nebula/calculated_remote.go

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package nebula
import (
"fmt"
"math"
"net"
"strconv"
"github.com/slackhq/nebula/cidr"
"github.com/slackhq/nebula/config"
"github.com/slackhq/nebula/iputil"
)
// This allows us to "guess" what the remote might be for a host while we wait
// for the lighthouse response. See "lighthouse.calculated_remotes" in the
// example config file.
type calculatedRemote struct {
ipNet net.IPNet
maskIP iputil.VpnIp
mask iputil.VpnIp
port uint32
}
func newCalculatedRemote(ipNet *net.IPNet, port int) (*calculatedRemote, error) {
// Ensure this is an IPv4 mask that we expect
ones, bits := ipNet.Mask.Size()
if ones == 0 || bits != 32 {
return nil, fmt.Errorf("invalid mask: %v", ipNet)
}
if port < 0 || port > math.MaxUint16 {
return nil, fmt.Errorf("invalid port: %d", port)
}
return &calculatedRemote{
ipNet: *ipNet,
maskIP: iputil.Ip2VpnIp(ipNet.IP),
mask: iputil.Ip2VpnIp(ipNet.Mask),
port: uint32(port),
}, nil
}
func (c *calculatedRemote) String() string {
return fmt.Sprintf("CalculatedRemote(mask=%v port=%d)", c.ipNet, c.port)
}
func (c *calculatedRemote) Apply(ip iputil.VpnIp) *Ip4AndPort {
// Combine the masked bytes of the "mask" IP with the unmasked bytes
// of the overlay IP
masked := (c.maskIP & c.mask) | (ip & ^c.mask)
return &Ip4AndPort{Ip: uint32(masked), Port: c.port}
}
func NewCalculatedRemotesFromConfig(c *config.C, k string) (*cidr.Tree4, error) {
value := c.Get(k)
if value == nil {
return nil, nil
}
calculatedRemotes := cidr.NewTree4()
rawMap, ok := value.(map[any]any)
if !ok {
return nil, fmt.Errorf("config `%s` has invalid type: %T", k, value)
}
for rawKey, rawValue := range rawMap {
rawCIDR, ok := rawKey.(string)
if !ok {
return nil, fmt.Errorf("config `%s` has invalid key (type %T): %v", k, rawKey, rawKey)
}
_, ipNet, err := net.ParseCIDR(rawCIDR)
if err != nil {
return nil, fmt.Errorf("config `%s` has invalid CIDR: %s", k, rawCIDR)
}
entry, err := newCalculatedRemotesListFromConfig(rawValue)
if err != nil {
return nil, fmt.Errorf("config '%s.%s': %w", k, rawCIDR, err)
}
calculatedRemotes.AddCIDR(ipNet, entry)
}
return calculatedRemotes, nil
}
func newCalculatedRemotesListFromConfig(raw any) ([]*calculatedRemote, error) {
rawList, ok := raw.([]any)
if !ok {
return nil, fmt.Errorf("calculated_remotes entry has invalid type: %T", raw)
}
var l []*calculatedRemote
for _, e := range rawList {
c, err := newCalculatedRemotesEntryFromConfig(e)
if err != nil {
return nil, fmt.Errorf("calculated_remotes entry: %w", err)
}
l = append(l, c)
}
return l, nil
}
func newCalculatedRemotesEntryFromConfig(raw any) (*calculatedRemote, error) {
rawMap, ok := raw.(map[any]any)
if !ok {
return nil, fmt.Errorf("invalid type: %T", raw)
}
rawValue := rawMap["mask"]
if rawValue == nil {
return nil, fmt.Errorf("missing mask: %v", rawMap)
}
rawMask, ok := rawValue.(string)
if !ok {
return nil, fmt.Errorf("invalid mask (type %T): %v", rawValue, rawValue)
}
_, ipNet, err := net.ParseCIDR(rawMask)
if err != nil {
return nil, fmt.Errorf("invalid mask: %s", rawMask)
}
var port int
rawValue = rawMap["port"]
if rawValue == nil {
return nil, fmt.Errorf("missing port: %v", rawMap)
}
switch v := rawValue.(type) {
case int:
port = v
case string:
port, err = strconv.Atoi(v)
if err != nil {
return nil, fmt.Errorf("invalid port: %s: %w", v, err)
}
default:
return nil, fmt.Errorf("invalid port (type %T): %v", rawValue, rawValue)
}
return newCalculatedRemote(ipNet, port)
}