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Message-ID: <Pine.LNX.4.61.0706021856590.5076@yvahk01.tjqt.qr>
Date: Sat, 2 Jun 2007 18:57:14 +0200 (MEST)
From: Jan Engelhardt <jengelh@...ux01.gwdg.de>
To: Amin Azez <azez@...mechanic.net>
cc: Netfilter Developer Mailing List
<netfilter-devel@...ts.netfilter.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] xt_gateway match (iptables)
---
extensions/.gateway-test | 3
extensions/libipt_gateway.c | 157 ++++++++++++++++++++++++++++++++++++++++++
extensions/libipt_gateway.man | 9 ++
3 files changed, 169 insertions(+)
Index: iptables/extensions/.gateway-test
===================================================================
--- /dev/null
+++ iptables/extensions/.gateway-test
@@ -0,0 +1,3 @@
+#!/bin/sh
+# True if gateway match patch is applied.
+[ -f "$KERNEL_DIR/include/linux/netfilter/xt_gateway.h" ] && echo gateway
Index: iptables/extensions/libipt_gateway.c
===================================================================
--- /dev/null
+++ iptables/extensions/libipt_gateway.c
@@ -0,0 +1,157 @@
+/*
+ * Shared library add-on to iptables to add gateway IP address matching support.
+ * Based on iprange
+ * (C) UFO Mechanic <azez@...mechanic.net>
+ * © Jan Engelhardt <jengelh@....de>, 2007
+ */
+#include <stdio.h>
+#include <netdb.h>
+#include <string.h>
+#include <stdlib.h>
+#include <getopt.h>
+
+#include <iptables.h>
+#include <linux/netfilter/xt_gateway.h>
+
+/* Function which prints out usage message. */
+static void help(void)
+{
+ printf(
+"gateway match v%s options:\n"
+"[!] --gateway ip Match IP address of routed gateway\n"
+"[!] --nexthop ip Match IP address of next hop\n"
+"\n",
+IPTABLES_VERSION);
+}
+
+static struct option opts[] = {
+ {"gateway", 1, NULL, '1'},
+ {"nexthop", 1, NULL, '2'},
+ {NULL},
+};
+
+/*
+ * Function which parses command options;
+ * returns true if it ate an option.
+ */
+static int parse(int c, char **argv, int invert, unsigned int *flags,
+ const struct ipt_entry *entry, unsigned int *nfcache,
+ struct ipt_entry_match **match)
+{
+ struct xt_gateway_info *info = (void *)(*match)->data;
+ struct in_addr *ip;
+
+ switch (c) {
+ case '1':
+ if (*flags)
+ exit_error(PARAMETER_PROBLEM, "gateway match: You "
+ "cannot specify both \"--gateway\" and "
+ "\"--nexthop\"");
+
+ check_inverse(optarg, &invert, &optind, 0);
+ if (invert)
+ info->flags |= XT_GATEWAY_INV;
+
+ ip = dotted_to_addr(optarg);
+ if (!ip)
+ exit_error(PARAMETER_PROBLEM, "gateway match: Bad IP "
+ "address \"%s\"\n", optarg);
+
+ info->gateway = ip->s_addr;
+ info->flags |= XT_GATEWAY_ROUTE;
+ *flags = 1;
+ break;
+
+ case '2':
+ if (*flags)
+ exit_error(PARAMETER_PROBLEM, "gateway match: You "
+ "cannot specify both \"--gateway\" and "
+ "\"--nexthop\"");
+
+ check_inverse(optarg, &invert, &optind, 0);
+ if (invert)
+ info->flags |= XT_GATEWAY_INV;
+
+ ip = dotted_to_addr(optarg);
+ if (!ip)
+ exit_error(PARAMETER_PROBLEM,
+ "gateway match: Bad IP address `%s'\n", optarg);
+
+ info->gateway = ip->s_addr;
+ info->flags &= XT_GATEWAY_ROUTE;
+ *flags = 1;
+ break;
+
+ default:
+ return 0;
+ }
+
+ return 1;
+}
+
+/* Final check; must have specified --gateway */
+static void final_check(unsigned int flags)
+{
+ if (!flags)
+ exit_error(PARAMETER_PROBLEM,
+ "gateway match: You must specify `--gateway' "
+ "or `--nexthop'");
+}
+
+/* Prints out the info. */
+static void print(const struct ipt_ip *ip, const struct ipt_entry_match *match,
+ int numeric)
+{
+ const struct xt_gateway_info *info = (const void *)match->data;
+ struct in_addr a;
+
+ a.s_addr = info->gateway;
+
+ if (info->flags & XT_GATEWAY_ROUTE)
+ printf("gateway ");
+ else
+ printf("nexthop ");
+
+ if (info->flags & XT_GATEWAY_INV)
+ printf("! ");
+
+ printf("%s", addr_to_dotted(&a));
+}
+
+/* Saves the union ipt_info in parsable form to stdout. */
+static void save(const struct ipt_ip *ip, const struct ipt_entry_match *match)
+{
+ const struct xt_gateway_info *info = (const void *)match->data;
+ struct in_addr a;
+
+ a.s_addr = info->gateway;
+
+ if (info->flags & XT_GATEWAY_INV)
+ printf("! ");
+
+ if (info->flags & XT_GATEWAY_ROUTE)
+ printf("--gateway ");
+ else
+ printf("--nexthop ");
+
+ printf("%s ", addr_to_dotted(&a));
+}
+
+static struct iptables_match gateway = {
+ .next = NULL,
+ .name = "gateway",
+ .version = IPTABLES_VERSION,
+ .size = IPT_ALIGN(sizeof(struct xt_gateway_info)),
+ .userspacesize = IPT_ALIGN(sizeof(struct xt_gateway_info)),
+ .help = &help,
+ .parse = &parse,
+ .final_check = &final_check,
+ .print = &print,
+ .save = &save,
+ .extra_opts = opts
+};
+
+static __attribute__((constructor)) void libipt_gateway_init(void)
+{
+ register_match(&gateway);
+}
Index: iptables/extensions/libipt_gateway.man
===================================================================
--- /dev/null
+++ iptables/extensions/libipt_gateway.man
@@ -0,0 +1,9 @@
+This matches the gateway by IP address on routed packets.
+It does not mach packets that are not routed, or which
+are directly addresses to the gateway.
+.TP
+.BI "[!]" "--gateway " "ip"
+Check that the packet is routed to a gateway with the specified ip address.
+.BI "[!]" "--nexthop " "ip"
+Check if the packet is being directed to the specified ip address
+either directly or as a route.
-
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