daemon: Add utilities to create private DBus servers

GDM creates private off-the-bus dbus servers for facilitating
communication between its various processes.

This commit adds a new function:

gdm_dbus_setup_private_server

that performs the work necessary to create a private server,
including code for generating the socket address, and code for
handling new connections.

The ultimate goal is to drop our dependency on dbus-glib, and
instead use GDBus. gdm_dbus_setup_private_server uses GDBus, so
this is one step toward that goal.

https://bugzilla.gnome.org/show_bug.cgi?id=622888

1 files changed, 125 insertions, 0 deletions

diff --git a/daemon/gdm-dbus-util.c b/daemon/gdm-dbus-util.c
new file mode 100644
index 00000000..f77bc92d
--- /dev/null
+++ b/daemon/gdm-dbus-util.c
@@ -0,0 +1,125 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 8 -*-
+ *
+ * Copyright (C) 2012 Giovanni Campagna <scampa.giovanni@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ */
+
+#include "gdm-dbus-util.h"
+#include <gio/gunixsocketaddress.h>
+
+/* a subset of org.freedesktop.DBus interface, to be used by internal servers */
+static const char *dbus_introspection =
+"<node name=\"/org/freedesktop/DBus\">"
+"  <interface name=\"org.freedesktop.DBus\">"
+"    <method name=\"AddMatch\">"
+"      <arg name=\"match_rule\" type=\"s\" direction=\"in\" />"
+"    </method>"
+"  </interface>"
+"</node>";
+
+static void
+handle_bus_method (GDBusConnection       *connection,
+                   const char            *sender,
+                   const char            *object_path,
+                   const char            *interface_name,
+                   const char            *method_name,
+                   GVariant              *parameters,
+                   GDBusMethodInvocation *invocation,
+                   gpointer               user_data)
+{
+        g_dbus_method_invocation_return_value (invocation, NULL);
+}
+
+static gboolean
+handle_connection (GDBusServer      *server,
+                   GDBusConnection  *new_connection,
+                   gpointer          user_data)
+{
+        GDBusInterfaceVTable bus_vtable = { handle_bus_method };
+        GDBusNodeInfo *bus_info;
+
+        bus_info = g_dbus_node_info_new_for_xml (dbus_introspection,
+                                                 NULL);
+
+        g_debug ("GdmDBusServer: new connection %p", new_connection);
+
+        g_dbus_connection_register_object (new_connection,
+                                           "/org/freedesktop/DBus",
+                                           bus_info->interfaces[0],
+                                           &bus_vtable,
+                                           NULL, NULL, NULL);
+        g_dbus_node_info_unref (bus_info);
+
+        /* We're not handling the signal */
+        return FALSE;
+}
+
+/* Note: Use abstract sockets like dbus does by default on Linux. Abstract
+ * sockets are only available on Linux.
+ */
+static char *
+generate_address (void)
+{
+        char *path;
+
+        if (g_unix_socket_address_abstract_names_supported ()) {
+                int   i;
+                char  tmp[9];
+
+                for (i = 0; i < 8; i++) {
+                        if (g_random_int_range (0, 2) == 0) {
+                                tmp[i] = g_random_int_range ('a', 'z' + 1);
+                        } else {
+                                tmp[i] = g_random_int_range ('A', 'Z' + 1);
+                        }
+                }
+                tmp[8] = '\0';
+
+                path = g_strdup_printf ("unix:abstract=/tmp/gdm-greeter-%s", tmp);
+        } else {
+                path = g_strdup ("unix:tmpdir=/tmp");
+        }
+
+        return path;
+}
+
+GDBusServer *
+gdm_dbus_setup_private_server (GDBusAuthObserver  *observer,
+                               GError            **error)
+{
+        char *address, *guid;
+        GDBusServer *server;
+
+        address = generate_address ();
+        guid = g_dbus_generate_guid ();
+
+        server = g_dbus_server_new_sync (address,
+                                         G_DBUS_SERVER_FLAGS_NONE,
+                                         guid,
+                                         observer,
+                                         NULL,
+                                         error);
+
+        g_signal_connect (server, "new-connection",
+                          G_CALLBACK (handle_connection),
+                          NULL);
+
+        g_free (address);
+        g_free (guid);
+
+        return server;
+}