lightningd: handle the case where the db contains a resolved HTLC without a preimage.

We need to handle this case (old db) before the next commit, which actually
fixes it.

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

lightningd/peer_htlcs.c

@@ -1704,7 +1704,7 @@ void htlcs_reconnect(struct lightningd *ld,
 
 		/* For fulfilled HTLCs, we fulfill incoming before outgoing is
 		 * completely resolved, so it's possible that we don't find
-		 * the incoming.  FIXME: iff hout->preimage! */
+		 * the incoming. */
 		for (hin = htlc_in_map_first(htlcs_in, &ini); hin;
 		     hin = htlc_in_map_next(htlcs_in, &ini)) {
 			if (hout->origin_htlc_id == hin->dbid) {
@@ -1716,6 +1716,13 @@ void htlcs_reconnect(struct lightningd *ld,
 				break;
 			}
 		}
+
+		if (!hout->in && !hout->preimage) {
+			/* FIXME: COMPAT_V061 only */
+			log_broken(ld->log,
+				   "Missing preimage for orphaned HTLC; replacing with zeros");
+			hout->preimage = talz(hout, struct preimage);
+		}
 	}
 }
 

tests/test_connection.py

@@ -1333,7 +1333,6 @@ def test_restart_multi_htlc_rexmit(node_factory, bitcoind, executor):
     wait_for(lambda: [p['status'] for p in l1.rpc.listpayments()['payments']] == ['complete', 'complete'])
 
 
-@pytest.mark.xfail(strict=True)
 @unittest.skipIf(not DEVELOPER, "needs dev-disconnect")
 def test_fulfill_incoming_first(node_factory, bitcoind):
     """Test that we handle the case where we completely resolve incoming htlc