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.arvados.org/arvados.git/sdk/go/arvados"
  23         "git.arvados.org/arvados.git/sdk/go/arvadosclient"
  24         "git.arvados.org/arvados.git/sdk/go/auth"
  25         "git.arvados.org/arvados.git/sdk/go/ctxlog"
  26         "git.arvados.org/arvados.git/sdk/go/health"
  27         "git.arvados.org/arvados.git/sdk/go/httpserver"
  28         "git.arvados.org/arvados.git/sdk/go/keepclient"
  29         "github.com/sirupsen/logrus"
  30         "golang.org/x/net/webdav"
  31 )
  32
  33 type handler struct {
  34         Config        *Config
  35         MetricsAPI    http.Handler
  36         clientPool    *arvadosclient.ClientPool
  37         setupOnce     sync.Once
  38         healthHandler http.Handler
  39         webdavLS      webdav.LockSystem
  40 }
  41
  42 // parseCollectionIDFromDNSName returns a UUID or PDH if s begins with
  43 // a UUID or URL-encoded PDH; otherwise "".
  44 func parseCollectionIDFromDNSName(s string) string {
  45         // Strip domain.
  46         if i := strings.IndexRune(s, '.'); i >= 0 {
  47                 s = s[:i]
  48         }
  49         // Names like {uuid}--collections.example.com serve the same
  50         // purpose as {uuid}.collections.example.com but can reduce
  51         // cost/effort of using [additional] wildcard certificates.
  52         if i := strings.Index(s, "--"); i >= 0 {
  53                 s = s[:i]
  54         }
  55         if arvadosclient.UUIDMatch(s) {
  56                 return s
  57         }
  58         if pdh := strings.Replace(s, "-", "+", 1); arvadosclient.PDHMatch(pdh) {
  59                 return pdh
  60         }
  61         return ""
  62 }
  63
  64 var urlPDHDecoder = strings.NewReplacer(" ", "+", "-", "+")
  65
  66 var notFoundMessage = "404 Not found\r\n\r\nThe requested path was not found, or you do not have permission to access it.\r"
  67 var unauthorizedMessage = "401 Unauthorized\r\n\r\nA valid Arvados token must be provided to access this resource.\r"
  68
  69 // parseCollectionIDFromURL returns a UUID or PDH if s is a UUID or a
  70 // PDH (even if it is a PDH with "+" replaced by " " or "-");
  71 // otherwise "".
  72 func parseCollectionIDFromURL(s string) string {
  73         if arvadosclient.UUIDMatch(s) {
  74                 return s
  75         }
  76         if pdh := urlPDHDecoder.Replace(s); arvadosclient.PDHMatch(pdh) {
  77                 return pdh
  78         }
  79         return ""
  80 }
  81
  82 func (h *handler) setup() {
  83         // Errors will be handled at the client pool.
  84         arv, _ := arvados.NewClientFromConfig(h.Config.cluster)
  85         h.clientPool = arvadosclient.MakeClientPoolWith(arv)
  86
  87         keepclient.RefreshServiceDiscoveryOnSIGHUP()
  88         keepclient.DefaultBlockCache.MaxBlocks = h.Config.cluster.Collections.WebDAVCache.MaxBlockEntries
  89
  90         h.healthHandler = &health.Handler{
  91                 Token:  h.Config.cluster.ManagementToken,
  92                 Prefix: "/_health/",
  93         }
  94
  95         // Even though we don't accept LOCK requests, every webdav
  96         // handler must have a non-nil LockSystem.
  97         h.webdavLS = &noLockSystem{}
  98 }
  99
 100 func (h *handler) serveStatus(w http.ResponseWriter, r *http.Request) {
 101         json.NewEncoder(w).Encode(struct{ Version string }{version})
 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         logger     logrus.FieldLogger
 112         update     func() error
 113         sentHeader bool
 114         err        error
 115 }
 116
 117 func (uos *updateOnSuccess) Write(p []byte) (int, error) {
 118         if !uos.sentHeader {
 119                 uos.WriteHeader(http.StatusOK)
 120         }
 121         if uos.err != nil {
 122                 return 0, uos.err
 123         }
 124         return uos.ResponseWriter.Write(p)
 125 }
 126
 127 func (uos *updateOnSuccess) WriteHeader(code int) {
 128         if !uos.sentHeader {
 129                 uos.sentHeader = true
 130                 if code >= 200 && code < 400 {
 131                         if uos.err = uos.update(); uos.err != nil {
 132                                 code := http.StatusInternalServerError
 133                                 if err, ok := uos.err.(*arvados.TransactionError); ok {
 134                                         code = err.StatusCode
 135                                 }
 136                                 uos.logger.WithError(uos.err).Errorf("update() returned error type %T, changing response to HTTP %d", uos.err, code)
 137                                 http.Error(uos.ResponseWriter, uos.err.Error(), code)
 138                                 return
 139                         }
 140                 }
 141         }
 142         uos.ResponseWriter.WriteHeader(code)
 143 }
 144
 145 var (
 146         corsAllowHeadersHeader = strings.Join([]string{
 147                 "Authorization", "Content-Type", "Range",
 148                 // WebDAV request headers:
 149                 "Depth", "Destination", "If", "Lock-Token", "Overwrite", "Timeout",
 150         }, ", ")
 151         writeMethod = map[string]bool{
 152                 "COPY":      true,
 153                 "DELETE":    true,
 154                 "LOCK":      true,
 155                 "MKCOL":     true,
 156                 "MOVE":      true,
 157                 "PROPPATCH": true,
 158                 "PUT":       true,
 159                 "RMCOL":     true,
 160                 "UNLOCK":    true,
 161         }
 162         webdavMethod = map[string]bool{
 163                 "COPY":      true,
 164                 "DELETE":    true,
 165                 "LOCK":      true,
 166                 "MKCOL":     true,
 167                 "MOVE":      true,
 168                 "OPTIONS":   true,
 169                 "PROPFIND":  true,
 170                 "PROPPATCH": true,
 171                 "PUT":       true,
 172                 "RMCOL":     true,
 173                 "UNLOCK":    true,
 174         }
 175         browserMethod = map[string]bool{
 176                 "GET":  true,
 177                 "HEAD": true,
 178                 "POST": true,
 179         }
 180         // top-level dirs to serve with siteFS
 181         siteFSDir = map[string]bool{
 182                 "":      true, // root directory
 183                 "by_id": true,
 184                 "users": true,
 185         }
 186 )
 187
 188 func stripDefaultPort(host string) string {
 189         // Will consider port 80 and port 443 to be the same vhost.  I think that's fine.
 190         u := &url.URL{Host: host}
 191         if p := u.Port(); p == "80" || p == "443" {
 192                 return u.Hostname()
 193         } else {
 194                 return host
 195         }
 196 }
 197
 198 // ServeHTTP implements http.Handler.
 199 func (h *handler) ServeHTTP(wOrig http.ResponseWriter, r *http.Request) {
 200         h.setupOnce.Do(h.setup)
 201
 202         if xfp := r.Header.Get("X-Forwarded-Proto"); xfp != "" && xfp != "http" {
 203                 r.URL.Scheme = xfp
 204         }
 205
 206         w := httpserver.WrapResponseWriter(wOrig)
 207
 208         if strings.HasPrefix(r.URL.Path, "/_health/") && r.Method == "GET" {
 209                 h.healthHandler.ServeHTTP(w, r)
 210                 return
 211         }
 212
 213         if method := r.Header.Get("Access-Control-Request-Method"); method != "" && r.Method == "OPTIONS" {
 214                 if !browserMethod[method] && !webdavMethod[method] {
 215                         w.WriteHeader(http.StatusMethodNotAllowed)
 216                         return
 217                 }
 218                 w.Header().Set("Access-Control-Allow-Headers", corsAllowHeadersHeader)
 219                 w.Header().Set("Access-Control-Allow-Methods", "COPY, DELETE, GET, LOCK, MKCOL, MOVE, OPTIONS, POST, PROPFIND, PROPPATCH, PUT, RMCOL, UNLOCK")
 220                 w.Header().Set("Access-Control-Allow-Origin", "*")
 221                 w.Header().Set("Access-Control-Max-Age", "86400")
 222                 return
 223         }
 224
 225         if !browserMethod[r.Method] && !webdavMethod[r.Method] {
 226                 w.WriteHeader(http.StatusMethodNotAllowed)
 227                 return
 228         }
 229
 230         if r.Header.Get("Origin") != "" {
 231                 // Allow simple cross-origin requests without user
 232                 // credentials ("user credentials" as defined by CORS,
 233                 // i.e., cookies, HTTP authentication, and client-side
 234                 // SSL certificates. See
 235                 // http://www.w3.org/TR/cors/#user-credentials).
 236                 w.Header().Set("Access-Control-Allow-Origin", "*")
 237                 w.Header().Set("Access-Control-Expose-Headers", "Content-Range")
 238         }
 239
 240         if h.serveS3(w, r) {
 241                 return
 242         }
 243
 244         pathParts := strings.Split(r.URL.Path[1:], "/")
 245
 246         var stripParts int
 247         var collectionID string
 248         var tokens []string
 249         var reqTokens []string
 250         var pathToken bool
 251         var attachment bool
 252         var useSiteFS bool
 253         credentialsOK := h.Config.cluster.Collections.TrustAllContent
 254         reasonNotAcceptingCredentials := ""
 255
 256         if r.Host != "" && stripDefaultPort(r.Host) == stripDefaultPort(h.Config.cluster.Services.WebDAVDownload.ExternalURL.Host) {
 257                 credentialsOK = true
 258                 attachment = true
 259         } else if r.FormValue("disposition") == "attachment" {
 260                 attachment = true
 261         }
 262
 263         if !credentialsOK {
 264                 reasonNotAcceptingCredentials = fmt.Sprintf("vhost %q does not specify a single collection ID or match Services.WebDAVDownload.ExternalURL %q, and Collections.TrustAllContent is false",
 265                         r.Host, h.Config.cluster.Services.WebDAVDownload.ExternalURL)
 266         }
 267
 268         if collectionID = parseCollectionIDFromDNSName(r.Host); collectionID != "" {
 269                 // http://ID.collections.example/PATH...
 270                 credentialsOK = true
 271         } else if r.URL.Path == "/status.json" {
 272                 h.serveStatus(w, r)
 273                 return
 274         } else if strings.HasPrefix(r.URL.Path, "/metrics") {
 275                 h.MetricsAPI.ServeHTTP(w, r)
 276                 return
 277         } else if siteFSDir[pathParts[0]] {
 278                 useSiteFS = true
 279         } else if len(pathParts) >= 1 && strings.HasPrefix(pathParts[0], "c=") {
 280                 // /c=ID[/PATH...]
 281                 collectionID = parseCollectionIDFromURL(pathParts[0][2:])
 282                 stripParts = 1
 283         } else if len(pathParts) >= 2 && pathParts[0] == "collections" {
 284                 if len(pathParts) >= 4 && pathParts[1] == "download" {
 285                         // /collections/download/ID/TOKEN/PATH...
 286                         collectionID = parseCollectionIDFromURL(pathParts[2])
 287                         tokens = []string{pathParts[3]}
 288                         stripParts = 4
 289                         pathToken = true
 290                 } else {
 291                         // /collections/ID/PATH...
 292                         collectionID = parseCollectionIDFromURL(pathParts[1])
 293                         stripParts = 2
 294                         // This path is only meant to work for public
 295                         // data. Tokens provided with the request are
 296                         // ignored.
 297                         credentialsOK = false
 298                         reasonNotAcceptingCredentials = "the '/collections/UUID/PATH' form only works for public data"
 299                 }
 300         }
 301
 302         if collectionID == "" && !useSiteFS {
 303                 http.Error(w, notFoundMessage, http.StatusNotFound)
 304                 return
 305         }
 306
 307         forceReload := false
 308         if cc := r.Header.Get("Cache-Control"); strings.Contains(cc, "no-cache") || strings.Contains(cc, "must-revalidate") {
 309                 forceReload = true
 310         }
 311
 312         if credentialsOK {
 313                 reqTokens = auth.CredentialsFromRequest(r).Tokens
 314         }
 315
 316         formToken := r.FormValue("api_token")
 317         origin := r.Header.Get("Origin")
 318         cors := origin != "" && !strings.HasSuffix(origin, "://"+r.Host)
 319         safeAjax := cors && (r.Method == http.MethodGet || r.Method == http.MethodHead)
 320         safeAttachment := attachment && r.URL.Query().Get("api_token") == ""
 321         if formToken == "" {
 322                 // No token to use or redact.
 323         } else if safeAjax || safeAttachment {
 324                 // If this is a cross-origin request, the URL won't
 325                 // appear in the browser's address bar, so
 326                 // substituting a clipboard-safe URL is pointless.
 327                 // Redirect-with-cookie wouldn't work anyway, because
 328                 // it's not safe to allow third-party use of our
 329                 // cookie.
 330                 //
 331                 // If we're supplying an attachment, we don't need to
 332                 // convert POST to GET to avoid the "really resubmit
 333                 // form?" problem, so provided the token isn't
 334                 // embedded in the URL, there's no reason to do
 335                 // redirect-with-cookie in this case either.
 336                 reqTokens = append(reqTokens, formToken)
 337         } else if browserMethod[r.Method] {
 338                 // If this is a page view, and the client provided a
 339                 // token via query string or POST body, we must put
 340                 // the token in an HttpOnly cookie, and redirect to an
 341                 // equivalent URL with the query param redacted and
 342                 // method = GET.
 343                 h.seeOtherWithCookie(w, r, "", credentialsOK)
 344                 return
 345         }
 346
 347         if useSiteFS {
 348                 h.serveSiteFS(w, r, reqTokens, credentialsOK, attachment)
 349                 return
 350         }
 351
 352         targetPath := pathParts[stripParts:]
 353         if tokens == nil && len(targetPath) > 0 && strings.HasPrefix(targetPath[0], "t=") {
 354                 // http://ID.example/t=TOKEN/PATH...
 355                 // /c=ID/t=TOKEN/PATH...
 356                 //
 357                 // This form must only be used to pass scoped tokens
 358                 // that give permission for a single collection. See
 359                 // FormValue case above.
 360                 tokens = []string{targetPath[0][2:]}
 361                 pathToken = true
 362                 targetPath = targetPath[1:]
 363                 stripParts++
 364         }
 365
 366         if tokens == nil {
 367                 tokens = reqTokens
 368                 if h.Config.cluster.Users.AnonymousUserToken != "" {
 369                         tokens = append(tokens, h.Config.cluster.Users.AnonymousUserToken)
 370                 }
 371         }
 372
 373         if tokens == nil {
 374                 if !credentialsOK {
 375                         http.Error(w, fmt.Sprintf("Authorization tokens are not accepted here: %v, and no anonymous user token is configured.", reasonNotAcceptingCredentials), http.StatusUnauthorized)
 376                 } else {
 377                         http.Error(w, fmt.Sprintf("No authorization token in request, and no anonymous user token is configured."), http.StatusUnauthorized)
 378                 }
 379                 return
 380         }
 381
 382         if len(targetPath) > 0 && targetPath[0] == "_" {
 383                 // If a collection has a directory called "t=foo" or
 384                 // "_", it can be served at
 385                 // //collections.example/_/t=foo/ or
 386                 // //collections.example/_/_/ respectively:
 387                 // //collections.example/t=foo/ won't work because
 388                 // t=foo will be interpreted as a token "foo".
 389                 targetPath = targetPath[1:]
 390                 stripParts++
 391         }
 392
 393         arv := h.clientPool.Get()
 394         if arv == nil {
 395                 http.Error(w, "client pool error: "+h.clientPool.Err().Error(), http.StatusInternalServerError)
 396                 return
 397         }
 398         defer h.clientPool.Put(arv)
 399
 400         var collection *arvados.Collection
 401         tokenResult := make(map[string]int)
 402         for _, arv.ApiToken = range tokens {
 403                 var err error
 404                 collection, err = h.Config.Cache.Get(arv, collectionID, forceReload)
 405                 if err == nil {
 406                         // Success
 407                         break
 408                 }
 409                 if srvErr, ok := err.(arvadosclient.APIServerError); ok {
 410                         switch srvErr.HttpStatusCode {
 411                         case 404, 401:
 412                                 // Token broken or insufficient to
 413                                 // retrieve collection
 414                                 tokenResult[arv.ApiToken] = srvErr.HttpStatusCode
 415                                 continue
 416                         }
 417                 }
 418                 // Something more serious is wrong
 419                 http.Error(w, "cache error: "+err.Error(), http.StatusInternalServerError)
 420                 return
 421         }
 422         if collection == nil {
 423                 if pathToken || !credentialsOK {
 424                         // Either the URL is a "secret sharing link"
 425                         // that didn't work out (and asking the client
 426                         // for additional credentials would just be
 427                         // confusing), or we don't even accept
 428                         // credentials at this path.
 429                         http.Error(w, notFoundMessage, http.StatusNotFound)
 430                         return
 431                 }
 432                 for _, t := range reqTokens {
 433                         if tokenResult[t] == 404 {
 434                                 // The client provided valid token(s), but the
 435                                 // collection was not found.
 436                                 http.Error(w, notFoundMessage, http.StatusNotFound)
 437                                 return
 438                         }
 439                 }
 440                 // The client's token was invalid (e.g., expired), or
 441                 // the client didn't even provide one.  Propagate the
 442                 // 401 to encourage the client to use a [different]
 443                 // token.
 444                 //
 445                 // TODO(TC): This response would be confusing to
 446                 // someone trying (anonymously) to download public
 447                 // data that has been deleted.  Allow a referrer to
 448                 // provide this context somehow?
 449                 w.Header().Add("WWW-Authenticate", "Basic realm=\"collections\"")
 450                 http.Error(w, unauthorizedMessage, http.StatusUnauthorized)
 451                 return
 452         }
 453
 454         kc, err := keepclient.MakeKeepClient(arv)
 455         if err != nil {
 456                 http.Error(w, "error setting up keep client: "+err.Error(), http.StatusInternalServerError)
 457                 return
 458         }
 459         kc.RequestID = r.Header.Get("X-Request-Id")
 460
 461         var basename string
 462         if len(targetPath) > 0 {
 463                 basename = targetPath[len(targetPath)-1]
 464         }
 465         applyContentDispositionHdr(w, r, basename, attachment)
 466
 467         client := (&arvados.Client{
 468                 APIHost:   arv.ApiServer,
 469                 AuthToken: arv.ApiToken,
 470                 Insecure:  arv.ApiInsecure,
 471         }).WithRequestID(r.Header.Get("X-Request-Id"))
 472
 473         fs, err := collection.FileSystem(client, kc)
 474         if err != nil {
 475                 http.Error(w, "error creating collection filesystem: "+err.Error(), http.StatusInternalServerError)
 476                 return
 477         }
 478
 479         writefs, writeOK := fs.(arvados.CollectionFileSystem)
 480         targetIsPDH := arvadosclient.PDHMatch(collectionID)
 481         if (targetIsPDH || !writeOK) && writeMethod[r.Method] {
 482                 http.Error(w, errReadOnly.Error(), http.StatusMethodNotAllowed)
 483                 return
 484         }
 485
 486         if webdavMethod[r.Method] {
 487                 if writeMethod[r.Method] {
 488                         // Save the collection only if/when all
 489                         // webdav->filesystem operations succeed --
 490                         // and send a 500 error if the modified
 491                         // collection can't be saved.
 492                         w = &updateOnSuccess{
 493                                 ResponseWriter: w,
 494                                 logger:         ctxlog.FromContext(r.Context()),
 495                                 update: func() error {
 496                                         return h.Config.Cache.Update(client, *collection, writefs)
 497                                 }}
 498                 }
 499                 h := webdav.Handler{
 500                         Prefix: "/" + strings.Join(pathParts[:stripParts], "/"),
 501                         FileSystem: &webdavFS{
 502                                 collfs:        fs,
 503                                 writing:       writeMethod[r.Method],
 504                                 alwaysReadEOF: r.Method == "PROPFIND",
 505                         },
 506                         LockSystem: h.webdavLS,
 507                         Logger: func(_ *http.Request, err error) {
 508                                 if err != nil {
 509                                         ctxlog.FromContext(r.Context()).WithError(err).Error("error reported by webdav handler")
 510                                 }
 511                         },
 512                 }
 513                 h.ServeHTTP(w, r)
 514                 return
 515         }
 516
 517         openPath := "/" + strings.Join(targetPath, "/")
 518         f, err := fs.Open(openPath)
 519         if os.IsNotExist(err) {
 520                 // Requested non-existent path
 521                 http.Error(w, notFoundMessage, http.StatusNotFound)
 522                 return
 523         } else if err != nil {
 524                 // Some other (unexpected) error
 525                 http.Error(w, "open: "+err.Error(), http.StatusInternalServerError)
 526                 return
 527         }
 528         defer f.Close()
 529         if stat, err := f.Stat(); err != nil {
 530                 // Can't get Size/IsDir (shouldn't happen with a collectionFS!)
 531                 http.Error(w, "stat: "+err.Error(), http.StatusInternalServerError)
 532         } else if stat.IsDir() && !strings.HasSuffix(r.URL.Path, "/") {
 533                 // If client requests ".../dirname", redirect to
 534                 // ".../dirname/". This way, relative links in the
 535                 // listing for "dirname" can always be "fnm", never
 536                 // "dirname/fnm".
 537                 h.seeOtherWithCookie(w, r, r.URL.Path+"/", credentialsOK)
 538         } else if stat.IsDir() {
 539                 h.serveDirectory(w, r, collection.Name, fs, openPath, true)
 540         } else {
 541                 http.ServeContent(w, r, basename, stat.ModTime(), f)
 542                 if wrote := int64(w.WroteBodyBytes()); wrote != stat.Size() && w.WroteStatus() == http.StatusOK {
 543                         // If we wrote fewer bytes than expected, it's
 544                         // too late to change the real response code
 545                         // or send an error message to the client, but
 546                         // at least we can try to put some useful
 547                         // debugging info in the logs.
 548                         n, err := f.Read(make([]byte, 1024))
 549                         ctxlog.FromContext(r.Context()).Errorf("stat.Size()==%d but only wrote %d bytes; read(1024) returns %d, %v", stat.Size(), wrote, n, err)
 550                 }
 551         }
 552 }
 553
 554 func (h *handler) getClients(reqID, token string) (arv *arvadosclient.ArvadosClient, kc *keepclient.KeepClient, client *arvados.Client, release func(), err error) {
 555         arv = h.clientPool.Get()
 556         if arv == nil {
 557                 err = h.clientPool.Err()
 558                 return
 559         }
 560         release = func() { h.clientPool.Put(arv) }
 561         arv.ApiToken = token
 562         kc, err = keepclient.MakeKeepClient(arv)
 563         if err != nil {
 564                 release()
 565                 return
 566         }
 567         kc.RequestID = reqID
 568         client = (&arvados.Client{
 569                 APIHost:   arv.ApiServer,
 570                 AuthToken: arv.ApiToken,
 571                 Insecure:  arv.ApiInsecure,
 572         }).WithRequestID(reqID)
 573         return
 574 }
 575
 576 func (h *handler) serveSiteFS(w http.ResponseWriter, r *http.Request, tokens []string, credentialsOK, attachment bool) {
 577         if len(tokens) == 0 {
 578                 w.Header().Add("WWW-Authenticate", "Basic realm=\"collections\"")
 579                 http.Error(w, unauthorizedMessage, http.StatusUnauthorized)
 580                 return
 581         }
 582         if writeMethod[r.Method] {
 583                 http.Error(w, errReadOnly.Error(), http.StatusMethodNotAllowed)
 584                 return
 585         }
 586         fs, err := h.Config.Cache.GetSession(tokens[0])
 587         if err != nil {
 588                 http.Error(w, err.Error(), http.StatusInternalServerError)
 589                 return
 590         }
 591         fs.ForwardSlashNameSubstitution(h.Config.cluster.Collections.ForwardSlashNameSubstitution)
 592         f, err := fs.Open(r.URL.Path)
 593         if os.IsNotExist(err) {
 594                 http.Error(w, err.Error(), http.StatusNotFound)
 595                 return
 596         } else if err != nil {
 597                 http.Error(w, err.Error(), http.StatusInternalServerError)
 598                 return
 599         }
 600         defer f.Close()
 601         if fi, err := f.Stat(); err == nil && fi.IsDir() && r.Method == "GET" {
 602                 if !strings.HasSuffix(r.URL.Path, "/") {
 603                         h.seeOtherWithCookie(w, r, r.URL.Path+"/", credentialsOK)
 604                 } else {
 605                         h.serveDirectory(w, r, fi.Name(), fs, r.URL.Path, false)
 606                 }
 607                 return
 608         }
 609         if r.Method == "GET" {
 610                 _, basename := filepath.Split(r.URL.Path)
 611                 applyContentDispositionHdr(w, r, basename, attachment)
 612         }
 613         wh := webdav.Handler{
 614                 Prefix: "/",
 615                 FileSystem: &webdavFS{
 616                         collfs:        fs,
 617                         writing:       writeMethod[r.Method],
 618                         alwaysReadEOF: r.Method == "PROPFIND",
 619                 },
 620                 LockSystem: h.webdavLS,
 621                 Logger: func(_ *http.Request, err error) {
 622                         if err != nil {
 623                                 ctxlog.FromContext(r.Context()).WithError(err).Error("error reported by webdav handler")
 624                         }
 625                 },
 626         }
 627         wh.ServeHTTP(w, r)
 628 }
 629
 630 var dirListingTemplate = `<!DOCTYPE HTML>
 631 <HTML><HEAD>
 632   <META name="robots" content="NOINDEX">
 633   <TITLE>{{ .CollectionName }}</TITLE>
 634   <STYLE type="text/css">
 635     body {
 636       margin: 1.5em;
 637     }
 638     pre {
 639       background-color: #D9EDF7;
 640       border-radius: .25em;
 641       padding: .75em;
 642       overflow: auto;
 643     }
 644     .footer p {
 645       font-size: 82%;
 646     }
 647     ul {
 648       padding: 0;
 649     }
 650     ul li {
 651       font-family: monospace;
 652       list-style: none;
 653     }
 654   </STYLE>
 655 </HEAD>
 656 <BODY>
 657
 658 <H1>{{ .CollectionName }}</H1>
 659
 660 <P>This collection of data files is being shared with you through
 661 Arvados.  You can download individual files listed below.  To download
 662 the entire directory tree with wget, try:</P>
 663
 664 <PRE>$ wget --mirror --no-parent --no-host --cut-dirs={{ .StripParts }} https://{{ .Request.Host }}{{ .Request.URL.Path }}</PRE>
 665
 666 <H2>File Listing</H2>
 667
 668 {{if .Files}}
 669 <UL>
 670 {{range .Files}}
 671 {{if .IsDir }}
 672   <LI>{{" " | printf "%15s  " | nbsp}}<A href="{{print "./" .Name}}/">{{.Name}}/</A></LI>
 673 {{else}}
 674   <LI>{{.Size | printf "%15d  " | nbsp}}<A href="{{print "./" .Name}}">{{.Name}}</A></LI>
 675 {{end}}
 676 {{end}}
 677 </UL>
 678 {{else}}
 679 <P>(No files; this collection is empty.)</P>
 680 {{end}}
 681
 682 <HR noshade>
 683 <DIV class="footer">
 684   <P>
 685     About Arvados:
 686     Arvados is a free and open source software bioinformatics platform.
 687     To learn more, visit arvados.org.
 688     Arvados is not responsible for the files listed on this page.
 689   </P>
 690 </DIV>
 691
 692 </BODY>
 693 `
 694
 695 type fileListEnt struct {
 696         Name  string
 697         Size  int64
 698         IsDir bool
 699 }
 700
 701 func (h *handler) serveDirectory(w http.ResponseWriter, r *http.Request, collectionName string, fs http.FileSystem, base string, recurse bool) {
 702         var files []fileListEnt
 703         var walk func(string) error
 704         if !strings.HasSuffix(base, "/") {
 705                 base = base + "/"
 706         }
 707         walk = func(path string) error {
 708                 dirname := base + path
 709                 if dirname != "/" {
 710                         dirname = strings.TrimSuffix(dirname, "/")
 711                 }
 712                 d, err := fs.Open(dirname)
 713                 if err != nil {
 714                         return err
 715                 }
 716                 ents, err := d.Readdir(-1)
 717                 if err != nil {
 718                         return err
 719                 }
 720                 for _, ent := range ents {
 721                         if recurse && ent.IsDir() {
 722                                 err = walk(path + ent.Name() + "/")
 723                                 if err != nil {
 724                                         return err
 725                                 }
 726                         } else {
 727                                 files = append(files, fileListEnt{
 728                                         Name:  path + ent.Name(),
 729                                         Size:  ent.Size(),
 730                                         IsDir: ent.IsDir(),
 731                                 })
 732                         }
 733                 }
 734                 return nil
 735         }
 736         if err := walk(""); err != nil {
 737                 http.Error(w, "error getting directory listing: "+err.Error(), http.StatusInternalServerError)
 738                 return
 739         }
 740
 741         funcs := template.FuncMap{
 742                 "nbsp": func(s string) template.HTML {
 743                         return template.HTML(strings.Replace(s, " ", "&nbsp;", -1))
 744                 },
 745         }
 746         tmpl, err := template.New("dir").Funcs(funcs).Parse(dirListingTemplate)
 747         if err != nil {
 748                 http.Error(w, "error parsing template: "+err.Error(), http.StatusInternalServerError)
 749                 return
 750         }
 751         sort.Slice(files, func(i, j int) bool {
 752                 return files[i].Name < files[j].Name
 753         })
 754         w.WriteHeader(http.StatusOK)
 755         tmpl.Execute(w, map[string]interface{}{
 756                 "CollectionName": collectionName,
 757                 "Files":          files,
 758                 "Request":        r,
 759                 "StripParts":     strings.Count(strings.TrimRight(r.URL.Path, "/"), "/"),
 760         })
 761 }
 762
 763 func applyContentDispositionHdr(w http.ResponseWriter, r *http.Request, filename string, isAttachment bool) {
 764         disposition := "inline"
 765         if isAttachment {
 766                 disposition = "attachment"
 767         }
 768         if strings.ContainsRune(r.RequestURI, '?') {
 769                 // Help the UA realize that the filename is just
 770                 // "filename.txt", not
 771                 // "filename.txt?disposition=attachment".
 772                 //
 773                 // TODO(TC): Follow advice at RFC 6266 appendix D
 774                 disposition += "; filename=" + strconv.QuoteToASCII(filename)
 775         }
 776         if disposition != "inline" {
 777                 w.Header().Set("Content-Disposition", disposition)
 778         }
 779 }
 780
 781 func (h *handler) seeOtherWithCookie(w http.ResponseWriter, r *http.Request, location string, credentialsOK bool) {
 782         if formToken := r.FormValue("api_token"); formToken != "" {
 783                 if !credentialsOK {
 784                         // It is not safe to copy the provided token
 785                         // into a cookie unless the current vhost
 786                         // (origin) serves only a single collection or
 787                         // we are in TrustAllContent mode.
 788                         http.Error(w, "cannot serve inline content at this URL (possible configuration error; see https://doc.arvados.org/install/install-keep-web.html#dns)", http.StatusBadRequest)
 789                         return
 790                 }
 791
 792                 // The HttpOnly flag is necessary to prevent
 793                 // JavaScript code (included in, or loaded by, a page
 794                 // in the collection being served) from employing the
 795                 // user's token beyond reading other files in the same
 796                 // domain, i.e., same collection.
 797                 //
 798                 // The 303 redirect is necessary in the case of a GET
 799                 // request to avoid exposing the token in the Location
 800                 // bar, and in the case of a POST request to avoid
 801                 // raising warnings when the user refreshes the
 802                 // resulting page.
 803                 http.SetCookie(w, &http.Cookie{
 804                         Name:     "arvados_api_token",
 805                         Value:    auth.EncodeTokenCookie([]byte(formToken)),
 806                         Path:     "/",
 807                         HttpOnly: true,
 808                         SameSite: http.SameSiteLaxMode,
 809                 })
 810         }
 811
 812         // Propagate query parameters (except api_token) from
 813         // the original request.
 814         redirQuery := r.URL.Query()
 815         redirQuery.Del("api_token")
 816
 817         u := r.URL
 818         if location != "" {
 819                 newu, err := u.Parse(location)
 820                 if err != nil {
 821                         http.Error(w, "error resolving redirect target: "+err.Error(), http.StatusInternalServerError)
 822                         return
 823                 }
 824                 u = newu
 825         }
 826         redir := (&url.URL{
 827                 Scheme:   r.URL.Scheme,
 828                 Host:     r.Host,
 829                 Path:     u.Path,
 830                 RawQuery: redirQuery.Encode(),
 831         }).String()
 832
 833         w.Header().Add("Location", redir)
 834         w.WriteHeader(http.StatusSeeOther)
 835         io.WriteString(w, `<A href="`)
 836         io.WriteString(w, html.EscapeString(redir))
 837         io.WriteString(w, `">Continue</A>`)
 838 }