Better JSON error messages (#91)

src/activity_sending.rs

@@ -56,14 +56,16 @@ impl SendActivityTask<'_> {
         data: &Data<Datatype>,
     ) -> Result<Vec<SendActivityTask<'a>>, Error>
     where
-        Activity: ActivityHandler + Serialize,
+        Activity: ActivityHandler + Serialize + Debug,
         Datatype: Clone,
         ActorType: Actor,
     {
         let config = &data.config;
         let actor_id = activity.actor();
         let activity_id = activity.id();
-        let activity_serialized: Bytes = serde_json::to_vec(&activity).map_err(Error::Json)?.into();
+        let activity_serialized: Bytes = serde_json::to_vec(&activity)
+            .map_err(|e| Error::SerializeOutgoingActivity(e, format!("{:?}", activity)))?
+            .into();
         let private_key = get_pkey_cached(data, actor).await?;
 
         Ok(futures::stream::iter(

src/actix_web/inbox.rs

@@ -130,8 +130,8 @@ mod test {
         .await;
 
         match res {
-            Err(Error::ParseReceivedActivity(url, _)) => {
-                assert_eq!(id, url.as_str());
+            Err(Error::ParseReceivedActivity(_, url)) => {
+                assert_eq!(id, url.expect("has url").as_str());
             }
             _ => unreachable!(),
         }

src/error.rs

@@ -35,12 +35,18 @@ pub enum Error {
     /// Failed to resolve actor via webfinger
     #[error("Failed to resolve actor via webfinger")]
     WebfingerResolveFailed(#[from] WebFingerError),
-    /// JSON Error
-    #[error(transparent)]
-    Json(#[from] serde_json::Error),
+    /// Failed to serialize outgoing activity
+    #[error("Failed to serialize outgoing activity {1}: {0}")]
+    SerializeOutgoingActivity(serde_json::Error, String),
+    /// Failed to parse an object fetched from url
+    #[error("Failed to parse object {1} with content {2}: {0}")]
+    ParseFetchedObject(serde_json::Error, Url, String),
     /// Failed to parse an activity received from another instance
-    #[error("Failed to parse incoming activity with id {0}: {1}")]
-    ParseReceivedActivity(Url, serde_json::Error),
+    #[error("Failed to parse incoming activity {}: {0}", match .1 {
+        Some(t) => format!("with id {t}"),
+        None => String::new(),
+    })]
+    ParseReceivedActivity(serde_json::Error, Option<Url>),
     /// Reqwest Middleware Error
     #[error(transparent)]
     ReqwestMiddleware(#[from] reqwest_middleware::Error),

src/fetch/mod.rs

@@ -4,7 +4,7 @@
 
 use crate::{
     config::Data,
-    error::Error,
+    error::{Error, Error::ParseFetchedObject},
     http_signatures::sign_request,
     reqwest_shim::ResponseExt,
     FEDERATION_CONTENT_TYPE,
@@ -93,8 +93,13 @@ async fn fetch_object_http_with_accept<T: Clone, Kind: DeserializeOwned>(
     }
 
     let url = res.url().clone();
-    Ok(FetchObjectResponse {
-        object: res.json_limited().await?,
-        url,
-    })
+    let text = res.bytes_limited().await?;
+    match serde_json::from_slice(&text) {
+        Ok(object) => Ok(FetchObjectResponse { object, url }),
+        Err(e) => Err(ParseFetchedObject(
+            e,
+            url,
+            String::from_utf8(Vec::from(text))?,
+        )),
+    }
 }

src/lib.rs

@@ -57,10 +57,8 @@ where
         struct Id {
             id: Url,
         }
-        match serde_json::from_slice::<Id>(body) {
-            Ok(id) => Error::ParseReceivedActivity(id.id, e),
-            Err(e) => Error::Json(e),
-        }
+        let id = serde_json::from_slice::<Id>(body).ok();
+        Error::ParseReceivedActivity(e, id.map(|i| i.id))
     })?;
     data.config.verify_url_and_domain(&activity).await?;
     let actor = ObjectId::<ActorT>::from(activity.actor().clone())

src/reqwest_shim.rs

@@ -3,10 +3,8 @@ use bytes::{BufMut, Bytes, BytesMut};
 use futures_core::{ready, stream::BoxStream, Stream};
 use pin_project_lite::pin_project;
 use reqwest::Response;
-use serde::de::DeserializeOwned;
 use std::{
     future::Future,
-    marker::PhantomData,
     mem,
     pin::Pin,
     task::{Context, Poll},
@@ -46,27 +44,6 @@ impl Future for BytesFuture {
     }
 }
 
-pin_project! {
-    pub struct JsonFuture<T> {
-        _t: PhantomData<T>,
-        #[pin]
-        future: BytesFuture,
-    }
-}
-
-impl<T> Future for JsonFuture<T>
-where
-    T: DeserializeOwned,
-{
-    type Output = Result<T, Error>;
-
-    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
-        let this = self.project();
-        let bytes = ready!(this.future.poll(cx))?;
-        Poll::Ready(serde_json::from_slice(&bytes).map_err(Error::Json))
-    }
-}
-
 pin_project! {
     pub struct TextFuture {
         #[pin]
@@ -94,20 +71,16 @@ impl Future for TextFuture {
 /// TODO: Remove this shim as soon as reqwest gets support for size-limited bodies.
 pub trait ResponseExt {
     type BytesFuture;
-    type JsonFuture<T>;
     type TextFuture;
 
     /// Size limited version of `bytes` to work around a reqwest issue. Check [`ResponseExt`] docs for details.
     fn bytes_limited(self) -> Self::BytesFuture;
-    /// Size limited version of `json` to work around a reqwest issue. Check [`ResponseExt`] docs for details.
-    fn json_limited<T>(self) -> Self::JsonFuture<T>;
     /// Size limited version of `text` to work around a reqwest issue. Check [`ResponseExt`] docs for details.
     fn text_limited(self) -> Self::TextFuture;
 }
 
 impl ResponseExt for Response {
     type BytesFuture = BytesFuture;
-    type JsonFuture<T> = JsonFuture<T>;
     type TextFuture = TextFuture;
 
     fn bytes_limited(self) -> Self::BytesFuture {
@@ -118,13 +91,6 @@ impl ResponseExt for Response {
         }
     }
 
-    fn json_limited<T>(self) -> Self::JsonFuture<T> {
-        JsonFuture {
-            _t: PhantomData,
-            future: self.bytes_limited(),
-        }
-    }
-
     fn text_limited(self) -> Self::TextFuture {
         TextFuture {
             future: self.bytes_limited(),