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package main
import (
"github.com/d2g/dhcp4"
"github.com/d2g/dhcp4client"
)
const (
MaxDHCPLen = 576
)
//Send the Discovery Packet to the Broadcast Channel
func DhcpSendDiscoverPacket(c *dhcp4client.Client, options dhcp4.Options) (dhcp4.Packet, error) {
discoveryPacket := c.DiscoverPacket()
for opt, data := range options {
discoveryPacket.AddOption(opt, data)
}
discoveryPacket.PadToMinSize()
return discoveryPacket, c.SendPacket(discoveryPacket)
}
//Send Request Based On the offer Received.
func DhcpSendRequest(c *dhcp4client.Client, options dhcp4.Options, offerPacket *dhcp4.Packet) (dhcp4.Packet, error) {
requestPacket := c.RequestPacket(offerPacket)
for opt, data := range options {
requestPacket.AddOption(opt, data)
}
requestPacket.PadToMinSize()
return requestPacket, c.SendPacket(requestPacket)
}
//Send Decline to the received acknowledgement.
func DhcpSendDecline(c *dhcp4client.Client, acknowledgementPacket *dhcp4.Packet, options dhcp4.Options) (dhcp4.Packet, error) {
declinePacket := c.DeclinePacket(acknowledgementPacket)
for opt, data := range options {
declinePacket.AddOption(opt, data)
}
declinePacket.PadToMinSize()
return declinePacket, c.SendPacket(declinePacket)
}
//Lets do a Full DHCP Request.
func DhcpRequest(c *dhcp4client.Client, options dhcp4.Options) (bool, dhcp4.Packet, error) {
discoveryPacket, err := DhcpSendDiscoverPacket(c, options)
if err != nil {
return false, discoveryPacket, err
}
offerPacket, err := c.GetOffer(&discoveryPacket)
if err != nil {
return false, offerPacket, err
}
requestPacket, err := DhcpSendRequest(c, options, &offerPacket)
if err != nil {
return false, requestPacket, err
}
acknowledgement, err := c.GetAcknowledgement(&requestPacket)
if err != nil {
return false, acknowledgement, err
}
acknowledgementOptions := acknowledgement.ParseOptions()
if dhcp4.MessageType(acknowledgementOptions[dhcp4.OptionDHCPMessageType][0]) != dhcp4.ACK {
return false, acknowledgement, nil
}
return true, acknowledgement, nil
}
//Renew a lease backed on the Acknowledgement Packet.
//Returns Successful, The AcknoledgementPacket, Any Errors
func DhcpRenew(c *dhcp4client.Client, acknowledgement dhcp4.Packet, options dhcp4.Options) (bool, dhcp4.Packet, error) {
renewRequest := c.RenewalRequestPacket(&acknowledgement)
for opt, data := range options {
renewRequest.AddOption(opt, data)
}
renewRequest.PadToMinSize()
err := c.SendPacket(renewRequest)
if err != nil {
return false, renewRequest, err
}
newAcknowledgement, err := c.GetAcknowledgement(&renewRequest)
if err != nil {
return false, newAcknowledgement, err
}
newAcknowledgementOptions := newAcknowledgement.ParseOptions()
if dhcp4.MessageType(newAcknowledgementOptions[dhcp4.OptionDHCPMessageType][0]) != dhcp4.ACK {
return false, newAcknowledgement, nil
}
return true, newAcknowledgement, nil
}
//Release a lease backed on the Acknowledgement Packet.
//Returns Any Errors
func DhcpRelease(c *dhcp4client.Client, acknowledgement dhcp4.Packet, options dhcp4.Options) error {
release := c.ReleasePacket(&acknowledgement)
for opt, data := range options {
release.AddOption(opt, data)
}
release.PadToMinSize()
return c.SendPacket(release)
}
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