/* * Lets do a Full DHCP Request. */ func (c *Client) Request() (bool, dhcp4.Packet, error) { discoveryPacket, err := c.SendDiscoverPacket() if err != nil { return false, discoveryPacket, err } offerPacket, err := c.GetOffer(&discoveryPacket) if err != nil { return false, offerPacket, err } requestPacket, err := c.SendRequest(&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 }
/* * Retreive Offer... * Wait for the offer for a specific Discovery Packet. */ func (c *Client) GetOffer(discoverPacket *dhcp4.Packet) (dhcp4.Packet, error) { for { c.connection.SetReadTimeout(c.timeout) readBuffer, source, err := c.connection.ReadFrom() if err != nil { return dhcp4.Packet{}, err } offerPacket := dhcp4.Packet(readBuffer) offerPacketOptions := offerPacket.ParseOptions() // Ignore Servers in my Ignore list for _, ignoreServer := range c.ignoreServers { if source.Equal(ignoreServer) { continue } if offerPacket.SIAddr().Equal(ignoreServer) { continue } } if len(offerPacketOptions[dhcp4.OptionDHCPMessageType]) < 1 || dhcp4.MessageType(offerPacketOptions[dhcp4.OptionDHCPMessageType][0]) != dhcp4.Offer || !bytes.Equal(discoverPacket.XId(), offerPacket.XId()) { continue } return offerPacket, nil } }
/* * Renew a lease backed on the Acknowledgement Packet. * Returns Sucessfull, The AcknoledgementPacket, Any Errors */ func (c *Client) Renew(acknowledgement dhcp4.Packet) (bool, dhcp4.Packet, error) { renewRequest := c.RenewalRequestPacket(&acknowledgement) 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 }
/* * Retreive Acknowledgement * Wait for the offer for a specific Request Packet. */ func (c *Client) GetAcknowledgement(requestPacket *dhcp4.Packet) (dhcp4.Packet, error) { for { c.connection.SetReadTimeout(c.timeout) readBuffer, source, err := c.connection.ReadFrom() if err != nil { return dhcp4.Packet{}, err } acknowledgementPacket := dhcp4.Packet(readBuffer) acknowledgementPacketOptions := acknowledgementPacket.ParseOptions() // Ignore Servers in my Ignore list for _, ignoreServer := range c.ignoreServers { if source.Equal(ignoreServer) { continue } if acknowledgementPacket.SIAddr().Equal(ignoreServer) { continue } } if !bytes.Equal(requestPacket.XId(), acknowledgementPacket.XId()) || len(acknowledgementPacketOptions[dhcp4.OptionDHCPMessageType]) < 1 || (dhcp4.MessageType(acknowledgementPacketOptions[dhcp4.OptionDHCPMessageType][0]) != dhcp4.ACK && dhcp4.MessageType(acknowledgementPacketOptions[dhcp4.OptionDHCPMessageType][0]) != dhcp4.NAK) { continue } return acknowledgementPacket, nil } }