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This commit is contained in:
Jorijn van der Graaf 2026-08-21 04:52:25 +02:00
commit 413740af2e
4 changed files with 134 additions and 13 deletions

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@ -351,6 +351,46 @@ BUNQ_API_KEY=… TRANSFER_IBAN=NL.. \
# -> pulled 2 new credit(s) into /var/lib/catcrafts/orders.jsonl.transfer-credits.jsonl
```
#### How settlement actually reaches the shop
Two paths, and the split is deliberate.
**Primary: the bunq webhook.** bunq pushes a `MUTATION` notification when money
lands; the backend decodes the payment and appends it to the credits file, and
the reconciler settles from there. Normally seconds end to end. Registered with
`tools/register-bunq-webhook.sh` from a machine bunq's key permits (`--show`
lists what is registered, with the secret redacted). **That call REPLACES the
whole filter set**, so look before overwriting.
**bunq does not sign these notifications** — verified against doc.bunq.com: no
HMAC, no server signature, and certificate pinning authenticates us to bunq
rather than bunq to us. So the endpoint's authentication is three transport-level
controls, all of which have to stay in place:
1. **Source-IP allowlist** for `185.40.108.0/22` in the Caddyfile. This is the
strong one: forging requires completing a TLS handshake from inside that
range. bunq warns the range may change; if it does, callbacks 403 and
settlement stops — it fails closed.
2. **A secret path.** Caddy matches only the non-secret prefix `/hooks/bunq/*`,
so the secret lives solely in `BUNQ_WEBHOOK_PATH` in `payments.env` and not
in the web server config. The backend compares it in constant time, and a
non-POST to it falls through to an ordinary 404 rather than a distinctive
405 — a different answer there would confirm a guessed path.
3. **`log_skip` on that prefix.** Without it the secret would be written to the
access log and then ingested into the GoAccess database and shown in its
top-URLs panel, i.e. leaked to anyone who opens `/analytics/`.
The handler deliberately does the least it can: decode one payment, append it,
answer 200. It makes no settlement decision, so a forged callback can at worst
manufacture a credit line — it cannot bypass the reference match or the
covering-amount rule, and nothing ships without a human either way.
**Backstop: the hourly pull.** Not optional. bunq retries a callback about six
times and then drops it permanently, so a payment arriving while the backend
restarts — every deploy is a restart — is lost to the webhook with no error
anywhere. `deploy/catcrafts-credits.timer` runs `pull-and-ship-credits.sh`
hourly to turn that from a missing donation into an hour of delay.
**The key is IP-restricted, and that decides the shape.** Verified the hard way
on 2026-08-20: the bunq API key permits one address (the owner's home
connection), and **bunq enforces that on every request, not only at device

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@ -1,23 +1,26 @@
# Every five minutes. Two things set the floor and the ceiling:
# Hourly, because this is now the BACKSTOP rather than the primary path.
#
# * bunq rate-limits reads to roughly 3 GET per 3 seconds per method, so one
# call per five minutes is nowhere near it. The cost of going faster is
# nothing technical; it is just noise.
# * a donor watching the order page wants confirmation while they still care.
# Five minutes here plus the reconciler's own 60 s cadence means a fresh
# order confirms within about six minutes of the money landing.
# Since the bunq webhook landed, a payment normally settles within seconds: bunq
# pushes it, the handler writes the credit, the reconciler picks it up. This
# timer exists for the case the webhook cannot cover — bunq retries a callback
# roughly six times over a few minutes and then DROPS IT FOREVER, so a payment
# that arrives while the backend is restarting (every deploy is a restart) is
# lost to the webhook with no error anywhere. An hourly pull turns that from a
# silently missing donation into an hour of delay.
#
# It was five minutes while the pull WAS the settlement path. Hourly is the
# right cadence for a safety net, and it keeps the noise down.
#
# Persistent=true so a laptop that was asleep pulls once on waking instead of
# silently skipping every window it missed — which is exactly when a donation
# would otherwise sit unacknowledged overnight.
# silently skipping every window it missed.
[Unit]
Description=Pull bunq credits for catcrafts.net every 5 minutes
Description=Backstop pull of bunq credits for catcrafts.net (hourly)
[Timer]
OnBootSec=2min
OnUnitActiveSec=5min
OnUnitActiveSec=1h
Persistent=true
AccuracySec=30s
AccuracySec=5min
[Install]
WantedBy=timers.target

View file

@ -768,7 +768,7 @@ SafeHtml RenderPayFieldset(const Form::Checkout& prev, SafeHtml payError,
? Format(
R"(<label class="pay-option">)"
R"(<input type="radio" name="pay"{}{}>)"
R"(<span><strong>Bank transfer</strong></span></label>)",
R"(<span><strong>Bank transfer</strong><br>Regular IBAN bank transfer.</span></label>)",
Attr("value", std::string(Form::kPayBank)),
wantsCrypto ? SafeHtml{} : Raw(" checked"))
: SafeHtml{};

78
tools/register-bunq-webhook.sh Executable file
View file

@ -0,0 +1,78 @@
#!/bin/sh
# Tell bunq where to push payment notifications.
#
# Run from a machine whose address the bunq API key permits — the web host is
# not one, which is the whole reason webhooks exist in this setup. The session
# it uses comes from the context file that tools/pull-and-ship-credits.sh
# created, so run that at least once first.
#
# tools/register-bunq-webhook.sh 'https://catcrafts.net/hooks/bunq/<secret>'
# tools/register-bunq-webhook.sh --show # list what is registered
#
# THIS REPLACES THE WHOLE FILTER SET. bunq treats the POST as "here is the
# complete list", so a call that omits an existing filter deletes it. Every
# filter wanted has to be in the one request, which is why --show exists: look
# before overwriting.
#
# The target URL is never echoed: it is a shared secret, and this script's
# output tends to end up pasted into issues and chat logs.
set -eu
cd "$(dirname "$0")/.."
CTX="${CREDITS_LOCAL:-$HOME/.cache/catcrafts}/orders.jsonl.transfer-credits.jsonl.bunq-context.json"
[ -f "$CTX" ] || { echo "$0: no bunq context at $CTX — run tools/pull-and-ship-credits.sh first" >&2; exit 1; }
SESSION=$(python3 -c 'import json,sys; print(json.load(open(sys.argv[1]))["session_token"])' "$CTX")
USERID=$(python3 -c 'import json,sys; print(json.load(open(sys.argv[1]))["user_id"])' "$CTX")
[ -n "$SESSION" ] && [ "$USERID" != "0" ] || { echo "$0: context has no session — run the pull once" >&2; exit 1; }
API="https://api.bunq.com/v1/user/$USERID/notification-filter-url"
HDRS="-H Content-Type:application/json -H X-Bunq-Client-Authentication:$SESSION -H User-Agent:catcrafts.net-register/1.0"
if [ "${1:-}" = "--show" ]; then
# Redact the secret out of the response before it reaches a terminal.
# shellcheck disable=SC2086
curl -s $HDRS "$API" | python3 -c '
import json,sys,re
try: d=json.load(sys.stdin)
except Exception: print("could not parse bunq response"); sys.exit(1)
for item in d.get("Response",[]):
f=item.get("NotificationFilterUrl") or {}
t=f.get("notification_target","")
print(" category=%-22s target=%s" % (f.get("category","?"), re.sub(r"(/hooks/bunq/).*", r"\1<redacted>", t)))
'
exit 0
fi
TARGET="${1:-}"
case "$TARGET" in
https://*) ;;
*) echo "$0: pass the full https:// callback URL (bunq refuses plain http)" >&2; exit 2 ;;
esac
# MUTATION alone: it fires on every balance change and carries the Payment
# object, which is exactly what the handler decodes. Adding PAYMENT as well
# would deliver most events twice, and while the handler deduplicates on the
# payment id, doubling the traffic to buy nothing is not a trade.
BODY=$(python3 -c '
import json,sys
# No notification_delivery_method: bunq rejects it as "Superfluous" on this
# endpoint, because /notification-filter-url already means URL delivery.
print(json.dumps({"notification_filters":[
{"notification_target":sys.argv[1],
"category":"MUTATION"}]}))
' "$TARGET")
# shellcheck disable=SC2086
OUT=$(printf '%s' "$BODY" | curl -s -w '\n%{http_code}' $HDRS -X POST --data-binary @- "$API")
CODE=$(printf '%s' "$OUT" | tail -1)
if [ "$CODE" = 200 ]; then
echo "$0: registered MUTATION callbacks (target not shown)"
echo "$0: verify with $0 --show"
else
# The body can echo the target back, so redact before printing an error.
printf '%s\n' "$OUT" | sed 's#\(/hooks/bunq/\)[^"]*#\1<redacted>#g' >&2
echo "$0: bunq refused the registration (HTTP $CODE)" >&2
exit 1
fi