utils.c

Adhoc无线网络路由协议源码

#include "utils.h"
#include "common.h"

/*
 *
 *   Gets the current time in milliseconds since 1 jan 1970
 *
 *   Return:
 *     u_int64_t - On error -1 is returned otherwise the time.
 */
u_int64_t
getcurrtime()
{
  struct timeval tv;

  if (gettimeofday(&tv, NULL) < 0)
    /* Couldn't get time of day */
    return -1;

  return ((u_int64_t)tv.tv_sec) * 1000 + ((u_int64_t)tv.tv_usec) / 1000;
}

/*
 *  dot_ip() : converts ip address from int to dot.dot notation.
 *  is a wrapper around inet_ntoa so that you do not have to declare a, in_addr structure 
 *  
 *	 dot_ip can be called only once in one statement.
 *	 this is because dot_ip uses inet_ntoa which returns in a statically 
 *	 allocated buffer which is overwritten in each call.
 * hence you have to break up the printfs if there are multiple calls to dot_ip
 *
*/

char *
dot_ip(u_int32_t ipint)
{
	struct in_addr ip;
	ip.s_addr = ipint ;
	return inet_ntoa(ip);
}


/* This is a routine to do a 'mknod' on the /dev/tun<n> if possible:
 * Return: 0 is ok, -1=already open, etc.
 * 
 * From sourcode of user-mode-linux by Jeff Dike --vikas
 */

int mk_node(char *devname, int major, int minor)
{
  struct stat statval;
  int retval;

  /* first do a stat on the node to see whether it exists and we
   * had some other reason to fail:
   */
  retval = stat(devname, &statval);
  if(retval == 0) return(0);
  else if(errno != ENOENT){
    /* it does exist. We are just going to return -1, 'cause there
     * was some other problem in the open :-(.
     */
    return -1;
  }

  /* It doesn't exist. We can create it. */

  return(mknod(devname, S_IFCHR|S_IREAD|S_IWRITE, makedev(major, minor)));
}