ing

service/matcher/dhcp/dhcp.go

@@ -0,0 +1,189 @@
+package dhcp
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"net"
+	"time"
+
+	"git.loafle.net/commons_go/logging"
+	"git.loafle.net/overflow/overflow_discovery/api/module/discovery/model"
+)
+
+const (
+	MAGIC_COOKIE               uint32 = 0x63825363
+	OPT_CODE_SERVER_IDENTIFIER uint8  = 54
+	OPT_CODE_SUBNET_MASK       uint8  = 1
+	OPT_CODE_ROUTER            uint8  = 3
+	OPT_CODE_DNS               uint8  = 6
+)
+
+type dhcpDiscover struct {
+	MsgType             byte
+	HwType              byte
+	HwAddrLen           byte
+	Hops                byte
+	Xid                 uint32
+	Secs                uint16
+	BootpFlags          uint16
+	ClientIp            uint32
+	YourIp              uint32
+	NextServerIp        uint32
+	RelayAgentIp        uint32
+	ClientMacAddr       [6]byte
+	ClientHwAddrPadding [10]byte
+	ServerHostName      [64]byte
+	BootFileName        [128]byte
+	MagicCookie         uint32
+	Mtype               byte
+	MtypeLen            byte
+	MtypeVal            byte
+	Opts                [200]byte
+	End                 byte
+	Padding             [16]byte
+}
+
+func DiscoverDHCP(zone *model.DiscoveryZone) {
+	err := sendDHCPDiscovery()
+	if err != nil {
+		logging.Logger().Error(fmt.Sprintf("Discovery: DHCP Matcher %v", err))
+		return
+	}
+	recvDHCPOffer(zone)
+}
+
+func sendDHCPDiscovery() error {
+	dhcp := dhcpDiscover{
+		MsgType:      0x01,
+		HwType:       0x01,
+		HwAddrLen:    0x06,
+		Hops:         0x00,
+		Xid:          0x00000000,
+		Secs:         0x0000,
+		ClientIp:     0x00000000,
+		YourIp:       0x00000000,
+		NextServerIp: 0x00000000,
+		RelayAgentIp: 0x00000000,
+		MagicCookie:  MAGIC_COOKIE,
+		Mtype:        0x35,
+		MtypeLen:     0x01,
+		MtypeVal:     0x01,
+		End:          0xff,
+	}
+
+	var flag uint16 = 0
+	dhcp.BootpFlags = ^flag // flag = unicast , ^flag = broadcast
+
+	//TODO : getting mac addr from zone
+	//dhcp.ClientMacAddr[0] = 0x50
+	//dhcp.ClientMacAddr[1] = 0xe5
+	//dhcp.ClientMacAddr[2] = 0x49
+	//dhcp.ClientMacAddr[3] = 0x46
+	//dhcp.ClientMacAddr[4] = 0x93
+	//dhcp.ClientMacAddr[5] = 0x28
+
+	writer := new(bytes.Buffer)
+	binary.Write(writer, binary.BigEndian, dhcp)
+	conn, err := net.Dial("udp", "255.255.255.255:67")
+	if err != nil {
+		return err
+	}
+	conn.Write(writer.Bytes())
+	defer conn.Close()
+
+	return nil
+}
+
+func recvDHCPOffer(zone *model.DiscoveryZone) {
+
+	socket, err := net.ListenUDP("udp4", &net.UDPAddr{
+		IP:   net.IPv4(255, 255, 255, 255),
+		Port: 68,
+	})
+	if err != nil {
+		logging.Logger().Error(fmt.Sprintf("Discovery: DHCP Matcher %v", err))
+		return
+	}
+	err = socket.SetDeadline(time.Now().Add(3 * time.Second))
+	if err != nil {
+		logging.Logger().Error(fmt.Sprintf("Discovery: DHCP Matcher %v", err))
+		return
+	}
+
+	buf := make([]byte, 4096)
+	n, _, err := socket.ReadFromUDP(buf)
+	if err != nil {
+		logging.Logger().Error(fmt.Sprintf("Discovery: DHCP Matcher %v", err))
+		return
+	}
+	if n <= 0 {
+		logging.Logger().Error(fmt.Sprintf("Discovery: DHCP Matcher has no DHCP offer."))
+		return
+	}
+
+	offer := dhcpDiscover{}
+
+	reader := new(bytes.Buffer)
+	reader.Write(buf)
+	if err := binary.Read(reader, binary.BigEndian, &offer); err != nil {
+		logging.Logger().Error(fmt.Sprintf("Discovery: DHCP Matcher %v", err))
+		return
+	}
+	if offer.MagicCookie != MAGIC_COOKIE {
+		logging.Logger().Error(fmt.Sprintf("Discovery: DHCP Matcher is not a DHCP packet."))
+		return
+	}
+
+	//option searching
+	r := new(bytes.Buffer)
+	r.Write(offer.Opts[:])
+
+	for i := 0; i < r.Len(); i++ {
+		v := r.Next(1)[0]
+
+		if v == OPT_CODE_SUBNET_MASK && r.Next(1)[0] == 4 {
+			ipStr := byteToIpString(r.Next(4))
+			logging.Logger().Info(fmt.Sprintf("Discovery: DHCP Matcher SUBNET MASK: %s", ipStr))
+		}
+
+		if v == OPT_CODE_ROUTER && r.Next(1)[0] == 4 {
+			ipStr := byteToIpString(r.Next(4))
+			logging.Logger().Info(fmt.Sprintf("Discovery: DHCP Matcher ROUTER: %s", ipStr))
+		}
+
+		if v == OPT_CODE_DNS {
+			len := r.Next(1)[0]
+			var dns []string = make([]string, 0)
+			var ipStr string
+			ipStr = byteToIpString(r.Next(4))
+			dns = append(dns, ipStr)
+			if len == 8 {
+				ipStr = byteToIpString(r.Next(4))
+				dns = append(dns, ipStr)
+			}
+			logging.Logger().Info(fmt.Sprintf("Discovery: DHCP Matcher DNS: %s", dns))
+		}
+
+		if v == OPT_CODE_SERVER_IDENTIFIER && r.Next(1)[0] == 4 {
+			ipStr := byteToIpString(r.Next(4))
+			logging.Logger().Info(fmt.Sprintf("Discovery: DHCP Matcher DHCP SERVER: %s", ipStr))
+		}
+	}
+	logging.Logger().Sync()
+
+}
+
+func byteToIpString(b []byte) string {
+	var ipStr string
+	len := len(b)
+	for i := 0; i < len; i++ {
+		v := b[i]
+		ipStr += fmt.Sprintf("%d", v)
+		if i < len-1 {
+			ipStr += "."
+		}
+	}
+
+	return ipStr
+}

service/matcher/dhcp/dhcp_test.go

@@ -0,0 +1,9 @@
+package dhcp
+
+import (
+	"testing"
+)
+
+func TestDHCP(t *testing.T) {
+
+}