Line data    Source code

       1              : /*
       2              :  *
       3              :  *    Copyright (c) 2021 Project CHIP Authors
       4              :  *    All rights reserved.
       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 defines functions for encoding and decoding CHIP messages.
      22              :  *      The encoded messages contain CHIP packet header, encrypted payload
      23              :  *      header, encrypted payload and message authentication code, as per
      24              :  *      CHIP specifications.
      25              :  *
      26              :  */
      27              : 
      28              : #include <lib/support/CodeUtils.h>
      29              : #include <lib/support/SafeInt.h>
      30              : #include <transport/SecureMessageCodec.h>
      31              : 
      32              : namespace chip {
      33              : 
      34              : using System::PacketBuffer;
      35              : using System::PacketBufferHandle;
      36              : 
      37              : namespace SecureMessageCodec {
      38              : 
      39         9725 : CHIP_ERROR Encrypt(const CryptoContext & context, CryptoContext::ConstNonceView nonce, PayloadHeader & payloadHeader,
      40              :                    PacketHeader & packetHeader, System::PacketBufferHandle & msgBuf)
      41              : {
      42         9725 :     VerifyOrReturnError(!msgBuf.IsNull(), CHIP_ERROR_INVALID_ARGUMENT);
      43         9725 :     VerifyOrReturnError(!msgBuf->HasChainedBuffer(), CHIP_ERROR_INVALID_MESSAGE_LENGTH);
      44              : 
      45         9725 :     ReturnErrorOnFailure(payloadHeader.EncodeBeforeData(msgBuf));
      46              : 
      47         9725 :     uint8_t * data  = msgBuf->Start();
      48         9725 :     size_t totalLen = msgBuf->TotalLength();
      49              : 
      50              :     MessageAuthenticationCode mac;
      51         9725 :     ReturnErrorOnFailure(context.Encrypt(data, totalLen, data, nonce, packetHeader, mac));
      52              : 
      53         9725 :     uint16_t taglen = 0;
      54         9725 :     ReturnErrorOnFailure(mac.Encode(packetHeader, &data[totalLen], msgBuf->AvailableDataLength(), &taglen));
      55              : 
      56         9725 :     msgBuf->SetDataLength(totalLen + taglen);
      57              : 
      58         9725 :     return CHIP_NO_ERROR;
      59              : }
      60              : 
      61         9638 : CHIP_ERROR Decrypt(const CryptoContext & context, CryptoContext::ConstNonceView nonce, PayloadHeader & payloadHeader,
      62              :                    const PacketHeader & packetHeader, System::PacketBufferHandle & msg)
      63              : {
      64         9638 :     VerifyOrReturnError(!msg.IsNull(), CHIP_ERROR_INVALID_ARGUMENT);
      65              : 
      66         9638 :     uint8_t * data = msg->Start();
      67         9638 :     size_t len     = msg->DataLength();
      68              : 
      69         9638 :     PacketBufferHandle origMsg;
      70              : #if CHIP_SYSTEM_CONFIG_USE_LWIP
      71              :     /* This is a workaround for the case where PacketBuffer payload is not
      72              :         allocated as an inline buffer to PacketBuffer structure */
      73              :     origMsg = std::move(msg);
      74              :     msg     = PacketBufferHandle::New(len);
      75              :     VerifyOrReturnError(!msg.IsNull(), CHIP_ERROR_NO_MEMORY);
      76              :     msg->SetDataLength(len);
      77              : #endif
      78              : 
      79         9638 :     uint16_t footerLen = packetHeader.MICTagLength();
      80         9638 :     VerifyOrReturnError(footerLen <= len, CHIP_ERROR_INVALID_MESSAGE_LENGTH);
      81              : 
      82         9638 :     uint16_t taglen = 0;
      83              :     MessageAuthenticationCode mac;
      84         9638 :     ReturnErrorOnFailure(mac.Decode(packetHeader, &data[len - footerLen], footerLen, &taglen));
      85         9638 :     VerifyOrReturnError(taglen == footerLen, CHIP_ERROR_INTERNAL);
      86              : 
      87         9638 :     len = len - taglen;
      88         9638 :     msg->SetDataLength(len);
      89              : 
      90         9638 :     uint8_t * plainText = msg->Start();
      91         9638 :     ReturnErrorOnFailure(context.Decrypt(data, len, plainText, nonce, packetHeader, mac));
      92              : 
      93         9635 :     ReturnErrorOnFailure(payloadHeader.DecodeAndConsume(msg));
      94         9635 :     return CHIP_NO_ERROR;
      95         9638 : }
      96              : 
      97              : } // namespace SecureMessageCodec
      98              : 
      99              : } // namespace chip