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
|
/* Shared library add-on to iptables to add static NAT support.
Author: Svenning Soerensen <svenning@post5.tele.dk>
*/
#include <stdbool.h>
#include <stdio.h>
#include <netdb.h>
#include <string.h>
#include <stdlib.h>
#include <getopt.h>
#include <xtables.h>
#include <net/netfilter/nf_nat.h>
#define MODULENAME "NETMAP"
static const struct option NETMAP_opts[] = {
{.name = "to", .has_arg = true, .val = '1'},
XT_GETOPT_TABLEEND,
};
static void NETMAP_help(void)
{
printf(MODULENAME" target options:\n"
" --%s address[/mask]\n"
" Network address to map to.\n\n",
NETMAP_opts[0].name);
}
static uint32_t
bits2netmask(int bits)
{
uint32_t netmask, bm;
if (bits >= 32 || bits < 0)
return(~0);
for (netmask = 0, bm = 0x80000000; bits; bits--, bm >>= 1)
netmask |= bm;
return htonl(netmask);
}
static int
netmask2bits(uint32_t netmask)
{
uint32_t bm;
int bits;
netmask = ntohl(netmask);
for (bits = 0, bm = 0x80000000; netmask & bm; netmask <<= 1)
bits++;
if (netmask)
return -1; /* holes in netmask */
return bits;
}
static void NETMAP_init(struct xt_entry_target *t)
{
struct nf_nat_multi_range *mr = (struct nf_nat_multi_range *)t->data;
/* Actually, it's 0, but it's ignored at the moment. */
mr->rangesize = 1;
}
/* Parses network address */
static void
parse_to(char *arg, struct nf_nat_range *range)
{
char *slash;
const struct in_addr *ip;
uint32_t netmask;
unsigned int bits;
range->flags |= IP_NAT_RANGE_MAP_IPS;
slash = strchr(arg, '/');
if (slash)
*slash = '\0';
ip = xtables_numeric_to_ipaddr(arg);
if (!ip)
xtables_error(PARAMETER_PROBLEM, "Bad IP address \"%s\"\n",
arg);
range->min_ip = ip->s_addr;
if (slash) {
if (strchr(slash+1, '.')) {
ip = xtables_numeric_to_ipmask(slash+1);
if (!ip)
xtables_error(PARAMETER_PROBLEM, "Bad netmask \"%s\"\n",
slash+1);
netmask = ip->s_addr;
}
else {
if (!xtables_strtoui(slash+1, NULL, &bits, 0, 32))
xtables_error(PARAMETER_PROBLEM, "Bad netmask \"%s\"\n",
slash+1);
netmask = bits2netmask(bits);
}
/* Don't allow /0 (/1 is probably insane, too) */
if (netmask == 0)
xtables_error(PARAMETER_PROBLEM, "Netmask needed\n");
}
else
netmask = ~0;
if (range->min_ip & ~netmask) {
if (slash)
*slash = '/';
xtables_error(PARAMETER_PROBLEM, "Bad network address \"%s\"\n",
arg);
}
range->max_ip = range->min_ip | ~netmask;
}
static int NETMAP_parse(int c, char **argv, int invert, unsigned int *flags,
const void *entry, struct xt_entry_target **target)
{
struct nf_nat_multi_range *mr
= (struct nf_nat_multi_range *)(*target)->data;
switch (c) {
case '1':
if (xtables_check_inverse(optarg, &invert, NULL, 0, argv))
xtables_error(PARAMETER_PROBLEM,
"Unexpected `!' after --%s", NETMAP_opts[0].name);
parse_to(optarg, &mr->range[0]);
*flags = 1;
return 1;
}
return 0;
}
static void NETMAP_check(unsigned int flags)
{
if (!flags)
xtables_error(PARAMETER_PROBLEM,
MODULENAME" needs --%s", NETMAP_opts[0].name);
}
static void NETMAP_print(const void *ip, const struct xt_entry_target *target,
int numeric)
{
const struct nf_nat_multi_range *mr = (const void *)target->data;
const struct nf_nat_range *r = &mr->range[0];
struct in_addr a;
int bits;
a.s_addr = r->min_ip;
printf("%s", xtables_ipaddr_to_numeric(&a));
a.s_addr = ~(r->min_ip ^ r->max_ip);
bits = netmask2bits(a.s_addr);
if (bits < 0)
printf("/%s", xtables_ipaddr_to_numeric(&a));
else
printf("/%d", bits);
}
static void NETMAP_save(const void *ip, const struct xt_entry_target *target)
{
printf(" --%s ", NETMAP_opts[0].name);
NETMAP_print(ip, target, 0);
}
static struct xtables_target netmap_tg_reg = {
.name = MODULENAME,
.version = XTABLES_VERSION,
.family = NFPROTO_IPV4,
.size = XT_ALIGN(sizeof(struct nf_nat_multi_range)),
.userspacesize = XT_ALIGN(sizeof(struct nf_nat_multi_range)),
.help = NETMAP_help,
.init = NETMAP_init,
.parse = NETMAP_parse,
.final_check = NETMAP_check,
.print = NETMAP_print,
.save = NETMAP_save,
.extra_opts = NETMAP_opts,
};
void _init(void)
{
xtables_register_target(&netmap_tg_reg);
}
|
