dbus/object_path.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 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 "../common/safety.h"
  33 #include "error.h"  /* lash_dbus_error() */
  34
  35 struct dbus_object_path_interface
  36 {
  37   const struct dbus_interface_descriptor * iface;
  38   void * iface_context;
  39 };
  40
  41 struct dbus_object_path
  42 {
  43   char * name;
  44   DBusMessage * introspection;
  45   struct dbus_object_path_interface * ifaces;
  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   xml_data = lash_malloc(1, 16384);
  69   buf_ptr = xml_data;
  70
  71   write_buf("<!DOCTYPE node PUBLIC \"-//freedesktop//DTD D-BUS Object Introspection 1.0//EN\"\n"
  72             " \"http://www.freedesktop.org/standards/dbus/1.0/introspect.dtd\">\n"
  73             "<node name=\"%s\">\n", opath_ptr->name);
  74
  75   /* Add the object path's interfaces. */
  76   for (iface_ptr = opath_ptr->ifaces; iface_ptr->iface != NULL; iface_ptr++)
  77   {
  78     write_buf("  <interface name=\"%s\">\n", iface_ptr->iface->name);
  79     if (iface_ptr->iface->methods != NULL)
  80     {
  81       /* Add the interface's methods. */
  82       for (method_ptr = iface_ptr->iface->methods; method_ptr->name != NULL; method_ptr++)
  83       {
  84         write_buf("    <method name=\"%s\">\n", method_ptr->name);
  85         /* Add the method's arguments. */
  86         for (method_arg_ptr = method_ptr->args; method_arg_ptr->name != NULL; method_arg_ptr++)
  87         {
  88           write_buf(
  89             "      <arg name=\"%s\" type=\"%s\" direction=\"%s\" />\n",
  90             method_arg_ptr->name,
  91             method_arg_ptr->type,
  92             method_arg_ptr->direction_in ? "in" : "out");
  93         }
  94         write_buf("    </method>\n");
  95       }
  96     }
  97     if (iface_ptr->iface->signals != NULL)
  98     {
  99       /* Add the interface's signals. */
 100       for (signal_ptr = iface_ptr->iface->signals; signal_ptr->name != NULL; signal_ptr++)
 101       {
 102         write_buf("    <signal name=\"%s\">\n", signal_ptr->name);
 103         /* Add the signal's arguments. */
 104         for (signal_arg_ptr = signal_ptr->args; signal_arg_ptr->name != NULL; signal_arg_ptr++)
 105         {
 106           write_buf("      <arg name=\"%s\" type=\"%s\" />\n", signal_arg_ptr->name, signal_arg_ptr->type);
 107         }
 108         write_buf("    </signal>\n");
 109       }
 110     }
 111     write_buf("  </interface>\n");
 112   }
 113   write_buf("</node>");
 114
 115   /*
 116    * Create a D-Bus message from the XML data.
 117    */
 118
 119   if ((msg = dbus_message_new(DBUS_MESSAGE_TYPE_METHOD_RETURN)))
 120   {
 121     dbus_message_iter_init_append(msg, &iter);
 122     if (dbus_message_iter_append_basic(&iter, DBUS_TYPE_STRING, (const void *) &xml_data))
 123     {
 124       dbus_message_set_no_reply(msg, TRUE);
 125     }
 126     else
 127     {
 128       dbus_message_unref(msg);
 129       msg = NULL;
 130       log_error("Failed to append data to introspection message");
 131     }
 132   }
 133   else
 134   {
 135     log_error("Failed to create introspection message");
 136   }
 137
 138   free(xml_data);
 139   return msg;
 140 }
 141
 142 #undef write_buf
 143
 144 void
 145 introspection_destroy(struct dbus_object_path *path)
 146 {
 147   log_debug("Destroying introspection message");
 148
 149   if (path && path->introspection) {
 150     dbus_message_unref(path->introspection);
 151     path->introspection = NULL;
 152   }
 153 #ifdef LADISH_DEBUG
 154   else
 155     log_debug("Nothing to destroy");
 156 #endif
 157 }
 158
 159 static bool introspection_handler(const struct dbus_interface_descriptor * interface, struct dbus_method_call * call_ptr)
 160 {
 161   if (strcmp(call_ptr->method_name, "Introspect") != 0)
 162   {
 163     /* The requested method wasn't "Introspect". */
 164     return false;
 165   }
 166
 167   /* Try to construct the instrospection message */
 168   call_ptr->reply = dbus_message_copy(call_ptr->iface_context); /* context contains the reply message */
 169   if (call_ptr->reply == NULL)
 170   {
 171     log_error("Ran out of memory trying to copy introspection message");
 172     goto fail;
 173   }
 174
 175   if (!dbus_message_set_destination(call_ptr->reply, dbus_message_get_sender(call_ptr->message)))
 176   {
 177     log_error("dbus_message_set_destination() failed.");
 178     goto unref_reply;
 179   }
 180
 181   if (!dbus_message_set_reply_serial(call_ptr->reply, dbus_message_get_serial(call_ptr->message)))
 182   {
 183     log_error("dbus_message_set_reply_serial() failed.");
 184     goto unref_reply;
 185   }
 186
 187   return true;
 188
 189 unref_reply:
 190   dbus_message_unref(call_ptr->reply);
 191   call_ptr->reply = NULL;
 192
 193 fail:
 194   /* Even after an error we need to return true, because the
 195      handler is only supposed to return false if a nonexistent
 196      method is requested. */
 197   return true;
 198 }
 199
 200 METHOD_ARGS_BEGIN(Introspect, "Get introspection XML")
 201   METHOD_ARG_DESCRIBE_OUT("xml_data", "s", "XML description of the object")
 202 METHOD_ARGS_END
 203
 204 METHODS_BEGIN
 205   METHOD_DESCRIBE(Introspect, NULL)
 206 METHODS_END
 207
 208 INTERFACE_BEGIN(g_dbus_interface_dtor_introspectable, "org.freedesktop.DBus.Introspectable")
 209   INTERFACE_HANDLER(introspection_handler)
 210   INTERFACE_EXPOSE_METHODS
 211 INTERFACE_END
 212
 213 dbus_object_path dbus_object_path_new(const char *name, const struct dbus_interface_descriptor * iface1_ptr, ...)
 214 {
 215   struct dbus_object_path * opath_ptr;
 216   va_list ap;
 217   const struct dbus_interface_descriptor * iface_src_ptr;
 218   struct dbus_object_path_interface * iface_dst_ptr;
 219   void * iface_context;
 220   size_t len;
 221
 222   log_debug("Creating object path");
 223
 224   opath_ptr = malloc(sizeof(struct dbus_object_path));
 225   if (opath_ptr == NULL)
 226   {
 227     log_error("malloc() failed to allocate struct dbus_object_path.");
 228     goto fail;
 229   }
 230
 231   opath_ptr->name = strdup(name);
 232   if (opath_ptr->name == NULL)
 233   {
 234     log_error("malloc() failed to allocate struct dbus_object_path.");
 235     goto free;
 236   }
 237
 238   va_start(ap, iface1_ptr);
 239   iface_src_ptr = iface1_ptr;
 240   len = 0;
 241   while (iface_src_ptr != NULL)
 242   {
 243     iface_context = va_arg(ap, void *);
 244     iface_src_ptr = va_arg(ap, const struct dbus_interface_descriptor *);
 245     len++;
 246   }
 247   va_end(ap);
 248
 249   opath_ptr->ifaces = malloc((len + 2) * sizeof(struct dbus_object_path_interface));
 250   if (opath_ptr->ifaces == NULL)
 251   {
 252     log_error("malloc failed to allocate interfaces array");
 253     goto free_name;
 254   }
 255
 256   va_start(ap, iface1_ptr);
 257   iface_src_ptr = iface1_ptr;
 258   iface_dst_ptr = opath_ptr->ifaces;
 259   while (iface_src_ptr != NULL)
 260   {
 261     iface_dst_ptr->iface = iface_src_ptr;
 262     iface_dst_ptr->iface_context = va_arg(ap, void *);
 263     iface_src_ptr = va_arg(ap, const struct dbus_interface_descriptor *);
 264     iface_dst_ptr++;
 265     len--;
 266   }
 267   va_end(ap);
 268
 269   ASSERT(len == 0);
 270
 271   iface_dst_ptr->iface = NULL;
 272   opath_ptr->introspection = introspection_new(opath_ptr);
 273   if (opath_ptr->introspection == NULL)
 274   {
 275     log_error("introspection_new() failed.");
 276     goto free_ifaces;
 277   }
 278
 279   iface_dst_ptr->iface = &g_dbus_interface_dtor_introspectable;
 280   iface_dst_ptr->iface_context = opath_ptr->introspection;
 281   iface_dst_ptr++;
 282   iface_dst_ptr->iface = NULL;
 283
 284   return (dbus_object_path)opath_ptr;
 285
 286 free_ifaces:
 287   free(opath_ptr->ifaces);
 288 free_name:
 289   free(opath_ptr->name);
 290 free:
 291   free(opath_ptr);
 292 fail:
 293   return NULL;
 294 }
 295
 296 #define opath_ptr ((struct dbus_object_path *)data)
 297
 298 void dbus_object_path_destroy(DBusConnection * connection_ptr, dbus_object_path data)
 299 {
 300   log_debug("Destroying object path");
 301
 302   if (connection_ptr != NULL && !dbus_connection_unregister_object_path(connection_ptr, opath_ptr->name))
 303   {
 304     log_error("dbus_connection_unregister_object_path() failed.");
 305   }
 306
 307   introspection_destroy(opath_ptr);
 308   free(opath_ptr->ifaces);
 309   free(opath_ptr->name);
 310   free(opath_ptr);
 311 }
 312
 313 static DBusHandlerResult dbus_object_path_handler(DBusConnection * connection, DBusMessage * message, void * data)
 314 {
 315   const char * iface_name;
 316   const struct dbus_object_path_interface * iface_ptr;
 317   struct dbus_method_call call;
 318
 319   /* Check if the message is a method call. If not, ignore it. */
 320   if (dbus_message_get_type(message) != DBUS_MESSAGE_TYPE_METHOD_CALL)
 321   {
 322     goto handled;
 323   }
 324
 325   /* Get the invoked method's name and make sure it's non-NULL. */
 326   call.method_name = dbus_message_get_member(message);
 327   if (call.method_name == NULL)
 328   {
 329     lash_dbus_error(&call, LASH_DBUS_ERROR_UNKNOWN_METHOD, "Received method call with empty method name");
 330     goto send_return;
 331   }
 332
 333   /* Initialize our data. */
 334   call.connection = connection;
 335   call.message = message;
 336   call.iface = NULL; /* To be set by the default interface handler */
 337   call.reply = NULL;
 338
 339   /* Check if there's an interface specified for this method call. */
 340   iface_name = dbus_message_get_interface(message);
 341   if (iface_name != NULL)
 342   {
 343     for (iface_ptr = opath_ptr->ifaces; iface_ptr->iface != NULL; iface_ptr++)
 344     {
 345       if (strcmp(iface_name, iface_ptr->iface->name) == 0)
 346       {
 347         call.iface_context = iface_ptr->iface_context;
 348         if (!iface_ptr->iface->handler(iface_ptr->iface, &call))
 349         {
 350           /* unknown method */
 351           break;
 352         }
 353
 354         goto send_return;
 355       }
 356     }
 357   }
 358   else
 359   {
 360     /* No interface was specified so we have to try them all. D-Bus spec states:
 361      *
 362      * Optionally, the message has an INTERFACE field giving the interface the method is a part of.
 363      * In the absence of an INTERFACE field, if two interfaces on the same object have a method with
 364      * the same name, it is undefined which of the two methods will be invoked.
 365      * Implementations may also choose to return an error in this ambiguous case.
 366      * However, if a method name is unique implementations must not require an interface field.
 367      */
 368     for (iface_ptr = opath_ptr->ifaces; iface_ptr->iface != NULL; iface_ptr++)
 369     {
 370       call.iface_context = iface_ptr->iface_context;
 371       if (!iface_ptr->iface->handler(iface_ptr->iface, &call))
 372       {
 373         /* known method */
 374         goto send_return;
 375       }
 376     }
 377   }
 378
 379   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);
 380
 381 send_return:
 382   method_return_send(&call);
 383
 384 handled:
 385   return DBUS_HANDLER_RESULT_HANDLED;
 386 }
 387
 388 static void dbus_object_path_handler_unregister(DBusConnection * connection_ptr, void * data)
 389 {
 390 #ifdef LADISH_DEBUG
 391   log_debug("Message handler of object path %s was unregistered", (opath_ptr && path->name) ? opath_ptr->name : "<unknown>");
 392 #endif /* LADISH_DEBUG */
 393 }
 394
 395 bool dbus_object_path_register(DBusConnection * connection_ptr, dbus_object_path data)
 396 {
 397   log_debug("Registering object path");
 398
 399   DBusObjectPathVTable vtable =
 400   {
 401     dbus_object_path_handler_unregister,
 402     dbus_object_path_handler,
 403     NULL, NULL, NULL, NULL
 404   };
 405
 406   dbus_connection_register_object_path(connection_ptr, opath_ptr->name, &vtable, opath_ptr);
 407
 408   return true;
 409 }
 410
 411 #undef opath_ptr