Correctly handle any `UPDATE` errors to phandom invoices

If we try to send any onion error with the `UPDATE` flag in
response to a phantom receipt, we should always swap it for
something generic that doesn't require a `channel_update` in it.
Here we use `temporary_node_failure`.

Test provided by Valentine Wallace <vwallace@protonmail.com>

diff --git a/lightning/src/ln/channelmanager.rs b/lightning/src/ln/channelmanager.rs
index e0a54841e5d432d8bce0cc0f16ecdb909eb18ca0..6e5df15908adb097ea5b96655b234e46ac66907a 100644 (file)
--- a/lightning/src/ln/channelmanager.rs
+++ b/lightning/src/ln/channelmanager.rs
@@ -2222,7 +2222,7 @@ impl<M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelManager<M, T, K, F
                        // with a short_channel_id of 0. This is important as various things later assume
                        // short_channel_id is non-0 in any ::Forward.
                        if let &PendingHTLCRouting::Forward { ref short_channel_id, .. } = routing {
-                               if let Some((err, code, chan_update)) = loop {
+                               if let Some((err, mut code, chan_update)) = loop {
                                        let id_option = self.short_to_chan_info.read().unwrap().get(&short_channel_id).cloned();
                                        let mut channel_state = self.channel_state.lock().unwrap();
                                        let forwarding_id_opt = match id_option {
@@ -2331,6 +2331,12 @@ impl<M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelManager<M, T, K, F
                                                (chan_update.serialized_length() as u16 + 2).write(&mut res).expect("Writes cannot fail");
                                                msgs::ChannelUpdate::TYPE.write(&mut res).expect("Writes cannot fail");
                                                chan_update.write(&mut res).expect("Writes cannot fail");
+                                       } else if code & 0x1000 == 0x1000 {
+                                               // If we're trying to return an error that requires a `channel_update` but
+                                               // we're forwarding to a phantom or intercept "channel" (i.e. cannot
+                                               // generate an update), just use the generic "temporary_node_failure"
+                                               // instead.
+                                               code = 0x2000 | 2;
                                        }
                                        return_err!(err, code, &res.0[..]);
                                }

diff --git a/lightning/src/ln/onion_route_tests.rs b/lightning/src/ln/onion_route_tests.rs
index d96b8df95337c31b15cedad3fae98b0ae9e98ef1..7978114c0ff6c90c902ae1a5f5c5adc26f6f0ea4 100644 (file)
--- a/lightning/src/ln/onion_route_tests.rs
+++ b/lightning/src/ln/onion_route_tests.rs
@@ -1150,6 +1150,45 @@ fn test_phantom_failure_modified_cltv() {
        expect_payment_failed_conditions(&nodes[0], payment_hash, false, fail_conditions);
 }
 
+#[test]
+fn test_phantom_failure_expires_too_soon() {
+       // Test that we fail back phantoms if the HTLC got delayed and we got blocks in between with
+       // the correct error code.
+       let chanmon_cfgs = create_chanmon_cfgs(2);
+       let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
+       let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
+       let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
+
+       let channel = create_announced_chan_between_nodes(&nodes, 0, 1, channelmanager::provided_init_features(), channelmanager::provided_init_features());
+
+       // Get the route.
+       let recv_value_msat = 10_000;
+       let (_, payment_hash, payment_secret) = get_payment_preimage_hash!(nodes[1], Some(recv_value_msat));
+       let (mut route, phantom_scid) = get_phantom_route!(nodes, recv_value_msat, channel);
+
+       // Route the HTLC through to the destination.
+       nodes[0].node.send_payment(&route, payment_hash, &Some(payment_secret), PaymentId(payment_hash.0)).unwrap();
+       check_added_monitors!(nodes[0], 1);
+       let update_0 = get_htlc_update_msgs!(nodes[0], nodes[1].node.get_our_node_id());
+       let mut update_add = update_0.update_add_htlcs[0].clone();
+
+       connect_blocks(&nodes[1], CLTV_FAR_FAR_AWAY);
+       nodes[1].node.handle_update_add_htlc(&nodes[0].node.get_our_node_id(), &update_add);
+       commitment_signed_dance!(nodes[1], nodes[0], &update_0.commitment_signed, false, true);
+
+       let update_1 = get_htlc_update_msgs!(nodes[1], nodes[0].node.get_our_node_id());
+       assert!(update_1.update_fail_htlcs.len() == 1);
+       let fail_msg = update_1.update_fail_htlcs[0].clone();
+       nodes[0].node.handle_update_fail_htlc(&nodes[1].node.get_our_node_id(), &fail_msg);
+       commitment_signed_dance!(nodes[0], nodes[1], update_1.commitment_signed, false);
+
+       // Ensure the payment fails with the expected error.
+       let mut fail_conditions = PaymentFailedConditions::new()
+               .blamed_scid(phantom_scid)
+               .expected_htlc_error_data(0x2000 | 2, &[]);
+       expect_payment_failed_conditions(&nodes[0], payment_hash, false, fail_conditions);
+}
+
 #[test]
 fn test_phantom_failure_too_low_recv_amt() {
        let chanmon_cfgs = create_chanmon_cfgs(2);