1/*
2 * Copyright (c) 1990 Jan-Simon Pendry
3 * Copyright (c) 1990 Imperial College of Science, Technology & Medicine
4 * Copyright (c) 1990, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Jan-Simon Pendry at Imperial College, London.
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 * 3. Neither the name of the University nor the names of its contributors
19 *    may be used to endorse or promote products derived from this software
20 *    without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 *
34 *	from: @(#)wire.c	8.1 (Berkeley) 6/6/93
35 *	$Id: wire.c,v 1.14 2022/12/28 21:30:15 jmc Exp $
36 */
37
38/*
39 * This function returns the subnet (address&netmask) for the primary network
40 * interface.  If the resulting address has an entry in the hosts file, the
41 * corresponding name is returned, otherwise the address is returned in
42 * standard internet format.
43 * As a side-effect, a list of local IP/net address is recorded for use
44 * by the islocalnet() function.
45 *
46 * Derived from original by Paul Anderson (23/4/90)
47 * Updates from Dirk Grunwald (11/11/91)
48 * Modified to use getifaddrs() by Todd C. Miller (6/14/2003)
49 */
50
51#include "am.h"
52
53#include <ifaddrs.h>
54#include <netdb.h>
55#include <net/if.h>
56
57#define NO_SUBNET "notknown"
58
59/*
60 * List of locally connected networks
61 */
62typedef struct addrlist addrlist;
63struct addrlist {
64	addrlist *ip_next;
65	in_addr_t ip_addr;
66	in_addr_t ip_mask;
67};
68static addrlist *localnets = 0;
69
70char *
71getwire(void)
72{
73	struct ifaddrs *ifa, *ifaddrs;
74	struct hostent *hp;
75	addrlist *al;
76	char *s, *netname = NULL;
77
78	if (getifaddrs(&ifaddrs))
79		return strdup(NO_SUBNET);
80
81	for (ifa = ifaddrs; ifa != NULL; ifa = ifa -> ifa_next) {
82		/*
83		 * Ignore non-AF_INET interfaces as well as any that
84		 * are down or loopback.
85		 */
86		if (ifa->ifa_addr == NULL ||
87		    ifa->ifa_addr->sa_family != AF_INET ||
88		    !(ifa->ifa_flags & IFF_UP) ||
89		    (ifa->ifa_flags & IFF_LOOPBACK))
90			continue;
91
92		/*
93		 * Add interface to local network list
94		 */
95		al = ALLOC(addrlist);
96		al->ip_addr =
97		    ((struct sockaddr_in *)ifa->ifa_addr)->sin_addr.s_addr;
98		al->ip_mask =
99		    ((struct sockaddr_in *)ifa->ifa_netmask)->sin_addr.s_addr;
100		al->ip_next = localnets;
101		localnets = al;
102
103		/*
104		 * Look up the host name; fall back to a dotted quad.
105		 */
106		if (netname == NULL) {
107			in_addr_t subnet;
108			char dq[20];
109
110			subnet = al->ip_addr & al->ip_mask;
111			hp = gethostbyaddr((char *) &subnet, 4, AF_INET);
112			if (hp)
113				s = hp->h_name;
114			else
115				s = inet_dquad(dq, sizeof(dq), subnet);
116			netname = strdup(s);
117		}
118	}
119	freeifaddrs(ifaddrs);
120	return (netname ? netname : strdup(NO_SUBNET));
121}
122
123/*
124 * Determine whether a network is on a local network
125 * (addr) is in network byte order.
126 */
127int
128islocalnet(in_addr_t addr)
129{
130	addrlist *al;
131
132	for (al = localnets; al; al = al->ip_next)
133		if (((addr ^ al->ip_addr) & al->ip_mask) == 0)
134			return TRUE;
135
136#ifdef DEBUG
137	{ char buf[16];
138	plog(XLOG_INFO, "%s is on a remote network", inet_dquad(buf, sizeof(buf), addr));
139	}
140#endif
141	return FALSE;
142}
143