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 2 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, write to the Free Software
  21    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  22 */
  23
  24 /**
  25   @defgroup messages Internal messaging framework
  26   @{
  27   @file messages.c
  28
  29   @brief  Module for internal messaging between Samba daemons.
  30
  31    The idea is that if a part of Samba wants to do communication with
  32    another Samba process then it will do a message_register() of a
  33    dispatch function, and use message_send_pid() to send messages to
  34    that process.
  35
  36    The dispatch function is given the pid of the sender, and it can
  37    use that to reply by message_send_pid().  See ping_message() for a
  38    simple example.
  39
  40    @caution Dispatch functions must be able to cope with incoming
  41    messages on an *odd* byte boundary.
  42
  43    This system doesn't have any inherent size limitations but is not
  44    very efficient for large messages or when messages are sent in very
  45    quick succession.
  46
  47 */
  48
  49 #include "includes.h"
  50 #include "librpc/gen_ndr/messaging.h"
  51 #include "librpc/gen_ndr/ndr_messaging.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(TDB_CONTEXT *the_tdb,
 100                        const struct connections_key *ckey,
 101                        const struct connections_data *crec,
 102                        void *private_data)
 103 {
 104         struct msg_all *msg_all = (struct msg_all *)private_data;
 105         NTSTATUS status;
 106
 107         if (crec->cnum != -1)
 108                 return 0;
 109
 110         /* Don't send if the receiver hasn't registered an interest. */
 111
 112         if(!(crec->bcast_msg_flags & msg_all->msg_flag))
 113                 return 0;
 114
 115         /* If the msg send fails because the pid was not found (i.e. smbd died),
 116          * the msg has already been deleted from the messages.tdb.*/
 117
 118         status = messaging_send_buf(msg_all->msg_ctx,
 119                                     crec->pid, msg_all->msg_type,
 120                                     (uint8 *)msg_all->buf, msg_all->len);
 121
 122         if (NT_STATUS_EQUAL(status, NT_STATUS_INVALID_HANDLE)) {
 123
 124                 TDB_DATA key;
 125
 126                 /* If the pid was not found delete the entry from
 127                  * connections.tdb */
 128
 129                 DEBUG(2,("pid %s doesn't exist - deleting connections "
 130                          "%d [%s]\n", procid_str_static(&crec->pid),
 131                          crec->cnum, crec->servicename));
 132
 133                 key.dptr = (uint8 *)ckey;
 134                 key.dsize = sizeof(*ckey);
 135
 136                 tdb_delete(the_tdb, key);
 137         }
 138         msg_all->n_sent++;
 139         return 0;
 140 }
 141
 142 /**
 143  * Send a message to all smbd processes.
 144  *
 145  * It isn't very efficient, but should be OK for the sorts of
 146  * applications that use it. When we need efficient broadcast we can add
 147  * it.
 148  *
 149  * @param n_sent Set to the number of messages sent.  This should be
 150  * equal to the number of processes, but be careful for races.
 151  *
 152  * @retval True for success.
 153  **/
 154 BOOL message_send_all(struct messaging_context *msg_ctx,
 155                       int msg_type,
 156                       const void *buf, size_t len,
 157                       int *n_sent)
 158 {
 159         struct msg_all msg_all;
 160
 161         msg_all.msg_type = msg_type;
 162         if (msg_type < 1000)
 163                 msg_all.msg_flag = FLAG_MSG_GENERAL;
 164         else if (msg_type > 1000 && msg_type < 2000)
 165                 msg_all.msg_flag = FLAG_MSG_NMBD;
 166         else if (msg_type > 2000 && msg_type < 2100)
 167                 msg_all.msg_flag = FLAG_MSG_PRINT_NOTIFY;
 168         else if (msg_type > 2100 && msg_type < 3000)
 169                 msg_all.msg_flag = FLAG_MSG_PRINT_GENERAL;
 170         else if (msg_type > 3000 && msg_type < 4000)
 171                 msg_all.msg_flag = FLAG_MSG_SMBD;
 172         else
 173                 return False;
 174
 175         msg_all.buf = buf;
 176         msg_all.len = len;
 177         msg_all.n_sent = 0;
 178         msg_all.msg_ctx = msg_ctx;
 179
 180         connections_forall(traverse_fn, &msg_all);
 181         if (n_sent)
 182                 *n_sent = msg_all.n_sent;
 183         return True;
 184 }
 185
 186 struct event_context *messaging_event_context(struct messaging_context *msg_ctx)
 187 {
 188         return msg_ctx->event_ctx;
 189 }
 190
 191 struct messaging_context *messaging_init(TALLOC_CTX *mem_ctx,
 192                                          struct server_id server_id,
 193                                          struct event_context *ev)
 194 {
 195         struct messaging_context *ctx;
 196         NTSTATUS status;
 197
 198         if (!(ctx = TALLOC_ZERO_P(mem_ctx, struct messaging_context))) {
 199                 return NULL;
 200         }
 201
 202         ctx->id = server_id;
 203         ctx->event_ctx = ev;
 204
 205         status = messaging_tdb_init(ctx, ctx, &ctx->local);
 206
 207         if (!NT_STATUS_IS_OK(status)) {
 208                 DEBUG(0, ("message_init failed: %s\n", nt_errstr(status)));
 209                 TALLOC_FREE(ctx);
 210         }
 211
 212         messaging_register(ctx, NULL, MSG_PING, ping_message);
 213
 214         /* Register some debugging related messages */
 215
 216         register_msg_pool_usage(ctx);
 217         register_dmalloc_msgs(ctx);
 218         debug_register_msgs(ctx);
 219
 220         return ctx;
 221 }
 222
 223 /*
 224  * Register a dispatch function for a particular message type. Allow multiple
 225  * registrants
 226 */
 227 NTSTATUS messaging_register(struct messaging_context *msg_ctx,
 228                             void *private_data,
 229                             uint32_t msg_type,
 230                             void (*fn)(struct messaging_context *msg,
 231                                        void *private_data,
 232                                        uint32_t msg_type,
 233                                        struct server_id server_id,
 234                                        DATA_BLOB *data))
 235 {
 236         struct messaging_callback *cb;
 237
 238         /*
 239          * Only one callback per type
 240          */
 241
 242         for (cb = msg_ctx->callbacks; cb != NULL; cb = cb->next) {
 243                 if (cb->msg_type == msg_type) {
 244                         cb->fn = fn;
 245                         cb->private_data = private_data;
 246                         return NT_STATUS_OK;
 247                 }
 248         }
 249
 250         if (!(cb = talloc(msg_ctx, struct messaging_callback))) {
 251                 return NT_STATUS_NO_MEMORY;
 252         }
 253
 254         cb->msg_type = msg_type;
 255         cb->fn = fn;
 256         cb->private_data = private_data;
 257
 258         DLIST_ADD(msg_ctx->callbacks, cb);
 259         return NT_STATUS_OK;
 260 }
 261
 262 /*
 263   De-register the function for a particular message type.
 264 */
 265 void messaging_deregister(struct messaging_context *ctx, uint32_t msg_type,
 266                           void *private_data)
 267 {
 268         struct messaging_callback *cb, *next;
 269
 270         for (cb = ctx->callbacks; cb; cb = next) {
 271                 next = cb->next;
 272                 if ((cb->msg_type == msg_type)
 273                     && (cb->private_data == private_data)) {
 274                         DLIST_REMOVE(ctx->callbacks, cb);
 275                         TALLOC_FREE(cb);
 276                 }
 277         }
 278 }
 279
 280 /*
 281   Send a message to a particular server
 282 */
 283 NTSTATUS messaging_send(struct messaging_context *msg_ctx,
 284                         struct server_id server, uint32_t msg_type,
 285                         const DATA_BLOB *data)
 286 {
 287         return msg_ctx->local->send_fn(msg_ctx, server, msg_type, data,
 288                                        msg_ctx->local);
 289 }
 290
 291 NTSTATUS messaging_send_buf(struct messaging_context *msg_ctx,
 292                             struct server_id server, uint32_t msg_type,
 293                             const uint8 *buf, size_t len)
 294 {
 295         DATA_BLOB blob = data_blob_const(buf, len);
 296         return messaging_send(msg_ctx, server, msg_type, &blob);
 297 }
 298
 299 /*
 300   Dispatch one messsaging_rec
 301 */
 302 void messaging_dispatch_rec(struct messaging_context *msg_ctx,
 303                             struct messaging_rec *rec)
 304 {
 305         struct messaging_callback *cb, *next;
 306
 307         for (cb = msg_ctx->callbacks; cb != NULL; cb = next) {
 308                 next = cb->next;
 309                 if (cb->msg_type == rec->msg_type) {
 310                         cb->fn(msg_ctx, cb->private_data, rec->msg_type,
 311                                rec->src, &rec->buf);
 312                         return;
 313                 }
 314         }
 315         return;
 316 }
 317
 318 /** @} **/