128 lines
2.7 KiB
Go
128 lines
2.7 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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"os"
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"strings"
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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/v2/maybe"
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"golang.org/x/exp/slices"
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)
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const (
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// dataFilename contains saved leases.
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dataFilename = "leases.json"
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// dataVersion is the current version of the stored DHCP leases structure.
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dataVersion = 1
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)
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// dataLeases is the structure of the stored DHCP leases.
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type dataLeases struct {
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// Version is the current version of the structure.
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Version int `json:"version"`
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// Leases is the list containing stored DHCP leases.
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Leases []*Lease `json:"leases"`
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}
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// dbLoad loads stored leases.
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func (s *server) dbLoad() (err error) {
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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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dl := &dataLeases{}
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err = json.Unmarshal(data, dl)
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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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leases := dl.Leases
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leases4 := []*Lease{}
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leases6 := []*Lease{}
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for _, l := range leases {
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if l.IP.Is4() {
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leases4 = append(leases4, l)
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} else {
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leases6 = append(leases6, l)
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}
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}
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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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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), len(leases))
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return nil
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}
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// dbStore stores DHCP leases.
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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 := []*Lease{}
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leases4 := s.srv4.getLeasesRef()
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leases = append(leases, leases4...)
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if s.srv6 != nil {
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leases6 := s.srv6.getLeasesRef()
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leases = append(leases, leases6...)
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}
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return writeDB(s.conf.dbFilePath, leases)
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}
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// writeDB writes leases to file at path.
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func writeDB(path string, leases []*Lease) (err error) {
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defer func() { err = errors.Annotate(err, "writing db: %w") }()
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slices.SortFunc(leases, func(a, b *Lease) (res int) {
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return strings.Compare(a.Hostname, b.Hostname)
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})
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dl := &dataLeases{
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Version: dataVersion,
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Leases: leases,
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}
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buf, err := json.Marshal(dl)
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if err != nil {
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// Don't wrap the error since it's informative enough as is.
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return err
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}
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err = maybe.WriteFile(path, buf, 0o644)
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if err != nil {
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// Don't wrap the error since it's informative enough as is.
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return err
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}
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log.Info("dhcp: stored %d leases in %q", len(leases), path)
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return nil
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}
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