libipt_ttl.c revision 5f2922cfc0bbfbeb878f5c12e9fb3eb602ae5507
1/* Shared library add-on to iptables to add TTL matching support 2 * (C) 2000 by Harald Welte <laforge@gnumonks.org> 3 * 4 * $Id$ 5 * 6 * This program is released under the terms of GNU GPL */ 7 8#include <stdio.h> 9#include <stdlib.h> 10#include <string.h> 11#include <getopt.h> 12#include <xtables.h> 13 14#include <linux/netfilter_ipv4/ip_tables.h> 15#include <linux/netfilter_ipv4/ipt_ttl.h> 16 17static void ttl_help(void) 18{ 19 printf( 20"ttl match options:\n" 21" --ttl-eq value Match time to live value\n" 22" --ttl-lt value Match TTL < value\n" 23" --ttl-gt value Match TTL > value\n"); 24} 25 26static int ttl_parse(int c, char **argv, int invert, unsigned int *flags, 27 const void *entry, struct xt_entry_match **match) 28{ 29 struct ipt_ttl_info *info = (struct ipt_ttl_info *) (*match)->data; 30 unsigned int value; 31 32 check_inverse(optarg, &invert, &optind, 0); 33 34 switch (c) { 35 case '2': 36 if (!xtables_strtoui(optarg, NULL, &value, 0, UINT8_MAX)) 37 exit_error(PARAMETER_PROBLEM, 38 "ttl: Expected value between 0 and 255"); 39 40 if (invert) 41 info->mode = IPT_TTL_NE; 42 else 43 info->mode = IPT_TTL_EQ; 44 45 /* is 0 allowed? */ 46 info->ttl = value; 47 break; 48 case '3': 49 if (!xtables_strtoui(optarg, NULL, &value, 0, UINT8_MAX)) 50 exit_error(PARAMETER_PROBLEM, 51 "ttl: Expected value between 0 and 255"); 52 53 if (invert) 54 exit_error(PARAMETER_PROBLEM, 55 "ttl: unexpected `!'"); 56 57 info->mode = IPT_TTL_LT; 58 info->ttl = value; 59 break; 60 case '4': 61 if (!xtables_strtoui(optarg, NULL, &value, 0, UINT8_MAX)) 62 exit_error(PARAMETER_PROBLEM, 63 "ttl: Expected value between 0 and 255"); 64 65 if (invert) 66 exit_error(PARAMETER_PROBLEM, 67 "ttl: unexpected `!'"); 68 69 info->mode = IPT_TTL_GT; 70 info->ttl = value; 71 break; 72 default: 73 return 0; 74 75 } 76 77 if (*flags) 78 exit_error(PARAMETER_PROBLEM, 79 "Can't specify TTL option twice"); 80 *flags = 1; 81 82 return 1; 83} 84 85static void ttl_check(unsigned int flags) 86{ 87 if (!flags) 88 exit_error(PARAMETER_PROBLEM, 89 "TTL match: You must specify one of " 90 "`--ttl-eq', `--ttl-lt', `--ttl-gt"); 91} 92 93static void ttl_print(const void *ip, const struct xt_entry_match *match, 94 int numeric) 95{ 96 const struct ipt_ttl_info *info = 97 (struct ipt_ttl_info *) match->data; 98 99 printf("TTL match "); 100 switch (info->mode) { 101 case IPT_TTL_EQ: 102 printf("TTL == "); 103 break; 104 case IPT_TTL_NE: 105 printf("TTL != "); 106 break; 107 case IPT_TTL_LT: 108 printf("TTL < "); 109 break; 110 case IPT_TTL_GT: 111 printf("TTL > "); 112 break; 113 } 114 printf("%u ", info->ttl); 115} 116 117static void ttl_save(const void *ip, const struct xt_entry_match *match) 118{ 119 const struct ipt_ttl_info *info = 120 (struct ipt_ttl_info *) match->data; 121 122 switch (info->mode) { 123 case IPT_TTL_EQ: 124 printf("--ttl-eq "); 125 break; 126 case IPT_TTL_NE: 127 printf("! --ttl-eq "); 128 break; 129 case IPT_TTL_LT: 130 printf("--ttl-lt "); 131 break; 132 case IPT_TTL_GT: 133 printf("--ttl-gt "); 134 break; 135 default: 136 /* error */ 137 break; 138 } 139 printf("%u ", info->ttl); 140} 141 142static const struct option ttl_opts[] = { 143 { "ttl", 1, NULL, '2' }, 144 { "ttl-eq", 1, NULL, '2'}, 145 { "ttl-lt", 1, NULL, '3'}, 146 { "ttl-gt", 1, NULL, '4'}, 147 { .name = NULL } 148}; 149 150static struct xtables_match ttl_mt_reg = { 151 .name = "ttl", 152 .version = XTABLES_VERSION, 153 .family = NFPROTO_IPV4, 154 .size = XT_ALIGN(sizeof(struct ipt_ttl_info)), 155 .userspacesize = XT_ALIGN(sizeof(struct ipt_ttl_info)), 156 .help = ttl_help, 157 .parse = ttl_parse, 158 .final_check = ttl_check, 159 .print = ttl_print, 160 .save = ttl_save, 161 .extra_opts = ttl_opts, 162}; 163 164 165void _init(void) 166{ 167 xtables_register_match(&ttl_mt_reg); 168} 169