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
|
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <errno.h>
#include <time.h>
#include <unistd.h>
#include <netdb.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/select.h>
#include "xmalloc.h"
#include "die.h"
#include "sock.h"
#include "stun.h"
#define BINDING_REQUEST 0x0001
#define BINDING_RESPONSE 0x0101
#define MAPPED_ADDRESS 0x0001
#define TIMEOUT 5000
#define REQUEST_LEN 20
#define ID_COOKIE_FIELD htonl(((int) 'a' << 24) + \
((int) 'c' << 16) + \
((int) 'd' << 8) + \
(int) 'c')
struct stun_header {
uint16_t type;
uint16_t len;
uint32_t magic_cookie;
uint32_t transid[3];
};
struct stun_attrib {
uint16_t type;
uint16_t len;
uint8_t *value;
};
struct stun_mapped_addr {
uint8_t none;
uint8_t family;
uint16_t port;
uint32_t ip;
};
static int stun_test(const char *server_ip, int server_port,
int tun_port)
{
int ret, sock;
uint8_t pkt[256];
uint8_t rpkt[256];
size_t len, off, max;
struct in_addr in;
struct timeval timeout;
struct stun_header *hdr, *rhdr;
struct stun_attrib *attr;
struct stun_mapped_addr *addr;
struct sockaddr_in saddr, daddr;
fd_set fdset;
if (!server_ip)
return -EINVAL;
sock = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
if (sock < 0)
panic("Cannot obtain socket!\n");
set_reuseaddr(sock);
saddr.sin_family = PF_INET;
saddr.sin_port = htons(tun_port);
saddr.sin_addr.s_addr = INADDR_ANY;
ret = bind(sock, (struct sockaddr *) &saddr, sizeof(saddr));
if (ret)
panic("Cannot bind udp socket!\n");
len = REQUEST_LEN;
hdr = (struct stun_header *) pkt;
hdr->type = htons(BINDING_REQUEST);
hdr->len = 0;
hdr->magic_cookie = ID_COOKIE_FIELD;
hdr->transid[0] = htonl(rand());
hdr->transid[1] = htonl(rand());
hdr->transid[2] = htonl(rand());
daddr.sin_family = PF_INET;
daddr.sin_port = htons(server_port);
daddr.sin_addr.s_addr = inet_addr(server_ip);
ret = sendto(sock, pkt, len, 0, (struct sockaddr *) &daddr,
sizeof(daddr));
if (ret != len) {
printf("Error sending request (%s)!\n", strerror(errno));
return -EIO;
}
timeout.tv_sec = TIMEOUT / 1000;
timeout.tv_usec = (TIMEOUT % 1000) * 1000;
FD_ZERO(&fdset);
FD_SET(sock, &fdset);
ret = select(sock + 1, &fdset, NULL, NULL, &timeout);
if (ret <= 0) {
printf("STUN server timeout!\n");
return -EIO;
}
memset(rpkt, 0, sizeof(rpkt));
len = read(sock, rpkt, sizeof(rpkt));
close(sock);
if (len < REQUEST_LEN) {
printf("Bad STUN response (%s)!\n", strerror(errno));
return -EIO;
}
rhdr = (struct stun_header *) rpkt;
if (ntohs(rhdr->type) != BINDING_RESPONSE) {
printf("Wrong STUN response type!\n");
return -EIO;
}
if (rhdr->len == 0) {
printf("No attributes in STUN response!\n");
return -EIO;
}
if (rhdr->magic_cookie != hdr->magic_cookie ||
rhdr->transid[0] != hdr->transid[0] ||
rhdr->transid[1] != hdr->transid[1] ||
rhdr->transid[2] != hdr->transid[2]) {
printf("Got wrong STUN transaction id!\n");
return -EIO;
}
off = REQUEST_LEN;
max = ntohs(rhdr->len) + REQUEST_LEN;
while (off + 8 < max) {
attr = (struct stun_attrib *) (rpkt + off);
if (ntohs(attr->type) != MAPPED_ADDRESS)
goto next;
addr = (struct stun_mapped_addr *) (rpkt + off + 4);
if (addr->family != 0x1)
break;
in.s_addr = addr->ip;
printf("Public mapping %s:%u!\n",
inet_ntoa(in), ntohs(addr->port));
break;
next:
off += 4;
off += ntohs(attr->len);
}
return 0;
}
int print_stun_probe(char *server, int sport, int tport)
{
char *address;
struct hostent *hp;
printf("STUN on %s:%u\n", server, sport);
srand(time(NULL));
hp = gethostbyname(server);
if (!hp)
return -EIO;
address = inet_ntoa(*(struct in_addr *) hp->h_addr_list[0]);
return stun_test(address, sport, tport);
}
|
