[Refactor] gvisor support hijack dns list

dns-hijack:
 - 1.1.1.1
 - 8.8.8.8:53
 - tcp://1.1.1.1:53
 - udp://223.5.5.5
 - 10.0.0.1:5353

common/net/tcpip.go

@@ -0,0 +1,46 @@
+package net
+
+import (
+	"fmt"
+	"net"
+	"strings"
+)
+
+func SplitNetworkType(s string) (string, string, error) {
+	var (
+		shecme   string
+		hostPort string
+	)
+	result := strings.Split(s, "://")
+	if len(result) == 2 {
+		shecme = result[0]
+		hostPort = result[1]
+	} else if len(result) == 1 {
+		hostPort = result[0]
+	} else {
+		return "", "", fmt.Errorf("tcp/udp style error")
+	}
+
+	if len(shecme) == 0 {
+		shecme = "udp"
+	}
+
+	if shecme != "tcp" && shecme != "udp" {
+		return "", "", fmt.Errorf("scheme should be tcp:// or udp://")
+	} else {
+		return shecme, hostPort, nil
+	}
+}
+
+func SplitHostPort(s string) (host, port string, hasPort bool, err error) {
+	temp := s
+	hasPort = true
+
+	if !strings.Contains(s, ":") && !strings.Contains(s, "]:") {
+		temp += ":0"
+		hasPort = false
+	}
+
+	host, port, err = net.SplitHostPort(temp)
+	return
+}