1/*
2 * m_nat.c		NAT module
3 *
4 *		This program is free software; you can distribute it and/or
5 *		modify it under the terms of the GNU General Public License
6 *		as published by the Free Software Foundation; either version
7 *		2 of the License, or (at your option) any later version.
8 *
9 * Authors:	Herbert Xu <herbert@gondor.apana.org.au>
10 *
11 */
12
13#include <stdio.h>
14#include <stdlib.h>
15#include <unistd.h>
16#include <syslog.h>
17#include <fcntl.h>
18#include <sys/socket.h>
19#include <netinet/in.h>
20#include <arpa/inet.h>
21#include <string.h>
22#include "utils.h"
23#include "tc_util.h"
24#include <linux/tc_act/tc_nat.h>
25
26static void
27explain(void)
28{
29	fprintf(stderr, "Usage: ... nat NAT\n"
30			"NAT := DIRECTION OLD NEW\n"
31			"DIRECTION := { ingress | egress }\n"
32			"OLD := PREFIX\n"
33			"NEW := ADDRESS\n");
34}
35
36static void
37usage(void)
38{
39	explain();
40	exit(-1);
41}
42
43static int
44parse_nat_args(int *argc_p, char ***argv_p, struct tc_nat *sel)
45{
46	int argc = *argc_p;
47	char **argv = *argv_p;
48	inet_prefix addr;
49
50	if (argc <= 0)
51		return -1;
52
53	if (matches(*argv, "egress") == 0)
54		sel->flags |= TCA_NAT_FLAG_EGRESS;
55	else if (matches(*argv, "ingress") != 0)
56		goto bad_val;
57
58	NEXT_ARG();
59
60	if (get_prefix_1(&addr, *argv, AF_INET))
61		goto bad_val;
62
63	sel->old_addr = addr.data[0];
64	sel->mask = htonl(~0u << (32 - addr.bitlen));
65
66	NEXT_ARG();
67
68	if (get_prefix_1(&addr, *argv, AF_INET))
69		goto bad_val;
70
71	sel->new_addr = addr.data[0];
72
73	argc--;
74	argv++;
75
76	*argc_p = argc;
77	*argv_p = argv;
78	return 0;
79
80bad_val:
81	return -1;
82}
83
84static int
85parse_nat(struct action_util *a, int *argc_p, char ***argv_p, int tca_id, struct nlmsghdr *n)
86{
87	struct tc_nat sel = {};
88
89	int argc = *argc_p;
90	char **argv = *argv_p;
91	int ok = 0;
92	struct rtattr *tail;
93
94	while (argc > 0) {
95		if (matches(*argv, "nat") == 0) {
96			NEXT_ARG();
97			if (parse_nat_args(&argc, &argv, &sel)) {
98				fprintf(stderr, "Illegal nat construct (%s)\n",
99					*argv);
100				explain();
101				return -1;
102			}
103			ok++;
104			continue;
105		} else if (matches(*argv, "help") == 0) {
106			usage();
107		} else {
108			break;
109		}
110
111	}
112
113	if (!ok) {
114		explain();
115		return -1;
116	}
117
118	parse_action_control_dflt(&argc, &argv, &sel.action, false, TC_ACT_OK);
119
120	if (argc) {
121		if (matches(*argv, "index") == 0) {
122			NEXT_ARG();
123			if (get_u32(&sel.index, *argv, 10)) {
124				fprintf(stderr, "Nat: Illegal \"index\"\n");
125				return -1;
126			}
127			argc--;
128			argv++;
129		}
130	}
131
132	tail = NLMSG_TAIL(n);
133	addattr_l(n, MAX_MSG, tca_id, NULL, 0);
134	addattr_l(n, MAX_MSG, TCA_NAT_PARMS, &sel, sizeof(sel));
135	tail->rta_len = (char *)NLMSG_TAIL(n) - (char *)tail;
136
137	*argc_p = argc;
138	*argv_p = argv;
139	return 0;
140}
141
142static int
143print_nat(struct action_util *au, FILE * f, struct rtattr *arg)
144{
145	struct tc_nat *sel;
146	struct rtattr *tb[TCA_NAT_MAX + 1];
147	char buf1[256];
148	char buf2[256];
149
150	int len;
151
152	if (arg == NULL)
153		return -1;
154
155	parse_rtattr_nested(tb, TCA_NAT_MAX, arg);
156
157	if (tb[TCA_NAT_PARMS] == NULL) {
158		fprintf(f, "[NULL nat parameters]");
159		return -1;
160	}
161	sel = RTA_DATA(tb[TCA_NAT_PARMS]);
162
163	len = ffs(sel->mask);
164	len = len ? 33 - len : 0;
165
166	fprintf(f, " nat %s %s/%d %s", sel->flags & TCA_NAT_FLAG_EGRESS ?
167				       "egress" : "ingress",
168		format_host_r(AF_INET, 4, &sel->old_addr, buf1, sizeof(buf1)),
169		len,
170		format_host_r(AF_INET, 4, &sel->new_addr, buf2, sizeof(buf2)));
171	print_action_control(f, " ", sel->action, "");
172
173	if (show_stats) {
174		if (tb[TCA_NAT_TM]) {
175			struct tcf_t *tm = RTA_DATA(tb[TCA_NAT_TM]);
176
177			print_tm(f, tm);
178		}
179	}
180
181	return 0;
182}
183
184struct action_util nat_action_util = {
185	.id = "nat",
186	.parse_aopt = parse_nat,
187	.print_aopt = print_nat,
188};
189