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
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
|
/* dnsmasq is Copyright (c) 2000-2020 Simon Kelley
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 dated June, 1991, or
(at your option) version 3 dated 29 June, 2007.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "dnsmasq.h"
/* Time between forced re-loads from kernel. */
#define INTERVAL 90
#define ARP_MARK 0
#define ARP_FOUND 1 /* Confirmed */
#define ARP_NEW 2 /* Newly created */
#define ARP_EMPTY 3 /* No MAC addr */
struct arp_record {
unsigned short hwlen, status;
int family;
unsigned char hwaddr[DHCP_CHADDR_MAX];
union all_addr addr;
struct arp_record *next;
};
static struct arp_record *arps = NULL, *old = NULL, *freelist = NULL;
static time_t last = 0;
static int filter_mac(int family, char *addrp, char *mac, size_t maclen, void *parmv)
{
struct arp_record *arp;
(void)parmv;
if (maclen > DHCP_CHADDR_MAX)
return 1;
/* Look for existing entry */
for (arp = arps; arp; arp = arp->next)
{
if (family != arp->family || arp->status == ARP_NEW)
continue;
if (family == AF_INET)
{
if (arp->addr.addr4.s_addr != ((struct in_addr *)addrp)->s_addr)
continue;
}
else
{
if (!IN6_ARE_ADDR_EQUAL(&arp->addr.addr6, (struct in6_addr *)addrp))
continue;
}
if (arp->status == ARP_EMPTY)
{
/* existing address, was negative. */
arp->status = ARP_NEW;
arp->hwlen = maclen;
memcpy(arp->hwaddr, mac, maclen);
}
else if (arp->hwlen == maclen && memcmp(arp->hwaddr, mac, maclen) == 0)
/* Existing entry matches - confirm. */
arp->status = ARP_FOUND;
else
continue;
break;
}
if (!arp)
{
/* New entry */
if (freelist)
{
arp = freelist;
freelist = freelist->next;
}
else if (!(arp = whine_malloc(sizeof(struct arp_record))))
return 1;
arp->next = arps;
arps = arp;
arp->status = ARP_NEW;
arp->hwlen = maclen;
arp->family = family;
memcpy(arp->hwaddr, mac, maclen);
if (family == AF_INET)
arp->addr.addr4.s_addr = ((struct in_addr *)addrp)->s_addr;
else
memcpy(&arp->addr.addr6, addrp, IN6ADDRSZ);
}
return 1;
}
/* If in lazy mode, we cache absence of ARP entries. */
int find_mac(union mysockaddr *addr, unsigned char *mac, int lazy, time_t now)
{
struct arp_record *arp, *tmp, **up;
int updated = 0;
again:
/* If the database is less then INTERVAL old, look in there */
if (difftime(now, last) < INTERVAL)
{
/* addr == NULL -> just make cache up-to-date */
if (!addr)
return 0;
for (arp = arps; arp; arp = arp->next)
{
if (addr->sa.sa_family != arp->family)
continue;
if (arp->family == AF_INET &&
arp->addr.addr4.s_addr != addr->in.sin_addr.s_addr)
continue;
if (arp->family == AF_INET6 &&
!IN6_ARE_ADDR_EQUAL(&arp->addr.addr6, &addr->in6.sin6_addr))
continue;
/* Only accept positive entries unless in lazy mode. */
if (arp->status != ARP_EMPTY || lazy || updated)
{
if (mac && arp->hwlen != 0)
memcpy(mac, arp->hwaddr, arp->hwlen);
return arp->hwlen;
}
}
}
/* Not found, try the kernel */
if (!updated)
{
updated = 1;
last = now;
/* Mark all non-negative entries */
for (arp = arps; arp; arp = arp->next)
if (arp->status != ARP_EMPTY)
arp->status = ARP_MARK;
iface_enumerate(AF_UNSPEC, NULL, filter_mac);
/* Remove all unconfirmed entries to old list. */
for (arp = arps, up = &arps; arp; arp = tmp)
{
tmp = arp->next;
if (arp->status == ARP_MARK)
{
*up = arp->next;
arp->next = old;
old = arp;
}
else
up = &arp->next;
}
goto again;
}
/* record failure, so we don't consult the kernel each time
we're asked for this address */
if (freelist)
{
arp = freelist;
freelist = freelist->next;
}
else
arp = whine_malloc(sizeof(struct arp_record));
if (arp)
{
arp->next = arps;
arps = arp;
arp->status = ARP_EMPTY;
arp->family = addr->sa.sa_family;
arp->hwlen = 0;
if (addr->sa.sa_family == AF_INET)
arp->addr.addr4.s_addr = addr->in.sin_addr.s_addr;
else
memcpy(&arp->addr.addr6, &addr->in6.sin6_addr, IN6ADDRSZ);
}
return 0;
}
int do_arp_script_run(void)
{
struct arp_record *arp;
/* Notify any which went, then move to free list */
if (old)
{
#ifdef HAVE_SCRIPT
if (option_bool(OPT_SCRIPT_ARP))
queue_arp(ACTION_ARP_DEL, old->hwaddr, old->hwlen, old->family, &old->addr);
#endif
arp = old;
old = arp->next;
arp->next = freelist;
freelist = arp;
return 1;
}
for (arp = arps; arp; arp = arp->next)
if (arp->status == ARP_NEW)
{
#ifdef HAVE_SCRIPT
if (option_bool(OPT_SCRIPT_ARP))
queue_arp(ACTION_ARP, arp->hwaddr, arp->hwlen, arp->family, &arp->addr);
#endif
arp->status = ARP_FOUND;
return 1;
}
return 0;
}
|
