Add a test for shutdown negotiaion funder restart and timeout

Author: TheBlueMatt

lightning/src/ln/channel.rs

@@ -435,9 +435,15 @@ pub(super) struct Channel<Signer: Sign> {
 	counterparty_max_commitment_tx_output: Mutex<(u64, u64)>,
 
 	last_sent_closing_fee: Option<(u64, Signature)>, // (fee, holder_sig)
-	closing_fee_limits: Option<(u64, u64)>,
 	target_closing_feerate_sats_per_1000_weight: Option<u32>,
 
+	/// The minimum and maximum absolute fee we are willing to place on the closing transaction.
+	/// These are set once we reach `closing_negotiation_ready`.
+	#[cfg(test)]
+	pub(crate) closing_fee_limits: Option<(u64, u64)>,
+	#[cfg(not(test))]
+	closing_fee_limits: Option<(u64, u64)>,
+
 	/// The hash of the block in which the funding transaction was included.
 	funding_tx_confirmed_in: Option<BlockHash>,
 	funding_tx_confirmation_height: u32,

lightning/src/ln/functional_test_utils.rs

@@ -416,12 +416,22 @@ macro_rules! get_htlc_update_msgs {
 	}
 }
 
+#[cfg(test)]
+macro_rules! get_channel_ref {
+	($node: expr, $lock: ident, $channel_id: expr) => {
+		{
+			$lock = $node.node.channel_state.lock().unwrap();
+			$lock.by_id.get_mut(&$channel_id).unwrap()
+		}
+	}
+}
+
 #[cfg(test)]
 macro_rules! get_feerate {
 	($node: expr, $channel_id: expr) => {
 		{
-			let chan_lock = $node.node.channel_state.lock().unwrap();
-			let chan = chan_lock.by_id.get(&$channel_id).unwrap();
+			let mut lock;
+			let chan = get_channel_ref!($node, lock, $channel_id);
 			chan.get_feerate()
 		}
 	}

lightning/src/ln/shutdown_tests.rs

@@ -722,3 +722,103 @@ fn test_invalid_shutdown_script() {
 	}
 	check_added_monitors!(nodes[0], 1);
 }
+
+fn do_test_closing_signed_reinit_timeout(timeout_step: u8) {
+	// The range-based closing signed negotiation allows the funder to restart the process with a
+	// new range if the previous range did not overlap. This allows implementations to request user
+	// intervention allowing users to enter a new fee range. We do not implement the sending side
+	// of this, instead opting to allow users to enter an explicit "willing to pay up to X to avoid
+	// force-closing" value and relying on that instead.
+	//
+	// Here we run test the fundee side of that restart mechanism, implementing the funder side of
+	// it manually.
+	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 mut nodes = create_network(2, &node_cfgs, &node_chanmgrs);
+	let chan_id = create_announced_chan_between_nodes(&nodes, 0, 1, InitFeatures::known(), InitFeatures::known()).2;
+
+	send_payment(&nodes[0], &[&nodes[1]], 8_000_000);
+
+	nodes[0].node.close_channel(&chan_id, None).unwrap();
+	let node_0_shutdown = get_event_msg!(nodes[0], MessageSendEvent::SendShutdown, nodes[1].node.get_our_node_id());
+	nodes[1].node.handle_shutdown(&nodes[0].node.get_our_node_id(), &InitFeatures::known(), &node_0_shutdown);
+	let node_1_shutdown = get_event_msg!(nodes[1], MessageSendEvent::SendShutdown, nodes[0].node.get_our_node_id());
+	nodes[0].node.handle_shutdown(&nodes[1].node.get_our_node_id(), &InitFeatures::known(), &node_1_shutdown);
+
+	{
+		// Now we set nodes[1] to require a relatively high feerate for closing. This should result
+		// in it rejecting nodes[0]'s initial closing_signed, giving nodes[0] a chance to try
+		// again.
+		let mut feerate_lock = chanmon_cfgs[1].fee_estimator.sat_per_kw.lock().unwrap();
+		*feerate_lock *= 10;
+	}
+
+	let mut node_0_closing_signed = get_event_msg!(nodes[0], MessageSendEvent::SendClosingSigned, nodes[1].node.get_our_node_id());
+	assert!(node_0_closing_signed.fee_satoshis <= 500);
+
+	if timeout_step != 0 {
+		nodes[1].node.handle_closing_signed(&nodes[0].node.get_our_node_id(), &node_0_closing_signed);
+		// At this point nodes[1] should send back a warning message indicating it disagrees with the
+		// given channel-closing fee. Currently we do not implement warning messages so instead we
+		// remain silent here.
+		assert!(nodes[1].node.get_and_clear_pending_msg_events().is_empty());
+
+		// Now deliver a mutated closing_signed indicating a higher acceptable fee range, which
+		// nodes[1] should happily accept and respond to.
+		node_0_closing_signed.fee_range.as_mut().unwrap().max_fee_satoshis *= 10;
+		{
+			let mut lock;
+			get_channel_ref!(nodes[0], lock, chan_id).closing_fee_limits.as_mut().unwrap().1 *= 10;
+		}
+		nodes[1].node.handle_closing_signed(&nodes[0].node.get_our_node_id(), &node_0_closing_signed);
+		let node_1_closing_signed = get_event_msg!(nodes[1], MessageSendEvent::SendClosingSigned, nodes[0].node.get_our_node_id());
+		nodes[0].node.handle_closing_signed(&nodes[1].node.get_our_node_id(), &node_1_closing_signed);
+		let node_0_2nd_closing_signed = get_closing_signed_broadcast!(nodes[0].node, nodes[1].node.get_our_node_id());
+		if timeout_step > 1 {
+			nodes[1].node.handle_closing_signed(&nodes[0].node.get_our_node_id(), &node_0_2nd_closing_signed.1.unwrap());
+		}
+	}
+
+	if timeout_step <= 1 {
+		assert!(nodes[1].tx_broadcaster.txn_broadcasted.lock().unwrap().is_empty());
+	} else {
+		assert_eq!(nodes[1].tx_broadcaster.txn_broadcasted.lock().unwrap().len(), 1);
+	}
+
+	nodes[1].node.timer_tick_occurred();
+	nodes[1].node.timer_tick_occurred();
+
+	let txn = nodes[1].tx_broadcaster.txn_broadcasted.lock().unwrap();
+	assert_eq!(txn.len(), 1);
+	assert_eq!(txn[0].output.len(), 2);
+
+	// If we timed out we should have a P2WPKH and P2WSH output, otherwise both should be P2WPKH.
+	if timeout_step <= 1 {
+		assert!((txn[0].output[0].script_pubkey.len() == 20+1+1 &&
+		         txn[0].output[1].script_pubkey.len() == 32+1+1) ||
+		        (txn[0].output[1].script_pubkey.len() == 20+1+1 &&
+		         txn[0].output[0].script_pubkey.len() == 32+1+1));
+		check_closed_broadcast!(nodes[1], true);
+		check_added_monitors!(nodes[1], 1);
+	} else {
+		assert_eq!(txn[0].output[0].script_pubkey.len(), 20+1+1);
+		assert_eq!(txn[0].output[1].script_pubkey.len(), 20+1+1);
+
+		let events = nodes[1].node.get_and_clear_pending_msg_events();
+		assert_eq!(events.len(), 1);
+		match events[0] {
+			MessageSendEvent::BroadcastChannelUpdate { ref msg } => {
+				assert_eq!(msg.contents.flags & 2, 2);
+			},
+			_ => panic!("Unexpected event"),
+		}
+	}
+}
+
+#[test]
+fn test_closing_signed_reinit_timeout() {
+	do_test_closing_signed_reinit_timeout(0);
+	do_test_closing_signed_reinit_timeout(1);
+	do_test_closing_signed_reinit_timeout(2);
+}