X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=src%2Fsweep.rs;fp=src%2Fsweep.rs;h=2a168a7d9235bbf4af012857ef36273863dd3b80;hb=b0987a419c33d81ef1e8ff135b6ffaff75a6a236;hp=0000000000000000000000000000000000000000;hpb=a0112e0db7bc145ee52859b1197104c76213daa1;p=ldk-sample diff --git a/src/sweep.rs b/src/sweep.rs new file mode 100644 index 0000000..2a168a7 --- /dev/null +++ b/src/sweep.rs @@ -0,0 +1,127 @@ +use std::io::{Read, Seek, SeekFrom}; +use std::path::PathBuf; +use std::sync::Arc; +use std::time::Duration; +use std::{fs, io}; + +use lightning::chain::chaininterface::{BroadcasterInterface, ConfirmationTarget, FeeEstimator}; +use lightning::chain::keysinterface::{EntropySource, KeysManager, SpendableOutputDescriptor}; +use lightning::util::logger::Logger; +use lightning::util::persist::KVStorePersister; +use lightning::util::ser::{Readable, WithoutLength}; + +use bitcoin::secp256k1::Secp256k1; + +use crate::hex_utils; +use crate::BitcoindClient; +use crate::FilesystemLogger; +use crate::FilesystemPersister; + +/// If we have any pending claimable outputs, we should slowly sweep them to our Bitcoin Core +/// wallet. We technically don't need to do this - they're ours to spend when we want and can just +/// use them to build new transactions instead, but we cannot feed them direclty into Bitcoin +/// Core's wallet so we have to sweep. +/// +/// Note that this is unececssary for [`SpendableOutputDescriptor::StaticOutput`]s, which *do* have +/// an associated secret key we could simply import into Bitcoin Core's wallet, but for consistency +/// we don't do that here either. +pub(crate) async fn periodic_sweep( + ldk_data_dir: String, keys_manager: Arc, logger: Arc, + persister: Arc, bitcoind_client: Arc, +) { + // Regularly claim outputs which are exclusively spendable by us and send them to Bitcoin Core. + // Note that if you more tightly integrate your wallet with LDK you may not need to do this - + // these outputs can just be treated as normal outputs during coin selection. + let pending_spendables_dir = + format!("{}/{}", crate::PENDING_SPENDABLE_OUTPUT_DIR, ldk_data_dir); + let processing_spendables_dir = format!("{}/processing_spendable_outputs", ldk_data_dir); + let spendables_dir = format!("{}/spendable_outputs", ldk_data_dir); + + // We batch together claims of all spendable outputs generated each day, however only after + // batching any claims of spendable outputs which were generated prior to restart. On a mobile + // device we likely won't ever be online for more than a minute, so we have to ensure we sweep + // any pending claims on startup, but for an always-online node you may wish to sweep even less + // frequently than this (or move the interval await to the top of the loop)! + // + // There is no particular rush here, we just have to ensure funds are availably by the time we + // need to send funds. + let mut interval = tokio::time::interval(Duration::from_secs(60 * 60 * 24)); + + loop { + interval.tick().await; // Note that the first tick completes immediately + if let Ok(dir_iter) = fs::read_dir(&pending_spendables_dir) { + // Move any spendable descriptors from pending folder so that we don't have any + // races with new files being added. + for file_res in dir_iter { + let file = file_res.unwrap(); + // Only move a file if its a 32-byte-hex'd filename, otherwise it might be a + // temporary file. + if file.file_name().len() == 64 { + fs::create_dir_all(&processing_spendables_dir).unwrap(); + let mut holding_path = PathBuf::new(); + holding_path.push(&processing_spendables_dir); + holding_path.push(&file.file_name()); + fs::rename(file.path(), holding_path).unwrap(); + } + } + // Now concatenate all the pending files we moved into one file in the + // `spendable_outputs` directory and drop the processing directory. + let mut outputs = Vec::new(); + if let Ok(processing_iter) = fs::read_dir(&processing_spendables_dir) { + for file_res in processing_iter { + outputs.append(&mut fs::read(file_res.unwrap().path()).unwrap()); + } + } + if !outputs.is_empty() { + let key = hex_utils::hex_str(&keys_manager.get_secure_random_bytes()); + persister + .persist(&format!("spendable_outputs/{}", key), &WithoutLength(&outputs)) + .unwrap(); + fs::remove_dir_all(&processing_spendables_dir).unwrap(); + } + } + // Iterate over all the sets of spendable outputs in `spendables_dir` and try to claim + // them. + // Note that here we try to claim each set of spendable outputs over and over again + // forever, even long after its been claimed. While this isn't an issue per se, in practice + // you may wish to track when the claiming transaction has confirmed and remove the + // spendable outputs set. You may also wish to merge groups of unspent spendable outputs to + // combine batches. + if let Ok(dir_iter) = fs::read_dir(&spendables_dir) { + for file_res in dir_iter { + let mut outputs: Vec = Vec::new(); + let mut file = fs::File::open(file_res.unwrap().path()).unwrap(); + loop { + // Check if there are any bytes left to read, and if so read a descriptor. + match file.read_exact(&mut [0; 1]) { + Ok(_) => { + file.seek(SeekFrom::Current(-1)).unwrap(); + } + Err(e) if e.kind() == io::ErrorKind::UnexpectedEof => break, + Err(e) => Err(e).unwrap(), + } + outputs.push(Readable::read(&mut file).unwrap()); + } + let destination_address = bitcoind_client.get_new_address().await; + let output_descriptors = &outputs.iter().map(|a| a).collect::>(); + let tx_feerate = + bitcoind_client.get_est_sat_per_1000_weight(ConfirmationTarget::Background); + if let Ok(spending_tx) = keys_manager.spend_spendable_outputs( + output_descriptors, + Vec::new(), + destination_address.script_pubkey(), + tx_feerate, + &Secp256k1::new(), + ) { + // Note that, most likely, we've already sweeped this set of outputs + // and they're already confirmed on-chain, so this broadcast will fail. + bitcoind_client.broadcast_transaction(&spending_tx); + } else { + lightning::log_error!( + logger, + "Failed to sweep spendable outputs! This may indicate the outputs are dust. Will try again in a day."); + } + } + } + } +}