/*
 * Copyright (c) 1999 - 2003
 * NetGroup, Politecnico di Torino (Italy)
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the Politecnico di Torino nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 *
 *	@(#)bpf.c	7.5 (Berkeley) 7/15/91
 */


/** @ingroup NPF 
 *  @{
 */

/** @defgroup win_bpf win_bpf.c
 *  XXX todo.
 *  @{
 */

#if !(defined(lint) || defined(KERNEL))
static const char rcsid[] =
    "@(#) $Header: /usr/cvsroot_private/winpcap/Packet9x/VXD/win_bpf_filter.c,v 1.5 2005/12/02 22:31:26 gianlucav Exp $ (LBL)";
#endif

#ifndef WIN32
#include <sys/param.h>
#include <sys/time.h>
#else 
#include <winsock2.h>
#endif
#include <sys/types.h>
#include "win_bpf.h"

#define int32 bpf_int32
#define u_int32 bpf_u_int32


#ifndef LBL_ALIGN
#if defined(sparc) || defined(mips) || defined(ibm032) || \
    defined(__alpha) || defined(__hpux)
#define LBL_ALIGN
#endif
#endif

#ifndef LBL_ALIGN
#ifndef WIN32
#include <netinet/in.h>
#endif

#define EXTRACT_SHORT(p)\
	((u_short)\
		((u_short)*((u_char *)p+0)<<8|\
		 (u_short)*((u_char *)p+1)<<0))
#define EXTRACT_LONG(p)\
		((u_int32)*((u_char *)p+0)<<24|\
		 (u_int32)*((u_char *)p+1)<<16|\
		 (u_int32)*((u_char *)p+2)<<8|\
		 (u_int32)*((u_char *)p+3)<<0)
#endif

/*
 * Execute the filter program starting at pc on the packet p
 * wirelen is the length of the original packet
 * buflen is the amount of data present
 */
u_int bpf_filter(pc, p, wirelen, buflen)
	register struct bpf_insn *pc;
	register u_char *p;
	u_int wirelen;
	register u_int buflen;
{
	register u_int32 A, X;
	register int k;
	int32 mem[BPF_MEMWORDS];

	if (pc == 0)
		/*
		 * No filter means accept all.
		 */
		return (u_int)-1;
	A = 0;
	X = 0;
	--pc;
	while (1) {
		++pc;
		switch (pc->code) {

		default:
		
			return 0;

		case BPF_RET|BPF_K:
			return (u_int)pc->k;

		case BPF_RET|BPF_A:
			return (u_int)A;

		case BPF_LD|BPF_W|BPF_ABS:
			k = pc->k;
			if (k + sizeof(int32) > buflen) {
				return 0;
			}
			A = EXTRACT_LONG(&p[k]);
			continue;

		case BPF_LD|BPF_H|BPF_ABS:
			k = pc->k;
			if (k + sizeof(short) > buflen) {
				return 0;
			}
			A = EXTRACT_SHORT(&p[k]);
			continue;

		case BPF_LD|BPF_B|BPF_ABS:
			k = pc->k;
			if ((int)k >= (int)buflen) {
				return 0;
			}
			A = p[k];
			continue;

		case BPF_LD|BPF_W|BPF_LEN:
			A = wirelen;
			continue;

		case BPF_LDX|BPF_W|BPF_LEN:
			X = wirelen;
			continue;

		case BPF_LD|BPF_W|BPF_IND:
			k = X + pc->k;
			if (k + sizeof(int32) > buflen) {
				return 0;
			}
			A = EXTRACT_LONG(&p[k]);
			continue;

		case BPF_LD|BPF_H|BPF_IND:
			k = X + pc->k;
			if (k + sizeof(short) > buflen) {
				return 0;
			}
			A = EXTRACT_SHORT(&p[k]);
			continue;

		case BPF_LD|BPF_B|BPF_IND:
			k = X + pc->k;
			if ((int)k >= (int)buflen) {
				return 0;
			}
			A = p[k];
			continue;

		case BPF_LDX|BPF_MSH|BPF_B:
			k = pc->k;
			if ((int)k >= (int)buflen) {
				return 0;
			}
			X = (p[pc->k] & 0xf) << 2;
			continue;

		case BPF_LD|BPF_IMM:
			A = pc->k;
			continue;

		case BPF_LDX|BPF_IMM:
			X = pc->k;
			continue;

		case BPF_LD|BPF_MEM:
			A = mem[pc->k];
			continue;
			
		case BPF_LDX|BPF_MEM:
			X = mem[pc->k];
			continue;

		case BPF_ST:
			mem[pc->k] = A;
			continue;

		case BPF_STX:
			mem[pc->k] = X;
			continue;

		case BPF_JMP|BPF_JA:
			pc += pc->k;
			continue;

		case BPF_JMP|BPF_JGT|BPF_K:
			pc += ((int)A > (int)pc->k) ? pc->jt : pc->jf;
			continue;

		case BPF_JMP|BPF_JGE|BPF_K:
			pc += ((int)A >= (int)pc->k) ? pc->jt : pc->jf;
			continue;

		case BPF_JMP|BPF_JEQ|BPF_K:
			pc += ((int)A == (int)pc->k) ? pc->jt : pc->jf;
			continue;

		case BPF_JMP|BPF_JSET|BPF_K:
			pc += (A & pc->k) ? pc->jt : pc->jf;
			continue;

		case BPF_JMP|BPF_JGT|BPF_X:
			pc += (A > X) ? pc->jt : pc->jf;
			continue;

		case BPF_JMP|BPF_JGE|BPF_X:
			pc += (A >= X) ? pc->jt : pc->jf;
			continue;

		case BPF_JMP|BPF_JEQ|BPF_X:
			pc += (A == X) ? pc->jt : pc->jf;
			continue;

		case BPF_JMP|BPF_JSET|BPF_X:
			pc += (A & X) ? pc->jt : pc->jf;
			continue;

		case BPF_ALU|BPF_ADD|BPF_X:
			A += X;
			continue;
			
		case BPF_ALU|BPF_SUB|BPF_X:
			A -= X;
			continue;
			
		case BPF_ALU|BPF_MUL|BPF_X:
			A *= X;
			continue;
			
		case BPF_ALU|BPF_DIV|BPF_X:
			if (X == 0)
				return 0;
			A /= X;
			continue;
			
		case BPF_ALU|BPF_AND|BPF_X:
			A &= X;
			continue;
			
		case BPF_ALU|BPF_OR|BPF_X:
			A |= X;
			continue;

		case BPF_ALU|BPF_LSH|BPF_X:
			A <<= X;
			continue;

		case BPF_ALU|BPF_RSH|BPF_X:
			A >>= X;
			continue;

		case BPF_ALU|BPF_ADD|BPF_K:
			A += pc->k;
			continue;
			
		case BPF_ALU|BPF_SUB|BPF_K:
			A -= pc->k;
			continue;
			
		case BPF_ALU|BPF_MUL|BPF_K:
			A *= pc->k;
			continue;
			
		case BPF_ALU|BPF_DIV|BPF_K:
			A /= pc->k;
			continue;
			
		case BPF_ALU|BPF_AND|BPF_K:
			A &= pc->k;
			continue;
			
		case BPF_ALU|BPF_OR|BPF_K:
			A |= pc->k;
			continue;

		case BPF_ALU|BPF_LSH|BPF_K:
			A <<= pc->k;
			continue;

		case BPF_ALU|BPF_RSH|BPF_K:
			A >>= pc->k;
			continue;

		case BPF_ALU|BPF_NEG:
			(int)A = -((int)A);
			continue;

		case BPF_MISC|BPF_TAX:
			X = A;
			continue;

		case BPF_MISC|BPF_TXA:
			A = X;
			continue;
		}
	}
}


/*
 * Execute the filter program starting at pc on the packet whose header is 
 * pointed by p and whose data is pointed by pd.
 * headersize is the size of the the header
 * wirelen is the length of the original packet
 * buflen is the amount of data present
 */

u_int bpf_filter_with_2_buffers(pc, p, pd, headersize, wirelen, buflen)
	register struct bpf_insn *pc;
	register u_char *p;
	register u_char *pd;
	register int headersize; 
	u_int wirelen;
	register u_int buflen;
{
	register u_int32 A, X;
	register int k;
	int32 mem[BPF_MEMWORDS];

	if (pc == 0)
		/*
		 * No filter means accept all.
		 */
		return (u_int)-1;
	A = 0;
	X = 0;
	--pc;
	while (1) {
		++pc;
		switch (pc->code) {

		default:
		
			return 0;

		case BPF_RET|BPF_K:
			return (u_int)pc->k;

		case BPF_RET|BPF_A:
			return (u_int)A;

		case BPF_LD|BPF_W|BPF_ABS:
			k = pc->k;
			if (k + sizeof(int32) > buflen) {
				return 0;
			}
			
			if(k + (int)sizeof(int32) < headersize) A = EXTRACT_LONG(&p[k]);
			else if(k + 2 == headersize){
				A=(u_int32)*((u_char *)p+k)<<24|
					(u_int32)*((u_char *)p+k+1)<<16|
					(u_int32)*((u_char *)p+k+2)<<8|
					(u_int32)*((u_char *)pd+k-headersize);
			}
			else if(k == headersize-1){
				A=(u_int32)*((u_char *)p+k)<<24|
					(u_int32)*((u_char *)p+k+1)<<16|
					(u_int32)*((u_char *)pd+k-headersize)<<8|
					(u_int32)*((u_char *)pd+k-headersize+1);
			}
			else if(k == headersize){
				A=(u_int32)*((u_char *)p+k)<<24|
					(u_int32)*((u_char *)pd+k-headersize+1)<<16|
					(u_int32)*((u_char *)pd+k-headersize+2)<<8|
					(u_int32)*((u_char *)pd+k-headersize+3);
			}
			A = EXTRACT_LONG(&pd[k-headersize]);
			
			continue;
			
		case BPF_LD|BPF_H|BPF_ABS:
			k = pc->k;
			if (k + sizeof(short) > buflen) {
				return 0;
			}
			
			if(k + (int)sizeof(short) < headersize) A = EXTRACT_SHORT(&p[k]);
			else if(k == headersize){
				A=(u_short)*((u_char *)p+k)<<8|
					(u_short)*((u_char *)pd+k-headersize);
			}
			A = EXTRACT_SHORT(&pd[k-headersize]);
			
			continue;

		case BPF_LD|BPF_B|BPF_ABS:
			k = pc->k;
			if ((int)k >= (int)buflen) {
				return 0;
			}

			if(k<headersize) A = p[k];
			 else A = pd[k-headersize];

			continue;

		case BPF_LD|BPF_W|BPF_LEN:
			A = wirelen;
			continue;

		case BPF_LDX|BPF_W|BPF_LEN:
			X = wirelen;
			continue;

		case BPF_LD|BPF_W|BPF_IND:
			k = X + pc->k;
			if (k + sizeof(int32) > buflen) {
				return 0;
			}

			if(k + (int)sizeof(int32) < headersize) A = EXTRACT_LONG(&p[k]);
			else if(k + (int)sizeof(int32) == headersize+2){
				A=(u_int32)*((u_char *)p+k)<<24|
					(u_int32)*((u_char *)p+k+1)<<16|
					(u_int32)*((u_char *)p+k+2)<<8|
					(u_int32)*((u_char *)pd+k-headersize);
			}
			else if(k + (int)sizeof(int32) == headersize+3){
				A=(u_int32)*((u_char *)p+k)<<24|
					(u_int32)*((u_char *)p+k+1)<<16|
					(u_int32)*((u_char *)pd+k-headersize)<<8|
					(u_int32)*((u_char *)pd+k-headersize+1);
			}
			else if(k + (int)sizeof(int32) == headersize+4){
				A=(u_int32)*((u_char *)p+k)<<24|
					(u_int32)*((u_char *)pd+k-headersize+1)<<16|
					(u_int32)*((u_char *)pd+k-headersize+2)<<8|
					(u_int32)*((u_char *)pd+k-headersize+3);
			}
			A = EXTRACT_LONG(&pd[k-headersize]);
			
			continue;
			
		case BPF_LD|BPF_H|BPF_IND:
			k = X + pc->k;
			if (k + sizeof(short) > buflen) {
				return 0;
			}
			
			if(k + (int)sizeof(short) < headersize) A = EXTRACT_SHORT(&p[k]);
			else if(k == headersize){
				A=(u_short)*((u_char *)p+k)<<8|
					(u_short)*((u_char *)pd+k-headersize);
			}
			A = EXTRACT_SHORT(&pd[k-headersize]);

			continue;

		case BPF_LD|BPF_B|BPF_IND:
			k = X + pc->k;
			if ((int)k >= (int)buflen) {
				return 0;
			}

			if(k<headersize) A = p[k];
			 else A = pd[k-headersize];

			continue;

		case BPF_LDX|BPF_MSH|BPF_B:
			k = pc->k;
			if ((int)k >= (int)buflen) {
				return 0;
			}
			
			if((pc->k)<headersize) X = (p[pc->k] & 0xf) << 2;
			 else X = (pd[(pc->k)-headersize] & 0xf) << 2;

			continue;

		case BPF_LD|BPF_IMM:
			A = pc->k;
			continue;

		case BPF_LDX|BPF_IMM:
			X = pc->k;
			continue;

		case BPF_LD|BPF_MEM:
			A = mem[pc->k];
			continue;
			
		case BPF_LDX|BPF_MEM:
			X = mem[pc->k];
			continue;

		case BPF_ST:
			mem[pc->k] = A;
			continue;

		case BPF_STX:
			mem[pc->k] = X;
			continue;

		case BPF_JMP|BPF_JA:
			pc += pc->k;
			continue;

		case BPF_JMP|BPF_JGT|BPF_K:
			pc += ((int)A > (int)pc->k) ? pc->jt : pc->jf;
			continue;

		case BPF_JMP|BPF_JGE|BPF_K:
			pc += ((int)A >= (int)pc->k) ? pc->jt : pc->jf;
			continue;

		case BPF_JMP|BPF_JEQ|BPF_K:
			pc += ((int)A == (int)pc->k) ? pc->jt : pc->jf;
			continue;

		case BPF_JMP|BPF_JSET|BPF_K:
			pc += (A & pc->k) ? pc->jt : pc->jf;
			continue;

		case BPF_JMP|BPF_JGT|BPF_X:
			pc += (A > X) ? pc->jt : pc->jf;
			continue;

		case BPF_JMP|BPF_JGE|BPF_X:
			pc += (A >= X) ? pc->jt : pc->jf;
			continue;

		case BPF_JMP|BPF_JEQ|BPF_X:
			pc += (A == X) ? pc->jt : pc->jf;
			continue;

		case BPF_JMP|BPF_JSET|BPF_X:
			pc += (A & X) ? pc->jt : pc->jf;
			continue;

		case BPF_ALU|BPF_ADD|BPF_X:
			A += X;
			continue;
			
		case BPF_ALU|BPF_SUB|BPF_X:
			A -= X;
			continue;
			
		case BPF_ALU|BPF_MUL|BPF_X:
			A *= X;
			continue;
			
		case BPF_ALU|BPF_DIV|BPF_X:
			if (X == 0)
				return 0;
			A /= X;
			continue;
			
		case BPF_ALU|BPF_AND|BPF_X:
			A &= X;
			continue;
			
		case BPF_ALU|BPF_OR|BPF_X:
			A |= X;
			continue;

		case BPF_ALU|BPF_LSH|BPF_X:
			A <<= X;
			continue;

		case BPF_ALU|BPF_RSH|BPF_X:
			A >>= X;
			continue;

		case BPF_ALU|BPF_ADD|BPF_K:
			A += pc->k;
			continue;
			
		case BPF_ALU|BPF_SUB|BPF_K:
			A -= pc->k;
			continue;
			
		case BPF_ALU|BPF_MUL|BPF_K:
			A *= pc->k;
			continue;
			
		case BPF_ALU|BPF_DIV|BPF_K:
			A /= pc->k;
			continue;
			
		case BPF_ALU|BPF_AND|BPF_K:
			A &= pc->k;
			continue;
			
		case BPF_ALU|BPF_OR|BPF_K:
			A |= pc->k;
			continue;

		case BPF_ALU|BPF_LSH|BPF_K:
			A <<= pc->k;
			continue;

		case BPF_ALU|BPF_RSH|BPF_K:
			A >>= pc->k;
			continue;

		case BPF_ALU|BPF_NEG:
			(int)A = -((int)A);
			continue;

		case BPF_MISC|BPF_TAX:
			X = A;
			continue;

		case BPF_MISC|BPF_TXA:
			A = X;
			continue;
		}
	}
}


/*
 * Return true if the 'fcode' is a valid filter program.
 * The constraints are that each jump be forward and to a valid
 * code, that memory accesses are within valid ranges (to the
 * extent that this can be checked statically; loads of packet
 * data have to be, and are, also checked at run time), and that
 * the code terminates with either an accept or reject.
 *
 * The kernel needs to be able to verify an application's filter code.
 * Otherwise, a bogus program could easily crash the system.
 */
int
bpf_validate(f, len)
	struct bpf_insn *f;
	int len;
{
	register u_int32 i, from;
	register struct bpf_insn *p;

	if (len < 1)
		return 0;

	for (i = 0; i < len; ++i) {
		p = &f[i];
		switch (BPF_CLASS(p->code)) {
		/*
		 * Check that memory operations use valid addresses.
		 */
		case BPF_LD:
		case BPF_LDX:
			switch (BPF_MODE(p->code)) {
			case BPF_IMM:
				break;
			case BPF_ABS:
			case BPF_IND:
			case BPF_MSH:
				break;
			case BPF_MEM:
				if (p->k >= BPF_MEMWORDS)
					return 0;
				break;
			case BPF_LEN:
				break;
			default:
				return 0;
			}
			break;
		case BPF_ST:
		case BPF_STX:
			if (p->k >= BPF_MEMWORDS)
				return 0;
			break;
		case BPF_ALU:
			switch (BPF_OP(p->code)) {
			case BPF_ADD:
			case BPF_SUB:
			case BPF_OR:
			case BPF_AND:
			case BPF_LSH:
			case BPF_RSH:
			case BPF_NEG:
				break;
			case BPF_DIV:
				/*
				 * Check for constant division by 0.
				 */
				if (BPF_RVAL(p->code) == BPF_K && p->k == 0)
					return 0;
			default:
				return 0;
			}
			break;
		case BPF_JMP:
			/*
			 * Check that jumps are within the code block,
			 * and that unconditional branches don't go
			 * backwards as a result of an overflow.
			 * Unconditional branches have a 32-bit offset,
			 * so they could overflow; we check to make
			 * sure they don't.  Conditional branches have
			 * an 8-bit offset, and the from address is <=
			 * BPF_MAXINSNS, and we assume that BPF_MAXINSNS
			 * is sufficiently small that adding 255 to it
			 * won't overflow.
			 *
			 * We know that len is <= BPF_MAXINSNS, and we
			 * assume that BPF_MAXINSNS is < the maximum size
			 * of a u_int, so that i + 1 doesn't overflow.
			 */
			from = i + 1;
			switch (BPF_OP(p->code)) {
			case BPF_JA:
				if (from + p->k < from || from + p->k >= len)
					return 0;
				break;
			case BPF_JEQ:
			case BPF_JGT:
			case BPF_JGE:
			case BPF_JSET:
				if (from + p->jt >= len || from + p->jf >= len)
					return 0;
				break;
			default:
				return 0;
			}
			IF_LOUD(DbgPrint("Validating program: no wrong JUMPS");)
			break;
		case BPF_RET:
			break;
		case BPF_MISC:
			break;
		default:
			return 0;
		}
	}
	return BPF_CLASS(f[len - 1].code) == BPF_RET;
}
