nf_conntrack_h323_asn1.c

linux 内核源代码

		CHECK_BOUND(bs, 2);
		len = get_len(bs) + f->lb;
		break;
	default:		/* 2 <= Range <= 255 */
		len = get_bits(bs, f->sz) + f->lb;
		BYTE_ALIGN(bs);
		break;
	}

	bs->cur += len;

	PRINT("\n");

	CHECK_BOUND(bs, 0);
	return H323_ERROR_NONE;
}

/****************************************************************************/
int decode_bmpstr(bitstr_t * bs, field_t * f, char *base, int level)
{
	unsigned len;

	PRINT("%*.s%s\n", level * TAB_SIZE, " ", f->name);

	switch (f->sz) {
	case BYTE:		/* Range == 256 */
		BYTE_ALIGN(bs);
		CHECK_BOUND(bs, 1);
		len = (*bs->cur++) + f->lb;
		break;
	default:		/* 2 <= Range <= 255 */
		len = get_bits(bs, f->sz) + f->lb;
		BYTE_ALIGN(bs);
		break;
	}

	bs->cur += len << 1;

	CHECK_BOUND(bs, 0);
	return H323_ERROR_NONE;
}

/****************************************************************************/
int decode_seq(bitstr_t * bs, field_t * f, char *base, int level)
{
	unsigned ext, bmp, i, opt, len = 0, bmp2, bmp2_len;
	int err;
	field_t *son;
	unsigned char *beg = NULL;

	PRINT("%*.s%s\n", level * TAB_SIZE, " ", f->name);

	/* Decode? */
	base = (base && (f->attr & DECODE)) ? base + f->offset : NULL;

	/* Extensible? */
	ext = (f->attr & EXT) ? get_bit(bs) : 0;

	/* Get fields bitmap */
	bmp = get_bitmap(bs, f->sz);
	if (base)
		*(unsigned *) base = bmp;

	/* Decode the root components */
	for (i = opt = 0, son = f->fields; i < f->lb; i++, son++) {
		if (son->attr & STOP) {
			PRINT("%*.s%s\n", (level + 1) * TAB_SIZE, " ",
			      son->name);
			return H323_ERROR_STOP;
		}

		if (son->attr & OPT) {	/* Optional component */
			if (!((0x80000000U >> (opt++)) & bmp))	/* Not exist */
				continue;
		}

		/* Decode */
		if (son->attr & OPEN) {	/* Open field */
			CHECK_BOUND(bs, 2);
			len = get_len(bs);
			CHECK_BOUND(bs, len);
			if (!base || !(son->attr & DECODE)) {
				PRINT("%*.s%s\n", (level + 1) * TAB_SIZE,
				      " ", son->name);
				bs->cur += len;
				continue;
			}
			beg = bs->cur;

			/* Decode */
			if ((err = (Decoders[son->type]) (bs, son, base,
							  level + 1)) <
			    H323_ERROR_NONE)
				return err;

			bs->cur = beg + len;
			bs->bit = 0;
		} else if ((err = (Decoders[son->type]) (bs, son, base,
							 level + 1)) <
			   H323_ERROR_NONE)
			return err;
	}

	/* No extension? */
	if (!ext)
		return H323_ERROR_NONE;

	/* Get the extension bitmap */
	bmp2_len = get_bits(bs, 7) + 1;
	CHECK_BOUND(bs, (bmp2_len + 7) >> 3);
	bmp2 = get_bitmap(bs, bmp2_len);
	bmp |= bmp2 >> f->sz;
	if (base)
		*(unsigned *) base = bmp;
	BYTE_ALIGN(bs);

	/* Decode the extension components */
	for (opt = 0; opt < bmp2_len; opt++, i++, son++) {
		/* Check Range */
		if (i >= f->ub) {	/* Newer Version? */
			CHECK_BOUND(bs, 2);
			len = get_len(bs);
			CHECK_BOUND(bs, len);
			bs->cur += len;
			continue;
		}

		if (son->attr & STOP) {
			PRINT("%*.s%s\n", (level + 1) * TAB_SIZE, " ",
			      son->name);
			return H323_ERROR_STOP;
		}

		if (!((0x80000000 >> opt) & bmp2))	/* Not present */
			continue;

		CHECK_BOUND(bs, 2);
		len = get_len(bs);
		CHECK_BOUND(bs, len);
		if (!base || !(son->attr & DECODE)) {
			PRINT("%*.s%s\n", (level + 1) * TAB_SIZE, " ",
			      son->name);
			bs->cur += len;
			continue;
		}
		beg = bs->cur;

		if ((err = (Decoders[son->type]) (bs, son, base,
						  level + 1)) <
		    H323_ERROR_NONE)
			return err;

		bs->cur = beg + len;
		bs->bit = 0;
	}
	return H323_ERROR_NONE;
}

/****************************************************************************/
int decode_seqof(bitstr_t * bs, field_t * f, char *base, int level)
{
	unsigned count, effective_count = 0, i, len = 0;
	int err;
	field_t *son;
	unsigned char *beg = NULL;

	PRINT("%*.s%s\n", level * TAB_SIZE, " ", f->name);

	/* Decode? */
	base = (base && (f->attr & DECODE)) ? base + f->offset : NULL;

	/* Decode item count */
	switch (f->sz) {
	case BYTE:
		BYTE_ALIGN(bs);
		CHECK_BOUND(bs, 1);
		count = *bs->cur++;
		break;
	case WORD:
		BYTE_ALIGN(bs);
		CHECK_BOUND(bs, 2);
		count = *bs->cur++;
		count <<= 8;
		count = *bs->cur++;
		break;
	case SEMI:
		BYTE_ALIGN(bs);
		CHECK_BOUND(bs, 2);
		count = get_len(bs);
		break;
	default:
		count = get_bits(bs, f->sz);
		break;
	}
	count += f->lb;

	/* Write Count */
	if (base) {
		effective_count = count > f->ub ? f->ub : count;
		*(unsigned *) base = effective_count;
		base += sizeof(unsigned);
	}

	/* Decode nested field */
	son = f->fields;
	if (base)
		base -= son->offset;
	for (i = 0; i < count; i++) {
		if (son->attr & OPEN) {
			BYTE_ALIGN(bs);
			len = get_len(bs);
			CHECK_BOUND(bs, len);
			if (!base || !(son->attr & DECODE)) {
				PRINT("%*.s%s\n", (level + 1) * TAB_SIZE,
				      " ", son->name);
				bs->cur += len;
				continue;
			}
			beg = bs->cur;

			if ((err = (Decoders[son->type]) (bs, son,
							  i <
							  effective_count ?
							  base : NULL,
							  level + 1)) <
			    H323_ERROR_NONE)
				return err;

			bs->cur = beg + len;
			bs->bit = 0;
		} else
			if ((err = (Decoders[son->type]) (bs, son,
							  i <
							  effective_count ?
							  base : NULL,
							  level + 1)) <
			    H323_ERROR_NONE)
				return err;

		if (base)
			base += son->offset;
	}

	return H323_ERROR_NONE;
}


/****************************************************************************/
int decode_choice(bitstr_t * bs, field_t * f, char *base, int level)
{
	unsigned type, ext, len = 0;
	int err;
	field_t *son;
	unsigned char *beg = NULL;

	PRINT("%*.s%s\n", level * TAB_SIZE, " ", f->name);

	/* Decode? */
	base = (base && (f->attr & DECODE)) ? base + f->offset : NULL;

	/* Decode the choice index number */
	if ((f->attr & EXT) && get_bit(bs)) {
		ext = 1;
		type = get_bits(bs, 7) + f->lb;
	} else {
		ext = 0;
		type = get_bits(bs, f->sz);
		if (type >= f->lb)
			return H323_ERROR_RANGE;
	}

	/* Write Type */
	if (base)
		*(unsigned *) base = type;

	/* Check Range */
	if (type >= f->ub) {	/* Newer version? */
		BYTE_ALIGN(bs);
		len = get_len(bs);
		CHECK_BOUND(bs, len);
		bs->cur += len;
		return H323_ERROR_NONE;
	}

	/* Transfer to son level */
	son = &f->fields[type];
	if (son->attr & STOP) {
		PRINT("%*.s%s\n", (level + 1) * TAB_SIZE, " ", son->name);
		return H323_ERROR_STOP;
	}

	if (ext || (son->attr & OPEN)) {
		BYTE_ALIGN(bs);
		len = get_len(bs);
		CHECK_BOUND(bs, len);
		if (!base || !(son->attr & DECODE)) {
			PRINT("%*.s%s\n", (level + 1) * TAB_SIZE, " ",
			      son->name);
			bs->cur += len;
			return H323_ERROR_NONE;
		}
		beg = bs->cur;

		if ((err = (Decoders[son->type]) (bs, son, base, level + 1)) <
		    H323_ERROR_NONE)
			return err;

		bs->cur = beg + len;
		bs->bit = 0;
	} else if ((err = (Decoders[son->type]) (bs, son, base, level + 1)) <
		   H323_ERROR_NONE)
		return err;

	return H323_ERROR_NONE;
}

/****************************************************************************/
int DecodeRasMessage(unsigned char *buf, size_t sz, RasMessage * ras)
{
	static field_t ras_message = {
		FNAME("RasMessage") CHOICE, 5, 24, 32, DECODE | EXT,
		0, _RasMessage
	};
	bitstr_t bs;

	bs.buf = bs.beg = bs.cur = buf;
	bs.end = buf + sz;
	bs.bit = 0;

	return decode_choice(&bs, &ras_message, (char *) ras, 0);
}

/****************************************************************************/
static int DecodeH323_UserInformation(unsigned char *buf, unsigned char *beg,
				      size_t sz, H323_UserInformation * uuie)
{
	static field_t h323_userinformation = {
		FNAME("H323-UserInformation") SEQ, 1, 2, 2, DECODE | EXT,
		0, _H323_UserInformation
	};
	bitstr_t bs;

	bs.buf = buf;
	bs.beg = bs.cur = beg;
	bs.end = beg + sz;
	bs.bit = 0;

	return decode_seq(&bs, &h323_userinformation, (char *) uuie, 0);
}

/****************************************************************************/
int DecodeMultimediaSystemControlMessage(unsigned char *buf, size_t sz,
					 MultimediaSystemControlMessage *
					 mscm)
{
	static field_t multimediasystemcontrolmessage = {
		FNAME("MultimediaSystemControlMessage") CHOICE, 2, 4, 4,
		DECODE | EXT, 0, _MultimediaSystemControlMessage
	};
	bitstr_t bs;

	bs.buf = bs.beg = bs.cur = buf;
	bs.end = buf + sz;
	bs.bit = 0;

	return decode_choice(&bs, &multimediasystemcontrolmessage,
			     (char *) mscm, 0);
}

/****************************************************************************/
int DecodeQ931(unsigned char *buf, size_t sz, Q931 * q931)
{
	unsigned char *p = buf;
	int len;

	if (!p || sz < 1)
		return H323_ERROR_BOUND;

	/* Protocol Discriminator */
	if (*p != 0x08) {
		PRINT("Unknown Protocol Discriminator\n");
		return H323_ERROR_RANGE;
	}
	p++;
	sz--;

	/* CallReferenceValue */
	if (sz < 1)
		return H323_ERROR_BOUND;
	len = *p++;
	sz--;
	if (sz < len)
		return H323_ERROR_BOUND;
	p += len;
	sz -= len;

	/* Message Type */
	if (sz < 1)
		return H323_ERROR_BOUND;
	q931->MessageType = *p++;
	PRINT("MessageType = %02X\n", q931->MessageType);
	if (*p & 0x80) {
		p++;
		sz--;
	}

	/* Decode Information Elements */
	while (sz > 0) {
		if (*p == 0x7e) {	/* UserUserIE */
			if (sz < 3)
				break;
			p++;
			len = *p++ << 8;
			len |= *p++;
			sz -= 3;
			if (sz < len)
				break;
			p++;
			len--;
			return DecodeH323_UserInformation(buf, p, len,
							  &q931->UUIE);
		}
		p++;
		sz--;
		if (sz < 1)
			break;
		len = *p++;
		if (sz < len)
			break;
		p += len;
		sz -= len;
	}

	PRINT("Q.931 UUIE not found\n");

	return H323_ERROR_BOUND;
}