Append attachment URL to post content if attachment is too large

CHANGELOG.md

@@ -9,6 +9,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 ### Added
 
 - Replace post attachments and other related objects when processing `Update(Note)` activity.
+- Append attachment URL to post content if attachment size exceeds limit.
 
 ### Changed
 

src/activitypub/fetcher/fetchers.rs

@@ -38,6 +38,9 @@ pub enum FetchError {
     #[error(transparent)]
     FileError(#[from] std::io::Error),
 
+    #[error("file size exceeds limit")]
+    FileTooLarge,
+
     #[error("too many objects")]
     RecursionError,
 
@@ -122,13 +125,13 @@ pub async fn fetch_file(
         let file_size: usize = file_size.try_into()
             .expect("value should be within bounds");
         if file_size > file_max_size {
-            return Err(FetchError::OtherError("file is too large"));
+            return Err(FetchError::FileTooLarge);
         };
     };
     let file_data = response.bytes().await?;
     let file_size = file_data.len();
     if file_size > file_max_size {
-        return Err(FetchError::OtherError("file is too large"));
+        return Err(FetchError::FileTooLarge);
     };
     let maybe_media_type = maybe_media_type
         .map(|media_type| media_type.to_string())

src/activitypub/handlers/create.rs

@@ -6,7 +6,7 @@ use uuid::Uuid;
 
 use crate::activitypub::{
     constants::{AP_MEDIA_TYPE, AP_PUBLIC, AS_MEDIA_TYPE},
-    fetcher::fetchers::fetch_file,
+    fetcher::fetchers::{fetch_file, FetchError},
     fetcher::helpers::{
         get_or_import_profile_by_actor_address,
         get_or_import_profile_by_actor_id,
@@ -129,10 +129,11 @@ pub async fn get_object_attachments(
     db_client: &impl DatabaseClient,
     object: &Object,
     author: &DbActorProfile,
-) -> Result<Vec<Uuid>, HandlerError> {
+) -> Result<(Vec<Uuid>, Vec<String>), HandlerError> {
     let instance = config.instance();
     let media_dir = config.media_dir();
     let mut attachments = vec![];
+    let mut unprocessed = vec![];
     if let Some(ref value) = object.attachment {
         let list: Vec<Attachment> = parse_property_value(value)
             .map_err(|_| ValidationError("invalid attachment property"))?;
@@ -157,17 +158,24 @@ pub async fn get_object_attachments(
             };
             let attachment_url = attachment.url
                 .ok_or(ValidationError("attachment URL is missing"))?;
-            let (file_name, file_size, maybe_media_type) = fetch_file(
+            let (file_name, file_size, maybe_media_type) = match fetch_file(
                 &instance,
                 &attachment_url,
                 attachment.media_type.as_deref(),
                 ATTACHMENT_MAX_SIZE,
                 &media_dir,
-            ).await
-                .map_err(|err| {
-                    log::warn!("{}", err);
-                    ValidationError("failed to fetch attachment")
-                })?;
+            ).await {
+                Ok(file) => file,
+                Err(FetchError::FileTooLarge) => {
+                    log::warn!("attachment is too large: {}", attachment_url);
+                    unprocessed.push(attachment_url);
+                    continue;
+                },
+                Err(other_error) => {
+                    log::warn!("{}", other_error);
+                    return Err(ValidationError("failed to fetch attachment").into());
+                },
+            };
             log::info!("downloaded attachment {}", attachment_url);
             downloaded.push((file_name, file_size, maybe_media_type));
             // Stop downloading if limit is reached
@@ -187,7 +195,7 @@ pub async fn get_object_attachments(
             attachments.push(db_attachment.id);
         };
     };
-    Ok(attachments)
+    Ok((attachments, unprocessed))
 }
 
 pub async fn get_object_tags(
@@ -498,12 +506,15 @@ pub async fn handle_note(
         let object_url = get_object_url(&object)?;
         content += &create_content_link(object_url);
     };
-    let attachments = get_object_attachments(
+    let (attachments, unprocessed) = get_object_attachments(
         config,
         db_client,
         &object,
         &author,
     ).await?;
+    for attachment_url in unprocessed {
+        content += &create_content_link(attachment_url);
+    };
     if content.is_empty() && attachments.is_empty() {
         return Err(ValidationError("post is empty").into());
     };

src/activitypub/handlers/update.rs

@@ -54,12 +54,15 @@ async fn handle_update_note(
         let object_url = get_object_url(&object)?;
         content += &create_content_link(object_url);
     };
-    let attachments = get_object_attachments(
+    let (attachments, unprocessed) = get_object_attachments(
         config,
         db_client,
         &object,
         &post.author,
     ).await?;
+    for attachment_url in unprocessed {
+        content += &create_content_link(attachment_url);
+    };
     if content.is_empty() && attachments.is_empty() {
         return Err(ValidationError("post is empty").into());
     };