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
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
|
/* Shared library add-on to iptables to add limit support.
*
* Jérôme de Vivie <devivie@info.enserb.u-bordeaux.fr>
* Hervé Eychenne <rv@wallfire.org>
*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <getopt.h>
#include <xtables.h>
#include <stddef.h>
#include <linux/netfilter/x_tables.h>
/* For 64bit kernel / 32bit userspace */
#include "../include/linux/netfilter/xt_limit.h"
#define XT_LIMIT_AVG "3/hour"
#define XT_LIMIT_BURST 5
/* Function which prints out usage message. */
static void
help(void)
{
printf(
"limit v%s options:\n"
"--limit avg max average match rate: default "XT_LIMIT_AVG"\n"
" [Packets per second unless followed by \n"
" /sec /minute /hour /day postfixes]\n"
"--limit-burst number number to match in a burst, default %u\n"
"\n", IPTABLES_VERSION, XT_LIMIT_BURST);
}
static const struct option opts[] = {
{ "limit", 1, 0, '%' },
{ "limit-burst", 1, 0, '$' },
{ 0 }
};
static
int parse_rate(const char *rate, u_int32_t *val)
{
const char *delim;
u_int32_t r;
u_int32_t mult = 1; /* Seconds by default. */
delim = strchr(rate, '/');
if (delim) {
if (strlen(delim+1) == 0)
return 0;
if (strncasecmp(delim+1, "second", strlen(delim+1)) == 0)
mult = 1;
else if (strncasecmp(delim+1, "minute", strlen(delim+1)) == 0)
mult = 60;
else if (strncasecmp(delim+1, "hour", strlen(delim+1)) == 0)
mult = 60*60;
else if (strncasecmp(delim+1, "day", strlen(delim+1)) == 0)
mult = 24*60*60;
else
return 0;
}
r = atoi(rate);
if (!r)
return 0;
/* This would get mapped to infinite (1/day is minimum they
can specify, so we're ok at that end). */
if (r / mult > XT_LIMIT_SCALE)
exit_error(PARAMETER_PROBLEM, "Rate too fast `%s'\n", rate);
*val = XT_LIMIT_SCALE * mult / r;
return 1;
}
/* Initialize the match. */
static void
init(struct xt_entry_match *m, unsigned int *nfcache)
{
struct xt_rateinfo *r = (struct xt_rateinfo *)m->data;
parse_rate(XT_LIMIT_AVG, &r->avg);
r->burst = XT_LIMIT_BURST;
}
/* FIXME: handle overflow:
if (r->avg*r->burst/r->burst != r->avg)
exit_error(PARAMETER_PROBLEM,
"Sorry: burst too large for that avg rate.\n");
*/
/* Function which parses command options; returns true if it
ate an option */
static int
parse(int c, char **argv, int invert, unsigned int *flags,
const void *entry,
unsigned int *nfcache,
struct xt_entry_match **match)
{
struct xt_rateinfo *r = (struct xt_rateinfo *)(*match)->data;
unsigned int num;
switch(c) {
case '%':
if (check_inverse(argv[optind-1], &invert, &optind, 0)) break;
if (!parse_rate(optarg, &r->avg))
exit_error(PARAMETER_PROBLEM,
"bad rate `%s'", optarg);
break;
case '$':
if (check_inverse(argv[optind-1], &invert, &optind, 0)) break;
if (string_to_number(optarg, 0, 10000, &num) == -1)
exit_error(PARAMETER_PROBLEM,
"bad --limit-burst `%s'", optarg);
r->burst = num;
break;
default:
return 0;
}
if (invert)
exit_error(PARAMETER_PROBLEM,
"limit does not support invert");
return 1;
}
/* Final check; nothing. */
static void final_check(unsigned int flags)
{
}
static struct rates
{
const char *name;
u_int32_t mult;
} rates[] = { { "day", XT_LIMIT_SCALE*24*60*60 },
{ "hour", XT_LIMIT_SCALE*60*60 },
{ "min", XT_LIMIT_SCALE*60 },
{ "sec", XT_LIMIT_SCALE } };
static void print_rate(u_int32_t period)
{
unsigned int i;
for (i = 1; i < sizeof(rates)/sizeof(struct rates); i++) {
if (period > rates[i].mult
|| rates[i].mult/period < rates[i].mult%period)
break;
}
printf("%u/%s ", rates[i-1].mult / period, rates[i-1].name);
}
/* Prints out the matchinfo. */
static void
print(const void *ip,
const struct xt_entry_match *match,
int numeric)
{
struct xt_rateinfo *r = (struct xt_rateinfo *)match->data;
printf("limit: avg "); print_rate(r->avg);
printf("burst %u ", r->burst);
}
/* FIXME: Make minimalist: only print rate if not default --RR */
static void save(const void *ip, const struct xt_entry_match *match)
{
struct xt_rateinfo *r = (struct xt_rateinfo *)match->data;
printf("--limit "); print_rate(r->avg);
if (r->burst != XT_LIMIT_BURST)
printf("--limit-burst %u ", r->burst);
}
static struct xtables_match limit = {
.family = AF_INET,
.name = "limit",
.version = IPTABLES_VERSION,
.size = XT_ALIGN(sizeof(struct xt_rateinfo)),
.userspacesize = offsetof(struct xt_rateinfo, prev),
.help = &help,
.init = &init,
.parse = &parse,
.final_check = &final_check,
.print = &print,
.save = &save,
.extra_opts = opts
};
static struct xtables_match limit6 = {
.family = AF_INET6,
.name = "limit",
.version = IPTABLES_VERSION,
.size = XT_ALIGN(sizeof(struct xt_rateinfo)),
.userspacesize = offsetof(struct xt_rateinfo, prev),
.help = &help,
.init = &init,
.parse = &parse,
.final_check = &final_check,
.print = &print,
.save = &save,
.extra_opts = opts
};
void _init(void)
{
xtables_register_match(&limit);
xtables_register_match(&limit6);
}
|
