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_ipv4/ip_nat_rule.h>
  10 #include <linux/netfilter_ipv4/ipt_SAME.h>
  11
  12 /* Function which prints out usage message. */
  13 static void
  14 help(void)
  15 {
  16         printf(
  17 "SAME v%s options:\n"
  18 " --to <ipaddr>-<ipaddr>\n"
  19 "                               Addresses to map source to.\n"
  20 "                                May be specified more than\n"
  21 "                                 once for multiple ranges.\n"
  22 " --nodst\n"
  23 "                               Don't use destination-ip in\n"
  24 "                                          source selection\n",
  25 IPTABLES_VERSION);
  26 }
  27
  28 static struct option opts[] = {
  29         { "to", 1, 0, '1' },
  30         { "nodst", 0, 0, '2'},
  31         { 0 }
  32 };
  33
  34 /* Initialize the target. */
  35 static void
  36 init(struct ipt_entry_target *t, unsigned int *nfcache)
  37 {
  38         struct ipt_same_info *mr = (struct ipt_same_info *)t->data;
  39
  40         /* Set default to 0 */
  41         mr->rangesize = 0;
  42         mr->info = 0;
  43         mr->ipnum = 0;
  44
  45         /* Can't cache this */
  46         *nfcache |= NFC_UNKNOWN;
  47 }
  48
  49 /* Parses range of IPs */
  50 static void
  51 parse_to(char *arg, struct ip_nat_range *range)
  52 {
  53         char *dash;
  54         struct in_addr *ip;
  55
  56         range->flags |= IP_NAT_RANGE_MAP_IPS;
  57         dash = strchr(arg, '-');
  58
  59         if (dash)
  60                 *dash = '\0';
  61
  62         ip = dotted_to_addr(arg);
  63         if (!ip)
  64                 exit_error(PARAMETER_PROBLEM, "Bad IP address `%s'\n",
  65                            arg);
  66         range->min_ip = ip->s_addr;
  67
  68         if (dash) {
  69                 ip = dotted_to_addr(dash+1);
  70                 if (!ip)
  71                         exit_error(PARAMETER_PROBLEM, "Bad IP address `%s'\n",
  72                                    dash+1);
  73         }
  74         range->max_ip = ip->s_addr;
  75         if (dash)
  76                 if (range->min_ip > range->max_ip)
  77                         exit_error(PARAMETER_PROBLEM, "Bad IP range `%s-%s'\n",
  78                                    arg, dash+1);
  79 }
  80
  81 #define IPT_SAME_OPT_TO                 0x01
  82 #define IPT_SAME_OPT_NODST              0x02
  83
  84 /* Function which parses command options; returns true if it
  85    ate an option */
  86 static int
  87 parse(int c, char **argv, int invert, unsigned int *flags,
  88       const struct ipt_entry *entry,
  89       struct ipt_entry_target **target)
  90 {
  91         struct ipt_same_info *mr
  92                 = (struct ipt_same_info *)(*target)->data;
  93
  94         switch (c) {
  95         case '1':
  96                 if (mr->rangesize == IPT_SAME_MAX_RANGE)
  97                         exit_error(PARAMETER_PROBLEM,
  98                                    "Too many ranges specified, maximum "
  99                                    "is %i ranges.\n",
 100                                    IPT_SAME_MAX_RANGE);
 101                 if (check_inverse(optarg, &invert, NULL, 0))
 102                         exit_error(PARAMETER_PROBLEM,
 103                                    "Unexpected `!' after --to");
 104
 105                 parse_to(optarg, &mr->range[mr->rangesize]);
 106                 mr->rangesize++;
 107                 *flags |= IPT_SAME_OPT_TO;
 108                 break;
 109
 110         case '2':
 111                 if (*flags & IPT_SAME_OPT_NODST)
 112                         exit_error(PARAMETER_PROBLEM,
 113                                    "Can't specify --nodst twice");
 114
 115                 mr->info |= IPT_SAME_NODST;
 116                 *flags |= IPT_SAME_OPT_NODST;
 117                 break;
 118
 119         default:
 120                 return 0;
 121         }
 122
 123         return 1;
 124 }
 125
 126 /* Final check; need --to. */
 127 static void final_check(unsigned int flags)
 128 {
 129         if (!(flags & IPT_SAME_OPT_TO))
 130                 exit_error(PARAMETER_PROBLEM,
 131                            "SAME needs --to");
 132 }
 133
 134 /* Prints out the targinfo. */
 135 static void
 136 print(const struct ipt_ip *ip,
 137       const struct ipt_entry_target *target,
 138       int numeric)
 139 {
 140         int count;
 141         struct ipt_same_info *mr
 142                 = (struct ipt_same_info *)target->data;
 143
 144         printf("same:");
 145
 146         for (count = 0; count < mr->rangesize; count++) {
 147                 struct ip_nat_range *r = &mr->range[count];
 148                 struct in_addr a;
 149
 150                 a.s_addr = r->min_ip;
 151
 152                 printf("%s", addr_to_dotted(&a));
 153                 a.s_addr = r->max_ip;
 154
 155                 if (r->min_ip == r->max_ip)
 156                         printf(" ");
 157                 else
 158                         printf("-%s ", addr_to_dotted(&a));
 159         }
 160
 161         if (mr->info & IPT_SAME_NODST)
 162                 printf("nodst ");
 163 }
 164
 165 /* Saves the union ipt_targinfo in parsable form to stdout. */
 166 static void
 167 save(const struct ipt_ip *ip, const struct ipt_entry_target *target)
 168 {
 169         int count;
 170         struct ipt_same_info *mr
 171                 = (struct ipt_same_info *)target->data;
 172
 173         for (count = 0; count < mr->rangesize; count++) {
 174                 struct ip_nat_range *r = &mr->range[count];
 175                 struct in_addr a;
 176
 177                 a.s_addr = r->min_ip;
 178                 printf("--to %s", addr_to_dotted(&a));
 179                 a.s_addr = r->max_ip;
 180
 181                 if (r->min_ip == r->max_ip)
 182                         printf(" ");
 183                 else
 184                         printf("-%s ", addr_to_dotted(&a));
 185         }
 186
 187         if (mr->info & IPT_SAME_NODST)
 188                 printf("--nodst ");
 189 }
 190
 191 static
 192 struct iptables_target same
 193 = { NULL,
 194     "SAME",
 195     IPTABLES_VERSION,
 196     IPT_ALIGN(sizeof(struct ipt_same_info)),
 197     IPT_ALIGN(sizeof(struct ipt_same_info)),
 198     &help,
 199     &init,
 200     &parse,
 201     &final_check,
 202     &print,
 203     &save,
 204     opts
 205 };
 206
 207 void _init(void)
 208 {
 209         register_target(&same);
 210 }