/*
* 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
}
}
func (c *client) renew(cl *dhcp4client.Client) (dhcp4.Packet, error) {
defer trace.End(trace.Begin(""))
rp := cl.RenewalRequestPacket(&c.ack)
rp, err := c.setOptions(rp)
if err != nil {
return nil, err
}
rp.PadToMinSize()
if err = cl.SendPacket(rp); err != nil {
return nil, err
}
newack, err := cl.GetAcknowledgement(&rp)
if err != nil {
return nil, err
}
opts := newack.ParseOptions()
if dhcp4.MessageType(opts[dhcp4.OptionDHCPMessageType][0]) == dhcp4.NAK {
return nil, fmt.Errorf("received NAK from DHCP server")
}
return newack, nil
}
func (c *client) request(cl *dhcp4client.Client) (bool, dhcp4.Packet, error) {
defer trace.End(trace.Begin(""))
dp, err := c.discoverPacket(cl)
if err != nil {
return false, nil, err
}
dp.PadToMinSize()
if err = cl.SendPacket(dp); err != nil {
return false, nil, err
}
var op dhcp4.Packet
for {
op, err = cl.GetOffer(&dp)
if err != nil {
return false, nil, err
}
if c.isCompletePacket(dhcp.NewPacket([]byte(op))) {
break
}
}
rp, err := c.requestPacket(cl, &op)
if err != nil {
return false, nil, err
}
rp.PadToMinSize()
if err = cl.SendPacket(rp); err != nil {
return false, nil, err
}
ack, err := cl.GetAcknowledgement(&rp)
if err != nil {
return false, nil, err
}
opts := ack.ParseOptions()
if dhcp4.MessageType(opts[dhcp4.OptionDHCPMessageType][0]) == dhcp4.NAK {
return false, nil, fmt.Errorf("Got NAK from DHCP server")
}
return true, ack, 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
}
func (c *client) renew(id ID, ack dhcp4.Packet, cl *dhcp4client.Client) (dhcp4.Packet, error) {
rp := cl.RenewalRequestPacket(&ack)
_, err := c.appendOptions(&rp, id)
if err != nil {
return nil, err
}
rp.PadToMinSize()
if err = cl.SendPacket(rp); err != nil {
return nil, err
}
newack, err := cl.GetAcknowledgement(&rp)
if err != nil {
return nil, err
}
opts := newack.ParseOptions()
if dhcp4.MessageType(opts[dhcp4.OptionDHCPMessageType][0]) == dhcp4.NAK {
return nil, fmt.Errorf("received NAK from DHCP server")
}
return newack, nil
}
func (s *Server) ServeDHCP(packet dhcp4.Packet) (dhcp4.Packet, error) {
packetOptions := packet.ParseOptions()
switch dhcp4.MessageType(packetOptions[dhcp4.OptionDHCPMessageType][0]) {
case dhcp4.Discover:
//Discover Received from client
//Lets get the lease we're going to send them
found, lease, err := s.GetLease(packet)
if err != nil {
return dhcp4.Packet{}, err
}
if !found {
log.Println("Warning: It Looks Like Our Leases Are Depleted...")
return dhcp4.Packet{}, nil
}
offerPacket := s.OfferPacket(packet)
offerPacket.SetYIAddr(lease.IP)
//Sort out the packet options
offerPacket.PadToMinSize()
lease.Status = leasepool.Reserved
lease.MACAddress = packet.CHAddr()
//If the lease expires within the next 5 Mins increase the lease expiary (Giving the Client 5 mins to complete)
if lease.Expiry.Before(time.Now().Add(time.Minute * 5)) {
lease.Expiry = time.Now().Add(time.Minute * 5)
}
if packetOptions[dhcp4.OptionHostName] != nil && string(packetOptions[dhcp4.OptionHostName]) != "" {
lease.Hostname = string(packetOptions[dhcp4.OptionHostName])
}
updated, err := s.leasePool.UpdateLease(lease)
if err != nil {
return dhcp4.Packet{}, err
}
if !updated {
//Unable to reserve lease (It's now active else where maybe?)
return dhcp4.Packet{}, errors.New("Unable to Reserve Lease:" + lease.IP.String())
}
return offerPacket, nil
case dhcp4.Request:
//Request Received from client
//Lets get the lease we're going to send them
found, lease, err := s.GetLease(packet)
if err != nil {
return dhcp4.Packet{}, err
}
if !found {
log.Println("Warning: It Looks Like Our Leases Are Depleted...")
return dhcp4.Packet{}, nil
}
//If the lease is not the one requested We should send a NAK..
if len(packetOptions) > 0 && !net.IP(packetOptions[dhcp4.OptionRequestedIPAddress]).Equal(lease.IP) {
//NAK
declinePacket := s.DeclinePacket(packet)
declinePacket.PadToMinSize()
return declinePacket, nil
} else {
lease.Status = leasepool.Active
lease.MACAddress = packet.CHAddr()
lease.Expiry = time.Now().Add(s.leaseDuration)
if packetOptions[dhcp4.OptionHostName] != nil && string(packetOptions[dhcp4.OptionHostName]) != "" {
lease.Hostname = string(packetOptions[dhcp4.OptionHostName])
}
updated, err := s.leasePool.UpdateLease(lease)
if err != nil {
return dhcp4.Packet{}, err
}
if updated {
//ACK
acknowledgementPacket := s.AcknowledgementPacket(packet)
acknowledgementPacket.SetYIAddr(lease.IP)
//Lease time.
acknowledgementPacket.AddOption(dhcp4.OptionIPAddressLeaseTime, dhcp4.OptionsLeaseTime(lease.Expiry.Sub(time.Now())))
acknowledgementPacket.PadToMinSize()
return acknowledgementPacket, nil
} else {
//NAK
declinePacket := s.DeclinePacket(packet)
declinePacket.PadToMinSize()
return declinePacket, nil
}
}
case dhcp4.Decline:
//Decline from the client:
log.Printf("Debug: Decline Message:%v\n", packet)
case dhcp4.Release:
//Decline from the client:
log.Printf("Debug: Release Message:%v\n", packet)
default:
log.Printf("Debug: Unexpected Packet Type:%v\n", dhcp4.MessageType(packetOptions[dhcp4.OptionDHCPMessageType][0]))
}
return dhcp4.Packet{}, nil
}
/*
* Test Discovering a Lease That's not Within Our Lease Range.
* This Happens When a devce switches network.
* Example: Mobile Phone on Mobile internet Has IP 100.123.123.123 Switch To Home Wifi
* The device requests 100.123.123.123 on Home Wifi which is out of range...
*/
func TestDiscoverOutOfRangeLease(test *testing.T) {
//Setup the Server
myServer, err := dhcp4server.New(
net.IPv4(192, 168, 1, 201),
getTestLeasePool(),
dhcp4server.SetLocalAddr(net.UDPAddr{IP: net.IPv4(127, 0, 0, 1), Port: 1067}),
dhcp4server.SetRemoteAddr(net.UDPAddr{IP: net.IPv4(127, 0, 0, 1), Port: 1068}),
)
if err != nil {
test.Error("Error: Can't Configure Server " + err.Error())
}
var wg sync.WaitGroup
wg.Add(1)
go func() {
defer wg.Done()
err := myServer.ListenAndServe()
if err != nil {
log.Fatalln("Error Starting Server:" + err.Error())
}
}()
time.Sleep(time.Duration(5) * time.Second)
//Generate Hardware Address
HardwareMACAddress, err := hardwareaddr.GenerateEUI48()
if err != nil {
test.Error("Error: Can't Generate Valid MACAddress" + err.Error())
}
//Lets Be A Client
//We need to set the connection ports to 1068 and 1067 so we don't need root access
c, err := dhcp4client.NewInetSock(dhcp4client.SetLocalAddr(net.UDPAddr{IP: net.IPv4(127, 0, 0, 1), Port: 1068}), dhcp4client.SetRemoteAddr(net.UDPAddr{IP: net.IPv4(127, 0, 0, 1), Port: 1067}))
if err != nil {
test.Error("Client Conection Generation:" + err.Error())
}
client, err := dhcp4client.New(dhcp4client.HardwareAddr(HardwareMACAddress), dhcp4client.Connection(c))
defer client.Close()
if err != nil {
test.Error("Conection Error:" + err.Error())
}
discoveryPacket := client.DiscoverPacket()
discoveryPacket.SetCIAddr(net.IPv4(100, 102, 96, 123))
discoveryPacket.PadToMinSize()
err = client.SendPacket(discoveryPacket)
if err != nil {
test.Error("Error: Sending Discover Packet" + err.Error())
}
test.Log("--Discovery Packet--")
test.Logf("Client IP : %v\n", discoveryPacket.CIAddr().String())
test.Logf("Your IP : %v\n", discoveryPacket.YIAddr().String())
test.Logf("Server IP : %v\n", discoveryPacket.SIAddr().String())
test.Logf("Gateway IP: %v\n", discoveryPacket.GIAddr().String())
test.Logf("Client Mac: %v\n", discoveryPacket.CHAddr().String())
if !bytes.Equal(discoveryPacket.CHAddr(), HardwareMACAddress) {
test.Error("MACAddresses Don't Match??")
}
offerPacket, err := client.GetOffer(&discoveryPacket)
if err != nil {
test.Error("Error Getting Offer:" + err.Error())
}
test.Log("--Offer Packet--")
test.Logf("Client IP : %v\n", offerPacket.CIAddr().String())
test.Logf("Your IP : %v\n", offerPacket.YIAddr().String())
test.Logf("Server IP : %v\n", offerPacket.SIAddr().String())
test.Logf("Gateway IP: %v\n", offerPacket.GIAddr().String())
test.Logf("Client Mac: %v\n", offerPacket.CHAddr().String())
requestPacket, err := client.SendRequest(&offerPacket)
if err != nil {
test.Error("Error Sending Request:" + err.Error())
}
test.Log("--Request Packet--")
test.Logf("Client IP : %v\n", requestPacket.CIAddr().String())
test.Logf("Your IP : %v\n", requestPacket.YIAddr().String())
test.Logf("Server IP : %v\n", requestPacket.SIAddr().String())
test.Logf("Gateway IP: %v\n", requestPacket.GIAddr().String())
test.Logf("Client Mac: %v\n", requestPacket.CHAddr().String())
acknowledgement, err := client.GetAcknowledgement(&requestPacket)
if err != nil {
test.Error("Error Getting Acknowledgement:" + err.Error())
}
test.Log("--Acknowledgement Packet--")
test.Logf("Client IP : %v\n", acknowledgement.CIAddr().String())
test.Logf("Your IP : %v\n", acknowledgement.YIAddr().String())
test.Logf("Server IP : %v\n", acknowledgement.SIAddr().String())
test.Logf("Gateway IP: %v\n", acknowledgement.GIAddr().String())
test.Logf("Client Mac: %v\n", acknowledgement.CHAddr().String())
acknowledgementOptions := acknowledgement.ParseOptions()
if dhcp4.MessageType(acknowledgementOptions[dhcp4.OptionDHCPMessageType][0]) != dhcp4.ACK {
test.Error("Didn't get ACK?:" + err.Error())
}
test.Log("Shutting Down Server")
myServer.Shutdown()
wg.Wait()
}
/*
* Try Renewing A Lease From A Different Network.
*/
func TestRequestOutOfRangeLease(test *testing.T) {
//Setup the Server
myServer, err := dhcp4server.New(
net.IPv4(192, 168, 1, 201),
getTestLeasePool(),
dhcp4server.SetLocalAddr(net.UDPAddr{IP: net.IPv4(127, 0, 0, 1), Port: 1067}),
dhcp4server.SetRemoteAddr(net.UDPAddr{IP: net.IPv4(127, 0, 0, 1), Port: 1068}),
)
if err != nil {
test.Error("Error: Can't Configure Server " + err.Error())
}
var wg sync.WaitGroup
wg.Add(1)
go func() {
defer wg.Done()
err := myServer.ListenAndServe()
if err != nil {
log.Fatalln("Error Starting Server:" + err.Error())
}
}()
//Sleep some so the server starts....
time.Sleep(time.Duration(5) * time.Second)
//Generate Hardware Address
HardwareMACAddress, err := hardwareaddr.GenerateEUI48()
if err != nil {
test.Error("Error: Can't Generate Valid MACAddress" + err.Error())
}
HardwareMACAddress, err = net.ParseMAC("58-94-6B-73-57-0C")
if err != nil {
log.Printf("MAC Error:%v\n", err)
}
//Lets Be A Client
c, err := dhcp4client.NewInetSock(dhcp4client.SetLocalAddr(net.UDPAddr{IP: net.IPv4(127, 0, 0, 1), Port: 1068}), dhcp4client.SetRemoteAddr(net.UDPAddr{IP: net.IPv4(127, 0, 0, 1), Port: 1067}))
if err != nil {
test.Error("Client Conection Generation:" + err.Error())
}
client, err := dhcp4client.New(dhcp4client.HardwareAddr(HardwareMACAddress), dhcp4client.Connection(c))
defer client.Close()
if err != nil {
test.Error("Conection Error:" + err.Error())
}
//Create a dummy offer packet
offerPacket := client.DiscoverPacket()
offerPacket.SetCIAddr(net.IPv4(100, 102, 96, 123))
offerPacket.SetSIAddr(net.IPv4(192, 168, 1, 201))
offerPacket.SetYIAddr(net.IPv4(100, 102, 96, 123))
offerPacket.AddOption(dhcp4.OptionDHCPMessageType, []byte{byte(dhcp4.Offer)})
requestPacket, err := client.SendRequest(&offerPacket)
if err != nil {
test.Error("Error Sending Request:" + err.Error())
}
test.Log("--Request Packet--")
test.Logf("Client IP : %v\n", requestPacket.CIAddr().String())
test.Logf("Your IP : %v\n", requestPacket.YIAddr().String())
test.Logf("Server IP : %v\n", requestPacket.SIAddr().String())
test.Logf("Gateway IP: %v\n", requestPacket.GIAddr().String())
test.Logf("Client Mac: %v\n", requestPacket.CHAddr().String())
acknowledgement, err := client.GetAcknowledgement(&requestPacket)
if err != nil {
test.Error("Error Getting Acknowledgement:" + err.Error())
}
test.Log("--Acknowledgement Packet--")
test.Logf("Client IP : %v\n", acknowledgement.CIAddr().String())
test.Logf("Your IP : %v\n", acknowledgement.YIAddr().String())
test.Logf("Server IP : %v\n", acknowledgement.SIAddr().String())
test.Logf("Gateway IP: %v\n", acknowledgement.GIAddr().String())
test.Logf("Client Mac: %v\n", acknowledgement.CHAddr().String())
acknowledgementOptions := acknowledgement.ParseOptions()
if len(acknowledgementOptions[dhcp4.OptionDHCPMessageType]) <= 0 || dhcp4.MessageType(acknowledgementOptions[dhcp4.OptionDHCPMessageType][0]) != dhcp4.NAK {
test.Errorf("Didn't get NAK got DHCP4 Message Type:%v\n", dhcp4.MessageType(acknowledgementOptions[dhcp4.OptionDHCPMessageType][0]))
}
test.Log("Shutting Down Server")
myServer.Shutdown()
wg.Wait()
}
/*
* 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
}
}