extensions/libip6t_REJECT.c

   1 /* Shared library add-on to iptables to add customized REJECT support.
   2  *
   3  * (C) 2000 Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
   4  *
   5  * ported to IPv6 by Harald Welte <laforge@gnumonks.org>
   6  *
   7  */
   8 #include <stdio.h>
   9 #include <string.h>
  10 #include <stdlib.h>
  11 #include <getopt.h>
  12 #include <ip6tables.h>
  13 #include <linux/netfilter_ipv6/ip6_tables.h>
  14 #include <linux/netfilter_ipv6/ip6t_REJECT.h>
  15
  16 struct reject_names {
  17         const char *name;
  18         const char *alias;
  19         enum ip6t_reject_with with;
  20         const char *desc;
  21 };
  22
  23 static const struct reject_names reject_table[] = {
  24         {"icmp6-no-route", "no-route",
  25                 IP6T_ICMP6_NO_ROUTE, "ICMPv6 no route"},
  26         {"icmp6-adm-prohibited", "adm-prohibited",
  27                 IP6T_ICMP6_ADM_PROHIBITED, "ICMPv6 administratively prohibited"},
  28 #if 0
  29         {"icmp6-not-neighbor", "not-neighbor"},
  30                 IP6T_ICMP6_NOT_NEIGHBOR, "ICMPv6 not a neighbor"},
  31 #endif
  32         {"icmp6-addr-unreachable", "addr-unreach",
  33                 IP6T_ICMP6_ADDR_UNREACH, "ICMPv6 address unreachable"},
  34         {"icmp6-port-unreachable", "port-unreach",
  35                 IP6T_ICMP6_PORT_UNREACH, "ICMPv6 port unreachable"},
  36         {"tcp-reset", "tcp-reset",
  37                 IP6T_TCP_RESET, "TCP RST packet"}
  38 };
  39
  40 static void
  41 print_reject_types(void)
  42 {
  43         unsigned int i;
  44
  45         printf("Valid reject types:\n");
  46
  47         for (i = 0; i < sizeof(reject_table)/sizeof(struct reject_names); i++) {
  48                 printf("    %-25s\t%s\n", reject_table[i].name, reject_table[i].desc);
  49                 printf("    %-25s\talias\n", reject_table[i].alias);
  50         }
  51         printf("\n");
  52 }
  53
  54 /* Saves the union ipt_targinfo in parsable form to stdout. */
  55
  56 /* Function which prints out usage message. */
  57 static void REJECT_help(void)
  58 {
  59         printf(
  60 "REJECT target options:\n"
  61 "--reject-with type              drop input packet and send back\n"
  62 "                                a reply packet according to type:\n");
  63
  64         print_reject_types();
  65 }
  66
  67 static const struct option REJECT_opts[] = {
  68         { "reject-with", 1, NULL, '1' },
  69         { .name = NULL }
  70 };
  71
  72 /* Allocate and initialize the target. */
  73 static void REJECT_init(struct xt_entry_target *t)
  74 {
  75         struct ip6t_reject_info *reject = (struct ip6t_reject_info *)t->data;
  76
  77         /* default */
  78         reject->with = IP6T_ICMP6_PORT_UNREACH;
  79
  80 }
  81
  82 /* Function which parses command options; returns true if it
  83    ate an option */
  84 static int REJECT_parse(int c, char **argv, int invert, unsigned int *flags,
  85                         const void *entry, struct xt_entry_target **target)
  86 {
  87         struct ip6t_reject_info *reject =
  88                 (struct ip6t_reject_info *)(*target)->data;
  89         unsigned int limit = sizeof(reject_table)/sizeof(struct reject_names);
  90         unsigned int i;
  91
  92         switch(c) {
  93         case '1':
  94                 if (check_inverse(optarg, &invert, NULL, 0))
  95                         exit_error(PARAMETER_PROBLEM,
  96                                    "Unexpected `!' after --reject-with");
  97                 for (i = 0; i < limit; i++) {
  98                         if ((strncasecmp(reject_table[i].name, optarg, strlen(optarg)) == 0)
  99                             || (strncasecmp(reject_table[i].alias, optarg, strlen(optarg)) == 0)) {
 100                                 reject->with = reject_table[i].with;
 101                                 return 1;
 102                         }
 103                 }
 104                 exit_error(PARAMETER_PROBLEM, "unknown reject type `%s'",optarg);
 105         default:
 106                 /* Fall through */
 107                 break;
 108         }
 109         return 0;
 110 }
 111
 112 /* Prints out ipt_reject_info. */
 113 static void REJECT_print(const void *ip, const struct xt_entry_target *target,
 114                          int numeric)
 115 {
 116         const struct ip6t_reject_info *reject
 117                 = (const struct ip6t_reject_info *)target->data;
 118         unsigned int i;
 119
 120         for (i = 0; i < sizeof(reject_table)/sizeof(struct reject_names); i++) {
 121                 if (reject_table[i].with == reject->with)
 122                         break;
 123         }
 124         printf("reject-with %s ", reject_table[i].name);
 125 }
 126
 127 /* Saves ipt_reject in parsable form to stdout. */
 128 static void REJECT_save(const void *ip, const struct xt_entry_target *target)
 129 {
 130         const struct ip6t_reject_info *reject
 131                 = (const struct ip6t_reject_info *)target->data;
 132         unsigned int i;
 133
 134         for (i = 0; i < sizeof(reject_table)/sizeof(struct reject_names); i++)
 135                 if (reject_table[i].with == reject->with)
 136                         break;
 137
 138         printf("--reject-with %s ", reject_table[i].name);
 139 }
 140
 141 static struct xtables_target reject_tg6_reg = {
 142         .name = "REJECT",
 143         .version        = XTABLES_VERSION,
 144         .family         = PF_INET6,
 145         .size           = XT_ALIGN(sizeof(struct ip6t_reject_info)),
 146         .userspacesize  = XT_ALIGN(sizeof(struct ip6t_reject_info)),
 147         .help           = REJECT_help,
 148         .init           = REJECT_init,
 149         .parse          = REJECT_parse,
 150         .print          = REJECT_print,
 151         .save           = REJECT_save,
 152         .extra_opts     = REJECT_opts,
 153 };
 154
 155 void _init(void)
 156 {
 157         xtables_register_target(&reject_tg6_reg);
 158 }