xref: /openbsd-src/lib/libusbhid/parse.c (revision 2c53affbcc0119d6480b86c18f2790523b6a0aad)

/*	$OpenBSD: parse.c,v 1.13 2022/12/27 17:10:07 jmc Exp $	*/
/*	$NetBSD: parse.c,v 1.2 2001/12/29 20:44:22 augustss Exp $	*/

/*
 * Copyright (c) 1999, 2001 Lennart Augustsson <augustss@netbsd.org>
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
 */

#include <stdlib.h>
#include <string.h>

#include <dev/usb/usb.h>
#include <dev/usb/usbhid.h>

#include "usbhid.h"
#include "usbvar.h"

#define	MAXUSAGE 100
#define	MAXPUSH 4
#define	MAXID 64
#define	ITEMTYPES 3

struct hid_pos_data {
	int32_t rid;
	uint32_t pos[ITEMTYPES];
};

struct hid_data {
	const uint8_t *start;
	const uint8_t *end;
	const uint8_t *p;
	struct hid_item cur[MAXPUSH];
	struct hid_pos_data last_pos[MAXID];
	uint32_t pos[ITEMTYPES];
	int32_t usages_min[MAXUSAGE];
	int32_t usages_max[MAXUSAGE];
	int32_t usage_last;	/* last seen usage */
	uint32_t loc_size;	/* last seen size */
	uint32_t loc_count;	/* last seen count */
	uint8_t	kindset;	/* we have 5 kinds so 8 bits are enough */
	uint8_t	pushlevel;	/* current pushlevel */
	uint8_t	ncount;		/* end usage item count */
	uint8_t icount;		/* current usage item count */
	uint8_t	nusage;		/* end "usages_min/max" index */
	uint8_t	iusage;		/* current "usages_min/max" index */
	uint8_t ousage;		/* current "usages_min/max" offset */
	uint8_t	susage;		/* usage set flags */
	int32_t	reportid;	/* requested report ID */
	struct hid_item savedcoll; /* save coll until we know the ID */
	uint8_t hassavedcoll;
};

static void
hid_clear_local(hid_item_t *c)
{

	c->usage = 0;
	c->usage_minimum = 0;
	c->usage_maximum = 0;
	c->designator_index = 0;
	c->designator_minimum = 0;
	c->designator_maximum = 0;
	c->string_index = 0;
	c->string_minimum = 0;
	c->string_maximum = 0;
	c->set_delimiter = 0;
}

static void
hid_switch_rid(struct hid_data *s, struct hid_item *c, int32_t next_rID)
{
	uint8_t i, j;

	/* check for same report ID - optimise */

	if (c->report_ID == next_rID)
		return;

	/* save current position for current rID */

	if (c->report_ID == 0) {
		i = 0;
	} else {
		for (i = 1; i != MAXID; i++) {
			if (s->last_pos[i].rid == c->report_ID)
				break;
			if (s->last_pos[i].rid == 0)
				break;
		}
	}
	if (i != MAXID) {
		s->last_pos[i].rid = c->report_ID;
		for (j = 0; j < ITEMTYPES; j++)
			s->last_pos[i].pos[j] = s->pos[j];
	}

	/* store next report ID */

	c->report_ID = next_rID;

	/* lookup last position for next rID */

	if (next_rID == 0) {
		i = 0;
	} else {
		for (i = 1; i != MAXID; i++) {
			if (s->last_pos[i].rid == next_rID)
				break;
			if (s->last_pos[i].rid == 0)
				break;
		}
	}
	if (i != MAXID) {
		s->last_pos[i].rid = next_rID;
		for (j = 0; j < ITEMTYPES; j++)
			s->pos[j] = s->last_pos[i].pos[j];
	} else {
		for (j = 0; j < ITEMTYPES; j++)
			s->pos[j] = 0;	/* Out of RID entries. */
	}
}

hid_data_t
hid_start_parse(report_desc_t d, int kindset, int id)
{
	struct hid_data *s;

	s = calloc(1, sizeof *s);
	if (s == NULL)
		return (NULL);
	s->start = s->p = d->data;
	s->end = d->data + d->size;
	s->kindset = kindset;
	s->reportid = id;
	s->hassavedcoll = 0;
	return (s);
}

void
hid_end_parse(hid_data_t s)
{

	if (s == NULL)
		return;

	free(s);
}

static uint8_t
hid_get_byte(struct hid_data *s, const uint16_t wSize)
{
	const uint8_t *ptr;
	uint8_t retval;

	ptr = s->p;

	/* check if end is reached */
	if (ptr == s->end)
		return (0);

	/* read out a byte */
	retval = *ptr;

	/* check if data pointer can be advanced by "wSize" bytes */
	if ((s->end - ptr) < wSize)
		ptr = s->end;
	else
		ptr += wSize;

	/* update pointer */
	s->p = ptr;

	return (retval);
}

#define REPORT_SAVED_COLL \
	do { \
		if (s->hassavedcoll) { \
			*h = s->savedcoll; \
			h->report_ID = c->report_ID; \
			s->hassavedcoll = 0; \
			return (1); \
		} \
	} while(0)

static int
hid_get_item_raw(hid_data_t s, hid_item_t *h)
{
	hid_item_t nc, *c;
	unsigned int bTag, bType, bSize;
	int32_t mask;
	int32_t dval;

	if (s == NULL)
		return (0);

	if (s->pushlevel >= MAXPUSH)
		return (0);

	c = &s->cur[s->pushlevel];

 top:
	/* check if there is an array of items */
	if (s->icount < s->ncount) {
		REPORT_SAVED_COLL;
		/* get current usage */
		if (s->iusage < s->nusage) {
			dval = s->usages_min[s->iusage] + s->ousage;
			c->usage = dval;
			s->usage_last = dval;
			if (dval == s->usages_max[s->iusage]) {
				s->iusage ++;
				s->ousage = 0;
			} else {
				s->ousage ++;
			}
		} else {
			/* Using last usage */
			dval = s->usage_last;
		}
		s->icount ++;
		/*
		 * Only copy HID item, increment position and return
		 * if correct kindset!
		 */
		if (s->kindset & (1 << c->kind)) {
			*h = *c;
			h->pos = s->pos[c->kind];
			s->pos[c->kind] += c->report_size * c->report_count;
			return (1);
		}
	}

	/* reset state variables */
	s->icount = 0;
	s->ncount = 0;
	s->iusage = 0;
	s->nusage = 0;
	s->susage = 0;
	s->ousage = 0;
	hid_clear_local(c);

	/* get next item */
	while (s->p != s->end) {

		bSize = hid_get_byte(s, 1);
		if (bSize == 0xfe) {
			/* long item */
			bSize = hid_get_byte(s, 1);
			bSize |= hid_get_byte(s, 1) << 8;
			bTag = hid_get_byte(s, 1);
			bType = 0xff;	/* XXX what should it be */
		} else {
			/* short item */
			bTag = bSize >> 4;
			bType = (bSize >> 2) & 3;
			bSize &= 3;
			if (bSize == 3)
				bSize = 4;
		}

		switch(bSize) {
		case 0:
			dval = 0;
			mask = 0;
			break;
		case 1:
			dval = (int8_t)hid_get_byte(s, 1);
			mask = 0xFF;
			break;
		case 2:
			dval = hid_get_byte(s, 1);
			dval |= hid_get_byte(s, 1) << 8;
			dval = (int16_t)dval;
			mask = 0xFFFF;
			break;
		case 4:
			dval = hid_get_byte(s, 1);
			dval |= hid_get_byte(s, 1) << 8;
			dval |= hid_get_byte(s, 1) << 16;
			dval |= hid_get_byte(s, 1) << 24;
			mask = 0xFFFFFFFF;
			break;
		default:
			dval = hid_get_byte(s, bSize);
			continue;
		}

		switch (bType) {
		case 0:		/* Main */
			switch (bTag) {
			case 8:	/* Input */
				c->kind = hid_input;
				c->flags = dval;
		ret:
				c->report_count = s->loc_count;
				c->report_size = s->loc_size;

				if (c->flags & HIO_VARIABLE) {
					/* range check usage count */
					if (c->report_count > 255) {
						s->ncount = 255;
					} else
						s->ncount = c->report_count;

					/*
					 * The "top" loop will return
					 * one and one item:
					 */
					c->report_count = 1;
					c->usage_minimum = 0;
					c->usage_maximum = 0;
				} else {
					s->ncount = 1;
				}
				goto top;

			case 9:	/* Output */
				c->kind = hid_output;
				c->flags = dval;
				goto ret;
			case 10:	/* Collection */
				c->kind = hid_collection;
				c->collection = dval;
				c->collevel++;
				c->usage = s->usage_last;
				nc = *c;
				if (s->hassavedcoll) {
					*h = s->savedcoll;
					h->report_ID = nc.report_ID;
					s->savedcoll = nc;
					return (1);
				} else {
					s->hassavedcoll = 1;
					s->savedcoll = nc;
				}
				goto top;
			case 11:	/* Feature */
				c->kind = hid_feature;
				c->flags = dval;
				goto ret;
			case 12:	/* End collection */
				REPORT_SAVED_COLL;
				c->kind = hid_endcollection;
				if (c->collevel == 0) {
					/* Invalid end collection. */
					return (0);
				}
				c->collevel--;
				*h = *c;
				return (1);
			default:
				break;
			}
			break;

		case 1:		/* Global */
			switch (bTag) {
			case 0:
				c->_usage_page = dval << 16;
				break;
			case 1:
				c->logical_minimum = dval;
				break;
			case 2:
				c->logical_maximum = dval;
				break;
			case 3:
				c->physical_minimum = dval;
				break;
			case 4:
				c->physical_maximum = dval;
				break;
			case 5:
				c->unit_exponent = dval;
				break;
			case 6:
				c->unit = dval;
				break;
			case 7:
				/* mask because value is unsigned */
				s->loc_size = dval & mask;
				break;
			case 8:
				hid_switch_rid(s, c, dval & mask);
				break;
			case 9:
				/* mask because value is unsigned */
				s->loc_count = dval & mask;
				break;
			case 10:	/* Push */
				if (s->pushlevel < MAXPUSH - 1) {
					s->pushlevel++;
					s->cur[s->pushlevel] = *c;
					/* store size and count */
					c->report_size = s->loc_size;
					c->report_count = s->loc_count;
					/* update current item pointer */
					c = &s->cur[s->pushlevel];
				}
				break;
			case 11:	/* Pop */
				if (s->pushlevel > 0) {
					s->pushlevel--;
					c = &s->cur[s->pushlevel];
					/* restore size and count */
					s->loc_size = c->report_size;
					s->loc_count = c->report_count;
					c->report_size = 0;
					c->report_count = 0;
				}
				break;
			default:
				break;
			}
			break;
		case 2:		/* Local */
			switch (bTag) {
			case 0:
				if (bSize != 4)
					dval = (dval & mask) | c->_usage_page;

				/* set last usage, in case of a collection */
				s->usage_last = dval;

				if (s->nusage < MAXUSAGE) {
					s->usages_min[s->nusage] = dval;
					s->usages_max[s->nusage] = dval;
					s->nusage ++;
				}
				/* else XXX */

				/* clear any pending usage sets */
				s->susage = 0;
				break;
			case 1:
				s->susage |= 1;

				if (bSize != 4)
					dval = (dval & mask) | c->_usage_page;
				c->usage_minimum = dval;

				goto check_set;
			case 2:
				s->susage |= 2;

				if (bSize != 4)
					dval = (dval & mask) | c->_usage_page;
				c->usage_maximum = dval;

			check_set:
				if (s->susage != 3)
					break;

				/* sanity check */
				if ((s->nusage < MAXUSAGE) &&
				    (c->usage_minimum <= c->usage_maximum)) {
					/* add usage range */
					s->usages_min[s->nusage] =
					    c->usage_minimum;
					s->usages_max[s->nusage] =
					    c->usage_maximum;
					s->nusage ++;
				}
				/* else XXX */

				s->susage = 0;
				break;
			case 3:
				c->designator_index = dval;
				break;
			case 4:
				c->designator_minimum = dval;
				break;
			case 5:
				c->designator_maximum = dval;
				break;
			case 7:
				c->string_index = dval;
				break;
			case 8:
				c->string_minimum = dval;
				break;
			case 9:
				c->string_maximum = dval;
				break;
			case 10:
				c->set_delimiter = dval;
				break;
			default:
				break;
			}
			break;
		default:
			break;
		}
	}
	return (0);
}

int
hid_get_item(hid_data_t s, hid_item_t *h)
{
	int r;

	for (;;) {
		r = hid_get_item_raw(s, h);
		if (r <= 0 || s->reportid == -1 || h->report_ID == s->reportid)
			break;
	}
	return (r);
}

int
hid_report_size(report_desc_t r, enum hid_kind k, int id)
{
	struct hid_data *d;
	struct hid_item h;
	uint32_t temp;
	uint32_t hpos;
	uint32_t lpos;
	int report_id = 0;

	hpos = 0;
	lpos = 0xFFFFFFFF;

	memset(&h, 0, sizeof h);
	for (d = hid_start_parse(r, 1 << k, id); hid_get_item(d, &h); ) {
		if (h.kind == k) {
			/* compute minimum */
			if (lpos > h.pos)
				lpos = h.pos;
			/* compute end position */
			temp = h.pos + (h.report_size * h.report_count);
			/* compute maximum */
			if (hpos < temp)
				hpos = temp;
			if (h.report_ID != 0)
				report_id = 1;
		}
	}
	hid_end_parse(d);

	/* safety check - can happen in case of corrupt descriptors */
	if (lpos > hpos)
		temp = 0;
	else
		temp = hpos - lpos;

	/* No extra byte for the reportID because the kernel skips it. */
	return ((temp + 7) / 8);
}

int
hid_locate(report_desc_t desc, unsigned int u, enum hid_kind k,
    hid_item_t *h, int id)
{
	struct hid_data *d;

	for (d = hid_start_parse(desc, 1 << k, id); hid_get_item(d, h); ) {
		if (h->kind == k && !(h->flags & HIO_CONST) && h->usage == u) {
			hid_end_parse(d);
			return (1);
		}
	}
	hid_end_parse(d);
	h->report_size = 0;
	return (0);
}