AdGuardHome/internal/dhcpd/db.go

128 lines
2.7 KiB
Go

// On-disk database for lease table
package dhcpd
import (
"encoding/json"
"fmt"
"os"
"strings"
"github.com/AdguardTeam/golibs/errors"
"github.com/AdguardTeam/golibs/log"
"github.com/google/renameio/v2/maybe"
"golang.org/x/exp/slices"
)
const (
// dataFilename contains saved leases.
dataFilename = "leases.json"
// dataVersion is the current version of the stored DHCP leases structure.
dataVersion = 1
)
// dataLeases is the structure of the stored DHCP leases.
type dataLeases struct {
// Version is the current version of the structure.
Version int `json:"version"`
// Leases is the list containing stored DHCP leases.
Leases []*Lease `json:"leases"`
}
// dbLoad loads stored leases.
func (s *server) dbLoad() (err error) {
data, err := os.ReadFile(s.conf.dbFilePath)
if err != nil {
if !errors.Is(err, os.ErrNotExist) {
return fmt.Errorf("reading db: %w", err)
}
return nil
}
dl := &dataLeases{}
err = json.Unmarshal(data, dl)
if err != nil {
return fmt.Errorf("decoding db: %w", err)
}
leases := dl.Leases
leases4 := []*Lease{}
leases6 := []*Lease{}
for _, l := range leases {
if l.IP.Is4() {
leases4 = append(leases4, l)
} else {
leases6 = append(leases6, l)
}
}
err = s.srv4.ResetLeases(leases4)
if err != nil {
return fmt.Errorf("resetting dhcpv4 leases: %w", err)
}
if s.srv6 != nil {
err = s.srv6.ResetLeases(leases6)
if err != nil {
return fmt.Errorf("resetting dhcpv6 leases: %w", err)
}
}
log.Info("dhcp: loaded leases v4:%d v6:%d total-read:%d from DB",
len(leases4), len(leases6), len(leases))
return nil
}
// dbStore stores DHCP leases.
func (s *server) dbStore() (err error) {
// Use an empty slice here as opposed to nil so that it doesn't write
// "null" into the database file if leases are empty.
leases := []*Lease{}
leases4 := s.srv4.getLeasesRef()
leases = append(leases, leases4...)
if s.srv6 != nil {
leases6 := s.srv6.getLeasesRef()
leases = append(leases, leases6...)
}
return writeDB(s.conf.dbFilePath, leases)
}
// writeDB writes leases to file at path.
func writeDB(path string, leases []*Lease) (err error) {
defer func() { err = errors.Annotate(err, "writing db: %w") }()
slices.SortFunc(leases, func(a, b *Lease) (res int) {
return strings.Compare(a.Hostname, b.Hostname)
})
dl := &dataLeases{
Version: dataVersion,
Leases: leases,
}
buf, err := json.Marshal(dl)
if err != nil {
// Don't wrap the error since it's informative enough as is.
return err
}
err = maybe.WriteFile(path, buf, 0o644)
if err != nil {
// Don't wrap the error since it's informative enough as is.
return err
}
log.Info("dhcp: stored %d leases in %q", len(leases), path)
return nil
}