func zonesReadDir(dirName string, zones Zones) error {
dir, err := ioutil.ReadDir(dirName)
if err != nil {
log.Println("Could not read", dirName, ":", err)
return err
}
seenZones := map[string]bool{}
var parseErr error
for _, file := range dir {
fileName := file.Name()
if !strings.HasSuffix(strings.ToLower(fileName), ".json") {
continue
}
zoneName := zoneNameFromFile(fileName)
seenZones[zoneName] = true
if zone, ok := zones[zoneName]; !ok || file.ModTime().After(zone.LastRead) {
if ok {
logPrintf("Reloading %s\n", fileName)
} else {
logPrintf("Reading new file %s\n", fileName)
}
//log.Println("FILE:", i, file, zoneName)
config, err := readZoneFile(zoneName, path.Join(dirName, fileName))
if config == nil || err != nil {
parseErr = fmt.Errorf("Error reading zone '%s': %s", zoneName, err)
log.Println(parseErr.Error())
continue
}
config.LastRead = file.ModTime()
addHandler(zones, zoneName, config)
}
}
for zoneName, zone := range zones {
if zoneName == "pgeodns" {
continue
}
if ok, _ := seenZones[zoneName]; ok {
continue
}
log.Println("Removing zone", zone.Origin)
zone.Close()
dns.HandleRemove(zoneName)
delete(zones, zoneName)
}
return parseErr
}
func zonesReadDir(dirName string, zones Zones) error {
dir, err := ioutil.ReadDir(dirName)
if err != nil {
log.Println("Could not read", dirName, ":", err)
return err
}
seenZones := map[string]bool{}
var parseErr error
for _, file := range dir {
fileName := file.Name()
if !strings.HasSuffix(strings.ToLower(fileName), ".json") ||
strings.HasPrefix(path.Base(fileName), ".") ||
file.IsDir() {
continue
}
zoneName := zoneNameFromFile(fileName)
seenZones[zoneName] = true
if _, ok := lastRead[zoneName]; !ok || file.ModTime().After(lastRead[zoneName].time) {
modTime := file.ModTime()
if ok {
logPrintf("Reloading %s\n", fileName)
lastRead[zoneName].time = modTime
} else {
logPrintf("Reading new file %s\n", fileName)
lastRead[zoneName] = &ZoneReadRecord{time: modTime}
}
filename := path.Join(dirName, fileName)
// Check the sha256 of the file has not changed. It's worth an explanation of
// why there isn't a TOCTOU race here. Conceivably after checking whether the
// SHA has changed, the contents then change again before we actually load
// the JSON. This can occur in two situations:
//
// 1. The SHA has not changed when we read the file for the SHA, but then
// changes before we process the JSON
//
// 2. The SHA has changed when we read the file for the SHA, but then changes
// again before we process the JSON
//
// In circumstance (1) we won't reread the file the first time, but the subsequent
// change should alter the mtime again, causing us to reread it. This reflects
// the fact there were actually two changes.
//
// In circumstance (2) we have already reread the file once, and then when the
// contents are changed the mtime changes again
//
// Provided files are replaced atomically, this should be OK. If files are not
// replaced atomically we have other problems (e.g. partial reads).
sha256 := sha256File(filename)
if lastRead[zoneName].hash == sha256 {
logPrintf("Skipping new file %s as hash is unchanged\n", filename)
continue
}
config, err := readZoneFile(zoneName, filename)
if config == nil || err != nil {
parseErr = fmt.Errorf("Error reading zone '%s': %s", zoneName, err)
log.Println(parseErr.Error())
continue
}
(lastRead[zoneName]).hash = sha256
addHandler(zones, zoneName, config)
}
}
for zoneName, zone := range zones {
if zoneName == "pgeodns" {
continue
}
if ok, _ := seenZones[zoneName]; ok {
continue
}
log.Println("Removing zone", zone.Origin)
delete(lastRead, zoneName)
zone.Close()
dns.HandleRemove(zoneName)
delete(zones, zoneName)
}
return parseErr
}