1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
|
/* Shared library add-on to iptables to add connection limit support. */
#include <stdio.h>
#include <netdb.h>
#include <string.h>
#include <stdlib.h>
#include <stddef.h>
#include <getopt.h>
#include <ip6tables.h>
#include "../include/linux/netfilter/xt_connlimit.h"
/* Function which prints out usage message. */
static void connlimit_help(void)
{
printf(
"connlimit v%s options:\n"
"[!] --connlimit-above n match if the number of existing "
" connections is (not) above n\n"
" --connlimit-mask n group hosts using mask\n"
"\n", IPTABLES_VERSION);
}
static const struct option connlimit_opts[] = {
{"connlimit-above", 1, NULL, 1},
{"connlimit-mask", 1, NULL, 2},
{NULL},
};
static void connlimit_init(struct ip6t_entry_match *match, unsigned int *nfc)
{
struct xt_connlimit_info *info = (void *)match->data;
info->v6_mask[0] =
info->v6_mask[1] =
info->v6_mask[2] =
info->v6_mask[3] = 0xFFFFFFFF;
}
static void prefix_to_netmask(u_int32_t *mask, unsigned int prefix_len)
{
if (prefix_len == 0) {
mask[0] = mask[1] = mask[2] = mask[3] = 0;
} else if (prefix_len <= 32) {
mask[0] <<= 32 - prefix_len;
mask[1] = mask[2] = mask[3] = 0;
} else if (prefix_len <= 64) {
mask[1] <<= 32 - (prefix_len - 32);
mask[2] = mask[3] = 0;
} else if (prefix_len <= 96) {
mask[2] <<= 32 - (prefix_len - 64);
mask[3] = 0;
} else if (prefix_len <= 128) {
mask[3] <<= 32 - (prefix_len - 96);
}
mask[0] = htonl(mask[0]);
mask[1] = htonl(mask[1]);
mask[2] = htonl(mask[2]);
mask[3] = htonl(mask[3]);
}
static int connlimit_parse(int c, char **argv, int invert, unsigned int *flags,
const struct ip6t_entry *entry,
unsigned int *nfcache,
struct ip6t_entry_match **match)
{
struct xt_connlimit_info *info = (void *)(*match)->data;
char *err;
int i;
if (*flags & c)
exit_error(PARAMETER_PROBLEM,
"--connlimit-above and/or --connlimit-mask may "
"only be given once");
switch (c) {
case 1:
check_inverse(optarg, &invert, &optind, 0);
info->limit = strtoul(argv[optind-1], NULL, 0);
info->inverse = invert;
break;
case 2:
i = strtoul(argv[optind-1], &err, 0);
if (i > 128 || *err != '\0')
exit_error(PARAMETER_PROBLEM,
"--connlimit-mask must be between 0 and 128");
prefix_to_netmask(info->v6_mask, i);
break;
default:
return 0;
}
*flags |= c;
return 1;
}
/* Final check */
static void connlimit_check(unsigned int flags)
{
if (!(flags & 1))
exit_error(PARAMETER_PROBLEM,
"You must specify \"--connlimit-above\"");
}
static unsigned int count_bits(const u_int32_t *mask)
{
unsigned int bits = 0, i;
u_int32_t tmp[4];
for (i = 0; i < 4; ++i)
for (tmp[i] = ~ntohl(mask[i]); tmp[i] != 0; tmp[i] >>= 1)
++bits;
return 128 - bits;
}
/* Prints out the matchinfo. */
static void connlimit_print(const struct ip6t_ip6 *ip,
const struct ip6t_entry_match *match, int numeric)
{
const struct xt_connlimit_info *info = (const void *)match->data;
printf("#conn/%u %s %u ", count_bits(info->v6_mask),
info->inverse ? "<" : ">", info->limit);
}
/* Saves the matchinfo in parsable form to stdout. */
static void connlimit_save(const struct ip6t_ip6 *ip,
const struct ip6t_entry_match *match)
{
const struct xt_connlimit_info *info = (const void *)match->data;
printf("%s--connlimit-above %u --connlimit-mask %u ",
info->inverse ? "! " : "", info->limit,
count_bits(info->v6_mask));
}
static struct ip6tables_match connlimit_reg = {
.name = "connlimit",
.version = IPTABLES_VERSION,
.size = IP6T_ALIGN(sizeof(struct xt_connlimit_info)),
.userspacesize = offsetof(struct xt_connlimit_info, data),
.help = connlimit_help,
.init = connlimit_init,
.parse = connlimit_parse,
.final_check = connlimit_check,
.print = connlimit_print,
.save = connlimit_save,
.extra_opts = connlimit_opts,
};
void _init(void)
{
register_match6(&connlimit_reg);
}
|
