From: Matt Corallo <649246+TheBlueMatt@users.noreply.github.com>
Date: Wed, 3 Mar 2021 01:32:45 +0000 (-0500)
Subject: Merge pull request #646 from naumenkogs/2020-06-router-mpp
X-Git-Tag: v0.0.13~11
X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=commitdiff_plain;h=4894d52d30399c21b7994952a8de0d1d7848c58d;p=rust-lightning

Merge pull request #646 from naumenkogs/2020-06-router-mpp

MPP on the router side
---

4894d52d30399c21b7994952a8de0d1d7848c58d
diff --cc lightning/src/ln/channel.rs
index 2bbe367de,3c8be717f..633652222
--- a/lightning/src/ln/channel.rs
+++ b/lightning/src/ln/channel.rs
@@@ -3325,9 -3167,9 +3325,9 @@@ impl<Signer: Sign> Channel<Signer> 
  			// Upper bound by capacity. We make it a bit less than full capacity to prevent attempts
  			// to use full capacity. This is an effort to reduce routing failures, because in many cases
  			// channel might have been used to route very small values (either by honest users or as DoS).
- 			self.channel_value_satoshis * 9 / 10,
+ 			self.channel_value_satoshis * 1000 * 9 / 10,
  
 -			Channel::<ChanSigner>::get_holder_max_htlc_value_in_flight_msat(self.channel_value_satoshis)
 +			Channel::<Signer>::get_holder_max_htlc_value_in_flight_msat(self.channel_value_satoshis)
  		);
  	}
  
diff --cc lightning/src/routing/router.rs
index 9f1b60e0d,dd18f1bc7..7819b06c0
--- a/lightning/src/routing/router.rs
+++ b/lightning/src/routing/router.rs
@@@ -1278,49 -2149,1190 +2151,1235 @@@ mod tests 
  		assert_eq!(route.paths[0][1].node_features.le_flags(), &[0; 0]); // We dont pass flags in from invoices yet
  		assert_eq!(route.paths[0][1].channel_features.le_flags(), &[0; 0]); // We can't learn any flags from invoices, sadly
  	}
+ 
+ 	#[test]
+ 	fn available_amount_while_routing_test() {
+ 		// Tests whether we choose the correct available channel amount while routing.
+ 
+ 		let (secp_ctx, mut net_graph_msg_handler, chain_monitor, logger) = build_graph();
+ 		let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
+ 
+ 		// We will use a simple single-path route from
+ 		// our node to node2 via node0: channels {1, 3}.
+ 
+ 		// First disable all other paths.
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 2,
+ 			timestamp: 2,
+ 			flags: 2,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(100_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 12,
+ 			timestamp: 2,
+ 			flags: 2,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(100_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 
+ 		// Make the first channel (#1) very permissive,
+ 		// and we will be testing all limits on the second channel.
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 1,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(1_000_000_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 
+ 		// First, let's see if routing works if we have absolutely no idea about the available amount.
+ 		// In this case, it should be set to 250_000 sats.
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 3,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Absent,
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 
+ 		{
+ 			// Attempt to route more than available results in a failure.
+ 			if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, &Vec::new(), 250_000_001, 42, Arc::clone(&logger)) {
+ 				assert_eq!(err, "Failed to find a sufficient route to the given destination");
+ 			} else { panic!(); }
+ 		}
+ 
+ 		{
+ 			// Now, attempt to route an exact amount we have should be fine.
+ 			let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, &Vec::new(), 250_000_000, 42, Arc::clone(&logger)).unwrap();
+ 			assert_eq!(route.paths.len(), 1);
+ 			let path = route.paths.last().unwrap();
+ 			assert_eq!(path.len(), 2);
+ 			assert_eq!(path.last().unwrap().pubkey, nodes[2]);
+ 			assert_eq!(path.last().unwrap().fee_msat, 250_000_000);
+ 		}
+ 
+ 		// Check that setting outbound_capacity_msat in first_hops limits the channels.
+ 		// Disable channel #1 and use another first hop.
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 1,
+ 			timestamp: 3,
+ 			flags: 2,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(1_000_000_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 
+ 		// Now, limit the first_hop by the outbound_capacity_msat of 200_000 sats.
+ 		let our_chans = vec![channelmanager::ChannelDetails {
+ 			channel_id: [0; 32],
+ 			short_channel_id: Some(42),
+ 			remote_network_id: nodes[0].clone(),
+ 			counterparty_features: InitFeatures::from_le_bytes(vec![0b11]),
+ 			channel_value_satoshis: 0,
+ 			user_id: 0,
+ 			outbound_capacity_msat: 200_000_000,
+ 			inbound_capacity_msat: 0,
+ 			is_live: true,
+ 		}];
+ 
+ 		{
+ 			// Attempt to route more than available results in a failure.
+ 			if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 200_000_001, 42, Arc::clone(&logger)) {
+ 				assert_eq!(err, "Failed to find a sufficient route to the given destination");
+ 			} else { panic!(); }
+ 		}
+ 
+ 		{
+ 			// Now, attempt to route an exact amount we have should be fine.
+ 			let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], Some(&our_chans.iter().collect::<Vec<_>>()), &Vec::new(), 200_000_000, 42, Arc::clone(&logger)).unwrap();
+ 			assert_eq!(route.paths.len(), 1);
+ 			let path = route.paths.last().unwrap();
+ 			assert_eq!(path.len(), 2);
+ 			assert_eq!(path.last().unwrap().pubkey, nodes[2]);
+ 			assert_eq!(path.last().unwrap().fee_msat, 200_000_000);
+ 		}
+ 
+ 		// Enable channel #1 back.
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 1,
+ 			timestamp: 4,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(1_000_000_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 
+ 
+ 		// Now let's see if routing works if we know only htlc_maximum_msat.
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 3,
+ 			timestamp: 3,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(15_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 
+ 		{
+ 			// Attempt to route more than available results in a failure.
+ 			if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, &Vec::new(), 15_001, 42, Arc::clone(&logger)) {
+ 				assert_eq!(err, "Failed to find a sufficient route to the given destination");
+ 			} else { panic!(); }
+ 		}
+ 
+ 		{
+ 			// Now, attempt to route an exact amount we have should be fine.
+ 			let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, &Vec::new(), 15_000, 42, Arc::clone(&logger)).unwrap();
+ 			assert_eq!(route.paths.len(), 1);
+ 			let path = route.paths.last().unwrap();
+ 			assert_eq!(path.len(), 2);
+ 			assert_eq!(path.last().unwrap().pubkey, nodes[2]);
+ 			assert_eq!(path.last().unwrap().fee_msat, 15_000);
+ 		}
+ 
+ 		// Now let's see if routing works if we know only capacity from the UTXO.
+ 
+ 		// We can't change UTXO capacity on the fly, so we'll disable
+ 		// the existing channel and add another one with the capacity we need.
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 3,
+ 			timestamp: 4,
+ 			flags: 2,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Absent,
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 
+ 		let good_script = Builder::new().push_opcode(opcodes::all::OP_PUSHNUM_2)
+ 		.push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[0]).serialize())
+ 		.push_slice(&PublicKey::from_secret_key(&secp_ctx, &privkeys[2]).serialize())
+ 		.push_opcode(opcodes::all::OP_PUSHNUM_2)
+ 		.push_opcode(opcodes::all::OP_CHECKMULTISIG).into_script().to_v0_p2wsh();
+ 
+ 		*chain_monitor.utxo_ret.lock().unwrap() = Ok(TxOut { value: 15, script_pubkey: good_script.clone() });
+ 		net_graph_msg_handler.add_chain_access(Some(chain_monitor));
+ 
+ 		add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 333);
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 333,
+ 			timestamp: 1,
+ 			flags: 0,
+ 			cltv_expiry_delta: (3 << 8) | 1,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Absent,
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 333,
+ 			timestamp: 1,
+ 			flags: 1,
+ 			cltv_expiry_delta: (3 << 8) | 2,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Absent,
+ 			fee_base_msat: 100,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 
+ 		{
+ 			// Attempt to route more than available results in a failure.
+ 			if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, &Vec::new(), 15_001, 42, Arc::clone(&logger)) {
+ 				assert_eq!(err, "Failed to find a sufficient route to the given destination");
+ 			} else { panic!(); }
+ 		}
+ 
+ 		{
+ 			// Now, attempt to route an exact amount we have should be fine.
+ 			let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, &Vec::new(), 15_000, 42, Arc::clone(&logger)).unwrap();
+ 			assert_eq!(route.paths.len(), 1);
+ 			let path = route.paths.last().unwrap();
+ 			assert_eq!(path.len(), 2);
+ 			assert_eq!(path.last().unwrap().pubkey, nodes[2]);
+ 			assert_eq!(path.last().unwrap().fee_msat, 15_000);
+ 		}
+ 
+ 		// Now let's see if routing chooses htlc_maximum_msat over UTXO capacity.
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 333,
+ 			timestamp: 6,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(10_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 
+ 		{
+ 			// Attempt to route more than available results in a failure.
+ 			if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, &Vec::new(), 10_001, 42, Arc::clone(&logger)) {
+ 				assert_eq!(err, "Failed to find a sufficient route to the given destination");
+ 			} else { panic!(); }
+ 		}
+ 
+ 		{
+ 			// Now, attempt to route an exact amount we have should be fine.
+ 			let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, &Vec::new(), 10_000, 42, Arc::clone(&logger)).unwrap();
+ 			assert_eq!(route.paths.len(), 1);
+ 			let path = route.paths.last().unwrap();
+ 			assert_eq!(path.len(), 2);
+ 			assert_eq!(path.last().unwrap().pubkey, nodes[2]);
+ 			assert_eq!(path.last().unwrap().fee_msat, 10_000);
+ 		}
+ 	}
+ 
+ 	#[test]
+ 	fn available_liquidity_last_hop_test() {
+ 		// Check that available liquidity properly limits the path even when only
+ 		// one of the latter hops is limited.
+ 		let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
+ 		let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
+ 
+ 		// Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
+ 		// {12, 13, 11} have the capacities of 100, {6} has a capacity of 50.
+ 		// Total capacity: 50 sats.
+ 
+ 		// Disable other potential paths.
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 2,
+ 			timestamp: 2,
+ 			flags: 2,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(100_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 7,
+ 			timestamp: 2,
+ 			flags: 2,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(100_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 
+ 		// Limit capacities
+ 
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 12,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(100_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 13,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(100_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 6,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(50_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 11,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(100_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 		{
+ 			// Attempt to route more than available results in a failure.
+ 			if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3], None, &Vec::new(), 60_000, 42, Arc::clone(&logger)) {
+ 				assert_eq!(err, "Failed to find a sufficient route to the given destination");
+ 			} else { panic!(); }
+ 		}
+ 
+ 		{
+ 			// Now, attempt to route 49 sats (just a bit below the capacity).
+ 			let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3], None, &Vec::new(), 49_000, 42, Arc::clone(&logger)).unwrap();
+ 			assert_eq!(route.paths.len(), 1);
+ 			let mut total_amount_paid_msat = 0;
+ 			for path in &route.paths {
+ 				assert_eq!(path.len(), 4);
+ 				assert_eq!(path.last().unwrap().pubkey, nodes[3]);
+ 				total_amount_paid_msat += path.last().unwrap().fee_msat;
+ 			}
+ 			assert_eq!(total_amount_paid_msat, 49_000);
+ 		}
+ 
+ 		{
+ 			// Attempt to route an exact amount is also fine
+ 			let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3], None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
+ 			assert_eq!(route.paths.len(), 1);
+ 			let mut total_amount_paid_msat = 0;
+ 			for path in &route.paths {
+ 				assert_eq!(path.len(), 4);
+ 				assert_eq!(path.last().unwrap().pubkey, nodes[3]);
+ 				total_amount_paid_msat += path.last().unwrap().fee_msat;
+ 			}
+ 			assert_eq!(total_amount_paid_msat, 50_000);
+ 		}
+ 	}
+ 
+ 	#[test]
+ 	fn ignore_fee_first_hop_test() {
+ 		let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
+ 		let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
+ 
+ 		// Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 1,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(100_000),
+ 			fee_base_msat: 1_000_000,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 3,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(50_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 
+ 		{
+ 			let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, &Vec::new(), 50_000, 42, Arc::clone(&logger)).unwrap();
+ 			assert_eq!(route.paths.len(), 1);
+ 			let mut total_amount_paid_msat = 0;
+ 			for path in &route.paths {
+ 				assert_eq!(path.len(), 2);
+ 				assert_eq!(path.last().unwrap().pubkey, nodes[2]);
+ 				total_amount_paid_msat += path.last().unwrap().fee_msat;
+ 			}
+ 			assert_eq!(total_amount_paid_msat, 50_000);
+ 		}
+ 	}
+ 
+ 	#[test]
+ 	fn simple_mpp_route_test() {
+ 		let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
+ 		let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
+ 
+ 		// We need a route consisting of 3 paths:
+ 		// From our node to node2 via node0, node7, node1 (three paths one hop each).
+ 		// To achieve this, the amount being transferred should be around
+ 		// the total capacity of these 3 paths.
+ 
+ 		// First, we set limits on these (previously unlimited) channels.
+ 		// Their aggregate capacity will be 50 + 60 + 180 = 290 sats.
+ 
+ 		// Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50).
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 1,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(100_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 3,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(50_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 
+ 		// Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats
+ 		// (total limit 60).
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 12,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(60_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 13,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(60_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 
+ 		// Path via node1 is channels {2, 4}. Limit them to 200 and 180 sats
+ 		// (total capacity 180 sats).
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 2,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(200_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 4,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(180_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 
+ 		{
+ 			// Attempt to route more than available results in a failure.
+ 			if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, &Vec::new(), 300_000, 42, Arc::clone(&logger)) {
+ 				assert_eq!(err, "Failed to find a sufficient route to the given destination");
+ 			} else { panic!(); }
+ 		}
+ 
+ 		{
+ 			// Now, attempt to route 250 sats (just a bit below the capacity).
+ 			// Our algorithm should provide us with these 3 paths.
+ 			let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, &Vec::new(), 250_000, 42, Arc::clone(&logger)).unwrap();
+ 			assert_eq!(route.paths.len(), 3);
+ 			let mut total_amount_paid_msat = 0;
+ 			for path in &route.paths {
+ 				assert_eq!(path.len(), 2);
+ 				assert_eq!(path.last().unwrap().pubkey, nodes[2]);
+ 				total_amount_paid_msat += path.last().unwrap().fee_msat;
+ 			}
+ 			assert_eq!(total_amount_paid_msat, 250_000);
+ 		}
+ 
+ 		{
+ 			// Attempt to route an exact amount is also fine
+ 			let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, &Vec::new(), 290_000, 42, Arc::clone(&logger)).unwrap();
+ 			assert_eq!(route.paths.len(), 3);
+ 			let mut total_amount_paid_msat = 0;
+ 			for path in &route.paths {
+ 				assert_eq!(path.len(), 2);
+ 				assert_eq!(path.last().unwrap().pubkey, nodes[2]);
+ 				total_amount_paid_msat += path.last().unwrap().fee_msat;
+ 			}
+ 			assert_eq!(total_amount_paid_msat, 290_000);
+ 		}
+ 	}
+ 
+ 	#[test]
+ 	fn long_mpp_route_test() {
+ 		let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
+ 		let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
+ 
+ 		// We need a route consisting of 3 paths:
+ 		// From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
+ 		// Note that these paths overlap (channels 5, 12, 13).
+ 		// We will route 300 sats.
+ 		// Each path will have 100 sats capacity, those channels which
+ 		// are used twice will have 200 sats capacity.
+ 
+ 		// Disable other potential paths.
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 2,
+ 			timestamp: 2,
+ 			flags: 2,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(100_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 7,
+ 			timestamp: 2,
+ 			flags: 2,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(100_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 
+ 		// Path via {node0, node2} is channels {1, 3, 5}.
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 1,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(100_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 3,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(100_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 
+ 		// Capacity of 200 sats because this channel will be used by 3rd path as well.
+ 		add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 5,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(200_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 
+ 		// Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
+ 		// Add 100 sats to the capacities of {12, 13}, because these channels
+ 		// are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 12,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(200_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 13,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(200_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 6,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(100_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 11,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(100_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 
+ 		// Path via {node7, node2} is channels {12, 13, 5}.
+ 		// We already limited them to 200 sats (they are used twice for 100 sats).
+ 		// Nothing to do here.
+ 
+ 		{
+ 			// Attempt to route more than available results in a failure.
+ 			if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3], None, &Vec::new(), 350_000, 42, Arc::clone(&logger)) {
+ 				assert_eq!(err, "Failed to find a sufficient route to the given destination");
+ 			} else { panic!(); }
+ 		}
+ 
+ 		{
+ 			// Now, attempt to route 300 sats (exact amount we can route).
+ 			// Our algorithm should provide us with these 3 paths, 100 sats each.
+ 			let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3], None, &Vec::new(), 300_000, 42, Arc::clone(&logger)).unwrap();
+ 			assert_eq!(route.paths.len(), 3);
+ 
+ 			let mut total_amount_paid_msat = 0;
+ 			for path in &route.paths {
+ 				assert_eq!(path.last().unwrap().pubkey, nodes[3]);
+ 				total_amount_paid_msat += path.last().unwrap().fee_msat;
+ 			}
+ 			assert_eq!(total_amount_paid_msat, 300_000);
+ 		}
+ 
+ 	}
+ 
+ 	#[test]
+ 	fn mpp_cheaper_route_test() {
+ 		let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
+ 		let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
+ 
+ 		// This test checks that if we have two cheaper paths and one more expensive path,
+ 		// so that liquidity-wise any 2 of 3 combination is sufficient,
+ 		// two cheaper paths will be taken.
+ 		// These paths have equal available liquidity.
+ 
+ 		// We need a combination of 3 paths:
+ 		// From our node to node3 via {node0, node2}, {node7, node2, node4} and {node7, node2}.
+ 		// Note that these paths overlap (channels 5, 12, 13).
+ 		// Each path will have 100 sats capacity, those channels which
+ 		// are used twice will have 200 sats capacity.
+ 
+ 		// Disable other potential paths.
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 2,
+ 			timestamp: 2,
+ 			flags: 2,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(100_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 7,
+ 			timestamp: 2,
+ 			flags: 2,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(100_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 
+ 		// Path via {node0, node2} is channels {1, 3, 5}.
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 1,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(100_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 3,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(100_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 
+ 		// Capacity of 200 sats because this channel will be used by 3rd path as well.
+ 		add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 5,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(200_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 
+ 		// Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
+ 		// Add 100 sats to the capacities of {12, 13}, because these channels
+ 		// are also used for 3rd path. 100 sats for the rest. Total capacity: 100 sats.
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 12,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(200_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 13,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(200_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 6,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(100_000),
+ 			fee_base_msat: 1_000,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 11,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(100_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 
+ 		// Path via {node7, node2} is channels {12, 13, 5}.
+ 		// We already limited them to 200 sats (they are used twice for 100 sats).
+ 		// Nothing to do here.
+ 
+ 		{
+ 			// Now, attempt to route 180 sats.
+ 			// Our algorithm should provide us with these 2 paths.
+ 			let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3], None, &Vec::new(), 180_000, 42, Arc::clone(&logger)).unwrap();
+ 			assert_eq!(route.paths.len(), 2);
+ 
+ 			let mut total_value_transferred_msat = 0;
+ 			let mut total_paid_msat = 0;
+ 			for path in &route.paths {
+ 				assert_eq!(path.last().unwrap().pubkey, nodes[3]);
+ 				total_value_transferred_msat += path.last().unwrap().fee_msat;
+ 				for hop in path {
+ 					total_paid_msat += hop.fee_msat;
+ 				}
+ 			}
+ 			// If we paid fee, this would be higher.
+ 			assert_eq!(total_value_transferred_msat, 180_000);
+ 			let total_fees_paid = total_paid_msat - total_value_transferred_msat;
+ 			assert_eq!(total_fees_paid, 0);
+ 		}
+ 	}
+ 
+ 	#[test]
+ 	fn fees_on_mpp_route_test() {
+ 		// This test makes sure that MPP algorithm properly takes into account
+ 		// fees charged on the channels, by making the fees impactful:
+ 		// if the fee is not properly accounted for, the behavior is different.
+ 		let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
+ 		let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
+ 
+ 		// We need a route consisting of 2 paths:
+ 		// From our node to node3 via {node0, node2} and {node7, node2, node4}.
+ 		// We will route 200 sats, Each path will have 100 sats capacity.
+ 
+ 		// This test is not particularly stable: e.g.,
+ 		// there's a way to route via {node0, node2, node4}.
+ 		// It works while pathfinding is deterministic, but can be broken otherwise.
+ 		// It's fine to ignore this concern for now.
+ 
+ 		// Disable other potential paths.
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 2,
+ 			timestamp: 2,
+ 			flags: 2,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(100_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 7,
+ 			timestamp: 2,
+ 			flags: 2,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(100_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 
+ 		// Path via {node0, node2} is channels {1, 3, 5}.
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 1,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(100_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 3,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(100_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 
+ 		add_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 5,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(100_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 
+ 		// Path via {node7, node2, node4} is channels {12, 13, 6, 11}.
+ 		// All channels should be 100 sats capacity. But for the fee experiment,
+ 		// we'll add absolute fee of 150 sats paid for the use channel 6 (paid to node2 on channel 13).
+ 		// Since channel 12 allows to deliver only 250 sats to channel 13, channel 13 can transfer only
+ 		// 100 sats (and pay 150 sats in fees for the use of channel 6),
+ 		// so no matter how large are other channels,
+ 		// the whole path will be limited by 100 sats with just these 2 conditions:
+ 		// - channel 12 capacity is 250 sats
+ 		// - fee for channel 6 is 150 sats
+ 		// Let's test this by enforcing these 2 conditions and removing other limits.
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 12,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(250_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 13,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Absent,
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 6,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Absent,
+ 			fee_base_msat: 150_000,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 11,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Absent,
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 
+ 		{
+ 			// Attempt to route more than available results in a failure.
+ 			if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3], None, &Vec::new(), 210_000, 42, Arc::clone(&logger)) {
+ 				assert_eq!(err, "Failed to find a sufficient route to the given destination");
+ 			} else { panic!(); }
+ 		}
+ 
+ 		{
+ 			// Now, attempt to route 200 sats (exact amount we can route).
+ 			let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[3], None, &Vec::new(), 200_000, 42, Arc::clone(&logger)).unwrap();
+ 			assert_eq!(route.paths.len(), 2);
+ 
+ 			let mut total_amount_paid_msat = 0;
+ 			for path in &route.paths {
+ 				assert_eq!(path.last().unwrap().pubkey, nodes[3]);
+ 				total_amount_paid_msat += path.last().unwrap().fee_msat;
+ 			}
+ 			assert_eq!(total_amount_paid_msat, 200_000);
+ 		}
+ 
+ 	}
+ 
+ 	#[test]
+ 	fn drop_lowest_channel_mpp_route_test() {
+ 		// This test checks that low-capacity channel is dropped when after
+ 		// path finding we realize that we found more capacity than we need.
+ 		let (secp_ctx, net_graph_msg_handler, _, logger) = build_graph();
+ 		let (our_privkey, our_id, privkeys, nodes) = get_nodes(&secp_ctx);
+ 
+ 		// We need a route consisting of 3 paths:
+ 		// From our node to node2 via node0, node7, node1 (three paths one hop each).
+ 
+ 		// The first and the second paths should be sufficient, but the third should be
+ 		// cheaper, so that we select it but drop later.
+ 
+ 		// First, we set limits on these (previously unlimited) channels.
+ 		// Their aggregate capacity will be 50 + 60 + 20 = 130 sats.
+ 
+ 		// Path via node0 is channels {1, 3}. Limit them to 100 and 50 sats (total limit 50);
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 1,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(100_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[0], UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 3,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(50_000),
+ 			fee_base_msat: 100,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 
+ 		// Path via node7 is channels {12, 13}. Limit them to 60 and 60 sats (total limit 60);
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 12,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(60_000),
+ 			fee_base_msat: 100,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[7], UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 13,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(60_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 
+ 		// Path via node1 is channels {2, 4}. Limit them to 20 and 20 sats (total capacity 20 sats).
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 2,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(20_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 		update_channel(&net_graph_msg_handler, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
+ 			chain_hash: genesis_block(Network::Testnet).header.block_hash(),
+ 			short_channel_id: 4,
+ 			timestamp: 2,
+ 			flags: 0,
+ 			cltv_expiry_delta: 0,
+ 			htlc_minimum_msat: 0,
+ 			htlc_maximum_msat: OptionalField::Present(20_000),
+ 			fee_base_msat: 0,
+ 			fee_proportional_millionths: 0,
+ 			excess_data: Vec::new()
+ 		});
+ 
+ 		{
+ 			// Attempt to route more than available results in a failure.
+ 			if let Err(LightningError{err, action: ErrorAction::IgnoreError}) = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, &Vec::new(), 150_000, 42, Arc::clone(&logger)) {
+ 				assert_eq!(err, "Failed to find a sufficient route to the given destination");
+ 			} else { panic!(); }
+ 		}
+ 
+ 		{
+ 			// Now, attempt to route 125 sats (just a bit below the capacity of 3 channels).
+ 			// Our algorithm should provide us with these 3 paths.
+ 			let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, &Vec::new(), 125_000, 42, Arc::clone(&logger)).unwrap();
+ 			assert_eq!(route.paths.len(), 3);
+ 			let mut total_amount_paid_msat = 0;
+ 			for path in &route.paths {
+ 				assert_eq!(path.len(), 2);
+ 				assert_eq!(path.last().unwrap().pubkey, nodes[2]);
+ 				total_amount_paid_msat += path.last().unwrap().fee_msat;
+ 			}
+ 			assert_eq!(total_amount_paid_msat, 125_000);
+ 		}
+ 
+ 		{
+ 			// Attempt to route without the last small cheap channel
+ 			let route = get_route(&our_id, &net_graph_msg_handler.network_graph.read().unwrap(), &nodes[2], None, &Vec::new(), 90_000, 42, Arc::clone(&logger)).unwrap();
+ 			assert_eq!(route.paths.len(), 2);
+ 			let mut total_amount_paid_msat = 0;
+ 			for path in &route.paths {
+ 				assert_eq!(path.len(), 2);
+ 				assert_eq!(path.last().unwrap().pubkey, nodes[2]);
+ 				total_amount_paid_msat += path.last().unwrap().fee_msat;
+ 			}
+ 			assert_eq!(total_amount_paid_msat, 90_000);
+ 		}
+ 	}
+ 
  }
 +
 +#[cfg(all(test, feature = "unstable"))]
 +mod benches {
 +	use super::*;
 +	use util::logger::{Logger, Record};
 +
 +	use std::fs::File;
 +	use test::Bencher;
 +
 +	struct DummyLogger {}
 +	impl Logger for DummyLogger {
 +		fn log(&self, _record: &Record) {}
 +	}
 +
 +	#[bench]
 +	fn generate_routes(bench: &mut Bencher) {
 +		let mut d = File::open("net_graph-2021-02-12.bin").expect("Please fetch https://bitcoin.ninja/ldk-net_graph-879e309c128-2020-02-12.bin and place it at lightning/net_graph-2021-02-12.bin");
 +		let graph = NetworkGraph::read(&mut d).unwrap();
 +
 +		// First, get 100 (source, destination) pairs for which route-getting actually succeeds...
 +		let mut path_endpoints = Vec::new();
 +		let mut seed: usize = 0xdeadbeef;
 +		'load_endpoints: for _ in 0..100 {
 +			loop {
 +				seed *= 0xdeadbeef;
 +				let src = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
 +				seed *= 0xdeadbeef;
 +				let dst = graph.get_nodes().keys().skip(seed % graph.get_nodes().len()).next().unwrap();
 +				let amt = seed as u64 % 1_000_000;
 +				if get_route(src, &graph, dst, None, &[], amt, 42, &DummyLogger{}).is_ok() {
 +					path_endpoints.push((src, dst, amt));
 +					continue 'load_endpoints;
 +				}
 +			}
 +		}
 +
 +		// ...then benchmark finding paths between the nodes we learned.
 +		let mut idx = 0;
 +		bench.iter(|| {
 +			let (src, dst, amt) = path_endpoints[idx % path_endpoints.len()];
 +			assert!(get_route(src, &graph, dst, None, &[], amt, 42, &DummyLogger{}).is_ok());
 +			idx += 1;
 +		});
 +	}
 +}