1/*	$NetBSD: npf.c,v 1.2 2016/12/10 22:09:18 christos Exp $	*/
2
3/*-
4 * Copyright (c) 2016 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Christos Zoulas.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32#include <sys/cdefs.h>
33__RCSID("$NetBSD: npf.c,v 1.2 2016/12/10 22:09:18 christos Exp $");
34
35#include <sys/types.h>
36#include <sys/socket.h>
37#include <sys/ioctl.h>
38#include <sys/fcntl.h>
39
40#include <net/if.h>
41#include <netinet/in.h>
42
43#include <npf.h>
44#include <stdlib.h>
45#include <string.h>
46#include <errno.h>
47#include <syslog.h>
48#include <unistd.h>
49
50#include "identd.h"
51
52int
53npf_natlookup(const struct sockaddr_storage *ss,
54    struct sockaddr_storage *nat_addr, in_port_t *nat_lport)
55{
56	npf_addr_t *addr[2];
57	in_port_t port[2];
58	int dev, af;
59
60	/* copy the source into nat_addr so it is writable */
61	memcpy(nat_addr, &ss[0], sizeof(ss[0]));
62
63	switch (af = ss[0].ss_family) {
64	case AF_INET:
65		addr[0] = (void *)&satosin(nat_addr)->sin_addr;
66		addr[1] = __UNCONST(&csatosin(&ss[1])->sin_addr);
67		port[0] = csatosin(&ss[0])->sin_port;
68		port[1] = csatosin(&ss[1])->sin_port;
69		break;
70	case AF_INET6:
71		addr[0] = (void *)&satosin6(&nat_addr)->sin6_addr;
72		addr[1] = __UNCONST(&csatosin6(&ss[0])->sin6_addr);
73		port[0] = csatosin6(&ss[0])->sin6_port;
74		port[1] = csatosin6(&ss[1])->sin6_port;
75		break;
76	default:
77		errno = EAFNOSUPPORT;
78		maybe_syslog(LOG_ERR, "NAT lookup for %d: %m" , af);
79		return 0;
80	}
81
82	/* Open the /dev/pf device and do the lookup. */
83	if ((dev = open("/dev/npf", O_RDWR)) == -1) {
84		maybe_syslog(LOG_ERR, "Cannot open /dev/npf: %m");
85		return 0;
86	}
87	if (npf_nat_lookup(dev, af, addr, port, IPPROTO_TCP, PFIL_OUT) == -1) {
88		maybe_syslog(LOG_ERR, "NAT lookup failure: %m");
89		(void)close(dev);
90		return 0;
91	}
92	(void)close(dev);
93
94	/*
95	 * The originating address is already set into nat_addr so fill
96	 * in the rest, family, port (ident), len....
97	 */
98	switch (af) {
99	case AF_INET:
100		satosin(nat_addr)->sin_port = htons(113);
101		satosin(nat_addr)->sin_len = sizeof(struct sockaddr_in);
102		satosin(nat_addr)->sin_family = AF_INET;
103		break;
104	case AF_INET6:
105		satosin6(nat_addr)->sin6_port = htons(113);
106		satosin6(nat_addr)->sin6_len = sizeof(struct sockaddr_in6);
107		satosin6(nat_addr)->sin6_family = AF_INET6;
108		break;
109	}
110	/* Put the originating port into nat_lport. */
111	*nat_lport = ntohs(port[0]);
112
113	return 1;
114}
115