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package libvirt
import (
"crypto/rand"
"fmt"
"net"
)
const (
maxIfaceNum = 100
)
func RandomMACAddress() (string, error) {
buf := make([]byte, 6)
_, err := rand.Read(buf)
if err != nil {
return "", err
}
// set local bit and unicast
buf[0] = (buf[0] | 2) & 0xfe
// Set the local bit
buf[0] |= 2
// avoid libvirt-reserved addresses
if buf[0] == 0xfe {
buf[0] = 0xee
}
return fmt.Sprintf("%02x:%02x:%02x:%02x:%02x:%02x",
buf[0], buf[1], buf[2], buf[3], buf[4], buf[5]), nil
}
func FreeNetworkInterface(basename string) (string, error) {
for i := 0; i < maxIfaceNum; i++ {
ifaceName := fmt.Sprintf("%s%d", basename, i)
_, err := net.InterfaceByName(ifaceName)
if err != nil {
return ifaceName, nil
}
}
return "", fmt.Errorf("could not obtain a free network interface")
}
// Calculates the first and last IP addresses in an IPNet
func NetworkRange(network *net.IPNet) (net.IP, net.IP) {
netIP := network.IP.To4()
lastIP := net.IPv4(0, 0, 0, 0).To4()
if netIP == nil {
netIP = network.IP.To16()
lastIP = net.IPv6zero.To16()
}
firstIP := netIP.Mask(network.Mask)
for i := 0; i < len(lastIP); i++ {
lastIP[i] = netIP[i] | ^network.Mask[i]
}
return firstIP, lastIP
}
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