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