extensions/libip6t_HL.c

   1 /*
   2  * IPv6 Hop Limit Target module
   3  * Maciej Soltysiak <solt@dns.toxicfilms.tv>
   4  * Based on HW's ttl target
   5  * This program is distributed under the terms of GNU GPL
   6  */
   7 #include <stdio.h>
   8 #include <xtables.h>
   9 #include <linux/netfilter_ipv6/ip6t_HL.h>
  10
  11 enum {
  12         O_HL_SET = 0,
  13         O_HL_INC,
  14         O_HL_DEC,
  15         F_HL_SET = 1 << O_HL_SET,
  16         F_HL_INC = 1 << O_HL_INC,
  17         F_HL_DEC = 1 << O_HL_DEC,
  18         F_ANY    = F_HL_SET | F_HL_INC | F_HL_DEC,
  19 };
  20
  21 #define s struct ip6t_HL_info
  22 static const struct xt_option_entry HL_opts[] = {
  23         {.name = "hl-set", .type = XTTYPE_UINT8, .id = O_HL_SET,
  24          .excl = F_ANY, .flags = XTOPT_PUT, XTOPT_POINTER(s, hop_limit)},
  25         {.name = "hl-dec", .type = XTTYPE_UINT8, .id = O_HL_DEC,
  26          .excl = F_ANY, .flags = XTOPT_PUT, XTOPT_POINTER(s, hop_limit),
  27          .min = 1},
  28         {.name = "hl-inc", .type = XTTYPE_UINT8, .id = O_HL_INC,
  29          .excl = F_ANY, .flags = XTOPT_PUT, XTOPT_POINTER(s, hop_limit),
  30          .min = 1},
  31         XTOPT_TABLEEND,
  32 };
  33 #undef s
  34
  35 static void HL_help(void)
  36 {
  37         printf(
  38 "HL target options\n"
  39 "  --hl-set value               Set HL to <value 0-255>\n"
  40 "  --hl-dec value               Decrement HL by <value 1-255>\n"
  41 "  --hl-inc value               Increment HL by <value 1-255>\n");
  42 }
  43
  44 static void HL_parse(struct xt_option_call *cb)
  45 {
  46         struct ip6t_HL_info *info = cb->data;
  47
  48         xtables_option_parse(cb);
  49         switch (cb->entry->id) {
  50         case O_HL_SET:
  51                 info->mode = IP6T_HL_SET;
  52                 break;
  53         case O_HL_INC:
  54                 info->mode = IP6T_HL_INC;
  55                 break;
  56         case O_HL_DEC:
  57                 info->mode = IP6T_HL_DEC;
  58                 break;
  59         }
  60 }
  61
  62 static void HL_check(struct xt_fcheck_call *cb)
  63 {
  64         if (!(cb->xflags & F_ANY))
  65                 xtables_error(PARAMETER_PROBLEM,
  66                                 "HL: You must specify an action");
  67 }
  68
  69 static void HL_save(const void *ip, const struct xt_entry_target *target)
  70 {
  71         const struct ip6t_HL_info *info =
  72                 (struct ip6t_HL_info *) target->data;
  73
  74         switch (info->mode) {
  75                 case IP6T_HL_SET:
  76                         printf(" --hl-set");
  77                         break;
  78                 case IP6T_HL_DEC:
  79                         printf(" --hl-dec");
  80                         break;
  81
  82                 case IP6T_HL_INC:
  83                         printf(" --hl-inc");
  84                         break;
  85         }
  86         printf(" %u", info->hop_limit);
  87 }
  88
  89 static void HL_print(const void *ip, const struct xt_entry_target *target,
  90                      int numeric)
  91 {
  92         const struct ip6t_HL_info *info =
  93                 (struct ip6t_HL_info *) target->data;
  94
  95         printf(" HL ");
  96         switch (info->mode) {
  97                 case IP6T_HL_SET:
  98                         printf("set to");
  99                         break;
 100                 case IP6T_HL_DEC:
 101                         printf("decrement by");
 102                         break;
 103                 case IP6T_HL_INC:
 104                         printf("increment by");
 105                         break;
 106         }
 107         printf(" %u", info->hop_limit);
 108 }
 109
 110 static struct xtables_target hl_tg6_reg = {
 111         .name           = "HL",
 112         .version        = XTABLES_VERSION,
 113         .family         = NFPROTO_IPV6,
 114         .size           = XT_ALIGN(sizeof(struct ip6t_HL_info)),
 115         .userspacesize  = XT_ALIGN(sizeof(struct ip6t_HL_info)),
 116         .help           = HL_help,
 117         .print          = HL_print,
 118         .save           = HL_save,
 119         .x6_parse       = HL_parse,
 120         .x6_fcheck      = HL_check,
 121         .x6_options     = HL_opts,
 122 };
 123
 124 void _init(void)
 125 {
 126         xtables_register_target(&hl_tg6_reg);
 127 }