dns: default to always loading nm-dns-systemd-resolvelr/always-systemd-resolve

If the primary plugin is different, create an instance of the
systemd-resolve plugin alongside it to keep systemd-resolve up to date.

If for whatever reasons don't want NetworkManager to push the DNS data
it discovers to systemd-resolved, the functionality can be disabled
with:

  [main]
  dns-=systemd-resolve

5 files changed, 77 insertions, 16 deletions

diff --git a/src/dns/nm-dns-manager.c b/src/dns/nm-dns-manager.c
index a29fd81f4e..febf82ab45 100644
--- a/src/dns/nm-dns-manager.c
+++ b/src/dns/nm-dns-manager.c
@@ -122,6 +122,7 @@ typedef struct {
 
 	NMDnsManagerResolvConfManager rc_manager;
 	char *mode;
+	NMDnsPlugin *sd_resolve_plugin;
 	NMDnsPlugin *plugin;
 
 	NMConfig *config;
@@ -1390,6 +1391,16 @@ update_dns (NMDnsManager *self,
 	                           &searches, &options, &nameservers,
 	                           &nis_servers, &nis_domain);
 
+	if (priv->plugin || priv->sd_resolve_plugin)
+		rebuild_domain_lists (self);
+
+	if (priv->sd_resolve_plugin) {
+		nm_dns_plugin_update (priv->sd_resolve_plugin,
+		                      global_config,
+		                      _ip_config_lst_head (self),
+		                      priv->hostname);
+	}
+
 	/* Let any plugins do their thing first */
 	if (priv->plugin) {
 		NMDnsPlugin *plugin = priv->plugin;
@@ -1405,7 +1416,6 @@ update_dns (NMDnsManager *self,
 		}
 
 		_LOGD ("update-dns: updating plugin %s", plugin_name);
-		rebuild_domain_lists (self);
 		if (!nm_dns_plugin_update (plugin,
 		                           global_config,
 		                           _ip_config_lst_head (self),
@@ -1417,15 +1427,17 @@ update_dns (NMDnsManager *self,
 			 */
 			caching = FALSE;
 		}
-		/* Clear the generated search list as it points to
-		 * strings owned by IP configurations and we can't
-		 * guarantee they stay alive. */
-		clear_domain_lists (self);
 
 	skip:
 		;
 	}
 
+	/* Clear the generated search list as it points to
+	 * strings owned by IP configurations and we can't
+	 * guarantee they stay alive. */
+	clear_domain_lists (self);
+	clear_domain_lists (self);
+
 	/* If caching was successful, we only send 127.0.0.1 to /etc/resolv.conf
 	 * to ensure that the glibc resolver doesn't try to round-robin nameservers,
 	 * but only uses the local caching nameserver.
@@ -1921,10 +1933,15 @@ init_resolv_conf_mode (NMDnsManager *self, gboolean force_reload_plugin)
 {
 	NMDnsManagerPrivate *priv = NM_DNS_MANAGER_GET_PRIVATE (self);
 	NMDnsManagerResolvConfManager rc_manager;
-	const char *mode;
+	gs_strfreev char **dns_mode;
+	const char *mode = NULL;
+	gboolean want_sd_resolve = FALSE;
 	gboolean param_changed = FALSE, plugin_changed = FALSE;
 
-	mode = nm_config_data_get_dns_mode (nm_config_get_data (priv->config));
+	dns_mode = nm_config_data_get_dns_mode (nm_config_get_data (priv->config));
+	mode = dns_mode[0];
+	if (mode)
+		want_sd_resolve = nm_streq0 (dns_mode[1], "systemd-resolved");
 
 	if (nm_streq0 (mode, "none"))
 		rc_manager = NM_DNS_MANAGER_RESOLV_CONF_MAN_UNMANAGED;
@@ -1970,6 +1987,7 @@ again:
 			plugin_changed = TRUE;
 		}
 		mode = "systemd-resolved";
+		want_sd_resolve = FALSE;
 	} else if (nm_streq0 (mode, "dnsmasq")) {
 		if (force_reload_plugin || !NM_IS_DNS_DNSMASQ (priv->plugin)) {
 			_clear_plugin (self);
@@ -1992,6 +2010,20 @@ again:
 			plugin_changed = TRUE;
 	}
 
+	/* The systemd-resolved plugin is special. We typically always want to keep
+	 * systemd-resolved up to date even if the configured plugin is different. */
+	if (want_sd_resolve) {
+		if (!priv->sd_resolve_plugin) {
+			priv->sd_resolve_plugin = nm_dns_systemd_resolved_new ();
+			plugin_changed = TRUE;
+		}
+	} else {
+		if (priv->sd_resolve_plugin) {
+			g_clear_object (&priv->sd_resolve_plugin);
+			plugin_changed = TRUE;
+		}
+	}
+
 	if (plugin_changed && priv->plugin) {
 		g_signal_connect (priv->plugin, NM_DNS_PLUGIN_FAILED, G_CALLBACK (plugin_failed), self);
 		g_signal_connect (priv->plugin, NM_DNS_PLUGIN_CHILD_QUIT, G_CALLBACK (plugin_child_quit), self);
@@ -2013,8 +2045,9 @@ again:
 	}
 
 	if (param_changed || plugin_changed) {
-		_LOGI ("init: dns=%s, rc-manager=%s%s%s%s",
-		       mode, _rc_manager_to_string (rc_manager),
+		_LOGI ("init: dns=%s%s rc-manager=%s%s%s%s",
+		       mode, (want_sd_resolve ? ",systemd-resolved" : ""),
+		       _rc_manager_to_string (rc_manager),
 		       NM_PRINT_FMT_QUOTED (priv->plugin, ", plugin=",
 		                            nm_dns_plugin_get_name (priv->plugin), "", ""));
 	}
@@ -2275,6 +2308,7 @@ dispose (GObject *object)
 	if (priv->config)
 		g_signal_handlers_disconnect_by_func (priv->config, config_changed_cb, self);
 
+	g_clear_object (&priv->sd_resolve_plugin);
 	_clear_plugin (self);
 
 	priv->best_ip_config_4 = NULL;
diff --git a/src/nm-config-data.c b/src/nm-config-data.c
index 813ef9c8a6..c09ba595ec 100644
--- a/src/nm-config-data.c
+++ b/src/nm-config-data.c
@@ -106,7 +106,6 @@ typedef struct {
 	GSList *ignore_carrier;
 	GSList *assume_ipv6ll_only;
 
-	char *dns_mode;
 	char *rc_manager;
 
 	NMGlobalDnsConfig *global_dns;
@@ -306,12 +305,25 @@ nm_config_data_get_no_auto_default_for_device (const NMConfigData *self, NMDevic
 	       || nm_device_spec_match_list (device, priv->no_auto_default.specs_config);
 }
 
-const char *
+char **
 nm_config_data_get_dns_mode (const NMConfigData *self)
 {
+	const NMConfigDataPrivate *priv;
+	char **list;
+
 	g_return_val_if_fail (self, NULL);
 
-	return NM_CONFIG_DATA_GET_PRIVATE (self)->dns_mode;
+	priv = NM_CONFIG_DATA_GET_PRIVATE (self);
+
+	list = g_key_file_get_string_list (priv->keyfile, NM_CONFIG_KEYFILE_GROUP_MAIN, "dns", NULL, NULL);
+	if (!list) {
+		gs_unref_keyfile GKeyFile *kf = nm_config_create_keyfile ();
+
+		/* let keyfile split the default string according to its own escaping rules. */
+		g_key_file_set_value (kf, NM_CONFIG_KEYFILE_GROUP_MAIN, "dns", NM_CONFIG_DEFAULT_MAIN_DNS);
+		list = g_key_file_get_string_list (kf, NM_CONFIG_KEYFILE_GROUP_MAIN, "dns", NULL, NULL);
+	}
+	return _nm_utils_strv_cleanup (list, TRUE, TRUE, TRUE);
 }
 
 const char *
@@ -597,6 +609,7 @@ static const struct {
 	const char *value;
 } default_values[] = {
 	{ NM_CONFIG_KEYFILE_GROUP_MAIN,    "plugins",                              NM_CONFIG_DEFAULT_MAIN_PLUGINS },
+	{ NM_CONFIG_KEYFILE_GROUP_MAIN,    "dns",                                  NM_CONFIG_DEFAULT_MAIN_DNS },
 	{ NM_CONFIG_KEYFILE_GROUP_MAIN,    "rc-manager",                           NM_CONFIG_DEFAULT_MAIN_RC_MANAGER },
 	{ NM_CONFIG_KEYFILE_GROUP_MAIN,    NM_CONFIG_KEYFILE_KEY_MAIN_AUTH_POLKIT, NM_CONFIG_DEFAULT_MAIN_AUTH_POLKIT },
 	{ NM_CONFIG_KEYFILE_GROUP_MAIN,    NM_CONFIG_KEYFILE_KEY_MAIN_DHCP,        NM_CONFIG_DEFAULT_MAIN_DHCP },
@@ -1461,6 +1474,15 @@ _slist_str_equals (GSList *a, GSList *b)
 	return !a && !b;
 }
 
+static gboolean
+_dns_mode_equals (NMConfigData *old_data, NMConfigData *new_data)
+{
+	gs_strfreev char **old_dns_mode = nm_config_data_get_dns_mode (old_data);
+	gs_strfreev char **new_dns_mode = nm_config_data_get_dns_mode (new_data);
+
+	return _nm_utils_strv_equal (old_dns_mode, new_dns_mode);
+}
+
 NMConfigChangeFlags
 nm_config_data_diff (NMConfigData *old_data, NMConfigData *new_data)
 {
@@ -1493,7 +1515,7 @@ nm_config_data_diff (NMConfigData *old_data, NMConfigData *new_data)
 	    || !_slist_str_equals (priv_old->no_auto_default.specs_config, priv_new->no_auto_default.specs_config))
 		changes |= NM_CONFIG_CHANGE_NO_AUTO_DEFAULT;
 
-	if (g_strcmp0 (nm_config_data_get_dns_mode (old_data), nm_config_data_get_dns_mode (new_data)))
+	if (!_dns_mode_equals (old_data, new_data))
 		changes |= NM_CONFIG_CHANGE_DNS_MODE;
 
 	if (g_strcmp0 (nm_config_data_get_rc_manager (old_data), nm_config_data_get_rc_manager (new_data)))
@@ -1638,7 +1660,6 @@ constructed (GObject *object)
 	priv->connectivity.interval = _nm_utils_ascii_str_to_int64 (str, 10, 0, G_MAXUINT, NM_CONFIG_DEFAULT_CONNECTIVITY_INTERVAL);
 	g_free (str);
 
-	priv->dns_mode = nm_strstrip (g_key_file_get_string (priv->keyfile, NM_CONFIG_KEYFILE_GROUP_MAIN, "dns", NULL));
 	priv->rc_manager = nm_strstrip (g_key_file_get_string (priv->keyfile, NM_CONFIG_KEYFILE_GROUP_MAIN, "rc-manager", NULL));
 
 	priv->ignore_carrier = nm_config_get_match_spec (priv->keyfile, NM_CONFIG_KEYFILE_GROUP_MAIN, "ignore-carrier", NULL);
@@ -1713,7 +1734,6 @@ finalize (GObject *gobject)
 	g_slist_free_full (priv->no_auto_default.specs_config, g_free);
 	g_strfreev (priv->no_auto_default.arr);
 
-	g_free (priv->dns_mode);
 	g_free (priv->rc_manager);
 
 	g_slist_free_full (priv->ignore_carrier, g_free);
diff --git a/src/nm-config-data.h b/src/nm-config-data.h
index 650fbe1480..3917670383 100644
--- a/src/nm-config-data.h
+++ b/src/nm-config-data.h
@@ -168,7 +168,7 @@ int nm_config_data_get_autoconnect_retries_default (const NMConfigData *config_d
 const char *const*nm_config_data_get_no_auto_default (const NMConfigData *config_data);
 gboolean          nm_config_data_get_no_auto_default_for_device (const NMConfigData *self, NMDevice *device);
 
-const char *nm_config_data_get_dns_mode (const NMConfigData *self);
+char **nm_config_data_get_dns_mode (const NMConfigData *self);
 const char *nm_config_data_get_rc_manager (const NMConfigData *self);
 
 gboolean nm_config_data_get_ignore_carrier (const NMConfigData *self, NMDevice *device);
diff --git a/src/nm-config.c b/src/nm-config.c
index d4682ed6da..0e8076eff7 100644
--- a/src/nm-config.c
+++ b/src/nm-config.c
@@ -670,6 +670,7 @@ static gboolean
 _setting_is_string_list (const char *group, const char *key)
 {
 	return    _IS (NM_CONFIG_KEYFILE_GROUP_MAIN, "plugins")
+	       || _IS (NM_CONFIG_KEYFILE_GROUP_MAIN, "dns")
 	       || _IS (NM_CONFIG_KEYFILE_GROUP_MAIN, NM_CONFIG_KEYFILE_KEY_MAIN_DEBUG)
 	       || _IS (NM_CONFIG_KEYFILE_GROUP_LOGGING, "domains")
 	       || g_str_has_prefix (group, NM_CONFIG_KEYFILE_GROUPPREFIX_TEST_APPEND_STRINGLIST);
@@ -788,6 +789,10 @@ read_config (GKeyFile *keyfile, gboolean is_base_config, const char *dirname, co
 								g_key_file_set_value (keyfile, group, base_key, NM_CONFIG_DEFAULT_MAIN_PLUGINS);
 								old_val = g_key_file_get_string_list (keyfile, group, base_key, NULL, NULL);
 							}
+							if (nm_streq (group, NM_CONFIG_KEYFILE_GROUP_MAIN) && nm_streq (base_key, "dns")) {
+								g_key_file_set_value (keyfile, group, base_key, NM_CONFIG_DEFAULT_MAIN_DNS);
+								old_val = g_key_file_get_string_list (keyfile, group, base_key, NULL, NULL);
+							}
 						}
 					} else {
 						gs_free char *old_sval = nm_config_keyfile_get_value (keyfile, group, base_key, NM_CONFIG_GET_VALUE_TYPE_SPEC);
diff --git a/src/nm-config.h b/src/nm-config.h
index 5d027ce06e..45939cd150 100644
--- a/src/nm-config.h
+++ b/src/nm-config.h
@@ -38,6 +38,8 @@
 /* Signals */
 #define NM_CONFIG_SIGNAL_CONFIG_CHANGED             "config-changed"
 
+#define NM_CONFIG_DEFAULT_MAIN_DNS "default,systemd-resolved"
+
 #define NM_CONFIG_DEFAULT_CONNECTIVITY_INTERVAL 300
 #define NM_CONFIG_DEFAULT_CONNECTIVITY_RESPONSE "NetworkManager is online" /* NOT LOCALIZED */