From 32c4d3224c1bc80e2a684bf1301bf4b1a2985d28 Mon Sep 17 00:00:00 2001
From: Felix Ableitner <me@nutomic.com>
Date: Wed, 2 Dec 2020 16:55:53 +0100
Subject: [PATCH] Check for community ban when parsing post/comment (fixes
 #1287)

---
 lemmy_apub/src/inbox/community_inbox.rs |  2 +-
 lemmy_apub/src/objects/comment.rs       |  3 +++
 lemmy_apub/src/objects/mod.rs           | 29 ++++++++++++++++++++++++-
 lemmy_apub/src/objects/post.rs          |  2 ++
 4 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/lemmy_apub/src/inbox/community_inbox.rs b/lemmy_apub/src/inbox/community_inbox.rs
index 6acdfa0d8..ad6eaffbf 100644
--- a/lemmy_apub/src/inbox/community_inbox.rs
+++ b/lemmy_apub/src/inbox/community_inbox.rs
@@ -259,7 +259,7 @@ async fn handle_undo_follow(
   Ok(())
 }
 
-async fn check_community_or_site_ban(
+pub(crate) async fn check_community_or_site_ban(
   user: &User_,
   community: &Community,
   pool: &DbPool,
diff --git a/lemmy_apub/src/objects/comment.rs b/lemmy_apub/src/objects/comment.rs
index 6d2933949..9ff63cbd2 100644
--- a/lemmy_apub/src/objects/comment.rs
+++ b/lemmy_apub/src/objects/comment.rs
@@ -7,6 +7,7 @@ use crate::{
   },
   objects::{
     check_object_domain,
+    check_object_for_community_or_site_ban,
     create_tombstone,
     get_object_from_apub,
     get_source_markdown_value,
@@ -101,6 +102,8 @@ impl FromApub for Comment {
     expected_domain: Option<Url>,
     request_counter: &mut i32,
   ) -> Result<Comment, LemmyError> {
+    check_object_for_community_or_site_ban(note, context, request_counter).await?;
+
     let comment: Comment =
       get_object_from_apub(note, context, expected_domain, request_counter).await?;
 
diff --git a/lemmy_apub/src/objects/mod.rs b/lemmy_apub/src/objects/mod.rs
index 6a0175051..f7db59c70 100644
--- a/lemmy_apub/src/objects/mod.rs
+++ b/lemmy_apub/src/objects/mod.rs
@@ -1,4 +1,8 @@
-use crate::check_is_apub_id_valid;
+use crate::{
+  check_is_apub_id_valid,
+  fetcher::{get_or_fetch_and_upsert_community, get_or_fetch_and_upsert_user},
+  inbox::community_inbox::check_community_or_site_ban,
+};
 use activitystreams::{
   base::{AsBase, BaseExt, ExtendsExt},
   markers::Base,
@@ -205,3 +209,26 @@ where
     Ok(to)
   }
 }
+
+pub(in crate::objects) async fn check_object_for_community_or_site_ban<T, Kind>(
+  object: &T,
+  context: &LemmyContext,
+  request_counter: &mut i32,
+) -> Result<(), LemmyError>
+where
+  T: ObjectExt<Kind>,
+{
+  let user_id = object
+    .attributed_to()
+    .context(location_info!())?
+    .as_single_xsd_any_uri()
+    .context(location_info!())?;
+  let user = get_or_fetch_and_upsert_user(user_id, context, request_counter).await?;
+  let community_id = object
+    .to()
+    .context(location_info!())?
+    .as_single_xsd_any_uri()
+    .context(location_info!())?;
+  let community = get_or_fetch_and_upsert_community(community_id, context, request_counter).await?;
+  check_community_or_site_ban(&user, &community, context.pool()).await
+}
diff --git a/lemmy_apub/src/objects/post.rs b/lemmy_apub/src/objects/post.rs
index 9c68c1c90..3ca8650da 100644
--- a/lemmy_apub/src/objects/post.rs
+++ b/lemmy_apub/src/objects/post.rs
@@ -3,6 +3,7 @@ use crate::{
   fetcher::{get_or_fetch_and_upsert_community, get_or_fetch_and_upsert_user},
   objects::{
     check_object_domain,
+    check_object_for_community_or_site_ban,
     create_tombstone,
     get_object_from_apub,
     get_source_markdown_value,
@@ -112,6 +113,7 @@ impl FromApub for Post {
     expected_domain: Option<Url>,
     request_counter: &mut i32,
   ) -> Result<Post, LemmyError> {
+    check_object_for_community_or_site_ban(page, context, request_counter).await?;
     get_object_from_apub(page, context, expected_domain, request_counter).await
   }
 }