mirror of
https://github.com/yarrick/iodine.git
synced 2024-09-07 19:47:03 +00:00
301 lines
5.6 KiB
C
301 lines
5.6 KiB
C
/*
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* Copyright (c) 2006 Bjorn Andersson <flex@kryo.se>, Erik Ekman <yarrick@kryo.se>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include <stdio.h>
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#include <stdint.h>
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#include <stdlib.h>
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#include <string.h>
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#include <signal.h>
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#include <unistd.h>
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <err.h>
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#include <pwd.h>
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#include <arpa/inet.h>
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#include <zlib.h>
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#include "tun.h"
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#include "structs.h"
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#include "dns.h"
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#ifndef MAX
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#define MAX(a,b) ((a)>(b)?(a):(b))
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#endif
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int running = 1;
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int tun_fd;
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int dns_fd;
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static void
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sighandler(int sig) {
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running = 0;
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}
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static int
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tunnel(int tun_fd, int dns_fd)
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{
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int i;
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int read;
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fd_set fds;
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struct timeval tv;
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char in[64*1024];
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long outlen;
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char out[64*1024];
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while (running) {
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tv.tv_sec = 1;
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tv.tv_usec = 0;
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FD_ZERO(&fds);
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if (!dns_sending())
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FD_SET(tun_fd, &fds);
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FD_SET(dns_fd, &fds);
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i = select(MAX(tun_fd, dns_fd) + 1, &fds, NULL, NULL, &tv);
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if(i < 0) {
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if (running) {
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warn("select");
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}
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return 1;
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}
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if(i == 0) {
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dns_ping(dns_fd);
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} else {
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if(FD_ISSET(tun_fd, &fds)) {
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read = read_tun(tun_fd, in, sizeof(in));
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if(read <= 0)
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continue;
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outlen = sizeof(out);
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compress2(out, &outlen, in, read, 9);
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dns_handle_tun(dns_fd, out, outlen);
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}
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if(FD_ISSET(dns_fd, &fds)) {
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read = dns_read(dns_fd, in, sizeof(in));
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if (read <= 0)
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continue;
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outlen = sizeof(out);
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uncompress(out, &outlen, in, read);
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write_tun(tun_fd, out, outlen);
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if (!dns_sending())
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dns_ping(dns_fd);
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}
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}
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}
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return 0;
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}
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static int
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handshake(int dns_fd)
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{
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int i;
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int r;
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char *p;
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int mtu;
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int read;
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fd_set fds;
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int timeout;
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char in[4096];
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struct timeval tv;
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timeout = 1;
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for (i=0; running && i<5 ;i++) {
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tv.tv_sec = timeout++;
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tv.tv_usec = 0;
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dns_handshake(dns_fd);
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FD_ZERO(&fds);
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FD_SET(dns_fd, &fds);
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r = select(dns_fd + 1, &fds, NULL, NULL, &tv);
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if(r > 0) {
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read = dns_read(dns_fd, in, sizeof(in));
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if(read < 0) {
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perror("read");
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continue;
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}
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if (read > 0) {
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p = strchr(in, '-');
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if (p) {
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*p++ = '\0';
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mtu = atoi(p);
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if (tun_setip(in) == 0 && tun_setmtu(atoi(p)) == 0)
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return 0;
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else
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warn("Received handshake but b0rk");
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}
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}
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}
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printf("Retrying...\n");
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}
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return 1;
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}
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extern char *__progname;
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static void
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usage() {
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printf("Usage: %s [-v] [-h] [-f] [-u user] [-t chrootdir] [-d device]"
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"nameserver topdomain\n", __progname);
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exit(2);
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}
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static void
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help() {
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printf("iodine IP over DNS tunneling client\n");
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printf("Usage: %s [-v] [-h] [-f] [-u user] [-t chrootdir] [-d device] "
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"nameserver topdomain\n", __progname);
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printf(" -v to print version info and exit\n");
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printf(" -h to print this help and exit\n");
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printf(" -f to keep running in foreground\n");
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printf(" -u name to drop privileges and run as user 'name'\n");
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printf(" -t dir to chroot to directory dir\n");
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printf(" -d device to set tunnel device name\n");
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printf("nameserver is the IP number of the relaying nameserver\n");
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printf("topdomain is the FQDN that is delegated to the tunnel endpoint.\n");
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exit(0);
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}
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static void
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version() {
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char *svnver = "$Rev$ from $Date$";
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printf("iodine IP over DNS tunneling client\n");
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printf("SVN version: %s\n", svnver);
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exit(0);
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}
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int
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main(int argc, char **argv)
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{
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int choice;
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char *newroot;
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char *username;
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char *device;
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int foreground;
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struct passwd *pw;
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newroot = NULL;
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username = NULL;
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device = NULL;
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foreground = 0;
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while ((choice = getopt(argc, argv, "vfhu:t:d:")) != -1) {
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switch(choice) {
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case 'v':
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version();
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break;
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case 'f':
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foreground = 1;
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break;
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case 'h':
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help();
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break;
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case 'u':
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username = optarg;
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break;
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case 't':
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newroot = optarg;
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break;
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case 'd':
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device = optarg;
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break;
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default:
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usage();
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break;
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}
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}
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if (geteuid() != 0) {
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printf("Run as root and you'll be happy.\n");
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usage();
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}
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argc -= optind;
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argv += optind;
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if (argc != 2)
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usage();
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if(username) {
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pw = getpwnam(username);
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if (!pw) {
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printf("User %s does not exist!\n", username);
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usage();
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}
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}
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if ((tun_fd = open_tun(device)) == -1)
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goto cleanup1;
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if ((dns_fd = open_dns(argv[1], 0)) == -1)
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goto cleanup2;
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if (dns_settarget(argv[0]) == -1)
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goto cleanup2;
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printf("Sending queries for %s to %s\n", argv[1], argv[0]);
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signal(SIGINT, sighandler);
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signal(SIGTERM, sighandler);
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if(handshake(dns_fd))
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goto cleanup2;
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if (newroot) {
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if (chroot(newroot) != 0 || chdir("/") != 0)
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err(1, "%s", newroot);
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seteuid(geteuid());
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setuid(getuid());
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}
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if (!foreground) {
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printf("Detaching from terminal...\n");
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daemon(0, 0);
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umask(0);
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alarm(0);
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}
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if (username) {
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if (setgid(pw->pw_gid) < 0 || setuid(pw->pw_uid) < 0) {
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printf("Could not switch to user %s!\n", username);
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usage();
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}
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}
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tunnel(tun_fd, dns_fd);
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cleanup2:
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close_dns(dns_fd);
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close_tun(tun_fd);
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cleanup1:
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return 0;
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}
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