#define MODULE
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/proc_fs.h>
#include <linux/sched.h>
#include <asm/uaccess.h>
#define MODULE_NAME "linTry"
#define FOOBAR_LEN 128

#define MAX_UNSIGNED_SHORT 65535 
extern float rate;                                /* drop percentage */
extern unsigned short cutoff;
extern __u32 target;	/* The above 3 variable are exported from 
			 * packet_dropper module */		

static struct proc_dir_entry *example_dir, *foo_file;


/* str is wrapped with '\0', the data is always valid, error check was done
* in userspace
* */
static void getIpRate(char * str, float * rate, unsigned *ip )
{
	int j,i,ipp=0;
	float decimal=0,dec=1;

	for( i=0; str[i] != '.'; i++);

	for ( i++; str[i] != ' '; i++ )
	{
	      	dec = dec * 0.1;	
		decimal += (str[ i ] - '0')*dec;
	}/* end of for loop */

	for ( j=i+1; str[j] != '\0'; j++ )
	{
		ipp = ipp*10 + str[j] - '0';
	}
	*rate = decimal;
	*ip = ipp;
}/* end of getipRate*/



static int proc_read_foobar(char *buf, char **start,
		off_t off, int count,int *eof, void *data)
{    
	int len,i;
	unsigned addr = target;	/* target is exported from packet_dropper*/
	float myRate = rate;	/* rate is exported from packet_dropper*/
	unsigned addr1;
	int digit;

  	//MOD_INC_USE_COUNT;
    	len = sprintf( buf, 
	          "Dropping Rate shows only the first 6 digits after '.'\n");
    	len += sprintf( buf+len, "Dropping Rate is: 0.");

	for( i=0; i<6; i++)
	{
		digit = (int) (myRate*10);
		myRate = myRate*10 - digit; 
		len += sprintf( buf+len, "%1d", digit );
	}
	len += sprintf( buf+len, "\n");

	/* in kernel there is not floating point number 
	 * the following is not working 
	 */
    	//len = sprintf( buf, "Dropping Rate is: %f\n", rate );

	addr1=addr%256;
        len += sprintf( buf+len, "Destination IP is: %d.", addr1);
	addr>>=8;
	addr1= addr%256;
        len += sprintf( buf+len, "%d.", addr1);
	addr>>=8;
	addr1= addr%256;
        len += sprintf( buf+len, "%d.", addr1);
	addr >>= 8;
	addr1= addr%256;
        len += sprintf( buf+len, "%d\n", addr1);
        //MOD_DEC_USE_COUNT;
	return len;
}

static int proc_write_foobar(struct file *file,const char *buffer,
				unsigned long count,void *data)
{    
	int len;
	char myData[ 256 ];
	unsigned myIp;
	float myRate;

	//MOD_INC_USE_COUNT;
	if(count > FOOBAR_LEN)
		len = FOOBAR_LEN;
	else    len = count;

	if(copy_from_user(myData, buffer, len)) 
	{
		//MOD_DEC_USE_COUNT;
		return -EFAULT;
	}
	myData[len] = '\0';
	printk("<1>my data is: %s\n", myData );
	getIpRate( myData, &myRate, &myIp );

	//MOD_DEC_USE_COUNT;
	rate = myRate;
	target = myIp;
	cutoff = (unsigned short) (rate*(1-rate)*MAX_UNSIGNED_SHORT); 
	return len;
}
int init_module()
{    
	int rv = 0;
	EXPORT_NO_SYMBOLS;
	/* create directory */
	example_dir = proc_mkdir(MODULE_NAME, NULL);
	if(example_dir == NULL) {
		printk("<1> example_dir failed\n");
		rv = -ENOMEM;
		goto out;
	}
	example_dir->owner = THIS_MODULE;


	/* create foo and bar files using same callback
	* functions
	*/
	foo_file = create_proc_entry("foo", 0644, example_dir);
	if(foo_file == NULL) {
		rv = -ENOMEM;
		goto no_foo;
	}
	//foo_file->data = &foo_data;
	foo_file->read_proc = proc_read_foobar;
	foo_file->write_proc = proc_write_foobar;
	foo_file->owner = THIS_MODULE;


	/* everything OK */
	printk(KERN_INFO "%s  initialised\n",MODULE_NAME );
	
	return 0;
	no_foo:  
	remove_proc_entry(MODULE_NAME, NULL);
	out:    return rv;
}

void cleanup_module()
{
	remove_proc_entry("foo", example_dir);
	remove_proc_entry(MODULE_NAME, NULL);
	printk(KERN_INFO "%s removed\n",MODULE_NAME);
}