Merge pull request #1303 from jkczyz/2022-02-docs-with-features

[rust-lightning] / lightning-persister / src / lib.rs

//! Utilities that handle persisting Rust-Lightning data to disk via standard filesystem APIs.

#![deny(broken_intra_doc_links)]
#![deny(missing_docs)]

#![cfg_attr(docsrs, feature(doc_auto_cfg))]

#![cfg_attr(all(test, feature = "_bench_unstable"), feature(test))]
#[cfg(all(test, feature = "_bench_unstable"))] extern crate test;

mod util;

extern crate lightning;
extern crate bitcoin;
extern crate libc;

use bitcoin::hash_types::{BlockHash, Txid};
use bitcoin::hashes::hex::{FromHex, ToHex};
use crate::util::DiskWriteable;
use lightning::chain;
use lightning::chain::chaininterface::{BroadcasterInterface, FeeEstimator};
use lightning::chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate};
use lightning::chain::chainmonitor;
use lightning::chain::keysinterface::{Sign, KeysInterface};
use lightning::chain::transaction::OutPoint;
use lightning::ln::channelmanager::ChannelManager;
use lightning::util::logger::Logger;
use lightning::util::ser::{ReadableArgs, Writeable};
use std::fs;
use std::io::{Cursor, Error};
use std::ops::Deref;
use std::path::{Path, PathBuf};

/// FilesystemPersister persists channel data on disk, where each channel's
/// data is stored in a file named after its funding outpoint.
///
/// Warning: this module does the best it can with calls to persist data, but it
/// can only guarantee that the data is passed to the drive. It is up to the
/// drive manufacturers to do the actual persistence properly, which they often
/// don't (especially on consumer-grade hardware). Therefore, it is up to the
/// user to validate their entire storage stack, to ensure the writes are
/// persistent.
/// Corollary: especially when dealing with larger amounts of money, it is best
/// practice to have multiple channel data backups and not rely only on one
/// FilesystemPersister.
pub struct FilesystemPersister {
        path_to_channel_data: String,
}

impl<Signer: Sign> DiskWriteable for ChannelMonitor<Signer> {
        fn write_to_file(&self, writer: &mut fs::File) -> Result<(), Error> {
                self.write(writer)
        }
}

impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> DiskWriteable for ChannelManager<Signer, M, T, K, F, L>
where
        M::Target: chain::Watch<Signer>,
        T::Target: BroadcasterInterface,
        K::Target: KeysInterface<Signer=Signer>,
        F::Target: FeeEstimator,
        L::Target: Logger,
{
        fn write_to_file(&self, writer: &mut fs::File) -> Result<(), std::io::Error> {
                self.write(writer)
        }
}

impl FilesystemPersister {
        /// Initialize a new FilesystemPersister and set the path to the individual channels'
        /// files.
        pub fn new(path_to_channel_data: String) -> Self {
                return Self {
                        path_to_channel_data,
                }
        }

        /// Get the directory which was provided when this persister was initialized.
        pub fn get_data_dir(&self) -> String {
                self.path_to_channel_data.clone()
        }

        pub(crate) fn path_to_monitor_data(&self) -> PathBuf {
                let mut path = PathBuf::from(self.path_to_channel_data.clone());
                path.push("monitors");
                path
        }

        /// Writes the provided `ChannelManager` to the path provided at `FilesystemPersister`
        /// initialization, within a file called "manager".
        pub fn persist_manager<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>(
                data_dir: String,
                manager: &ChannelManager<Signer, M, T, K, F, L>
        ) -> Result<(), std::io::Error>
        where
                M::Target: chain::Watch<Signer>,
                T::Target: BroadcasterInterface,
                K::Target: KeysInterface<Signer=Signer>,
                F::Target: FeeEstimator,
                L::Target: Logger,
        {
                let path = PathBuf::from(data_dir);
                util::write_to_file(path, "manager".to_string(), manager)
        }

        /// Read `ChannelMonitor`s from disk.
        pub fn read_channelmonitors<Signer: Sign, K: Deref> (
                &self, keys_manager: K
        ) -> Result<Vec<(BlockHash, ChannelMonitor<Signer>)>, std::io::Error>
                where K::Target: KeysInterface<Signer=Signer> + Sized,
        {
                let path = self.path_to_monitor_data();
                if !Path::new(&path).exists() {
                        return Ok(Vec::new());
                }
                let mut res = Vec::new();
                for file_option in fs::read_dir(path).unwrap() {
                        let file = file_option.unwrap();
                        let owned_file_name = file.file_name();
                        let filename = owned_file_name.to_str();
                        if !filename.is_some() || !filename.unwrap().is_ascii() || filename.unwrap().len() < 65 {
                                return Err(std::io::Error::new(
                                        std::io::ErrorKind::InvalidData,
                                        "Invalid ChannelMonitor file name",
                                ));
                        }
                        if filename.unwrap().ends_with(".tmp") {
                                // If we were in the middle of committing an new update and crashed, it should be
                                // safe to ignore the update - we should never have returned to the caller and
                                // irrevocably committed to the new state in any way.
                                continue;
                        }

                        let txid = Txid::from_hex(filename.unwrap().split_at(64).0);
                        if txid.is_err() {
                                return Err(std::io::Error::new(
                                        std::io::ErrorKind::InvalidData,
                                        "Invalid tx ID in filename",
                                ));
                        }

                        let index = filename.unwrap().split_at(65).1.parse();
                        if index.is_err() {
                                return Err(std::io::Error::new(
                                        std::io::ErrorKind::InvalidData,
                                        "Invalid tx index in filename",
                                ));
                        }

                        let contents = fs::read(&file.path())?;
                        let mut buffer = Cursor::new(&contents);
                        match <(BlockHash, ChannelMonitor<Signer>)>::read(&mut buffer, &*keys_manager) {
                                Ok((blockhash, channel_monitor)) => {
                                        if channel_monitor.get_funding_txo().0.txid != txid.unwrap() || channel_monitor.get_funding_txo().0.index != index.unwrap() {
                                                return Err(std::io::Error::new(std::io::ErrorKind::InvalidData, "ChannelMonitor was stored in the wrong file"));
                                        }
                                        res.push((blockhash, channel_monitor));
                                }
                                Err(e) => return Err(std::io::Error::new(
                                        std::io::ErrorKind::InvalidData,
                                        format!("Failed to deserialize ChannelMonitor: {}", e),
                                ))
                        }
                }
                Ok(res)
        }
}

impl<ChannelSigner: Sign> chainmonitor::Persist<ChannelSigner> for FilesystemPersister {
        // TODO: We really need a way for the persister to inform the user that its time to crash/shut
        // down once these start returning failure.
        // A PermanentFailure implies we need to shut down since we're force-closing channels without
        // even broadcasting!

        fn persist_new_channel(&self, funding_txo: OutPoint, monitor: &ChannelMonitor<ChannelSigner>, _update_id: chainmonitor::MonitorUpdateId) -> Result<(), chain::ChannelMonitorUpdateErr> {
                let filename = format!("{}_{}", funding_txo.txid.to_hex(), funding_txo.index);
                util::write_to_file(self.path_to_monitor_data(), filename, monitor)
                        .map_err(|_| chain::ChannelMonitorUpdateErr::PermanentFailure)
        }

        fn update_persisted_channel(&self, funding_txo: OutPoint, _update: &Option<ChannelMonitorUpdate>, monitor: &ChannelMonitor<ChannelSigner>, _update_id: chainmonitor::MonitorUpdateId) -> Result<(), chain::ChannelMonitorUpdateErr> {
                let filename = format!("{}_{}", funding_txo.txid.to_hex(), funding_txo.index);
                util::write_to_file(self.path_to_monitor_data(), filename, monitor)
                        .map_err(|_| chain::ChannelMonitorUpdateErr::PermanentFailure)
        }
}

#[cfg(test)]
mod tests {
        extern crate lightning;
        extern crate bitcoin;
        use crate::FilesystemPersister;
        use bitcoin::blockdata::block::{Block, BlockHeader};
        use bitcoin::hashes::hex::FromHex;
        use bitcoin::Txid;
        use lightning::chain::ChannelMonitorUpdateErr;
        use lightning::chain::chainmonitor::Persist;
        use lightning::chain::transaction::OutPoint;
        use lightning::{check_closed_broadcast, check_closed_event, check_added_monitors};
        use lightning::ln::features::InitFeatures;
        use lightning::ln::functional_test_utils::*;
        use lightning::util::events::{ClosureReason, MessageSendEventsProvider};
        use lightning::util::test_utils;
        use std::fs;
        #[cfg(target_os = "windows")]
        use {
                lightning::get_event_msg,
                lightning::ln::msgs::ChannelMessageHandler,
        };

        impl Drop for FilesystemPersister {
                fn drop(&mut self) {
                        // We test for invalid directory names, so it's OK if directory removal
                        // fails.
                        match fs::remove_dir_all(&self.path_to_channel_data) {
                                Err(e) => println!("Failed to remove test persister directory: {}", e),
                                _ => {}
                        }
                }
        }

        // Integration-test the FilesystemPersister. Test relaying a few payments
        // and check that the persisted data is updated the appropriate number of
        // times.
        #[test]
        fn test_filesystem_persister() {
                // Create the nodes, giving them FilesystemPersisters for data persisters.
                let persister_0 = FilesystemPersister::new("test_filesystem_persister_0".to_string());
                let persister_1 = FilesystemPersister::new("test_filesystem_persister_1".to_string());
                let chanmon_cfgs = create_chanmon_cfgs(2);
                let mut node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
                let chain_mon_0 = test_utils::TestChainMonitor::new(Some(&chanmon_cfgs[0].chain_source), &chanmon_cfgs[0].tx_broadcaster, &chanmon_cfgs[0].logger, &chanmon_cfgs[0].fee_estimator, &persister_0, &node_cfgs[0].keys_manager);
                let chain_mon_1 = test_utils::TestChainMonitor::new(Some(&chanmon_cfgs[1].chain_source), &chanmon_cfgs[1].tx_broadcaster, &chanmon_cfgs[1].logger, &chanmon_cfgs[1].fee_estimator, &persister_1, &node_cfgs[1].keys_manager);
                node_cfgs[0].chain_monitor = chain_mon_0;
                node_cfgs[1].chain_monitor = chain_mon_1;
                let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
                let nodes = create_network(2, &node_cfgs, &node_chanmgrs);

                // Check that the persisted channel data is empty before any channels are
                // open.
                let mut persisted_chan_data_0 = persister_0.read_channelmonitors(nodes[0].keys_manager).unwrap();
                assert_eq!(persisted_chan_data_0.len(), 0);
                let mut persisted_chan_data_1 = persister_1.read_channelmonitors(nodes[1].keys_manager).unwrap();
                assert_eq!(persisted_chan_data_1.len(), 0);

                // Helper to make sure the channel is on the expected update ID.
                macro_rules! check_persisted_data {
                        ($expected_update_id: expr) => {
                                persisted_chan_data_0 = persister_0.read_channelmonitors(nodes[0].keys_manager).unwrap();
                                assert_eq!(persisted_chan_data_0.len(), 1);
                                for (_, mon) in persisted_chan_data_0.iter() {
                                        assert_eq!(mon.get_latest_update_id(), $expected_update_id);
                                }
                                persisted_chan_data_1 = persister_1.read_channelmonitors(nodes[1].keys_manager).unwrap();
                                assert_eq!(persisted_chan_data_1.len(), 1);
                                for (_, mon) in persisted_chan_data_1.iter() {
                                        assert_eq!(mon.get_latest_update_id(), $expected_update_id);
                                }
                        }
                }

                // Create some initial channel and check that a channel was persisted.
                let _ = create_announced_chan_between_nodes(&nodes, 0, 1, InitFeatures::known(), InitFeatures::known());
                check_persisted_data!(0);

                // Send a few payments and make sure the monitors are updated to the latest.
                send_payment(&nodes[0], &vec!(&nodes[1])[..], 8000000);
                check_persisted_data!(5);
                send_payment(&nodes[1], &vec!(&nodes[0])[..], 4000000);
                check_persisted_data!(10);

                // Force close because cooperative close doesn't result in any persisted
                // updates.
                nodes[0].node.force_close_channel(&nodes[0].node.list_channels()[0].channel_id).unwrap();
                check_closed_event!(nodes[0], 1, ClosureReason::HolderForceClosed);
                check_closed_broadcast!(nodes[0], true);
                check_added_monitors!(nodes[0], 1);

                let node_txn = nodes[0].tx_broadcaster.txn_broadcasted.lock().unwrap();
                assert_eq!(node_txn.len(), 1);

                let header = BlockHeader { version: 0x20000000, prev_blockhash: nodes[0].best_block_hash(), merkle_root: Default::default(), time: 42, bits: 42, nonce: 42 };
                connect_block(&nodes[1], &Block { header, txdata: vec![node_txn[0].clone(), node_txn[0].clone()]});
                check_closed_broadcast!(nodes[1], true);
                check_closed_event!(nodes[1], 1, ClosureReason::CommitmentTxConfirmed);
                check_added_monitors!(nodes[1], 1);

                // Make sure everything is persisted as expected after close.
                check_persisted_data!(11);
        }

        // Test that if the persister's path to channel data is read-only, writing a
        // monitor to it results in the persister returning a PermanentFailure.
        // Windows ignores the read-only flag for folders, so this test is Unix-only.
        #[cfg(not(target_os = "windows"))]
        #[test]
        fn test_readonly_dir_perm_failure() {
                let persister = FilesystemPersister::new("test_readonly_dir_perm_failure".to_string());
                fs::create_dir_all(&persister.path_to_channel_data).unwrap();

                // Set up a dummy channel and force close. This will produce a monitor
                // that we can then use to test persistence.
                let chanmon_cfgs = create_chanmon_cfgs(2);
                let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
                let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
                let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
                let chan = create_announced_chan_between_nodes(&nodes, 0, 1, InitFeatures::known(), InitFeatures::known());
                nodes[1].node.force_close_channel(&chan.2).unwrap();
                check_closed_event!(nodes[1], 1, ClosureReason::HolderForceClosed);
                let mut added_monitors = nodes[1].chain_monitor.added_monitors.lock().unwrap();
                let update_map = nodes[1].chain_monitor.latest_monitor_update_id.lock().unwrap();
                let update_id = update_map.get(&added_monitors[0].0.to_channel_id()).unwrap();

                // Set the persister's directory to read-only, which should result in
                // returning a permanent failure when we then attempt to persist a
                // channel update.
                let path = &persister.path_to_channel_data;
                let mut perms = fs::metadata(path).unwrap().permissions();
                perms.set_readonly(true);
                fs::set_permissions(path, perms).unwrap();

                let test_txo = OutPoint {
                        txid: Txid::from_hex("8984484a580b825b9972d7adb15050b3ab624ccd731946b3eeddb92f4e7ef6be").unwrap(),
                        index: 0
                };
                match persister.persist_new_channel(test_txo, &added_monitors[0].1, update_id.2) {
                        Err(ChannelMonitorUpdateErr::PermanentFailure) => {},
                        _ => panic!("unexpected result from persisting new channel")
                }

                nodes[1].node.get_and_clear_pending_msg_events();
                added_monitors.clear();
        }

        // Test that if a persister's directory name is invalid, monitor persistence
        // will fail.
        #[cfg(target_os = "windows")]
        #[test]
        fn test_fail_on_open() {
                // Set up a dummy channel and force close. This will produce a monitor
                // that we can then use to test persistence.
                let chanmon_cfgs = create_chanmon_cfgs(2);
                let mut node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
                let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
                let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
                let chan = create_announced_chan_between_nodes(&nodes, 0, 1, InitFeatures::known(), InitFeatures::known());
                nodes[1].node.force_close_channel(&chan.2).unwrap();
                check_closed_event!(nodes[1], 1, ClosureReason::HolderForceClosed);
                let mut added_monitors = nodes[1].chain_monitor.added_monitors.lock().unwrap();
                let update_map = nodes[1].chain_monitor.latest_monitor_update_id.lock().unwrap();
                let update_id = update_map.get(&added_monitors[0].0.to_channel_id()).unwrap();

                // Create the persister with an invalid directory name and test that the
                // channel fails to open because the directories fail to be created. There
                // don't seem to be invalid filename characters on Unix that Rust doesn't
                // handle, hence why the test is Windows-only.
                let persister = FilesystemPersister::new(":<>/".to_string());

                let test_txo = OutPoint {
                        txid: Txid::from_hex("8984484a580b825b9972d7adb15050b3ab624ccd731946b3eeddb92f4e7ef6be").unwrap(),
                        index: 0
                };
                match persister.persist_new_channel(test_txo, &added_monitors[0].1, update_id.2) {
                        Err(ChannelMonitorUpdateErr::PermanentFailure) => {},
                        _ => panic!("unexpected result from persisting new channel")
                }

                nodes[1].node.get_and_clear_pending_msg_events();
                added_monitors.clear();
        }
}

#[cfg(all(test, feature = "_bench_unstable"))]
pub mod bench {
        use test::Bencher;

        #[bench]
        fn bench_sends(bench: &mut Bencher) {
                let persister_a = super::FilesystemPersister::new("bench_filesystem_persister_a".to_string());
                let persister_b = super::FilesystemPersister::new("bench_filesystem_persister_b".to_string());
                lightning::ln::channelmanager::bench::bench_two_sends(bench, persister_a, persister_b);
        }
}