Fix data race in xfr.go (#8039)

Signed-off-by: Ryan Brewster <rpb@anthropic.com>
This commit is contained in:
rpb-ant
2026-04-11 04:39:31 -04:00
committed by GitHub
parent c0e6e7cef3
commit 0ed3aae547
3 changed files with 14 additions and 5 deletions

View File

@@ -19,8 +19,12 @@ func (f File) Transfer(zone string, serial uint32) (<-chan []dns.RR, error) {
// Transfer transfers a zone with serial in the returned channel and implements IXFR fallback, by just
// sending a single SOA record.
func (z *Zone) Transfer(serial uint32) (<-chan []dns.RR, error) {
// get soa and apex
apex, err := z.ApexIfDefined()
// Snapshot apex and tree under one read lock so the goroutine walks the
// same generation the SOA came from, even if TransferIn swaps them mid-AXFR.
z.RLock()
apex, err := z.apexIfDefinedLocked()
t := z.Tree
z.RUnlock()
if err != nil {
return nil, err
}
@@ -35,7 +39,7 @@ func (z *Zone) Transfer(serial uint32) (<-chan []dns.RR, error) {
}
ch <- apex
z.Walk(func(e *tree.Elem, _ map[uint16][]dns.RR) error { ch <- e.All(); return nil })
t.Walk(func(e *tree.Elem, _ map[uint16][]dns.RR) error { ch <- e.All(); return nil })
ch <- []dns.RR{apex[0]}
close(ch)

View File

@@ -146,6 +146,11 @@ func (z *Zone) SetFile(path string) {
func (z *Zone) ApexIfDefined() ([]dns.RR, error) {
z.RLock()
defer z.RUnlock()
return z.apexIfDefinedLocked()
}
// apexIfDefinedLocked is ApexIfDefined without locking; caller must hold z's read lock.
func (z *Zone) apexIfDefinedLocked() ([]dns.RR, error) {
if z.SOA == nil {
return nil, fmt.Errorf("no SOA")
}

View File

@@ -290,7 +290,7 @@ func TestSecondaryZoneNotify(t *testing.T) {
if len(r.Answer) != 0 {
break
}
time.Sleep(1000 * time.Microsecond)
time.Sleep(100 * time.Millisecond)
}
if len(r.Answer) == 0 {
t.Fatalf("Expected answer section")
@@ -323,7 +323,7 @@ www IN A 127.0.0.1
if len(r.Answer) != 0 {
break
}
time.Sleep(1000 * time.Microsecond)
time.Sleep(100 * time.Millisecond)
}
if len(r.Answer) != 1 {
t.Fatalf("Expected one RR in answer section got %d", len(r.Answer))