You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: v4_unix.go
    path of file: ./repos/AdGuardHome/internal/dhcpd
    
    the code of the file until where you have to start completion: //go:build darwin || freebsd || linux || openbsd

package dhcpd

import (
	"bytes"
	"fmt"
	"net"
	"net/netip"
	"slices"
	"strings"
	"sync"
	"time"

	"github.com/AdguardTeam/AdGuardHome/internal/aghnet"
	"github.com/AdguardTeam/AdGuardHome/internal/dhcpsvc"
	"github.com/AdguardTeam/golibs/errors"
	"github.com/AdguardTeam/golibs/log"
	"github.com/AdguardTeam/golibs/netutil"
	"github.com/AdguardTeam/golibs/timeutil"
	"github.com/go-ping/ping"
	"github.com/insomniacslk/dhcp/dhcpv4"
	"github.com/insomniacslk/dhcp/dhcpv
    
func (s *v4Server) handle(req, resp *dhcpv4.DHCPv4) (rCode int) {
	var err error

	// Include server's identifier option since any reply should contain it.
	//
	// See https://datatracker.ietf.org/doc/html/rfc2131#page-29.
	resp.UpdateOption(dhcpv4.OptServerIdentifier(s.conf.dnsIPAddrs[0].AsSlice()))

	handler := messageHandlers[req.MessageType()]
	if handler == nil {
		s.updateOptions(req, resp)

		return 1
	}

	rCode, l, err := handler(s, req, resp)
	if err != nil {
		log.Error("dhcpv4: %s", err)

		return 0
	}

	if rCode != 1 {
		return rCode
	}

	if l != nil {
		resp.YourIPAddr = l.IP.AsSlice()
	}

	s.updateOptions(req, resp)

	return 1
}