source3/smbd/notify_internal.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    Copyright (C) Andrew Tridgell 2006
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18 */
  19
  20 /*
  21   this is the change notify database. It implements mechanisms for
  22   storing current change notify waiters in a tdb, and checking if a
  23   given event matches any of the stored notify waiiters.
  24 */
  25
  26 #include "includes.h"
  27 #include "librpc/gen_ndr/ndr_notify.h"
  28
  29 struct notify_context {
  30         struct db_context *db;
  31         struct server_id server;
  32         struct messaging_context *messaging_ctx;
  33         struct notify_list *list;
  34         struct notify_array *array;
  35         int seqnum;
  36         struct sys_notify_context *sys_notify_ctx;
  37         TDB_DATA key;
  38 };
  39
  40
  41 struct notify_list {
  42         struct notify_list *next, *prev;
  43         void *private_data;
  44         void (*callback)(void *, const struct notify_event *);
  45         void *sys_notify_handle;
  46         int depth;
  47 };
  48
  49 #define NOTIFY_KEY "notify array"
  50
  51 #define NOTIFY_ENABLE           "notify:enable"
  52 #define NOTIFY_ENABLE_DEFAULT   True
  53
  54 static NTSTATUS notify_remove_all(struct notify_context *notify,
  55                                   const struct server_id *server);
  56 static void notify_handler(struct messaging_context *msg_ctx, void *private_data,
  57                            uint32_t msg_type, struct server_id server_id, DATA_BLOB *data);
  58
  59 /*
  60   destroy the notify context
  61 */
  62 static int notify_destructor(struct notify_context *notify)
  63 {
  64         messaging_deregister(notify->messaging_ctx, MSG_PVFS_NOTIFY, notify);
  65
  66         if (notify->list != NULL) {
  67                 notify_remove_all(notify, &notify->server);
  68         }
  69
  70         return 0;
  71 }
  72
  73 /*
  74   Open up the notify.tdb database. You should close it down using
  75   talloc_free(). We need the messaging_ctx to allow for notifications
  76   via internal messages
  77 */
  78 struct notify_context *notify_init(TALLOC_CTX *mem_ctx, struct server_id server,
  79                                    struct messaging_context *messaging_ctx,
  80                                    struct event_context *ev,
  81                                    connection_struct *conn)
  82 {
  83         struct notify_context *notify;
  84
  85         if (!lp_change_notify(conn->params)) {
  86                 return NULL;
  87         }
  88
  89         notify = talloc(mem_ctx, struct notify_context);
  90         if (notify == NULL) {
  91                 return NULL;
  92         }
  93
  94         notify->db = db_open(notify, lock_path("notify.tdb"),
  95                                   0, TDB_SEQNUM|TDB_CLEAR_IF_FIRST,
  96                                   O_RDWR|O_CREAT, 0644);
  97         if (notify->db == NULL) {
  98                 talloc_free(notify);
  99                 return NULL;
 100         }
 101
 102         notify->server = server;
 103         notify->messaging_ctx = messaging_ctx;
 104         notify->list = NULL;
 105         notify->array = NULL;
 106         notify->seqnum = notify->db->get_seqnum(notify->db);
 107         notify->key = string_term_tdb_data(NOTIFY_KEY);
 108
 109         talloc_set_destructor(notify, notify_destructor);
 110
 111         /* register with the messaging subsystem for the notify
 112            message type */
 113         messaging_register(notify->messaging_ctx, notify,
 114                            MSG_PVFS_NOTIFY, notify_handler);
 115
 116         notify->sys_notify_ctx = sys_notify_context_create(conn, notify, ev);
 117
 118         return notify;
 119 }
 120
 121 /*
 122   lock and fetch the record
 123 */
 124 static NTSTATUS notify_fetch_locked(struct notify_context *notify, struct db_record **rec)
 125 {
 126         *rec = notify->db->fetch_locked(notify->db, notify, notify->key);
 127         if (*rec == NULL) {
 128                 return NT_STATUS_INTERNAL_DB_CORRUPTION;
 129         }
 130         return NT_STATUS_OK;
 131 }
 132
 133 /*
 134   load the notify array
 135 */
 136 static NTSTATUS notify_load(struct notify_context *notify, struct db_record *rec)
 137 {
 138         TDB_DATA dbuf;
 139         DATA_BLOB blob;
 140         NTSTATUS status;
 141         int seqnum;
 142
 143         seqnum = notify->db->get_seqnum(notify->db);
 144
 145         if (seqnum == notify->seqnum && notify->array != NULL) {
 146                 return NT_STATUS_OK;
 147         }
 148
 149         notify->seqnum = seqnum;
 150
 151         talloc_free(notify->array);
 152         notify->array = TALLOC_ZERO_P(notify, struct notify_array);
 153         NT_STATUS_HAVE_NO_MEMORY(notify->array);
 154
 155         if (!rec) {
 156                 if (notify->db->fetch(notify->db, notify, notify->key, &dbuf) != 0) {
 157                         return NT_STATUS_INTERNAL_DB_CORRUPTION;
 158                 }
 159         } else {
 160                 dbuf = rec->value;
 161         }
 162
 163         blob.data = (uint8 *)dbuf.dptr;
 164         blob.length = dbuf.dsize;
 165
 166         status = NT_STATUS_OK;
 167         if (blob.length > 0) {
 168                 enum ndr_err_code ndr_err;
 169                 ndr_err = ndr_pull_struct_blob(&blob, notify->array, NULL, notify->array,
 170                                                (ndr_pull_flags_fn_t)ndr_pull_notify_array);
 171                 if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 172                         status = ndr_map_error2ntstatus(ndr_err);
 173                 }
 174         }
 175
 176         if (DEBUGLEVEL >= 10) {
 177                 DEBUG(10, ("notify_load:\n"));
 178                 NDR_PRINT_DEBUG(notify_array, notify->array);
 179         }
 180
 181         if (!rec) {
 182                 talloc_free(dbuf.dptr);
 183         }
 184
 185         return status;
 186 }
 187
 188 /*
 189   compare notify entries for sorting
 190 */
 191 static int notify_compare(const void *p1, const void *p2)
 192 {
 193         const struct notify_entry *e1 = (const struct notify_entry *)p1;
 194         const struct notify_entry *e2 = (const struct notify_entry *)p2;
 195         return strcmp(e1->path, e2->path);
 196 }
 197
 198 /*
 199   save the notify array
 200 */
 201 static NTSTATUS notify_save(struct notify_context *notify, struct db_record *rec)
 202 {
 203         TDB_DATA dbuf;
 204         DATA_BLOB blob;
 205         NTSTATUS status;
 206         enum ndr_err_code ndr_err;
 207         TALLOC_CTX *tmp_ctx;
 208
 209         /* if possible, remove some depth arrays */
 210         while (notify->array->num_depths > 0 &&
 211                notify->array->depth[notify->array->num_depths-1].num_entries == 0) {
 212                 notify->array->num_depths--;
 213         }
 214
 215         /* we might just be able to delete the record */
 216         if (notify->array->num_depths == 0) {
 217                 return rec->delete_rec(rec);
 218         }
 219
 220         tmp_ctx = talloc_new(notify);
 221         NT_STATUS_HAVE_NO_MEMORY(tmp_ctx);
 222
 223         ndr_err = ndr_push_struct_blob(&blob, tmp_ctx, NULL, notify->array,
 224                                       (ndr_push_flags_fn_t)ndr_push_notify_array);
 225         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 226                 talloc_free(tmp_ctx);
 227                 return ndr_map_error2ntstatus(ndr_err);
 228         }
 229
 230         if (DEBUGLEVEL >= 10) {
 231                 DEBUG(10, ("notify_save:\n"));
 232                 NDR_PRINT_DEBUG(notify_array, notify->array);
 233         }
 234
 235         dbuf.dptr = blob.data;
 236         dbuf.dsize = blob.length;
 237
 238         status = rec->store(rec, dbuf, TDB_REPLACE);
 239         talloc_free(tmp_ctx);
 240
 241         return status;
 242 }
 243
 244
 245 /*
 246   handle incoming notify messages
 247 */
 248 static void notify_handler(struct messaging_context *msg_ctx, void *private_data,
 249                            uint32_t msg_type, struct server_id server_id, DATA_BLOB *data)
 250 {
 251         struct notify_context *notify = talloc_get_type(private_data, struct notify_context);
 252         enum ndr_err_code ndr_err;
 253         struct notify_event ev;
 254         TALLOC_CTX *tmp_ctx = talloc_new(notify);
 255         struct notify_list *listel;
 256
 257         if (tmp_ctx == NULL) {
 258                 return;
 259         }
 260
 261         ndr_err = ndr_pull_struct_blob(data, tmp_ctx, NULL, &ev,
 262                                        (ndr_pull_flags_fn_t)ndr_pull_notify_event);
 263         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 264                 talloc_free(tmp_ctx);
 265                 return;
 266         }
 267
 268         for (listel=notify->list;listel;listel=listel->next) {
 269                 if (listel->private_data == ev.private_data) {
 270                         listel->callback(listel->private_data, &ev);
 271                         break;
 272                 }
 273         }
 274
 275         talloc_free(tmp_ctx);
 276 }
 277
 278 /*
 279   callback from sys_notify telling us about changes from the OS
 280 */
 281 static void sys_notify_callback(struct sys_notify_context *ctx,
 282                                 void *ptr, struct notify_event *ev)
 283 {
 284         struct notify_list *listel = talloc_get_type(ptr, struct notify_list);
 285         ev->private_data = listel;
 286         DEBUG(10, ("sys_notify_callback called with action=%d, for %s\n",
 287                    ev->action, ev->path));
 288         listel->callback(listel->private_data, ev);
 289 }
 290
 291 /*
 292   add an entry to the notify array
 293 */
 294 static NTSTATUS notify_add_array(struct notify_context *notify, struct db_record *rec,
 295                                  struct notify_entry *e,
 296                                  void *private_data, int depth)
 297 {
 298         int i;
 299         struct notify_depth *d;
 300         struct notify_entry *ee;
 301
 302         /* possibly expand the depths array */
 303         if (depth >= notify->array->num_depths) {
 304                 d = talloc_realloc(notify->array, notify->array->depth,
 305                                    struct notify_depth, depth+1);
 306                 NT_STATUS_HAVE_NO_MEMORY(d);
 307                 for (i=notify->array->num_depths;i<=depth;i++) {
 308                         ZERO_STRUCT(d[i]);
 309                 }
 310                 notify->array->depth = d;
 311                 notify->array->num_depths = depth+1;
 312         }
 313         d = &notify->array->depth[depth];
 314
 315         /* expand the entries array */
 316         ee = talloc_realloc(notify->array->depth, d->entries, struct notify_entry,
 317                             d->num_entries+1);
 318         NT_STATUS_HAVE_NO_MEMORY(ee);
 319         d->entries = ee;
 320
 321         d->entries[d->num_entries] = *e;
 322         d->entries[d->num_entries].private_data = private_data;
 323         d->entries[d->num_entries].server = notify->server;
 324         d->entries[d->num_entries].path_len = strlen(e->path);
 325         d->num_entries++;
 326
 327         d->max_mask |= e->filter;
 328         d->max_mask_subdir |= e->subdir_filter;
 329
 330         if (d->num_entries > 1) {
 331                 qsort(d->entries, d->num_entries, sizeof(d->entries[0]), notify_compare);
 332         }
 333
 334         /* recalculate the maximum masks */
 335         d->max_mask = 0;
 336         d->max_mask_subdir = 0;
 337
 338         for (i=0;i<d->num_entries;i++) {
 339                 d->max_mask |= d->entries[i].filter;
 340                 d->max_mask_subdir |= d->entries[i].subdir_filter;
 341         }
 342
 343         return notify_save(notify, rec);
 344 }
 345
 346 /*
 347   add a notify watch. This is called when a notify is first setup on a open
 348   directory handle.
 349 */
 350 NTSTATUS notify_add(struct notify_context *notify, struct notify_entry *e0,
 351                     void (*callback)(void *, const struct notify_event *),
 352                     void *private_data)
 353 {
 354         struct notify_entry e = *e0;
 355         NTSTATUS status;
 356         char *tmp_path = NULL;
 357         struct notify_list *listel;
 358         size_t len;
 359         int depth;
 360         struct db_record *rec;
 361
 362         /* see if change notify is enabled at all */
 363         if (notify == NULL) {
 364                 return NT_STATUS_NOT_IMPLEMENTED;
 365         }
 366
 367         status = notify_fetch_locked(notify, &rec);
 368         NT_STATUS_NOT_OK_RETURN(status);
 369
 370         status = notify_load(notify, rec);
 371         if (!NT_STATUS_IS_OK(status)) {
 372                 talloc_free(rec);
 373                 return status;
 374         }
 375
 376         /* cope with /. on the end of the path */
 377         len = strlen(e.path);
 378         if (len > 1 && e.path[len-1] == '.' && e.path[len-2] == '/') {
 379                 tmp_path = talloc_strndup(notify, e.path, len-2);
 380                 if (tmp_path == NULL) {
 381                         status = NT_STATUS_NO_MEMORY;
 382                         goto done;
 383                 }
 384                 e.path = tmp_path;
 385         }
 386
 387         depth = count_chars(e.path, '/');
 388
 389         listel = TALLOC_ZERO_P(notify, struct notify_list);
 390         if (listel == NULL) {
 391                 status = NT_STATUS_NO_MEMORY;
 392                 goto done;
 393         }
 394
 395         listel->private_data = private_data;
 396         listel->callback = callback;
 397         listel->depth = depth;
 398         DLIST_ADD(notify->list, listel);
 399
 400         /* ignore failures from sys_notify */
 401         if (notify->sys_notify_ctx != NULL) {
 402                 /*
 403                   this call will modify e.filter and e.subdir_filter
 404                   to remove bits handled by the backend
 405                 */
 406                 status = sys_notify_watch(notify->sys_notify_ctx, &e,
 407                                           sys_notify_callback, listel,
 408                                           &listel->sys_notify_handle);
 409                 if (NT_STATUS_IS_OK(status)) {
 410                         talloc_steal(listel, listel->sys_notify_handle);
 411                 }
 412         }
 413
 414         /* if the system notify handler couldn't handle some of the
 415            filter bits, or couldn't handle a request for recursion
 416            then we need to install it in the array used for the
 417            intra-samba notify handling */
 418         if (e.filter != 0 || e.subdir_filter != 0) {
 419                 status = notify_add_array(notify, rec, &e, private_data, depth);
 420         }
 421
 422 done:
 423         talloc_free(rec);
 424         talloc_free(tmp_path);
 425
 426         return status;
 427 }
 428
 429 /*
 430   remove a notify watch. Called when the directory handle is closed
 431 */
 432 NTSTATUS notify_remove(struct notify_context *notify, void *private_data)
 433 {
 434         NTSTATUS status;
 435         struct notify_list *listel;
 436         int i, depth;
 437         struct notify_depth *d;
 438         struct db_record *rec;
 439
 440         /* see if change notify is enabled at all */
 441         if (notify == NULL) {
 442                 return NT_STATUS_NOT_IMPLEMENTED;
 443         }
 444
 445         for (listel=notify->list;listel;listel=listel->next) {
 446                 if (listel->private_data == private_data) {
 447                         DLIST_REMOVE(notify->list, listel);
 448                         break;
 449                 }
 450         }
 451         if (listel == NULL) {
 452                 return NT_STATUS_OBJECT_NAME_NOT_FOUND;
 453         }
 454
 455         depth = listel->depth;
 456
 457         talloc_free(listel);
 458
 459         status = notify_fetch_locked(notify, &rec);
 460         NT_STATUS_NOT_OK_RETURN(status);
 461
 462         status = notify_load(notify, rec);
 463         if (!NT_STATUS_IS_OK(status)) {
 464                 talloc_free(rec);
 465                 return status;
 466         }
 467
 468         if (depth >= notify->array->num_depths) {
 469                 talloc_free(rec);
 470                 return NT_STATUS_OBJECT_NAME_NOT_FOUND;
 471         }
 472
 473         /* we only have to search at the depth of this element */
 474         d = &notify->array->depth[depth];
 475
 476         for (i=0;i<d->num_entries;i++) {
 477                 if (private_data == d->entries[i].private_data &&
 478                     cluster_id_equal(&notify->server, &d->entries[i].server)) {
 479                         break;
 480                 }
 481         }
 482         if (i == d->num_entries) {
 483                 talloc_free(rec);
 484                 return NT_STATUS_OBJECT_NAME_NOT_FOUND;
 485         }
 486
 487         if (i < d->num_entries-1) {
 488                 memmove(&d->entries[i], &d->entries[i+1],
 489                         sizeof(d->entries[i])*(d->num_entries-(i+1)));
 490         }
 491         d->num_entries--;
 492
 493         status = notify_save(notify, rec);
 494
 495         talloc_free(rec);
 496
 497         return status;
 498 }
 499
 500 /*
 501   remove all notify watches for a messaging server
 502 */
 503 static NTSTATUS notify_remove_all(struct notify_context *notify,
 504                                   const struct server_id *server)
 505 {
 506         NTSTATUS status;
 507         int i, depth, del_count=0;
 508         struct db_record *rec;
 509
 510         status = notify_fetch_locked(notify, &rec);
 511         NT_STATUS_NOT_OK_RETURN(status);
 512
 513         status = notify_load(notify, rec);
 514         if (!NT_STATUS_IS_OK(status)) {
 515                 talloc_free(rec);
 516                 return status;
 517         }
 518
 519         /* we have to search for all entries across all depths, looking for matches
 520            for the server id */
 521         for (depth=0;depth<notify->array->num_depths;depth++) {
 522                 struct notify_depth *d = &notify->array->depth[depth];
 523                 for (i=0;i<d->num_entries;i++) {
 524                         if (cluster_id_equal(server, &d->entries[i].server)) {
 525                                 if (i < d->num_entries-1) {
 526                                         memmove(&d->entries[i], &d->entries[i+1],
 527                                                 sizeof(d->entries[i])*(d->num_entries-(i+1)));
 528                                 }
 529                                 i--;
 530                                 d->num_entries--;
 531                                 del_count++;
 532                         }
 533                 }
 534         }
 535
 536         if (del_count > 0) {
 537                 status = notify_save(notify, rec);
 538         }
 539
 540         talloc_free(rec);
 541
 542         return status;
 543 }
 544
 545
 546 /*
 547   send a notify message to another messaging server
 548 */
 549 static NTSTATUS notify_send(struct notify_context *notify, struct notify_entry *e,
 550                             const char *path, uint32_t action)
 551 {
 552         struct notify_event ev;
 553         DATA_BLOB data;
 554         NTSTATUS status;
 555         enum ndr_err_code ndr_err;
 556         TALLOC_CTX *tmp_ctx;
 557
 558         ev.action = action;
 559         ev.path = path;
 560         ev.private_data = e->private_data;
 561
 562         tmp_ctx = talloc_new(notify);
 563
 564         ndr_err = ndr_push_struct_blob(&data, tmp_ctx, NULL, &ev,
 565                                        (ndr_push_flags_fn_t)ndr_push_notify_event);
 566         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 567                 talloc_free(tmp_ctx);
 568                 return ndr_map_error2ntstatus(ndr_err);
 569         }
 570
 571         status = messaging_send(notify->messaging_ctx, e->server,
 572                                 MSG_PVFS_NOTIFY, &data);
 573         talloc_free(tmp_ctx);
 574         return status;
 575 }
 576
 577
 578 /*
 579   trigger a notify message for anyone waiting on a matching event
 580
 581   This function is called a lot, and needs to be very fast. The unusual data structure
 582   and traversal is designed to be fast in the average case, even for large numbers of
 583   notifies
 584 */
 585 void notify_trigger(struct notify_context *notify,
 586                     uint32_t action, uint32_t filter, const char *path)
 587 {
 588         NTSTATUS status;
 589         int depth;
 590         const char *p, *next_p;
 591
 592         DEBUG(10, ("notify_trigger called action=0x%x, filter=0x%x, "
 593                    "path=%s\n", (unsigned)action, (unsigned)filter, path));
 594
 595         /* see if change notify is enabled at all */
 596         if (notify == NULL) {
 597                 return;
 598         }
 599
 600  again:
 601         status = notify_load(notify, NULL);
 602         if (!NT_STATUS_IS_OK(status)) {
 603                 return;
 604         }
 605
 606         /* loop along the given path, working with each directory depth separately */
 607         for (depth=0,p=path;
 608              p && depth < notify->array->num_depths;
 609              p=next_p,depth++) {
 610                 int p_len = p - path;
 611                 int min_i, max_i, i;
 612                 struct notify_depth *d = &notify->array->depth[depth];
 613                 next_p = strchr(p+1, '/');
 614
 615                 /* see if there are any entries at this depth */
 616                 if (d->num_entries == 0) continue;
 617
 618                 /* try to skip based on the maximum mask. If next_p is
 619                  NULL then we know it will be a 'this directory'
 620                  match, otherwise it must be a subdir match */
 621                 if (next_p != NULL) {
 622                         if (0 == (filter & d->max_mask_subdir)) {
 623                                 continue;
 624                         }
 625                 } else {
 626                         if (0 == (filter & d->max_mask)) {
 627                                 continue;
 628                         }
 629                 }
 630
 631                 /* we know there is an entry here worth looking
 632                  for. Use a bisection search to find the first entry
 633                  with a matching path */
 634                 min_i = 0;
 635                 max_i = d->num_entries-1;
 636
 637                 while (min_i < max_i) {
 638                         struct notify_entry *e;
 639                         int cmp;
 640                         i = (min_i+max_i)/2;
 641                         e = &d->entries[i];
 642                         cmp = strncmp(path, e->path, p_len);
 643                         if (cmp == 0) {
 644                                 if (p_len == e->path_len) {
 645                                         max_i = i;
 646                                 } else {
 647                                         max_i = i-1;
 648                                 }
 649                         } else if (cmp < 0) {
 650                                 max_i = i-1;
 651                         } else {
 652                                 min_i = i+1;
 653                         }
 654                 }
 655
 656                 if (min_i != max_i) {
 657                         /* none match */
 658                         continue;
 659                 }
 660
 661                 /* we now know that the entries start at min_i */
 662                 for (i=min_i;i<d->num_entries;i++) {
 663                         struct notify_entry *e = &d->entries[i];
 664                         if (p_len != e->path_len ||
 665                             strncmp(path, e->path, p_len) != 0) break;
 666                         if (next_p != NULL) {
 667                                 if (0 == (filter & e->subdir_filter)) {
 668                                         continue;
 669                                 }
 670                         } else {
 671                                 if (0 == (filter & e->filter)) {
 672                                         continue;
 673                                 }
 674                         }
 675                         status = notify_send(notify, e, path + e->path_len + 1,
 676                                              action);
 677
 678                         if (NT_STATUS_EQUAL(
 679                                     status, NT_STATUS_INVALID_HANDLE)) {
 680                                 struct server_id server = e->server;
 681
 682                                 DEBUG(10, ("Deleting notify entries for "
 683                                            "process %s because it's gone\n",
 684                                            procid_str_static(&e->server)));
 685                                 notify_remove_all(notify, &server);
 686                                 goto again;
 687                         }
 688                 }
 689         }
 690 }