/src/PcapPlusPlus/Packet++/src/TextBasedProtocol.cpp

Source
#include "TextBasedProtocol.h"
#include "Logger.h"
#include "PayloadLayer.h"
#include <cstring>
#include <algorithm>
#include <utility>

namespace pcpp
{

  // this implementation of strnlen is required since mingw doesn't have strnlen
  size_t tbp_my_own_strnlen(const char* s, size_t maxlen)
  {
    if (s == nullptr || maxlen == 0)
      return 0;

    size_t i = 0;
    for (; (i < maxlen) && s[i]; ++i)
      ;
    return i;
  }

  // -------- Class TextBasedProtocolMessage -----------------

  TextBasedProtocolMessage::TextBasedProtocolMessage(uint8_t* data, size_t dataLen, Layer* prevLayer, Packet* packet,
                                                     ProtocolType protocol)
      : Layer(data, dataLen, prevLayer, packet, protocol), m_FieldList(nullptr), m_LastField(nullptr),
        m_FieldsOffset(0)
  {}

  TextBasedProtocolMessage::TextBasedProtocolMessage(const TextBasedProtocolMessage& other) : Layer(other)
  {
    copyDataFrom(other);
  }

  TextBasedProtocolMessage& TextBasedProtocolMessage::operator=(const TextBasedProtocolMessage& other)
  {
    Layer::operator=(other);
    HeaderField* curField = m_FieldList;
    while (curField != nullptr)
    {
      HeaderField* temp = curField;
      curField = curField->getNextField();
      delete temp;
    }

    copyDataFrom(other);

    return *this;
  }

  void TextBasedProtocolMessage::copyDataFrom(const TextBasedProtocolMessage& other)
  {
    // copy field list
    if (other.m_FieldList != nullptr)
    {
      m_FieldList = new HeaderField(*(other.m_FieldList));
      HeaderField* curField = m_FieldList;
      curField->attachToTextBasedProtocolMessage(this, other.m_FieldList->m_NameOffsetInMessage);
      HeaderField* curOtherField = other.m_FieldList;
      while (curOtherField->getNextField() != nullptr)
      {
        HeaderField* newField = new HeaderField(*(curOtherField->getNextField()));
        newField->attachToTextBasedProtocolMessage(this, curOtherField->getNextField()->m_NameOffsetInMessage);
        curField->setNextField(newField);
        curField = curField->getNextField();
        curOtherField = curOtherField->getNextField();
      }

      m_LastField = curField;
    }
    else
    {
      m_FieldList = nullptr;
      m_LastField = nullptr;
    }

    m_FieldsOffset = other.m_FieldsOffset;

    // copy map
    for (HeaderField* field = m_FieldList; field != nullptr; field = field->getNextField())
    {
      m_FieldNameToFieldMap.insert(std::pair<std::string, HeaderField*>(field->getFieldName(), field));
    }
  }

  void TextBasedProtocolMessage::parseFields()
  {
    char nameValueSeparator = getHeaderFieldNameValueSeparator();
    bool spacesAllowedBetweenNameAndValue = spacesAllowedBetweenHeaderFieldNameAndValue();

    HeaderField* firstField =
        new HeaderField(this, m_FieldsOffset, nameValueSeparator, spacesAllowedBetweenNameAndValue);
    PCPP_LOG_DEBUG("Added new field: name='" << firstField->getFieldName()
                                             << "'; offset in packet=" << firstField->m_NameOffsetInMessage
                                             << "; length=" << firstField->getFieldSize());
    PCPP_LOG_DEBUG("     Field value = " << firstField->getFieldValue());

    if (m_FieldList == nullptr)
      m_FieldList = firstField;
    else
      m_FieldList->setNextField(firstField);

    std::string fieldName = firstField->getFieldName();
    std::transform(fieldName.begin(), fieldName.end(), fieldName.begin(), ::tolower);
    m_FieldNameToFieldMap.insert(std::pair<std::string, HeaderField*>(fieldName, firstField));

    // Last field will be empty and contain just "\n" or "\r\n". This field will mark the end of the header
    HeaderField* curField = m_FieldList;
    int curOffset = m_FieldsOffset;
    // last field can be one of:
    // a.) \r\n\r\n or \n\n marking the end of the header
    // b.) the end of the packet
    while (!curField->isEndOfHeader() && curOffset + curField->getFieldSize() < m_DataLen)
    {
      curOffset += curField->getFieldSize();
      HeaderField* newField =
          new HeaderField(this, curOffset, nameValueSeparator, spacesAllowedBetweenNameAndValue);
      if (newField->getFieldSize() > 0)
      {
        PCPP_LOG_DEBUG("Added new field: name='" << newField->getFieldName()
                                                 << "'; offset in packet=" << newField->m_NameOffsetInMessage
                                                 << "; length=" << newField->getFieldSize());
        PCPP_LOG_DEBUG("     Field value = " << newField->getFieldValue());
        curField->setNextField(newField);
        curField = newField;
        fieldName = newField->getFieldName();
        std::transform(fieldName.begin(), fieldName.end(), fieldName.begin(), ::tolower);
        m_FieldNameToFieldMap.insert(std::pair<std::string, HeaderField*>(fieldName, newField));
      }
      else
      {
        delete newField;
        break;
      }
    }

    m_LastField = curField;
  }

  TextBasedProtocolMessage::~TextBasedProtocolMessage()
  {
    while (m_FieldList != nullptr)
    {
      HeaderField* temp = m_FieldList;
      m_FieldList = m_FieldList->getNextField();
      delete temp;
    }
  }

  HeaderField* TextBasedProtocolMessage::addField(const std::string& fieldName, const std::string& fieldValue)
  {
    HeaderField newField(fieldName, fieldValue, getHeaderFieldNameValueSeparator(),
                         spacesAllowedBetweenHeaderFieldNameAndValue());
    return addField(newField);
  }

  HeaderField* TextBasedProtocolMessage::addField(const HeaderField& newField)
  {
    return insertField(m_LastField, newField);
  }

  HeaderField* TextBasedProtocolMessage::addEndOfHeader()
  {
    HeaderField endOfHeaderField(PCPP_END_OF_TEXT_BASED_PROTOCOL_HEADER, "", '\0', false);
    return insertField(m_LastField, endOfHeaderField);
  }

  HeaderField* TextBasedProtocolMessage::insertField(HeaderField* prevField, const std::string& fieldName,
                                                     const std::string& fieldValue)
  {
    HeaderField newField(fieldName, fieldValue, getHeaderFieldNameValueSeparator(),
                         spacesAllowedBetweenHeaderFieldNameAndValue());
    return insertField(prevField, newField);
  }

  HeaderField* TextBasedProtocolMessage::insertField(std::string prevFieldName, const std::string& fieldName,
                                                     const std::string& fieldValue)
  {
    if (prevFieldName == "")
    {
      return insertField(nullptr, fieldName, fieldValue);
    }
    else
    {
      HeaderField* prevField = getFieldByName(prevFieldName);
      if (prevField == nullptr)
        return nullptr;

      return insertField(prevField, fieldName, fieldValue);
    }
  }

  HeaderField* TextBasedProtocolMessage::insertField(HeaderField* prevField, const HeaderField& newField)
  {
    if (newField.m_TextBasedProtocolMessage != nullptr)
    {
      PCPP_LOG_ERROR("This field is already associated with another message");
      return nullptr;
    }

    if (prevField != nullptr && prevField->getFieldName() == PCPP_END_OF_TEXT_BASED_PROTOCOL_HEADER)
    {
      PCPP_LOG_ERROR("Cannot add a field after end of header");
      return nullptr;
    }

    HeaderField* newFieldToAdd = new HeaderField(newField);

    int newFieldOffset = m_FieldsOffset;
    if (prevField != nullptr)
      newFieldOffset = prevField->m_NameOffsetInMessage + prevField->getFieldSize();

    // extend layer to make room for the new field. Field will be added just before the last field
    if (!extendLayer(newFieldOffset, newFieldToAdd->getFieldSize()))
    {
      PCPP_LOG_ERROR("Cannot extend layer to insert the header");
      delete newFieldToAdd;
      return nullptr;
    }

    HeaderField* curField = m_FieldList;
    if (prevField != nullptr)
      curField = prevField->getNextField();

    // go over all fields after prevField and update their offsets
    shiftFieldsOffset(curField, newFieldToAdd->getFieldSize());

    // copy new field data to message
    memcpy(m_Data + newFieldOffset, newFieldToAdd->m_NewFieldData, newFieldToAdd->getFieldSize());

    // attach new field to message
    newFieldToAdd->attachToTextBasedProtocolMessage(this, newFieldOffset);

    // insert field into fields link list
    if (prevField == nullptr)
    {
      newFieldToAdd->setNextField(m_FieldList);
      m_FieldList = newFieldToAdd;
    }
    else
    {
      newFieldToAdd->setNextField(prevField->getNextField());
      prevField->setNextField(newFieldToAdd);
    }

    // if newField is the last field, update m_LastField
    if (newFieldToAdd->getNextField() == nullptr)
      m_LastField = newFieldToAdd;

    // insert the new field into name to field map
    std::string fieldName = newFieldToAdd->getFieldName();
    std::transform(fieldName.begin(), fieldName.end(), fieldName.begin(), ::tolower);
    m_FieldNameToFieldMap.insert(std::pair<std::string, HeaderField*>(fieldName, newFieldToAdd));

    return newFieldToAdd;
  }

  bool TextBasedProtocolMessage::removeField(std::string fieldName, int index)
  {
    std::transform(fieldName.begin(), fieldName.end(), fieldName.begin(), ::tolower);

    HeaderField* fieldToRemove = nullptr;

    auto range = m_FieldNameToFieldMap.equal_range(fieldName);
    int i = 0;
    for (std::multimap<std::string, HeaderField*>::iterator iter = range.first; iter != range.second; ++iter)
    {
      if (i == index)
      {
        fieldToRemove = iter->second;
        break;
      }

      i++;
    }

    if (fieldToRemove != nullptr)
      return removeField(fieldToRemove);
    else
    {
      PCPP_LOG_ERROR("Cannot find field '" << fieldName << "'");
      return false;
    }
  }

  bool TextBasedProtocolMessage::removeField(HeaderField* fieldToRemove)
  {
    if (fieldToRemove == nullptr)
      return true;

    if (fieldToRemove->m_TextBasedProtocolMessage != this)
    {
      PCPP_LOG_ERROR("Field isn't associated with this message");
      return false;
    }

    std::string fieldName = fieldToRemove->getFieldName();

    // shorten layer and delete this field
    if (!shortenLayer(fieldToRemove->m_NameOffsetInMessage, fieldToRemove->getFieldSize()))
    {
      PCPP_LOG_ERROR("Cannot shorten layer");
      return false;
    }

    // update offsets of all fields after this field
    HeaderField* curField = fieldToRemove->getNextField();
    shiftFieldsOffset(curField, 0 - fieldToRemove->getFieldSize());

    // update fields link list
    if (fieldToRemove == m_FieldList)
      m_FieldList = m_FieldList->getNextField();
    else
    {
      curField = m_FieldList;
      while (curField->getNextField() != fieldToRemove)
        curField = curField->getNextField();

      curField->setNextField(fieldToRemove->getNextField());
    }

    // re-calculate m_LastField if needed
    if (fieldToRemove == m_LastField)
    {
      if (m_FieldList == nullptr)
        m_LastField = nullptr;
      else
      {
        curField = m_FieldList;
        while (curField->getNextField() != nullptr)
          curField = curField->getNextField();
        m_LastField = curField;
      }
    }

    // remove the hash entry for this field
    std::transform(fieldName.begin(), fieldName.end(), fieldName.begin(), ::tolower);
    auto range = m_FieldNameToFieldMap.equal_range(fieldName);
    for (std::multimap<std::string, HeaderField*>::iterator iter = range.first; iter != range.second; ++iter)
    {
      if (iter->second == fieldToRemove)
      {
        m_FieldNameToFieldMap.erase(iter);
        break;
      }
    }

    // finally - delete this field
    delete fieldToRemove;

    return true;
  }

  bool TextBasedProtocolMessage::isHeaderComplete() const
  {
    if (m_LastField == nullptr)
      return false;

    return (m_LastField->getFieldName() == PCPP_END_OF_TEXT_BASED_PROTOCOL_HEADER);
  }

  void TextBasedProtocolMessage::shiftFieldsOffset(HeaderField* fromField, int numOfBytesToShift)
  {
    while (fromField != nullptr)
    {
      fromField->m_NameOffsetInMessage += numOfBytesToShift;
      if (fromField->m_ValueOffsetInMessage != -1)
        fromField->m_ValueOffsetInMessage += numOfBytesToShift;
      fromField = fromField->getNextField();
    }
  }

  HeaderField* TextBasedProtocolMessage::getFieldByName(std::string fieldName, int index) const
  {
    std::transform(fieldName.begin(), fieldName.end(), fieldName.begin(), ::tolower);

    auto range = m_FieldNameToFieldMap.equal_range(fieldName);
    int i = 0;
    for (std::multimap<std::string, HeaderField*>::const_iterator iter = range.first; iter != range.second; ++iter)
    {
      if (i == index)
        return iter->second;

      i++;
    }

    return nullptr;
  }

  int TextBasedProtocolMessage::getFieldCount() const
  {
    int result = 0;

    HeaderField* curField = getFirstField();
    while (curField != nullptr)
    {
      if (!curField->isEndOfHeader())
        result++;
      curField = curField->getNextField();
    }

    return result;
  }

  void TextBasedProtocolMessage::parseNextLayer()
  {
    size_t headerLen = getHeaderLen();
    if (m_DataLen <= headerLen)
      return;

    constructNextLayer<PayloadLayer>(m_Data + headerLen, m_DataLen - headerLen);
  }

  size_t TextBasedProtocolMessage::getHeaderLen() const
  {
    return m_LastField->m_NameOffsetInMessage + m_LastField->m_FieldSize;
  }

  void TextBasedProtocolMessage::computeCalculateFields()
  {
    // nothing to do for now
  }

  // -------- Class HeaderField -----------------

  HeaderField::HeaderField(TextBasedProtocolMessage* TextBasedProtocolMessage, int offsetInMessage,
                           char nameValueSeparator, bool spacesAllowedBetweenNameAndValue)
      : m_NewFieldData(nullptr), m_TextBasedProtocolMessage(TextBasedProtocolMessage),
        m_NameOffsetInMessage(offsetInMessage), m_NextField(nullptr), m_NameValueSeparator(nameValueSeparator),
        m_SpacesAllowedBetweenNameAndValue(spacesAllowedBetweenNameAndValue)
  {
    char* fieldData = reinterpret_cast<char*>(m_TextBasedProtocolMessage->m_Data + m_NameOffsetInMessage);
    char* fieldEndPtr = static_cast<char*>(memchr(
        fieldData, '\n', m_TextBasedProtocolMessage->m_DataLen - static_cast<size_t>(m_NameOffsetInMessage)));
    if (fieldEndPtr == nullptr)
      m_FieldSize = tbp_my_own_strnlen(fieldData, m_TextBasedProtocolMessage->m_DataLen -
                                                      static_cast<size_t>(m_NameOffsetInMessage));
    else
      m_FieldSize = fieldEndPtr - fieldData + 1;

    if (m_FieldSize == 0 || (*fieldData) == '\r' || (*fieldData) == '\n')
    {
      m_FieldNameSize = -1;
      m_ValueOffsetInMessage = -1;
      m_FieldValueSize = -1;
      m_FieldNameSize = -1;
      m_IsEndOfHeaderField = true;
      return;
    }
    else
      m_IsEndOfHeaderField = false;

    char* fieldValuePtr = static_cast<char*>(
        memchr(fieldData, nameValueSeparator,
               m_TextBasedProtocolMessage->m_DataLen - static_cast<size_t>(m_NameOffsetInMessage)));
    // could not find the position of the separator, meaning field value position is unknown
    if (fieldValuePtr == nullptr || (fieldEndPtr != nullptr && fieldValuePtr >= fieldEndPtr))
    {
      m_ValueOffsetInMessage = -1;
      m_FieldValueSize = -1;
      m_FieldNameSize = m_FieldSize;
    }
    else
    {
      m_FieldNameSize = fieldValuePtr - fieldData;
      // Header field looks like this: <field_name>[separator]<zero or more spaces><field_Value>
      // So fieldValuePtr give us the position of the separator. Value offset is the first non-space byte forward
      fieldValuePtr++;

      // reached the end of the packet and value start offset wasn't found
      if (static_cast<size_t>(fieldValuePtr - reinterpret_cast<char*>(m_TextBasedProtocolMessage->m_Data)) >=
          m_TextBasedProtocolMessage->getDataLen())
      {
        m_ValueOffsetInMessage = -1;
        m_FieldValueSize = -1;
        return;
      }

      if (spacesAllowedBetweenNameAndValue)
      {
        // advance fieldValuePtr 1 byte forward while didn't get to end of packet and fieldValuePtr points to a
        // space char
        while (
            static_cast<size_t>(fieldValuePtr - reinterpret_cast<char*>(m_TextBasedProtocolMessage->m_Data)) <
                m_TextBasedProtocolMessage->getDataLen() &&
            (*fieldValuePtr) == ' ')
        {
          fieldValuePtr++;
        }
      }

      // reached the end of the packet and value start offset wasn't found
      if (static_cast<size_t>(fieldValuePtr - reinterpret_cast<char*>(m_TextBasedProtocolMessage->m_Data)) >=
          m_TextBasedProtocolMessage->getDataLen())
      {
        m_ValueOffsetInMessage = -1;
        m_FieldValueSize = -1;
      }
      else
      {
        m_ValueOffsetInMessage = fieldValuePtr - reinterpret_cast<char*>(m_TextBasedProtocolMessage->m_Data);
        // couldn't find the end of the field, so assuming the field value length is from m_ValueOffsetInMessage
        // until the end of the packet
        if (fieldEndPtr == nullptr)
        {
          // clang-format off
          m_FieldValueSize = reinterpret_cast<char*>(m_TextBasedProtocolMessage->m_Data + m_TextBasedProtocolMessage->getDataLen()) - fieldValuePtr;
          // clang-format on
        }
        else
        {
          m_FieldValueSize = fieldEndPtr - fieldValuePtr;
          // if field ends with \r\n, decrease the value length by 1
          if ((*(--fieldEndPtr)) == '\r')
            m_FieldValueSize--;
        }
      }
    }
  }

  HeaderField::HeaderField(const std::string& name, const std::string& value, char nameValueSeparator,
                           bool spacesAllowedBetweenNameAndValue)
  {
    m_NameValueSeparator = nameValueSeparator;
    m_SpacesAllowedBetweenNameAndValue = spacesAllowedBetweenNameAndValue;
    initNewField(name, value);
  }

  void HeaderField::initNewField(const std::string& name, const std::string& value)
  {
    m_TextBasedProtocolMessage = nullptr;
    m_NameOffsetInMessage = 0;
    m_NextField = nullptr;

    // first building the name-value separator
    std::string nameValueSeparation(1, m_NameValueSeparator);
    if (m_SpacesAllowedBetweenNameAndValue)
      nameValueSeparation += " ";

    // Field size is: name_length + separator_len + value_length + '\r\n'
    if (name != PCPP_END_OF_TEXT_BASED_PROTOCOL_HEADER)
      m_FieldSize = name.length() + nameValueSeparation.length() + value.length() + 2;
    else
      // Field is \r\n (2B)
      m_FieldSize = 2;

    m_NewFieldData = new uint8_t[m_FieldSize];
    std::string fieldData;

    if (name != PCPP_END_OF_TEXT_BASED_PROTOCOL_HEADER)
      fieldData = name + nameValueSeparation + value + "\r\n";
    else
      fieldData = "\r\n";

    // copy field data to m_NewFieldData
    memcpy(m_NewFieldData, fieldData.c_str(), m_FieldSize);

    // calculate value offset
    if (name != PCPP_END_OF_TEXT_BASED_PROTOCOL_HEADER)
      m_ValueOffsetInMessage = name.length() + nameValueSeparation.length();
    else
      m_ValueOffsetInMessage = 0;
    m_FieldNameSize = name.length();
    m_FieldValueSize = value.length();

    if (name != PCPP_END_OF_TEXT_BASED_PROTOCOL_HEADER)
      m_IsEndOfHeaderField = false;
    else
      m_IsEndOfHeaderField = true;
  }

  HeaderField::~HeaderField()
  {
    if (m_NewFieldData != nullptr)
      delete[] m_NewFieldData;
  }

  HeaderField::HeaderField(const HeaderField& other)
      : m_NameValueSeparator('\0'), m_SpacesAllowedBetweenNameAndValue(false)
  {
    m_NameValueSeparator = other.m_NameValueSeparator;
    m_SpacesAllowedBetweenNameAndValue = other.m_SpacesAllowedBetweenNameAndValue;
    initNewField(other.getFieldName(), other.getFieldValue());
  }

  HeaderField& HeaderField::operator=(const HeaderField& other)
  {
    m_NameValueSeparator = other.m_NameValueSeparator;
    m_SpacesAllowedBetweenNameAndValue = other.m_SpacesAllowedBetweenNameAndValue;
    if (m_NewFieldData != nullptr)
      delete[] m_NewFieldData;
    initNewField(other.getFieldName(), other.getFieldValue());

    return (*this);
  }

  char* HeaderField::getData() const
  {
    if (m_TextBasedProtocolMessage == nullptr)
      return reinterpret_cast<char*>(m_NewFieldData);
    else
      return reinterpret_cast<char*>(m_TextBasedProtocolMessage->m_Data);
  }

  void HeaderField::setNextField(HeaderField* nextField)
  {
    m_NextField = nextField;
  }

  HeaderField* HeaderField::getNextField() const
  {
    return m_NextField;
  }

  std::string HeaderField::getFieldName() const
  {
    std::string result;

    if (m_FieldNameSize != static_cast<size_t>(-1))
      result.assign((getData() + m_NameOffsetInMessage), m_FieldNameSize);

    return result;
  }

  std::string HeaderField::getFieldValue() const
  {
    std::string result;
    if (m_ValueOffsetInMessage != -1)
      result.assign((getData() + m_ValueOffsetInMessage), m_FieldValueSize);
    return result;
  }

  bool HeaderField::setFieldValue(const std::string& newValue)
  {
    // Field isn't linked with any message yet
    if (m_TextBasedProtocolMessage == nullptr)
    {
      std::string name = getFieldName();
      delete[] m_NewFieldData;
      initNewField(name, newValue);
      return true;
    }

    std::string curValue = getFieldValue();
    int lengthDifference = newValue.length() - curValue.length();
    // new value is longer than current value
    if (lengthDifference > 0)
    {
      if (!m_TextBasedProtocolMessage->extendLayer(m_ValueOffsetInMessage, lengthDifference))
      {
        PCPP_LOG_ERROR("Could not extend layer");
        return false;
      }
    }
    // new value is shorter than current value
    else if (lengthDifference < 0)
    {
      if (!m_TextBasedProtocolMessage->shortenLayer(m_ValueOffsetInMessage, 0 - lengthDifference))
      {
        PCPP_LOG_ERROR("Could not shorten layer");
        return false;
      }
    }

    if (lengthDifference != 0)
      m_TextBasedProtocolMessage->shiftFieldsOffset(getNextField(), lengthDifference);

    // update sizes
    m_FieldValueSize += lengthDifference;
    m_FieldSize += lengthDifference;

    // write new value to field data
    memcpy(getData() + m_ValueOffsetInMessage, newValue.c_str(), newValue.length());

    return true;
  }

  void HeaderField::attachToTextBasedProtocolMessage(TextBasedProtocolMessage* message, int fieldOffsetInMessage)
  {
    if (m_TextBasedProtocolMessage != nullptr && m_TextBasedProtocolMessage != message)
    {
      PCPP_LOG_ERROR("Header field already associated with another message");
      return;
    }

    if (m_NewFieldData == nullptr)
    {
      PCPP_LOG_ERROR("Header field doesn't have new field data");
      return;
    }

    delete[] m_NewFieldData;
    m_NewFieldData = nullptr;
    m_TextBasedProtocolMessage = message;

    int valueAndNameDifference = m_ValueOffsetInMessage - m_NameOffsetInMessage;
    m_NameOffsetInMessage = fieldOffsetInMessage;
    m_ValueOffsetInMessage = m_NameOffsetInMessage + valueAndNameDifference;
  }

}  // namespace pcpp

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Created: 2026-03-07 06:49