core: implement setting MDNS setting for systemd

The connection.mdns setting is a per-connection setting,
so one might expect that one activated device can only have
one MDNS setting at a time.

However, with certain VPN plugins (those that don't have their
own IP interface, like libreswan), the VPN configuration is merged
into the configuration of the device. So, in this case, there
might be multiple settings for one device that must be merged.

We already have a mechanism for that. It's NMIP4Config. Let NMIP4Config
track this piece of information. Although, stricitly speaking this
is not tied to IPv4, the alternative would be to introduce a new
object to track such data, which would be a tremendous effort
and more complicated then this.

Luckily, NMDnsManager and NMDnsPlugin are already equipped to
handle multiple NMIPConfig instances per device (IPv4 vs. IPv6,
and Device vs. VPN).

Also make "connection.mdns" configurable via global defaults in
NetworkManager.conf.

8 files changed, 108 insertions, 4 deletions

diff --git a/man/NetworkManager.conf.xml b/man/NetworkManager.conf.xml
index 04f6b54b23..4171bfd09a 100644
--- a/man/NetworkManager.conf.xml
+++ b/man/NetworkManager.conf.xml
@@ -655,6 +655,9 @@ ipv6.ip6-privacy=0
           <term><varname>connection.lldp</varname></term>
         </varlistentry>
         <varlistentry>
+          <term><varname>connection.mdns</varname></term>
+        </varlistentry>
+        <varlistentry>
           <term><varname>connection.stable-id</varname></term>
         </varlistentry>
         <varlistentry>
diff --git a/src/devices/nm-device.c b/src/devices/nm-device.c
index ce144c3b08..c4569ef613 100644
--- a/src/devices/nm-device.c
+++ b/src/devices/nm-device.c
@@ -1878,6 +1878,34 @@ out:
 	return nm_utils_ip_route_metric_normalize (addr_family, route_metric);
 }
 
+static NMSettingConnectionMdns
+_get_mdns (NMDevice *self)
+{
+	NMConnection *connection;
+	NMSettingConnectionMdns mdns = NM_SETTING_CONNECTION_MDNS_DEFAULT;
+
+	g_return_val_if_fail (NM_IS_DEVICE (self), NM_SETTING_CONNECTION_MDNS_DEFAULT);
+
+	connection = nm_device_get_applied_connection (self);
+	if (connection)
+		mdns = nm_setting_connection_get_mdns (nm_connection_get_setting_connection (connection));
+
+	if (mdns == NM_SETTING_CONNECTION_MDNS_DEFAULT) {
+		gs_free char *value = NULL;
+
+		value = nm_config_data_get_connection_default (NM_CONFIG_GET_DATA,
+		                                               "connection.mdns",
+		                                               self);
+		mdns = _nm_utils_ascii_str_to_int64 (value,
+		                                     10,
+		                                     NM_SETTING_CONNECTION_MDNS_NO,
+		                                     NM_SETTING_CONNECTION_MDNS_YES,
+		                                     NM_SETTING_CONNECTION_MDNS_DEFAULT);
+	}
+
+	return mdns;
+}
+
 guint32
 nm_device_get_route_table (NMDevice *self,
                            int addr_family,
@@ -5922,6 +5950,7 @@ ensure_con_ip4_config (NMDevice *self)
 	priv->con_ip4_config = _ip4_config_new (self);
 	nm_ip4_config_merge_setting (priv->con_ip4_config,
 	                             nm_connection_get_setting_ip4_config (connection),
+	                             _get_mdns (self),
 	                             nm_device_get_route_table (self, AF_INET, TRUE),
 	                             nm_device_get_route_metric (self, AF_INET));
 
@@ -6217,6 +6246,7 @@ dhcp4_state_changed (NMDhcpClient *client,
 			manual = _ip4_config_new (self);
 			nm_ip4_config_merge_setting (manual,
 			                             nm_connection_get_setting_ip4_config (connection),
+			                             NM_SETTING_CONNECTION_MDNS_DEFAULT,
 			                             nm_device_get_route_table (self, AF_INET, TRUE),
 			                             nm_device_get_route_metric (self, AF_INET));
 
@@ -6596,6 +6626,7 @@ act_stage3_ip4_config_start (NMDevice *self,
 		config = _ip4_config_new (self);
 		nm_ip4_config_merge_setting (config,
 		                             nm_connection_get_setting_ip4_config (connection),
+		                             NM_SETTING_CONNECTION_MDNS_DEFAULT,
 		                             nm_device_get_route_table (self, AF_INET, TRUE),
 		                             nm_device_get_route_metric (self, AF_INET));
 
@@ -9313,6 +9344,7 @@ nm_device_reactivate_ip4_config (NMDevice *self,
 		priv->con_ip4_config = _ip4_config_new (self);
 		nm_ip4_config_merge_setting (priv->con_ip4_config,
 		                             s_ip4_new,
+		                             _get_mdns (self),
 		                             nm_device_get_route_table (self, AF_INET, TRUE),
 		                             nm_device_get_route_metric (self, AF_INET));
 
diff --git a/src/devices/nm-device.h b/src/devices/nm-device.h
index 8c823bab4d..3f3da48578 100644
--- a/src/devices/nm-device.h
+++ b/src/devices/nm-device.h
@@ -24,6 +24,7 @@
 
 #include <netinet/in.h>
 
+#include "nm-setting-connection.h"
 #include "nm-exported-object.h"
 #include "nm-dbus-interface.h"
 #include "nm-connection.h"
diff --git a/src/dns/nm-dns-systemd-resolved.c b/src/dns/nm-dns-systemd-resolved.c
index da049726dc..7625bcaede 100644
--- a/src/dns/nm-dns-systemd-resolved.c
+++ b/src/dns/nm-dns-systemd-resolved.c
@@ -228,6 +228,8 @@ prepare_one_interface (NMDnsSystemdResolved *self, InterfaceConfig *ic)
 	NMDnsSystemdResolvedPrivate *priv = NM_DNS_SYSTEMD_RESOLVED_GET_PRIVATE (self);
 	GVariantBuilder dns, domains;
 	NMCListElem *elem;
+	NMSettingConnectionMdns mdns = NM_SETTING_CONNECTION_MDNS_DEFAULT;
+	const char *mdns_arg = NULL;
 
 	g_variant_builder_init (&dns, G_VARIANT_TYPE ("(ia(iay))"));
 	g_variant_builder_add (&dns, "i", ic->ifindex);
@@ -237,18 +239,43 @@ prepare_one_interface (NMDnsSystemdResolved *self, InterfaceConfig *ic)
 	g_variant_builder_add (&domains, "i", ic->ifindex);
 	g_variant_builder_open (&domains, G_VARIANT_TYPE ("a(sb)"));
 
-	c_list_for_each_entry (elem, &ic->configs_lst_head, lst)
-		update_add_ip_config (self, &dns, &domains, elem->data);
+	c_list_for_each_entry (elem, &ic->configs_lst_head, lst) {
+		NMIPConfig *ip_config = elem->data;
+
+		update_add_ip_config (self, &dns, &domains, ip_config);
+
+		if (NM_IS_IP4_CONFIG (ip_config))
+			mdns = NM_MAX (mdns, nm_ip4_config_mdns_get (NM_IP4_CONFIG (ip_config)));
+	}
 
 	g_variant_builder_close (&dns);
 	g_variant_builder_close (&domains);
 
+	switch (mdns) {
+	case NM_SETTING_CONNECTION_MDNS_NO:
+		mdns_arg = "no";
+		break;
+	case NM_SETTING_CONNECTION_MDNS_RESOLVE:
+		mdns_arg = "resolve";
+		break;
+	case NM_SETTING_CONNECTION_MDNS_YES:
+		mdns_arg = "yes";
+		break;
+	case NM_SETTING_CONNECTION_MDNS_DEFAULT:
+		mdns_arg = "";
+		break;
+	}
+	nm_assert (mdns_arg);
+
 	_request_item_append (&priv->request_queue_lst_head,
 	                      "SetLinkDNS",
 	                      g_variant_builder_end (&dns));
 	_request_item_append (&priv->request_queue_lst_head,
 	                      "SetLinkDomains",
 	                      g_variant_builder_end (&domains));
+	_request_item_append (&priv->request_queue_lst_head,
+	                      "SetLinkMulticastDNS",
+	                      g_variant_new ("(is)", ic->ifindex, mdns_arg ?: ""));
 }
 
 static void
diff --git a/src/nm-ip4-config.c b/src/nm-ip4-config.c
index 5c51a4f66f..9893b14084 100644
--- a/src/nm-ip4-config.c
+++ b/src/nm-ip4-config.c
@@ -293,6 +293,7 @@ typedef struct {
 	int ifindex;
 	NMIPConfigSource mtu_source;
 	gint dns_priority;
+	NMSettingConnectionMdns mdns;
 	GArray *nameservers;
 	GPtrArray *domains;
 	GPtrArray *searches;
@@ -901,6 +902,7 @@ _nm_ip_config_merge_route_attributes (int addr_family,
 void
 nm_ip4_config_merge_setting (NMIP4Config *self,
                              NMSettingIPConfig *setting,
+                             NMSettingConnectionMdns mdns,
                              guint32 route_table,
                              guint32 route_metric)
 {
@@ -1017,6 +1019,8 @@ nm_ip4_config_merge_setting (NMIP4Config *self,
 	if (priority)
 		nm_ip4_config_set_dns_priority (self, priority);
 
+	nm_ip4_config_mdns_set (self, mdns);
+
 	g_object_thaw_notify (G_OBJECT (self));
 }
 
@@ -1232,6 +1236,11 @@ nm_ip4_config_merge (NMIP4Config *dst,
 	if (nm_ip4_config_get_dns_priority (src))
 		nm_ip4_config_set_dns_priority (dst, nm_ip4_config_get_dns_priority (src));
 
+	/* mdns */
+	nm_ip4_config_mdns_set (dst,
+	                        NM_MAX (nm_ip4_config_mdns_get (src),
+	                                nm_ip4_config_mdns_get (dst)));
+
 	g_object_thaw_notify (G_OBJECT (dst));
 }
 
@@ -1468,6 +1477,10 @@ nm_ip4_config_subtract (NMIP4Config *dst,
 	if (nm_ip4_config_get_dns_priority (src) == nm_ip4_config_get_dns_priority (dst))
 		nm_ip4_config_set_dns_priority (dst, 0);
 
+	/* mdns */
+	if (nm_ip4_config_mdns_get (src) == nm_ip4_config_mdns_get (dst))
+		nm_ip4_config_mdns_set (dst, NM_SETTING_CONNECTION_MDNS_DEFAULT);
+
 	g_object_thaw_notify (G_OBJECT (dst));
 }
 
@@ -1568,6 +1581,7 @@ _nm_ip4_config_intersect_helper (NMIP4Config *dst,
 	/* ignore dns options */
 	/* ignore NIS */
 	/* ignore WINS */
+	/* ignore mdns */
 
 	if (update_dst)
 		g_object_thaw_notify (G_OBJECT (dst));
@@ -1846,6 +1860,8 @@ nm_ip4_config_replace (NMIP4Config *dst, const NMIP4Config *src, gboolean *relev
 		has_relevant_changes = TRUE;
 	}
 
+	dst_priv->mdns = src_priv->mdns;
+
 	/* DNS priority */
 	if (src_priv->dns_priority != dst_priv->dns_priority) {
 		nm_ip4_config_set_dns_priority (dst, src_priv->dns_priority);
@@ -2523,6 +2539,21 @@ nm_ip4_config_get_dns_option (const NMIP4Config *self, guint i)
 
 /*****************************************************************************/
 
+NMSettingConnectionMdns
+nm_ip4_config_mdns_get (const NMIP4Config *self)
+{
+	return NM_IP4_CONFIG_GET_PRIVATE (self)->mdns;
+}
+
+void
+nm_ip4_config_mdns_set (NMIP4Config *self,
+                        NMSettingConnectionMdns mdns)
+{
+	NM_IP4_CONFIG_GET_PRIVATE (self)->mdns = mdns;
+}
+
+/*****************************************************************************/
+
 void
 nm_ip4_config_set_dns_priority (NMIP4Config *self, gint priority)
 {
@@ -3133,6 +3164,7 @@ nm_ip4_config_init (NMIP4Config *self)
 	nm_ip_config_dedup_multi_idx_type_init ((NMIPConfigDedupMultiIdxType *) &priv->idx_ip4_routes,
 	                                        NMP_OBJECT_TYPE_IP4_ROUTE);
 
+	priv->mdns = NM_SETTING_CONNECTION_MDNS_DEFAULT;
 	priv->nameservers = g_array_new (FALSE, FALSE, sizeof (guint32));
 	priv->domains = g_ptr_array_new_with_free_func (g_free);
 	priv->searches = g_ptr_array_new_with_free_func (g_free);
diff --git a/src/nm-ip4-config.h b/src/nm-ip4-config.h
index ba2d6ad981..d4c67d8943 100644
--- a/src/nm-ip4-config.h
+++ b/src/nm-ip4-config.h
@@ -21,6 +21,8 @@
 #ifndef __NETWORKMANAGER_IP4_CONFIG_H__
 #define __NETWORKMANAGER_IP4_CONFIG_H__
 
+#include "nm-setting-connection.h"
+
 #include "nm-exported-object.h"
 #include "nm-setting-ip4-config.h"
 
@@ -172,6 +174,7 @@ gboolean nm_ip4_config_commit (const NMIP4Config *self,
 
 void nm_ip4_config_merge_setting (NMIP4Config *self,
                                   NMSettingIPConfig *setting,
+                                  NMSettingConnectionMdns mdns,
                                   guint32 route_table,
                                   guint32 route_metric);
 NMSetting *nm_ip4_config_create_setting (const NMIP4Config *self);
@@ -198,6 +201,10 @@ const NMPObject *_nm_ip4_config_best_default_route_find (const NMIP4Config *self
 
 in_addr_t nmtst_ip4_config_get_gateway (NMIP4Config *config);
 
+NMSettingConnectionMdns nm_ip4_config_mdns_get (const NMIP4Config *self);
+void                    nm_ip4_config_mdns_set (NMIP4Config *self,
+                                                NMSettingConnectionMdns mdns);
+
 const NMDedupMultiHeadEntry *nm_ip4_config_lookup_addresses (const NMIP4Config *self);
 void nm_ip4_config_reset_addresses (NMIP4Config *self);
 void nm_ip4_config_add_address (NMIP4Config *self, const NMPlatformIP4Address *address);
diff --git a/src/settings/plugins/ifcfg-rh/nms-ifcfg-rh-writer.c b/src/settings/plugins/ifcfg-rh/nms-ifcfg-rh-writer.c
index f326795254..32f056f7e0 100644
--- a/src/settings/plugins/ifcfg-rh/nms-ifcfg-rh-writer.c
+++ b/src/settings/plugins/ifcfg-rh/nms-ifcfg-rh-writer.c
@@ -1888,9 +1888,8 @@ write_connection_setting (NMSettingConnection *s_con, shvarFile *ifcfg)
 	if (mdns != NM_SETTING_CONNECTION_MDNS_DEFAULT) {
 		svSetValueEnum (ifcfg, "MDNS", nm_setting_connection_mdns_get_type (),
 		                mdns);
-	} else {
+	} else
 		svUnsetValue (ifcfg, "MDNS");
-	}
 }
 
 static char *
diff --git a/src/vpn/nm-vpn-connection.c b/src/vpn/nm-vpn-connection.c
index 948d867333..964167fc8f 100644
--- a/src/vpn/nm-vpn-connection.c
+++ b/src/vpn/nm-vpn-connection.c
@@ -1460,6 +1460,7 @@ nm_vpn_connection_ip4_config_get (NMVpnConnection *self, GVariant *dict)
 	NMPlatformIP4Address address;
 	guint32 u32, route_metric;
 	NMSettingIPConfig *s_ip;
+	NMSettingConnection *s_con;
 	guint32 route_table;
 	NMIP4Config *config;
 	GVariantIter *iter;
@@ -1564,6 +1565,7 @@ nm_vpn_connection_ip4_config_get (NMVpnConnection *self, GVariant *dict)
 	route_table = get_route_table (self, AF_INET, TRUE);
 	route_metric = nm_vpn_connection_get_ip4_route_metric (self);
 	s_ip = nm_connection_get_setting_ip4_config (_get_applied_connection (self));
+	s_con = nm_connection_get_setting_connection (_get_applied_connection (self));
 
 	if (nm_setting_ip_config_get_ignore_auto_routes (s_ip)) {
 		/* ignore VPN routes */
@@ -1621,6 +1623,7 @@ nm_vpn_connection_ip4_config_get (NMVpnConnection *self, GVariant *dict)
 	/* Merge in user overrides from the NMConnection's IPv4 setting */
 	nm_ip4_config_merge_setting (config,
 	                             s_ip,
+	                             nm_setting_connection_get_mdns (s_con),
 	                             route_table,
 	                             route_metric);