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 "librpc/gen_ndr/messaging.h"
  50 #include "librpc/gen_ndr/ndr_messaging.h"
  51
  52 struct messaging_callback {
  53         struct messaging_callback *prev, *next;
  54         uint32 msg_type;
  55         void (*fn)(struct messaging_context *msg, void *private_data,
  56                    uint32_t msg_type,
  57                    struct server_id server_id, DATA_BLOB *data);
  58         void *private_data;
  59 };
  60
  61 /****************************************************************************
  62  A useful function for testing the message system.
  63 ****************************************************************************/
  64
  65 static void ping_message(struct messaging_context *msg_ctx,
  66                          void *private_data,
  67                          uint32_t msg_type,
  68                          struct server_id src,
  69                          DATA_BLOB *data)
  70 {
  71         const char *msg = data->data ? (const char *)data->data : "none";
  72
  73         DEBUG(1,("INFO: Received PING message from PID %s [%s]\n",
  74                  procid_str_static(&src), msg));
  75         messaging_send(msg_ctx, src, MSG_PONG, data);
  76 }
  77
  78 /****************************************************************************
  79  Register/replace a dispatch function for a particular message type.
  80  JRA changed Dec 13 2006. Only one message handler now permitted per type.
  81  *NOTE*: Dispatch functions must be able to cope with incoming
  82  messages on an *odd* byte boundary.
  83 ****************************************************************************/
  84
  85 struct msg_all {
  86         struct messaging_context *msg_ctx;
  87         int msg_type;
  88         uint32 msg_flag;
  89         const void *buf;
  90         size_t len;
  91         int n_sent;
  92 };
  93
  94 /****************************************************************************
  95  Send one of the messages for the broadcast.
  96 ****************************************************************************/
  97
  98 static int traverse_fn(struct db_record *rec,
  99                        const struct connections_key *ckey,
 100                        const struct connections_data *crec,
 101                        void *state)
 102 {
 103         struct msg_all *msg_all = (struct msg_all *)state;
 104         NTSTATUS status;
 105
 106         if (crec->cnum != -1)
 107                 return 0;
 108
 109         /* Don't send if the receiver hasn't registered an interest. */
 110
 111         if(!(crec->bcast_msg_flags & msg_all->msg_flag))
 112                 return 0;
 113
 114         /* If the msg send fails because the pid was not found (i.e. smbd died),
 115          * the msg has already been deleted from the messages.tdb.*/
 116
 117         status = messaging_send_buf(msg_all->msg_ctx,
 118                                     crec->pid, msg_all->msg_type,
 119                                     (uint8 *)msg_all->buf, msg_all->len);
 120
 121         if (NT_STATUS_EQUAL(status, NT_STATUS_INVALID_HANDLE)) {
 122
 123                 /* If the pid was not found delete the entry from connections.tdb */
 124
 125                 DEBUG(2,("pid %s doesn't exist - deleting connections %d [%s]\n",
 126                          procid_str_static(&crec->pid), crec->cnum,
 127                          crec->servicename));
 128
 129                 rec->delete_rec(rec);
 130         }
 131         msg_all->n_sent++;
 132         return 0;
 133 }
 134
 135 /**
 136  * Send a message to all smbd processes.
 137  *
 138  * It isn't very efficient, but should be OK for the sorts of
 139  * applications that use it. When we need efficient broadcast we can add
 140  * it.
 141  *
 142  * @param n_sent Set to the number of messages sent.  This should be
 143  * equal to the number of processes, but be careful for races.
 144  *
 145  * @retval True for success.
 146  **/
 147 bool message_send_all(struct messaging_context *msg_ctx,
 148                       int msg_type,
 149                       const void *buf, size_t len,
 150                       int *n_sent)
 151 {
 152         struct msg_all msg_all;
 153
 154         msg_all.msg_type = msg_type;
 155         if (msg_type < 1000)
 156                 msg_all.msg_flag = FLAG_MSG_GENERAL;
 157         else if (msg_type > 1000 && msg_type < 2000)
 158                 msg_all.msg_flag = FLAG_MSG_NMBD;
 159         else if (msg_type > 2000 && msg_type < 2100)
 160                 msg_all.msg_flag = FLAG_MSG_PRINT_NOTIFY;
 161         else if (msg_type > 2100 && msg_type < 3000)
 162                 msg_all.msg_flag = FLAG_MSG_PRINT_GENERAL;
 163         else if (msg_type > 3000 && msg_type < 4000)
 164                 msg_all.msg_flag = FLAG_MSG_SMBD;
 165         else if (msg_type > 4000 && msg_type < 5000)
 166                 msg_all.msg_flag = FLAG_MSG_DBWRAP;
 167         else
 168                 return False;
 169
 170         msg_all.buf = buf;
 171         msg_all.len = len;
 172         msg_all.n_sent = 0;
 173         msg_all.msg_ctx = msg_ctx;
 174
 175         connections_forall(traverse_fn, &msg_all);
 176         if (n_sent)
 177                 *n_sent = msg_all.n_sent;
 178         return True;
 179 }
 180
 181 struct event_context *messaging_event_context(struct messaging_context *msg_ctx)
 182 {
 183         return msg_ctx->event_ctx;
 184 }
 185
 186 struct messaging_context *messaging_init(TALLOC_CTX *mem_ctx,
 187                                          struct server_id server_id,
 188                                          struct event_context *ev)
 189 {
 190         struct messaging_context *ctx;
 191         NTSTATUS status;
 192
 193         if (!(ctx = TALLOC_ZERO_P(mem_ctx, struct messaging_context))) {
 194                 return NULL;
 195         }
 196
 197         ctx->id = server_id;
 198         ctx->event_ctx = ev;
 199
 200         status = messaging_tdb_init(ctx, ctx, &ctx->local);
 201
 202         if (!NT_STATUS_IS_OK(status)) {
 203                 DEBUG(0, ("messaging_tdb_init failed: %s\n",
 204                           nt_errstr(status)));
 205                 TALLOC_FREE(ctx);
 206                 return NULL;
 207         }
 208
 209 #ifdef CLUSTER_SUPPORT
 210         if (lp_clustering()) {
 211                 status = messaging_ctdbd_init(ctx, ctx, &ctx->remote);
 212
 213                 if (!NT_STATUS_IS_OK(status)) {
 214                         DEBUG(1, ("messaging_ctdb_init failed: %s\n",
 215                                   nt_errstr(status)));
 216                         TALLOC_FREE(ctx);
 217                         return NULL;
 218                 }
 219         }
 220 #endif
 221
 222         messaging_register(ctx, NULL, MSG_PING, ping_message);
 223
 224         /* Register some debugging related messages */
 225
 226         register_msg_pool_usage(ctx);
 227         register_dmalloc_msgs(ctx);
 228         debug_register_msgs(ctx);
 229
 230         return ctx;
 231 }
 232
 233 /*
 234  * re-init after a fork
 235  */
 236 NTSTATUS messaging_reinit(struct messaging_context *msg_ctx)
 237 {
 238         NTSTATUS status;
 239
 240         TALLOC_FREE(msg_ctx->local);
 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_ctdb_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         /*
 285          * Only one callback per type
 286          */
 287
 288         for (cb = msg_ctx->callbacks; cb != NULL; cb = cb->next) {
 289                 /* we allow a second registration of the same message
 290                    type if it has a different private pointer. This is
 291                    needed in, for example, the internal notify code,
 292                    which creates a new notify context for each tree
 293                    connect, and expects to receive messages to each of
 294                    them. */
 295                 if (cb->msg_type == msg_type && private_data == cb->private_data) {
 296                         DEBUG(5,("Overriding messaging pointer for type %u - private_data=%p\n",
 297                                   (unsigned)msg_type, private_data));
 298                         cb->fn = fn;
 299                         cb->private_data = private_data;
 300                         return NT_STATUS_OK;
 301                 }
 302         }
 303
 304         if (!(cb = talloc(msg_ctx, struct messaging_callback))) {
 305                 return NT_STATUS_NO_MEMORY;
 306         }
 307
 308         cb->msg_type = msg_type;
 309         cb->fn = fn;
 310         cb->private_data = private_data;
 311
 312         DLIST_ADD(msg_ctx->callbacks, cb);
 313         return NT_STATUS_OK;
 314 }
 315
 316 /*
 317   De-register the function for a particular message type.
 318 */
 319 void messaging_deregister(struct messaging_context *ctx, uint32_t msg_type,
 320                           void *private_data)
 321 {
 322         struct messaging_callback *cb, *next;
 323
 324         for (cb = ctx->callbacks; cb; cb = next) {
 325                 next = cb->next;
 326                 if ((cb->msg_type == msg_type)
 327                     && (cb->private_data == private_data)) {
 328                         DEBUG(5,("Deregistering messaging pointer for type %u - private_data=%p\n",
 329                                   (unsigned)msg_type, private_data));
 330                         DLIST_REMOVE(ctx->callbacks, cb);
 331                         TALLOC_FREE(cb);
 332                 }
 333         }
 334 }
 335
 336 /*
 337   Send a message to a particular server
 338 */
 339 NTSTATUS messaging_send(struct messaging_context *msg_ctx,
 340                         struct server_id server, uint32_t msg_type,
 341                         const DATA_BLOB *data)
 342 {
 343 #ifdef CLUSTER_SUPPORT
 344         if (!procid_is_local(&server)) {
 345                 return msg_ctx->remote->send_fn(msg_ctx, server,
 346                                                 msg_type, data,
 347                                                 msg_ctx->remote);
 348         }
 349 #endif
 350         return msg_ctx->local->send_fn(msg_ctx, server, msg_type, data,
 351                                        msg_ctx->local);
 352 }
 353
 354 NTSTATUS messaging_send_buf(struct messaging_context *msg_ctx,
 355                             struct server_id server, uint32_t msg_type,
 356                             const uint8 *buf, size_t len)
 357 {
 358         DATA_BLOB blob = data_blob_const(buf, len);
 359         return messaging_send(msg_ctx, server, msg_type, &blob);
 360 }
 361
 362 /*
 363   Dispatch one messsaging_rec
 364 */
 365 void messaging_dispatch_rec(struct messaging_context *msg_ctx,
 366                             struct messaging_rec *rec)
 367 {
 368         struct messaging_callback *cb, *next;
 369
 370         for (cb = msg_ctx->callbacks; cb != NULL; cb = next) {
 371                 next = cb->next;
 372                 if (cb->msg_type == rec->msg_type) {
 373                         cb->fn(msg_ctx, cb->private_data, rec->msg_type,
 374                                rec->src, &rec->buf);
 375                         /* we continue looking for matching messages
 376                            after finding one. This matters for
 377                            subsystems like the internal notify code
 378                            which register more than one handler for
 379                            the same message type */
 380                 }
 381         }
 382         return;
 383 }
 384
 385 /** @} **/