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125 lines
3.4 KiB
Go
125 lines
3.4 KiB
Go
// +build linux
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// Network utility functions.
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package netutils
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import (
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"fmt"
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"net"
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"strings"
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"github.com/docker/libnetwork/ipamutils"
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"github.com/docker/libnetwork/ns"
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"github.com/docker/libnetwork/osl"
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"github.com/docker/libnetwork/resolvconf"
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"github.com/docker/libnetwork/types"
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"github.com/vishvananda/netlink"
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)
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var (
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networkGetRoutesFct func(netlink.Link, int) ([]netlink.Route, error)
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)
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// CheckRouteOverlaps checks whether the passed network overlaps with any existing routes
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func CheckRouteOverlaps(toCheck *net.IPNet) error {
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if networkGetRoutesFct == nil {
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networkGetRoutesFct = ns.NlHandle().RouteList
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}
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networks, err := networkGetRoutesFct(nil, netlink.FAMILY_V4)
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if err != nil {
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return err
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}
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for _, network := range networks {
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if network.Dst != nil && NetworkOverlaps(toCheck, network.Dst) {
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return ErrNetworkOverlaps
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}
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}
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return nil
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}
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// GenerateIfaceName returns an interface name using the passed in
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// prefix and the length of random bytes. The api ensures that the
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// there are is no interface which exists with that name.
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func GenerateIfaceName(nlh *netlink.Handle, prefix string, len int) (string, error) {
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linkByName := netlink.LinkByName
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if nlh != nil {
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linkByName = nlh.LinkByName
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}
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for i := 0; i < 3; i++ {
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name, err := GenerateRandomName(prefix, len)
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if err != nil {
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continue
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}
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_, err = linkByName(name)
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if err != nil {
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if strings.Contains(err.Error(), "not found") {
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return name, nil
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}
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return "", err
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}
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}
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return "", types.InternalErrorf("could not generate interface name")
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}
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// ElectInterfaceAddresses looks for an interface on the OS with the
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// specified name and returns its IPv4 and IPv6 addresses in CIDR
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// form. If the interface does not exist, it chooses from a predifined
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// list the first IPv4 address which does not conflict with other
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// interfaces on the system.
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func ElectInterfaceAddresses(name string) (*net.IPNet, []*net.IPNet, error) {
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var (
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v4Net *net.IPNet
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v6Nets []*net.IPNet
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err error
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)
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defer osl.InitOSContext()()
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link, _ := ns.NlHandle().LinkByName(name)
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if link != nil {
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v4addr, err := ns.NlHandle().AddrList(link, netlink.FAMILY_V4)
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if err != nil {
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return nil, nil, err
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}
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v6addr, err := ns.NlHandle().AddrList(link, netlink.FAMILY_V6)
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if err != nil {
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return nil, nil, err
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}
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if len(v4addr) > 0 {
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v4Net = v4addr[0].IPNet
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}
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for _, nlAddr := range v6addr {
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v6Nets = append(v6Nets, nlAddr.IPNet)
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}
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}
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if link == nil || v4Net == nil {
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// Choose from predifined broad networks
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v4Net, err = FindAvailableNetwork(ipamutils.PredefinedBroadNetworks)
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if err != nil {
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return nil, nil, err
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}
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}
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return v4Net, v6Nets, nil
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}
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// FindAvailableNetwork returns a network from the passed list which does not
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// overlap with existing interfaces in the system
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func FindAvailableNetwork(list []*net.IPNet) (*net.IPNet, error) {
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// We don't check for an error here, because we don't really care if we
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// can't read /etc/resolv.conf. So instead we skip the append if resolvConf
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// is nil. It either doesn't exist, or we can't read it for some reason.
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var nameservers []string
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if rc, err := resolvconf.Get(); err == nil {
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nameservers = resolvconf.GetNameserversAsCIDR(rc.Content)
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}
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for _, nw := range list {
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if err := CheckNameserverOverlaps(nameservers, nw); err == nil {
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if err := CheckRouteOverlaps(nw); err == nil {
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return nw, nil
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}
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}
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}
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return nil, fmt.Errorf("no available network")
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}
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