dhcp test
This commit is contained in:
insanity
parent
01b201266c
commit
69c2837a31
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@ -5,41 +5,12 @@ import (
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"encoding/binary"
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"encoding/binary"
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"fmt"
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"fmt"
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"net"
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"net"
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"strings"
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)
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const (
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"github.com/google/gopacket/layers"
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MAGIC_COOKIE uint32 = 0x63825363
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OPT_CODE_SERVER_IDENTIFIER uint8 = 54
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OPT_CODE_SUBNET_MASK uint8 = 1
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OPT_CODE_ROUTER uint8 = 3
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OPT_CODE_DNS uint8 = 6
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)
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type dhcpDiscover struct {
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"github.com/google/gopacket"
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MsgType byte
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gl "github.com/google/gopacket/layers"
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HwType byte
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)
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HwAddrLen byte
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Hops byte
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Xid uint32
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Secs uint16
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BootpFlags uint16
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ClientIp uint32
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YourIp uint32
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NextServerIp uint32
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RelayAgentIp uint32
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ClientMacAddr [6]byte
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ClientHwAddrPadding [10]byte
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ServerHostName [64]byte
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BootFileName [128]byte
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MagicCookie uint32
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Mtype byte
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MtypeLen byte
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MtypeVal byte
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Opts [200]byte
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End byte
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Padding [16]byte
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}
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func doDiscover(address string) (map[string]string, error) {
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func doDiscover(address string) (map[string]string, error) {
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@ -51,13 +22,9 @@ func doDiscover(address string) (map[string]string, error) {
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if err != nil {
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if err != nil {
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return nil, err
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return nil, err
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}
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}
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if err != nil {
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return nil, err
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}
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defer conn.Close()
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defer conn.Close()
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sendDiscover(conn) // broadcast 255.255.255.255:67
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sendDiscover(conn) // broadcast 255.255.255.255:67
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return readOffer(conn) // unicast
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return readOffer(conn) // unicast
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}
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}
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@ -70,32 +37,27 @@ func sendDiscover(conn *net.UDPConn) error {
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return err
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return err
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}
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}
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dhcp := dhcpDiscover{
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dhcp := &gl.DHCPv4{Operation: gl.DHCPOpRequest, HardwareType: gl.LinkTypeEthernet, Xid: 0x12345678,
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MsgType: 0x01,
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ClientIP: net.IP{0, 0, 0, 0}, YourClientIP: net.IP{0, 0, 0, 0}, NextServerIP: net.IP{0, 0, 0, 0}, RelayAgentIP: net.IP{0, 0, 0, 0},
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HwType: 0x01,
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ClientHWAddr: net.HardwareAddr{0x12, 0x34, 0x56, 0x78, 0x9a, 0xbc},
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HwAddrLen: 0x06,
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ServerName: make([]byte, 64), File: make([]byte, 128)}
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Hops: 0x00,
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Xid: 0x00000000,
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Secs: 0x0000,
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ClientIp: 0x00000000,
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YourIp: 0x00000000,
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NextServerIp: 0x00000000,
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RelayAgentIp: 0x00000000,
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MagicCookie: MAGIC_COOKIE,
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Mtype: 0x35,
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MtypeLen: 0x01,
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MtypeVal: 0x01,
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End: 0xff,
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}
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var flag uint16 = 0
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dhcp.Options = append(dhcp.Options, gl.NewDHCPOption(gl.DHCPOptMessageType, []byte{byte(gl.DHCPMsgTypeDiscover)}))
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dhcp.BootpFlags = ^flag // flag = unicast , ^flag = broadcast
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dhcp.Options = append(dhcp.Options, gl.NewDHCPOption(gl.DHCPOptHostname, []byte{'o', 'v', 'e', 'r', 'f', 'l', 'o', 'w', '.', 'c', 'o', 'm'}))
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dhcp.Options = append(dhcp.Options, gl.NewDHCPOption(gl.DHCPOptPad, nil))
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dhcp.Options = append(dhcp.Options, gl.NewDHCPOption(gl.DHCPOptParamsRequest,
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[]byte{byte(gl.DHCPOptSubnetMask), byte(gl.DHCPOptBroadcastAddr), byte(gl.DHCPOptTimeOffset),
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byte(gl.DHCPOptRouter), byte(gl.DHCPOptDomainName), byte(gl.DHCPOptDNS), byte(gl.DHCPOptDomainSearch),
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byte(gl.DHCPOptHostname), byte(gl.DHCPOptNetBIOSTCPNS), byte(gl.DHCPOptInterfaceMTU), byte(gl.DHCPOptClasslessStaticRoute),
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byte(gl.DHCPOptNTPServers)}))
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writer := new(bytes.Buffer)
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buf := gopacket.NewSerializeBuffer()
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if err := binary.Write(writer, binary.BigEndian, dhcp); err != nil {
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opts := gopacket.SerializeOptions{FixLengths: true}
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err = gopacket.SerializeLayers(buf, opts, dhcp)
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if err != nil {
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return err
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return err
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}
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}
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_, err = conn.WriteToUDP(writer.Bytes(), serverAddr)
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_, err = conn.WriteToUDP(buf.Bytes(), serverAddr)
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if err != nil {
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if err != nil {
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return err
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return err
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}
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}
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@ -107,62 +69,52 @@ func readOffer(conn *net.UDPConn) (map[string]string, error) {
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offerOptions := make(map[string]string)
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offerOptions := make(map[string]string)
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buf := make([]byte, 1024)
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buf := make([]byte, 1024)
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_, _, err := conn.ReadFromUDP(buf)
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n, _, err := conn.ReadFromUDP(buf)
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if err != nil {
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if err != nil {
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return nil, err
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return nil, err
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}
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}
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if n <= 0 {
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return nil, fmt.Errorf("%s", "Emptry response.")
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}
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offer := dhcpDiscover{}
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var dhcp gl.DHCPv4
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decoded := []gopacket.LayerType{}
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reader := new(bytes.Buffer)
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parser := gopacket.NewDecodingLayerParser(gl.LayerTypeDHCPv4, &dhcp)
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reader.Write(buf)
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if err = parser.DecodeLayers(buf, &decoded); err != nil {
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if err := binary.Read(reader, binary.BigEndian, &offer); err != nil {
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return nil, err
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return nil, err
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}
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}
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if offer.MagicCookie != MAGIC_COOKIE {
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for _, layerType := range decoded {
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return nil, err
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switch layerType {
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case layers.LayerTypeDHCPv4:
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for _, opt := range dhcp.Options {
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switch opt.Type {
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case gl.DHCPOptServerID:
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offerOptions["DHCP_SERVER"] = optDataToIPString(opt.Data)
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break
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case gl.DHCPOptLeaseTime:
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var sec int32
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if err = binary.Read(bytes.NewReader(opt.Data), binary.BigEndian, &sec); err == nil {
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offerOptions["LEASE_TIME"] = fmt.Sprintf("%d", sec)
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}
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}
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break
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//option searching
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case gl.DHCPOptSubnetMask:
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r := new(bytes.Buffer)
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offerOptions["SUBNET_MASK"] = optDataToIPString(opt.Data)
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r.Write(offer.Opts[:])
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break
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case gl.DHCPOptRouter:
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for i := 0; i < r.Len(); i++ {
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offerOptions["ROUTER"] = optDataToIPString(opt.Data)
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v := r.Next(1)[0]
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break
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case gl.DHCPOptDNS:
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if v == OPT_CODE_SUBNET_MASK && r.Next(1)[0] == 4 {
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offerOptions["DNS_SERVER"] = optDataToIPString(opt.Data)
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ipStr := byteToIPString(r.Next(4))
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break
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offerOptions["SUBNETMASK"] = ipStr
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}
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}
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if v == OPT_CODE_ROUTER && r.Next(1)[0] == 4 {
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ipStr := byteToIPString(r.Next(4))
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offerOptions["ROUTER"] = ipStr
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}
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}
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if v == OPT_CODE_DNS {
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len := r.Next(1)[0]
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var dns []string
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var ipStr string
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ipStr = byteToIPString(r.Next(4))
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dns = append(dns, ipStr)
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if len == 8 {
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ipStr = byteToIPString(r.Next(4))
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dns = append(dns, ipStr)
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}
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offerOptions["DNS"] = strings.Join(dns, ",")
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}
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if v == OPT_CODE_SERVER_IDENTIFIER && r.Next(1)[0] == 4 {
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ipStr := byteToIPString(r.Next(4))
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offerOptions["DHCP_SERVER"] = ipStr
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}
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}
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}
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}
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return offerOptions, nil
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return offerOptions, nil
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}
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}
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func byteToIPString(b []byte) string {
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func optDataToIPString(b []byte) string {
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var ipStr string
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var ipStr string
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len := len(b)
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len := len(b)
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for i := 0; i < len; i++ {
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for i := 0; i < len; i++ {
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@ -5,7 +5,7 @@ import (
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)
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)
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func TestDHCP(t *testing.T) {
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func TestDHCP(t *testing.T) {
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offer, err := doDiscover("192.168.1.201")
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offer, err := doDiscover("192.168.1.203")
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if err != nil {
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if err != nil {
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t.Errorf("ERROR : %s", err.Error())
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t.Errorf("ERROR : %s", err.Error())
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}
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}
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