package util import ( "errors" "io/ioutil" "net" "os" "regexp" ) var ( RegexpEmail = regexp.MustCompile("^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$") ) // ReadFile file content func ReadFile(path string) (bytes []byte, err error) { bytes, err = ioutil.ReadFile(path) if err != nil { return nil, err } return bytes, nil } // WriteFile content to file func WriteFile(path string, bytes []byte) (err error) { err = ioutil.WriteFile(path, bytes, 0644) if err != nil { return err } return nil } // FileExists check if file exists func FileExists(name string) bool { info, err := os.Stat(name) if os.IsNotExist(err) { return false } return !info.IsDir() } // DirectoryExists check if directory exists func DirectoryExists(name string) bool { info, err := os.Stat(name) if os.IsNotExist(err) { return false } return info.IsDir() } // GetAvailableIp search for an available in cidr against a list of reserved ips func GetAvailableIp(cidr string, reserved []string) (string, error) { ip, ipnet, err := net.ParseCIDR(cidr) if err != nil { return "", err } // this two addresses are not usable broadcastAddr := BroadcastAddr(ipnet).String() networkAddr := ipnet.IP.String() for ip := ip.Mask(ipnet.Mask); ipnet.Contains(ip); inc(ip) { ok := true address := ip.String() for _, r := range reserved { if address == r { ok = false break } } if ok && address != networkAddr && address != broadcastAddr { return address, nil } } return "", errors.New("no more available address from cidr") } // IsIPv6 check if given ip is IPv6 func IsIPv6(address string) bool { ip := net.ParseIP(address) if ip == nil { return false } return ip.To4() == nil } // IsValidIp check if ip is valid func IsValidIp(ip string) bool { return net.ParseIP(ip) != nil } // IsValidCidr check if CIDR is valid func IsValidCidr(cidr string) bool { _, _, err := net.ParseCIDR(cidr) return err == nil } // GetIpFromCidr get ip from cidr func GetIpFromCidr(cidr string) (string, error) { ip, _, err := net.ParseCIDR(cidr) if err != nil { return "", err } return ip.String(), nil } // http://play.golang.org/p/m8TNTtygK0 func inc(ip net.IP) { for j := len(ip) - 1; j >= 0; j-- { ip[j]++ if ip[j] > 0 { break } } } // BroadcastAddr returns the last address in the given network, or the broadcast address. func BroadcastAddr(n *net.IPNet) net.IP { // The golang net package doesn't make it easy to calculate the broadcast address. :( var broadcast net.IP if len(n.IP) == 4 { broadcast = net.ParseIP("0.0.0.0").To4() } else { broadcast = net.ParseIP("::") } for i := 0; i < len(n.IP); i++ { broadcast[i] = n.IP[i] | ^n.Mask[i] } return broadcast }