update: 允许参数后置

main.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"log"
 	"os"
+	"strings"
 	"time"
 
 	"github.com/xgadget-lab/nexttrace/ipgeo"
@@ -14,31 +15,47 @@ import (
 	"github.com/xgadget-lab/nexttrace/util"
 )
 
-var tcpSYNFlag = flag.Bool("T", false, "Use TCP SYN for tracerouting (default port is 80)")
-var udpPackageFlag = flag.Bool("U", false, "Use UDP Package for tracerouting (default port is 53 in UDP)")
-var port = flag.Int("p", 80, "Set SYN Traceroute Port")
-var numMeasurements = flag.Int("q", 3, "Set the number of probes per each hop.")
-var parallelRequests = flag.Int("r", 18, "Set ParallelRequests number. It should be 1 when there is a multi-routing.")
-var maxHops = flag.Int("m", 30, "Set the max number of hops (max TTL to be reached).")
-var dataOrigin = flag.String("d", "LeoMoeAPI", "Choose IP Geograph Data Provider [LeoMoeAPI, IP.SB, IPInfo, IPInsight]")
-var rdnsenable = flag.Bool("rdns", false, "Set whether rDNS will be display")
-var routePath = flag.Bool("report", false, "Route Path")
-var realtimePrint = flag.Bool("realtime", false, "Output trace results in runtime")
-var tablePrint = flag.Bool("table", false, "Output trace results as table")
-var ver = flag.Bool("V", false, "Check Version")
+var fSet = flag.NewFlagSet("", flag.ExitOnError)
+var tcpSYNFlag = fSet.Bool("T", false, "Use TCP SYN for tracerouting (default port is 80)")
+var udpPackageFlag = fSet.Bool("U", false, "Use UDP Package for tracerouting (default port is 53 in UDP)")
+var port = fSet.Int("p", -1, "Set SYN Traceroute Port")
+var numMeasurements = fSet.Int("q", 3, "Set the number of probes per each hop.")
+var parallelRequests = fSet.Int("r", 18, "Set ParallelRequests number. It should be 1 when there is a multi-routing.")
+var maxHops = fSet.Int("m", 30, "Set the max number of hops (max TTL to be reached).")
+var dataOrigin = fSet.String("d", "LeoMoeAPI", "Choose IP Geograph Data Provider [LeoMoeAPI, IP.SB, IPInfo, IPInsight]")
+var rdnsenable = fSet.Bool("rdns", false, "Set whether rDNS will be display")
+var routePath = fSet.Bool("report", false, "Route Path")
+var realtimePrint = fSet.Bool("realtime", false, "Output trace results in runtime")
+var tablePrint = fSet.Bool("table", false, "Output trace results as table")
+var ver = fSet.Bool("V", false, "Check Version")
+
+func printArgHelp() {
+	fmt.Println("\nArgs Error\nUsage : 'nexttrace [option...] <hostname>' or 'nexttrace <hostname> [option...]'")
+	fSet.PrintDefaults()
+	os.Exit(2)
+}
 
 func flagApply() string {
-	flag.Parse()
 	printer.Version()
+
+	target := ""
+	if len(os.Args) < 2 {
+		printArgHelp()
+	}
+	if !strings.HasPrefix(os.Args[1], "-") {
+		target = os.Args[1]
+		fSet.Parse(os.Args[2:])
+	} else {
+		fSet.Parse(os.Args[1:])
+		target = fSet.Arg(0)
+	}
 	if *ver {
 		os.Exit(0)
 	}
-	ipArg := flag.Args()
-	if flag.NArg() != 1 {
-		fmt.Println("Args Error\nUsage : nexttrace [-VTU] [-d DATAORIGIN.STR ] [ -m TTL ] [ -p PORT ] [ -q PROBES.COUNT ] [ -r PARALLELREQUESTS.COUNT ] [-rdns] [ -realtime | -table ] -report HOSTNAME")
-		os.Exit(2)
+	if target == "" {
+		printArgHelp()
 	}
-	return ipArg[0]
+	return target
 }
 
 func main() {