/* this program runs in user space by root*/
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>

int buildIp( char * ipStr, unsigned * IP )
{
	unsigned int r = 0;
	unsigned fact[] = { 1, 256, 65536,16777216 };
	int i=0, dotPos = -1; 
	int justPoint=0;	/* used to check error of ".." */
	int numDot=0;		/* used to check error of 1.2.2.3.3 */
	unsigned int a=0;

	while (ipStr[i] != '\0')
	{
		if ( ipStr[i] == '.' )
		{
			if (justPoint)
				return -1;
			justPoint=1;
			if ( numDot >=3 )
				return -1;
			numDot++;
			dotPos++;
			r += a*fact[ dotPos ];
			a = 0;
			i++;
			continue;
		}
		justPoint = 0;
		if (( ipStr[i] > '9' ) || (ipStr[i]<'0') )
			return -1;
		a = a*10 + ipStr[i] - '0';
		if ( a > 255 )
			return -1;
		i++;
	}/* end of while */
	if ( numDot != 3 )
		return -1;
	dotPos++;
	r += a*fact[ dotPos ];

	*IP = r;
	return 0;
}/* end of buildIP*/


int main(int argc, char *argv[] )
{
	//unsigned int rate;
	float rate;
	unsigned int IP;
	FILE* procEntry=NULL;


	if ( argc != 3 )
	{
		printf("usage: %s DropRate DestIp\n", argv[0] );
		return -1;
	}

	rate = (float) atof( argv[1] );
	if ( (rate > 1) || (rate<0) )
	{
		printf("Rate should be in the range [0.0, 1.0]\n" );
	 	return -1;	
	}

	if ( buildIp( argv[2], &IP ) )
	{
		printf("bad format of IP address\n" );
		return -1;
	}
	procEntry = fopen( "/proc/linTry/foo", "w" );
	if ( procEntry == NULL )
	{
		printf("Error opening: /proc/linTry/foo for writing\n" );
		exit( 1 );
	}

	fprintf( procEntry, "%f %u", rate, IP );
	fclose( procEntry );

	return 0;
}/* end of main */