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
|
/* Shared library add-on to iptables to add redirect support. */
#include <stdio.h>
#include <netdb.h>
#include <string.h>
#include <stdlib.h>
#include <getopt.h>
#include <iptables.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter/nf_nat.h>
#define IPT_REDIRECT_OPT_DEST 0x01
#define IPT_REDIRECT_OPT_RANDOM 0x02
/* Function which prints out usage message. */
static void REDIRECT_help(void)
{
printf(
"REDIRECT v%s options:\n"
" --to-ports <port>[-<port>]\n"
" Port (range) to map to.\n\n",
IPTABLES_VERSION);
}
static const struct option REDIRECT_opts[] = {
{ "to-ports", 1, NULL, '1' },
{ "random", 0, NULL, '2' },
{ .name = NULL }
};
/* Initialize the target. */
static void REDIRECT_init(struct xt_entry_target *t)
{
struct ip_nat_multi_range *mr = (struct ip_nat_multi_range *)t->data;
/* Actually, it's 0, but it's ignored at the moment. */
mr->rangesize = 1;
}
/* Parses ports */
static void
parse_ports(const char *arg, struct ip_nat_multi_range *mr)
{
const char *dash;
int port;
mr->range[0].flags |= IP_NAT_RANGE_PROTO_SPECIFIED;
if (strchr(arg, '.'))
exit_error(PARAMETER_PROBLEM, "IP address not permitted\n");
port = atoi(arg);
if (port == 0 || port > 65535)
exit_error(PARAMETER_PROBLEM, "Port `%s' not valid\n", arg);
dash = strchr(arg, '-');
if (!dash) {
mr->range[0].min.tcp.port
= mr->range[0].max.tcp.port
= htons(port);
} else {
int maxport;
maxport = atoi(dash + 1);
if (maxport == 0 || maxport > 65535)
exit_error(PARAMETER_PROBLEM,
"Port `%s' not valid\n", dash+1);
if (maxport < port)
/* People are stupid. */
exit_error(PARAMETER_PROBLEM,
"Port range `%s' funky\n", arg);
mr->range[0].min.tcp.port = htons(port);
mr->range[0].max.tcp.port = htons(maxport);
}
}
/* Function which parses command options; returns true if it
ate an option */
static int REDIRECT_parse(int c, char **argv, int invert, unsigned int *flags,
const void *e, struct xt_entry_target **target)
{
const struct ipt_entry *entry = e;
struct ip_nat_multi_range *mr
= (struct ip_nat_multi_range *)(*target)->data;
int portok;
if (entry->ip.proto == IPPROTO_TCP
|| entry->ip.proto == IPPROTO_UDP
|| entry->ip.proto == IPPROTO_ICMP)
portok = 1;
else
portok = 0;
switch (c) {
case '1':
if (!portok)
exit_error(PARAMETER_PROBLEM,
"Need TCP or UDP with port specification");
if (check_inverse(optarg, &invert, NULL, 0))
exit_error(PARAMETER_PROBLEM,
"Unexpected `!' after --to-ports");
parse_ports(optarg, mr);
if (*flags & IPT_REDIRECT_OPT_RANDOM)
mr->range[0].flags |= IP_NAT_RANGE_PROTO_RANDOM;
*flags |= IPT_REDIRECT_OPT_DEST;
return 1;
case '2':
if (*flags & IPT_REDIRECT_OPT_DEST) {
mr->range[0].flags |= IP_NAT_RANGE_PROTO_RANDOM;
*flags |= IPT_REDIRECT_OPT_RANDOM;
} else
*flags |= IPT_REDIRECT_OPT_RANDOM;
return 1;
default:
return 0;
}
}
/* Prints out the targinfo. */
static void REDIRECT_print(const void *ip, const struct xt_entry_target *target,
int numeric)
{
struct ip_nat_multi_range *mr
= (struct ip_nat_multi_range *)target->data;
struct ip_nat_range *r = &mr->range[0];
if (r->flags & IP_NAT_RANGE_PROTO_SPECIFIED) {
printf("redir ports ");
printf("%hu", ntohs(r->min.tcp.port));
if (r->max.tcp.port != r->min.tcp.port)
printf("-%hu", ntohs(r->max.tcp.port));
printf(" ");
if (mr->range[0].flags & IP_NAT_RANGE_PROTO_RANDOM)
printf("random ");
}
}
/* Saves the union ipt_targinfo in parsable form to stdout. */
static void REDIRECT_save(const void *ip, const struct xt_entry_target *target)
{
struct ip_nat_multi_range *mr
= (struct ip_nat_multi_range *)target->data;
struct ip_nat_range *r = &mr->range[0];
if (r->flags & IP_NAT_RANGE_PROTO_SPECIFIED) {
printf("--to-ports ");
printf("%hu", ntohs(r->min.tcp.port));
if (r->max.tcp.port != r->min.tcp.port)
printf("-%hu", ntohs(r->max.tcp.port));
printf(" ");
if (mr->range[0].flags & IP_NAT_RANGE_PROTO_RANDOM)
printf("--random ");
}
}
static struct iptables_target redirect_target = {
.name = "REDIRECT",
.version = IPTABLES_VERSION,
.size = IPT_ALIGN(sizeof(struct ip_nat_multi_range)),
.userspacesize = IPT_ALIGN(sizeof(struct ip_nat_multi_range)),
.help = REDIRECT_help,
.init = REDIRECT_init,
.parse = REDIRECT_parse,
.print = REDIRECT_print,
.save = REDIRECT_save,
.extra_opts = REDIRECT_opts,
};
void _init(void)
{
register_target(&redirect_target);
}
|
