From b7722f29b7d1e376bc758d25aa5a9e1cd94b2d51 Mon Sep 17 00:00:00 2001 From: Harald Welte Date: Sat, 21 Jul 2001 14:42:43 +0000 Subject: added n'th packet match to patch-o-matic --- extensions/.nth-test | 3 + extensions/libipt_nth.c | 179 ++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 182 insertions(+) create mode 100755 extensions/.nth-test create mode 100644 extensions/libipt_nth.c diff --git a/extensions/.nth-test b/extensions/.nth-test new file mode 100755 index 00000000..536da95d --- /dev/null +++ b/extensions/.nth-test @@ -0,0 +1,3 @@ +#!/bin/sh +# True if nth is applied. +[ -f $KERNEL_DIR/include/linux/netfilter_ipv4/ipt_nth.h ] && echo nth diff --git a/extensions/libipt_nth.c b/extensions/libipt_nth.c new file mode 100644 index 00000000..5fdd3625 --- /dev/null +++ b/extensions/libipt_nth.c @@ -0,0 +1,179 @@ +/* + Shared library add-on to iptables to add match support for every Nth packet + + 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 + + 2001-07-17 Fabrice MARIE : initial development. +*/ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + + +/* Function which prints out usage message. */ +static void +help(void) +{ + printf( +"nth v%s options:\n" +" --every Nth Match every Nth packet.\n\n", +" [--start] counter Initialize the counter at the number 'counter'\n" +" instead of 0. Must be of the form :\n" +" 0 <= counter <= (nth-1)" +" Example if nth=2 : 0 <= counter <= 1\n\n" +NETFILTER_VERSION); +} + +static struct option opts[] = { + { "every", 1, 0, '1' }, + { "start", 1, 0, '2' }, + { 0 } +}; + +/* Initialize the target. */ +static void +init(struct ipt_entry_match *m, unsigned int *nfcache) +{ + *nfcache |= NFC_UNKNOWN; +} + +#define IPT_NTH_OPT_EVERY 0x01 +#define IPT_NTH_OPT_NOT_EVERY 0x02 +#define IPT_NTH_OPT_START 0x04 + +/* 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_nth_info *nthinfo = (struct ipt_nth_info *)(*match)->data; + int num; + + switch (c) { + case '1': + /* check for common mistakes... */ + if ((!invert) && (*flags & IPT_NTH_OPT_EVERY)) + exit_error(PARAMETER_PROBLEM, + "Can't specify --every twice"); + if (invert && (*flags & IPT_NTH_OPT_NOT_EVERY)) + exit_error(PARAMETER_PROBLEM, + "Can't specify ! --every twice"); + if ((!invert) && (*flags & IPT_NTH_OPT_NOT_EVERY)) + exit_error(PARAMETER_PROBLEM, + "Can't specify --every with ! --every"); + if (invert && (*flags & IPT_NTH_OPT_EVERY)) + exit_error(PARAMETER_PROBLEM, + "Can't specify ! --every with --every"); + + /* Remember, this function will interpret a leading 0 to be + Octal, a leading 0x to be hexdecimal... */ + num = string_to_number(optarg, 2, 100); + if (num < 2) + exit_error(PARAMETER_PROBLEM, + "bad --every `%s', must be between 2 and 100", optarg); + + /* assign the values */ + nthinfo->every = num-1; + nthinfo->startat = 0; + if (invert) + { + *flags |= IPT_NTH_OPT_NOT_EVERY; + nthinfo->not = 1; + } + else + { + *flags |= IPT_NTH_OPT_EVERY; + nthinfo->not = 0; + } + break; + case '2': + /* check for common mistakes... */ + if (!((*flags & IPT_NTH_OPT_EVERY) || + (*flags & IPT_NTH_OPT_NOT_EVERY))) + exit_error(PARAMETER_PROBLEM, + "Can't specify --start before --every"); + if (invert) + exit_error(PARAMETER_PROBLEM, + "Can't specify with ! --start"); + if (*flags & IPT_NTH_OPT_START) + exit_error(PARAMETER_PROBLEM, + "Can't specify --start twice"); + num = string_to_number(optarg, 0, nthinfo->every); + if (num < 0) + exit_error(PARAMETER_PROBLEM, + "bad --start `%s', must between 0 and %u", optarg, nthinfo->every); + *flags |= IPT_NTH_OPT_START; + nthinfo->startat = num; + 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_nth_info *nthinfo + = (const struct ipt_nth_info *)match->data; + + if (nthinfo->not == 1) + printf(" !"); + printf("every %uth ", (nthinfo->every +1)); + if (nthinfo->startat != 0) + printf(" start at %u ", nthinfo->startat); +} + +/* 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_nth_info *nthinfo + = (const struct ipt_nth_info *)match->data; + + if (nthinfo->not == 1) + printf("! "); + printf("--every %u ", (nthinfo->every +1)); + if (nthinfo->startat != 0) + printf(" --start %u", nthinfo->startat ); +} + +struct iptables_match nth += { NULL, + "nth", + NETFILTER_VERSION, + IPT_ALIGN(sizeof(struct ipt_nth_info)), + IPT_ALIGN(sizeof(struct ipt_nth_info)), + &help, + &init, + &parse, + &final_check, + &print, + &save, + opts +}; + +void _init(void) +{ + register_match(&nth); +} -- cgit v1.2.3