release/src/router/iptables/extensions/libipt_SAME.c

   1 /* Shared library add-on to iptables to add simple non load-balancing SNAT support. */
   2 #include <stdio.h>
   3 #include <netdb.h>
   4 #include <string.h>
   5 #include <stdlib.h>
   6 #include <getopt.h>
   7 #include <iptables.h>
   8 #include <linux/netfilter_ipv4/ip_tables.h>
   9 #include <linux/netfilter/nf_nat.h>
  10 /* For 64bit kernel / 32bit userspace */
  11 #include "../include/linux/netfilter_ipv4/ipt_SAME.h"
  12
  13 /* Function which prints out usage message. */
  14 static void
  15 help(void)
  16 {
  17         printf(
  18 "SAME v%s options:\n"
  19 " --to <ipaddr>-<ipaddr>\n"
  20 "                               Addresses to map source to.\n"
  21 "                                May be specified more than\n"
  22 "                                 once for multiple ranges.\n"
  23 " --nodst\n"
  24 "                               Don't use destination-ip in\n"
  25 "                                          source selection\n"
  26 " --random\n"
  27 "                               Randomize source port\n"
  28 ,
  29 IPTABLES_VERSION);
  30 }
  31
  32 static struct option opts[] = {
  33         { "to", 1, 0, '1' },
  34         { "nodst", 0, 0, '2'},
  35         { "random", 0, 0, '3' },
  36         { 0 }
  37 };
  38
  39 /* Initialize the target. */
  40 static void
  41 init(struct ipt_entry_target *t, unsigned int *nfcache)
  42 {
  43         struct ipt_same_info *mr = (struct ipt_same_info *)t->data;
  44
  45         /* Set default to 0 */
  46         mr->rangesize = 0;
  47         mr->info = 0;
  48         mr->ipnum = 0;
  49
  50 }
  51
  52 /* Parses range of IPs */
  53 static void
  54 parse_to(char *arg, struct ip_nat_range *range)
  55 {
  56         char *dash;
  57         struct in_addr *ip;
  58
  59         range->flags |= IP_NAT_RANGE_MAP_IPS;
  60         dash = strchr(arg, '-');
  61
  62         if (dash)
  63                 *dash = '\0';
  64
  65         ip = dotted_to_addr(arg);
  66         if (!ip)
  67                 exit_error(PARAMETER_PROBLEM, "Bad IP address `%s'\n",
  68                            arg);
  69         range->min_ip = ip->s_addr;
  70
  71         if (dash) {
  72                 ip = dotted_to_addr(dash+1);
  73                 if (!ip)
  74                         exit_error(PARAMETER_PROBLEM, "Bad IP address `%s'\n",
  75                                    dash+1);
  76         }
  77         range->max_ip = ip->s_addr;
  78         if (dash)
  79                 if (range->min_ip > range->max_ip)
  80                         exit_error(PARAMETER_PROBLEM, "Bad IP range `%s-%s'\n",
  81                                    arg, dash+1);
  82 }
  83
  84 #define IPT_SAME_OPT_TO                 0x01
  85 #define IPT_SAME_OPT_NODST              0x02
  86 #define IPT_SAME_OPT_RANDOM             0x04
  87
  88 /* Function which parses command options; returns true if it
  89    ate an option */
  90 static int
  91 parse(int c, char **argv, int invert, unsigned int *flags,
  92       const struct ipt_entry *entry,
  93       struct ipt_entry_target **target)
  94 {
  95         struct ipt_same_info *mr
  96                 = (struct ipt_same_info *)(*target)->data;
  97         int count;
  98
  99         switch (c) {
 100         case '1':
 101                 if (mr->rangesize == IPT_SAME_MAX_RANGE)
 102                         exit_error(PARAMETER_PROBLEM,
 103                                    "Too many ranges specified, maximum "
 104                                    "is %i ranges.\n",
 105                                    IPT_SAME_MAX_RANGE);
 106                 if (check_inverse(optarg, &invert, NULL, 0))
 107                         exit_error(PARAMETER_PROBLEM,
 108                                    "Unexpected `!' after --to");
 109
 110                 parse_to(optarg, &mr->range[mr->rangesize]);
 111                 /* WTF do we need this for? */
 112                 if (*flags & IPT_SAME_OPT_RANDOM)
 113                         mr->range[mr->rangesize].flags
 114                                 |= IP_NAT_RANGE_PROTO_RANDOM;
 115                 mr->rangesize++;
 116                 *flags |= IPT_SAME_OPT_TO;
 117                 break;
 118
 119         case '2':
 120                 if (*flags & IPT_SAME_OPT_NODST)
 121                         exit_error(PARAMETER_PROBLEM,
 122                                    "Can't specify --nodst twice");
 123
 124                 mr->info |= IPT_SAME_NODST;
 125                 *flags |= IPT_SAME_OPT_NODST;
 126                 break;
 127
 128         case '3':
 129                 *flags |= IPT_SAME_OPT_RANDOM;
 130                 for (count=0; count < mr->rangesize; count++)
 131                         mr->range[count].flags |= IP_NAT_RANGE_PROTO_RANDOM;
 132                 break;
 133
 134         default:
 135                 return 0;
 136         }
 137
 138         return 1;
 139 }
 140
 141 /* Final check; need --to. */
 142 static void final_check(unsigned int flags)
 143 {
 144         if (!(flags & IPT_SAME_OPT_TO))
 145                 exit_error(PARAMETER_PROBLEM,
 146                            "SAME needs --to");
 147 }
 148
 149 /* Prints out the targinfo. */
 150 static void
 151 print(const struct ipt_ip *ip,
 152       const struct ipt_entry_target *target,
 153       int numeric)
 154 {
 155         int count;
 156         struct ipt_same_info *mr
 157                 = (struct ipt_same_info *)target->data;
 158         int random = 0;
 159
 160         printf("same:");
 161
 162         for (count = 0; count < mr->rangesize; count++) {
 163                 struct ip_nat_range *r = &mr->range[count];
 164                 struct in_addr a;
 165
 166                 a.s_addr = r->min_ip;
 167
 168                 printf("%s", addr_to_dotted(&a));
 169                 a.s_addr = r->max_ip;
 170
 171                 if (r->min_ip == r->max_ip)
 172                         printf(" ");
 173                 else
 174                         printf("-%s ", addr_to_dotted(&a));
 175                 if (r->flags & IP_NAT_RANGE_PROTO_RANDOM)
 176                         random = 1;
 177         }
 178
 179         if (mr->info & IPT_SAME_NODST)
 180                 printf("nodst ");
 181
 182         if (random)
 183                 printf("random ");
 184 }
 185
 186 /* Saves the union ipt_targinfo in parsable form to stdout. */
 187 static void
 188 save(const struct ipt_ip *ip, const struct ipt_entry_target *target)
 189 {
 190         int count;
 191         struct ipt_same_info *mr
 192                 = (struct ipt_same_info *)target->data;
 193         int random = 0;
 194
 195         for (count = 0; count < mr->rangesize; count++) {
 196                 struct ip_nat_range *r = &mr->range[count];
 197                 struct in_addr a;
 198
 199                 a.s_addr = r->min_ip;
 200                 printf("--to %s", addr_to_dotted(&a));
 201                 a.s_addr = r->max_ip;
 202
 203                 if (r->min_ip == r->max_ip)
 204                         printf(" ");
 205                 else
 206                         printf("-%s ", addr_to_dotted(&a));
 207                 if (r->flags & IP_NAT_RANGE_PROTO_RANDOM)
 208                         random = 1;
 209         }
 210
 211         if (mr->info & IPT_SAME_NODST)
 212                 printf("--nodst ");
 213
 214         if (random)
 215                 printf("--random ");
 216 }
 217
 218 static struct iptables_target same = {
 219         .next           = NULL,
 220         .name           = "SAME",
 221         .version        = IPTABLES_VERSION,
 222         .size           = IPT_ALIGN(sizeof(struct ipt_same_info)),
 223         .userspacesize  = IPT_ALIGN(sizeof(struct ipt_same_info)),
 224         .help           = &help,
 225         .init           = &init,
 226         .parse          = &parse,
 227         .final_check    = &final_check,
 228         .print          = &print,
 229         .save           = &save,
 230         .extra_opts     = opts
 231 };
 232
 233 void _init(void)
 234 {
 235         register_target(&same);
 236 }