增加对多MPLS情景的支持，支持通过ENV或参数禁用MPLS功能

要提交的变更：
	修改：     cmd/cmd.go
	修改：     printer/basic.go
	修改：     printer/printer.go
	修改：     printer/realtime_printer.go
	修改：     trace/icmp_ipv4.go
	修改：     trace/icmp_ipv6.go
	修改：     trace/trace.go
	修改：     util/util.go

trace/icmp_ipv4.go

@@ -30,6 +30,8 @@ type ICMPTracer struct {
 	fetchLock             sync.Mutex
 }
 
+var psize = 52
+
 func (t *ICMPTracer) PrintFunc() {
 	defer t.wg.Done()
 	var ttl = t.Config.BeginHop - 1
@@ -118,6 +120,7 @@ func (t *ICMPTracer) Execute() (*Result, error) {
 
 func (t *ICMPTracer) listenICMP() {
 	lc := NewPacketListener(t.icmpListen, t.ctx)
+	psize = t.Config.PktSize
 	go lc.Start()
 	for {
 		select {
@@ -186,45 +189,6 @@ func (t *ICMPTracer) handleICMPMessage(msg ReceivedMessage, icmpType int8, data
 	}
 }
 
-func extractMPLS(msg ReceivedMessage, data []byte) string {
-	extensionOffset := 20 + 8 + 52
-
-	if len(data) <= extensionOffset {
-		return ""
-	}
-
-	extensionBody := data[extensionOffset:]
-	if len(extensionBody) < 8 || len(extensionBody)%8 != 0 {
-		return ""
-	}
-
-	tmp := fmt.Sprintf("%x", msg.Msg[:*msg.N])
-	if len(tmp) < 8 {
-		return ""
-	}
-
-	label, err := strconv.ParseInt(tmp[len(tmp)-8:len(tmp)-3], 16, 32)
-	if err != nil {
-		return ""
-	}
-
-	strSlice := []byte(tmp[len(tmp)-3 : len(tmp)-2])
-	charValue := int(strSlice[0] - '0')
-	binaryStr := fmt.Sprintf("%04b", charValue)
-	tc, err := strconv.ParseInt(binaryStr[:3], 2, 32)
-	if err != nil {
-		return ""
-	}
-	s := binaryStr[3:]
-
-	ttlMpls, err := strconv.ParseInt(tmp[len(tmp)-2:], 16, 32)
-	if err != nil {
-		return ""
-	}
-
-	return fmt.Sprintf("Lbl %d, TC %d, S %s, TTL %d", label, tc, s, ttlMpls)
-}
-
 func gernerateID(ttl_int int) int {
 	const ID_FIXED_HEADER = "10"
 	var processID = fmt.Sprintf("%07b", os.Getpid()&0x7f) //取进程ID的前7位
@@ -298,7 +262,7 @@ func (t *ICMPTracer) send(ttl int) error {
 		Body: &icmp.Echo{
 			ID: id,
 			//Data: []byte("HELLO-R-U-THERE"),
-			Data: bytes.Repeat([]byte{1}, t.Config.PktSize),
+			Data: append(bytes.Repeat([]byte{1}, t.Config.PktSize-4), 0x00, 0x00, 0x4f, 0xff),
 			Seq:  ttl,
 		},
 	}

trace/icmp_ipv6.go

@@ -137,6 +137,7 @@ func (t *ICMPTracerv6) Execute() (*Result, error) {
 
 func (t *ICMPTracerv6) listenICMP() {
 	lc := NewPacketListener(t.icmpListen, t.ctx)
+	psize = t.Config.PktSize
 	go lc.Start()
 	for {
 		select {
@@ -256,7 +257,7 @@ func (t *ICMPTracerv6) send(ttl int) error {
 		Body: &icmp.Echo{
 			ID: id,
 			//Data: []byte("HELLO-R-U-THERE"),
-			Data: bytes.Repeat([]byte{1}, t.Config.PktSize),
+			Data: append(bytes.Repeat([]byte{1}, t.Config.PktSize-4), 0x00, 0x00, 0x4f, 0xff),
 			Seq:  ttl,
 		},
 	}

trace/trace.go

@@ -2,7 +2,10 @@ package trace
 
 import (
 	"errors"
+	"fmt"
 	"net"
+	"strconv"
+	"strings"
 	"sync"
 	"time"
 
@@ -124,7 +127,7 @@ type Hop struct {
 	Error    error
 	Geo      *ipgeo.IPGeoData
 	Lang     string
-	MPLS     string
+	MPLS     []string
 }
 
 func (h *Hop) fetchIPData(c Config) (err error) {
@@ -226,3 +229,108 @@ func (h *Hop) fetchIPData(c Config) (err error) {
 
 	return
 }
+
+func extractMPLS(msg ReceivedMessage, data []byte) []string {
+	if util.DisableMPLS != "" {
+		return nil
+	}
+
+	if psize != 52 {
+		return nil
+	}
+
+	extensionOffset := 20 + 8 + psize
+
+	if len(data) <= extensionOffset {
+		return nil
+	}
+
+	extensionBody := data[extensionOffset:]
+	if len(extensionBody) < 8 || len(extensionBody)%8 != 0 {
+		return nil
+	}
+
+	tmp := fmt.Sprintf("%x", msg.Msg[:*msg.N])
+
+	index := strings.Index(tmp, strings.Repeat("01", psize-4)+"00004fff")
+	if index == -1 {
+		return nil
+	}
+	tmp = tmp[index+psize*2:]
+	//由于限制长度了
+	index1 := strings.Index(tmp, "00002000")
+	l := len(tmp[index1+4:])/8 - 2
+	//fmt.Printf("l:%d\n", l)
+
+	if l < 1 {
+		return nil
+	}
+	//去掉扩展头和MPLS头
+	tmp = tmp[index1+4+8*2:]
+	//fmt.Print(tmp)
+
+	var retStrList []string
+	for i := 0; i < l; i++ {
+		label, err := strconv.ParseInt(tmp[i*8+0:i*8+5], 16, 32)
+		if err != nil {
+			return nil
+		}
+
+		strSlice := fmt.Sprintf("%s", []byte(tmp[i*8+5:i*8+6]))
+		//fmt.Printf("\nstrSlice: %s\n", strSlice)
+
+		num, err := strconv.ParseUint(strSlice, 16, 64)
+		if err != nil {
+			return nil
+		}
+		binaryStr := fmt.Sprintf("%04s", strconv.FormatUint(num, 2))
+
+		//fmt.Printf("\nbinaryStr: %s\n", binaryStr)
+		tc, err := strconv.ParseInt(binaryStr[:3], 2, 32)
+		if err != nil {
+			return nil
+		}
+		s := binaryStr[3:]
+
+		ttlMpls, err := strconv.ParseInt(tmp[i*8+6:i*8+8], 16, 32)
+		if err != nil {
+			return nil
+		}
+
+		//if i > 0 {
+		//	retStr += "\n    "
+		//}
+
+		retStrList = append(retStrList, fmt.Sprintf("[MPLS: Lbl %d, TC %d, S %s, TTL %d]", label, tc, s, ttlMpls))
+	}
+
+	//label, err := strconv.ParseInt(tmp[len(tmp)-8:len(tmp)-3], 16, 32)
+	//if err != nil {
+	//	return ""
+	//}
+	//
+	//strSlice := fmt.Sprintf("%s", []byte(tmp[len(tmp)-3:len(tmp)-2]))
+	////fmt.Printf("\nstrSlice: %s\n", strSlice)
+	//
+	//num, err := strconv.ParseUint(strSlice, 16, 64)
+	//if err != nil {
+	//	return ""
+	//}
+	//binaryStr := fmt.Sprintf("%04s", strconv.FormatUint(num, 2))
+	//
+	////fmt.Printf("\nbinaryStr: %s\n", binaryStr)
+	//tc, err := strconv.ParseInt(binaryStr[:3], 2, 32)
+	//if err != nil {
+	//	return ""
+	//}
+	//s := binaryStr[3:]
+	//
+	//ttlMpls, err := strconv.ParseInt(tmp[len(tmp)-2:], 16, 32)
+	//if err != nil {
+	//	return ""
+	//}
+	//
+	//retStr := fmt.Sprintf("Lbl %d, TC %d, S %s, TTL %d", label, tc, s, ttlMpls)
+
+	return retStrList
+}