// ReplyPacket creates a reply packet that a Server would send to a client.
// It uses the req Packet param to copy across common/necessary fields to
// associate the reply with the request.
func informReplyPacket(req dhcp4.Packet, mt dhcp4.MessageType, serverID net.IP, options []dhcp4.Option) dhcp4.Packet {
p := dhcp4.NewPacket(dhcp4.BootReply)
p.SetXId(req.XId())
p.SetHType(req.HType())
p[2] = req.HLen() // dhcp4 library does not provide a setter
p.SetFlags(req.Flags())
p.SetCIAddr(req.CIAddr())
p.SetCHAddr(req.CHAddr())
p.AddOption(dhcp4.OptionDHCPMessageType, []byte{byte(mt)})
p.AddOption(dhcp4.OptionServerIdentifier, []byte(serverID))
for _, o := range options {
p.AddOption(o.Code, o.Value)
}
p.PadToMinSize()
return p
}
