libipt_REJECT.c revision 8caee8b9e34fed4562fcff553197c161fc9d9979
1/* Shared library add-on to iptables to add customized REJECT support. 2 * 3 * (C) 2000 Jozsef Kadlecsik <kadlec@blackhole.kfki.hu> 4 */ 5#include <stdio.h> 6#include <string.h> 7#include <stdlib.h> 8#include <getopt.h> 9#include <iptables.h> 10#include <linux/netfilter_ipv4/ip_tables.h> 11#include <linux/netfilter_ipv4/ipt_REJECT.h> 12#include <linux/version.h> 13 14/* If we are compiling against a kernel that does not support 15 * IPT_ICMP_ADMIN_PROHIBITED, we are emulating it. 16 * The result will be a plain DROP of the packet instead of 17 * reject. -- Maciej Soltysiak <solt@dns.toxicfilms.tv> 18 */ 19#ifndef IPT_ICMP_ADMIN_PROHIBITED 20#define IPT_ICMP_ADMIN_PROHIBITED IPT_TCP_RESET + 1 21#endif 22 23struct reject_names { 24 const char *name; 25 const char *alias; 26 enum ipt_reject_with with; 27 const char *desc; 28}; 29 30static const struct reject_names reject_table[] = { 31 {"icmp-net-unreachable", "net-unreach", 32 IPT_ICMP_NET_UNREACHABLE, "ICMP network unreachable"}, 33 {"icmp-host-unreachable", "host-unreach", 34 IPT_ICMP_HOST_UNREACHABLE, "ICMP host unreachable"}, 35 {"icmp-proto-unreachable", "proto-unreach", 36 IPT_ICMP_PROT_UNREACHABLE, "ICMP protocol unreachable"}, 37 {"icmp-port-unreachable", "port-unreach", 38 IPT_ICMP_PORT_UNREACHABLE, "ICMP port unreachable (default)"}, 39#if 0 40 {"echo-reply", "echoreply", 41 IPT_ICMP_ECHOREPLY, "for ICMP echo only: faked ICMP echo reply"}, 42#endif 43 {"icmp-net-prohibited", "net-prohib", 44 IPT_ICMP_NET_PROHIBITED, "ICMP network prohibited"}, 45 {"icmp-host-prohibited", "host-prohib", 46 IPT_ICMP_HOST_PROHIBITED, "ICMP host prohibited"}, 47 {"tcp-reset", "tcp-reset", 48 IPT_TCP_RESET, "TCP RST packet"}, 49 {"icmp-admin-prohibited", "admin-prohib", 50 IPT_ICMP_ADMIN_PROHIBITED, "ICMP administratively prohibited (*)"} 51}; 52 53static void 54print_reject_types() 55{ 56 unsigned int i; 57 58 printf("Valid reject types:\n"); 59 60 for (i = 0; i < sizeof(reject_table)/sizeof(struct reject_names); i++) { 61 printf(" %-25s\t%s\n", reject_table[i].name, reject_table[i].desc); 62 printf(" %-25s\talias\n", reject_table[i].alias); 63 } 64 printf("\n"); 65} 66 67/* Saves the union ipt_targinfo in parsable form to stdout. */ 68 69/* Function which prints out usage message. */ 70static void 71help(void) 72{ 73 printf( 74"REJECT options:\n" 75"--reject-with type drop input packet and send back\n" 76" a reply packet according to type:\n"); 77 78 print_reject_types(); 79 80 printf("(*) See man page or read the INCOMPATIBILITES file for compatibility issues.\n"); 81} 82 83static struct option opts[] = { 84 { "reject-with", 1, 0, '1' }, 85 { 0 } 86}; 87 88/* Allocate and initialize the target. */ 89static void 90init(struct ipt_entry_target *t, unsigned int *nfcache) 91{ 92 struct ipt_reject_info *reject = (struct ipt_reject_info *)t->data; 93 94 /* default */ 95 reject->with = IPT_ICMP_PORT_UNREACHABLE; 96 97 /* Can't cache this */ 98 *nfcache |= NFC_UNKNOWN; 99} 100 101/* Function which parses command options; returns true if it 102 ate an option */ 103static int 104parse(int c, char **argv, int invert, unsigned int *flags, 105 const struct ipt_entry *entry, 106 struct ipt_entry_target **target) 107{ 108 struct ipt_reject_info *reject = (struct ipt_reject_info *)(*target)->data; 109 unsigned int limit = sizeof(reject_table)/sizeof(struct reject_names); 110 unsigned int i; 111 112 switch(c) { 113 case '1': 114 if (check_inverse(optarg, &invert, NULL, 0)) 115 exit_error(PARAMETER_PROBLEM, 116 "Unexpected `!' after --reject-with"); 117 for (i = 0; i < limit; i++) { 118 if ((strncasecmp(reject_table[i].name, optarg, strlen(optarg)) == 0) 119 || (strncasecmp(reject_table[i].alias, optarg, strlen(optarg)) == 0)) { 120 reject->with = reject_table[i].with; 121 return 1; 122 } 123 } 124 /* This due to be dropped late in 2.4 pre-release cycle --RR */ 125 if (strncasecmp("echo-reply", optarg, strlen(optarg)) == 0 126 || strncasecmp("echoreply", optarg, strlen(optarg)) == 0) 127 fprintf(stderr, "--reject-with echo-reply no longer" 128 " supported\n"); 129 exit_error(PARAMETER_PROBLEM, "unknown reject type `%s'",optarg); 130 default: 131 /* Fall through */ 132 break; 133 } 134 return 0; 135} 136 137/* Final check; nothing. */ 138static void final_check(unsigned int flags) 139{ 140} 141 142/* Prints out ipt_reject_info. */ 143static void 144print(const struct ipt_ip *ip, 145 const struct ipt_entry_target *target, 146 int numeric) 147{ 148 const struct ipt_reject_info *reject 149 = (const struct ipt_reject_info *)target->data; 150 unsigned int i; 151 152 for (i = 0; i < sizeof(reject_table)/sizeof(struct reject_names); i++) { 153 if (reject_table[i].with == reject->with) 154 break; 155 } 156 printf("reject-with %s ", reject_table[i].name); 157} 158 159/* Saves ipt_reject in parsable form to stdout. */ 160static void save(const struct ipt_ip *ip, const struct ipt_entry_target *target) 161{ 162 const struct ipt_reject_info *reject 163 = (const struct ipt_reject_info *)target->data; 164 unsigned int i; 165 166 for (i = 0; i < sizeof(reject_table)/sizeof(struct reject_names); i++) 167 if (reject_table[i].with == reject->with) 168 break; 169 170 printf("--reject-with %s ", reject_table[i].name); 171} 172 173static struct iptables_target reject = { 174 .next = NULL, 175 .name = "REJECT", 176 .version = IPTABLES_VERSION, 177 .size = IPT_ALIGN(sizeof(struct ipt_reject_info)), 178 .userspacesize = IPT_ALIGN(sizeof(struct ipt_reject_info)), 179 .help = &help, 180 .init = &init, 181 .parse = &parse, 182 .final_check = &final_check, 183 .print = &print, 184 .save = &save, 185 .extra_opts = opts 186}; 187 188void _init(void) 189{ 190 register_target(&reject); 191} 192