android/libwvdrmengine/oemcrypto/odk/src/serialization_base.c

// Copyright 2019 Google LLC. All rights reserved. This file and proprietary
// source code may only be used and distributed under the Widevine
// License Agreement.

#include "serialization_base.h"

#include <assert.h>
#include <stddef.h>
#include <stdint.h>
#include <string.h>

#include "OEMCryptoCENCCommon.h"
#include "odk_message.h"
#include "odk_message_priv.h"
#include "odk_overflow.h"

/*
 * An ODK_Message_Impl pointer must only be obtained by calling GetMessageImpl.
 * This forces any message to pass the validity check before being operated on,
 * which means that no function can modify or access the internals of a message
 * without having it be validated first.
 */
static ODK_Message_Impl* GetMessageImpl(ODK_Message* message) {
  if (!ODK_Message_IsValid(message)) return NULL;
  return (ODK_Message_Impl*)message;
}

static void PackBytes(ODK_Message* message, const uint8_t* ptr, size_t count) {
  ODK_Message_Impl* message_impl = GetMessageImpl(message);
  if (!message_impl) return;
  if (count <= message_impl->capacity - message_impl->size) {
    memcpy((void*)(message_impl->base + message_impl->size), (const void*)ptr,
           count);
    message_impl->size += count;
  } else {
    message_impl->status = MESSAGE_STATUS_OVERFLOW_ERROR;
  }
}

void Pack_enum(ODK_Message* message, int value) {
  uint32_t v32 = value;
  Pack_uint32_t(message, &v32);
}

void Pack_bool(ODK_Message* message, const bool* value) {
  assert(value);
  uint8_t data[4] = {0};
  data[3] = *value ? 1 : 0;
  PackBytes(message, data, sizeof(data));
}

void Pack_uint16_t(ODK_Message* message, const uint16_t* value) {
  assert(value);
  uint8_t data[2] = {0};
  data[0] = (uint8_t)(*value >> 8);
  data[1] = (uint8_t)(*value >> 0);
  PackBytes(message, data, sizeof(data));
}

void Pack_uint32_t(ODK_Message* message, const uint32_t* value) {
  assert(value);
  uint8_t data[4] = {0};
  data[0] = (uint8_t)(*value >> 24);
  data[1] = (uint8_t)(*value >> 16);
  data[2] = (uint8_t)(*value >> 8);
  data[3] = (uint8_t)(*value >> 0);
  PackBytes(message, data, sizeof(data));
}

void Pack_uint64_t(ODK_Message* message, const uint64_t* value) {
  assert(value);
  uint32_t hi = (uint32_t)(*value >> 32);
  uint32_t lo = (uint32_t)(*value);
  Pack_uint32_t(message, &hi);
  Pack_uint32_t(message, &lo);
}

void PackArray(ODK_Message* message, const uint8_t* base, size_t size) {
  PackBytes(message, base, size);
}

void Pack_OEMCrypto_Substring(ODK_Message* message,
                              const OEMCrypto_Substring* obj) {
  assert(obj);
  uint32_t offset = (uint32_t)obj->offset;
  uint32_t length = (uint32_t)obj->length;
  Pack_uint32_t(message, &offset);
  Pack_uint32_t(message, &length);
}

static void UnpackBytes(ODK_Message* message, uint8_t* ptr, size_t count) {
  assert(ptr);
  ODK_Message_Impl* message_impl = GetMessageImpl(message);
  if (!message_impl) return;
  if (count <= message_impl->size - message_impl->read_offset) {
    memcpy((void*)ptr, (void*)(message_impl->base + message_impl->read_offset),
           count);
    message_impl->read_offset += count;
  } else {
    message_impl->status = MESSAGE_STATUS_UNDERFLOW_ERROR;
  }
}

int Unpack_enum(ODK_Message* message) {
  uint32_t v32;
  Unpack_uint32_t(message, &v32);
  return (int)v32;
}

void Unpack_bool(ODK_Message* message, bool* value) {
  uint8_t data[4] = {0};
  UnpackBytes(message, data, sizeof(data));
  assert(value);
  *value = (0 != data[3]);
}

void Unpack_uint16_t(ODK_Message* message, uint16_t* value) {
  assert(value);
  uint8_t data[2] = {0};
  UnpackBytes(message, data, sizeof(data));
  *value = data[0];
  *value = *value << 8 | data[1];
}

void Unpack_uint32_t(ODK_Message* message, uint32_t* value) {
  ODK_Message_Impl* message_impl = GetMessageImpl(message);
  if (!message_impl) return;
  uint8_t data[4] = {0};
  UnpackBytes(message, data, sizeof(data));
  assert(value);
  *value = data[0];
  *value = *value << 8 | data[1];
  *value = *value << 8 | data[2];
  *value = *value << 8 | data[3];
}

void Unpack_uint64_t(ODK_Message* message, uint64_t* value) {
  uint32_t hi = 0;
  uint32_t lo = 0;
  Unpack_uint32_t(message, &hi);
  Unpack_uint32_t(message, &lo);
  assert(value);
  *value = hi;
  *value = *value << 32 | lo;
}

void Unpack_OEMCrypto_Substring(ODK_Message* message,
                                OEMCrypto_Substring* obj) {
  uint32_t offset = 0, length = 0;
  Unpack_uint32_t(message, &offset);
  Unpack_uint32_t(message, &length);
  ODK_Message_Impl* message_impl = GetMessageImpl(message);
  if (!message_impl) return;

  /* Each substring should be contained within the message body, which is in the
   * total message, just after the core message. The offset of a substring is
   * relative to the message body. So we need to verify:
   * 0 < offset and  offset + length < message_impl->capacity -
   * message_impl->size or offset + length + message_impl->size <
   * message_impl->capacity
   */
  size_t substring_end = 0; /* = offset + length; */
  size_t end = 0;           /* = substring_end + message_impl->size; */
  if (odk_add_overflow_ux(offset, length, &substring_end) ||
      odk_add_overflow_ux(substring_end, message_impl->size, &end) ||
      end > message_impl->capacity) {
    message_impl->status = MESSAGE_STATUS_OVERFLOW_ERROR;
    return;
  }
  assert(obj);
  obj->offset = offset;
  obj->length = length;
}

/* copy out */
void UnpackArray(ODK_Message* message, uint8_t* address, size_t size) {
  UnpackBytes(message, address, size);
}