Test a pending delivery whose target is found only on lookup

When the batch's target map lacks a delivery's target, as it does
for every delivery when the batch query fails, sendRecoveredDeliveries
looks the target up on its own. The new test hands it an empty map
and checks the healthy delivery is queued once, with its real target
id and type.

Model: opus-5-5

README.md

@@ -147,7 +147,7 @@ TTY detection, and security headers are always applied.
 | `RETENTION_SWEEP_INTERVAL` | How often the retention reaper and archive sweeper run (Go duration, must be positive) | `1h` |
 | `SESSION_IDLE_TIMEOUT`  | Idle session timeout (Go duration)  | `24h`    |
 | `RECEIVER_RATE_LIMIT`   | Receiver requests/minute per IP per entrypoint (10x that per IP across the route) | `120` |
-| `TRUSTED_PROXIES`       | CIDRs whose forwarded headers are trusted. A set value replaces the default. Under the default, any client with a private address, whether it connects directly or through the proxy, can choose its own rate-limit key by sending its own `X-Forwarded-For`; if any clients have private addresses, set it to the proxy's address alone. See [Trusted proxies](#trusted-proxies) | `10.0.0.0/8,172.16.0.0/12,192.168.0.0/16` (RFC 1918) |
+| `TRUSTED_PROXIES`       | CIDRs whose forwarded headers are trusted (unset: all clients behind a proxy share one rate-limit bucket; a correct login password is never throttled either way) | `""` (none) |
 | `ALLOWED_EGRESS_CIDRS`  | CIDRs that delivery targets may reach despite the SSRF blocklist. Read [Allowing egress to your own network](#allowing-egress-to-your-own-network) before setting it | `""` (none) |
 
 #### Allowing egress to your own network
@@ -157,11 +157,6 @@ private and reserved ranges — RFC 1918, loopback, CGNAT, link-local and
 the rest — are refused, which stops a target from being used to make
 webhooker probe the network it sits in.
 
-Besides the private and reserved ranges, the default blocklist refuses
-public cloud metadata addresses: currently only `168.63.129.16`, Azure's
-WireServer, which serves an Azure VM its credentials. Because it is a
-public address, listing it in `ALLOWED_EGRESS_CIDRS` reopens it.
-
 That default is also inconvenient for the thing webhooker is mostly
 for: taking a public webhook and forwarding it to something on your own
 network. A container on the same Docker network, a box on `10.x`, a
@@ -200,16 +195,15 @@ Two things this setting cannot do:
   the list is always an allowlist; an empty list (the default) means
   every private and reserved range stays refused. Note that
   `0.0.0.0/0` gets you most of the way there anyway, per above.
-- **It cannot open link-local, or a cloud metadata endpoint at a
+- **It cannot open link-local, or a cloud metadata endpoint that
-  non-public address that discloses credentials or user data.** An
+  discloses credentials or user data.** An address is on the list below
-  address is on the list below when it is not a public address and both
+  when both of these hold: the provider fixes it, so it cannot collide
-  of these hold: the provider fixes it, so it cannot collide with
+  with anything you run; and reaching it hands out credentials, user
-  anything you run; and reaching it hands out credentials, user data or
+  data or bootstrap material. Those stay blocked no matter what you
-  bootstrap material. Those stay blocked no matter what you list,
+  list, including when you list them outright or list a supernet such
-  including when you list them outright or list a supernet such as
+  as `0.0.0.0/0`, `::/0`, `fd00::/8` or `100.64.0.0/10`. Treat this as
-  `0.0.0.0/0`, `::/0`, `fd00::/8` or `100.64.0.0/10`. Treat this as best
+  best effort rather than a guarantee — it is a hand-maintained list
-  effort rather than a guarantee — it is a hand-maintained list and the
+  and the caveat below the table applies:
-  caveat below the table applies:
 
   | Blocked unconditionally | What it is |
   | ----------------------- | ---------- |
@@ -248,8 +242,7 @@ Two things this setting cannot do:
   encodings, which the default blocklist does not match. A publicly
   routable metadata address is not listed here, because nothing on this
   list can be reopened and blocking one that way would leave you no
-  escape hatch at all; Azure's `168.63.129.16` is refused by the default
+  escape hatch at all.
-  blocklist instead, as described above.
 
   This list is not exhaustive of every cloud's metadata address — if
   yours is not here, do not allowlist the block that contains it.
@@ -379,48 +372,41 @@ unlocked.
 `TRUSTED_PROXIES` is a comma-separated list of CIDR blocks (a bare
 address such as `192.168.1.7` is accepted and treated as a single
 host), for example `192.168.1.7, 2001:db8::5`. It decides whose
-`X-Forwarded-For` header the rate limiters believe, so it should cover
+`X-Forwarded-For` header the rate limiters believe, so it should name
-the addresses of your reverse proxies.
+the addresses of your reverse proxies and nothing else.
 
 `X-Forwarded-For` is honoured **only** when the connecting peer is
 inside one of these blocks; for every other peer the client identity is
-the connection's own address and the header is ignored. Unset (or
+the connection's own address and the header is ignored. The default is
-empty), the list is the RFC 1918 private ranges: `10.0.0.0/8`,
+the empty list, which trusts nobody — anything else would let any
-`172.16.0.0/12` and `192.168.0.0/16`. That covers a reverse proxy
+client pick its own rate limit bucket, minting a fresh one per request
-reaching webhooker over a Docker network or a private LAN without
+or draining someone else's. Set it to the address of your reverse
-anything set. A set value replaces the default entirely. A set but
+proxy, and to nothing wider. A set but unparseable value aborts
-unparseable value aborts startup.
+startup.
 
-Trusting those ranges has two consequences for clients with private
+That default is safe against forged headers, but leaving it unset in
-addresses:
+production has a cost you must know about. Production runs behind a
-
+TLS-terminating reverse proxy, so with `TRUSTED_PROXIES` unset every
-- Any such client, whether it connects directly or through the proxy,
+request keys on the proxy's own address and all clients share a single
-  can choose its own rate-limit key by sending its own
-  `X-Forwarded-For`. A direct client's header is walked because the
-  client is itself trusted; behind the proxy, the client's own address
-  is skipped as a trusted hop when the chain is walked (below), so the
-  entry it wrote is taken as the client. If any of your clients have
-  private addresses, you must set `TRUSTED_PROXIES` to the proxy's
-  address alone.
-- A client behind the proxy that sends no `X-Forwarded-For` of its own
-  shares the proxy's bucket, because its own address is skipped too.
-  Setting the list to the proxy's address alone gives each its own
-  bucket.
-
-A proxy the list does not cover, such as nginx on the same host
-reaching webhooker over loopback, is not trusted: every request through
-it keys on the proxy's own address and all clients share a single
 bucket per limit. The receiver limits become service-wide ceilings,
 and the login endpoint's failure counting collapses onto one key, so a
 stranger's wrong passwords throttle every other client's wrong
-passwords. Set `TRUSTED_PROXIES` to that proxy's address to restore
+passwords.
-per-client buckets.
 
 What it cannot do is lock the operator out. The login endpoint
 verifies credentials **before** it consults any limit and charges only
 failures, so a correct password is never throttled no matter how full
 the bucket is. See [Rate Limiting](#rate-limiting).
 
+The remedy is to set `TRUSTED_PROXIES` to your reverse proxy's
+address, which restores per-client buckets. webhooker logs a warning
+at startup whenever `TRUSTED_PROXIES` is empty, in every environment,
+because behind a proxy every client shares one bucket in `dev` and
+`prod` alike. The warning is informational when nothing proxies to the
+process: with no proxy in front, the peer address is the client's own
+and the buckets are already per-client. See
+[Rate Limiting](#rate-limiting) for what each limit shares.
+
 `X-Real-IP` and `True-Client-IP` are **never** read, from any peer.
 Reverse proxies append to `X-Forwarded-For` but forward other client
 headers verbatim, so a single-valued header is client-controlled even
@@ -442,14 +428,14 @@ Two operator requirements follow:
   (nginx `$proxy_add_x_forwarded_for`, HAProxy `option forwardfor`,
   Caddy and AWS ALB by default), and must append a bare address with
   no port.
-- Keep clients out of the list. Any address inside `TRUSTED_PROXIES`
+- List proxy hosts **only**. Any address inside `TRUSTED_PROXIES`
   chooses its own rate-limit key: its `X-Forwarded-For` is walked, so
   it can name a different address on every request to get a fresh
   bucket each time, or name another client's address to drain that
-  client's bucket. A block that also covers clients — the default, on
+  client's bucket. Never list a block that also covers clients — a
-  a network where clients have private addresses — makes all three
+  broad `10.0.0.0/8` on a network where clients live in the same range
-  limits, including the unauthenticated webhook receiver, silently
+  makes all three limits, including the unauthenticated webhook
-  bypassable by every client in the block.
+  receiver, silently bypassable by every client in the block.
 
 #### Sessions
 
@@ -771,16 +757,10 @@ repository's `Dockerfile` and runs it. The app needs:
 
 - **Environment variables:**
     - `WEBHOOKER_ENVIRONMENT=prod`
-    - `TRUSTED_PROXIES`: Docker networks use private addresses, so the
+    - `TRUSTED_PROXIES`: your reverse proxy's address on that Docker
-      default covers your reverse proxy on that network. Under the
+      network. The `remoteIP` field of the `http request` log line for a
-      default, any client with a private address, whether it connects
+      request that came through the proxy shows it; the health check's
-      directly or through the proxy, can choose its own rate-limit key
+      own lines show `::1`. See [Trusted proxies](#trusted-proxies).
-      by sending its own `X-Forwarded-For`. If any clients have private
-      addresses, or the network's addresses are outside the RFC 1918
-      ranges, set it to the proxy's address there. The `remoteIP` field
-      of the `http request` log line for a request that came through
-      the proxy shows it; the health check's own lines show `::1`. See
-      [Trusted proxies](#trusted-proxies).
     - Leave `BIND_ADDRESS` and `DATA_DIR` unset: the image sets
       `BIND_ADDRESS` to `0.0.0.0`, and `DATA_DIR` defaults to
       `/var/lib/webhooker`.
@@ -843,14 +823,12 @@ reports.
    behind a proxy means the `X-Forwarded-Proto` header. The block below
    sets it; without it every request is read as plaintext and cookies
    ship without `Secure`. See [Configuration](#configuration).
-3. **Make sure `TRUSTED_PROXIES` covers the proxy's address.** Unset,
+3. **Set `TRUSTED_PROXIES` to the proxy's address.** Unset, every rate
-   it covers the RFC 1918 private ranges, so a proxy on a Docker
+   limiter keys on the connecting peer, which behind a proxy is the
-   network or a private LAN is covered and one on loopback is not. For
+   proxy on every request: all clients collapse into one global bucket
-   a proxy it does not cover, every rate limiter keys on the connecting
+   per limit and the receiver's per-IP limits become service-wide
-   peer, which is the proxy on every request: all clients collapse into
+   ceilings. See [Trusted proxies](#trusted-proxies). List the proxy
-   one global bucket per limit and the receiver's per-IP limits become
+   and nothing else.
-   service-wide ceilings. See [Trusted proxies](#trusted-proxies). If
-   any clients have private addresses, list the proxy and nothing else.
 4. **Send `Host` as `$http_host`, not `$host`.** `$host` strips the
    port. webhooker's Origin/Referer check compares against the host it
    was given, so on any port other than 443 `$host` makes every form
@@ -990,10 +968,15 @@ scratch file**: it holds committed transactions that are not yet in the
 have no readable schema at all. `-shm` is regenerable, but there is no
 reason to separate the two — copy the directory and you have them.
 
-A clean shutdown closes every database, which checkpoints and removes
+A clean shutdown closes `webhooker.db` and every `events-*.db`, which
-its sidecars; a killed or crashed instance leaves them, and they must be
+checkpoints and removes their sidecars; a killed or crashed instance
-carried with the `.db`. An archive the service has not opened since a
+leaves them, and they must be carried with the `.db`. **Archive
-crash keeps that crash's sidecars, even across a later clean stop.
+databases are different**: their handle is not closed at shutdown, so
+`archive-*.db-wal` and `-shm` normally survive a clean stop and the
+`-wal` can hold every row the archive has. Measured on a stopped
+instance: `archive-….db` 4096 bytes with no table, its `-wal` 157 KB
+holding all 8 archived events. Copying `DATA_DIR` in full is what makes
+this a non-issue; copying `.db` files out of it by name is not.
 
 Configuration is **not** in `DATA_DIR` — it comes from the environment
 and from a `.env` file read out of the process working directory. Back
@@ -1068,9 +1051,10 @@ The file becomes self-contained again when the handle closes, which
 happens on the next write past the debounce window, when the connection
 pool retires the idle connection (about a minute after the last write),
 or at the idle archive sweep — measured, the same file was a complete
-20 KB `.db` with no sidecars about a minute after its last write. A
+20 KB `.db` with no sidecars about a minute after its last write.
-clean stop closes it too. So either move `archive-{uuid}.db` together
+Shutdown is **not** on that list: the archive handle is not closed when
-with any `-wal`/`-shm` beside it, or wait until there are none.
+the service stops. So either move `archive-{uuid}.db` together with any
+`-wal`/`-shm` beside it, or wait until there are none.
 
 ### Restore
 
@@ -1089,10 +1073,12 @@ with any `-wal`/`-shm` beside it, or wait until there are none.
    They are part of the database, and dropping a `-wal` silently
    discards every transaction it still holds. An `.backup` set will not
    contain any: it writes a single consolidated file per database. A
-   stop-and-copy set normally has none, because a clean stop closes
+   stop-and-copy set has none for `webhooker.db` or the `events-*.db`,
-   every database and checkpoints its sidecars away; the exception is an
+   because a clean stop closes those and checkpoints their sidecars
-   archive not opened since a crash. A copy salvaged from a crashed
+   away — but it will normally have them for `archive-*.db`, whose
-   instance has them for everything, and needs all of them.
+   handle stays open across shutdown, and those carry the archive's
+   rows. A copy salvaged from a crashed instance has them for
+   everything, and needs all of them.
 
 4. **Fix ownership.** The container runs as the non-root `webhooker`
    user, UID 1000 / GID 1000. Restored files must be owned by (or
@@ -1411,11 +1397,10 @@ It uses:
 - **[go-chi/httprate](https://github.com/go-chi/httprate)** for
   sliding-window rate limiting of the password-change and webhook
   receiver endpoints. The bucket is per client IP only when
-  `TRUSTED_PROXIES` covers the reverse proxy (by default it covers the
+  `TRUSTED_PROXIES` names the reverse proxy; unset, every client
-  RFC 1918 private ranges); otherwise every client behind that proxy
+  behind that proxy shares one bucket per limit. The login endpoint
-  shares one bucket per limit. The login endpoint counts failed
+  counts failed attempts itself instead, so that a correct password is
-  attempts itself instead, so that a correct password is never
+  never throttled (see [Rate Limiting](#rate-limiting))
-  throttled (see [Rate Limiting](#rate-limiting))
 - **[Prometheus](https://prometheus.io)** for metrics, served at
   `/metrics` behind basic auth
 - **[Sentry](https://sentry.io)** for optional error reporting
@@ -2596,30 +2581,30 @@ let one subscriber rotate source addresses and mint a fresh bucket per
 request, evading these limits at the network layer without spoofing
 anything; the cost is that distinct clients inside one `/64` share a
 bucket. IPv4-mapped addresses (`::ffff:1.2.3.4`) key as the IPv4 address
-they carry. See [Trusted proxies](#trusted-proxies). When that variable
+they carry. See [Trusted proxies](#trusted-proxies). Deployed without that
-does not cover the reverse proxy, a client behind it shares one bucket
+variable set, a client behind a reverse proxy shares one bucket with
-with every other client behind the same proxy. Set `TRUSTED_PROXIES` to
+every other client behind the same proxy. Set `TRUSTED_PROXIES` to the
-the proxy's address to get per-client limits back. What the shared bucket
+proxy's address to get per-client limits back. What the shared bucket
 costs is not the same for every limiter, and the two cases pull in
 opposite directions:
 
 - For the **receiver** limits it costs throughput, which is the safe
   direction to be wrong in: sharing can only make a limit bind sooner,
   never let a sender past it. It matters more for the aggregate limit
-  than for the per-entrypoint one: when `TRUSTED_PROXIES` does not
+  than for the per-entrypoint one: with `TRUSTED_PROXIES` unset behind
-  cover the reverse proxy a production deployment is required to run
+  the reverse proxy a production deployment is required to run behind,
-  behind, every request keys on the proxy, so the aggregate limit
+  every request keys on the proxy, so the aggregate limit becomes a
-  becomes a service-wide ceiling of 1200 requests per minute across all
+  service-wide ceiling of 1200 requests per minute across all senders
-  senders and all entrypoints, where the per-entrypoint limit's
+  and all entrypoints, where the per-entrypoint limit's capacity still
-  capacity still grows with the number of entrypoints. Any deployment
+  grows with the number of entrypoints. Any deployment with more than a
-  with more than a handful of busy entrypoints must make sure
+  handful of busy entrypoints must set `TRUSTED_PROXIES`.
-  `TRUSTED_PROXIES` covers its proxy.
 - For the **login and password-change** limits it costs precision, not
   availability. Login failures from every client land in one counter,
   so a stranger's wrong passwords make the operator's own wrong
   passwords answer `429` sooner; the operator's _correct_ password is
   never affected, because it is never counted. Production deployments
-  should still make sure `TRUSTED_PROXIES` covers their proxy.
+  should still set `TRUSTED_PROXIES`; webhooker warns at startup
+  whenever it is empty, in any environment.
 
 #### The login endpoint
 
@@ -2722,10 +2707,8 @@ re-fills both verification slots on its first two requests. The
 remedies are to block the source at the reverse proxy, or to
 rate-limit `POST /pages/login` there — the one place a limit can be
 applied without reintroducing the lockout, because the proxy sees the
-real client address. `TRUSTED_PROXIES` does not stop the saturation.
+real client address. Setting `TRUSTED_PROXIES` does not stop the
-The flood's source is in the proxy's access log: webhooker's own logs
+saturation, but it makes the source visible in the failure logs.
-record the proxy's address, not the client's (see
-[Deployment behind a reverse proxy](#deployment-behind-a-reverse-proxy)).
 
 Finer-grained per-webhook rate limits (configured in the web UI and
 enforced in the webhook handler) can layer on top of this env-level
@@ -3082,9 +3065,10 @@ check, see [The login endpoint](#the-login-endpoint).
   It runs behind session auth, so only a client already holding a
   valid session reaches it, and an operator throttled out of changing
   a password can still log in. The bucket is per client IP only when
-  `TRUSTED_PROXIES` covers the reverse proxy; otherwise every client
+  `TRUSTED_PROXIES` names the reverse proxy; unset, every client
   shares one bucket, which costs precision rather than availability
-  (see [Rate Limiting](#rate-limiting))
+  (see [Rate Limiting](#rate-limiting)). webhooker warns at startup
+  whenever `TRUSTED_PROXIES` is empty
 - Prometheus metrics behind basic auth
 - Static assets embedded in binary (no filesystem access needed at
   runtime)
@@ -3104,8 +3088,7 @@ each hook. The order, read off the fx stop-hook log:
 3. `server` — the HTTP drain, bounded separately by
    `server.ShutdownTimeout` (**3 seconds**), then a Sentry flush if
    `SENTRY_DSN` is set
-4. `delivery.Engine` — waits for its workers, then closes the archive
+4. `delivery.Engine`
-   databases
 5. `healthcheck`
 6. `WebhookDBManager`
 7. the database close

internal/config/config.go

@@ -75,11 +75,6 @@ const (
 	// internet-exposed endpoint.
 	defaultReceiverRateLimit = 120
 
-	// defaultTrustedProxies is TRUSTED_PROXIES when it is unset: the
-	// RFC 1918 private ranges, which a reverse proxy reaching the
-	// process over a Docker network or a private LAN connects from.
-	defaultTrustedProxies = "10.0.0.0/8,172.16.0.0/12,192.168.0.0/16"
-
 	// maxPort is the highest valid TCP port number. The lower
 	// bound (at least 1) is enforced by envPositiveInt.
 	maxPort = 65535
@@ -177,14 +172,13 @@ type Config struct {
 
 	// TrustedProxies is the set of networks whose members are
 	// allowed to speak for the client with X-Forwarded-For, the
-	// only forwarded header read. Unless TRUSTED_PROXIES is set it
+	// only forwarded header read. It is empty unless
-	// is the RFC 1918 private ranges (defaultTrustedProxies).
+	// TRUSTED_PROXIES is set, and empty means no peer is
-	// Other peers' forwarded headers are ignored and they are
+	// trusted: forwarded headers are then ignored entirely and
-	// identified by the connection's own address. Under the
+	// clients are identified by the connection's own address.
-	// default any client with a private address, directly or
+	// Members can choose their own rate-limit key, so this must
-	// through a proxy, can choose its own rate-limit key, so
+	// name proxy hosts only, never a block that also covers
-	// where any clients have private addresses this must be set
+	// clients.
-	// to the proxy hosts alone.
 	TrustedProxies []netip.Prefix
 
 	// AllowedEgressCIDRs is the set of networks a delivery target
@@ -198,10 +192,9 @@ type Config struct {
 	// alwaysBlockedNetworks stays blocked no matter what is listed
 	// here. That set is link-local plus the cloud metadata
 	// endpoints outside it that disclose credentials or user data
-	// at a provider-fixed, non-public address; it is not
+	// at a provider-fixed address; it is not exhaustive of every
-	// exhaustive of every cloud's metadata address. See
+	// cloud's metadata address. See alwaysBlockedNetworks for the
-	// alwaysBlockedNetworks for the authoritative list and the
+	// authoritative list and the criterion it is built from.
-	// criterion it is built from.
 	AllowedEgressCIDRs []netip.Prefix
 
 	params *ConfigParams
@@ -466,15 +459,14 @@ func parseCIDR(entry string) (netip.Prefix, error) {
 
 // envPrefixList returns the value of the named environment variable
 // parsed as a comma-separated list of CIDR blocks (bare addresses
-// allowed). An unset, empty, or blank value is read as defaultValue
+// allowed). An unset, empty, or blank value yields an empty list. A
-// instead. A set value containing an unparseable entry is a hard
+// set value containing an unparseable entry is a hard error naming
-// error naming the key and the bad entry, so startup fails loudly
+// the key and the bad entry, so startup fails loudly rather than
-// rather than silently running with a list the operator did not
+// silently running with a list the operator did not intend.
-// intend.
+func envPrefixList(key string) ([]netip.Prefix, error) {
-func envPrefixList(key, defaultValue string) ([]netip.Prefix, error) {
 	v := strings.TrimSpace(os.Getenv(key))
 	if v == "" {
-		v = defaultValue
+		return nil, nil
 	}
 
 	var prefixes []netip.Prefix
@@ -688,12 +680,12 @@ func loadFromEnv() (*Config, error) {
 		return nil, err
 	}
 
-	trustedProxies, err := envPrefixList("TRUSTED_PROXIES", defaultTrustedProxies)
+	trustedProxies, err := envPrefixList("TRUSTED_PROXIES")
 	if err != nil {
 		return nil, err
 	}
 
-	allowedEgressCIDRs, err := envPrefixList("ALLOWED_EGRESS_CIDRS", "")
+	allowedEgressCIDRs, err := envPrefixList("ALLOWED_EGRESS_CIDRS")
 	if err != nil {
 		return nil, err
 	}
@@ -754,19 +746,61 @@ func (c *Config) warnEgressAllowlist(log *slog.Logger) {
 
 	log.Warn(
 		"ALLOWED_EGRESS_CIDRS lets delivery targets reach these "+
-			"otherwise-blocked networks. Anyone who can create a "+
+			"otherwise-blocked private/reserved networks. Anyone "+
-			"delivery target can now make this process issue "+
+			"who can create a delivery target can now make this "+
-			"requests into them, and read back the response. Only "+
+			"process issue requests into them, and read back the "+
-			"the addresses the README lists as blocked "+
+			"response. Link-local and the known cloud instance "+
-			"unconditionally stay blocked regardless of what is "+
+			"metadata endpoints outside it stay blocked "+
-			"listed here; a public cloud metadata address such as "+
+			"regardless of what is listed here.",
-			"168.63.129.16 is reachable once it, or a block "+
-			"covering it, is listed.",
 		"allowedEgressCIDRs",
 		strings.Join(PrefixStrings(c.AllowedEgressCIDRs), ","),
 	)
 }
 
+// warnSharedRateLimitBucket logs a startup warning whenever
+// TRUSTED_PROXIES is empty, in any environment.
+//
+// With no trusted proxies every rate limiter keys on the connecting
+// peer's address. Whether that is harmless or dangerous depends on
+// what is in front of the process, which this code cannot observe:
+// with nothing in front, the peer is the client and the limits are
+// per-client as intended; behind a reverse proxy the peer is the proxy
+// for every request, so all clients share one bucket per limiter.
+//
+// The login endpoint no longer spends budget on arrival — it verifies
+// credentials first and charges only failures — so a shared bucket
+// cannot deny the operator a correct password. What it does collapse
+// is the failure counting: one client's wrong passwords throttle
+// everyone else's wrong passwords, and the receiver's limits become
+// service-wide ceilings.
+//
+// The warning is deliberately not gated on WEBHOOKER_ENVIRONMENT:
+// behind a proxy every client shares one bucket in dev and prod alike.
+//
+// The default of trusting nobody is deliberate — trusting forwarded
+// headers from arbitrary peers lets any client choose its own bucket —
+// so this warns rather than failing startup or changing the key.
+func (c *Config) warnSharedRateLimitBucket(log *slog.Logger) {
+	if len(c.TrustedProxies) > 0 {
+		return
+	}
+
+	log.Warn(
+		"TRUSTED_PROXIES is empty: every rate limit keys on the "+
+			"connecting peer's address. With nothing proxying to "+
+			"this process that is the client itself and the limits "+
+			"are per-client as intended. Behind a reverse proxy the "+
+			"peer is the proxy on every request, so all clients "+
+			"share one bucket per limit: the receiver limits become "+
+			"service-wide ceilings, and one client's failed logins "+
+			"throttle every other client's failed logins — a "+
+			"correct password still gets in. If anything proxies to "+
+			"this process, set TRUSTED_PROXIES to its address.",
+		"environment", c.Environment,
+		"trustedProxies", len(c.TrustedProxies),
+	)
+}
+
 // New creates a Config by reading environment variables.
 //
 //nolint:revive // lc parameter is required by fx even if unused.
@@ -812,6 +846,7 @@ func New(lc fx.Lifecycle, params ConfigParams) (*Config, error) {
 		"hasMetricsAuth", s.MetricsAuthEnabled(),
 	)
 
+	s.warnSharedRateLimitBucket(log)
 	s.warnEgressAllowlist(log)
 
 	return s, nil

internal/config/config_test.go

@@ -551,11 +551,6 @@ func testReceiverRateLimitSuccess(
 }
 
 func TestTrustedProxies(t *testing.T) {
-	// Unset, the RFC 1918 private ranges are trusted, so a reverse
-	// proxy on a Docker network or a private LAN is covered without
-	// configuration.
-	defaultProxies := []string{cidrPrivateV4, "172.16.0.0/12", "192.168.0.0/16"}
-
 	tests := []struct {
 		name        string
 		set         bool
@@ -564,21 +559,18 @@ func TestTrustedProxies(t *testing.T) {
 		expected    []string
 	}{
 		{
+			// The default must be "trust nobody": an empty list
+			// means forwarded headers are ignored, never that
+			// every peer may speak for the client.
 			name:     caseUnsetUsesDefault,
 			set:      false,
-			expected: defaultProxies,
+			expected: []string{},
 		},
 		{
-			name:     "blank value uses default",
+			name:     "blank value trusts nothing",
 			set:      true,
 			value:    "  ",
-			expected: defaultProxies,
+			expected: []string{},
-		},
-		{
-			name:     "set value replaces the default entirely",
-			set:      true,
-			value:    "203.0.113.7",
-			expected: []string{"203.0.113.7/32"},
 		},
 		{
 			name:  caseValidValueParsed,
@@ -842,13 +834,107 @@ func TestEgressAllowlistWarning(t *testing.T) {
 			// to be able to read back which networks are open.
 			assert.Contains(t, logged, "10.0.0.0/8")
 			assert.Contains(t, logged, "127.0.0.0/8")
-			// What stays shut is the whole unconditional set, not
+			// What stays shut. Asserted on the clause naming the
-			// link-local alone; a public metadata address is not in
+			// wider set rather than on "Link-local" alone, so the
-			// it, so a listed block covering it opens it.
+			// string cannot narrow back to link-local only while
-			assert.Contains(t, logged, "blocked unconditionally")
+			// the always-blocked set covers ULA, CGNAT and two
-			assert.Contains(t, logged, "168.63.129.16 is reachable")
+			// public metadata addresses as well.
-			// The listed blocks need not be private or reserved.
+			assert.Contains(t, logged, "metadata endpoints outside it")
-			assert.NotContains(t, logged, "private/reserved")
+		})
+	}
+}
+
+// TestSharedRateLimitBucketWarning covers the startup warning that
+// tells an operator a deployment behind a reverse proxy shares one
+// rate-limit bucket between every client, which turns the receiver
+// limits into service-wide ceilings and collapses login failure
+// counting. It must fire whenever TRUSTED_PROXIES is empty, in any
+// environment, because behind a proxy every client shares one bucket
+// in dev and prod alike. It stays quiet once proxies are named.
+func TestSharedRateLimitBucketWarning(t *testing.T) {
+	tests := []struct {
+		name           string
+		environment    string
+		trustedProxies string
+		expectWarning  bool
+	}{
+		{
+			name:          "prod without trusted proxies warns",
+			environment:   config.EnvironmentProd,
+			expectWarning: true,
+		},
+		{
+			name:           "prod with trusted proxies is quiet",
+			environment:    config.EnvironmentProd,
+			trustedProxies: cidrPrivateV4,
+			expectWarning:  false,
+		},
+		{
+			name:          "dev without trusted proxies warns",
+			environment:   config.EnvironmentDev,
+			expectWarning: true,
+		},
+		{
+			name:           "dev with trusted proxies is quiet",
+			environment:    config.EnvironmentDev,
+			trustedProxies: cidrPrivateV4,
+			expectWarning:  false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// Cannot use t.Parallel() here because t.Setenv
+			// is incompatible with parallel subtests.
+			t.Setenv("WEBHOOKER_ENVIRONMENT", tt.environment)
+
+			if tt.trustedProxies == "" {
+				require.NoError(
+					t, os.Unsetenv("TRUSTED_PROXIES"),
+				)
+			} else {
+				t.Setenv("TRUSTED_PROXIES", tt.trustedProxies)
+			}
+
+			var buf bytes.Buffer
+
+			log := slog.New(slog.NewJSONHandler(
+				&buf, &slog.HandlerOptions{
+					Level: slog.LevelDebug,
+				},
+			))
+
+			require.NoError(
+				t,
+				config.WarnSharedRateLimitBucketForTest(log),
+			)
+
+			if !tt.expectWarning {
+				assert.Empty(t, buf.String())
+
+				return
+			}
+
+			logged := buf.String()
+
+			assert.Contains(t, logged, `"level":"WARN"`)
+			assert.Contains(t, logged, "TRUSTED_PROXIES")
+			assert.Contains(t, logged, "share one bucket")
+			assert.Contains(
+				t, logged, "throttle every other client's failed logins",
+			)
+			// The warning must not claim a lockout the login
+			// endpoint no longer permits: credentials are verified
+			// before any budget is spent.
+			assert.Contains(
+				t, logged, "a correct password still gets in",
+			)
+			// The text must stay accurate for a developer with
+			// nothing in front of the process, where an empty
+			// list costs nothing.
+			assert.Contains(
+				t, logged, "nothing proxying to this process",
+			)
 		})
 	}
 }

internal/config/export_test.go

@@ -6,6 +6,21 @@ import "log/slog"
 // the external config_test package so each helper can be covered by
 // its own table-driven test without weakening the package API.
 
+// WarnSharedRateLimitBucketForTest loads a Config from the current
+// environment and emits its startup warnings to log. The real logger
+// writes to stdout, so this lets the warning's firing condition be
+// asserted against a handler the test controls.
+func WarnSharedRateLimitBucketForTest(log *slog.Logger) error {
+	c, err := loadFromEnv()
+	if err != nil {
+		return err
+	}
+
+	c.warnSharedRateLimitBucket(log)
+
+	return nil
+}
+
 // WarnEgressAllowlistForTest loads a Config from the current
 // environment and emits its egress-allowlist startup warning to
 // log, so a test can assert both that the warning fires only when

internal/delivery/engine.go

@@ -362,15 +362,6 @@ func (e *Engine) start() {
 // stop cancels the worker pool's context and waits for the pool
 // to drain, bounded by the stop hook's context: a wedged worker
 // must not hang the process past fx's stop timeout.
-//
-// Once the pool has drained it closes the archive writers, so a
-// clean stop leaves no archive -wal behind. Nothing else holds a
-// writer for long by then: the archive sweeper stops before the
-// engine, and deleting a webhook only closes one. If the pool did
-// not drain in time, the writers are left open, as a kill would
-// leave them. Closing them would wait for any write in progress,
-// and a worker still running would then open new writers that
-// nothing closes, so it gains nothing over a kill.
 func (e *Engine) stop(ctx context.Context) error {
 	e.log.Info("delivery engine stopping")
 
@@ -385,8 +376,6 @@ func (e *Engine) stop(ctx context.Context) error {
 		return err
 	}
 
-	e.dbTarget.evictAll()
-
 	e.log.Info("delivery engine stopped")
 
 	return nil

internal/delivery/engine_lifecycle_test.go

@@ -2,8 +2,6 @@ package delivery_test
 
 import (
 	"context"
-	"fmt"
-	"path/filepath"
 	"testing"
 	"time"
 
@@ -271,88 +269,3 @@ func TestEngine_StopHookHonoursStopTimeout(t *testing.T) {
 
 	requireStopHookExpires(t, lc.hooks[0], "delivery engine")
 }
-
-// deliverToArchive runs one delivery to a database target through
-// the running engine and returns the webhook's archive file path.
-// The archive writer holds the file open afterwards.
-func deliverToArchive(t *testing.T, s iSetup) string {
-	t.Helper()
-
-	deliveryID, task := seedLogTask(t, s)
-	task.TargetType = database.TargetTypeDatabase
-
-	s.Engine.Notify([]delivery.Task{task})
-
-	iWaitForDelivered(t, s.WebhookDB, deliveryID)
-
-	return filepath.Join(
-		filepath.Dir(s.DBMgr.DBPath(s.WebhookID)),
-		fmt.Sprintf("archive-%s.db", s.WebhookID),
-	)
-}
-
-// TestEngine_StopHookClosesArchives is the regression test for an
-// archive split across two files by a clean stop. The engine never
-// closed its archive writers, so after a stop the archived rows
-// could sit in archive-{id}.db-wal while archive-{id}.db held no
-// table at all, and copying the .db on its own gave an empty
-// database.
-func TestEngine_StopHookClosesArchives(t *testing.T) {
-	t.Parallel()
-
-	s := newISetup(t)
-
-	lc := startEngineViaHook(t, s.Engine)
-
-	path := deliverToArchive(t, s)
-	require.FileExists(
-		t, path+"-wal",
-		"an open archive should have a -wal for the stop to remove",
-	)
-
-	require.NoError(t, lc.hooks[0].OnStop(context.Background()))
-
-	wals, err := filepath.Glob(
-		filepath.Join(filepath.Dir(path), "archive-*.db-wal"),
-	)
-	require.NoError(t, err)
-	require.Empty(
-		t, wals, "a clean stop must leave no archive -wal behind",
-	)
-
-	// With no -wal beside it, the row can only be in the .db.
-	count, err := countArchivedRows(path)
-	require.NoError(t, err)
-	require.Equal(t, int64(1), count)
-}
-
-// TestEngine_StopHookTimeoutLeavesArchivesOpen covers a stop whose
-// budget runs out while a worker is still running. The archive
-// writers are left open, as a kill would leave them: closing them
-// would wait for any write in progress, and that worker would then
-// open new writers that nothing closes.
-func TestEngine_StopHookTimeoutLeavesArchivesOpen(t *testing.T) {
-	t.Parallel()
-
-	s := newISetup(t)
-
-	lc := startEngineViaHook(t, s.Engine)
-
-	deliverToArchive(t, s)
-
-	release := make(chan struct{})
-
-	t.Cleanup(func() {
-		close(release)
-		s.Engine.EvictWebhook(s.WebhookID)
-	})
-
-	s.Engine.ExportWedgeWorker(release)
-
-	requireStopHookExpires(t, lc.hooks[0], "delivery engine")
-
-	require.True(
-		t, s.Engine.ExportArchiveHandleOpen(s.WebhookID),
-		"a stop that timed out must not close archive writers",
-	)
-}

internal/delivery/engine_test.go

@@ -1166,10 +1166,6 @@ func TestIsForwardableHeader(t *testing.T) {
 	assert.False(t,
 		delivery.ExportIsForwardableHeader("Content-Length"),
 	)
-
-	assert.False(t,
-		delivery.ExportIsForwardableHeader("Content-Type"),
-	)
 }
 
 func TestTruncate(t *testing.T) {
@@ -1251,81 +1247,6 @@ func TestDoHTTPRequest_ForwardsHeaders(t *testing.T) {
 	)
 }
 
-// The event's stored inbound headers carry the same Content-Type the
-// receiver saved as the event's ContentType, so a delivery could send
-// it twice. It must go out exactly once, with a Content-Type configured
-// on the target winning, then the event's ContentType.
-func TestApplyRequestHeaders_SendsOneContentType(t *testing.T) {
-	t.Parallel()
-
-	cases := map[string]struct {
-		inbound    string
-		event      string
-		configured string
-		want       []string
-	}{
-		"inbound and event agree": {
-			inbound: testContentType,
-			event:   testContentType,
-			want:    []string{testContentType},
-		},
-		"inbound and event disagree": {
-			inbound: "text/plain",
-			event:   testContentType,
-			want:    []string{testContentType},
-		},
-		"event has none": {
-			inbound: testContentType,
-			want:    nil,
-		},
-		"target configures its own": {
-			inbound:    testContentType,
-			event:      testContentType,
-			configured: "application/xml",
-			want:       []string{"application/xml"},
-		},
-	}
-
-	for name, tc := range cases {
-		t.Run(name, func(t *testing.T) {
-			t.Parallel()
-
-			inbound, err := json.Marshal(map[string][]string{
-				headerContentType: {tc.inbound},
-			})
-			require.NoError(t, err)
-
-			cfg := &delivery.HTTPTargetConfig{}
-			if tc.configured != "" {
-				cfg.Headers = map[string]string{
-					headerContentType: tc.configured,
-				}
-			}
-
-			req, err := http.NewRequestWithContext(
-				context.Background(),
-				http.MethodPost,
-				"https://target.example.com/hook",
-				http.NoBody,
-			)
-			require.NoError(t, err)
-
-			delivery.ExportApplyRequestHeaders(
-				req,
-				&database.Event{
-					Headers:     string(inbound),
-					ContentType: tc.event,
-				},
-				cfg,
-			)
-
-			assert.Equal(t,
-				tc.want, req.Header.Values(headerContentType),
-			)
-		})
-	}
-}
-
 func TestProcessDelivery_RoutesToCorrectHandler(
 	t *testing.T,
 ) {

internal/delivery/redirect_test.go

@@ -339,11 +339,10 @@ func TestRedirectPolicy_StopsAtHopCap(t *testing.T) {
 // The set the redirect policy strips is whatever the delivery path
 // actually put on the wire, so a header added to the forward set is
 // covered without a second edit. A header the event never carried
-// is not in the set, and neither is the inbound Content-Type, because
+// is not in the set, and the delivery path's own two are deliberately
-// it is not forwarded. Two more are deliberately excluded: a
+// excluded: Content-Type describes the body, which a 307 carries
-// Content-Type configured on the target describes the body, which a
+// across hosts, and the inbound User-Agent every real sender supplies
-// 307 carries across hosts, and the inbound User-Agent every real
+// is overwritten before the request goes out.
-// sender supplies is overwritten before the request goes out.
 func TestApplyRequestHeaders_ReportsOriginScopedNames(t *testing.T) {
 	t.Parallel()
 
@@ -372,7 +371,6 @@ func TestApplyRequestHeaders_ReportsOriginScopedNames(t *testing.T) {
 		&delivery.HTTPTargetConfig{
 			Headers: map[string]string{
 				probeHeaderName: probeHeaderValue,
-				"Content-Type":  testContentType,
 			},
 		},
 	)
@@ -380,11 +378,7 @@ func TestApplyRequestHeaders_ReportsOriginScopedNames(t *testing.T) {
 	assert.Equal(t,
 		[]string{probeHeaderName, inboundHeaderName}, names,
 		"both header classes are reported, and only those: "+
-			"Host and the inbound Content-Type are never "+
+			"Host is never forwarded, Content-Type and "+
-			"forwarded, User-Agent is the delivery path's own",
+			"User-Agent are the delivery path's own",
-	)
-	assert.NotContains(t, names, "Content-Type",
-		"a Content-Type configured on the target must survive "+
-			"a cross-origin 307/308 with the body it describes",
 	)
 }

internal/delivery/ssrf.go

@@ -26,7 +26,7 @@ var (
 		"hostname resolved to no IP addresses",
 	)
 	errBlockedIP = errors.New(
-		"blocked private, reserved or cloud metadata address",
+		"blocked private/reserved IP range",
 	)
 	errBlockedMetadata = errors.New(
 		"blocked link-local or cloud instance metadata " +
@@ -37,10 +37,9 @@ var (
 	)
 )
 
-// blockedNetworks is the default blocklist: the private and
+// blockedNetworks contains all private/reserved IP ranges
-// reserved IP ranges, plus the public cloud metadata addresses,
+// that should be blocked to prevent SSRF attacks. An operator
-// that are blocked to prevent SSRF attacks. An operator can
+// can permit specific blocks out of this set with
-// permit specific blocks out of this set with
 // ALLOWED_EGRESS_CIDRS; see Guard.
 //
 //nolint:gochecknoglobals // package-level network list is appropriate here
@@ -123,8 +122,6 @@ func init() {
 		"::1/128",
 		"fc00::/7",
 		"fe80::/10",
-		// Azure WireServer, a public address that serves VM credentials.
-		"168.63.129.16/32",
 	})
 
 	// Every entry is named. The set must not grow or shrink
@@ -219,8 +216,8 @@ func matchesAny(networks []*net.IPNet, ip net.IP) bool {
 }
 
 // isBlockedIP checks whether an IP address falls within
-// the default blocklist, before any operator allowlist is
+// any blocked private/reserved network range, before any
-// considered.
+// operator allowlist is considered.
 func isBlockedIP(ip net.IP) bool {
 	return matchesAny(blockedNetworks, ip)
 }
@@ -323,7 +320,7 @@ func (g *Guard) allows(ip net.IP) bool {
 //
 //  1. alwaysBlockedNetworks is refused before the allowlist is
 //     consulted, so no configured CIDR reaches link-local or a
-//     cloud metadata endpoint at a non-public address.
+//     cloud instance metadata endpoint.
 //  2. The allowlist is consulted next, so a listed private
 //     network becomes reachable.
 //  3. Everything else keeps the default blocklist's answer.

internal/delivery/ssrf_allowlist_test.go

@@ -390,41 +390,6 @@ func TestGuardAllowlist_PublicUnaffected(t *testing.T) {
 	}
 }
 
-// TestGuardAllowlist_AzureWireServerReopenable covers Azure's
-// WireServer, a public address that serves VM credentials. The
-// default guard refuses it, but because it is public it sits in
-// the default blocklist rather than the unconditional set, so an
-// operator who lists it can reach it.
-func TestGuardAllowlist_AzureWireServerReopenable(t *testing.T) {
-	t.Parallel()
-
-	const wireServerIP = "168.63.129.16"
-
-	target := "http://" + wireServerIP + "/?comp=versions"
-
-	defaultGuard := delivery.NewTestGuard()
-
-	err := defaultGuard.ValidateTargetURL(context.Background(), target)
-	require.Error(t, err,
-		"WireServer must be refused with no allowlist set",
-	)
-	assert.NotContains(t, err.Error(), metadataRefusalClause,
-		"WireServer must be refused by the default blocklist, "+
-			"which an allowlist can override",
-	)
-
-	assertDialRefused(t, defaultGuard, target)
-
-	listed := delivery.NewTestGuard(
-		netip.MustParsePrefix(wireServerIP + "/32"),
-	)
-
-	assert.NoError(t,
-		listed.ValidateTargetURL(context.Background(), target),
-		"an operator who lists WireServer must be able to reach it",
-	)
-}
-
 // TestGuardCheckIP_BothPathsShareOneDecision asserts that the
 // validator and the dialer are not two policies that happen to
 // agree: both are defined in terms of checkIP, so the exported

internal/delivery/target_database.go

@@ -277,24 +277,6 @@ func (t *databaseTarget) evict(webhookID string) {
 	)
 }
 
-// evictAll evicts every cached archive writer, exactly as evict
-// does for one webhook. The engine calls it at shutdown, once its
-// workers have returned. Closing the last handle on an archive
-// moves the contents of its -wal into the .db and removes the
-// -wal, so a clean stop leaves each archive as a single file.
-func (t *databaseTarget) evictAll() {
-	t.mu.Lock()
-
-	writers := t.writers
-	t.writers = nil
-
-	t.mu.Unlock()
-
-	for _, w := range writers {
-		w.evict()
-	}
-}
-
 // sweepWebhook prunes one webhook's archive of rows older than
 // expiry, without requiring a write. It returns nil (nothing to
 // do) when the archive file does not exist, so a sweep never

internal/delivery/target_database_evict_test.go

@@ -1,7 +1,6 @@
 package delivery_test
 
 import (
-	"context"
 	"errors"
 	"fmt"
 	"net/http"
@@ -362,46 +361,3 @@ func TestEvictWebhook_LaterDeliveryRecreatesWriter(t *testing.T) {
 		"a later delivery should recreate the writer",
 	)
 }
-
-// TestEngineStop_WriteAfterStopIsRefused proves the engine's stop
-// closes each archive writer the way deleting its webhook does: a
-// write that reaches a writer after the stop is refused, reopens
-// nothing and adds no row.
-func TestEngineStop_WriteAfterStopIsRefused(t *testing.T) {
-	t.Parallel()
-
-	eng, _ := evictTestEngine(t)
-
-	webhookDB := testWebhookDB(t)
-	event := seedEvent(t, webhookDB, `{"archived":true}`)
-	d := seedDatabaseTargetDelivery(t, webhookDB, event, "")
-
-	eng.ExportDeliverDatabase(webhookDB, d)
-
-	w := eng.ExportArchiveWriterFor(event.WebhookID)
-	require.NotNil(t, w)
-	require.True(t, w.HandleOpen())
-
-	require.NoError(t, eng.ExportStop(context.Background()))
-
-	err := w.Write(evictTestRow("ev-after-stop"), 0)
-
-	require.ErrorIs(
-		t, err, delivery.ErrExportArchiveWriterEvicted,
-		"a write after the stop must be refused",
-	)
-	assert.False(
-		t, w.HandleOpen(),
-		"a refused write must not reopen the archive",
-	)
-	assert.False(
-		t, eng.ExportHasArchiveWriter(event.WebhookID),
-		"the stop should empty the registry",
-	)
-
-	count, err := countArchivedRows(w.Path())
-	require.NoError(t, err)
-	assert.Equal(
-		t, int64(1), count, "the refused row must not be written",
-	)
-}

internal/delivery/target_headers_test.go

@@ -11,11 +11,10 @@ import (
 	"sneak.berlin/go/webhooker/internal/delivery"
 )
 
-// Literals these tests repeat, named so that the header names and the
+// Literals these tests repeat, named so that the header name and the
 // keep-forever archive config each have one definition.
 const (
 	headerAuthorization = "Authorization"
-	headerContentType   = "Content-Type"
 	bearerValue         = "Bearer abc"
 	archiveConfigNever  = "{\"expiry\":\"never\"}"
 )

internal/delivery/target_http.go

@@ -541,11 +541,6 @@ func isForwardableHeader(name string) bool {
 		"Upgrade", "Proxy-Authorization",
 		"Proxy-Connection", "Content-Length":
 		return false
-	case "Content-Type":
-		// applyRequestHeaders sets Content-Type itself. The receiver
-		// already stored this inbound value as the event's
-		// ContentType, so forwarding it too would send it twice.
-		return false
 	default:
 		return true
 	}
@@ -558,10 +553,6 @@ func isForwardableHeader(name string) bool {
 // policy strips exactly that set on a hop that leaves the origin,
 // so the forward set is decided here and only here — a header added
 // to it is covered off-origin without a second edit elsewhere.
-//
-// Content-Type goes out once: a Content-Type configured on the target
-// wins, otherwise the event's ContentType, otherwise none. The inbound
-// Content-Type in the event's headers is never forwarded.
 func applyRequestHeaders(
 	req *http.Request,
 	event *database.Event,
@@ -582,10 +573,10 @@ func applyRequestHeaders(
 
 	req.Header.Set("User-Agent", "webhooker/1.0")
 
-	// A Content-Type configured on the target describes the body
+	// Content-Type describes the body being sent rather than the
-	// being sent rather than the sender. A 307/308 preserves the
+	// sender, and the delivery path sets it from the event itself.
-	// body across hosts, so stripping it would send that body
+	// A 307/308 preserves the body across hosts, so stripping it
-	// untyped.
+	// would send that body untyped.
 	delete(originScoped, "Content-Type")
 
 	// User-Agent is overwritten just above, so an inbound one never

internal/handlers/auth.go

@@ -103,10 +103,9 @@ func (h *Handlers) renderLoginError(
 // The credential check runs BEFORE any rate-limit budget is
 // consulted, and only a failed check spends budget. That is what
 // keeps the single administrative path reachable: behind the reverse
-// proxy this deployment requires, when TRUSTED_PROXIES does not cover
+// proxy this deployment requires, with TRUSTED_PROXIES unset, every
-// it, every client shares one bucket, so a limiter spent on arrival
+// client shares one bucket, so a limiter spent on arrival lets any
-// lets any stranger deny the operator's own correct password
+// stranger deny the operator's own correct password indefinitely.
-// indefinitely.
 //
 // Verifying first means every login POST costs an Argon2id hash, so
 // the work is taken under a bounded number of verification slots.

internal/handlers/auth_test.go

@@ -25,7 +25,7 @@ const (
 
 	// sharedProxyPeer is the whole point of this file. Production is
 	// required to run behind a TLS-terminating reverse proxy, and
-	// when TRUSTED_PROXIES does not cover it every client — attacker
+	// TRUSTED_PROXIES defaults to empty, so every client — attacker
 	// and operator alike — reaches the process from the proxy's
 	// address and shares one rate-limit bucket. Both parties in
 	// these tests therefore use the same RemoteAddr.
@@ -115,11 +115,11 @@ func floodFailures(
 // done-criterion of https://git.eeqj.de/sneak/webhooker/issues/150.
 //
 // The attacker and the operator share one rate-limit bucket, because
-// behind the mandated reverse proxy, when TRUSTED_PROXIES does not
+// behind the mandated reverse proxy with TRUSTED_PROXIES unset every
-// cover it, every client keys on the proxy's address. The attacker
+// client keys on the proxy's address. The attacker floods the
-// floods the operator's own username — a single-admin product has a
+// operator's own username — a single-admin product has a predictable
-// predictable one — far past the failure limit. The operator must
+// one — far past the failure limit. The operator must still be able
-// still be able to log in with the correct password.
+// to log in with the correct password.
 //
 // This fails if credentials stop being verified ahead of the limiter.
 func TestLogin_StrangersFloodCannotLockOutTheOperator(t *testing.T) {

internal/middleware/loginguard.go

@@ -108,10 +108,10 @@ type failureWindow struct {
 //
 // A limiter that spends budget on arrival cannot protect a
 // single-admin product: behind the reverse proxy the deployment
-// requires, when TRUSTED_PROXIES does not cover it, every client
+// requires, with TRUSTED_PROXIES unset, every client keys on the
-// keys on the proxy, so a stranger trickling five POSTs a minute
+// proxy, so a stranger trickling five POSTs a minute keeps the one
-// keeps the one bucket full and the operator's own correct password
+// bucket full and the operator's own correct password is answered 429
-// is answered 429 forever. There is no second administrative path.
+// forever. There is no second administrative path.
 //
 // So budget is spent only by a FAILED verification. A correct
 // password is never throttled, whatever the counters say, which is

internal/middleware/ratelimit.go

@@ -123,8 +123,9 @@ func bucketKey(addr netip.Addr) string {
 	return prefix.String()
 }
 
-// isTrustedProxy reports whether addr belongs to a network in
+// isTrustedProxy reports whether addr belongs to a network the
-// TRUSTED_PROXIES, which by default is the RFC 1918 private ranges.
+// operator listed in TRUSTED_PROXIES. The list is empty by default,
+// so by default nothing is trusted.
 func (m *Middleware) isTrustedProxy(addr netip.Addr) bool {
 	for _, prefix := range m.params.Config.TrustedProxies {
 		if prefix.Contains(addr) {

internal/middleware/ratelimit_test.go

@@ -426,8 +426,8 @@ func assertSharedBucket(
 }
 
 // TestRateLimitKey_SpoofedForwardedFromUntrustedPeer is the test
-// this gating exists for: from a peer that is not a trusted
+// this gating exists for: with no trusted proxies configured (the
-// proxy, a client that rotates a forwarded header on every
+// default), a client that rotates a forwarded header on every
 // request must stay in one bucket. If forwarded headers were
 // trusted unconditionally, each spoofed value would mint a fresh
 // bucket and the limit would stop no one.

internal/middleware/recoverer.go

@@ -133,11 +133,6 @@ func (w *recoverResponseWriter) Unwrap() http.ResponseWriter {
 // what the access log records and the metrics count, and outside the
 // sentryhttp handler, whose Repanic option depends on something
 // further out recovering what it re-raises.
-//
-// Unlike http.Error on its own, it deletes any Set-Cookie the handler
-// set before panicking, because a request that failed must not hand
-// the client a credential; every other header is left to http.Error.
-// See https://git.eeqj.de/sneak/webhooker/issues/193.
 func (s *Middleware) Recoverer() func(http.Handler) http.Handler {
 	return func(next http.Handler) http.Handler {
 		return http.HandlerFunc(func(
@@ -169,8 +164,6 @@ func (s *Middleware) Recoverer() func(http.Handler) http.Handler {
 					return
 				}
 
-				rw.Header().Del("Set-Cookie")
-
 				http.Error(
 					rw,
 					http.StatusText(

internal/middleware/recoverer_test.go

@@ -304,44 +304,16 @@ func TestRecovererRepanicsErrAbortHandler(t *testing.T) {
 	)
 }
 
-// TestRecovererDropsSetCookieFromTheRecovered500 covers a handler that
-// sets a cookie and a redirect target and then panics before sending
-// anything. A request that failed must not hand the client a
-// credential, so the 500 carries no cookie; Location is left alone.
-func TestRecovererDropsSetCookieFromTheRecovered500(t *testing.T) {
-	t.Parallel()
-
-	probe := newRecovererProbe(
-		t, false,
-		func(w http.ResponseWriter, _ *http.Request) {
-			w.Header().Set("Set-Cookie", "session=x")
-			w.Header().Set("Location", "/after")
-
-			panic(panicMarker)
-		},
-	)
-
-	resp, err := probe.get(t)
-	require.NoError(t, err)
-	require.NoError(t, resp.Body.Close())
-
-	assert.Equal(t, http.StatusInternalServerError, resp.StatusCode)
-	assert.Empty(t, resp.Cookies())
-	assert.Equal(t, "/after", resp.Header.Get("Location"))
-}
-
 // TestRecovererKeepsAnAlreadyCommittedResponse covers a handler that
 // panics after sending its status. The bytes are already on the wire,
-// cookie included, so a second WriteHeader would change nothing the
+// so a second WriteHeader would change nothing the client sees and
-// client sees and would draw net/http's "superfluous
+// would draw net/http's "superfluous response.WriteHeader" report.
-// response.WriteHeader" report.
 func TestRecovererKeepsAnAlreadyCommittedResponse(t *testing.T) {
 	t.Parallel()
 
 	probe := newRecovererProbe(
 		t, false,
 		func(w http.ResponseWriter, _ *http.Request) {
-			w.Header().Set("Set-Cookie", "session=x")
 			w.WriteHeader(committedStatus)
 			_, _ = w.Write([]byte("partial"))
 
@@ -359,7 +331,6 @@ func TestRecovererKeepsAnAlreadyCommittedResponse(t *testing.T) {
 
 	assert.Equal(t, committedStatus, resp.StatusCode)
 	assert.Equal(t, "partial", string(body))
-	assert.Len(t, resp.Cookies(), 1)
 
 	record := probe.panicRecord(t)
 	assert.Equal(t, panicMarker, record["panic"])

internal/server/routes.go

@@ -140,12 +140,11 @@ func (s *Server) setupPageRoutes() {
 		r.Use(s.mw.NoCache())
 
 		// The login POST carries no pre-emptive rate limiter. Behind
-		// the reverse proxy production requires, when TRUSTED_PROXIES
+		// the reverse proxy production requires, with TRUSTED_PROXIES
-		// does not cover it, every client shares one bucket, so a
+		// unset, every client shares one bucket, so a limiter spent
-		// limiter spent on arrival lets any stranger deny the operator
+		// on arrival lets any stranger deny the operator the only
-		// the only administrative path. The handler verifies
+		// administrative path. The handler verifies credentials first
-		// credentials first and charges only failures; see
+		// and charges only failures; see Handlers.authenticateUser.
-		// Handlers.authenticateUser.
 		r.Get("/login", s.h.HandleLoginPage())
 		r.Post("/login", s.h.HandleLoginSubmit())