/*  
    VTun - Virtual Tunnel over TCP/IP network.

    Copyright (C) 1998-2000  Maxim Krasnyansky <max_mk@yahoo.com>

    VTun has been derived from VPPP package by Maxim Krasnyansky. 

    This program 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.

    This program 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.
 */

/*
 * $Id: tun_dev.c,v 1.5.2.1 2007/06/29 05:27:23 mtbishop Exp $
 */ 

#include "config.h"

#include <unistd.h>
#include <fcntl.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <stdarg.h>
#include <sys/time.h>
#include <sys/wait.h>
#include <syslog.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/sockio.h>
#include <sys/ioctl.h>
#include <errno.h>
#include <signal.h>
#include <stropts.h>
#include <net/if.h>
#include <net/if_tun.h>

#ifdef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif

#ifdef HAVE_NETINET_IN_SYSTM_H
#include <netinet/in_systm.h>
#endif

#ifdef HAVE_NETINET_IP_H
#include <netinet/ip.h>
#endif

#ifdef HAVE_NETINET_TCP_H
#include <netinet/tcp.h>
#endif

#include "vtun.h"
#include "lib.h"

static int ip_fd = -1;

/* 
 * Allocate TUN device, returns opened fd. 
 * Stores dev name in the first arg(must be large enough).
 */  
int tun_open(char *dev)
{
    int tun_fd, if_fd, muxid, ppa = -1;
    struct ifreq ifr;
    char *ptr;

    if( *dev ){
       ptr = dev;	
       while( *ptr && !isdigit((int)*ptr) ) ptr++; 
       ppa = atoi(ptr);
    }

    if( (ip_fd = open("/dev/udp", O_RDWR, 0)) < 0){
       syslog(LOG_ERR, "Can't open /dev/ip");
       return -1;
    }

    if( (tun_fd = open("/dev/tun", O_RDWR, 0)) < 0){
       syslog(LOG_ERR, "Can't open /dev/tun");
       return -1;
    }

    /* Assign a new PPA and get its unit number. */
    if( (ppa = ioctl(tun_fd, TUNNEWPPA, ppa)) < 0){
       syslog(LOG_ERR, "Can't assign new interface");
       return -1;
    }

    if( (if_fd = open("/dev/tun", O_RDWR, 0)) < 0){
       syslog(LOG_ERR, "Can't open /dev/tun (2)");
       return -1;
    }
    if(ioctl(if_fd, I_PUSH, "ip") < 0){
       syslog(LOG_ERR, "Can't push IP module");
       return -1;
    }

    /* Assign ppa according to the unit number returned by tun device */
    if(ioctl(if_fd, IF_UNITSEL, (char *)&ppa) < 0){
       syslog(LOG_ERR, "Can't set PPA %d", ppa);
       return -1;
    }
    if( (muxid = ioctl(ip_fd, I_PLINK, if_fd)) < 0){
       syslog(LOG_ERR, "Can't link TUN device to IP");
       return -1;
    }
    close(if_fd);    

    sprintf(dev, "tun%d", ppa);

    memset(&ifr, 0, sizeof(ifr));
    strcpy(ifr.ifr_name, dev);
    ifr.ifr_ip_muxid = muxid;

    if( ioctl(ip_fd, SIOCSIFMUXID, &ifr) < 0 ){
       ioctl(ip_fd, I_PUNLINK, muxid);
       syslog(LOG_ERR, "Can't set multiplexor id");
       return -1;
    }

    return tun_fd;
}

/* 
 * Close TUN device. 
 */  
int tun_close(int fd, char *dev)
{
    struct ifreq ifr;

    memset(&ifr, 0, sizeof(ifr));
    strcpy(ifr.ifr_name, dev);
    if( ioctl(ip_fd, SIOCGIFFLAGS, &ifr) < 0 ){
       syslog(LOG_ERR, "Can't get iface flags");
       return 0;
    }

    if( ioctl(ip_fd, SIOCGIFMUXID, &ifr) < 0 ){
       syslog(LOG_ERR, "Can't get multiplexor id");
       return 0;
    }

    if( ioctl(ip_fd, I_PUNLINK, ifr.ifr_ip_muxid) < 0 ){
       syslog(LOG_ERR, "Can't unlink interface");
       return 0;
    }

    close(ip_fd); close(fd);
    return 0;
}

int tun_write(int fd, char *buf, int len)
{
    struct strbuf sbuf;
    sbuf.len = len;      
    sbuf.buf = buf;      
    return putmsg(fd, NULL, &sbuf, 0) >=0 ? sbuf.len : -1;
}

int tun_read(int fd, char *buf, int len)
{
    struct strbuf sbuf;
    int f = 0;

    sbuf.maxlen = len;      
    sbuf.buf = buf;      
    return getmsg(fd, NULL, &sbuf, &f) >=0 ? sbuf.len : -1;
}