services/keep-web/s3.go

   1 // Copyright (C) The Arvados Authors. All rights reserved.
   2 //
   3 // SPDX-License-Identifier: AGPL-3.0
   4
   5 package main
   6
   7 import (
   8         "crypto/hmac"
   9         "crypto/sha256"
  10         "encoding/xml"
  11         "errors"
  12         "fmt"
  13         "hash"
  14         "io"
  15         "net/http"
  16         "net/url"
  17         "os"
  18         "path/filepath"
  19         "regexp"
  20         "sort"
  21         "strconv"
  22         "strings"
  23         "time"
  24
  25         "git.arvados.org/arvados.git/sdk/go/arvados"
  26         "git.arvados.org/arvados.git/sdk/go/ctxlog"
  27         "github.com/AdRoll/goamz/s3"
  28 )
  29
  30 const (
  31         s3MaxKeys       = 1000
  32         s3SignAlgorithm = "AWS4-HMAC-SHA256"
  33         s3MaxClockSkew  = 5 * time.Minute
  34 )
  35
  36 func hmacstring(msg string, key []byte) []byte {
  37         h := hmac.New(sha256.New, key)
  38         io.WriteString(h, msg)
  39         return h.Sum(nil)
  40 }
  41
  42 func hashdigest(h hash.Hash, payload string) string {
  43         io.WriteString(h, payload)
  44         return fmt.Sprintf("%x", h.Sum(nil))
  45 }
  46
  47 // Signing key for given secret key and request attrs.
  48 func s3signatureKey(key, datestamp, regionName, serviceName string) []byte {
  49         return hmacstring("aws4_request",
  50                 hmacstring(serviceName,
  51                         hmacstring(regionName,
  52                                 hmacstring(datestamp, []byte("AWS4"+key)))))
  53 }
  54
  55 // Canonical query string for S3 V4 signature: sorted keys, spaces
  56 // escaped as %20 instead of +, keyvalues joined with &.
  57 func s3querystring(u *url.URL) string {
  58         keys := make([]string, 0, len(u.Query()))
  59         values := make(map[string]string, len(u.Query()))
  60         for k, vs := range u.Query() {
  61                 k = strings.Replace(url.QueryEscape(k), "+", "%20", -1)
  62                 keys = append(keys, k)
  63                 for _, v := range vs {
  64                         v = strings.Replace(url.QueryEscape(v), "+", "%20", -1)
  65                         if values[k] != "" {
  66                                 values[k] += "&"
  67                         }
  68                         values[k] += k + "=" + v
  69                 }
  70         }
  71         sort.Strings(keys)
  72         for i, k := range keys {
  73                 keys[i] = values[k]
  74         }
  75         return strings.Join(keys, "&")
  76 }
  77
  78 var reMultipleSlashChars = regexp.MustCompile(`//+`)
  79
  80 func s3stringToSign(alg, scope, signedHeaders string, r *http.Request) (string, error) {
  81         timefmt, timestr := "20060102T150405Z", r.Header.Get("X-Amz-Date")
  82         if timestr == "" {
  83                 timefmt, timestr = time.RFC1123, r.Header.Get("Date")
  84         }
  85         t, err := time.Parse(timefmt, timestr)
  86         if err != nil {
  87                 return "", fmt.Errorf("invalid timestamp %q: %s", timestr, err)
  88         }
  89         if skew := time.Now().Sub(t); skew < -s3MaxClockSkew || skew > s3MaxClockSkew {
  90                 return "", errors.New("exceeded max clock skew")
  91         }
  92
  93         var canonicalHeaders string
  94         for _, h := range strings.Split(signedHeaders, ";") {
  95                 if h == "host" {
  96                         canonicalHeaders += h + ":" + r.Host + "\n"
  97                 } else {
  98                         canonicalHeaders += h + ":" + r.Header.Get(h) + "\n"
  99                 }
 100         }
 101
 102         normalizedURL := *r.URL
 103         normalizedURL.RawPath = ""
 104         normalizedURL.Path = reMultipleSlashChars.ReplaceAllString(normalizedURL.Path, "/")
 105         ctxlog.FromContext(r.Context()).Infof("escapedPath %s", normalizedURL.EscapedPath())
 106         canonicalRequest := fmt.Sprintf("%s\n%s\n%s\n%s\n%s\n%s", r.Method, normalizedURL.EscapedPath(), s3querystring(r.URL), canonicalHeaders, signedHeaders, r.Header.Get("X-Amz-Content-Sha256"))
 107         ctxlog.FromContext(r.Context()).Debugf("s3stringToSign: canonicalRequest %s", canonicalRequest)
 108         return fmt.Sprintf("%s\n%s\n%s\n%s", alg, r.Header.Get("X-Amz-Date"), scope, hashdigest(sha256.New(), canonicalRequest)), nil
 109 }
 110
 111 func s3signature(secretKey, scope, signedHeaders, stringToSign string) (string, error) {
 112         // scope is {datestamp}/{region}/{service}/aws4_request
 113         drs := strings.Split(scope, "/")
 114         if len(drs) != 4 {
 115                 return "", fmt.Errorf("invalid scope %q", scope)
 116         }
 117         key := s3signatureKey(secretKey, drs[0], drs[1], drs[2])
 118         return hashdigest(hmac.New(sha256.New, key), stringToSign), nil
 119 }
 120
 121 var v2tokenUnderscore = regexp.MustCompile(`^v2_[a-z0-9]{5}-gj3su-[a-z0-9]{15}_`)
 122
 123 func unescapeKey(key string) string {
 124         if v2tokenUnderscore.MatchString(key) {
 125                 // Entire Arvados token, with "/" replaced by "_" to
 126                 // avoid colliding with the Authorization header
 127                 // format.
 128                 return strings.Replace(key, "_", "/", -1)
 129         } else if s, err := url.PathUnescape(key); err == nil {
 130                 return s
 131         } else {
 132                 return key
 133         }
 134 }
 135
 136 // checks3signature verifies the given S3 V4 signature and returns the
 137 // Arvados token that corresponds to the given accessKey. An error is
 138 // returned if accessKey is not a valid token UUID or the signature
 139 // does not match.
 140 func (h *handler) checks3signature(r *http.Request) (string, error) {
 141         var key, scope, signedHeaders, signature string
 142         authstring := strings.TrimPrefix(r.Header.Get("Authorization"), s3SignAlgorithm+" ")
 143         for _, cmpt := range strings.Split(authstring, ",") {
 144                 cmpt = strings.TrimSpace(cmpt)
 145                 split := strings.SplitN(cmpt, "=", 2)
 146                 switch {
 147                 case len(split) != 2:
 148                         // (?) ignore
 149                 case split[0] == "Credential":
 150                         keyandscope := strings.SplitN(split[1], "/", 2)
 151                         if len(keyandscope) == 2 {
 152                                 key, scope = keyandscope[0], keyandscope[1]
 153                         }
 154                 case split[0] == "SignedHeaders":
 155                         signedHeaders = split[1]
 156                 case split[0] == "Signature":
 157                         signature = split[1]
 158                 }
 159         }
 160
 161         client := (&arvados.Client{
 162                 APIHost:  h.Config.cluster.Services.Controller.ExternalURL.Host,
 163                 Insecure: h.Config.cluster.TLS.Insecure,
 164         }).WithRequestID(r.Header.Get("X-Request-Id"))
 165         var aca arvados.APIClientAuthorization
 166         var secret string
 167         var err error
 168         if len(key) == 27 && key[5:12] == "-gj3su-" {
 169                 // Access key is the UUID of an Arvados token, secret
 170                 // key is the secret part.
 171                 ctx := arvados.ContextWithAuthorization(r.Context(), "Bearer "+h.Config.cluster.SystemRootToken)
 172                 err = client.RequestAndDecodeContext(ctx, &aca, "GET", "arvados/v1/api_client_authorizations/"+key, nil, nil)
 173                 secret = aca.APIToken
 174         } else {
 175                 // Access key and secret key are both an entire
 176                 // Arvados token or OIDC access token.
 177                 ctx := arvados.ContextWithAuthorization(r.Context(), "Bearer "+unescapeKey(key))
 178                 err = client.RequestAndDecodeContext(ctx, &aca, "GET", "arvados/v1/api_client_authorizations/current", nil, nil)
 179                 secret = key
 180         }
 181         if err != nil {
 182                 ctxlog.FromContext(r.Context()).WithError(err).WithField("UUID", key).Info("token lookup failed")
 183                 return "", errors.New("invalid access key")
 184         }
 185         stringToSign, err := s3stringToSign(s3SignAlgorithm, scope, signedHeaders, r)
 186         if err != nil {
 187                 return "", err
 188         }
 189         expect, err := s3signature(secret, scope, signedHeaders, stringToSign)
 190         if err != nil {
 191                 return "", err
 192         } else if expect != signature {
 193                 return "", fmt.Errorf("signature does not match (scope %q signedHeaders %q stringToSign %q)", scope, signedHeaders, stringToSign)
 194         }
 195         return aca.TokenV2(), nil
 196 }
 197
 198 func s3ErrorResponse(w http.ResponseWriter, s3code string, message string, resource string, code int) {
 199         w.Header().Set("Content-Type", "application/xml")
 200         w.Header().Set("X-Content-Type-Options", "nosniff")
 201         w.WriteHeader(code)
 202         var errstruct struct {
 203                 Code      string
 204                 Message   string
 205                 Resource  string
 206                 RequestId string
 207         }
 208         errstruct.Code = s3code
 209         errstruct.Message = message
 210         errstruct.Resource = resource
 211         errstruct.RequestId = ""
 212         enc := xml.NewEncoder(w)
 213         fmt.Fprint(w, xml.Header)
 214         enc.EncodeElement(errstruct, xml.StartElement{Name: xml.Name{Local: "Error"}})
 215 }
 216
 217 var NoSuchKey = "NoSuchKey"
 218 var NoSuchBucket = "NoSuchBucket"
 219 var InvalidArgument = "InvalidArgument"
 220 var InternalError = "InternalError"
 221 var UnauthorizedAccess = "UnauthorizedAccess"
 222 var InvalidRequest = "InvalidRequest"
 223 var SignatureDoesNotMatch = "SignatureDoesNotMatch"
 224
 225 var reRawQueryIndicatesAPI = regexp.MustCompile(`^[a-z]+(&|$)`)
 226
 227 // serveS3 handles r and returns true if r is a request from an S3
 228 // client, otherwise it returns false.
 229 func (h *handler) serveS3(w http.ResponseWriter, r *http.Request) bool {
 230         var token string
 231         if auth := r.Header.Get("Authorization"); strings.HasPrefix(auth, "AWS ") {
 232                 split := strings.SplitN(auth[4:], ":", 2)
 233                 if len(split) < 2 {
 234                         s3ErrorResponse(w, InvalidRequest, "malformed Authorization header", r.URL.Path, http.StatusUnauthorized)
 235                         return true
 236                 }
 237                 token = unescapeKey(split[0])
 238         } else if strings.HasPrefix(auth, s3SignAlgorithm+" ") {
 239                 t, err := h.checks3signature(r)
 240                 if err != nil {
 241                         s3ErrorResponse(w, SignatureDoesNotMatch, "signature verification failed: "+err.Error(), r.URL.Path, http.StatusForbidden)
 242                         return true
 243                 }
 244                 token = t
 245         } else {
 246                 return false
 247         }
 248
 249         var err error
 250         var fs arvados.CustomFileSystem
 251         if r.Method == http.MethodGet || r.Method == http.MethodHead {
 252                 // Use a single session (cached FileSystem) across
 253                 // multiple read requests.
 254                 fs, err = h.Config.Cache.GetSession(token)
 255                 if err != nil {
 256                         s3ErrorResponse(w, InternalError, err.Error(), r.URL.Path, http.StatusInternalServerError)
 257                         return true
 258                 }
 259         } else {
 260                 // Create a FileSystem for this request, to avoid
 261                 // exposing incomplete write operations to concurrent
 262                 // requests.
 263                 _, kc, client, release, err := h.getClients(r.Header.Get("X-Request-Id"), token)
 264                 if err != nil {
 265                         s3ErrorResponse(w, InternalError, err.Error(), r.URL.Path, http.StatusInternalServerError)
 266                         return true
 267                 }
 268                 defer release()
 269                 fs = client.SiteFileSystem(kc)
 270                 fs.ForwardSlashNameSubstitution(h.Config.cluster.Collections.ForwardSlashNameSubstitution)
 271         }
 272
 273         var objectNameGiven bool
 274         var bucketName string
 275         fspath := "/by_id"
 276         if id := parseCollectionIDFromDNSName(r.Host); id != "" {
 277                 fspath += "/" + id
 278                 bucketName = id
 279                 objectNameGiven = strings.Count(strings.TrimSuffix(r.URL.Path, "/"), "/") > 0
 280         } else {
 281                 bucketName = strings.SplitN(strings.TrimPrefix(r.URL.Path, "/"), "/", 2)[0]
 282                 objectNameGiven = strings.Count(strings.TrimSuffix(r.URL.Path, "/"), "/") > 1
 283         }
 284         fspath += reMultipleSlashChars.ReplaceAllString(r.URL.Path, "/")
 285
 286         switch {
 287         case r.Method == http.MethodGet && !objectNameGiven:
 288                 // Path is "/{uuid}" or "/{uuid}/", has no object name
 289                 if _, ok := r.URL.Query()["versioning"]; ok {
 290                         // GetBucketVersioning
 291                         w.Header().Set("Content-Type", "application/xml")
 292                         io.WriteString(w, xml.Header)
 293                         fmt.Fprintln(w, `<VersioningConfiguration xmlns="http://s3.amazonaws.com/doc/2006-03-01/"/>`)
 294                 } else if _, ok = r.URL.Query()["location"]; ok {
 295                         // GetBucketLocation
 296                         w.Header().Set("Content-Type", "application/xml")
 297                         io.WriteString(w, xml.Header)
 298                         fmt.Fprintln(w, `<LocationConstraint><LocationConstraint xmlns="http://s3.amazonaws.com/doc/2006-03-01/">`+
 299                                 h.Config.cluster.ClusterID+
 300                                 `</LocationConstraint></LocationConstraint>`)
 301                 } else if reRawQueryIndicatesAPI.MatchString(r.URL.RawQuery) {
 302                         // GetBucketWebsite ("GET /bucketid/?website"), GetBucketTagging, etc.
 303                         s3ErrorResponse(w, InvalidRequest, "API not supported", r.URL.Path+"?"+r.URL.RawQuery, http.StatusBadRequest)
 304                 } else {
 305                         // ListObjects
 306                         h.s3list(bucketName, w, r, fs)
 307                 }
 308                 return true
 309         case r.Method == http.MethodGet || r.Method == http.MethodHead:
 310                 if reRawQueryIndicatesAPI.MatchString(r.URL.RawQuery) {
 311                         // GetObjectRetention ("GET /bucketid/objectid?retention&versionID=..."), etc.
 312                         s3ErrorResponse(w, InvalidRequest, "API not supported", r.URL.Path+"?"+r.URL.RawQuery, http.StatusBadRequest)
 313                         return true
 314                 }
 315                 fi, err := fs.Stat(fspath)
 316                 if r.Method == "HEAD" && !objectNameGiven {
 317                         // HeadBucket
 318                         if err == nil && fi.IsDir() {
 319                                 w.WriteHeader(http.StatusOK)
 320                         } else if os.IsNotExist(err) {
 321                                 s3ErrorResponse(w, NoSuchBucket, "The specified bucket does not exist.", r.URL.Path, http.StatusNotFound)
 322                         } else {
 323                                 s3ErrorResponse(w, InternalError, err.Error(), r.URL.Path, http.StatusBadGateway)
 324                         }
 325                         return true
 326                 }
 327                 if err == nil && fi.IsDir() && objectNameGiven && strings.HasSuffix(fspath, "/") && h.Config.cluster.Collections.S3FolderObjects {
 328                         w.Header().Set("Content-Type", "application/x-directory")
 329                         w.WriteHeader(http.StatusOK)
 330                         return true
 331                 }
 332                 if os.IsNotExist(err) ||
 333                         (err != nil && err.Error() == "not a directory") ||
 334                         (fi != nil && fi.IsDir()) {
 335                         s3ErrorResponse(w, NoSuchKey, "The specified key does not exist.", r.URL.Path, http.StatusNotFound)
 336                         return true
 337                 }
 338                 // shallow copy r, and change URL path
 339                 r := *r
 340                 r.URL.Path = fspath
 341                 http.FileServer(fs).ServeHTTP(w, &r)
 342                 return true
 343         case r.Method == http.MethodPut:
 344                 if reRawQueryIndicatesAPI.MatchString(r.URL.RawQuery) {
 345                         // PutObjectAcl ("PUT /bucketid/objectid?acl&versionID=..."), etc.
 346                         s3ErrorResponse(w, InvalidRequest, "API not supported", r.URL.Path+"?"+r.URL.RawQuery, http.StatusBadRequest)
 347                         return true
 348                 }
 349                 if !objectNameGiven {
 350                         s3ErrorResponse(w, InvalidArgument, "Missing object name in PUT request.", r.URL.Path, http.StatusBadRequest)
 351                         return true
 352                 }
 353                 var objectIsDir bool
 354                 if strings.HasSuffix(fspath, "/") {
 355                         if !h.Config.cluster.Collections.S3FolderObjects {
 356                                 s3ErrorResponse(w, InvalidArgument, "invalid object name: trailing slash", r.URL.Path, http.StatusBadRequest)
 357                                 return true
 358                         }
 359                         n, err := r.Body.Read(make([]byte, 1))
 360                         if err != nil && err != io.EOF {
 361                                 s3ErrorResponse(w, InternalError, fmt.Sprintf("error reading request body: %s", err), r.URL.Path, http.StatusInternalServerError)
 362                                 return true
 363                         } else if n > 0 {
 364                                 s3ErrorResponse(w, InvalidArgument, "cannot create object with trailing '/' char unless content is empty", r.URL.Path, http.StatusBadRequest)
 365                                 return true
 366                         } else if strings.SplitN(r.Header.Get("Content-Type"), ";", 2)[0] != "application/x-directory" {
 367                                 s3ErrorResponse(w, InvalidArgument, "cannot create object with trailing '/' char unless Content-Type is 'application/x-directory'", r.URL.Path, http.StatusBadRequest)
 368                                 return true
 369                         }
 370                         // Given PUT "foo/bar/", we'll use "foo/bar/."
 371                         // in the "ensure parents exist" block below,
 372                         // and then we'll be done.
 373                         fspath += "."
 374                         objectIsDir = true
 375                 }
 376                 fi, err := fs.Stat(fspath)
 377                 if err != nil && err.Error() == "not a directory" {
 378                         // requested foo/bar, but foo is a file
 379                         s3ErrorResponse(w, InvalidArgument, "object name conflicts with existing object", r.URL.Path, http.StatusBadRequest)
 380                         return true
 381                 }
 382                 if strings.HasSuffix(r.URL.Path, "/") && err == nil && !fi.IsDir() {
 383                         // requested foo/bar/, but foo/bar is a file
 384                         s3ErrorResponse(w, InvalidArgument, "object name conflicts with existing object", r.URL.Path, http.StatusBadRequest)
 385                         return true
 386                 }
 387                 // create missing parent/intermediate directories, if any
 388                 for i, c := range fspath {
 389                         if i > 0 && c == '/' {
 390                                 dir := fspath[:i]
 391                                 if strings.HasSuffix(dir, "/") {
 392                                         err = errors.New("invalid object name (consecutive '/' chars)")
 393                                         s3ErrorResponse(w, InvalidArgument, err.Error(), r.URL.Path, http.StatusBadRequest)
 394                                         return true
 395                                 }
 396                                 err = fs.Mkdir(dir, 0755)
 397                                 if err == arvados.ErrInvalidArgument {
 398                                         // Cannot create a directory
 399                                         // here.
 400                                         err = fmt.Errorf("mkdir %q failed: %w", dir, err)
 401                                         s3ErrorResponse(w, InvalidArgument, err.Error(), r.URL.Path, http.StatusBadRequest)
 402                                         return true
 403                                 } else if err != nil && !os.IsExist(err) {
 404                                         err = fmt.Errorf("mkdir %q failed: %w", dir, err)
 405                                         s3ErrorResponse(w, InternalError, err.Error(), r.URL.Path, http.StatusInternalServerError)
 406                                         return true
 407                                 }
 408                         }
 409                 }
 410                 if !objectIsDir {
 411                         f, err := fs.OpenFile(fspath, os.O_WRONLY|os.O_TRUNC|os.O_CREATE, 0644)
 412                         if os.IsNotExist(err) {
 413                                 f, err = fs.OpenFile(fspath, os.O_WRONLY|os.O_TRUNC|os.O_CREATE, 0644)
 414                         }
 415                         if err != nil {
 416                                 err = fmt.Errorf("open %q failed: %w", r.URL.Path, err)
 417                                 s3ErrorResponse(w, InvalidArgument, err.Error(), r.URL.Path, http.StatusBadRequest)
 418                                 return true
 419                         }
 420                         defer f.Close()
 421                         _, err = io.Copy(f, r.Body)
 422                         if err != nil {
 423                                 err = fmt.Errorf("write to %q failed: %w", r.URL.Path, err)
 424                                 s3ErrorResponse(w, InternalError, err.Error(), r.URL.Path, http.StatusBadGateway)
 425                                 return true
 426                         }
 427                         err = f.Close()
 428                         if err != nil {
 429                                 err = fmt.Errorf("write to %q failed: close: %w", r.URL.Path, err)
 430                                 s3ErrorResponse(w, InternalError, err.Error(), r.URL.Path, http.StatusBadGateway)
 431                                 return true
 432                         }
 433                 }
 434                 err = fs.Sync()
 435                 if err != nil {
 436                         err = fmt.Errorf("sync failed: %w", err)
 437                         s3ErrorResponse(w, InternalError, err.Error(), r.URL.Path, http.StatusInternalServerError)
 438                         return true
 439                 }
 440                 // Ensure a subsequent read operation will see the changes.
 441                 h.Config.Cache.ResetSession(token)
 442                 w.WriteHeader(http.StatusOK)
 443                 return true
 444         case r.Method == http.MethodDelete:
 445                 if reRawQueryIndicatesAPI.MatchString(r.URL.RawQuery) {
 446                         // DeleteObjectTagging ("DELETE /bucketid/objectid?tagging&versionID=..."), etc.
 447                         s3ErrorResponse(w, InvalidRequest, "API not supported", r.URL.Path+"?"+r.URL.RawQuery, http.StatusBadRequest)
 448                         return true
 449                 }
 450                 if !objectNameGiven || r.URL.Path == "/" {
 451                         s3ErrorResponse(w, InvalidArgument, "missing object name in DELETE request", r.URL.Path, http.StatusBadRequest)
 452                         return true
 453                 }
 454                 if strings.HasSuffix(fspath, "/") {
 455                         fspath = strings.TrimSuffix(fspath, "/")
 456                         fi, err := fs.Stat(fspath)
 457                         if os.IsNotExist(err) {
 458                                 w.WriteHeader(http.StatusNoContent)
 459                                 return true
 460                         } else if err != nil {
 461                                 s3ErrorResponse(w, InternalError, err.Error(), r.URL.Path, http.StatusInternalServerError)
 462                                 return true
 463                         } else if !fi.IsDir() {
 464                                 // if "foo" exists and is a file, then
 465                                 // "foo/" doesn't exist, so we say
 466                                 // delete was successful.
 467                                 w.WriteHeader(http.StatusNoContent)
 468                                 return true
 469                         }
 470                 } else if fi, err := fs.Stat(fspath); err == nil && fi.IsDir() {
 471                         // if "foo" is a dir, it is visible via S3
 472                         // only as "foo/", not "foo" -- so we leave
 473                         // the dir alone and return 204 to indicate
 474                         // that "foo" does not exist.
 475                         w.WriteHeader(http.StatusNoContent)
 476                         return true
 477                 }
 478                 err = fs.Remove(fspath)
 479                 if os.IsNotExist(err) {
 480                         w.WriteHeader(http.StatusNoContent)
 481                         return true
 482                 }
 483                 if err != nil {
 484                         err = fmt.Errorf("rm failed: %w", err)
 485                         s3ErrorResponse(w, InvalidArgument, err.Error(), r.URL.Path, http.StatusBadRequest)
 486                         return true
 487                 }
 488                 err = fs.Sync()
 489                 if err != nil {
 490                         err = fmt.Errorf("sync failed: %w", err)
 491                         s3ErrorResponse(w, InternalError, err.Error(), r.URL.Path, http.StatusInternalServerError)
 492                         return true
 493                 }
 494                 // Ensure a subsequent read operation will see the changes.
 495                 h.Config.Cache.ResetSession(token)
 496                 w.WriteHeader(http.StatusNoContent)
 497                 return true
 498         default:
 499                 s3ErrorResponse(w, InvalidRequest, "method not allowed", r.URL.Path, http.StatusMethodNotAllowed)
 500                 return true
 501         }
 502 }
 503
 504 // Call fn on the given path (directory) and its contents, in
 505 // lexicographic order.
 506 //
 507 // If isRoot==true and path is not a directory, return nil.
 508 //
 509 // If fn returns filepath.SkipDir when called on a directory, don't
 510 // descend into that directory.
 511 func walkFS(fs arvados.CustomFileSystem, path string, isRoot bool, fn func(path string, fi os.FileInfo) error) error {
 512         if isRoot {
 513                 fi, err := fs.Stat(path)
 514                 if os.IsNotExist(err) || (err == nil && !fi.IsDir()) {
 515                         return nil
 516                 } else if err != nil {
 517                         return err
 518                 }
 519                 err = fn(path, fi)
 520                 if err == filepath.SkipDir {
 521                         return nil
 522                 } else if err != nil {
 523                         return err
 524                 }
 525         }
 526         f, err := fs.Open(path)
 527         if os.IsNotExist(err) && isRoot {
 528                 return nil
 529         } else if err != nil {
 530                 return fmt.Errorf("open %q: %w", path, err)
 531         }
 532         defer f.Close()
 533         if path == "/" {
 534                 path = ""
 535         }
 536         fis, err := f.Readdir(-1)
 537         if err != nil {
 538                 return err
 539         }
 540         sort.Slice(fis, func(i, j int) bool { return fis[i].Name() < fis[j].Name() })
 541         for _, fi := range fis {
 542                 err = fn(path+"/"+fi.Name(), fi)
 543                 if err == filepath.SkipDir {
 544                         continue
 545                 } else if err != nil {
 546                         return err
 547                 }
 548                 if fi.IsDir() {
 549                         err = walkFS(fs, path+"/"+fi.Name(), false, fn)
 550                         if err != nil {
 551                                 return err
 552                         }
 553                 }
 554         }
 555         return nil
 556 }
 557
 558 var errDone = errors.New("done")
 559
 560 func (h *handler) s3list(bucket string, w http.ResponseWriter, r *http.Request, fs arvados.CustomFileSystem) {
 561         var params struct {
 562                 delimiter string
 563                 marker    string
 564                 maxKeys   int
 565                 prefix    string
 566         }
 567         params.delimiter = r.FormValue("delimiter")
 568         params.marker = r.FormValue("marker")
 569         if mk, _ := strconv.ParseInt(r.FormValue("max-keys"), 10, 64); mk > 0 && mk < s3MaxKeys {
 570                 params.maxKeys = int(mk)
 571         } else {
 572                 params.maxKeys = s3MaxKeys
 573         }
 574         params.prefix = r.FormValue("prefix")
 575
 576         bucketdir := "by_id/" + bucket
 577         // walkpath is the directory (relative to bucketdir) we need
 578         // to walk: the innermost directory that is guaranteed to
 579         // contain all paths that have the requested prefix. Examples:
 580         // prefix "foo/bar"  => walkpath "foo"
 581         // prefix "foo/bar/" => walkpath "foo/bar"
 582         // prefix "foo"      => walkpath ""
 583         // prefix ""         => walkpath ""
 584         walkpath := params.prefix
 585         if cut := strings.LastIndex(walkpath, "/"); cut >= 0 {
 586                 walkpath = walkpath[:cut]
 587         } else {
 588                 walkpath = ""
 589         }
 590
 591         type commonPrefix struct {
 592                 Prefix string
 593         }
 594         type listResp struct {
 595                 XMLName string `xml:"http://s3.amazonaws.com/doc/2006-03-01/ ListBucketResult"`
 596                 s3.ListResp
 597                 // s3.ListResp marshals an empty tag when
 598                 // CommonPrefixes is nil, which confuses some clients.
 599                 // Fix by using this nested struct instead.
 600                 CommonPrefixes []commonPrefix
 601                 // Similarly, we need omitempty here, because an empty
 602                 // tag confuses some clients (e.g.,
 603                 // github.com/aws/aws-sdk-net never terminates its
 604                 // paging loop).
 605                 NextMarker string `xml:"NextMarker,omitempty"`
 606                 // ListObjectsV2 has a KeyCount response field.
 607                 KeyCount int
 608         }
 609         resp := listResp{
 610                 ListResp: s3.ListResp{
 611                         Name:      bucket,
 612                         Prefix:    params.prefix,
 613                         Delimiter: params.delimiter,
 614                         Marker:    params.marker,
 615                         MaxKeys:   params.maxKeys,
 616                 },
 617         }
 618         commonPrefixes := map[string]bool{}
 619         err := walkFS(fs, strings.TrimSuffix(bucketdir+"/"+walkpath, "/"), true, func(path string, fi os.FileInfo) error {
 620                 if path == bucketdir {
 621                         return nil
 622                 }
 623                 path = path[len(bucketdir)+1:]
 624                 filesize := fi.Size()
 625                 if fi.IsDir() {
 626                         path += "/"
 627                         filesize = 0
 628                 }
 629                 if len(path) <= len(params.prefix) {
 630                         if path > params.prefix[:len(path)] {
 631                                 // with prefix "foobar", walking "fooz" means we're done
 632                                 return errDone
 633                         }
 634                         if path < params.prefix[:len(path)] {
 635                                 // with prefix "foobar", walking "foobag" is pointless
 636                                 return filepath.SkipDir
 637                         }
 638                         if fi.IsDir() && !strings.HasPrefix(params.prefix+"/", path) {
 639                                 // with prefix "foo/bar", walking "fo"
 640                                 // is pointless (but walking "foo" or
 641                                 // "foo/bar" is necessary)
 642                                 return filepath.SkipDir
 643                         }
 644                         if len(path) < len(params.prefix) {
 645                                 // can't skip anything, and this entry
 646                                 // isn't in the results, so just
 647                                 // continue descent
 648                                 return nil
 649                         }
 650                 } else {
 651                         if path[:len(params.prefix)] > params.prefix {
 652                                 // with prefix "foobar", nothing we
 653                                 // see after "foozzz" is relevant
 654                                 return errDone
 655                         }
 656                 }
 657                 if path < params.marker || path < params.prefix {
 658                         return nil
 659                 }
 660                 if fi.IsDir() && !h.Config.cluster.Collections.S3FolderObjects {
 661                         // Note we don't add anything to
 662                         // commonPrefixes here even if delimiter is
 663                         // "/". We descend into the directory, and
 664                         // return a commonPrefix only if we end up
 665                         // finding a regular file inside it.
 666                         return nil
 667                 }
 668                 if params.delimiter != "" {
 669                         idx := strings.Index(path[len(params.prefix):], params.delimiter)
 670                         if idx >= 0 {
 671                                 // with prefix "foobar" and delimiter
 672                                 // "z", when we hit "foobar/baz", we
 673                                 // add "/baz" to commonPrefixes and
 674                                 // stop descending.
 675                                 commonPrefixes[path[:len(params.prefix)+idx+1]] = true
 676                                 return filepath.SkipDir
 677                         }
 678                 }
 679                 if len(resp.Contents)+len(commonPrefixes) >= params.maxKeys {
 680                         resp.IsTruncated = true
 681                         if params.delimiter != "" {
 682                                 resp.NextMarker = path
 683                         }
 684                         return errDone
 685                 }
 686                 resp.Contents = append(resp.Contents, s3.Key{
 687                         Key:          path,
 688                         LastModified: fi.ModTime().UTC().Format("2006-01-02T15:04:05.999") + "Z",
 689                         Size:         filesize,
 690                 })
 691                 return nil
 692         })
 693         if err != nil && err != errDone {
 694                 http.Error(w, err.Error(), http.StatusInternalServerError)
 695                 return
 696         }
 697         if params.delimiter != "" {
 698                 resp.CommonPrefixes = make([]commonPrefix, 0, len(commonPrefixes))
 699                 for prefix := range commonPrefixes {
 700                         resp.CommonPrefixes = append(resp.CommonPrefixes, commonPrefix{prefix})
 701                 }
 702                 sort.Slice(resp.CommonPrefixes, func(i, j int) bool { return resp.CommonPrefixes[i].Prefix < resp.CommonPrefixes[j].Prefix })
 703         }
 704         resp.KeyCount = len(resp.Contents)
 705         w.Header().Set("Content-Type", "application/xml")
 706         io.WriteString(w, xml.Header)
 707         if err := xml.NewEncoder(w).Encode(resp); err != nil {
 708                 ctxlog.FromContext(r.Context()).WithError(err).Error("error writing xml response")
 709         }
 710 }