golang get ip address

getip.go

func getIp() (net.IP, error) {
	interfaces, e := net.Interfaces()
	if e != nil {
		return nil, errors.New("get Interfaces error")
	}
	for _, i := range interfaces {
		// the flags value maybe 'pointtopoint', it also has a ip, filter it.
		if !strings.Contains(i.Flags.String(), "broadcast") {
			continue
		}

		addresses, e := i.Addrs()
		if e != nil {
			return nil, errors.New("get addresses failed")
		}
		for _, add := range addresses {
			var ip net.IP
			switch t := add.(type) {
			case *net.IPNet:
				ip = t.IP
			case *net.IPAddr:
				ip = t.IP
			}
			// filter loopback ip
			if !ip.IsLoopback() && ip.To4() != nil {
				// return the first occurrence ip
				return ip, nil
			}
		}
	}

	return nil, errors.New("find none ip")
}