Merge pull request #233 from TheBlueMatt/2018-10-shutdown-updates
[rust-lightning] / src / ln / channel.rs
index 1fbc605bb3baa34491bf0d4d034f0a3de805503f..b9a81f6ebc0465cf34396eb44073b790fd7c3925 100644 (file)
@@ -1553,6 +1553,12 @@ impl Channel {
 
                //TODO: Check msg.cltv_expiry further? Do this in channel manager?
 
+               if self.channel_state & ChannelState::LocalShutdownSent as u32 != 0 {
+                       if let PendingHTLCStatus::Forward(_) = pending_forward_state {
+                               panic!("ChannelManager shouldn't be trying to add a forwardable HTLC after we've started closing");
+                       }
+               }
+
                // Now update local state:
                self.next_remote_htlc_id += 1;
                self.pending_inbound_htlcs.push(InboundHTLCOutput {
@@ -1632,13 +1638,16 @@ impl Channel {
                self.mark_outbound_htlc_removed(msg.htlc_id, None, Some(fail_reason))
        }
 
-       pub fn commitment_signed(&mut self, msg: &msgs::CommitmentSigned) -> Result<(msgs::RevokeAndACK, Option<msgs::CommitmentSigned>, ChannelMonitor), HandleError> {
+       pub fn commitment_signed(&mut self, msg: &msgs::CommitmentSigned, fee_estimator: &FeeEstimator) -> Result<(msgs::RevokeAndACK, Option<msgs::CommitmentSigned>, Option<msgs::ClosingSigned>, ChannelMonitor), HandleError> {
                if (self.channel_state & (ChannelState::ChannelFunded as u32)) != (ChannelState::ChannelFunded as u32) {
                        return Err(HandleError{err: "Got commitment signed message when channel was not in an operational state", action: None});
                }
                if self.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
                        return Err(HandleError{err: "Peer sent commitment_signed when we needed a channel_reestablish", action: Some(msgs::ErrorAction::SendErrorMessage{msg: msgs::ErrorMessage{data: "Peer sent commitment_signed when we needed a channel_reestablish".to_string(), channel_id: msg.channel_id}})});
                }
+               if self.channel_state & BOTH_SIDES_SHUTDOWN_MASK == BOTH_SIDES_SHUTDOWN_MASK && self.last_sent_closing_fee.is_some() {
+                       return Err(HandleError{err: "Peer sent commitment_signed after we'd started exchanging closing_signeds", action: Some(msgs::ErrorAction::SendErrorMessage{msg: msgs::ErrorMessage{data: "Peer sent commitment_signed after we'd started exchanging closing_signeds".to_string(), channel_id: msg.channel_id}})});
+               }
 
                let funding_script = self.get_funding_redeemscript();
 
@@ -1730,19 +1739,21 @@ impl Channel {
                        return Err(HandleError{err: "Previous monitor update failure prevented generation of RAA", action: Some(ErrorAction::IgnoreError)});
                }
 
-               let (our_commitment_signed, monitor_update) = if need_our_commitment && (self.channel_state & (ChannelState::AwaitingRemoteRevoke as u32)) == 0 {
+               let (our_commitment_signed, monitor_update, closing_signed) = if need_our_commitment && (self.channel_state & (ChannelState::AwaitingRemoteRevoke as u32)) == 0 {
                        // If we're AwaitingRemoteRevoke we can't send a new commitment here, but that's ok -
                        // we'll send one right away when we get the revoke_and_ack when we
                        // free_holding_cell_htlcs().
                        let (msg, monitor) = self.send_commitment_no_status_check()?;
-                       (Some(msg), monitor)
-               } else { (None, self.channel_monitor.clone()) };
+                       (Some(msg), monitor, None)
+               } else if !need_our_commitment {
+                       (None, self.channel_monitor.clone(), self.maybe_propose_first_closing_signed(fee_estimator))
+               } else { (None, self.channel_monitor.clone(), None) };
 
                Ok((msgs::RevokeAndACK {
                        channel_id: self.channel_id,
                        per_commitment_secret: per_commitment_secret,
                        next_per_commitment_point: next_per_commitment_point,
-               }, our_commitment_signed, monitor_update))
+               }, our_commitment_signed, closing_signed, monitor_update))
        }
 
        /// Used to fulfill holding_cell_htlcs when we get a remote ack (or implicitly get it by them
@@ -1843,13 +1854,16 @@ impl Channel {
        /// waiting on this revoke_and_ack. The generation of this new commitment_signed may also fail,
        /// generating an appropriate error *after* the channel state has been updated based on the
        /// revoke_and_ack message.
-       pub fn revoke_and_ack(&mut self, msg: &msgs::RevokeAndACK) -> Result<(Option<msgs::CommitmentUpdate>, Vec<(PendingForwardHTLCInfo, u64)>, Vec<(HTLCSource, [u8; 32], HTLCFailReason)>, ChannelMonitor), HandleError> {
+       pub fn revoke_and_ack(&mut self, msg: &msgs::RevokeAndACK, fee_estimator: &FeeEstimator) -> Result<(Option<msgs::CommitmentUpdate>, Vec<(PendingForwardHTLCInfo, u64)>, Vec<(HTLCSource, [u8; 32], HTLCFailReason)>, Option<msgs::ClosingSigned>, ChannelMonitor), HandleError> {
                if (self.channel_state & (ChannelState::ChannelFunded as u32)) != (ChannelState::ChannelFunded as u32) {
                        return Err(HandleError{err: "Got revoke/ACK message when channel was not in an operational state", action: None});
                }
                if self.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
                        return Err(HandleError{err: "Peer sent revoke_and_ack when we needed a channel_reestablish", action: Some(msgs::ErrorAction::SendErrorMessage{msg: msgs::ErrorMessage{data: "Peer sent revoke_and_ack when we needed a channel_reestablish".to_string(), channel_id: msg.channel_id}})});
                }
+               if self.channel_state & BOTH_SIDES_SHUTDOWN_MASK == BOTH_SIDES_SHUTDOWN_MASK && self.last_sent_closing_fee.is_some() {
+                       return Err(HandleError{err: "Peer sent revoke_and_ack after we'd started exchanging closing_signeds", action: Some(msgs::ErrorAction::SendErrorMessage{msg: msgs::ErrorMessage{data: "Peer sent revoke_and_ack after we'd started exchanging closing_signeds".to_string(), channel_id: msg.channel_id}})});
+               }
 
                if let Some(their_prev_commitment_point) = self.their_prev_commitment_point {
                        if PublicKey::from_secret_key(&self.secp_ctx, &secp_call!(SecretKey::from_slice(&self.secp_ctx, &msg.per_commitment_secret), "Peer provided an invalid per_commitment_secret", self.channel_id())) != their_prev_commitment_point {
@@ -1971,7 +1985,7 @@ impl Channel {
                        }
                        self.monitor_pending_forwards.append(&mut to_forward_infos);
                        self.monitor_pending_failures.append(&mut revoked_htlcs);
-                       return Ok((None, Vec::new(), Vec::new(), self.channel_monitor.clone()));
+                       return Ok((None, Vec::new(), Vec::new(), None, self.channel_monitor.clone()));
                }
 
                match self.free_holding_cell_htlcs()? {
@@ -1984,7 +1998,7 @@ impl Channel {
                                for fail_msg in update_fail_malformed_htlcs.drain(..) {
                                        commitment_update.0.update_fail_malformed_htlcs.push(fail_msg);
                                }
-                               Ok((Some(commitment_update.0), to_forward_infos, revoked_htlcs, commitment_update.1))
+                               Ok((Some(commitment_update.0), to_forward_infos, revoked_htlcs, None, commitment_update.1))
                        },
                        None => {
                                if require_commitment {
@@ -1996,9 +2010,9 @@ impl Channel {
                                                update_fail_malformed_htlcs,
                                                update_fee: None,
                                                commitment_signed
-                                       }), to_forward_infos, revoked_htlcs, monitor_update))
+                                       }), to_forward_infos, revoked_htlcs, None, monitor_update))
                                } else {
-                                       Ok((None, to_forward_infos, revoked_htlcs, self.channel_monitor.clone()))
+                                       Ok((None, to_forward_infos, revoked_htlcs, self.maybe_propose_first_closing_signed(fee_estimator), self.channel_monitor.clone()))
                                }
                        }
                }
@@ -2057,6 +2071,9 @@ impl Channel {
                        self.channel_state = ChannelState::ShutdownComplete as u32;
                        return outbound_drops;
                }
+               // Upon reconnect we have to start the closing_signed dance over, but shutdown messages
+               // will be retransmitted.
+               self.last_sent_closing_fee = None;
 
                let mut inbound_drop_count = 0;
                self.pending_inbound_htlcs.retain(|htlc| {
@@ -2244,7 +2261,7 @@ impl Channel {
 
        /// May panic if some calls other than message-handling calls (which will all Err immediately)
        /// have been called between remove_uncommitted_htlcs_and_mark_paused and this call.
-       pub fn channel_reestablish(&mut self, msg: &msgs::ChannelReestablish) -> Result<(Option<msgs::FundingLocked>, Option<msgs::RevokeAndACK>, Option<msgs::CommitmentUpdate>, Option<ChannelMonitor>, RAACommitmentOrder), ChannelError> {
+       pub fn channel_reestablish(&mut self, msg: &msgs::ChannelReestablish) -> Result<(Option<msgs::FundingLocked>, Option<msgs::RevokeAndACK>, Option<msgs::CommitmentUpdate>, Option<ChannelMonitor>, RAACommitmentOrder, Option<msgs::Shutdown>), ChannelError> {
                if self.channel_state & (ChannelState::PeerDisconnected as u32) == 0 {
                        // While BOLT 2 doesn't indicate explicitly we should error this channel here, it
                        // almost certainly indicates we are going to end up out-of-sync in some way, so we
@@ -2260,9 +2277,16 @@ impl Channel {
                // remaining cases either succeed or ErrorMessage-fail).
                self.channel_state &= !(ChannelState::PeerDisconnected as u32);
 
+               let shutdown_msg = if self.channel_state & (ChannelState::LocalShutdownSent as u32) != 0 {
+                       Some(msgs::Shutdown {
+                               channel_id: self.channel_id,
+                               scriptpubkey: self.get_closing_scriptpubkey(),
+                       })
+               } else { None };
+
                if self.channel_state & (ChannelState::FundingSent as u32 | ChannelState::OurFundingLocked as u32) == ChannelState::FundingSent as u32 {
                        // Short circuit the whole handler as there is nothing we can resend them
-                       return Ok((None, None, None, None, RAACommitmentOrder::CommitmentFirst));
+                       return Ok((None, None, None, None, RAACommitmentOrder::CommitmentFirst, shutdown_msg));
                }
 
                if msg.next_local_commitment_number == 0 || msg.next_remote_commitment_number == 0 {
@@ -2275,7 +2299,7 @@ impl Channel {
                        return Ok((Some(msgs::FundingLocked {
                                channel_id: self.channel_id(),
                                next_per_commitment_point: next_per_commitment_point,
-                       }), None, None, None, RAACommitmentOrder::CommitmentFirst));
+                       }), None, None, None, RAACommitmentOrder::CommitmentFirst, shutdown_msg));
                }
 
                let required_revoke = if msg.next_remote_commitment_number == INITIAL_COMMITMENT_NUMBER - self.cur_local_commitment_transaction_number {
@@ -2338,11 +2362,11 @@ impl Channel {
                                                        panic!("Got non-channel-failing result from free_holding_cell_htlcs");
                                                }
                                        },
-                                       Ok(Some((commitment_update, channel_monitor))) => return Ok((resend_funding_locked, required_revoke, Some(commitment_update), Some(channel_monitor), order)),
-                                       Ok(None) => return Ok((resend_funding_locked, required_revoke, None, None, order)),
+                                       Ok(Some((commitment_update, channel_monitor))) => return Ok((resend_funding_locked, required_revoke, Some(commitment_update), Some(channel_monitor), order, shutdown_msg)),
+                                       Ok(None) => return Ok((resend_funding_locked, required_revoke, None, None, order, shutdown_msg)),
                                }
                        } else {
-                               return Ok((resend_funding_locked, required_revoke, None, None, order));
+                               return Ok((resend_funding_locked, required_revoke, None, None, order, shutdown_msg));
                        }
                } else if msg.next_local_commitment_number == our_next_remote_commitment_number - 1 {
                        if required_revoke.is_some() {
@@ -2356,71 +2380,78 @@ impl Channel {
 
                        if self.channel_state & (ChannelState::MonitorUpdateFailed as u32) != 0 {
                                self.monitor_pending_commitment_signed = true;
-                               return Ok((resend_funding_locked, None, None, None, order));
+                               return Ok((resend_funding_locked, None, None, None, order, shutdown_msg));
                        }
 
-                       return Ok((resend_funding_locked, required_revoke, Some(self.get_last_commitment_update()), None, order));
+                       return Ok((resend_funding_locked, required_revoke, Some(self.get_last_commitment_update()), None, order, shutdown_msg));
                } else {
                        return Err(ChannelError::Close("Peer attempted to reestablish channel with a very old remote commitment transaction"));
                }
        }
 
-       pub fn shutdown(&mut self, fee_estimator: &FeeEstimator, msg: &msgs::Shutdown) -> Result<(Option<msgs::Shutdown>, Option<msgs::ClosingSigned>, Vec<(HTLCSource, [u8; 32])>), HandleError> {
+       fn maybe_propose_first_closing_signed(&mut self, fee_estimator: &FeeEstimator) -> Option<msgs::ClosingSigned> {
+               if !self.channel_outbound || !self.pending_inbound_htlcs.is_empty() || !self.pending_outbound_htlcs.is_empty() ||
+                               self.channel_state & (BOTH_SIDES_SHUTDOWN_MASK | ChannelState::AwaitingRemoteRevoke as u32) != BOTH_SIDES_SHUTDOWN_MASK ||
+                               self.last_sent_closing_fee.is_some() ||
+                               self.cur_remote_commitment_transaction_number != self.cur_local_commitment_transaction_number{
+                       return None;
+               }
+
+               let mut proposed_feerate = fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::Background);
+               if self.feerate_per_kw > proposed_feerate {
+                       proposed_feerate = self.feerate_per_kw;
+               }
+               let tx_weight = Self::get_closing_transaction_weight(&self.get_closing_scriptpubkey(), self.their_shutdown_scriptpubkey.as_ref().unwrap());
+               let proposed_total_fee_satoshis = proposed_feerate * tx_weight / 1000;
+
+               let (closing_tx, total_fee_satoshis) = self.build_closing_transaction(proposed_total_fee_satoshis, false);
+               let funding_redeemscript = self.get_funding_redeemscript();
+               let sighash = Message::from_slice(&bip143::SighashComponents::new(&closing_tx).sighash_all(&closing_tx.input[0], &funding_redeemscript, self.channel_value_satoshis)[..]).unwrap();
+
+               self.last_sent_closing_fee = Some((proposed_feerate, total_fee_satoshis));
+               Some(msgs::ClosingSigned {
+                       channel_id: self.channel_id,
+                       fee_satoshis: total_fee_satoshis,
+                       signature: self.secp_ctx.sign(&sighash, &self.local_keys.funding_key),
+               })
+       }
+
+       pub fn shutdown(&mut self, fee_estimator: &FeeEstimator, msg: &msgs::Shutdown) -> Result<(Option<msgs::Shutdown>, Option<msgs::ClosingSigned>, Vec<(HTLCSource, [u8; 32])>), ChannelError> {
                if self.channel_state & (ChannelState::PeerDisconnected as u32) == ChannelState::PeerDisconnected as u32 {
-                       return Err(HandleError{err: "Peer sent shutdown when we needed a channel_reestablish", action: Some(msgs::ErrorAction::SendErrorMessage{msg: msgs::ErrorMessage{data: "Peer sent shutdown when we needed a channel_reestablish".to_string(), channel_id: msg.channel_id}})});
+                       return Err(ChannelError::Close("Peer sent shutdown when we needed a channel_reestablish"));
                }
                if self.channel_state < ChannelState::FundingSent as u32 {
-                       self.channel_state = ChannelState::ShutdownComplete as u32;
-                       self.channel_update_count += 1;
-                       return Ok((None, None, Vec::new()));
+                       // Spec says we should fail the connection, not the channel, but that's nonsense, there
+                       // are plenty of reasons you may want to fail a channel pre-funding, and spec says you
+                       // can do that via error message without getting a connection fail anyway...
+                       return Err(ChannelError::Close("Peer sent shutdown pre-funding generation"));
                }
                for htlc in self.pending_inbound_htlcs.iter() {
                        if let InboundHTLCState::RemoteAnnounced(_) = htlc.state {
-                               return Err(HandleError{err: "Got shutdown with remote pending HTLCs", action: None});
+                               return Err(ChannelError::Close("Got shutdown with remote pending HTLCs"));
                        }
                }
-               if (self.channel_state & ChannelState::RemoteShutdownSent as u32) == ChannelState::RemoteShutdownSent as u32 {
-                       return Err(HandleError{err: "Remote peer sent duplicate shutdown message", action: None});
-               }
                assert_eq!(self.channel_state & ChannelState::ShutdownComplete as u32, 0);
 
                // BOLT 2 says we must only send a scriptpubkey of certain standard forms, which are up to
                // 34 bytes in length, so dont let the remote peer feed us some super fee-heavy script.
                if self.channel_outbound && msg.scriptpubkey.len() > 34 {
-                       return Err(HandleError{err: "Got shutdown_scriptpubkey of absurd length from remote peer", action: None});
+                       return Err(ChannelError::Close("Got shutdown_scriptpubkey of absurd length from remote peer"));
                }
 
                //Check shutdown_scriptpubkey form as BOLT says we must
-               if !(msg.scriptpubkey.is_p2pkh()) && !(msg.scriptpubkey.is_p2sh())
-                       && !(msg.scriptpubkey.is_v0_p2wpkh()) && !(msg.scriptpubkey.is_v0_p2wsh()){
-                       return Err(HandleError{err: "Got an invalid scriptpubkey from remote peer", action: Some(msgs::ErrorAction::DisconnectPeer{ msg: None })});
+               if !msg.scriptpubkey.is_p2pkh() && !msg.scriptpubkey.is_p2sh() && !msg.scriptpubkey.is_v0_p2wpkh() && !msg.scriptpubkey.is_v0_p2wsh() {
+                       return Err(ChannelError::Close("Got a nonstandard scriptpubkey from remote peer"));
                }
 
                if self.their_shutdown_scriptpubkey.is_some() {
                        if Some(&msg.scriptpubkey) != self.their_shutdown_scriptpubkey.as_ref() {
-                               return Err(HandleError{err: "Got shutdown request with a scriptpubkey which did not match their previous scriptpubkey", action: None});
+                               return Err(ChannelError::Close("Got shutdown request with a scriptpubkey which did not match their previous scriptpubkey"));
                        }
                } else {
                        self.their_shutdown_scriptpubkey = Some(msg.scriptpubkey.clone());
                }
 
-               let our_closing_script = self.get_closing_scriptpubkey();
-
-               let (proposed_feerate, proposed_fee, our_sig) = if self.channel_outbound && self.pending_inbound_htlcs.is_empty() && self.pending_outbound_htlcs.is_empty() {
-                       let mut proposed_feerate = fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::Background);
-                       if self.feerate_per_kw > proposed_feerate {
-                               proposed_feerate = self.feerate_per_kw;
-                       }
-                       let tx_weight = Self::get_closing_transaction_weight(&our_closing_script, &msg.scriptpubkey);
-                       let proposed_total_fee_satoshis = proposed_feerate * tx_weight / 1000;
-
-                       let (closing_tx, total_fee_satoshis) = self.build_closing_transaction(proposed_total_fee_satoshis, false);
-                       let funding_redeemscript = self.get_funding_redeemscript();
-                       let sighash = Message::from_slice(&bip143::SighashComponents::new(&closing_tx).sighash_all(&closing_tx.input[0], &funding_redeemscript, self.channel_value_satoshis)[..]).unwrap();
-
-                       (Some(proposed_feerate), Some(total_fee_satoshis), Some(self.secp_ctx.sign(&sighash, &self.local_keys.funding_key)))
-               } else { (None, None, None) };
-
                // From here on out, we may not fail!
 
                self.channel_state |= ChannelState::RemoteShutdownSent as u32;
@@ -2429,6 +2460,7 @@ impl Channel {
                // We can't send our shutdown until we've committed all of our pending HTLCs, but the
                // remote side is unlikely to accept any new HTLCs, so we go ahead and "free" any holding
                // cell HTLCs and return them to fail the payment.
+               self.holding_cell_update_fee = None;
                let mut dropped_outbound_htlcs = Vec::with_capacity(self.holding_cell_htlc_updates.len());
                self.holding_cell_htlc_updates.retain(|htlc_update| {
                        match htlc_update {
@@ -2439,35 +2471,22 @@ impl Channel {
                                _ => true
                        }
                });
-               for htlc in self.pending_outbound_htlcs.iter() {
-                       if let OutboundHTLCState::LocalAnnounced(_) = htlc.state {
-                               return Ok((None, None, dropped_outbound_htlcs));
-                       }
-               }
+               // If we have any LocalAnnounced updates we'll probably just get back a update_fail_htlc
+               // immediately after the commitment dance, but we can send a Shutdown cause we won't send
+               // any further commitment updates after we set LocalShutdownSent.
 
                let our_shutdown = if (self.channel_state & ChannelState::LocalShutdownSent as u32) == ChannelState::LocalShutdownSent as u32 {
                        None
                } else {
                        Some(msgs::Shutdown {
                                channel_id: self.channel_id,
-                               scriptpubkey: our_closing_script,
+                               scriptpubkey: self.get_closing_scriptpubkey(),
                        })
                };
 
                self.channel_state |= ChannelState::LocalShutdownSent as u32;
                self.channel_update_count += 1;
-               if self.pending_inbound_htlcs.is_empty() && self.pending_outbound_htlcs.is_empty() && self.channel_outbound {
-                       // There are no more HTLCs and we're the funder, this means we start the closing_signed
-                       // dance with an initial fee proposal!
-                       self.last_sent_closing_fee = Some((proposed_feerate.unwrap(), proposed_fee.unwrap()));
-                       Ok((our_shutdown, Some(msgs::ClosingSigned {
-                               channel_id: self.channel_id,
-                               fee_satoshis: proposed_fee.unwrap(),
-                               signature: our_sig.unwrap(),
-                       }), dropped_outbound_htlcs))
-               } else {
-                       Ok((our_shutdown, None, dropped_outbound_htlcs))
-               }
+               Ok((our_shutdown, self.maybe_propose_first_closing_signed(fee_estimator), dropped_outbound_htlcs))
        }
 
        pub fn closing_signed(&mut self, fee_estimator: &FeeEstimator, msg: &msgs::ClosingSigned) -> Result<(Option<msgs::ClosingSigned>, Option<Transaction>), HandleError> {
@@ -3250,9 +3269,9 @@ impl Channel {
                }
                self.channel_update_count += 1;
 
-               // We can't send our shutdown until we've committed all of our pending HTLCs, but the
-               // remote side is unlikely to accept any new HTLCs, so we go ahead and "free" any holding
-               // cell HTLCs and return them to fail the payment.
+               // Go ahead and drop holding cell updates as we'd rather fail payments than wait to send
+               // our shutdown until we've committed all of the pending changes.
+               self.holding_cell_update_fee = None;
                let mut dropped_outbound_htlcs = Vec::with_capacity(self.holding_cell_htlc_updates.len());
                self.holding_cell_htlc_updates.retain(|htlc_update| {
                        match htlc_update {