fix(faucet): rate-limit the faucet to prevent testnet drain - #2
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POST /faucet had no rate limiting, so any caller could repeatedly drain the funded testnet faucet account. Add an in-memory cooldown limiter (std only, no new dependency) keyed by: - client IP: 30s window (anti-spam), read via realip_remote_addr so it uses X-Forwarded-For behind the nginx reverse proxy, not the proxy IP; - recipient address: 1h window (anti-refund drain), case-insensitive. Rejected requests return 429 with a Retry-After header and do not record a hit, so a blocked caller cannot push its own cooldown forward. The limiter is created once and shared across all Actix workers (a per-worker instance would multiply the limit by the worker count). The map self-prunes to the longest window to stay bounded. Cooldowns are fixed constants for now (marked with ponytail: comments as the tuning knob). Captcha/PoW and per-period amount caps are out of scope: an attacker rotating both IP and address still bypasses a keyless faucet. Adds unit tests for the cooldown and case-insensitivity behavior. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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What
Rate-limits
POST /faucetto stop testnet faucet drain. Previously anycaller could hit the endpoint repeatedly and drain the funded faucet account.
How
In-memory cooldown limiter (
src/hub/rate_limit.rs),stdonly — no new dependency:realip_remote_addr()so itreads
X-Forwarded-For/X-Real-IPbehind the nginx reverse proxy, not the proxy IP.Rejected requests return
429 Too Many Requests+Retry-After. A rejected hit isnot recorded, so a blocked caller can't push its own cooldown forward. The limiter
is instantiated once and shared across all Actix workers (per-worker would multiply the
limit by worker count). The map self-prunes to the longest window.
Out of scope
ponytail:comments).still bypasses a keyless faucet.
Testing
cargo test— 21 passed (19 existing + 2 new: cooldown + case-insensitivity).