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Add ModbusRequest.toRawCRC() function #17

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e9a85b0
Add ModbusRequest.toRawCRC() function
Dec 23, 2024
121ef91
bug: Modbus Response cannot handle parsing exception response
Jan 9, 2025
1ec6057
bug: No range checking for inputData.
Jan 10, 2025
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4 changes: 4 additions & 0 deletions include/MB/modbusRequest.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -95,6 +95,10 @@ class ModbusRequest {
//! communication
[[nodiscard]] std::vector<uint8_t> toRaw() const;

//! Returns raw bytes representation of object, ready for modbus
//! communication
[[nodiscard]] std::vector<uint8_t> toRawCRC() const;

//! Returns function type based on Modbus function code
[[nodiscard]] utils::MBFunctionType functionType() const noexcept {
return utils::functionType(_functionCode);
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2 changes: 2 additions & 0 deletions include/MB/modbusResponse.hpp
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Expand Up @@ -27,9 +27,11 @@ class ModbusResponse {
private:
uint8_t _slaveID;
utils::MBFunctionCode _functionCode;
bool _exception;

uint16_t _address;
uint16_t _registersNumber;
uint8_t _bytes;

std::vector<ModbusCell> _values;

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4 changes: 4 additions & 0 deletions include/MB/modbusUtils.hpp
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Expand Up @@ -47,6 +47,7 @@ enum MBErrorCode : uint8_t {
// See issue: https://github.com/Mazurel/Modbus/issues/3
NumberOfRegistersInvalid = 0b01111000,
NumberOfValuesInvalid = 0b01110111,
InputDataLengthInvalid = 0b01110110,
};

//! Checks if error code is modbus standard error code
Expand All @@ -71,6 +72,7 @@ inline bool isStandardErrorCode(MBErrorCode code) {
case ConnectionClosed:
case Timeout:
case NumberOfRegistersInvalid:
case InputDataLengthInvalid:
default:
return false;
}
Expand Down Expand Up @@ -117,6 +119,8 @@ inline std::string mbErrorCodeToStr(MBErrorCode code) noexcept {
return "Number of registers in response is too big - cannot be serialized";
case NumberOfValuesInvalid:
return "Number of values is not valid";
case InputDataLengthInvalid:
return "Encountered end of data during parsing";
}

return "Unknown";
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9 changes: 9 additions & 0 deletions src/modbusRequest.cpp
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Expand Up @@ -201,3 +201,12 @@ std::vector<uint8_t> ModbusRequest::toRaw() const {

return result;
}

std::vector<uint8_t> ModbusRequest::toRawCRC() const {
std::vector<uint8_t> result {toRaw()};
const auto crc = MB::utils::calculateCRC(result);
result.push_back(reinterpret_cast<const uint8_t *>(&crc)[0]);
result.push_back(reinterpret_cast<const uint8_t *>(&crc)[1]);

return result;
}
107 changes: 60 additions & 47 deletions src/modbusResponse.cpp
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Expand Up @@ -50,76 +50,89 @@ ModbusResponse &ModbusResponse::operator=(const ModbusResponse &reference) {
ModbusResponse::ModbusResponse(std::vector<uint8_t> inputData, bool CRC) {
try {
if (inputData.size() < 3)
throw ModbusException(utils::InvalidByteOrder);
throw ModbusException(utils::InputDataLengthInvalid);

_slaveID = inputData[0];
_functionCode = static_cast<utils::MBFunctionCode>(inputData[1]);
_slaveID = inputData.at(0);
_functionCode = static_cast<utils::MBFunctionCode>(0b01111111 & inputData.at(1));
_exception = (inputData.at(1) & 0b10000000) != 0;

if (functionType() != utils::Read)
_address = utils::bigEndianConv(&inputData[2]);
_address = utils::bigEndianConv(&inputData.at(2));

int crcIndex = -1;
uint8_t bytes;

switch (_functionCode) {
case utils::ReadDiscreteOutputCoils:
case utils::ReadDiscreteInputContacts:
bytes = inputData[2];
_registersNumber = bytes * 8;
_values = std::vector<ModbusCell>(_registersNumber);
for (auto i = 0; i < _registersNumber; i++) {
_values[i].coil() = inputData[3 + (i / 8)] & (1 << (i % 8));
}
crcIndex = 2 + bytes + 1;
break;
case utils::ReadAnalogOutputHoldingRegisters:
case utils::ReadAnalogInputRegisters:
bytes = inputData[2];
_registersNumber = bytes / 2;
for (auto i = 0; i < bytes / 2; i++) {
_values.emplace_back(utils::bigEndianConv(&inputData[3 + (i * 2)]));

if(!_exception){
switch (_functionCode) {
case utils::ReadDiscreteOutputCoils:
case utils::ReadDiscreteInputContacts:
_bytes = inputData.at(2);
_registersNumber = _bytes * 8;
_values = std::vector<ModbusCell>(_registersNumber);
for (auto i = 0; i < _registersNumber; i++) {
_values[i].coil() = inputData.at(3 + (i / 8)) & (1 << (i % 8));
}
crcIndex = 2 + _bytes + 1;
break;
case utils::ReadAnalogOutputHoldingRegisters:
case utils::ReadAnalogInputRegisters:
_bytes = inputData.at(2);
_registersNumber = _bytes / 2;
for (auto i = 0; i < _bytes / 2; i++) {
_values.emplace_back(utils::bigEndianConv(&inputData.at(3 + (i * 2))));
}
crcIndex = 2 + _bytes + 1;
break;
case utils::WriteSingleDiscreteOutputCoil:
_bytes = 8;
_registersNumber = 1;
_address = utils::bigEndianConv(&inputData.at(2));
_values = {ModbusCell::initCoil(inputData.at(4) == 0xFF)};
crcIndex = 6;
break;
case utils::WriteSingleAnalogOutputRegister:
_bytes = 8;
_registersNumber = 1;
_address = utils::bigEndianConv(&inputData.at(2));
_values = {ModbusCell::initReg(utils::bigEndianConv(&inputData.at(4)))};
crcIndex = 6;
break;
case utils::WriteMultipleDiscreteOutputCoils:
case utils::WriteMultipleAnalogOutputHoldingRegisters:
_bytes = 8;
_address = utils::bigEndianConv(&inputData.at(2));
_registersNumber = utils::bigEndianConv(&inputData.at(4));
crcIndex = 6;
break;
default:
throw ModbusException(utils::InvalidByteOrder);
}
crcIndex = 2 + bytes + 1;
break;
case utils::WriteSingleDiscreteOutputCoil:
_registersNumber = 1;
_address = utils::bigEndianConv(&inputData[2]);
_values = {ModbusCell::initCoil(inputData[4] == 0xFF)};
crcIndex = 6;
break;
case utils::WriteSingleAnalogOutputRegister:
_registersNumber = 1;
_address = utils::bigEndianConv(&inputData[2]);
_values = {ModbusCell::initReg(utils::bigEndianConv(&inputData[4]))};
crcIndex = 6;
break;
case utils::WriteMultipleDiscreteOutputCoils:
case utils::WriteMultipleAnalogOutputHoldingRegisters:
_address = utils::bigEndianConv(&inputData[2]);
_registersNumber = utils::bigEndianConv(&inputData[4]);
crcIndex = 6;
break;
default:
throw ModbusException(utils::InvalidByteOrder);
}else{
crcIndex = 3;
}

_values.resize(_registersNumber);

if (CRC) {
if (crcIndex == -1 || static_cast<size_t>(crcIndex) + 2 > inputData.size())
throw ModbusException(utils::InvalidByteOrder);
throw ModbusException(utils::InputDataLengthInvalid);

const auto receivedCRC =
*reinterpret_cast<const uint16_t *>(&inputData[crcIndex]);
*reinterpret_cast<const uint16_t *>(&inputData.at(crcIndex));
const auto inputDataLen = static_cast<std::size_t>(crcIndex);
const auto calculatedCRC = MB::CRC::calculateCRC(inputData, inputDataLen);

if (receivedCRC != calculatedCRC) {
throw ModbusException(utils::InvalidCRC, _slaveID);
}
}
if(_exception){
throw ModbusException{inputData,CRC};
}

} catch (const ModbusException &ex) {
throw ex;
} catch (const std::out_of_range& inputDataInSufficient){
throw ModbusException(utils::InputDataLengthInvalid);
} catch (const std::exception &) {
// TODO: Save the exception somewhere
throw ModbusException(utils::InvalidByteOrder);
Expand Down