source3/lib/messages.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    Samba internal messaging functions
   4    Copyright (C) Andrew Tridgell 2000
   5    Copyright (C) 2001 by Martin Pool
   6    Copyright (C) 2002 by Jeremy Allison
   7    Copyright (C) 2007 by Volker Lendecke
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 3 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  21 */
  22
  23 /**
  24   @defgroup messages Internal messaging framework
  25   @{
  26   @file messages.c
  27
  28   @brief  Module for internal messaging between Samba daemons.
  29
  30    The idea is that if a part of Samba wants to do communication with
  31    another Samba process then it will do a message_register() of a
  32    dispatch function, and use message_send_pid() to send messages to
  33    that process.
  34
  35    The dispatch function is given the pid of the sender, and it can
  36    use that to reply by message_send_pid().  See ping_message() for a
  37    simple example.
  38
  39    @caution Dispatch functions must be able to cope with incoming
  40    messages on an *odd* byte boundary.
  41
  42    This system doesn't have any inherent size limitations but is not
  43    very efficient for large messages or when messages are sent in very
  44    quick succession.
  45
  46 */
  47
  48 #include "includes.h"
  49 #include "dbwrap/dbwrap.h"
  50 #include "serverid.h"
  51 #include "messages.h"
  52
  53 struct messaging_callback {
  54         struct messaging_callback *prev, *next;
  55         uint32 msg_type;
  56         void (*fn)(struct messaging_context *msg, void *private_data,
  57                    uint32_t msg_type,
  58                    struct server_id server_id, DATA_BLOB *data);
  59         void *private_data;
  60 };
  61
  62 /****************************************************************************
  63  A useful function for testing the message system.
  64 ****************************************************************************/
  65
  66 static void ping_message(struct messaging_context *msg_ctx,
  67                          void *private_data,
  68                          uint32_t msg_type,
  69                          struct server_id src,
  70                          DATA_BLOB *data)
  71 {
  72         const char *msg = data->data ? (const char *)data->data : "none";
  73
  74         DEBUG(1,("INFO: Received PING message from PID %s [%s]\n",
  75                  procid_str_static(&src), msg));
  76         messaging_send(msg_ctx, src, MSG_PONG, data);
  77 }
  78
  79 /****************************************************************************
  80  Register/replace a dispatch function for a particular message type.
  81  JRA changed Dec 13 2006. Only one message handler now permitted per type.
  82  *NOTE*: Dispatch functions must be able to cope with incoming
  83  messages on an *odd* byte boundary.
  84 ****************************************************************************/
  85
  86 struct msg_all {
  87         struct messaging_context *msg_ctx;
  88         int msg_type;
  89         uint32 msg_flag;
  90         const void *buf;
  91         size_t len;
  92         int n_sent;
  93 };
  94
  95 /****************************************************************************
  96  Send one of the messages for the broadcast.
  97 ****************************************************************************/
  98
  99 static int traverse_fn(struct db_record *rec, const struct server_id *id,
 100                        uint32_t msg_flags, void *state)
 101 {
 102         struct msg_all *msg_all = (struct msg_all *)state;
 103         NTSTATUS status;
 104
 105         /* Don't send if the receiver hasn't registered an interest. */
 106
 107         if((msg_flags & msg_all->msg_flag) == 0) {
 108                 return 0;
 109         }
 110
 111         /* If the msg send fails because the pid was not found (i.e. smbd died),
 112          * the msg has already been deleted from the messages.tdb.*/
 113
 114         status = messaging_send_buf(msg_all->msg_ctx, *id, msg_all->msg_type,
 115                                     (const uint8 *)msg_all->buf, msg_all->len);
 116
 117         if (NT_STATUS_EQUAL(status, NT_STATUS_INVALID_HANDLE)) {
 118
 119                 /*
 120                  * If the pid was not found delete the entry from
 121                  * serverid.tdb
 122                  */
 123
 124                 DEBUG(2, ("pid %s doesn't exist\n", procid_str_static(id)));
 125
 126                 dbwrap_record_delete(rec);
 127         }
 128         msg_all->n_sent++;
 129         return 0;
 130 }
 131
 132 /**
 133  * Send a message to all smbd processes.
 134  *
 135  * It isn't very efficient, but should be OK for the sorts of
 136  * applications that use it. When we need efficient broadcast we can add
 137  * it.
 138  *
 139  * @param n_sent Set to the number of messages sent.  This should be
 140  * equal to the number of processes, but be careful for races.
 141  *
 142  * @retval True for success.
 143  **/
 144 bool message_send_all(struct messaging_context *msg_ctx,
 145                       int msg_type,
 146                       const void *buf, size_t len,
 147                       int *n_sent)
 148 {
 149         struct msg_all msg_all;
 150
 151         msg_all.msg_type = msg_type;
 152         if (msg_type < 0x100) {
 153                 msg_all.msg_flag = FLAG_MSG_GENERAL;
 154         } else if (msg_type > 0x100 && msg_type < 0x200) {
 155                 msg_all.msg_flag = FLAG_MSG_NMBD;
 156         } else if (msg_type > 0x200 && msg_type < 0x300) {
 157                 msg_all.msg_flag = FLAG_MSG_PRINT_GENERAL;
 158         } else if (msg_type > 0x300 && msg_type < 0x400) {
 159                 msg_all.msg_flag = FLAG_MSG_SMBD;
 160         } else if (msg_type > 0x400 && msg_type < 0x600) {
 161                 msg_all.msg_flag = FLAG_MSG_WINBIND;
 162         } else if (msg_type > 4000 && msg_type < 5000) {
 163                 msg_all.msg_flag = FLAG_MSG_DBWRAP;
 164         } else {
 165                 return false;
 166         }
 167
 168         msg_all.buf = buf;
 169         msg_all.len = len;
 170         msg_all.n_sent = 0;
 171         msg_all.msg_ctx = msg_ctx;
 172
 173         serverid_traverse(traverse_fn, &msg_all);
 174         if (n_sent)
 175                 *n_sent = msg_all.n_sent;
 176         return true;
 177 }
 178
 179 struct event_context *messaging_event_context(struct messaging_context *msg_ctx)
 180 {
 181         return msg_ctx->event_ctx;
 182 }
 183
 184 struct messaging_context *messaging_init(TALLOC_CTX *mem_ctx,
 185                                          struct event_context *ev)
 186 {
 187         struct messaging_context *ctx;
 188         NTSTATUS status;
 189
 190         if (!(ctx = talloc_zero(mem_ctx, struct messaging_context))) {
 191                 return NULL;
 192         }
 193
 194         ctx->id = procid_self();
 195         ctx->event_ctx = ev;
 196
 197         status = messaging_tdb_init(ctx, ctx, &ctx->local);
 198
 199         if (!NT_STATUS_IS_OK(status)) {
 200                 DEBUG(2, ("messaging_tdb_init failed: %s\n",
 201                           nt_errstr(status)));
 202                 TALLOC_FREE(ctx);
 203                 return NULL;
 204         }
 205
 206 #ifdef CLUSTER_SUPPORT
 207         if (lp_clustering()) {
 208                 status = messaging_ctdbd_init(ctx, ctx, &ctx->remote);
 209
 210                 if (!NT_STATUS_IS_OK(status)) {
 211                         DEBUG(2, ("messaging_ctdbd_init failed: %s\n",
 212                                   nt_errstr(status)));
 213                         TALLOC_FREE(ctx);
 214                         return NULL;
 215                 }
 216         }
 217         ctx->id.vnn = get_my_vnn();
 218 #endif
 219
 220         messaging_register(ctx, NULL, MSG_PING, ping_message);
 221
 222         /* Register some debugging related messages */
 223
 224         register_msg_pool_usage(ctx);
 225         register_dmalloc_msgs(ctx);
 226         debug_register_msgs(ctx);
 227
 228         return ctx;
 229 }
 230
 231 struct server_id messaging_server_id(const struct messaging_context *msg_ctx)
 232 {
 233         return msg_ctx->id;
 234 }
 235
 236 /*
 237  * re-init after a fork
 238  */
 239 NTSTATUS messaging_reinit(struct messaging_context *msg_ctx)
 240 {
 241         NTSTATUS status;
 242
 243         TALLOC_FREE(msg_ctx->local);
 244
 245         msg_ctx->id = procid_self();
 246
 247         status = messaging_tdb_init(msg_ctx, msg_ctx, &msg_ctx->local);
 248         if (!NT_STATUS_IS_OK(status)) {
 249                 DEBUG(0, ("messaging_tdb_init failed: %s\n",
 250                           nt_errstr(status)));
 251                 return status;
 252         }
 253
 254 #ifdef CLUSTER_SUPPORT
 255         TALLOC_FREE(msg_ctx->remote);
 256
 257         if (lp_clustering()) {
 258                 status = messaging_ctdbd_init(msg_ctx, msg_ctx,
 259                                               &msg_ctx->remote);
 260
 261                 if (!NT_STATUS_IS_OK(status)) {
 262                         DEBUG(1, ("messaging_ctdbd_init failed: %s\n",
 263                                   nt_errstr(status)));
 264                         return status;
 265                 }
 266         }
 267
 268 #endif
 269
 270         return NT_STATUS_OK;
 271 }
 272
 273
 274 /*
 275  * Register a dispatch function for a particular message type. Allow multiple
 276  * registrants
 277 */
 278 NTSTATUS messaging_register(struct messaging_context *msg_ctx,
 279                             void *private_data,
 280                             uint32_t msg_type,
 281                             void (*fn)(struct messaging_context *msg,
 282                                        void *private_data,
 283                                        uint32_t msg_type,
 284                                        struct server_id server_id,
 285                                        DATA_BLOB *data))
 286 {
 287         struct messaging_callback *cb;
 288
 289         /*
 290          * Only one callback per type
 291          */
 292
 293         for (cb = msg_ctx->callbacks; cb != NULL; cb = cb->next) {
 294                 /* we allow a second registration of the same message
 295                    type if it has a different private pointer. This is
 296                    needed in, for example, the internal notify code,
 297                    which creates a new notify context for each tree
 298                    connect, and expects to receive messages to each of
 299                    them. */
 300                 if (cb->msg_type == msg_type && private_data == cb->private_data) {
 301                         DEBUG(5,("Overriding messaging pointer for type %u - private_data=%p\n",
 302                                   (unsigned)msg_type, private_data));
 303                         cb->fn = fn;
 304                         cb->private_data = private_data;
 305                         return NT_STATUS_OK;
 306                 }
 307         }
 308
 309         if (!(cb = talloc(msg_ctx, struct messaging_callback))) {
 310                 return NT_STATUS_NO_MEMORY;
 311         }
 312
 313         cb->msg_type = msg_type;
 314         cb->fn = fn;
 315         cb->private_data = private_data;
 316
 317         DLIST_ADD(msg_ctx->callbacks, cb);
 318         return NT_STATUS_OK;
 319 }
 320
 321 /*
 322   De-register the function for a particular message type.
 323 */
 324 void messaging_deregister(struct messaging_context *ctx, uint32_t msg_type,
 325                           void *private_data)
 326 {
 327         struct messaging_callback *cb, *next;
 328
 329         for (cb = ctx->callbacks; cb; cb = next) {
 330                 next = cb->next;
 331                 if ((cb->msg_type == msg_type)
 332                     && (cb->private_data == private_data)) {
 333                         DEBUG(5,("Deregistering messaging pointer for type %u - private_data=%p\n",
 334                                   (unsigned)msg_type, private_data));
 335                         DLIST_REMOVE(ctx->callbacks, cb);
 336                         TALLOC_FREE(cb);
 337                 }
 338         }
 339 }
 340
 341 /*
 342   Send a message to a particular server
 343 */
 344 NTSTATUS messaging_send(struct messaging_context *msg_ctx,
 345                         struct server_id server, uint32_t msg_type,
 346                         const DATA_BLOB *data)
 347 {
 348 #ifdef CLUSTER_SUPPORT
 349         if (!procid_is_local(&server)) {
 350                 return msg_ctx->remote->send_fn(msg_ctx, server,
 351                                                 msg_type, data,
 352                                                 msg_ctx->remote);
 353         }
 354 #endif
 355         return msg_ctx->local->send_fn(msg_ctx, server, msg_type, data,
 356                                        msg_ctx->local);
 357 }
 358
 359 NTSTATUS messaging_send_buf(struct messaging_context *msg_ctx,
 360                             struct server_id server, uint32_t msg_type,
 361                             const uint8 *buf, size_t len)
 362 {
 363         DATA_BLOB blob = data_blob_const(buf, len);
 364         return messaging_send(msg_ctx, server, msg_type, &blob);
 365 }
 366
 367 /*
 368   Dispatch one messaging_rec
 369 */
 370 void messaging_dispatch_rec(struct messaging_context *msg_ctx,
 371                             struct messaging_rec *rec)
 372 {
 373         struct messaging_callback *cb, *next;
 374
 375         for (cb = msg_ctx->callbacks; cb != NULL; cb = next) {
 376                 next = cb->next;
 377                 if (cb->msg_type == rec->msg_type) {
 378                         cb->fn(msg_ctx, cb->private_data, rec->msg_type,
 379                                rec->src, &rec->buf);
 380                         /* we continue looking for matching messages
 381                            after finding one. This matters for
 382                            subsystems like the internal notify code
 383                            which register more than one handler for
 384                            the same message type */
 385                 }
 386         }
 387         return;
 388 }
 389
 390 /** @} **/