UserOrCommunity::Community(c) => c.delete(data).await,
-      },
     }
   }
 
   async fn into_json(self, data: &Data<Self::DataType>) -> LemmyResult<Self::Kind> {
+    use SearchableObjects::*;
     Ok(match self {
-      SearchableObjects::Post(p) => SearchableKinds::Page(Box::new(p.into_json(data).await?)),
+      PostOrComment(pc) => SearchableKinds::PageOrNote(Box::new(pc.into_json(data).await?)),
-      SearchableObjects::Comment(c) => SearchableKinds::Note(c.into_json(data).await?),
+      PersonOrCommunity(pc) => SearchableKinds::PersonOrGroup(Box::new(pc.into_json(data).await?)),
-      SearchableObjects::PersonOrCommunity(pc) => {
-        SearchableKinds::PersonOrGroup(Box::new(match *pc {
-          UserOrCommunity::User(p) => PersonOrGroup::Person(p.into_json(data).await?),
-          UserOrCommunity::Community(c) => PersonOrGroup::Group(c.into_json(data).await?),
-        }))
-      }
     })
   }
 
@@ -137,24 +118,20 @@ impl Object for SearchableObjects {
     expected_domain: &Url,
     data: &Data<Self::DataType>,
   ) -> LemmyResult<()> {
+    use SearchableKinds::*;
     match apub {
-      SearchableKinds::Page(a) => ApubPost::verify(a, expected_domain, data).await,
+      PageOrNote(pn) => PostOrComment::verify(pn, expected_domain, data).await,
-      SearchableKinds::Note(a) => ApubComment::verify(a, expected_domain, data).await,
+      PersonOrGroup(pg) => UserOrCommunity::verify(pg, expected_domain, data).await,
-      SearchableKinds::PersonOrGroup(pg) => match pg.as_ref() {
-        PersonOrGroup::Person(a) => ApubPerson::verify(a, expected_domain, data).await,
-        PersonOrGroup::Group(a) => ApubCommunity::verify(a, expected_domain, data).await,
-      },
     }
   }
 
   #[tracing::instrument(skip_all)]
   async fn from_json(apub: Self::Kind, context: &Data<LemmyContext>) -> LemmyResult<Self> {
-    use SearchableKinds as SAT;
+    use SearchableKinds::*;
     use SearchableObjects as SO;
     Ok(match apub {
-      SAT::Page(p) => SO::Post(ApubPost::from_json(*p, context).await?),
+      PageOrNote(pg) => SO::PostOrComment(Box::new(PostOrComment::from_json(*pg, context).await?)),
-      SAT::Note(n) => SO::Comment(ApubComment::from_json(n, context).await?),
+      PersonOrGroup(pg) => {
-      SAT::PersonOrGroup(pg) => {
         SO::PersonOrCommunity(Box::new(UserOrCommunity::from_json(*pg, context).await?))
       }
     })

crates/apub/src/objects/comment.rs

@@ -1,6 +1,7 @@
 use crate::{
   activities::{verify_is_public, verify_person_in_community},
   check_apub_id_valid_with_strictness,
+  fetcher::markdown_links::markdown_rewrite_remote_links,
   mentions::collect_non_local_mentions,
   objects::{read_from_string_or_source, verify_is_remote_object},
   protocol::{
@@ -181,6 +182,7 @@ impl Object for ApubComment {
     let slur_regex = &local_site_opt_to_slur_regex(&local_site);
     let url_blocklist = get_url_blocklist(context).await?;
     let content = process_markdown(&content, slur_regex, &url_blocklist, context).await?;
+    let content = markdown_rewrite_remote_links(content, context).await;
     let language_id = Some(
       LanguageTag::to_language_id_single(note.language.unwrap_or_default(), &mut context.pool())
         .await?,
@@ -298,7 +300,7 @@ pub(crate) mod tests {
     let comment = ApubComment::from_json(json, &context).await?;
 
     assert_eq!(comment.ap_id, pleroma_url.into());
-    assert_eq!(comment.content.len(), 64);
+    assert_eq!(comment.content.len(), 10);
     assert!(!comment.local);
     assert_eq!(context.request_count(), 1);
 

crates/apub/src/objects/community.rs

@@ -1,6 +1,7 @@
 use crate::{
   activities::GetActorType,
   check_apub_id_valid,
+  fetcher::markdown_links::markdown_rewrite_remote_links_opt,
   local_site_data_cached,
   objects::{instance::fetch_instance_actor_for_object, read_from_string_or_source_opt},
   protocol::{
@@ -148,6 +149,7 @@ impl Object for ApubCommunity {
     let description = read_from_string_or_source_opt(&group.summary, &None, &group.source);
     let description =
       process_markdown_opt(&description, slur_regex, &url_blocklist, context).await?;
+    let description = markdown_rewrite_remote_links_opt(description, context).await;
     let icon = proxy_image_link_opt_apub(group.icon.map(|i| i.url), context).await?;
     let banner = proxy_image_link_opt_apub(group.image.map(|i| i.url), context).await?;
 
@@ -296,7 +298,7 @@ pub(crate) mod tests {
     assert!(!community.local);
     assert_eq!(
       community.description.as_ref().map(std::string::String::len),
-      Some(132)
+      Some(63)
     );
 
     Community::delete(&mut context.pool(), community.id).await?;

crates/apub/src/objects/instance.rs

@@ -2,6 +2,7 @@ use super::verify_is_remote_object;
 use crate::{
   activities::GetActorType,
   check_apub_id_valid_with_strictness,
+  fetcher::markdown_links::markdown_rewrite_remote_links_opt,
   local_site_data_cached,
   objects::read_from_string_or_source_opt,
   protocol::{
@@ -151,6 +152,7 @@ impl Object for ApubSite {
     let url_blocklist = get_url_blocklist(context).await?;
     let sidebar = read_from_string_or_source_opt(&apub.content, &None, &apub.source);
     let sidebar = process_markdown_opt(&sidebar, slur_regex, &url_blocklist, context).await?;
+    let sidebar = markdown_rewrite_remote_links_opt(sidebar, context).await;
     let icon = proxy_image_link_opt_apub(apub.icon.map(|i| i.url), context).await?;
     let banner = proxy_image_link_opt_apub(apub.image.map(|i| i.url), context).await?;
 

crates/apub/src/objects/person.rs

@@ -2,6 +2,7 @@ use super::verify_is_remote_object;
 use crate::{
   activities::GetActorType,
   check_apub_id_valid_with_strictness,
+  fetcher::markdown_links::markdown_rewrite_remote_links_opt,
   local_site_data_cached,
   objects::{instance::fetch_instance_actor_for_object, read_from_string_or_source_opt},
   protocol::{
@@ -156,6 +157,7 @@ impl Object for ApubPerson {
     let url_blocklist = get_url_blocklist(context).await?;
     let bio = read_from_string_or_source_opt(&person.summary, &None, &person.source);
     let bio = process_markdown_opt(&bio, slur_regex, &url_blocklist, context).await?;
+    let bio = markdown_rewrite_remote_links_opt(bio, context).await;
     let avatar = proxy_image_link_opt_apub(person.icon.map(|i| i.url), context).await?;
     let banner = proxy_image_link_opt_apub(person.image.map(|i| i.url), context).await?;
 
@@ -277,7 +279,7 @@ pub(crate) mod tests {
     assert_eq!(person.name, "lanodan");
     assert!(!person.local);
     assert_eq!(context.request_count(), 0);
-    assert_eq!(person.bio.as_ref().map(std::string::String::len), Some(873));
+    assert_eq!(person.bio.as_ref().map(std::string::String::len), Some(812));
 
     cleanup((person, site), &context).await?;
     Ok(())

crates/apub/src/objects/post.rs

@@ -1,6 +1,7 @@
 use crate::{
   activities::{verify_is_public, verify_person_in_community},
   check_apub_id_valid_with_strictness,
+  fetcher::markdown_links::{markdown_rewrite_remote_links_opt, to_local_url},
   local_site_data_cached,
   objects::{read_from_string_or_source_opt, verify_is_remote_object},
   protocol::{
@@ -226,10 +227,13 @@ impl Object for ApubPost {
 
     let url_blocklist = get_url_blocklist(context).await?;
 
-    if let Some(url) = &url {
+    let url = if let Some(url) = url {
-      is_url_blocked(url, &url_blocklist)?;
+      is_url_blocked(&url, &url_blocklist)?;
-      is_valid_url(url)?;
+      is_valid_url(&url)?;
-    }
+      to_local_url(url.as_str(), context).await.or(Some(url))
+    } else {
+      None
+    };
 
     let alt_text = first_attachment.cloned().and_then(Attachment::alt_text);
 
@@ -237,6 +241,7 @@ impl Object for ApubPost {
 
     let body = read_from_string_or_source_opt(&page.content, &page.media_type, &page.source);
     let body = process_markdown_opt(&body, slur_regex, &url_blocklist, context).await?;
+    let body = markdown_rewrite_remote_links_opt(body, context).await;
     let language_id = Some(
       LanguageTag::to_language_id_single(page.language.unwrap_or_default(), &mut context.pool())
         .await?,
@@ -303,7 +308,7 @@ mod tests {
     assert_eq!(post.body.as_ref().map(std::string::String::len), Some(45));
     assert!(!post.locked);
     assert!(!post.featured_community);
-    assert_eq!(context.request_count(), 0);
+    assert_eq!(context.request_count(), 1);
 
     Post::delete(&mut context.pool(), post.id).await?;
     Person::delete(&mut context.pool(), person.id).await?;

crates/apub/src/objects/private_message.rs

@@ -1,6 +1,7 @@
 use super::verify_is_remote_object;
 use crate::{
   check_apub_id_valid_with_strictness,
+  fetcher::markdown_links::markdown_rewrite_remote_links,
   objects::read_from_string_or_source,
   protocol::{
     objects::chat_message::{ChatMessage, ChatMessageType},
@@ -134,6 +135,7 @@ impl Object for ApubPrivateMessage {
     let url_blocklist = get_url_blocklist(context).await?;
     let content = read_from_string_or_source(&note.content, &None, &note.source);
     let content = process_markdown(&content, slur_regex, &url_blocklist, context).await?;
+    let content = markdown_rewrite_remote_links(content, context).await;
 
     let form = PrivateMessageInsertForm {
       creator_id: creator.id,

crates/db_schema/src/impls/instance.rs

@@ -67,6 +67,11 @@ impl Instance {
       }
     }
   }
+  pub async fn read(pool: &mut DbPool<'_>, instance_id: InstanceId) -> Result<Self, Error> {
+    let conn = &mut get_conn(pool).await?;
+    instance::table.find(instance_id).first(conn).await
+  }
+
   pub async fn update(
     pool: &mut DbPool<'_>,
     instance_id: InstanceId,

crates/utils/src/utils/markdown/image_links.rs

@@ -0,0 +1,168 @@
+use super::{link_rule::Link, MARKDOWN_PARSER};
+use crate::settings::SETTINGS;
+use markdown_it::{plugins::cmark::inline::image::Image, NodeValue};
+use url::Url;
+use urlencoding::encode;
+
+/// Rewrites all links to remote domains in markdown, so they go through `/api/v3/image_proxy`.
+pub fn markdown_rewrite_image_links(mut src: String) -> (String, Vec<Url>) {
+  let links_offsets = find_urls::<Image>(&src);
+
+  let mut links = vec![];
+  // Go through the collected links in reverse order
+  for (start, end) in links_offsets.into_iter().rev() {
+    let (url, extra) = markdown_handle_title(&src, start, end);
+    match Url::parse(url) {
+      Ok(parsed) => {
+        links.push(parsed.clone());
+        // If link points to remote domain, replace with proxied link
+        if parsed.domain() != Some(&SETTINGS.hostname) {
+          let mut proxied = format!(
+            "{}/api/v3/image_proxy?url={}",
+            SETTINGS.get_protocol_and_hostname(),
+            encode(url),
+          );
+          // restore custom emoji format
+          if let Some(extra) = extra {
+            proxied = format!("{proxied} {extra}");
+          }
+          src.replace_range(start..end, &proxied);
+        }
+      }
+      Err(_) => {
+        // If its not a valid url, replace with empty text
+        src.replace_range(start..end, "");
+      }
+    }
+  }
+
+  (src, links)
+}
+
+pub fn markdown_handle_title(src: &str, start: usize, end: usize) -> (&str, Option<&str>) {
+  let content = src.get(start..end).unwrap_or_default();
+  // necessary for custom emojis which look like `![name](url "title")`
+  let (url, extra) = if content.contains(' ') {
+    let split = content.split_once(' ').expect("split is valid");
+    (split.0, Some(split.1))
+  } else {
+    (content, None)
+  };
+  (url, extra)
+}
+
+pub fn markdown_find_links(src: &str) -> Vec<(usize, usize)> {
+  find_urls::<Link>(src)
+}
+
+// Walk the syntax tree to find positions of image or link urls
+fn find_urls<T: NodeValue + UrlAndTitle>(src: &str) -> Vec<(usize, usize)> {
+  let ast = MARKDOWN_PARSER.parse(src);
+  let mut links_offsets = vec![];
+  ast.walk(|node, _depth| {
+    if let Some(image) = node.cast::<T>() {
+      let node_offsets = node.srcmap.expect("srcmap is none").get_byte_offsets();
+      let start_offset = node_offsets.1 - image.url_len() - 1 - image.title_len();
+      let end_offset = node_offsets.1 - 1;
+
+      links_offsets.push((start_offset, end_offset));
+    }
+  });
+  links_offsets
+}
+
+pub trait UrlAndTitle {
+  fn url_len(&self) -> usize;
+  fn title_len(&self) -> usize;
+}
+
+impl UrlAndTitle for Image {
+  fn url_len(&self) -> usize {
+    self.url.len()
+  }
+
+  fn title_len(&self) -> usize {
+    self.title.as_ref().map(|t| t.len() + 3).unwrap_or_default()
+  }
+}
+impl UrlAndTitle for Link {
+  fn url_len(&self) -> usize {
+    self.url.len()
+  }
+  fn title_len(&self) -> usize {
+    self.title.as_ref().map(|t| t.len() + 3).unwrap_or_default()
+  }
+}
+
+#[cfg(test)]
+mod tests {
+
+  use super::*;
+  use pretty_assertions::assert_eq;
+
+  #[test]
+  fn test_find_links() {
+    let links = markdown_find_links("[test](https://example.com)");
+    assert_eq!(vec![(7, 26)], links);
+
+    let links = find_urls::<Image>("![test](https://example.com)");
+    assert_eq!(vec![(8, 27)], links);
+  }
+
+  #[test]
+  fn test_markdown_proxy_images() {
+    let tests: Vec<_> =
+      vec![
+        (
+          "remote image proxied",
+          "![link](http://example.com/image.jpg)",
+          "![link](https://lemmy-alpha/api/v3/image_proxy?url=http%3A%2F%2Fexample.com%2Fimage.jpg)",
+        ),
+        (
+          "local image unproxied",
+          "![link](http://lemmy-alpha/image.jpg)",
+          "![link](http://lemmy-alpha/image.jpg)",
+        ),
+        (
+          "multiple image links",
+          "![link](http://example.com/image1.jpg) ![link](http://example.com/image2.jpg)",
+          "![link](https://lemmy-alpha/api/v3/image_proxy?url=http%3A%2F%2Fexample.com%2Fimage1.jpg) ![link](https://lemmy-alpha/api/v3/image_proxy?url=http%3A%2F%2Fexample.com%2Fimage2.jpg)",
+        ),
+        (
+          "empty link handled",
+          "![image]()",
+          "![image]()"
+        ),
+        (
+          "empty label handled",
+          "![](http://example.com/image.jpg)",
+          "![](https://lemmy-alpha/api/v3/image_proxy?url=http%3A%2F%2Fexample.com%2Fimage.jpg)"
+        ),
+        (
+          "invalid image link removed",
+          "![image](http-not-a-link)",
+          "![image]()"
+        ),
+        (
+          "label with nested markdown handled",
+          "![a *b* c](http://example.com/image.jpg)",
+          "![a *b* c](https://lemmy-alpha/api/v3/image_proxy?url=http%3A%2F%2Fexample.com%2Fimage.jpg)"
+        ),
+        (
+          "custom emoji support",
+          r#"![party-blob](https://www.hexbear.net/pictrs/image/83405746-0620-4728-9358-5f51b040ffee.gif "emoji party-blob")"#,
+          r#"![party-blob](https://lemmy-alpha/api/v3/image_proxy?url=https%3A%2F%2Fwww.hexbear.net%2Fpictrs%2Fimage%2F83405746-0620-4728-9358-5f51b040ffee.gif "emoji party-blob")"#
+        )
+      ];
+
+    tests.iter().for_each(|&(msg, input, expected)| {
+      let result = markdown_rewrite_image_links(input.to_string());
+
+      assert_eq!(
+        result.0, expected,
+        "Testing {}, with original input '{}'",
+        msg, input
+      );
+    });
+  }
+}

crates/utils/src/utils/markdown/mod.rs

@@ -1,10 +1,9 @@
-use crate::{error::LemmyResult, settings::SETTINGS, LemmyErrorType};
+use crate::{error::LemmyResult, LemmyErrorType};
-use markdown_it::{plugins::cmark::inline::image::Image, MarkdownIt};
+use markdown_it::MarkdownIt;
 use regex::RegexSet;
 use std::sync::LazyLock;
-use url::Url;
-use urlencoding::encode;
 
+pub mod image_links;
 mod link_rule;
 mod spoiler_rule;
 
@@ -35,70 +34,6 @@ pub fn markdown_to_html(text: &str) -> String {
   MARKDOWN_PARSER.parse(text).xrender()
 }
 
-/// Rewrites all links to remote domains in markdown, so they go through `/api/v3/image_proxy`.
-pub fn markdown_rewrite_image_links(mut src: String) -> (String, Vec<Url>) {
-  let ast = MARKDOWN_PARSER.parse(&src);
-  let mut links_offsets = vec![];
-
-  // Walk the syntax tree to find positions of image links
-  ast.walk(|node, _depth| {
-    if let Some(image) = node.cast::<Image>() {
-      // srcmap is always present for image
-      // https://github.com/markdown-it-rust/markdown-it/issues/36#issuecomment-1777844387
-      let node_offsets = node.srcmap.expect("srcmap is none").get_byte_offsets();
-      // necessary for custom emojis which look like `![name](url "title")`
-      let start_offset = node_offsets.1
-        - image.url.len()
-        - 1
-        - image
-          .title
-          .as_ref()
-          .map(|t| t.len() + 3)
-          .unwrap_or_default();
-      let end_offset = node_offsets.1 - 1;
-
-      links_offsets.push((start_offset, end_offset));
-    }
-  });
-
-  let mut links = vec![];
-  // Go through the collected links in reverse order
-  while let Some((start, end)) = links_offsets.pop() {
-    let content = src.get(start..end).unwrap_or_default();
-    // necessary for custom emojis which look like `![name](url "title")`
-    let (url, extra) = if content.contains(' ') {
-      let split = content.split_once(' ').expect("split is valid");
-      (split.0, Some(split.1))
-    } else {
-      (content, None)
-    };
-    match Url::parse(url) {
-      Ok(parsed) => {
-        links.push(parsed.clone());
-        // If link points to remote domain, replace with proxied link
-        if parsed.domain() != Some(&SETTINGS.hostname) {
-          let mut proxied = format!(
-            "{}/api/v3/image_proxy?url={}",
-            SETTINGS.get_protocol_and_hostname(),
-            encode(url),
-          );
-          // restore custom emoji format
-          if let Some(extra) = extra {
-            proxied = format!("{proxied} {extra}");
-          }
-          src.replace_range(start..end, &proxied);
-        }
-      }
-      Err(_) => {
-        // If its not a valid url, replace with empty text
-        src.replace_range(start..end, "");
-      }
-    }
-  }
-
-  (src, links)
-}
-
 pub fn markdown_check_for_blocked_urls(text: &str, blocklist: &RegexSet) -> LemmyResult<()> {
   if blocklist.is_match(text) {
     Err(LemmyErrorType::BlockedUrl)?
@@ -110,6 +45,7 @@ pub fn markdown_check_for_blocked_urls(text: &str, blocklist: &RegexSet) -> Lemm
 mod tests {
 
   use super::*;
+  use image_links::markdown_rewrite_image_links;
   use pretty_assertions::assert_eq;
 
   #[test]