core: read "disable_ipv6" sysctl before nm_ip6_config_create_setting()

First of all, the entire nm_device_generate_connection() and
nm_ip._config_create_setting() approach is fundamentally flawed. You
cannot generate sensible configuration by reading IP addresses from
an interface. Anyway, that's what we still sometimes do, and we possibly
should do it less and less.

It's ugly that nm_ip6_config_capture() would read the "disable_ipv6"
sysctl value and cache it in NMIP6Config. Only so that it can be use
much later during nm_ip6_config_create_setting().

Instead, read the sysctl value shortly before it's needed.

3 files changed, 28 insertions, 26 deletions

diff --git a/src/devices/nm-device.c b/src/devices/nm-device.c
index 91b0edfd50..8950f01bde 100644
--- a/src/devices/nm-device.c
+++ b/src/devices/nm-device.c
@@ -6169,6 +6169,26 @@ nm_device_master_update_slave_connection (NMDevice *self,
 	return FALSE;
 }
 
+static gboolean
+_get_maybe_ipv6_disabled (NMDevice *self)
+{
+	NMPlatform *platform;
+	int ifindex;
+	const char *path;
+	char ifname[IFNAMSIZ];
+
+	ifindex = nm_device_get_ip_ifindex (self);
+	if (ifindex <= 0)
+		return FALSE;
+
+	platform = nm_device_get_platform (self);
+	if (!nm_platform_if_indextoname (platform, ifindex, ifname))
+		return FALSE;
+
+	path = nm_sprintf_bufa (128, "/proc/sys/net/ipv6/conf/%s/disable_ipv6", ifname);
+	return (nm_platform_sysctl_get_int32 (platform, NMP_SYSCTL_PATHID_ABSOLUTE (path), 0) == 0);
+}
+
 NMConnection *
 nm_device_generate_connection (NMDevice *self,
                                NMDevice *master,
@@ -6237,7 +6257,7 @@ nm_device_generate_connection (NMDevice *self,
 		s_ip4 = nm_ip4_config_create_setting (priv->ip_config_4);
 		nm_connection_add_setting (connection, s_ip4);
 
-		s_ip6 = nm_ip6_config_create_setting (priv->ip_config_6);
+		s_ip6 = nm_ip6_config_create_setting (priv->ip_config_6, _get_maybe_ipv6_disabled (self));
 		nm_connection_add_setting (connection, s_ip6);
 
 		nm_connection_add_setting (connection, nm_setting_proxy_new ());
@@ -13415,9 +13435,10 @@ nm_device_set_ip_config (NMDevice *self,
 			new_connection = nm_simple_connection_new_clone (nm_settings_connection_get_connection (settings_connection));
 
 			nm_connection_add_setting (new_connection,
-			                           IS_IPv4
-			                             ? nm_ip4_config_create_setting (priv->ip_config_4)
-			                             : nm_ip6_config_create_setting (priv->ip_config_6));
+			                             IS_IPv4
+			                           ? nm_ip4_config_create_setting (priv->ip_config_4)
+			                           : nm_ip6_config_create_setting (priv->ip_config_6,
+			                                                           _get_maybe_ipv6_disabled (self)));
 
 			nm_settings_connection_update (settings_connection,
 			                               new_connection,
diff --git a/src/nm-ip6-config.c b/src/nm-ip6-config.c
index 6c15e99765..61b32b68a1 100644
--- a/src/nm-ip6-config.c
+++ b/src/nm-ip6-config.c
@@ -64,7 +64,6 @@ typedef struct {
 		NMDedupMultiIdxType idx_ip6_routes;
 	};
 	NMIPConfigFlags config_flags;
-	bool ipv6_disabled;
 } NMIP6ConfigPrivate;
 
 struct _NMIP6Config {
@@ -373,8 +372,6 @@ nm_ip6_config_capture (NMDedupMultiIndex *multi_idx, NMPlatform *platform, int i
 	const NMDedupMultiHeadEntry *head_entry;
 	NMDedupMultiIter iter;
 	const NMPObject *plobj = NULL;
-	char ifname[IFNAMSIZ];
-	char *path;
 
 	nm_assert (ifindex > 0);
 
@@ -416,12 +413,6 @@ nm_ip6_config_capture (NMDedupMultiIndex *multi_idx, NMPlatform *platform, int i
 	nmp_cache_iter_for_each (&iter, head_entry, &plobj)
 		_add_route (self, plobj, NULL, NULL);
 
-	if (nm_platform_if_indextoname (platform, ifindex, ifname)) {
-		path = nm_sprintf_bufa (128, "/proc/sys/net/ipv6/conf/%s/disable_ipv6", ifname);
-		if (nm_platform_sysctl_get_int32 (platform, NMP_SYSCTL_PATHID_ABSOLUTE (path), 0) != 0)
-			priv->ipv6_disabled = TRUE;
-	}
-
 	return self;
 }
 
@@ -757,7 +748,7 @@ nm_ip6_config_merge_setting (NMIP6Config *self,
 }
 
 NMSetting *
-nm_ip6_config_create_setting (const NMIP6Config *self)
+nm_ip6_config_create_setting (const NMIP6Config *self, gboolean maybe_ipv6_disabled)
 {
 	const NMIP6ConfigPrivate *priv;
 	NMSettingIPConfig *s_ip6;
@@ -822,7 +813,7 @@ nm_ip6_config_create_setting (const NMIP6Config *self)
 
 	/* Use 'ignore' if the method wasn't previously set */
 	if (!method) {
-		method =   priv->ipv6_disabled
+		method =   maybe_ipv6_disabled
 		         ? NM_SETTING_IP6_CONFIG_METHOD_DISABLED
 		         : NM_SETTING_IP6_CONFIG_METHOD_IGNORE;
 	}
@@ -893,13 +884,11 @@ nm_ip6_config_merge (NMIP6Config *dst,
 	NMDedupMultiIter ipconf_iter;
 	const NMPlatformIP6Address *address = NULL;
 	const NMIP6ConfigPrivate *src_priv;
-	NMIP6ConfigPrivate *dst_priv;
 
 	g_return_if_fail (src != NULL);
 	g_return_if_fail (dst != NULL);
 
 	src_priv = NM_IP6_CONFIG_GET_PRIVATE (src);
-	dst_priv = NM_IP6_CONFIG_GET_PRIVATE (dst);
 
 	g_object_freeze_notify (G_OBJECT (dst));
 
@@ -965,9 +954,6 @@ nm_ip6_config_merge (NMIP6Config *dst,
 	if (nm_ip6_config_get_dns_priority (src))
 		nm_ip6_config_set_dns_priority (dst, nm_ip6_config_get_dns_priority (src));
 
-	if (src_priv->ipv6_disabled)
-		dst_priv->ipv6_disabled = src_priv->ipv6_disabled;
-
 	g_object_thaw_notify (G_OBJECT (dst));
 }
 
@@ -1573,11 +1559,6 @@ nm_ip6_config_replace (NMIP6Config *dst, const NMIP6Config *src, gboolean *relev
 		has_minor_changes = TRUE;
 	}
 
-	if (src_priv->ipv6_disabled != dst_priv->ipv6_disabled) {
-		dst_priv->ipv6_disabled = src_priv->ipv6_disabled;
-		has_minor_changes = TRUE;
-	}
-
 #if NM_MORE_ASSERTS
 	/* config_equal does not compare *all* the fields, therefore, we might have has_minor_changes
 	 * regardless of config_equal. But config_equal must correspond to has_relevant_changes. */
diff --git a/src/nm-ip6-config.h b/src/nm-ip6-config.h
index b6f461b29f..4c21768ad8 100644
--- a/src/nm-ip6-config.h
+++ b/src/nm-ip6-config.h
@@ -105,7 +105,7 @@ void nm_ip6_config_merge_setting (NMIP6Config *self,
                                   NMSettingIPConfig *setting,
                                   guint32 route_table,
                                   guint32 route_metric);
-NMSetting *nm_ip6_config_create_setting (const NMIP6Config *self);
+NMSetting *nm_ip6_config_create_setting (const NMIP6Config *self, gboolean maybe_ipv6_disabled);
 
 void nm_ip6_config_merge (NMIP6Config *dst,
                           const NMIP6Config *src,