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#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);
memset(&saddr, 0, sizeof(saddr));
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));
goto close_error;
}
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");
goto close_error;
}
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;
close_error:
close(sock);
return -EIO;
}
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);
}
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