lnurl: expire payRequest callback ids after seven days

A callback id is read once, minutes after the metadata request, and never
again, but the pointer keys were written without an expiry and had grown
to roughly 45% of all keys in the main database. Let the set helper take
a TTL and apply one to both lnurl pointer keys.

Co-Authored-By: Claude Fable 5.1 <[email protected]>

2 files changed, 10 insertions, 5 deletions

diff --git a/lib/db.ts b/lib/db.ts
index 4e746fa2..e03fb810 100644
--- a/lib/db.ts
+++ b/lib/db.ts
@@ -130,9 +130,9 @@ export const g = async (k) => {
   }
 };
 
-export const s = (k, v) => {
+export const s = (k, v, ttl?: number) => {
   if (k === "user:null" || k === "user:undefined") fail("null user");
-  db.set(k, JSON.stringify(v));
+  db.set(k, JSON.stringify(v), ttl ? { EX: ttl } : undefined);
 };
 
 export const ga = async (k) => {
diff --git a/routes/lnurl.ts b/routes/lnurl.ts
index 1b3f84c1..a1ee22e5 100644
--- a/routes/lnurl.ts
+++ b/routes/lnurl.ts
@@ -10,6 +10,11 @@ import { v4 } from "uuid";
 
 import { PaymentType } from "$lib/types";
 
+// A payRequest callback id is fetched once, minutes after the metadata
+// request, and never again; without an expiry these one-shot pointers were
+// ~45% of all keys in the main db.
+const LNURL_TTL = 7 * 24 * 60 * 60;
+
 const { URL } = process.env;
 const host = URL.split("/").at(-1);
 const fiveMinutes = 1000 * 60 * 5;
@@ -124,7 +129,7 @@ export default {
       ]);
 
       const id = v4();
-      await s(`lnurl:${id}`, uid);
+      await s(`lnurl:${id}`, uid, LNURL_TTL);
 
       res.send({
         allowsNostr: true,
@@ -283,8 +288,8 @@ export default {
       const total =
         (parseInt(invoice.amount || 0) + parseInt(invoice.tip || 0)) * 1000;
 
-      await s(`lnurl:${id}`, uid);
-      if (total > 0) await s(`lnurl:${id}:invoice`, invoice.id);
+      await s(`lnurl:${id}`, uid, LNURL_TTL);
+      if (total > 0) await s(`lnurl:${id}:invoice`, invoice.id, LNURL_TTL);
 
       res.send({
         allowsNostr: true,