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