nos-tun.c revision 38023
135137Sphk/* 235137Sphk * Copyright (c) 1996, Nickolay Dudorov 335137Sphk * All rights reserved. 435137Sphk * 535137Sphk * Redistribution and use in source and binary forms, with or without 635137Sphk * modification, are permitted provided that the following conditions 735137Sphk * are met: 835137Sphk * 1. Redistributions of source code must retain the above copyright 935137Sphk * notice unmodified, this list of conditions, and the following 1035137Sphk * disclaimer. 1135137Sphk * 2. Redistributions in binary form must reproduce the above copyright 1235137Sphk * notice, this list of conditions and the following disclaimer in the 1335137Sphk * documentation and/or other materials provided with the distribution. 1435137Sphk * 1535137Sphk * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 1635137Sphk * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 1735137Sphk * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 1835137Sphk * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 1935137Sphk * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 2035137Sphk * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 2135137Sphk * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 2235137Sphk * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 2335137Sphk * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 2435137Sphk * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 2535137Sphk * SUCH DAMAGE. 2635137Sphk * 2735137Sphk */ 2835137Sphk 2935137Sphk/* 3035137Sphk * 'nos_tun' program configure tunN interface as a point-to-point 3135137Sphk * connection with two "pseudo"-addresses between this host and 3235137Sphk * 'target'. 3335137Sphk * 3435137Sphk * It uses Ip-over-Ip incapsulation ( protocol number 94 - IPIP) 3535137Sphk * (known as NOS-incapsulation in CISCO-routers' terminology). 3635137Sphk * 3735137Sphk * 'nos_tun' can works with itself and CISCO-routers. 3835137Sphk * (It may also work with Linux 'nos_tun's, but 3935137Sphk * I have no Linux system here to test with). 4035137Sphk * 4135137Sphk * BUGS (or features ?): 4235137Sphk * - you must specify ONE of the target host's addresses 4335137Sphk * ( nos_tun sends and accepts packets only to/from this 4435137Sphk * address ) 4535137Sphk * - there can be only ONE tunnel between two hosts, 4635137Sphk * more precisely - between given host and (one of) 4735137Sphk * target hosts' address(es) 4835137Sphk * (and why do you want more ?) 4935137Sphk */ 5035137Sphk 5137669Scharnier#ifndef lint 5237669Scharnierstatic const char rcsid[] = 5338023Sbde "$Id: nos-tun.c,v 1.3 1998/07/15 06:38:53 charnier Exp $"; 5437669Scharnier#endif /* not lint */ 5535137Sphk 5635734Scharnier#include <fcntl.h> 5735734Scharnier#include <netdb.h> 5835137Sphk#include <stdio.h> 5935137Sphk#include <stdlib.h> 6035137Sphk#include <string.h> 6135137Sphk#include <syslog.h> 6235734Scharnier#include <sys/signal.h> 6335137Sphk#include <sys/socket.h> 6435137Sphk#include <sys/ioctl.h> 6535137Sphk#include <netinet/in.h> 6635137Sphk#include <netinet/in_systm.h> 6735137Sphk#include <netinet/ip.h> 6835137Sphk#include <net/if.h> 6935137Sphk#include <arpa/inet.h> 7035734Scharnier#include <unistd.h> 7135137Sphk 7235137Sphk/* Tunnel interface configuration stuff */ 7335137Sphkstatic struct ifaliasreq ifra; 7435137Sphkstatic struct ifreq ifrq; 7535137Sphk 7635137Sphk/* Global descriptors */ 7735137Sphkint net; /* socket descriptor */ 7835137Sphkint tun; /* tunnel descriptor */ 7935137Sphk 8035734Scharnierstatic void usage __P((void)); 8135734Scharnier 8235137Sphkint Set_address(char *addr, struct sockaddr_in *sin) 8335137Sphk{ 8435137Sphk struct hostent *hp; 8535137Sphk 8635137Sphk bzero((char *)sin, sizeof(struct sockaddr)); 8735137Sphk sin->sin_family = AF_INET; 8835137Sphk if((sin->sin_addr.s_addr = inet_addr(addr)) == (u_long)-1) { 8935137Sphk hp = gethostbyname(addr); 9035137Sphk if (!hp) { 9137669Scharnier syslog(LOG_ERR,"unknown host %s", addr); 9235137Sphk return 1; 9335137Sphk } 9435137Sphk sin->sin_family = hp->h_addrtype; 9535137Sphk bcopy(hp->h_addr, (caddr_t)&sin->sin_addr, hp->h_length); 9635137Sphk } 9735137Sphk return 0; 9835137Sphk} 9935137Sphk 10035137Sphkint tun_open(char *devname, struct sockaddr *ouraddr, char *theiraddr) 10135137Sphk{ 10235137Sphk int s; 10335137Sphk struct sockaddr_in *sin; 10435137Sphk 10535137Sphk /* Open tun device */ 10635137Sphk tun = open (devname, O_RDWR); 10735137Sphk if (tun < 0) { 10837669Scharnier syslog(LOG_ERR,"can't open %s - %m",devname); 10935137Sphk return(1); 11035137Sphk } 11135137Sphk 11235137Sphk /* 11335137Sphk * At first, name the interface. 11435137Sphk */ 11535137Sphk bzero((char *)&ifra, sizeof(ifra)); 11635137Sphk bzero((char *)&ifrq, sizeof(ifrq)); 11735137Sphk 11835137Sphk strncpy(ifrq.ifr_name, devname+5, IFNAMSIZ); 11935137Sphk strncpy(ifra.ifra_name, devname+5, IFNAMSIZ); 12035137Sphk 12135137Sphk s = socket(AF_INET, SOCK_DGRAM, 0); 12235137Sphk if (s < 0) { 12338023Sbde syslog(LOG_ERR,"can't open socket - %m"); 12435137Sphk goto tunc_return; 12535137Sphk } 12635137Sphk 12735137Sphk /* 12835137Sphk * Delete (previous) adresses for interface 12935137Sphk * 13035137Sphk * !!!! 13135137Sphk * On FreeBSD this ioctl returns error 13235137Sphk * when tunN have no addresses, so - log and ignore it. 13335137Sphk * 13435137Sphk */ 13535137Sphk if (ioctl(s, SIOCDIFADDR, &ifra) < 0) { 13635137Sphk syslog(LOG_ERR,"SIOCDIFADDR - %m"); 13735137Sphk } 13835137Sphk 13935137Sphk /* 14035137Sphk * Set interface address 14135137Sphk */ 14235137Sphk sin = (struct sockaddr_in *)&(ifra.ifra_addr); 14335137Sphk bcopy(ouraddr, sin, sizeof(struct sockaddr_in)); 14435137Sphk sin->sin_len = sizeof(*sin); 14535137Sphk 14635137Sphk /* 14735137Sphk * Set destination address 14835137Sphk */ 14935137Sphk sin = (struct sockaddr_in *)&(ifra.ifra_broadaddr); 15035137Sphk if(Set_address(theiraddr,sin)) { 15137669Scharnier syslog(LOG_ERR,"bad destination address: %s",theiraddr); 15235137Sphk goto stunc_return; 15335137Sphk } 15435137Sphk sin->sin_len = sizeof(*sin); 15535137Sphk 15635137Sphk if (ioctl(s, SIOCAIFADDR, &ifra) < 0) { 15737669Scharnier syslog(LOG_ERR,"can't set interface address - %m"); 15835137Sphk goto stunc_return; 15935137Sphk } 16035137Sphk 16135137Sphk /* 16235137Sphk * Now, bring up the interface. 16335137Sphk */ 16435137Sphk if (ioctl(s, SIOCGIFFLAGS, &ifrq) < 0) { 16537669Scharnier syslog(LOG_ERR,"can't get interface flags - %m"); 16635137Sphk goto stunc_return; 16735137Sphk } 16835137Sphk 16935137Sphk ifrq.ifr_flags |= IFF_UP; 17035137Sphk if (!(ioctl(s, SIOCSIFFLAGS, &ifrq) < 0)) { 17135137Sphk close(s); 17235137Sphk return(0); 17335137Sphk } 17437669Scharnier syslog(LOG_ERR,"can't set interface UP - %m"); 17535137Sphkstunc_return: 17635137Sphk close(s); 17735137Sphktunc_return: 17835137Sphk close(tun); 17935137Sphk return(1); 18035137Sphk} 18135137Sphk 18235137Sphkvoid Finish(int signum) 18335137Sphk{ 18435137Sphk int s; 18535137Sphk 18637669Scharnier syslog(LOG_INFO,"exiting"); 18735137Sphk 18835137Sphk close(net); 18935137Sphk 19035137Sphk s = socket(AF_INET, SOCK_DGRAM, 0); 19135137Sphk if (s < 0) { 19237669Scharnier syslog(LOG_ERR,"can't open socket - %m"); 19335137Sphk goto closing_tun; 19435137Sphk } 19535137Sphk 19635137Sphk /* 19735137Sphk * Shut down interface. 19835137Sphk */ 19935137Sphk if (ioctl(s, SIOCGIFFLAGS, &ifrq) < 0) { 20037669Scharnier syslog(LOG_ERR,"can't get interface flags - %m"); 20135137Sphk goto closing_fds; 20235137Sphk } 20335137Sphk 20435137Sphk ifrq.ifr_flags &= ~(IFF_UP|IFF_RUNNING); 20535137Sphk if (ioctl(s, SIOCSIFFLAGS, &ifrq) < 0) { 20637669Scharnier syslog(LOG_ERR,"can't set interface DOWN - %m"); 20735137Sphk goto closing_fds; 20835137Sphk } 20935137Sphk 21035137Sphk /* 21135137Sphk * Delete adresses for interface 21235137Sphk */ 21335137Sphk bzero(&ifra.ifra_addr, sizeof(ifra.ifra_addr)); 21435137Sphk bzero(&ifra.ifra_broadaddr, sizeof(ifra.ifra_addr)); 21535137Sphk bzero(&ifra.ifra_mask, sizeof(ifra.ifra_addr)); 21635137Sphk if (ioctl(s, SIOCDIFADDR, &ifra) < 0) { 21737669Scharnier syslog(LOG_ERR,"can't delete interface's addresses - %m"); 21835137Sphk } 21935137Sphkclosing_fds: 22035137Sphk close(s); 22135137Sphkclosing_tun: 22235137Sphk close(tun); 22335137Sphk closelog(); 22435137Sphk exit(signum); 22535137Sphk} 22635137Sphk 22735137Sphkint main (int argc, char **argv) 22835137Sphk{ 22935137Sphk int c, len, ipoff; 23035137Sphk 23135137Sphk char *devname = NULL; 23235137Sphk char *point_to = NULL; 23335137Sphk char *to_point = NULL; 23435137Sphk char *target; 23535137Sphk 23635137Sphk struct sockaddr t_laddr; /* Source address of tunnel */ 23735137Sphk struct sockaddr whereto; /* Destination of tunnel */ 23835137Sphk struct sockaddr_in *to; 23935137Sphk 24035137Sphk char buf[0x2000]; /* Packets buffer */ 24135137Sphk struct ip *ip = (struct ip *)buf; 24235137Sphk 24335137Sphk fd_set rfds, wfds, efds; /* File descriptors for select() */ 24435137Sphk int nfds; /* Return from select() */ 24535137Sphk 24635137Sphk 24735734Scharnier while ((c = getopt(argc, argv, "d:s:t:")) != -1) { 24835137Sphk switch (c) { 24935137Sphk case 'd': 25035137Sphk to_point = optarg; 25135137Sphk break; 25235137Sphk case 's': 25335137Sphk point_to = optarg; 25435137Sphk break; 25535137Sphk case 't': 25635137Sphk devname = optarg; 25735137Sphk break; 25835137Sphk } 25935137Sphk } 26035137Sphk argc -= optind; 26135137Sphk argv += optind; 26235137Sphk 26335137Sphk if (argc != 1 || (devname == NULL) || 26435137Sphk (point_to == NULL) || (to_point == NULL)) { 26535734Scharnier usage(); 26635137Sphk } 26735137Sphk 26835137Sphk target = *argv; 26935137Sphk 27035137Sphk /* Establish logging through 'syslog' */ 27135137Sphk openlog("nos_tun", LOG_PID, LOG_DAEMON); 27235137Sphk 27335137Sphk if(Set_address(point_to, (struct sockaddr_in *)&t_laddr)) { 27435137Sphk closelog(); 27535137Sphk exit(2); 27635137Sphk } 27735137Sphk 27835137Sphk if(tun_open(devname, &t_laddr, to_point)) { 27935137Sphk closelog(); 28035137Sphk exit(3); 28135137Sphk } 28235137Sphk 28335137Sphk to = (struct sockaddr_in *)&whereto; 28435137Sphk if(Set_address(target, to)) 28535137Sphk Finish(4); 28635137Sphk 28735137Sphk if ((net = socket(AF_INET, SOCK_RAW, 94)) < 0) { 28837669Scharnier syslog(LOG_ERR,"can't open socket - %m"); 28935137Sphk Finish(5); 29035137Sphk } 29135137Sphk 29235137Sphk if (connect(net,&whereto,sizeof(struct sockaddr_in)) < 0 ) { 29337669Scharnier syslog(LOG_ERR,"can't connect to target - %m"); 29435137Sphk close(net); 29535137Sphk Finish(6); 29635137Sphk } 29735137Sphk 29835137Sphk /* Demonize it */ 29935137Sphk daemon(0,0); 30035137Sphk 30135137Sphk /* Install signal handlers */ 30235137Sphk (void)signal(SIGHUP,Finish); 30335137Sphk (void)signal(SIGINT,Finish); 30435137Sphk (void)signal(SIGTERM,Finish); 30535137Sphk 30635137Sphk for (;;) { 30735137Sphk /* Set file descriptors for select() */ 30835137Sphk FD_ZERO(&rfds); FD_ZERO(&wfds); FD_ZERO(&efds); 30935137Sphk FD_SET(tun,&rfds); FD_SET(net,&rfds); 31035137Sphk 31135137Sphk nfds = select(net+10,&rfds,&wfds,&efds,NULL); 31235137Sphk if(nfds < 0) { 31337669Scharnier syslog(LOG_ERR,"interrupted select"); 31435137Sphk close(net); 31535137Sphk Finish(7); 31635137Sphk } 31735137Sphk if(nfds == 0) { /* Impossible ? */ 31837669Scharnier syslog(LOG_ERR,"timeout in select"); 31935137Sphk close(net); 32035137Sphk Finish(8); 32135137Sphk } 32235137Sphk 32335137Sphk 32435137Sphk if(FD_ISSET(net,&rfds)) { 32535137Sphk /* Read from socket ... */ 32635137Sphk len = read(net, buf, sizeof(buf)); 32735137Sphk /* Check if this is "our" packet */ 32835137Sphk if((ip->ip_src).s_addr == (to->sin_addr).s_addr) { 32935137Sphk /* ... skip encapsulation headers ... */ 33035137Sphk ipoff = (ip->ip_hl << 2); 33135137Sphk /* ... and write to tun-device */ 33235137Sphk write(tun,buf+ipoff,len-ipoff); 33335137Sphk } 33435137Sphk } 33535137Sphk 33635137Sphk if(FD_ISSET(tun,&rfds)) { 33735137Sphk /* Read from tun ... */ 33835137Sphk len = read(tun, buf, sizeof(buf)); 33935137Sphk /* ... and send to network */ 34035137Sphk if(send(net, buf, len,0) <= 0) { 34137669Scharnier syslog(LOG_ERR,"can't send - %m"); 34235137Sphk } 34335137Sphk } 34435137Sphk } 34535137Sphk} 34635137Sphk 34735734Scharnierstatic void 34835734Scharnierusage() 34935734Scharnier{ 35035734Scharnier fprintf(stderr, 35135734Scharnier"usage: nos_tun -t <tun_name> -s <source_addr> -d <dest_addr> <target_addr>\n"); 35235734Scharnier exit(1); 35335734Scharnier} 35435734Scharnier 355