first commit

util/util.go

@@ -0,0 +1,135 @@
+package util
+
+import (
+	"errors"
+	"io/ioutil"
+	"net"
+	"os"
+	"regexp"
+)
+
+var (
+	RegexpEmail = regexp.MustCompile("^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$")
+	// pushed build time
+	Version string
+)
+
+// 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
+}