headscale/utils.go
2022-05-16 20:30:43 +02:00

333 lines
7.7 KiB
Go

// Codehere is mostly taken from github.com/tailscale/tailscale
// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package headscale
import (
"context"
"crypto/rand"
"encoding/base64"
"encoding/json"
"fmt"
"net"
"strings"
"github.com/rs/zerolog/log"
"inet.af/netaddr"
"tailscale.com/tailcfg"
"tailscale.com/types/key"
)
const (
errCannotDecryptReponse = Error("cannot decrypt response")
errCouldNotAllocateIP = Error("could not find any suitable IP")
// These constants are copied from the upstream tailscale.com/types/key
// library, because they are not exported.
// https://github.com/tailscale/tailscale/tree/main/types/key
// nodePublicHexPrefix is the prefix used to identify a
// hex-encoded node public key.
//
// This prefix is used in the control protocol, so cannot be
// changed.
nodePublicHexPrefix = "nodekey:"
// machinePublicHexPrefix is the prefix used to identify a
// hex-encoded machine public key.
//
// This prefix is used in the control protocol, so cannot be
// changed.
machinePublicHexPrefix = "mkey:"
// discoPublicHexPrefix is the prefix used to identify a
// hex-encoded disco public key.
//
// This prefix is used in the control protocol, so cannot be
// changed.
discoPublicHexPrefix = "discokey:"
// privateKey prefix.
privateHexPrefix = "privkey:"
)
func MachinePublicKeyStripPrefix(machineKey key.MachinePublic) string {
return strings.TrimPrefix(machineKey.String(), machinePublicHexPrefix)
}
func NodePublicKeyStripPrefix(nodeKey key.NodePublic) string {
return strings.TrimPrefix(nodeKey.String(), nodePublicHexPrefix)
}
func DiscoPublicKeyStripPrefix(discoKey key.DiscoPublic) string {
return strings.TrimPrefix(discoKey.String(), discoPublicHexPrefix)
}
func MachinePublicKeyEnsurePrefix(machineKey string) string {
if !strings.HasPrefix(machineKey, machinePublicHexPrefix) {
return machinePublicHexPrefix + machineKey
}
return machineKey
}
func NodePublicKeyEnsurePrefix(nodeKey string) string {
if !strings.HasPrefix(nodeKey, nodePublicHexPrefix) {
return nodePublicHexPrefix + nodeKey
}
return nodeKey
}
func DiscoPublicKeyEnsurePrefix(discoKey string) string {
if !strings.HasPrefix(discoKey, discoPublicHexPrefix) {
return discoPublicHexPrefix + discoKey
}
return discoKey
}
func PrivateKeyEnsurePrefix(privateKey string) string {
if !strings.HasPrefix(privateKey, privateHexPrefix) {
return privateHexPrefix + privateKey
}
return privateKey
}
// Error is used to compare errors as per https://dave.cheney.net/2016/04/07/constant-errors
type Error string
func (e Error) Error() string { return string(e) }
func decode(
msg []byte,
output interface{},
pubKey *key.MachinePublic,
privKey *key.MachinePrivate,
) error {
log.Trace().Int("length", len(msg)).Msg("Trying to decrypt")
decrypted, ok := privKey.OpenFrom(*pubKey, msg)
if !ok {
return errCannotDecryptReponse
}
if err := json.Unmarshal(decrypted, output); err != nil {
return err
}
return nil
}
func encode(
v interface{},
pubKey *key.MachinePublic,
privKey *key.MachinePrivate,
) ([]byte, error) {
b, err := json.Marshal(v)
if err != nil {
return nil, err
}
return privKey.SealTo(*pubKey, b), nil
}
func (h *Headscale) getAvailableIPs() (ips MachineAddresses, err error) {
ipPrefixes := h.cfg.IPPrefixes
for _, ipPrefix := range ipPrefixes {
var ip *netaddr.IP
ip, err = h.getAvailableIP(ipPrefix)
if err != nil {
return
}
ips = append(ips, *ip)
}
return
}
func GetIPPrefixEndpoints(na netaddr.IPPrefix) (network, broadcast netaddr.IP) {
ipRange := na.Range()
network = ipRange.From()
broadcast = ipRange.To()
return
}
func (h *Headscale) getAvailableIP(ipPrefix netaddr.IPPrefix) (*netaddr.IP, error) {
usedIps, err := h.getUsedIPs()
if err != nil {
return nil, err
}
ipPrefixNetworkAddress, ipPrefixBroadcastAddress := GetIPPrefixEndpoints(ipPrefix)
// Get the first IP in our prefix
ip := ipPrefixNetworkAddress.Next()
for {
if !ipPrefix.Contains(ip) {
return nil, errCouldNotAllocateIP
}
switch {
case ip.Compare(ipPrefixBroadcastAddress) == 0:
fallthrough
case usedIps.Contains(ip):
fallthrough
case ip.IsZero() || ip.IsLoopback():
ip = ip.Next()
continue
default:
return &ip, nil
}
}
}
func (h *Headscale) getUsedIPs() (*netaddr.IPSet, error) {
// FIXME: This really deserves a better data model,
// but this was quick to get running and it should be enough
// to begin experimenting with a dual stack tailnet.
var addressesSlices []string
h.db.Model(&Machine{}).Pluck("ip_addresses", &addressesSlices)
var ips netaddr.IPSetBuilder
for _, slice := range addressesSlices {
var machineAddresses MachineAddresses
err := machineAddresses.Scan(slice)
if err != nil {
return &netaddr.IPSet{}, fmt.Errorf(
"failed to read ip from database: %w",
err,
)
}
for _, ip := range machineAddresses {
ips.Add(ip)
}
}
ipSet, err := ips.IPSet()
if err != nil {
return &netaddr.IPSet{}, fmt.Errorf(
"failed to build IP Set: %w",
err,
)
}
return ipSet, nil
}
func containsString(ss []string, s string) bool {
for _, v := range ss {
if v == s {
return true
}
}
return false
}
func tailNodesToString(nodes []*tailcfg.Node) string {
temp := make([]string, len(nodes))
for index, node := range nodes {
temp[index] = node.Name
}
return fmt.Sprintf("[ %s ](%d)", strings.Join(temp, ", "), len(temp))
}
func tailMapResponseToString(resp tailcfg.MapResponse) string {
return fmt.Sprintf(
"{ Node: %s, Peers: %s }",
resp.Node.Name,
tailNodesToString(resp.Peers),
)
}
func GrpcSocketDialer(ctx context.Context, addr string) (net.Conn, error) {
var d net.Dialer
return d.DialContext(ctx, "unix", addr)
}
func ipPrefixToString(prefixes []netaddr.IPPrefix) []string {
result := make([]string, len(prefixes))
for index, prefix := range prefixes {
result[index] = prefix.String()
}
return result
}
func stringToIPPrefix(prefixes []string) ([]netaddr.IPPrefix, error) {
result := make([]netaddr.IPPrefix, len(prefixes))
for index, prefixStr := range prefixes {
prefix, err := netaddr.ParseIPPrefix(prefixStr)
if err != nil {
return []netaddr.IPPrefix{}, err
}
result[index] = prefix
}
return result, nil
}
func containsIPPrefix(prefixes []netaddr.IPPrefix, prefix netaddr.IPPrefix) bool {
for _, p := range prefixes {
if prefix == p {
return true
}
}
return false
}
// GenerateRandomBytes returns securely generated random bytes.
// It will return an error if the system's secure random
// number generator fails to function correctly, in which
// case the caller should not continue.
func GenerateRandomBytes(n int) ([]byte, error) {
bytes := make([]byte, n)
// Note that err == nil only if we read len(b) bytes.
if _, err := rand.Read(bytes); err != nil {
return nil, err
}
return bytes, nil
}
// GenerateRandomStringURLSafe returns a URL-safe, base64 encoded
// securely generated random string.
// It will return an error if the system's secure random
// number generator fails to function correctly, in which
// case the caller should not continue.
func GenerateRandomStringURLSafe(n int) (string, error) {
b, err := GenerateRandomBytes(n)
return base64.RawURLEncoding.EncodeToString(b), err
}
// GenerateRandomStringDNSSafe returns a DNS-safe
// securely generated random string.
// It will return an error if the system's secure random
// number generator fails to function correctly, in which
// case the caller should not continue.
func GenerateRandomStringDNSSafe(n int) (string, error) {
str, err := GenerateRandomStringURLSafe(n)
str = strings.ReplaceAll(str, "_", "-")
return str[:n], err
}