// SPDX-License-Identifier: MIT
/*
 * Copyright (C) 2016 The Android Open Source Project
 */

#include <libavb/avb_descriptor.h>
#include <libavb/avb_util.h>
#include <libavb/avb_vbmeta_image.h>

bool avb_descriptor_validate_and_byteswap(const AvbDescriptor* src,
                                          AvbDescriptor* dest) {
  dest->tag = avb_be64toh(src->tag);
  dest->num_bytes_following = avb_be64toh(src->num_bytes_following);

  if ((dest->num_bytes_following & 0x07) != 0) {
    avb_error("Descriptor size is not divisible by 8.\n");
    return false;
  }
  return true;
}

bool avb_descriptor_foreach(const uint8_t* image_data,
			    size_t image_size,
			    AvbDescriptorForeachFunc foreach_func,
			    void *user_data)
{
	const AvbVBMetaImageHeader *header = NULL;
	bool ret = false;
	const uint8_t *image_end;
	const uint8_t *desc_start;
	const uint8_t *desc_end;
	const uint8_t *p;
	uint64_t desc_offset = 0;
	uint64_t desc_size = 0;

	if (!image_data) {
		avb_error("image_data is NULL\n.");
		goto out;
	}

	if (!foreach_func) {
		avb_error("foreach_func is NULL\n.");
		goto out;
	}

	if (image_size < sizeof(AvbVBMetaImageHeader)) {
		avb_error("Length is smaller than header.\n");
		goto out;
	}

	/* Ensure magic is correct. */
	if (avb_memcmp(image_data, AVB_MAGIC, AVB_MAGIC_LEN) != 0) {
		avb_error("Magic is incorrect.\n");
		goto out;
	}

	/* Careful, not byteswapped - also ensure it's aligned properly. */
	avb_assert_aligned(image_data);
	header = (const AvbVBMetaImageHeader *)image_data;
	image_end = image_data + image_size;

	/* Since the data is supposed to have been cryptographically verified at this
	 * point, being overflow-safe is just for defense.
	 * The following lines are overflow-safe version of:
	 * desc_offset = sizeof(AvbVBMetaImageHeader) +
	 *               avb_be64toh(header->authentication_data_block_size)) +
	 *               avb_be64toh(header->descriptors_offset)
	 */
	if (!avb_safe_add(&desc_offset,
				sizeof(AvbVBMetaImageHeader),
				avb_be64toh(header->authentication_data_block_size))) {
		avb_error("Invalid authentication data block size.\n");
		goto out;
	}
	if (!avb_safe_add_to(&desc_offset, avb_be64toh(header->descriptors_offset))) {
		avb_error("Invalid descriptors offset.\n");
		goto out;
	}

	if (desc_offset > (uint64_t)(image_end - image_data)) {
		avb_error("Descriptors not inside passed-in data.\n");
		goto out;
	}

	desc_start = image_data + desc_offset;

	desc_size = avb_be64toh(header->descriptors_size);
	if (desc_size > (uint64_t)(image_end - desc_start)) {
		avb_error("Descriptors not inside passed-in data.\n");
		goto out;
	}

	desc_end = desc_start + desc_size;

	for (p = desc_start; p < desc_end;) {
		uint64_t nb_following;
		uint64_t nb_total = 0;

		const AvbDescriptor *dh;

		if (sizeof(AvbDescriptor) > (size_t)(desc_end - p)) {
			avb_error("Invalid descriptor length.\n");
			goto out;
		}

		dh = (const AvbDescriptor *)p;
		avb_assert_aligned(dh);
		nb_following = avb_be64toh(dh->num_bytes_following);

		if (!avb_safe_add(&nb_total, sizeof(AvbDescriptor), nb_following)) {
			avb_error("Invalid descriptor length.\n");
			goto out;
		}

		if ((nb_total & 7) != 0) {
			avb_error("Invalid descriptor length.\n");
			goto out;
		}

		if (nb_total > (uint64_t)(desc_end - p)) {
			avb_error("Invalid data in descriptors array.\n");
			goto out;
		}

		if (foreach_func(dh, user_data) == 0)
			goto out;

		p += nb_total;
	}

	ret = true;

out:
	return ret;
}

static bool count_descriptors(const AvbDescriptor* descriptor,
                              void* user_data) {
  size_t* num_descriptors = user_data;
  *num_descriptors += 1;
  return true;
}

typedef struct {
  size_t descriptor_number;
  const AvbDescriptor** descriptors;
} SetDescriptorData;

static bool set_descriptors(const AvbDescriptor* descriptor, void* user_data) {
  SetDescriptorData* data = user_data;
  data->descriptors[data->descriptor_number++] = descriptor;
  return true;
}

const AvbDescriptor** avb_descriptor_get_all(const uint8_t* image_data,
                                             size_t image_size,
                                             size_t* out_num_descriptors) {
  size_t num_descriptors = 0;
  SetDescriptorData data;

  avb_descriptor_foreach(
      image_data, image_size, count_descriptors, &num_descriptors);

  data.descriptor_number = 0;
  data.descriptors =
      avb_calloc(sizeof(const AvbDescriptor*) * (num_descriptors + 1));
  if (data.descriptors == NULL) {
    return NULL;
  }
  avb_descriptor_foreach(image_data, image_size, set_descriptors, &data);
  avb_assert(data.descriptor_number == num_descriptors);

  if (out_num_descriptors != NULL) {
    *out_num_descriptors = num_descriptors;
  }

  return data.descriptors;
}