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itun.c
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itun.c
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/*
* Copyright (c) 2005 Sergey Chvalyuk <ant@unity.net>
* All Rights Reserved.
*
* This file is part of the Icmp Tunnel - ITun.
*
* ITun 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 2 of the License, or
* (at your option) any later version.
*
* ITun 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 Foobar; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place, Suite 330,
* Boston, MA 02111-1307 USA.
*/
#include <unistd.h>
#include <fcntl.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <linux/if.h>
#include <linux/if_tun.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <netinet/ip_icmp.h>
#include <arpa/inet.h>
#include "config.h"
int get_icmp(int,unsigned char *,int,struct sockaddr_in *,socklen_t *);
int send_icmp(int,unsigned char *,int,struct sockaddr_in *,socklen_t);
int tun_open(char *dev);
int main()
{
unsigned char buff[4096];
fd_set rset;
struct sockaddr_in addr;
struct sockaddr_in addr_recv;
int sock;
int ret;
socklen_t len = sizeof(struct sockaddr_in);
socklen_t len_recv = sizeof(struct sockaddr_in);
unsigned char dev[] = IFACE;
int tunfd;
if ((tunfd = tun_open(dev)) < 0)
{
perror("error: tun_open");
exit(1);
}
sprintf(buff,"%s %s %s pointopoint %s",IFCFG,IFACE,VPN_LOCAL_IP,VPN_REMOTE_IP);
if (system(buff) < 0)
{
perror("error: fork");
exit(1);
}
if ((sock = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP)) < 0)
{
perror("error: socket\n");
exit(1);
}
memset(&addr,0,sizeof(struct sockaddr_in));
addr.sin_family = AF_INET;
addr.sin_port = 0;
addr.sin_addr.s_addr = inet_addr(PEER_IP);
while(1)
{
FD_ZERO(&rset);
FD_SET(sock,&rset);
FD_SET(tunfd,&rset);
while ((ret = select(sock+1,&rset,NULL,NULL,NULL)) < 0 && errno == EINTR);
if (ret < 0)
{
perror("error: select");
exit(1);
}
if (FD_ISSET(sock,&rset))
{
if ((ret = get_icmp(sock,buff,sizeof(buff),&addr_recv,&len_recv)) > 0)
{
//printf("get icmp pkt ret = %d ip = %s\n",ret,inet_ntoa(addr_recv.sin_addr));
//print_DUMP(buff,ret);
write(tunfd,buff,ret);
}
}
if (FD_ISSET(tunfd,&rset))
{
ret = read(tunfd,buff,sizeof(buff));
send_icmp(sock,buff,ret,&addr,len);
//printf("send icmp pkt ret = %d ip = %s\n",ret,inet_ntoa(addr.sin_addr));
//print_DUMP(buff,ret);
}
}
return(0);
}