utils_linux.go 2.3 KB

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  1. //go:build linux
  2. // Network utility functions.
  3. package netutils
  4. import (
  5. "net"
  6. "os"
  7. "github.com/docker/docker/libnetwork/ns"
  8. "github.com/docker/docker/libnetwork/resolvconf"
  9. "github.com/docker/docker/libnetwork/types"
  10. "github.com/pkg/errors"
  11. "github.com/vishvananda/netlink"
  12. )
  13. var networkGetRoutesFct func(netlink.Link, int) ([]netlink.Route, error)
  14. // CheckRouteOverlaps checks whether the passed network overlaps with any existing routes
  15. func CheckRouteOverlaps(toCheck *net.IPNet) error {
  16. networkGetRoutesFct := networkGetRoutesFct
  17. if networkGetRoutesFct == nil {
  18. networkGetRoutesFct = ns.NlHandle().RouteList
  19. }
  20. networks, err := networkGetRoutesFct(nil, netlink.FAMILY_V4)
  21. if err != nil {
  22. return err
  23. }
  24. for _, network := range networks {
  25. if network.Dst != nil && network.Scope == netlink.SCOPE_LINK && NetworkOverlaps(toCheck, network.Dst) {
  26. return ErrNetworkOverlaps
  27. }
  28. }
  29. return nil
  30. }
  31. // GenerateIfaceName returns an interface name using the passed in
  32. // prefix and the length of random bytes. The api ensures that the
  33. // there are is no interface which exists with that name.
  34. func GenerateIfaceName(nlh *netlink.Handle, prefix string, len int) (string, error) {
  35. linkByName := netlink.LinkByName
  36. if nlh != nil {
  37. linkByName = nlh.LinkByName
  38. }
  39. for i := 0; i < 3; i++ {
  40. name, err := GenerateRandomName(prefix, len)
  41. if err != nil {
  42. return "", err
  43. }
  44. _, err = linkByName(name)
  45. if err != nil {
  46. if errors.As(err, &netlink.LinkNotFoundError{}) {
  47. return name, nil
  48. }
  49. return "", err
  50. }
  51. }
  52. return "", types.InternalErrorf("could not generate interface name")
  53. }
  54. // FindAvailableNetwork returns a network from the passed list which does not
  55. // overlap with existing interfaces in the system
  56. func FindAvailableNetwork(list []*net.IPNet) (*net.IPNet, error) {
  57. // We don't check for an error here, because we don't really care if we
  58. // can't read /etc/resolv.conf. So instead we skip the append if resolvConf
  59. // is nil. It either doesn't exist, or we can't read it for some reason.
  60. var nameservers []string
  61. if rc, err := os.ReadFile(resolvconf.Path()); err == nil {
  62. nameservers = resolvconf.GetNameserversAsCIDR(rc)
  63. }
  64. for _, nw := range list {
  65. if err := CheckNameserverOverlaps(nameservers, nw); err == nil {
  66. if err := CheckRouteOverlaps(nw); err == nil {
  67. return nw, nil
  68. }
  69. }
  70. }
  71. return nil, errors.New("no available network")
  72. }