From c4d9d6fd06a1d6b486e88782fcb7965ffdbd6494 Mon Sep 17 00:00:00 2001
From: Ariadne Conill <ariadne@dereferenced.org>
Date: Wed, 2 Dec 2020 11:38:39 -0700
Subject: [PATCH] interface: add lif_interface_finalize() which rewrites
 addresses as CIDR when an interface stanza ends

---
 libifupdown/interface-file.c | 11 ++++++++
 libifupdown/interface.c      | 52 ++++++++++++++++++++++++++++++------
 libifupdown/interface.h      |  1 +
 3 files changed, 56 insertions(+), 8 deletions(-)

diff --git a/libifupdown/interface-file.c b/libifupdown/interface-file.c
index d5c9fa5..3d217a9 100644
--- a/libifupdown/interface-file.c
+++ b/libifupdown/interface-file.c
@@ -263,6 +263,12 @@ handle_iface(struct lif_interface_file_parse_state *state, char *token, char *bu
 		return true;
 	}
 
+	/* if we have a current interface, call lif_interface_finalize to finalize any
+	 * address properties by converting them to CIDR and flushing the netmask property.
+	 */
+	if (state->cur_iface != NULL)
+		lif_interface_finalize(state->cur_iface);
+
 	state->cur_iface = lif_interface_collection_find(state->collection, ifname);
 	if (state->cur_iface == NULL)
 	{
@@ -501,6 +507,11 @@ lif_interface_file_parse(struct lif_interface_file_parse_state *state, const cha
 	}
 
 	fclose(f);
+
+	/* finalize any open interface */
+	if (state->cur_iface != NULL)
+		lif_interface_finalize(state->cur_iface);
+
 	state->cur_filename = old_filename;
 	state->cur_lineno = old_lineno;
 	return true;
diff --git a/libifupdown/interface.c b/libifupdown/interface.c
index b18e318..0294383 100644
--- a/libifupdown/interface.c
+++ b/libifupdown/interface.c
@@ -84,6 +84,19 @@ count_set_bits(const char *netmask)
 	return r;
 }
 
+static inline size_t
+determine_interface_netmask(const struct lif_interface *iface, const struct lif_address *addr)
+{
+	/* if netmask is not set, default to /24 or /64, ifupdown does so too */
+	size_t netmask = addr->domain == AF_INET6 ? 64 : 24;
+
+	struct lif_dict_entry *entry = lif_dict_find(&iface->vars, "netmask");
+	if (entry != NULL)
+		netmask = count_set_bits(entry->data);
+
+	return netmask;
+}
+
 bool
 lif_address_format_cidr(const struct lif_interface *iface, struct lif_dict_entry *entry, char *buf, size_t buflen)
 {
@@ -91,14 +104,7 @@ lif_address_format_cidr(const struct lif_interface *iface, struct lif_dict_entry
 	size_t orig_netmask = addr->netmask;
 
 	if (!addr->netmask)
-	{
-		/* if netmask is not set, default to 255.255.255.0, ifupdown does so too */
-		addr->netmask = addr->domain == AF_INET6 ? 64 : 24;
-
-		struct lif_dict_entry *entry = lif_dict_find(&iface->vars, "netmask");
-		if (entry != NULL)
-			addr->netmask = count_set_bits(entry->data);
-	}
+		addr->netmask = determine_interface_netmask(iface, addr);
 
 	if (!lif_address_unparse(addr, buf, buflen, true))
 	{
@@ -213,6 +219,36 @@ lif_interface_use_executor(struct lif_interface *interface, const char *executor
 	lif_dict_add(&interface->vars, "hostname", strdup(un.nodename));
 }
 
+void
+lif_interface_finalize(struct lif_interface *interface)
+{
+	struct lif_node *iter;
+
+	/* convert all addresses to CIDR notation. */
+	LIF_DICT_FOREACH(iter, &interface->vars)
+	{
+		struct lif_dict_entry *entry = iter->data;
+
+		if (strcmp(entry->key, "address"))
+			continue;
+
+		struct lif_address *addr = entry->data;
+
+		if (!addr->netmask)
+			addr->netmask = determine_interface_netmask(interface, addr);
+	}
+
+	/* with all addresses converted to CIDR, netmask property is no longer needed. */
+	struct lif_dict_entry *entry = lif_dict_find(&interface->vars, "netmask");
+
+	if (entry != NULL)
+	{
+		free(entry->data);
+
+		lif_dict_delete_entry(&interface->vars, entry);
+	}
+}
+
 void
 lif_interface_collection_init(struct lif_dict *collection)
 {
diff --git a/libifupdown/interface.h b/libifupdown/interface.h
index 0c6d8b2..49c867d 100644
--- a/libifupdown/interface.h
+++ b/libifupdown/interface.h
@@ -75,6 +75,7 @@ extern bool lif_interface_address_add(struct lif_interface *interface, const cha
 extern void lif_interface_address_delete(struct lif_interface *interface, const char *address);
 extern void lif_interface_fini(struct lif_interface *interface);
 extern void lif_interface_use_executor(struct lif_interface *interface, const char *executor);
+extern void lif_interface_finalize(struct lif_interface *interface);
 
 extern void lif_interface_collection_init(struct lif_dict *collection);
 extern void lif_interface_collection_fini(struct lif_dict *collection);