Server: add baseline security response headers - #187
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Found during a repo-wide security audit: the server sends no hardening headers at all — no CORS config (fine, no browser client), but also nothing on X-Frame-Options, X-Content-Type-Options, Referrer-Policy, or HSTS. Adds SecurityHeadersMiddleware, applying X-Frame-Options: DENY, X-Content-Type-Options: nosniff, Referrer-Policy: no-referrer, and Strict-Transport-Security to every response. Registered at `.beginning` so it wraps Vapor's default ErrorMiddleware rather than being wrapped by it — at the default `.end` position an error thrown by routing or a handler unwinds past the middleware without running its header-setting code, so 404/401/429/500 responses would ship without these headers. Caught by a test that specifically checks a 404. Not auth/token/crypto/session logic, so not gated behind the security-review rule — pure response hardening with no behavior change for the iOS client (which ignores headers it doesn't recognize). Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
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Summary
Found during a repo-wide security audit (auth surface, rate limiter, secrets, dependencies, transport/headers, authorization). The server currently sends no hardening headers on any response — no CORS config (correct: no browser client exists, so same-origin policy is the right default and adding CORS would be a regression), but also nothing on
X-Frame-Options,X-Content-Type-Options,Referrer-Policy, or HSTS.This is a JSON API consumed only by the iOS app, so these headers are second-order hardening (they matter if a response body is ever rendered by a browser — an error page, a misconfigured proxy, a future web client) rather than a direct fix for an exploitable path. Cheap, zero behavior change for the app, worth doing.
What it does
Adds
SecurityHeadersMiddleware(chess-server/Sources/App/Middleware/SecurityHeadersMiddleware.swift), applied to every response:X-Frame-Options: DENYX-Content-Type-Options: nosniffReferrer-Policy: no-referrerStrict-Transport-Security: max-age=31536000; includeSubDomainsRegistration order matters and is covered by a test. Registered at
.beginningso it wraps Vapor's defaultErrorMiddlewarerather than being wrapped by it. At the default.endposition, an error thrown by routing or a handler (a 404, a 401, a 429 from the rate limiter, a 500) unwinds straight past the middleware without running its header-setting code — I hit this myself first (testHeadersAreAlsoPresentOnErrorResponsesfailed against the naive.endregistration) and fixed it before opening this PR. Error responses are exactly the ones where these headers matter most, so this isn't a cosmetic detail.Test plan
SecurityHeadersMiddlewareTests: headers present on a normal 200 (/health) and on a 404 (/no-such-route).swift test --package-path chess-server— 91/91 pass locally (Xcode-beta toolchain).swiftformat --lintclean on the changed files.Security-sensitive?
No — this is response-header middleware, not auth/token/crypto/account-linking/session logic, so it's not gated behind CLAUDE.md rule 5's draft-until-APPROVE flow. Opened as a normal PR.