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origin/tunnel.go

680lines · modecode

1package origin
2
3import (
4 "bufio"
5 "crypto/tls"
6 "fmt"
7 "github.com/google/uuid"
8 "io"
9 "net"
10 "net/http"
11 "net/url"
12 "strconv"
13 "strings"
14 "time"
15
16 "golang.org/x/net/context"
17 "golang.org/x/sync/errgroup"
18
19 "github.com/cloudflare/cloudflared/h2mux"
20 "github.com/cloudflare/cloudflared/tunnelrpc"
21 tunnelpogs "github.com/cloudflare/cloudflared/tunnelrpc/pogs"
22 "github.com/cloudflare/cloudflared/validation"
23 "github.com/cloudflare/cloudflared/websocket"
24
25 raven "github.com/getsentry/raven-go"
26 "github.com/pkg/errors"
27 _ "github.com/prometheus/client_golang/prometheus"
28 log "github.com/sirupsen/logrus"
29 rpc "zombiezen.com/go/capnproto2/rpc"
30)
31
32const (
33 dialTimeout = 15 * time.Second
34 lbProbeUserAgentPrefix = "Mozilla/5.0 (compatible; Cloudflare-Traffic-Manager/1.0; +https://www.cloudflare.com/traffic-manager/;"
35 TagHeaderNamePrefix = "Cf-Warp-Tag-"
36 DuplicateConnectionError = "EDUPCONN"
37)
38
39type TunnelConfig struct {
40 EdgeAddrs []string
41 OriginUrl string
42 Hostname string
43 OriginCert []byte
44 TlsConfig *tls.Config
45 ClientTlsConfig *tls.Config
46 Retries uint
47 HeartbeatInterval time.Duration
48 MaxHeartbeats uint64
49 ClientID string
50 BuildInfo *BuildInfo
51 ReportedVersion string
52 LBPool string
53 Tags []tunnelpogs.Tag
54 HAConnections int
55 HTTPTransport http.RoundTripper
56 Metrics *TunnelMetrics
57 MetricsUpdateFreq time.Duration
58 ProtocolLogger *log.Logger
59 Logger *log.Logger
60 IsAutoupdated bool
61 GracePeriod time.Duration
62 RunFromTerminal bool
63 NoChunkedEncoding bool
64 WSGI bool
65 CompressionQuality uint64
66}
67
68type dialError struct {
69 cause error
70}
71
72func (e dialError) Error() string {
73 return e.cause.Error()
74}
75
76type dupConnRegisterTunnelError struct{}
77
78func (e dupConnRegisterTunnelError) Error() string {
79 return "already connected to this server"
80}
81
82type muxerShutdownError struct{}
83
84func (e muxerShutdownError) Error() string {
85 return "muxer shutdown"
86}
87
88// RegisterTunnel error from server
89type serverRegisterTunnelError struct {
90 cause error
91 permanent bool
92}
93
94func (e serverRegisterTunnelError) Error() string {
95 return e.cause.Error()
96}
97
98// RegisterTunnel error from client
99type clientRegisterTunnelError struct {
100 cause error
101}
102
103func (e clientRegisterTunnelError) Error() string {
104 return e.cause.Error()
105}
106
107func (c *TunnelConfig) RegistrationOptions(connectionID uint8, OriginLocalIP string, uuid uuid.UUID) *tunnelpogs.RegistrationOptions {
108 policy := tunnelrpc.ExistingTunnelPolicy_balance
109 if c.HAConnections <= 1 && c.LBPool == "" {
110 policy = tunnelrpc.ExistingTunnelPolicy_disconnect
111 }
112 return &tunnelpogs.RegistrationOptions{
113 ClientID: c.ClientID,
114 Version: c.ReportedVersion,
115 OS: fmt.Sprintf("%s_%s", c.BuildInfo.GoOS, c.BuildInfo.GoArch),
116 ExistingTunnelPolicy: policy,
117 PoolName: c.LBPool,
118 Tags: c.Tags,
119 ConnectionID: connectionID,
120 OriginLocalIP: OriginLocalIP,
121 IsAutoupdated: c.IsAutoupdated,
122 RunFromTerminal: c.RunFromTerminal,
123 CompressionQuality: c.CompressionQuality,
124 UUID: uuid.String(),
125 }
126}
127
128func StartTunnelDaemon(config *TunnelConfig, shutdownC <-chan struct{}, connectedSignal chan struct{}) error {
129 ctx, cancel := context.WithCancel(context.Background())
130 go func() {
131 <-shutdownC
132 cancel()
133 }()
134 // If a user specified negative HAConnections, we will treat it as requesting 1 connection
135 if config.HAConnections > 1 {
136 return NewSupervisor(config).Run(ctx, connectedSignal)
137 } else {
138 addrs, err := ResolveEdgeIPs(config.EdgeAddrs)
139 if err != nil {
140 return err
141 }
142 return ServeTunnelLoop(ctx, config, addrs[0], 0, connectedSignal)
143 }
144}
145
146func ServeTunnelLoop(ctx context.Context,
147 config *TunnelConfig,
148 addr *net.TCPAddr,
149 connectionID uint8,
150 connectedSignal chan struct{},
151) error {
152 logger := config.Logger
153 config.Metrics.incrementHaConnections()
154 defer config.Metrics.decrementHaConnections()
155 backoff := BackoffHandler{MaxRetries: config.Retries}
156 // Used to close connectedSignal no more than once
157 connectedFuse := h2mux.NewBooleanFuse()
158 go func() {
159 if connectedFuse.Await() {
160 close(connectedSignal)
161 }
162 }()
163 // Ensure the above goroutine will terminate if we return without connecting
164 defer connectedFuse.Fuse(false)
165 for {
166 err, recoverable := ServeTunnel(ctx, config, addr, connectionID, connectedFuse, &backoff)
167 if recoverable {
168 if duration, ok := backoff.GetBackoffDuration(ctx); ok {
169 logger.Infof("Retrying in %s seconds", duration)
170 backoff.Backoff(ctx)
171 continue
172 }
173 }
174 return err
175 }
176}
177
178func ServeTunnel(
179 ctx context.Context,
180 config *TunnelConfig,
181 addr *net.TCPAddr,
182 connectionID uint8,
183 connectedFuse *h2mux.BooleanFuse,
184 backoff *BackoffHandler,
185) (err error, recoverable bool) {
186 // Treat panics as recoverable errors
187 defer func() {
188 if r := recover(); r != nil {
189 var ok bool
190 err, ok = r.(error)
191 if !ok {
192 err = fmt.Errorf("ServeTunnel: %v", r)
193 }
194 recoverable = true
195 }
196 }()
197
198 connectionTag := uint8ToString(connectionID)
199 logger := config.Logger.WithField("connectionID", connectionTag)
200
201 // additional tags to send other than hostname which is set in cloudflared main package
202 tags := make(map[string]string)
203 tags["ha"] = connectionTag
204
205 // Returns error from parsing the origin URL or handshake errors
206 handler, originLocalIP, err := NewTunnelHandler(ctx, config, addr.String(), connectionID)
207 if err != nil {
208 errLog := config.Logger.WithError(err)
209 switch err.(type) {
210 case dialError:
211 errLog.Error("Unable to dial edge")
212 case h2mux.MuxerHandshakeError:
213 errLog.Error("Handshake failed with edge server")
214 default:
215 errLog.Error("Tunnel creation failure")
216 return err, false
217 }
218 return err, true
219 }
220
221 errGroup, serveCtx := errgroup.WithContext(ctx)
222
223 errGroup.Go(func() error {
224 err := RegisterTunnel(serveCtx, handler.muxer, config, connectionID, originLocalIP)
225 if err == nil {
226 connectedFuse.Fuse(true)
227 backoff.SetGracePeriod()
228 }
229 return err
230 })
231
232 errGroup.Go(func() error {
233 updateMetricsTickC := time.Tick(config.MetricsUpdateFreq)
234 for {
235 select {
236 case <-serveCtx.Done():
237 // UnregisterTunnel blocks until the RPC call returns
238 err := UnregisterTunnel(handler.muxer, config.GracePeriod, config.Logger)
239 handler.muxer.Shutdown()
240 return err
241 case <-updateMetricsTickC:
242 handler.UpdateMetrics(connectionTag)
243 }
244 }
245 })
246
247 errGroup.Go(func() error {
248 // All routines should stop when muxer finish serving. When muxer is shutdown
249 // gracefully, it doesn't return an error, so we need to return errMuxerShutdown
250 // here to notify other routines to stop
251 err := handler.muxer.Serve(serveCtx)
252 if err == nil {
253 return muxerShutdownError{}
254 }
255 return err
256 })
257
258 err = errGroup.Wait()
259 if err != nil {
260 switch castedErr := err.(type) {
261 case dupConnRegisterTunnelError:
262 logger.Info("Already connected to this server, selecting a different one")
263 return err, true
264 case serverRegisterTunnelError:
265 logger.WithError(castedErr.cause).Error("Register tunnel error from server side")
266 // Don't send registration error return from server to Sentry. They are
267 // logged on server side
268 return castedErr.cause, !castedErr.permanent
269 case clientRegisterTunnelError:
270 logger.WithError(castedErr.cause).Error("Register tunnel error on client side")
271 raven.CaptureError(castedErr.cause, tags)
272 return err, true
273 case muxerShutdownError:
274 logger.Infof("Muxer shutdown")
275 return err, true
276 default:
277 logger.WithError(err).Error("Serve tunnel error")
278 raven.CaptureError(err, tags)
279 return err, true
280 }
281 }
282 return nil, true
283}
284
285func IsRPCStreamResponse(headers []h2mux.Header) bool {
286 if len(headers) != 1 {
287 return false
288 }
289 if headers[0].Name != ":status" || headers[0].Value != "200" {
290 return false
291 }
292 return true
293}
294
295func RegisterTunnel(ctx context.Context, muxer *h2mux.Muxer, config *TunnelConfig, connectionID uint8, originLocalIP string) error {
296 config.Logger.Debug("initiating RPC stream to register")
297 stream, err := muxer.OpenStream([]h2mux.Header{
298 {Name: ":method", Value: "RPC"},
299 {Name: ":scheme", Value: "capnp"},
300 {Name: ":path", Value: "*"},
301 }, nil)
302 if err != nil {
303 // RPC stream open error
304 return clientRegisterTunnelError{cause: err}
305 }
306 if !IsRPCStreamResponse(stream.Headers) {
307 // stream response error
308 return clientRegisterTunnelError{cause: err}
309 }
310 conn := rpc.NewConn(
311 tunnelrpc.NewTransportLogger(config.Logger.WithField("subsystem", "rpc-register"), rpc.StreamTransport(stream)),
312 tunnelrpc.ConnLog(config.Logger.WithField("subsystem", "rpc-transport")),
313 )
314 defer conn.Close()
315 ts := tunnelpogs.TunnelServer_PogsClient{Client: conn.Bootstrap(ctx)}
316 // Request server info without blocking tunnel registration; must use capnp library directly.
317 tsClient := tunnelrpc.TunnelServer{Client: ts.Client}
318 serverInfoPromise := tsClient.GetServerInfo(ctx, func(tunnelrpc.TunnelServer_getServerInfo_Params) error {
319 return nil
320 })
321 uuid, err := uuid.NewRandom()
322 if err != nil {
323 return clientRegisterTunnelError{cause: err}
324 }
325 registration, err := ts.RegisterTunnel(
326 ctx,
327 config.OriginCert,
328 config.Hostname,
329 config.RegistrationOptions(connectionID, originLocalIP, uuid),
330 )
331 LogServerInfo(serverInfoPromise.Result(), connectionID, config.Metrics, config.Logger)
332 if err != nil {
333 // RegisterTunnel RPC failure
334 return clientRegisterTunnelError{cause: err}
335 }
336 for _, logLine := range registration.LogLines {
337 config.Logger.Info(logLine)
338 }
339 if registration.Err == DuplicateConnectionError {
340 return dupConnRegisterTunnelError{}
341 } else if registration.Err != "" {
342 return serverRegisterTunnelError{
343 cause: fmt.Errorf("Server error: %s", registration.Err),
344 permanent: registration.PermanentFailure,
345 }
346 }
347
348 if registration.TunnelID != "" {
349 config.Logger.Info("Tunnel ID: " + registration.TunnelID)
350 }
351
352 // Print out the user's trial zone URL in a nice box (if they requested and got one)
353 if isTrialTunnel := config.Hostname == "" && registration.Url != ""; isTrialTunnel {
354 for _, line := range asciiBox(trialZoneMsg(registration.Url), 2) {
355 config.Logger.Infoln(line)
356 }
357 }
358
359 config.Logger.Infof("Route propagating, it may take up to 1 minute for your new route to become functional")
360 return nil
361}
362
363func UnregisterTunnel(muxer *h2mux.Muxer, gracePeriod time.Duration, logger *log.Logger) error {
364 logger.Debug("initiating RPC stream to unregister")
365 stream, err := muxer.OpenStream([]h2mux.Header{
366 {Name: ":method", Value: "RPC"},
367 {Name: ":scheme", Value: "capnp"},
368 {Name: ":path", Value: "*"},
369 }, nil)
370 if err != nil {
371 // RPC stream open error
372 return err
373 }
374 if !IsRPCStreamResponse(stream.Headers) {
375 // stream response error
376 return err
377 }
378 ctx := context.Background()
379 conn := rpc.NewConn(
380 tunnelrpc.NewTransportLogger(logger.WithField("subsystem", "rpc-unregister"), rpc.StreamTransport(stream)),
381 tunnelrpc.ConnLog(logger.WithField("subsystem", "rpc-transport")),
382 )
383 defer conn.Close()
384 ts := tunnelpogs.TunnelServer_PogsClient{Client: conn.Bootstrap(ctx)}
385 // gracePeriod is encoded in int64 using capnproto
386 return ts.UnregisterTunnel(ctx, gracePeriod.Nanoseconds())
387}
388
389func LogServerInfo(
390 promise tunnelrpc.ServerInfo_Promise,
391 connectionID uint8,
392 metrics *TunnelMetrics,
393 logger *log.Logger,
394) {
395 serverInfoMessage, err := promise.Struct()
396 if err != nil {
397 logger.WithError(err).Warn("Failed to retrieve server information")
398 return
399 }
400 serverInfo, err := tunnelpogs.UnmarshalServerInfo(serverInfoMessage)
401 if err != nil {
402 logger.WithError(err).Warn("Failed to retrieve server information")
403 return
404 }
405 logger.Infof("Connected to %s", serverInfo.LocationName)
406 metrics.registerServerLocation(uint8ToString(connectionID), serverInfo.LocationName)
407}
408
409func H2RequestHeadersToH1Request(h2 []h2mux.Header, h1 *http.Request) error {
410 for _, header := range h2 {
411 switch header.Name {
412 case ":method":
413 h1.Method = header.Value
414 case ":scheme":
415 case ":authority":
416 // Otherwise the host header will be based on the origin URL
417 h1.Host = header.Value
418 case ":path":
419 u, err := url.Parse(header.Value)
420 if err != nil {
421 return fmt.Errorf("unparseable path")
422 }
423 resolved := h1.URL.ResolveReference(u)
424 // prevent escaping base URL
425 if !strings.HasPrefix(resolved.String(), h1.URL.String()) {
426 return fmt.Errorf("invalid path")
427 }
428 h1.URL = resolved
429 default:
430 h1.Header.Add(http.CanonicalHeaderKey(header.Name), header.Value)
431 }
432 }
433 return nil
434}
435
436func H1ResponseToH2Response(h1 *http.Response) (h2 []h2mux.Header) {
437 h2 = []h2mux.Header{{Name: ":status", Value: fmt.Sprintf("%d", h1.StatusCode)}}
438 for headerName, headerValues := range h1.Header {
439 for _, headerValue := range headerValues {
440 h2 = append(h2, h2mux.Header{Name: strings.ToLower(headerName), Value: headerValue})
441 }
442 }
443 return
444}
445
446func FindCfRayHeader(h1 *http.Request) string {
447 return h1.Header.Get("Cf-Ray")
448}
449
450type TunnelHandler struct {
451 originUrl string
452 muxer *h2mux.Muxer
453 httpClient http.RoundTripper
454 tlsConfig *tls.Config
455 tags []tunnelpogs.Tag
456 metrics *TunnelMetrics
457 // connectionID is only used by metrics, and prometheus requires labels to be string
458 connectionID string
459 logger *log.Logger
460 noChunkedEncoding bool
461}
462
463var dialer = net.Dialer{DualStack: true}
464
465// NewTunnelHandler returns a TunnelHandler, origin LAN IP and error
466func NewTunnelHandler(ctx context.Context,
467 config *TunnelConfig,
468 addr string,
469 connectionID uint8,
470) (*TunnelHandler, string, error) {
471 originURL, err := validation.ValidateUrl(config.OriginUrl)
472 if err != nil {
473 return nil, "", fmt.Errorf("unable to parse origin URL %#v", originURL)
474 }
475 h := &TunnelHandler{
476 originUrl: originURL,
477 httpClient: config.HTTPTransport,
478 tlsConfig: config.ClientTlsConfig,
479 tags: config.Tags,
480 metrics: config.Metrics,
481 connectionID: uint8ToString(connectionID),
482 logger: config.Logger,
483 noChunkedEncoding: config.NoChunkedEncoding,
484 }
485 if h.httpClient == nil {
486 h.httpClient = http.DefaultTransport
487 }
488 // Inherit from parent context so we can cancel (Ctrl-C) while dialing
489 dialCtx, dialCancel := context.WithTimeout(ctx, dialTimeout)
490 // TUN-92: enforce a timeout on dial and handshake (as tls.Dial does not support one)
491 plaintextEdgeConn, err := dialer.DialContext(dialCtx, "tcp", addr)
492 dialCancel()
493 if err != nil {
494 return nil, "", dialError{cause: errors.Wrap(err, "DialContext error")}
495 }
496 edgeConn := tls.Client(plaintextEdgeConn, config.TlsConfig)
497 edgeConn.SetDeadline(time.Now().Add(dialTimeout))
498 err = edgeConn.Handshake()
499 if err != nil {
500 return nil, "", dialError{cause: errors.Wrap(err, "Handshake with edge error")}
501 }
502 // clear the deadline on the conn; h2mux has its own timeouts
503 edgeConn.SetDeadline(time.Time{})
504 // Establish a muxed connection with the edge
505 // Client mux handshake with agent server
506 h.muxer, err = h2mux.Handshake(edgeConn, edgeConn, h2mux.MuxerConfig{
507 Timeout: 5 * time.Second,
508 Handler: h,
509 IsClient: true,
510 HeartbeatInterval: config.HeartbeatInterval,
511 MaxHeartbeats: config.MaxHeartbeats,
512 Logger: config.ProtocolLogger.WithFields(log.Fields{}),
513 CompressionQuality: h2mux.CompressionSetting(config.CompressionQuality),
514 })
515 if err != nil {
516 return h, "", errors.New("TLS handshake error")
517 }
518 return h, edgeConn.LocalAddr().String(), err
519}
520
521func (h *TunnelHandler) AppendTagHeaders(r *http.Request) {
522 for _, tag := range h.tags {
523 r.Header.Add(TagHeaderNamePrefix+tag.Name, tag.Value)
524 }
525}
526
527func (h *TunnelHandler) ServeStream(stream *h2mux.MuxedStream) error {
528 h.metrics.incrementRequests(h.connectionID)
529 req, err := http.NewRequest("GET", h.originUrl, h2mux.MuxedStreamReader{MuxedStream: stream})
530 if err != nil {
531 h.logger.WithError(err).Panic("Unexpected error from http.NewRequest")
532 }
533 err = H2RequestHeadersToH1Request(stream.Headers, req)
534 if err != nil {
535 h.logger.WithError(err).Error("invalid request received")
536 }
537 h.AppendTagHeaders(req)
538 cfRay := FindCfRayHeader(req)
539 lbProbe := isLBProbeRequest(req)
540 h.logRequest(req, cfRay, lbProbe)
541 if websocket.IsWebSocketUpgrade(req) {
542 conn, response, err := websocket.ClientConnect(req, h.tlsConfig)
543 if err != nil {
544 h.logError(stream, err)
545 } else {
546 stream.WriteHeaders(H1ResponseToH2Response(response))
547 defer conn.Close()
548 // Copy to/from stream to the undelying connection. Use the underlying
549 // connection because cloudflared doesn't operate on the message themselves
550 websocket.Stream(conn.UnderlyingConn(), stream)
551 h.metrics.incrementResponses(h.connectionID, "200")
552 h.logResponse(response, cfRay, lbProbe)
553 }
554 } else {
555 // Support for WSGI Servers by switching transfer encoding from chunked to gzip/deflate
556 if h.noChunkedEncoding {
557 req.TransferEncoding = []string{"gzip", "deflate"}
558 cLength, err := strconv.Atoi(req.Header.Get("Content-Length"))
559 if err == nil {
560 req.ContentLength = int64(cLength)
561 }
562 }
563
564 // Request origin to keep connection alive to improve performance
565 req.Header.Set("Connection", "keep-alive")
566
567 response, err := h.httpClient.RoundTrip(req)
568
569 if err != nil {
570 h.logError(stream, err)
571 } else {
572 defer response.Body.Close()
573 stream.WriteHeaders(H1ResponseToH2Response(response))
574 if h.isEventStream(response) {
575 h.writeEventStream(stream, response.Body)
576 } else {
577 // Use CopyBuffer, because Copy only allocates a 32KiB buffer, and cross-stream
578 // compression generates dictionary on first write
579 io.CopyBuffer(stream, response.Body, make([]byte, 512*1024))
580 }
581
582 h.metrics.incrementResponses(h.connectionID, "200")
583 h.logResponse(response, cfRay, lbProbe)
584 }
585 }
586 h.metrics.decrementConcurrentRequests(h.connectionID)
587 return nil
588}
589
590func (h *TunnelHandler) writeEventStream(stream *h2mux.MuxedStream, responseBody io.ReadCloser) {
591 reader := bufio.NewReader(responseBody)
592 for {
593 line, err := reader.ReadBytes('\n')
594 if err != nil {
595 break
596 }
597 stream.Write(line)
598 }
599}
600
601func (h *TunnelHandler) isEventStream(response *http.Response) bool {
602 if response.Header.Get("content-type") == "text/event-stream" {
603 h.logger.Debug("Detected Server-Side Events from Origin")
604 return true
605 }
606 return false
607}
608
609func (h *TunnelHandler) logError(stream *h2mux.MuxedStream, err error) {
610 h.logger.WithError(err).Error("HTTP request error")
611 stream.WriteHeaders([]h2mux.Header{{Name: ":status", Value: "502"}})
612 stream.Write([]byte("502 Bad Gateway"))
613 h.metrics.incrementResponses(h.connectionID, "502")
614}
615
616func (h *TunnelHandler) logRequest(req *http.Request, cfRay string, lbProbe bool) {
617 if cfRay != "" {
618 h.logger.WithField("CF-RAY", cfRay).Debugf("%s %s %s", req.Method, req.URL, req.Proto)
619 } else if lbProbe {
620 h.logger.Debugf("Load Balancer health check %s %s %s", req.Method, req.URL, req.Proto)
621 } else {
622 h.logger.Warnf("All requests should have a CF-RAY header. Please open a support ticket with Cloudflare. %s %s %s ", req.Method, req.URL, req.Proto)
623 }
624 h.logger.Debugf("Request Headers %+v", req.Header)
625}
626
627func (h *TunnelHandler) logResponse(r *http.Response, cfRay string, lbProbe bool) {
628 if cfRay != "" {
629 h.logger.WithField("CF-RAY", cfRay).Debugf("%s", r.Status)
630 } else if lbProbe {
631 h.logger.Debugf("Response to Load Balancer health check %s", r.Status)
632 } else {
633 h.logger.Infof("%s", r.Status)
634 }
635 h.logger.Debugf("Response Headers %+v", r.Header)
636}
637
638func (h *TunnelHandler) UpdateMetrics(connectionID string) {
639 h.metrics.updateMuxerMetrics(connectionID, h.muxer.Metrics())
640}
641
642func uint8ToString(input uint8) string {
643 return strconv.FormatUint(uint64(input), 10)
644}
645
646func isLBProbeRequest(req *http.Request) bool {
647 return strings.HasPrefix(req.UserAgent(), lbProbeUserAgentPrefix)
648}
649
650// Print out the given lines in a nice ASCII box.
651func asciiBox(lines []string, padding int) (box []string) {
652 maxLen := maxLen(lines)
653 spacer := strings.Repeat(" ", padding)
654
655 border := "+" + strings.Repeat("-", maxLen+(padding*2)) + "+"
656
657 box = append(box, border)
658 for _, line := range lines {
659 box = append(box, "|"+spacer+line+strings.Repeat(" ", maxLen-len(line))+spacer+"|")
660 }
661 box = append(box, border)
662 return
663}
664
665func maxLen(lines []string) int {
666 max := 0
667 for _, line := range lines {
668 if len(line) > max {
669 max = len(line)
670 }
671 }
672 return max
673}
674
675func trialZoneMsg(url string) []string {
676 return []string{
677 "Your free tunnel has started! Visit it:",
678 " " + url,
679 }
680}
681