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      1 /*
      2  * IPv6 Hop Limit Target module
      3  * Maciej Soltysiak <solt (at) 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 }
    128