Line data    Source code

       1              : /*
       2              :  *
       3              :  *    Copyright (c) 2020-2023 Project CHIP Authors
       4              :  *    Copyright (c) 2013-2017 Nest Labs, Inc.
       5              :  *
       6              :  *    Licensed under the Apache License, Version 2.0 (the "License");
       7              :  *    you may not use this file except in compliance with the License.
       8              :  *    You may obtain a copy of the License at
       9              :  *
      10              :  *        http://www.apache.org/licenses/LICENSE-2.0
      11              :  *
      12              :  *    Unless required by applicable law or agreed to in writing, software
      13              :  *    distributed under the License is distributed on an "AS IS" BASIS,
      14              :  *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
      15              :  *    See the License for the specific language governing permissions and
      16              :  *    limitations under the License.
      17              :  */
      18              : 
      19              : /**
      20              :  *    @file
      21              :  *      This file contains common headers and definitions for working with data encoded in CHIP TLV format.
      22              :  *
      23              :  *      CHIP TLV (Tag-Length-Value) is a generalized encoding method for simple structured data. It
      24              :  *      shares many properties with the commonly used JSON serialization format while being considerably
      25              :  *      more compact over the wire.
      26              :  */
      27              : 
      28              : #pragma once
      29              : 
      30              : #include <lib/core/CHIPError.h>
      31              : #include <lib/core/TLVTags.h>
      32              : #include <lib/core/TLVTypes.h>
      33              : 
      34              : #include <lib/support/BitFlags.h>
      35              : #include <lib/support/BitMask.h>
      36              : #include <lib/support/DLLUtil.h>
      37              : #include <lib/support/EnforceFormat.h>
      38              : #include <lib/support/ScopedBuffer.h>
      39              : #include <lib/support/Span.h>
      40              : #include <lib/support/TypeTraits.h>
      41              : #include <lib/support/logging/Constants.h>
      42              : 
      43              : #include <stdarg.h>
      44              : #include <stdlib.h>
      45              : #include <type_traits>
      46              : 
      47              : /**
      48              :  * @namespace chip::TLV
      49              :  *
      50              :  * Definitions for working with data encoded in CHIP TLV format.
      51              :  *
      52              :  * CHIP TLV is a generalized encoding method for simple structured data. It shares many properties
      53              :  * with the commonly used JSON serialization format while being considerably more compact over the wire.
      54              :  */
      55              : 
      56              : namespace chip {
      57              : namespace TLV {
      58              : 
      59              : /* Forward declarations */
      60              : class TLVReader;
      61              : class TLVWriter;
      62              : class TLVUpdater;
      63              : class TLVBackingStore;
      64              : 
      65              : constexpr inline uint8_t operator|(TLVElementType lhs, TLVTagControl rhs)
      66              : {
      67              :     return static_cast<uint8_t>(lhs) | static_cast<uint8_t>(rhs);
      68              : }
      69              : 
      70       367365 : constexpr inline uint8_t operator|(TLVTagControl lhs, TLVElementType rhs)
      71              : {
      72       367365 :     return static_cast<uint8_t>(lhs) | static_cast<uint8_t>(rhs);
      73              : }
      74              : 
      75              : enum
      76              : {
      77              :     kTLVControlByte_NotSpecified = 0xFFFF
      78              : };
      79              : 
      80         1851 : constexpr size_t EstimateStructOverhead()
      81              : {
      82              :     // The struct itself has a control byte and an end-of-struct marker.
      83         1851 :     return 2;
      84              : }
      85              : 
      86              : template <typename... FieldSizes>
      87         6058 : constexpr size_t EstimateStructOverhead(size_t firstFieldSize, FieldSizes... otherFields)
      88              : {
      89              :     // Estimate 4 bytes of overhead per field.  This can happen for a large
      90              :     // octet string field: 1 byte control, 1 byte context tag, 2 bytes
      91              :     // length.
      92         6058 :     return firstFieldSize + 4u + EstimateStructOverhead(otherFields...);
      93              : }
      94              : 
      95              : } // namespace TLV
      96              : } // namespace chip