static void apply_bpf(int sock, uint16_t port, uint32_t ip)
{
struct sock_filter filter[] = {
BPF_STMT(BPF_LD + BPF_W + BPF_ABS, 12 /* src ip */),
BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ip, 0, 5),
BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 20 /* src port */),
BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, PORT, 0, 3),
BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 22 /* dst port */),
BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, port, 0, 1),
BPF_STMT(BPF_RET + BPF_K, -1),
BPF_STMT(BPF_RET + BPF_K, 0)
};
struct sock_fprog filter_prog = {
.len = sizeof(filter) / sizeof(filter[0]),
.filter = filter
};
if (setsockopt(sock, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog, sizeof(filter_prog)) < 0) {
perror("setsockopt(bpf)");
exit(errno);
}
}
int main(int argc, char *argv[])
{
struct sockaddr_in addr = {
.sin_family = AF_INET
};
struct {
struct udphdr udp;
uint8_t my_pubkey[32];
uint8_t their_pubkey[32];
} __attribute__((packed)) packet = {
.udp = {
.len = htons(sizeof(packet)),
.dest = htons(PORT)
}
};
struct {
struct iphdr iphdr;
struct udphdr udp;
uint32_t ip;
uint16_t port;
} __attribute__((packed)) reply;
ssize_t len;
int sock, i;
bool repeat;
struct hostent *ent;
const char *server = argv[1], *interface = argv[2];
if (argc < 3) {
fprintf(stderr, "Usage: %s SERVER WIREGUARD_INTERFACE\nExample:\n %s demo.wireguard.com wg0\n", argv[0], argv[0]);
return EINVAL;
}
if (getuid() != 0) {
fprintf(stderr, "Must be root!\n");
return EPERM;
}
ent = gethostbyname2(server, AF_INET);
if (!ent) {
herror("gethostbyname2");
return h_errno;
}
addr.sin_addr = *(struct in_addr *)ent->h_addr;
read_peers(interface);
cmd("ip link set %s up", interface);
unbase64(packet.my_pubkey, cmd("wg show %s public-key", interface));
packet.udp.source = htons(atoi(cmd("wg show %s listen-port", interface)));
/* We use raw sockets so that the WireGuard interface can actually own the real socket. */
sock = socket(AF_INET, SOCK_RAW, IPPROTO_UDP);
if (sock < 0) {
perror("socket");
return errno;
}
apply_bpf(sock, ntohs(packet.udp.source), ntohl(addr.sin_addr.s_addr));
check_again:
repeat = false;
for (i = 0; i < total_peers; ++i) {
if (peers[i].have_seen)
continue;
printf("[+] Requesting IP and port of %s: ", peers[i].base64_key);
unbase64(packet.their_pubkey, peers[i].base64_key);
if (sendto(sock, &packet, sizeof(packet), 0, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
putchar('\n');
perror("sendto");
return errno;
}
len = recv(sock, &reply, sizeof(reply), 0);
if (len < 0) {
putchar('\n');
perror("recv");
return errno;
}
if (len != sizeof(reply)) {
printf("server does not yet have it\n");
repeat = true;
} else {
printf("%s:%d\n", inet_ntoa(*(struct in_addr *)&reply.ip), ntohs(reply.port));
peers[i].have_seen = true;
cmd("wg set %s peer %s persistent-keepalive 25 endpoint %s:%d", interface, peers[i].base64_key, inet_ntoa(*(struct in_addr *)&reply.ip), ntohs(reply.port));
}
}
if (repeat) {
sleep(2);
goto check_again;
}
close(sock);
return 0;
}
void iqconverter_float_process(iqconverter_float_t *cnv, float *samples, int len)
{
apply_bpf(cnv, samples, len);
translate_fs_4(cnv, samples, len);
}