dp.c

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/*
 * Copyright (c) 2011 Vojtech Horky
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - 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.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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 <stdio.h>
#include <str_error.h>
#include <errno.h>
#include <assert.h>
#include <bool.h>
#include <usb/dev/dp.h>
#include <usb/descriptor.h>

#define NESTING(parentname, childname) \
        { \
                .child = USB_DESCTYPE_##childname, \
                .parent = USB_DESCTYPE_##parentname, \
        }
#define LAST_NESTING { -1, -1 }

usb_dp_descriptor_nesting_t usb_dp_standard_descriptor_nesting[] = {
        NESTING(CONFIGURATION, INTERFACE),
        NESTING(INTERFACE, ENDPOINT),
        NESTING(INTERFACE, HUB),
        NESTING(INTERFACE, HID),
        NESTING(HID, HID_REPORT),
        LAST_NESTING
};

#undef NESTING
#undef LAST_NESTING

static bool is_valid_descriptor_pointer(usb_dp_parser_data_t *data,
    uint8_t *ptr)
{
        if (ptr == NULL) {
                return false;
        }

        if (ptr < data->data) {
                return false;
        }

        if ((size_t)(ptr - data->data) >= data->size) {
                return false;
        }

        return true;
}

static uint8_t *get_next_descriptor(usb_dp_parser_data_t *data,
    uint8_t *current)
{
        assert(is_valid_descriptor_pointer(data, current));

        uint8_t current_length = *current;
        uint8_t *next = current + current_length;

        if (!is_valid_descriptor_pointer(data, next)) {
                return NULL;
        }

        return next;
}

static int get_descriptor_type(usb_dp_parser_data_t *data, uint8_t *start)
{
        if (start == NULL) {
                return -1;
        }

        start++;
        if (!is_valid_descriptor_pointer(data, start)) {
                return -1;
        } else {
                return (int) (*start);
        }
}

static bool is_nested_descriptor_type(usb_dp_parser_t *parser,
    int child, int parent)
{
        usb_dp_descriptor_nesting_t *nesting = parser->nesting;
        while ((nesting->child > 0) && (nesting->parent > 0)) {
                if ((nesting->child == child) && (nesting->parent == parent)) {
                        return true;
                }
                nesting++;
        }
        return false;
}

static bool is_nested_descriptor(usb_dp_parser_t *parser,
    usb_dp_parser_data_t *data, uint8_t *child, uint8_t *parent)
{
        return is_nested_descriptor_type(parser,
            get_descriptor_type(data, child),
            get_descriptor_type(data, parent));
}

uint8_t *usb_dp_get_nested_descriptor(usb_dp_parser_t *parser,
    usb_dp_parser_data_t *data, uint8_t *parent)
{
        if (!is_valid_descriptor_pointer(data, parent)) {
                return NULL;
        }

        uint8_t *next = get_next_descriptor(data, parent);
        if (next == NULL) {
                return NULL;
        }

        if (is_nested_descriptor(parser, data, next, parent)) {
                return next;
        } else {
                return NULL;
        }
}

static uint8_t *skip_nested_descriptors(usb_dp_parser_t *parser,
    usb_dp_parser_data_t *data, uint8_t *parent)
{
        uint8_t *child = usb_dp_get_nested_descriptor(parser, data, parent);
        if (child == NULL) {
                return get_next_descriptor(data, parent);
        }
        uint8_t *next_child = skip_nested_descriptors(parser, data, child);
        while (is_nested_descriptor(parser, data, next_child, parent)) {
                next_child = skip_nested_descriptors(parser, data, next_child);
        }

        return next_child;
}

uint8_t *usb_dp_get_sibling_descriptor(usb_dp_parser_t *parser,
    usb_dp_parser_data_t *data, uint8_t *parent, uint8_t *sibling)
{
        if (!is_valid_descriptor_pointer(data, parent)
            || !is_valid_descriptor_pointer(data, sibling)) {
                return NULL;
        }

        uint8_t *possible_sibling = skip_nested_descriptors(parser, data, sibling);
        if (possible_sibling == NULL) {
                return NULL;
        }

        int parent_type = get_descriptor_type(data, parent);
        int possible_sibling_type = get_descriptor_type(data, possible_sibling);
        if (is_nested_descriptor_type(parser, possible_sibling_type, parent_type)) {
                return possible_sibling;
        } else {
                return NULL;
        }
}

static void usb_dp_browse_simple_internal(usb_dp_parser_t *parser,
    usb_dp_parser_data_t *data, uint8_t *root, size_t depth,
    void (*callback)(uint8_t *, size_t, void *), void *arg)
{
        if (root == NULL) {
                return;
        }
        callback(root, depth, arg);
        uint8_t *child = usb_dp_get_nested_descriptor(parser, data, root);
        do {
                usb_dp_browse_simple_internal(parser, data, child, depth + 1,
                    callback, arg);
                child = usb_dp_get_sibling_descriptor(parser, data,
                    root, child);
        } while (child != NULL);
}

void usb_dp_walk_simple(uint8_t *descriptors, size_t descriptors_size,
    usb_dp_descriptor_nesting_t *descriptor_nesting,
    void (*callback)(uint8_t *, size_t, void *), void *arg)
{
        if ((descriptors == NULL) || (descriptors_size == 0)
            || (descriptor_nesting == NULL) || (callback == NULL)) {
                return;
        }

        usb_dp_parser_data_t data = {
                .data = descriptors,
                .size = descriptors_size,
                .arg = NULL
        };

        usb_dp_parser_t parser = {
                .nesting = descriptor_nesting
        };

        usb_dp_browse_simple_internal(&parser, &data, descriptors,
            0, callback, arg);
}

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