lightningd: fix case where injectpaymentonion failure results in listsendpays "pending".

If we failed after we register (e.g. channeld not available), we don't
mark it failed.  We shouldn't register until we've definitely created
the htlc.

Changelog-Fixed: `xpay` would sometimes leave payment parts status `pending` in failure cases (as seen in listpays or listsendpays).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Fixes: #8629

Author: rustyrussell

lightningd/pay.c

@@ -2076,19 +2076,11 @@ static struct command_result *json_injectpaymentonion(struct command *cmd,
 	if (command_check_only(cmd))
 		return command_check_done(cmd);
 
-	register_payment_and_waiter(cmd,
-				    payment_hash,
-				    *partid, *groupid,
-				    *destination_msat, *msat, AMOUNT_MSAT(0),
-				    label, invstring, local_invreq_id,
-				    &shared_secret,
-				    destination);
-
-	/* If unknown, we set this equal (so accounting logs 0 fees) */
-	if (amount_msat_eq(*destination_msat, AMOUNT_MSAT(0)))
-		*destination_msat = *msat;
 	failmsg = send_htlc_out(tmpctx, next, *msat,
-				*cltv, *destination_msat,
+				*cltv,
+				/* If unknown, we set this equal (so accounting logs 0 fees) */
+				amount_msat_eq(*destination_msat, AMOUNT_MSAT(0))
+				? *msat : *destination_msat,
 				payment_hash,
 				next_path_key, NULL, *partid, *groupid,
 				serialize_onionpacket(tmpctx, rs->next),
@@ -2098,6 +2090,16 @@ static struct command_result *json_injectpaymentonion(struct command *cmd,
 				    "Could not send to first peer: %s",
 				    onion_wire_name(fromwire_peektype(failmsg)));
 	}
+
+	/* Now HTLC is created, we can add the payment as pending */
+	register_payment_and_waiter(cmd,
+				    payment_hash,
+				    *partid, *groupid,
+				    *destination_msat, *msat, AMOUNT_MSAT(0),
+				    label, invstring, local_invreq_id,
+				    &shared_secret,
+				    destination);
+
 	return command_still_pending(cmd);
 }
 

tests/test_pay.py

@@ -6755,7 +6755,6 @@ def test_injectpaymentonion_failures(node_factory, executor):
     assert 'onionreply' in err.value.error['data']
 
 
-@pytest.mark.xfail(strict=True)
 def test_injectpaymentonion_peerfail(node_factory, executor):
     l1, l2 = node_factory.line_graph(2,
                                      opts=[{'may_reconnect': True,