source/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(0, ("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 #ifdef CLUSTER_SUPPORT
 239
 240         TALLOC_FREE(msg_ctx->remote);
 241
 242         if (lp_clustering()) {
 243                 NTSTATUS status;
 244
 245                 status = messaging_ctdbd_init(msg_ctx, msg_ctx,
 246                                               &msg_ctx->remote);
 247
 248                 if (!NT_STATUS_IS_OK(status)) {
 249                         DEBUG(0, ("messaging_ctdb_init failed: %s\n",
 250                                   nt_errstr(status)));
 251                         return status;
 252                 }
 253         }
 254
 255 #endif
 256
 257         return NT_STATUS_OK;
 258 }
 259
 260
 261 /*
 262  * Register a dispatch function for a particular message type. Allow multiple
 263  * registrants
 264 */
 265 NTSTATUS messaging_register(struct messaging_context *msg_ctx,
 266                             void *private_data,
 267                             uint32_t msg_type,
 268                             void (*fn)(struct messaging_context *msg,
 269                                        void *private_data,
 270                                        uint32_t msg_type,
 271                                        struct server_id server_id,
 272                                        DATA_BLOB *data))
 273 {
 274         struct messaging_callback *cb;
 275
 276         /*
 277          * Only one callback per type
 278          */
 279
 280         for (cb = msg_ctx->callbacks; cb != NULL; cb = cb->next) {
 281                 /* we allow a second registration of the same message
 282                    type if it has a different private pointer. This is
 283                    needed in, for example, the internal notify code,
 284                    which creates a new notify context for each tree
 285                    connect, and expects to receive messages to each of
 286                    them. */
 287                 if (cb->msg_type == msg_type && private_data == cb->private_data) {
 288                         DEBUG(5,("Overriding messaging pointer for type %u - private_data=%p\n",
 289                                   (unsigned)msg_type, private_data));
 290                         cb->fn = fn;
 291                         cb->private_data = private_data;
 292                         return NT_STATUS_OK;
 293                 }
 294         }
 295
 296         if (!(cb = talloc(msg_ctx, struct messaging_callback))) {
 297                 return NT_STATUS_NO_MEMORY;
 298         }
 299
 300         cb->msg_type = msg_type;
 301         cb->fn = fn;
 302         cb->private_data = private_data;
 303
 304         DLIST_ADD(msg_ctx->callbacks, cb);
 305         return NT_STATUS_OK;
 306 }
 307
 308 /*
 309   De-register the function for a particular message type.
 310 */
 311 void messaging_deregister(struct messaging_context *ctx, uint32_t msg_type,
 312                           void *private_data)
 313 {
 314         struct messaging_callback *cb, *next;
 315
 316         for (cb = ctx->callbacks; cb; cb = next) {
 317                 next = cb->next;
 318                 if ((cb->msg_type == msg_type)
 319                     && (cb->private_data == private_data)) {
 320                         DEBUG(5,("Deregistering messaging pointer for type %u - private_data=%p\n",
 321                                   (unsigned)msg_type, private_data));
 322                         DLIST_REMOVE(ctx->callbacks, cb);
 323                         TALLOC_FREE(cb);
 324                 }
 325         }
 326 }
 327
 328 /*
 329   Send a message to a particular server
 330 */
 331 NTSTATUS messaging_send(struct messaging_context *msg_ctx,
 332                         struct server_id server, uint32_t msg_type,
 333                         const DATA_BLOB *data)
 334 {
 335 #ifdef CLUSTER_SUPPORT
 336         if (!procid_is_local(&server)) {
 337                 return msg_ctx->remote->send_fn(msg_ctx, server,
 338                                                 msg_type, data,
 339                                                 msg_ctx->remote);
 340         }
 341 #endif
 342         return msg_ctx->local->send_fn(msg_ctx, server, msg_type, data,
 343                                        msg_ctx->local);
 344 }
 345
 346 NTSTATUS messaging_send_buf(struct messaging_context *msg_ctx,
 347                             struct server_id server, uint32_t msg_type,
 348                             const uint8 *buf, size_t len)
 349 {
 350         DATA_BLOB blob = data_blob_const(buf, len);
 351         return messaging_send(msg_ctx, server, msg_type, &blob);
 352 }
 353
 354 /*
 355   Dispatch one messsaging_rec
 356 */
 357 void messaging_dispatch_rec(struct messaging_context *msg_ctx,
 358                             struct messaging_rec *rec)
 359 {
 360         struct messaging_callback *cb, *next;
 361
 362         for (cb = msg_ctx->callbacks; cb != NULL; cb = next) {
 363                 next = cb->next;
 364                 if (cb->msg_type == rec->msg_type) {
 365                         cb->fn(msg_ctx, cb->private_data, rec->msg_type,
 366                                rec->src, &rec->buf);
 367                         /* we continue looking for matching messages
 368                            after finding one. This matters for
 369                            subsystems like the internal notify code
 370                            which register more than one handler for
 371                            the same message type */
 372                 }
 373         }
 374         return;
 375 }
 376
 377 /** @} **/