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         "net/http"
  14         "net/url"
  15         "os"
  16         "path/filepath"
  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         log "github.com/Sirupsen/logrus"
  29         "golang.org/x/net/webdav"
  30 )
  31
  32 type handler struct {
  33         Config        *Config
  34         MetricsAPI    http.Handler
  35         clientPool    *arvadosclient.ClientPool
  36         setupOnce     sync.Once
  37         healthHandler http.Handler
  38         webdavLS      webdav.LockSystem
  39 }
  40
  41 // parseCollectionIDFromDNSName returns a UUID or PDH if s begins with
  42 // a UUID or URL-encoded PDH; otherwise "".
  43 func parseCollectionIDFromDNSName(s string) string {
  44         // Strip domain.
  45         if i := strings.IndexRune(s, '.'); i >= 0 {
  46                 s = s[:i]
  47         }
  48         // Names like {uuid}--collections.example.com serve the same
  49         // purpose as {uuid}.collections.example.com but can reduce
  50         // cost/effort of using [additional] wildcard certificates.
  51         if i := strings.Index(s, "--"); i >= 0 {
  52                 s = s[:i]
  53         }
  54         if arvadosclient.UUIDMatch(s) {
  55                 return s
  56         }
  57         if pdh := strings.Replace(s, "-", "+", 1); arvadosclient.PDHMatch(pdh) {
  58                 return pdh
  59         }
  60         return ""
  61 }
  62
  63 var urlPDHDecoder = strings.NewReplacer(" ", "+", "-", "+")
  64
  65 // parseCollectionIDFromURL returns a UUID or PDH if s is a UUID or a
  66 // PDH (even if it is a PDH with "+" replaced by " " or "-");
  67 // otherwise "".
  68 func parseCollectionIDFromURL(s string) string {
  69         if arvadosclient.UUIDMatch(s) {
  70                 return s
  71         }
  72         if pdh := urlPDHDecoder.Replace(s); arvadosclient.PDHMatch(pdh) {
  73                 return pdh
  74         }
  75         return ""
  76 }
  77
  78 func (h *handler) setup() {
  79         h.clientPool = arvadosclient.MakeClientPool()
  80
  81         keepclient.RefreshServiceDiscoveryOnSIGHUP()
  82
  83         h.healthHandler = &health.Handler{
  84                 Token:  h.Config.ManagementToken,
  85                 Prefix: "/_health/",
  86         }
  87
  88         // Even though we don't accept LOCK requests, every webdav
  89         // handler must have a non-nil LockSystem.
  90         h.webdavLS = &noLockSystem{}
  91 }
  92
  93 func (h *handler) serveStatus(w http.ResponseWriter, r *http.Request) {
  94         status := struct {
  95                 cacheStats
  96                 Version string
  97         }{
  98                 cacheStats: h.Config.Cache.Stats(),
  99                 Version:    version,
 100         }
 101         json.NewEncoder(w).Encode(status)
 102 }
 103
 104 // updateOnSuccess wraps httpserver.ResponseWriter. If the handler
 105 // sends an HTTP header indicating success, updateOnSuccess first
 106 // calls the provided update func. If the update func fails, a 500
 107 // response is sent, and the status code and body sent by the handler
 108 // are ignored (all response writes return the update error).
 109 type updateOnSuccess struct {
 110         httpserver.ResponseWriter
 111         update     func() error
 112         sentHeader bool
 113         err        error
 114 }
 115
 116 func (uos *updateOnSuccess) Write(p []byte) (int, error) {
 117         if !uos.sentHeader {
 118                 uos.WriteHeader(http.StatusOK)
 119         }
 120         if uos.err != nil {
 121                 return 0, uos.err
 122         }
 123         return uos.ResponseWriter.Write(p)
 124 }
 125
 126 func (uos *updateOnSuccess) WriteHeader(code int) {
 127         if !uos.sentHeader {
 128                 uos.sentHeader = true
 129                 if code >= 200 && code < 400 {
 130                         if uos.err = uos.update(); uos.err != nil {
 131                                 code := http.StatusInternalServerError
 132                                 if err, ok := uos.err.(*arvados.TransactionError); ok {
 133                                         code = err.StatusCode
 134                                 }
 135                                 log.Printf("update() changes response to HTTP %d: %T %q", code, uos.err, uos.err)
 136                                 http.Error(uos.ResponseWriter, uos.err.Error(), code)
 137                                 return
 138                         }
 139                 }
 140         }
 141         uos.ResponseWriter.WriteHeader(code)
 142 }
 143
 144 var (
 145         writeMethod = map[string]bool{
 146                 "COPY":   true,
 147                 "DELETE": true,
 148                 "MKCOL":  true,
 149                 "MOVE":   true,
 150                 "PUT":    true,
 151                 "RMCOL":  true,
 152         }
 153         webdavMethod = map[string]bool{
 154                 "COPY":     true,
 155                 "DELETE":   true,
 156                 "MKCOL":    true,
 157                 "MOVE":     true,
 158                 "OPTIONS":  true,
 159                 "PROPFIND": true,
 160                 "PUT":      true,
 161                 "RMCOL":    true,
 162         }
 163         browserMethod = map[string]bool{
 164                 "GET":  true,
 165                 "HEAD": true,
 166                 "POST": true,
 167         }
 168         // top-level dirs to serve with siteFS
 169         siteFSDir = map[string]bool{
 170                 "":      true, // root directory
 171                 "by_id": true,
 172                 "users": true,
 173         }
 174 )
 175
 176 // ServeHTTP implements http.Handler.
 177 func (h *handler) ServeHTTP(wOrig http.ResponseWriter, r *http.Request) {
 178         h.setupOnce.Do(h.setup)
 179
 180         var statusCode = 0
 181         var statusText string
 182
 183         remoteAddr := r.RemoteAddr
 184         if xff := r.Header.Get("X-Forwarded-For"); xff != "" {
 185                 remoteAddr = xff + "," + remoteAddr
 186         }
 187         if xfp := r.Header.Get("X-Forwarded-Proto"); xfp != "" && xfp != "http" {
 188                 r.URL.Scheme = xfp
 189         }
 190
 191         w := httpserver.WrapResponseWriter(wOrig)
 192         defer func() {
 193                 if statusCode == 0 {
 194                         statusCode = w.WroteStatus()
 195                 } else if w.WroteStatus() == 0 {
 196                         w.WriteHeader(statusCode)
 197                 } else if w.WroteStatus() != statusCode {
 198                         log.WithField("RequestID", r.Header.Get("X-Request-Id")).Warn(
 199                                 fmt.Sprintf("Our status changed from %d to %d after we sent headers", w.WroteStatus(), statusCode))
 200                 }
 201                 if statusText == "" {
 202                         statusText = http.StatusText(statusCode)
 203                 }
 204         }()
 205
 206         if strings.HasPrefix(r.URL.Path, "/_health/") && r.Method == "GET" {
 207                 h.healthHandler.ServeHTTP(w, r)
 208                 return
 209         }
 210
 211         if method := r.Header.Get("Access-Control-Request-Method"); method != "" && r.Method == "OPTIONS" {
 212                 if !browserMethod[method] && !webdavMethod[method] {
 213                         statusCode = http.StatusMethodNotAllowed
 214                         return
 215                 }
 216                 w.Header().Set("Access-Control-Allow-Headers", "Authorization, Content-Type, Range")
 217                 w.Header().Set("Access-Control-Allow-Methods", "COPY, DELETE, GET, MKCOL, MOVE, OPTIONS, POST, PROPFIND, PUT, RMCOL")
 218                 w.Header().Set("Access-Control-Allow-Origin", "*")
 219                 w.Header().Set("Access-Control-Max-Age", "86400")
 220                 statusCode = http.StatusOK
 221                 return
 222         }
 223
 224         if !browserMethod[r.Method] && !webdavMethod[r.Method] {
 225                 statusCode, statusText = http.StatusMethodNotAllowed, r.Method
 226                 return
 227         }
 228
 229         if r.Header.Get("Origin") != "" {
 230                 // Allow simple cross-origin requests without user
 231                 // credentials ("user credentials" as defined by CORS,
 232                 // i.e., cookies, HTTP authentication, and client-side
 233                 // SSL certificates. See
 234                 // http://www.w3.org/TR/cors/#user-credentials).
 235                 w.Header().Set("Access-Control-Allow-Origin", "*")
 236                 w.Header().Set("Access-Control-Expose-Headers", "Content-Range")
 237         }
 238
 239         pathParts := strings.Split(r.URL.Path[1:], "/")
 240
 241         var stripParts int
 242         var collectionID string
 243         var tokens []string
 244         var reqTokens []string
 245         var pathToken bool
 246         var attachment bool
 247         var useSiteFS bool
 248         credentialsOK := h.Config.TrustAllContent
 249
 250         if r.Host != "" && r.Host == h.Config.AttachmentOnlyHost {
 251                 credentialsOK = true
 252                 attachment = true
 253         } else if r.FormValue("disposition") == "attachment" {
 254                 attachment = true
 255         }
 256
 257         if collectionID = parseCollectionIDFromDNSName(r.Host); collectionID != "" {
 258                 // http://ID.collections.example/PATH...
 259                 credentialsOK = true
 260         } else if r.URL.Path == "/status.json" {
 261                 h.serveStatus(w, r)
 262                 return
 263         } else if strings.HasPrefix(r.URL.Path, "/metrics") {
 264                 h.MetricsAPI.ServeHTTP(w, r)
 265                 return
 266         } else if siteFSDir[pathParts[0]] {
 267                 useSiteFS = true
 268         } else if len(pathParts) >= 1 && strings.HasPrefix(pathParts[0], "c=") {
 269                 // /c=ID[/PATH...]
 270                 collectionID = parseCollectionIDFromURL(pathParts[0][2:])
 271                 stripParts = 1
 272         } else if len(pathParts) >= 2 && pathParts[0] == "collections" {
 273                 if len(pathParts) >= 4 && pathParts[1] == "download" {
 274                         // /collections/download/ID/TOKEN/PATH...
 275                         collectionID = parseCollectionIDFromURL(pathParts[2])
 276                         tokens = []string{pathParts[3]}
 277                         stripParts = 4
 278                         pathToken = true
 279                 } else {
 280                         // /collections/ID/PATH...
 281                         collectionID = parseCollectionIDFromURL(pathParts[1])
 282                         tokens = h.Config.AnonymousTokens
 283                         stripParts = 2
 284                 }
 285         }
 286
 287         if collectionID == "" && !useSiteFS {
 288                 statusCode = http.StatusNotFound
 289                 return
 290         }
 291
 292         forceReload := false
 293         if cc := r.Header.Get("Cache-Control"); strings.Contains(cc, "no-cache") || strings.Contains(cc, "must-revalidate") {
 294                 forceReload = true
 295         }
 296
 297         formToken := r.FormValue("api_token")
 298         if formToken != "" && r.Header.Get("Origin") != "" && attachment && r.URL.Query().Get("api_token") == "" {
 299                 // The client provided an explicit token in the POST
 300                 // body. The Origin header indicates this *might* be
 301                 // an AJAX request, in which case redirect-with-cookie
 302                 // won't work: we should just serve the content in the
 303                 // POST response. This is safe because:
 304                 //
 305                 // * We're supplying an attachment, not inline
 306                 //   content, so we don't need to convert the POST to
 307                 //   a GET and avoid the "really resubmit form?"
 308                 //   problem.
 309                 //
 310                 // * The token isn't embedded in the URL, so we don't
 311                 //   need to worry about bookmarks and copy/paste.
 312                 tokens = append(tokens, formToken)
 313         } else if formToken != "" && browserMethod[r.Method] {
 314                 // The client provided an explicit token in the query
 315                 // string, or a form in POST body. We must put the
 316                 // token in an HttpOnly cookie, and redirect to the
 317                 // same URL with the query param redacted and method =
 318                 // GET.
 319                 h.seeOtherWithCookie(w, r, "", credentialsOK)
 320                 return
 321         }
 322
 323         if useSiteFS {
 324                 if tokens == nil {
 325                         tokens = auth.NewCredentialsFromHTTPRequest(r).Tokens
 326                 }
 327                 h.serveSiteFS(w, r, tokens, credentialsOK, attachment)
 328                 return
 329         }
 330
 331         targetPath := pathParts[stripParts:]
 332         if tokens == nil && len(targetPath) > 0 && strings.HasPrefix(targetPath[0], "t=") {
 333                 // http://ID.example/t=TOKEN/PATH...
 334                 // /c=ID/t=TOKEN/PATH...
 335                 //
 336                 // This form must only be used to pass scoped tokens
 337                 // that give permission for a single collection. See
 338                 // FormValue case above.
 339                 tokens = []string{targetPath[0][2:]}
 340                 pathToken = true
 341                 targetPath = targetPath[1:]
 342                 stripParts++
 343         }
 344
 345         if tokens == nil {
 346                 if credentialsOK {
 347                         reqTokens = auth.NewCredentialsFromHTTPRequest(r).Tokens
 348                 }
 349                 tokens = append(reqTokens, h.Config.AnonymousTokens...)
 350         }
 351
 352         if len(targetPath) > 0 && targetPath[0] == "_" {
 353                 // If a collection has a directory called "t=foo" or
 354                 // "_", it can be served at
 355                 // //collections.example/_/t=foo/ or
 356                 // //collections.example/_/_/ respectively:
 357                 // //collections.example/t=foo/ won't work because
 358                 // t=foo will be interpreted as a token "foo".
 359                 targetPath = targetPath[1:]
 360                 stripParts++
 361         }
 362
 363         arv := h.clientPool.Get()
 364         if arv == nil {
 365                 statusCode, statusText = http.StatusInternalServerError, "Pool failed: "+h.clientPool.Err().Error()
 366                 return
 367         }
 368         defer h.clientPool.Put(arv)
 369
 370         var collection *arvados.Collection
 371         tokenResult := make(map[string]int)
 372         for _, arv.ApiToken = range tokens {
 373                 var err error
 374                 collection, err = h.Config.Cache.Get(arv, collectionID, forceReload)
 375                 if err == nil {
 376                         // Success
 377                         break
 378                 }
 379                 if srvErr, ok := err.(arvadosclient.APIServerError); ok {
 380                         switch srvErr.HttpStatusCode {
 381                         case 404, 401:
 382                                 // Token broken or insufficient to
 383                                 // retrieve collection
 384                                 tokenResult[arv.ApiToken] = srvErr.HttpStatusCode
 385                                 continue
 386                         }
 387                 }
 388                 // Something more serious is wrong
 389                 statusCode, statusText = http.StatusInternalServerError, err.Error()
 390                 return
 391         }
 392         if collection == nil {
 393                 if pathToken || !credentialsOK {
 394                         // Either the URL is a "secret sharing link"
 395                         // that didn't work out (and asking the client
 396                         // for additional credentials would just be
 397                         // confusing), or we don't even accept
 398                         // credentials at this path.
 399                         statusCode = http.StatusNotFound
 400                         return
 401                 }
 402                 for _, t := range reqTokens {
 403                         if tokenResult[t] == 404 {
 404                                 // The client provided valid token(s), but the
 405                                 // collection was not found.
 406                                 statusCode = http.StatusNotFound
 407                                 return
 408                         }
 409                 }
 410                 // The client's token was invalid (e.g., expired), or
 411                 // the client didn't even provide one.  Propagate the
 412                 // 401 to encourage the client to use a [different]
 413                 // token.
 414                 //
 415                 // TODO(TC): This response would be confusing to
 416                 // someone trying (anonymously) to download public
 417                 // data that has been deleted.  Allow a referrer to
 418                 // provide this context somehow?
 419                 w.Header().Add("WWW-Authenticate", "Basic realm=\"collections\"")
 420                 statusCode = http.StatusUnauthorized
 421                 return
 422         }
 423
 424         kc, err := keepclient.MakeKeepClient(arv)
 425         if err != nil {
 426                 statusCode, statusText = http.StatusInternalServerError, err.Error()
 427                 return
 428         }
 429         kc.RequestID = r.Header.Get("X-Request-Id")
 430
 431         var basename string
 432         if len(targetPath) > 0 {
 433                 basename = targetPath[len(targetPath)-1]
 434         }
 435         applyContentDispositionHdr(w, r, basename, attachment)
 436
 437         client := (&arvados.Client{
 438                 APIHost:   arv.ApiServer,
 439                 AuthToken: arv.ApiToken,
 440                 Insecure:  arv.ApiInsecure,
 441         }).WithRequestID(r.Header.Get("X-Request-Id"))
 442
 443         fs, err := collection.FileSystem(client, kc)
 444         if err != nil {
 445                 statusCode, statusText = http.StatusInternalServerError, err.Error()
 446                 return
 447         }
 448
 449         writefs, writeOK := fs.(arvados.CollectionFileSystem)
 450         targetIsPDH := arvadosclient.PDHMatch(collectionID)
 451         if (targetIsPDH || !writeOK) && writeMethod[r.Method] {
 452                 statusCode, statusText = http.StatusMethodNotAllowed, errReadOnly.Error()
 453                 return
 454         }
 455
 456         if webdavMethod[r.Method] {
 457                 if writeMethod[r.Method] {
 458                         // Save the collection only if/when all
 459                         // webdav->filesystem operations succeed --
 460                         // and send a 500 error if the modified
 461                         // collection can't be saved.
 462                         w = &updateOnSuccess{
 463                                 ResponseWriter: w,
 464                                 update: func() error {
 465                                         return h.Config.Cache.Update(client, *collection, writefs)
 466                                 }}
 467                 }
 468                 h := webdav.Handler{
 469                         Prefix: "/" + strings.Join(pathParts[:stripParts], "/"),
 470                         FileSystem: &webdavFS{
 471                                 collfs:        fs,
 472                                 writing:       writeMethod[r.Method],
 473                                 alwaysReadEOF: r.Method == "PROPFIND",
 474                         },
 475                         LockSystem: h.webdavLS,
 476                         Logger: func(_ *http.Request, err error) {
 477                                 if err != nil {
 478                                         log.Printf("error from webdav handler: %q", err)
 479                                 }
 480                         },
 481                 }
 482                 h.ServeHTTP(w, r)
 483                 return
 484         }
 485
 486         openPath := "/" + strings.Join(targetPath, "/")
 487         if f, err := fs.Open(openPath); os.IsNotExist(err) {
 488                 // Requested non-existent path
 489                 statusCode = http.StatusNotFound
 490         } else if err != nil {
 491                 // Some other (unexpected) error
 492                 statusCode, statusText = http.StatusInternalServerError, err.Error()
 493         } else if stat, err := f.Stat(); err != nil {
 494                 // Can't get Size/IsDir (shouldn't happen with a collectionFS!)
 495                 statusCode, statusText = http.StatusInternalServerError, err.Error()
 496         } else if stat.IsDir() && !strings.HasSuffix(r.URL.Path, "/") {
 497                 // If client requests ".../dirname", redirect to
 498                 // ".../dirname/". This way, relative links in the
 499                 // listing for "dirname" can always be "fnm", never
 500                 // "dirname/fnm".
 501                 h.seeOtherWithCookie(w, r, r.URL.Path+"/", credentialsOK)
 502         } else if stat.IsDir() {
 503                 h.serveDirectory(w, r, collection.Name, fs, openPath, true)
 504         } else {
 505                 http.ServeContent(w, r, basename, stat.ModTime(), f)
 506                 if r.Header.Get("Range") == "" && int64(w.WroteBodyBytes()) != stat.Size() {
 507                         // If we wrote fewer bytes than expected, it's
 508                         // too late to change the real response code
 509                         // or send an error message to the client, but
 510                         // at least we can try to put some useful
 511                         // debugging info in the logs.
 512                         n, err := f.Read(make([]byte, 1024))
 513                         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)
 514
 515                 }
 516         }
 517 }
 518
 519 func (h *handler) serveSiteFS(w http.ResponseWriter, r *http.Request, tokens []string, credentialsOK, attachment bool) {
 520         if len(tokens) == 0 {
 521                 w.Header().Add("WWW-Authenticate", "Basic realm=\"collections\"")
 522                 http.Error(w, http.StatusText(http.StatusUnauthorized), http.StatusUnauthorized)
 523                 return
 524         }
 525         if writeMethod[r.Method] {
 526                 http.Error(w, errReadOnly.Error(), http.StatusMethodNotAllowed)
 527                 return
 528         }
 529         arv := h.clientPool.Get()
 530         if arv == nil {
 531                 http.Error(w, "Pool failed: "+h.clientPool.Err().Error(), http.StatusInternalServerError)
 532                 return
 533         }
 534         defer h.clientPool.Put(arv)
 535         arv.ApiToken = tokens[0]
 536
 537         kc, err := keepclient.MakeKeepClient(arv)
 538         if err != nil {
 539                 http.Error(w, err.Error(), http.StatusInternalServerError)
 540                 return
 541         }
 542         kc.RequestID = r.Header.Get("X-Request-Id")
 543         client := (&arvados.Client{
 544                 APIHost:   arv.ApiServer,
 545                 AuthToken: arv.ApiToken,
 546                 Insecure:  arv.ApiInsecure,
 547         }).WithRequestID(r.Header.Get("X-Request-Id"))
 548         fs := client.SiteFileSystem(kc)
 549         f, err := fs.Open(r.URL.Path)
 550         if os.IsNotExist(err) {
 551                 http.Error(w, err.Error(), http.StatusNotFound)
 552                 return
 553         } else if err != nil {
 554                 http.Error(w, err.Error(), http.StatusInternalServerError)
 555                 return
 556         }
 557         defer f.Close()
 558         if fi, err := f.Stat(); err == nil && fi.IsDir() && r.Method == "GET" {
 559                 if !strings.HasSuffix(r.URL.Path, "/") {
 560                         h.seeOtherWithCookie(w, r, r.URL.Path+"/", credentialsOK)
 561                 } else {
 562                         h.serveDirectory(w, r, fi.Name(), fs, r.URL.Path, false)
 563                 }
 564                 return
 565         }
 566         if r.Method == "GET" {
 567                 _, basename := filepath.Split(r.URL.Path)
 568                 applyContentDispositionHdr(w, r, basename, attachment)
 569         }
 570         wh := webdav.Handler{
 571                 Prefix: "/",
 572                 FileSystem: &webdavFS{
 573                         collfs:        fs,
 574                         writing:       writeMethod[r.Method],
 575                         alwaysReadEOF: r.Method == "PROPFIND",
 576                 },
 577                 LockSystem: h.webdavLS,
 578                 Logger: func(_ *http.Request, err error) {
 579                         if err != nil {
 580                                 log.Printf("error from webdav handler: %q", err)
 581                         }
 582                 },
 583         }
 584         wh.ServeHTTP(w, r)
 585 }
 586
 587 var dirListingTemplate = `<!DOCTYPE HTML>
 588 <HTML><HEAD>
 589   <META name="robots" content="NOINDEX">
 590   <TITLE>{{ .CollectionName }}</TITLE>
 591   <STYLE type="text/css">
 592     body {
 593       margin: 1.5em;
 594     }
 595     pre {
 596       background-color: #D9EDF7;
 597       border-radius: .25em;
 598       padding: .75em;
 599       overflow: auto;
 600     }
 601     .footer p {
 602       font-size: 82%;
 603     }
 604     ul {
 605       padding: 0;
 606     }
 607     ul li {
 608       font-family: monospace;
 609       list-style: none;
 610     }
 611   </STYLE>
 612 </HEAD>
 613 <BODY>
 614
 615 <H1>{{ .CollectionName }}</H1>
 616
 617 <P>This collection of data files is being shared with you through
 618 Arvados.  You can download individual files listed below.  To download
 619 the entire directory tree with wget, try:</P>
 620
 621 <PRE>$ wget --mirror --no-parent --no-host --cut-dirs={{ .StripParts }} https://{{ .Request.Host }}{{ .Request.URL.Path }}</PRE>
 622
 623 <H2>File Listing</H2>
 624
 625 {{if .Files}}
 626 <UL>
 627 {{range .Files}}
 628 {{if .IsDir }}
 629   <LI>{{" " | printf "%15s  " | nbsp}}<A href="{{print "./" .Name}}/">{{.Name}}/</A></LI>
 630 {{else}}
 631   <LI>{{.Size | printf "%15d  " | nbsp}}<A href="{{print "./" .Name}}">{{.Name}}</A></LI>
 632 {{end}}
 633 {{end}}
 634 </UL>
 635 {{else}}
 636 <P>(No files; this collection is empty.)</P>
 637 {{end}}
 638
 639 <HR noshade>
 640 <DIV class="footer">
 641   <P>
 642     About Arvados:
 643     Arvados is a free and open source software bioinformatics platform.
 644     To learn more, visit arvados.org.
 645     Arvados is not responsible for the files listed on this page.
 646   </P>
 647 </DIV>
 648
 649 </BODY>
 650 `
 651
 652 type fileListEnt struct {
 653         Name  string
 654         Size  int64
 655         IsDir bool
 656 }
 657
 658 func (h *handler) serveDirectory(w http.ResponseWriter, r *http.Request, collectionName string, fs http.FileSystem, base string, recurse bool) {
 659         var files []fileListEnt
 660         var walk func(string) error
 661         if !strings.HasSuffix(base, "/") {
 662                 base = base + "/"
 663         }
 664         walk = func(path string) error {
 665                 dirname := base + path
 666                 if dirname != "/" {
 667                         dirname = strings.TrimSuffix(dirname, "/")
 668                 }
 669                 d, err := fs.Open(dirname)
 670                 if err != nil {
 671                         return err
 672                 }
 673                 ents, err := d.Readdir(-1)
 674                 if err != nil {
 675                         return err
 676                 }
 677                 for _, ent := range ents {
 678                         if recurse && ent.IsDir() {
 679                                 err = walk(path + ent.Name() + "/")
 680                                 if err != nil {
 681                                         return err
 682                                 }
 683                         } else {
 684                                 files = append(files, fileListEnt{
 685                                         Name:  path + ent.Name(),
 686                                         Size:  ent.Size(),
 687                                         IsDir: ent.IsDir(),
 688                                 })
 689                         }
 690                 }
 691                 return nil
 692         }
 693         if err := walk(""); err != nil {
 694                 http.Error(w, err.Error(), http.StatusInternalServerError)
 695                 return
 696         }
 697
 698         funcs := template.FuncMap{
 699                 "nbsp": func(s string) template.HTML {
 700                         return template.HTML(strings.Replace(s, " ", "&nbsp;", -1))
 701                 },
 702         }
 703         tmpl, err := template.New("dir").Funcs(funcs).Parse(dirListingTemplate)
 704         if err != nil {
 705                 http.Error(w, err.Error(), http.StatusInternalServerError)
 706                 return
 707         }
 708         sort.Slice(files, func(i, j int) bool {
 709                 return files[i].Name < files[j].Name
 710         })
 711         w.WriteHeader(http.StatusOK)
 712         tmpl.Execute(w, map[string]interface{}{
 713                 "CollectionName": collectionName,
 714                 "Files":          files,
 715                 "Request":        r,
 716                 "StripParts":     strings.Count(strings.TrimRight(r.URL.Path, "/"), "/"),
 717         })
 718 }
 719
 720 func applyContentDispositionHdr(w http.ResponseWriter, r *http.Request, filename string, isAttachment bool) {
 721         disposition := "inline"
 722         if isAttachment {
 723                 disposition = "attachment"
 724         }
 725         if strings.ContainsRune(r.RequestURI, '?') {
 726                 // Help the UA realize that the filename is just
 727                 // "filename.txt", not
 728                 // "filename.txt?disposition=attachment".
 729                 //
 730                 // TODO(TC): Follow advice at RFC 6266 appendix D
 731                 disposition += "; filename=" + strconv.QuoteToASCII(filename)
 732         }
 733         if disposition != "inline" {
 734                 w.Header().Set("Content-Disposition", disposition)
 735         }
 736 }
 737
 738 func (h *handler) seeOtherWithCookie(w http.ResponseWriter, r *http.Request, location string, credentialsOK bool) {
 739         if formToken := r.FormValue("api_token"); formToken != "" {
 740                 if !credentialsOK {
 741                         // It is not safe to copy the provided token
 742                         // into a cookie unless the current vhost
 743                         // (origin) serves only a single collection or
 744                         // we are in TrustAllContent mode.
 745                         w.WriteHeader(http.StatusBadRequest)
 746                         return
 747                 }
 748
 749                 // The HttpOnly flag is necessary to prevent
 750                 // JavaScript code (included in, or loaded by, a page
 751                 // in the collection being served) from employing the
 752                 // user's token beyond reading other files in the same
 753                 // domain, i.e., same collection.
 754                 //
 755                 // The 303 redirect is necessary in the case of a GET
 756                 // request to avoid exposing the token in the Location
 757                 // bar, and in the case of a POST request to avoid
 758                 // raising warnings when the user refreshes the
 759                 // resulting page.
 760                 http.SetCookie(w, &http.Cookie{
 761                         Name:     "arvados_api_token",
 762                         Value:    auth.EncodeTokenCookie([]byte(formToken)),
 763                         Path:     "/",
 764                         HttpOnly: true,
 765                 })
 766         }
 767
 768         // Propagate query parameters (except api_token) from
 769         // the original request.
 770         redirQuery := r.URL.Query()
 771         redirQuery.Del("api_token")
 772
 773         u := r.URL
 774         if location != "" {
 775                 newu, err := u.Parse(location)
 776                 if err != nil {
 777                         w.WriteHeader(http.StatusInternalServerError)
 778                         return
 779                 }
 780                 u = newu
 781         }
 782         redir := (&url.URL{
 783                 Scheme:   r.URL.Scheme,
 784                 Host:     r.Host,
 785                 Path:     u.Path,
 786                 RawQuery: redirQuery.Encode(),
 787         }).String()
 788
 789         w.Header().Add("Location", redir)
 790         w.WriteHeader(http.StatusSeeOther)
 791         io.WriteString(w, `<A href="`)
 792         io.WriteString(w, html.EscapeString(redir))
 793         io.WriteString(w, `">Continue</A>`)
 794 }