Ignore partially-pruned channels during routing

If we prune one side of a channel's `ChannelUpdateInfo` that means
the node hasn't been online for two weeks (as they haven't
generated a new `channel_update` in that time). In such cases, even
if we haven't yet pruned the channel entirely, we should definitely
not be treating these channels as candidates for routing.

Note that this requires some additional `channel_update`s in the
router tests, but all of the new ones are added as disabled
channels.

Fixes #1824

Author: TheBlueMatt

lightning/src/routing/gossip.rs

@@ -879,6 +879,7 @@ impl ChannelInfo {
 	/// Returns a [`DirectedChannelInfo`] for the channel directed to the given `target` from a
 	/// returned `source`, or `None` if `target` is not one of the channel's counterparties.
 	pub fn as_directed_to(&self, target: &NodeId) -> Option<(DirectedChannelInfo, &NodeId)> {
+		if self.one_to_two.is_none() || self.two_to_one.is_none() { return None; }
 		let (direction, source, outbound) = {
 			if target == &self.node_one {
 				(self.two_to_one.as_ref(), &self.node_two, false)
@@ -888,12 +889,14 @@ impl ChannelInfo {
 				return None;
 			}
 		};
-		direction.map(|dir| (DirectedChannelInfo::new(self, dir, outbound), source))
+		let dir = direction.expect("We checked that both directions are available at the start");
+		Some((DirectedChannelInfo::new(self, dir, outbound), source))
 	}
 
 	/// Returns a [`DirectedChannelInfo`] for the channel directed from the given `source` to a
 	/// returned `target`, or `None` if `source` is not one of the channel's counterparties.
 	pub fn as_directed_from(&self, source: &NodeId) -> Option<(DirectedChannelInfo, &NodeId)> {
+		if self.one_to_two.is_none() || self.two_to_one.is_none() { return None; }
 		let (direction, target, outbound) = {
 			if source == &self.node_one {
 				(self.one_to_two.as_ref(), &self.node_two, true)
@@ -903,7 +906,8 @@ impl ChannelInfo {
 				return None;
 			}
 		};
-		direction.map(|dir| (DirectedChannelInfo::new(self, dir, outbound), target))
+		let dir = direction.expect("We checked that both directions are available at the start");
+		Some((DirectedChannelInfo::new(self, dir, outbound), target))
 	}
 
 	/// Returns a [`ChannelUpdateInfo`] based on the direction implied by the channel_flag.

lightning/src/routing/router.rs

@@ -5466,6 +5466,18 @@ mod tests {
 			fee_proportional_millionths: 0,
 			excess_data: Vec::new()
 		});
+		update_channel(&gossip_sync, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
+			chain_hash: ChainHash::using_genesis_block(Network::Testnet),
+			short_channel_id: 5,
+			timestamp: 2,
+			flags: 3, // disable direction 1
+			cltv_expiry_delta: 0,
+			htlc_minimum_msat: 0,
+			htlc_maximum_msat: 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
@@ -5643,6 +5655,18 @@ mod tests {
 			fee_proportional_millionths: 0,
 			excess_data: Vec::new()
 		});
+		update_channel(&gossip_sync, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
+			chain_hash: ChainHash::using_genesis_block(Network::Testnet),
+			short_channel_id: 5,
+			timestamp: 2,
+			flags: 3, // disable direction 1
+			cltv_expiry_delta: 0,
+			htlc_minimum_msat: 0,
+			htlc_maximum_msat: 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
@@ -5816,6 +5840,18 @@ mod tests {
 			fee_proportional_millionths: 0,
 			excess_data: Vec::new()
 		});
+		update_channel(&gossip_sync, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
+			chain_hash: ChainHash::using_genesis_block(Network::Testnet),
+			short_channel_id: 5,
+			timestamp: 2,
+			flags: 3, // Disable direction 1
+			cltv_expiry_delta: 0,
+			htlc_minimum_msat: 0,
+			htlc_maximum_msat: 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,
@@ -6208,92 +6244,104 @@ mod tests {
 		let payment_params = PaymentParameters::from_node_id(nodes[6], 42);
 
 		add_channel(&gossip_sync, &secp_ctx, &our_privkey, &privkeys[1], ChannelFeatures::from_le_bytes(id_to_feature_flags(6)), 6);
-		update_channel(&gossip_sync, &secp_ctx, &our_privkey, UnsignedChannelUpdate {
-			chain_hash: ChainHash::using_genesis_block(Network::Testnet),
-			short_channel_id: 6,
-			timestamp: 1,
-			flags: 0,
-			cltv_expiry_delta: (6 << 4) | 0,
-			htlc_minimum_msat: 0,
-			htlc_maximum_msat: MAX_VALUE_MSAT,
-			fee_base_msat: 0,
-			fee_proportional_millionths: 0,
-			excess_data: Vec::new()
-		});
+		for (key, flags) in [(&our_privkey, 0), (&privkeys[1], 3)] {
+			update_channel(&gossip_sync, &secp_ctx, key, UnsignedChannelUpdate {
+				chain_hash: ChainHash::using_genesis_block(Network::Testnet),
+				short_channel_id: 6,
+				timestamp: 1,
+				flags,
+				cltv_expiry_delta: (6 << 4) | 0,
+				htlc_minimum_msat: 0,
+				htlc_maximum_msat: MAX_VALUE_MSAT,
+				fee_base_msat: 0,
+				fee_proportional_millionths: 0,
+				excess_data: Vec::new()
+			});
+		}
 		add_or_update_node(&gossip_sync, &secp_ctx, &privkeys[1], NodeFeatures::from_le_bytes(id_to_feature_flags(1)), 0);
 
 		add_channel(&gossip_sync, &secp_ctx, &privkeys[1], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(5)), 5);
-		update_channel(&gossip_sync, &secp_ctx, &privkeys[1], UnsignedChannelUpdate {
-			chain_hash: ChainHash::using_genesis_block(Network::Testnet),
-			short_channel_id: 5,
-			timestamp: 1,
-			flags: 0,
-			cltv_expiry_delta: (5 << 4) | 0,
-			htlc_minimum_msat: 0,
-			htlc_maximum_msat: MAX_VALUE_MSAT,
-			fee_base_msat: 100,
-			fee_proportional_millionths: 0,
-			excess_data: Vec::new()
-		});
+		for (key, flags) in [(&privkeys[1], 0), (&privkeys[4], 3)] {
+			update_channel(&gossip_sync, &secp_ctx, key, UnsignedChannelUpdate {
+				chain_hash: ChainHash::using_genesis_block(Network::Testnet),
+				short_channel_id: 5,
+				timestamp: 1,
+				flags,
+				cltv_expiry_delta: (5 << 4) | 0,
+				htlc_minimum_msat: 0,
+				htlc_maximum_msat: MAX_VALUE_MSAT,
+				fee_base_msat: 100,
+				fee_proportional_millionths: 0,
+				excess_data: Vec::new()
+			});
+		}
 		add_or_update_node(&gossip_sync, &secp_ctx, &privkeys[4], NodeFeatures::from_le_bytes(id_to_feature_flags(4)), 0);
 
 		add_channel(&gossip_sync, &secp_ctx, &privkeys[4], &privkeys[3], ChannelFeatures::from_le_bytes(id_to_feature_flags(4)), 4);
-		update_channel(&gossip_sync, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
-			chain_hash: ChainHash::using_genesis_block(Network::Testnet),
-			short_channel_id: 4,
-			timestamp: 1,
-			flags: 0,
-			cltv_expiry_delta: (4 << 4) | 0,
-			htlc_minimum_msat: 0,
-			htlc_maximum_msat: MAX_VALUE_MSAT,
-			fee_base_msat: 0,
-			fee_proportional_millionths: 0,
-			excess_data: Vec::new()
-		});
+		for (key, flags) in [(&privkeys[4], 0), (&privkeys[3], 3)] {
+			update_channel(&gossip_sync, &secp_ctx, key, UnsignedChannelUpdate {
+				chain_hash: ChainHash::using_genesis_block(Network::Testnet),
+				short_channel_id: 4,
+				timestamp: 1,
+				flags,
+				cltv_expiry_delta: (4 << 4) | 0,
+				htlc_minimum_msat: 0,
+				htlc_maximum_msat: MAX_VALUE_MSAT,
+				fee_base_msat: 0,
+				fee_proportional_millionths: 0,
+				excess_data: Vec::new()
+			});
+		}
 		add_or_update_node(&gossip_sync, &secp_ctx, &privkeys[3], NodeFeatures::from_le_bytes(id_to_feature_flags(3)), 0);
 
 		add_channel(&gossip_sync, &secp_ctx, &privkeys[3], &privkeys[2], ChannelFeatures::from_le_bytes(id_to_feature_flags(3)), 3);
-		update_channel(&gossip_sync, &secp_ctx, &privkeys[3], UnsignedChannelUpdate {
-			chain_hash: ChainHash::using_genesis_block(Network::Testnet),
-			short_channel_id: 3,
-			timestamp: 1,
-			flags: 0,
-			cltv_expiry_delta: (3 << 4) | 0,
-			htlc_minimum_msat: 0,
-			htlc_maximum_msat: MAX_VALUE_MSAT,
-			fee_base_msat: 0,
-			fee_proportional_millionths: 0,
-			excess_data: Vec::new()
-		});
+		for (key, flags) in [(&privkeys[3], 0), (&privkeys[2], 3)] {
+			update_channel(&gossip_sync, &secp_ctx, key, UnsignedChannelUpdate {
+				chain_hash: ChainHash::using_genesis_block(Network::Testnet),
+				short_channel_id: 3,
+				timestamp: 1,
+				flags,
+				cltv_expiry_delta: (3 << 4) | 0,
+				htlc_minimum_msat: 0,
+				htlc_maximum_msat: MAX_VALUE_MSAT,
+				fee_base_msat: 0,
+				fee_proportional_millionths: 0,
+				excess_data: Vec::new()
+			});
+		}
 		add_or_update_node(&gossip_sync, &secp_ctx, &privkeys[2], NodeFeatures::from_le_bytes(id_to_feature_flags(2)), 0);
 
 		add_channel(&gossip_sync, &secp_ctx, &privkeys[2], &privkeys[4], ChannelFeatures::from_le_bytes(id_to_feature_flags(2)), 2);
-		update_channel(&gossip_sync, &secp_ctx, &privkeys[2], UnsignedChannelUpdate {
-			chain_hash: ChainHash::using_genesis_block(Network::Testnet),
-			short_channel_id: 2,
-			timestamp: 1,
-			flags: 0,
-			cltv_expiry_delta: (2 << 4) | 0,
-			htlc_minimum_msat: 0,
-			htlc_maximum_msat: MAX_VALUE_MSAT,
-			fee_base_msat: 0,
-			fee_proportional_millionths: 0,
-			excess_data: Vec::new()
-		});
+		for (key, flags) in [(&privkeys[2], 0), (&privkeys[4], 3)] {
+			update_channel(&gossip_sync, &secp_ctx, key, UnsignedChannelUpdate {
+				chain_hash: ChainHash::using_genesis_block(Network::Testnet),
+				short_channel_id: 2,
+				timestamp: 1,
+				flags,
+				cltv_expiry_delta: (2 << 4) | 0,
+				htlc_minimum_msat: 0,
+				htlc_maximum_msat: MAX_VALUE_MSAT,
+				fee_base_msat: 0,
+				fee_proportional_millionths: 0,
+				excess_data: Vec::new()
+			});
+		}
 
 		add_channel(&gossip_sync, &secp_ctx, &privkeys[4], &privkeys[6], ChannelFeatures::from_le_bytes(id_to_feature_flags(1)), 1);
-		update_channel(&gossip_sync, &secp_ctx, &privkeys[4], UnsignedChannelUpdate {
-			chain_hash: ChainHash::using_genesis_block(Network::Testnet),
-			short_channel_id: 1,
-			timestamp: 1,
-			flags: 0,
-			cltv_expiry_delta: (1 << 4) | 0,
-			htlc_minimum_msat: 100,
-			htlc_maximum_msat: MAX_VALUE_MSAT,
-			fee_base_msat: 0,
-			fee_proportional_millionths: 0,
-			excess_data: Vec::new()
-		});
+		for (key, flags) in [(&privkeys[4], 0), (&privkeys[6], 3)] {
+			update_channel(&gossip_sync, &secp_ctx, key, UnsignedChannelUpdate {
+				chain_hash: ChainHash::using_genesis_block(Network::Testnet),
+				short_channel_id: 1,
+				timestamp: 1,
+				flags,
+				cltv_expiry_delta: (1 << 4) | 0,
+				htlc_minimum_msat: 100,
+				htlc_maximum_msat: MAX_VALUE_MSAT,
+				fee_base_msat: 0,
+				fee_proportional_millionths: 0,
+				excess_data: Vec::new()
+			});
+		}
 		add_or_update_node(&gossip_sync, &secp_ctx, &privkeys[6], NodeFeatures::from_le_bytes(id_to_feature_flags(6)), 0);
 
 		{