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package main
import (
"encoding/binary"
"fmt"
"math/big"
"net"
"os"
"path"
"strconv"
)
func main() {
cmd := path.Base(os.Args[1])
switch cmd {
case "ip2int":
for _, ip := range os.Args[2:] {
r, err := IPtoInt(ip)
if err != nil {
fmt.Fprintf(os.Stderr, "failed to parse %s to an int: %s", ip, err)
continue
}
fmt.Printf("%s\t%d\n", ip, r)
}
case "int2ip":
for _, ip := range os.Args[2:] {
r, err := IPtoN(ip)
if err != nil {
fmt.Fprintf(os.Stderr, "failed to parse %s to an addresse IP: %s", ip, err)
continue
}
fmt.Printf("%s\t%s", ip, r)
}
default:
fmt.Printf("`%s' is not a supported command", cmd)
os.Exit(1)
}
}
func IPtoInt(ip string) (*big.Int, error) {
i := net.ParseIP(ip)
if len(i.To4()) == 4 {
return big.NewInt(0).SetBytes(i.To4()), nil
} else {
return nil, fmt.Errorf("%s is not an IPv4 address", ip)
}
}
func IPtoN(ip string) (string, error) {
r, err := strconv.Atoi(ip)
if err != nil {
return "", fmt.Errorf("failed to parse %s to an int: %s", ip, err)
}
newIP := make(net.IP, 4)
binary.BigEndian.PutUint32(newIP, uint32(r))
return newIP.To4().String(), nil
}
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