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Bound decoy selection to prevent it from infinite looping

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This commit is contained in:
Luke Parker 2022-06-10 00:32:56 -04:00
parent e1831ee5af
commit 1ef528bf8c
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GPG key ID: F9F1386DB1E119B6
1 changed files with 10 additions and 3 deletions
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13
coins/monero/src/wallet/decoys.rs
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@ -33,11 +33,18 @@ async fn select_n<R: RngCore + CryptoRng>(
used: &mut HashSet<u64>,
count: usize
) -> Result<Vec<(u64, [EdwardsPoint; 2])>, RpcError> {
let mut iters = 0;
let mut confirmed = Vec::with_capacity(count);
while confirmed.len() != count {
let remaining = count - confirmed.len();
let mut candidates = Vec::with_capacity(remaining);
while candidates.len() != remaining {
iters += 1;
// This is cheap and on fresh chains, thousands of rounds may be needed
if iters == 10000 {
Err(RpcError::InternalError("not enough decoy candidates".to_string()))?;
}
// Use a gamma distribution
let mut age = GAMMA.sample(rng).exp();
if age > TIP_APPLICATION {
@ -126,7 +133,7 @@ impl Decoys {
// Panic if not enough decoys are available
// TODO: Simply create a TX with less than the target amount, or at least return an error
if (high - MATURITY) < u64::try_from(inputs.len() * RING_LEN).unwrap() {
panic!("Not enough decoys available");
Err(RpcError::InternalError("not enough decoy candidates".to_string()))?;
}
// Select all decoys for this transaction, assuming we generate a sane transaction
@ -161,8 +168,8 @@ impl Decoys {
if high > 500 {
// Make sure the TX passes the sanity check that the median output is within the last 40%
// This actually checks the median is within the last third, a slightly more aggressive
// boundary, as the height used in this calculation will be slightly under the height this is
// sanity checked against
// boundary, as the height used in this calculation will be slightly under the height this
// is sanity checked against
let target_median = high * 2 / 3;
while ring[RING_LEN / 2].0 < target_median {
// If it's not, update the bottom half with new values to ensure the median only moves up