dns: always reload the dns configuration mode on SIGHUP

diff --git a/src/dns-manager/nm-dns-manager.c b/src/dns-manager/nm-dns-manager.c
index bd011ea..ec83e60 100644 (file)
--- a/src/dns-manager/nm-dns-manager.c
+++ b/src/dns-manager/nm-dns-manager.c
@@ -125,6 +125,9 @@ typedef struct {
 
        NMDnsManagerResolvConfMode resolv_conf_mode;
        NMDnsManagerResolvConfManager rc_manager;
+       char *last_mode;
+       bool last_immutable:1;
+       bool mode_initialized:1;
        NMDnsPlugin *plugin;
 
        NMConfig *config;
@@ -1363,6 +1366,26 @@ nm_dns_manager_end_updates (NMDnsManager *self, const char *func)
 
 /******************************************************************/
 
+static bool
+_get_resconf_immutable (int *immutable_cached)
+{
+       int fd, flags;
+       int immutable;
+
+       immutable = *immutable_cached;
+       if (!NM_IN_SET (immutable, FALSE, TRUE)) {
+               immutable = FALSE;
+               fd = open (_PATH_RESCONF, O_RDONLY);
+               if (fd != -1) {
+                       if (ioctl (fd, FS_IOC_GETFLAGS, &flags) != -1)
+                               immutable = NM_FLAGS_HAS (flags, FS_IMMUTABLE_FL);
+                       close (fd);
+               }
+               *immutable_cached = immutable;
+       }
+       return immutable;
+}
+
 NM_DEFINE_SINGLETON_GETTER (NMDnsManager, nm_dns_manager_get, NM_TYPE_DNS_MANAGER);
 
 static void
@@ -1370,25 +1393,34 @@ init_resolv_conf_mode (NMDnsManager *self)
 {
        NMDnsManagerPrivate *priv = NM_DNS_MANAGER_GET_PRIVATE (self);
        const char *mode, *mode_unknown;
-       int fd, flags;
-       gboolean immutable = FALSE;
+       int immutable = -1;
+
+       mode = nm_config_data_get_dns_mode (nm_config_get_data (priv->config));
 
+       if (   priv->mode_initialized
+           && nm_streq0 (mode, priv->last_mode)
+           && (   nm_streq0 (mode, "none")
+               || priv->last_immutable == _get_resconf_immutable (&immutable))) {
+               /* we call init_resolv_conf_mode() on every SIGHUP to possibly reload
+                * when either "mode" or "immutable" changed. However, we don't want to
+                * re-create the plugin, when the paramters didn't actually change. So
+                * detect that we would recreate the same plugin and return early. */
+               return;
+       }
+
+       priv->mode_initialized = TRUE;
+       g_free (priv->last_mode);
+       priv->last_mode = g_strdup (mode);
+       priv->last_immutable = FALSE;
        g_clear_object (&priv->plugin);
        priv->resolv_conf_mode = NM_DNS_MANAGER_RESOLV_CONF_UNMANAGED;
 
-       mode = nm_config_data_get_dns_mode (nm_config_get_data (priv->config));
-       if (!g_strcmp0 (mode, "none")) {
+       if (nm_streq0 (mode, "none")) {
                _LOGI ("%s%s", "set resolv-conf-mode: ", "none");
                return;
        }
 
-       fd = open (_PATH_RESCONF, O_RDONLY);
-       if (fd != -1) {
-               if (ioctl (fd, FS_IOC_GETFLAGS, &flags) == -1)
-                       flags = 0;
-               close (fd);
-               immutable = NM_FLAGS_HAS (flags, FS_IMMUTABLE_FL);
-       }
+       priv->last_immutable = _get_resconf_immutable (&immutable);
 
        if (NM_IN_STRSET (mode, "dnsmasq", "unbound")) {
                if (!immutable)
@@ -1461,8 +1493,15 @@ config_changed_cb (NMConfig *config,
 {
        GError *error = NULL;
 
-       if (NM_FLAGS_HAS (changes, NM_CONFIG_CHANGE_DNS_MODE))
+       if (NM_FLAGS_ANY (changes, NM_CONFIG_CHANGE_DNS_MODE |
+                                  NM_CONFIG_CHANGE_SIGHUP)) {
+               /* reload the resolv-conf mode also on SIGHUP (when DNS_MODE didn't change).
+                * The reason is, that the configuration also depends on whether resolv.conf
+                * is immutable, thus, without the configuration changing, we always want to
+                * re-configure the mode. */
                init_resolv_conf_mode (self);
+       }
+
        if (NM_FLAGS_HAS (changes, NM_CONFIG_CHANGE_RC_MANAGER))
                init_resolv_conf_manager (self);
 
@@ -1513,6 +1552,8 @@ dispose (GObject *object)
                g_clear_object (&priv->plugin);
        }
 
+       g_clear_pointer (&priv->last_mode, g_free);
+
        /* If we're quitting, leave a valid resolv.conf in place, not one
         * pointing to 127.0.0.1 if any plugins were active.  Thus update
         * DNS after disposing of all plugins.  But if we haven't done any