Check affordability of new fee during update_fee call #204
authorPhilip Robinson <simian@tari.com>
Tue, 30 Oct 2018 12:31:57 +0000 (14:31 +0200)
committerPhilip Robinson <simian@tari.com>
Wed, 14 Nov 2018 12:14:10 +0000 (14:14 +0200)
src/ln/channel.rs
src/ln/channelmanager.rs

index b9a81f6ebc0465cf34396eb44073b790fd7c3925..57070e41d5fe27aa2085a4155952a9618a218a34 100644 (file)
@@ -357,8 +357,9 @@ const UNCONF_THRESHOLD: u32 = 6;
 const BREAKDOWN_TIMEOUT: u16 = 6 * 24 * 7; //TODO?
 /// The amount of time we're willing to wait to claim money back to us
 const MAX_LOCAL_BREAKDOWN_TIMEOUT: u16 = 6 * 24 * 14;
-const COMMITMENT_TX_BASE_WEIGHT: u64 = 724;
-const COMMITMENT_TX_WEIGHT_PER_HTLC: u64 = 172;
+/// Exposing these two constants for use in test in ChannelMonitor
+pub const COMMITMENT_TX_BASE_WEIGHT: u64 = 724;
+pub const COMMITMENT_TX_WEIGHT_PER_HTLC: u64 = 172;
 const SPENDING_INPUT_FOR_A_OUTPUT_WEIGHT: u64 = 79; // prevout: 36, nSequence: 4, script len: 1, witness lengths: (3+1)/4, sig: 73/4, if-selector: 1, redeemScript: (6 ops + 2*33 pubkeys + 1*2 delay)/4
 const B_OUTPUT_PLUS_SPENDING_INPUT_WEIGHT: u64 = 104; // prevout: 40, nSequence: 4, script len: 1, witness lengths: 3/4, sig: 73/4, pubkey: 33/4, output: 31 (TODO: Wrong? Useless?)
 /// Maximmum `funding_satoshis` value, according to the BOLT #2 specification
@@ -1653,7 +1654,9 @@ impl Channel {
 
                let local_keys = self.build_local_transaction_keys(self.cur_local_commitment_transaction_number)?;
 
+               let mut update_fee = false;
                let feerate_per_kw = if !self.channel_outbound && self.pending_update_fee.is_some() {
+                       update_fee = true;
                        self.pending_update_fee.unwrap()
                } else {
                        self.feerate_per_kw
@@ -1664,6 +1667,16 @@ impl Channel {
                let local_sighash = Message::from_slice(&bip143::SighashComponents::new(&local_commitment_tx.0).sighash_all(&local_commitment_tx.0.input[0], &funding_script, self.channel_value_satoshis)[..]).unwrap();
                secp_call!(self.secp_ctx.verify(&local_sighash, &msg.signature, &self.their_funding_pubkey.unwrap()), "Invalid commitment tx signature from peer", self.channel_id());
 
+               //If channel fee was updated by funder confirm funder can afford the new fee rate when applied to the current local commitment transaction
+               if update_fee {
+                       let num_htlcs = local_commitment_tx.1.len();
+                       let total_fee: u64 = feerate_per_kw as u64 * (COMMITMENT_TX_BASE_WEIGHT + (num_htlcs as u64) * COMMITMENT_TX_WEIGHT_PER_HTLC) / 1000;
+
+                       if self.channel_value_satoshis - self.value_to_self_msat / 1000 < total_fee + self.their_channel_reserve_satoshis {
+                               return Err(HandleError { err: "Funding remote cannot afford proposed new fee", action: Some(ErrorAction::DisconnectPeer { msg: None }) });
+                       }
+               }
+
                if msg.htlc_signatures.len() != local_commitment_tx.1.len() {
                        return Err(HandleError{err: "Got wrong number of HTLC signatures from remote", action: None});
                }
@@ -1677,7 +1690,7 @@ impl Channel {
                        let mut htlc_tx = self.build_htlc_transaction(&local_commitment_txid, htlc, true, &local_keys, feerate_per_kw);
                        let htlc_redeemscript = chan_utils::get_htlc_redeemscript(&htlc, &local_keys);
                        let htlc_sighash = Message::from_slice(&bip143::SighashComponents::new(&htlc_tx).sighash_all(&htlc_tx.input[0], &htlc_redeemscript, htlc.amount_msat / 1000)[..]).unwrap();
-                       secp_call!(self.secp_ctx.verify(&htlc_sighash, &msg.htlc_signatures[idx], &local_keys.b_htlc_key), "Invalid HTLC tx siganture from peer", self.channel_id());
+                       secp_call!(self.secp_ctx.verify(&htlc_sighash, &msg.htlc_signatures[idx], &local_keys.b_htlc_key), "Invalid HTLC tx signature from peer", self.channel_id());
                        let htlc_sig = if htlc.offered {
                                let htlc_sig = self.sign_htlc_transaction(&mut htlc_tx, &msg.htlc_signatures[idx], &None, htlc, &local_keys)?;
                                new_local_commitment_txn.push(htlc_tx);
@@ -1705,6 +1718,7 @@ impl Channel {
                                }
                        }
                }
+
                if self.channel_state & (ChannelState::MonitorUpdateFailed as u32) == 0 {
                        // This is a response to our post-monitor-failed unfreeze messages, so we can clear the
                        // monitor_pending_order requirement as we won't re-send the monitor_pending messages.
@@ -2188,7 +2202,6 @@ impl Channel {
                        return Err(ChannelError::Close("Peer sent update_fee when we needed a channel_reestablish"));
                }
                Channel::check_remote_fee(fee_estimator, msg.feerate_per_kw)?;
-
                self.pending_update_fee = Some(msg.feerate_per_kw as u64);
                self.channel_update_count += 1;
                Ok(())
index a650c89bb44668149cb305a4c0f4b35d307ad279..0600c4e703cd82bdd3bb98a83f963f2e95817054 100644 (file)
@@ -3212,6 +3212,7 @@ mod tests {
        use chain::chaininterface::{ChainListener, ChainWatchInterface};
        use chain::keysinterface::KeysInterface;
        use chain::keysinterface;
+       use ln::channel::{COMMITMENT_TX_BASE_WEIGHT, COMMITMENT_TX_WEIGHT_PER_HTLC};
        use ln::channelmanager::{ChannelManager,ChannelManagerReadArgs,OnionKeys,PaymentFailReason,RAACommitmentOrder};
        use ln::channelmonitor::{ChannelMonitor, ChannelMonitorUpdateErr, CLTV_CLAIM_BUFFER, HTLC_FAIL_TIMEOUT_BLOCKS, ManyChannelMonitor};
        use ln::router::{Route, RouteHop, Router};
@@ -3501,6 +3502,17 @@ mod tests {
                }
        }
 
+       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();
+                               chan.get_feerate()
+                       }
+               }
+       }
+
+
        fn create_chan_between_nodes_with_value_init(node_a: &Node, node_b: &Node, channel_value: u64, push_msat: u64) -> Transaction {
                node_a.node.create_channel(node_b.node.get_our_node_id(), channel_value, push_msat, 42).unwrap();
                node_b.node.handle_open_channel(&node_a.node.get_our_node_id(), &get_event_msg!(node_a, MessageSendEvent::SendOpenChannel, node_b.node.get_our_node_id())).unwrap();
@@ -4134,14 +4146,6 @@ mod tests {
                let chan = create_announced_chan_between_nodes(&nodes, 0, 1);
                let channel_id = chan.2;
 
-               macro_rules! get_feerate {
-                       ($node: expr) => {{
-                               let chan_lock = $node.node.channel_state.lock().unwrap();
-                               let chan = chan_lock.by_id.get(&channel_id).unwrap();
-                               chan.get_feerate()
-                       }}
-               }
-
                // balancing
                send_payment(&nodes[0], &vec!(&nodes[1])[..], 8000000);
 
@@ -4163,7 +4167,7 @@ mod tests {
                // (6) RAA is delivered                  ->
 
                // First nodes[0] generates an update_fee
-               nodes[0].node.update_fee(channel_id, get_feerate!(nodes[0]) + 20).unwrap();
+               nodes[0].node.update_fee(channel_id, get_feerate!(nodes[0], channel_id) + 20).unwrap();
                check_added_monitors!(nodes[0], 1);
 
                let events_0 = nodes[0].node.get_and_clear_pending_msg_events();
@@ -4252,19 +4256,11 @@ mod tests {
                let chan = create_announced_chan_between_nodes(&nodes, 0, 1);
                let channel_id = chan.2;
 
-               macro_rules! get_feerate {
-                       ($node: expr) => {{
-                               let chan_lock = $node.node.channel_state.lock().unwrap();
-                               let chan = chan_lock.by_id.get(&channel_id).unwrap();
-                               chan.get_feerate()
-                       }}
-               }
-
                // balancing
                send_payment(&nodes[0], &vec!(&nodes[1])[..], 8000000);
 
                // First nodes[0] generates an update_fee
-               nodes[0].node.update_fee(channel_id, get_feerate!(nodes[0]) + 20).unwrap();
+               nodes[0].node.update_fee(channel_id, get_feerate!(nodes[0], channel_id) + 20).unwrap();
                check_added_monitors!(nodes[0], 1);
 
                let events_0 = nodes[0].node.get_and_clear_pending_msg_events();
@@ -4310,14 +4306,6 @@ mod tests {
                let chan = create_announced_chan_between_nodes(&nodes, 0, 1);
                let channel_id = chan.2;
 
-               macro_rules! get_feerate {
-                       ($node: expr) => {{
-                               let chan_lock = $node.node.channel_state.lock().unwrap();
-                               let chan = chan_lock.by_id.get(&channel_id).unwrap();
-                               chan.get_feerate()
-                       }}
-               }
-
                // A                                        B
                // update_fee/commitment_signed          ->
                //                                       .- send (1) RAA and (2) commitment_signed
@@ -4338,7 +4326,7 @@ mod tests {
                // revoke_and_ack                        ->
 
                // First nodes[0] generates an update_fee
-               let initial_feerate = get_feerate!(nodes[0]);
+               let initial_feerate = get_feerate!(nodes[0], channel_id);
                nodes[0].node.update_fee(channel_id, initial_feerate + 20).unwrap();
                check_added_monitors!(nodes[0], 1);
 
@@ -4422,16 +4410,8 @@ mod tests {
                let chan = create_announced_chan_between_nodes(&nodes, 0, 1);
                let channel_id = chan.2;
 
-               macro_rules! get_feerate {
-                       ($node: expr) => {{
-                               let chan_lock = $node.node.channel_state.lock().unwrap();
-                               let chan = chan_lock.by_id.get(&channel_id).unwrap();
-                               chan.get_feerate()
-                       }}
-               }
-
-               let feerate = get_feerate!(nodes[0]);
-               nodes[0].node.update_fee(channel_id, feerate+20).unwrap();
+               let feerate = get_feerate!(nodes[0], channel_id);
+               nodes[0].node.update_fee(channel_id, feerate+25).unwrap();
                check_added_monitors!(nodes[0], 1);
 
                let events_0 = nodes[0].node.get_and_clear_pending_msg_events();
@@ -4462,24 +4442,69 @@ mod tests {
                check_added_monitors!(nodes[1], 1);
        }
 
+       #[test]
+       fn test_update_fee_that_funder_cannot_afford() {
+               let mut nodes = create_network(2);
+               let channel_value = 1888;
+               let chan = create_announced_chan_between_nodes_with_value(&nodes, 0, 1, channel_value, 700000);
+               let channel_id = chan.2;
+
+               let feerate = 260;
+               nodes[0].node.update_fee(channel_id, feerate).unwrap();
+               check_added_monitors!(nodes[0], 1);
+               let update_msg = get_htlc_update_msgs!(nodes[0], nodes[1].node.get_our_node_id());
+
+               nodes[1].node.handle_update_fee(&nodes[0].node.get_our_node_id(), &update_msg.update_fee.unwrap()).unwrap();
+
+               commitment_signed_dance!(nodes[1], nodes[0], update_msg.commitment_signed, false);
+
+               //Confirm that the new fee based on the last local commitment txn is what we expected based on the feerate of 260 set above.
+               //This value results in a fee that is exactly what the funder can afford (277 sat + 1000 sat channel reserve)
+               {
+                       let chan_lock = nodes[1].node.channel_state.lock().unwrap();
+                       let chan = chan_lock.by_id.get(&channel_id).unwrap();
+
+                       //We made sure neither party's funds are below the dust limit so -2 non-HTLC txns from number of outputs
+                       let num_htlcs = chan.last_local_commitment_txn[0].output.len() - 2;
+                       let total_fee: u64 = feerate * (COMMITMENT_TX_BASE_WEIGHT + (num_htlcs as u64) * COMMITMENT_TX_WEIGHT_PER_HTLC) / 1000;
+                       let mut actual_fee = chan.last_local_commitment_txn[0].output.iter().fold(0, |acc, output| acc + output.value);
+                       actual_fee = channel_value - actual_fee;
+                       assert_eq!(total_fee, actual_fee);
+               } //drop the mutex
+
+               //Add 2 to the previous fee rate to the final fee increases by 1 (with no HTLCs the fee is essentially
+               //fee_rate*(724/1000) so the increment of 1*0.724 is rounded back down)
+               nodes[0].node.update_fee(channel_id, feerate+2).unwrap();
+               check_added_monitors!(nodes[0], 1);
+
+               let update2_msg = get_htlc_update_msgs!(nodes[0], nodes[1].node.get_our_node_id());
+
+               nodes[1].node.handle_update_fee(&nodes[0].node.get_our_node_id(), &update2_msg.update_fee.unwrap());
+
+               //While producing the commitment_signed response after handling a received update_fee request the
+               //check to see if the funder, who sent the update_fee request, can afford the new fee (funder_balance >= fee+channel_reserve)
+               //Should produce and error.
+               let err = nodes[1].node.handle_commitment_signed(&nodes[0].node.get_our_node_id(), &update2_msg.commitment_signed).unwrap_err();
+
+               assert!(match err.err {
+                       "Funding remote cannot afford proposed new fee" => true,
+                       _ => false,
+               });
+
+               //clear the message we could not handle
+               nodes[1].node.get_and_clear_pending_msg_events();
+       }
+
        #[test]
        fn test_update_fee_with_fundee_update_add_htlc() {
                let mut nodes = create_network(2);
                let chan = create_announced_chan_between_nodes(&nodes, 0, 1);
                let channel_id = chan.2;
 
-               macro_rules! get_feerate {
-                       ($node: expr) => {{
-                               let chan_lock = $node.node.channel_state.lock().unwrap();
-                               let chan = chan_lock.by_id.get(&channel_id).unwrap();
-                               chan.get_feerate()
-                       }}
-               }
-
                // balancing
                send_payment(&nodes[0], &vec!(&nodes[1])[..], 8000000);
 
-               let feerate = get_feerate!(nodes[0]);
+               let feerate = get_feerate!(nodes[0], channel_id);
                nodes[0].node.update_fee(channel_id, feerate+20).unwrap();
                check_added_monitors!(nodes[0], 1);
 
@@ -4577,14 +4602,6 @@ mod tests {
                let chan = create_announced_chan_between_nodes(&nodes, 0, 1);
                let channel_id = chan.2;
 
-               macro_rules! get_feerate {
-                       ($node: expr) => {{
-                               let chan_lock = $node.node.channel_state.lock().unwrap();
-                               let chan = chan_lock.by_id.get(&channel_id).unwrap();
-                               chan.get_feerate()
-                       }}
-               }
-
                // A                                        B
                // (1) update_fee/commitment_signed      ->
                //                                       <- (2) revoke_and_ack
@@ -4600,7 +4617,7 @@ mod tests {
                // revoke_and_ack                        ->
 
                // Create and deliver (1)...
-               let feerate = get_feerate!(nodes[0]);
+               let feerate = get_feerate!(nodes[0], channel_id);
                nodes[0].node.update_fee(channel_id, feerate+20).unwrap();
                check_added_monitors!(nodes[0], 1);
 
@@ -4674,8 +4691,8 @@ mod tests {
                check_added_monitors!(nodes[1], 1);
                assert!(nodes[1].node.get_and_clear_pending_msg_events().is_empty());
 
-               assert_eq!(get_feerate!(nodes[0]), feerate + 30);
-               assert_eq!(get_feerate!(nodes[1]), feerate + 30);
+               assert_eq!(get_feerate!(nodes[0], channel_id), feerate + 30);
+               assert_eq!(get_feerate!(nodes[1], channel_id), feerate + 30);
                close_channel(&nodes[0], &nodes[1], &chan.2, chan.3, true);
        }