code: func (c *Client) RenewalRequestPacket(acknowledgement *dhcp4.Packet) dhcp4.Packet {
  	messageid := make([]byte, 4)
  	c.generateXID(messageid)
  
  	acknowledgementOptions := acknowledgement.ParseOptions()
  
  	packet := dhcp4.NewPacket(dhcp4.BootRequest)
  	packet.SetCHAddr(acknowledgement.CHAddr())
  
  	packet.SetXId(messageid)
  	packet.SetCIAddr(acknowledgement.YIAddr())
  	packet.SetSIAddr(acknowledgement.SIAddr())
  
  	packet.SetBroadcast(c.broadcast)
  	packet.AddOption(dhcp4.OptionDHCPMessageType, []byte{byte(dhcp4.Request)})
  	packet.AddOption(dhcp4.OptionRequestedIPAddress, (acknowledgement.YIAddr()).To4())
  	packet.AddOption(dhcp4.OptionServerIdentifier, acknowledgementOptions[dhcp4.OptionServerIdentifier])
  
  	return packet
  }
docs: //Create Request Packet For a Renew