Ip Address 필터중 좋은 방법알려주세요

글로 쓸라니깐 귀차니즘의 압박으로 인해, 그냥 간단히 코드로 끄적거려 봅니다.

추가덧글: 시간이 없어서리 글을 좀 짧게 썼습니다. 죄송함다 ㅡ.ㅡ
파지랑 빈병 줏으러 가야되기 땜에...

/*	------------------------------------------------------------------------- */
/*	compare address/netmask function for src/dst address.
	wfellow at naver dot com
	for bbs.kldp.org - Programming QnA forum.

	gcc -O2 -Wall -o cmpmask cmpmask.c

		return <0 - 등록되어 있는 주소의 범위에 속하지 않는다.                */
/*	------------------------------------------------------------------------- */

#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#define OBJECT_NUM_NETWORK	(8)

#define OBJECT_DEF_EMPTY	(0)
#define OBJECT_DEF_OCCUPIED	(1)

typedef struct {
	unsigned int occupied;
	unsigned int address;
	unsigned int netmask;
} OBJECT_STR_NETWORK;

OBJECT_STR_NETWORK network[OBJECT_NUM_NETWORK];

#define INSPECT_LIST_FOR_EACH( i )	for ( i = 0; i < OBJECT_NUM_NETWORK; ++i )

static int object_address_compare_range( unsigned int addr )
{
	register int i;

	register unsigned int oaddr;
	register unsigned int caddr;
	register unsigned int cmask;

	if ( addr == 0 ) return -1;

	oaddr = addr;

	INSPECT_LIST_FOR_EACH( i )
	{
		if ( network[i].occupied == OBJECT_DEF_EMPTY ) continue;

		caddr = network[i].address;
		cmask = network[i].netmask;

		if ( (caddr & cmask) == (oaddr & cmask) ) return i;
	}

	return -2;
}

int main(int argc, char *argv[])
{
	int i;
	int r;
	unsigned int wn;

	/*	Initialize.	*/
	for ( i = 0; i < OBJECT_NUM_NETWORK; ++i )
	{
		network[i].occupied = OBJECT_DEF_EMPTY;
		network[i].address = 0;
		network[i].netmask = 0;
	}

	/*	192.168.0.0/24	*/
	network[0].address = (unsigned int)inet_addr("192.168.0.0");
	network[0].netmask = (unsigned int)inet_addr("255.255.255.0");

	/*	10.4.1.0/24	*/
	network[1].address = (unsigned int)inet_addr("10.4.1.0");
	network[1].netmask = (unsigned int)inet_addr("255.255.255.0");

	/*	10.4.2.0/24	*/
	network[2].address = (unsigned int)inet_addr("10.4.2.0");
	network[2].netmask = (unsigned int)inet_addr("255.255.255.0");

	/*	Occupied!	*/
	network[0].occupied = OBJECT_DEF_OCCUPIED;
	network[1].occupied = OBJECT_DEF_OCCUPIED;
	network[2].occupied = OBJECT_DEF_OCCUPIED;

	/*	Test #1: 192.168.0.20	*/
	wn = (unsigned int)inet_addr("192.168.0.20");
	r = object_address_compare_range( wn );
	printf( "Result = %d\n", r );

	/*	Test #2: 10.4.1.20	*/
	wn = (unsigned int)inet_addr("10.4.1.20");
	r = object_address_compare_range( wn );
	printf( "Result = %d\n", r );

	/*	Test #3: 10.4.2.20	*/
	wn = (unsigned int)inet_addr("10.4.2.20");
	r = object_address_compare_range( wn );
	printf( "Result = %d\n", r );

	/*	Test #4: 10.4.9.20	*/
	wn = (unsigned int)inet_addr("10.4.9.20");
	r = object_address_compare_range( wn );
	printf( "Result = %d\n", r );

	return EXIT_SUCCESS;
}