compat: Add glue for ifupdown2 bridge port VLAN inheritance.

Add config options <compat_ifupdown2_bridge_ports_inherit_vlans>.

  In ifupdown2 <bridge-vids> as well as the <bridge-pvid> set on a bridge
  interface will be inherited by all member ports if not set explicitly.
  When set to 1 ifupdown-ng behaves the same way and will internally copy
  both options from the bridge member ports if they are not set on the
  member port. Valid values are 0 and 1, the default is 1.

Signed-off-by: Maximilian Wilhelm <max@sdn.clinic>

dist/ifupdown-ng.conf.example

@@ -17,6 +17,14 @@ allow_addon_scripts = 1
 # templates.  Valid values are 0 and 1, the default is 1.
 allow_any_iface_as_template = 1
 
+# compat_ifupdown2_bridge_ports_inherit_vlans:
+# In ifupdown2 <bridge-vids> as well as the <bridge-pvid> set on a bridge
+# interface will be inherited by all member ports if not set explicitly.
+# When set to 1 ifupdown-ng behaves the same way and will internally copy
+# both options from the bridge member ports if they are not set on the
+# member port. Valid values are 0 and 1, the default is 1.
+compat_ifupdown2_bridge_ports_inherit_vlans = 1
+
 # implicit_template_conversion:
 # In some legacy configs, a template may be declared as an iface, and
 # ifupdown-ng automatically converts those declarations to a proper

doc/ADMIN-GUIDE.md

@@ -60,6 +60,13 @@ Currently the following settings are supported in
   in order to require inheritance from specified templates.
   Valid values are `0` and `1`, the default is `1`.
 
+* `compat_ifupdown2_bridge_ports_inherit_vlans`: In ifupdown2 `bridge-vids`
+  as well as the <bridge-pvid> set on a bridge interface will be inherited
+  by all member ports if not set explicitly.  When set to `1` ifupdown-ng
+  behaves the same way and will internally copy both options from the
+  bridge member ports if they are not set on the member port.
+  Valid values are `0` and `1`, the default is `1`.
+
 * `implicit_template_conversion`: In some legacy configs, a template
   may be declared as an iface, and ifupdown-ng automatically converts
   those declarations to a proper template.  If this setting is

libifupdown/compat.c

@@ -14,14 +14,91 @@
  */
 
 #include <stdbool.h>
+#include <string.h>
+#include "libifupdown/config-file.h"
 #include "libifupdown/dict.h"
+#include "libifupdown/interface.h"
+#include "libifupdown/tokenize.h"
+
+static bool
+compat_ifupdown2_bridge_ports_inherit_vlans(struct lif_dict *collection)
+{
+	struct lif_node *iter;
+
+	/* Loop through all interfaces and search for bridges */
+	LIF_DICT_FOREACH(iter, collection)
+	{
+		struct lif_dict_entry *entry = iter->data;
+		struct lif_interface *bridge = entry->data;
+
+		/* We only care for bridges */
+		if (!bridge->is_bridge)
+			continue;
+
+		struct lif_dict_entry *bridge_pvid = lif_dict_find(&bridge->vars, "bridge-pvid");
+		struct lif_dict_entry *bridge_vids = lif_dict_find(&bridge->vars, "bridge-vids");
+
+		/* If there's nothing to inherit here, carry on */
+		if (bridge_pvid == NULL && bridge_vids == NULL)
+			continue;
+
+		struct lif_dict_entry *bridge_ports_entry = lif_dict_find(&bridge->vars, "bridge-ports");
+
+		/* This SHOULD not happen, but better save than sorry */
+		if (bridge_ports_entry == NULL)
+			continue;
+
+		char bridge_ports_str[4096] = {};
+		strlcpy(bridge_ports_str, bridge_ports_entry->data, sizeof bridge_ports_str);
+
+		/* If there are no bridge-ports configured, carry on */
+		if (strcmp(bridge_ports_str, "none") == 0)
+			continue;
+
+		/* Loop over all bridge-ports and set bridge-pvid and bridge-vid if not set already */
+		char *bufp = bridge_ports_str;
+		for (char *tokenp = lif_next_token(&bufp); *tokenp; tokenp = lif_next_token(&bufp))
+		{
+			entry = lif_dict_find(collection, tokenp);
+
+			/* There might be interfaces give within the bridge-ports for which there is no
+			 * interface stanza. If this is the case, we add one, so we can inherit the
+			 * bridge-vids/pvid to it. */
+			struct lif_interface *bridge_port;
+			if (entry)
+				bridge_port = entry->data;
+
+			else
+			{
+				bridge_port = lif_interface_collection_find(collection, tokenp);
+				if (bridge_port == NULL)
+				{
+					fprintf(stderr, "Failed to add interface \"%s\"", tokenp);
+					return false;
+				}
+			}
+
+			/* Maybe pimp bridge-pvid */
+			struct lif_dict_entry *port_pvid = lif_dict_find(&bridge_port->vars, "bridge-pvid");
+			if (bridge_pvid && !port_pvid)
+				lif_dict_add(&bridge_port->vars, "bridge-pvid", bridge_pvid->data);
+
+			/* Maybe pimp bridge-vids */
+			struct lif_dict_entry *port_vids = lif_dict_find(&bridge_port->vars, "bridge-vids");
+			if (bridge_vids && !port_vids)
+				lif_dict_add(&bridge_port->vars, "bridge-vids", bridge_vids->data);
+		}
+	}
+
+	return true;
+}
 
 extern bool
 lif_compat_apply(struct lif_dict *collection)
 {
-	(void) collection;
-
-	/* Mangle interfaces according to some config options here */
+	if (lif_config.compat_ifupdown2_bridge_ports_inherit_vlans &&
+	    !compat_ifupdown2_bridge_ports_inherit_vlans(collection))
+		return false;
 
 	return true;
 }

libifupdown/config-file.c

@@ -21,6 +21,7 @@
 struct lif_config_file lif_config = {
 	.allow_addon_scripts = true,
 	.allow_any_iface_as_template = true,
+	.compat_ifupdown2_bridge_ports_inherit_vlans = true,
 	.implicit_template_conversion = true,
 	.use_hostname_for_dhcp = true,
 };
@@ -47,6 +48,7 @@ set_bool_value(const char *key, const char *value, void *opaque)
 static struct lif_config_handler handlers[] = {
 	{"allow_addon_scripts", set_bool_value, &lif_config.allow_addon_scripts},
 	{"allow_any_iface_as_template", set_bool_value, &lif_config.allow_any_iface_as_template},
+	{"compat_ifupdown2_bridge_ports_inherit_vlans", set_bool_value, &lif_config.compat_ifupdown2_bridge_ports_inherit_vlans},
 	{"implicit_template_conversion", set_bool_value, &lif_config.implicit_template_conversion},
 	{"use_hostname_for_dhcp", set_bool_value, &lif_config.use_hostname_for_dhcp},
 };

libifupdown/config-file.h

@@ -21,6 +21,7 @@
 struct lif_config_file {
 	bool allow_addon_scripts;
 	bool allow_any_iface_as_template;
+	bool compat_ifupdown2_bridge_ports_inherit_vlans;
 	bool implicit_template_conversion;
 	bool use_hostname_for_dhcp;
 };

libifupdown/interface-file.c

@@ -203,6 +203,10 @@ handle_generic(struct lif_interface_file_parse_state *state, char *token, char *
 
 	token = maybe_remap_token(token);
 
+	/* This smells like a bridge */
+	if (strcmp(token, "bridge-ports") == 0)
+		state->cur_iface->is_bridge = true;
+
 	/* Skip any leading whitespaces in value for <token> */
 	while (isspace (*bufp))
 		bufp++;