kdhcp/server/lease_state.go

package server

import (
	"encoding/json"
	"os"

	log "git.wntrmute.dev/kyle/goutils/log"
	"git.wntrmute.dev/kyle/kdhcp/iptools"
	"git.wntrmute.dev/kyle/kdhcp/leases"
)

type LeaseState struct {
	Pools  map[string]*iptools.Pool `json:"pools"`
	Static map[string]*leases.Info  `json:"static"`
}

func (srv *Server) SaveLeases() error {
	state := &LeaseState{
		Pools:  srv.Pools,
		Static: srv.Static,
	}

	out, err := json.MarshalIndent(state, "", "    ")
	if err != nil {
		return err
	}

	err = os.WriteFile(srv.Config.LeaseFile, out, 0644)
	if err != nil {
		return err
	}

	log.Infof("wrote lease state to file %s", srv.Config.LeaseFile)
	return nil
}

func (srv *Server) LoadLeases() error {
	state := &LeaseState{}

	stateBytes, err := os.ReadFile(srv.Config.LeaseFile)
	if err != nil {
		if os.IsNotExist(err) {
			log.Infof("not restoring leases from %s: file doesn't exist", srv.Config.LeaseFile)
			return nil
		}
		return err
	}

	err = json.Unmarshal(stateBytes, state)
	if err != nil {
		switch err := err.(type) {
		case *json.UnmarshalTypeError:
			log.Infof("type error: %q: [ \"bad type: got %s; want %s\" ]", err.Field, err.Value, err.Type.String())
			return err
		case *json.InvalidUnmarshalError:
			log.Infof("invalid unmarshal error: %s", err)
		}
		return err
	}

	log.Infoln("restored lease states")

	srv.Pools = state.Pools
	srv.Static = state.Static
	return nil
}