Rate Limiting Library

All token-gate APIs share a Cloudflare Durable Object that tracks request volume, SIWE nonces, and quotas. The server-side helpers in dapp/app/lib/rateLimit/rateLimit.server.ts wrap that worker so every request—whether it lands on Vercel, a local dev server, or another host—pulls from the exact same counters.

The library exposes:

isRateLimitEnabled() – true only when NEXT_PUBLIC_ENABLE_STATE_WORKER=true, the state worker creds exist, and the worker client can initialize.
checkRateLimitWithNonce() – applies a per-endpoint limiter, an optional global limiter, and opportunistically returns the cached nonce for SIWE flows.
Helpers for extracting client identifiers and translating limiter metadata into HTTP headers (X-RateLimit-*, Retry-After).

Architecture Overview

Client identifier – derived from x-forwarded-for (production) or the request socket/IP (everywhere else) via getIdentifier.
Per-endpoint limiter – configuration-driven (RATE_LIMITER_CONFIGS) and enforced by the Durable Object (state:ratelimit:check action).
Global limiter – optional 200 req/hour bucket for most endpoints (token-status polling is exempt).
Nonce lookup – the same worker stores SIWE nonces; if one already exists for the identifier it is injected into the limiter response to avoid redundant writes.

Configuration


NEXT_PUBLIC_ENABLE_STATE_WORKER=true
STATE_WORKER_URL=https://ritoswap-state-worker.worker.dev/state
STATE_WORKER_API_KEY=your_shared_secret

Disable the flag locally to bypass rate limits entirely while iterating. In production, the worker must be reachable before any route can perform SIWE or rate-limited operations.

Limiter Catalog

Limiter	Limit	Window	Prefix	Purpose
`nonce`	30	60s	`rl:nonce:`	SIWE nonce generation attempts
`gateAccess`	60	60s	`rl:gate-access:`	Main gate unlock endpoint
`formSubmissionGate`	10	60s	`rl:form-submission:`	Single-use message submission endpoint
`tokenStatus`	60	60s	`rl:token-status:`	High-frequency polling for UI updates (no global limiter)
`global`	200	3600s	`rl:global:`	Catch-all protection shared across most routes

The configuration lives in RATE_LIMITER_CONFIGS and feeds both the worker payload (limit, windowSeconds) and the doc site.

Request Lifecycle

1. Identifier Extraction

getIdentifier(req) prioritizes x-forwarded-for, falls back to x-real-ip, and finally req.ip. Development requests default to 127.0.0.1 so the limiter remains stable between reloads.

2. Per-Route Check

applyLimiter(type, identifier) calls getStateClient().checkRateLimit(...). Failures (network issues, worker downtime) are logged and treated as success: true to avoid blocking the app.

3. Optional Global Check

For everything except tokenStatus, a second limiter (global) is evaluated to cap total throughput per identifier.

4. Nonce Lookup

When SIWE is enabled, the helper also tries getStateClient().getNonce(identifier) so /api/nonce can reuse the cached value without performing another worker round trip.

5. Response Headers

When a request is throttled, rateLimitResponse computes Retry-After, X-RateLimit-Limit, and X-RateLimit-Remaining and attaches them to the 429 response.

Surfacing to APIs

Routes typically integrate like this:


const result = await checkRateLimitWithNonce(request, 'gateAccess');
if (!result.success) {
  return rateLimitResponse(result, 'Rate limit exceeded');
}
// result.nonce may contain a SIWE nonce for reuse

/api/gate-access passes 'gateAccess' and leaves includeGlobal at true.
/api/token-status/[tokenId] uses 'tokenStatus' and explicitly sets includeGlobal=false to keep polling responsive.
/api/form-submission-gate uses 'formSubmissionGate' before parsing any user content, protecting the most expensive code path.

Testing & Debugging

dapp/app/lib/rateLimit/__tests__/rateLimit.server.test.ts verifies:

Rate-limit enablement gating via env + state service checks
Identifier extraction fallbacks
Per-route limiter + global limiter ordering and short-circuit behavior
Nonce passthrough when cached

For manual diagnostics, /api/debug/status responds in development with booleans indicating whether the state worker URL and API key are configured.

⚠️

Because all rate limiting, nonce storage, and quota tracking shares the same Durable Object, never expose its STATE_WORKER_API_KEY publicly. The worker authenticates every request coming from the Next.js app.