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
   8 #include <stdio.h>
   9 #include <string.h>
  10 #include <stdlib.h>
  11 #include <getopt.h>
  12 #include <ip6tables.h>
  13
  14 #include <linux/netfilter_ipv6/ip6_tables.h>
  15 #include <linux/netfilter_ipv6/ip6t_HL.h>
  16
  17 #define IP6T_HL_USED    1
  18
  19 static void init(struct ip6t_entry_target *t, unsigned int *nfcache)
  20 {
  21 }
  22
  23 static void help(void)
  24 {
  25         printf(
  26 "HL target v%s options\n"
  27 "  --hl-set value               Set HL to <value>\n"
  28 "  --hl-dec value               Decrement HL by <value>\n"
  29 "  --hl-inc value               Increment HL by <value>\n"
  30 , IPTABLES_VERSION);
  31 }
  32
  33 static int parse(int c, char **argv, int invert, unsigned int *flags,
  34                 const struct ip6t_entry *entry,
  35                 struct ip6t_entry_target **target)
  36 {
  37         struct ip6t_HL_info *info = (struct ip6t_HL_info *) (*target)->data;
  38         u_int8_t value;
  39
  40         if (*flags & IP6T_HL_USED) {
  41                 exit_error(PARAMETER_PROBLEM,
  42                                 "Can't specify HL option twice");
  43         }
  44
  45         if (!optarg)
  46                 exit_error(PARAMETER_PROBLEM,
  47                                 "HL: You must specify a value");
  48
  49         if (check_inverse(optarg, &invert, NULL, 0))
  50                 exit_error(PARAMETER_PROBLEM,
  51                                 "HL: unexpected `!'");
  52
  53         value = atoi(optarg);
  54
  55         switch (c) {
  56
  57                 case '1':
  58                         info->mode = IP6T_HL_SET;
  59                         break;
  60
  61                 case '2':
  62                         if (value == 0) {
  63                                 exit_error(PARAMETER_PROBLEM,
  64                                         "HL: decreasing by 0?");
  65                         }
  66
  67                         info->mode = IP6T_HL_DEC;
  68                         break;
  69
  70                 case '3':
  71                         if (value == 0) {
  72                                 exit_error(PARAMETER_PROBLEM,
  73                                         "HL: increasing by 0?");
  74                         }
  75
  76                         info->mode = IP6T_HL_INC;
  77                         break;
  78
  79                 default:
  80                         return 0;
  81
  82         }
  83
  84         info->hop_limit = value;
  85         *flags |= IP6T_HL_USED;
  86
  87         return 1;
  88 }
  89
  90 static void final_check(unsigned int flags)
  91 {
  92         if (!(flags & IP6T_HL_USED))
  93                 exit_error(PARAMETER_PROBLEM,
  94                                 "HL: You must specify an action");
  95 }
  96
  97 static void save(const struct ip6t_ip6 *ip,
  98                 const struct ip6t_entry_target *target)
  99 {
 100         const struct ip6t_HL_info *info =
 101                 (struct ip6t_HL_info *) target->data;
 102
 103         switch (info->mode) {
 104                 case IP6T_HL_SET:
 105                         printf("--hl-set ");
 106                         break;
 107                 case IP6T_HL_DEC:
 108                         printf("--hl-dec ");
 109                         break;
 110
 111                 case IP6T_HL_INC:
 112                         printf("--hl-inc ");
 113                         break;
 114         }
 115         printf("%u ", info->hop_limit);
 116 }
 117
 118 static void print(const struct ip6t_ip6 *ip,
 119                 const struct ip6t_entry_target *target, int numeric)
 120 {
 121         const struct ip6t_HL_info *info =
 122                 (struct ip6t_HL_info *) target->data;
 123
 124         printf("HL ");
 125         switch (info->mode) {
 126                 case IP6T_HL_SET:
 127                         printf("set to ");
 128                         break;
 129                 case IP6T_HL_DEC:
 130                         printf("decrement by ");
 131                         break;
 132                 case IP6T_HL_INC:
 133                         printf("increment by ");
 134                         break;
 135         }
 136         printf("%u ", info->hop_limit);
 137 }
 138
 139 static struct option opts[] = {
 140         { "hl-set", 1, 0, '1' },
 141         { "hl-dec", 1, 0, '2' },
 142         { "hl-inc", 1, 0, '3' },
 143         { 0 }
 144 };
 145
 146 static
 147 struct ip6tables_target HL = { NULL,
 148         "HL",
 149         IPTABLES_VERSION,
 150         IP6T_ALIGN(sizeof(struct ip6t_HL_info)),
 151         IP6T_ALIGN(sizeof(struct ip6t_HL_info)),
 152         &help,
 153         &init,
 154         &parse,
 155         &final_check,
 156         &print,
 157         &save,
 158         opts
 159 };
 160
 161 void _init(void)
 162 {
 163         register_target6(&HL);
 164 }