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 Master */
/* License Agreement. */

#include "serialization_base.h"

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

#include "OEMCryptoCENCCommon.h"
#include "odk_assert.h"
#include "odk_overflow.h"

struct _Message {
  uint8_t* base;
  size_t capacity;
  size_t size;        /* bytes written */
  size_t read_offset; /* bytes read */
  MessageStatus status;
};

odk_static_assert(SIZE_OF_MESSAGE_STRUCT >= sizeof(Message),
                  "SIZE_OF_MESSAGE_STRUCT too small");

bool ValidMessage(Message* message) {
  if (message == NULL) {
    return false;
  }
  if (message->status != MESSAGE_STATUS_OK) {
    return false;
  }
  if (message->base == NULL) {
    message->status = MESSAGE_STATUS_NULL_POINTER_ERROR;
    return false;
  }
  if (message->size > message->capacity ||
      message->read_offset > message->size) {
    message->status = MESSAGE_STATUS_OVERFLOW_ERROR;
    return false;
  }
  return true;
}

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

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

void Pack_bool(Message* message, const bool* value) {
  if (!ValidMessage(message)) return;
  uint8_t data[4] = {0};
  data[3] = *value ? 1 : 0;
  PackBytes(message, data, sizeof(data));
}

void Pack_uint16_t(Message* message, const uint16_t* value) {
  if (!ValidMessage(message)) return;
  uint8_t data[2] = {0};
  data[0] = *value >> 8;
  data[1] = *value >> 0;
  PackBytes(message, data, sizeof(data));
}

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

void Pack_uint64_t(Message* message, const uint64_t* value) {
  if (!ValidMessage(message)) return;
  uint32_t hi = *value >> 32;
  uint32_t lo = *value;
  Pack_uint32_t(message, &hi);
  Pack_uint32_t(message, &lo);
}

void PackArray(Message* message, const uint8_t* base, size_t size) {
  if (!ValidMessage(message)) return;
  PackBytes(message, base, size);
}

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

static void UnpackBytes(Message* message, uint8_t* ptr, size_t count) {
  if (count <= message->size - message->read_offset) {
    memcpy((void*)ptr, (void*)(message->base + message->read_offset), count);
    message->read_offset += count;
  } else {
    message->status = MESSAGE_STATUS_UNDERFLOW_ERROR;
  }
}

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

void Unpack_bool(Message* message, bool* value) {
  if (!ValidMessage(message)) return;
  uint8_t data[4] = {0};
  UnpackBytes(message, data, sizeof(data));
  *value = (0 != data[3]);
}

void Unpack_uint16_t(Message* message, uint16_t* value) {
  if (!ValidMessage(message)) return;
  uint8_t data[2] = {0};
  UnpackBytes(message, data, sizeof(data));
  *value = data[0];
  *value = *value << 8 | data[1];
}

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

void Unpack_uint64_t(Message* message, uint64_t* value) {
  if (!ValidMessage(message)) return;
  uint32_t hi = 0;
  uint32_t lo = 0;
  Unpack_uint32_t(message, &hi);
  Unpack_uint32_t(message, &lo);
  *value = hi;
  *value = *value << 32 | lo;
}

void Unpack_OEMCrypto_Substring(Message* msg, OEMCrypto_Substring* obj) {
  uint32_t offset = 0, length = 0;
  Unpack_uint32_t(msg, &offset);
  Unpack_uint32_t(msg, &length);
  if (!ValidMessage(msg)) 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->capacity - message->size
   * or offset + length + message->size < message->capacity
   */
  size_t substring_end = 0; /* = offset + length; */
  size_t end = 0;           /* = substring_end + message->size; */
  if (odk_add_overflow_ux(offset, length, &substring_end) ||
      odk_add_overflow_ux(substring_end, msg->size, &end) ||
      end > msg->capacity) {
    msg->status = MESSAGE_STATUS_OVERFLOW_ERROR;
    return;
  }
  obj->offset = offset;
  obj->length = length;
}

/* copy out */
void UnpackArray(Message* message, uint8_t* address, size_t size) {
  if (!ValidMessage(message)) return;
  UnpackBytes(message, address, size);
}

/*
 * The message structure, which is separate from the buffer,
 * is initialized to reference the buffer
 */
void InitMessage(Message* message, uint8_t* buffer, size_t capacity) {
  if (message == NULL) return;
  memset(message, 0, sizeof(Message));
  message->base = buffer;
  message->capacity = capacity;
  message->size = 0;
  message->read_offset = 0;
  message->status = MESSAGE_STATUS_OK;
}

/*
 * The message structure is in the first sizeof(Memory) bytes
 * of the buffer
 */
Message* CreateMessage(uint8_t* buffer, size_t buffer_size) {
  if (buffer == NULL || buffer_size < sizeof(Message)) return NULL;
  Message* message = (Message*)buffer;
  message->base = buffer + sizeof(Message);
  message->capacity = buffer_size - sizeof(Message);
  message->size = 0;
  message->read_offset = 0;
  message->status = MESSAGE_STATUS_OK;
  return message;
}

/*
 * Set the message to an empty state
 */
void ResetMessage(Message* message) {
  message->size = 0;
  message->read_offset = 0;
  message->status = MESSAGE_STATUS_OK;
}

uint8_t* GetBase(Message* message) {
  if (message == NULL) return NULL;
  return message->base;
}

size_t GetCapacity(Message* message) {
  if (message == NULL) return 0;
  return message->capacity;
}

size_t GetSize(Message* message) {
  if (message == NULL) return 0;
  return message->size;
}

void SetSize(Message* message, size_t size) {
  if (message == NULL) return;
  if (size > message->capacity) message->status = MESSAGE_STATUS_OVERFLOW_ERROR;
  else
    message->size = size;
}

MessageStatus GetStatus(Message* message) { return message->status; }

void SetStatus(Message* message, MessageStatus status) {
  message->status = status;
}

size_t GetOffset(Message* message) {
  if (message == NULL) return 0;
  return message->read_offset;
}

size_t SizeOfMessageStruct() { return sizeof(Message); }