From 45e4c6946426785d30733701d1ee8112e58538a4 Mon Sep 17 00:00:00 2001
From: Yasuyuki KOZAKAI <yasuyuki@netfilter.org>
Date: Tue, 24 Jul 2007 07:22:24 +0000
Subject: Unifies libip[6]t_TCPMSS.c into libxt_TCPMSS.c

---
 extensions/libxt_TCPMSS.c | 178 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 178 insertions(+)
 create mode 100644 extensions/libxt_TCPMSS.c

(limited to 'extensions/libxt_TCPMSS.c')

diff --git a/extensions/libxt_TCPMSS.c b/extensions/libxt_TCPMSS.c
new file mode 100644
index 00000000..d5b6c1f0
--- /dev/null
+++ b/extensions/libxt_TCPMSS.c
@@ -0,0 +1,178 @@
+/* Shared library add-on to iptables to add TCPMSS target support.
+ *
+ * Copyright (c) 2000 Marc Boucher
+*/
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <getopt.h>
+
+#include <xtables.h>
+#include <linux/netfilter/x_tables.h>
+#include <linux/netfilter/xt_TCPMSS.h>
+
+struct mssinfo {
+	struct xt_entry_target t;
+	struct xt_tcpmss_info mss;
+};
+
+/* Function which prints out usage message. */
+static void __help(int hdrsize)
+{
+	printf(
+"TCPMSS target v%s mutually-exclusive options:\n"
+"  --set-mss value               explicitly set MSS option to specified value\n"
+"  --clamp-mss-to-pmtu           automatically clamp MSS value to (path_MTU - %d)\n",
+IPTABLES_VERSION, hdrsize);
+}
+
+static void help(void)
+{
+	__help(40);
+}
+
+static void help6(void)
+{
+	__help(60);
+}
+
+static struct option opts[] = {
+	{ "set-mss", 1, 0, '1' },
+	{ "clamp-mss-to-pmtu", 0, 0, '2' },
+	{ 0 }
+};
+
+/* Initialize the target. */
+static void
+init(struct xt_entry_target *t, unsigned int *nfcache)
+{
+}
+
+/* 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 void *entry,
+      struct xt_entry_target **target,
+      int hdrsize)
+{
+	struct xt_tcpmss_info *mssinfo
+		= (struct xt_tcpmss_info *)(*target)->data;
+
+	switch (c) {
+		unsigned int mssval;
+
+	case '1':
+		if (*flags)
+			exit_error(PARAMETER_PROBLEM,
+			           "TCPMSS target: Only one option may be specified");
+		if (string_to_number(optarg, 0, 65535 - hdrsize, &mssval) == -1)
+			exit_error(PARAMETER_PROBLEM, "Bad TCPMSS value `%s'", optarg);
+		
+		mssinfo->mss = mssval;
+		*flags = 1;
+		break;
+
+	case '2':
+		if (*flags)
+			exit_error(PARAMETER_PROBLEM,
+			           "TCPMSS target: Only one option may be specified");
+		mssinfo->mss = XT_TCPMSS_CLAMP_PMTU;
+		*flags = 1;
+		break;
+
+	default:
+		return 0;
+	}
+
+	return 1;
+}
+
+static int
+parse(int c, char **argv, int invert, unsigned int *flags,
+      const void *entry,
+      struct xt_entry_target **target)
+{
+	return __parse(c, argv, invert, flags, entry, target, 40);
+}
+
+static int
+parse6(int c, char **argv, int invert, unsigned int *flags,
+      const void *entry,
+      struct xt_entry_target **target)
+{
+	return __parse(c, argv, invert, flags, entry, target, 60);
+}
+
+static void
+final_check(unsigned int flags)
+{
+	if (!flags)
+		exit_error(PARAMETER_PROBLEM,
+		           "TCPMSS target: At least one parameter is required");
+}
+
+/* Prints out the targinfo. */
+static void
+print(const void *ip,
+      const struct xt_entry_target *target,
+      int numeric)
+{
+	const struct xt_tcpmss_info *mssinfo =
+		(const struct xt_tcpmss_info *)target->data;
+	if(mssinfo->mss == XT_TCPMSS_CLAMP_PMTU)
+		printf("TCPMSS clamp to PMTU ");
+	else
+		printf("TCPMSS set %u ", mssinfo->mss);
+}
+
+/* Saves the union ipt_targinfo in parsable form to stdout. */
+static void
+save(const void *ip, const struct xt_entry_target *target)
+{
+	const struct xt_tcpmss_info *mssinfo =
+		(const struct xt_tcpmss_info *)target->data;
+
+	if(mssinfo->mss == XT_TCPMSS_CLAMP_PMTU)
+		printf("--clamp-mss-to-pmtu ");
+	else
+		printf("--set-mss %u ", mssinfo->mss);
+}
+
+static struct xtables_target mss = {
+	.next		= NULL,
+	.family		= AF_INET,
+	.name		= "TCPMSS",
+	.version	= IPTABLES_VERSION,
+	.size		= XT_ALIGN(sizeof(struct xt_tcpmss_info)),
+	.userspacesize	= XT_ALIGN(sizeof(struct xt_tcpmss_info)),
+	.help		= &help,
+	.init		= &init,
+	.parse		= &parse,
+	.final_check	= &final_check,
+	.print		= &print,
+	.save		= &save,
+	.extra_opts	= opts
+};
+
+static struct xtables_target mss6 = {
+	.next		= NULL,
+	.family		= AF_INET6,
+	.name		= "TCPMSS",
+	.version	= IPTABLES_VERSION,
+	.size		= XT_ALIGN(sizeof(struct xt_tcpmss_info)),
+	.userspacesize	= XT_ALIGN(sizeof(struct xt_tcpmss_info)),
+	.help		= &help6,
+	.init		= &init,
+	.parse		= &parse6,
+	.final_check	= &final_check,
+	.print		= &print,
+	.save		= &save,
+	.extra_opts	= opts
+};
+
+void _init(void)
+{
+	xtables_register_target(&mss);
+	xtables_register_target(&mss6);
+}
-- 
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