libipt_SAME.c revision 5d9678ad3eabc34ac40dfe055d7f6a8e44445a5a 
1/* Shared library add-on to iptables to add simple non load-balancing SNAT support. */
2#include <stdio.h>
3#include <netdb.h>
4#include <string.h>
5#include <stdlib.h>
6#include <getopt.h>
7#include <xtables.h>
8#include <linux/netfilter_ipv4/ip_tables.h>
9#include <linux/netfilter/nf_nat.h>
10/* For 64bit kernel / 32bit userspace */
11#include <linux/netfilter_ipv4/ipt_SAME.h>
12
13static void SAME_help(void)
14{
15	printf(
16"SAME target options:\n"
17" --to <ipaddr>-<ipaddr>\n"
18"				Addresses to map source to.\n"
19"				 May be specified more than\n"
20"				  once for multiple ranges.\n"
21" --nodst\n"
22"				Don't use destination-ip in\n"
23"				           source selection\n"
24" --random\n"
25"				Randomize source port\n");
26}
27
28static const struct option SAME_opts[] = {
29	{ "to", 1, NULL, '1' },
30	{ "nodst", 0, NULL, '2'},
31	{ "random", 0, NULL, '3' },
32	{ .name = NULL }
33};
34
35static void SAME_init(struct xt_entry_target *t)
36{
37	struct ipt_same_info *mr = (struct ipt_same_info *)t->data;
38
39	/* Set default to 0 */
40	mr->rangesize = 0;
41	mr->info = 0;
42	mr->ipnum = 0;
43
44}
45
46/* Parses range of IPs */
47static void
48parse_to(char *arg, struct ip_nat_range *range)
49{
50	char *dash;
51	const struct in_addr *ip;
52
53	range->flags |= IP_NAT_RANGE_MAP_IPS;
54	dash = strchr(arg, '-');
55
56	if (dash)
57		*dash = '\0';
58
59	ip = numeric_to_ipaddr(arg);
60	if (!ip)
61		exit_error(PARAMETER_PROBLEM, "Bad IP address `%s'\n",
62			   arg);
63	range->min_ip = ip->s_addr;
64
65	if (dash) {
66		ip = numeric_to_ipaddr(dash+1);
67		if (!ip)
68			exit_error(PARAMETER_PROBLEM, "Bad IP address `%s'\n",
69				   dash+1);
70	}
71	range->max_ip = ip->s_addr;
72	if (dash)
73		if (range->min_ip > range->max_ip)
74			exit_error(PARAMETER_PROBLEM, "Bad IP range `%s-%s'\n",
75				   arg, dash+1);
76}
77
78#define IPT_SAME_OPT_TO			0x01
79#define IPT_SAME_OPT_NODST		0x02
80#define IPT_SAME_OPT_RANDOM		0x04
81
82static int SAME_parse(int c, char **argv, int invert, unsigned int *flags,
83                      const void *entry, struct xt_entry_target **target)
84{
85	struct ipt_same_info *mr
86		= (struct ipt_same_info *)(*target)->data;
87	unsigned int count;
88
89	switch (c) {
90	case '1':
91		if (mr->rangesize == IPT_SAME_MAX_RANGE)
92			exit_error(PARAMETER_PROBLEM,
93				   "Too many ranges specified, maximum "
94				   "is %i ranges.\n",
95				   IPT_SAME_MAX_RANGE);
96		if (check_inverse(optarg, &invert, NULL, 0))
97			exit_error(PARAMETER_PROBLEM,
98				   "Unexpected `!' after --to");
99
100		parse_to(optarg, &mr->range[mr->rangesize]);
101		/* WTF do we need this for? */
102		if (*flags & IPT_SAME_OPT_RANDOM)
103			mr->range[mr->rangesize].flags
104				|= IP_NAT_RANGE_PROTO_RANDOM;
105		mr->rangesize++;
106		*flags |= IPT_SAME_OPT_TO;
107		break;
108
109	case '2':
110		if (*flags & IPT_SAME_OPT_NODST)
111			exit_error(PARAMETER_PROBLEM,
112				   "Can't specify --nodst twice");
113
114		mr->info |= IPT_SAME_NODST;
115		*flags |= IPT_SAME_OPT_NODST;
116		break;
117
118	case '3':
119		*flags |= IPT_SAME_OPT_RANDOM;
120		for (count=0; count < mr->rangesize; count++)
121			mr->range[count].flags |= IP_NAT_RANGE_PROTO_RANDOM;
122		break;
123
124	default:
125		return 0;
126	}
127
128	return 1;
129}
130
131static void SAME_check(unsigned int flags)
132{
133	if (!(flags & IPT_SAME_OPT_TO))
134		exit_error(PARAMETER_PROBLEM,
135			   "SAME needs --to");
136}
137
138static void SAME_print(const void *ip, const struct xt_entry_target *target,
139                       int numeric)
140{
141	unsigned int count;
142	struct ipt_same_info *mr
143		= (struct ipt_same_info *)target->data;
144	int random_selection = 0;
145
146	printf("same:");
147
148	for (count = 0; count < mr->rangesize; count++) {
149		struct ip_nat_range *r = &mr->range[count];
150		struct in_addr a;
151
152		a.s_addr = r->min_ip;
153
154		printf("%s", ipaddr_to_numeric(&a));
155		a.s_addr = r->max_ip;
156
157		if (r->min_ip == r->max_ip)
158			printf(" ");
159		else
160			printf("-%s ", ipaddr_to_numeric(&a));
161		if (r->flags & IP_NAT_RANGE_PROTO_RANDOM)
162			random_selection = 1;
163	}
164
165	if (mr->info & IPT_SAME_NODST)
166		printf("nodst ");
167
168	if (random_selection)
169		printf("random ");
170}
171
172static void SAME_save(const void *ip, const struct xt_entry_target *target)
173{
174	unsigned int count;
175	struct ipt_same_info *mr
176		= (struct ipt_same_info *)target->data;
177	int random_selection = 0;
178
179	for (count = 0; count < mr->rangesize; count++) {
180		struct ip_nat_range *r = &mr->range[count];
181		struct in_addr a;
182
183		a.s_addr = r->min_ip;
184		printf("--to %s", ipaddr_to_numeric(&a));
185		a.s_addr = r->max_ip;
186
187		if (r->min_ip == r->max_ip)
188			printf(" ");
189		else
190			printf("-%s ", ipaddr_to_numeric(&a));
191		if (r->flags & IP_NAT_RANGE_PROTO_RANDOM)
192			random_selection = 1;
193	}
194
195	if (mr->info & IPT_SAME_NODST)
196		printf("--nodst ");
197
198	if (random_selection)
199		printf("--random ");
200}
201
202static struct xtables_target same_tg_reg = {
203	.name		= "SAME",
204	.version	= XTABLES_VERSION,
205	.family		= NFPROTO_IPV4,
206	.size		= XT_ALIGN(sizeof(struct ipt_same_info)),
207	.userspacesize	= XT_ALIGN(sizeof(struct ipt_same_info)),
208	.help		= SAME_help,
209	.init		= SAME_init,
210	.parse		= SAME_parse,
211	.final_check	= SAME_check,
212	.print		= SAME_print,
213	.save		= SAME_save,
214	.extra_opts	= SAME_opts,
215};
216
217void _init(void)
218{
219	xtables_register_target(&same_tg_reg);
220}
221