Extract iputil package

iputil/iputil.go

@@ -0,0 +1,37 @@
+package iputil
+
+import (
+	"fmt"
+	"math/big"
+	"net"
+	"strings"
+	"time"
+)
+
+func LookupAddr(ip net.IP) ([]string, error) {
+	names, err := net.LookupAddr(ip.String())
+	for i, _ := range names {
+		names[i] = strings.TrimRight(names[i], ".") // Always return unrooted name
+	}
+	return names, err
+}
+
+func LookupPort(ip net.IP, port uint64) error {
+	address := fmt.Sprintf("[%s]:%d", ip, port)
+	conn, err := net.DialTimeout("tcp", address, 2*time.Second)
+	if err != nil {
+		return err
+	}
+	defer conn.Close()
+	return nil
+}
+
+func ToDecimal(ip net.IP) *big.Int {
+	i := big.NewInt(0)
+	if to4 := ip.To4(); to4 != nil {
+		i.SetBytes(to4)
+	} else {
+		i.SetBytes(ip)
+	}
+	return i
+}