Improve error handling in server::api

Cargo.lock

@@ -1547,6 +1547,7 @@ dependencies = [
 name = "server"
 version = "0.0.0"
 dependencies = [
+ "derive_more",
  "http",
  "http-body-util",
  "hyper",

bin/server/Cargo.toml

@@ -10,3 +10,4 @@ http-body-util = "*"
 hyper-util = { version = "*", features = ["full"] }
 serde_json = "*"
 http = "*"
+derive_more = "*"

bin/server/src/api.rs

@@ -18,164 +18,20 @@ use crate::sig::{Signer, Verdict, Verifier, VERIFIER_MOUNT};
 
 use self::error::Message;
 
-pub mod ap {
-    //! ActivityPub handlers.
-
-    use http_body_util::Full;
-    use hyper::body::Bytes;
-    use puppy::{
-        actor::Actor,
-        data::{Id, PrivateKey, PublicKey},
-        fetch::signatures::{Private, SigningKey},
-        get_local_ap_object, Context, Key,
-    };
-    use serde_json::{to_string, Value};
-
-    use crate::sig::{Signer, Verifier};
-    use super::{
-        error::{self, Message},
-        respond, Response,
-    };
-
-    /// Proxy a request through the instance.
-    pub async fn proxy(cx: &Context, params: &[(&str, &str)]) -> Response {
-        // Extract our query parameters.
-        let Some(user) = params.iter().find_map(|(k, v)| (*k == "user").then_some(v)) else {
-            return respond(400, Some("Expected `user` query param"), []);
-        };
-        let Some(url) = params.iter().find_map(|(k, v)| (*k == "url").then_some(v)) else {
-            return respond(400, Some("Expected `url` query param"), []);
-        };
-
-        // Look up the actor's key in the store (which is accessible through the puppy context).
-        let Ok(signing_key) = cx.run(|tx| {
-            let actor = Actor::by_username(&tx, user)?.unwrap();
-            let (PrivateKey { key_pem, .. }, PublicKey { key_id, .. }) =
-                tx.get_mixin_many(actor.key)?;
-            let Id(owner) = tx.get_alias(actor.key)?.unwrap();
-            let inner = Private::decode_pem(&key_pem);
-            Ok(SigningKey { id: key_id, owner, inner })
-        }) else {
-            panic!("failed to get signing key");
-        };
-
-        eprintln!("proxy: params: {params:?}");
-        // Proxy the request through our fetcher.
-        let resp = puppy::fetch::forward(&signing_key, url).await.unwrap();
-        eprintln!("proxy: status = {}", resp.status());
-
-        // Convert the http-types request to a hyper request.
-        resp.map(Bytes::from).map(Full::new).into()
-    }
-
-    /// Handle POSTs to actor inboxes. Requires request signature.
-    pub fn inbox(cx: &Context, actor_id: &str, sig: Signer, body: Value) -> Response {
-        todo!()
-    }
-
-    /// Serve an ActivityPub object as json-ld.
-    pub fn serve_object(cx: &Context, object_ulid: &str) -> Result<Response, Message> {
-        let Ok(parsed) = object_ulid.parse::<Key>() else {
-            return Err(Message {
-                error: "improperly formatted ulid",
-                ..error::BAD_REQUEST
-            });
-        };
-        let result = cx.run(|tx| get_local_ap_object(&tx, parsed));
-        let Ok(object) = result else {
-            return Err(error::NOT_FOUND);
-        };
-        let json = to_string(&object.to_json_ld()).unwrap();
-        Ok(respond(200, Some(json), [AP_CONTENT_TYPE]))
-    }
-
-    const AP_CONTENT_TYPE: (&str, &str) = ("content-type", "application/activity+json");
-
-    /// Serve the special actor used for signing requests.
-    pub fn serve_verifier_actor(verifier: &Verifier) -> Response {
-        let body = verifier.to_json_ld();
-        let encoded = serde_json::to_vec(&body).unwrap();
-        respond(200, Some(encoded), [AP_CONTENT_TYPE])
-    }
-}
-
-pub mod wf {
-    //! WebFinger endpoints and related stuff.
-
-    use puppy::{
-        data::{Id, Username},
-        Context,
-    };
-    use serde_json::{json, Value};
-
-    use super::{
-        error::{Message, BAD_REQUEST, INTERNAL, NOT_FOUND},
-        respond, Response,
-    };
-
-    const WF_CONTENT_TYPE: (&str, &str) = ("content-type", "application/jrd+json");
-
-    /// Respond to a webfinger request.
-    pub fn resolve(cx: &Context, params: &[(&str, &str)]) -> Result<Response, Message> {
-        match params.iter().find_map(get_handle) {
-            Some(handle) if cx.config().wf_domain == handle.instance => {
-                let username = Username(handle.username.to_string());
-                let Ok(Some(user)) = cx.store().lookup(username) else {
-                    do yeet NOT_FOUND;
-                };
-                let Ok(Some(Id(id))) = cx.store().get_alias(user) else {
-                    do yeet INTERNAL;
-                };
-                let jrd = make_jrd(handle, &id);
-                let encoded = serde_json::to_vec(&jrd).unwrap();
-                Ok(respond(200, Some(encoded), [WF_CONTENT_TYPE]))
-            }
-            Some(_) | None => Err(Message {
-                error: "missing/invalid resource parameter",
-                ..BAD_REQUEST
-            }),
-        }
-    }
-
-    #[derive(Clone, Copy)]
-    pub struct Handle<'x> {
-        username: &'x str,
-        instance: &'x str,
-    }
-
-    /// Parse the `resource` parameter into a [`Handle`].
-    fn get_handle<'x>((k, v): &'x (&str, &str)) -> Option<Handle<'x>> {
-        // We're looking for the `resource` query parameter.
-        if *k == "resource" {
-            // This prefix needs to exist according to spec.
-            let (username, instance) = v
-                .strip_prefix("acct:")?
-                // Some implementations may prefix with `@`. its ok if it's there and its also ok
-                // if its not there, so we use `trim_start_matches` instead of `strip_prefix`.
-                .trim_start_matches('@')
-                // Split on the middle `@` symbol, which separates the username and instance bits
-                .split_once('@')?;
-            Some(Handle { username, instance })
-        } else {
-            None
-        }
-    }
-
-    /// Construct a "JSON resource descriptor".
-    fn make_jrd(handle: Handle<'_>, id: &str) -> Value {
-        json!({
-          "subject": format!("acct:{}@{}", handle.username, handle.instance),
-          "links": [
-            {
-              "rel": "self",
-              "type": "application/activity+json",
-              "href": id
-            },
-          ]
+// A simple macro for returning an error message.
+macro_rules! fuck {
+    ($code:literal: $($arg:tt)*) => {
+        return Err(crate::api::error::Message {
+            status: $code,
+            error: format!($($arg)*),
+            detail: None,
         })
-    }
+    };
 }
 
+pub mod ap;
+pub mod wf;
+
 type Request = hyper::Request<hyper::body::Incoming>;
 type Response<T = Full<Bytes>> = hyper::Response<T>;
 
@@ -279,7 +135,7 @@ async fn handle(req: Request, verifier: &Verifier, cx: Context) -> Result<Respon
         Verdict::Unsigned => dispatch_public(cx, &verifier, &req).await,
         // If a signature was provided *but it turned out to be unverifiable*, show them the error message.
         Verdict::Rejected { reason, signature_str } => Err(Message {
-            error: "signature verification failed",
+            error: String::from("signature verification failed for request"),
             status: 403,
             detail: Some(json!({
                 "signature": signature_str,
@@ -331,11 +187,11 @@ async fn dispatch_public(
     req: &Req<'_>,
 ) -> Result<Response, Message> {
     match (req.method, req.path()) {
-        (GET, ["proxy"]) => Ok(ap::proxy(&cx, &req.params).await),
+        (GET, ["proxy"]) => ap::proxy(&cx, &req.params).await,
         (GET, [".well-known", "webfinger"]) => wf::resolve(&cx, &req.params),
         // TODO: nicer solution for this
         (GET, VERIFIER_MOUNT) => Ok(ap::serve_verifier_actor(&verifier)),
-        _ => Err(error::NOT_FOUND),
+        _ => fuck!(404: "not found"),
     }
 }
 
@@ -343,13 +199,10 @@ fn with_json(
     body: &[u8],
     f: impl FnOnce(Value) -> Result<Response, Message>,
 ) -> Result<Response, Message> {
-    let Ok(json) = from_slice(body) else {
-        return Err(Message {
-            error: "could not decode json",
-            ..error::BAD_REQUEST
-        });
-    };
-    f(json)
+    match from_slice(body) {
+        Ok(json) => f(json),
+        Err(e) => fuck!(400: "could not decode json: {e}"),
+    }
 }
 
 /// A quick, simple way to construct a response.
@@ -378,7 +231,7 @@ mod error {
     /// An error message shown to an end user of the API.
     pub struct Message {
         /// The main error message.
-        pub error: &'static str,
+        pub error: String,
         /// Only shown if the `accept` header included json.
         pub detail: Option<Value>,
         /// The status code for the response.
@@ -414,25 +267,4 @@ mod error {
                 .any(|(k, v)| k == "application" && v.split('+').any(|p| p == "json"))
         }
     }
-
-    /// A 404 NOT FOUND response.
-    pub const NOT_FOUND: Message = Message {
-        error: "not found",
-        detail: None,
-        status: 404,
-    };
-
-    /// A basic 400 BAD REQUEST response.
-    pub const BAD_REQUEST: Message = Message {
-        error: "bad request",
-        detail: None,
-        status: 400,
-    };
-
-    /// A basic 500 INTERNAL SERVER ERROR message.
-    pub const INTERNAL: Message = Message {
-        error: "internal server error",
-        detail: None,
-        status: 500,
-    };
 }

bin/server/src/api/ap.rs

@@ -0,0 +1,66 @@
+//! ActivityPub handlers.
+
+use http_body_util::Full;
+use hyper::body::Bytes;
+use puppy::{
+    actor::{get_signing_key, Actor},
+    get_local_ap_object, Context, Error, Key,
+};
+use serde_json::{to_string, Value};
+
+use crate::sig::{Signer, Verifier};
+use super::{error::Message, respond, Response};
+
+/// Proxy a request through the instance.
+pub async fn proxy(cx: &Context, params: &[(&str, &str)]) -> Result<Response, Message> {
+    // Extract our query parameters.
+    let Some(user) = params.iter().find_map(|(k, v)| (*k == "user").then_some(v)) else {
+        fuck!(400: "Expected `user` query param");
+    };
+    let Some(url) = params.iter().find_map(|(k, v)| (*k == "url").then_some(v)) else {
+        fuck!(400: "Expected `url` query param");
+    };
+
+    // Look up the actor's key in the store (which is accessible through the puppy context).
+    let Ok(signing_key) = cx.run(|tx| {
+        let actor = Actor::by_username(&tx, user)?.unwrap();
+        get_signing_key(tx, actor).map_err(Error::from)
+    }) else {
+        fuck!(500: "failed to get signing key");
+    };
+
+    eprintln!("proxy: params: {params:?}");
+    // Proxy the request through our fetcher.
+    let resp = puppy::fetch::forward(&signing_key, url).await.unwrap();
+    eprintln!("proxy: status = {}", resp.status());
+
+    // Convert the http-types request to a hyper request.
+    Ok(resp.map(Bytes::from).map(Full::new).into())
+}
+
+/// Handle POSTs to actor inboxes. Requires request signature.
+pub fn inbox(cx: &Context, actor_id: &str, sig: Signer, body: Value) -> Response {
+    todo!()
+}
+
+/// Serve an ActivityPub object as json-ld.
+pub fn serve_object(cx: &Context, object_ulid: &str) -> Result<Response, Message> {
+    let Ok(parsed) = object_ulid.parse::<Key>() else {
+        fuck!(400: "improperly formatted ulid");
+    };
+    let result = cx.run(|tx| get_local_ap_object(&tx, parsed));
+    let Ok(object) = result else {
+        fuck!(404: "object does not exist");
+    };
+    let json = to_string(&object.to_json_ld()).unwrap();
+    Ok(respond(200, Some(json), [AP_CONTENT_TYPE]))
+}
+
+const AP_CONTENT_TYPE: (&str, &str) = ("content-type", "application/activity+json");
+
+/// Serve the special actor used for signing requests.
+pub fn serve_verifier_actor(verifier: &Verifier) -> Response {
+    let body = verifier.to_json_ld();
+    let encoded = serde_json::to_vec(&body).unwrap();
+    respond(200, Some(encoded), [AP_CONTENT_TYPE])
+}

bin/server/src/api/wf.rs

@@ -0,0 +1,70 @@
+//! WebFinger endpoints and related stuff.
+
+use puppy::{
+    data::{Id, Username},
+    Context,
+};
+use serde_json::{json, Value};
+use derive_more::Display;
+
+use super::{error::Message, respond, Response};
+
+const WF_CONTENT_TYPE: (&str, &str) = ("content-type", "application/jrd+json");
+
+/// Respond to a webfinger request.
+pub fn resolve(cx: &Context, params: &[(&str, &str)]) -> Result<Response, Message> {
+    match params.iter().find_map(get_handle) {
+        Some(handle) if cx.config().wf_domain == handle.instance => {
+            let username = Username(handle.username.to_string());
+            let Ok(Some(user)) = cx.store().lookup(username) else {
+                fuck!(404: "no user {}@{} exists", handle.username, handle.instance);
+            };
+            let Ok(Some(Id(id))) = cx.store().get_alias(user) else {
+                fuck!(500: "internal error");
+            };
+            let jrd = make_jrd(handle, &id);
+            let encoded = serde_json::to_vec(&jrd).unwrap();
+            Ok(respond(200, Some(encoded), [WF_CONTENT_TYPE]))
+        }
+        Some(_) | None => fuck!(400: "missing/invalid resource param"),
+    }
+}
+
+#[derive(Clone, Copy, Display)]
+#[display(fmt = "@{username}@{instance}")]
+pub struct Handle<'x> {
+    username: &'x str,
+    instance: &'x str,
+}
+
+/// Parse the `resource` parameter into a [`Handle`].
+fn get_handle<'x>((k, v): &'x (&str, &str)) -> Option<Handle<'x>> {
+    // We're looking for the `resource` query parameter.
+    if *k == "resource" {
+        // This prefix needs to exist according to spec.
+        let (username, instance) = v
+            .strip_prefix("acct:")?
+            // Some implementations may prefix with `@`. its ok if it's there and its also ok
+            // if its not there, so we use `trim_start_matches` instead of `strip_prefix`.
+            .trim_start_matches('@')
+            // Split on the middle `@` symbol, which separates the username and instance bits
+            .split_once('@')?;
+        Some(Handle { username, instance })
+    } else {
+        None
+    }
+}
+
+/// Construct a "JSON resource descriptor".
+fn make_jrd(handle: Handle<'_>, id: &str) -> Value {
+    json!({
+      "subject": format!("acct:{}@{}", handle.username, handle.instance),
+      "links": [
+        {
+          "rel": "self",
+          "type": "application/activity+json",
+          "href": id
+        },
+      ]
+    })
+}

lib/puppy/src/lib.rs

@@ -88,7 +88,7 @@ pub fn get_local_ap_object(tx: &Transaction<'_>, key: Key) -> Result<fetch::obje
 }
 
 pub mod actor {
-    use fetch::signatures::Private;
+    use fetch::signatures::{Private, SigningKey};
     use store::{Key, StoreError, Transaction};
 
     use crate::{
@@ -173,6 +173,14 @@ pub mod actor {
         tx.add_mixin(vertex, PrivateKey { key_pem: private.encode_pem() })?;
         store::OK
     }
+
+    pub fn get_signing_key(tx: &Transaction<'_>, actor: Actor) -> Result<SigningKey, StoreError> {
+        let (PrivateKey { key_pem, .. }, PublicKey { key_id, .. }) =
+            tx.get_mixin_many(actor.key)?;
+        let Id(owner) = tx.get_alias(actor.key)?.unwrap();
+        let inner = Private::decode_pem(&key_pem);
+        Ok(SigningKey { id: key_id, owner, inner })
+    }
 }
 
 pub type Result<T, E = Error> = std::result::Result<T, E>;