FreeBSD-5.3/sbin/nos-tun/nos-tun.c
/*
* Copyright (c) 1996, Nickolay Dudorov
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice unmodified, this list of conditions, and the following
* disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
*/
/*
* 'nos-tun' program configure tunN interface as a point-to-point
* connection with two "pseudo"-addresses between this host and
* 'target'.
*
* It uses Ip-over-Ip incapsulation ( protocol number 94 - IPIP)
* (known as NOS-incapsulation in CISCO-routers' terminology).
*
* 'nos-tun' can works with itself and CISCO-routers.
* (It may also work with Linux 'nos-tun's, but
* I have no Linux system here to test with).
*
* BUGS (or features ?):
* - you must specify ONE of the target host's addresses
* ( nos-tun sends and accepts packets only to/from this
* address )
* - there can be only ONE tunnel between two hosts,
* more precisely - between given host and (one of)
* target hosts' address(es)
* (and why do you want more ?)
*/
/*
* Mar. 23 1999 by Isao SEKI <iseki@gongon.com>
* I added a new flag for ip protocol number.
* We are using 4 as protocol number in ampr.org.
*
*/
#ifndef lint
static const char rcsid[] =
"$FreeBSD: src/sbin/nos-tun/nos-tun.c,v 1.13 2003/10/26 04:37:57 peter Exp $";
#endif /* not lint */
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/signal.h>
#include <sys/socket.h>
#include <net/if.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <arpa/inet.h>
#include <fcntl.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
/* Tunnel interface configuration stuff */
static struct ifaliasreq ifra;
static struct ifreq ifrq;
/* Global descriptors */
int net; /* socket descriptor */
int tun; /* tunnel descriptor */
static void usage(void);
int Set_address(char *addr, struct sockaddr_in *sin)
{
struct hostent *hp;
bzero((char *)sin, sizeof(struct sockaddr));
sin->sin_family = AF_INET;
if((sin->sin_addr.s_addr = inet_addr(addr)) == (in_addr_t)-1) {
hp = gethostbyname(addr);
if (!hp) {
syslog(LOG_ERR,"unknown host %s", addr);
return 1;
}
sin->sin_family = hp->h_addrtype;
bcopy(hp->h_addr, (caddr_t)&sin->sin_addr, hp->h_length);
}
return 0;
}
int tun_open(char *devname, struct sockaddr *ouraddr, char *theiraddr)
{
int s;
struct sockaddr_in *sin;
/* Open tun device */
tun = open (devname, O_RDWR);
if (tun < 0) {
syslog(LOG_ERR,"can't open %s - %m",devname);
return(1);
}
/*
* At first, name the interface.
*/
bzero((char *)&ifra, sizeof(ifra));
bzero((char *)&ifrq, sizeof(ifrq));
strncpy(ifrq.ifr_name, devname+5, IFNAMSIZ);
strncpy(ifra.ifra_name, devname+5, IFNAMSIZ);
s = socket(AF_INET, SOCK_DGRAM, 0);
if (s < 0) {
syslog(LOG_ERR,"can't open socket - %m");
goto tunc_return;
}
/*
* Delete (previous) addresses for interface
*
* !!!!
* On FreeBSD this ioctl returns error
* when tunN have no addresses, so - log and ignore it.
*
*/
if (ioctl(s, SIOCDIFADDR, &ifra) < 0) {
syslog(LOG_ERR,"SIOCDIFADDR - %m");
}
/*
* Set interface address
*/
sin = (struct sockaddr_in *)&(ifra.ifra_addr);
bcopy(ouraddr, sin, sizeof(struct sockaddr_in));
sin->sin_len = sizeof(*sin);
/*
* Set destination address
*/
sin = (struct sockaddr_in *)&(ifra.ifra_broadaddr);
if(Set_address(theiraddr,sin)) {
syslog(LOG_ERR,"bad destination address: %s",theiraddr);
goto stunc_return;
}
sin->sin_len = sizeof(*sin);
if (ioctl(s, SIOCAIFADDR, &ifra) < 0) {
syslog(LOG_ERR,"can't set interface address - %m");
goto stunc_return;
}
/*
* Now, bring up the interface.
*/
if (ioctl(s, SIOCGIFFLAGS, &ifrq) < 0) {
syslog(LOG_ERR,"can't get interface flags - %m");
goto stunc_return;
}
ifrq.ifr_flags |= IFF_UP;
if (!(ioctl(s, SIOCSIFFLAGS, &ifrq) < 0)) {
close(s);
return(0);
}
syslog(LOG_ERR,"can't set interface UP - %m");
stunc_return:
close(s);
tunc_return:
close(tun);
return(1);
}
void Finish(int signum)
{
int s;
syslog(LOG_INFO,"exiting");
close(net);
s = socket(AF_INET, SOCK_DGRAM, 0);
if (s < 0) {
syslog(LOG_ERR,"can't open socket - %m");
goto closing_tun;
}
/*
* Shut down interface.
*/
if (ioctl(s, SIOCGIFFLAGS, &ifrq) < 0) {
syslog(LOG_ERR,"can't get interface flags - %m");
goto closing_fds;
}
ifrq.ifr_flags &= ~(IFF_UP|IFF_RUNNING);
if (ioctl(s, SIOCSIFFLAGS, &ifrq) < 0) {
syslog(LOG_ERR,"can't set interface DOWN - %m");
goto closing_fds;
}
/*
* Delete addresses for interface
*/
bzero(&ifra.ifra_addr, sizeof(ifra.ifra_addr));
bzero(&ifra.ifra_broadaddr, sizeof(ifra.ifra_addr));
bzero(&ifra.ifra_mask, sizeof(ifra.ifra_addr));
if (ioctl(s, SIOCDIFADDR, &ifra) < 0) {
syslog(LOG_ERR,"can't delete interface's addresses - %m");
}
closing_fds:
close(s);
closing_tun:
close(tun);
closelog();
exit(signum);
}
int main (int argc, char **argv)
{
int c, len, ipoff;
char *devname = NULL;
char *point_to = NULL;
char *to_point = NULL;
char *target;
char *source = NULL;
char *protocol = NULL;
int protnum;
struct sockaddr t_laddr; /* Source address of tunnel */
struct sockaddr whereto; /* Destination of tunnel */
struct sockaddr wherefrom; /* Source of tunnel */
struct sockaddr_in *to;
char buf[0x2000]; /* Packets buffer */
struct ip *ip = (struct ip *)buf;
fd_set rfds; /* File descriptors for select() */
int nfds; /* Return from select() */
int lastfd; /* highest fd we care about */
while ((c = getopt(argc, argv, "d:s:t:p:")) != -1) {
switch (c) {
case 'd':
to_point = optarg;
break;
case 's':
point_to = optarg;
break;
case 't':
devname = optarg;
break;
case 'p':
protocol = optarg;
break;
}
}
argc -= optind;
argv += optind;
if ((argc != 1 && argc != 2) || (devname == NULL) ||
(point_to == NULL) || (to_point == NULL)) {
usage();
}
if(protocol == NULL)
protnum = 94;
else
protnum = atoi(protocol);
if (argc == 1) {
target = *argv;
} else {
source = *argv++; target = *argv;
}
/* Establish logging through 'syslog' */
openlog("nos-tun", LOG_PID, LOG_DAEMON);
if(Set_address(point_to, (struct sockaddr_in *)&t_laddr)) {
closelog();
exit(2);
}
if(tun_open(devname, &t_laddr, to_point)) {
closelog();
exit(3);
}
to = (struct sockaddr_in *)&whereto;
if(Set_address(target, to))
Finish(4);
if ((net = socket(AF_INET, SOCK_RAW, protnum)) < 0) {
syslog(LOG_ERR,"can't open socket - %m");
Finish(5);
}
if (source) {
if (Set_address(source, (struct sockaddr_in *)&wherefrom))
Finish(9);
if (bind(net, &wherefrom, sizeof(wherefrom)) < 0) {
syslog(LOG_ERR, "can't bind source address - %m");
Finish(10);
}
}
if (connect(net,&whereto,sizeof(struct sockaddr_in)) < 0 ) {
syslog(LOG_ERR,"can't connect to target - %m");
close(net);
Finish(6);
}
/* Demonize it */
daemon(0,0);
/* Install signal handlers */
(void)signal(SIGHUP,Finish);
(void)signal(SIGINT,Finish);
(void)signal(SIGTERM,Finish);
if (tun > net)
lastfd = tun;
else
lastfd = net;
for (;;) {
/* Set file descriptors for select() */
FD_ZERO(&rfds);
FD_SET(tun,&rfds); FD_SET(net,&rfds);
nfds = select(lastfd+1,&rfds,NULL,NULL,NULL);
if(nfds < 0) {
syslog(LOG_ERR,"interrupted select");
close(net);
Finish(7);
}
if(nfds == 0) { /* Impossible ? */
syslog(LOG_ERR,"timeout in select");
close(net);
Finish(8);
}
if(FD_ISSET(net,&rfds)) {
/* Read from socket ... */
len = read(net, buf, sizeof(buf));
/* Check if this is "our" packet */
if((ip->ip_src).s_addr == (to->sin_addr).s_addr) {
/* ... skip encapsulation headers ... */
ipoff = (ip->ip_hl << 2);
/* ... and write to tun-device */
write(tun,buf+ipoff,len-ipoff);
}
}
if(FD_ISSET(tun,&rfds)) {
/* Read from tun ... */
len = read(tun, buf, sizeof(buf));
/* ... and send to network */
if(send(net, buf, len,0) <= 0) {
syslog(LOG_ERR,"can't send - %m");
}
}
}
}
static void
usage()
{
fprintf(stderr,
"usage: nos-tun -t <tun_name> -s <source_addr> -d <dest_addr> -p <protocol_number> [<source_addr>] <target_addr>\n");
exit(1);
}