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origin/tunnel.go

691lines · 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 == ""; isTrialTunnel {
354 if url, err := url.Parse(registration.Url); err == nil {
355 for _, line := range asciiBox(trialZoneMsg(url.String()), 2) {
356 config.Logger.Infoln(line)
357 }
358 } else {
359 config.Logger.Errorln("Failed to connect tunnel, please try again.")
360 return fmt.Errorf("empty URL in response from Cloudflare edge")
361 }
362 }
363
364 config.Logger.Infof("Route propagating, it may take up to 1 minute for your new route to become functional")
365 return nil
366}
367
368func UnregisterTunnel(muxer *h2mux.Muxer, gracePeriod time.Duration, logger *log.Logger) error {
369 logger.Debug("initiating RPC stream to unregister")
370 stream, err := muxer.OpenStream([]h2mux.Header{
371 {Name: ":method", Value: "RPC"},
372 {Name: ":scheme", Value: "capnp"},
373 {Name: ":path", Value: "*"},
374 }, nil)
375 if err != nil {
376 // RPC stream open error
377 return err
378 }
379 if !IsRPCStreamResponse(stream.Headers) {
380 // stream response error
381 return err
382 }
383 ctx := context.Background()
384 conn := rpc.NewConn(
385 tunnelrpc.NewTransportLogger(logger.WithField("subsystem", "rpc-unregister"), rpc.StreamTransport(stream)),
386 tunnelrpc.ConnLog(logger.WithField("subsystem", "rpc-transport")),
387 )
388 defer conn.Close()
389 ts := tunnelpogs.TunnelServer_PogsClient{Client: conn.Bootstrap(ctx)}
390 // gracePeriod is encoded in int64 using capnproto
391 return ts.UnregisterTunnel(ctx, gracePeriod.Nanoseconds())
392}
393
394func LogServerInfo(
395 promise tunnelrpc.ServerInfo_Promise,
396 connectionID uint8,
397 metrics *TunnelMetrics,
398 logger *log.Logger,
399) {
400 serverInfoMessage, err := promise.Struct()
401 if err != nil {
402 logger.WithError(err).Warn("Failed to retrieve server information")
403 return
404 }
405 serverInfo, err := tunnelpogs.UnmarshalServerInfo(serverInfoMessage)
406 if err != nil {
407 logger.WithError(err).Warn("Failed to retrieve server information")
408 return
409 }
410 logger.Infof("Connected to %s", serverInfo.LocationName)
411 metrics.registerServerLocation(uint8ToString(connectionID), serverInfo.LocationName)
412}
413
414func H2RequestHeadersToH1Request(h2 []h2mux.Header, h1 *http.Request) error {
415 for _, header := range h2 {
416 switch header.Name {
417 case ":method":
418 h1.Method = header.Value
419 case ":scheme":
420 case ":authority":
421 // Otherwise the host header will be based on the origin URL
422 h1.Host = header.Value
423 case ":path":
424 u, err := url.Parse(header.Value)
425 if err != nil {
426 return fmt.Errorf("unparseable path")
427 }
428 resolved := h1.URL.ResolveReference(u)
429 // prevent escaping base URL
430 if !strings.HasPrefix(resolved.String(), h1.URL.String()) {
431 return fmt.Errorf("invalid path")
432 }
433 h1.URL = resolved
434 case "content-length":
435 contentLength, err := strconv.ParseInt(header.Value, 10, 64)
436 if err != nil {
437 return fmt.Errorf("unparseable content length")
438 }
439 h1.ContentLength = contentLength
440 default:
441 h1.Header.Add(http.CanonicalHeaderKey(header.Name), header.Value)
442 }
443 }
444 return nil
445}
446
447func H1ResponseToH2Response(h1 *http.Response) (h2 []h2mux.Header) {
448 h2 = []h2mux.Header{{Name: ":status", Value: fmt.Sprintf("%d", h1.StatusCode)}}
449 for headerName, headerValues := range h1.Header {
450 for _, headerValue := range headerValues {
451 h2 = append(h2, h2mux.Header{Name: strings.ToLower(headerName), Value: headerValue})
452 }
453 }
454 return
455}
456
457func FindCfRayHeader(h1 *http.Request) string {
458 return h1.Header.Get("Cf-Ray")
459}
460
461type TunnelHandler struct {
462 originUrl string
463 muxer *h2mux.Muxer
464 httpClient http.RoundTripper
465 tlsConfig *tls.Config
466 tags []tunnelpogs.Tag
467 metrics *TunnelMetrics
468 // connectionID is only used by metrics, and prometheus requires labels to be string
469 connectionID string
470 logger *log.Logger
471 noChunkedEncoding bool
472}
473
474var dialer = net.Dialer{DualStack: true}
475
476// NewTunnelHandler returns a TunnelHandler, origin LAN IP and error
477func NewTunnelHandler(ctx context.Context,
478 config *TunnelConfig,
479 addr string,
480 connectionID uint8,
481) (*TunnelHandler, string, error) {
482 originURL, err := validation.ValidateUrl(config.OriginUrl)
483 if err != nil {
484 return nil, "", fmt.Errorf("unable to parse origin URL %#v", originURL)
485 }
486 h := &TunnelHandler{
487 originUrl: originURL,
488 httpClient: config.HTTPTransport,
489 tlsConfig: config.ClientTlsConfig,
490 tags: config.Tags,
491 metrics: config.Metrics,
492 connectionID: uint8ToString(connectionID),
493 logger: config.Logger,
494 noChunkedEncoding: config.NoChunkedEncoding,
495 }
496 if h.httpClient == nil {
497 h.httpClient = http.DefaultTransport
498 }
499 // Inherit from parent context so we can cancel (Ctrl-C) while dialing
500 dialCtx, dialCancel := context.WithTimeout(ctx, dialTimeout)
501 // TUN-92: enforce a timeout on dial and handshake (as tls.Dial does not support one)
502 plaintextEdgeConn, err := dialer.DialContext(dialCtx, "tcp", addr)
503 dialCancel()
504 if err != nil {
505 return nil, "", dialError{cause: errors.Wrap(err, "DialContext error")}
506 }
507 edgeConn := tls.Client(plaintextEdgeConn, config.TlsConfig)
508 edgeConn.SetDeadline(time.Now().Add(dialTimeout))
509 err = edgeConn.Handshake()
510 if err != nil {
511 return nil, "", dialError{cause: errors.Wrap(err, "Handshake with edge error")}
512 }
513 // clear the deadline on the conn; h2mux has its own timeouts
514 edgeConn.SetDeadline(time.Time{})
515 // Establish a muxed connection with the edge
516 // Client mux handshake with agent server
517 h.muxer, err = h2mux.Handshake(edgeConn, edgeConn, h2mux.MuxerConfig{
518 Timeout: 5 * time.Second,
519 Handler: h,
520 IsClient: true,
521 HeartbeatInterval: config.HeartbeatInterval,
522 MaxHeartbeats: config.MaxHeartbeats,
523 Logger: config.ProtocolLogger.WithFields(log.Fields{}),
524 CompressionQuality: h2mux.CompressionSetting(config.CompressionQuality),
525 })
526 if err != nil {
527 return h, "", errors.New("TLS handshake error")
528 }
529 return h, edgeConn.LocalAddr().String(), err
530}
531
532func (h *TunnelHandler) AppendTagHeaders(r *http.Request) {
533 for _, tag := range h.tags {
534 r.Header.Add(TagHeaderNamePrefix+tag.Name, tag.Value)
535 }
536}
537
538func (h *TunnelHandler) ServeStream(stream *h2mux.MuxedStream) error {
539 h.metrics.incrementRequests(h.connectionID)
540 req, err := http.NewRequest("GET", h.originUrl, h2mux.MuxedStreamReader{MuxedStream: stream})
541 if err != nil {
542 h.logger.WithError(err).Panic("Unexpected error from http.NewRequest")
543 }
544 err = H2RequestHeadersToH1Request(stream.Headers, req)
545 if err != nil {
546 h.logger.WithError(err).Error("invalid request received")
547 }
548 h.AppendTagHeaders(req)
549 cfRay := FindCfRayHeader(req)
550 lbProbe := isLBProbeRequest(req)
551 h.logRequest(req, cfRay, lbProbe)
552 if websocket.IsWebSocketUpgrade(req) {
553 conn, response, err := websocket.ClientConnect(req, h.tlsConfig)
554 if err != nil {
555 h.logError(stream, err)
556 } else {
557 stream.WriteHeaders(H1ResponseToH2Response(response))
558 defer conn.Close()
559 // Copy to/from stream to the undelying connection. Use the underlying
560 // connection because cloudflared doesn't operate on the message themselves
561 websocket.Stream(conn.UnderlyingConn(), stream)
562 h.metrics.incrementResponses(h.connectionID, "200")
563 h.logResponse(response, cfRay, lbProbe)
564 }
565 } else {
566 // Support for WSGI Servers by switching transfer encoding from chunked to gzip/deflate
567 if h.noChunkedEncoding {
568 req.TransferEncoding = []string{"gzip", "deflate"}
569 cLength, err := strconv.Atoi(req.Header.Get("Content-Length"))
570 if err == nil {
571 req.ContentLength = int64(cLength)
572 }
573 }
574
575 // Request origin to keep connection alive to improve performance
576 req.Header.Set("Connection", "keep-alive")
577
578 response, err := h.httpClient.RoundTrip(req)
579
580 if err != nil {
581 h.logError(stream, err)
582 } else {
583 defer response.Body.Close()
584 stream.WriteHeaders(H1ResponseToH2Response(response))
585 if h.isEventStream(response) {
586 h.writeEventStream(stream, response.Body)
587 } else {
588 // Use CopyBuffer, because Copy only allocates a 32KiB buffer, and cross-stream
589 // compression generates dictionary on first write
590 io.CopyBuffer(stream, response.Body, make([]byte, 512*1024))
591 }
592
593 h.metrics.incrementResponses(h.connectionID, "200")
594 h.logResponse(response, cfRay, lbProbe)
595 }
596 }
597 h.metrics.decrementConcurrentRequests(h.connectionID)
598 return nil
599}
600
601func (h *TunnelHandler) writeEventStream(stream *h2mux.MuxedStream, responseBody io.ReadCloser) {
602 reader := bufio.NewReader(responseBody)
603 for {
604 line, err := reader.ReadBytes('\n')
605 if err != nil {
606 break
607 }
608 stream.Write(line)
609 }
610}
611
612func (h *TunnelHandler) isEventStream(response *http.Response) bool {
613 if response.Header.Get("content-type") == "text/event-stream" {
614 h.logger.Debug("Detected Server-Side Events from Origin")
615 return true
616 }
617 return false
618}
619
620func (h *TunnelHandler) logError(stream *h2mux.MuxedStream, err error) {
621 h.logger.WithError(err).Error("HTTP request error")
622 stream.WriteHeaders([]h2mux.Header{{Name: ":status", Value: "502"}})
623 stream.Write([]byte("502 Bad Gateway"))
624 h.metrics.incrementResponses(h.connectionID, "502")
625}
626
627func (h *TunnelHandler) logRequest(req *http.Request, cfRay string, lbProbe bool) {
628 if cfRay != "" {
629 h.logger.WithField("CF-RAY", cfRay).Debugf("%s %s %s", req.Method, req.URL, req.Proto)
630 } else if lbProbe {
631 h.logger.Debugf("Load Balancer health check %s %s %s", req.Method, req.URL, req.Proto)
632 } else {
633 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)
634 }
635 h.logger.Debugf("Request Headers %+v", req.Header)
636}
637
638func (h *TunnelHandler) logResponse(r *http.Response, cfRay string, lbProbe bool) {
639 if cfRay != "" {
640 h.logger.WithField("CF-RAY", cfRay).Debugf("%s", r.Status)
641 } else if lbProbe {
642 h.logger.Debugf("Response to Load Balancer health check %s", r.Status)
643 } else {
644 h.logger.Infof("%s", r.Status)
645 }
646 h.logger.Debugf("Response Headers %+v", r.Header)
647}
648
649func (h *TunnelHandler) UpdateMetrics(connectionID string) {
650 h.metrics.updateMuxerMetrics(connectionID, h.muxer.Metrics())
651}
652
653func uint8ToString(input uint8) string {
654 return strconv.FormatUint(uint64(input), 10)
655}
656
657func isLBProbeRequest(req *http.Request) bool {
658 return strings.HasPrefix(req.UserAgent(), lbProbeUserAgentPrefix)
659}
660
661// Print out the given lines in a nice ASCII box.
662func asciiBox(lines []string, padding int) (box []string) {
663 maxLen := maxLen(lines)
664 spacer := strings.Repeat(" ", padding)
665
666 border := "+" + strings.Repeat("-", maxLen+(padding*2)) + "+"
667
668 box = append(box, border)
669 for _, line := range lines {
670 box = append(box, "|"+spacer+line+strings.Repeat(" ", maxLen-len(line))+spacer+"|")
671 }
672 box = append(box, border)
673 return
674}
675
676func maxLen(lines []string) int {
677 max := 0
678 for _, line := range lines {
679 if len(line) > max {
680 max = len(line)
681 }
682 }
683 return max
684}
685
686func trialZoneMsg(url string) []string {
687 return []string{
688 "Your free tunnel has started! Visit it:",
689 " " + url,
690 }
691}
692