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	memset(&sel, 0, sizeof(sel));
95
96	while (argc > 0) {
97		if (matches(*argv, "nat") == 0) {
98			NEXT_ARG();
99			if (parse_nat_args(&argc, &argv, &sel)) {
100				fprintf(stderr, "Illegal nat construct (%s) \n",
101					*argv);
102				explain();
103				return -1;
104			}
105			ok++;
106			continue;
107		} else if (matches(*argv, "help") == 0) {
108			usage();
109		} else {
110			break;
111		}
112
113	}
114
115	if (!ok) {
116		explain();
117		return -1;
118	}
119
120	if (argc) {
121		if (matches(*argv, "reclassify") == 0) {
122			sel.action = TC_ACT_RECLASSIFY;
123			argc--;
124			argv++;
125		} else if (matches(*argv, "pipe") == 0) {
126			sel.action = TC_ACT_PIPE;
127			argc--;
128			argv++;
129		} else if (matches(*argv, "drop") == 0 ||
130			matches(*argv, "shot") == 0) {
131			sel.action = TC_ACT_SHOT;
132			argc--;
133			argv++;
134		} else if (matches(*argv, "continue") == 0) {
135			sel.action = TC_ACT_UNSPEC;
136			argc--;
137			argv++;
138		} else if (matches(*argv, "pass") == 0) {
139			sel.action = TC_ACT_OK;
140			argc--;
141			argv++;
142		}
143	}
144
145	if (argc) {
146		if (matches(*argv, "index") == 0) {
147			NEXT_ARG();
148			if (get_u32(&sel.index, *argv, 10)) {
149				fprintf(stderr, "Pedit: Illegal \"index\"\n");
150				return -1;
151			}
152			argc--;
153			argv++;
154		}
155	}
156
157	tail = NLMSG_TAIL(n);
158	addattr_l(n, MAX_MSG, tca_id, NULL, 0);
159	addattr_l(n, MAX_MSG, TCA_NAT_PARMS, &sel, sizeof(sel));
160	tail->rta_len = (char *)NLMSG_TAIL(n) - (char *)tail;
161
162	*argc_p = argc;
163	*argv_p = argv;
164	return 0;
165}
166
167static int
168print_nat(struct action_util *au,FILE * f, struct rtattr *arg)
169{
170	struct tc_nat *sel;
171	struct rtattr *tb[TCA_NAT_MAX + 1];
172	char buf1[256];
173	char buf2[256];
174	SPRINT_BUF(buf3);
175	int len;
176
177	if (arg == NULL)
178		return -1;
179
180	parse_rtattr_nested(tb, TCA_NAT_MAX, arg);
181
182	if (tb[TCA_NAT_PARMS] == NULL) {
183		fprintf(f, "[NULL nat parameters]");
184		return -1;
185	}
186	sel = RTA_DATA(tb[TCA_NAT_PARMS]);
187
188	len = ffs(sel->mask);
189	len = len ? 33 - len : 0;
190
191	fprintf(f, " nat %s %s/%d %s %s", sel->flags & TCA_NAT_FLAG_EGRESS ?
192					  "egress" : "ingress",
193		format_host(AF_INET, 4, &sel->old_addr, buf1, sizeof(buf1)),
194		len,
195		format_host(AF_INET, 4, &sel->new_addr, buf2, sizeof(buf2)),
196		action_n2a(sel->action, buf3, sizeof (buf3)));
197
198	if (show_stats) {
199		if (tb[TCA_NAT_TM]) {
200			struct tcf_t *tm = RTA_DATA(tb[TCA_NAT_TM]);
201			print_tm(f,tm);
202		}
203	}
204
205	return 0;
206}
207
208struct action_util nat_action_util = {
209	.id = "nat",
210	.parse_aopt = parse_nat,
211	.print_aopt = print_nat,
212};
213