libifupdown: add initial interface management code

Makefile

@@ -3,7 +3,8 @@ CFLAGS := -ggdb3 -O2 -Wall -I.
 
 LIBIFUPDOWN_SRC = \
 	libifupdown/list.c \
-	libifupdown/dict.c
+	libifupdown/dict.c \
+	libifupdown/interface.c
 
 LIBIFUPDOWN_OBJ = ${LIBIFUPDOWN_SRC:.c=.o}
 

libifupdown/interface.c

@@ -0,0 +1,209 @@
+/*
+ * libifupdown/interface.c
+ * Purpose: interface management
+ *
+ * Copyright (c) 2020 Ariadne Conill <ariadne@dereferenced.org>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * This software is provided 'as is' and without any warranty, express or
+ * implied.  In no event shall the authors be liable for any damages arising
+ * from the use of this software.
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include "libifupdown/interface.h"
+
+bool
+lif_address_parse(struct lif_address *address, const char *presentation)
+{
+	char buf[512], *netmask_p;
+
+	strlcpy(buf, presentation, sizeof buf);
+
+	address->domain = strchr(buf, ':') != NULL ? AF_INET6 : AF_INET;
+
+	netmask_p = strrchr(buf, '/');
+	if (netmask_p != NULL)
+	{
+		*netmask_p++ = '\0';
+		address->netmask = strtol(netmask_p, NULL, 10);
+	}
+	else
+		address->netmask = 0;
+
+	return !!inet_pton(address->domain, buf, address->addr_buf);
+}
+
+bool
+lif_address_unparse(const struct lif_address *address, char *buf, size_t buflen, bool with_netmask)
+{
+	char workbuf[512] = {};
+
+	if (!inet_ntop(address->domain, address->addr_buf, workbuf, sizeof workbuf))
+		return false;
+
+	if (!with_netmask || !address->netmask)
+	{
+		strlcpy(buf, workbuf, buflen);
+		return true;
+	}
+
+	snprintf(buf, buflen, "%s/%zu", workbuf, address->netmask);
+	return true;
+}
+
+void
+lif_interface_init(struct lif_interface *interface, const char *ifname)
+{
+	memset(interface, '\0', sizeof *interface);
+
+	interface->ifname = strdup(ifname);
+}
+
+bool
+lif_interface_address_add(struct lif_interface *interface, const char *address)
+{
+	struct lif_address *addr = calloc(1, sizeof *addr);
+
+	if (!lif_address_parse(addr, address))
+	{
+		free(addr);
+		return false;
+	}
+
+	lif_dict_add(&interface->vars, "address", addr);
+	return true;
+}
+
+void
+lif_interface_address_delete(struct lif_interface *interface, const char *address)
+{
+	struct lif_node *iter, *iter_next;
+	struct lif_address addr;
+
+	if (!lif_address_parse(&addr, address))
+		return;
+
+	LIF_DICT_FOREACH_SAFE(iter, iter_next, &interface->vars)
+	{
+		struct lif_dict_entry *entry = iter->data;
+
+		if (strcmp(entry->key, "address"))
+			continue;
+
+		struct lif_address *entry_addr = entry->data;
+		char addr_buf[512] = {};
+
+		if (!lif_address_unparse(entry_addr, addr_buf, sizeof addr_buf, addr.netmask != 0))
+			continue;
+
+		if (strcmp(addr_buf, address))
+			continue;
+
+		lif_dict_delete_entry(&interface->vars, entry);
+		free(entry_addr);
+	}
+}
+
+void
+lif_interface_fini(struct lif_interface *interface)
+{
+	struct lif_node *iter, *iter_next;
+
+	LIF_DICT_FOREACH_SAFE(iter, iter_next, &interface->vars)
+	{
+		struct lif_dict_entry *entry = iter->data;
+
+		free(entry->data);
+		lif_dict_delete_entry(&interface->vars, entry);
+	}
+
+	free(interface->ifname);
+}
+
+void
+lif_interface_collection_init(struct lif_dict *collection)
+{
+	struct lif_interface *if_lo;
+
+	memset(collection, '\0', sizeof *collection);
+
+	/* always enable loopback interface as part of a collection */
+	if_lo = lif_interface_collection_find(collection, "lo");
+	if_lo->is_auto = if_lo->is_loopback = true;
+
+	lif_interface_address_add(if_lo, "127.0.0.1/8");
+}
+
+void
+lif_interface_collection_fini(struct lif_dict *collection)
+{
+	struct lif_node *iter, *iter_next;
+
+	LIF_DICT_FOREACH_SAFE(iter, iter_next, collection)
+	{
+		struct lif_dict_entry *entry = iter->data;
+		struct lif_interface *iface = entry->data;
+
+		lif_interface_fini(iface);
+		free(iface);
+
+		lif_dict_delete_entry(collection, entry);
+	}
+}
+
+struct lif_interface *
+lif_interface_collection_find(struct lif_dict *collection, const char *ifname)
+{
+	struct lif_dict_entry *entry = lif_dict_find(collection, ifname);
+
+	if (entry == NULL)
+	{
+		struct lif_interface *iface = calloc(1, sizeof *iface);
+
+		lif_interface_init(iface, ifname);
+		lif_dict_add(collection, ifname, iface);
+
+		return iface;
+	}
+
+	return entry->data;
+}
+
+struct lif_interface *
+lif_interface_collection_upsert(struct lif_dict *collection, struct lif_interface *interface)
+{
+	struct lif_dict_entry *entry = lif_dict_find(collection, interface->ifname);
+
+	if (entry == NULL)
+	{
+		lif_dict_add(collection, interface->ifname, interface);
+		return interface;
+	}
+
+	if (entry->data == interface)
+		return interface;
+
+	lif_interface_collection_delete(collection, entry->data);
+	lif_dict_add(collection, interface->ifname, interface);
+
+	return interface;
+}
+
+void
+lif_interface_collection_delete(struct lif_dict *collection, struct lif_interface *interface)
+{
+	struct lif_dict_entry *entry = lif_dict_find(collection, interface->ifname);
+
+	if (entry == NULL)
+		return;
+
+	lif_interface_fini(interface);
+	free(interface);
+
+	lif_dict_delete_entry(collection, entry);
+}

libifupdown/interface.h

@@ -0,0 +1,74 @@
+/*
+ * libifupdown/interface.h
+ * Purpose: interface management
+ *
+ * Copyright (c) 2020 Ariadne Conill <ariadne@dereferenced.org>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * This software is provided 'as is' and without any warranty, express or
+ * implied.  In no event shall the authors be liable for any damages arising
+ * from the use of this software.
+ */
+
+#ifndef LIBIFUPDOWN_INTERFACE_H__GUARD
+#define LIBIFUPDOWN_INTERFACE_H__GUARD
+
+#include <arpa/inet.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include "libifupdown/dict.h"
+
+/*
+ * Addresses are stored in a buffer with netmask and type.
+ */
+struct lif_address {
+	unsigned char addr_buf[sizeof(struct in6_addr)];
+	size_t netmask;
+	int domain;
+};
+
+extern bool lif_address_parse(struct lif_address *address, const char *presentation);
+extern bool lif_address_unparse(const struct lif_address *address, char *buf, size_t buflen, bool with_netmask);
+
+/*
+ * Interfaces are contained in a dictionary, with the interfaces mapped by
+ * interface name to their `struct lif_interface`.
+ *
+ * Interfaces are simply upserted as needed.  This allows for `auto eth0`
+ * to create a placeholder `struct lif_interface` with auto set to true.
+ *
+ * Configuration variables are simply stored in a `struct lif_dict`, which
+ * can act as a multidict.
+ */
+struct lif_interface {
+	char *ifname;
+
+	bool is_dhcp;
+	bool is_loopback;
+	bool is_auto;
+
+	struct lif_dict vars;
+};
+
+#define LIF_INTERFACE_COLLECTION_FOREACH(iter, collection) \
+	LIF_DICT_FOREACH((iter), (collection))
+
+#define LIF_INTERFACE_COLLECTION_FOREACH_SAFE(iter, iter_next, collection) \
+	LIF_DICT_FOREACH_SAFE((iter), (iter_next), (collection))
+
+extern void lif_interface_init(struct lif_interface *interface, const char *ifname);
+extern bool lif_interface_address_add(struct lif_interface *interface, const char *address);
+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_collection_init(struct lif_dict *collection);
+extern void lif_interface_collection_fini(struct lif_dict *collection);
+extern struct lif_interface *lif_interface_collection_find(struct lif_dict *collection, const char *ifname);
+extern struct lif_interface *lif_interface_collection_upsert(struct lif_dict *collection, struct lif_interface *interface);
+extern void lif_interface_collection_delete(struct lif_dict *collection, struct lif_interface *interface);
+
+#endif