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//This is lease support for nclient4
package nclient4
import (
"fmt"
"net"
"time"
"github.com/insomniacslk/dhcp/dhcpv4"
)
//Lease contains a DHCPv4 lease after DORA.
//note: Lease doesn't include binding interface name
type Lease struct {
Offer *dhcpv4.DHCPv4
ACK *dhcpv4.DHCPv4
CreationTime time.Time
IDOptions dhcpv4.Options //DHCPv4 options to identify the client like client-id, option82/remote-id
}
// WithClientIDOptions configures a list of DHCPv4 option code that DHCP server
// uses to identify client, beside the MAC address.
func WithClientIDOptions(cidl dhcpv4.OptionCodeList) ClientOpt {
return func(c *Client) (err error) {
c.clientIDOptions = cidl
return
}
}
//Release send DHCPv4 release messsage to server, based on specified lease.
//release is sent as unicast per RFC2131, section 4.4.4.
//Note: some DHCP server requries of using assigned IP address as source IP,
//use nclient4.WithUnicast to create client for such case.
func (c *Client) Release(lease *Lease) error {
if lease == nil {
return fmt.Errorf("lease is nil")
}
req, err := dhcpv4.New()
if err != nil {
return err
}
//This is to make sure use same client identification options used during
//DORA, so that DHCP server could identify the required lease
req.Options = lease.IDOptions
req.UpdateOption(dhcpv4.OptMessageType(dhcpv4.MessageTypeRelease))
req.ClientHWAddr = lease.ACK.ClientHWAddr
req.ClientIPAddr = lease.ACK.YourIPAddr
req.UpdateOption(dhcpv4.OptGeneric(dhcpv4.OptionServerIdentifier, lease.ACK.Options.Get(dhcpv4.OptionServerIdentifier)))
req.SetUnicast()
if err != nil {
return err
}
_, err = c.conn.WriteTo(req.ToBytes(), &net.UDPAddr{IP: lease.ACK.Options.Get(dhcpv4.OptionServerIdentifier), Port: 67})
if err == nil {
c.logger.PrintMessage("sent message:", req)
}
return err
}
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