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 2 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, write to the Free Software
  18    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19 */
  20
  21 /*
  22   this is the change notify database. It implements mechanisms for
  23   storing current change notify waiters in a tdb, and checking if a
  24   given event matches any of the stored notify waiiters.
  25 */
  26
  27 #include "includes.h"
  28 #include "librpc/gen_ndr/ndr_notify.h"
  29
  30 struct notify_context {
  31         struct db_context *db;
  32         struct server_id server;
  33         struct messaging_context *messaging_ctx;
  34         struct notify_list *list;
  35         struct notify_array *array;
  36         int seqnum;
  37         struct sys_notify_context *sys_notify_ctx;
  38         TDB_DATA key;
  39 };
  40
  41
  42 struct notify_list {
  43         struct notify_list *next, *prev;
  44         void *private_data;
  45         void (*callback)(void *, const struct notify_event *);
  46         void *sys_notify_handle;
  47         int depth;
  48 };
  49
  50 #define NOTIFY_KEY "notify array"
  51
  52 #define NOTIFY_ENABLE           "notify:enable"
  53 #define NOTIFY_ENABLE_DEFAULT   True
  54
  55 static NTSTATUS notify_remove_all(struct notify_context *notify,
  56                                   const struct server_id *server);
  57 static void notify_handler(struct messaging_context *msg_ctx, void *private_data,
  58                            uint32_t msg_type, struct server_id server_id, DATA_BLOB *data);
  59
  60 /*
  61   destroy the notify context
  62 */
  63 static int notify_destructor(struct notify_context *notify)
  64 {
  65         messaging_deregister(notify->messaging_ctx, MSG_PVFS_NOTIFY, notify);
  66
  67         if (notify->list != NULL) {
  68                 notify_remove_all(notify, &notify->server);
  69         }
  70
  71         return 0;
  72 }
  73
  74 /*
  75   Open up the notify.tdb database. You should close it down using
  76   talloc_free(). We need the messaging_ctx to allow for notifications
  77   via internal messages
  78 */
  79 struct notify_context *notify_init(TALLOC_CTX *mem_ctx, struct server_id server,
  80                                    struct messaging_context *messaging_ctx,
  81                                    struct event_context *ev,
  82                                    connection_struct *conn)
  83 {
  84         struct notify_context *notify;
  85
  86         if (!lp_change_notify(conn->params)) {
  87                 return NULL;
  88         }
  89
  90         notify = talloc(mem_ctx, struct notify_context);
  91         if (notify == NULL) {
  92                 return NULL;
  93         }
  94
  95         notify->db = db_open(notify, lock_path("notify.tdb"),
  96                                   0, TDB_SEQNUM|TDB_CLEAR_IF_FIRST,
  97                                   O_RDWR|O_CREAT, 0644);
  98         if (notify->db == NULL) {
  99                 talloc_free(notify);
 100                 return NULL;
 101         }
 102
 103         notify->server = server;
 104         notify->messaging_ctx = messaging_ctx;
 105         notify->list = NULL;
 106         notify->array = NULL;
 107         notify->seqnum = notify->db->get_seqnum(notify->db);
 108         notify->key = string_term_tdb_data(NOTIFY_KEY);
 109
 110         talloc_set_destructor(notify, notify_destructor);
 111
 112         /* register with the messaging subsystem for the notify
 113            message type */
 114         messaging_register(notify->messaging_ctx, notify,
 115                            MSG_PVFS_NOTIFY, notify_handler);
 116
 117         notify->sys_notify_ctx = sys_notify_context_create(conn, notify, ev);
 118
 119         return notify;
 120 }
 121
 122 /*
 123   lock and fetch the record
 124 */
 125 static NTSTATUS notify_fetch_locked(struct notify_context *notify, struct db_record **rec)
 126 {
 127         *rec = notify->db->fetch_locked(notify->db, notify, notify->key);
 128         if (*rec == NULL) {
 129                 return NT_STATUS_INTERNAL_DB_CORRUPTION;
 130         }
 131         return NT_STATUS_OK;
 132 }
 133
 134 /*
 135   load the notify array
 136 */
 137 static NTSTATUS notify_load(struct notify_context *notify, struct db_record *rec)
 138 {
 139         TDB_DATA dbuf;
 140         DATA_BLOB blob;
 141         NTSTATUS status;
 142         int seqnum;
 143
 144         seqnum = notify->db->get_seqnum(notify->db);
 145
 146         if (seqnum == notify->seqnum && notify->array != NULL) {
 147                 return NT_STATUS_OK;
 148         }
 149
 150         notify->seqnum = seqnum;
 151
 152         talloc_free(notify->array);
 153         notify->array = TALLOC_ZERO_P(notify, struct notify_array);
 154         NT_STATUS_HAVE_NO_MEMORY(notify->array);
 155
 156         if (!rec) {
 157                 if (notify->db->fetch(notify->db, notify, notify->key, &dbuf) != 0) {
 158                         return NT_STATUS_INTERNAL_DB_CORRUPTION;
 159                 }
 160         } else {
 161                 dbuf = rec->value;
 162         }
 163
 164         blob.data = (uint8 *)dbuf.dptr;
 165         blob.length = dbuf.dsize;
 166
 167         if (blob.length == 0) {
 168                 status = NT_STATUS_OK;
 169         } else {
 170                 status = ndr_pull_struct_blob(&blob, notify->array, notify->array,
 171                                               (ndr_pull_flags_fn_t)ndr_pull_notify_array);
 172         }
 173
 174         if (DEBUGLEVEL >= 10) {
 175                 DEBUG(10, ("notify_load:\n"));
 176                 NDR_PRINT_DEBUG(notify_array, notify->array);
 177         }
 178
 179         if (!rec) {
 180                 talloc_free(dbuf.dptr);
 181         }
 182
 183         return status;
 184 }
 185
 186 /*
 187   compare notify entries for sorting
 188 */
 189 static int notify_compare(const void *p1, const void *p2)
 190 {
 191         const struct notify_entry *e1 = (const struct notify_entry *)p1;
 192         const struct notify_entry *e2 = (const struct notify_entry *)p2;
 193         return strcmp(e1->path, e2->path);
 194 }
 195
 196 /*
 197   save the notify array
 198 */
 199 static NTSTATUS notify_save(struct notify_context *notify, struct db_record *rec)
 200 {
 201         TDB_DATA dbuf;
 202         DATA_BLOB blob;
 203         NTSTATUS status;
 204         TALLOC_CTX *tmp_ctx;
 205
 206         /* if possible, remove some depth arrays */
 207         while (notify->array->num_depths > 0 &&
 208                notify->array->depth[notify->array->num_depths-1].num_entries == 0) {
 209                 notify->array->num_depths--;
 210         }
 211
 212         /* we might just be able to delete the record */
 213         if (notify->array->num_depths == 0) {
 214                 return rec->delete_rec(rec);
 215         }
 216
 217         tmp_ctx = talloc_new(notify);
 218         NT_STATUS_HAVE_NO_MEMORY(tmp_ctx);
 219
 220         status = ndr_push_struct_blob(&blob, tmp_ctx, notify->array,
 221                                       (ndr_push_flags_fn_t)ndr_push_notify_array);
 222         if (!NT_STATUS_IS_OK(status)) {
 223                 talloc_free(tmp_ctx);
 224                 return status;
 225         }
 226
 227         if (DEBUGLEVEL >= 10) {
 228                 DEBUG(10, ("notify_save:\n"));
 229                 NDR_PRINT_DEBUG(notify_array, notify->array);
 230         }
 231
 232         dbuf.dptr = blob.data;
 233         dbuf.dsize = blob.length;
 234
 235         status = rec->store(rec, dbuf, TDB_REPLACE);
 236         talloc_free(tmp_ctx);
 237
 238         return status;
 239 }
 240
 241
 242 /*
 243   handle incoming notify messages
 244 */
 245 static void notify_handler(struct messaging_context *msg_ctx, void *private_data,
 246                            uint32_t msg_type, struct server_id server_id, DATA_BLOB *data)
 247 {
 248         struct notify_context *notify = talloc_get_type(private_data, struct notify_context);
 249         NTSTATUS status;
 250         struct notify_event ev;
 251         TALLOC_CTX *tmp_ctx = talloc_new(notify);
 252         struct notify_list *listel;
 253
 254         if (tmp_ctx == NULL) {
 255                 return;
 256         }
 257
 258         status = ndr_pull_struct_blob(data, tmp_ctx, &ev,
 259                                       (ndr_pull_flags_fn_t)ndr_pull_notify_event);
 260         if (!NT_STATUS_IS_OK(status)) {
 261                 talloc_free(tmp_ctx);
 262                 return;
 263         }
 264
 265         for (listel=notify->list;listel;listel=listel->next) {
 266                 if (listel->private_data == ev.private_data) {
 267                         listel->callback(listel->private_data, &ev);
 268                         break;
 269                 }
 270         }
 271
 272         talloc_free(tmp_ctx);
 273 }
 274
 275 /*
 276   callback from sys_notify telling us about changes from the OS
 277 */
 278 static void sys_notify_callback(struct sys_notify_context *ctx,
 279                                 void *ptr, struct notify_event *ev)
 280 {
 281         struct notify_list *listel = talloc_get_type(ptr, struct notify_list);
 282         ev->private_data = listel;
 283         DEBUG(10, ("sys_notify_callback called with action=%d, for %s\n",
 284                    ev->action, ev->path));
 285         listel->callback(listel->private_data, ev);
 286 }
 287
 288 /*
 289   add an entry to the notify array
 290 */
 291 static NTSTATUS notify_add_array(struct notify_context *notify, struct db_record *rec,
 292                                  struct notify_entry *e,
 293                                  void *private_data, int depth)
 294 {
 295         int i;
 296         struct notify_depth *d;
 297         struct notify_entry *ee;
 298
 299         /* possibly expand the depths array */
 300         if (depth >= notify->array->num_depths) {
 301                 d = talloc_realloc(notify->array, notify->array->depth,
 302                                    struct notify_depth, depth+1);
 303                 NT_STATUS_HAVE_NO_MEMORY(d);
 304                 for (i=notify->array->num_depths;i<=depth;i++) {
 305                         ZERO_STRUCT(d[i]);
 306                 }
 307                 notify->array->depth = d;
 308                 notify->array->num_depths = depth+1;
 309         }
 310         d = &notify->array->depth[depth];
 311
 312         /* expand the entries array */
 313         ee = talloc_realloc(notify->array->depth, d->entries, struct notify_entry,
 314                             d->num_entries+1);
 315         NT_STATUS_HAVE_NO_MEMORY(ee);
 316         d->entries = ee;
 317
 318         d->entries[d->num_entries] = *e;
 319         d->entries[d->num_entries].private_data = private_data;
 320         d->entries[d->num_entries].server = notify->server;
 321         d->entries[d->num_entries].path_len = strlen(e->path);
 322         d->num_entries++;
 323
 324         d->max_mask |= e->filter;
 325         d->max_mask_subdir |= e->subdir_filter;
 326
 327         if (d->num_entries > 1) {
 328                 qsort(d->entries, d->num_entries, sizeof(d->entries[0]), notify_compare);
 329         }
 330
 331         /* recalculate the maximum masks */
 332         d->max_mask = 0;
 333         d->max_mask_subdir = 0;
 334
 335         for (i=0;i<d->num_entries;i++) {
 336                 d->max_mask |= d->entries[i].filter;
 337                 d->max_mask_subdir |= d->entries[i].subdir_filter;
 338         }
 339
 340         return notify_save(notify, rec);
 341 }
 342
 343 /*
 344   add a notify watch. This is called when a notify is first setup on a open
 345   directory handle.
 346 */
 347 NTSTATUS notify_add(struct notify_context *notify, struct notify_entry *e0,
 348                     void (*callback)(void *, const struct notify_event *),
 349                     void *private_data)
 350 {
 351         struct notify_entry e = *e0;
 352         NTSTATUS status;
 353         char *tmp_path = NULL;
 354         struct notify_list *listel;
 355         size_t len;
 356         int depth;
 357         struct db_record *rec;
 358
 359         /* see if change notify is enabled at all */
 360         if (notify == NULL) {
 361                 return NT_STATUS_NOT_IMPLEMENTED;
 362         }
 363
 364         status = notify_fetch_locked(notify, &rec);
 365         NT_STATUS_NOT_OK_RETURN(status);
 366
 367         status = notify_load(notify, rec);
 368         if (!NT_STATUS_IS_OK(status)) {
 369                 talloc_free(rec);
 370                 return status;
 371         }
 372
 373         /* cope with /. on the end of the path */
 374         len = strlen(e.path);
 375         if (len > 1 && e.path[len-1] == '.' && e.path[len-2] == '/') {
 376                 tmp_path = talloc_strndup(notify, e.path, len-2);
 377                 if (tmp_path == NULL) {
 378                         status = NT_STATUS_NO_MEMORY;
 379                         goto done;
 380                 }
 381                 e.path = tmp_path;
 382         }
 383
 384         depth = count_chars(e.path, '/');
 385
 386         listel = TALLOC_ZERO_P(notify, struct notify_list);
 387         if (listel == NULL) {
 388                 status = NT_STATUS_NO_MEMORY;
 389                 goto done;
 390         }
 391
 392         listel->private_data = private_data;
 393         listel->callback = callback;
 394         listel->depth = depth;
 395         DLIST_ADD(notify->list, listel);
 396
 397         /* ignore failures from sys_notify */
 398         if (notify->sys_notify_ctx != NULL) {
 399                 /*
 400                   this call will modify e.filter and e.subdir_filter
 401                   to remove bits handled by the backend
 402                 */
 403                 status = sys_notify_watch(notify->sys_notify_ctx, &e,
 404                                           sys_notify_callback, listel,
 405                                           &listel->sys_notify_handle);
 406                 if (NT_STATUS_IS_OK(status)) {
 407                         talloc_steal(listel, listel->sys_notify_handle);
 408                 }
 409         }
 410
 411         /* if the system notify handler couldn't handle some of the
 412            filter bits, or couldn't handle a request for recursion
 413            then we need to install it in the array used for the
 414            intra-samba notify handling */
 415         if (e.filter != 0 || e.subdir_filter != 0) {
 416                 status = notify_add_array(notify, rec, &e, private_data, depth);
 417         }
 418
 419 done:
 420         talloc_free(rec);
 421         talloc_free(tmp_path);
 422
 423         return status;
 424 }
 425
 426 /*
 427   remove a notify watch. Called when the directory handle is closed
 428 */
 429 NTSTATUS notify_remove(struct notify_context *notify, void *private_data)
 430 {
 431         NTSTATUS status;
 432         struct notify_list *listel;
 433         int i, depth;
 434         struct notify_depth *d;
 435         struct db_record *rec;
 436
 437         /* see if change notify is enabled at all */
 438         if (notify == NULL) {
 439                 return NT_STATUS_NOT_IMPLEMENTED;
 440         }
 441
 442         for (listel=notify->list;listel;listel=listel->next) {
 443                 if (listel->private_data == private_data) {
 444                         DLIST_REMOVE(notify->list, listel);
 445                         break;
 446                 }
 447         }
 448         if (listel == NULL) {
 449                 return NT_STATUS_OBJECT_NAME_NOT_FOUND;
 450         }
 451
 452         depth = listel->depth;
 453
 454         talloc_free(listel);
 455
 456         status = notify_fetch_locked(notify, &rec);
 457         NT_STATUS_NOT_OK_RETURN(status);
 458
 459         status = notify_load(notify, rec);
 460         if (!NT_STATUS_IS_OK(status)) {
 461                 talloc_free(rec);
 462                 return status;
 463         }
 464
 465         if (depth >= notify->array->num_depths) {
 466                 talloc_free(rec);
 467                 return NT_STATUS_OBJECT_NAME_NOT_FOUND;
 468         }
 469
 470         /* we only have to search at the depth of this element */
 471         d = &notify->array->depth[depth];
 472
 473         for (i=0;i<d->num_entries;i++) {
 474                 if (private_data == d->entries[i].private_data &&
 475                     cluster_id_equal(&notify->server, &d->entries[i].server)) {
 476                         break;
 477                 }
 478         }
 479         if (i == d->num_entries) {
 480                 talloc_free(rec);
 481                 return NT_STATUS_OBJECT_NAME_NOT_FOUND;
 482         }
 483
 484         if (i < d->num_entries-1) {
 485                 memmove(&d->entries[i], &d->entries[i+1],
 486                         sizeof(d->entries[i])*(d->num_entries-(i+1)));
 487         }
 488         d->num_entries--;
 489
 490         status = notify_save(notify, rec);
 491
 492         talloc_free(rec);
 493
 494         return status;
 495 }
 496
 497 /*
 498   remove all notify watches for a messaging server
 499 */
 500 static NTSTATUS notify_remove_all(struct notify_context *notify,
 501                                   const struct server_id *server)
 502 {
 503         NTSTATUS status;
 504         int i, depth, del_count=0;
 505         struct db_record *rec;
 506
 507         status = notify_fetch_locked(notify, &rec);
 508         NT_STATUS_NOT_OK_RETURN(status);
 509
 510         status = notify_load(notify, rec);
 511         if (!NT_STATUS_IS_OK(status)) {
 512                 talloc_free(rec);
 513                 return status;
 514         }
 515
 516         /* we have to search for all entries across all depths, looking for matches
 517            for the server id */
 518         for (depth=0;depth<notify->array->num_depths;depth++) {
 519                 struct notify_depth *d = &notify->array->depth[depth];
 520                 for (i=0;i<d->num_entries;i++) {
 521                         if (cluster_id_equal(server, &d->entries[i].server)) {
 522                                 if (i < d->num_entries-1) {
 523                                         memmove(&d->entries[i], &d->entries[i+1],
 524                                                 sizeof(d->entries[i])*(d->num_entries-(i+1)));
 525                                 }
 526                                 i--;
 527                                 d->num_entries--;
 528                                 del_count++;
 529                         }
 530                 }
 531         }
 532
 533         if (del_count > 0) {
 534                 status = notify_save(notify, rec);
 535         }
 536
 537         talloc_free(rec);
 538
 539         return status;
 540 }
 541
 542
 543 /*
 544   send a notify message to another messaging server
 545 */
 546 static NTSTATUS notify_send(struct notify_context *notify, struct notify_entry *e,
 547                             const char *path, uint32_t action)
 548 {
 549         struct notify_event ev;
 550         DATA_BLOB data;
 551         NTSTATUS status;
 552         TALLOC_CTX *tmp_ctx;
 553
 554         ev.action = action;
 555         ev.path = path;
 556         ev.private_data = e->private_data;
 557
 558         tmp_ctx = talloc_new(notify);
 559
 560         status = ndr_push_struct_blob(&data, tmp_ctx, &ev,
 561                                       (ndr_push_flags_fn_t)ndr_push_notify_event);
 562         if (!NT_STATUS_IS_OK(status)) {
 563                 talloc_free(tmp_ctx);
 564                 return status;
 565         }
 566
 567         status = messaging_send(notify->messaging_ctx, e->server,
 568                                 MSG_PVFS_NOTIFY, &data);
 569         talloc_free(tmp_ctx);
 570         return status;
 571 }
 572
 573
 574 /*
 575   trigger a notify message for anyone waiting on a matching event
 576
 577   This function is called a lot, and needs to be very fast. The unusual data structure
 578   and traversal is designed to be fast in the average case, even for large numbers of
 579   notifies
 580 */
 581 void notify_trigger(struct notify_context *notify,
 582                     uint32_t action, uint32_t filter, const char *path)
 583 {
 584         NTSTATUS status;
 585         int depth;
 586         const char *p, *next_p;
 587
 588         DEBUG(10, ("notify_trigger called action=0x%x, filter=0x%x, "
 589                    "path=%s\n", (unsigned)action, (unsigned)filter, path));
 590
 591         /* see if change notify is enabled at all */
 592         if (notify == NULL) {
 593                 return;
 594         }
 595
 596  again:
 597         status = notify_load(notify, NULL);
 598         if (!NT_STATUS_IS_OK(status)) {
 599                 return;
 600         }
 601
 602         /* loop along the given path, working with each directory depth separately */
 603         for (depth=0,p=path;
 604              p && depth < notify->array->num_depths;
 605              p=next_p,depth++) {
 606                 int p_len = p - path;
 607                 int min_i, max_i, i;
 608                 struct notify_depth *d = &notify->array->depth[depth];
 609                 next_p = strchr(p+1, '/');
 610
 611                 /* see if there are any entries at this depth */
 612                 if (d->num_entries == 0) continue;
 613
 614                 /* try to skip based on the maximum mask. If next_p is
 615                  NULL then we know it will be a 'this directory'
 616                  match, otherwise it must be a subdir match */
 617                 if (next_p != NULL) {
 618                         if (0 == (filter & d->max_mask_subdir)) {
 619                                 continue;
 620                         }
 621                 } else {
 622                         if (0 == (filter & d->max_mask)) {
 623                                 continue;
 624                         }
 625                 }
 626
 627                 /* we know there is an entry here worth looking
 628                  for. Use a bisection search to find the first entry
 629                  with a matching path */
 630                 min_i = 0;
 631                 max_i = d->num_entries-1;
 632
 633                 while (min_i < max_i) {
 634                         struct notify_entry *e;
 635                         int cmp;
 636                         i = (min_i+max_i)/2;
 637                         e = &d->entries[i];
 638                         cmp = strncmp(path, e->path, p_len);
 639                         if (cmp == 0) {
 640                                 if (p_len == e->path_len) {
 641                                         max_i = i;
 642                                 } else {
 643                                         max_i = i-1;
 644                                 }
 645                         } else if (cmp < 0) {
 646                                 max_i = i-1;
 647                         } else {
 648                                 min_i = i+1;
 649                         }
 650                 }
 651
 652                 if (min_i != max_i) {
 653                         /* none match */
 654                         continue;
 655                 }
 656
 657                 /* we now know that the entries start at min_i */
 658                 for (i=min_i;i<d->num_entries;i++) {
 659                         struct notify_entry *e = &d->entries[i];
 660                         if (p_len != e->path_len ||
 661                             strncmp(path, e->path, p_len) != 0) break;
 662                         if (next_p != NULL) {
 663                                 if (0 == (filter & e->subdir_filter)) {
 664                                         continue;
 665                                 }
 666                         } else {
 667                                 if (0 == (filter & e->filter)) {
 668                                         continue;
 669                                 }
 670                         }
 671                         status = notify_send(notify, e, path + e->path_len + 1,
 672                                              action);
 673
 674                         if (NT_STATUS_EQUAL(
 675                                     status, NT_STATUS_INVALID_HANDLE)) {
 676                                 struct server_id server = e->server;
 677
 678                                 DEBUG(10, ("Deleting notify entries for "
 679                                            "process %s because it's gone\n",
 680                                            procid_str_static(&e->server)));
 681                                 notify_remove_all(notify, &server);
 682                                 goto again;
 683                         }
 684                 }
 685         }
 686 }