189 lines
3.8 KiB
Go
189 lines
3.8 KiB
Go
// On-disk database for lease table
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package dhcpd
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import (
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"encoding/json"
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"fmt"
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"net"
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"os"
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"time"
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"github.com/AdguardTeam/golibs/errors"
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"github.com/AdguardTeam/golibs/log"
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"github.com/google/renameio/maybe"
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)
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const dbFilename = "leases.db"
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type leaseJSON struct {
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HWAddr []byte `json:"mac"`
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IP []byte `json:"ip"`
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Hostname string `json:"host"`
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Expiry int64 `json:"exp"`
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}
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func normalizeIP(ip net.IP) net.IP {
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ip4 := ip.To4()
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if ip4 != nil {
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return ip4
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}
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return ip
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}
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// Load lease table from DB
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func (s *server) dbLoad() (err error) {
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dynLeases := []*Lease{}
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staticLeases := []*Lease{}
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v6StaticLeases := []*Lease{}
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v6DynLeases := []*Lease{}
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data, err := os.ReadFile(s.conf.DBFilePath)
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if err != nil {
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if !errors.Is(err, os.ErrNotExist) {
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return fmt.Errorf("reading db: %w", err)
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}
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return nil
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}
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obj := []leaseJSON{}
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err = json.Unmarshal(data, &obj)
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if err != nil {
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return fmt.Errorf("decoding db: %w", err)
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}
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numLeases := len(obj)
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for i := range obj {
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obj[i].IP = normalizeIP(obj[i].IP)
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if !(len(obj[i].IP) == 4 || len(obj[i].IP) == 16) {
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log.Info("dhcp: invalid IP: %s", obj[i].IP)
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continue
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}
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lease := Lease{
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HWAddr: obj[i].HWAddr,
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IP: obj[i].IP,
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Hostname: obj[i].Hostname,
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Expiry: time.Unix(obj[i].Expiry, 0),
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}
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if len(obj[i].IP) == 16 {
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if obj[i].Expiry == leaseExpireStatic {
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v6StaticLeases = append(v6StaticLeases, &lease)
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} else {
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v6DynLeases = append(v6DynLeases, &lease)
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}
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} else {
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if obj[i].Expiry == leaseExpireStatic {
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staticLeases = append(staticLeases, &lease)
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} else {
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dynLeases = append(dynLeases, &lease)
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}
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}
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}
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leases4 := normalizeLeases(staticLeases, dynLeases)
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err = s.srv4.ResetLeases(leases4)
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if err != nil {
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return fmt.Errorf("resetting dhcpv4 leases: %w", err)
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}
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leases6 := normalizeLeases(v6StaticLeases, v6DynLeases)
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if s.srv6 != nil {
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err = s.srv6.ResetLeases(leases6)
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if err != nil {
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return fmt.Errorf("resetting dhcpv6 leases: %w", err)
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}
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}
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log.Info("dhcp: loaded leases v4:%d v6:%d total-read:%d from DB",
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len(leases4), len(leases6), numLeases)
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return nil
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}
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// Skip duplicate leases
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// Static leases have a priority over dynamic leases
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func normalizeLeases(staticLeases, dynLeases []*Lease) []*Lease {
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leases := []*Lease{}
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index := map[string]int{}
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for i, lease := range staticLeases {
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_, ok := index[lease.HWAddr.String()]
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if ok {
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continue // skip the lease with the same HW address
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}
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index[lease.HWAddr.String()] = i
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leases = append(leases, lease)
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}
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for i, lease := range dynLeases {
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_, ok := index[lease.HWAddr.String()]
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if ok {
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continue // skip the lease with the same HW address
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}
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index[lease.HWAddr.String()] = i
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leases = append(leases, lease)
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}
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return leases
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}
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// Store lease table in DB
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func (s *server) dbStore() (err error) {
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// Use an empty slice here as opposed to nil so that it doesn't write
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// "null" into the database file if leases are empty.
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leases := []leaseJSON{}
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leases4 := s.srv4.getLeasesRef()
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for _, l := range leases4 {
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if l.Expiry.Unix() == 0 {
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continue
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}
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lease := leaseJSON{
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HWAddr: l.HWAddr,
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IP: l.IP,
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Hostname: l.Hostname,
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Expiry: l.Expiry.Unix(),
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}
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leases = append(leases, lease)
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}
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if s.srv6 != nil {
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leases6 := s.srv6.getLeasesRef()
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for _, l := range leases6 {
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if l.Expiry.Unix() == 0 {
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continue
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}
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lease := leaseJSON{
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HWAddr: l.HWAddr,
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IP: l.IP,
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Hostname: l.Hostname,
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Expiry: l.Expiry.Unix(),
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}
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leases = append(leases, lease)
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}
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}
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var data []byte
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data, err = json.Marshal(leases)
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if err != nil {
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return fmt.Errorf("encoding db: %w", err)
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}
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err = maybe.WriteFile(s.conf.DBFilePath, data, 0o644)
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if err != nil {
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return fmt.Errorf("writing db: %w", err)
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}
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log.Info("dhcp: stored %d leases in db", len(leases))
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return nil
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}
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