TelnetLayer.h

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#pragma once
 
#include "Layer.h"
 
 
namespace pcpp
{
 
    class TelnetLayer : public Layer
    {
    private:
        // Position iterator for next command
        size_t lastPositionOffset;
 
        // Checks if position is a data field
        bool isDataField(uint8_t* pos) const;
        // Checks if position is a command field
        bool isCommandField(uint8_t* pos) const;
        // Returns distance to next IAC
        size_t distanceToNextIAC(uint8_t* startPos, size_t maxLength);
        // Returns length of provided field
        size_t getFieldLen(uint8_t* startPos, size_t maxLength);
        // Get position of next data field
        uint8_t* getNextDataField(uint8_t* pos, size_t len);
        // Get position of next command field
        uint8_t* getNextCommandField(uint8_t* pos, size_t len);
        // Get options of provided field
        int16_t getSubCommand(uint8_t* pos, size_t len);
        // Get data of provided field
        uint8_t* getCommandData(uint8_t* pos, size_t& slen);
 
    public:
        enum class TelnetCommand : int
        {
            TelnetCommandEndOfPacket = -1,
 
            EndOfFile = 236,
            Suspend,
            Abort,
            EndOfRecordCommand,
            SubnegotiationEnd,
            NoOperation,
            DataMark,
            Break,
            InterruptProcess,
            AbortOutput,
            AreYouThere,
            EraseCharacter,
            EraseLine,
            GoAhead,
            Subnegotiation,
            WillPerform,
            WontPerform,
            DoPerform,
            DontPerform,
            InterpretAsCommand
        };
 
        enum class TelnetOption : int
        {
            TelnetOptionNoOption = -1,
 
            TransmitBinary = 0,
            Echo,
            Reconnection,
            SuppressGoAhead,
            ApproxMsgSizeNegotiation,
            Status,
            TimingMark,
            RemoteControlledTransAndEcho,
            OutputLineWidth,
            OutputPageSize,
            OutputCarriageReturnDisposition,
            OutputHorizontalTabStops,
            OutputHorizontalTabDisposition,
            OutputFormfeedDisposition,
            OutputVerticalTabStops,
            OutputVerticalTabDisposition,
            OutputLinefeedDisposition,
            ExtendedASCII,
            Logout,
            ByteMacro,
            DataEntryTerminal,
            SUPDUP,
            SUPDUPOutput,
            SendLocation,
            TerminalType,
            EndOfRecordOption,
            TACACSUserIdentification,
            OutputMarking,
            TerminalLocationNumber,
            Telnet3270Regime,
            X3Pad,
            NegotiateAboutWindowSize,
            TerminalSpeed,
            RemoteFlowControl,
            Linemode,
            XDisplayLocation,
            EnvironmentOption,
            AuthenticationOption,
            EncryptionOption,
            NewEnvironmentOption,
            TN3270E,
            XAuth,
            Charset,
            TelnetRemoteSerialPort,
            ComPortControlOption,
            TelnetSuppressLocalEcho,
            TelnetStartTLS,
            Kermit,
            SendURL,
            ForwardX,
 
            TelOptPragmaLogon = 138,
            TelOptSSPILogon,
            TelOptPragmaHeartbeat,
 
            ExtendedOptions = 255
        };
 
        TelnetLayer(uint8_t* data, size_t dataLen, Layer* prevLayer, Packet* packet)
            : Layer(data, dataLen, prevLayer, packet, Telnet)
        {
            lastPositionOffset = SIZE_MAX;
        };
 
        std::string getDataAsString(bool removeEscapeCharacters = true);
 
        size_t getTotalNumberOfCommands();
 
        size_t getNumberOfCommands(TelnetCommand command);
 
        TelnetCommand getFirstCommand();
 
        TelnetCommand getNextCommand();
 
        TelnetOption getOption();
 
        TelnetOption getOption(TelnetCommand command);
 
        uint8_t* getOptionData(size_t& length);
 
        uint8_t* getOptionData(TelnetCommand command, size_t& length);
 
        static std::string getTelnetCommandAsString(TelnetCommand val);
 
        static std::string getTelnetOptionAsString(TelnetOption val);
 
        static bool isTelnetPort(uint16_t port)
        {
            return port == 23;
        }
 
        static bool isDataValid(const uint8_t* data, size_t dataSize)
        {
            return data && dataSize;
        }
 
        // overridden methods
 
        void parseNextLayer() override
        {}
 
        size_t getHeaderLen() const override
        {
            return m_DataLen;
        }
 
        void computeCalculateFields() override
        {}
 
        OsiModelLayer getOsiModelLayer() const override
        {
            return OsiModelApplicationLayer;
        }
 
        std::string toString() const override;
    };
 
}  // namespace pcpp