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/*
This file is part of GNUnet.
(C) 2010 Christian Grothoff
GNUnet is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published
by the Free Software Foundation; either version 3, or (at your
option) any later version.
GNUnet is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with GNUnet; see the file COPYING. If not, write to the
Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.
*/
/**
* @file vpn/gnunet-helper-hijack-dns.c
* @brief
* @author Philipp Tölke
*/
#define _GNU_SOURCE
#include <arpa/inet.h>
#include <string.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <gnunet_common.h>
int fork_and_exec(char* file, char* cmd[]) {
pid_t pid = fork();
if (pid < 0) {
fprintf(stderr, "could not fork: %m\n");
return GNUNET_SYSERR;
}
int st = 0;
if (pid == 0) {
execv(file, cmd);
} else {
waitpid(pid, &st, 0);
}
return WIFEXITED(st) && (WEXITSTATUS(st) == 0);
}
int main(int argc, char** argv) {
int delete = 0;
int port = 0;
if (argc < 2) return GNUNET_SYSERR;
if (strncmp(argv[1], "-d", 2) == 0) {
if (argc < 3) return GNUNET_SYSERR;
delete = 1;
port = atoi(argv[2]);
} else {
port = atoi(argv[1]);
}
if (port == 0) return GNUNET_SYSERR;
struct stat s;
if (stat("/sbin/iptables", &s) < 0) {
fprintf(stderr, "stat on /sbin/iptables failed: %m\n");
return GNUNET_SYSERR;
}
char localport[7];
snprintf(localport, 7, "%d", port);
int r;
if (delete) {
r = fork_and_exec("/sbin/iptables", (char*[]){"iptables", "-t", "nat", "-D", "OUTPUT", "-p", "udp", "--sport", localport, "--dport", "53", "-j", "ACCEPT", NULL});
r = fork_and_exec("/sbin/iptables", (char*[]){"iptables", "-t", "nat", "-D", "OUTPUT", "-p", "udp", "--dport", "53", "-j", "DNAT", "--to-destination", "10.10.10.2:53", NULL});
} else {
r = fork_and_exec("/sbin/iptables", (char*[]){"iptables", "-t", "nat", "-I", "OUTPUT", "1", "-p", "udp", "--sport", localport, "--dport", "53", "-j", "ACCEPT", NULL});
r = fork_and_exec("/sbin/iptables", (char*[]){"iptables", "-t", "nat", "-I", "OUTPUT", "2", "-p", "udp", "--dport", "53", "-j", "DNAT", "--to-destination", "10.10.10.2:53", NULL});
}
if (r) return GNUNET_YES;
return GNUNET_SYSERR;
}
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