func (_ discoverState) do(ctx *dhcpContext) iState {
ctx.resetLease()
// Set up all the layers' fields we can.
eth := &layers.Ethernet{
SrcMAC: ctx.MacAddr,
DstMAC: arp.HwAddrBcast,
EthernetType: layers.EthernetTypeIPv4,
}
ipv4 := &layers.IPv4{
Version: 4,
TTL: 255,
Protocol: layers.IPProtocolUDP,
SrcIP: net.IPv4zero,
DstIP: net.IPv4bcast,
}
udp := &layers.UDP{
SrcPort: network.Bootpc,
DstPort: network.Bootps,
}
udp.SetNetworkLayerForChecksum(ipv4)
buf := network.GetBuffer()
defer network.ReleaseBuffer(buf)
discover := new(dhcpv4.DhcpPacket)
discover.ConstructWithPreAllocatedBuffer(buf, option.DHCPDISCOVER)
discover.SetMacAddr(ctx.MacAddr)
discover.SetXid(ctx.xid[:])
if DhcRelay {
discover.SetGiAddr(ctx.giaddr)
discover.AddOption(generateOption82(ctx.MacAddr))
}
if Option90 {
discover.AddOption(generateOption90(ctx.login))
}
bootp := &layer.PayloadLayer{
Contents: discover.Raw,
}
var (
sleep time.Duration
tries uint = 1
)
for {
// send discover
for err := network.SentPacket(eth, ipv4, udp, bootp); err != nil; {
log.Println(ctx.MacAddr, "DISCOVER: error sending discover", err)
time.Sleep(2 * time.Second)
continue
}
// sleep = 2s, 4s, 8s, 16s, 32s, 64s, 64s 64s ...
if tries < 6 {
sleep = (1 << tries) * time.Second
} else {
sleep = 64 * time.Second
}
var (
payload []byte
timeout time.Duration
deadline = time.Now().Add(sleep)
)
for {
timeout = deadline.Sub(time.Now())
select {
case <-time.After(timeout):
log.Println(ctx.MacAddr, "DISCOVER: timeout", tries)
goto TIMEOUT
case payload = <-ctx.dhcpIn:
dp, err := dhcpv4.Parse(payload)
if err != nil {
// it is not DHCP packet...
continue
}
if !bytes.Equal(ctx.xid[:], dp.GetXid()) {
// bug of DHCP Server ?
log.Println(ctx.MacAddr, fmt.Sprintf("DISCOVER: unexpected xid [Expected: 0x%v] [Actual: 0x%v]", hex.EncodeToString(ctx.xid[:]), hex.EncodeToString(dp.GetXid())))
continue
}
if msgType, err := dp.GetTypeMessage(); err == nil {
switch msgType {
case option.DHCPOFFER:
ctx.IpAddr.Store(net.IP(util.ConvertUint32ToNew4byte(dp.GetYourIp())))
ctx.serverIp = dp.GetNextServerIp()
err := ctx.arpClient.SendGratuitousARP()
if err != nil {
fmt.Println(ctx.MacAddr, "send gratuitousARP error", err)
}
ctx.t0, ctx.t1, ctx.t2 = extractAllLeaseTime(dp)
return requestSelectState{}
default:
log.Println(ctx.MacAddr, fmt.Sprintf("DISCOVER: Unexcpected message [Excpected: %s] [Actual: %s]", option.DHCPDISCOVER, msgType))
continue
}
} else {
log.Println(ctx.MacAddr, "DISCOVER: Option 53 is missing")
continue
}
}
}
TIMEOUT:
tries++
}
}
func (_ requestRebindState) do(ctx *dhcpContext) iState {
ipAddr := ctx.IpAddr.Load().(net.IP)
// Set up all the layers' fields we can.
eth := &layers.Ethernet{
SrcMAC: ctx.MacAddr,
DstMAC: arp.HwAddrBcast,
EthernetType: layers.EthernetTypeIPv4,
}
ipv4 := &layers.IPv4{
Version: 4,
TTL: 255,
Protocol: layers.IPProtocolUDP,
SrcIP: net.IPv4zero,
DstIP: net.IPv4bcast,
}
udp := &layers.UDP{
SrcPort: network.Bootpc,
DstPort: network.Bootps,
}
udp.SetNetworkLayerForChecksum(ipv4)
buf := network.GetBuffer()
defer network.ReleaseBuffer(buf)
request := new(dhcpv4.DhcpPacket)
request.ConstructWithPreAllocatedBuffer(buf, option.DHCPREQUEST)
request.SetXid(ctx.xid[:])
request.SetMacAddr(ctx.MacAddr)
opt50 := new(option.Option50RequestedIpAddress)
opt50.Construct(util.Convert4byteToUint32(ipAddr))
request.AddOption(opt50)
opt61 := new(option.Option61ClientIdentifier)
opt61.Construct(byte(1), ctx.MacAddr)
request.AddOption(opt61)
if DhcRelay {
request.SetGiAddr(ctx.giaddr)
request.AddOption(generateOption82(ctx.MacAddr))
}
if Option90 {
request.AddOption(generateOption90(ctx.login))
}
bootp := &layer.PayloadLayer{
Contents: request.Raw,
}
for {
// send request
for err := network.SentPacket(eth, ipv4, udp, bootp); err != nil; {
log.Println(ctx.MacAddr, "REBIND: error sending request", err)
time.Sleep(2 * time.Second)
}
var (
payload []byte
timeout time.Duration
deadline = time.Now().Add(2 * time.Second)
)
for {
timeout = deadline.Sub(time.Now())
select {
case <-time.After(timeout):
log.Println(ctx.MacAddr, "REBIND: timeout")
return timeoutRebindState{}
case payload = <-ctx.dhcpIn:
dp, err := dhcpv4.Parse(payload)
if err != nil {
// it is not DHCP packet...
continue
}
if !bytes.Equal(ctx.xid[:], dp.GetXid()) {
// bug of DHCP Server ?
log.Println(ctx.MacAddr, fmt.Sprintf("REBIND: unexpected xid [Expected: 0x%v] [Actual: 0x%v]", hex.EncodeToString(ctx.xid[:]), hex.EncodeToString(dp.GetXid())))
continue
}
if msgType, err := dp.GetTypeMessage(); err == nil {
switch msgType {
case option.DHCPACK:
ctx.t0, ctx.t1, ctx.t2 = extractAllLeaseTime(dp)
return sleepState{}
case option.DHCPNAK:
log.Println(ctx.MacAddr, "REBIND: receive NAK")
return discoverState{}
default:
log.Println(ctx.MacAddr, fmt.Sprintf("REBIND: unexpected message [Excpected: %s] [Actual: %s]", option.DHCPACK, msgType))
continue
}
} else {
log.Println(ctx.MacAddr, "REBIND: option 53 is missing")
continue
}
}
}
}
}
