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
245
246
247
248
249
250
251
252
253
254
|
/* LAN_discovery.c
*
* LAN discovery implementation.
*
* Copyright (C) 2013 Tox project All Rights Reserved.
*
* This file is part of Tox.
*
* Tox 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, either version 3 of the License, or
* (at your option) any later version.
*
* Tox 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 Tox. If not, see <http://www.gnu.org/licenses/>.
*
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "LAN_discovery.h"
#include "util.h"
#define MAX_INTERFACES 16
#ifdef __linux
static int broadcast_count = -1;
static IP_Port broadcast_ip_port[MAX_INTERFACES];
static void fetch_broadcast_info(uint16_t port)
{
/* Not sure how many platforms this will run on,
* so it's wrapped in __linux for now.
* Definitely won't work like this on Windows...
*/
broadcast_count = 0;
sock_t sock = 0;
if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0)
return;
/* Configure ifconf for the ioctl call. */
struct ifreq i_faces[MAX_INTERFACES];
memset(i_faces, 0, sizeof(struct ifreq) * MAX_INTERFACES);
struct ifconf ifconf;
ifconf.ifc_buf = (char *)i_faces;
ifconf.ifc_len = sizeof(i_faces);
if (ioctl(sock, SIOCGIFCONF, &ifconf) < 0) {
close(sock);
return;
}
/* ifconf.ifc_len is set by the ioctl() to the actual length used;
* on usage of the complete array the call should be repeated with
* a larger array, not done (640kB and 16 interfaces shall be
* enough, for everybody!)
*/
int i, count = ifconf.ifc_len / sizeof(struct ifreq);
for (i = 0; i < count; i++) {
/* there are interfaces with are incapable of broadcast */
if (ioctl(sock, SIOCGIFBRDADDR, &i_faces[i]) < 0)
continue;
/* moot check: only AF_INET returned (backwards compat.) */
if (i_faces[i].ifr_broadaddr.sa_family != AF_INET)
continue;
struct sockaddr_in *sock4 = (struct sockaddr_in *)&i_faces[i].ifr_broadaddr;
if (broadcast_count >= MAX_INTERFACES)
return;
IP_Port *ip_port = &broadcast_ip_port[broadcast_count];
ip_port->ip.family = AF_INET;
ip_port->ip.ip4.in_addr = sock4->sin_addr;
ip_port->port = port;
broadcast_count++;
}
close(sock);
}
/* Send packet to all IPv4 broadcast addresses
*
* return 1 if sent to at least one broadcast target.
* return 0 on failure to find any valid broadcast target.
*/
static uint32_t send_broadcasts(Networking_Core *net, uint16_t port, uint8_t *data, uint16_t length)
{
/* fetch only once? on every packet? every X seconds?
* old: every packet, new: once */
if (broadcast_count < 0)
fetch_broadcast_info(port);
if (!broadcast_count)
return 0;
int i;
for (i = 0; i < broadcast_count; i++)
sendpacket(net, broadcast_ip_port[i], data, 1 + crypto_box_PUBLICKEYBYTES);
return 1;
}
#endif /* __linux */
/* Return the broadcast ip. */
static IP broadcast_ip(sa_family_t family_socket, sa_family_t family_broadcast)
{
IP ip;
ip_reset(&ip);
if (family_socket == AF_INET6) {
if (family_broadcast == AF_INET6) {
ip.family = AF_INET6;
/* FF02::1 is - according to RFC 4291 - multicast all-nodes link-local */
/* FE80::*: MUST be exact, for that we would need to look over all
* interfaces and check in which status they are */
ip.ip6.uint8[ 0] = 0xFF;
ip.ip6.uint8[ 1] = 0x02;
ip.ip6.uint8[15] = 0x01;
} else if (family_broadcast == AF_INET) {
ip.family = AF_INET6;
ip.ip6.uint32[0] = 0;
ip.ip6.uint32[1] = 0;
ip.ip6.uint32[2] = htonl(0xFFFF);
ip.ip6.uint32[3] = INADDR_BROADCAST;
}
} else if (family_socket == AF_INET) {
if (family_broadcast == AF_INET) {
ip.family = AF_INET;
ip.ip4.uint32 = INADDR_BROADCAST;
}
}
return ip;
}
/* return 0 if ip is a LAN ip.
* return -1 if it is not.
*/
int LAN_ip(IP ip)
{
if (ip.family == AF_INET) {
IP4 ip4 = ip.ip4;
/* Loopback. */
if (ip4.uint8[0] == 127)
return 0;
/* 10.0.0.0 to 10.255.255.255 range. */
if (ip4.uint8[0] == 10)
return 0;
/* 172.16.0.0 to 172.31.255.255 range. */
if (ip4.uint8[0] == 172 && ip4.uint8[1] >= 16 && ip4.uint8[1] <= 31)
return 0;
/* 192.168.0.0 to 192.168.255.255 range. */
if (ip4.uint8[0] == 192 && ip4.uint8[1] == 168)
return 0;
/* 169.254.1.0 to 169.254.254.255 range. */
if (ip4.uint8[0] == 169 && ip4.uint8[1] == 254 && ip4.uint8[2] != 0
&& ip4.uint8[2] != 255)
return 0;
} else if (ip.family == AF_INET6) {
/* autogenerated for each interface: FE80::* (up to FEBF::*)
FF02::1 is - according to RFC 4291 - multicast all-nodes link-local */
if (((ip.ip6.uint8[0] == 0xFF) && (ip.ip6.uint8[1] < 3) && (ip.ip6.uint8[15] == 1)) ||
((ip.ip6.uint8[0] == 0xFE) && ((ip.ip6.uint8[1] & 0xC0) == 0x80)))
return 0;
/* embedded IPv4-in-IPv6 */
if (IN6_IS_ADDR_V4MAPPED(&ip.ip6.in6_addr)) {
IP ip4;
ip4.family = AF_INET;
ip4.ip4.uint32 = ip.ip6.uint32[3];
return LAN_ip(ip4);
}
/* localhost in IPv6 (::1) */
if (IN6_IS_ADDR_LOOPBACK(&ip.ip6.in6_addr))
return 0;
}
return -1;
}
static int handle_LANdiscovery(void *object, IP_Port source, uint8_t *packet, uint32_t length)
{
DHT *dht = object;
if (LAN_ip(source.ip) == -1)
return 1;
if (length != crypto_box_PUBLICKEYBYTES + 1)
return 1;
DHT_bootstrap(dht, source, packet + 1);
return 0;
}
int send_LANdiscovery(uint16_t port, Net_Crypto *c)
{
uint8_t data[crypto_box_PUBLICKEYBYTES + 1];
data[0] = NET_PACKET_LAN_DISCOVERY;
id_copy(data + 1, c->self_public_key);
#ifdef __linux
send_broadcasts(c->lossless_udp->net, port, data, 1 + crypto_box_PUBLICKEYBYTES);
#endif
int res = -1;
IP_Port ip_port;
ip_port.port = port;
/* IPv6 multicast */
if (c->lossless_udp->net->family == AF_INET6) {
ip_port.ip = broadcast_ip(AF_INET6, AF_INET6);
if (ip_isset(&ip_port.ip))
if (sendpacket(c->lossless_udp->net, ip_port, data, 1 + crypto_box_PUBLICKEYBYTES) > 0)
res = 1;
}
/* IPv4 broadcast (has to be IPv4-in-IPv6 mapping if socket is AF_INET6 */
ip_port.ip = broadcast_ip(c->lossless_udp->net->family, AF_INET);
if (ip_isset(&ip_port.ip))
if (sendpacket(c->lossless_udp->net, ip_port, data, 1 + crypto_box_PUBLICKEYBYTES))
res = 1;
return res;
}
void LANdiscovery_init(DHT *dht)
{
networking_registerhandler(dht->c->lossless_udp->net, NET_PACKET_LAN_DISCOVERY, &handle_LANdiscovery, dht);
}
|
