Files
netbird/client/internal/connect.go
riccardom 9b179be324 Defines an API for knowing if the SERVICE is running (regardless of up and down state)
New() builds s.connecClient and is called when the gRPC service is started.
Up() is invoked only IF a gRPC service IS running which is possible only if the New() was
called.
2026-06-17 23:30:30 +02:00

753 lines
24 KiB
Go

package internal
import (
"context"
"errors"
"fmt"
"net"
"net/netip"
"path/filepath"
"runtime"
"runtime/debug"
"strings"
"sync"
"time"
"github.com/cenkalti/backoff/v4"
log "github.com/sirupsen/logrus"
"golang.zx2c4.com/wireguard/wgctrl/wgtypes"
"google.golang.org/grpc/codes"
"google.golang.org/grpc/metadata"
gstatus "google.golang.org/grpc/status"
"github.com/netbirdio/netbird/client/iface/wgaddr"
"github.com/netbirdio/netbird/client/iface"
"github.com/netbirdio/netbird/client/iface/device"
"github.com/netbirdio/netbird/client/iface/netstack"
"github.com/netbirdio/netbird/client/internal/dns"
"github.com/netbirdio/netbird/client/internal/listener"
"github.com/netbirdio/netbird/client/internal/metrics"
"github.com/netbirdio/netbird/client/internal/peer"
"github.com/netbirdio/netbird/client/internal/profilemanager"
"github.com/netbirdio/netbird/client/internal/statemanager"
"github.com/netbirdio/netbird/client/internal/stdnet"
"github.com/netbirdio/netbird/client/internal/updater"
"github.com/netbirdio/netbird/client/internal/updater/installer"
nbnet "github.com/netbirdio/netbird/client/net"
cProto "github.com/netbirdio/netbird/client/proto"
"github.com/netbirdio/netbird/client/ssh"
sshconfig "github.com/netbirdio/netbird/client/ssh/config"
"github.com/netbirdio/netbird/client/system"
mgm "github.com/netbirdio/netbird/shared/management/client"
mgmProto "github.com/netbirdio/netbird/shared/management/proto"
"github.com/netbirdio/netbird/shared/relay/auth/hmac"
relayClient "github.com/netbirdio/netbird/shared/relay/client"
signal "github.com/netbirdio/netbird/shared/signal/client"
"github.com/netbirdio/netbird/util"
"github.com/netbirdio/netbird/version"
)
// androidRunOverride is set on Android to inject mobile dependencies
// when using embed.Client (which calls Run() with empty MobileDependency).
var androidRunOverride func(c *ConnectClient, config *profilemanager.Config, runningChan chan struct{}, logPath string) error
type ConnectClient struct {
ctx context.Context
statusRecorder *peer.Status
engine *Engine
engineMutex sync.Mutex
clientMetrics *metrics.ClientMetrics
updateManager *updater.Manager
persistSyncResponse bool
// sup serializes all start/stop requests so two lifecycle operations can
// never overlap. See connect_lifecycle.go.
sup *supervisor
}
func NewConnectClient(
ctx context.Context,
statusRecorder *peer.Status,
) *ConnectClient {
c := &ConnectClient{
ctx: ctx,
statusRecorder: statusRecorder,
engineMutex: sync.Mutex{},
}
c.sup = newSupervisor(ctx, c.run)
return c
}
func (c *ConnectClient) SetUpdateManager(um *updater.Manager) {
c.updateManager = um
}
// Run with main logic. md carries optional gRPC metadata (e.g. the UI
// user-agent) to forward to the management/signal services; nil when none.
func (c *ConnectClient) Run(config *profilemanager.Config, md metadata.MD, runningChan chan struct{}, logPath string) error {
if androidRunOverride != nil {
return androidRunOverride(c, config, runningChan, logPath)
}
return c.sup.start(config, md, MobileDependency{}, runningChan, logPath)
}
// RunAsync starts a client run without blocking. done (if non-nil, buffered)
// receives the run's end result. Used by the daemon, which drives the lifecycle
// through the supervisor (Run/Stop/IsRunning) rather than blocking on Run.
func (c *ConnectClient) RunAsync(config *profilemanager.Config, md metadata.MD, runningChan chan struct{}, done chan error) {
c.sup.startAsync(config, md, MobileDependency{}, runningChan, "", done)
}
// RunOnAndroid with main logic on mobile system
func (c *ConnectClient) RunOnAndroid(
config *profilemanager.Config,
tunAdapter device.TunAdapter,
iFaceDiscover stdnet.ExternalIFaceDiscover,
networkChangeListener listener.NetworkChangeListener,
dnsAddresses []netip.AddrPort,
dnsReadyListener dns.ReadyListener,
stateFilePath string,
cacheDir string,
) error {
// in case of non Android os these variables will be nil
mobileDependency := MobileDependency{
TunAdapter: tunAdapter,
IFaceDiscover: iFaceDiscover,
NetworkChangeListener: networkChangeListener,
HostDNSAddresses: dnsAddresses,
DnsReadyListener: dnsReadyListener,
StateFilePath: stateFilePath,
TempDir: cacheDir,
}
return c.sup.start(config, nil, mobileDependency, nil, "")
}
func (c *ConnectClient) RunOniOS(
config *profilemanager.Config,
fileDescriptor int32,
networkChangeListener listener.NetworkChangeListener,
dnsManager dns.IosDnsManager,
stateFilePath string,
) error {
// Set GC percent to 5% to reduce memory usage as iOS only allows 50MB of memory for the extension.
debug.SetGCPercent(5)
mobileDependency := MobileDependency{
FileDescriptor: fileDescriptor,
NetworkChangeListener: networkChangeListener,
DnsManager: dnsManager,
StateFilePath: stateFilePath,
}
return c.sup.start(config, nil, mobileDependency, nil, "")
}
// run executes a single client run. runCtx is owned by the supervisor: cancelling
// it tears the run down (it is the parent of the per-attempt engine context).
func (c *ConnectClient) run(runCtx context.Context, config *profilemanager.Config, mobileDependency MobileDependency, runningChan chan struct{}, logPath string) error {
defer func() {
if r := recover(); r != nil {
rec := c.statusRecorder
if rec != nil {
rec.PublishEvent(
cProto.SystemEvent_CRITICAL, cProto.SystemEvent_SYSTEM,
"panic occurred",
"The Netbird service panicked. Please restart the service and submit a bug report with the client logs.",
nil,
)
}
log.Panicf("Panic occurred: %v, stack trace: %s", r, string(debug.Stack()))
}
}()
// Stop metrics push on exit
defer func() {
if c.clientMetrics != nil {
c.clientMetrics.StopPush()
}
}()
log.Infof("starting NetBird client version %s on %s/%s", version.NetbirdVersion(), runtime.GOOS, runtime.GOARCH)
nbnet.Init()
// Initialize metrics once at startup (always active for debug bundles)
if c.clientMetrics == nil {
agentInfo := metrics.AgentInfo{
DeploymentType: metrics.DeploymentTypeUnknown,
Version: version.NetbirdVersion(),
OS: runtime.GOOS,
Arch: runtime.GOARCH,
}
c.clientMetrics = metrics.NewClientMetrics(agentInfo)
log.Debugf("initialized client metrics")
// Start metrics push if enabled (uses daemon context, persists across engine restarts)
if metrics.IsMetricsPushEnabled() {
c.clientMetrics.StartPush(c.ctx, metrics.PushConfigFromEnv())
}
}
backOff := &backoff.ExponentialBackOff{
InitialInterval: time.Second,
RandomizationFactor: 1,
Multiplier: 1.7,
MaxInterval: 15 * time.Second,
MaxElapsedTime: 3 * 30 * 24 * time.Hour, // 3 months
Stop: backoff.Stop,
Clock: backoff.SystemClock,
}
state := CtxGetState(c.ctx)
defer func() {
s, err := state.Status()
if err != nil || s != StatusNeedsLogin {
state.Set(StatusIdle)
}
}()
wrapErr := state.Wrap
myPrivateKey, err := wgtypes.ParseKey(config.PrivateKey)
if err != nil {
log.Errorf("failed parsing Wireguard key %s: [%s]", config.PrivateKey, err.Error())
return wrapErr(err)
}
var mgmTlsEnabled bool
if config.ManagementURL.Scheme == "https" {
mgmTlsEnabled = true
}
publicSSHKey, err := ssh.GeneratePublicKey([]byte(config.SSHKey))
if err != nil {
return err
}
var path string
if runtime.GOOS == "ios" || runtime.GOOS == "android" {
// On mobile, use the provided state file path directly
if !fileExists(mobileDependency.StateFilePath) {
if err := createFile(mobileDependency.StateFilePath); err != nil {
log.Errorf("failed to create state file: %v", err)
// we are not exiting as we can run without the state manager
}
}
path = mobileDependency.StateFilePath
} else {
sm := profilemanager.NewServiceManager("")
path = sm.GetStatePath()
}
stateManager := statemanager.New(path)
stateManager.RegisterState(&sshconfig.ShutdownState{})
if c.updateManager != nil {
c.updateManager.CheckUpdateSuccess(c.ctx)
}
inst := installer.New()
if err := inst.CleanUpInstallerFiles(); err != nil {
log.Errorf("failed to clean up temporary installer file: %v", err)
}
defer c.statusRecorder.ClientStop()
operation := func() error {
// if context cancelled we not start new backoff cycle
if runCtx.Err() != nil {
return nil
}
state.Set(StatusConnecting)
engineCtx, cancel := context.WithCancel(runCtx)
defer func() {
_, err := state.Status()
c.statusRecorder.MarkManagementDisconnected(err)
c.statusRecorder.CleanLocalPeerState()
cancel()
}()
log.Debugf("connecting to the Management service %s", config.ManagementURL.Host)
mgmClient, err := mgm.NewClient(engineCtx, config.ManagementURL.Host, myPrivateKey, mgmTlsEnabled)
if err != nil {
return wrapErr(gstatus.Errorf(codes.FailedPrecondition, "failed connecting to Management Service : %s", err))
}
mgmNotifier := statusRecorderToMgmConnStateNotifier(c.statusRecorder)
mgmClient.SetConnStateListener(mgmNotifier)
// Update metrics with actual deployment type after connection
deploymentType := metrics.DetermineDeploymentType(mgmClient.GetServerURL())
agentInfo := metrics.AgentInfo{
DeploymentType: deploymentType,
Version: version.NetbirdVersion(),
OS: runtime.GOOS,
Arch: runtime.GOARCH,
}
c.clientMetrics.UpdateAgentInfo(agentInfo, myPrivateKey.PublicKey().String())
log.Debugf("connected to the Management service %s", config.ManagementURL.Host)
defer func() {
if err = mgmClient.Close(); err != nil {
log.Warnf("failed to close the Management service client %v", err)
}
}()
// connect (just a connection, no stream yet) and login to Management Service to get an initial global Netbird config
loginStarted := time.Now()
loginResp, err := loginToManagement(engineCtx, mgmClient, publicSSHKey, config)
if err != nil {
c.clientMetrics.RecordLoginDuration(engineCtx, time.Since(loginStarted), false)
log.Debug(err)
if s, ok := gstatus.FromError(err); ok && (s.Code() == codes.PermissionDenied) {
state.Set(StatusNeedsLogin)
// No teardown needed: login fails before the engine is started
// (engine.Start is below), so there is nothing running to stop.
return backoff.Permanent(wrapErr(err)) // unrecoverable error
}
return wrapErr(err)
}
c.clientMetrics.RecordLoginDuration(engineCtx, time.Since(loginStarted), true)
c.statusRecorder.MarkManagementConnected()
localPeerState := peer.LocalPeerState{
IP: loginResp.GetPeerConfig().GetAddress(),
PubKey: myPrivateKey.PublicKey().String(),
KernelInterface: device.WireGuardModuleIsLoaded() && !netstack.IsEnabled(),
FQDN: loginResp.GetPeerConfig().GetFqdn(),
}
c.statusRecorder.UpdateLocalPeerState(localPeerState)
signalURL := fmt.Sprintf("%s://%s",
strings.ToLower(loginResp.GetNetbirdConfig().GetSignal().GetProtocol().String()),
loginResp.GetNetbirdConfig().GetSignal().GetUri(),
)
c.statusRecorder.UpdateSignalAddress(signalURL)
c.statusRecorder.MarkSignalDisconnected(nil)
defer func() {
_, err := state.Status()
c.statusRecorder.MarkSignalDisconnected(err)
}()
// with the global Netbird config in hand connect (just a connection, no stream yet) Signal
signalClient, err := connectToSignal(engineCtx, loginResp.GetNetbirdConfig(), myPrivateKey)
if err != nil {
log.Error(err)
return wrapErr(err)
}
defer func() {
err = signalClient.Close()
if err != nil {
log.Warnf("failed closing Signal service client %v", err)
}
}()
signalNotifier := statusRecorderToSignalConnStateNotifier(c.statusRecorder)
signalClient.SetConnStateListener(signalNotifier)
c.statusRecorder.MarkSignalConnected()
relayURLs, token := parseRelayInfo(loginResp)
if override, ok := peer.OverrideRelayURLs(); ok {
log.Infof("overriding relay URLs from %s: %v", peer.EnvKeyNBHomeRelayServers, override)
relayURLs = override
}
peerConfig := loginResp.GetPeerConfig()
engineConfig, err := createEngineConfig(myPrivateKey, config, peerConfig, logPath)
if err != nil {
log.Error(err)
return wrapErr(err)
}
engineConfig.TempDir = mobileDependency.TempDir
// Leave StateDir empty when there is no state path so a disk-backed
// syncstore falls back to os.TempDir() instead of filepath.Dir("") == ".".
if path != "" {
engineConfig.StateDir = filepath.Dir(path)
}
relayManager := relayClient.NewManager(engineCtx, relayURLs, myPrivateKey.PublicKey().String(), engineConfig.MTU)
c.statusRecorder.SetRelayMgr(relayManager)
if len(relayURLs) > 0 {
if token != nil {
if err := relayManager.UpdateToken(token); err != nil {
log.Errorf("failed to update token: %s", err)
return wrapErr(err)
}
}
log.Infof("connecting to the Relay service(s): %s", strings.Join(relayURLs, ", "))
if err = relayManager.Serve(); err != nil {
log.Error(err)
}
}
checks := loginResp.GetChecks()
c.engineMutex.Lock()
engine := NewEngine(engineCtx, cancel, engineConfig, EngineServices{
SignalClient: signalClient,
MgmClient: mgmClient,
RelayManager: relayManager,
StatusRecorder: c.statusRecorder,
Checks: checks,
StateManager: stateManager,
UpdateManager: c.updateManager,
ClientMetrics: c.clientMetrics,
}, mobileDependency)
engine.SetSyncResponsePersistence(c.persistSyncResponse)
c.engine = engine
c.engineMutex.Unlock()
if err := engine.Start(loginResp.GetNetbirdConfig(), config.ManagementURL); err != nil {
log.Errorf("error while starting Netbird Connection Engine: %s", err)
return wrapErr(err)
}
log.Infof("Netbird engine started, the IP is: %s", peerConfig.GetAddress())
state.Set(StatusConnected)
if runningChan != nil {
select {
case <-runningChan:
default:
close(runningChan)
}
}
<-engineCtx.Done()
c.engineMutex.Lock()
c.engine = nil
c.engineMutex.Unlock()
// Always tear the engine down once its context is cancelled. engine.Stop
// is nil-guarded per component, so calling it unconditionally is safe and
// avoids both the data race on engine.wgInterface and skipping teardown
// when the interface was never brought up (e.g. a mid-start failure).
if err := engine.Stop(); err != nil {
log.Errorf("Failed to stop engine: %v", err)
}
c.statusRecorder.ClientTeardown()
backOff.Reset()
log.Info("stopped NetBird client")
if _, err := state.Status(); errors.Is(err, ErrResetConnection) {
return err
}
return nil
}
c.statusRecorder.ClientStart()
err = backoff.Retry(operation, backOff)
if err != nil {
log.Debugf("exiting client retry loop due to unrecoverable error: %s", err)
if s, ok := gstatus.FromError(err); ok && (s.Code() == codes.PermissionDenied) {
// Login failed permanently: the engine was never started, so there
// is nothing to tear down — just record that a login is needed.
state.Set(StatusNeedsLogin)
}
return err
}
return nil
}
func parseRelayInfo(loginResp *mgmProto.LoginResponse) ([]string, *hmac.Token) {
relayCfg := loginResp.GetNetbirdConfig().GetRelay()
if relayCfg == nil {
return nil, nil
}
token := &hmac.Token{
Payload: relayCfg.GetTokenPayload(),
Signature: relayCfg.GetTokenSignature(),
}
return relayCfg.GetUrls(), token
}
// IsRunning reports whether a client run is currently in flight. It is the
// single source of truth for "is the client running", answered by the
// supervisor via a serialized query (so it settles behind an in-flight stop).
// Intended for the external status surface (CLI/UI), not internal pre-checks.
func (c *ConnectClient) IsRunning() bool {
if c == nil || c.sup == nil {
return false
}
return c.sup.isRunning()
}
// ServiceRunning reports whether the client's lifecycle supervisor is alive and
// able to accept start/stop commands — i.e. the daemon-lifetime client exists
// and its context has not been cancelled. It is independent of whether a run is
// currently up (that is IsRunning). Nil-safe, so callers can ask it on a
// not-yet-constructed client and treat false as "service not running".
func (c *ConnectClient) ServiceRunning() bool {
if c == nil || c.sup == nil {
return false
}
return c.sup.ctx.Err() == nil
}
func (c *ConnectClient) Engine() *Engine {
if c == nil {
return nil
}
var e *Engine
c.engineMutex.Lock()
e = c.engine
c.engineMutex.Unlock()
return e
}
// GetLatestSyncResponse returns the latest sync response from the engine.
func (c *ConnectClient) GetLatestSyncResponse() (*mgmProto.SyncResponse, error) {
engine := c.Engine()
if engine == nil {
return nil, errors.New("engine is not initialized")
}
syncResponse, err := engine.GetLatestSyncResponse()
if err != nil {
return nil, fmt.Errorf("get latest sync response: %w", err)
}
if syncResponse == nil {
return nil, errors.New("sync response is not available")
}
return syncResponse, nil
}
// SetLogLevel sets the log level for the firewall manager if the engine is running.
func (c *ConnectClient) SetLogLevel(level log.Level) {
engine := c.Engine()
if engine == nil {
return
}
fwManager := engine.GetFirewallManager()
if fwManager != nil {
fwManager.SetLogLevel(level)
}
}
// Status returns the current client status
func (c *ConnectClient) Status() StatusType {
if c == nil {
return StatusIdle
}
status, err := CtxGetState(c.ctx).Status()
if err != nil {
return StatusIdle
}
return status
}
// Stop serializes a stop request through the lifecycle supervisor and blocks
// until the in-flight run is fully torn down.
func (c *ConnectClient) Stop() error {
return c.sup.stop()
}
// SetSyncResponsePersistence enables or disables sync response persistence.
// When enabled, the last received sync response will be stored and can be retrieved
// through the Engine's GetLatestSyncResponse method. When disabled, any stored
// sync response will be cleared.
func (c *ConnectClient) SetSyncResponsePersistence(enabled bool) {
c.engineMutex.Lock()
c.persistSyncResponse = enabled
c.engineMutex.Unlock()
engine := c.Engine()
if engine != nil {
engine.SetSyncResponsePersistence(enabled)
}
}
// createEngineConfig converts configuration received from Management Service to EngineConfig
func createEngineConfig(key wgtypes.Key, config *profilemanager.Config, peerConfig *mgmProto.PeerConfig, logPath string) (*EngineConfig, error) {
nm := false
if config.NetworkMonitor != nil {
nm = *config.NetworkMonitor
}
wgAddr, err := wgaddr.ParseWGAddress(peerConfig.Address)
if err != nil {
return nil, fmt.Errorf("parse overlay address %q: %w", peerConfig.Address, err)
}
if !config.DisableIPv6 {
if err := wgAddr.SetIPv6FromCompact(peerConfig.GetAddressV6()); err != nil {
log.Warn(err)
}
}
engineConf := &EngineConfig{
WgIfaceName: config.WgIface,
WgAddr: wgAddr,
IFaceBlackList: config.IFaceBlackList,
DisableIPv6Discovery: config.DisableIPv6Discovery,
WgPrivateKey: key,
WgPort: config.WgPort,
NetworkMonitor: nm,
SSHKey: []byte(config.SSHKey),
NATExternalIPs: config.NATExternalIPs,
CustomDNSAddress: config.CustomDNSAddress,
RosenpassEnabled: config.RosenpassEnabled,
RosenpassPermissive: config.RosenpassPermissive,
ServerSSHAllowed: util.ReturnBoolWithDefaultTrue(config.ServerSSHAllowed),
EnableSSHRoot: config.EnableSSHRoot,
EnableSSHSFTP: config.EnableSSHSFTP,
EnableSSHLocalPortForwarding: config.EnableSSHLocalPortForwarding,
EnableSSHRemotePortForwarding: config.EnableSSHRemotePortForwarding,
DisableSSHAuth: config.DisableSSHAuth,
DNSRouteInterval: config.DNSRouteInterval,
DisableClientRoutes: config.DisableClientRoutes,
DisableServerRoutes: config.DisableServerRoutes || config.BlockInbound,
DisableDNS: config.DisableDNS,
DisableFirewall: config.DisableFirewall,
BlockLANAccess: config.BlockLANAccess,
BlockInbound: config.BlockInbound,
DisableIPv6: config.DisableIPv6,
LazyConnectionEnabled: config.LazyConnectionEnabled,
MTU: selectMTU(config.MTU, peerConfig.Mtu),
LogPath: logPath,
ProfileConfig: config,
}
if config.PreSharedKey != "" {
preSharedKey, err := wgtypes.ParseKey(config.PreSharedKey)
if err != nil {
return nil, err
}
engineConf.PreSharedKey = &preSharedKey
}
port, err := freePort(config.WgPort)
if err != nil {
return nil, err
}
if port != config.WgPort {
log.Infof("using %d as wireguard port: %d is in use", port, config.WgPort)
}
engineConf.WgPort = port
return engineConf, nil
}
func selectMTU(localMTU uint16, peerMTU int32) uint16 {
var finalMTU uint16 = iface.DefaultMTU
if localMTU > 0 {
finalMTU = localMTU
} else if peerMTU > 0 {
finalMTU = uint16(peerMTU)
}
// Set global DNS MTU
dns.SetCurrentMTU(finalMTU)
return finalMTU
}
// connectToSignal creates Signal Service client and established a connection
func connectToSignal(ctx context.Context, wtConfig *mgmProto.NetbirdConfig, ourPrivateKey wgtypes.Key) (*signal.GrpcClient, error) {
var sigTLSEnabled bool
if wtConfig.Signal.Protocol == mgmProto.HostConfig_HTTPS {
sigTLSEnabled = true
} else {
sigTLSEnabled = false
}
signalClient, err := signal.NewClient(ctx, wtConfig.Signal.Uri, ourPrivateKey, sigTLSEnabled)
if err != nil {
log.Errorf("error while connecting to the Signal Exchange Service %s: %s", wtConfig.Signal.Uri, err)
return nil, gstatus.Errorf(codes.FailedPrecondition, "failed connecting to Signal Service : %s", err)
}
return signalClient, nil
}
// loginToManagement creates Management ServiceDependencies client, establishes a connection, logs-in and gets a global Netbird config (signal, turn, stun hosts, etc)
func loginToManagement(ctx context.Context, client mgm.Client, pubSSHKey []byte, config *profilemanager.Config) (*mgmProto.LoginResponse, error) {
sysInfo := system.GetInfo(ctx)
sysInfo.SetFlags(
config.RosenpassEnabled,
config.RosenpassPermissive,
config.ServerSSHAllowed,
config.DisableClientRoutes,
config.DisableServerRoutes,
config.DisableDNS,
config.DisableFirewall,
config.BlockLANAccess,
config.BlockInbound,
config.DisableIPv6,
config.LazyConnectionEnabled,
config.EnableSSHRoot,
config.EnableSSHSFTP,
config.EnableSSHLocalPortForwarding,
config.EnableSSHRemotePortForwarding,
config.DisableSSHAuth,
)
return client.Login(sysInfo, pubSSHKey, config.DNSLabels)
}
func statusRecorderToMgmConnStateNotifier(statusRecorder *peer.Status) mgm.ConnStateNotifier {
var sri interface{} = statusRecorder
mgmNotifier, _ := sri.(mgm.ConnStateNotifier)
return mgmNotifier
}
func statusRecorderToSignalConnStateNotifier(statusRecorder *peer.Status) signal.ConnStateNotifier {
var sri interface{} = statusRecorder
notifier, _ := sri.(signal.ConnStateNotifier)
return notifier
}
// freePort attempts to determine if the provided port is available, if not it will ask the system for a free port.
func freePort(initPort int) (int, error) {
addr := net.UDPAddr{Port: initPort}
conn, err := net.ListenUDP("udp", &addr)
if err == nil {
returnPort := conn.LocalAddr().(*net.UDPAddr).Port
closeConnWithLog(conn)
return returnPort, nil
}
// if the port is already in use, ask the system for a free port
addr.Port = 0
conn, err = net.ListenUDP("udp", &addr)
if err != nil {
return 0, fmt.Errorf("unable to get a free port: %v", err)
}
udpAddr, ok := conn.LocalAddr().(*net.UDPAddr)
if !ok {
return 0, errors.New("wrong address type when getting a free port")
}
closeConnWithLog(conn)
return udpAddr.Port, nil
}
func closeConnWithLog(conn *net.UDPConn) {
startClosing := time.Now()
err := conn.Close()
if err != nil {
log.Warnf("closing probe port %d failed: %v. NetBird will still attempt to use this port for connection.", conn.LocalAddr().(*net.UDPAddr).Port, err)
}
if time.Since(startClosing) > time.Second {
log.Warnf("closing the testing port %d took %s. Usually it is safe to ignore, but continuous warnings may indicate a problem.", conn.LocalAddr().(*net.UDPAddr).Port, time.Since(startClosing))
}
}