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