NetworkManager/examples/C/glib/monitor-nm-state-gdbus.c

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * Copyright (C) 2012 Red Hat, Inc.
 */

/*
 * This example monitors NM state via D-Bus "StateChanged" signal on
 * "org.freedesktop.NetworkManager" object.
 * It uses GDBus and the libnm headers.

 * You don't need to have the NetworkManager devel packages installed. You can just
 * grab nm-dbus-interface.h and put it in the path.
 *
 * Standalone compilation:
 *   gcc -Wall monitor-nm-state-gdbus.c -o monitor-nm-state-gdbus `pkg-config --cflags --libs libnm`
 */

#include <gio/gio.h>
#include <string.h>
#include <nm-dbus-interface.h>

static const char *
nm_state_to_string(NMState state)
{
    switch (state) {
    case NM_STATE_ASLEEP:
        return "asleep";
    case NM_STATE_CONNECTING:
        return "connecting";
    case NM_STATE_CONNECTED_LOCAL:
        return "connected (local only)";
    case NM_STATE_CONNECTED_SITE:
        return "connected (site only)";
    case NM_STATE_CONNECTED_GLOBAL:
        return "connected";
    case NM_STATE_DISCONNECTING:
        return "disconnecting";
    case NM_STATE_DISCONNECTED:
        return "disconnected";
    case NM_STATE_UNKNOWN:
    default:
        return "unknown";
    }
}

static void
on_signal(GDBusProxy *proxy,
          char       *sender_name,
          char       *signal_name,
          GVariant   *parameters,
          gpointer    user_data)
{
    guint32 new_state;

    /* Print all signals */
    //char *parameters_str;
    //parameters_str = g_variant_print (parameters, TRUE);
    //g_print (" *** Received Signal: %s: %s\n", signal_name, parameters_str);
    //g_free (parameters_str);

    /* We are only interested in "StateChanged" signal */
    if (strcmp(signal_name, "StateChanged") == 0) {
        GVariant *tmp = g_variant_get_child_value(parameters, 0);
        new_state     = g_variant_get_uint32(tmp);
        g_variant_unref(tmp);
        g_print("NetworkManager state is: (%d) %s\n",
                new_state,
                nm_state_to_string((NMState) new_state));
    }
}

int
main(int argc, char *argv[])
{
    GMainLoop      *loop;
    GError         *error = NULL;
    GDBusProxyFlags flags;
    GDBusProxy     *proxy;

    /* Monitor 'StateChanged' signal on 'org.freedesktop.NetworkManager' interface */
    g_print("Monitor NetworkManager's state\n");
    g_print("==============================\n");

    flags = G_DBUS_PROXY_FLAGS_DO_NOT_LOAD_PROPERTIES | G_DBUS_PROXY_FLAGS_DO_NOT_AUTO_START;
    proxy = g_dbus_proxy_new_for_bus_sync(G_BUS_TYPE_SYSTEM,
                                          flags,
                                          NULL, /* GDBusInterfaceInfo */
                                          "org.freedesktop.NetworkManager",
                                          "/org/freedesktop/NetworkManager",
                                          "org.freedesktop.NetworkManager",
                                          NULL, /* GCancellable */
                                          &error);

    if (proxy == NULL) {
        g_dbus_error_strip_remote_error(error);
        g_printerr("Error creating D-Bus proxy: %s\n", error->message);
        g_error_free(error);
        return -1;
    }

    /* Connect to g-signal to receive signals from proxy (remote object) */
    g_signal_connect(proxy, "g-signal", G_CALLBACK(on_signal), NULL);

    /* Run main loop */
    loop = g_main_loop_new(NULL, FALSE);
    g_main_loop_run(loop);

    g_object_unref(proxy);

    return 0;
}