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- //go:build linux
- // Network utility functions.
- package netutils
- import (
- "net"
- "os"
- "github.com/docker/docker/libnetwork/ns"
- "github.com/docker/docker/libnetwork/resolvconf"
- "github.com/docker/docker/libnetwork/types"
- "github.com/pkg/errors"
- "github.com/vishvananda/netlink"
- )
- var networkGetRoutesFct func(netlink.Link, int) ([]netlink.Route, error)
- // CheckRouteOverlaps checks whether the passed network overlaps with any existing routes
- func CheckRouteOverlaps(toCheck *net.IPNet) error {
- networkGetRoutesFct := networkGetRoutesFct
- if networkGetRoutesFct == nil {
- networkGetRoutesFct = ns.NlHandle().RouteList
- }
- networks, err := networkGetRoutesFct(nil, netlink.FAMILY_V4)
- if err != nil {
- return err
- }
- for _, network := range networks {
- if network.Dst != nil && network.Scope == netlink.SCOPE_LINK && NetworkOverlaps(toCheck, network.Dst) {
- return ErrNetworkOverlaps
- }
- }
- return nil
- }
- // GenerateIfaceName returns an interface name using the passed in
- // prefix and the length of random bytes. The api ensures that the
- // there are is no interface which exists with that name.
- func GenerateIfaceName(nlh *netlink.Handle, prefix string, len int) (string, error) {
- linkByName := netlink.LinkByName
- if nlh != nil {
- linkByName = nlh.LinkByName
- }
- for i := 0; i < 3; i++ {
- name, err := GenerateRandomName(prefix, len)
- if err != nil {
- return "", err
- }
- _, err = linkByName(name)
- if err != nil {
- if errors.As(err, &netlink.LinkNotFoundError{}) {
- return name, nil
- }
- return "", err
- }
- }
- return "", types.InternalErrorf("could not generate interface name")
- }
- // FindAvailableNetwork returns a network from the passed list which does not
- // overlap with existing interfaces in the system
- func FindAvailableNetwork(list []*net.IPNet) (*net.IPNet, error) {
- // We don't check for an error here, because we don't really care if we
- // can't read /etc/resolv.conf. So instead we skip the append if resolvConf
- // is nil. It either doesn't exist, or we can't read it for some reason.
- var nameservers []string
- if rc, err := os.ReadFile(resolvconf.Path()); err == nil {
- nameservers = resolvconf.GetNameserversAsCIDR(rc)
- }
- for _, nw := range list {
- if err := CheckNameserverOverlaps(nameservers, nw); err == nil {
- if err := CheckRouteOverlaps(nw); err == nil {
- return nw, nil
- }
- }
- }
- return nil, errors.New("no available network")
- }
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