10537513186

Committed 24 Aug 2024 09:36AM UTC coverage: 82.091% (+0.2%) from 81.848%

Build # 10537513186

Build Type

Pull #1569

github

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web-flow

Commit Message

Merge 5144f7c71 into 9e6ac72a6

Pull Request Pull Request #1569: `bdk_core` WIP WIP WIP

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/crates/electrum/src/bdk_electrum_client.rs

use bdk_core::{
    bitcoin::{block::Header, BlockHash, OutPoint, ScriptBuf, Transaction, Txid},
    collections::{BTreeMap, HashMap},
    spk_client::{FullScanRequest, FullScanResult, SyncRequest, SyncResult},
    tx_graph, BlockId, CheckPoint, ConfirmationBlockTime,
};
use electrum_client::{ElectrumApi, Error, HeaderNotification};
use std::{
    collections::HashSet,
    sync::{Arc, Mutex},
};

/// We include a chain suffix of a certain length for the purpose of robustness.
const CHAIN_SUFFIX_LENGTH: u32 = 8;

/// Wrapper around an [`electrum_client::ElectrumApi`] which includes an internal in-memory
/// transaction cache to avoid re-fetching already downloaded transactions.
#[derive(Debug)]
pub struct BdkElectrumClient<E> {
    /// The internal [`electrum_client::ElectrumApi`]
    pub inner: E,
    /// The transaction cache
    tx_cache: Mutex<HashMap<Txid, Arc<Transaction>>>,
    /// The header cache
    block_header_cache: Mutex<HashMap<u32, Header>>,
}

impl<E: ElectrumApi> BdkElectrumClient<E> {
    /// Creates a new bdk client from a [`electrum_client::ElectrumApi`]
    pub fn new(client: E) -> Self {
        Self {
            inner: client,
            tx_cache: Default::default(),
            block_header_cache: Default::default(),
        }
    }

    /// Inserts transactions into the transaction cache so that the client will not fetch these
    /// transactions.
    pub fn populate_tx_cache(&self, txs: impl IntoIterator<Item = impl Into<Arc<Transaction>>>) {
        let mut tx_cache = self.tx_cache.lock().unwrap();
        for tx in txs {
            let tx = tx.into();
            let txid = tx.compute_txid();
            tx_cache.insert(txid, tx);
        }
    }

    /// Fetch transaction of given `txid`.
    ///
    /// If it hits the cache it will return the cached version and avoid making the request.
    pub fn fetch_tx(&self, txid: Txid) -> Result<Arc<Transaction>, Error> {
        let tx_cache = self.tx_cache.lock().unwrap();

        if let Some(tx) = tx_cache.get(&txid) {
            return Ok(Arc::clone(tx));
        }

        drop(tx_cache);

        let tx = Arc::new(self.inner.transaction_get(&txid)?);

        self.tx_cache.lock().unwrap().insert(txid, Arc::clone(&tx));

        Ok(tx)
    }

    /// Fetch block header of given `height`.
    ///
    /// If it hits the cache it will return the cached version and avoid making the request.
    fn fetch_header(&self, height: u32) -> Result<Header, Error> {
        let block_header_cache = self.block_header_cache.lock().unwrap();

        if let Some(header) = block_header_cache.get(&height) {
            return Ok(*header);
        }

        drop(block_header_cache);

        self.update_header(height)
    }

    /// Update a block header at given `height`. Returns the updated header.
    fn update_header(&self, height: u32) -> Result<Header, Error> {
        let header = self.inner.block_header(height as usize)?;

        self.block_header_cache
            .lock()
            .unwrap()
            .insert(height, header);

        Ok(header)
    }

    /// Broadcasts a transaction to the network.
    ///
    /// This is a re-export of [`ElectrumApi::transaction_broadcast`].
    pub fn transaction_broadcast(&self, tx: &Transaction) -> Result<Txid, Error> {
        self.inner.transaction_broadcast(tx)
    }

    /// Full scan the keychain scripts specified with the blockchain (via an Electrum client) and
    /// returns updates for [`bdk_chain`] data structures.
    ///
    /// - `request`: struct with data required to perform a spk-based blockchain client full scan,
    ///              see [`FullScanRequest`].
    /// - `stop_gap`: the full scan for each keychain stops after a gap of script pubkeys with no
    ///               associated transactions.
    /// - `batch_size`: specifies the max number of script pubkeys to request for in a single batch
    ///                 request.
    /// - `fetch_prev_txouts`: specifies whether we want previous `TxOut`s for fee calculation.
    ///                        Note that this requires additional calls to the Electrum server, but
    ///                        is necessary for calculating the fee on a transaction if your wallet
    ///                        does not own the inputs. Methods like [`Wallet.calculate_fee`] and
    ///                        [`Wallet.calculate_fee_rate`] will return a
    ///                        [`CalculateFeeError::MissingTxOut`] error if those `TxOut`s are not
    ///                        present in the transaction graph.
    ///
    /// [`CalculateFeeError::MissingTxOut`]: bdk_chain::tx_graph::CalculateFeeError::MissingTxOut
    /// [`Wallet.calculate_fee`]: https://docs.rs/bdk_wallet/latest/bdk_wallet/struct.Wallet.html#method.calculate_fee
    /// [`Wallet.calculate_fee_rate`]: https://docs.rs/bdk_wallet/latest/bdk_wallet/struct.Wallet.html#method.calculate_fee_rate
    pub fn full_scan<K: Ord + Clone>(
        &self,
        request: impl Into<FullScanRequest<K>>,
        stop_gap: usize,
        batch_size: usize,
        fetch_prev_txouts: bool,
    ) -> Result<FullScanResult<K>, Error> {
        let mut request: FullScanRequest<K> = request.into();

        let tip_and_latest_blocks = match request.chain_tip() {
            Some(chain_tip) => Some(fetch_tip_and_latest_blocks(&self.inner, chain_tip)?),
            None => None,
        };

        let mut graph_update = tx_graph::Update::<ConfirmationBlockTime>::default();
        let mut last_active_indices = BTreeMap::<K, u32>::default();
        for keychain in request.keychains() {
            let spks = request.iter_spks(keychain.clone());
            if let Some(last_active_index) =
                self.populate_with_spks(&mut graph_update, spks, stop_gap, batch_size)?
            {
                last_active_indices.insert(keychain, last_active_index);
            }
        }

        // Fetch previous `TxOut`s for fee calculation if flag is enabled.
        if fetch_prev_txouts {
            self.fetch_prev_txout(&mut graph_update)?;
        }

        let chain_update = match tip_and_latest_blocks {
            Some((chain_tip, latest_blocks)) => Some(chain_update(
                chain_tip,
                &latest_blocks,
                graph_update.anchors.iter().cloned(),
            )?),
            _ => None,
        };

        Ok(FullScanResult {
            graph_update,
            chain_update,
            last_active_indices,
        })
    }

    /// Sync a set of scripts with the blockchain (via an Electrum client) for the data specified
    /// and returns updates for [`bdk_chain`] data structures.
    ///
    /// - `request`: struct with data required to perform a spk-based blockchain client sync,
    ///              see [`SyncRequest`]
    /// - `batch_size`: specifies the max number of script pubkeys to request for in a single batch
    ///                 request
    /// - `fetch_prev_txouts`: specifies whether we want previous `TxOut`s for fee calculation.
    ///                        Note that this requires additional calls to the Electrum server, but
    ///                        is necessary for calculating the fee on a transaction if your wallet
    ///                        does not own the inputs. Methods like [`Wallet.calculate_fee`] and
    ///                        [`Wallet.calculate_fee_rate`] will return a
    ///                        [`CalculateFeeError::MissingTxOut`] error if those `TxOut`s are not
    ///                        present in the transaction graph.
    ///
    /// If the scripts to sync are unknown, such as when restoring or importing a keychain that
    /// may include scripts that have been used, use [`full_scan`] with the keychain.
    ///
    /// [`full_scan`]: Self::full_scan
    /// [`CalculateFeeError::MissingTxOut`]: bdk_chain::tx_graph::CalculateFeeError::MissingTxOut
    /// [`Wallet.calculate_fee`]: https://docs.rs/bdk_wallet/latest/bdk_wallet/struct.Wallet.html#method.calculate_fee
    /// [`Wallet.calculate_fee_rate`]: https://docs.rs/bdk_wallet/latest/bdk_wallet/struct.Wallet.html#method.calculate_fee_rate
    pub fn sync<I: 'static>(
        &self,
        request: impl Into<SyncRequest<I>>,
        batch_size: usize,
        fetch_prev_txouts: bool,
    ) -> Result<SyncResult, Error> {
        let mut request: SyncRequest<I> = request.into();

        let tip_and_latest_blocks = match request.chain_tip() {
            Some(chain_tip) => Some(fetch_tip_and_latest_blocks(&self.inner, chain_tip)?),
            None => None,
        };

        let mut graph_update = tx_graph::Update::<ConfirmationBlockTime>::default();
        self.populate_with_spks(
            &mut graph_update,
            request
                .iter_spks()
                .enumerate()
                .map(|(i, spk)| (i as u32, spk)),
            usize::MAX,
            batch_size,
        )?;
        self.populate_with_txids(&mut graph_update, request.iter_txids())?;
        self.populate_with_outpoints(&mut graph_update, request.iter_outpoints())?;

        // Fetch previous `TxOut`s for fee calculation if flag is enabled.
        if fetch_prev_txouts {
            self.fetch_prev_txout(&mut graph_update)?;
        }

        let chain_update = match tip_and_latest_blocks {
            Some((chain_tip, latest_blocks)) => Some(chain_update(
                chain_tip,
                &latest_blocks,
                graph_update.anchors.iter().cloned(),
            )?),
            None => None,
        };

        Ok(SyncResult {
            graph_update,
            chain_update,
        })
    }

    /// Populate the `graph_update` with transactions/anchors associated with the given `spks`.
    ///
    /// Transactions that contains an output with requested spk, or spends form an output with
    /// requested spk will be added to `graph_update`. Anchors of the aforementioned transactions are
    /// also included.
    fn populate_with_spks(
        &self,
        graph_update: &mut tx_graph::Update<ConfirmationBlockTime>,
        mut spks: impl Iterator<Item = (u32, ScriptBuf)>,
        stop_gap: usize,
        batch_size: usize,
    ) -> Result<Option<u32>, Error> {
        let mut unused_spk_count = 0_usize;
        let mut last_active_index = Option::<u32>::None;

        loop {
            let spks = (0..batch_size)
                .map_while(|_| spks.next())
                .collect::<Vec<_>>();
            if spks.is_empty() {
                return Ok(last_active_index);
            }

            let spk_histories = self
                .inner
                .batch_script_get_history(spks.iter().map(|(_, s)| s.as_script()))?;

            for ((spk_index, _spk), spk_history) in spks.into_iter().zip(spk_histories) {
                if spk_history.is_empty() {
                    unused_spk_count = unused_spk_count.saturating_add(1);
                    if unused_spk_count >= stop_gap {
                        return Ok(last_active_index);
                    }
                    continue;
                } else {
                    last_active_index = Some(spk_index);
                    unused_spk_count = 0;
                }

                for tx_res in spk_history {
                    graph_update.txs.push(self.fetch_tx(tx_res.tx_hash)?);
                    self.validate_merkle_for_anchor(graph_update, tx_res.tx_hash, tx_res.height)?;
                }
            }
        }
    }

    /// Populate the `graph_update` with associated transactions/anchors of `outpoints`.
    ///
    /// Transactions in which the outpoint resides, and transactions that spend from the outpoint are
    /// included. Anchors of the aforementioned transactions are included.
    fn populate_with_outpoints(
        &self,
        graph_update: &mut tx_graph::Update<ConfirmationBlockTime>,
        outpoints: impl IntoIterator<Item = OutPoint>,
    ) -> Result<(), Error> {
        for outpoint in outpoints {
            let op_txid = outpoint.txid;
            let op_tx = self.fetch_tx(op_txid)?;
            let op_txout = match op_tx.output.get(outpoint.vout as usize) {
                Some(txout) => txout,
                None => continue,
            };
            debug_assert_eq!(op_tx.compute_txid(), op_txid);

            // attempt to find the following transactions (alongside their chain positions), and
            // add to our sparsechain `update`:
            let mut has_residing = false; // tx in which the outpoint resides
            let mut has_spending = false; // tx that spends the outpoint
            for res in self.inner.script_get_history(&op_txout.script_pubkey)? {
                if has_residing && has_spending {
                    break;
                }

                if !has_residing && res.tx_hash == op_txid {
                    has_residing = true;
                    graph_update.txs.push(Arc::clone(&op_tx));
                    self.validate_merkle_for_anchor(graph_update, res.tx_hash, res.height)?;
                }

                if !has_spending && res.tx_hash != op_txid {
                    let res_tx = self.fetch_tx(res.tx_hash)?;
                    // we exclude txs/anchors that do not spend our specified outpoint(s)
                    has_spending = res_tx
                        .input
                        .iter()
                        .any(|txin| txin.previous_output == outpoint);
                    if !has_spending {
                        continue;
                    }
                    graph_update.txs.push(Arc::clone(&res_tx));
                    self.validate_merkle_for_anchor(graph_update, res.tx_hash, res.height)?;
                }
            }
        }
        Ok(())
    }

    /// Populate the `graph_update` with transactions/anchors of the provided `txids`.
    fn populate_with_txids(
        &self,
        graph_update: &mut tx_graph::Update<ConfirmationBlockTime>,
        txids: impl IntoIterator<Item = Txid>,
    ) -> Result<(), Error> {
        for txid in txids {
            let tx = match self.fetch_tx(txid) {
                Ok(tx) => tx,
                Err(electrum_client::Error::Protocol(_)) => continue,
                Err(other_err) => return Err(other_err),
            };

            let spk = tx
                .output
                .first()
                .map(|txo| &txo.script_pubkey)
                .expect("tx must have an output");

            // because of restrictions of the Electrum API, we have to use the `script_get_history`
            // call to get confirmation status of our transaction
            if let Some(r) = self
                .inner
                .script_get_history(spk)?
                .into_iter()
                .find(|r| r.tx_hash == txid)
            {
                self.validate_merkle_for_anchor(graph_update, txid, r.height)?;
            }

            graph_update.txs.push(tx);
        }
        Ok(())
    }

    // Helper function which checks if a transaction is confirmed by validating the merkle proof.
    // An anchor is inserted if the transaction is validated to be in a confirmed block.
    fn validate_merkle_for_anchor(
        &self,
        graph_update: &mut tx_graph::Update<ConfirmationBlockTime>,
        txid: Txid,
        confirmation_height: i32,
    ) -> Result<(), Error> {
        if let Ok(merkle_res) = self
            .inner
            .transaction_get_merkle(&txid, confirmation_height as usize)
        {
            let mut header = self.fetch_header(merkle_res.block_height as u32)?;
            let mut is_confirmed_tx = electrum_client::utils::validate_merkle_proof(
                &txid,
                &header.merkle_root,
                &merkle_res,
            );

            // Merkle validation will fail if the header in `block_header_cache` is outdated, so we
            // want to check if there is a new header and validate against the new one.
            if !is_confirmed_tx {
                header = self.update_header(merkle_res.block_height as u32)?;
                is_confirmed_tx = electrum_client::utils::validate_merkle_proof(
                    &txid,
                    &header.merkle_root,
                    &merkle_res,
                );
            }

            if is_confirmed_tx {
                graph_update.anchors.insert((
                    ConfirmationBlockTime {
                        confirmation_time: header.time as u64,
                        block_id: BlockId {
                            height: merkle_res.block_height as u32,
                            hash: header.block_hash(),
                        },
                    },
                    txid,
                ));
            }
        }
        Ok(())
    }

    // Helper function which fetches the `TxOut`s of our relevant transactions' previous transactions,
    // which we do not have by default. This data is needed to calculate the transaction fee.
    fn fetch_prev_txout(
        &self,
        graph_update: &mut tx_graph::Update<ConfirmationBlockTime>,
    ) -> Result<(), Error> {
        let mut no_dup = HashSet::<Txid>::new();
        for tx in &graph_update.txs {
            if no_dup.insert(tx.compute_txid()) {
                for vin in &tx.input {
                    let outpoint = vin.previous_output;
                    let vout = outpoint.vout;
                    let prev_tx = self.fetch_tx(outpoint.txid)?;
                    let txout = prev_tx.output[vout as usize].clone();
                    let _ = graph_update.txouts.insert(outpoint, txout);
                }
            }
        }
        Ok(())
    }
}

/// Return a [`CheckPoint`] of the latest tip, that connects with `prev_tip`. The latest blocks are
/// fetched to construct checkpoint updates with the proper [`BlockHash`] in case of re-org.
fn fetch_tip_and_latest_blocks(
    client: &impl ElectrumApi,
    prev_tip: CheckPoint,
) -> Result<(CheckPoint, BTreeMap<u32, BlockHash>), Error> {
    let HeaderNotification { height, .. } = client.block_headers_subscribe()?;
    let new_tip_height = height as u32;

    // If electrum returns a tip height that is lower than our previous tip, then checkpoints do
    // not need updating. We just return the previous tip and use that as the point of agreement.
    if new_tip_height < prev_tip.height() {
        return Ok((prev_tip, BTreeMap::new()));
    }

    // Atomically fetch the latest `CHAIN_SUFFIX_LENGTH` count of blocks from Electrum. We use this
    // to construct our checkpoint update.
    let mut new_blocks = {
        let start_height = new_tip_height.saturating_sub(CHAIN_SUFFIX_LENGTH - 1);
        let hashes = client
            .block_headers(start_height as _, CHAIN_SUFFIX_LENGTH as _)?
            .headers
            .into_iter()
            .map(|h| h.block_hash());
        (start_height..).zip(hashes).collect::<BTreeMap<u32, _>>()
    };

    // Find the "point of agreement" (if any).
    let agreement_cp = {
        let mut agreement_cp = Option::<CheckPoint>::None;
        for cp in prev_tip.iter() {
            let cp_block = cp.block_id();
            let hash = match new_blocks.get(&cp_block.height) {
                Some(&hash) => hash,
                None => {
                    assert!(
                        new_tip_height >= cp_block.height,
                        "already checked that electrum's tip cannot be smaller"
                    );
                    let hash = client.block_header(cp_block.height as _)?.block_hash();
                    new_blocks.insert(cp_block.height, hash);
                    hash
                }
            };
            if hash == cp_block.hash {
                agreement_cp = Some(cp);
                break;
            }
        }
        agreement_cp
    };

    let agreement_height = agreement_cp.as_ref().map(CheckPoint::height);

    let new_tip = new_blocks
        .iter()
        // Prune `new_blocks` to only include blocks that are actually new.
        .filter(|(height, _)| Some(*<&u32>::clone(height)) > agreement_height)
        .map(|(height, hash)| BlockId {
            height: *height,
            hash: *hash,
        })
        .fold(agreement_cp, |prev_cp, block| {
            Some(match prev_cp {
                Some(cp) => cp.push(block).expect("must extend checkpoint"),
                None => CheckPoint::new(block),
            })
        })
        .expect("must have at least one checkpoint");

    Ok((new_tip, new_blocks))
}

// Add a corresponding checkpoint per anchor height if it does not yet exist. Checkpoints should not
// surpass `latest_blocks`.
fn chain_update(
    mut tip: CheckPoint,
    latest_blocks: &BTreeMap<u32, BlockHash>,
    anchors: impl Iterator<Item = (ConfirmationBlockTime, Txid)>,
) -> Result<CheckPoint, Error> {
    for (anchor, _txid) in anchors {
        let height = anchor.block_id.height;

        // Checkpoint uses the `BlockHash` from `latest_blocks` so that the hash will be consistent
        // in case of a re-org.
        if tip.get(height).is_none() && height <= tip.height() {
            let hash = match latest_blocks.get(&height) {
                Some(&hash) => hash,
                None => anchor.block_id.hash,
            };
            tip = tip.insert(BlockId { hash, height });
        }
    }
    Ok(tip)
}

1	use bdk_core::{
2	bitcoin::{block::Header, BlockHash, OutPoint, ScriptBuf, Transaction, Txid},
3	collections::{BTreeMap, HashMap},
4	spk_client::{FullScanRequest, FullScanResult, SyncRequest, SyncResult},
5	tx_graph, BlockId, CheckPoint, ConfirmationBlockTime,
6	};
7	use electrum_client::{ElectrumApi, Error, HeaderNotification};
8	use std::{
9	collections::HashSet,
10	sync::{Arc, Mutex},
11	};
12
13	/// We include a chain suffix of a certain length for the purpose of robustness.
14	const CHAIN_SUFFIX_LENGTH: u32 = 8;
15
16	/// Wrapper around an [`electrum_client::ElectrumApi`] which includes an internal in-memory
17	/// transaction cache to avoid re-fetching already downloaded transactions.
18	#[derive(Debug)]
19	pub struct BdkElectrumClient<E> {
20	/// The internal [`electrum_client::ElectrumApi`]
21	pub inner: E,
22	/// The transaction cache
23	tx_cache: Mutex<HashMap<Txid, Arc<Transaction>>>,
24	/// The header cache
25	block_header_cache: Mutex<HashMap<u32, Header>>,
26	}
27
28	impl<E: ElectrumApi> BdkElectrumClient<E> {
29	/// Creates a new bdk client from a [`electrum_client::ElectrumApi`]
30	pub fn new(client: E) -> Self {	4✔
31	Self {	4✔
32	inner: client,	4✔
33	tx_cache: Default::default(),	4✔
34	block_header_cache: Default::default(),	4✔
35	}	4✔
36	}	4✔
37
38	/// Inserts transactions into the transaction cache so that the client will not fetch these
39	/// transactions.
NEW 40	pub fn populate_tx_cache(&self, txs: impl IntoIterator<Item = impl Into<Arc<Transaction>>>) {	×
41	let mut tx_cache = self.tx_cache.lock().unwrap();	×
NEW 42	for tx in txs {	×
NEW 43	let tx = tx.into();	×
NEW 44	let txid = tx.compute_txid();	×
45	tx_cache.insert(txid, tx);	×
46	}	×
47	}	×
48
49	/// Fetch transaction of given `txid`.
50	///
51	/// If it hits the cache it will return the cached version and avoid making the request.
52	pub fn fetch_tx(&self, txid: Txid) -> Result<Arc<Transaction>, Error> {	104✔
53	let tx_cache = self.tx_cache.lock().unwrap();	104✔
54
55	if let Some(tx) = tx_cache.get(&txid) {	104✔
56	return Ok(Arc::clone(tx));	80✔
57	}	24✔
58		24✔
59	drop(tx_cache);	24✔
60
61	let tx = Arc::new(self.inner.transaction_get(&txid)?);	24✔
62
63	self.tx_cache.lock().unwrap().insert(txid, Arc::clone(&tx));	24✔
64		24✔
65	Ok(tx)	24✔
66	}	104✔
67
68	/// Fetch block header of given `height`.
69	///
70	/// If it hits the cache it will return the cached version and avoid making the request.
71	fn fetch_header(&self, height: u32) -> Result<Header, Error> {	44✔
72	let block_header_cache = self.block_header_cache.lock().unwrap();	44✔
73
74	if let Some(header) = block_header_cache.get(&height) {	44✔
75	return Ok(*header);	31✔
76	}	13✔
77		13✔
78	drop(block_header_cache);	13✔
79		13✔
80	self.update_header(height)	13✔
81	}	44✔
82
83	/// Update a block header at given `height`. Returns the updated header.
84	fn update_header(&self, height: u32) -> Result<Header, Error> {	13✔
85	let header = self.inner.block_header(height as usize)?;	13✔
86
87	self.block_header_cache	13✔
88	.lock()	13✔
89	.unwrap()	13✔
90	.insert(height, header);	13✔
91		13✔
92	Ok(header)	13✔
93	}	13✔
94
95	/// Broadcasts a transaction to the network.
96	///
97	/// This is a re-export of [`ElectrumApi::transaction_broadcast`].
98	pub fn transaction_broadcast(&self, tx: &Transaction) -> Result<Txid, Error> {	×
99	self.inner.transaction_broadcast(tx)	×
100	}	×
101
102	/// Full scan the keychain scripts specified with the blockchain (via an Electrum client) and
103	/// returns updates for [`bdk_chain`] data structures.
104	///
105	/// - `request`: struct with data required to perform a spk-based blockchain client full scan,
106	/// see [`FullScanRequest`].
107	/// - `stop_gap`: the full scan for each keychain stops after a gap of script pubkeys with no
108	/// associated transactions.
109	/// - `batch_size`: specifies the max number of script pubkeys to request for in a single batch
110	/// request.
111	/// - `fetch_prev_txouts`: specifies whether we want previous `TxOut`s for fee calculation.
112	/// Note that this requires additional calls to the Electrum server, but
113	/// is necessary for calculating the fee on a transaction if your wallet
114	/// does not own the inputs. Methods like [`Wallet.calculate_fee`] and
115	/// [`Wallet.calculate_fee_rate`] will return a
116	/// [`CalculateFeeError::MissingTxOut`] error if those `TxOut`s are not
117	/// present in the transaction graph.
118	///
119	/// [`CalculateFeeError::MissingTxOut`]: bdk_chain::tx_graph::CalculateFeeError::MissingTxOut
120	/// [`Wallet.calculate_fee`]: https://docs.rs/bdk_wallet/latest/bdk_wallet/struct.Wallet.html#method.calculate_fee
121	/// [`Wallet.calculate_fee_rate`]: https://docs.rs/bdk_wallet/latest/bdk_wallet/struct.Wallet.html#method.calculate_fee_rate
122	pub fn full_scan<K: Ord + Clone>(	4✔
123	&self,	4✔
124	request: impl Into<FullScanRequest<K>>,	4✔
125	stop_gap: usize,	4✔
126	batch_size: usize,	4✔
127	fetch_prev_txouts: bool,	4✔
128	) -> Result<FullScanResult<K>, Error> {	4✔
129	let mut request: FullScanRequest<K> = request.into();	4✔
130
131	let tip_and_latest_blocks = match request.chain_tip() {	4✔
132	Some(chain_tip) => Some(fetch_tip_and_latest_blocks(&self.inner, chain_tip)?),	4✔
133	None => None,	×
134	};
135
136	let mut graph_update = tx_graph::Update::<ConfirmationBlockTime>::default();	4✔
137	let mut last_active_indices = BTreeMap::<K, u32>::default();	4✔
138	for keychain in request.keychains() {	4✔
139	let spks = request.iter_spks(keychain.clone());	4✔
140	if let Some(last_active_index) =	3✔
141	self.populate_with_spks(&mut graph_update, spks, stop_gap, batch_size)?	4✔
142	{	3✔
143	last_active_indices.insert(keychain, last_active_index);	3✔
144	}	3✔
145	}
146
147	// Fetch previous `TxOut`s for fee calculation if flag is enabled.
148	if fetch_prev_txouts {	4✔
149	self.fetch_prev_txout(&mut graph_update)?;	×
150	}	4✔
151
152	let chain_update = match tip_and_latest_blocks {	4✔
153	Some((chain_tip, latest_blocks)) => Some(chain_update(	4✔
154	chain_tip,	4✔
155	&latest_blocks,	4✔
156	graph_update.anchors.iter().cloned(),	4✔
157	)?),	4✔
158	_ => None,	×
159	};
160
161	Ok(FullScanResult {	4✔
162	graph_update,	4✔
163	chain_update,	4✔
164	last_active_indices,	4✔
165	})	4✔
166	}	4✔
167
168	/// Sync a set of scripts with the blockchain (via an Electrum client) for the data specified
169	/// and returns updates for [`bdk_chain`] data structures.
170	///
171	/// - `request`: struct with data required to perform a spk-based blockchain client sync,
172	/// see [`SyncRequest`]
173	/// - `batch_size`: specifies the max number of script pubkeys to request for in a single batch
174	/// request
175	/// - `fetch_prev_txouts`: specifies whether we want previous `TxOut`s for fee calculation.
176	/// Note that this requires additional calls to the Electrum server, but
177	/// is necessary for calculating the fee on a transaction if your wallet
178	/// does not own the inputs. Methods like [`Wallet.calculate_fee`] and
179	/// [`Wallet.calculate_fee_rate`] will return a
180	/// [`CalculateFeeError::MissingTxOut`] error if those `TxOut`s are not
181	/// present in the transaction graph.
182	///
183	/// If the scripts to sync are unknown, such as when restoring or importing a keychain that
184	/// may include scripts that have been used, use [`full_scan`] with the keychain.
185	///
186	/// [`full_scan`]: Self::full_scan
187	/// [`CalculateFeeError::MissingTxOut`]: bdk_chain::tx_graph::CalculateFeeError::MissingTxOut
188	/// [`Wallet.calculate_fee`]: https://docs.rs/bdk_wallet/latest/bdk_wallet/struct.Wallet.html#method.calculate_fee
189	/// [`Wallet.calculate_fee_rate`]: https://docs.rs/bdk_wallet/latest/bdk_wallet/struct.Wallet.html#method.calculate_fee_rate
190	pub fn sync<I: 'static>(	14✔
191	&self,	14✔
192	request: impl Into<SyncRequest<I>>,	14✔
193	batch_size: usize,	14✔
194	fetch_prev_txouts: bool,	14✔
195	) -> Result<SyncResult, Error> {	14✔
196	let mut request: SyncRequest<I> = request.into();	14✔
197
198	let tip_and_latest_blocks = match request.chain_tip() {	14✔
199	Some(chain_tip) => Some(fetch_tip_and_latest_blocks(&self.inner, chain_tip)?),	14✔
200	None => None,	×
201	};
202
203	let mut graph_update = tx_graph::Update::<ConfirmationBlockTime>::default();	14✔
204	self.populate_with_spks(	14✔
205	&mut graph_update,	14✔
206	request	14✔
207	.iter_spks()	14✔
208	.enumerate()	14✔
209	.map(\|(i, spk)\| (i as u32, spk)),	15✔
210	usize::MAX,	14✔
211	batch_size,	14✔
212	)?;	14✔
213	self.populate_with_txids(&mut graph_update, request.iter_txids())?;	14✔
214	self.populate_with_outpoints(&mut graph_update, request.iter_outpoints())?;	14✔
215
216	// Fetch previous `TxOut`s for fee calculation if flag is enabled.
217	if fetch_prev_txouts {	14✔
218	self.fetch_prev_txout(&mut graph_update)?;	14✔
219	}	×
220
221	let chain_update = match tip_and_latest_blocks {	14✔
222	Some((chain_tip, latest_blocks)) => Some(chain_update(	14✔
223	chain_tip,	14✔
224	&latest_blocks,	14✔
225	graph_update.anchors.iter().cloned(),	14✔
226	)?),	14✔
227	None => None,	×
228	};
229
230	Ok(SyncResult {	14✔
231	graph_update,	14✔
232	chain_update,	14✔
233	})	14✔
234	}	14✔
235
236	/// Populate the `graph_update` with transactions/anchors associated with the given `spks`.
237	///
238	/// Transactions that contains an output with requested spk, or spends form an output with
239	/// requested spk will be added to `graph_update`. Anchors of the aforementioned transactions are
240	/// also included.
241	fn populate_with_spks(	18✔
242	&self,	18✔
243	graph_update: &mut tx_graph::Update<ConfirmationBlockTime>,	18✔
244	mut spks: impl Iterator<Item = (u32, ScriptBuf)>,	18✔
245	stop_gap: usize,	18✔
246	batch_size: usize,	18✔
247	) -> Result<Option<u32>, Error> {	18✔
248	let mut unused_spk_count = 0_usize;	18✔
249	let mut last_active_index = Option::<u32>::None;	18✔
250
251	loop {	60✔
252	let spks = (0..batch_size)	60✔
253	.map_while(\|_\| spks.next())	73✔
254	.collect::<Vec<_>>();	60✔
255	if spks.is_empty() {	60✔
256	return Ok(last_active_index);	15✔
257	}	45✔
258
259	let spk_histories = self	45✔
260	.inner	45✔
261	.batch_script_get_history(spks.iter().map(\|(_, s)\| s.as_script()))?;	45✔
262
263	for ((spk_index, _spk), spk_history) in spks.into_iter().zip(spk_histories) {	45✔
264	if spk_history.is_empty() {	45✔
265	unused_spk_count = unused_spk_count.saturating_add(1);	26✔
266	if unused_spk_count >= stop_gap {	26✔
267	return Ok(last_active_index);	3✔
268	}	23✔
269	continue;	23✔
270	} else {	19✔
271	last_active_index = Some(spk_index);	19✔
272	unused_spk_count = 0;	19✔
273	}	19✔
274
275	for tx_res in spk_history {	73✔
276	graph_update.txs.push(self.fetch_tx(tx_res.tx_hash)?);	54✔
277	self.validate_merkle_for_anchor(graph_update, tx_res.tx_hash, tx_res.height)?;	54✔
278	}
279	}
280	}
281	}	18✔
282
283	/// Populate the `graph_update` with associated transactions/anchors of `outpoints`.
284	///
285	/// Transactions in which the outpoint resides, and transactions that spend from the outpoint are
286	/// included. Anchors of the aforementioned transactions are included.
287	fn populate_with_outpoints(	14✔
288	&self,	14✔
289	graph_update: &mut tx_graph::Update<ConfirmationBlockTime>,	14✔
290	outpoints: impl IntoIterator<Item = OutPoint>,	14✔
291	) -> Result<(), Error> {	14✔
292	for outpoint in outpoints {	14✔
293	let op_txid = outpoint.txid;	×
294	let op_tx = self.fetch_tx(op_txid)?;	×
295	let op_txout = match op_tx.output.get(outpoint.vout as usize) {	×
296	Some(txout) => txout,	×
297	None => continue,	×
298	};
299	debug_assert_eq!(op_tx.compute_txid(), op_txid);	×
300
301	// attempt to find the following transactions (alongside their chain positions), and
302	// add to our sparsechain `update`:
303	let mut has_residing = false; // tx in which the outpoint resides	×
304	let mut has_spending = false; // tx that spends the outpoint	×
305	for res in self.inner.script_get_history(&op_txout.script_pubkey)? {	×
306	if has_residing && has_spending {	×
307	break;	×
308	}	×
309		×
310	if !has_residing && res.tx_hash == op_txid {	×
311	has_residing = true;	×
NEW 312	graph_update.txs.push(Arc::clone(&op_tx));	×
313	self.validate_merkle_for_anchor(graph_update, res.tx_hash, res.height)?;	×
314	}	×
315
316	if !has_spending && res.tx_hash != op_txid {	×
317	let res_tx = self.fetch_tx(res.tx_hash)?;	×
318	// we exclude txs/anchors that do not spend our specified outpoint(s)
319	has_spending = res_tx	×
320	.input	×
321	.iter()	×
322	.any(\|txin\| txin.previous_output == outpoint);	×
323	if !has_spending {	×
324	continue;	×
325	}	×
NEW 326	graph_update.txs.push(Arc::clone(&res_tx));	×
327	self.validate_merkle_for_anchor(graph_update, res.tx_hash, res.height)?;	×
328	}	×
329	}
330	}
331	Ok(())	14✔
332	}	14✔
333
334	/// Populate the `graph_update` with transactions/anchors of the provided `txids`.
335	fn populate_with_txids(	14✔
336	&self,	14✔
337	graph_update: &mut tx_graph::Update<ConfirmationBlockTime>,	14✔
338	txids: impl IntoIterator<Item = Txid>,	14✔
339	) -> Result<(), Error> {	14✔
340	for txid in txids {	14✔
341	let tx = match self.fetch_tx(txid) {	×
342	Ok(tx) => tx,	×
343	Err(electrum_client::Error::Protocol(_)) => continue,	×
344	Err(other_err) => return Err(other_err),	×
345	};
346
347	let spk = tx	×
348	.output	×
349	.first()	×
350	.map(\|txo\| &txo.script_pubkey)	×
351	.expect("tx must have an output");	×
352
353	// because of restrictions of the Electrum API, we have to use the `script_get_history`
354	// call to get confirmation status of our transaction
355	if let Some(r) = self	×
356	.inner	×
357	.script_get_history(spk)?	×
358	.into_iter()	×
359	.find(\|r\| r.tx_hash == txid)	×
360	{
361	self.validate_merkle_for_anchor(graph_update, txid, r.height)?;	×
362	}	×
363
NEW 364	graph_update.txs.push(tx);	×
365	}
366	Ok(())	14✔
367	}	14✔
368
369	// Helper function which checks if a transaction is confirmed by validating the merkle proof.
370	// An anchor is inserted if the transaction is validated to be in a confirmed block.
371	fn validate_merkle_for_anchor(	54✔
372	&self,	54✔
373	graph_update: &mut tx_graph::Update<ConfirmationBlockTime>,	54✔
374	txid: Txid,	54✔
375	confirmation_height: i32,	54✔
376	) -> Result<(), Error> {	54✔
377	if let Ok(merkle_res) = self	54✔
378	.inner	54✔
379	.transaction_get_merkle(&txid, confirmation_height as usize)	54✔
380	{
381	let mut header = self.fetch_header(merkle_res.block_height as u32)?;	44✔
382	let mut is_confirmed_tx = electrum_client::utils::validate_merkle_proof(	44✔
383	&txid,	44✔
384	&header.merkle_root,	44✔
385	&merkle_res,	44✔
386	);	44✔
387		44✔
388	// Merkle validation will fail if the header in `block_header_cache` is outdated, so we	44✔
389	// want to check if there is a new header and validate against the new one.	44✔
390	if !is_confirmed_tx {	44✔
391	header = self.update_header(merkle_res.block_height as u32)?;	×
392	is_confirmed_tx = electrum_client::utils::validate_merkle_proof(	×
393	&txid,	×
394	&header.merkle_root,	×
395	&merkle_res,	×
396	);	×
397	}	44✔
398
399	if is_confirmed_tx {	44✔
400	graph_update.anchors.insert((	44✔
401	ConfirmationBlockTime {	44✔
402	confirmation_time: header.time as u64,	44✔
403	block_id: BlockId {	44✔
404	height: merkle_res.block_height as u32,	44✔
405	hash: header.block_hash(),	44✔
406	},	44✔
407	},	44✔
408	txid,	44✔
409	));	44✔
410	}	44✔
411	}	10✔
412	Ok(())	54✔
413	}	54✔
414
415	// Helper function which fetches the `TxOut`s of our relevant transactions' previous transactions,
416	// which we do not have by default. This data is needed to calculate the transaction fee.
417	fn fetch_prev_txout(	14✔
418	&self,	14✔
419	graph_update: &mut tx_graph::Update<ConfirmationBlockTime>,	14✔
420	) -> Result<(), Error> {	14✔
421	let mut no_dup = HashSet::<Txid>::new();	14✔
422	for tx in &graph_update.txs {	64✔
423	if no_dup.insert(tx.compute_txid()) {	50✔
424	for vin in &tx.input {	50✔
425	let outpoint = vin.previous_output;	50✔
426	let vout = outpoint.vout;	50✔
427	let prev_tx = self.fetch_tx(outpoint.txid)?;	50✔
428	let txout = prev_tx.output[vout as usize].clone();	50✔
429	let _ = graph_update.txouts.insert(outpoint, txout);	50✔
430	}
UNCOV 431	}	×
432	}
433	Ok(())	14✔
434	}	14✔
435	}
436
437	/// Return a [`CheckPoint`] of the latest tip, that connects with `prev_tip`. The latest blocks are
438	/// fetched to construct checkpoint updates with the proper [`BlockHash`] in case of re-org.
439	fn fetch_tip_and_latest_blocks(	18✔
440	client: &impl ElectrumApi,	18✔
441	prev_tip: CheckPoint,	18✔
442	) -> Result<(CheckPoint, BTreeMap<u32, BlockHash>), Error> {	18✔
443	let HeaderNotification { height, .. } = client.block_headers_subscribe()?;	18✔
444	let new_tip_height = height as u32;	18✔
445		18✔
446	// If electrum returns a tip height that is lower than our previous tip, then checkpoints do	18✔
447	// not need updating. We just return the previous tip and use that as the point of agreement.	18✔
448	if new_tip_height < prev_tip.height() {	18✔
449	return Ok((prev_tip, BTreeMap::new()));	×
450	}	18✔
451
452	// Atomically fetch the latest `CHAIN_SUFFIX_LENGTH` count of blocks from Electrum. We use this
453	// to construct our checkpoint update.
454	let mut new_blocks = {	18✔
455	let start_height = new_tip_height.saturating_sub(CHAIN_SUFFIX_LENGTH - 1);	18✔
456	let hashes = client	18✔
457	.block_headers(start_height as _, CHAIN_SUFFIX_LENGTH as _)?	18✔
458	.headers
459	.into_iter()	18✔
460	.map(\|h\| h.block_hash());	144✔
461	(start_height..).zip(hashes).collect::<BTreeMap<u32, _>>()	18✔
462	};
463
464	// Find the "point of agreement" (if any).
465	let agreement_cp = {	18✔
466	let mut agreement_cp = Option::<CheckPoint>::None;	18✔
467	for cp in prev_tip.iter() {	55✔
468	let cp_block = cp.block_id();	55✔
469	let hash = match new_blocks.get(&cp_block.height) {	55✔
470	Some(&hash) => hash,	52✔
471	None => {
472	assert!(	3✔
473	new_tip_height >= cp_block.height,	3✔
474	"already checked that electrum's tip cannot be smaller"	×
475	);
476	let hash = client.block_header(cp_block.height as _)?.block_hash();	3✔
477	new_blocks.insert(cp_block.height, hash);	3✔
478	hash	3✔
479	}
480	};
481	if hash == cp_block.hash {	55✔
482	agreement_cp = Some(cp);	18✔
483	break;	18✔
484	}	37✔
485	}
486	agreement_cp	18✔
487	};	18✔
488		18✔
489	let agreement_height = agreement_cp.as_ref().map(CheckPoint::height);	18✔
490		18✔
491	let new_tip = new_blocks	18✔
492	.iter()	18✔
493	// Prune `new_blocks` to only include blocks that are actually new.	18✔
494	.filter(\|(height, _)\| Some(*<&u32>::clone(height)) > agreement_height)	147✔
495	.map(\|(height, hash)\| BlockId {	57✔
496	height: *height,	57✔
497	hash: *hash,	57✔
498	})	57✔
499	.fold(agreement_cp, \|prev_cp, block\| {	57✔
500	Some(match prev_cp {	57✔
501	Some(cp) => cp.push(block).expect("must extend checkpoint"),	57✔
502	None => CheckPoint::new(block),	×
503	})
504	})	57✔
505	.expect("must have at least one checkpoint");	18✔
506		18✔
507	Ok((new_tip, new_blocks))	18✔
508	}	18✔
509
510	// Add a corresponding checkpoint per anchor height if it does not yet exist. Checkpoints should not
511	// surpass `latest_blocks`.
512	fn chain_update(	18✔
513	mut tip: CheckPoint,	18✔
514	latest_blocks: &BTreeMap<u32, BlockHash>,	18✔
515	anchors: impl Iterator<Item = (ConfirmationBlockTime, Txid)>,	18✔
516	) -> Result<CheckPoint, Error> {	18✔
517	for (anchor, _txid) in anchors {	62✔
518	let height = anchor.block_id.height;	44✔
519		44✔
520	// Checkpoint uses the `BlockHash` from `latest_blocks` so that the hash will be consistent	44✔
521	// in case of a re-org.	44✔
522	if tip.get(height).is_none() && height <= tip.height() {	44✔
523	let hash = match latest_blocks.get(&height) {	×
524	Some(&hash) => hash,	×
NEW 525	None => anchor.block_id.hash,	×
526	};
527	tip = tip.insert(BlockId { hash, height });	×
528	}	44✔
529	}
530	Ok(tip)	18✔
531	}	18✔

bitcoindevkit / bdk / 10537513186

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