iodine/dnstun.c
2006-06-11 12:18:49 +00:00

188 lines
3.6 KiB
C

/*
* Copyright (c) 2006 Bjorn Andersson <flex@kryo.se>, Erik Ekman <yarrick@kryo.se>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <err.h>
#include <pwd.h>
#include <arpa/inet.h>
#include <zlib.h>
#include "tun.h"
#include "dns.h"
#ifndef MAX
#define MAX(a,b) ((a)>(b)?(a):(b))
#endif
#define FRAMESIZE (64*1024)
int running = 1;
static void
sigint(int sig) {
running = 0;
}
static int
tunnel(int tun_fd, int dns_fd)
{
int i;
int read;
fd_set fds;
struct timeval tv;
struct tun_frame *frame;
long buflen;
char buf[64*1024];
frame = malloc(FRAMESIZE);
while (running) {
tv.tv_sec = 1;
tv.tv_usec = 0;
FD_ZERO(&fds);
if (!dns_sending())
FD_SET(tun_fd, &fds);
FD_SET(dns_fd, &fds);
i = select(MAX(tun_fd, dns_fd) + 1, &fds, NULL, NULL, &tv);
if(i < 0) {
if (running) {
warn("select");
}
return 1;
}
if(i == 0) {
dns_ping(dns_fd);
} else {
if(FD_ISSET(tun_fd, &fds)) {
read = read_tun(tun_fd, frame, FRAMESIZE);
if (read > 0) {
printf("Got data on tun! %d bytes\n", read);
buflen = sizeof(buf);
compress2(buf, &buflen, frame->data, read - 4, 9);
dns_handle_tun(dns_fd, buf, buflen);
}
}
if(FD_ISSET(dns_fd, &fds)) {
read = dns_read(dns_fd, buf, FRAMESIZE-4);
if (read > 0) {
buflen = 64*1024-4;
uncompress(frame->data, &buflen, buf, read);
printf("Got data on dns! %d bytes\n", read);
frame->flags = htons(0x0000);
#ifdef LINUX
frame->proto = htons(0x0800); // Linux wants ETH_P_IP
#else
frame->proto = htons(0x0002); // BSD wants AF_INET as long word
#endif
write_tun(tun_fd, frame, buflen + 4);
if (!dns_sending()) {
dns_ping(dns_fd);
}
}
}
}
}
free(frame);
return 0;
}
extern char *__progname;
static void
usage() {
printf("Usage: %s [-u user] nameserver topdomain\n", __progname);
exit(2);
}
int
main(int argc, char **argv)
{
int tun_fd;
int dns_fd;
int choice;
char *username;
struct passwd *pw;
username = NULL;
while ((choice = getopt(argc, argv, "u:")) != -1) {
switch(choice) {
case 'u':
username = optarg;
break;
default:
usage();
break;
}
}
argc -= optind;
argv += optind;
if (argc != 2) {
usage();
}
if(username) {
pw = getpwnam(username);
if (!pw) {
printf("User %s does not exist!\n", username);
usage();
}
}
tun_fd = open_tun();
dns_fd = open_dns(argv[0], argv[1]);
printf("Sending queries for %s to %s\n", argv[1], argv[0]);
signal(SIGINT, sigint);
if (username) {
if (setgid(pw->pw_gid) < 0 || setuid(pw->pw_uid) < 0) {
printf("Could not switch to user %s!\n", username);
usage();
}
printf("Now running as user %s\n", username);
}
tunnel(tun_fd, dns_fd);
printf("Closing tunnel\n");
close_dns(dns_fd);
close_tun(tun_fd);
return 0;
}