AdGuardHome/dhcpd/db.go

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// On-disk database for lease table
package dhcpd
import (
"encoding/json"
"io/ioutil"
"net"
"os"
"time"
"github.com/AdguardTeam/golibs/file"
"github.com/AdguardTeam/golibs/log"
"github.com/krolaw/dhcp4"
)
const dbFilename = "leases.db"
type leaseJSON struct {
HWAddr []byte `json:"mac"`
IP []byte `json:"ip"`
Hostname string `json:"host"`
Expiry int64 `json:"exp"`
}
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// Safe version of dhcp4.IPInRange()
func ipInRange(start, stop, ip net.IP) bool {
if len(start) != len(stop) ||
len(start) != len(ip) {
return false
}
return dhcp4.IPInRange(start, stop, ip)
}
// Load lease table from DB
func (s *Server) dbLoad() {
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s.leases = nil
s.IPpool = make(map[[4]byte]net.HardwareAddr)
data, err := ioutil.ReadFile(s.conf.DBFilePath)
if err != nil {
if !os.IsNotExist(err) {
log.Error("DHCP: can't read file %s: %v", s.conf.DBFilePath, err)
}
return
}
obj := []leaseJSON{}
err = json.Unmarshal(data, &obj)
if err != nil {
log.Error("DHCP: invalid DB: %v", err)
return
}
numLeases := len(obj)
for i := range obj {
if obj[i].Expiry != leaseExpireStatic &&
!ipInRange(s.leaseStart, s.leaseStop, obj[i].IP) {
log.Tracef("Skipping a lease with IP %s: not within current IP range", obj[i].IP)
continue
}
lease := Lease{
HWAddr: obj[i].HWAddr,
IP: obj[i].IP,
Hostname: obj[i].Hostname,
Expiry: time.Unix(obj[i].Expiry, 0),
}
s.leases = append(s.leases, &lease)
s.reserveIP(lease.IP, lease.HWAddr)
}
log.Info("DHCP: loaded %d leases from DB", numLeases)
}
// Store lease table in DB
func (s *Server) dbStore() {
var leases []leaseJSON
for i := range s.leases {
if s.leases[i].Expiry.Unix() == 0 {
continue
}
lease := leaseJSON{
HWAddr: s.leases[i].HWAddr,
IP: s.leases[i].IP,
Hostname: s.leases[i].Hostname,
Expiry: s.leases[i].Expiry.Unix(),
}
leases = append(leases, lease)
}
data, err := json.Marshal(leases)
if err != nil {
log.Error("json.Marshal: %v", err)
return
}
err = file.SafeWrite(s.conf.DBFilePath, data)
if err != nil {
log.Error("DHCP: can't store lease table on disk: %v filename: %s",
err, s.conf.DBFilePath)
return
}
log.Info("DHCP: stored %d leases in DB", len(leases))
}