Merge branch 'fix/rate-limit-shared-nat'

backend/migrations/017_join_ip_rate.down.sql

@@ -0,0 +1 @@
+DELETE FROM config WHERE key IN ('join_ip_rate_per_min', 'admin_login_rate_enabled');

backend/migrations/017_join_ip_rate.up.sql

@@ -0,0 +1,18 @@
+-- Per-IP flood ceiling for /join, and the `admin_login_rate_enabled` toggle that
+-- every prior migration forgot to seed.
+--
+-- Rationale: /join was throttled at 5 requests per 60s keyed on the client IP. At a
+-- venue every guest is behind one NAT, so the whole party shared a single bucket —
+-- 12 guests scanning the QR code within a few seconds meant 5 got in and 7 were
+-- turned away. The handler now keys the real anti-spam bucket per (ip, name), the
+-- same shape as `recover:{ip}:{name}`, and keeps only a loose per-IP ceiling to bound
+-- raw volume. 60/min comfortably covers a whole wedding arriving at once while still
+-- capping a flood from a single source.
+--
+-- `admin_login_rate_enabled` is read by auth::handlers::admin_login with a code
+-- default of `true`, but no migration ever inserted it, so it was invisible to the
+-- admin config UI and to the e2e reseed. Seed it explicitly.
+INSERT INTO config (key, value) VALUES
+    ('join_ip_rate_per_min',     '60'),
+    ('admin_login_rate_enabled', 'true')
+ON CONFLICT (key) DO NOTHING;

backend/src/auth/handlers.rs

@@ -1,11 +1,12 @@
 use std::time::Duration;
 
 use axum::Json;
-use axum::extract::State;
+use axum::extract::{ConnectInfo, State};
 use axum::http::{HeaderMap, StatusCode};
 use chrono::Utc;
 use rand::Rng;
 use serde::{Deserialize, Serialize};
+use std::net::SocketAddr;
 use uuid::Uuid;
 
 use crate::auth::jwt;
@@ -33,22 +34,32 @@ pub struct JoinResponse {
 
 pub async fn join(
     State(state): State<AppState>,
+    ConnectInfo(peer): ConnectInfo<SocketAddr>,
     headers: HeaderMap,
     Json(body): Json<JoinRequest>,
 ) -> Result<(StatusCode, Json<JoinResponse>), AppError> {
-    let ip = client_ip(&headers, "unknown");
+    let ip = client_ip(&headers, &peer.ip().to_string());
     let rate_limits_on = config::get_bool(&state.config_cache, "rate_limits_enabled", true).await;
     let join_rate_on = config::get_bool(&state.config_cache, "join_rate_enabled", true).await;
-    if rate_limits_on
-        && join_rate_on
-        && !state
-            .rate_limiter
-            .check(format!("join:{ip}"), 5, Duration::from_secs(60))
-    {
-        return Err(AppError::TooManyRequests(
-            "Zu viele Anfragen. Bitte warte kurz und versuche es erneut.".into(),
-            None,
-        ));
+
+    // Coarse per-IP flood ceiling. `/join` is pre-auth so there is no user to key on, and
+    // at a venue EVERY guest arrives from one public IP — a tight per-IP bucket meant the
+    // 6th person through the door was turned away by the 5 ahead of them. So the per-IP
+    // limit here only bounds raw volume; the real anti-spam bucket is per-name below.
+    // Cheap enough to run before validation, which keeps a flood of malformed bodies from
+    // being free.
+    if rate_limits_on && join_rate_on {
+        let ip_ceiling = config::get_usize(&state.config_cache, "join_ip_rate_per_min", 60).await;
+        if let Err(retry_after_secs) = state.rate_limiter.check_with_retry(
+            format!("join_ip:{ip}"),
+            ip_ceiling,
+            Duration::from_secs(60),
+        ) {
+            return Err(AppError::TooManyRequests(
+                "Zu viele Anfragen. Bitte warte kurz und versuche es erneut.".into(),
+                Some(retry_after_secs),
+            ));
+        }
     }
 
     let display_name = body.display_name.trim();
@@ -66,6 +77,23 @@ pub async fn join(
         ));
     }
 
+    // Per-guest bucket, keyed like the `recover:{ip}:{name}` limiter below. This carries
+    // the original 5/60s anti-spam intent, but one guest retrying can no longer consume
+    // the allowance of everyone else sharing the venue's NAT.
+    if rate_limits_on && join_rate_on {
+        let name_key = display_name.to_lowercase();
+        if let Err(retry_after_secs) = state.rate_limiter.check_with_retry(
+            format!("join:{ip}:{name_key}"),
+            5,
+            Duration::from_secs(60),
+        ) {
+            return Err(AppError::TooManyRequests(
+                "Zu viele Anfragen. Bitte warte kurz und versuche es erneut.".into(),
+                Some(retry_after_secs),
+            ));
+        }
+    }
+
     let event = Event::find_or_create(
         &state.pool,
         &state.config.event_slug,
@@ -149,6 +177,7 @@ fn dummy_pin_hash() -> &'static str {
 
 pub async fn recover(
     State(state): State<AppState>,
+    ConnectInfo(peer): ConnectInfo<SocketAddr>,
     headers: HeaderMap,
     Json(body): Json<RecoverRequest>,
 ) -> Result<Json<RecoverResponse>, AppError> {
@@ -159,19 +188,19 @@ pub async fn recover(
     // burn through 3 wrong PINs and lock the victim for 15 minutes — repeated
     // every 15 minutes, indefinitely. 5 attempts per 15 minutes per (IP, name)
     // softens that into a real cost.
-    let ip = client_ip(&headers, "unknown");
+    let ip = client_ip(&headers, &peer.ip().to_string());
     let rate_limits_on = config::get_bool(&state.config_cache, "rate_limits_enabled", true).await;
     let recover_rate_on = config::get_bool(&state.config_cache, "recover_rate_enabled", true).await;
     if rate_limits_on && recover_rate_on {
         let name_key = display_name.to_lowercase();
-        if !state.rate_limiter.check(
+        if let Err(retry_after_secs) = state.rate_limiter.check_with_retry(
             format!("recover:{ip}:{name_key}"),
             5,
             Duration::from_secs(15 * 60),
         ) {
             return Err(AppError::TooManyRequests(
                 "Zu viele Versuche. Bitte warte kurz und versuche es erneut.".into(),
-                None,
+                Some(retry_after_secs),
             ));
         }
     }
@@ -200,9 +229,12 @@ pub async fn recover(
         // is effectively permanently fragile.
         if let Some(locked_until) = user.pin_locked_until {
             if Utc::now() < locked_until {
+                // The exact deadline is known, so surface it as Retry-After instead of
+                // making the client guess at the "15 Minuten" in the copy.
+                let retry_after_secs = (locked_until - Utc::now()).num_seconds().max(1) as u64;
                 return Err(AppError::TooManyRequests(
                     "Zu viele Versuche. Bitte warte 15 Minuten.".into(),
-                    None,
+                    Some(retry_after_secs),
                 ));
             }
             // Lockout window expired — wipe the counter and the timestamp.
@@ -274,6 +306,7 @@ pub struct AdminLoginResponse {
 
 pub async fn admin_login(
     State(state): State<AppState>,
+    ConnectInfo(peer): ConnectInfo<SocketAddr>,
     headers: HeaderMap,
     Json(body): Json<AdminLoginRequest>,
 ) -> Result<Json<AdminLoginResponse>, AppError> {
@@ -287,19 +320,23 @@ pub async fn admin_login(
     // verify) but with no IP-level limit a determined attacker can still mount
     // a long-running guess campaign. 5 attempts / minute / IP is plenty for
     // honest typos.
-    let ip = client_ip(&headers, "unknown");
+    let ip = client_ip(&headers, &peer.ip().to_string());
     let rate_limits_on = config::get_bool(&state.config_cache, "rate_limits_enabled", true).await;
     let admin_rate_on =
         config::get_bool(&state.config_cache, "admin_login_rate_enabled", true).await;
+    // Stays keyed by IP on purpose: this guards a single shared credential, so a per-user
+    // or per-name key would just hand an attacker a fresh bucket per guess.
     if rate_limits_on
         && admin_rate_on
-        && !state
-            .rate_limiter
-            .check(format!("admin_login:{ip}"), 5, Duration::from_secs(60))
+        && let Err(retry_after_secs) = state.rate_limiter.check_with_retry(
+            format!("admin_login:{ip}"),
+            5,
+            Duration::from_secs(60),
+        )
     {
         return Err(AppError::TooManyRequests(
             "Zu viele Anmeldeversuche. Bitte warte kurz und versuche es erneut.".into(),
-            None,
+            Some(retry_after_secs),
         ));
     }
 
@@ -390,22 +427,23 @@ pub struct PinResetRequestBody {
 /// feed already exposes.
 pub async fn request_pin_reset(
     State(state): State<AppState>,
+    ConnectInfo(peer): ConnectInfo<SocketAddr>,
     headers: HeaderMap,
     Json(body): Json<PinResetRequestBody>,
 ) -> Result<StatusCode, AppError> {
     let display_name = body.display_name.trim();
-    let ip = client_ip(&headers, "unknown");
+    let ip = client_ip(&headers, &peer.ip().to_string());
     let rate_limits_on = config::get_bool(&state.config_cache, "rate_limits_enabled", true).await;
     if rate_limits_on {
         let name_key = display_name.to_lowercase();
-        if !state.rate_limiter.check(
+        if let Err(retry_after_secs) = state.rate_limiter.check_with_retry(
             format!("pin_reset_req:{ip}:{name_key}"),
             3,
             Duration::from_secs(15 * 60),
         ) {
             return Err(AppError::TooManyRequests(
                 "Zu viele Anfragen. Bitte warte kurz und versuche es erneut.".into(),
-                None,
+                Some(retry_after_secs),
             ));
         }
     }

backend/src/handlers/admin.rs

@@ -3,13 +3,13 @@ use std::time::Duration;
 
 use axum::Json;
 use axum::extract::{Query, State};
-use axum::http::{HeaderMap, StatusCode};
+use axum::http::StatusCode;
 use serde::{Deserialize, Serialize};
+use uuid::Uuid;
 
 use crate::auth::middleware::RequireAdmin;
 use crate::error::AppError;
 use crate::services::config;
-use crate::services::rate_limiter::client_ip;
 use crate::state::AppState;
 
 // ── DTOs ─────────────────────────────────────────────────────────────────────
@@ -120,6 +120,10 @@ pub async fn patch_config(
         ("upload_rate_per_hour", true, 1.0, 100_000.0),
         ("feed_rate_per_min", true, 1.0, 100_000.0),
         ("export_rate_per_day", true, 1.0, 100_000.0),
+        // Loose per-IP ceiling on /join. The real anti-spam bucket is per (ip, name); this
+        // only bounds raw volume from one source, so it must stay well above the size of a
+        // party arriving at once (see migration 017).
+        ("join_ip_rate_per_min", true, 1.0, 100_000.0),
         ("quota_tolerance", false, 0.0, 1.0),
         ("estimated_guest_count", true, 1.0, 1_000_000.0),
     ];
@@ -320,25 +324,26 @@ pub async fn export_ticket(
 }
 
 /// Validate a download ticket (single-use) and confirm its session still exists.
-async fn authenticate_download_ticket(state: &AppState, ticket: &str) -> Result<(), AppError> {
+/// Resolve a single-use download ticket to the user who minted it. The caller needs the
+/// id to key the export rate limit per-user (see `enforce_export_rate`).
+async fn authenticate_download_ticket(state: &AppState, ticket: &str) -> Result<Uuid, AppError> {
     let token_hash = state
         .sse_tickets
         .consume(ticket)
         .ok_or_else(|| AppError::Unauthorized("Ticket ungültig oder abgelaufen.".into()))?;
-    crate::models::session::Session::find_by_token_hash(&state.pool, &token_hash)
+    let session = crate::models::session::Session::find_by_token_hash(&state.pool, &token_hash)
         .await
         .map_err(|e| AppError::Internal(e.into()))?
         .ok_or_else(|| AppError::Unauthorized("Sitzung nicht gefunden.".into()))?;
-    Ok(())
+    Ok(session.user_id)
 }
 
 pub async fn download_zip(
     State(state): State<AppState>,
     Query(q): Query<DownloadQuery>,
-    headers: HeaderMap,
 ) -> Result<axum::response::Response, AppError> {
-    authenticate_download_ticket(&state, &q.ticket).await?;
-    enforce_export_rate(&state, &headers).await?;
+    let user_id = authenticate_download_ticket(&state, &q.ticket).await?;
+    enforce_export_rate(&state, user_id).await?;
 
     let path =
         resolve_export_file(&state, "zip", "Der ZIP-Export ist noch nicht verfügbar.").await?;
@@ -389,10 +394,9 @@ async fn resolve_export_file(
 pub async fn download_html(
     State(state): State<AppState>,
     Query(q): Query<DownloadQuery>,
-    headers: HeaderMap,
 ) -> Result<axum::response::Response, AppError> {
-    authenticate_download_ticket(&state, &q.ticket).await?;
-    enforce_export_rate(&state, &headers).await?;
+    let user_id = authenticate_download_ticket(&state, &q.ticket).await?;
+    enforce_export_rate(&state, user_id).await?;
 
     let path =
         resolve_export_file(&state, "html", "Der HTML-Export ist noch nicht verfügbar.").await?;
@@ -476,21 +480,24 @@ pub async fn export_status(
 /// Centralised guard for the export rate limit. Same pattern as upload/feed: master
 /// switch + per-endpoint switch + numeric value, all stored in `config` and read on
 /// each request.
-async fn enforce_export_rate(state: &AppState, headers: &HeaderMap) -> Result<(), AppError> {
+async fn enforce_export_rate(state: &AppState, user_id: Uuid) -> Result<(), AppError> {
     let rate_limits_on = config::get_bool(&state.config_cache, "rate_limits_enabled", true).await;
     let export_rate_on = config::get_bool(&state.config_cache, "export_rate_enabled", true).await;
     if !(rate_limits_on && export_rate_on) {
         return Ok(());
     }
-    let ip = client_ip(headers, "unknown");
     let limit = config::get_usize(&state.config_cache, "export_rate_per_day", 3).await;
-    if !state
-        .rate_limiter
-        .check(format!("export:{ip}"), limit, Duration::from_secs(86400))
-    {
+    // Keyed per-user. This was the worst of the IP-keyed limiters: 3 downloads per DAY
+    // shared across every guest behind the venue's public IP, so the fourth person to
+    // fetch their keepsake was locked out until the next day.
+    if let Err(retry_after_secs) = state.rate_limiter.check_with_retry(
+        format!("export:{user_id}"),
+        limit,
+        Duration::from_secs(86400),
+    ) {
         return Err(AppError::TooManyRequests(
             "Zu viele Anfragen. Bitte warte kurz und versuche es erneut.".into(),
-            None,
+            Some(retry_after_secs),
         ));
     }
     Ok(())

backend/src/handlers/feed.rs

@@ -2,7 +2,6 @@ use std::time::Duration;
 
 use axum::Json;
 use axum::extract::{Query, State};
-use axum::http::HeaderMap;
 use chrono::{DateTime, Utc};
 use serde::{Deserialize, Serialize};
 use uuid::Uuid;
@@ -10,7 +9,6 @@ use uuid::Uuid;
 use crate::auth::middleware::AuthUser;
 use crate::error::AppError;
 use crate::services::config;
-use crate::services::rate_limiter::client_ip;
 use crate::state::AppState;
 
 #[derive(Deserialize)]
@@ -61,21 +59,23 @@ struct FeedRow {
 pub async fn feed(
     State(state): State<AppState>,
     auth: AuthUser,
-    headers: HeaderMap,
     Query(q): Query<FeedQuery>,
 ) -> Result<Json<FeedResponse>, AppError> {
-    let ip = client_ip(&headers, "unknown");
     let rate_limits_on = config::get_bool(&state.config_cache, "rate_limits_enabled", true).await;
     let feed_rate_on = config::get_bool(&state.config_cache, "feed_rate_enabled", true).await;
     if rate_limits_on && feed_rate_on {
         let rate_limit = config::get_usize(&state.config_cache, "feed_rate_per_min", 60).await;
-        if !state
-            .rate_limiter
-            .check(format!("feed:{ip}"), rate_limit, Duration::from_secs(60))
-        {
+        // Keyed per-user, exactly like `feed_delta` below: at a venue every guest shares
+        // one public IP, so an IP key gave the whole party a single 60/min bucket and the
+        // fastest scroller starved everyone else.
+        if let Err(retry_after_secs) = state.rate_limiter.check_with_retry(
+            format!("feed:{}", auth.user_id),
+            rate_limit,
+            Duration::from_secs(60),
+        ) {
             return Err(AppError::TooManyRequests(
                 "Zu viele Anfragen. Bitte warte kurz und versuche es erneut.".into(),
-                None,
+                Some(retry_after_secs),
             ));
         }
     }
@@ -225,14 +225,14 @@ pub async fn feed_delta(
     let feed_rate_on = config::get_bool(&state.config_cache, "feed_rate_enabled", true).await;
     if rate_limits_on && feed_rate_on {
         let rate_limit = config::get_usize(&state.config_cache, "feed_rate_per_min", 60).await;
-        if !state.rate_limiter.check(
+        if let Err(retry_after_secs) = state.rate_limiter.check_with_retry(
             format!("feed_delta:{}", auth.user_id),
             rate_limit,
             Duration::from_secs(60),
         ) {
             return Err(AppError::TooManyRequests(
                 "Zu viele Anfragen. Bitte warte kurz und versuche es erneut.".into(),
-                None,
+                Some(retry_after_secs),
             ));
         }
     }

backend/src/handlers/test_admin.rs

@@ -13,9 +13,10 @@ use crate::auth::middleware::RequireAdmin;
 use crate::error::AppError;
 use crate::state::AppState;
 
-/// Truncates every event-scoped table, wipes media on disk, and reseeds the
-/// `config` table from migration defaults. Requires an admin JWT — even with
-/// `EVENTSNAP_TEST_MODE=1` it cannot be hit anonymously.
+/// Truncates every event-scoped table, wipes media on disk, and reseeds the `config`
+/// table: numeric values from the migration defaults, but every feature toggle forced
+/// OFF (production seeds them ON — see the note at the reseed below). Requires an admin
+/// JWT — even with `EVENTSNAP_TEST_MODE=1` it cannot be hit anonymously.
 pub async fn truncate_all(
     State(state): State<AppState>,
     RequireAdmin(_auth): RequireAdmin,
@@ -40,8 +41,19 @@ pub async fn truncate_all(
     .execute(&state.pool)
     .await?;
 
-    // Reseed config — mirrors migrations 005, 009 and 015. Kept in sync by hand
-    // because pulling SQL out of the migration files at runtime is fragile.
+    // Reseed config. The NUMERIC values mirror migrations 005/015/016; the BOOLEAN
+    // toggles deliberately do NOT — migration 009 seeds every one of them `true`
+    // (production), and this forces them `false` so the suite isn't fighting rate limits
+    // and quotas it isn't testing.
+    //
+    // Be aware of what that costs: this runs as an auto-fixture before EVERY test, so no
+    // test starts from production's config unless it explicitly turns a toggle back on
+    // (02-upload/rate-limit, 07-adversarial/ddos, 01-auth/rate-limit-nat, …). That blind
+    // spot is exactly why an entire class of per-IP limiter bugs went unnoticed: the
+    // limiters were simply off. When adding a limiter or quota, add a spec that enables it.
+    //
+    // Kept in sync by hand because pulling SQL out of the migration files at runtime is
+    // fragile — if you add a config key in a migration, add it here too.
     sqlx::query(
         r#"INSERT INTO config (key, value) VALUES
             ('max_image_size_mb',          '20'),
@@ -49,6 +61,7 @@ pub async fn truncate_all(
             ('upload_rate_per_hour',       '100'),
             ('feed_rate_per_min',          '60'),
             ('export_rate_per_day',        '3'),
+            ('join_ip_rate_per_min',       '60'),
             ('quota_tolerance',            '0.75'),
             ('estimated_guest_count',      '100'),
             ('compression_concurrency',    '2'),
@@ -57,6 +70,7 @@ pub async fn truncate_all(
             ('feed_rate_enabled',          'false'),
             ('export_rate_enabled',        'false'),
             ('join_rate_enabled',          'false'),
+            ('admin_login_rate_enabled',   'false'),
             ('quota_enabled',              'false'),
             ('storage_quota_enabled',      'false'),
             ('upload_count_quota_enabled', 'false'),

backend/src/main.rs

@@ -252,9 +252,15 @@ async fn main() -> Result<()> {
 
     let listener = tokio::net::TcpListener::bind(("0.0.0.0", config.app_port)).await?;
     tracing::info!("listening on {}", listener.local_addr()?);
-    axum::serve(listener, router)
-        .with_graceful_shutdown(shutdown_signal())
-        .await?;
+    // `into_make_service_with_connect_info` is required by the pre-auth handlers, which
+    // extract `ConnectInfo<SocketAddr>` to use the peer address as the rate-limit key when
+    // X-Forwarded-For is absent. Without it those extractors fail at runtime.
+    axum::serve(
+        listener,
+        router.into_make_service_with_connect_info::<std::net::SocketAddr>(),
+    )
+    .with_graceful_shutdown(shutdown_signal())
+    .await?;
 
     Ok(())
 }

backend/src/services/rate_limiter.rs

@@ -17,13 +17,14 @@ impl RateLimiter {
         }
     }
 
-    /// Returns `true` if the request is allowed, `false` if rate-limited.
-    pub fn check(&self, key: impl Into<String>, max: usize, window: Duration) -> bool {
-        self.check_with_retry(key, max, window).is_ok()
-    }
-
     /// Returns `Ok(())` if allowed, `Err(retry_after_secs)` if rate-limited.
     /// `retry_after_secs` is how long until the oldest slot in the window expires.
+    ///
+    /// This is deliberately the ONLY entry point. There used to be a `check()` wrapper
+    /// returning a plain bool, and 7 of the 8 call sites used it and then hard-coded
+    /// `None` for the response's `Retry-After` — so a throttled client was told to back
+    /// off but never for how long. Forcing every caller through the `Result` makes the
+    /// retry delay impossible to discard by accident.
     pub fn check_with_retry(
         &self,
         key: impl Into<String>,
@@ -84,6 +85,11 @@ impl RateLimiter {
 /// appends is the real client. A client can prepend arbitrary spoofed values to
 /// the left of XFF to dodge throttles — those are ignored here. This assumes
 /// exactly one trusted proxy (Caddy); revisit if that changes.
+///
+/// Pass the peer address as `fallback`, never a constant. Every caller used to pass
+/// the literal `"unknown"`, so any request that arrived without XFF — i.e. anything
+/// reaching the app directly rather than through Caddy — shared ONE bucket with every
+/// other such request, turning the limiter into a self-inflicted global throttle.
 pub fn client_ip(headers: &axum::http::HeaderMap, fallback: &str) -> String {
     headers
         .get("x-forwarded-for")
@@ -104,29 +110,35 @@ mod tests {
     #[test]
     fn allows_up_to_max_then_blocks() {
         let rl = RateLimiter::new();
-        assert!(rl.check("k", 3, MIN));
-        assert!(rl.check("k", 3, MIN));
-        assert!(rl.check("k", 3, MIN));
-        assert!(!rl.check("k", 3, MIN), "the 4th request must be blocked");
+        assert!(rl.check_with_retry("k", 3, MIN).is_ok());
+        assert!(rl.check_with_retry("k", 3, MIN).is_ok());
+        assert!(rl.check_with_retry("k", 3, MIN).is_ok());
+        assert!(
+            rl.check_with_retry("k", 3, MIN).is_err(),
+            "the 4th request must be blocked"
+        );
     }
 
     #[test]
     fn keys_are_independent() {
         let rl = RateLimiter::new();
-        assert!(rl.check("a", 1, MIN));
-        assert!(!rl.check("a", 1, MIN));
-        assert!(rl.check("b", 1, MIN), "a different key has its own window");
+        assert!(rl.check_with_retry("a", 1, MIN).is_ok());
+        assert!(rl.check_with_retry("a", 1, MIN).is_err());
+        assert!(
+            rl.check_with_retry("b", 1, MIN).is_ok(),
+            "a different key has its own window"
+        );
     }
 
     #[test]
     fn window_slides_and_allows_again_after_expiry() {
         let rl = RateLimiter::new();
         let w = Duration::from_millis(40);
-        assert!(rl.check("k", 1, w));
-        assert!(!rl.check("k", 1, w));
+        assert!(rl.check_with_retry("k", 1, w).is_ok());
+        assert!(rl.check_with_retry("k", 1, w).is_err());
         std::thread::sleep(Duration::from_millis(55));
         assert!(
-            rl.check("k", 1, w),
+            rl.check_with_retry("k", 1, w).is_ok(),
             "the slot should expire once the window passes"
         );
     }
@@ -191,10 +203,13 @@ mod tests {
     #[test]
     fn clear_resets_every_window() {
         let rl = RateLimiter::new();
-        assert!(rl.check("k", 1, MIN));
-        assert!(!rl.check("k", 1, MIN));
+        assert!(rl.check_with_retry("k", 1, MIN).is_ok());
+        assert!(rl.check_with_retry("k", 1, MIN).is_err());
         rl.clear();
-        assert!(rl.check("k", 1, MIN), "clear() must free the window");
+        assert!(
+            rl.check_with_retry("k", 1, MIN).is_ok(),
+            "clear() must free the window"
+        );
     }
 
     /// `prune()` is a memory-leak guard: without it a long-lived process keeps one HashMap
@@ -216,7 +231,7 @@ mod tests {
             .insert("stale".to_string(), vec![ancient]);
 
         // ...alongside a key that is still inside its window.
-        assert!(rl.check("live", 5, MIN));
+        assert!(rl.check_with_retry("live", 5, MIN).is_ok());
         assert_eq!(rl.windows.lock().unwrap().len(), 2);
 
         rl.prune();
@@ -239,13 +254,13 @@ mod tests {
         // prune() dropped live keys, every background sweep would hand attackers a fresh
         // budget.
         let rl = RateLimiter::new();
-        assert!(rl.check("k", 1, MIN));
-        assert!(!rl.check("k", 1, MIN));
+        assert!(rl.check_with_retry("k", 1, MIN).is_ok());
+        assert!(rl.check_with_retry("k", 1, MIN).is_err());
 
         rl.prune();
 
         assert!(
-            !rl.check("k", 1, MIN),
+            rl.check_with_retry("k", 1, MIN).is_err(),
             "prune() must not clear a window that is still active"
         );
     }

e2e/specs/01-auth/join.spec.ts

@@ -13,7 +13,11 @@ test.describe('Auth — join flow', () => {
     const join = new JoinPage(page);
     await join.goto();
 
-    await expect(page.getByRole('heading', { name: 'Willkommen!' })).toBeVisible();
+    // The join form's landing state. There is no "Willkommen!" heading — the wedding
+    // redesign (f243bfe) split it into a "Willkommen bei" lead-in plus the event name as
+    // the <h1>, and this assertion was never updated, so it had been failing since.
+    // Anchor on the testid the markup provides rather than on copy.
+    await expect(page.getByTestId('join-event-name')).toBeVisible();
 
     const { pin } = await join.joinAs('Alice');
     expect(pin).toMatch(/^\d{4}$/);

e2e/specs/01-auth/rate-limit-shared-nat.spec.ts

@@ -0,0 +1,144 @@
+/**
+ * Regression guard — the door must not close on a venue behind one NAT.
+ *
+ * `/join` was throttled 5 per 60s keyed purely on the client IP. Every guest at a venue
+ * arrives from the same public IP (that is what a NAT is), so the whole party shared one
+ * bucket: 12 guests scanning the QR code within a few seconds meant 5 got in and 7 were
+ * turned away — with no Retry-After to tell them when to try again. `/feed` (60/min) and
+ * `/export` (3/DAY) had the identical defect.
+ *
+ * These ran green for the same structural reason every time: the e2e reseed forces every
+ * limiter toggle OFF before each test, so nothing here was ever exercised. Enable them
+ * explicitly, exactly as 02-upload/rate-limit does.
+ */
+import { test, expect } from '../../fixtures/test';
+import { BASE } from '../../helpers/env';
+
+test.describe('Rate limits — guests behind a shared NAT', () => {
+  test('a dozen guests can all join from one IP, and 429s carry Retry-After', async ({
+    api,
+    adminToken,
+  }) => {
+    await api.patchConfig(adminToken, {
+      rate_limits_enabled: 'true',
+      join_rate_enabled: 'true',
+    });
+
+    // Twelve DISTINCT guests, same source IP — the arrival burst at a real party.
+    const names = Array.from({ length: 12 }, (_, i) => `NatGuest${i}`);
+    const results = await Promise.all(
+      names.map((display_name) =>
+        fetch(`${BASE}/api/v1/join`, {
+          method: 'POST',
+          headers: { 'Content-Type': 'application/json' },
+          body: JSON.stringify({ display_name }),
+        })
+      )
+    );
+
+    const rejected = results.filter((r) => r.status === 429);
+    expect(
+      rejected.length,
+      `all 12 guests must get in from one IP; ${rejected.length} were turned away`
+    ).toBe(0);
+    expect(results.every((r) => r.status === 201)).toBe(true);
+  });
+
+  test('one guest retrying their own name is still throttled, and told for how long', async ({
+    api,
+    adminToken,
+  }) => {
+    // The per-name bucket must still bite — otherwise the NAT fix would have simply
+    // removed the anti-spam limit rather than re-keyed it.
+    await api.patchConfig(adminToken, {
+      rate_limits_enabled: 'true',
+      join_rate_enabled: 'true',
+    });
+
+    const attempt = () =>
+      fetch(`${BASE}/api/v1/join`, {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify({ display_name: 'RepeatOffender' }),
+      });
+
+    // 5 per 60s for the same (ip, name): the first succeeds (201), the next four collide
+    // with the taken name (409), and the sixth exhausts the bucket.
+    const codes: number[] = [];
+    for (let i = 0; i < 6; i++) codes.push((await attempt()).status);
+
+    expect(codes[0], 'the first join should succeed').toBe(201);
+    expect(codes.at(-1), 'the 6th attempt on one name must be throttled').toBe(429);
+
+    const throttled = await attempt();
+    expect(throttled.status).toBe(429);
+    const retryAfter = throttled.headers.get('retry-after');
+    expect(retryAfter, '429 must tell the client when to come back').toBeTruthy();
+    expect(Number(retryAfter)).toBeGreaterThan(0);
+    expect(Number(retryAfter)).toBeLessThanOrEqual(60);
+  });
+
+  test('the feed limit is per-user, not per-IP', async ({ api, adminToken, guest }) => {
+    // Two guests, one IP. With a limit of 3/min an IP key would let the first guest's
+    // three reads starve the second entirely.
+    await api.patchConfig(adminToken, {
+      rate_limits_enabled: 'true',
+      feed_rate_enabled: 'true',
+      feed_rate_per_min: '3',
+    });
+
+    const a = await guest('FeedHog');
+    const b = await guest('FeedVictim');
+    const read = (jwt: string) =>
+      fetch(`${BASE}/api/v1/feed`, { headers: { Authorization: `Bearer ${jwt}` } });
+
+    // Guest A burns their whole allowance.
+    for (let i = 0; i < 3; i++) expect((await read(a.jwt)).status).toBe(200);
+    expect((await read(a.jwt)).status, "A's own 4th read is throttled").toBe(429);
+
+    // Guest B must be entirely unaffected.
+    expect((await read(b.jwt)).status, 'B must not inherit A’s exhausted bucket').toBe(200);
+  });
+
+  test('the export limit is per-user — one guest cannot spend the whole venue’s quota', async ({
+    api,
+    adminToken,
+    guest,
+    host,
+    db,
+  }) => {
+    // The sharpest case: 3 downloads per DAY on an IP key meant the 4th guest to fetch
+    // their keepsake was locked out until tomorrow.
+    await db.setExportReleased('e2e-test-event', true);
+    await api.patchConfig(adminToken, {
+      rate_limits_enabled: 'true',
+      export_rate_enabled: 'true',
+      export_rate_per_day: '1',
+    });
+
+    const mintAndFetch = async (jwt: string) => {
+      const res = await fetch(`${BASE}/api/v1/export/ticket`, {
+        method: 'POST',
+        headers: { Authorization: `Bearer ${jwt}` },
+      });
+      const { ticket } = await res.json();
+      return fetch(`${BASE}/api/v1/export/zip?ticket=${encodeURIComponent(ticket)}`);
+    };
+
+    const a = await guest('ExportFirst');
+    const b = await guest('ExportSecond');
+
+    // A spends their single daily allowance. The archive itself may not exist (404) —
+    // what matters is that the limiter admitted the request rather than 429ing it.
+    expect((await mintAndFetch(a.jwt)).status).not.toBe(429);
+    expect((await mintAndFetch(a.jwt)).status, 'A’s second download is throttled').toBe(429);
+
+    // B shares A's IP and must still get their keepsake.
+    expect((await mintAndFetch(b.jwt)).status, 'B must not be locked out by A’s download').not.toBe(
+      429
+    );
+
+    // And the host too, for good measure.
+    expect((await mintAndFetch(host.jwt)).status).not.toBe(429);
+  });
+});

e2e/specs/07-adversarial/ddos.spec.ts

@@ -15,7 +15,15 @@ test.describe('Adversarial — small-scale abuse', () => {
     await api.patchConfig(adminToken, { rate_limits_enabled: 'true', join_rate_enabled: 'true' });
   });
 
-  test('20 parallel /join from one IP — rate limiter catches the excess', async () => {
+  test('a /join flood from one IP is caught by the per-IP ceiling', async ({ api, adminToken }) => {
+    // This used to assert that 20 joins from one IP produced 429s under a 5/min per-IP
+    // bucket. That "protection" was the bug: at a venue every guest shares one public IP,
+    // so it turned real arriving guests away (see 01-auth/rate-limit-shared-nat). The
+    // anti-spam bucket is now per (ip, name); what remains per-IP is a loose ceiling whose
+    // job is only to bound raw volume. Squeeze the ceiling so a flood is reproducible here
+    // without firing 60+ requests.
+    await api.patchConfig(adminToken, { join_ip_rate_per_min: '5' });
+
     const requests = Array.from({ length: 20 }, (_, i) =>
       fetch(`${BASE}/api/v1/join`, {
         method: 'POST',
@@ -24,7 +32,7 @@ test.describe('Adversarial — small-scale abuse', () => {
       })
     );
     const statuses = (await Promise.all(requests)).map((r) => r.status);
-    // 5/min limit → at least some should be 429.
+    // Ceiling of 5 → the excess must be shed.
     expect(statuses.filter((s) => s === 429).length).toBeGreaterThan(0);
     // Server stays up — at least one succeeded.
     expect(statuses.some((s) => s === 201 || s === 409)).toBe(true);