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 keepweb
   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/httpserver"
  27         "git.arvados.org/arvados.git/sdk/go/keepclient"
  28         "github.com/sirupsen/logrus"
  29         "golang.org/x/net/webdav"
  30 )
  31
  32 type handler struct {
  33         Cache      cache
  34         Cluster    *arvados.Cluster
  35         clientPool *arvadosclient.ClientPool
  36         setupOnce  sync.Once
  37         webdavLS   webdav.LockSystem
  38 }
  39
  40 var urlPDHDecoder = strings.NewReplacer(" ", "+", "-", "+")
  41
  42 var notFoundMessage = "404 Not found\r\n\r\nThe requested path was not found, or you do not have permission to access it.\r"
  43 var unauthorizedMessage = "401 Unauthorized\r\n\r\nA valid Arvados token must be provided to access this resource.\r"
  44
  45 // parseCollectionIDFromURL returns a UUID or PDH if s is a UUID or a
  46 // PDH (even if it is a PDH with "+" replaced by " " or "-");
  47 // otherwise "".
  48 func parseCollectionIDFromURL(s string) string {
  49         if arvadosclient.UUIDMatch(s) {
  50                 return s
  51         }
  52         if pdh := urlPDHDecoder.Replace(s); arvadosclient.PDHMatch(pdh) {
  53                 return pdh
  54         }
  55         return ""
  56 }
  57
  58 func (h *handler) setup() {
  59         // Errors will be handled at the client pool.
  60         arv, _ := arvados.NewClientFromConfig(h.Cluster)
  61         h.clientPool = arvadosclient.MakeClientPoolWith(arv)
  62
  63         keepclient.DefaultBlockCache.MaxBlocks = h.Cluster.Collections.WebDAVCache.MaxBlockEntries
  64
  65         // Even though we don't accept LOCK requests, every webdav
  66         // handler must have a non-nil LockSystem.
  67         h.webdavLS = &noLockSystem{}
  68 }
  69
  70 func (h *handler) serveStatus(w http.ResponseWriter, r *http.Request) {
  71         json.NewEncoder(w).Encode(struct{ Version string }{version})
  72 }
  73
  74 // updateOnSuccess wraps httpserver.ResponseWriter. If the handler
  75 // sends an HTTP header indicating success, updateOnSuccess first
  76 // calls the provided update func. If the update func fails, a 500
  77 // response is sent, and the status code and body sent by the handler
  78 // are ignored (all response writes return the update error).
  79 type updateOnSuccess struct {
  80         httpserver.ResponseWriter
  81         logger     logrus.FieldLogger
  82         update     func() error
  83         sentHeader bool
  84         err        error
  85 }
  86
  87 func (uos *updateOnSuccess) Write(p []byte) (int, error) {
  88         if !uos.sentHeader {
  89                 uos.WriteHeader(http.StatusOK)
  90         }
  91         if uos.err != nil {
  92                 return 0, uos.err
  93         }
  94         return uos.ResponseWriter.Write(p)
  95 }
  96
  97 func (uos *updateOnSuccess) WriteHeader(code int) {
  98         if !uos.sentHeader {
  99                 uos.sentHeader = true
 100                 if code >= 200 && code < 400 {
 101                         if uos.err = uos.update(); uos.err != nil {
 102                                 code := http.StatusInternalServerError
 103                                 if err, ok := uos.err.(*arvados.TransactionError); ok {
 104                                         code = err.StatusCode
 105                                 }
 106                                 uos.logger.WithError(uos.err).Errorf("update() returned error type %T, changing response to HTTP %d", uos.err, code)
 107                                 http.Error(uos.ResponseWriter, uos.err.Error(), code)
 108                                 return
 109                         }
 110                 }
 111         }
 112         uos.ResponseWriter.WriteHeader(code)
 113 }
 114
 115 var (
 116         corsAllowHeadersHeader = strings.Join([]string{
 117                 "Authorization", "Content-Type", "Range",
 118                 // WebDAV request headers:
 119                 "Depth", "Destination", "If", "Lock-Token", "Overwrite", "Timeout",
 120         }, ", ")
 121         writeMethod = map[string]bool{
 122                 "COPY":      true,
 123                 "DELETE":    true,
 124                 "LOCK":      true,
 125                 "MKCOL":     true,
 126                 "MOVE":      true,
 127                 "PROPPATCH": true,
 128                 "PUT":       true,
 129                 "RMCOL":     true,
 130                 "UNLOCK":    true,
 131         }
 132         webdavMethod = map[string]bool{
 133                 "COPY":      true,
 134                 "DELETE":    true,
 135                 "LOCK":      true,
 136                 "MKCOL":     true,
 137                 "MOVE":      true,
 138                 "OPTIONS":   true,
 139                 "PROPFIND":  true,
 140                 "PROPPATCH": true,
 141                 "PUT":       true,
 142                 "RMCOL":     true,
 143                 "UNLOCK":    true,
 144         }
 145         browserMethod = map[string]bool{
 146                 "GET":  true,
 147                 "HEAD": true,
 148                 "POST": true,
 149         }
 150         // top-level dirs to serve with siteFS
 151         siteFSDir = map[string]bool{
 152                 "":      true, // root directory
 153                 "by_id": true,
 154                 "users": true,
 155         }
 156 )
 157
 158 func stripDefaultPort(host string) string {
 159         // Will consider port 80 and port 443 to be the same vhost.  I think that's fine.
 160         u := &url.URL{Host: host}
 161         if p := u.Port(); p == "80" || p == "443" {
 162                 return strings.ToLower(u.Hostname())
 163         } else {
 164                 return strings.ToLower(host)
 165         }
 166 }
 167
 168 // CheckHealth implements service.Handler.
 169 func (h *handler) CheckHealth() error {
 170         return nil
 171 }
 172
 173 // Done implements service.Handler.
 174 func (h *handler) Done() <-chan struct{} {
 175         return nil
 176 }
 177
 178 // ServeHTTP implements http.Handler.
 179 func (h *handler) ServeHTTP(wOrig http.ResponseWriter, r *http.Request) {
 180         h.setupOnce.Do(h.setup)
 181
 182         if xfp := r.Header.Get("X-Forwarded-Proto"); xfp != "" && xfp != "http" {
 183                 r.URL.Scheme = xfp
 184         }
 185
 186         w := httpserver.WrapResponseWriter(wOrig)
 187
 188         if method := r.Header.Get("Access-Control-Request-Method"); method != "" && r.Method == "OPTIONS" {
 189                 if !browserMethod[method] && !webdavMethod[method] {
 190                         w.WriteHeader(http.StatusMethodNotAllowed)
 191                         return
 192                 }
 193                 w.Header().Set("Access-Control-Allow-Headers", corsAllowHeadersHeader)
 194                 w.Header().Set("Access-Control-Allow-Methods", "COPY, DELETE, GET, LOCK, MKCOL, MOVE, OPTIONS, POST, PROPFIND, PROPPATCH, PUT, RMCOL, UNLOCK")
 195                 w.Header().Set("Access-Control-Allow-Origin", "*")
 196                 w.Header().Set("Access-Control-Max-Age", "86400")
 197                 return
 198         }
 199
 200         if !browserMethod[r.Method] && !webdavMethod[r.Method] {
 201                 w.WriteHeader(http.StatusMethodNotAllowed)
 202                 return
 203         }
 204
 205         if r.Header.Get("Origin") != "" {
 206                 // Allow simple cross-origin requests without user
 207                 // credentials ("user credentials" as defined by CORS,
 208                 // i.e., cookies, HTTP authentication, and client-side
 209                 // SSL certificates. See
 210                 // http://www.w3.org/TR/cors/#user-credentials).
 211                 w.Header().Set("Access-Control-Allow-Origin", "*")
 212                 w.Header().Set("Access-Control-Expose-Headers", "Content-Range")
 213         }
 214
 215         if h.serveS3(w, r) {
 216                 return
 217         }
 218
 219         pathParts := strings.Split(r.URL.Path[1:], "/")
 220
 221         var stripParts int
 222         var collectionID string
 223         var tokens []string
 224         var reqTokens []string
 225         var pathToken bool
 226         var attachment bool
 227         var useSiteFS bool
 228         credentialsOK := h.Cluster.Collections.TrustAllContent
 229         reasonNotAcceptingCredentials := ""
 230
 231         if r.Host != "" && stripDefaultPort(r.Host) == stripDefaultPort(h.Cluster.Services.WebDAVDownload.ExternalURL.Host) {
 232                 credentialsOK = true
 233                 attachment = true
 234         } else if r.FormValue("disposition") == "attachment" {
 235                 attachment = true
 236         }
 237
 238         if !credentialsOK {
 239                 reasonNotAcceptingCredentials = fmt.Sprintf("vhost %q does not specify a single collection ID or match Services.WebDAVDownload.ExternalURL %q, and Collections.TrustAllContent is false",
 240                         r.Host, h.Cluster.Services.WebDAVDownload.ExternalURL)
 241         }
 242
 243         if collectionID = arvados.CollectionIDFromDNSName(r.Host); collectionID != "" {
 244                 // http://ID.collections.example/PATH...
 245                 credentialsOK = true
 246         } else if r.URL.Path == "/status.json" {
 247                 h.serveStatus(w, r)
 248                 return
 249         } else if siteFSDir[pathParts[0]] {
 250                 useSiteFS = true
 251         } else if len(pathParts) >= 1 && strings.HasPrefix(pathParts[0], "c=") {
 252                 // /c=ID[/PATH...]
 253                 collectionID = parseCollectionIDFromURL(pathParts[0][2:])
 254                 stripParts = 1
 255         } else if len(pathParts) >= 2 && pathParts[0] == "collections" {
 256                 if len(pathParts) >= 4 && pathParts[1] == "download" {
 257                         // /collections/download/ID/TOKEN/PATH...
 258                         collectionID = parseCollectionIDFromURL(pathParts[2])
 259                         tokens = []string{pathParts[3]}
 260                         stripParts = 4
 261                         pathToken = true
 262                 } else {
 263                         // /collections/ID/PATH...
 264                         collectionID = parseCollectionIDFromURL(pathParts[1])
 265                         stripParts = 2
 266                         // This path is only meant to work for public
 267                         // data. Tokens provided with the request are
 268                         // ignored.
 269                         credentialsOK = false
 270                         reasonNotAcceptingCredentials = "the '/collections/UUID/PATH' form only works for public data"
 271                 }
 272         }
 273
 274         if collectionID == "" && !useSiteFS {
 275                 http.Error(w, notFoundMessage, http.StatusNotFound)
 276                 return
 277         }
 278
 279         forceReload := false
 280         if cc := r.Header.Get("Cache-Control"); strings.Contains(cc, "no-cache") || strings.Contains(cc, "must-revalidate") {
 281                 forceReload = true
 282         }
 283
 284         if credentialsOK {
 285                 reqTokens = auth.CredentialsFromRequest(r).Tokens
 286         }
 287
 288         formToken := r.FormValue("api_token")
 289         origin := r.Header.Get("Origin")
 290         cors := origin != "" && !strings.HasSuffix(origin, "://"+r.Host)
 291         safeAjax := cors && (r.Method == http.MethodGet || r.Method == http.MethodHead)
 292         safeAttachment := attachment && r.URL.Query().Get("api_token") == ""
 293         if formToken == "" {
 294                 // No token to use or redact.
 295         } else if safeAjax || safeAttachment {
 296                 // If this is a cross-origin request, the URL won't
 297                 // appear in the browser's address bar, so
 298                 // substituting a clipboard-safe URL is pointless.
 299                 // Redirect-with-cookie wouldn't work anyway, because
 300                 // it's not safe to allow third-party use of our
 301                 // cookie.
 302                 //
 303                 // If we're supplying an attachment, we don't need to
 304                 // convert POST to GET to avoid the "really resubmit
 305                 // form?" problem, so provided the token isn't
 306                 // embedded in the URL, there's no reason to do
 307                 // redirect-with-cookie in this case either.
 308                 reqTokens = append(reqTokens, formToken)
 309         } else if browserMethod[r.Method] {
 310                 // If this is a page view, and the client provided a
 311                 // token via query string or POST body, we must put
 312                 // the token in an HttpOnly cookie, and redirect to an
 313                 // equivalent URL with the query param redacted and
 314                 // method = GET.
 315                 h.seeOtherWithCookie(w, r, "", credentialsOK)
 316                 return
 317         }
 318
 319         if useSiteFS {
 320                 h.serveSiteFS(w, r, reqTokens, credentialsOK, attachment)
 321                 return
 322         }
 323
 324         targetPath := pathParts[stripParts:]
 325         if tokens == nil && len(targetPath) > 0 && strings.HasPrefix(targetPath[0], "t=") {
 326                 // http://ID.example/t=TOKEN/PATH...
 327                 // /c=ID/t=TOKEN/PATH...
 328                 //
 329                 // This form must only be used to pass scoped tokens
 330                 // that give permission for a single collection. See
 331                 // FormValue case above.
 332                 tokens = []string{targetPath[0][2:]}
 333                 pathToken = true
 334                 targetPath = targetPath[1:]
 335                 stripParts++
 336         }
 337
 338         if tokens == nil {
 339                 tokens = reqTokens
 340                 if h.Cluster.Users.AnonymousUserToken != "" {
 341                         tokens = append(tokens, h.Cluster.Users.AnonymousUserToken)
 342                 }
 343         }
 344
 345         if tokens == nil {
 346                 if !credentialsOK {
 347                         http.Error(w, fmt.Sprintf("Authorization tokens are not accepted here: %v, and no anonymous user token is configured.", reasonNotAcceptingCredentials), http.StatusUnauthorized)
 348                 } else {
 349                         http.Error(w, fmt.Sprintf("No authorization token in request, and no anonymous user token is configured."), http.StatusUnauthorized)
 350                 }
 351                 return
 352         }
 353
 354         if len(targetPath) > 0 && targetPath[0] == "_" {
 355                 // If a collection has a directory called "t=foo" or
 356                 // "_", it can be served at
 357                 // //collections.example/_/t=foo/ or
 358                 // //collections.example/_/_/ respectively:
 359                 // //collections.example/t=foo/ won't work because
 360                 // t=foo will be interpreted as a token "foo".
 361                 targetPath = targetPath[1:]
 362                 stripParts++
 363         }
 364
 365         arv := h.clientPool.Get()
 366         if arv == nil {
 367                 http.Error(w, "client pool error: "+h.clientPool.Err().Error(), http.StatusInternalServerError)
 368                 return
 369         }
 370         defer h.clientPool.Put(arv)
 371
 372         var collection *arvados.Collection
 373         var tokenUser *arvados.User
 374         tokenResult := make(map[string]int)
 375         for _, arv.ApiToken = range tokens {
 376                 var err error
 377                 collection, err = h.Cache.Get(arv, collectionID, forceReload)
 378                 if err == nil {
 379                         // Success
 380                         break
 381                 }
 382                 if srvErr, ok := err.(arvadosclient.APIServerError); ok {
 383                         switch srvErr.HttpStatusCode {
 384                         case 404, 401:
 385                                 // Token broken or insufficient to
 386                                 // retrieve collection
 387                                 tokenResult[arv.ApiToken] = srvErr.HttpStatusCode
 388                                 continue
 389                         }
 390                 }
 391                 // Something more serious is wrong
 392                 http.Error(w, "cache error: "+err.Error(), http.StatusInternalServerError)
 393                 return
 394         }
 395         if collection == nil {
 396                 if pathToken || !credentialsOK {
 397                         // Either the URL is a "secret sharing link"
 398                         // that didn't work out (and asking the client
 399                         // for additional credentials would just be
 400                         // confusing), or we don't even accept
 401                         // credentials at this path.
 402                         http.Error(w, notFoundMessage, http.StatusNotFound)
 403                         return
 404                 }
 405                 for _, t := range reqTokens {
 406                         if tokenResult[t] == 404 {
 407                                 // The client provided valid token(s), but the
 408                                 // collection was not found.
 409                                 http.Error(w, notFoundMessage, http.StatusNotFound)
 410                                 return
 411                         }
 412                 }
 413                 // The client's token was invalid (e.g., expired), or
 414                 // the client didn't even provide one.  Propagate the
 415                 // 401 to encourage the client to use a [different]
 416                 // token.
 417                 //
 418                 // TODO(TC): This response would be confusing to
 419                 // someone trying (anonymously) to download public
 420                 // data that has been deleted.  Allow a referrer to
 421                 // provide this context somehow?
 422                 w.Header().Add("WWW-Authenticate", "Basic realm=\"collections\"")
 423                 http.Error(w, unauthorizedMessage, http.StatusUnauthorized)
 424                 return
 425         }
 426
 427         kc, err := keepclient.MakeKeepClient(arv)
 428         if err != nil {
 429                 http.Error(w, "error setting up keep client: "+err.Error(), http.StatusInternalServerError)
 430                 return
 431         }
 432         kc.RequestID = r.Header.Get("X-Request-Id")
 433
 434         var basename string
 435         if len(targetPath) > 0 {
 436                 basename = targetPath[len(targetPath)-1]
 437         }
 438         applyContentDispositionHdr(w, r, basename, attachment)
 439
 440         client := (&arvados.Client{
 441                 APIHost:   arv.ApiServer,
 442                 AuthToken: arv.ApiToken,
 443                 Insecure:  arv.ApiInsecure,
 444         }).WithRequestID(r.Header.Get("X-Request-Id"))
 445
 446         fs, err := collection.FileSystem(client, kc)
 447         if err != nil {
 448                 http.Error(w, "error creating collection filesystem: "+err.Error(), http.StatusInternalServerError)
 449                 return
 450         }
 451
 452         writefs, writeOK := fs.(arvados.CollectionFileSystem)
 453         targetIsPDH := arvadosclient.PDHMatch(collectionID)
 454         if (targetIsPDH || !writeOK) && writeMethod[r.Method] {
 455                 http.Error(w, errReadOnly.Error(), http.StatusMethodNotAllowed)
 456                 return
 457         }
 458
 459         // Check configured permission
 460         _, sess, err := h.Cache.GetSession(arv.ApiToken)
 461         tokenUser, err = h.Cache.GetTokenUser(arv.ApiToken)
 462
 463         if webdavMethod[r.Method] {
 464                 if !h.userPermittedToUploadOrDownload(r.Method, tokenUser) {
 465                         http.Error(w, "Not permitted", http.StatusForbidden)
 466                         return
 467                 }
 468                 h.logUploadOrDownload(r, sess.arvadosclient, nil, strings.Join(targetPath, "/"), collection, tokenUser)
 469
 470                 if writeMethod[r.Method] {
 471                         // Save the collection only if/when all
 472                         // webdav->filesystem operations succeed --
 473                         // and send a 500 error if the modified
 474                         // collection can't be saved.
 475                         w = &updateOnSuccess{
 476                                 ResponseWriter: w,
 477                                 logger:         ctxlog.FromContext(r.Context()),
 478                                 update: func() error {
 479                                         return h.Cache.Update(client, *collection, writefs)
 480                                 }}
 481                 }
 482                 h := webdav.Handler{
 483                         Prefix: "/" + strings.Join(pathParts[:stripParts], "/"),
 484                         FileSystem: &webdavFS{
 485                                 collfs:        fs,
 486                                 writing:       writeMethod[r.Method],
 487                                 alwaysReadEOF: r.Method == "PROPFIND",
 488                         },
 489                         LockSystem: h.webdavLS,
 490                         Logger: func(_ *http.Request, err error) {
 491                                 if err != nil {
 492                                         ctxlog.FromContext(r.Context()).WithError(err).Error("error reported by webdav handler")
 493                                 }
 494                         },
 495                 }
 496                 h.ServeHTTP(w, r)
 497                 return
 498         }
 499
 500         openPath := "/" + strings.Join(targetPath, "/")
 501         f, err := fs.Open(openPath)
 502         if os.IsNotExist(err) {
 503                 // Requested non-existent path
 504                 http.Error(w, notFoundMessage, http.StatusNotFound)
 505                 return
 506         } else if err != nil {
 507                 // Some other (unexpected) error
 508                 http.Error(w, "open: "+err.Error(), http.StatusInternalServerError)
 509                 return
 510         }
 511         defer f.Close()
 512         if stat, err := f.Stat(); err != nil {
 513                 // Can't get Size/IsDir (shouldn't happen with a collectionFS!)
 514                 http.Error(w, "stat: "+err.Error(), http.StatusInternalServerError)
 515         } else if stat.IsDir() && !strings.HasSuffix(r.URL.Path, "/") {
 516                 // If client requests ".../dirname", redirect to
 517                 // ".../dirname/". This way, relative links in the
 518                 // listing for "dirname" can always be "fnm", never
 519                 // "dirname/fnm".
 520                 h.seeOtherWithCookie(w, r, r.URL.Path+"/", credentialsOK)
 521         } else if stat.IsDir() {
 522                 h.serveDirectory(w, r, collection.Name, fs, openPath, true)
 523         } else {
 524                 if !h.userPermittedToUploadOrDownload(r.Method, tokenUser) {
 525                         http.Error(w, "Not permitted", http.StatusForbidden)
 526                         return
 527                 }
 528                 h.logUploadOrDownload(r, sess.arvadosclient, nil, strings.Join(targetPath, "/"), collection, tokenUser)
 529
 530                 http.ServeContent(w, r, basename, stat.ModTime(), f)
 531                 if wrote := int64(w.WroteBodyBytes()); wrote != stat.Size() && w.WroteStatus() == http.StatusOK {
 532                         // If we wrote fewer bytes than expected, it's
 533                         // too late to change the real response code
 534                         // or send an error message to the client, but
 535                         // at least we can try to put some useful
 536                         // debugging info in the logs.
 537                         n, err := f.Read(make([]byte, 1024))
 538                         ctxlog.FromContext(r.Context()).Errorf("stat.Size()==%d but only wrote %d bytes; read(1024) returns %d, %v", stat.Size(), wrote, n, err)
 539                 }
 540         }
 541 }
 542
 543 func (h *handler) getClients(reqID, token string) (arv *arvadosclient.ArvadosClient, kc *keepclient.KeepClient, client *arvados.Client, release func(), err error) {
 544         arv = h.clientPool.Get()
 545         if arv == nil {
 546                 err = h.clientPool.Err()
 547                 return
 548         }
 549         release = func() { h.clientPool.Put(arv) }
 550         arv.ApiToken = token
 551         kc, err = keepclient.MakeKeepClient(arv)
 552         if err != nil {
 553                 release()
 554                 return
 555         }
 556         kc.RequestID = reqID
 557         client = (&arvados.Client{
 558                 APIHost:   arv.ApiServer,
 559                 AuthToken: arv.ApiToken,
 560                 Insecure:  arv.ApiInsecure,
 561         }).WithRequestID(reqID)
 562         return
 563 }
 564
 565 func (h *handler) serveSiteFS(w http.ResponseWriter, r *http.Request, tokens []string, credentialsOK, attachment bool) {
 566         if len(tokens) == 0 {
 567                 w.Header().Add("WWW-Authenticate", "Basic realm=\"collections\"")
 568                 http.Error(w, unauthorizedMessage, http.StatusUnauthorized)
 569                 return
 570         }
 571         if writeMethod[r.Method] {
 572                 http.Error(w, errReadOnly.Error(), http.StatusMethodNotAllowed)
 573                 return
 574         }
 575
 576         fs, sess, err := h.Cache.GetSession(tokens[0])
 577         if err != nil {
 578                 http.Error(w, err.Error(), http.StatusInternalServerError)
 579                 return
 580         }
 581         fs.ForwardSlashNameSubstitution(h.Cluster.Collections.ForwardSlashNameSubstitution)
 582         f, err := fs.Open(r.URL.Path)
 583         if os.IsNotExist(err) {
 584                 http.Error(w, err.Error(), http.StatusNotFound)
 585                 return
 586         } else if err != nil {
 587                 http.Error(w, err.Error(), http.StatusInternalServerError)
 588                 return
 589         }
 590         defer f.Close()
 591         if fi, err := f.Stat(); err == nil && fi.IsDir() && r.Method == "GET" {
 592                 if !strings.HasSuffix(r.URL.Path, "/") {
 593                         h.seeOtherWithCookie(w, r, r.URL.Path+"/", credentialsOK)
 594                 } else {
 595                         h.serveDirectory(w, r, fi.Name(), fs, r.URL.Path, false)
 596                 }
 597                 return
 598         }
 599
 600         tokenUser, err := h.Cache.GetTokenUser(tokens[0])
 601         if !h.userPermittedToUploadOrDownload(r.Method, tokenUser) {
 602                 http.Error(w, "Not permitted", http.StatusForbidden)
 603                 return
 604         }
 605         h.logUploadOrDownload(r, sess.arvadosclient, fs, r.URL.Path, nil, tokenUser)
 606
 607         if r.Method == "GET" {
 608                 _, basename := filepath.Split(r.URL.Path)
 609                 applyContentDispositionHdr(w, r, basename, attachment)
 610         }
 611         wh := webdav.Handler{
 612                 Prefix: "/",
 613                 FileSystem: &webdavFS{
 614                         collfs:        fs,
 615                         writing:       writeMethod[r.Method],
 616                         alwaysReadEOF: r.Method == "PROPFIND",
 617                 },
 618                 LockSystem: h.webdavLS,
 619                 Logger: func(_ *http.Request, err error) {
 620                         if err != nil {
 621                                 ctxlog.FromContext(r.Context()).WithError(err).Error("error reported by webdav handler")
 622                         }
 623                 },
 624         }
 625         wh.ServeHTTP(w, r)
 626 }
 627
 628 var dirListingTemplate = `<!DOCTYPE HTML>
 629 <HTML><HEAD>
 630   <META name="robots" content="NOINDEX">
 631   <TITLE>{{ .CollectionName }}</TITLE>
 632   <STYLE type="text/css">
 633     body {
 634       margin: 1.5em;
 635     }
 636     pre {
 637       background-color: #D9EDF7;
 638       border-radius: .25em;
 639       padding: .75em;
 640       overflow: auto;
 641     }
 642     .footer p {
 643       font-size: 82%;
 644     }
 645     ul {
 646       padding: 0;
 647     }
 648     ul li {
 649       font-family: monospace;
 650       list-style: none;
 651     }
 652   </STYLE>
 653 </HEAD>
 654 <BODY>
 655
 656 <H1>{{ .CollectionName }}</H1>
 657
 658 <P>This collection of data files is being shared with you through
 659 Arvados.  You can download individual files listed below.  To download
 660 the entire directory tree with wget, try:</P>
 661
 662 <PRE>$ wget --mirror --no-parent --no-host --cut-dirs={{ .StripParts }} https://{{ .Request.Host }}{{ .Request.URL.Path }}</PRE>
 663
 664 <H2>File Listing</H2>
 665
 666 {{if .Files}}
 667 <UL>
 668 {{range .Files}}
 669 {{if .IsDir }}
 670   <LI>{{" " | printf "%15s  " | nbsp}}<A href="{{print "./" .Name}}/">{{.Name}}/</A></LI>
 671 {{else}}
 672   <LI>{{.Size | printf "%15d  " | nbsp}}<A href="{{print "./" .Name}}">{{.Name}}</A></LI>
 673 {{end}}
 674 {{end}}
 675 </UL>
 676 {{else}}
 677 <P>(No files; this collection is empty.)</P>
 678 {{end}}
 679
 680 <HR noshade>
 681 <DIV class="footer">
 682   <P>
 683     About Arvados:
 684     Arvados is a free and open source software bioinformatics platform.
 685     To learn more, visit arvados.org.
 686     Arvados is not responsible for the files listed on this page.
 687   </P>
 688 </DIV>
 689
 690 </BODY>
 691 `
 692
 693 type fileListEnt struct {
 694         Name  string
 695         Size  int64
 696         IsDir bool
 697 }
 698
 699 func (h *handler) serveDirectory(w http.ResponseWriter, r *http.Request, collectionName string, fs http.FileSystem, base string, recurse bool) {
 700         var files []fileListEnt
 701         var walk func(string) error
 702         if !strings.HasSuffix(base, "/") {
 703                 base = base + "/"
 704         }
 705         walk = func(path string) error {
 706                 dirname := base + path
 707                 if dirname != "/" {
 708                         dirname = strings.TrimSuffix(dirname, "/")
 709                 }
 710                 d, err := fs.Open(dirname)
 711                 if err != nil {
 712                         return err
 713                 }
 714                 ents, err := d.Readdir(-1)
 715                 if err != nil {
 716                         return err
 717                 }
 718                 for _, ent := range ents {
 719                         if recurse && ent.IsDir() {
 720                                 err = walk(path + ent.Name() + "/")
 721                                 if err != nil {
 722                                         return err
 723                                 }
 724                         } else {
 725                                 files = append(files, fileListEnt{
 726                                         Name:  path + ent.Name(),
 727                                         Size:  ent.Size(),
 728                                         IsDir: ent.IsDir(),
 729                                 })
 730                         }
 731                 }
 732                 return nil
 733         }
 734         if err := walk(""); err != nil {
 735                 http.Error(w, "error getting directory listing: "+err.Error(), http.StatusInternalServerError)
 736                 return
 737         }
 738
 739         funcs := template.FuncMap{
 740                 "nbsp": func(s string) template.HTML {
 741                         return template.HTML(strings.Replace(s, " ", "&nbsp;", -1))
 742                 },
 743         }
 744         tmpl, err := template.New("dir").Funcs(funcs).Parse(dirListingTemplate)
 745         if err != nil {
 746                 http.Error(w, "error parsing template: "+err.Error(), http.StatusInternalServerError)
 747                 return
 748         }
 749         sort.Slice(files, func(i, j int) bool {
 750                 return files[i].Name < files[j].Name
 751         })
 752         w.WriteHeader(http.StatusOK)
 753         tmpl.Execute(w, map[string]interface{}{
 754                 "CollectionName": collectionName,
 755                 "Files":          files,
 756                 "Request":        r,
 757                 "StripParts":     strings.Count(strings.TrimRight(r.URL.Path, "/"), "/"),
 758         })
 759 }
 760
 761 func applyContentDispositionHdr(w http.ResponseWriter, r *http.Request, filename string, isAttachment bool) {
 762         disposition := "inline"
 763         if isAttachment {
 764                 disposition = "attachment"
 765         }
 766         if strings.ContainsRune(r.RequestURI, '?') {
 767                 // Help the UA realize that the filename is just
 768                 // "filename.txt", not
 769                 // "filename.txt?disposition=attachment".
 770                 //
 771                 // TODO(TC): Follow advice at RFC 6266 appendix D
 772                 disposition += "; filename=" + strconv.QuoteToASCII(filename)
 773         }
 774         if disposition != "inline" {
 775                 w.Header().Set("Content-Disposition", disposition)
 776         }
 777 }
 778
 779 func (h *handler) seeOtherWithCookie(w http.ResponseWriter, r *http.Request, location string, credentialsOK bool) {
 780         if formToken := r.FormValue("api_token"); formToken != "" {
 781                 if !credentialsOK {
 782                         // It is not safe to copy the provided token
 783                         // into a cookie unless the current vhost
 784                         // (origin) serves only a single collection or
 785                         // we are in TrustAllContent mode.
 786                         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)
 787                         return
 788                 }
 789
 790                 // The HttpOnly flag is necessary to prevent
 791                 // JavaScript code (included in, or loaded by, a page
 792                 // in the collection being served) from employing the
 793                 // user's token beyond reading other files in the same
 794                 // domain, i.e., same collection.
 795                 //
 796                 // The 303 redirect is necessary in the case of a GET
 797                 // request to avoid exposing the token in the Location
 798                 // bar, and in the case of a POST request to avoid
 799                 // raising warnings when the user refreshes the
 800                 // resulting page.
 801                 http.SetCookie(w, &http.Cookie{
 802                         Name:     "arvados_api_token",
 803                         Value:    auth.EncodeTokenCookie([]byte(formToken)),
 804                         Path:     "/",
 805                         HttpOnly: true,
 806                         SameSite: http.SameSiteLaxMode,
 807                 })
 808         }
 809
 810         // Propagate query parameters (except api_token) from
 811         // the original request.
 812         redirQuery := r.URL.Query()
 813         redirQuery.Del("api_token")
 814
 815         u := r.URL
 816         if location != "" {
 817                 newu, err := u.Parse(location)
 818                 if err != nil {
 819                         http.Error(w, "error resolving redirect target: "+err.Error(), http.StatusInternalServerError)
 820                         return
 821                 }
 822                 u = newu
 823         }
 824         redir := (&url.URL{
 825                 Scheme:   r.URL.Scheme,
 826                 Host:     r.Host,
 827                 Path:     u.Path,
 828                 RawQuery: redirQuery.Encode(),
 829         }).String()
 830
 831         w.Header().Add("Location", redir)
 832         w.WriteHeader(http.StatusSeeOther)
 833         io.WriteString(w, `<A href="`)
 834         io.WriteString(w, html.EscapeString(redir))
 835         io.WriteString(w, `">Continue</A>`)
 836 }
 837
 838 func (h *handler) userPermittedToUploadOrDownload(method string, tokenUser *arvados.User) bool {
 839         var permitDownload bool
 840         var permitUpload bool
 841         if tokenUser != nil && tokenUser.IsAdmin {
 842                 permitUpload = h.Cluster.Collections.WebDAVPermission.Admin.Upload
 843                 permitDownload = h.Cluster.Collections.WebDAVPermission.Admin.Download
 844         } else {
 845                 permitUpload = h.Cluster.Collections.WebDAVPermission.User.Upload
 846                 permitDownload = h.Cluster.Collections.WebDAVPermission.User.Download
 847         }
 848         if (method == "PUT" || method == "POST") && !permitUpload {
 849                 // Disallow operations that upload new files.
 850                 // Permit webdav operations that move existing files around.
 851                 return false
 852         } else if method == "GET" && !permitDownload {
 853                 // Disallow downloading file contents.
 854                 // Permit webdav operations like PROPFIND that retrieve metadata
 855                 // but not file contents.
 856                 return false
 857         }
 858         return true
 859 }
 860
 861 func (h *handler) logUploadOrDownload(
 862         r *http.Request,
 863         client *arvadosclient.ArvadosClient,
 864         fs arvados.CustomFileSystem,
 865         filepath string,
 866         collection *arvados.Collection,
 867         user *arvados.User) {
 868
 869         log := ctxlog.FromContext(r.Context())
 870         props := make(map[string]string)
 871         props["reqPath"] = r.URL.Path
 872         var useruuid string
 873         if user != nil {
 874                 log = log.WithField("user_uuid", user.UUID).
 875                         WithField("user_full_name", user.FullName)
 876                 useruuid = user.UUID
 877         } else {
 878                 useruuid = fmt.Sprintf("%s-tpzed-anonymouspublic", h.Cluster.ClusterID)
 879         }
 880         if collection == nil && fs != nil {
 881                 collection, filepath = h.determineCollection(fs, filepath)
 882         }
 883         if collection != nil {
 884                 log = log.WithField("collection_uuid", collection.UUID).
 885                         WithField("collection_file_path", filepath)
 886                 props["collection_uuid"] = collection.UUID
 887                 props["collection_file_path"] = filepath
 888                 // h.determineCollection populates the collection_uuid prop with the PDH, if
 889                 // this collection is being accessed via PDH. In that case, blank the
 890                 // collection_uuid field so that consumers of the log entries can rely on it
 891                 // being a UUID, or blank. The PDH remains available via the
 892                 // portable_data_hash property.
 893                 if props["collection_uuid"] == collection.PortableDataHash {
 894                         props["collection_uuid"] = ""
 895                 }
 896         }
 897         if r.Method == "PUT" || r.Method == "POST" {
 898                 log.Info("File upload")
 899                 if h.Cluster.Collections.WebDAVLogEvents {
 900                         go func() {
 901                                 lr := arvadosclient.Dict{"log": arvadosclient.Dict{
 902                                         "object_uuid": useruuid,
 903                                         "event_type":  "file_upload",
 904                                         "properties":  props}}
 905                                 err := client.Create("logs", lr, nil)
 906                                 if err != nil {
 907                                         log.WithError(err).Error("Failed to create upload log event on API server")
 908                                 }
 909                         }()
 910                 }
 911         } else if r.Method == "GET" {
 912                 if collection != nil && collection.PortableDataHash != "" {
 913                         log = log.WithField("portable_data_hash", collection.PortableDataHash)
 914                         props["portable_data_hash"] = collection.PortableDataHash
 915                 }
 916                 log.Info("File download")
 917                 if h.Cluster.Collections.WebDAVLogEvents {
 918                         go func() {
 919                                 lr := arvadosclient.Dict{"log": arvadosclient.Dict{
 920                                         "object_uuid": useruuid,
 921                                         "event_type":  "file_download",
 922                                         "properties":  props}}
 923                                 err := client.Create("logs", lr, nil)
 924                                 if err != nil {
 925                                         log.WithError(err).Error("Failed to create download log event on API server")
 926                                 }
 927                         }()
 928                 }
 929         }
 930 }
 931
 932 func (h *handler) determineCollection(fs arvados.CustomFileSystem, path string) (*arvados.Collection, string) {
 933         segments := strings.Split(path, "/")
 934         var i int
 935         for i = 0; i < len(segments); i++ {
 936                 dir := append([]string{}, segments[0:i]...)
 937                 dir = append(dir, ".arvados#collection")
 938                 f, err := fs.OpenFile(strings.Join(dir, "/"), os.O_RDONLY, 0)
 939                 if f != nil {
 940                         defer f.Close()
 941                 }
 942                 if err != nil {
 943                         if !os.IsNotExist(err) {
 944                                 return nil, ""
 945                         }
 946                         continue
 947                 }
 948                 // err is nil so we found it.
 949                 decoder := json.NewDecoder(f)
 950                 var collection arvados.Collection
 951                 err = decoder.Decode(&collection)
 952                 if err != nil {
 953                         return nil, ""
 954                 }
 955                 return &collection, strings.Join(segments[i:], "/")
 956         }
 957         return nil, ""
 958 }