117 lines
2.8 KiB
Go
117 lines
2.8 KiB
Go
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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"net/netip"
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"os"
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"path/filepath"
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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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)
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const (
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// leaseExpireStatic is used to define the Expiry field for static
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// leases.
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//
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// Deprecated: Remove it when migration of DHCP leases will be not needed.
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leaseExpireStatic = 1
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// dbFilename contains saved leases.
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//
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// Deprecated: Use dataFilename.
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dbFilename = "leases.db"
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)
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// leaseJSON is the structure of stored lease in a legacy database.
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//
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// Deprecated: Use [dbLease].
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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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// readOldDB reads the old database from the given path.
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func readOldDB(path string) (leases []*leaseJSON, err error) {
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// #nosec G304 -- Trust this path, since it's taken from the old file name
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// relative to the working directory and should generally be considered
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// safe.
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file, err := os.Open(path)
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if errors.Is(err, os.ErrNotExist) {
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// Nothing to migrate.
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return nil, nil
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} else if err != nil {
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// Don't wrap the error since it's informative enough as is.
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return nil, err
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}
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defer func() { err = errors.WithDeferred(err, file.Close()) }()
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leases = []*leaseJSON{}
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err = json.NewDecoder(file).Decode(&leases)
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if err != nil {
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return nil, fmt.Errorf("decoding old db: %w", err)
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}
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return leases, nil
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}
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// migrateDB migrates stored leases if necessary.
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func migrateDB(conf *ServerConfig) (err error) {
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defer func() { err = errors.Annotate(err, "migrating db: %w") }()
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oldLeasesPath := filepath.Join(conf.WorkDir, dbFilename)
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dataDirPath := filepath.Join(conf.DataDir, dataFilename)
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oldLeases, err := readOldDB(oldLeasesPath)
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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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} else if oldLeases == nil {
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// Nothing to migrate.
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return nil
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}
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leases := make([]*dbLease, 0, len(oldLeases))
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for _, l := range oldLeases {
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l.IP = normalizeIP(l.IP)
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ip, ok := netip.AddrFromSlice(l.IP)
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if !ok {
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log.Info("dhcp: invalid IP: %s", l.IP)
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continue
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}
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leases = append(leases, &dbLease{
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Expiry: time.Unix(l.Expiry, 0).Format(time.RFC3339),
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Hostname: l.Hostname,
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HWAddr: net.HardwareAddr(l.HWAddr).String(),
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IP: ip,
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IsStatic: l.Expiry == leaseExpireStatic,
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})
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}
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err = writeDB(dataDirPath, leases)
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if err != nil {
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// Don't wrap the error since an annotation deferred already.
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return err
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}
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return os.Remove(oldLeasesPath)
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}
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// normalizeIP converts the given IP address to IPv4 if it's IPv4-mapped IPv6,
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// or leaves it as is otherwise.
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func normalizeIP(ip net.IP) (normalized net.IP) {
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normalized = ip.To4()
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if normalized != nil {
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return normalized
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}
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return ip
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}
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