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authorFabrice MARIE <fabrice@celestix.com>2001-10-15 15:38:55 +0000
committerHarald Welte <laforge@gnumonks.org>2001-10-15 15:38:55 +0000
commitcced2e496a974d333b394177d18f8d0b9506e12d (patch)
tree38da59f34b39c9f599ee2c5049d014e15f240161 /extensions
parent0612943cdad594e978e4b7fc5d6d098b09003da9 (diff)
added randmo match by Fabrice Maurie
Diffstat (limited to 'extensions')
-rwxr-xr-xextensions/.random-test3
-rw-r--r--extensions/libipt_random.c151
2 files changed, 154 insertions, 0 deletions
diff --git a/extensions/.random-test b/extensions/.random-test
new file mode 100755
index 00000000..7626722f
--- /dev/null
+++ b/extensions/.random-test
@@ -0,0 +1,3 @@
+#!/bin/sh
+# True if random is applied.
+[ -f $KERNEL_DIR/include/linux/netfilter_ipv4/ipt_random.h ] && echo random
diff --git a/extensions/libipt_random.c b/extensions/libipt_random.c
new file mode 100644
index 00000000..19859ebe
--- /dev/null
+++ b/extensions/libipt_random.c
@@ -0,0 +1,151 @@
+/*
+ Shared library add-on to iptables to add match support for random match.
+
+ This file is distributed under the terms of the GNU General Public
+ License (GPL). Copies of the GPL can be obtained from:
+ ftp://prep.ai.mit.edu/pub/gnu/GPL
+
+ 2001-10-14 Fabrice MARIE <fabrice@celestix.com> : initial development.
+*/
+
+#include <stdio.h>
+#include <netdb.h>
+#include <string.h>
+#include <stdlib.h>
+#include <syslog.h>
+#include <getopt.h>
+#include <iptables.h>
+#include <linux/netfilter_ipv4/ip_tables.h>
+#include <linux/netfilter_ipv4/ipt_random.h>
+
+/**
+ * The kernel random routing returns numbers between 0 and 255.
+ * To ease the task of the user in choosing the probability
+ * of matching, we want him to be able to use percentages.
+ * Therefore we have to accept numbers in percentage here,
+ * turn them into number between 0 and 255 for the kernel module,
+ * and turn them back to percentages when we print/save
+ * the rule.
+ */
+
+
+/* Function which prints out usage message. */
+static void
+help(void)
+{
+ printf(
+"random v%s options:\n"
+" [--average] percent The probability in percentage of the match\n"
+" If ommited, a probability of 50%% percent is set.\n"
+" Percentage must be within : 1 <= percent <= 99.\n\n",
+NETFILTER_VERSION);
+}
+
+static struct option opts[] = {
+ { "average", 1, 0, '1' },
+ { 0 }
+};
+
+/* Initialize the target. */
+static void
+init(struct ipt_entry_match *m, unsigned int *nfcache)
+{
+ struct ipt_rand_info *randinfo = (struct ipt_rand_info *)(m)->data;
+ *nfcache |= NFC_UNKNOWN;
+
+ /* We assign the average to be 50 which is our default value */
+ /* 50 * 2.55 = 128 */
+ randinfo->average = 128;
+}
+
+#define IPT_RAND_OPT_AVERAGE 0x01
+
+/* 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 ipt_rand_info *randinfo = (struct ipt_rand_info *)(*match)->data;
+ unsigned int num;
+
+ switch (c) {
+ case '1':
+ /* check for common mistakes... */
+ if (invert)
+ exit_error(PARAMETER_PROBLEM,
+ "Can't specify ! --average");
+ if (*flags & IPT_RAND_OPT_AVERAGE)
+ exit_error(PARAMETER_PROBLEM,
+ "Can't specify --average twice");
+
+ /* Remember, this function will interpret a leading 0 to be
+ Octal, a leading 0x to be hexdecimal... */
+ if (string_to_number(optarg, 1, 99, &num) == -1 || num < 1)
+ exit_error(PARAMETER_PROBLEM,
+ "bad --average `%s', must be between 1 and 99", optarg);
+
+ /* assign the values */
+ randinfo->average = (int)(num * 2.55);
+ *flags |= IPT_RAND_OPT_AVERAGE;
+ break;
+ default:
+ return 0;
+ }
+ return 1;
+}
+
+/* Final check; nothing. */
+static void final_check(unsigned int flags)
+{
+}
+
+/* Prints out the targinfo. */
+static void
+print(const struct ipt_ip *ip,
+ const struct ipt_entry_match *match,
+ int numeric)
+{
+ const struct ipt_rand_info *randinfo
+ = (const struct ipt_rand_info *)match->data;
+ div_t result = div((randinfo->average*100), 255);
+ if (result.rem > 127) /* round up... */
+ ++result.quot;
+
+ printf(" random %u%% ", result.quot);
+}
+
+/* Saves the union ipt_targinfo in parsable form to stdout. */
+static void
+save(const struct ipt_ip *ip, const struct ipt_entry_match *match)
+{
+ const struct ipt_rand_info *randinfo
+ = (const struct ipt_rand_info *)match->data;
+ div_t result = div((randinfo->average *100), 255);
+ if (result.rem > 127) /* round up... */
+ ++result.quot;
+
+ printf("--average %u ", result.quot);
+}
+
+struct iptables_match rand_match
+= { NULL,
+ "random",
+ NETFILTER_VERSION,
+ IPT_ALIGN(sizeof(struct ipt_rand_info)),
+ IPT_ALIGN(sizeof(struct ipt_rand_info)),
+ &help,
+ &init,
+ &parse,
+ &final_check,
+ &print,
+ &save,
+ opts
+};
+
+void _init(void)
+{
+ register_match(&rand_match);
+}