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