Add more comments about timelock assumptions and security model
[rust-lightning] / src / ln / channelmanager.rs
index ba2bfefccebaad2f68d1d2fee27681eee6a21229..64a9f2ebb8e575c3895d77efd3ab4eaa1b82ccf0 100644 (file)
@@ -12,11 +12,12 @@ use bitcoin::blockdata::block::BlockHeader;
 use bitcoin::blockdata::transaction::Transaction;
 use bitcoin::blockdata::constants::genesis_block;
 use bitcoin::network::constants::Network;
-use bitcoin::util::hash::{BitcoinHash, Sha256dHash};
+use bitcoin::util::hash::BitcoinHash;
 
 use bitcoin_hashes::{Hash, HashEngine};
 use bitcoin_hashes::hmac::{Hmac, HmacEngine};
 use bitcoin_hashes::sha256::Hash as Sha256;
+use bitcoin_hashes::sha256d::Hash as Sha256dHash;
 use bitcoin_hashes::cmp::fixed_time_eq;
 
 use secp256k1::key::{SecretKey,PublicKey};
@@ -27,7 +28,7 @@ use secp256k1;
 use chain::chaininterface::{BroadcasterInterface,ChainListener,ChainWatchInterface,FeeEstimator};
 use chain::transaction::OutPoint;
 use ln::channel::{Channel, ChannelError};
-use ln::channelmonitor::{ChannelMonitor, ChannelMonitorUpdateErr, ManyChannelMonitor, CLTV_CLAIM_BUFFER, HTLC_FAIL_TIMEOUT_BLOCKS, HTLC_FAIL_ANTI_REORG_DELAY};
+use ln::channelmonitor::{ChannelMonitor, ChannelMonitorUpdateErr, ManyChannelMonitor, CLTV_CLAIM_BUFFER, LATENCY_GRACE_PERIOD_BLOCKS, ANTI_REORG_DELAY};
 use ln::router::Route;
 use ln::msgs;
 use ln::onion_utils;
@@ -161,6 +162,16 @@ impl MsgHandleErrInternal {
                }
        }
        #[inline]
+       fn ignore_no_close(err: &'static str) -> Self {
+               Self {
+                       err: HandleError {
+                               err,
+                               action: Some(msgs::ErrorAction::IgnoreError),
+                       },
+                       shutdown_finish: None,
+               }
+       }
+       #[inline]
        fn from_no_close(err: msgs::HandleError) -> Self {
                Self { err, shutdown_finish: None }
        }
@@ -239,13 +250,15 @@ pub(super) struct ChannelHolder {
        pub(super) next_forward: Instant,
        /// short channel id -> forward infos. Key of 0 means payments received
        /// Note that while this is held in the same mutex as the channels themselves, no consistency
-       /// guarantees are made about there existing a channel with the short id here, nor the short
+       /// guarantees are made about the existence of a channel with the short id here, nor the short
        /// ids in the PendingForwardHTLCInfo!
        pub(super) forward_htlcs: HashMap<u64, Vec<HTLCForwardInfo>>,
+       /// payment_hash -> Vec<(amount_received, htlc_source)> for tracking things that were to us and
+       /// can be failed/claimed by the user
        /// Note that while this is held in the same mutex as the channels themselves, no consistency
        /// guarantees are made about the channels given here actually existing anymore by the time you
        /// go to read them!
-       pub(super) claimable_htlcs: HashMap<PaymentHash, Vec<HTLCPreviousHopData>>,
+       pub(super) claimable_htlcs: HashMap<PaymentHash, Vec<(u64, HTLCPreviousHopData)>>,
        /// Messages to send to peers - pushed to in the same lock that they are generated in (except
        /// for broadcast messages, where ordering isn't as strict).
        pub(super) pending_msg_events: Vec<events::MessageSendEvent>,
@@ -255,7 +268,7 @@ pub(super) struct MutChannelHolder<'a> {
        pub(super) short_to_id: &'a mut HashMap<u64, [u8; 32]>,
        pub(super) next_forward: &'a mut Instant,
        pub(super) forward_htlcs: &'a mut HashMap<u64, Vec<HTLCForwardInfo>>,
-       pub(super) claimable_htlcs: &'a mut HashMap<PaymentHash, Vec<HTLCPreviousHopData>>,
+       pub(super) claimable_htlcs: &'a mut HashMap<PaymentHash, Vec<(u64, HTLCPreviousHopData)>>,
        pub(super) pending_msg_events: &'a mut Vec<events::MessageSendEvent>,
 }
 impl ChannelHolder {
@@ -334,24 +347,25 @@ pub struct ChannelManager {
 /// HTLC's CLTV. This should always be a few blocks greater than channelmonitor::CLTV_CLAIM_BUFFER,
 /// ie the node we forwarded the payment on to should always have enough room to reliably time out
 /// the HTLC via a full update_fail_htlc/commitment_signed dance before we hit the
-/// CLTV_CLAIM_BUFFER point (we static assert that its at least 3 blocks more).
+/// CLTV_CLAIM_BUFFER point (we static assert that it's at least 3 blocks more).
 const CLTV_EXPIRY_DELTA: u16 = 6 * 12; //TODO?
 pub(super) const CLTV_FAR_FAR_AWAY: u32 = 6 * 24 * 7; //TODO?
 
-// Check that our CLTV_EXPIRY is at least CLTV_CLAIM_BUFFER + 2*HTLC_FAIL_TIMEOUT_BLOCKS +
-// HTLC_FAIL_ANTI_REORG_DELAY, ie that if the next-hop peer fails the HTLC within
-// HTLC_FAIL_TIMEOUT_BLOCKS then we'll still have HTLC_FAIL_TIMEOUT_BLOCKS left to fail it
-// backwards ourselves before hitting the CLTV_CLAIM_BUFFER point and failing the channel
-// on-chain to time out the HTLC.
+// Check that our CLTV_EXPIRY is at least CLTV_CLAIM_BUFFER + ANTI_REORG_DELAY + LATENCY_GRACE_PERIOD_BLOCKS,
+// ie that if the next-hop peer fails the HTLC within
+// LATENCY_GRACE_PERIOD_BLOCKS then we'll still have CLTV_CLAIM_BUFFER left to timeout it onchain,
+// then waiting ANTI_REORG_DELAY to be reorg-safe on the outbound HLTC and
+// failing the corresponding htlc backward, and us now seeing the last block of ANTI_REORG_DELAY before
+// LATENCY_GRACE_PERIOD_BLOCKS.
 #[deny(const_err)]
 #[allow(dead_code)]
-const CHECK_CLTV_EXPIRY_SANITY: u32 = CLTV_EXPIRY_DELTA as u32 - 2*HTLC_FAIL_TIMEOUT_BLOCKS - CLTV_CLAIM_BUFFER - HTLC_FAIL_ANTI_REORG_DELAY;
+const CHECK_CLTV_EXPIRY_SANITY: u32 = CLTV_EXPIRY_DELTA as u32 - LATENCY_GRACE_PERIOD_BLOCKS - CLTV_CLAIM_BUFFER - ANTI_REORG_DELAY - LATENCY_GRACE_PERIOD_BLOCKS;
 
 // Check for ability of an attacker to make us fail on-chain by delaying inbound claim. See
 // ChannelMontior::would_broadcast_at_height for a description of why this is needed.
 #[deny(const_err)]
 #[allow(dead_code)]
-const CHECK_CLTV_EXPIRY_SANITY_2: u32 = CLTV_EXPIRY_DELTA as u32 - HTLC_FAIL_TIMEOUT_BLOCKS - 2*CLTV_CLAIM_BUFFER;
+const CHECK_CLTV_EXPIRY_SANITY_2: u32 = CLTV_EXPIRY_DELTA as u32 - LATENCY_GRACE_PERIOD_BLOCKS - 2*CLTV_CLAIM_BUFFER;
 
 macro_rules! secp_call {
        ( $res: expr, $err: expr ) => {
@@ -438,13 +452,14 @@ macro_rules! try_chan_entry {
        }
 }
 
-macro_rules! return_monitor_err {
+macro_rules! handle_monitor_err {
        ($self: ident, $err: expr, $channel_state: expr, $entry: expr, $action_type: path, $resend_raa: expr, $resend_commitment: expr) => {
-               return_monitor_err!($self, $err, $channel_state, $entry, $action_type, $resend_raa, $resend_commitment, Vec::new(), Vec::new())
+               handle_monitor_err!($self, $err, $channel_state, $entry, $action_type, $resend_raa, $resend_commitment, Vec::new(), Vec::new())
        };
        ($self: ident, $err: expr, $channel_state: expr, $entry: expr, $action_type: path, $resend_raa: expr, $resend_commitment: expr, $failed_forwards: expr, $failed_fails: expr) => {
                match $err {
                        ChannelMonitorUpdateErr::PermanentFailure => {
+                               log_error!($self, "Closing channel {} due to monitor update PermanentFailure", log_bytes!($entry.key()[..]));
                                let (channel_id, mut chan) = $entry.remove_entry();
                                if let Some(short_id) = chan.get_short_channel_id() {
                                        $channel_state.short_to_id.remove(&short_id);
@@ -458,30 +473,52 @@ macro_rules! return_monitor_err {
                                // splitting hairs we'd prefer to claim payments that were to us, but we haven't
                                // given up the preimage yet, so might as well just wait until the payment is
                                // retried, avoiding the on-chain fees.
-                               return Err(MsgHandleErrInternal::from_finish_shutdown("ChannelMonitor storage failure", channel_id, chan.force_shutdown(), $self.get_channel_update(&chan).ok()))
+                               let res: Result<(), _> = Err(MsgHandleErrInternal::from_finish_shutdown("ChannelMonitor storage failure", channel_id, chan.force_shutdown(), $self.get_channel_update(&chan).ok()));
+                               res
                        },
                        ChannelMonitorUpdateErr::TemporaryFailure => {
-                               $entry.get_mut().monitor_update_failed($action_type, $resend_raa, $resend_commitment, $failed_forwards, $failed_fails);
-                               return Err(MsgHandleErrInternal::from_chan_no_close(ChannelError::Ignore("Failed to update ChannelMonitor"), *$entry.key()));
+                               log_info!($self, "Disabling channel {} due to monitor update TemporaryFailure. On restore will send {} and process {} forwards and {} fails",
+                                               log_bytes!($entry.key()[..]),
+                                               if $resend_commitment && $resend_raa {
+                                                               match $action_type {
+                                                                       RAACommitmentOrder::CommitmentFirst => { "commitment then RAA" },
+                                                                       RAACommitmentOrder::RevokeAndACKFirst => { "RAA then commitment" },
+                                                               }
+                                                       } else if $resend_commitment { "commitment" }
+                                                       else if $resend_raa { "RAA" }
+                                                       else { "nothing" },
+                                               (&$failed_forwards as &Vec<(PendingForwardHTLCInfo, u64)>).len(),
+                                               (&$failed_fails as &Vec<(HTLCSource, PaymentHash, HTLCFailReason)>).len());
+                               if !$resend_commitment {
+                                       debug_assert!($action_type == RAACommitmentOrder::RevokeAndACKFirst || !$resend_raa);
+                               }
+                               if !$resend_raa {
+                                       debug_assert!($action_type == RAACommitmentOrder::CommitmentFirst || !$resend_commitment);
+                               }
+                               $entry.get_mut().monitor_update_failed($resend_raa, $resend_commitment, $failed_forwards, $failed_fails);
+                               Err(MsgHandleErrInternal::from_chan_no_close(ChannelError::Ignore("Failed to update ChannelMonitor"), *$entry.key()))
                        },
                }
        }
 }
 
+macro_rules! return_monitor_err {
+       ($self: ident, $err: expr, $channel_state: expr, $entry: expr, $action_type: path, $resend_raa: expr, $resend_commitment: expr) => {
+               return handle_monitor_err!($self, $err, $channel_state, $entry, $action_type, $resend_raa, $resend_commitment);
+       };
+       ($self: ident, $err: expr, $channel_state: expr, $entry: expr, $action_type: path, $resend_raa: expr, $resend_commitment: expr, $failed_forwards: expr, $failed_fails: expr) => {
+               return handle_monitor_err!($self, $err, $channel_state, $entry, $action_type, $resend_raa, $resend_commitment, $failed_forwards, $failed_fails);
+       }
+}
+
 // Does not break in case of TemporaryFailure!
 macro_rules! maybe_break_monitor_err {
        ($self: ident, $err: expr, $channel_state: expr, $entry: expr, $action_type: path, $resend_raa: expr, $resend_commitment: expr) => {
-               match $err {
-                       ChannelMonitorUpdateErr::PermanentFailure => {
-                               let (channel_id, mut chan) = $entry.remove_entry();
-                               if let Some(short_id) = chan.get_short_channel_id() {
-                                       $channel_state.short_to_id.remove(&short_id);
-                               }
-                               break Err(MsgHandleErrInternal::from_finish_shutdown("ChannelMonitor storage failure", channel_id, chan.force_shutdown(), $self.get_channel_update(&chan).ok()))
-                       },
-                       ChannelMonitorUpdateErr::TemporaryFailure => {
-                               $entry.get_mut().monitor_update_failed($action_type, $resend_raa, $resend_commitment, Vec::new(), Vec::new());
+               match (handle_monitor_err!($self, $err, $channel_state, $entry, $action_type, $resend_raa, $resend_commitment), $err) {
+                       (e, ChannelMonitorUpdateErr::PermanentFailure) => {
+                               break e;
                        },
+                       (_, ChannelMonitorUpdateErr::TemporaryFailure) => { },
                }
        }
 }
@@ -734,7 +771,7 @@ impl ChannelManager {
                if msg.onion_routing_packet.version != 0 {
                        //TODO: Spec doesn't indicate if we should only hash hop_data here (and in other
                        //sha256_of_onion error data packets), or the entire onion_routing_packet. Either way,
-                       //the hash doesn't really serve any purpuse - in the case of hashing all data, the
+                       //the hash doesn't really serve any purpose - in the case of hashing all data, the
                        //receiving node would have to brute force to figure out which version was put in the
                        //packet by the node that send us the message, in the case of hashing the hop_data, the
                        //node knows the HMAC matched, so they already know what is there...
@@ -784,7 +821,7 @@ impl ChannelManager {
                let pending_forward_info = if next_hop_data.hmac == [0; 32] {
                                // OUR PAYMENT!
                                // final_expiry_too_soon
-                               if (msg.cltv_expiry as u64) < self.latest_block_height.load(Ordering::Acquire) as u64 + (CLTV_CLAIM_BUFFER + HTLC_FAIL_TIMEOUT_BLOCKS) as u64 {
+                               if (msg.cltv_expiry as u64) < self.latest_block_height.load(Ordering::Acquire) as u64 + (CLTV_CLAIM_BUFFER + LATENCY_GRACE_PERIOD_BLOCKS) as u64 {
                                        return_err!("The final CLTV expiry is too soon to handle", 17, &[0;0]);
                                }
                                // final_incorrect_htlc_amount
@@ -876,8 +913,8 @@ impl ChannelManager {
                                                break Some(("Forwarding node has tampered with the intended HTLC values or origin node has an obsolete cltv_expiry_delta", 0x1000 | 13, Some(self.get_channel_update(chan).unwrap())));
                                        }
                                        let cur_height = self.latest_block_height.load(Ordering::Acquire) as u32 + 1;
-                                       // We want to have at least HTLC_FAIL_TIMEOUT_BLOCKS to fail prior to going on chain CLAIM_BUFFER blocks before expiration
-                                       if msg.cltv_expiry <= cur_height + CLTV_CLAIM_BUFFER + HTLC_FAIL_TIMEOUT_BLOCKS as u32 { // expiry_too_soon
+                                       // We want to have at least LATENCY_GRACE_PERIOD_BLOCKS to fail prior to going on chain CLAIM_BUFFER blocks before expiration
+                                       if msg.cltv_expiry <= cur_height + CLTV_CLAIM_BUFFER + LATENCY_GRACE_PERIOD_BLOCKS as u32 { // expiry_too_soon
                                                break Some(("CLTV expiry is too close", 0x1000 | 14, Some(self.get_channel_update(chan).unwrap())));
                                        }
                                        if msg.cltv_expiry > cur_height + CLTV_FAR_FAR_AWAY as u32 { // expiry_too_far
@@ -929,7 +966,7 @@ impl ChannelManager {
                        excess_data: Vec::new(),
                };
 
-               let msg_hash = Sha256dHash::from_data(&unsigned.encode()[..]);
+               let msg_hash = Sha256dHash::hash(&unsigned.encode()[..]);
                let sig = self.secp_ctx.sign(&hash_to_message!(&msg_hash[..]), &self.our_network_key);
 
                Ok(msgs::ChannelUpdate {
@@ -1123,7 +1160,7 @@ impl ChannelManager {
                        Ok(res) => res,
                        Err(_) => return None, // Only in case of state precondition violations eg channel is closing
                };
-               let msghash = hash_to_message!(&Sha256dHash::from_data(&announcement.encode()[..])[..]);
+               let msghash = hash_to_message!(&Sha256dHash::hash(&announcement.encode()[..])[..]);
                let our_node_sig = self.secp_ctx.sign(&msghash, &self.our_network_key);
 
                Some(msgs::AnnouncementSignatures {
@@ -1136,13 +1173,14 @@ impl ChannelManager {
 
        /// Processes HTLCs which are pending waiting on random forward delay.
        ///
-       /// Should only really ever be called in response to an PendingHTLCsForwardable event.
+       /// Should only really ever be called in response to a PendingHTLCsForwardable event.
        /// Will likely generate further events.
        pub fn process_pending_htlc_forwards(&self) {
                let _ = self.total_consistency_lock.read().unwrap();
 
                let mut new_events = Vec::new();
                let mut failed_forwards = Vec::new();
+               let mut handle_errors = Vec::new();
                {
                        let mut channel_state_lock = self.channel_state.lock().unwrap();
                        let channel_state = channel_state_lock.borrow_parts();
@@ -1178,101 +1216,104 @@ impl ChannelManager {
                                                        continue;
                                                }
                                        };
-                                       let forward_chan = &mut channel_state.by_id.get_mut(&forward_chan_id).unwrap();
-
-                                       let mut add_htlc_msgs = Vec::new();
-                                       let mut fail_htlc_msgs = Vec::new();
-                                       for forward_info in pending_forwards.drain(..) {
-                                               match forward_info {
-                                                       HTLCForwardInfo::AddHTLC { prev_short_channel_id, prev_htlc_id, forward_info } => {
-                                                               log_trace!(self, "Adding HTLC from short id {} with payment_hash {} to channel with short id {} after delay", log_bytes!(forward_info.payment_hash.0), prev_short_channel_id, short_chan_id);
-                                                               let htlc_source = HTLCSource::PreviousHopData(HTLCPreviousHopData {
-                                                                       short_channel_id: prev_short_channel_id,
-                                                                       htlc_id: prev_htlc_id,
-                                                                       incoming_packet_shared_secret: forward_info.incoming_shared_secret,
-                                                               });
-                                                               match forward_chan.send_htlc(forward_info.amt_to_forward, forward_info.payment_hash, forward_info.outgoing_cltv_value, htlc_source.clone(), forward_info.onion_packet.unwrap()) {
-                                                                       Err(e) => {
-                                                                               if let ChannelError::Ignore(msg) = e {
-                                                                                       log_trace!(self, "Failed to forward HTLC with payment_hash {}: {}", log_bytes!(forward_info.payment_hash.0), msg);
-                                                                               } else {
-                                                                                       panic!("Stated return value requirements in send_htlc() were not met");
-                                                                               }
-                                                                               let chan_update = self.get_channel_update(forward_chan).unwrap();
-                                                                               failed_forwards.push((htlc_source, forward_info.payment_hash, 0x1000 | 7, Some(chan_update)));
-                                                                               continue;
-                                                                       },
-                                                                       Ok(update_add) => {
-                                                                               match update_add {
-                                                                                       Some(msg) => { add_htlc_msgs.push(msg); },
-                                                                                       None => {
-                                                                                               // Nothing to do here...we're waiting on a remote
-                                                                                               // revoke_and_ack before we can add anymore HTLCs. The Channel
-                                                                                               // will automatically handle building the update_add_htlc and
-                                                                                               // commitment_signed messages when we can.
-                                                                                               // TODO: Do some kind of timer to set the channel as !is_live()
-                                                                                               // as we don't really want others relying on us relaying through
-                                                                                               // this channel currently :/.
+                                       if let hash_map::Entry::Occupied(mut chan) = channel_state.by_id.entry(forward_chan_id) {
+                                               let mut add_htlc_msgs = Vec::new();
+                                               let mut fail_htlc_msgs = Vec::new();
+                                               for forward_info in pending_forwards.drain(..) {
+                                                       match forward_info {
+                                                               HTLCForwardInfo::AddHTLC { prev_short_channel_id, prev_htlc_id, forward_info } => {
+                                                                       log_trace!(self, "Adding HTLC from short id {} with payment_hash {} to channel with short id {} after delay", log_bytes!(forward_info.payment_hash.0), prev_short_channel_id, short_chan_id);
+                                                                       let htlc_source = HTLCSource::PreviousHopData(HTLCPreviousHopData {
+                                                                               short_channel_id: prev_short_channel_id,
+                                                                               htlc_id: prev_htlc_id,
+                                                                               incoming_packet_shared_secret: forward_info.incoming_shared_secret,
+                                                                       });
+                                                                       match chan.get_mut().send_htlc(forward_info.amt_to_forward, forward_info.payment_hash, forward_info.outgoing_cltv_value, htlc_source.clone(), forward_info.onion_packet.unwrap()) {
+                                                                               Err(e) => {
+                                                                                       if let ChannelError::Ignore(msg) = e {
+                                                                                               log_trace!(self, "Failed to forward HTLC with payment_hash {}: {}", log_bytes!(forward_info.payment_hash.0), msg);
+                                                                                       } else {
+                                                                                               panic!("Stated return value requirements in send_htlc() were not met");
+                                                                                       }
+                                                                                       let chan_update = self.get_channel_update(chan.get()).unwrap();
+                                                                                       failed_forwards.push((htlc_source, forward_info.payment_hash, 0x1000 | 7, Some(chan_update)));
+                                                                                       continue;
+                                                                               },
+                                                                               Ok(update_add) => {
+                                                                                       match update_add {
+                                                                                               Some(msg) => { add_htlc_msgs.push(msg); },
+                                                                                               None => {
+                                                                                                       // Nothing to do here...we're waiting on a remote
+                                                                                                       // revoke_and_ack before we can add anymore HTLCs. The Channel
+                                                                                                       // will automatically handle building the update_add_htlc and
+                                                                                                       // commitment_signed messages when we can.
+                                                                                                       // TODO: Do some kind of timer to set the channel as !is_live()
+                                                                                                       // as we don't really want others relying on us relaying through
+                                                                                                       // this channel currently :/.
+                                                                                               }
                                                                                        }
                                                                                }
                                                                        }
-                                                               }
-                                                       },
-                                                       HTLCForwardInfo::FailHTLC { htlc_id, err_packet } => {
-                                                               log_trace!(self, "Failing HTLC back to channel with short id {} after delay", short_chan_id);
-                                                               match forward_chan.get_update_fail_htlc(htlc_id, err_packet) {
-                                                                       Err(e) => {
-                                                                               if let ChannelError::Ignore(msg) = e {
-                                                                                       log_trace!(self, "Failed to fail backwards to short_id {}: {}", short_chan_id, msg);
-                                                                               } else {
-                                                                                       panic!("Stated return value requirements in get_update_fail_htlc() were not met");
+                                                               },
+                                                               HTLCForwardInfo::FailHTLC { htlc_id, err_packet } => {
+                                                                       log_trace!(self, "Failing HTLC back to channel with short id {} after delay", short_chan_id);
+                                                                       match chan.get_mut().get_update_fail_htlc(htlc_id, err_packet) {
+                                                                               Err(e) => {
+                                                                                       if let ChannelError::Ignore(msg) = e {
+                                                                                               log_trace!(self, "Failed to fail backwards to short_id {}: {}", short_chan_id, msg);
+                                                                                       } else {
+                                                                                               panic!("Stated return value requirements in get_update_fail_htlc() were not met");
+                                                                                       }
+                                                                                       // fail-backs are best-effort, we probably already have one
+                                                                                       // pending, and if not that's OK, if not, the channel is on
+                                                                                       // the chain and sending the HTLC-Timeout is their problem.
+                                                                                       continue;
+                                                                               },
+                                                                               Ok(Some(msg)) => { fail_htlc_msgs.push(msg); },
+                                                                               Ok(None) => {
+                                                                                       // Nothing to do here...we're waiting on a remote
+                                                                                       // revoke_and_ack before we can update the commitment
+                                                                                       // transaction. The Channel will automatically handle
+                                                                                       // building the update_fail_htlc and commitment_signed
+                                                                                       // messages when we can.
+                                                                                       // We don't need any kind of timer here as they should fail
+                                                                                       // the channel onto the chain if they can't get our
+                                                                                       // update_fail_htlc in time, it's not our problem.
                                                                                }
-                                                                               // fail-backs are best-effort, we probably already have one
-                                                                               // pending, and if not that's OK, if not, the channel is on
-                                                                               // the chain and sending the HTLC-Timeout is their problem.
-                                                                               continue;
-                                                                       },
-                                                                       Ok(Some(msg)) => { fail_htlc_msgs.push(msg); },
-                                                                       Ok(None) => {
-                                                                               // Nothing to do here...we're waiting on a remote
-                                                                               // revoke_and_ack before we can update the commitment
-                                                                               // transaction. The Channel will automatically handle
-                                                                               // building the update_fail_htlc and commitment_signed
-                                                                               // messages when we can.
-                                                                               // We don't need any kind of timer here as they should fail
-                                                                               // the channel onto the chain if they can't get our
-                                                                               // update_fail_htlc in time, its not our problem.
                                                                        }
-                                                               }
-                                                       },
+                                                               },
+                                                       }
                                                }
-                                       }
 
-                                       if !add_htlc_msgs.is_empty() || !fail_htlc_msgs.is_empty() {
-                                               let (commitment_msg, monitor) = match forward_chan.send_commitment() {
-                                                       Ok(res) => res,
-                                                       Err(e) => {
-                                                               if let ChannelError::Ignore(_) = e {
-                                                                       panic!("Stated return value requirements in send_commitment() were not met");
-                                                               }
-                                                               //TODO: Handle...this is bad!
+                                               if !add_htlc_msgs.is_empty() || !fail_htlc_msgs.is_empty() {
+                                                       let (commitment_msg, monitor) = match chan.get_mut().send_commitment() {
+                                                               Ok(res) => res,
+                                                               Err(e) => {
+                                                                       if let ChannelError::Ignore(_) = e {
+                                                                               panic!("Stated return value requirements in send_commitment() were not met");
+                                                                       }
+                                                                       //TODO: Handle...this is bad!
+                                                                       continue;
+                                                               },
+                                                       };
+                                                       if let Err(e) = self.monitor.add_update_monitor(monitor.get_funding_txo().unwrap(), monitor) {
+                                                               handle_errors.push((chan.get().get_their_node_id(), handle_monitor_err!(self, e, channel_state, chan, RAACommitmentOrder::CommitmentFirst, false, true)));
                                                                continue;
-                                                       },
-                                               };
-                                               if let Err(_e) = self.monitor.add_update_monitor(monitor.get_funding_txo().unwrap(), monitor) {
-                                                       unimplemented!();
+                                                       }
+                                                       channel_state.pending_msg_events.push(events::MessageSendEvent::UpdateHTLCs {
+                                                               node_id: chan.get().get_their_node_id(),
+                                                               updates: msgs::CommitmentUpdate {
+                                                                       update_add_htlcs: add_htlc_msgs,
+                                                                       update_fulfill_htlcs: Vec::new(),
+                                                                       update_fail_htlcs: fail_htlc_msgs,
+                                                                       update_fail_malformed_htlcs: Vec::new(),
+                                                                       update_fee: None,
+                                                                       commitment_signed: commitment_msg,
+                                                               },
+                                                       });
                                                }
-                                               channel_state.pending_msg_events.push(events::MessageSendEvent::UpdateHTLCs {
-                                                       node_id: forward_chan.get_their_node_id(),
-                                                       updates: msgs::CommitmentUpdate {
-                                                               update_add_htlcs: add_htlc_msgs,
-                                                               update_fulfill_htlcs: Vec::new(),
-                                                               update_fail_htlcs: fail_htlc_msgs,
-                                                               update_fail_malformed_htlcs: Vec::new(),
-                                                               update_fee: None,
-                                                               commitment_signed: commitment_msg,
-                                                       },
-                                               });
+                                       } else {
+                                               unreachable!();
                                        }
                                } else {
                                        for forward_info in pending_forwards.drain(..) {
@@ -1284,8 +1325,8 @@ impl ChannelManager {
                                                                        incoming_packet_shared_secret: forward_info.incoming_shared_secret,
                                                                };
                                                                match channel_state.claimable_htlcs.entry(forward_info.payment_hash) {
-                                                                       hash_map::Entry::Occupied(mut entry) => entry.get_mut().push(prev_hop_data),
-                                                                       hash_map::Entry::Vacant(entry) => { entry.insert(vec![prev_hop_data]); },
+                                                                       hash_map::Entry::Occupied(mut entry) => entry.get_mut().push((forward_info.amt_to_forward, prev_hop_data)),
+                                                                       hash_map::Entry::Vacant(entry) => { entry.insert(vec![(forward_info.amt_to_forward, prev_hop_data)]); },
                                                                };
                                                                new_events.push(events::Event::PaymentReceived {
                                                                        payment_hash: forward_info.payment_hash,
@@ -1308,26 +1349,43 @@ impl ChannelManager {
                        };
                }
 
+               for (their_node_id, err) in handle_errors.drain(..) {
+                       match handle_error!(self, err) {
+                               Ok(_) => {},
+                               Err(e) => {
+                                       if let Some(msgs::ErrorAction::IgnoreError) = e.action {
+                                       } else {
+                                               let mut channel_state = self.channel_state.lock().unwrap();
+                                               channel_state.pending_msg_events.push(events::MessageSendEvent::HandleError {
+                                                       node_id: their_node_id,
+                                                       action: e.action,
+                                               });
+                                       }
+                               },
+                       }
+               }
+
                if new_events.is_empty() { return }
                let mut events = self.pending_events.lock().unwrap();
                events.append(&mut new_events);
        }
 
        /// Indicates that the preimage for payment_hash is unknown or the received amount is incorrect
-       /// after a PaymentReceived event.
-       /// expected_value is the value you expected the payment to be for (not the amount it actually
-       /// was for from the PaymentReceived event).
-       pub fn fail_htlc_backwards(&self, payment_hash: &PaymentHash, expected_value: u64) -> bool {
+       /// after a PaymentReceived event, failing the HTLC back to its origin and freeing resources
+       /// along the path (including in our own channel on which we received it).
+       /// Returns false if no payment was found to fail backwards, true if the process of failing the
+       /// HTLC backwards has been started.
+       pub fn fail_htlc_backwards(&self, payment_hash: &PaymentHash) -> bool {
                let _ = self.total_consistency_lock.read().unwrap();
 
                let mut channel_state = Some(self.channel_state.lock().unwrap());
                let removed_source = channel_state.as_mut().unwrap().claimable_htlcs.remove(payment_hash);
                if let Some(mut sources) = removed_source {
-                       for htlc_with_hash in sources.drain(..) {
+                       for (recvd_value, htlc_with_hash) in sources.drain(..) {
                                if channel_state.is_none() { channel_state = Some(self.channel_state.lock().unwrap()); }
                                self.fail_htlc_backwards_internal(channel_state.take().unwrap(),
                                                HTLCSource::PreviousHopData(htlc_with_hash), payment_hash,
-                                               HTLCFailReason::Reason { failure_code: 0x4000 | 15, data: byte_utils::be64_to_array(expected_value).to_vec() });
+                                               HTLCFailReason::Reason { failure_code: 0x4000 | 15, data: byte_utils::be64_to_array(recvd_value).to_vec() });
                        }
                        true
                } else { false }
@@ -1445,7 +1503,10 @@ impl ChannelManager {
                let mut channel_state = Some(self.channel_state.lock().unwrap());
                let removed_source = channel_state.as_mut().unwrap().claimable_htlcs.remove(&payment_hash);
                if let Some(mut sources) = removed_source {
-                       for htlc_with_hash in sources.drain(..) {
+                       // TODO: We should require the user specify the expected amount so that we can claim
+                       // only payments for the correct amount, and reject payments for incorrect amounts
+                       // (which are probably middle nodes probing to break our privacy).
+                       for (_, htlc_with_hash) in sources.drain(..) {
                                if channel_state.is_none() { channel_state = Some(self.channel_state.lock().unwrap()); }
                                self.claim_funds_internal(channel_state.take().unwrap(), HTLCSource::PreviousHopData(htlc_with_hash), payment_preimage);
                        }
@@ -1453,56 +1514,79 @@ impl ChannelManager {
                } else { false }
        }
        fn claim_funds_internal(&self, mut channel_state_lock: MutexGuard<ChannelHolder>, source: HTLCSource, payment_preimage: PaymentPreimage) {
-               match source {
-                       HTLCSource::OutboundRoute { .. } => {
-                               mem::drop(channel_state_lock);
-                               let mut pending_events = self.pending_events.lock().unwrap();
-                               pending_events.push(events::Event::PaymentSent {
-                                       payment_preimage
-                               });
-                       },
-                       HTLCSource::PreviousHopData(HTLCPreviousHopData { short_channel_id, htlc_id, .. }) => {
-                               //TODO: Delay the claimed_funds relaying just like we do outbound relay!
-                               let channel_state = channel_state_lock.borrow_parts();
-
-                               let chan_id = match channel_state.short_to_id.get(&short_channel_id) {
-                                       Some(chan_id) => chan_id.clone(),
-                                       None => {
-                                               // TODO: There is probably a channel manager somewhere that needs to
-                                               // learn the preimage as the channel already hit the chain and that's
-                                               // why its missing.
-                                               return
-                                       }
-                               };
+               let (their_node_id, err) = loop {
+                       match source {
+                               HTLCSource::OutboundRoute { .. } => {
+                                       mem::drop(channel_state_lock);
+                                       let mut pending_events = self.pending_events.lock().unwrap();
+                                       pending_events.push(events::Event::PaymentSent {
+                                               payment_preimage
+                                       });
+                               },
+                               HTLCSource::PreviousHopData(HTLCPreviousHopData { short_channel_id, htlc_id, .. }) => {
+                                       //TODO: Delay the claimed_funds relaying just like we do outbound relay!
+                                       let channel_state = channel_state_lock.borrow_parts();
 
-                               let chan = channel_state.by_id.get_mut(&chan_id).unwrap();
-                               match chan.get_update_fulfill_htlc_and_commit(htlc_id, payment_preimage) {
-                                       Ok((msgs, monitor_option)) => {
-                                               if let Some(chan_monitor) = monitor_option {
-                                                       if let Err(_e) = self.monitor.add_update_monitor(chan_monitor.get_funding_txo().unwrap(), chan_monitor) {
-                                                               unimplemented!();// but def dont push the event...
-                                                       }
+                                       let chan_id = match channel_state.short_to_id.get(&short_channel_id) {
+                                               Some(chan_id) => chan_id.clone(),
+                                               None => {
+                                                       // TODO: There is probably a channel manager somewhere that needs to
+                                                       // learn the preimage as the channel already hit the chain and that's
+                                                       // why it's missing.
+                                                       return
                                                }
-                                               if let Some((msg, commitment_signed)) = msgs {
-                                                       channel_state.pending_msg_events.push(events::MessageSendEvent::UpdateHTLCs {
-                                                               node_id: chan.get_their_node_id(),
-                                                               updates: msgs::CommitmentUpdate {
-                                                                       update_add_htlcs: Vec::new(),
-                                                                       update_fulfill_htlcs: vec![msg],
-                                                                       update_fail_htlcs: Vec::new(),
-                                                                       update_fail_malformed_htlcs: Vec::new(),
-                                                                       update_fee: None,
-                                                                       commitment_signed,
+                                       };
+
+                                       if let hash_map::Entry::Occupied(mut chan) = channel_state.by_id.entry(chan_id) {
+                                               let was_frozen_for_monitor = chan.get().is_awaiting_monitor_update();
+                                               match chan.get_mut().get_update_fulfill_htlc_and_commit(htlc_id, payment_preimage) {
+                                                       Ok((msgs, monitor_option)) => {
+                                                               if let Some(chan_monitor) = monitor_option {
+                                                                       if let Err(e) = self.monitor.add_update_monitor(chan_monitor.get_funding_txo().unwrap(), chan_monitor) {
+                                                                               if was_frozen_for_monitor {
+                                                                                       assert!(msgs.is_none());
+                                                                               } else {
+                                                                                       break (chan.get().get_their_node_id(), handle_monitor_err!(self, e, channel_state, chan, RAACommitmentOrder::CommitmentFirst, false, msgs.is_some()));
+                                                                               }
+                                                                       }
                                                                }
-                                                       });
+                                                               if let Some((msg, commitment_signed)) = msgs {
+                                                                       channel_state.pending_msg_events.push(events::MessageSendEvent::UpdateHTLCs {
+                                                                               node_id: chan.get().get_their_node_id(),
+                                                                               updates: msgs::CommitmentUpdate {
+                                                                                       update_add_htlcs: Vec::new(),
+                                                                                       update_fulfill_htlcs: vec![msg],
+                                                                                       update_fail_htlcs: Vec::new(),
+                                                                                       update_fail_malformed_htlcs: Vec::new(),
+                                                                                       update_fee: None,
+                                                                                       commitment_signed,
+                                                                               }
+                                                                       });
+                                                               }
+                                                       },
+                                                       Err(_e) => {
+                                                               // TODO: There is probably a channel manager somewhere that needs to
+                                                               // learn the preimage as the channel may be about to hit the chain.
+                                                               //TODO: Do something with e?
+                                                               return
+                                                       },
                                                }
-                                       },
-                                       Err(_e) => {
-                                               // TODO: There is probably a channel manager somewhere that needs to
-                                               // learn the preimage as the channel may be about to hit the chain.
-                                               //TODO: Do something with e?
-                                               return
-                                       },
+                                       } else { unreachable!(); }
+                               },
+                       }
+                       return;
+               };
+
+               match handle_error!(self, err) {
+                       Ok(_) => {},
+                       Err(e) => {
+                               if let Some(msgs::ErrorAction::IgnoreError) = e.action {
+                               } else {
+                                       let mut channel_state = self.channel_state.lock().unwrap();
+                                       channel_state.pending_msg_events.push(events::MessageSendEvent::HandleError {
+                                               node_id: their_node_id,
+                                               action: e.action,
+                                       });
                                }
                        },
                }
@@ -1538,7 +1622,7 @@ impl ChannelManager {
                                                                // knowledge of those gets moved into the appropriate in-memory
                                                                // ChannelMonitor and they get failed backwards once we get
                                                                // on-chain confirmations.
-                                                               // Note I think #198 addresses this, so once its merged a test
+                                                               // Note I think #198 addresses this, so once it's merged a test
                                                                // should be written.
                                                                if let Some(short_id) = channel.get_short_channel_id() {
                                                                        short_to_id.remove(&short_id);
@@ -1838,7 +1922,7 @@ impl ChannelManager {
                //
                //TODO: There exists a further attack where a node may garble the onion data, forward it to
                //us repeatedly garbled in different ways, and compare our error messages, which are
-               //encrypted with the same key. Its not immediately obvious how to usefully exploit that,
+               //encrypted with the same key. It's not immediately obvious how to usefully exploit that,
                //but we should prevent it anyway.
 
                let (mut pending_forward_info, mut channel_state_lock) = self.decode_update_add_htlc_onion(msg);
@@ -2030,10 +2114,16 @@ impl ChannelManager {
                                                //TODO: here and below MsgHandleErrInternal, #153 case
                                                return Err(MsgHandleErrInternal::send_err_msg_no_close("Got a message for a channel from the wrong node!", msg.channel_id));
                                        }
+                                       let was_frozen_for_monitor = chan.get().is_awaiting_monitor_update();
                                        let (commitment_update, pending_forwards, pending_failures, closing_signed, chan_monitor) =
                                                try_chan_entry!(self, chan.get_mut().revoke_and_ack(&msg, &*self.fee_estimator), channel_state, chan);
                                        if let Err(e) = self.monitor.add_update_monitor(chan_monitor.get_funding_txo().unwrap(), chan_monitor) {
-                                               return_monitor_err!(self, e, channel_state, chan, RAACommitmentOrder::CommitmentFirst, false, commitment_update.is_some(), pending_forwards, pending_failures);
+                                               if was_frozen_for_monitor {
+                                                       assert!(commitment_update.is_none() && closing_signed.is_none() && pending_forwards.is_empty() && pending_failures.is_empty());
+                                                       return Err(MsgHandleErrInternal::ignore_no_close("Previous monitor update failure prevented responses to RAA"));
+                                               } else {
+                                                       return_monitor_err!(self, e, channel_state, chan, RAACommitmentOrder::CommitmentFirst, false, commitment_update.is_some(), pending_forwards, pending_failures);
+                                               }
                                        }
                                        if let Some(updates) = commitment_update {
                                                channel_state.pending_msg_events.push(events::MessageSendEvent::UpdateHTLCs {
@@ -2094,7 +2184,7 @@ impl ChannelManager {
                                        try_chan_entry!(self, chan.get_mut().get_channel_announcement(our_node_id.clone(), self.genesis_hash.clone()), channel_state, chan);
 
                                let were_node_one = announcement.node_id_1 == our_node_id;
-                               let msghash = hash_to_message!(&Sha256dHash::from_data(&announcement.encode()[..])[..]);
+                               let msghash = hash_to_message!(&Sha256dHash::hash(&announcement.encode()[..])[..]);
                                if self.secp_ctx.verify(&msghash, &msg.node_signature, if were_node_one { &announcement.node_id_2 } else { &announcement.node_id_1 }).is_err() ||
                                                self.secp_ctx.verify(&msghash, &msg.bitcoin_signature, if were_node_one { &announcement.bitcoin_key_2 } else { &announcement.bitcoin_key_1 }).is_err() {
                                        try_chan_entry!(self, Err(ChannelError::Close("Bad announcement_signatures node_signature")), channel_state, chan);
@@ -2256,7 +2346,7 @@ impl ChannelManager {
 
 impl events::MessageSendEventsProvider for ChannelManager {
        fn get_and_clear_pending_msg_events(&self) -> Vec<events::MessageSendEvent> {
-               // TODO: Event release to users and serialization is currently race-y: its very easy for a
+               // TODO: Event release to users and serialization is currently race-y: it's very easy for a
                // user to serialize a ChannelManager with pending events in it and lose those events on
                // restart. This is doubly true for the fail/fulfill-backs from monitor events!
                {
@@ -2281,7 +2371,7 @@ impl events::MessageSendEventsProvider for ChannelManager {
 
 impl events::EventsProvider for ChannelManager {
        fn get_and_clear_pending_events(&self) -> Vec<events::Event> {
-               // TODO: Event release to users and serialization is currently race-y: its very easy for a
+               // TODO: Event release to users and serialization is currently race-y: it's very easy for a
                // user to serialize a ChannelManager with pending events in it and lose those events on
                // restart. This is doubly true for the fail/fulfill-backs from monitor events!
                {
@@ -2385,7 +2475,7 @@ impl ChainListener for ChannelManager {
        }
 
        /// We force-close the channel without letting our counterparty participate in the shutdown
-       fn block_disconnected(&self, header: &BlockHeader) {
+       fn block_disconnected(&self, header: &BlockHeader, _: u32) {
                let _ = self.total_consistency_lock.read().unwrap();
                let mut failed_channels = Vec::new();
                {
@@ -2547,6 +2637,25 @@ impl ChannelMessageHandler for ChannelManager {
                                        true
                                })
                        }
+                       pending_msg_events.retain(|msg| {
+                               match msg {
+                                       &events::MessageSendEvent::SendAcceptChannel { ref node_id, .. } => node_id != their_node_id,
+                                       &events::MessageSendEvent::SendOpenChannel { ref node_id, .. } => node_id != their_node_id,
+                                       &events::MessageSendEvent::SendFundingCreated { ref node_id, .. } => node_id != their_node_id,
+                                       &events::MessageSendEvent::SendFundingSigned { ref node_id, .. } => node_id != their_node_id,
+                                       &events::MessageSendEvent::SendFundingLocked { ref node_id, .. } => node_id != their_node_id,
+                                       &events::MessageSendEvent::SendAnnouncementSignatures { ref node_id, .. } => node_id != their_node_id,
+                                       &events::MessageSendEvent::UpdateHTLCs { ref node_id, .. } => node_id != their_node_id,
+                                       &events::MessageSendEvent::SendRevokeAndACK { ref node_id, .. } => node_id != their_node_id,
+                                       &events::MessageSendEvent::SendClosingSigned { ref node_id, .. } => node_id != their_node_id,
+                                       &events::MessageSendEvent::SendShutdown { ref node_id, .. } => node_id != their_node_id,
+                                       &events::MessageSendEvent::SendChannelReestablish { ref node_id, .. } => node_id != their_node_id,
+                                       &events::MessageSendEvent::BroadcastChannelAnnouncement { .. } => true,
+                                       &events::MessageSendEvent::BroadcastChannelUpdate { .. } => true,
+                                       &events::MessageSendEvent::HandleError { ref node_id, .. } => node_id != their_node_id,
+                                       &events::MessageSendEvent::PaymentFailureNetworkUpdate { .. } => true,
+                               }
+                       });
                }
                for failure in failed_channels.drain(..) {
                        self.finish_force_close_channel(failure);
@@ -2605,12 +2714,7 @@ const MIN_SERIALIZATION_VERSION: u8 = 1;
 
 impl Writeable for PendingForwardHTLCInfo {
        fn write<W: Writer>(&self, writer: &mut W) -> Result<(), ::std::io::Error> {
-               if let &Some(ref onion) = &self.onion_packet {
-                       1u8.write(writer)?;
-                       onion.write(writer)?;
-               } else {
-                       0u8.write(writer)?;
-               }
+               self.onion_packet.write(writer)?;
                self.incoming_shared_secret.write(writer)?;
                self.payment_hash.write(writer)?;
                self.short_channel_id.write(writer)?;
@@ -2622,13 +2726,8 @@ impl Writeable for PendingForwardHTLCInfo {
 
 impl<R: ::std::io::Read> Readable<R> for PendingForwardHTLCInfo {
        fn read(reader: &mut R) -> Result<PendingForwardHTLCInfo, DecodeError> {
-               let onion_packet = match <u8 as Readable<R>>::read(reader)? {
-                       0 => None,
-                       1 => Some(msgs::OnionPacket::read(reader)?),
-                       _ => return Err(DecodeError::InvalidValue),
-               };
                Ok(PendingForwardHTLCInfo {
-                       onion_packet,
+                       onion_packet: Readable::read(reader)?,
                        incoming_shared_secret: Readable::read(reader)?,
                        payment_hash: Readable::read(reader)?,
                        short_channel_id: Readable::read(reader)?,
@@ -2832,7 +2931,8 @@ impl Writeable for ChannelManager {
                for (payment_hash, previous_hops) in channel_state.claimable_htlcs.iter() {
                        payment_hash.write(writer)?;
                        (previous_hops.len() as u64).write(writer)?;
-                       for previous_hop in previous_hops {
+                       for &(recvd_amt, ref previous_hop) in previous_hops.iter() {
+                               recvd_amt.write(writer)?;
                                previous_hop.write(writer)?;
                        }
                }
@@ -2891,7 +2991,7 @@ pub struct ChannelManagerReadArgs<'a> {
        /// value.get_funding_txo() should be the key).
        ///
        /// If a monitor is inconsistent with the channel state during deserialization the channel will
-       /// be force-closed using the data in the channelmonitor and the Channel will be dropped. This
+       /// be force-closed using the data in the ChannelMonitor and the channel will be dropped. This
        /// is true for missing channels as well. If there is a monitor missing for which we find
        /// channel data Err(DecodeError::InvalidValue) will be returned.
        ///
@@ -2969,7 +3069,7 @@ impl<'a, R : ::std::io::Read> ReadableArgs<R, ChannelManagerReadArgs<'a>> for (S
                        let previous_hops_len: u64 = Readable::read(reader)?;
                        let mut previous_hops = Vec::with_capacity(cmp::min(previous_hops_len as usize, 2));
                        for _ in 0..previous_hops_len {
-                               previous_hops.push(Readable::read(reader)?);
+                               previous_hops.push((Readable::read(reader)?, Readable::read(reader)?));
                        }
                        claimable_htlcs.insert(payment_hash, previous_hops);
                }