1 /*
2 * IPv6 Hop Limit matching module
3 * Maciej Soltysiak <solt@dns.toxicfilms.tv>
4 * Based on HW's ttl match
5 * This program is released under the terms of GNU GPL
6 * Cleanups by Stephane Ouellette <ouellettes@videotron.ca>
7 */
8 #include <stdio.h>
9 #include <xtables.h>
10 #include <linux/netfilter_ipv6/ip6t_hl.h>
11
12 enum {
13 O_HL_EQ = 0,
14 O_HL_LT,
15 O_HL_GT,
16 F_HL_EQ = 1 << O_HL_EQ,
17 F_HL_LT = 1 << O_HL_LT,
18 F_HL_GT = 1 << O_HL_GT,
19 F_ANY = F_HL_EQ | F_HL_LT | F_HL_GT,
20 };
21
hl_help(void)22 static void hl_help(void)
23 {
24 printf(
25 "hl match options:\n"
26 "[!] --hl-eq value Match hop limit value\n"
27 " --hl-lt value Match HL < value\n"
28 " --hl-gt value Match HL > value\n");
29 }
30
hl_parse(struct xt_option_call * cb)31 static void hl_parse(struct xt_option_call *cb)
32 {
33 struct ip6t_hl_info *info = cb->data;
34
35 xtables_option_parse(cb);
36 switch (cb->entry->id) {
37 case O_HL_EQ:
38 info->mode = cb->invert ? IP6T_HL_NE : IP6T_HL_EQ;
39 break;
40 case O_HL_LT:
41 info->mode = IP6T_HL_LT;
42 break;
43 case O_HL_GT:
44 info->mode = IP6T_HL_GT;
45 break;
46 }
47 }
48
hl_check(struct xt_fcheck_call * cb)49 static void hl_check(struct xt_fcheck_call *cb)
50 {
51 if (!(cb->xflags & F_ANY))
52 xtables_error(PARAMETER_PROBLEM,
53 "HL match: You must specify one of "
54 "`--hl-eq', `--hl-lt', `--hl-gt'");
55 }
56
hl_print(const void * ip,const struct xt_entry_match * match,int numeric)57 static void hl_print(const void *ip, const struct xt_entry_match *match,
58 int numeric)
59 {
60 static const char *const op[] = {
61 [IP6T_HL_EQ] = "==",
62 [IP6T_HL_NE] = "!=",
63 [IP6T_HL_LT] = "<",
64 [IP6T_HL_GT] = ">" };
65
66 const struct ip6t_hl_info *info =
67 (struct ip6t_hl_info *) match->data;
68
69 printf(" HL match HL %s %u", op[info->mode], info->hop_limit);
70 }
71
hl_save(const void * ip,const struct xt_entry_match * match)72 static void hl_save(const void *ip, const struct xt_entry_match *match)
73 {
74 static const char *const op[] = {
75 [IP6T_HL_EQ] = "--hl-eq",
76 [IP6T_HL_NE] = "! --hl-eq",
77 [IP6T_HL_LT] = "--hl-lt",
78 [IP6T_HL_GT] = "--hl-gt" };
79
80 const struct ip6t_hl_info *info =
81 (struct ip6t_hl_info *) match->data;
82
83 printf(" %s %u", op[info->mode], info->hop_limit);
84 }
85
86 static const char *const op[] = {
87 [IP6T_HL_EQ] = "",
88 [IP6T_HL_NE] = "!= ",
89 [IP6T_HL_LT] = "lt ",
90 [IP6T_HL_GT] = "gt "
91 };
92
hl_xlate(struct xt_xlate * xl,const struct xt_xlate_mt_params * params)93 static int hl_xlate(struct xt_xlate *xl,
94 const struct xt_xlate_mt_params *params)
95 {
96 const struct ip6t_hl_info *info =
97 (struct ip6t_hl_info *) params->match->data;
98
99 xt_xlate_add(xl, "ip6 hoplimit %s%u", op[info->mode], info->hop_limit);
100
101 return 1;
102 }
103
104 #define s struct ip6t_hl_info
105 static const struct xt_option_entry hl_opts[] = {
106 {.name = "hl-lt", .id = O_HL_LT, .excl = F_ANY, .type = XTTYPE_UINT8,
107 .flags = XTOPT_PUT, XTOPT_POINTER(s, hop_limit)},
108 {.name = "hl-gt", .id = O_HL_GT, .excl = F_ANY, .type = XTTYPE_UINT8,
109 .flags = XTOPT_PUT, XTOPT_POINTER(s, hop_limit)},
110 {.name = "hl-eq", .id = O_HL_EQ, .excl = F_ANY, .type = XTTYPE_UINT8,
111 .flags = XTOPT_INVERT | XTOPT_PUT, XTOPT_POINTER(s, hop_limit)},
112 {.name = "hl", .id = O_HL_EQ, .excl = F_ANY, .type = XTTYPE_UINT8,
113 .flags = XTOPT_PUT, XTOPT_POINTER(s, hop_limit)},
114 XTOPT_TABLEEND,
115 };
116 #undef s
117
118 static struct xtables_match hl_mt6_reg = {
119 .name = "hl",
120 .version = XTABLES_VERSION,
121 .family = NFPROTO_IPV6,
122 .size = XT_ALIGN(sizeof(struct ip6t_hl_info)),
123 .userspacesize = XT_ALIGN(sizeof(struct ip6t_hl_info)),
124 .help = hl_help,
125 .print = hl_print,
126 .save = hl_save,
127 .x6_parse = hl_parse,
128 .x6_fcheck = hl_check,
129 .x6_options = hl_opts,
130 .xlate = hl_xlate,
131 };
132
133
_init(void)134 void _init(void)
135 {
136 xtables_register_match(&hl_mt6_reg);
137 }
138