X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=src%2Fln%2Fchannelmonitor.rs;h=f3eed0fe16ac0ed9d7e4a59d67f8e82bf5330e8f;hb=3aeec96470cc681bf6bf50baa5ce1b533762c479;hp=f037c673079b2b0071697c012bbbac3d4d4d850d;hpb=27d5a3a94f9bac6d88f4ea364142d98a8ff2dc20;p=rust-lightning diff --git a/src/ln/channelmonitor.rs b/src/ln/channelmonitor.rs index f037c673..f3eed0fe 100644 --- a/src/ln/channelmonitor.rs +++ b/src/ln/channelmonitor.rs @@ -1,3 +1,14 @@ +//! The logic to monitor for on-chain transactions and create the relevant claim responses lives +//! here. +//! ChannelMonitor objects are generated by ChannelManager in response to relevant +//! messages/actions, and MUST be persisted to disk (and, preferably, remotely) before progress can +//! be made in responding to certain messages, see ManyChannelMonitor for more. +//! Note that ChannelMonitors are an important part of the lightning trust model and a copy of the +//! latest ChannelMonitor must always be actively monitoring for chain updates (and no out-of-date +//! ChannelMonitors should do so). Thus, if you're building rust-lightning into an HSM or other +//! security-domain-separated system design, you should consider having multiple paths for +//! ChannelMonitors to get out of the HSM and onto monitoring devices. + use bitcoin::blockdata::block::BlockHeader; use bitcoin::blockdata::transaction::{TxIn,TxOut,SigHashType,Transaction}; use bitcoin::blockdata::transaction::OutPoint as BitcoinOutPoint; @@ -24,6 +35,7 @@ use std::collections::HashMap; use std::sync::{Arc,Mutex}; use std::{hash,cmp}; +/// An error enum representing a failure to persist a channel monitor update. pub enum ChannelMonitorUpdateErr { /// Used to indicate a temporary failure (eg connection to a watchtower failed, but is expected /// to succeed at some point in the future). @@ -63,6 +75,9 @@ pub trait ManyChannelMonitor: Send + Sync { /// If you're using this for local monitoring of your own channels, you probably want to use /// `OutPoint` as the key, which will give you a ManyChannelMonitor implementation. pub struct SimpleManyChannelMonitor { + #[cfg(test)] // Used in ChannelManager tests to manipulate channels directly + pub monitors: Mutex>, + #[cfg(not(test))] monitors: Mutex>, chain_monitor: Arc, broadcaster: Arc @@ -85,6 +100,8 @@ impl ChainListener for SimpleManyChannelMonit } impl SimpleManyChannelMonitor { + /// Creates a new object which can be used to monitor several channels given the chain + /// interface with which to register to receive notifications. pub fn new(chain_monitor: Arc, broadcaster: Arc) -> Arc> { let res = Arc::new(SimpleManyChannelMonitor { monitors: Mutex::new(HashMap::new()), @@ -96,6 +113,7 @@ impl SimpleManyChannelMonitor res } + /// Adds or udpates the monitor which monitors the channel referred to by the given key. pub fn add_update_monitor_by_key(&self, key: Key, monitor: ChannelMonitor) -> Result<(), HandleError> { let mut monitors = self.monitors.lock().unwrap(); match monitors.get_mut(&key) { @@ -159,6 +177,10 @@ struct LocalSignedTx { const SERIALIZATION_VERSION: u8 = 1; const MIN_SERIALIZATION_VERSION: u8 = 1; +/// A ChannelMonitor handles chain events (blocks connected and disconnected) and generates +/// on-chain transactions to ensure no loss of funds occurs. +/// You MUST ensure that no ChannelMonitors for a given channel anywhere contain out-of-date +/// information and are actively monitoring the chain. pub struct ChannelMonitor { funding_txo: Option<(OutPoint, Script)>, commitment_transaction_number_obscure_factor: u64, @@ -266,7 +288,7 @@ impl PartialEq for ChannelMonitor { } impl ChannelMonitor { - pub fn new(revocation_base_key: &SecretKey, delayed_payment_base_key: &PublicKey, htlc_base_key: &SecretKey, our_to_self_delay: u16, destination_script: Script) -> ChannelMonitor { + pub(super) fn new(revocation_base_key: &SecretKey, delayed_payment_base_key: &PublicKey, htlc_base_key: &SecretKey, our_to_self_delay: u16, destination_script: Script) -> ChannelMonitor { ChannelMonitor { funding_txo: None, commitment_transaction_number_obscure_factor: 0, @@ -435,6 +457,9 @@ impl ChannelMonitor { self.payment_preimages.insert(payment_hash.clone(), payment_preimage.clone()); } + /// Combines this ChannelMonitor with the information contained in the other ChannelMonitor. + /// After a successful call this ChannelMonitor is up-to-date and is safe to use to monitor the + /// chain for new blocks/transactions. pub fn insert_combine(&mut self, mut other: ChannelMonitor) -> Result<(), HandleError> { if self.funding_txo.is_some() { // We should be able to compare the entire funding_txo, but in fuzztarget its trivially @@ -496,6 +521,7 @@ impl ChannelMonitor { self.funding_txo = None; } + /// Gets the funding transaction outpoint of the channel this ChannelMonitor is monitoring for. pub fn get_funding_txo(&self) -> Option { match self.funding_txo { Some((outpoint, _)) => Some(outpoint), @@ -900,7 +926,7 @@ impl ChannelMonitor { //we want to leave out (eg funding_txo, etc). /// Can only fail if idx is < get_min_seen_secret - pub fn get_secret(&self, idx: u64) -> Result<[u8; 32], HandleError> { + pub(super) fn get_secret(&self, idx: u64) -> Result<[u8; 32], HandleError> { for i in 0..self.old_secrets.len() { if (idx & (!((1 << i) - 1))) == self.old_secrets[i].1 { return Ok(ChannelMonitor::derive_secret(self.old_secrets[i].0, i as u8, idx)) @@ -910,7 +936,7 @@ impl ChannelMonitor { Err(HandleError{err: "idx too low", action: None}) } - pub fn get_min_seen_secret(&self) -> u64 { + pub(super) fn get_min_seen_secret(&self) -> u64 { //TODO This can be optimized? let mut min = 1 << 48; for &(_, idx) in self.old_secrets.iter() { @@ -1222,7 +1248,7 @@ impl ChannelMonitor { }; } - let secret = self.get_secret(commitment_number).unwrap(); + let secret = ignore_error!(self.get_secret(commitment_number)); let per_commitment_key = ignore_error!(SecretKey::from_slice(&self.secp_ctx, &secret)); let per_commitment_point = PublicKey::from_secret_key(&self.secp_ctx, &per_commitment_key); let revocation_pubkey = match self.key_storage { @@ -1269,7 +1295,6 @@ impl ChannelMonitor { output: outputs, }; - let sighash_parts = bip143::SighashComponents::new(&spend_tx); let sig = match self.key_storage { @@ -1352,9 +1377,14 @@ impl ChannelMonitor { fn block_connected(&self, txn_matched: &[&Transaction], height: u32, broadcaster: &BroadcasterInterface)-> Vec<(Sha256dHash, Vec)> { let mut watch_outputs = Vec::new(); for tx in txn_matched { - let mut txn: Vec = Vec::new(); - for txin in tx.input.iter() { - if self.funding_txo.is_none() || (txin.previous_output.txid == self.funding_txo.as_ref().unwrap().0.txid && txin.previous_output.vout == self.funding_txo.as_ref().unwrap().0.index as u32) { + if tx.input.len() == 1 { + // Assuming our keys were not leaked (in which case we're screwed no matter what), + // commitment transactions and HTLC transactions will all only ever have one input, + // which is an easy way to filter out any potential non-matching txn for lazy + // filters. + let prevout = &tx.input[0].previous_output; + let mut txn: Vec = Vec::new(); + if self.funding_txo.is_none() || (prevout.txid == self.funding_txo.as_ref().unwrap().0.txid && prevout.vout == self.funding_txo.as_ref().unwrap().0.index as u32) { let (remote_txn, new_outputs) = self.check_spend_remote_transaction(tx, height); txn = remote_txn; if !new_outputs.1.is_empty() { @@ -1396,7 +1426,7 @@ impl ChannelMonitor { watch_outputs } - pub fn would_broadcast_at_height(&self, height: u32) -> bool { + pub(super) fn would_broadcast_at_height(&self, height: u32) -> bool { if let Some(ref cur_local_tx) = self.current_local_signed_commitment_tx { for &(ref htlc, _, _) in cur_local_tx.htlc_outputs.iter() { if htlc.cltv_expiry <= height + CLTV_CLAIM_BUFFER {