Merge pull request #231 from philipr-za/philip-204-check-commitment-transaction-fee

[rust-lightning] / src / ln / channel.rs

diff --git a/src/ln/channel.rs b/src/ln/channel.rs
index 6e8038da281ee5551c317ea55f47a1978446059d..d0a4644abdfa7164a25275ca2738f4a3e535b093 100644 (file)
--- a/src/ln/channel.rs
+++ b/src/ln/channel.rs
@@ -355,8 +355,9 @@ 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
@@ -1663,7 +1664,9 @@ 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
@@ -1674,6 +1677,16 @@ 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});
                }
@@ -1687,7 +1700,7 @@ 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);
@@ -1715,6 +1728,7 @@ 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.
@@ -2199,7 +2213,6 @@ 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(())