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 messaging_context *messaging_init(TALLOC_CTX *mem_ctx,
 180                                          struct event_context *ev)
 181 {
 182         struct messaging_context *ctx;
 183         NTSTATUS status;
 184
 185         if (!(ctx = talloc_zero(mem_ctx, struct messaging_context))) {
 186                 return NULL;
 187         }
 188
 189         ctx->id = procid_self();
 190         ctx->event_ctx = ev;
 191
 192         status = messaging_tdb_init(ctx, ctx, &ctx->local);
 193
 194         if (!NT_STATUS_IS_OK(status)) {
 195                 DEBUG(2, ("messaging_tdb_init failed: %s\n",
 196                           nt_errstr(status)));
 197                 TALLOC_FREE(ctx);
 198                 return NULL;
 199         }
 200
 201 #ifdef CLUSTER_SUPPORT
 202         if (lp_clustering()) {
 203                 status = messaging_ctdbd_init(ctx, ctx, &ctx->remote);
 204
 205                 if (!NT_STATUS_IS_OK(status)) {
 206                         DEBUG(2, ("messaging_ctdbd_init failed: %s\n",
 207                                   nt_errstr(status)));
 208                         TALLOC_FREE(ctx);
 209                         return NULL;
 210                 }
 211         }
 212         ctx->id.vnn = get_my_vnn();
 213 #endif
 214
 215         messaging_register(ctx, NULL, MSG_PING, ping_message);
 216
 217         /* Register some debugging related messages */
 218
 219         register_msg_pool_usage(ctx);
 220         register_dmalloc_msgs(ctx);
 221         debug_register_msgs(ctx);
 222
 223         return ctx;
 224 }
 225
 226 struct server_id messaging_server_id(const struct messaging_context *msg_ctx)
 227 {
 228         return msg_ctx->id;
 229 }
 230
 231 /*
 232  * re-init after a fork
 233  */
 234 NTSTATUS messaging_reinit(struct messaging_context *msg_ctx)
 235 {
 236         NTSTATUS status;
 237
 238         TALLOC_FREE(msg_ctx->local);
 239
 240         msg_ctx->id = procid_self();
 241
 242         status = messaging_tdb_init(msg_ctx, msg_ctx, &msg_ctx->local);
 243         if (!NT_STATUS_IS_OK(status)) {
 244                 DEBUG(0, ("messaging_tdb_init failed: %s\n",
 245                           nt_errstr(status)));
 246                 return status;
 247         }
 248
 249 #ifdef CLUSTER_SUPPORT
 250         TALLOC_FREE(msg_ctx->remote);
 251
 252         if (lp_clustering()) {
 253                 status = messaging_ctdbd_init(msg_ctx, msg_ctx,
 254                                               &msg_ctx->remote);
 255
 256                 if (!NT_STATUS_IS_OK(status)) {
 257                         DEBUG(1, ("messaging_ctdbd_init failed: %s\n",
 258                                   nt_errstr(status)));
 259                         return status;
 260                 }
 261         }
 262
 263 #endif
 264
 265         return NT_STATUS_OK;
 266 }
 267
 268
 269 /*
 270  * Register a dispatch function for a particular message type. Allow multiple
 271  * registrants
 272 */
 273 NTSTATUS messaging_register(struct messaging_context *msg_ctx,
 274                             void *private_data,
 275                             uint32_t msg_type,
 276                             void (*fn)(struct messaging_context *msg,
 277                                        void *private_data,
 278                                        uint32_t msg_type,
 279                                        struct server_id server_id,
 280                                        DATA_BLOB *data))
 281 {
 282         struct messaging_callback *cb;
 283
 284         DEBUG(5, ("Registering messaging pointer for type %u - "
 285                   "private_data=%p\n",
 286                   (unsigned)msg_type, private_data));
 287
 288         /*
 289          * Only one callback per type
 290          */
 291
 292         for (cb = msg_ctx->callbacks; cb != NULL; cb = cb->next) {
 293                 /* we allow a second registration of the same message
 294                    type if it has a different private pointer. This is
 295                    needed in, for example, the internal notify code,
 296                    which creates a new notify context for each tree
 297                    connect, and expects to receive messages to each of
 298                    them. */
 299                 if (cb->msg_type == msg_type && private_data == cb->private_data) {
 300                         DEBUG(5,("Overriding messaging pointer for type %u - private_data=%p\n",
 301                                   (unsigned)msg_type, private_data));
 302                         cb->fn = fn;
 303                         cb->private_data = private_data;
 304                         return NT_STATUS_OK;
 305                 }
 306         }
 307
 308         if (!(cb = talloc(msg_ctx, struct messaging_callback))) {
 309                 return NT_STATUS_NO_MEMORY;
 310         }
 311
 312         cb->msg_type = msg_type;
 313         cb->fn = fn;
 314         cb->private_data = private_data;
 315
 316         DLIST_ADD(msg_ctx->callbacks, cb);
 317         return NT_STATUS_OK;
 318 }
 319
 320 /*
 321   De-register the function for a particular message type.
 322 */
 323 void messaging_deregister(struct messaging_context *ctx, uint32_t msg_type,
 324                           void *private_data)
 325 {
 326         struct messaging_callback *cb, *next;
 327
 328         for (cb = ctx->callbacks; cb; cb = next) {
 329                 next = cb->next;
 330                 if ((cb->msg_type == msg_type)
 331                     && (cb->private_data == private_data)) {
 332                         DEBUG(5,("Deregistering messaging pointer for type %u - private_data=%p\n",
 333                                   (unsigned)msg_type, private_data));
 334                         DLIST_REMOVE(ctx->callbacks, cb);
 335                         TALLOC_FREE(cb);
 336                 }
 337         }
 338 }
 339
 340 /*
 341   Send a message to a particular server
 342 */
 343 NTSTATUS messaging_send(struct messaging_context *msg_ctx,
 344                         struct server_id server, uint32_t msg_type,
 345                         const DATA_BLOB *data)
 346 {
 347 #ifdef CLUSTER_SUPPORT
 348         if (!procid_is_local(&server)) {
 349                 return msg_ctx->remote->send_fn(msg_ctx, server,
 350                                                 msg_type, data,
 351                                                 msg_ctx->remote);
 352         }
 353 #endif
 354         return msg_ctx->local->send_fn(msg_ctx, server, msg_type, data,
 355                                        msg_ctx->local);
 356 }
 357
 358 NTSTATUS messaging_send_buf(struct messaging_context *msg_ctx,
 359                             struct server_id server, uint32_t msg_type,
 360                             const uint8 *buf, size_t len)
 361 {
 362         DATA_BLOB blob = data_blob_const(buf, len);
 363         return messaging_send(msg_ctx, server, msg_type, &blob);
 364 }
 365
 366 /*
 367   Dispatch one messaging_rec
 368 */
 369 void messaging_dispatch_rec(struct messaging_context *msg_ctx,
 370                             struct messaging_rec *rec)
 371 {
 372         struct messaging_callback *cb, *next;
 373
 374         for (cb = msg_ctx->callbacks; cb != NULL; cb = next) {
 375                 next = cb->next;
 376                 if (cb->msg_type == rec->msg_type) {
 377                         cb->fn(msg_ctx, cb->private_data, rec->msg_type,
 378                                rec->src, &rec->buf);
 379                         /* we continue looking for matching messages
 380                            after finding one. This matters for
 381                            subsystems like the internal notify code
 382                            which register more than one handler for
 383                            the same message type */
 384                 }
 385         }
 386         return;
 387 }
 388
 389 /** @} **/