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//this is an example for nclient4 with lease/release
package nclient4
import (
"context"
"fmt"
"log"
"github.com/insomniacslk/dhcp/dhcpv4"
"github.com/insomniacslk/dhcp/dhcpv4/nclient4"
"github.com/vishvananda/netlink"
)
//applyLease adding the assigned ip to the interface specified by ifname
func applyLease(lease *nclient4.Lease, ifname string) error {
link, err := netlink.LinkByName(ifname)
if err != nil {
return err
}
prefixlen := 32
if ipmask := lease.ACK.SubnetMask(); ipmask != nil {
prefixlen, _ = ipmask.Size()
}
prefixstr := fmt.Sprintf("%v/%v", lease.ACK.YourIPAddr, prefixlen)
naddr, err := netlink.ParseAddr(prefixstr)
if err != nil {
return err
}
err = netlink.AddrReplace(link, naddr)
return err
}
func main() {
ifname := "eth1.200"
remoteid := "client-1"
var idoptlist dhcpv4.OptionCodeList
//specify option82 is part of client identification used by DHCPv4 server
idoptlist.Add(dhcpv4.OptionRelayAgentInformation)
clntOptions := []nclient4.ClientOpt{nclient4.WithClientIDOptions(idoptlist), nclient4.WithDebugLogger()}
clnt, err := nclient4.New(ifname, clntOptions...)
if err != nil {
log.Fatalf("failed to create dhcpv4 client,%v", err)
}
//adding option82/remote-id option to discovery and request
remoteidsubopt := dhcpv4.OptGeneric(dhcpv4.AgentRemoteIDSubOption, []byte(remoteid))
option82 := dhcpv4.OptRelayAgentInfo(remoteidsubopt)
_, lease, err := clnt.Request(context.Background(), dhcpv4.WithOption(option82))
if err != nil {
log.Fatal(err)
}
//print the lease
log.Printf("Got lease:\n%+v", lease)
//apply the lease
applyLease(lease, ifname)
//release the lease
log.Print("Releasing lease...")
err = clnt.Release(lease)
if err != nil {
log.Fatal(err)
}
log.Print("done")
}
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