With TRUSTED_PROXIES empty behind the reverse proxy production is
required to run behind, every login POST keyed on the proxy's address
and shared one 5/minute bucket. A stranger sending five POSTs a
minute -- 0.08 requests per second, from anywhere -- kept that bucket
permanently full, and the operator's own correct password was answered
429 indefinitely with no second administrative path.
The login POST no longer has a pre-emptive limiter. The handler
verifies credentials first and spends budget only on a FAILED attempt,
so a correct password is never throttled whatever the counters hold.
Three things follow, and are implemented together because the first is
unsafe without the other two:
- Failures are counted per (client bucket, submitted username), five
per minute, after which further failures get 429 with a Retry-After.
A successful login clears the counter, so mistyping and then
succeeding does not leave the operator throttled.
- Both key sets are capped at 1024 entries. The submitted username is
attacker-controlled, so past the first cap failures fall back to a
counter keyed on the client alone, and past both caps a failure is
answered as throttled without being recorded. Tracked state stays
under half a megabyte and does not grow with invented usernames.
- Concurrent Argon2id verifications are capped at two, a 128 MB
ceiling at 64 MB per hash, and the queue for those slots is capped
at 16 waiters. Every password-hashing endpoint takes a slot,
including the password-change endpoint, which holds one across both
its hashes. A request that waits five seconds without a slot is
answered 503, and one that arrives with the queue already full is
shed with 503 immediately rather than joining it. Bounding the wait
alone would not bound memory, and the queue depth is sized from what
a parked waiter measurably retains rather than from the 1 MB body
cap, which bounds only the raw body read. The body-cap, CSRF and
form-parsing middleware all run before the guard, so a waiter holds
its parsed form plus its request header block for the whole wait.
Measured on the pinned go1.26.1 toolchain as the HeapAlloc delta
across two GCs with 64 waiters parked in the handler: an ordinary
two-field login form retains ~0 MB, a 1 MB urlencoded body at Go's
10,000-parameter parse cap retains 2.82 MB (3.09 MB with %41
escapes), and the ~0.9 MB of headers the 1 MB header cap allows
takes it to 4.18 MB. The retained parse and the header block
dominate, not the raw body. So 16 waiters: 16 x 4.18 MB is about
67 MB of committed queue memory, and two slots drain a full 16-deep
queue in about 0.6 s, far inside the deadline. Peak commitment for
the endpoint is about 203 MB — 128 MB of Argon2id plus the 18
requests holding a parsed form, 16 queued and the 2 being hashed, at
about 75 MB. That 203 MB is live commitment, not resident size: the
Go collector lets the heap reach roughly twice the live set before
collecting, and the review measured a peak HeapAlloc of 392 MB under
18 adversarial requests, so the README says to provision on the
order of 400 MB.
An unknown username is verified against a dummy hash instead of
returning early, so a nonexistent account costs the same time as a
real one and the response cannot be used to enumerate usernames.
The password-change limiter is unchanged: RequireAuth runs ahead of
it, so only a request already carrying a valid session reaches its
bucket.
Two consequences are documented rather than fixed, because they follow
from the shape the issue asks for. Online guessing throughput rises
from 5 a minute to roughly 27 a second, about 2.3 million a day: the
credential check always precedes the counter, so the 429 is a label on
the response rather than a gate in front of the hash, and what bounds
brute force is the semaphore. And under a sustained flood the residual
exposure is a loss of login availability, not merely of latency --
above about 27 requests a second most attempts are shed with 503, so a
determined flood still denies login for as long as it runs. It costs
roughly 400x more to run, nothing accumulates, and the first attempt
after it stops succeeds. Restarting the service does not help: the
counters a restart clears are not what is saturated.
Also adds the missing test for the third bucketKey call site, where
the peer is a trusted proxy but the forwarded chain names no client.
Every existing test of that fallback uses an IPv4 proxy, where
bucketKey is the identity function, so dropping the /64 masking there
left the suite green.
README and the TRUSTED_PROXIES startup warning updated: a shared
bucket now costs precision, not the availability of the admin path.
Rate-limit keys were per-address, i.e. per /128 for IPv6. A routed /64
is the normal residential and mobile allocation, so a client rotated
source addresses inside its own prefix and minted a fresh bucket per
request — evading every limiter at the network layer, with no spoofing
and nothing to detect. #88 closed the header half of this control; this
is the network half.
IPv6 now keys on the /64, IPv4 on the full address, via stdlib
net/netip. IPv4-mapped form is unmapped rather than masked, so clients
behind a mapping proxy do not collapse into one bucket.
Independently reviewed twice. The first round found the trusted-proxy
forwarded path — the one carrying production traffic — had no coverage
at all, so a silent revert there was undetectable; that is now pinned.
The reviewer confirmed both branches are independently mutation-tested:
reverting either the direct-peer return or the forwarded return alone
fails only that branch's tests. The 18-site test-constant refactor was
verified byte-identical against next, with no pre-existing assertion
changed.
Known remaining coverage gap, judged not a defect: the fallback when the
peer is trusted but the forwarded address does not parse has no test.
Only operator-controlled addresses inside TRUSTED_PROXIES reach it, they
already share the proxy's single bucket, and masking there can only
merge operator proxies — fail-closed, nothing attacker-controlled.
check / check (push) Superseded by a newer commit; never tested
The receiver limiter keyed on the request path, and /webhook/{uuid} matches any single segment, so a client minted a fresh bucket per invented path and had unlimited aggregate rate against the only unauthenticated endpoint. An outer limiter keyed on the client address alone now bounds that, chained in front of the unchanged per-entrypoint limiter. Its rejections log at DEBUG without the path, and the README states what each limit does and does not bound.
check / check (push) Superseded by a newer commit; never tested
forwardedClientAddr now walks the header values in reverse with strings.LastIndexByte instead of joining and splitting, so allocation is bounded by the 64-hop cap rather than by header length: 1.6 MB per call becomes 16 bytes for a 1 MB chain. Semantics are unchanged, verified by differential testing against the previous implementation.
The walk now keeps only the rightmost 64 hops, so an attacker-supplied chain cannot burn unbounded CPU in the rate-limit key function. Running off the end of the truncated slice falls back to the peer address, the same fail-closed direction the rest of the function takes. Also corrects the unparseable-RemoteAddr comment, which overclaimed about Unix-socket peers.
All three rate limiters (receiver, login, password change) now key on the connection's own address unless the direct peer is inside the new TRUSTED_PROXIES CIDR list, in which case X-Forwarded-For is walked right to left for the first non-proxy hop. Default is the empty list, which trusts nothing. A set-but-unparseable value aborts startup.
The receiver was the one unauthenticated, internet-facing endpoint with no
rate limit, so a misbehaving or hostile sender could flood a webhook
without bound. RECEIVER_RATE_LIMIT (default 120/min) now caps it, keyed on
client IP plus entrypoint path so one entrypoint cannot exhaust another's
budget. Over-limit requests get 429 with Retry-After.
The limiter deliberately does not reuse postRateLimit: that helper is
POST-only and keys on IP alone, whereas the receiver must count every
method. A test locks that property in.
Config parsing follows the fail-loudly idiom: a set-but-unparseable or
non-positive value aborts startup rather than falling back to the default.
Known limitation, tracked in #88: the key still trusts forwarded headers
unconditionally, so the limit is evadable by rotating X-Forwarded-For until
trusted-proxy gating lands.
check / check (push) Superseded by a newer commit; never tested
Adds an authenticated, CSRF-protected flow that lets a user change their own password from the profile page.
## Route
- New `POST /password` under the `/user/{username}` group in `setupUserRoutes` (`internal/server/routes.go`). That group already applies `CSRF`, `NoCache`, and `RequireAuth`, so the new endpoint inherits all three.
## Handler (`internal/handlers/profile.go`)
- `HandlePasswordChange` enforces own-user access: the `{username}` path parameter must equal the session username (same 403 rule `HandleProfile` uses). This check plus the session lookup is factored into a shared `profileOwnerOrDeny` helper now used by both handlers.
- Parses `current_password`, `new_password`, and `confirm_password` (body size limited via `http.MaxBytesReader`).
- Verifies the current password with `database.VerifyPassword` against the stored hash.
- Requires the new password to be non-empty and equal to the confirmation.
- Hashes the new password with `database.HashPassword` — the same Argon2id helper used to bootstrap the admin user — and persists it on the user row. No new crypto.
- Re-renders the profile page with a clear success or error message. Wrong current password, empty new password, and mismatched confirmation are each rejected with their own message and leave the stored hash unchanged.
## Template (`templates/profile.html`)
- Adds a "Change Password" card with current / new / confirm password fields plus the hidden `csrf_token` (matching the login form's CSRF embedding).
- Renders success/error alerts using the existing `alert-success` / `alert-error` styles. No new CSS classes, so no Tailwind rebuild is required.
## Tests (`internal/handlers/profile_test.go`)
- `TestHandlePasswordChange_Success`: seeds a user, posts a valid change, asserts success message and that the stored hash changed and verifies against the new password.
- `TestHandlePasswordChange_WrongCurrentPassword`: posts a wrong current password, asserts the rejection message and that the stored hash is unchanged.
Validated with `docker build .` (fmt-check, lint, test, build) — exit 0.
Closes#65
Co-authored-by: sneak <sneak@sneak.berlin>
Co-authored-by: Jeffrey Paul <sneak@noreply.example.org>
Reviewed-on: #83
Co-authored-by: clawbot <clawbot@noreply.example.org>
Co-committed-by: clawbot <clawbot@noreply.example.org>
Closes [issue #50](#50)
## Summary
Refactors the Dockerfile to use a separate lint stage with a pinned golangci-lint Docker image, following the pattern used by [sneak/pixa](https://git.eeqj.de/sneak/pixa). This replaces the previous approach of installing golangci-lint via curl in the builder stage.
## Changes
### Dockerfile
- **New `lint` stage** using `golangci/golangci-lint:v2.11.3` (Debian-based, pinned by sha256 digest) as a separate build stage
- **Builder stage** depends on lint via `COPY --from=lint /src/go.sum /dev/null` — build won't proceed unless linting passes
- **Go bumped** from 1.24 to 1.26.1 (`golang:1.26.1-bookworm`, pinned by sha256)
- **golangci-lint bumped** from v1.64.8 to v2.11.3
- All three Docker images (golangci-lint, golang, alpine) pinned by sha256 digest
- Debian-based golangci-lint image used (not Alpine) because mattn/go-sqlite3 CGO does not compile on musl (off64_t)
### Linter Config (.golangci.yml)
- Migrated from v1 to v2 format (`version: "2"` added)
- Removed linters no longer available in v2: `gofmt` (handled by `make fmt-check`), `gosimple` (merged into `staticcheck`), `typecheck` (always-on in v2)
- Same set of linters enabled — no rules weakened
### Code Fixes (all lint issues from v2 upgrade)
- Added package comments to all packages
- Added doc comments to all exported types, functions, and methods
- Fixed unchecked errors flagged by `errcheck` (sqlDB.Close, os.Setenv in tests, resp.Body.Close, fmt.Fprint)
- Fixed unused parameters flagged by `revive` (renamed to `_`)
- Fixed `gosec` G120 warnings: added `http.MaxBytesReader` before `r.ParseForm()` calls
- Fixed `staticcheck` QF1012: replaced `WriteString(fmt.Sprintf(...))` with `fmt.Fprintf`
- Fixed `staticcheck` QF1003: converted if/else chain to tagged switch
- Renamed `DeliveryTask` → `Task` to avoid package stutter (`delivery.Task` instead of `delivery.DeliveryTask`)
- Renamed shadowed builtin `max` parameter to `upperBound` in `cryptoRandInt`
- Used `t.Setenv` instead of `os.Setenv` in tests (auto-restores)
### README.md
- Updated version requirements: Go 1.26+, golangci-lint v2.11+
- Updated Dockerfile description in project structure
## Verification
`docker build .` passes cleanly — formatting check, linting, all tests, and build all succeed.
Co-authored-by: clawbot <clawbot@noreply.git.eeqj.de>
Reviewed-on: #55
Co-authored-by: clawbot <clawbot@noreply.example.org>
Co-committed-by: clawbot <clawbot@noreply.example.org>
