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guardmgr: Use new ambiguity-tolerant contains in state handling 

This has subtleties; the comments try to explain them.
This commit is contained in:
Nick Mathewson 2022-10-25 11:13:16 -04:00
parent d65c351b33
commit 20016df6fa
1 changed files with 30 additions and 2 deletions
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32
crates/tor-guardmgr/src/sample.rs
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@ -200,14 +200,42 @@ impl GuardSet {
}
/// Copy non-persistent status from every guard shared with `other`.
///
/// This is used as part of our reload process when we don't own our state
/// files, and we're reloading in order to find out what the other Arti
/// instance thinks the guards are. At that point, `self` is the set of
/// guards that we just loaded from state, and `other` is our old guards,
/// which we are using only for their status information.
pub(crate) fn copy_status_from(&mut self, mut other: GuardSet) {
// XXXX TODO pt-client document ID issues.
let old_guards = std::mem::take(&mut self.guards);
self.guards = old_guards
.into_values()
.map(|guard| {
let id = guard.guard_id();
if let Some(other_guard) = other.guards.remove_by_all_ids(id) {
// We insist on a superset of identities here, which carries
// some risk of misidentification if:
// * We don't own our state
// * We have discovered an additional ID for this guard.
// * The state-owning Arti instance has not discovered that
// ID, AND has not discovered any conflicting ID.
// * That ID is not in fact correct.
//
// This shouldn't be too likely in reality, however, and the
// impact is limited to us applying our assumptions about
// whether a guard is up or down to an incorrect guard.
//
// TODO relay: A relay should never be able to reach this code,
// since it should insist on knowing its state.
let other_id = match other.contains(id) {
Ok(true) => Some(id),
Err(less_specific) => Some(less_specific),
Ok(false) => None,
};
if let Some(other_guard) = other_id
.cloned()
.and_then(|oid| other.guards.remove_by_all_ids(&oid))
{
guard.copy_status_from(other_guard)
} else {
guard