dbus/object_path.c

   1 /* -*- Mode: C ; c-basic-offset: 2 -*- */
   2 /*
   3  * LADI Session Handler (ladish)
   4  *
   5  * Copyright (C) 2008, 2009, 2010 Nedko Arnaudov <nedko@arnaudov.name>
   6  * Copyright (C) 2008 Juuso Alasuutari <juuso.alasuutari@gmail.com>
   7  *
   8  **************************************************************************
   9  * This file contains D-Bus object path helpers
  10  **************************************************************************
  11  *
  12  * Licensed under the Academic Free License version 2.1
  13  *
  14  * LADI Session Handler is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation; either version 2 of the License, or
  17  * (at your option) any later version.
  18  *
  19  * LADI Session Handler is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with LADI Session Handler. If not, see <http://www.gnu.org/licenses/>
  26  * or write to the Free Software Foundation, Inc.,
  27  * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  28  */
  29
  30 #include "../common.h"
  31 #include "helpers.h"
  32 #include "error.h"  /* lash_dbus_error() */
  33
  34 struct dbus_object_path_interface
  35 {
  36   const struct dbus_interface_descriptor * iface;
  37   void * iface_context;
  38 };
  39
  40 struct dbus_object_path
  41 {
  42   char * name;
  43   DBusMessage * introspection;
  44   struct dbus_object_path_interface * ifaces;
  45   bool registered;
  46 };
  47
  48 #define write_buf(args...) buf_ptr += sprintf(buf_ptr, ## args)
  49
  50 DBusMessage *
  51 introspection_new(struct dbus_object_path * opath_ptr)
  52 {
  53   char *xml_data, *buf_ptr;
  54   const struct dbus_object_path_interface * iface_ptr;
  55   const struct dbus_method_descriptor * method_ptr;
  56   const struct dbus_method_arg_descriptor * method_arg_ptr;
  57   const struct dbus_signal_descriptor * signal_ptr;
  58   const struct dbus_signal_arg_descriptor * signal_arg_ptr;
  59   DBusMessage * msg;
  60   DBusMessageIter iter;
  61
  62   log_debug("Creating introspection message");
  63
  64   /*
  65    * Create introspection XML data.
  66    */
  67
  68   /* TODO: we assume that 16 KiB is enough to hold introspection xml.
  69    * If it gets larger, memory corruption will occur.
  70    * Use realloc-like algorithm instead */
  71   xml_data = malloc(16384);
  72   if (xml_data == NULL)
  73   {
  74     return NULL;
  75   }
  76
  77   buf_ptr = xml_data;
  78
  79   write_buf("<!DOCTYPE node PUBLIC \"-//freedesktop//DTD D-BUS Object Introspection 1.0//EN\"\n"
  80             " \"http://www.freedesktop.org/standards/dbus/1.0/introspect.dtd\">\n"
  81             "<node name=\"%s\">\n", opath_ptr->name);
  82
  83   /* Add the object path's interfaces. */
  84   for (iface_ptr = opath_ptr->ifaces; iface_ptr->iface != NULL; iface_ptr++)
  85   {
  86     write_buf("  <interface name=\"%s\">\n", iface_ptr->iface->name);
  87     if (iface_ptr->iface->methods != NULL)
  88     {
  89       /* Add the interface's methods. */
  90       for (method_ptr = iface_ptr->iface->methods; method_ptr->name != NULL; method_ptr++)
  91       {
  92         write_buf("    <method name=\"%s\">\n", method_ptr->name);
  93         /* Add the method's arguments. */
  94         for (method_arg_ptr = method_ptr->args; method_arg_ptr->name != NULL; method_arg_ptr++)
  95         {
  96           write_buf(
  97             "      <arg name=\"%s\" type=\"%s\" direction=\"%s\" />\n",
  98             method_arg_ptr->name,
  99             method_arg_ptr->type,
 100             method_arg_ptr->direction_in ? "in" : "out");
 101         }
 102         write_buf("    </method>\n");
 103       }
 104     }
 105     if (iface_ptr->iface->signals != NULL)
 106     {
 107       /* Add the interface's signals. */
 108       for (signal_ptr = iface_ptr->iface->signals; signal_ptr->name != NULL; signal_ptr++)
 109       {
 110         write_buf("    <signal name=\"%s\">\n", signal_ptr->name);
 111         /* Add the signal's arguments. */
 112         for (signal_arg_ptr = signal_ptr->args; signal_arg_ptr->name != NULL; signal_arg_ptr++)
 113         {
 114           write_buf("      <arg name=\"%s\" type=\"%s\" />\n", signal_arg_ptr->name, signal_arg_ptr->type);
 115         }
 116         write_buf("    </signal>\n");
 117       }
 118     }
 119     write_buf("  </interface>\n");
 120   }
 121   write_buf("</node>\n");
 122
 123   /*
 124    * Create a D-Bus message from the XML data.
 125    */
 126
 127   if ((msg = dbus_message_new(DBUS_MESSAGE_TYPE_METHOD_RETURN)))
 128   {
 129     dbus_message_iter_init_append(msg, &iter);
 130     if (dbus_message_iter_append_basic(&iter, DBUS_TYPE_STRING, (const void *) &xml_data))
 131     {
 132       dbus_message_set_no_reply(msg, TRUE);
 133     }
 134     else
 135     {
 136       dbus_message_unref(msg);
 137       msg = NULL;
 138       log_error("Failed to append data to introspection message");
 139     }
 140   }
 141   else
 142   {
 143     log_error("Failed to create introspection message");
 144   }
 145
 146   free(xml_data);
 147   return msg;
 148 }
 149
 150 #undef write_buf
 151
 152 void
 153 introspection_destroy(struct dbus_object_path *path)
 154 {
 155   log_debug("Destroying introspection message");
 156
 157   if (path && path->introspection) {
 158     dbus_message_unref(path->introspection);
 159     path->introspection = NULL;
 160   }
 161 #ifdef LADISH_DEBUG
 162   else
 163     log_debug("Nothing to destroy");
 164 #endif
 165 }
 166
 167 static bool introspection_handler(const struct dbus_interface_descriptor * interface, struct dbus_method_call * call_ptr)
 168 {
 169   if (strcmp(call_ptr->method_name, "Introspect") != 0)
 170   {
 171     /* The requested method wasn't "Introspect". */
 172     return false;
 173   }
 174
 175   /* Try to construct the instrospection message */
 176   call_ptr->reply = dbus_message_copy(call_ptr->iface_context); /* context contains the reply message */
 177   if (call_ptr->reply == NULL)
 178   {
 179     log_error("Ran out of memory trying to copy introspection message");
 180     goto fail;
 181   }
 182
 183   if (!dbus_message_set_destination(call_ptr->reply, dbus_message_get_sender(call_ptr->message)))
 184   {
 185     log_error("dbus_message_set_destination() failed.");
 186     goto unref_reply;
 187   }
 188
 189   if (!dbus_message_set_reply_serial(call_ptr->reply, dbus_message_get_serial(call_ptr->message)))
 190   {
 191     log_error("dbus_message_set_reply_serial() failed.");
 192     goto unref_reply;
 193   }
 194
 195   return true;
 196
 197 unref_reply:
 198   dbus_message_unref(call_ptr->reply);
 199   call_ptr->reply = NULL;
 200
 201 fail:
 202   /* Even after an error we need to return true, because the
 203      handler is only supposed to return false if a nonexistent
 204      method is requested. */
 205   return true;
 206 }
 207
 208 METHOD_ARGS_BEGIN(Introspect, "Get introspection XML")
 209   METHOD_ARG_DESCRIBE_OUT("xml_data", "s", "XML description of the object")
 210 METHOD_ARGS_END
 211
 212 METHODS_BEGIN
 213   METHOD_DESCRIBE(Introspect, NULL)
 214 METHODS_END
 215
 216 INTERFACE_BEGIN(g_dbus_interface_dtor_introspectable, "org.freedesktop.DBus.Introspectable")
 217   INTERFACE_HANDLER(introspection_handler)
 218   INTERFACE_EXPOSE_METHODS
 219 INTERFACE_END
 220
 221 dbus_object_path dbus_object_path_new(const char *name, const struct dbus_interface_descriptor * iface1_ptr, ...)
 222 {
 223   struct dbus_object_path * opath_ptr;
 224   va_list ap;
 225   const struct dbus_interface_descriptor * iface_src_ptr;
 226   struct dbus_object_path_interface * iface_dst_ptr;
 227   void * iface_context;
 228   size_t len;
 229
 230   log_debug("Creating object path");
 231
 232   opath_ptr = malloc(sizeof(struct dbus_object_path));
 233   if (opath_ptr == NULL)
 234   {
 235     log_error("malloc() failed to allocate struct dbus_object_path.");
 236     goto fail;
 237   }
 238
 239   opath_ptr->name = strdup(name);
 240   if (opath_ptr->name == NULL)
 241   {
 242     log_error("malloc() failed to allocate struct dbus_object_path.");
 243     goto free;
 244   }
 245
 246   va_start(ap, iface1_ptr);
 247   iface_src_ptr = iface1_ptr;
 248   len = 0;
 249   while (iface_src_ptr != NULL)
 250   {
 251     iface_context = va_arg(ap, void *);
 252     iface_src_ptr = va_arg(ap, const struct dbus_interface_descriptor *);
 253     len++;
 254   }
 255   va_end(ap);
 256
 257   opath_ptr->ifaces = malloc((len + 2) * sizeof(struct dbus_object_path_interface));
 258   if (opath_ptr->ifaces == NULL)
 259   {
 260     log_error("malloc failed to allocate interfaces array");
 261     goto free_name;
 262   }
 263
 264   va_start(ap, iface1_ptr);
 265   iface_src_ptr = iface1_ptr;
 266   iface_dst_ptr = opath_ptr->ifaces;
 267   while (iface_src_ptr != NULL)
 268   {
 269     iface_dst_ptr->iface = iface_src_ptr;
 270     iface_dst_ptr->iface_context = va_arg(ap, void *);
 271     iface_src_ptr = va_arg(ap, const struct dbus_interface_descriptor *);
 272     iface_dst_ptr++;
 273     len--;
 274   }
 275   va_end(ap);
 276
 277   ASSERT(len == 0);
 278
 279   iface_dst_ptr->iface = NULL;
 280   opath_ptr->introspection = introspection_new(opath_ptr);
 281   if (opath_ptr->introspection == NULL)
 282   {
 283     log_error("introspection_new() failed.");
 284     goto free_ifaces;
 285   }
 286
 287   iface_dst_ptr->iface = &g_dbus_interface_dtor_introspectable;
 288   iface_dst_ptr->iface_context = opath_ptr->introspection;
 289   iface_dst_ptr++;
 290   iface_dst_ptr->iface = NULL;
 291
 292   opath_ptr->registered = false;
 293
 294   return (dbus_object_path)opath_ptr;
 295
 296 free_ifaces:
 297   free(opath_ptr->ifaces);
 298 free_name:
 299   free(opath_ptr->name);
 300 free:
 301   free(opath_ptr);
 302 fail:
 303   return NULL;
 304 }
 305
 306 #define opath_ptr ((struct dbus_object_path *)data)
 307
 308 void dbus_object_path_unregister(DBusConnection * connection_ptr, dbus_object_path data)
 309 {
 310   ASSERT(opath_ptr->registered);
 311
 312   if (!dbus_connection_unregister_object_path(connection_ptr, opath_ptr->name))
 313   {
 314     log_error("dbus_connection_unregister_object_path() failed.");
 315   }
 316 }
 317
 318 void dbus_object_path_destroy(DBusConnection * connection_ptr, dbus_object_path data)
 319 {
 320   log_debug("Destroying object path");
 321
 322   if (opath_ptr->registered && connection_ptr != NULL && !dbus_connection_unregister_object_path(connection_ptr, opath_ptr->name))
 323   {
 324     log_error("dbus_connection_unregister_object_path() failed.");
 325   }
 326
 327   introspection_destroy(opath_ptr);
 328   free(opath_ptr->ifaces);
 329   free(opath_ptr->name);
 330   free(opath_ptr);
 331 }
 332
 333 static DBusHandlerResult dbus_object_path_handler(DBusConnection * connection, DBusMessage * message, void * data)
 334 {
 335   const char * iface_name;
 336   const struct dbus_object_path_interface * iface_ptr;
 337   struct dbus_method_call call;
 338
 339   /* Check if the message is a method call. If not, ignore it. */
 340   if (dbus_message_get_type(message) != DBUS_MESSAGE_TYPE_METHOD_CALL)
 341   {
 342     goto handled;
 343   }
 344
 345   /* Get the invoked method's name and make sure it's non-NULL. */
 346   call.method_name = dbus_message_get_member(message);
 347   if (call.method_name == NULL)
 348   {
 349     lash_dbus_error(&call, LASH_DBUS_ERROR_UNKNOWN_METHOD, "Received method call with empty method name");
 350     goto send_return;
 351   }
 352
 353   /* Initialize our data. */
 354   call.connection = connection;
 355   call.message = message;
 356   call.iface = NULL; /* To be set by the default interface handler */
 357   call.reply = NULL;
 358
 359   /* Check if there's an interface specified for this method call. */
 360   iface_name = dbus_message_get_interface(message);
 361   if (iface_name != NULL)
 362   {
 363     for (iface_ptr = opath_ptr->ifaces; iface_ptr->iface != NULL; iface_ptr++)
 364     {
 365       if (strcmp(iface_name, iface_ptr->iface->name) == 0)
 366       {
 367         call.iface_context = iface_ptr->iface_context;
 368         if (!iface_ptr->iface->handler(iface_ptr->iface, &call))
 369         {
 370           /* unknown method */
 371           break;
 372         }
 373
 374         goto send_return;
 375       }
 376     }
 377   }
 378   else
 379   {
 380     /* No interface was specified so we have to try them all. D-Bus spec states:
 381      *
 382      * Optionally, the message has an INTERFACE field giving the interface the method is a part of.
 383      * In the absence of an INTERFACE field, if two interfaces on the same object have a method with
 384      * the same name, it is undefined which of the two methods will be invoked.
 385      * Implementations may also choose to return an error in this ambiguous case.
 386      * However, if a method name is unique implementations must not require an interface field.
 387      */
 388     for (iface_ptr = opath_ptr->ifaces; iface_ptr->iface != NULL; iface_ptr++)
 389     {
 390       call.iface_context = iface_ptr->iface_context;
 391       if (!iface_ptr->iface->handler(iface_ptr->iface, &call))
 392       {
 393         /* known method */
 394         goto send_return;
 395       }
 396     }
 397   }
 398
 399   lash_dbus_error(&call, LASH_DBUS_ERROR_UNKNOWN_METHOD, "Method \"%s\" with signature \"%s\" on interface \"%s\" doesn't exist", call.method_name, dbus_message_get_signature(message), iface_name);
 400
 401 send_return:
 402   method_return_send(&call);
 403
 404 handled:
 405   return DBUS_HANDLER_RESULT_HANDLED;
 406 }
 407
 408 static void dbus_object_path_handler_unregister(DBusConnection * connection_ptr, void * data)
 409 {
 410 #ifdef LADISH_DEBUG
 411   log_debug("Message handler of object path %s was unregistered", (opath_ptr && path->name) ? opath_ptr->name : "<unknown>");
 412 #endif /* LADISH_DEBUG */
 413 }
 414
 415 bool dbus_object_path_register(DBusConnection * connection_ptr, dbus_object_path data)
 416 {
 417   log_debug("Registering object path \"%s\"", opath_ptr->name);
 418
 419   ASSERT(!opath_ptr->registered);
 420
 421   DBusObjectPathVTable vtable =
 422   {
 423     dbus_object_path_handler_unregister,
 424     dbus_object_path_handler,
 425     NULL, NULL, NULL, NULL
 426   };
 427
 428   if (!dbus_connection_register_object_path(connection_ptr, opath_ptr->name, &vtable, opath_ptr))
 429   {
 430     return false;
 431   }
 432
 433   opath_ptr->registered = true;
 434   return true;
 435 }
 436
 437 #undef opath_ptr