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refactor: extract the code that does cache flush #490

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Merged
keepsimple1 merged 3 commits into from
Aug 10, 2026
Merged

refactor: extract the code that does cache flush #490

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5b37d2f
refactor: extract the code that does cache flush
keepsimple1 Aug 10, 2026
da756cf
fix clippy
keepsimple1 Aug 10, 2026
6015cc3
renaming only
keepsimple1 Aug 10, 2026
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90 changes: 50 additions & 40 deletions src/dns_cache.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -276,46 +276,7 @@ impl DnsCache {
};

if incoming.get_cache_flush() {
let now = current_time_millis();
let class = incoming.get_class();
let rtype = incoming.get_type();

record_vec.iter_mut().for_each(|r| {
// When cache flush is asked, we set expire date to 1 second in the future if:
// - The record has the same rclass
// - The record was created more than 1 second ago.
// - The record expire is more than 1 second away.
// Ref: RFC 6762 Section 10.2
//
// Note: when the updated record actually expires, it will trigger events properly.
let mut should_flush = false;

if class == r.record.get_class()
&& rtype == r.record.get_type()
&& now > r.record.get_created() + 1000
&& r.record.get_expire() > now + 1000
{
should_flush = true;

// additional checks for address records.
if rtype == RRType::A || rtype == RRType::AAAA {
if let Some(addr) = r.record.any().downcast_ref::<DnsAddress>() {
if let Some(addr_b) = incoming.any().downcast_ref::<DnsAddress>() {
should_flush = addr.interface_id.index == addr_b.interface_id.index;
}
}
}
}

if should_flush {
trace!("FLUSH one record: {:?}", &r.record);
let new_expire = now + 1000;
r.record.set_expire(new_expire);

// Add a timer so the run loop will handle this expire.
timers.push(new_expire);
}
});
apply_cache_flush(&incoming, record_vec, timers);
}

// update TTL for existing record or create a new record.
Expand Down Expand Up @@ -856,6 +817,55 @@ impl DnsCache {
}
}

/// When a record has the cache flush bit set, we need to update the expire time of
/// existing records of the same type and class per RFC 6762 Section 10.2.
fn apply_cache_flush(
incoming: &DnsRecordBox,
existing_records: &mut [DnsRecordIntf],
timers: &mut Vec<u64>,
) {
let now = current_time_millis();
let class = incoming.get_class();
let rtype = incoming.get_type();

existing_records.iter_mut().for_each(|r| {
// When cache flush is asked, we set expire date to 1 second in the future if:
// - The record has the same rclass
// - The record was created more than 1 second ago.
// - The record expire is more than 1 second away.
// Ref: RFC 6762 Section 10.2
//
// Note: when the updated record actually expires, it will trigger events properly.
let mut should_flush = false;

if class == r.record.get_class()
&& rtype == r.record.get_type()
&& now > r.record.get_created() + 1000
&& r.record.get_expire() > now + 1000
{
should_flush = true;

// additional checks for address records.
if rtype == RRType::A || rtype == RRType::AAAA {
if let Some(addr) = r.record.any().downcast_ref::<DnsAddress>() {
if let Some(addr_b) = incoming.any().downcast_ref::<DnsAddress>() {
should_flush = addr.interface_id.index == addr_b.interface_id.index;
}
}
}
}

if should_flush {
trace!("FLUSH one record: {:?}", &r.record);
let new_expire = now + 1000;
r.record.set_expire(new_expire);

// Add a timer so the run loop will handle this expire.
timers.push(new_expire);
}
});
}

#[cfg(test)]
mod tests {
use super::*;
Expand Down