1/* Shared library add-on to iptables to add simple load-balance 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
11#define BREAKUP_IP(x) (x)>>24, ((x)>>16) & 0xFF, ((x)>>8) & 0xFF, (x) & 0xFF
12
13/* Function which prints out usage message. */
14static void
15help(void)
16{
17	printf(
18"BALANCE v%s options:\n"
19" --to-destination <ipaddr>-<ipaddr>\n"
20"				Addresses to map destination to.\n",
21IPTABLES_VERSION);
22}
23
24static struct option opts[] = {
25	{ "to-destination", 1, 0, '1' },
26	{ 0 }
27};
28
29/* Initialize the target. */
30static void
31init(struct ipt_entry_target *t, unsigned int *nfcache)
32{
33	struct ip_nat_multi_range *mr = (struct ip_nat_multi_range *)t->data;
34
35	/* Actually, it's 0, but it's ignored at the moment. */
36	mr->rangesize = 1;
37
38	/* Can't cache this */
39	*nfcache |= NFC_UNKNOWN;
40}
41
42/* Parses range of IPs */
43static void
44parse_to(char *arg, struct ip_nat_range *range)
45{
46	char *dash;
47	struct in_addr *ip;
48
49	range->flags |= IP_NAT_RANGE_MAP_IPS;
50	dash = strchr(arg, '-');
51	if (dash)
52		*dash = '\0';
53	else
54		exit_error(PARAMETER_PROBLEM, "Bad IP range `%s'\n", arg);
55
56	ip = dotted_to_addr(arg);
57	if (!ip)
58		exit_error(PARAMETER_PROBLEM, "Bad IP address `%s'\n",
59			   arg);
60	range->min_ip = ip->s_addr;
61	ip = dotted_to_addr(dash+1);
62	if (!ip)
63		exit_error(PARAMETER_PROBLEM, "Bad IP address `%s'\n",
64			   dash+1);
65	range->max_ip = ip->s_addr;
66}
67
68/* Function which parses command options; returns true if it
69   ate an option */
70static int
71parse(int c, char **argv, int invert, unsigned int *flags,
72      const struct ipt_entry *entry,
73      struct ipt_entry_target **target)
74{
75	struct ip_nat_multi_range *mr
76		= (struct ip_nat_multi_range *)(*target)->data;
77
78	switch (c) {
79	case '1':
80		if (check_inverse(optarg, &invert, NULL, 0))
81			exit_error(PARAMETER_PROBLEM,
82				   "Unexpected `!' after --to-destination");
83
84		parse_to(optarg, &mr->range[0]);
85		*flags = 1;
86		return 1;
87
88	default:
89		return 0;
90	}
91}
92
93/* Final check; need --to-dest. */
94static void final_check(unsigned int flags)
95{
96	if (!flags)
97		exit_error(PARAMETER_PROBLEM,
98			   "BALANCE needs --to-destination");
99}
100
101/* Prints out the targinfo. */
102static void
103print(const struct ipt_ip *ip,
104      const struct ipt_entry_target *target,
105      int numeric)
106{
107	struct ip_nat_multi_range *mr
108		= (struct ip_nat_multi_range *)target->data;
109	struct ip_nat_range *r = &mr->range[0];
110	struct in_addr a;
111
112	a.s_addr = r->min_ip;
113
114	printf("balance %s", addr_to_dotted(&a));
115	a.s_addr = r->max_ip;
116	printf("-%s ", addr_to_dotted(&a));
117}
118
119/* Saves the union ipt_targinfo in parsable form to stdout. */
120static void
121save(const struct ipt_ip *ip, const struct ipt_entry_target *target)
122{
123	struct ip_nat_multi_range *mr
124		= (struct ip_nat_multi_range *)target->data;
125	struct ip_nat_range *r = &mr->range[0];
126	struct in_addr a;
127
128	a.s_addr = r->min_ip;
129	printf("--to-destination %s", addr_to_dotted(&a));
130	a.s_addr = r->max_ip;
131	printf("-%s ", addr_to_dotted(&a));
132}
133
134static
135struct iptables_target balance
136= { NULL,
137    "BALANCE",
138    IPTABLES_VERSION,
139    IPT_ALIGN(sizeof(struct ip_nat_multi_range)),
140    IPT_ALIGN(sizeof(struct ip_nat_multi_range)),
141    &help,
142    &init,
143    &parse,
144    &final_check,
145    &print,
146    &save,
147    opts
148};
149
150void _init(void)
151{
152	register_target(&balance);
153}
154