add ECN match plugin

1 files changed, 187 insertions, 0 deletions

diff --git a/extensions/libipt_ecn.c b/extensions/libipt_ecn.c
new file mode 100644
index 00000000..7dcee2c8
--- /dev/null
+++ b/extensions/libipt_ecn.c
@@ -0,0 +1,187 @@
+/* Shared library add-on to iptables for ECN matching
+ *
+ * (C) 2002 by Harald Welte <laforge@gnumonks.org>
+ *
+ * This program is distributed under the terms of GNU GPL v2, 1991
+ *
+ * libipt_ecn.c borrowed heavily from libipt_dscp.c
+ *
+ */
+#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_ecn.h>
+
+static void init(struct ipt_entry_match *m, unsigned int *nfcache) 
+{
+	*nfcache |= NFC_IP_TOS;
+}
+
+static void help(void) 
+{
+	printf(
+"ECN match v%s options\n"
+"[!] --ecn-tcp-cwr 		Match CWR bit of TCP header\n"
+"[!] --ecn-tcp-ece		Match ECE bit of TCP header\n"
+"[!] --ecn-ip-ect [0..3]	Match ECN codepoint in IPv4 header\n",
+	IPTABLES_VERSION);
+}
+
+static struct option opts[] = {
+	{ "ecn-tcp-cwr", 0, 0, 'F' },
+	{ "ecn-tcp-ece", 0, 0, 'G' },
+	{ "ecn-ip-ect", 1, 0, 'H' },
+	{ 0 }
+};
+
+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)
+{
+	unsigned int result;
+	struct ipt_ecn_info *einfo
+		= (struct ipt_ecn_info *)(*match)->data;
+
+	switch (c) {
+	case 'F':
+		if (*flags & IPT_ECN_OP_MATCH_CWR)
+			exit_error(PARAMETER_PROBLEM,
+			           "ECN match: can only use parameter ONCE!");
+		check_inverse(optarg, &invert, &optind, 0);
+		einfo->operation |= IPT_ECN_OP_MATCH_CWR;
+		if (invert)
+			einfo->invert |= IPT_ECN_OP_MATCH_CWR;
+		*flags |= IPT_ECN_OP_MATCH_CWR;
+		break;
+
+	case 'G':
+		if (*flags & IPT_ECN_OP_MATCH_ECE)
+			exit_error(PARAMETER_PROBLEM,
+				   "ECN match: can only use parameter ONCE!");
+		check_inverse(optarg, &invert, &optind, 0);
+		einfo->operation |= IPT_ECN_OP_MATCH_ECE;
+		if (invert)
+			einfo->invert |= IPT_ECN_OP_MATCH_ECE;
+		*flags |= IPT_ECN_OP_MATCH_ECE;
+		break;
+
+	case 'H':
+		if (*flags & IPT_ECN_OP_MATCH_IP)
+			exit_error(PARAMETER_PROBLEM,
+				   "ECN match: can only use parameter ONCE!");
+		check_inverse(optarg, &invert, &optind, 0);
+		if (invert)
+			einfo->invert |= IPT_ECN_OP_MATCH_IP;
+		*flags |= IPT_ECN_OP_MATCH_IP;
+		einfo->operation |= IPT_ECN_OP_MATCH_IP;
+		if (string_to_number(optarg, 0, 3, &result))
+			exit_error(PARAMETER_PROBLEM,
+				   "ECN match: Value out of range");
+		einfo->ip_ect = result;
+		break;
+	default:
+		return 0;
+	}
+
+	return 1;
+}
+
+static void
+final_check(unsigned int flags)
+{
+	if (!flags)
+		exit_error(PARAMETER_PROBLEM,
+		           "ECN match: some option required");
+}
+
+static void
+print_dscp(u_int8_t dscp, int invert, int numeric)
+{
+	if (invert)
+		fputc('!', stdout);
+
+ 	printf("0x%02x ", dscp);
+}
+
+/* Prints out the matchinfo. */
+static void
+print(const struct ipt_ip *ip,
+      const struct ipt_entry_match *match,
+      int numeric)
+{
+	const struct ipt_ecn_info *einfo =
+		(const struct ipt_ecn_info *)match->data;
+
+	printf("ECN match ");
+
+	if (einfo->operation & IPT_ECN_OP_MATCH_ECE) {
+		if (einfo->invert & IPT_ECN_OP_MATCH_ECE)
+			fputc('!', stdout);
+		printf("ECE ");
+	}
+
+	if (einfo->operation & IPT_ECN_OP_MATCH_CWR) {
+		if (einfo->invert & IPT_ECN_OP_MATCH_CWR)
+			fputc('!', stdout);
+		printf("CWR ");
+	}
+
+	if (einfo->operation & IPT_ECN_OP_MATCH_IP) {
+		if (einfo->invert & IPT_ECN_OP_MATCH_IP)
+			fputc('!', stdout);
+		printf("ECT=%d ", einfo->ip_ect);
+	}
+}
+
+/* Saves the union ipt_matchinfo in parsable form to stdout. */
+static void
+save(const struct ipt_ip *ip, const struct ipt_entry_match *match)
+{
+	const struct ipt_ecn_info *einfo =
+		(const struct ipt_ecn_info *)match->data;
+	
+	if (einfo->operation & IPT_ECN_OP_MATCH_ECE) {
+		if (einfo->invert & IPT_ECN_OP_MATCH_ECE)
+			printf("! ");
+		printf("--ecn-tcp-ece ");
+	}
+
+	if (einfo->operation & IPT_ECN_OP_MATCH_CWR) {
+		if (einfo->invert & IPT_ECN_OP_MATCH_CWR)
+			printf("! ");
+		printf("--ecn-tcp-cwr ");
+	}
+
+	if (einfo->operation & IPT_ECN_OP_MATCH_IP) {
+		if (einfo->invert & IPT_ECN_OP_MATCH_IP)
+			printf("! ");
+		printf("--ecn-ip-ect %d", einfo->ip_ect);
+	}
+}
+
+static
+struct iptables_match ecn
+= { NULL,
+    "ecn",
+    IPTABLES_VERSION,
+    IPT_ALIGN(sizeof(struct ipt_ecn_info)),
+    IPT_ALIGN(sizeof(struct ipt_ecn_info)),
+    &help,
+    &init,
+    &parse,
+    &final_check,
+    &print,
+    &save,
+    opts
+};
+
+void _init(void)
+{
+	register_match(&ecn);
+}