extensions/libipt_ROUTE.c

   1 /* Shared library add-on to iptables to add ROUTE target support.
   2  * Author : Cedric de Launois, <delaunois@info.ucl.ac.be>
   3  * v 1.11 2004/11/23
   4  */
   5
   6 #include <stdio.h>
   7 #include <string.h>
   8 #include <stdlib.h>
   9 #include <getopt.h>
  10 #include <iptables.h>
  11 #include <net/if.h>
  12 #include <sys/socket.h>
  13 #include <netinet/in.h>
  14 #include <arpa/inet.h>
  15 #include <linux/netfilter_ipv4/ip_tables.h>
  16 #include <linux/netfilter_ipv4/ipt_ROUTE.h>
  17
  18 /* compile IPT_ROUTE_TEE support even if kernel headers are unpatched */
  19 #ifndef IPT_ROUTE_TEE
  20 #define IPT_ROUTE_TEE           0x02
  21 #endif
  22
  23 /* Function which prints out usage message. */
  24 static void
  25 help(void)
  26 {
  27         printf(
  28 "ROUTE target v%s options:\n"
  29 "    --oif   \tifname \t\tRoute packet through `ifname' network interface\n"
  30 "    --iif   \tifname \t\tChange packet's incoming interface to `ifname'\n"
  31 "    --gw    \tip     \t\tRoute packet via this gateway `ip'\n"
  32 "    --continue\t     \t\tRoute packet and continue traversing the\n"
  33 "            \t       \t\trules. Not valid with --iif or --tee.\n"
  34 "    --tee\t  \t\tDuplicate packet, route the duplicate,\n"
  35 "            \t       \t\tcontinue traversing with original packet.\n"
  36 "            \t       \t\tNot valid with --iif or --continue.\n"
  37 "\n",
  38 "1.11");
  39 }
  40
  41 static struct option opts[] = {
  42         { "oif", 1, 0, '1' },
  43         { "iif", 1, 0, '2' },
  44         { "gw", 1, 0, '3' },
  45         { "continue", 0, 0, '4' },
  46         { "tee", 0, 0, '5' },
  47         { 0 }
  48 };
  49
  50 /* Initialize the target. */
  51 static void
  52 init(struct ipt_entry_target *t, unsigned int *nfcache)
  53 {
  54         struct ipt_route_target_info *route_info =
  55                 (struct ipt_route_target_info*)t->data;
  56
  57         route_info->oif[0] = '\0';
  58         route_info->iif[0] = '\0';
  59         route_info->gw = 0;
  60         route_info->flags = 0;
  61 }
  62
  63
  64 #define IPT_ROUTE_OPT_OIF      0x01
  65 #define IPT_ROUTE_OPT_IIF      0x02
  66 #define IPT_ROUTE_OPT_GW       0x04
  67 #define IPT_ROUTE_OPT_CONTINUE 0x08
  68 #define IPT_ROUTE_OPT_TEE      0x10
  69
  70 /* Function which parses command options; returns true if it
  71    ate an option */
  72 static int
  73 parse(int c, char **argv, int invert, unsigned int *flags,
  74       const struct ipt_entry *entry,
  75       struct ipt_entry_target **target)
  76 {
  77         struct ipt_route_target_info *route_info =
  78                 (struct ipt_route_target_info*)(*target)->data;
  79
  80         switch (c) {
  81         case '1':
  82                 if (*flags & IPT_ROUTE_OPT_OIF)
  83                         exit_error(PARAMETER_PROBLEM,
  84                                    "Can't specify --oif twice");
  85
  86                 if (*flags & IPT_ROUTE_OPT_IIF)
  87                         exit_error(PARAMETER_PROBLEM,
  88                                    "Can't use --oif and --iif together");
  89
  90                 if (check_inverse(optarg, &invert, NULL, 0))
  91                         exit_error(PARAMETER_PROBLEM,
  92                                    "Unexpected `!' after --oif");
  93
  94                 if (strlen(optarg) > sizeof(route_info->oif) - 1)
  95                         exit_error(PARAMETER_PROBLEM,
  96                                    "Maximum interface name length %u",
  97                                    sizeof(route_info->oif) - 1);
  98
  99                 strcpy(route_info->oif, optarg);
 100                 *flags |= IPT_ROUTE_OPT_OIF;
 101                 break;
 102
 103         case '2':
 104                 if (*flags & IPT_ROUTE_OPT_IIF)
 105                         exit_error(PARAMETER_PROBLEM,
 106                                    "Can't specify --iif twice");
 107
 108                 if (*flags & IPT_ROUTE_OPT_OIF)
 109                         exit_error(PARAMETER_PROBLEM,
 110                                    "Can't use --iif and --oif together");
 111
 112                 if (check_inverse(optarg, &invert, NULL, 0))
 113                         exit_error(PARAMETER_PROBLEM,
 114                                    "Unexpected `!' after --iif");
 115
 116                 if (strlen(optarg) > sizeof(route_info->iif) - 1)
 117                         exit_error(PARAMETER_PROBLEM,
 118                                    "Maximum interface name length %u",
 119                                    sizeof(route_info->iif) - 1);
 120
 121                 strcpy(route_info->iif, optarg);
 122                 *flags |= IPT_ROUTE_OPT_IIF;
 123                 break;
 124
 125         case '3':
 126                 if (*flags & IPT_ROUTE_OPT_GW)
 127                         exit_error(PARAMETER_PROBLEM,
 128                                    "Can't specify --gw twice");
 129
 130                 if (check_inverse(optarg, &invert, NULL, 0))
 131                         exit_error(PARAMETER_PROBLEM,
 132                                    "Unexpected `!' after --gw");
 133
 134                 if (!inet_aton(optarg, (struct in_addr*)&route_info->gw)) {
 135                         exit_error(PARAMETER_PROBLEM,
 136                                    "Invalid IP address %s",
 137                                    optarg);
 138                 }
 139
 140                 *flags |= IPT_ROUTE_OPT_GW;
 141                 break;
 142
 143         case '4':
 144                 if (*flags & IPT_ROUTE_OPT_CONTINUE)
 145                         exit_error(PARAMETER_PROBLEM,
 146                                    "Can't specify --continue twice");
 147                 if (*flags & IPT_ROUTE_OPT_TEE)
 148                         exit_error(PARAMETER_PROBLEM,
 149                                    "Can't specify --continue AND --tee");
 150
 151                 route_info->flags |= IPT_ROUTE_CONTINUE;
 152                 *flags |= IPT_ROUTE_OPT_CONTINUE;
 153
 154                 break;
 155
 156         case '5':
 157                 if (*flags & IPT_ROUTE_OPT_TEE)
 158                         exit_error(PARAMETER_PROBLEM,
 159                                    "Can't specify --tee twice");
 160                 if (*flags & IPT_ROUTE_OPT_CONTINUE)
 161                         exit_error(PARAMETER_PROBLEM,
 162                                    "Can't specify --tee AND --continue");
 163
 164                 route_info->flags |= IPT_ROUTE_TEE;
 165                 *flags |= IPT_ROUTE_OPT_TEE;
 166
 167                 break;
 168
 169         default:
 170                 return 0;
 171         }
 172
 173         return 1;
 174 }
 175
 176
 177 static void
 178 final_check(unsigned int flags)
 179 {
 180         if (!flags)
 181                 exit_error(PARAMETER_PROBLEM,
 182                            "ROUTE target: oif, iif or gw option required");
 183
 184         if ((flags & (IPT_ROUTE_OPT_CONTINUE|IPT_ROUTE_OPT_TEE)) && (flags & IPT_ROUTE_OPT_IIF))
 185                 exit_error(PARAMETER_PROBLEM,
 186                            "ROUTE target: can't continue traversing the rules with iif option");
 187 }
 188
 189
 190 /* Prints out the targinfo. */
 191 static void
 192 print(const struct ipt_ip *ip,
 193       const struct ipt_entry_target *target,
 194       int numeric)
 195 {
 196         const struct ipt_route_target_info *route_info
 197                 = (const struct ipt_route_target_info *)target->data;
 198
 199         printf("ROUTE ");
 200
 201         if (route_info->oif[0])
 202                 printf("oif:%s ", route_info->oif);
 203
 204         if (route_info->iif[0])
 205                 printf("iif:%s ", route_info->iif);
 206
 207         if (route_info->gw) {
 208                 struct in_addr ip = { route_info->gw };
 209                 printf("gw:%s ", inet_ntoa(ip));
 210         }
 211
 212         if (route_info->flags & IPT_ROUTE_CONTINUE)
 213                 printf("continue");
 214
 215         if (route_info->flags & IPT_ROUTE_TEE)
 216                 printf("tee");
 217
 218 }
 219
 220
 221 static void save(const struct ipt_ip *ip,
 222                  const struct ipt_entry_target *target)
 223 {
 224         const struct ipt_route_target_info *route_info
 225                 = (const struct ipt_route_target_info *)target->data;
 226
 227         if (route_info->oif[0])
 228                 printf("--oif %s ", route_info->oif);
 229
 230         if (route_info->iif[0])
 231                 printf("--iif %s ", route_info->iif);
 232
 233         if (route_info->gw) {
 234                 struct in_addr ip = { route_info->gw };
 235                 printf("--gw %s ", inet_ntoa(ip));
 236         }
 237
 238         if (route_info->flags & IPT_ROUTE_CONTINUE)
 239                 printf("--continue ");
 240
 241         if (route_info->flags & IPT_ROUTE_TEE)
 242                 printf("--tee ");
 243 }
 244
 245
 246 static struct iptables_target route = {
 247         .next           = NULL,
 248         .name           = "ROUTE",
 249         .version        = IPTABLES_VERSION,
 250         .size           = IPT_ALIGN(sizeof(struct ipt_route_target_info)),
 251         .userspacesize  = IPT_ALIGN(sizeof(struct ipt_route_target_info)),
 252         .help           = &help,
 253         .init           = &init,
 254         .parse          = &parse,
 255         .final_check    = &final_check,
 256         .print          = &print,
 257         .save           = &save,
 258         .extra_opts     = opts
 259 };
 260
 261 void _init(void)
 262 {
 263         register_target(&route);
 264 }