services/keep-web/handler.go

   1 // Copyright (C) The Arvados Authors. All rights reserved.
   2 //
   3 // SPDX-License-Identifier: AGPL-3.0
   4
   5 package main
   6
   7 import (
   8         "encoding/json"
   9         "fmt"
  10         "html"
  11         "html/template"
  12         "io"
  13         "log"
  14         "net/http"
  15         "net/url"
  16         "os"
  17         "sort"
  18         "strconv"
  19         "strings"
  20         "sync"
  21
  22         "git.curoverse.com/arvados.git/sdk/go/arvados"
  23         "git.curoverse.com/arvados.git/sdk/go/arvadosclient"
  24         "git.curoverse.com/arvados.git/sdk/go/auth"
  25         "git.curoverse.com/arvados.git/sdk/go/health"
  26         "git.curoverse.com/arvados.git/sdk/go/httpserver"
  27         "git.curoverse.com/arvados.git/sdk/go/keepclient"
  28         "golang.org/x/net/webdav"
  29 )
  30
  31 type handler struct {
  32         Config        *Config
  33         clientPool    *arvadosclient.ClientPool
  34         setupOnce     sync.Once
  35         healthHandler http.Handler
  36         webdavLS      webdav.LockSystem
  37 }
  38
  39 // parseCollectionIDFromDNSName returns a UUID or PDH if s begins with
  40 // a UUID or URL-encoded PDH; otherwise "".
  41 func parseCollectionIDFromDNSName(s string) string {
  42         // Strip domain.
  43         if i := strings.IndexRune(s, '.'); i >= 0 {
  44                 s = s[:i]
  45         }
  46         // Names like {uuid}--collections.example.com serve the same
  47         // purpose as {uuid}.collections.example.com but can reduce
  48         // cost/effort of using [additional] wildcard certificates.
  49         if i := strings.Index(s, "--"); i >= 0 {
  50                 s = s[:i]
  51         }
  52         if arvadosclient.UUIDMatch(s) {
  53                 return s
  54         }
  55         if pdh := strings.Replace(s, "-", "+", 1); arvadosclient.PDHMatch(pdh) {
  56                 return pdh
  57         }
  58         return ""
  59 }
  60
  61 var urlPDHDecoder = strings.NewReplacer(" ", "+", "-", "+")
  62
  63 // parseCollectionIDFromURL returns a UUID or PDH if s is a UUID or a
  64 // PDH (even if it is a PDH with "+" replaced by " " or "-");
  65 // otherwise "".
  66 func parseCollectionIDFromURL(s string) string {
  67         if arvadosclient.UUIDMatch(s) {
  68                 return s
  69         }
  70         if pdh := urlPDHDecoder.Replace(s); arvadosclient.PDHMatch(pdh) {
  71                 return pdh
  72         }
  73         return ""
  74 }
  75
  76 func (h *handler) setup() {
  77         h.clientPool = arvadosclient.MakeClientPool()
  78
  79         keepclient.RefreshServiceDiscoveryOnSIGHUP()
  80
  81         h.healthHandler = &health.Handler{
  82                 Token:  h.Config.ManagementToken,
  83                 Prefix: "/_health/",
  84         }
  85
  86         // Even though we don't accept LOCK requests, every webdav
  87         // handler must have a non-nil LockSystem.
  88         h.webdavLS = &noLockSystem{}
  89 }
  90
  91 func (h *handler) serveStatus(w http.ResponseWriter, r *http.Request) {
  92         status := struct {
  93                 cacheStats
  94                 Version string
  95         }{
  96                 cacheStats: h.Config.Cache.Stats(),
  97                 Version:    version,
  98         }
  99         json.NewEncoder(w).Encode(status)
 100 }
 101
 102 // updateOnSuccess wraps httpserver.ResponseWriter. If the handler
 103 // sends an HTTP header indicating success, updateOnSuccess first
 104 // calls the provided update func. If the update func fails, a 500
 105 // response is sent, and the status code and body sent by the handler
 106 // are ignored (all response writes return the update error).
 107 type updateOnSuccess struct {
 108         httpserver.ResponseWriter
 109         update     func() error
 110         sentHeader bool
 111         err        error
 112 }
 113
 114 func (uos *updateOnSuccess) Write(p []byte) (int, error) {
 115         if uos.err != nil {
 116                 return 0, uos.err
 117         }
 118         if !uos.sentHeader {
 119                 uos.WriteHeader(http.StatusOK)
 120         }
 121         return uos.ResponseWriter.Write(p)
 122 }
 123
 124 func (uos *updateOnSuccess) WriteHeader(code int) {
 125         if !uos.sentHeader {
 126                 uos.sentHeader = true
 127                 if code >= 200 && code < 400 {
 128                         if uos.err = uos.update(); uos.err != nil {
 129                                 code := http.StatusInternalServerError
 130                                 if err, ok := uos.err.(*arvados.TransactionError); ok {
 131                                         code = err.StatusCode
 132                                 }
 133                                 log.Printf("update() changes response to HTTP %d: %T %q", code, uos.err, uos.err)
 134                                 http.Error(uos.ResponseWriter, uos.err.Error(), code)
 135                                 return
 136                         }
 137                 }
 138         }
 139         uos.ResponseWriter.WriteHeader(code)
 140 }
 141
 142 var (
 143         writeMethod = map[string]bool{
 144                 "COPY":   true,
 145                 "DELETE": true,
 146                 "MKCOL":  true,
 147                 "MOVE":   true,
 148                 "PUT":    true,
 149                 "RMCOL":  true,
 150         }
 151         webdavMethod = map[string]bool{
 152                 "COPY":     true,
 153                 "DELETE":   true,
 154                 "MKCOL":    true,
 155                 "MOVE":     true,
 156                 "OPTIONS":  true,
 157                 "PROPFIND": true,
 158                 "PUT":      true,
 159                 "RMCOL":    true,
 160         }
 161         browserMethod = map[string]bool{
 162                 "GET":  true,
 163                 "HEAD": true,
 164                 "POST": true,
 165         }
 166 )
 167
 168 // ServeHTTP implements http.Handler.
 169 func (h *handler) ServeHTTP(wOrig http.ResponseWriter, r *http.Request) {
 170         h.setupOnce.Do(h.setup)
 171
 172         var statusCode = 0
 173         var statusText string
 174
 175         remoteAddr := r.RemoteAddr
 176         if xff := r.Header.Get("X-Forwarded-For"); xff != "" {
 177                 remoteAddr = xff + "," + remoteAddr
 178         }
 179
 180         w := httpserver.WrapResponseWriter(wOrig)
 181         defer func() {
 182                 if statusCode == 0 {
 183                         statusCode = w.WroteStatus()
 184                 } else if w.WroteStatus() == 0 {
 185                         w.WriteHeader(statusCode)
 186                 } else if w.WroteStatus() != statusCode {
 187                         httpserver.Log(r.RemoteAddr, "WARNING",
 188                                 fmt.Sprintf("Our status changed from %d to %d after we sent headers", w.WroteStatus(), statusCode))
 189                 }
 190                 if statusText == "" {
 191                         statusText = http.StatusText(statusCode)
 192                 }
 193                 httpserver.Log(remoteAddr, statusCode, statusText, w.WroteBodyBytes(), r.Method, r.Host, r.URL.Path, r.URL.RawQuery)
 194         }()
 195
 196         if strings.HasPrefix(r.URL.Path, "/_health/") && r.Method == "GET" {
 197                 h.healthHandler.ServeHTTP(w, r)
 198                 return
 199         }
 200
 201         if method := r.Header.Get("Access-Control-Request-Method"); method != "" && r.Method == "OPTIONS" {
 202                 if !browserMethod[method] && !webdavMethod[method] {
 203                         statusCode = http.StatusMethodNotAllowed
 204                         return
 205                 }
 206                 w.Header().Set("Access-Control-Allow-Headers", "Authorization, Content-Type, Range")
 207                 w.Header().Set("Access-Control-Allow-Methods", "COPY, DELETE, GET, MKCOL, MOVE, OPTIONS, POST, PROPFIND, PUT, RMCOL")
 208                 w.Header().Set("Access-Control-Allow-Origin", "*")
 209                 w.Header().Set("Access-Control-Max-Age", "86400")
 210                 statusCode = http.StatusOK
 211                 return
 212         }
 213
 214         if !browserMethod[r.Method] && !webdavMethod[r.Method] {
 215                 statusCode, statusText = http.StatusMethodNotAllowed, r.Method
 216                 return
 217         }
 218
 219         if r.Header.Get("Origin") != "" {
 220                 // Allow simple cross-origin requests without user
 221                 // credentials ("user credentials" as defined by CORS,
 222                 // i.e., cookies, HTTP authentication, and client-side
 223                 // SSL certificates. See
 224                 // http://www.w3.org/TR/cors/#user-credentials).
 225                 w.Header().Set("Access-Control-Allow-Origin", "*")
 226                 w.Header().Set("Access-Control-Expose-Headers", "Content-Range")
 227         }
 228
 229         pathParts := strings.Split(r.URL.Path[1:], "/")
 230
 231         var stripParts int
 232         var collectionID string
 233         var tokens []string
 234         var reqTokens []string
 235         var pathToken bool
 236         var attachment bool
 237         var useSiteFS bool
 238         credentialsOK := h.Config.TrustAllContent
 239
 240         if r.Host != "" && r.Host == h.Config.AttachmentOnlyHost {
 241                 credentialsOK = true
 242                 attachment = true
 243         } else if r.FormValue("disposition") == "attachment" {
 244                 attachment = true
 245         }
 246
 247         if collectionID = parseCollectionIDFromDNSName(r.Host); collectionID != "" {
 248                 // http://ID.collections.example/PATH...
 249                 credentialsOK = true
 250         } else if r.URL.Path == "/status.json" {
 251                 h.serveStatus(w, r)
 252                 return
 253         } else if len(pathParts) >= 1 && pathParts[0] == "users" {
 254                 useSiteFS = true
 255         } else if len(pathParts) >= 1 && strings.HasPrefix(pathParts[0], "c=") {
 256                 // /c=ID[/PATH...]
 257                 collectionID = parseCollectionIDFromURL(pathParts[0][2:])
 258                 stripParts = 1
 259         } else if len(pathParts) >= 2 && pathParts[0] == "collections" {
 260                 if len(pathParts) >= 4 && pathParts[1] == "download" {
 261                         // /collections/download/ID/TOKEN/PATH...
 262                         collectionID = parseCollectionIDFromURL(pathParts[2])
 263                         tokens = []string{pathParts[3]}
 264                         stripParts = 4
 265                         pathToken = true
 266                 } else {
 267                         // /collections/ID/PATH...
 268                         collectionID = parseCollectionIDFromURL(pathParts[1])
 269                         tokens = h.Config.AnonymousTokens
 270                         stripParts = 2
 271                 }
 272         }
 273
 274         if collectionID == "" && !useSiteFS {
 275                 statusCode = http.StatusNotFound
 276                 return
 277         }
 278
 279         forceReload := false
 280         if cc := r.Header.Get("Cache-Control"); strings.Contains(cc, "no-cache") || strings.Contains(cc, "must-revalidate") {
 281                 forceReload = true
 282         }
 283
 284         formToken := r.FormValue("api_token")
 285         if formToken != "" && r.Header.Get("Origin") != "" && attachment && r.URL.Query().Get("api_token") == "" {
 286                 // The client provided an explicit token in the POST
 287                 // body. The Origin header indicates this *might* be
 288                 // an AJAX request, in which case redirect-with-cookie
 289                 // won't work: we should just serve the content in the
 290                 // POST response. This is safe because:
 291                 //
 292                 // * We're supplying an attachment, not inline
 293                 //   content, so we don't need to convert the POST to
 294                 //   a GET and avoid the "really resubmit form?"
 295                 //   problem.
 296                 //
 297                 // * The token isn't embedded in the URL, so we don't
 298                 //   need to worry about bookmarks and copy/paste.
 299                 tokens = append(tokens, formToken)
 300         } else if formToken != "" && browserMethod[r.Method] {
 301                 // The client provided an explicit token in the query
 302                 // string, or a form in POST body. We must put the
 303                 // token in an HttpOnly cookie, and redirect to the
 304                 // same URL with the query param redacted and method =
 305                 // GET.
 306                 h.seeOtherWithCookie(w, r, "", credentialsOK)
 307                 return
 308         }
 309
 310         targetPath := pathParts[stripParts:]
 311         if tokens == nil && len(targetPath) > 0 && strings.HasPrefix(targetPath[0], "t=") {
 312                 // http://ID.example/t=TOKEN/PATH...
 313                 // /c=ID/t=TOKEN/PATH...
 314                 //
 315                 // This form must only be used to pass scoped tokens
 316                 // that give permission for a single collection. See
 317                 // FormValue case above.
 318                 tokens = []string{targetPath[0][2:]}
 319                 pathToken = true
 320                 targetPath = targetPath[1:]
 321                 stripParts++
 322         }
 323
 324         if tokens == nil {
 325                 if credentialsOK {
 326                         reqTokens = auth.NewCredentialsFromHTTPRequest(r).Tokens
 327                 }
 328                 tokens = append(reqTokens, h.Config.AnonymousTokens...)
 329         }
 330
 331         if useSiteFS {
 332                 h.serveSiteFS(w, r, tokens)
 333                 return
 334         }
 335
 336         if len(targetPath) > 0 && targetPath[0] == "_" {
 337                 // If a collection has a directory called "t=foo" or
 338                 // "_", it can be served at
 339                 // //collections.example/_/t=foo/ or
 340                 // //collections.example/_/_/ respectively:
 341                 // //collections.example/t=foo/ won't work because
 342                 // t=foo will be interpreted as a token "foo".
 343                 targetPath = targetPath[1:]
 344                 stripParts++
 345         }
 346
 347         arv := h.clientPool.Get()
 348         if arv == nil {
 349                 statusCode, statusText = http.StatusInternalServerError, "Pool failed: "+h.clientPool.Err().Error()
 350                 return
 351         }
 352         defer h.clientPool.Put(arv)
 353
 354         var collection *arvados.Collection
 355         tokenResult := make(map[string]int)
 356         for _, arv.ApiToken = range tokens {
 357                 var err error
 358                 collection, err = h.Config.Cache.Get(arv, collectionID, forceReload)
 359                 if err == nil {
 360                         // Success
 361                         break
 362                 }
 363                 if srvErr, ok := err.(arvadosclient.APIServerError); ok {
 364                         switch srvErr.HttpStatusCode {
 365                         case 404, 401:
 366                                 // Token broken or insufficient to
 367                                 // retrieve collection
 368                                 tokenResult[arv.ApiToken] = srvErr.HttpStatusCode
 369                                 continue
 370                         }
 371                 }
 372                 // Something more serious is wrong
 373                 statusCode, statusText = http.StatusInternalServerError, err.Error()
 374                 return
 375         }
 376         if collection == nil {
 377                 if pathToken || !credentialsOK {
 378                         // Either the URL is a "secret sharing link"
 379                         // that didn't work out (and asking the client
 380                         // for additional credentials would just be
 381                         // confusing), or we don't even accept
 382                         // credentials at this path.
 383                         statusCode = http.StatusNotFound
 384                         return
 385                 }
 386                 for _, t := range reqTokens {
 387                         if tokenResult[t] == 404 {
 388                                 // The client provided valid token(s), but the
 389                                 // collection was not found.
 390                                 statusCode = http.StatusNotFound
 391                                 return
 392                         }
 393                 }
 394                 // The client's token was invalid (e.g., expired), or
 395                 // the client didn't even provide one.  Propagate the
 396                 // 401 to encourage the client to use a [different]
 397                 // token.
 398                 //
 399                 // TODO(TC): This response would be confusing to
 400                 // someone trying (anonymously) to download public
 401                 // data that has been deleted.  Allow a referrer to
 402                 // provide this context somehow?
 403                 w.Header().Add("WWW-Authenticate", "Basic realm=\"collections\"")
 404                 statusCode = http.StatusUnauthorized
 405                 return
 406         }
 407
 408         kc, err := keepclient.MakeKeepClient(arv)
 409         if err != nil {
 410                 statusCode, statusText = http.StatusInternalServerError, err.Error()
 411                 return
 412         }
 413
 414         var basename string
 415         if len(targetPath) > 0 {
 416                 basename = targetPath[len(targetPath)-1]
 417         }
 418         applyContentDispositionHdr(w, r, basename, attachment)
 419
 420         client := &arvados.Client{
 421                 APIHost:   arv.ApiServer,
 422                 AuthToken: arv.ApiToken,
 423                 Insecure:  arv.ApiInsecure,
 424         }
 425
 426         fs, err := collection.FileSystem(client, kc)
 427         if err != nil {
 428                 statusCode, statusText = http.StatusInternalServerError, err.Error()
 429                 return
 430         }
 431
 432         writefs, writeOK := fs.(arvados.CollectionFileSystem)
 433         targetIsPDH := arvadosclient.PDHMatch(collectionID)
 434         if (targetIsPDH || !writeOK) && writeMethod[r.Method] {
 435                 statusCode, statusText = http.StatusMethodNotAllowed, errReadOnly.Error()
 436                 return
 437         }
 438
 439         if webdavMethod[r.Method] {
 440                 if writeMethod[r.Method] {
 441                         // Save the collection only if/when all
 442                         // webdav->filesystem operations succeed --
 443                         // and send a 500 error if the modified
 444                         // collection can't be saved.
 445                         w = &updateOnSuccess{
 446                                 ResponseWriter: w,
 447                                 update: func() error {
 448                                         return h.Config.Cache.Update(client, *collection, writefs)
 449                                 }}
 450                 }
 451                 h := webdav.Handler{
 452                         Prefix: "/" + strings.Join(pathParts[:stripParts], "/"),
 453                         FileSystem: &webdavFS{
 454                                 collfs:        fs,
 455                                 writing:       writeMethod[r.Method],
 456                                 alwaysReadEOF: r.Method == "PROPFIND",
 457                         },
 458                         LockSystem: h.webdavLS,
 459                         Logger: func(_ *http.Request, err error) {
 460                                 if err != nil {
 461                                         log.Printf("error from webdav handler: %q", err)
 462                                 }
 463                         },
 464                 }
 465                 h.ServeHTTP(w, r)
 466                 return
 467         }
 468
 469         openPath := "/" + strings.Join(targetPath, "/")
 470         if f, err := fs.Open(openPath); os.IsNotExist(err) {
 471                 // Requested non-existent path
 472                 statusCode = http.StatusNotFound
 473         } else if err != nil {
 474                 // Some other (unexpected) error
 475                 statusCode, statusText = http.StatusInternalServerError, err.Error()
 476         } else if stat, err := f.Stat(); err != nil {
 477                 // Can't get Size/IsDir (shouldn't happen with a collectionFS!)
 478                 statusCode, statusText = http.StatusInternalServerError, err.Error()
 479         } else if stat.IsDir() && !strings.HasSuffix(r.URL.Path, "/") {
 480                 // If client requests ".../dirname", redirect to
 481                 // ".../dirname/". This way, relative links in the
 482                 // listing for "dirname" can always be "fnm", never
 483                 // "dirname/fnm".
 484                 h.seeOtherWithCookie(w, r, r.URL.Path+"/", credentialsOK)
 485         } else if stat.IsDir() {
 486                 h.serveDirectory(w, r, collection.Name, fs, openPath, true)
 487         } else {
 488                 http.ServeContent(w, r, basename, stat.ModTime(), f)
 489                 if r.Header.Get("Range") == "" && int64(w.WroteBodyBytes()) != stat.Size() {
 490                         // If we wrote fewer bytes than expected, it's
 491                         // too late to change the real response code
 492                         // or send an error message to the client, but
 493                         // at least we can try to put some useful
 494                         // debugging info in the logs.
 495                         n, err := f.Read(make([]byte, 1024))
 496                         statusCode, statusText = http.StatusInternalServerError, fmt.Sprintf("f.Size()==%d but only wrote %d bytes; read(1024) returns %d, %s", stat.Size(), w.WroteBodyBytes(), n, err)
 497
 498                 }
 499         }
 500 }
 501
 502 func (h *handler) serveSiteFS(w http.ResponseWriter, r *http.Request, tokens []string) {
 503         if len(tokens) == 0 {
 504                 w.Header().Add("WWW-Authenticate", "Basic realm=\"collections\"")
 505                 http.Error(w, http.StatusText(http.StatusUnauthorized), http.StatusUnauthorized)
 506                 return
 507         }
 508         if writeMethod[r.Method] {
 509                 http.Error(w, errReadOnly.Error(), http.StatusMethodNotAllowed)
 510                 return
 511         }
 512         arv := h.clientPool.Get()
 513         if arv == nil {
 514                 http.Error(w, "Pool failed: "+h.clientPool.Err().Error(), http.StatusInternalServerError)
 515                 return
 516         }
 517         defer h.clientPool.Put(arv)
 518         arv.ApiToken = tokens[0]
 519
 520         kc, err := keepclient.MakeKeepClient(arv)
 521         if err != nil {
 522                 http.Error(w, err.Error(), http.StatusInternalServerError)
 523                 return
 524         }
 525         client := &arvados.Client{
 526                 APIHost:   arv.ApiServer,
 527                 AuthToken: arv.ApiToken,
 528                 Insecure:  arv.ApiInsecure,
 529         }
 530         fs := client.SiteFileSystem(kc)
 531         if f, err := fs.Open(r.URL.Path); os.IsNotExist(err) {
 532                 http.Error(w, err.Error(), http.StatusNotFound)
 533                 return
 534         } else if err != nil {
 535                 http.Error(w, err.Error(), http.StatusInternalServerError)
 536                 return
 537         } else if fi, err := f.Stat(); err == nil && fi.IsDir() && r.Method == "GET" {
 538
 539                 h.serveDirectory(w, r, fi.Name(), fs, r.URL.Path, false)
 540                 return
 541         } else {
 542                 f.Close()
 543         }
 544         wh := webdav.Handler{
 545                 Prefix: "/",
 546                 FileSystem: &webdavFS{
 547                         collfs:        fs,
 548                         writing:       writeMethod[r.Method],
 549                         alwaysReadEOF: r.Method == "PROPFIND",
 550                 },
 551                 LockSystem: h.webdavLS,
 552                 Logger: func(_ *http.Request, err error) {
 553                         if err != nil {
 554                                 log.Printf("error from webdav handler: %q", err)
 555                         }
 556                 },
 557         }
 558         wh.ServeHTTP(w, r)
 559 }
 560
 561 var dirListingTemplate = `<!DOCTYPE HTML>
 562 <HTML><HEAD>
 563   <META name="robots" content="NOINDEX">
 564   <TITLE>{{ .CollectionName }}</TITLE>
 565   <STYLE type="text/css">
 566     body {
 567       margin: 1.5em;
 568     }
 569     pre {
 570       background-color: #D9EDF7;
 571       border-radius: .25em;
 572       padding: .75em;
 573       overflow: auto;
 574     }
 575     .footer p {
 576       font-size: 82%;
 577     }
 578     ul {
 579       padding: 0;
 580     }
 581     ul li {
 582       font-family: monospace;
 583       list-style: none;
 584     }
 585   </STYLE>
 586 </HEAD>
 587 <BODY>
 588
 589 <H1>{{ .CollectionName }}</H1>
 590
 591 <P>This collection of data files is being shared with you through
 592 Arvados.  You can download individual files listed below.  To download
 593 the entire directory tree with wget, try:</P>
 594
 595 <PRE>$ wget --mirror --no-parent --no-host --cut-dirs={{ .StripParts }} https://{{ .Request.Host }}{{ .Request.URL.Path }}</PRE>
 596
 597 <H2>File Listing</H2>
 598
 599 {{if .Files}}
 600 <UL>
 601 {{range .Files}}
 602 {{if .IsDir }}
 603   <LI>{{" " | printf "%15s  " | nbsp}}<A href="{{.Name}}/">{{.Name}}/</A></LI>
 604 {{else}}
 605   <LI>{{.Size | printf "%15d  " | nbsp}}<A href="{{.Name}}">{{.Name}}</A></LI>
 606 {{end}}
 607 {{end}}
 608 </UL>
 609 {{else}}
 610 <P>(No files; this collection is empty.)</P>
 611 {{end}}
 612
 613 <HR noshade>
 614 <DIV class="footer">
 615   <P>
 616     About Arvados:
 617     Arvados is a free and open source software bioinformatics platform.
 618     To learn more, visit arvados.org.
 619     Arvados is not responsible for the files listed on this page.
 620   </P>
 621 </DIV>
 622
 623 </BODY>
 624 `
 625
 626 type fileListEnt struct {
 627         Name  string
 628         Size  int64
 629         IsDir bool
 630 }
 631
 632 func (h *handler) serveDirectory(w http.ResponseWriter, r *http.Request, collectionName string, fs http.FileSystem, base string, recurse bool) {
 633         var files []fileListEnt
 634         var walk func(string) error
 635         if !strings.HasSuffix(base, "/") {
 636                 base = base + "/"
 637         }
 638         walk = func(path string) error {
 639                 dirname := base + path
 640                 if dirname != "/" {
 641                         dirname = strings.TrimSuffix(dirname, "/")
 642                 }
 643                 d, err := fs.Open(dirname)
 644                 if err != nil {
 645                         return err
 646                 }
 647                 ents, err := d.Readdir(-1)
 648                 if err != nil {
 649                         return err
 650                 }
 651                 for _, ent := range ents {
 652                         if recurse && ent.IsDir() {
 653                                 err = walk(path + ent.Name() + "/")
 654                                 if err != nil {
 655                                         return err
 656                                 }
 657                         } else {
 658                                 files = append(files, fileListEnt{
 659                                         Name:  path + ent.Name(),
 660                                         Size:  ent.Size(),
 661                                         IsDir: ent.IsDir(),
 662                                 })
 663                         }
 664                 }
 665                 return nil
 666         }
 667         if err := walk(""); err != nil {
 668                 http.Error(w, err.Error(), http.StatusInternalServerError)
 669                 return
 670         }
 671
 672         funcs := template.FuncMap{
 673                 "nbsp": func(s string) template.HTML {
 674                         return template.HTML(strings.Replace(s, " ", "&nbsp;", -1))
 675                 },
 676         }
 677         tmpl, err := template.New("dir").Funcs(funcs).Parse(dirListingTemplate)
 678         if err != nil {
 679                 http.Error(w, err.Error(), http.StatusInternalServerError)
 680                 return
 681         }
 682         sort.Slice(files, func(i, j int) bool {
 683                 return files[i].Name < files[j].Name
 684         })
 685         w.WriteHeader(http.StatusOK)
 686         tmpl.Execute(w, map[string]interface{}{
 687                 "CollectionName": collectionName,
 688                 "Files":          files,
 689                 "Request":        r,
 690                 "StripParts":     strings.Count(strings.TrimRight(r.URL.Path, "/"), "/"),
 691         })
 692 }
 693
 694 func applyContentDispositionHdr(w http.ResponseWriter, r *http.Request, filename string, isAttachment bool) {
 695         disposition := "inline"
 696         if isAttachment {
 697                 disposition = "attachment"
 698         }
 699         if strings.ContainsRune(r.RequestURI, '?') {
 700                 // Help the UA realize that the filename is just
 701                 // "filename.txt", not
 702                 // "filename.txt?disposition=attachment".
 703                 //
 704                 // TODO(TC): Follow advice at RFC 6266 appendix D
 705                 disposition += "; filename=" + strconv.QuoteToASCII(filename)
 706         }
 707         if disposition != "inline" {
 708                 w.Header().Set("Content-Disposition", disposition)
 709         }
 710 }
 711
 712 func (h *handler) seeOtherWithCookie(w http.ResponseWriter, r *http.Request, location string, credentialsOK bool) {
 713         if formToken := r.FormValue("api_token"); formToken != "" {
 714                 if !credentialsOK {
 715                         // It is not safe to copy the provided token
 716                         // into a cookie unless the current vhost
 717                         // (origin) serves only a single collection or
 718                         // we are in TrustAllContent mode.
 719                         w.WriteHeader(http.StatusBadRequest)
 720                         return
 721                 }
 722
 723                 // The HttpOnly flag is necessary to prevent
 724                 // JavaScript code (included in, or loaded by, a page
 725                 // in the collection being served) from employing the
 726                 // user's token beyond reading other files in the same
 727                 // domain, i.e., same collection.
 728                 //
 729                 // The 303 redirect is necessary in the case of a GET
 730                 // request to avoid exposing the token in the Location
 731                 // bar, and in the case of a POST request to avoid
 732                 // raising warnings when the user refreshes the
 733                 // resulting page.
 734                 http.SetCookie(w, &http.Cookie{
 735                         Name:     "arvados_api_token",
 736                         Value:    auth.EncodeTokenCookie([]byte(formToken)),
 737                         Path:     "/",
 738                         HttpOnly: true,
 739                 })
 740         }
 741
 742         // Propagate query parameters (except api_token) from
 743         // the original request.
 744         redirQuery := r.URL.Query()
 745         redirQuery.Del("api_token")
 746
 747         u := r.URL
 748         if location != "" {
 749                 newu, err := u.Parse(location)
 750                 if err != nil {
 751                         w.WriteHeader(http.StatusInternalServerError)
 752                         return
 753                 }
 754                 u = newu
 755         }
 756         redir := (&url.URL{
 757                 Host:     r.Host,
 758                 Path:     u.Path,
 759                 RawQuery: redirQuery.Encode(),
 760         }).String()
 761
 762         w.Header().Add("Location", redir)
 763         w.WriteHeader(http.StatusSeeOther)
 764         io.WriteString(w, `<A href="`)
 765         io.WriteString(w, html.EscapeString(redir))
 766         io.WriteString(w, `">Continue</A>`)
 767 }