couple C++ questions

BrianK · 07-16-2002, 05:36 PM

I need to be able to find out how to determine the MAC address inside C++.

I also need to be able to find out the last access time of a file (as in, I give the file name and get a time_t back).

I've done this stuff in windows (which was quite a pain) and now need to port to Linux.

any help would be great.

BrianK · 07-16-2002, 06:54 PM

well, in case anyone is interested, here's a super easy method a friend fo mine came up with that works better than anything else on the web...

Code:


#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <signal.h>
#include <ctype.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <linux/sockios.h>
#include <linux/if.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <netdb.h>
#include <fcntl.h>

int main (int argc, char *argv[])
{
  int      sd, sd2;             /* socket descriptors */
  int c;
  unsigned char foo[14];
  struct ifreq ifr;
  int idx;

  fprintf(stderr,"socket %d\n",sd);
  sprintf(ifr.ifr_ifrn.ifrn_name,"eth0");
  // fprintf(stderr,"ioctl ret %d\n",ioctl(sd, SIOCGIFHWADDR,&ifr));
  memcpy(foo,&ifr.ifr_ifru.ifru_hwaddr.sa_data,14);

  for(idx=0;idx<6;idx++){
    fprintf(stderr,"%02x:",foo[idx]);
  }
  fprintf(stderr, "\n");
}

there's a lot of extra includes, but you get the picture...

BrianK · 07-16-2002, 07:41 PM

wait a minute, that was totally wrong, this is better:

Code:



int main (int argc, char *argv[])
{
  struct   protoent  *ptrp;     /* pointer to a protocol table entry */
  struct   sockaddr_in sad;     /* structure to hold server's address */
  int      sd, sd2;             /* socket descriptors */
  int      port=5193;                /* protocol port number */
  int c;
  unsigned char foo[14];
  struct ifreq ifr;
  int idx;

   
  if (port > 0)                          /* test for illegal value    */
    sad.sin_port = htons((u_short)port);
  else {                                /* print error message and exit */
    fprintf (stderr, "bad port number %s/n",argv[1]);
    exit (1);
  }
  
  if ( ((int)(ptrp = getprotobyname("tcp"))) == 0)  {
    fprintf(stderr, "cannot map \"tcp\" to protocol number");
    exit (1);
  }
  sd = socket (PF_INET, SOCK_STREAM, ptrp->p_proto);
  if (sd < 0) {
    fprintf(stderr, "socket creation failed\n");
    exit(1);
  }


  sprintf(ifr.ifr_ifrn.ifrn_name,"eth0");
  ioctl(sd, SIOCGIFHWADDR,&ifr);
  memcpy(foo,&ifr.ifr_ifru.ifru_hwaddr.sa_data,14);

  printf("MAC address: %02X:%02X:%02X:%02X:%02X:%02X\n",
	 foo[0],
	 foo[1],
	 foo[2],
	 foo[3],
	 foo[4],
	 foo[5]);

}

Mik · 07-17-2002, 03:17 AM

To get the last access time of a file you would do something like this (this program would also work in windows):

Code:

#include <stdio.h>
#include <sys/stat.h>
#include <time.h>

int main()
{
  char filename[] = "atime.c";
  char timeStr[100];
  struct stat buf;
  if (!stat(filename, &buf))
  {
     struct tm* atime = localtime(&buf.st_atime);
     strftime(timeStr, 100, "%Y-%m-%d %H:%M.%S", atime);
     printf("atime = %s\n", timeStr);
  }
  else
     printf("error getting atime\n");

  return 0;
}