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
235
236
237
238
239
240
241
242
243
244
|
/*
* Copyright (c) 2018-2021, OARC, Inc.
* All rights reserved.
*
* 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 copyright holder 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 COPYRIGHT HOLDERS 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
* COPYRIGHT HOLDER 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.
*/
#include "config.h"
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include "dnscap_common.h"
static set_iaddr_t anonmask_set_iaddr = 0;
static logerr_t* logerr;
static int only_clients = 0, only_servers = 0, mask_port = 53, mask_v4 = 24, mask_v6 = 48;
static struct in_addr in4 = { INADDR_ANY };
static struct in6_addr in6 = IN6ADDR_ANY_INIT;
static uint32_t* in6p = (uint32_t*)&in6;
enum plugin_type anonmask_type()
{
return plugin_filter;
}
void usage(const char* msg)
{
fprintf(stderr, "anonmask.so usage error: %s\n", msg);
exit(1);
}
void anonmask_usage()
{
fprintf(stderr,
"\nanonmask.so options:\n"
"\t-? print these instructions and exit\n"
"\t-c Only mask clients (port != 53)\n"
"\t-s Only mask servers (port == 53)\n"
"\t-p <port> Set port for -c/-s masking, default 53\n"
"\t-4 <netmask> The /mask for IPv4 addresses, default /24\n"
"\t-6 <netmask> The /mask for IPv6 addresses, default /48\n");
}
void anonmask_extension(int ext, void* arg)
{
switch (ext) {
case DNSCAP_EXT_SET_IADDR:
anonmask_set_iaddr = (set_iaddr_t)arg;
break;
}
}
void anonmask_getopt(int* argc, char** argv[])
{
int c;
unsigned long ul;
char* p;
while ((c = getopt(*argc, *argv, "?csp:4:6:")) != EOF) {
switch (c) {
case 'c':
only_clients = 1;
break;
case 's':
only_servers = 1;
break;
case 'p':
ul = strtoul(optarg, &p, 0);
if (*p != '\0' || ul < 1U || ul > 65535U)
usage("port must be an integer 1..65535");
mask_port = (unsigned)ul;
break;
case '4':
ul = strtoul(optarg, &p, 0);
if (*p != '\0' || ul > 31U)
usage("IPv4 mask must be an integer 0..31");
mask_v4 = (unsigned)ul;
break;
case '6':
ul = strtoul(optarg, &p, 0);
if (*p != '\0' || ul > 127U)
usage("IPv6 mask must be an integer 0..127");
mask_v6 = (unsigned)ul;
break;
case '?':
anonmask_usage();
if (!optopt || optopt == '?') {
exit(0);
}
// fallthrough
default:
exit(1);
}
}
if (only_clients && only_servers) {
usage("-c and -s options are mutually exclusive");
}
if (mask_v4) {
in4.s_addr = htonl(0xffffffff << (32 - mask_v4));
}
if (mask_v6) {
if (mask_v6 <= 32) {
in6p[0] = htonl(0xffffffff << (32 - mask_v6));
} else if (mask_v6 <= 64) {
in6p[0] = 0xffffffff;
in6p[1] = htonl(0xffffffff << (64 - mask_v6));
} else if (mask_v6 <= 96) {
in6p[0] = 0xffffffff;
in6p[1] = 0xffffffff;
in6p[2] = htonl(0xffffffff << (96 - mask_v6));
} else {
in6p[0] = 0xffffffff;
in6p[1] = 0xffffffff;
in6p[2] = 0xffffffff;
in6p[3] = htonl(0xffffffff << (128 - mask_v6));
}
}
}
int anonmask_start(logerr_t* a_logerr)
{
logerr = a_logerr;
return 0;
}
void anonmask_stop()
{
}
int anonmask_open(my_bpftimeval ts)
{
return 0;
}
int anonmask_close(my_bpftimeval ts)
{
return 0;
}
int anonmask_filter(const char* descr, iaddr* from, iaddr* to, uint8_t proto, unsigned flags,
unsigned sport, unsigned dport, my_bpftimeval ts,
const u_char* pkt_copy, const unsigned olen,
const u_char* payload, const unsigned payloadlen)
{
uint32_t* p6;
for (;;) {
if (only_clients && sport == mask_port) {
from = 0;
break;
}
if (only_servers && sport != mask_port) {
from = 0;
break;
}
switch (from->af) {
case AF_INET:
from->u.a4.s_addr &= in4.s_addr;
break;
case AF_INET6:
p6 = (uint32_t*)&from->u.a6;
p6[0] &= in6p[0];
p6[1] &= in6p[1];
p6[2] &= in6p[2];
p6[3] &= in6p[3];
break;
default:
from = 0;
break;
}
break;
}
for (;;) {
if (only_clients && dport == mask_port) {
to = 0;
break;
}
if (only_servers && dport != mask_port) {
to = 0;
break;
}
switch (to->af) {
case AF_INET:
to->u.a4.s_addr &= in4.s_addr;
break;
case AF_INET6:
p6 = (uint32_t*)&to->u.a6;
p6[0] &= in6p[0];
p6[1] &= in6p[1];
p6[2] &= in6p[2];
p6[3] &= in6p[3];
break;
default:
to = 0;
break;
}
break;
}
if (anonmask_set_iaddr && (from || to)) {
anonmask_set_iaddr(from, to);
}
return 0;
}
|
