DHCP address match and mangler

extensions/libxt_dhcpaddr.c

@@ -0,0 +1,102 @@
+/*
+ *	"dhcpaddr" match extension for iptables
+ *	Copyright © Jan Engelhardt <jengelh [at] medozas de>, 2008
+ *
+ *	This program is free software; you can redistribute it and/or
+ *	modify it under the terms of the GNU General Public License; either
+ *	version 2 of the License, or any later version, as published by the
+ *	Free Software Foundation.
+ */
+#include <getopt.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <netdb.h>
+#include <net/ethernet.h>
+#include <xtables.h>
+#include "xt_DHCPADDR.h"
+#include "mac.c"
+
+enum {
+	F_MAC = 1 << 0,
+};
+
+static const struct option dhcpaddr_mt_opts[] = {
+	{.name = "mac", .has_arg = true, .val = 'M'},
+	{NULL},
+};
+
+static void dhcpaddr_mt_help(void)
+{
+	printf(
+"dhcpaddr match options:\n"
+"[!] --mac lladdr[/mask]    Match on MAC address in DHCP Client Host field\n"
+	);
+}
+
+static int dhcpaddr_mt_parse(int c, char **argv, int invert,
+    unsigned int *flags, const void *entry, struct xt_entry_match **match)
+{
+	struct dhcpaddr_info *info = (void *)(*match)->data;
+
+	switch (c) {
+	case 'M':
+		param_act(P_ONLY_ONCE, "dhcpaddr", "--mac", *flags & F_MAC);
+		param_act(P_NO_INVERT, "dhcpaddr", "--mac", invert);
+		if (!mac_parse(optarg, info->addr, &info->mask))
+			param_act(P_BAD_VALUE, "dhcpaddr", "--mac", optarg);
+		if (invert)
+			info->invert = true;
+		*flags |= F_MAC;
+		return true;
+	}
+
+	return false;
+}
+
+static void dhcpaddr_mt_check(unsigned int flags)
+{
+	if (flags == 0)
+		exit_error(PARAMETER_PROBLEM, "dhcpaddr match: "
+		           "--mac parameter required");
+}
+
+static void dhcpaddr_mt_print(const void *ip,
+    const struct xt_entry_match *match, int numeric)
+{
+	const struct dhcpaddr_info *info = (void *)match->data;
+
+	printf("dhcpaddr %s" DH_MAC_FMT "/%u ",
+	       info->invert ? "!" : "", DH_MAC_HEX(info->addr), info->mask);
+}
+
+static void dhcpaddr_mt_save(const void *ip,
+    const struct xt_entry_match *match)
+{
+	const struct dhcpaddr_info *info = (void *)match->data;
+
+	if (info->invert)
+		printf("! ");
+	printf("--mac " DH_MAC_FMT "/%u ",
+	       DH_MAC_HEX(info->addr), info->mask);
+}
+
+static struct xtables_match dhcpaddr_mt_reg = {
+	.version       = XTABLES_VERSION,
+	.name          = "dhcpaddr",
+	.revision      = 0,
+	.family        = PF_INET,
+	.size          = XT_ALIGN(sizeof(struct dhcpaddr_info)),
+	.userspacesize = XT_ALIGN(sizeof(struct dhcpaddr_info)),
+	.help          = dhcpaddr_mt_help,
+	.parse         = dhcpaddr_mt_parse,
+	.final_check   = dhcpaddr_mt_check,
+	.print         = dhcpaddr_mt_print,
+	.save          = dhcpaddr_mt_save,
+	.extra_opts    = dhcpaddr_mt_opts,
+};
+
+static void _init(void)
+{
+	xtables_register_match(&dhcpaddr_mt_reg);
+}