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         "errors"
  10         "fmt"
  11         "html"
  12         "html/template"
  13         "io"
  14         "net/http"
  15         "net/url"
  16         "os"
  17         "sort"
  18         "strconv"
  19         "strings"
  20         "sync"
  21         "time"
  22
  23         "git.arvados.org/arvados.git/lib/cmd"
  24         "git.arvados.org/arvados.git/lib/webdavfs"
  25         "git.arvados.org/arvados.git/sdk/go/arvados"
  26         "git.arvados.org/arvados.git/sdk/go/arvadosclient"
  27         "git.arvados.org/arvados.git/sdk/go/auth"
  28         "git.arvados.org/arvados.git/sdk/go/ctxlog"
  29         "git.arvados.org/arvados.git/sdk/go/httpserver"
  30         "github.com/sirupsen/logrus"
  31         "golang.org/x/net/webdav"
  32 )
  33
  34 type handler struct {
  35         Cache   cache
  36         Cluster *arvados.Cluster
  37         metrics *metrics
  38
  39         lockMtx    sync.Mutex
  40         lock       map[string]*sync.RWMutex
  41         lockTidied time.Time
  42
  43         s3SecretCache         map[string]*cachedS3Secret
  44         s3SecretCacheMtx      sync.Mutex
  45         s3SecretCacheNextTidy time.Time
  46 }
  47
  48 var urlPDHDecoder = strings.NewReplacer(" ", "+", "-", "+")
  49
  50 var notFoundMessage = "Not Found"
  51 var unauthorizedMessage = "401 Unauthorized\n\nA valid Arvados token must be provided to access this resource."
  52
  53 // parseCollectionIDFromURL returns a UUID or PDH if s is a UUID or a
  54 // PDH (even if it is a PDH with "+" replaced by " " or "-");
  55 // otherwise "".
  56 func parseCollectionIDFromURL(s string) string {
  57         if arvadosclient.UUIDMatch(s) {
  58                 return s
  59         }
  60         if pdh := urlPDHDecoder.Replace(s); arvadosclient.PDHMatch(pdh) {
  61                 return pdh
  62         }
  63         return ""
  64 }
  65
  66 func (h *handler) serveStatus(w http.ResponseWriter, r *http.Request) {
  67         json.NewEncoder(w).Encode(struct{ Version string }{cmd.Version.String()})
  68 }
  69
  70 type errorWithHTTPStatus interface {
  71         HTTPStatus() int
  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, an error
  77 // response is sent (using the error's HTTP status or 500 if none),
  78 // and the status code and body sent by the handler are ignored (all
  79 // response writes return the update error).
  80 type updateOnSuccess struct {
  81         httpserver.ResponseWriter
  82         logger     logrus.FieldLogger
  83         update     func() error
  84         sentHeader bool
  85         err        error
  86 }
  87
  88 func (uos *updateOnSuccess) Write(p []byte) (int, error) {
  89         if !uos.sentHeader {
  90                 uos.WriteHeader(http.StatusOK)
  91         }
  92         if uos.err != nil {
  93                 return 0, uos.err
  94         }
  95         return uos.ResponseWriter.Write(p)
  96 }
  97
  98 func (uos *updateOnSuccess) WriteHeader(code int) {
  99         if !uos.sentHeader {
 100                 uos.sentHeader = true
 101                 if code >= 200 && code < 400 {
 102                         if uos.err = uos.update(); uos.err != nil {
 103                                 code := http.StatusInternalServerError
 104                                 if he := errorWithHTTPStatus(nil); errors.As(uos.err, &he) {
 105                                         code = he.HTTPStatus()
 106                                 }
 107                                 uos.logger.WithError(uos.err).Errorf("update() returned %T error, changing response to HTTP %d", uos.err, code)
 108                                 http.Error(uos.ResponseWriter, uos.err.Error(), code)
 109                                 return
 110                         }
 111                 }
 112         }
 113         uos.ResponseWriter.WriteHeader(code)
 114 }
 115
 116 var (
 117         corsAllowHeadersHeader = strings.Join([]string{
 118                 "Authorization", "Content-Type", "Range",
 119                 // WebDAV request headers:
 120                 "Depth", "Destination", "If", "Lock-Token", "Overwrite", "Timeout", "Cache-Control",
 121         }, ", ")
 122         writeMethod = map[string]bool{
 123                 "COPY":      true,
 124                 "DELETE":    true,
 125                 "LOCK":      true,
 126                 "MKCOL":     true,
 127                 "MOVE":      true,
 128                 "PROPPATCH": true,
 129                 "PUT":       true,
 130                 "RMCOL":     true,
 131                 "UNLOCK":    true,
 132         }
 133         webdavMethod = map[string]bool{
 134                 "COPY":      true,
 135                 "DELETE":    true,
 136                 "LOCK":      true,
 137                 "MKCOL":     true,
 138                 "MOVE":      true,
 139                 "OPTIONS":   true,
 140                 "PROPFIND":  true,
 141                 "PROPPATCH": true,
 142                 "PUT":       true,
 143                 "RMCOL":     true,
 144                 "UNLOCK":    true,
 145         }
 146         browserMethod = map[string]bool{
 147                 "GET":  true,
 148                 "HEAD": true,
 149                 "POST": true,
 150         }
 151         // top-level dirs to serve with siteFS
 152         siteFSDir = map[string]bool{
 153                 "":      true, // root directory
 154                 "by_id": true,
 155                 "users": true,
 156         }
 157 )
 158
 159 func stripDefaultPort(host string) string {
 160         // Will consider port 80 and port 443 to be the same vhost.  I think that's fine.
 161         u := &url.URL{Host: host}
 162         if p := u.Port(); p == "80" || p == "443" {
 163                 return strings.ToLower(u.Hostname())
 164         } else {
 165                 return strings.ToLower(host)
 166         }
 167 }
 168
 169 // CheckHealth implements service.Handler.
 170 func (h *handler) CheckHealth() error {
 171         return nil
 172 }
 173
 174 // Done implements service.Handler.
 175 func (h *handler) Done() <-chan struct{} {
 176         return nil
 177 }
 178
 179 // ServeHTTP implements http.Handler.
 180 func (h *handler) ServeHTTP(wOrig http.ResponseWriter, r *http.Request) {
 181         if xfp := r.Header.Get("X-Forwarded-Proto"); xfp != "" && xfp != "http" {
 182                 r.URL.Scheme = xfp
 183         }
 184
 185         wbuffer := newWriteBuffer(wOrig, int(h.Cluster.Collections.WebDAVOutputBuffer))
 186         defer wbuffer.Close()
 187         w := httpserver.WrapResponseWriter(responseWriter{
 188                 Writer:         wbuffer,
 189                 ResponseWriter: wOrig,
 190         })
 191
 192         if r.Method == "OPTIONS" && ServeCORSPreflight(w, r.Header) {
 193                 return
 194         }
 195
 196         if !browserMethod[r.Method] && !webdavMethod[r.Method] {
 197                 w.WriteHeader(http.StatusMethodNotAllowed)
 198                 return
 199         }
 200
 201         if r.Header.Get("Origin") != "" {
 202                 // Allow simple cross-origin requests without user
 203                 // credentials ("user credentials" as defined by CORS,
 204                 // i.e., cookies, HTTP authentication, and client-side
 205                 // SSL certificates. See
 206                 // http://www.w3.org/TR/cors/#user-credentials).
 207                 w.Header().Set("Access-Control-Allow-Origin", "*")
 208                 w.Header().Set("Access-Control-Expose-Headers", "Content-Range")
 209         }
 210
 211         if h.serveS3(w, r) {
 212                 return
 213         }
 214
 215         webdavPrefix := ""
 216         arvPath := r.URL.Path
 217         if prefix := r.Header.Get("X-Webdav-Prefix"); prefix != "" {
 218                 // Enable a proxy (e.g., container log handler in
 219                 // controller) to satisfy a request for path
 220                 // "/foo/bar/baz.txt" using content from
 221                 // "//abc123-4.internal/bar/baz.txt", by adding a
 222                 // request header "X-Webdav-Prefix: /foo"
 223                 if !strings.HasPrefix(arvPath, prefix) {
 224                         http.Error(w, "X-Webdav-Prefix header is not a prefix of the requested path", http.StatusBadRequest)
 225                         return
 226                 }
 227                 arvPath = r.URL.Path[len(prefix):]
 228                 if arvPath == "" {
 229                         arvPath = "/"
 230                 }
 231                 w.Header().Set("Vary", "X-Webdav-Prefix, "+w.Header().Get("Vary"))
 232                 webdavPrefix = prefix
 233         }
 234         pathParts := strings.Split(arvPath[1:], "/")
 235
 236         var stripParts int
 237         var collectionID string
 238         var tokens []string
 239         var reqTokens []string
 240         var pathToken bool
 241         var attachment bool
 242         var useSiteFS bool
 243         credentialsOK := h.Cluster.Collections.TrustAllContent
 244         reasonNotAcceptingCredentials := ""
 245
 246         if r.Host != "" && stripDefaultPort(r.Host) == stripDefaultPort(h.Cluster.Services.WebDAVDownload.ExternalURL.Host) {
 247                 credentialsOK = true
 248                 attachment = true
 249         } else if r.FormValue("disposition") == "attachment" {
 250                 attachment = true
 251         }
 252
 253         if !credentialsOK {
 254                 reasonNotAcceptingCredentials = fmt.Sprintf("vhost %q does not specify a single collection ID or match Services.WebDAVDownload.ExternalURL %q, and Collections.TrustAllContent is false",
 255                         r.Host, h.Cluster.Services.WebDAVDownload.ExternalURL)
 256         }
 257
 258         if collectionID = arvados.CollectionIDFromDNSName(r.Host); collectionID != "" {
 259                 // http://ID.collections.example/PATH...
 260                 credentialsOK = true
 261         } else if r.URL.Path == "/status.json" {
 262                 h.serveStatus(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                         stripParts = 2
 281                         // This path is only meant to work for public
 282                         // data. Tokens provided with the request are
 283                         // ignored.
 284                         credentialsOK = false
 285                         reasonNotAcceptingCredentials = "the '/collections/UUID/PATH' form only works for public data"
 286                 }
 287         }
 288
 289         forceReload := false
 290         if cc := r.Header.Get("Cache-Control"); strings.Contains(cc, "no-cache") || strings.Contains(cc, "must-revalidate") {
 291                 forceReload = true
 292         }
 293
 294         if credentialsOK {
 295                 reqTokens = auth.CredentialsFromRequest(r).Tokens
 296         }
 297
 298         r.ParseForm()
 299         origin := r.Header.Get("Origin")
 300         cors := origin != "" && !strings.HasSuffix(origin, "://"+r.Host)
 301         safeAjax := cors && (r.Method == http.MethodGet || r.Method == http.MethodHead)
 302         // Important distinction: safeAttachment checks whether api_token exists
 303         // as a query parameter. haveFormTokens checks whether api_token exists
 304         // as request form data *or* a query parameter. Different checks are
 305         // necessary because both the request disposition and the location of
 306         // the API token affect whether or not the request needs to be
 307         // redirected. The different branch comments below explain further.
 308         safeAttachment := attachment && !r.URL.Query().Has("api_token")
 309         if formTokens, haveFormTokens := r.Form["api_token"]; !haveFormTokens {
 310                 // No token to use or redact.
 311         } else if safeAjax || safeAttachment {
 312                 // If this is a cross-origin request, the URL won't
 313                 // appear in the browser's address bar, so
 314                 // substituting a clipboard-safe URL is pointless.
 315                 // Redirect-with-cookie wouldn't work anyway, because
 316                 // it's not safe to allow third-party use of our
 317                 // cookie.
 318                 //
 319                 // If we're supplying an attachment, we don't need to
 320                 // convert POST to GET to avoid the "really resubmit
 321                 // form?" problem, so provided the token isn't
 322                 // embedded in the URL, there's no reason to do
 323                 // redirect-with-cookie in this case either.
 324                 for _, tok := range formTokens {
 325                         reqTokens = append(reqTokens, tok)
 326                 }
 327         } else if browserMethod[r.Method] {
 328                 // If this is a page view, and the client provided a
 329                 // token via query string or POST body, we must put
 330                 // the token in an HttpOnly cookie, and redirect to an
 331                 // equivalent URL with the query param redacted and
 332                 // method = GET.
 333                 h.seeOtherWithCookie(w, r, "", credentialsOK)
 334                 return
 335         }
 336
 337         targetPath := pathParts[stripParts:]
 338         if tokens == nil && len(targetPath) > 0 && strings.HasPrefix(targetPath[0], "t=") {
 339                 // http://ID.example/t=TOKEN/PATH...
 340                 // /c=ID/t=TOKEN/PATH...
 341                 //
 342                 // This form must only be used to pass scoped tokens
 343                 // that give permission for a single collection. See
 344                 // FormValue case above.
 345                 tokens = []string{targetPath[0][2:]}
 346                 pathToken = true
 347                 targetPath = targetPath[1:]
 348                 stripParts++
 349         }
 350
 351         fsprefix := ""
 352         if useSiteFS {
 353                 if writeMethod[r.Method] {
 354                         http.Error(w, webdavfs.ErrReadOnly.Error(), http.StatusMethodNotAllowed)
 355                         return
 356                 }
 357                 if len(reqTokens) == 0 {
 358                         w.Header().Add("WWW-Authenticate", "Basic realm=\"collections\"")
 359                         http.Error(w, unauthorizedMessage, http.StatusUnauthorized)
 360                         return
 361                 }
 362                 tokens = reqTokens
 363         } else if collectionID == "" {
 364                 http.Error(w, notFoundMessage, http.StatusNotFound)
 365                 return
 366         } else {
 367                 fsprefix = "by_id/" + collectionID + "/"
 368         }
 369
 370         if src := r.Header.Get("X-Webdav-Source"); strings.HasPrefix(src, "/") && !strings.Contains(src, "//") && !strings.Contains(src, "/../") {
 371                 fsprefix += src[1:]
 372         }
 373
 374         if tokens == nil {
 375                 tokens = reqTokens
 376                 if h.Cluster.Users.AnonymousUserToken != "" {
 377                         tokens = append(tokens, h.Cluster.Users.AnonymousUserToken)
 378                 }
 379         }
 380
 381         if len(targetPath) > 0 && targetPath[0] == "_" {
 382                 // If a collection has a directory called "t=foo" or
 383                 // "_", it can be served at
 384                 // //collections.example/_/t=foo/ or
 385                 // //collections.example/_/_/ respectively:
 386                 // //collections.example/t=foo/ won't work because
 387                 // t=foo will be interpreted as a token "foo".
 388                 targetPath = targetPath[1:]
 389                 stripParts++
 390         }
 391
 392         dirOpenMode := os.O_RDONLY
 393         if writeMethod[r.Method] {
 394                 dirOpenMode = os.O_RDWR
 395         }
 396
 397         var tokenValid bool
 398         var tokenScopeProblem bool
 399         var token string
 400         var tokenUser *arvados.User
 401         var sessionFS arvados.CustomFileSystem
 402         var session *cachedSession
 403         var collectionDir arvados.File
 404         for _, token = range tokens {
 405                 var statusErr errorWithHTTPStatus
 406                 fs, sess, user, err := h.Cache.GetSession(token)
 407                 if errors.As(err, &statusErr) && statusErr.HTTPStatus() == http.StatusUnauthorized {
 408                         // bad token
 409                         continue
 410                 } else if err != nil {
 411                         http.Error(w, "cache error: "+err.Error(), http.StatusInternalServerError)
 412                         return
 413                 }
 414                 if token != h.Cluster.Users.AnonymousUserToken {
 415                         tokenValid = true
 416                 }
 417                 f, err := fs.OpenFile(fsprefix, dirOpenMode, 0)
 418                 if errors.As(err, &statusErr) &&
 419                         statusErr.HTTPStatus() == http.StatusForbidden &&
 420                         token != h.Cluster.Users.AnonymousUserToken {
 421                         // collection id is outside scope of supplied
 422                         // token
 423                         tokenScopeProblem = true
 424                         sess.Release()
 425                         continue
 426                 } else if os.IsNotExist(err) {
 427                         // collection does not exist or is not
 428                         // readable using this token
 429                         sess.Release()
 430                         continue
 431                 } else if err != nil {
 432                         http.Error(w, err.Error(), http.StatusInternalServerError)
 433                         sess.Release()
 434                         return
 435                 }
 436                 defer f.Close()
 437
 438                 collectionDir, sessionFS, session, tokenUser = f, fs, sess, user
 439                 break
 440         }
 441
 442         // releaseSession() is equivalent to session.Release() except
 443         // that it's a no-op if (1) session is nil, or (2) it has
 444         // already been called.
 445         //
 446         // This way, we can do a defer call here to ensure it gets
 447         // called in all code paths, and also call it inline (see
 448         // below) in the cases where we want to release the lock
 449         // before returning.
 450         releaseSession := func() {}
 451         if session != nil {
 452                 var releaseSessionOnce sync.Once
 453                 releaseSession = func() { releaseSessionOnce.Do(func() { session.Release() }) }
 454         }
 455         defer releaseSession()
 456
 457         if forceReload && collectionDir != nil {
 458                 err := collectionDir.Sync()
 459                 if err != nil {
 460                         if he := errorWithHTTPStatus(nil); errors.As(err, &he) {
 461                                 http.Error(w, err.Error(), he.HTTPStatus())
 462                         } else {
 463                                 http.Error(w, err.Error(), http.StatusInternalServerError)
 464                         }
 465                         return
 466                 }
 467         }
 468         if session == nil {
 469                 if pathToken {
 470                         // The URL is a "secret sharing link" that
 471                         // didn't work out.  Asking the client for
 472                         // additional credentials would just be
 473                         // confusing.
 474                         http.Error(w, notFoundMessage, http.StatusNotFound)
 475                         return
 476                 }
 477                 if tokenValid {
 478                         // The client provided valid token(s), but the
 479                         // collection was not found.
 480                         http.Error(w, notFoundMessage, http.StatusNotFound)
 481                         return
 482                 }
 483                 if tokenScopeProblem {
 484                         // The client provided a valid token but
 485                         // fetching a collection returned 401, which
 486                         // means the token scope doesn't permit
 487                         // fetching that collection.
 488                         http.Error(w, notFoundMessage, http.StatusForbidden)
 489                         return
 490                 }
 491                 // The client's token was invalid (e.g., expired), or
 492                 // the client didn't even provide one.  Redirect to
 493                 // workbench2's login-and-redirect-to-download url if
 494                 // this is a browser navigation request. (The redirect
 495                 // flow can't preserve the original method if it's not
 496                 // GET, and doesn't make sense if the UA is a
 497                 // command-line tool, is trying to load an inline
 498                 // image, etc.; in these cases, there's nothing we can
 499                 // do, so return 401 unauthorized.)
 500                 //
 501                 // Note Sec-Fetch-Mode is sent by all non-EOL
 502                 // browsers, except Safari.
 503                 // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Sec-Fetch-Mode
 504                 //
 505                 // TODO(TC): This response would be confusing to
 506                 // someone trying (anonymously) to download public
 507                 // data that has been deleted.  Allow a referrer to
 508                 // provide this context somehow?
 509                 if r.Method == http.MethodGet && r.Header.Get("Sec-Fetch-Mode") == "navigate" {
 510                         target := url.URL(h.Cluster.Services.Workbench2.ExternalURL)
 511                         redirkey := "redirectToPreview"
 512                         if attachment {
 513                                 redirkey = "redirectToDownload"
 514                         }
 515                         callback := "/c=" + collectionID + "/" + strings.Join(targetPath, "/")
 516                         // target.RawQuery = url.Values{redirkey:
 517                         // {target}}.Encode() would be the obvious
 518                         // thing to do here, but wb2 doesn't decode
 519                         // this as a query param -- it takes
 520                         // everything after "${redirkey}=" as the
 521                         // target URL. If we encode "/" as "%2F" etc.,
 522                         // the redirect won't work.
 523                         target.RawQuery = redirkey + "=" + callback
 524                         w.Header().Add("Location", target.String())
 525                         w.WriteHeader(http.StatusSeeOther)
 526                         return
 527                 }
 528                 if !credentialsOK {
 529                         http.Error(w, fmt.Sprintf("Authorization tokens are not accepted here: %v, and no anonymous user token is configured.", reasonNotAcceptingCredentials), http.StatusUnauthorized)
 530                         return
 531                 }
 532                 // If none of the above cases apply, suggest the
 533                 // user-agent (which is either a non-browser agent
 534                 // like wget, or a browser that can't redirect through
 535                 // a login flow) prompt the user for credentials.
 536                 w.Header().Add("WWW-Authenticate", "Basic realm=\"collections\"")
 537                 http.Error(w, unauthorizedMessage, http.StatusUnauthorized)
 538                 return
 539         }
 540
 541         if r.Method == http.MethodGet || r.Method == http.MethodHead {
 542                 targetfnm := fsprefix + strings.Join(pathParts[stripParts:], "/")
 543                 if fi, err := sessionFS.Stat(targetfnm); err == nil && fi.IsDir() {
 544                         releaseSession() // because we won't be writing anything
 545                         if !strings.HasSuffix(r.URL.Path, "/") {
 546                                 h.seeOtherWithCookie(w, r, r.URL.Path+"/", credentialsOK)
 547                         } else {
 548                                 h.serveDirectory(w, r, fi.Name(), sessionFS, targetfnm, !useSiteFS)
 549                         }
 550                         return
 551                 }
 552         }
 553
 554         var basename string
 555         if len(targetPath) > 0 {
 556                 basename = targetPath[len(targetPath)-1]
 557         }
 558         if arvadosclient.PDHMatch(collectionID) && writeMethod[r.Method] {
 559                 http.Error(w, webdavfs.ErrReadOnly.Error(), http.StatusMethodNotAllowed)
 560                 return
 561         }
 562         if !h.userPermittedToUploadOrDownload(r.Method, tokenUser) {
 563                 http.Error(w, "Not permitted", http.StatusForbidden)
 564                 return
 565         }
 566         h.logUploadOrDownload(r, session.arvadosclient, sessionFS, fsprefix+strings.Join(targetPath, "/"), nil, tokenUser)
 567
 568         writing := writeMethod[r.Method]
 569         locker := h.collectionLock(collectionID, writing)
 570         defer locker.Unlock()
 571
 572         if writing {
 573                 // Save the collection only if/when all
 574                 // webdav->filesystem operations succeed --
 575                 // and send a 500 error if the modified
 576                 // collection can't be saved.
 577                 //
 578                 // Perform the write in a separate sitefs, so
 579                 // concurrent read operations on the same
 580                 // collection see the previous saved
 581                 // state. After the write succeeds and the
 582                 // collection record is updated, we reset the
 583                 // session so the updates are visible in
 584                 // subsequent read requests.
 585                 client := session.client.WithRequestID(r.Header.Get("X-Request-Id"))
 586                 sessionFS = client.SiteFileSystem(session.keepclient)
 587                 writingDir, err := sessionFS.OpenFile(fsprefix, os.O_RDONLY, 0)
 588                 if err != nil {
 589                         http.Error(w, err.Error(), http.StatusInternalServerError)
 590                         return
 591                 }
 592                 defer writingDir.Close()
 593                 w = &updateOnSuccess{
 594                         ResponseWriter: w,
 595                         logger:         ctxlog.FromContext(r.Context()),
 596                         update: func() error {
 597                                 err := writingDir.Sync()
 598                                 var te arvados.TransactionError
 599                                 if errors.As(err, &te) {
 600                                         err = te
 601                                 }
 602                                 if err != nil {
 603                                         return err
 604                                 }
 605                                 // Sync the changes to the persistent
 606                                 // sessionfs for this token.
 607                                 snap, err := writingDir.Snapshot()
 608                                 if err != nil {
 609                                         return err
 610                                 }
 611                                 collectionDir.Splice(snap)
 612                                 return nil
 613                         }}
 614         } else {
 615                 // When writing, we need to block session renewal
 616                 // until we're finished, in order to guarantee the
 617                 // effect of the write is visible in future responses.
 618                 // But if we're not writing, we can release the lock
 619                 // early.  This enables us to keep renewing sessions
 620                 // and processing more requests even if a slow client
 621                 // takes a long time to download a large file.
 622                 releaseSession()
 623         }
 624         if r.Method == http.MethodGet {
 625                 applyContentDispositionHdr(w, r, basename, attachment)
 626         }
 627         if webdavPrefix == "" {
 628                 webdavPrefix = "/" + strings.Join(pathParts[:stripParts], "/")
 629         }
 630         wh := &webdav.Handler{
 631                 Prefix: webdavPrefix,
 632                 FileSystem: &webdavfs.FS{
 633                         FileSystem:    sessionFS,
 634                         Prefix:        fsprefix,
 635                         Writing:       writeMethod[r.Method],
 636                         AlwaysReadEOF: r.Method == "PROPFIND",
 637                 },
 638                 LockSystem: webdavfs.NoLockSystem,
 639                 Logger: func(r *http.Request, err error) {
 640                         if err != nil && !os.IsNotExist(err) {
 641                                 ctxlog.FromContext(r.Context()).WithError(err).Error("error reported by webdav handler")
 642                         }
 643                 },
 644         }
 645         h.metrics.track(wh, w, r)
 646         if r.Method == http.MethodGet && w.WroteStatus() == http.StatusOK {
 647                 wrote := int64(w.WroteBodyBytes())
 648                 fnm := strings.Join(pathParts[stripParts:], "/")
 649                 fi, err := wh.FileSystem.Stat(r.Context(), fnm)
 650                 if err == nil && fi.Size() != wrote {
 651                         var n int
 652                         f, err := wh.FileSystem.OpenFile(r.Context(), fnm, os.O_RDONLY, 0)
 653                         if err == nil {
 654                                 n, err = f.Read(make([]byte, 1024))
 655                                 f.Close()
 656                         }
 657                         ctxlog.FromContext(r.Context()).Errorf("stat.Size()==%d but only wrote %d bytes; read(1024) returns %d, %v", fi.Size(), wrote, n, err)
 658                 }
 659         }
 660 }
 661
 662 var dirListingTemplate = `<!DOCTYPE HTML>
 663 <HTML><HEAD>
 664   <META name="robots" content="NOINDEX">
 665   <TITLE>{{ .CollectionName }}</TITLE>
 666   <STYLE type="text/css">
 667     body {
 668       margin: 1.5em;
 669     }
 670     pre {
 671       background-color: #D9EDF7;
 672       border-radius: .25em;
 673       padding: .75em;
 674       overflow: auto;
 675     }
 676     .footer p {
 677       font-size: 82%;
 678     }
 679     hr {
 680       border: 1px solid #808080;
 681     }
 682     ul {
 683       padding: 0;
 684     }
 685     ul li {
 686       font-family: monospace;
 687       list-style: none;
 688     }
 689   </STYLE>
 690 </HEAD>
 691 <BODY>
 692
 693 <H1>{{ .CollectionName }}</H1>
 694
 695 <P>This collection of data files is being shared with you through
 696 Arvados.  You can download individual files listed below.  To download
 697 the entire directory tree with <CODE>wget</CODE>, try:</P>
 698
 699 <PRE id="wget-example">$ wget --mirror --no-parent --no-host --cut-dirs={{ .StripParts }} {{ .QuotedUrlForWget }}</PRE>
 700
 701 <H2>File Listing</H2>
 702
 703 {{if .Files}}
 704 <UL>
 705 {{range .Files}}
 706 {{if .IsDir }}
 707   <LI>{{" " | printf "%15s  " | nbsp}}<A class="item" href="{{ .Href }}/">{{ .Name }}/</A></LI>
 708 {{else}}
 709   <LI>{{.Size | printf "%15d  " | nbsp}}<A class="item" href="{{ .Href }}">{{ .Name }}</A></LI>
 710 {{end}}
 711 {{end}}
 712 </UL>
 713 {{else}}
 714 <P>(No files; this collection is empty.)</P>
 715 {{end}}
 716
 717 <HR>
 718 <DIV class="footer">
 719   <P>
 720     About Arvados:
 721     Arvados is a free and open source software bioinformatics platform.
 722     To learn more, visit arvados.org.
 723     Arvados is not responsible for the files listed on this page.
 724   </P>
 725 </DIV>
 726
 727 </BODY>
 728 </HTML>
 729 `
 730
 731 type fileListEnt struct {
 732         Name  string
 733         Href  string
 734         Size  int64
 735         IsDir bool
 736 }
 737
 738 // Given a filesystem path like `foo/"bar baz"`, return an escaped
 739 // (percent-encoded) relative path like `./foo/%22bar%20%baz%22`.
 740 //
 741 // Note the result may contain html-unsafe characters like '&'. These
 742 // will be handled separately by the HTML templating engine as needed.
 743 func relativeHref(path string) string {
 744         u := &url.URL{Path: path}
 745         return "./" + u.EscapedPath()
 746 }
 747
 748 // Return a shell-quoted URL suitable for pasting to a command line
 749 // ("wget ...") to repeat the given HTTP request.
 750 func makeQuotedUrlForWget(r *http.Request) string {
 751         scheme := r.Header.Get("X-Forwarded-Proto")
 752         if scheme == "http" || scheme == "https" {
 753                 // use protocol reported by load balancer / proxy
 754         } else if r.TLS != nil {
 755                 scheme = "https"
 756         } else {
 757                 scheme = "http"
 758         }
 759         p := r.URL.EscapedPath()
 760         // An escaped path may still contain single quote chars, which
 761         // would interfere with our shell quoting. Avoid this by
 762         // escaping them as %27.
 763         return fmt.Sprintf("'%s://%s%s'", scheme, r.Host, strings.Replace(p, "'", "%27", -1))
 764 }
 765
 766 func (h *handler) serveDirectory(w http.ResponseWriter, r *http.Request, collectionName string, fs http.FileSystem, base string, recurse bool) {
 767         var files []fileListEnt
 768         var walk func(string) error
 769         if !strings.HasSuffix(base, "/") {
 770                 base = base + "/"
 771         }
 772         walk = func(path string) error {
 773                 dirname := base + path
 774                 if dirname != "/" {
 775                         dirname = strings.TrimSuffix(dirname, "/")
 776                 }
 777                 d, err := fs.Open(dirname)
 778                 if err != nil {
 779                         return err
 780                 }
 781                 ents, err := d.Readdir(-1)
 782                 if err != nil {
 783                         return err
 784                 }
 785                 for _, ent := range ents {
 786                         if recurse && ent.IsDir() {
 787                                 err = walk(path + ent.Name() + "/")
 788                                 if err != nil {
 789                                         return err
 790                                 }
 791                         } else {
 792                                 listingName := path + ent.Name()
 793                                 files = append(files, fileListEnt{
 794                                         Name:  listingName,
 795                                         Href:  relativeHref(listingName),
 796                                         Size:  ent.Size(),
 797                                         IsDir: ent.IsDir(),
 798                                 })
 799                         }
 800                 }
 801                 return nil
 802         }
 803         if err := walk(""); err != nil {
 804                 http.Error(w, "error getting directory listing: "+err.Error(), http.StatusInternalServerError)
 805                 return
 806         }
 807
 808         funcs := template.FuncMap{
 809                 "nbsp": func(s string) template.HTML {
 810                         return template.HTML(strings.Replace(s, " ", "&nbsp;", -1))
 811                 },
 812         }
 813         tmpl, err := template.New("dir").Funcs(funcs).Parse(dirListingTemplate)
 814         if err != nil {
 815                 http.Error(w, "error parsing template: "+err.Error(), http.StatusInternalServerError)
 816                 return
 817         }
 818         sort.Slice(files, func(i, j int) bool {
 819                 return files[i].Name < files[j].Name
 820         })
 821         w.WriteHeader(http.StatusOK)
 822         tmpl.Execute(w, map[string]interface{}{
 823                 "CollectionName":   collectionName,
 824                 "Files":            files,
 825                 "Request":          r,
 826                 "StripParts":       strings.Count(strings.TrimRight(r.URL.Path, "/"), "/"),
 827                 "QuotedUrlForWget": makeQuotedUrlForWget(r),
 828         })
 829 }
 830
 831 func applyContentDispositionHdr(w http.ResponseWriter, r *http.Request, filename string, isAttachment bool) {
 832         disposition := "inline"
 833         if isAttachment {
 834                 disposition = "attachment"
 835         }
 836         if strings.ContainsRune(r.RequestURI, '?') {
 837                 // Help the UA realize that the filename is just
 838                 // "filename.txt", not
 839                 // "filename.txt?disposition=attachment".
 840                 //
 841                 // TODO(TC): Follow advice at RFC 6266 appendix D
 842                 disposition += "; filename=" + strconv.QuoteToASCII(filename)
 843         }
 844         if disposition != "inline" {
 845                 w.Header().Set("Content-Disposition", disposition)
 846         }
 847 }
 848
 849 func (h *handler) seeOtherWithCookie(w http.ResponseWriter, r *http.Request, location string, credentialsOK bool) {
 850         if formTokens, haveFormTokens := r.Form["api_token"]; haveFormTokens {
 851                 if !credentialsOK {
 852                         // It is not safe to copy the provided token
 853                         // into a cookie unless the current vhost
 854                         // (origin) serves only a single collection or
 855                         // we are in TrustAllContent mode.
 856                         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)
 857                         return
 858                 }
 859
 860                 // The HttpOnly flag is necessary to prevent
 861                 // JavaScript code (included in, or loaded by, a page
 862                 // in the collection being served) from employing the
 863                 // user's token beyond reading other files in the same
 864                 // domain, i.e., same collection.
 865                 //
 866                 // The 303 redirect is necessary in the case of a GET
 867                 // request to avoid exposing the token in the Location
 868                 // bar, and in the case of a POST request to avoid
 869                 // raising warnings when the user refreshes the
 870                 // resulting page.
 871                 for _, tok := range formTokens {
 872                         if tok == "" {
 873                                 continue
 874                         }
 875                         http.SetCookie(w, &http.Cookie{
 876                                 Name:     "arvados_api_token",
 877                                 Value:    auth.EncodeTokenCookie([]byte(tok)),
 878                                 Path:     "/",
 879                                 HttpOnly: true,
 880                                 SameSite: http.SameSiteLaxMode,
 881                         })
 882                         break
 883                 }
 884         }
 885
 886         // Propagate query parameters (except api_token) from
 887         // the original request.
 888         redirQuery := r.URL.Query()
 889         redirQuery.Del("api_token")
 890
 891         u := r.URL
 892         if location != "" {
 893                 newu, err := u.Parse(location)
 894                 if err != nil {
 895                         http.Error(w, "error resolving redirect target: "+err.Error(), http.StatusInternalServerError)
 896                         return
 897                 }
 898                 u = newu
 899         }
 900         redir := (&url.URL{
 901                 Scheme:   r.URL.Scheme,
 902                 Host:     r.Host,
 903                 Path:     u.Path,
 904                 RawQuery: redirQuery.Encode(),
 905         }).String()
 906
 907         w.Header().Add("Location", redir)
 908         w.WriteHeader(http.StatusSeeOther)
 909         io.WriteString(w, `<A href="`)
 910         io.WriteString(w, html.EscapeString(redir))
 911         io.WriteString(w, `">Continue</A>`)
 912 }
 913
 914 func (h *handler) userPermittedToUploadOrDownload(method string, tokenUser *arvados.User) bool {
 915         var permitDownload bool
 916         var permitUpload bool
 917         if tokenUser != nil && tokenUser.IsAdmin {
 918                 permitUpload = h.Cluster.Collections.WebDAVPermission.Admin.Upload
 919                 permitDownload = h.Cluster.Collections.WebDAVPermission.Admin.Download
 920         } else {
 921                 permitUpload = h.Cluster.Collections.WebDAVPermission.User.Upload
 922                 permitDownload = h.Cluster.Collections.WebDAVPermission.User.Download
 923         }
 924         if (method == "PUT" || method == "POST") && !permitUpload {
 925                 // Disallow operations that upload new files.
 926                 // Permit webdav operations that move existing files around.
 927                 return false
 928         } else if method == "GET" && !permitDownload {
 929                 // Disallow downloading file contents.
 930                 // Permit webdav operations like PROPFIND that retrieve metadata
 931                 // but not file contents.
 932                 return false
 933         }
 934         return true
 935 }
 936
 937 func (h *handler) logUploadOrDownload(
 938         r *http.Request,
 939         client *arvadosclient.ArvadosClient,
 940         fs arvados.CustomFileSystem,
 941         filepath string,
 942         collection *arvados.Collection,
 943         user *arvados.User) {
 944
 945         log := ctxlog.FromContext(r.Context())
 946         props := make(map[string]string)
 947         props["reqPath"] = r.URL.Path
 948         var useruuid string
 949         if user != nil {
 950                 log = log.WithField("user_uuid", user.UUID).
 951                         WithField("user_full_name", user.FullName)
 952                 useruuid = user.UUID
 953         } else {
 954                 useruuid = fmt.Sprintf("%s-tpzed-anonymouspublic", h.Cluster.ClusterID)
 955         }
 956         if collection == nil && fs != nil {
 957                 collection, filepath = h.determineCollection(fs, filepath)
 958         }
 959         if collection != nil {
 960                 log = log.WithField("collection_file_path", filepath)
 961                 props["collection_file_path"] = filepath
 962                 // h.determineCollection populates the collection_uuid
 963                 // prop with the PDH, if this collection is being
 964                 // accessed via PDH. For logging, we use a different
 965                 // field depending on whether it's a UUID or PDH.
 966                 if len(collection.UUID) > 32 {
 967                         log = log.WithField("portable_data_hash", collection.UUID)
 968                         props["portable_data_hash"] = collection.UUID
 969                 } else {
 970                         log = log.WithField("collection_uuid", collection.UUID)
 971                         props["collection_uuid"] = collection.UUID
 972                 }
 973         }
 974         if r.Method == "PUT" || r.Method == "POST" {
 975                 log.Info("File upload")
 976                 if h.Cluster.Collections.WebDAVLogEvents {
 977                         go func() {
 978                                 lr := arvadosclient.Dict{"log": arvadosclient.Dict{
 979                                         "object_uuid": useruuid,
 980                                         "event_type":  "file_upload",
 981                                         "properties":  props}}
 982                                 err := client.Create("logs", lr, nil)
 983                                 if err != nil {
 984                                         log.WithError(err).Error("Failed to create upload log event on API server")
 985                                 }
 986                         }()
 987                 }
 988         } else if r.Method == "GET" {
 989                 if collection != nil && collection.PortableDataHash != "" {
 990                         log = log.WithField("portable_data_hash", collection.PortableDataHash)
 991                         props["portable_data_hash"] = collection.PortableDataHash
 992                 }
 993                 log.Info("File download")
 994                 if h.Cluster.Collections.WebDAVLogEvents {
 995                         go func() {
 996                                 lr := arvadosclient.Dict{"log": arvadosclient.Dict{
 997                                         "object_uuid": useruuid,
 998                                         "event_type":  "file_download",
 999                                         "properties":  props}}
1000                                 err := client.Create("logs", lr, nil)
1001                                 if err != nil {
1002                                         log.WithError(err).Error("Failed to create download log event on API server")
1003                                 }
1004                         }()
1005                 }
1006         }
1007 }
1008
1009 func (h *handler) determineCollection(fs arvados.CustomFileSystem, path string) (*arvados.Collection, string) {
1010         target := strings.TrimSuffix(path, "/")
1011         for cut := len(target); cut >= 0; cut = strings.LastIndexByte(target, '/') {
1012                 target = target[:cut]
1013                 fi, err := fs.Stat(target)
1014                 if os.IsNotExist(err) {
1015                         // creating a new file/dir, or download
1016                         // destined to fail
1017                         continue
1018                 } else if err != nil {
1019                         return nil, ""
1020                 }
1021                 switch src := fi.Sys().(type) {
1022                 case *arvados.Collection:
1023                         return src, strings.TrimPrefix(path[len(target):], "/")
1024                 case *arvados.Group:
1025                         return nil, ""
1026                 default:
1027                         if _, ok := src.(error); ok {
1028                                 return nil, ""
1029                         }
1030                 }
1031         }
1032         return nil, ""
1033 }
1034
1035 var lockTidyInterval = time.Minute * 10
1036
1037 // Lock the specified collection for reading or writing. Caller must
1038 // call Unlock() on the returned Locker when the operation is
1039 // finished.
1040 func (h *handler) collectionLock(collectionID string, writing bool) sync.Locker {
1041         h.lockMtx.Lock()
1042         defer h.lockMtx.Unlock()
1043         if time.Since(h.lockTidied) > lockTidyInterval {
1044                 // Periodically delete all locks that aren't in use.
1045                 h.lockTidied = time.Now()
1046                 for id, locker := range h.lock {
1047                         if locker.TryLock() {
1048                                 locker.Unlock()
1049                                 delete(h.lock, id)
1050                         }
1051                 }
1052         }
1053         locker := h.lock[collectionID]
1054         if locker == nil {
1055                 locker = new(sync.RWMutex)
1056                 if h.lock == nil {
1057                         h.lock = map[string]*sync.RWMutex{}
1058                 }
1059                 h.lock[collectionID] = locker
1060         }
1061         if writing {
1062                 locker.Lock()
1063                 return locker
1064         } else {
1065                 locker.RLock()
1066                 return locker.RLocker()
1067         }
1068 }
1069
1070 func ServeCORSPreflight(w http.ResponseWriter, header http.Header) bool {
1071         method := header.Get("Access-Control-Request-Method")
1072         if method == "" {
1073                 return false
1074         }
1075         if !browserMethod[method] && !webdavMethod[method] {
1076                 w.WriteHeader(http.StatusMethodNotAllowed)
1077                 return true
1078         }
1079         w.Header().Set("Access-Control-Allow-Headers", corsAllowHeadersHeader)
1080         w.Header().Set("Access-Control-Allow-Methods", "COPY, DELETE, GET, LOCK, MKCOL, MOVE, OPTIONS, POST, PROPFIND, PROPPATCH, PUT, RMCOL, UNLOCK")
1081         w.Header().Set("Access-Control-Allow-Origin", "*")
1082         w.Header().Set("Access-Control-Max-Age", "86400")
1083         return true
1084 }