From: Matt Corallo <649246+TheBlueMatt@users.noreply.github.com> Date: Mon, 28 Aug 2023 21:20:51 +0000 (+0000) Subject: Merge pull request #55 from arik-so/2023/08/multiplication-overflow-fix X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=commitdiff_plain;h=858c7f23cee5fd36b5fa77232412d0cc106b1f76;hp=3fccdff87744f2fccd5280e24a49172b6a877a21;p=rapid-gossip-sync-server Merge pull request #55 from arik-so/2023/08/multiplication-overflow-fix Fix multiplication overflow bug --- diff --git a/src/snapshot.rs b/src/snapshot.rs index a27eafd..65f6fad 100644 --- a/src/snapshot.rs +++ b/src/snapshot.rs @@ -115,11 +115,27 @@ impl Snapshotter where L::Target: Logger { // special-case 0 to always refer to a full/initial sync u64::MAX } else { + /* + We have snapshots for 6-day- and 7-day-intervals, but the next interval is + 14 days. So if somebody requests an update with a timestamp that is 10 days old, + there is no longer a snapshot for that specific interval. + + The correct snapshot will be the next highest interval, i. e. for 14 days. + + The `snapshot_sync_day_factors` array is sorted ascendingly, so find() will + return on the first iteration that is at least equal to the requested interval. + + Note, however, that the last value in the array is u64::max, which means that + multiplying it with DAY_SECONDS will overflow. To avoid that, we use + saturating_mul. + */ + // find min(x) in snapshot_sync_day_factors where x >= i snapshot_sync_day_factors.iter().find(|x| { - *x * DAY_SECONDS >= i * config::SNAPSHOT_CALCULATION_INTERVAL as u64 + DAY_SECONDS.saturating_mul(**x) >= i * config::SNAPSHOT_CALCULATION_INTERVAL as u64 }).unwrap().clone() }; + log_info!(self.logger, "i: {}, referenced day range: {}", i, referenced_day_range); let snapshot_filename = snapshot_filenames_by_day_range.get(&referenced_day_range).unwrap(); let relative_snapshot_path = format!("{}/{}", relative_symlink_to_snapshot_path, snapshot_filename);