invoice: fix potential race where invoice is paid/expired while we're calling hook.

There's actually a (very unlikely) race here: we would previously have
crashed with an assertion in invoices_resolve.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

lightningd/invoice.c

@@ -250,11 +250,17 @@ invoice_payment_hooks_done(struct invoice_payment_hook_payload *payload STEALS)
 		return;
 	}
 
+	/* Paid or expired in the meantime. */
+	if (!wallet_invoice_resolve(ld->wallet, invoice, payload->msat)) {
+		htlc_set_fail(payload->set, take(failmsg_incorrect_or_unknown(
+							 NULL, ld, payload->set->htlcs[0])));
+		return;
+	}
+
 	log_info(ld->log, "Resolved invoice '%s' with amount %s in %zu htlcs",
 		 payload->label->s,
 		 type_to_string(tmpctx, struct amount_msat, &payload->msat),
 		 tal_count(payload->set->htlcs));
-	wallet_invoice_resolve(ld->wallet, invoice, payload->msat);
 	htlc_set_fulfill(payload->set, &payload->preimage);
 }
 

lightningd/test/run-invoice-select-inchan.c

@@ -643,7 +643,7 @@ const struct invoice_details *wallet_invoice_iterator_deref(const tal_t *ctx UNN
 			      const struct invoice_iterator *it UNNEEDED)
 { fprintf(stderr, "wallet_invoice_iterator_deref called!\n"); abort(); }
 /* Generated stub for wallet_invoice_resolve */
-void wallet_invoice_resolve(struct wallet *wallet UNNEEDED,
+bool wallet_invoice_resolve(struct wallet *wallet UNNEEDED,
 			    struct invoice invoice UNNEEDED,
 			    struct amount_msat received UNNEEDED)
 { fprintf(stderr, "wallet_invoice_resolve called!\n"); abort(); }

wallet/db_postgres_sqlgen.c

@@ -1690,4 +1690,4 @@ struct db_query db_postgres_queries[] = {
 
 #endif /* LIGHTNINGD_WALLET_GEN_DB_POSTGRES */
 
-// SHA256STAMP:a61b8b6ea86287e22c696530a9b5cd35ccef271280b8ac34d2665dc5aff42fce
+// SHA256STAMP:fac2fa6846e0deadf6f24fc9deb6efb0bac04b5947c254ae39300663366178af

wallet/db_sqlite3_sqlgen.c

@@ -1690,4 +1690,4 @@ struct db_query db_sqlite3_queries[] = {
 
 #endif /* LIGHTNINGD_WALLET_GEN_DB_SQLITE3 */
 
-// SHA256STAMP:a61b8b6ea86287e22c696530a9b5cd35ccef271280b8ac34d2665dc5aff42fce
+// SHA256STAMP:fac2fa6846e0deadf6f24fc9deb6efb0bac04b5947c254ae39300663366178af

wallet/invoices.c

@@ -496,7 +496,7 @@ static enum invoice_status invoice_get_status(struct invoices *invoices, struct
 	return state;
 }
 
-void invoices_resolve(struct invoices *invoices,
+bool invoices_resolve(struct invoices *invoices,
 		      struct invoice invoice,
 		      struct amount_msat received)
 {
@@ -505,7 +505,8 @@ void invoices_resolve(struct invoices *invoices,
 	u64 paid_timestamp;
 	enum invoice_status state = invoice_get_status(invoices, invoice);
 
-	assert(state == UNPAID);
+	if (state != UNPAID)
+		return false;
 
 	/* Assign a pay-index. */
 	pay_index = get_next_pay_index(invoices->db);
@@ -527,6 +528,7 @@ void invoices_resolve(struct invoices *invoices,
 
 	/* Tell all the waiters about the paid invoice. */
 	trigger_invoice_waiter_resolve(invoices, invoice.id, &invoice);
+	return true;
 }
 
 /* Called when an invoice waiter is destructed. */

wallet/invoices.h

@@ -174,10 +174,9 @@ const struct invoice_details *invoices_iterator_deref(
  * @invoice - the invoice to mark as paid.
  * @received - the actual amount received.
  *
- * Precondition: the invoice must not yet be expired (invoices
+ * If the invoice is not UNPAID, returns false.
- * does not check).
  */
-void invoices_resolve(struct invoices *invoices,
+bool invoices_resolve(struct invoices *invoices,
 		      struct invoice invoice,
 		      struct amount_msat received);
 

wallet/statements_gettextgen.po

@@ -666,15 +666,15 @@ msgstr ""
 msgid "SELECT state FROM invoices WHERE id = ?;"
 msgstr ""
 
-#: wallet/invoices.c:515
+#: wallet/invoices.c:516
 msgid "UPDATE invoices   SET state=?     , pay_index=?     , msatoshi_received=?     , paid_timestamp=? WHERE id=?;"
 msgstr ""
 
-#: wallet/invoices.c:571
+#: wallet/invoices.c:573
 msgid "SELECT id  FROM invoices WHERE pay_index IS NOT NULL   AND pay_index > ? ORDER BY pay_index ASC LIMIT 1;"
 msgstr ""
 
-#: wallet/invoices.c:620
+#: wallet/invoices.c:622
 msgid "SELECT  state, payment_key, payment_hash, label, msatoshi, expiry_time, pay_index, msatoshi_received, paid_timestamp, bolt11, description, features FROM invoices WHERE id = ?;"
 msgstr ""
 
@@ -1113,4 +1113,4 @@ msgstr ""
 #: wallet/test/run-wallet.c:1376
 msgid "INSERT INTO channels (id) VALUES (1);"
 msgstr ""
-#  SHA256STAMP:a63bd31a3977b161d8245ffddf5de3a03c972a60436eb8cbc1bb23f0ffb03405
+#  SHA256STAMP:8f226711a58166b481aaa7b8c0593c7159711bee623737e3b4750f6c154d4f65

wallet/test/run-wallet.c

@@ -220,7 +220,7 @@ struct invoices *invoices_new(const tal_t *ctx UNNEEDED,
 			      struct timers *timers UNNEEDED)
 { fprintf(stderr, "invoices_new called!\n"); abort(); }
 /* Generated stub for invoices_resolve */
-void invoices_resolve(struct invoices *invoices UNNEEDED,
+bool invoices_resolve(struct invoices *invoices UNNEEDED,
 		      struct invoice invoice UNNEEDED,
 		      struct amount_msat received UNNEEDED)
 { fprintf(stderr, "invoices_resolve called!\n"); abort(); }

wallet/wallet.c

@@ -2337,11 +2337,11 @@ wallet_invoice_iterator_deref(const tal_t *ctx, struct wallet *wallet,
 {
 	return invoices_iterator_deref(ctx, wallet->invoices, it);
 }
-void wallet_invoice_resolve(struct wallet *wallet,
+bool wallet_invoice_resolve(struct wallet *wallet,
 			    struct invoice invoice,
 			    struct amount_msat msatoshi_received)
 {
-	invoices_resolve(wallet->invoices, invoice, msatoshi_received);
+	return invoices_resolve(wallet->invoices, invoice, msatoshi_received);
 }
 void wallet_invoice_waitany(const tal_t *ctx,
 			    struct wallet *wallet,

wallet/wallet.h

@@ -883,10 +883,9 @@ const struct invoice_details *wallet_invoice_iterator_deref(const tal_t *ctx,
  * @invoice - the invoice to mark as paid.
  * @received - the actual amount received.
  *
- * Precondition: the invoice must not yet be expired (wallet
+ * If the invoice is not UNPAID, returns false.
- * does not check!).
  */
-void wallet_invoice_resolve(struct wallet *wallet,
+bool wallet_invoice_resolve(struct wallet *wallet,
 			    struct invoice invoice,
 			    struct amount_msat received);