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      316975 : constexpr inline uint8_t operator|(TLVTagControl lhs, TLVElementType rhs)
      71             : {
      72      316975 :     return static_cast<uint8_t>(lhs) | static_cast<uint8_t>(rhs);
      73             : }
      74             : 
      75             : enum
      76             : {
      77             :     kTLVControlByte_NotSpecified = 0xFFFF
      78             : };
      79             : 
      80         283 : constexpr size_t EstimateStructOverhead()
      81             : {
      82             :     // The struct itself has a control byte and an end-of-struct marker.
      83         283 :     return 2;
      84             : }
      85             : 
      86             : template <typename... FieldSizes>
      87         962 : 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         962 :     return firstFieldSize + 4u + EstimateStructOverhead(otherFields...);
      93             : }
      94             : 
      95             : } // namespace TLV
      96             : } // namespace chip