A lexicon-driven AppView for ATProto.
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Rust
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#[derive(Debug, Clone, Serialize)]#[serde(rename_all = "snake_case")]pub enum ScriptErrorType { Syntax, Runtime, Timeout, MissingHandle,}
impl std::fmt::Display for ScriptErrorType { fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { match self { ScriptErrorType::Syntax => write!(f, "syntax"), ScriptErrorType::Runtime => write!(f, "runtime"), ScriptErrorType::Timeout => write!(f, "timeout"), ScriptErrorType::MissingHandle => write!(f, "missing_handle"), } }}
/// Parse a Lua error message to extract a line number.////// Prefix used to tag auth errors that pass through the Lua runtime boundary./// The script executor checks for this prefix to recover `AppError::Auth` from/// a generic `mlua::Error::runtime`, returning 401 instead of 500.pub const LUA_AUTH_ERROR_PREFIX: &str = "AUTH_ERROR:";
/// mlua errors look like:/// - `[string "..."]:42: attempt to index a nil value`/// - `runtime error: [string "..."]:10: bad argument`////// Returns `(Some(line), cleaned_message)` or `(None, original_message)`.pub fn parse_lua_line(raw: &str) -> (Option<u32>, String) { if let Some(bracket_pos) = raw.find("]:") { let after_bracket = &raw[bracket_pos + 2..]; if let Some(colon_pos) = after_bracket.find(": ") { let line_str = &after_bracket[..colon_pos]; if let Ok(line) = line_str.parse::<u32>() { let message = after_bracket[colon_pos + 2..].to_string(); return (Some(line), message); } } } (None, raw.to_string())}
#[derive(Debug)]pub enum AppError { Auth(String), /// Auth failure with a DPoP nonce that the client should retry with. AuthDpopNonce(String), BadGateway(String), BadRequest(String), Conflict(String), FeatureDisabled(String), Forbidden(String), InsufficientPermissions(String), Internal(String), NotFound(String), PdsError(StatusCode, Bytes), RateLimited { retry_after: u64, limit: u32, reset: u64, }, ScriptError { error_type: ScriptErrorType, message: String, method: String, line: Option<u32>, },}
impl std::fmt::Display for AppError { fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { match self { AppError::Auth(msg) => write!(f, "auth error: {msg}"), AppError::AuthDpopNonce(nonce) => write!(f, "auth error: use_dpop_nonce ({nonce})"), AppError::BadGateway(msg) => write!(f, "bad gateway: {msg}"), AppError::BadRequest(msg) => write!(f, "bad request: {msg}"), AppError::Conflict(msg) => write!(f, "conflict: {msg}"), AppError::FeatureDisabled(msg) => write!(f, "feature disabled: {msg}"), AppError::Forbidden(msg) => write!(f, "forbidden: {msg}"), AppError::InsufficientPermissions(perm) => write!(f, "Missing permission: {perm}"), AppError::Internal(msg) => write!(f, "internal error: {msg}"), AppError::NotFound(msg) => write!(f, "not found: {msg}"), AppError::PdsError(status, _) => write!(f, "PDS error: {status}"), AppError::RateLimited { retry_after, .. } => { write!(f, "rate limited: retry after {retry_after}s") } AppError::ScriptError { error_type, message, method, line, } => { if let Some(l) = line { write!( f, "script {error_type} error in {method} at line {l}: {message}" ) } else { write!(f, "script {error_type} error in {method}: {message}") } } } }}
impl IntoResponse for AppError { fn into_response(self) -> Response { match self { AppError::PdsError(status, body) => ( status, [(axum::http::header::CONTENT_TYPE, "application/json")], body, ) .into_response(), AppError::AuthDpopNonce(nonce) => { let body = serde_json::json!({ "error": "use_dpop_nonce", "dpop_nonce": nonce }); let mut response = (StatusCode::UNAUTHORIZED, axum::Json(body)).into_response(); if let Ok(val) = axum::http::HeaderValue::from_str(&nonce) { response.headers_mut().insert("dpop-nonce", val); } response } AppError::ScriptError { error_type, message, method, line, } => { let status = match &error_type { ScriptErrorType::Timeout => StatusCode::REQUEST_TIMEOUT, _ => StatusCode::INTERNAL_SERVER_ERROR, }; tracing::error!(%method, ?error_type, ?line, "{message}"); let body = serde_json::json!({ "error": "script_error", "errorType": error_type, "message": message, "method": method, "line": line, }); (status, axum::Json(body)).into_response() } AppError::FeatureDisabled(msg) => { let body = serde_json::json!({ "error": "FeatureDisabled", "message": msg, }); (StatusCode::NOT_FOUND, axum::Json(body)).into_response() } AppError::InsufficientPermissions(perm) => { let body = serde_json::json!({ "error": "InsufficientPermissions", "message": format!("Missing permission: {perm}"), }); (StatusCode::FORBIDDEN, axum::Json(body)).into_response() } AppError::RateLimited { retry_after, limit, reset, } => { let body = serde_json::json!({ "error": "RateLimited", "message": "Too many requests", }); let mut response = (StatusCode::TOO_MANY_REQUESTS, axum::Json(body)).into_response(); let headers = response.headers_mut(); headers.insert("RateLimit-Limit", limit.into()); headers.insert("RateLimit-Remaining", 0u32.into()); headers.insert("RateLimit-Reset", reset.into()); headers.insert("Retry-After", retry_after.into()); response } other => { let (status, message) = match &other { AppError::Auth(msg) => (StatusCode::UNAUTHORIZED, msg.clone()), AppError::BadGateway(msg) => (StatusCode::BAD_GATEWAY, msg.clone()), AppError::BadRequest(msg) => (StatusCode::BAD_REQUEST, msg.clone()), AppError::Conflict(msg) => (StatusCode::CONFLICT, msg.clone()), AppError::Forbidden(msg) => (StatusCode::FORBIDDEN, msg.clone()), AppError::Internal(msg) => { tracing::error!("{msg}"); (StatusCode::INTERNAL_SERVER_ERROR, msg.clone()) } AppError::NotFound(msg) => (StatusCode::NOT_FOUND, msg.clone()), AppError::PdsError(..) | AppError::AuthDpopNonce(..) | AppError::FeatureDisabled(..) | AppError::InsufficientPermissions(..) | AppError::RateLimited { .. } | AppError::ScriptError { .. } => unreachable!(), };
let body = serde_json::json!({ "error": message }); (status, axum::Json(body)).into_response() } } }}
#[cfg(test)]mod tests { use super::*; use axum::response::IntoResponse; use http_body_util::BodyExt;
async fn response_parts(err: AppError) -> (StatusCode, serde_json::Value) { let resp = err.into_response(); let status = resp.status(); let body = resp.into_body().collect().await.unwrap().to_bytes(); let json: serde_json::Value = serde_json::from_slice(&body).unwrap(); (status, json) }
#[tokio::test] async fn auth_error_returns_401() { let (status, body) = response_parts(AppError::Auth("bad token".into())).await; assert_eq!(status, StatusCode::UNAUTHORIZED); assert_eq!(body["error"], "bad token"); }
#[tokio::test] async fn bad_request_returns_400() { let (status, body) = response_parts(AppError::BadRequest("missing field".into())).await; assert_eq!(status, StatusCode::BAD_REQUEST); assert_eq!(body["error"], "missing field"); }
#[tokio::test] async fn internal_error_returns_500_with_message() { let (status, body) = response_parts(AppError::Internal("secret details".into())).await; assert_eq!(status, StatusCode::INTERNAL_SERVER_ERROR); assert_eq!(body["error"], "secret details"); }
#[tokio::test] async fn script_error_returns_500_with_structured_body() { let (status, body) = response_parts(AppError::ScriptError { error_type: ScriptErrorType::Runtime, message: "attempt to index a nil value".into(), method: "games.gamesgamesgamesgames.search".into(), line: Some(42), }) .await; assert_eq!(status, StatusCode::INTERNAL_SERVER_ERROR); assert_eq!(body["error"], "script_error"); assert_eq!(body["errorType"], "runtime"); assert_eq!(body["message"], "attempt to index a nil value"); assert_eq!(body["method"], "games.gamesgamesgamesgames.search"); assert_eq!(body["line"], 42); }
#[tokio::test] async fn script_error_timeout_returns_408() { let (status, body) = response_parts(AppError::ScriptError { error_type: ScriptErrorType::Timeout, message: "script exceeded execution time limit".into(), method: "test.method".into(), line: None, }) .await; assert_eq!(status, StatusCode::REQUEST_TIMEOUT); assert_eq!(body["error"], "script_error"); assert_eq!(body["errorType"], "timeout"); assert!(body["line"].is_null()); }
#[tokio::test] async fn script_error_syntax_returns_500() { let (status, body) = response_parts(AppError::ScriptError { error_type: ScriptErrorType::Syntax, message: "unexpected symbol near ')'".into(), method: "test.method".into(), line: Some(5), }) .await; assert_eq!(status, StatusCode::INTERNAL_SERVER_ERROR); assert_eq!(body["error"], "script_error"); assert_eq!(body["errorType"], "syntax"); assert_eq!(body["line"], 5); }
#[tokio::test] async fn feature_disabled_returns_404() { let (status, body) = response_parts(AppError::FeatureDisabled("spaces not enabled".into())).await; assert_eq!(status, StatusCode::NOT_FOUND); assert_eq!(body["error"], "FeatureDisabled"); assert_eq!(body["message"], "spaces not enabled"); }
#[tokio::test] async fn not_found_returns_404() { let (status, body) = response_parts(AppError::NotFound("no such thing".into())).await; assert_eq!(status, StatusCode::NOT_FOUND); assert_eq!(body["error"], "no such thing"); }
#[tokio::test] async fn pds_error_preserves_status_and_body() { let raw_body = Bytes::from(r#"{"error":"upstream"}"#); let resp = AppError::PdsError(StatusCode::BAD_GATEWAY, raw_body.clone()).into_response(); assert_eq!(resp.status(), StatusCode::BAD_GATEWAY); let body = resp.into_body().collect().await.unwrap().to_bytes(); assert_eq!(body, raw_body); }
#[test] fn parse_lua_line_extracts_line_number() { let (line, msg) = parse_lua_line("[string \"...\"]:42: attempt to index a nil value"); assert_eq!(line, Some(42)); assert_eq!(msg, "attempt to index a nil value"); }
#[test] fn parse_lua_line_no_line_number() { let (line, msg) = parse_lua_line("some other error"); assert_eq!(line, None); assert_eq!(msg, "some other error"); }
#[test] fn parse_lua_line_runtime_error_prefix() { let (line, msg) = parse_lua_line("runtime error: [string \"...\"]:10: bad argument"); assert_eq!(line, Some(10)); assert_eq!(msg, "bad argument"); }
#[test] fn script_error_type_serializes() { assert_eq!( serde_json::to_string(&ScriptErrorType::Syntax).unwrap(), "\"syntax\"" ); assert_eq!( serde_json::to_string(&ScriptErrorType::Runtime).unwrap(), "\"runtime\"" ); assert_eq!( serde_json::to_string(&ScriptErrorType::Timeout).unwrap(), "\"timeout\"" ); assert_eq!( serde_json::to_string(&ScriptErrorType::MissingHandle).unwrap(), "\"missing_handle\"" ); }
#[test] fn display_formats() { assert_eq!(AppError::Auth("x".into()).to_string(), "auth error: x"); assert_eq!( AppError::BadRequest("y".into()).to_string(), "bad request: y" ); assert_eq!( AppError::Internal("z".into()).to_string(), "internal error: z" ); assert_eq!( AppError::FeatureDisabled("x".into()).to_string(), "feature disabled: x" ); assert_eq!(AppError::NotFound("w".into()).to_string(), "not found: w"); assert_eq!( AppError::PdsError(StatusCode::BAD_GATEWAY, Bytes::new()).to_string(), "PDS error: 502 Bad Gateway" ); assert_eq!( AppError::ScriptError { error_type: ScriptErrorType::Runtime, message: "oops".into(), method: "test.method".into(), line: Some(5), } .to_string(), "script runtime error in test.method at line 5: oops" ); }}