135 lines
3.8 KiB
Go
135 lines
3.8 KiB
Go
// Network utility functions.
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package netutils
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import (
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"crypto/rand"
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"encoding/hex"
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"errors"
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"fmt"
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"io"
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"net"
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"github.com/docker/libnetwork/types"
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)
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var (
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// ErrNetworkOverlapsWithNameservers preformatted error
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ErrNetworkOverlapsWithNameservers = errors.New("requested network overlaps with nameserver")
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// ErrNetworkOverlaps preformatted error
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ErrNetworkOverlaps = errors.New("requested network overlaps with existing network")
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// ErrNoDefaultRoute preformatted error
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ErrNoDefaultRoute = errors.New("no default route")
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)
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// CheckNameserverOverlaps checks whether the passed network overlaps with any of the nameservers
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func CheckNameserverOverlaps(nameservers []string, toCheck *net.IPNet) error {
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if len(nameservers) > 0 {
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for _, ns := range nameservers {
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_, nsNetwork, err := net.ParseCIDR(ns)
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if err != nil {
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return err
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}
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if NetworkOverlaps(toCheck, nsNetwork) {
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return ErrNetworkOverlapsWithNameservers
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}
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}
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}
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return nil
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}
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// NetworkOverlaps detects overlap between one IPNet and another
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func NetworkOverlaps(netX *net.IPNet, netY *net.IPNet) bool {
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return netX.Contains(netY.IP) || netY.Contains(netX.IP)
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}
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// NetworkRange calculates the first and last IP addresses in an IPNet
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func NetworkRange(network *net.IPNet) (net.IP, net.IP) {
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if network == nil {
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return nil, nil
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}
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firstIP := network.IP.Mask(network.Mask)
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lastIP := types.GetIPCopy(firstIP)
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for i := 0; i < len(firstIP); i++ {
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lastIP[i] = firstIP[i] | ^network.Mask[i]
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}
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if network.IP.To4() != nil {
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firstIP = firstIP.To4()
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lastIP = lastIP.To4()
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}
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return firstIP, lastIP
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}
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// GetIfaceAddr returns the first IPv4 address and slice of IPv6 addresses for the specified network interface
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func GetIfaceAddr(name string) (net.Addr, []net.Addr, error) {
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iface, err := net.InterfaceByName(name)
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if err != nil {
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return nil, nil, err
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}
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addrs, err := iface.Addrs()
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if err != nil {
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return nil, nil, err
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}
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var addrs4 []net.Addr
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var addrs6 []net.Addr
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for _, addr := range addrs {
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ip := (addr.(*net.IPNet)).IP
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if ip4 := ip.To4(); ip4 != nil {
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addrs4 = append(addrs4, addr)
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} else if ip6 := ip.To16(); len(ip6) == net.IPv6len {
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addrs6 = append(addrs6, addr)
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}
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}
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switch {
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case len(addrs4) == 0:
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return nil, nil, fmt.Errorf("Interface %v has no IPv4 addresses", name)
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case len(addrs4) > 1:
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fmt.Printf("Interface %v has more than 1 IPv4 address. Defaulting to using %v\n",
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name, (addrs4[0].(*net.IPNet)).IP)
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}
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return addrs4[0], addrs6, nil
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}
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func genMAC(ip net.IP) net.HardwareAddr {
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hw := make(net.HardwareAddr, 6)
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// The first byte of the MAC address has to comply with these rules:
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// 1. Unicast: Set the least-significant bit to 0.
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// 2. Address is locally administered: Set the second-least-significant bit (U/L) to 1.
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hw[0] = 0x02
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// The first 24 bits of the MAC represent the Organizationally Unique Identifier (OUI).
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// Since this address is locally administered, we can do whatever we want as long as
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// it doesn't conflict with other addresses.
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hw[1] = 0x42
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// Fill the remaining 4 bytes based on the input
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if ip == nil {
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rand.Read(hw[2:])
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} else {
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copy(hw[2:], ip.To4())
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}
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return hw
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}
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// GenerateRandomMAC returns a new 6-byte(48-bit) hardware address (MAC)
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func GenerateRandomMAC() net.HardwareAddr {
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return genMAC(nil)
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}
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// GenerateMACFromIP returns a locally administered MAC address where the 4 least
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// significant bytes are derived from the IPv4 address.
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func GenerateMACFromIP(ip net.IP) net.HardwareAddr {
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return genMAC(ip)
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}
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// GenerateRandomName returns a new name joined with a prefix. This size
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// specified is used to truncate the randomly generated value
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func GenerateRandomName(prefix string, size int) (string, error) {
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id := make([]byte, 32)
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if _, err := io.ReadFull(rand.Reader, id); err != nil {
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return "", err
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}
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return prefix + hex.EncodeToString(id)[:size], nil
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}
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