forked from coredns/coredns
/
subzone.go
48 lines (40 loc) · 1.38 KB
/
subzone.go
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package kubernetes
import (
"log"
"github.com/miekg/dns"
)
// NormalizeZoneList filters the zones argument to remove
// array items that conflict with other items in zones.
// For example, providing the following zones array:
// [ "a.b.c", "b.c", "a", "e.d.f", "a.b" ]
// Returns:
// [ "a.b.c", "a", "e.d.f", "a.b" ]
// Zones filted out:
// - "b.c" because "a.b.c" and "b.c" share the common top
// level "b.c". First listed zone wins if there is a conflict.
//
// Note: This may prove to be too restrictive in practice.
// Need to find counter-example use-cases.
func NormalizeZoneList(zones []string) []string {
filteredZones := []string{}
for _, z := range zones {
zoneConflict, _ := subzoneConflict(filteredZones, z)
if zoneConflict {
log.Printf("[WARN] new zone '%v' from Corefile conflicts with existing zones: %v\n Ignoring zone '%v'\n", z, filteredZones, z)
} else {
filteredZones = append(filteredZones, z)
}
}
return filteredZones
}
// subzoneConflict returns true if name is a child or parent zone of
// any element in zones. If conflicts exist, return the conflicting zones.
func subzoneConflict(zones []string, name string) (bool, []string) {
conflicts := []string{}
for _, z := range zones {
if dns.IsSubDomain(z, name) || dns.IsSubDomain(name, z) {
conflicts = append(conflicts, z)
}
}
return (len(conflicts) != 0), conflicts
}