//-------------------------------------------------------------------
//	joinvlan.cpp
//
//	This program allows a user to modify the VLAN identification
//	number being used by our 'nic2.c' device-driver, assuming it
//	has already been compiled and installed in the Linux kernel. 
//
//	     compile using:  $ g++ joinvlan.cpp -o joinvlan
//	     execute using:  $ ./joinvlan 
//
//	programmer: ALLAN CRUSE
//	written on: 20 MAR 2008
//-------------------------------------------------------------------

#include <stdio.h>	// for printf(), perror() 
#include <fcntl.h>	// for open() 
#include <stdlib.h>	// for exit() 
#include <sys/ioctl.h>	// for ioctl()

char devname[] = "/dev/nic";
char mac[6];
short vlan_id;

int main( int argc, char **argv )
{
	// open the device-file
	int	fd = open( devname, O_RDWR );
	if ( fd < 0 ) { perror( devname ); exit(1); }

	// get the current value of the driver's VLAN identification
	if ( ioctl( fd, 3, &vlan_id ) ) { perror( "ioctl 3" ); exit(1); }
	printf( "\nCurrent VLAN identification: 0x%04X \n", vlan_id );
	
	// prompt the user to enter a new VLAN identification value
	printf( "\nRevised VLAN identification: 0x" );
	fflush( stdout );

	// convert the user's hexadecimal input-string into a number 
	char	inbuf[ 8 ] = {0};
	fgets( inbuf, 7, stdin );
	vlan_id = (short)strtoul( inbuf, NULL, 16 );

	// set the revised value of the driver's VLAN identification
	if ( ioctl( fd, 2, &vlan_id ) ) { perror( "ioctl 2" ); exit(1); }

	// get the revised value and display it for confirmation
	if ( ioctl( fd, 3, &vlan_id ) ) { perror( "ioctl 3" ); exit(1); }
	printf( "\nCurrent VLAN identification: 0x%04X \n", vlan_id );
	printf( "\n" );
}