Fix issue where a downed lightning node would take down the API server

src/invoicing.js

@@ -255,17 +255,26 @@ class PurpleInvoiceManager {
 
   // Checks the status of an invoice once. Returns true if paid, false otherwise.
   async check_invoice_is_paid(label) {
+    const params = { label }
+    const timeout_ms = parseInt(process.env.LN_INVOICE_CHECK_TIMEOUT_MS) || 60000
+
     try {
-      const params = { label }
-      return new Promise(async (resolve, reject) => {
-        setTimeout(() => {
-          resolve(undefined)
-        }, parseInt(process.env.LN_INVOICE_CHECK_TIMEOUT_MS) || 60000)
-        const res = await this.ln_rpc({ method: "waitinvoice", params })
-        resolve(res.error ? false : true)
-      })
-    }
-    catch {
+      const res = await Promise.race([
+        this.ln_rpc({ method: "waitinvoice", params }),
+        new Promise((resolve) => {
+          setTimeout(() => {
+            resolve(undefined)
+          }, timeout_ms)
+        })
+      ])
+
+      if (res == null) {
+        return undefined
+      }
+
+      return res.error ? false : true
+    } catch (e) {
+      error("Error checking invoice %s: %s", label, e.toString())
       return undefined
     }
   }

test/ln_flow.test.js

@@ -240,3 +240,49 @@ test('LN Flow — Background polling processes paid invoices without client chec
 
   t.end();
 });
+
+test('LN Flow — failed LN node connection during check-invoice returns unpaid checkout and server keeps working', async (t) => {
+  const purple_api_controller = await PurpleTestController.new(t);
+  const user_pubkey_1 = purple_api_controller.new_client();
+
+  const new_checkout_response = await purple_api_controller.clients[user_pubkey_1].new_checkout(PURPLE_ONE_MONTH);
+  t.same(new_checkout_response.statusCode, 200);
+
+  const verify_checkout_response = await purple_api_controller.clients[user_pubkey_1].verify_checkout(new_checkout_response.body.id);
+  t.same(verify_checkout_response.statusCode, 200);
+
+  const originalLNSocket = purple_api_controller.purple_api.invoice_manager.constructor.LNSocket;
+  purple_api_controller.purple_api.invoice_manager.constructor.LNSocket = async () => ({
+    genkey() {},
+    async connect_and_init() {
+      throw new Error('connect ECONNREFUSED 24.86.66.39:9735');
+    },
+    destroy() {}
+  });
+
+  t.teardown(() => {
+    purple_api_controller.purple_api.invoice_manager.constructor.LNSocket = originalLNSocket;
+  });
+
+  const failedCheckResponse = await purple_api_controller.clients[user_pubkey_1].check_invoice(new_checkout_response.body.id);
+  t.same(failedCheckResponse.statusCode, 200);
+  t.same(failedCheckResponse.body.completed, false);
+  t.same(failedCheckResponse.body.invoice?.paid, undefined);
+
+  const checkoutAfterFailure = await purple_api_controller.clients[user_pubkey_1].get_checkout(new_checkout_response.body.id);
+  t.same(checkoutAfterFailure.statusCode, 200);
+  t.same(checkoutAfterFailure.body.completed, false);
+  t.same(checkoutAfterFailure.body.invoice?.paid, undefined);
+
+  const accountAfterFailure = await purple_api_controller.clients[user_pubkey_1].get_account();
+  t.same(accountAfterFailure.statusCode, 404);
+
+  const productsResponse = await purple_api_controller.clients[user_pubkey_1].get_products();
+  t.same(productsResponse.statusCode, 200);
+  t.ok(productsResponse.body[PURPLE_ONE_MONTH]);
+
+  const secondCheckoutResponse = await purple_api_controller.clients[user_pubkey_1].new_checkout(PURPLE_ONE_MONTH);
+  t.same(secondCheckoutResponse.statusCode, 200);
+});
+
+