Marc Boucher's TCPMSS patch.

1 files changed, 118 insertions, 0 deletions

diff --git a/extensions/libipt_TCPMSS.c b/extensions/libipt_TCPMSS.c
new file mode 100644
index 0000000..db8757b
--- /dev/null
+++ b/extensions/libipt_TCPMSS.c
@@ -0,0 +1,118 @@
+/* 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 <iptables.h>
+#include <linux/netfilter_ipv4/ip_tables.h>
+#include <linux/netfilter_ipv4/ipt_TCPMSS.h>
+
+struct mssinfo {
+	struct ipt_entry_target t;
+	struct ipt_tcpmss_info mss;
+};
+
+/* Function which prints out usage message. */
+static void
+help(void)
+{
+	printf(
+"TCPMSS target v%s options:\n"
+"  --set-mss value                   Value to set MSS option to\n",
+NETFILTER_VERSION);
+}
+
+static struct option opts[] = {
+	{ "set-mss", 1, 0, '1' },
+	{ 0 }
+};
+
+/* Initialize the target. */
+static void
+init(struct ipt_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 struct ipt_entry *entry,
+      struct ipt_entry_target **target)
+{
+	struct ipt_tcpmss_info *mssinfo
+		= (struct ipt_tcpmss_info *)(*target)->data;
+
+	switch (c) {
+		int mssval;
+
+	case '1':
+		if (*flags)
+			exit_error(PARAMETER_PROBLEM,
+			           "TCPMSS target: Can't specify --set-mss twice");
+		if ((mssval = string_to_number(optarg, 0, 65535)) == -1)
+			exit_error(PARAMETER_PROBLEM, "Bad TCPMSS value `%s'", optarg);
+		
+		mssinfo->mss = mssval;
+		*flags = 1;
+		break;
+
+	default:
+		return 0;
+	}
+
+	return 1;
+}
+
+static void
+final_check(unsigned int flags)
+{
+	if (!flags)
+		exit_error(PARAMETER_PROBLEM,
+		           "TCPMSS target: Parameter --set-mss is required");
+}
+
+/* Prints out the targinfo. */
+static void
+print(const struct ipt_ip *ip,
+      const struct ipt_entry_target *target,
+      int numeric)
+{
+	const struct ipt_tcpmss_info *mssinfo =
+		(const struct ipt_tcpmss_info *)target->data;
+	printf("TCPMSS set %u ", mssinfo->mss);
+}
+
+/* Saves the union ipt_targinfo in parsable form to stdout. */
+static void
+save(const struct ipt_ip *ip, const struct ipt_entry_target *target)
+{
+	const struct ipt_tcpmss_info *mssinfo =
+		(const struct ipt_tcpmss_info *)target->data;
+
+	printf("--set-mss %u ", mssinfo->mss);
+}
+
+struct iptables_target mss
+= { NULL,
+    "TCPMSS",
+    NETFILTER_VERSION,
+    IPT_ALIGN(sizeof(struct ipt_tcpmss_info)),
+    IPT_ALIGN(sizeof(struct ipt_tcpmss_info)),
+    &help,
+    &init,
+    &parse,
+    &final_check,
+    &print,
+    &save,
+    opts
+};
+
+void _init(void)
+{
+	register_target(&mss);
+}