libipt_SAME.c revision cf655eb194951a93e4e1371747273c12466c1952 
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 <iptables.h>
8#include <linux/netfilter_ipv4/ip_tables.h>
9#include <linux/netfilter_ipv4/ip_nat_rule.h>
10#include <linux/netfilter_ipv4/ipt_SAME.h>
11
12#define BREAKUP_IP(x) (x) & 0xFF, ((x)>>8) & 0xFF, ((x)>>16) & 0xFF, (x)>>24
13
14/* Function which prints out usage message. */
15static void
16help(void)
17{
18	printf(
19"SAME v%s options:\n"
20" --to <ipaddr>-<ipaddr>\n"
21"				Addresses to map source to.\n"
22" --nodst\n"
23"				Don't use destination-ip in\n"
24"				           source selection\n",
25NETFILTER_VERSION);
26}
27
28static struct option opts[] = {
29	{ "to", 1, 0, '1' },
30	{ "nodst", 0, 0, '2'},
31	{ 0 }
32};
33
34/* Initialize the target. */
35static void
36init(struct ipt_entry_target *t, unsigned int *nfcache)
37{
38	struct ipt_same_info *mr = (struct ipt_same_info *)t->data;
39
40	/* Actually, it's 0, but it's ignored at the moment. */
41	mr->rangesize = 1;
42
43	/* Set default info to 0 */
44	mr->info = 0;
45
46	/* Can't cache this */
47	*nfcache |= NFC_UNKNOWN;
48}
49
50/* Parses range of IPs */
51static void
52parse_to(char *arg, struct ip_nat_range *range)
53{
54	char *dash;
55	struct in_addr *ip;
56
57	range->flags |= IP_NAT_RANGE_MAP_IPS;
58	dash = strchr(arg, '-');
59	if (dash)
60		*dash = '\0';
61	else
62		exit_error(PARAMETER_PROBLEM, "Bad IP range `%s'\n", arg);
63
64	ip = dotted_to_addr(arg);
65	if (!ip)
66		exit_error(PARAMETER_PROBLEM, "Bad IP address `%s'\n",
67			   arg);
68	range->min_ip = ip->s_addr;
69	ip = dotted_to_addr(dash+1);
70	if (!ip)
71		exit_error(PARAMETER_PROBLEM, "Bad IP address `%s'\n",
72			   dash+1);
73	range->max_ip = ip->s_addr;
74	if (range->min_ip >= range->max_ip)
75		exit_error(PARAMETER_PROBLEM, "Bad IP range `%u.%u.%u.%u-%u.%u.%u.%u'\n", BREAKUP_IP(range->min_ip), BREAKUP_IP(range->max_ip));
76}
77
78#define IPT_SAME_OPT_TO			0x01
79#define IPT_SAME_OPT_NODST		0x02
80
81/* Function which parses command options; returns true if it
82   ate an option */
83static int
84parse(int c, char **argv, int invert, unsigned int *flags,
85      const struct ipt_entry *entry,
86      struct ipt_entry_target **target)
87{
88	struct ipt_same_info *mr
89		= (struct ipt_same_info *)(*target)->data;
90
91	switch (c) {
92	case '1':
93		if (*flags & IPT_SAME_OPT_TO)
94			exit_error(PARAMETER_PROBLEM,
95				   "Can't specify --to twice");
96
97		if (check_inverse(optarg, &invert))
98			exit_error(PARAMETER_PROBLEM,
99				   "Unexpected `!' after --to");
100
101		parse_to(optarg, &mr->range[0]);
102		*flags |= IPT_SAME_OPT_TO;
103		break;
104
105	case '2':
106		if (*flags & IPT_SAME_OPT_NODST)
107			exit_error(PARAMETER_PROBLEM,
108				   "Can't specify --nodst twice");
109
110		mr->info |= IPT_SAME_NODST;
111		*flags |= IPT_SAME_OPT_NODST;
112		break;
113
114	default:
115		return 0;
116	}
117
118	return 1;
119}
120
121/* Final check; need --to. */
122static void final_check(unsigned int flags)
123{
124	if (!(flags & IPT_SAME_OPT_TO))
125		exit_error(PARAMETER_PROBLEM,
126			   "SAME needs --to");
127}
128
129/* Prints out the targinfo. */
130static void
131print(const struct ipt_ip *ip,
132      const struct ipt_entry_target *target,
133      int numeric)
134{
135	struct ipt_same_info *mr
136		= (struct ipt_same_info *)target->data;
137	struct ip_nat_range *r = &mr->range[0];
138	struct in_addr a;
139
140	a.s_addr = r->min_ip;
141
142	printf("same %s", addr_to_dotted(&a));
143	a.s_addr = r->max_ip;
144	printf("-%s ", addr_to_dotted(&a));
145
146	if (mr->info & IPT_SAME_NODST)
147		printf("nodst ");
148}
149
150/* Saves the union ipt_targinfo in parsable form to stdout. */
151static void
152save(const struct ipt_ip *ip, const struct ipt_entry_target *target)
153{
154	struct ipt_same_info *mr
155		= (struct ipt_same_info *)target->data;
156	struct ip_nat_range *r = &mr->range[0];
157	struct in_addr a;
158
159	a.s_addr = r->min_ip;
160	printf("--to %s", addr_to_dotted(&a));
161	a.s_addr = r->max_ip;
162	printf("-%s ", addr_to_dotted(&a));
163
164	if (mr->info & IPT_SAME_NODST)
165		printf("--nodst ");
166}
167
168struct iptables_target same
169= { NULL,
170    "SAME",
171    NETFILTER_VERSION,
172    IPT_ALIGN(sizeof(struct ipt_same_info)),
173    IPT_ALIGN(sizeof(struct ipt_same_info)),
174    &help,
175    &init,
176    &parse,
177    &final_check,
178    &print,
179    &save,
180    opts
181};
182
183void _init(void)
184{
185	register_target(&same);
186}
187