1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
|
/*
* Copyright (c) 1990 Jan-Simon Pendry
* Copyright (c) 1990 Imperial College of Science, Technology & Medicine
* Copyright (c) 1990, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Jan-Simon Pendry at Imperial College, London.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* from: @(#)wire.c 8.1 (Berkeley) 6/6/93
* $Id: wire.c,v 1.12 2003/06/17 18:00:24 millert Exp $
*/
/*
* This function returns the subnet (address&netmask) for the primary network
* interface. If the resulting address has an entry in the hosts file, the
* corresponding name is retuned, otherwise the address is returned in
* standard internet format.
* As a side-effect, a list of local IP/net address is recorded for use
* by the islocalnet() function.
*
* Derived from original by Paul Anderson (23/4/90)
* Updates from Dirk Grunwald (11/11/91)
* Modified to use getifaddrs() by Todd C. Miller (6/14/2003)
*/
#include "am.h"
#include <ifaddrs.h>
#include <netdb.h>
#include <net/if.h>
#define NO_SUBNET "notknown"
/*
* List of locally connected networks
*/
typedef struct addrlist addrlist;
struct addrlist {
addrlist *ip_next;
in_addr_t ip_addr;
in_addr_t ip_mask;
};
static addrlist *localnets = 0;
char *
getwire(void)
{
struct ifaddrs *ifa, *ifaddrs;
struct hostent *hp;
struct netent *np;
addrlist *al;
char *s, *netname = NULL;
if (getifaddrs(&ifaddrs))
return strdup(NO_SUBNET);
for (ifa = ifaddrs; ifa != NULL; ifa = ifa -> ifa_next) {
/*
* Ignore non-AF_INET interfaces as well as any that
* are down or loopback.
*/
if (ifa->ifa_addr == NULL ||
ifa->ifa_addr->sa_family != AF_INET ||
!(ifa->ifa_flags & IFF_UP) ||
(ifa->ifa_flags & IFF_LOOPBACK))
continue;
/*
* Add interface to local network list
*/
al = ALLOC(addrlist);
al->ip_addr =
((struct sockaddr_in *)ifa->ifa_addr)->sin_addr.s_addr;
al->ip_mask =
((struct sockaddr_in *)ifa->ifa_netmask)->sin_addr.s_addr;
al->ip_next = localnets;
localnets = al;
if (netname == NULL) {
in_addr_t net;
in_addr_t mask;
in_addr_t subnet;
in_addr_t subnetshift;
char dq[20];
/*
* Figure out the subnet's network address
*/
subnet = al->ip_addr & al->ip_mask;
#ifdef IN_CLASSA
subnet = ntohl(subnet);
if (IN_CLASSA(subnet)) {
mask = IN_CLASSA_NET;
subnetshift = 8;
} else if (IN_CLASSB(subnet)) {
mask = IN_CLASSB_NET;
subnetshift = 8;
} else {
mask = IN_CLASSC_NET;
subnetshift = 4;
}
/*
* If there are more bits than the standard mask
* would suggest, subnets must be in use.
* Guess at the subnet mask, assuming reasonable
* width subnet fields.
* XXX: Or-in at least 1 byte's worth of 1s to make
* sure the top bits remain set.
*/
while (subnet &~ mask)
mask = (mask >> subnetshift) | 0xff000000;
net = subnet & mask;
while ((mask & 1) == 0)
mask >>= 1, net >>= 1;
/*
* Now get a usable name.
* First use the network database,
* then the host database,
* and finally just make a dotted quad.
*/
np = getnetbyaddr(net, AF_INET);
#else
/* This is probably very wrong. */
np = getnetbyaddr(subnet, AF_INET);
#endif /* IN_CLASSA */
if (np)
s = np->n_name;
else {
subnet = al->ip_addr & al->ip_mask;
hp = gethostbyaddr((char *) &subnet, 4, AF_INET);
if (hp)
s = hp->h_name;
else
s = inet_dquad(dq, sizeof(dq), subnet);
}
netname = strdup(s);
}
}
freeifaddrs(ifaddrs);
return (netname ? netname : strdup(NO_SUBNET));
}
/*
* Determine whether a network is on a local network
* (addr) is in network byte order.
*/
int
islocalnet(in_addr_t addr)
{
addrlist *al;
for (al = localnets; al; al = al->ip_next)
if (((addr ^ al->ip_addr) & al->ip_mask) == 0)
return TRUE;
#ifdef DEBUG
{ char buf[16];
plog(XLOG_INFO, "%s is on a remote network", inet_dquad(buf, sizeof(buf), addr));
}
#endif
return FALSE;
}
|
