dbus/method.c

   1 /* -*- Mode: C ; c-basic-offset: 2 -*- */
   2 /*
   3  * LADI Session Handler (ladish)
   4  *
   5  * Copyright (C) 2008, 2009 Nedko Arnaudov <nedko@arnaudov.name>
   6  * Copyright (C) 2008 Juuso Alasuutari <juuso.alasuutari@gmail.com>
   7  *
   8  **************************************************************************
   9  * This file contains D-Bus methods helpers
  10  **************************************************************************
  11  *
  12  * LADI Session Handler is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License as published by
  14  * the Free Software Foundation; either version 2 of the License, or
  15  * (at your option) any later version.
  16  *
  17  * LADI Session Handler is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with LADI Session Handler. If not, see <http://www.gnu.org/licenses/>
  24  * or write to the Free Software Foundation, Inc.,
  25  * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  26  */
  27
  28 #include "../common/safety.h"
  29 #include "../common/debug.h"
  30
  31 #include "method.h"
  32 #include "service.h"
  33 #include "helpers.h"
  34
  35 /*
  36  * Construct a void method return.
  37  *
  38  * The operation can only fail due to lack of memory, in which case
  39  * there's no sense in trying to construct an error return. Instead,
  40  * call->reply will be set to NULL and handled in send_method_return().
  41  */
  42 void
  43 method_return_new_void(method_call_t *call)
  44 {
  45   if (!(call->reply = dbus_message_new_method_return(call->message))) {
  46     lash_error("Ran out of memory trying to construct method return");
  47   }
  48 }
  49
  50 /*
  51  * Construct a method return which holds a single argument or, if
  52  * the type parameter is DBUS_TYPE_INVALID, no arguments at all
  53  * (a void message).
  54  *
  55  * The operation can only fail due to lack of memory, in which case
  56  * there's no sense in trying to construct an error return. Instead,
  57  * call->reply will be set to NULL and handled in send_method_return().
  58  */
  59 void
  60 method_return_new_single(method_call_t *call,
  61                          int            type,
  62                          const void    *arg)
  63 {
  64   if (!call || !arg) {
  65     lash_error("Invalid arguments");
  66     return;
  67   }
  68
  69   call->reply = dbus_message_new_method_return(call->message);
  70
  71   if (!call->reply)
  72     goto fail_no_mem;
  73
  74   /* Void method return requested by caller. */
  75   // TODO: do we really need this?
  76   if (type == DBUS_TYPE_INVALID)
  77     return;
  78
  79   /* Prevent crash on NULL input string. */
  80   if (type == DBUS_TYPE_STRING && !(*((const char **) arg)))
  81     *((const char **) arg) = "";
  82
  83   DBusMessageIter iter;
  84
  85   dbus_message_iter_init_append(call->reply, &iter);
  86
  87   if (dbus_message_iter_append_basic(&iter, type, arg))
  88     return;
  89
  90   dbus_message_unref(call->reply);
  91   call->reply = NULL;
  92
  93 fail_no_mem:
  94   lash_error("Ran out of memory trying to construct method return");
  95 }
  96
  97 void
  98 method_return_new_valist(method_call_t *call,
  99                          int            type,
 100                                         ...)
 101 {
 102   if (!call) {
 103     lash_error("Call pointer is NULL");
 104     return;
 105   }
 106
 107   if (type == DBUS_TYPE_INVALID) {
 108     lash_error("No argument(s) supplied");
 109     return;
 110   }
 111
 112   va_list argp;
 113
 114   call->reply = dbus_message_new_method_return(call->message);
 115   if (!call->reply)
 116     goto fail_no_mem;
 117
 118   va_start(argp, type);
 119
 120   if (dbus_message_append_args_valist(call->reply, type, argp)) {
 121     va_end(argp);
 122     return;
 123   }
 124
 125   va_end(argp);
 126
 127   dbus_message_unref(call->reply);
 128   call->reply = NULL;
 129
 130 fail_no_mem:
 131   lash_error("Ran out of memory trying to construct method return");
 132 }
 133
 134 /*
 135  * Send a method call.
 136  */
 137 bool
 138 method_send(method_msg_t *call,
 139             bool          will_block)
 140 {
 141   if (!call->message) {
 142     lash_error("Cannot send method call: Message is NULL");
 143     return false;
 144   }
 145
 146   DBusPendingCall *pending = NULL;
 147   bool retval;
 148
 149   if (!dbus_connection_send_with_reply(call->service->connection,
 150                                        call->message, &pending, -1)) {
 151     lash_error("Ran out of memory trying to queue "
 152                "method call");
 153     retval = false;
 154     /* Never wait for a reply if sending failed */
 155     will_block = false;
 156   } else {
 157     if (pending)
 158       dbus_pending_call_set_notify(pending,
 159                                    call->return_handler,
 160                                    call->context, NULL);
 161     dbus_connection_flush(call->service->connection);
 162     retval = true;
 163   }
 164
 165   dbus_message_unref(call->message);
 166   call->message = NULL;
 167
 168   if (will_block && pending) {
 169     lash_debug("Blocking until a return arrives");
 170     dbus_pending_call_block(pending);
 171   }
 172
 173   return retval;
 174 }
 175
 176 /*
 177  * Send a method return.
 178  *
 179  * If call->reply is NULL, i.e. a previous attempt to construct
 180  * a return has failed, attempt to send a void return.
 181  */
 182 void
 183 method_return_send(method_call_t *call)
 184 {
 185   if (call->reply) {
 186   retry_send:
 187     if (!dbus_connection_send(call->connection, call->reply, NULL))
 188       lash_error("Ran out of memory trying to queue "
 189                  "method return");
 190     else
 191       dbus_connection_flush(call->connection);
 192
 193     dbus_message_unref(call->reply);
 194     call->reply = NULL;
 195   } else {
 196     lash_debug("Message was NULL, trying to construct a void return");
 197
 198     if ((call->reply = dbus_message_new_method_return(call->message))) {
 199       lash_debug("Constructed a void return, trying to queue it");
 200       goto retry_send;
 201     } else {
 202       lash_error("Failed to construct method return!");
 203     }
 204   }
 205 }
 206
 207 bool
 208 method_return_verify(DBusMessage  *msg,
 209                      const char  **str)
 210 {
 211   if (!msg || dbus_message_get_type(msg) != DBUS_MESSAGE_TYPE_ERROR)
 212     return true;
 213
 214   const char *ptr;
 215
 216   if (!dbus_message_get_args(msg, &g_dbus_error,
 217                              DBUS_TYPE_STRING, &ptr,
 218                              DBUS_TYPE_INVALID)) {
 219     lash_error("Cannot read description from D-Bus error message: %s ",
 220                g_dbus_error.message);
 221     dbus_error_free(&g_dbus_error);
 222     ptr = NULL;
 223   }
 224
 225   if (str)
 226     *str = ptr;
 227
 228   return false;
 229 }
 230
 231 /*
 232  * Append a variant type to a D-Bus message.
 233  * Return false if something fails, true otherwise.
 234  */
 235 bool
 236 method_iter_append_variant(DBusMessageIter *iter,
 237                            int              type,
 238                            const void      *arg)
 239 {
 240   DBusMessageIter sub_iter;
 241   char s[2];
 242
 243   s[0] = (char) type;
 244   s[1] = '\0';
 245
 246   /* Open a variant container. */
 247   if (!dbus_message_iter_open_container(iter, DBUS_TYPE_VARIANT,
 248                                         (const char *) s, &sub_iter))
 249     return false;
 250
 251   /* Append the supplied value. */
 252   if (!dbus_message_iter_append_basic(&sub_iter, type, arg)) {
 253     dbus_message_iter_close_container(iter, &sub_iter);
 254     return false;
 255   }
 256
 257   /* Close the container. */
 258   if (!dbus_message_iter_close_container(iter, &sub_iter))
 259     return false;
 260
 261   return true;
 262 }
 263
 264 static __inline__ bool
 265 method_iter_append_variant_raw(DBusMessageIter *iter,
 266                                const void      *buf,
 267                                int              len)
 268 {
 269   DBusMessageIter variant_iter, array_iter;
 270
 271   /* Open a variant container. */
 272   if (!dbus_message_iter_open_container(iter, DBUS_TYPE_VARIANT,
 273                                         "ay", &variant_iter))
 274     return false;
 275
 276   /* Open an array container. */
 277   if (!dbus_message_iter_open_container(&variant_iter, DBUS_TYPE_ARRAY,
 278                                         "y", &array_iter))
 279     goto fail;
 280
 281   /* Append the supplied data. */
 282   if (!dbus_message_iter_append_fixed_array(&array_iter, DBUS_TYPE_BYTE, buf, len)) {
 283     dbus_message_iter_close_container(&variant_iter, &array_iter);
 284     goto fail;
 285   }
 286
 287   /* Close the containers. */
 288   if (!dbus_message_iter_close_container(&variant_iter, &array_iter))
 289     goto fail;
 290   else if (!dbus_message_iter_close_container(iter, &variant_iter))
 291     return false;
 292
 293   return true;
 294
 295 fail:
 296   dbus_message_iter_close_container(iter, &variant_iter);
 297   return false;
 298 }
 299
 300 bool
 301 method_iter_append_dict_entry(DBusMessageIter *iter,
 302                               int              type,
 303                               const char      *key,
 304                               const void      *value,
 305                               int              length)
 306 {
 307   DBusMessageIter dict_iter;
 308
 309   if (!dbus_message_iter_open_container(iter, DBUS_TYPE_DICT_ENTRY,
 310                                         NULL, &dict_iter))
 311     return false;
 312
 313   if (!dbus_message_iter_append_basic(&dict_iter, DBUS_TYPE_STRING, &key))
 314     goto fail;
 315
 316   if (type == '-') {
 317     if (!method_iter_append_variant_raw(&dict_iter, value, length))
 318       goto fail;
 319   } else if (!method_iter_append_variant(&dict_iter, type, value))
 320     goto fail;
 321
 322   if (!dbus_message_iter_close_container(iter, &dict_iter))
 323     return false;
 324
 325   return true;
 326
 327 fail:
 328   dbus_message_iter_close_container(iter, &dict_iter);
 329   return false;
 330 }
 331
 332 void
 333 method_default_handler(DBusPendingCall *pending,
 334                        void            *data)
 335 {
 336   DBusMessage *msg = dbus_pending_call_steal_reply(pending);
 337
 338   if (msg) {
 339     const char *err_str;
 340
 341     if (!method_return_verify(msg, &err_str))
 342       lash_error("%s", err_str);
 343
 344     dbus_message_unref(msg);
 345   } else
 346     lash_error("Cannot get method return from pending call");
 347
 348   dbus_pending_call_unref(pending);
 349 }
 350
 351 bool
 352 method_call_init(method_msg_t                  *call,
 353                  service_t                     *service,
 354                  void                          *return_context,
 355                  DBusPendingCallNotifyFunction  return_handler,
 356                  const char                    *destination,
 357                  const char                    *path,
 358                  const char                    *interface,
 359                  const char                    *method)
 360 {
 361   if (!call || !service || !service->connection
 362       || !destination || !path || !method) {
 363     lash_error("Invalid arguments");
 364     return false;
 365   }
 366
 367   if (!interface)
 368     interface = "";
 369
 370   call->message = dbus_message_new_method_call(destination, path,
 371                                                interface, method);
 372   if (!call->message) {
 373     lash_error("Ran out of memory trying to create "
 374                "new method call");
 375     return false;
 376   }
 377
 378   call->service = service;
 379   call->context = return_context;
 380   call->return_handler = return_handler;
 381
 382   if (!return_handler)
 383     dbus_message_set_no_reply(call->message, true);
 384
 385   return true;
 386 }
 387
 388 bool
 389 method_call_new_void(service_t                     *service,
 390                      void                          *return_context,
 391                      DBusPendingCallNotifyFunction  return_handler,
 392                      bool                           will_block,
 393                      const char                    *destination,
 394                      const char                    *path,
 395                      const char                    *interface,
 396                      const char                    *method)
 397 {
 398   method_msg_t call;
 399
 400   if (method_call_init(&call, service, return_context, return_handler,
 401                        destination, path, interface, method))
 402     return method_send(&call, will_block);
 403
 404   return false;
 405 }
 406
 407 bool
 408 method_call_new_single(service_t                     *service,
 409                        void                          *return_context,
 410                        DBusPendingCallNotifyFunction  return_handler,
 411                        bool                           will_block,
 412                        const char                    *destination,
 413                        const char                    *path,
 414                        const char                    *interface,
 415                        const char                    *method,
 416                        int                            type,
 417                        const void                    *arg)
 418 {
 419   if (type == DBUS_TYPE_INVALID || !arg) {
 420     lash_error("No argument supplied");
 421     return false;
 422   }
 423
 424   method_msg_t call;
 425   DBusMessageIter iter;
 426
 427   if (!method_call_init(&call, service, return_context, return_handler,
 428                         destination, path, interface, method))
 429     return false;
 430
 431   dbus_message_iter_init_append(call.message, &iter);
 432
 433   if (dbus_message_iter_append_basic(&iter, type, arg)) {
 434     return method_send(&call, will_block);
 435   }
 436
 437   lash_error("Ran out of memory trying to append method call argument");
 438
 439   dbus_message_unref(call.message);
 440   call.message = NULL;
 441
 442   return false;
 443 }
 444
 445 bool
 446 method_call_new_valist(service_t                     *service,
 447                        void                          *return_context,
 448                        DBusPendingCallNotifyFunction  return_handler,
 449                        bool                           will_block,
 450                        const char                    *destination,
 451                        const char                    *path,
 452                        const char                    *interface,
 453                        const char                    *method,
 454                        int                            type,
 455                                                        ...)
 456 {
 457   if (type == DBUS_TYPE_INVALID) {
 458     lash_error("No argument(s) supplied");
 459     return false;
 460   }
 461
 462   method_msg_t call;
 463   va_list argp;
 464
 465   if (!method_call_init(&call, service, return_context, return_handler,
 466                         destination, path, interface, method))
 467     return false;
 468
 469   va_start(argp, type);
 470
 471   if (dbus_message_append_args_valist(call.message, type, argp)) {
 472     va_end(argp);
 473     return method_send(&call, will_block);
 474   }
 475
 476   va_end(argp);
 477
 478   lash_error("Ran out of memory trying to append "
 479              "method call argument(s)");
 480
 481   dbus_message_unref(call.message);
 482   call.message = NULL;
 483
 484   return false;
 485 }
 486
 487 bool
 488 method_iter_get_args(DBusMessageIter *iter,
 489                                       ...)
 490 {
 491   if (!iter) {
 492     lash_error("Iterator pointer is NULL");
 493     return false;
 494   }
 495
 496   va_list argp;
 497   int expected_type, type, n = 0;
 498   void *ptr;
 499
 500   va_start(argp, iter);
 501
 502   while ((expected_type = va_arg(argp, int)) != DBUS_TYPE_INVALID) {
 503     ptr = va_arg(argp, void *);
 504
 505     if ((type = dbus_message_iter_get_arg_type(iter))
 506         == DBUS_TYPE_INVALID) {
 507       lash_error("Insufficient arguments");
 508       va_end(argp);
 509       return false;
 510     }
 511
 512     if (type != expected_type) {
 513       lash_error("Invalid type for argument %i", n);
 514       va_end(argp);
 515       return false;
 516     }
 517
 518     if (ptr)
 519       dbus_message_iter_get_basic(iter, ptr);
 520
 521     dbus_message_iter_next(iter);
 522
 523     ++n;
 524   }
 525
 526   va_end(argp);
 527
 528   return true;
 529 }
 530
 531 bool
 532 method_iter_get_dict_entry(DBusMessageIter  *iter,
 533                            const char      **key_ptr,
 534                            void             *value_ptr,
 535                            int              *type_ptr,
 536                            int              *size_ptr)
 537 {
 538   if (!iter || !key_ptr || !value_ptr || !type_ptr) {
 539     lash_error("Invalid arguments");
 540     return false;
 541   }
 542
 543   DBusMessageIter dict_iter, variant_iter;
 544
 545   if (dbus_message_iter_get_arg_type(iter) != DBUS_TYPE_DICT_ENTRY) {
 546     lash_error("Iterator does not point to a dict entry container");
 547     return false;
 548   }
 549
 550   dbus_message_iter_recurse(iter, &dict_iter);
 551
 552   if (dbus_message_iter_get_arg_type(&dict_iter) != DBUS_TYPE_STRING) {
 553     lash_error("Cannot find key in dict entry container");
 554     return false;
 555   }
 556
 557   dbus_message_iter_get_basic(&dict_iter, key_ptr);
 558
 559   if (!dbus_message_iter_next(&dict_iter)
 560       || dbus_message_iter_get_arg_type(&dict_iter) != DBUS_TYPE_VARIANT) {
 561     lash_error("Cannot find variant container in dict entry");
 562     return false;
 563   }
 564
 565   dbus_message_iter_recurse(&dict_iter, &variant_iter);
 566
 567   *type_ptr = dbus_message_iter_get_arg_type(&variant_iter);
 568   if (*type_ptr == DBUS_TYPE_INVALID) {
 569     lash_error("Cannot find value in variant container");
 570     return false;
 571   }
 572
 573   if (*type_ptr == DBUS_TYPE_ARRAY) {
 574     DBusMessageIter array_iter;
 575     int n;
 576
 577     if (dbus_message_iter_get_element_type(&variant_iter)
 578         != DBUS_TYPE_BYTE) {
 579       lash_error("Dict entry value is a non-byte array");
 580       return false;
 581     }
 582     *type_ptr = '-';
 583
 584     dbus_message_iter_recurse(&variant_iter, &array_iter);
 585     dbus_message_iter_get_fixed_array(&array_iter, value_ptr, &n);
 586
 587     if (size_ptr)
 588       *size_ptr = n;
 589   } else
 590     dbus_message_iter_get_basic(&variant_iter, value_ptr);
 591
 592   return true;
 593 }
 594
 595 /* EOF */