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#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
int main(int argc, char *argv[])
{
char buf[2048], dev[10]="";
int fd, len;
if( (fd = tun_alloc(dev)) < 0 ){
printf("Cannot allocate TUN device\n");
exit(1);
}
while(1){
if( (len = tun_read(fd, buf, sizeof(buf))) < 0 ){
printf("Cannot allocate TUN device\n");
exit(1);
}
printf("Received %d bytes\n", len);
}
}
/*
* Allocate TUN device, returns opened fd.
* Stores dev name in the first arg(must be large enough).
*/
int tun_alloc(char *dev)
{
int tun_fd, if_fd, ppa = -1;
static int ip_fd = 0;
char *ptr;
if( *dev ){
ptr = dev;
while( *ptr && !isdigit((int)*ptr) ) ptr++;
ppa = atoi(ptr);
}
/* Check if IP device was opened */
if( ip_fd )
close(ip_fd);
if( (ip_fd = open("/dev/ip", 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(ioctl(ip_fd, I_LINK, if_fd) < 0){
syslog(LOG_ERR, "Can't link TUN device to IP");
return -1;
}
sprintf(dev, "tun%d", ppa);
return tun_fd;
}
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;
}
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