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