//---------------------------------------------------------------------
//	rxtester.cpp	
//
//	This utility displays the raw network packets received by the
//	network interface on this workstation.  It is adapted from an       
//	example that appeared in Linux Journal (June 2001) pp. 26-31.
//
//	NOTE: a user normally needs 'root' privileges when executing. 
//
//	programmer: ALLAN CRUSE
//	written on: 06 APR 2005
//---------------------------------------------------------------------

#include <stdio.h>		// for printf(), perror()
#include <stdlib.h>		// for exit()
#include <linux/if_ether.h>	// for ETH_P_ALL
#include <netinet/in.h>		// for htons()
#include <sys/socket.h>		// for socket(), recvfrom()

void dump_packet( char *buf, int n )
{
	static int	pktid = 0;

	printf( "\npacket #%d ", ++pktid );
	for (int i = 0; i < n; i+=16)
		{
		printf( "\n%04X: ", i );
		for (int j = 0; j < 16; j++)
			{
			unsigned char	ch = ( i + j < n ) ? buf[ i+j ] : 0;
			if ( i + j < n ) printf( "%02X ", ch );
			else	printf( "   " );
			}
		for (int j = 0; j < 16; j++)
			{
			unsigned char	ch = ( i + j < n ) ? buf[ i+j ] : ' ';
			if (( ch < 0x20 )||( ch > 0x7E )) ch = '.';
			printf( "%c", ch );
			}
		}
	printf( "\n" );
}

int main( void )
{
	int sock = socket( PF_PACKET, SOCK_RAW, htons( ETH_P_ALL ) ); 
	if ( sock < 0 ) { perror( "socket" ); exit( 1 ); }

	while ( 1 )
		{
		printf( "-------\n" );
		char	buffer[ 2048 ];
		int	n = recvfrom( sock, buffer, 2048, 0, NULL, NULL );
		printf( "%d bytes read\n", n );
		dump_packet( buffer, n );
		}
	printf( "\n" );
}