Rate limit register and unregister

docs/api.md

@@ -227,16 +227,23 @@ curl -i -X POST http://localhost:8080/api/notify \
 | 200    | `/api/health`, `/api/info`, `/api/status`, `/api/register`, `/api/unregister` |
 | 202    | `/api/notify` on parse-valid input                                            |
 | 400    | Malformed body, invalid `trade_pubkey`, invalid `platform`, empty `token`     |
-| 429    | `/api/notify` only — per-IP or per-pubkey rate limit                          |
-| 500    | `/api/notify` only — fail-closed when the per-IP key cannot be extracted      |
+| 429    | `/api/register`, `/api/unregister`, `/api/notify` rate limits                 |
+| 500    | Rate-limited endpoints fail closed when the per-IP key cannot be extracted   |
 
 ## Rate limiting
 
-Only `/api/notify` is rate-limited. Limits are per-IP and per-`trade_pubkey`; both must allow the request to pass. Defaults:
+`/api/register` and `/api/unregister` share a per-IP limit to protect the
+in-memory token store from registration churn:
+
+- Per-IP: `120/min`, burst `100`
+
+`/api/notify` has separate per-IP and per-`trade_pubkey` limits; both must allow the request to pass. Defaults:
 
 - Per-pubkey: `30/min`, burst `10` (env `NOTIFY_RATE_PER_PUBKEY_PER_MIN`)
 - Per-IP: `120/min`, burst `30` (env `NOTIFY_RATE_PER_IP_PER_MIN`)
 
-The other endpoints are intentionally not rate-limited at the HTTP layer; capacity at the edge is governed by `fly.toml` `hard_limit = 25`.
+`/api/health`, `/api/info`, and `/api/status` are intentionally not
+rate-limited at the HTTP layer; capacity at the edge is governed by
+`fly.toml` `hard_limit = 25`.
 
 See [configuration.md](./configuration.md) for the full rate-limit knob list and the `NOTIFY_TRUST_PROXY_HEADERS` flag governing trust of `Fly-Client-IP` / `X-Forwarded-For`.

docs/architecture.md

@@ -33,7 +33,7 @@ src/
 
 ### HTTP server (`actix-web`)
 
-Five always-on endpoints (`/api/health`, `/api/info`, `/api/status`, `/api/register`, `/api/unregister`) plus the rate-limited `/api/notify` resource. The `/api/notify` resource is the only endpoint wrapped by middleware: `request_id_mw` (outermost) and `per_ip_rate_limit_mw`.
+Five always-on endpoints (`/api/health`, `/api/info`, `/api/status`, `/api/register`, `/api/unregister`) plus `/api/notify`. `/api/register` and `/api/unregister` share a per-IP middleware to bound token-store churn. `/api/notify` has its own middleware stack: `request_id_mw` (outermost) and `per_ip_rate_limit_mw`.
 
 ### Nostr listener (`nostr-sdk`)
 

docs/configuration.md

@@ -85,9 +85,11 @@ To turn the filter on/off without rebuilding, flip
 | `TOKEN_TTL_HOURS`         | `48`    | Tokens older than this are evicted by the cleanup task                       |
 | `CLEANUP_INTERVAL_HOURS`  | `1`     | How often the cleanup task runs                                              |
 
-## `/api/notify` rate limiter
+## HTTP rate limiters
 
-The dual-keyed rate limiter is documented in detail in [architecture.md](./architecture.md). Defaults are tuned for the Fly.io single-machine deployment.
+The `/api/notify` dual-keyed rate limiter is documented in detail in
+[architecture.md](./architecture.md). Defaults are tuned for the Fly.io
+single-machine deployment.
 
 | Variable                                      | Default  | Description                                                                                          |
 |-----------------------------------------------|----------|------------------------------------------------------------------------------------------------------|
@@ -99,6 +101,11 @@ The dual-keyed rate limiter is documented in detail in [architecture.md](./archi
 
 Setting either of `NOTIFY_RATE_PER_PUBKEY_PER_MIN` or `NOTIFY_RATE_PER_IP_PER_MIN` to `0` causes startup to fail with a chained error message; both must be greater than zero.
 
+`/api/register` and `/api/unregister` also share a fixed per-IP limiter:
+`120/min`, burst `100`. It is intentionally separate from `/api/notify` so
+registration churn cannot consume the notify per-IP bucket, and notify traffic
+cannot disable client re-registration.
+
 ## Legacy / reserved
 
 | Variable                | Default                                                                | Description                                                                                              |

src/api/rate_limit.rs

@@ -21,6 +21,13 @@ pub type PerPubkeyLimiter = DefaultKeyedRateLimiter<String>;
 /// Per-IP keyed rate limiter type alias (D-20).
 pub type PerIpLimiter = DefaultKeyedRateLimiter<IpAddr>;
 
+/// Separate per-IP limiter for /api/register and /api/unregister.
+///
+/// Kept as a newtype so it can live next to the /api/notify per-IP limiter
+/// in Actix app_data without type collision.
+#[derive(Clone)]
+pub struct RegisterIpLimiter(pub Arc<PerIpLimiter>);
+
 /// Newtype injected into `web::Data` to gate trust of `Fly-Client-IP` and
 /// `X-Forwarded-For`. When `false`, both proxy headers are ignored and the
 /// per-IP limiter keys exclusively on `req.peer_addr()`. Default is `false`
@@ -38,6 +45,11 @@ pub const PUBKEY_BURST: u32 = 10;
 /// Per-IP burst (D-02). Not env-overridable in this phase per D-29.
 pub const IP_BURST: u32 = 30;
 
+/// Register/unregister per-IP limiter. Higher than /api/notify because normal
+/// clients can re-register on app/session churn, but still caps store spam.
+pub const REGISTER_IP_RATE_PER_MIN: u32 = 120;
+pub const REGISTER_IP_BURST: u32 = 100;
+
 /// Cleanup interval default in seconds (D-16). Override via NOTIFY_RATE_LIMIT_CLEANUP_INTERVAL_SECS.
 /// Defaults are duplicated in `Config::from_env` so this constant is currently
 /// unused at runtime; kept as the canonical reference for D-16.
@@ -165,6 +177,60 @@ pub async fn per_ip_rate_limit_mw(
     }
 }
 
+/// Per-IP middleware for /api/register and /api/unregister.
+pub async fn register_ip_rate_limit_mw(
+    req: ServiceRequest,
+    next: Next<impl MessageBody + 'static>,
+) -> Result<ServiceResponse<BoxBody>, Error> {
+    let limiter = req
+        .app_data::<web::Data<RegisterIpLimiter>>()
+        .map(|d| d.0.clone());
+
+    let limiter = match limiter {
+        Some(l) => l,
+        None => {
+            warn!("register per-ip rate-limit middleware: limiter not in app_data (wiring bug)");
+            let resp = HttpResponse::InternalServerError().json(json!({
+                "success": false,
+                "message": "internal error"
+            }));
+            return Ok(req.into_response(resp).map_into_boxed_body());
+        }
+    };
+
+    let trust_proxy_headers = req
+        .app_data::<web::Data<TrustProxyHeaders>>()
+        .map(|d| d.0)
+        .unwrap_or(false);
+
+    let ip = match extract_client_ip(&req, trust_proxy_headers) {
+        Some(ip) => ip,
+        None => {
+            let resp = HttpResponse::InternalServerError().json(json!({
+                "success": false,
+                "message": "internal error"
+            }));
+            return Ok(req.into_response(resp).map_into_boxed_body());
+        }
+    };
+
+    match limiter.check_key(&ip) {
+        Ok(()) => {
+            let res = next.call(req).await?;
+            Ok(res.map_into_boxed_body())
+        }
+        Err(not_until) => {
+            let retry_after_secs = not_until
+                .wait_time_from(DefaultClock::default().now())
+                .as_secs()
+                .max(1);
+            let resp = rate_limited_response(retry_after_secs);
+            log::debug!("register per-ip 429 retry_after={}s", retry_after_secs);
+            Ok(req.into_response(resp).map_into_boxed_body())
+        }
+    }
+}
+
 /// Soft-cap branch of the cleanup task, extracted as a sync helper so the
 /// LIMIT-06 warn-emission path is unit-testable without spawning a real
 /// `tokio::time::interval` loop.