/src/PcapPlusPlus/Packet++/header/TelnetLayer.h

Source (jump to first uncovered line)
#ifndef PACKETPP_TELNET_LAYER
#define PACKETPP_TELNET_LAYER

#include "Layer.h"

/// @file

/**
 * \namespace pcpp
 * \brief The main namespace for the PcapPlusPlus lib
 */
namespace pcpp
{

/**
 * Class for representing the Telnet Layer
 */
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:
  /**
   * Telnet Command Indicator
   */
  enum TelnetCommand
  {
    /// Indicator to parser reached end of packet
    TelnetCommandEndOfPacket = -1,

    /// End of file
    EndOfFile = 236,
    /// Suspend current process
    Suspend,
    /// Abort Process
    Abort,
    /// End of Record
    EndOfRecordCommand,
    /// Marks the end of a Telnet option subnegotiation, used with the SB code to specify more specific option
    /// parameters.
    SubnegotiationEnd,
    /// Null command; does nothing.
    NoOperation,
    /// Used to mark the end of a sequence of data that the recipient should scan for urgent Telnet commands.
    DataMark,
    /// Represents the pressing of the “break” or “attention” key on the terminal.
    Break,
    /// Tells the recipient to interrupt, abort, suspend or terminate the process currently in use.
    InterruptProcess,
    /// Instructs the remote host to continue running the current process, but discard all remaining output from it.
    /// This may be needed if a program starts to send unexpectedly large amounts of data to the user.
    AbortOutput,
    /// May be used to check that the remote host is still “alive”. When this character is sent the remote host
    /// returns some type of output to indicate that it is still functioning.
    AreYouThere,
    /// Instructs the recipient to delete the last undeleted character from the data stream. Used to “undo” the
    /// sending of a character.
    EraseCharacter,
    /// Tells the recipient to delete all characters from the data stream back to (but not including) the last end
    /// of line (CR+LF) sequence.
    EraseLine,
    /// Used in Telnet half-duplex mode to signal the other device that it may transmit.
    GoAhead,
    /// Marks the beginning of a Telnet option subnegotiation, used when an option requires the client and server to
    /// exchange parameters.
    Subnegotiation,
    /// Indicates that the device sending this code is willing to perform or continue performing a particular
    /// option.
    WillPerform,
    /// Indicates that the device sending this code is either not willing to perform a particular option, or is now
    /// refusing to continue to perform it.
    WontPerform,
    /// Requests that the other device perform a particular option or confirms the expectation that the other device
    /// will perform that option.
    DoPerform,
    /// Specifies that the other party not perform an option, or confirms a device’s expectation that the other
    /// party not perform an option.
    DontPerform,
    /// Precedes command values 240 through 254 as described above. A pair of IAC bytes in a row represents the data
    /// value 255.
    InterpretAsCommand
  };

  /**
   * Telnet Options
   */
  enum TelnetOption
  {
    /// Internal return for no option detected
    TelnetOptionNoOption = -1,

    /// Binary Transmission RFC856 https://www.iana.org/go/rfc856
    TransmitBinary = 0,
    /// Echo RFC857 https://www.iana.org/go/rfc857
    Echo,
    /// Reconnection
    Reconnection,
    /// Suppress Go Ahead RFC858 https://www.iana.org/go/rfc858
    SuppressGoAhead,
    /// Negotiate approximate message size
    ApproxMsgSizeNegotiation,
    /// Status RFC859 https://www.iana.org/go/rfc859
    Status,
    /// Timing Mark RFC860 https://www.iana.org/go/rfc860
    TimingMark,
    /// RCTE, Remote Controlled Transmission and Echo RFC726 https://www.iana.org/go/rfc726
    RemoteControlledTransAndEcho,
    /// Output Line Width
    OutputLineWidth,
    /// Output Page Size
    OutputPageSize,
    /// NAOCRD, Negotiate About Output Carriage-Return Disposition RFC652 https://www.iana.org/go/rfc652
    OutputCarriageReturnDisposition,
    /// NAOHTS, Negotiate About Output Horizontal Tabstops RFC653 https://www.iana.org/go/rfc653
    OutputHorizontalTabStops,
    /// NAOHTD, Negotiate About Output Horizontal Tab Disposition RFC654 https://www.iana.org/go/rfc654
    OutputHorizontalTabDisposition,
    /// NAOFFD, Negotiate About Output Formfeed Disposition RFC655 https://www.iana.org/go/rfc655
    OutputFormfeedDisposition,
    /// NAOVTS, Negotiate About Vertical Tabstops RFC656 https://www.iana.org/go/rfc656
    OutputVerticalTabStops,
    /// NAOVTD, Negotiate About Output Vertcial Tab Disposition RFC657 https://www.iana.org/go/rfc657
    OutputVerticalTabDisposition,
    /// NAOLFD, Negotiate About Output Linefeed Disposition RFC658 https://www.iana.org/go/rfc658
    OutputLinefeedDisposition,
    /// Extended ASCII RFC698 https://www.iana.org/go/rfc698
    ExtendedASCII,
    /// Logout RFC727 https://www.iana.org/go/rfc727
    Logout,
    /// BM, Byte Macro RFC735 https://www.iana.org/go/rfc735
    ByteMacro,
    /// Data Entry Terminal RFC1043 - RFC732 https://www.iana.org/go/rfc1043 https://www.iana.org/go/rfc732
    DataEntryTerminal,
    /// SUPDUP RFC736 - RFC734 https://www.iana.org/go/rfc736 https://www.iana.org/go/rfc734
    SUPDUP,
    /// SUPDUP Output RFC749 https://www.iana.org/go/rfc749
    SUPDUPOutput,
    /// Send Location RFC779 https://www.iana.org/go/rfc779
    SendLocation,
    /// Terminal Type RFC1091 https://www.iana.org/go/rfc1091
    TerminalType,
    /// End of record RFC885 https://www.iana.org/go/rfc885
    EndOfRecordOption,
    /// TUID, TACACS User Identification RFC927 https://www.iana.org/go/rfc927
    TACACSUserIdentification,
    /// OUTMRK, Output Marking RFC933 https://www.iana.org/go/rfc933
    OutputMarking,
    /// TTYLOC, Terminal Location Number RFC946 https://www.iana.org/go/rfc946
    TerminalLocationNumber,
    /// Telnet 3270 Regime RFC1041 https://www.iana.org/go/rfc1041
    Telnet3270Regime,
    /// X.3 PAD RFC1053 https://www.iana.org/go/rfc1053
    X3Pad,
    /// NAWS, Negotiate About Window Size RFC1073 https://www.iana.org/go/rfc1073
    NegotiateAboutWindowSize,
    /// Terminal Speed RFC1079 https://www.iana.org/go/rfc1079
    TerminalSpeed,
    /// Remote Flow Control RFC1372 https://www.iana.org/go/rfc1372
    RemoteFlowControl,
    /// Line Mode RFC1184 https://www.iana.org/go/rfc1184
    Linemode,
    /// X Display Location RFC1096 https://www.iana.org/go/rfc1096
    XDisplayLocation,
    /// Environment Option RFC1408 https://www.iana.org/go/rfc1408
    EnvironmentOption,
    /// Authentication Option RFC2941 https://www.iana.org/go/rfc2941
    AuthenticationOption,
    /// Encryption Option RFC2946 https://www.iana.org/go/rfc2946
    EncryptionOption,
    /// New Environment Option RFC1572 https://www.iana.org/go/rfc1572
    NewEnvironmentOption,
    /// TN3270E RFC2355 https://www.iana.org/go/rfc2355
    TN3270E,
    /// X Server Authentication
    XAuth,
    /// Charset RFC2066 https://www.iana.org/go/rfc2066
    Charset,
    /// RSP, Telnet Remote Serial Port
    TelnetRemoteSerialPort,
    /// Com Port Control Option RFC2217 https://www.iana.org/go/rfc2217
    ComPortControlOption,
    /// Telnet Suppress Local Echo
    TelnetSuppressLocalEcho,
    /// Telnet Start TLS
    TelnetStartTLS,
    /// Kermit RFC2840 https://www.iana.org/go/rfc2840
    Kermit,
    /// Send URL
    SendURL,
    /// Forward X Server
    ForwardX,

    /// Telnet Option Pragma Logon
    TelOptPragmaLogon = 138,
    /// Telnet Option SSPI Logon
    TelOptSSPILogon,
    /// Telnet Option Pragma Heartbeat
    TelOptPragmaHeartbeat,

    /// Extended option list
    ExtendedOptions = 255
  };

  /**
   * A constructor that creates the layer from an existing packet raw data
   * @param[in] data A pointer to the raw data
   * @param[in] dataLen Size of the data in bytes
   * @param[in] prevLayer A pointer to the previous layer
   * @param[in] packet A pointer to the Packet instance where layer will be stored in
   */
  TelnetLayer(uint8_t *data, size_t dataLen, Layer *prevLayer, Packet *packet) : Layer(data, dataLen, prevLayer, packet)
  {
    m_Protocol = Telnet;
    lastPositionOffset = SIZE_MAX;
  };

  /**
   * Get the Telnet data as readable string
   * @param[in] removeEscapeCharacters Whether non-alphanumerical characters should be removed or not
   * @return Full payload as readable string, empty if Telnet packet contains control commands/options.
   */
  std::string getDataAsString(bool removeEscapeCharacters = true);

  /**
   * Get the total number of detected Telnet commands
   * @return size_t The number of Telnet commands
   */
  size_t getTotalNumberOfCommands();

  /**
   * Returns the number of occurrences of provided command
   * @param[in] command Telnet command to count
   * @return size_t Number of occurrences of command
   */
  size_t getNumberOfCommands(TelnetCommand command);

  /**
   * Returns the first command of packet
   * @return TelnetCommand First detected command value, TelnetCommandEndOfPacket if there is no command field
   */
  TelnetCommand getFirstCommand();

  /**
   * Returns the next command of packet. Uses an internal iterator. The iterator resets when reached end of packet.
   * @return TelnetCommand Detected command value, TelnetCommandEndOfPacket if reached the end of packet.
   */
  TelnetCommand getNextCommand();

  /**
   * Returns the option of current command. Uses an internal iterator. Iterator can be moved with getNextCommand
   * @return TelnetOption Option of current command
   */
  TelnetOption getOption();

  /**
   * Returns the option of provided command. It will return option of first occurrence of the command
   * @param[in] command Telnet command to search
   * @return TelnetOption Option of the command. Returns TelnetOptionNoOption if the provided command not found.
   */
  TelnetOption getOption(TelnetCommand command);

  /**
   * Returns the data of current command. Uses an internal iterator. Iterator can be moved with getNextCommand
   * @param[out] length Length of the data of current command
   * @return uint8_t* Pointer to the data of current command. NULL if there is no data for this command.
   */
  uint8_t *getOptionData(size_t &length);

  /**
   * Returns the data of provided command. It will return data of first occurrence of the command
   * @param[in] command Telnet command to search
   * @param[out] length Length of the data of current command
   * @return uint8_t* Pointer to the data of current command. NULL if there is no data for this command or if can't
   * find the command.
   */
  uint8_t *getOptionData(TelnetCommand command, size_t &length);

  /**
   * Convert the Telnet Command to readable string
   * @param[in] val Value of the command
   * @return The Telnet Command as readable string
   */
  static std::string getTelnetCommandAsString(TelnetCommand val);

  /**
   * Convert the Telnet option to readable string
   * @param[in] val Value of the option
   * @return The Telnet Option as readable string
   */
  static std::string getTelnetOptionAsString(TelnetOption val);

  /**
   * A static method that checks whether the port is considered as Telnet
   * @param[in] port The port number to be checked
   */
  static bool isTelnetPort(uint16_t port) { return port == 23; }

  /**
   * A static method that takes a byte array and detects whether it is a Telnet message
   * @param[in] data A byte array
   * @param[in] dataSize The byte array size (in bytes)
   * @return True if the data is identified as Telnet message
   */
  static bool isDataValid(const uint8_t *data, size_t dataSize) { return data && dataSize; }

  // overridden methods

  /// Parses the next layer. Telnet is the always last so does nothing for this layer
  void parseNextLayer() {}

  /**
   * @return Get the size of the layer
   */
  size_t getHeaderLen() const { return m_DataLen; }

  /// Does nothing for this layer
  void computeCalculateFields() {}

  /**
   * @return The OSI layer level of Telnet (Application Layer).
   */
  OsiModelLayer getOsiModelLayer() const { return OsiModelApplicationLayer; }

  /**
   * @return Returns the protocol info as readable string
   */
  std::string toString() const;
};

} // namespace pcpp

#endif /* PACKETPP_TELNET_LAYER */

Coverage Report

Created: 2023-01-17 06:15

Line	Count	Source (jump to first uncovered line)
1		#ifndef PACKETPP_TELNET_LAYER
2		#define PACKETPP_TELNET_LAYER
3
4		#include "Layer.h"
5
6		/// @file
7
8		/**
9		* \namespace pcpp
10		* \brief The main namespace for the PcapPlusPlus lib
11		*/
12		namespace pcpp
13		{
14
15		/**
16		* Class for representing the Telnet Layer
17		*/
18		class TelnetLayer : public Layer
19		{
20		private:
21		// Position iterator for next command
22		size_t lastPositionOffset;
23
24		// Checks if position is a data field
25		bool isDataField(uint8_t *pos) const;
26		// Checks if position is a command field
27		bool isCommandField(uint8_t *pos) const;
28		// Returns distance to next IAC
29		size_t distanceToNextIAC(uint8_t *startPos, size_t maxLength);
30		// Returns length of provided field
31		size_t getFieldLen(uint8_t *startPos, size_t maxLength);
32		// Get position of next data field
33		uint8_t getNextDataField(uint8_t pos, size_t len);
34		// Get position of next command field
35		uint8_t getNextCommandField(uint8_t pos, size_t len);
36		// Get options of provided field
37		int16_t getSubCommand(uint8_t *pos, size_t len);
38		// Get data of provided field
39		uint8_t getCommandData(uint8_t pos, size_t &slen);
40
41		public:
42		/**
43		* Telnet Command Indicator
44		*/
45		enum TelnetCommand
46		{
47		/// Indicator to parser reached end of packet
48		TelnetCommandEndOfPacket = -1,
49
50		/// End of file
51		EndOfFile = 236,
52		/// Suspend current process
53		Suspend,
54		/// Abort Process
55		Abort,
56		/// End of Record
57		EndOfRecordCommand,
58		/// Marks the end of a Telnet option subnegotiation, used with the SB code to specify more specific option
59		/// parameters.
60		SubnegotiationEnd,
61		/// Null command; does nothing.
62		NoOperation,
63		/// Used to mark the end of a sequence of data that the recipient should scan for urgent Telnet commands.
64		DataMark,
65		/// Represents the pressing of the “break” or “attention” key on the terminal.
66		Break,
67		/// Tells the recipient to interrupt, abort, suspend or terminate the process currently in use.
68		InterruptProcess,
69		/// Instructs the remote host to continue running the current process, but discard all remaining output from it.
70		/// This may be needed if a program starts to send unexpectedly large amounts of data to the user.
71		AbortOutput,
72		/// May be used to check that the remote host is still “alive”. When this character is sent the remote host
73		/// returns some type of output to indicate that it is still functioning.
74		AreYouThere,
75		/// Instructs the recipient to delete the last undeleted character from the data stream. Used to “undo” the
76		/// sending of a character.
77		EraseCharacter,
78		/// Tells the recipient to delete all characters from the data stream back to (but not including) the last end
79		/// of line (CR+LF) sequence.
80		EraseLine,
81		/// Used in Telnet half-duplex mode to signal the other device that it may transmit.
82		GoAhead,
83		/// Marks the beginning of a Telnet option subnegotiation, used when an option requires the client and server to
84		/// exchange parameters.
85		Subnegotiation,
86		/// Indicates that the device sending this code is willing to perform or continue performing a particular
87		/// option.
88		WillPerform,
89		/// Indicates that the device sending this code is either not willing to perform a particular option, or is now
90		/// refusing to continue to perform it.
91		WontPerform,
92		/// Requests that the other device perform a particular option or confirms the expectation that the other device
93		/// will perform that option.
94		DoPerform,
95		/// Specifies that the other party not perform an option, or confirms a device’s expectation that the other
96		/// party not perform an option.
97		DontPerform,
98		/// Precedes command values 240 through 254 as described above. A pair of IAC bytes in a row represents the data
99		/// value 255.
100		InterpretAsCommand
101		};
102
103		/**
104		* Telnet Options
105		*/
106		enum TelnetOption
107		{
108		/// Internal return for no option detected
109		TelnetOptionNoOption = -1,
110
111		/// Binary Transmission RFC856 https://www.iana.org/go/rfc856
112		TransmitBinary = 0,
113		/// Echo RFC857 https://www.iana.org/go/rfc857
114		Echo,
115		/// Reconnection
116		Reconnection,
117		/// Suppress Go Ahead RFC858 https://www.iana.org/go/rfc858
118		SuppressGoAhead,
119		/// Negotiate approximate message size
120		ApproxMsgSizeNegotiation,
121		/// Status RFC859 https://www.iana.org/go/rfc859
122		Status,
123		/// Timing Mark RFC860 https://www.iana.org/go/rfc860
124		TimingMark,
125		/// RCTE, Remote Controlled Transmission and Echo RFC726 https://www.iana.org/go/rfc726
126		RemoteControlledTransAndEcho,
127		/// Output Line Width
128		OutputLineWidth,
129		/// Output Page Size
130		OutputPageSize,
131		/// NAOCRD, Negotiate About Output Carriage-Return Disposition RFC652 https://www.iana.org/go/rfc652
132		OutputCarriageReturnDisposition,
133		/// NAOHTS, Negotiate About Output Horizontal Tabstops RFC653 https://www.iana.org/go/rfc653
134		OutputHorizontalTabStops,
135		/// NAOHTD, Negotiate About Output Horizontal Tab Disposition RFC654 https://www.iana.org/go/rfc654
136		OutputHorizontalTabDisposition,
137		/// NAOFFD, Negotiate About Output Formfeed Disposition RFC655 https://www.iana.org/go/rfc655
138		OutputFormfeedDisposition,
139		/// NAOVTS, Negotiate About Vertical Tabstops RFC656 https://www.iana.org/go/rfc656
140		OutputVerticalTabStops,
141		/// NAOVTD, Negotiate About Output Vertcial Tab Disposition RFC657 https://www.iana.org/go/rfc657
142		OutputVerticalTabDisposition,
143		/// NAOLFD, Negotiate About Output Linefeed Disposition RFC658 https://www.iana.org/go/rfc658
144		OutputLinefeedDisposition,
145		/// Extended ASCII RFC698 https://www.iana.org/go/rfc698
146		ExtendedASCII,
147		/// Logout RFC727 https://www.iana.org/go/rfc727
148		Logout,
149		/// BM, Byte Macro RFC735 https://www.iana.org/go/rfc735
150		ByteMacro,
151		/// Data Entry Terminal RFC1043 - RFC732 https://www.iana.org/go/rfc1043 https://www.iana.org/go/rfc732
152		DataEntryTerminal,
153		/// SUPDUP RFC736 - RFC734 https://www.iana.org/go/rfc736 https://www.iana.org/go/rfc734
154		SUPDUP,
155		/// SUPDUP Output RFC749 https://www.iana.org/go/rfc749
156		SUPDUPOutput,
157		/// Send Location RFC779 https://www.iana.org/go/rfc779
158		SendLocation,
159		/// Terminal Type RFC1091 https://www.iana.org/go/rfc1091
160		TerminalType,
161		/// End of record RFC885 https://www.iana.org/go/rfc885
162		EndOfRecordOption,
163		/// TUID, TACACS User Identification RFC927 https://www.iana.org/go/rfc927
164		TACACSUserIdentification,
165		/// OUTMRK, Output Marking RFC933 https://www.iana.org/go/rfc933
166		OutputMarking,
167		/// TTYLOC, Terminal Location Number RFC946 https://www.iana.org/go/rfc946
168		TerminalLocationNumber,
169		/// Telnet 3270 Regime RFC1041 https://www.iana.org/go/rfc1041
170		Telnet3270Regime,
171		/// X.3 PAD RFC1053 https://www.iana.org/go/rfc1053
172		X3Pad,
173		/// NAWS, Negotiate About Window Size RFC1073 https://www.iana.org/go/rfc1073
174		NegotiateAboutWindowSize,
175		/// Terminal Speed RFC1079 https://www.iana.org/go/rfc1079
176		TerminalSpeed,
177		/// Remote Flow Control RFC1372 https://www.iana.org/go/rfc1372
178		RemoteFlowControl,
179		/// Line Mode RFC1184 https://www.iana.org/go/rfc1184
180		Linemode,
181		/// X Display Location RFC1096 https://www.iana.org/go/rfc1096
182		XDisplayLocation,
183		/// Environment Option RFC1408 https://www.iana.org/go/rfc1408
184		EnvironmentOption,
185		/// Authentication Option RFC2941 https://www.iana.org/go/rfc2941
186		AuthenticationOption,
187		/// Encryption Option RFC2946 https://www.iana.org/go/rfc2946
188		EncryptionOption,
189		/// New Environment Option RFC1572 https://www.iana.org/go/rfc1572
190		NewEnvironmentOption,
191		/// TN3270E RFC2355 https://www.iana.org/go/rfc2355
192		TN3270E,
193		/// X Server Authentication
194		XAuth,
195		/// Charset RFC2066 https://www.iana.org/go/rfc2066
196		Charset,
197		/// RSP, Telnet Remote Serial Port
198		TelnetRemoteSerialPort,
199		/// Com Port Control Option RFC2217 https://www.iana.org/go/rfc2217
200		ComPortControlOption,
201		/// Telnet Suppress Local Echo
202		TelnetSuppressLocalEcho,
203		/// Telnet Start TLS
204		TelnetStartTLS,
205		/// Kermit RFC2840 https://www.iana.org/go/rfc2840
206		Kermit,
207		/// Send URL
208		SendURL,
209		/// Forward X Server
210		ForwardX,
211
212		/// Telnet Option Pragma Logon
213		TelOptPragmaLogon = 138,
214		/// Telnet Option SSPI Logon
215		TelOptSSPILogon,
216		/// Telnet Option Pragma Heartbeat
217		TelOptPragmaHeartbeat,
218
219		/// Extended option list
220		ExtendedOptions = 255
221		};
222
223		/**
224		* A constructor that creates the layer from an existing packet raw data
225		* @param[in] data A pointer to the raw data
226		* @param[in] dataLen Size of the data in bytes
227		* @param[in] prevLayer A pointer to the previous layer
228		* @param[in] packet A pointer to the Packet instance where layer will be stored in
229		*/
230		TelnetLayer(uint8_t data, size_t dataLen, Layer prevLayer, Packet *packet) : Layer(data, dataLen, prevLayer, packet)
231	16.0k	{
232	16.0k	m_Protocol = Telnet;
233	16.0k	lastPositionOffset = SIZE_MAX;
234	16.0k	};
235
236		/**
237		* Get the Telnet data as readable string
238		* @param[in] removeEscapeCharacters Whether non-alphanumerical characters should be removed or not
239		* @return Full payload as readable string, empty if Telnet packet contains control commands/options.
240		*/
241		std::string getDataAsString(bool removeEscapeCharacters = true);
242
243		/**
244		* Get the total number of detected Telnet commands
245		* @return size_t The number of Telnet commands
246		*/
247		size_t getTotalNumberOfCommands();
248
249		/**
250		* Returns the number of occurrences of provided command
251		* @param[in] command Telnet command to count
252		* @return size_t Number of occurrences of command
253		*/
254		size_t getNumberOfCommands(TelnetCommand command);
255
256		/**
257		* Returns the first command of packet
258		* @return TelnetCommand First detected command value, TelnetCommandEndOfPacket if there is no command field
259		*/
260		TelnetCommand getFirstCommand();
261
262		/**
263		* Returns the next command of packet. Uses an internal iterator. The iterator resets when reached end of packet.
264		* @return TelnetCommand Detected command value, TelnetCommandEndOfPacket if reached the end of packet.
265		*/
266		TelnetCommand getNextCommand();
267
268		/**
269		* Returns the option of current command. Uses an internal iterator. Iterator can be moved with getNextCommand
270		* @return TelnetOption Option of current command
271		*/
272		TelnetOption getOption();
273
274		/**
275		* Returns the option of provided command. It will return option of first occurrence of the command
276		* @param[in] command Telnet command to search
277		* @return TelnetOption Option of the command. Returns TelnetOptionNoOption if the provided command not found.
278		*/
279		TelnetOption getOption(TelnetCommand command);
280
281		/**
282		* Returns the data of current command. Uses an internal iterator. Iterator can be moved with getNextCommand
283		* @param[out] length Length of the data of current command
284		* @return uint8_t* Pointer to the data of current command. NULL if there is no data for this command.
285		*/
286		uint8_t *getOptionData(size_t &length);
287
288		/**
289		* Returns the data of provided command. It will return data of first occurrence of the command
290		* @param[in] command Telnet command to search
291		* @param[out] length Length of the data of current command
292		* @return uint8_t* Pointer to the data of current command. NULL if there is no data for this command or if can't
293		* find the command.
294		*/
295		uint8_t *getOptionData(TelnetCommand command, size_t &length);
296
297		/**
298		* Convert the Telnet Command to readable string
299		* @param[in] val Value of the command
300		* @return The Telnet Command as readable string
301		*/
302		static std::string getTelnetCommandAsString(TelnetCommand val);
303
304		/**
305		* Convert the Telnet option to readable string
306		* @param[in] val Value of the option
307		* @return The Telnet Option as readable string
308		*/
309		static std::string getTelnetOptionAsString(TelnetOption val);
310
311		/**
312		* A static method that checks whether the port is considered as Telnet
313		* @param[in] port The port number to be checked
314		*/
315	187k	static bool isTelnetPort(uint16_t port) { return port == 23; }
316
317		/**
318		* A static method that takes a byte array and detects whether it is a Telnet message
319		* @param[in] data A byte array
320		* @param[in] dataSize The byte array size (in bytes)
321		* @return True if the data is identified as Telnet message
322		*/
323	101k	static bool isDataValid(const uint8_t *data, size_t dataSize) { return data && dataSize; }
324
325		// overridden methods
326
327		/// Parses the next layer. Telnet is the always last so does nothing for this layer
328	16.0k	void parseNextLayer() {}
329
330		/**
331		* @return Get the size of the layer
332		*/
333	0	size_t getHeaderLen() const { return m_DataLen; }
334
335		/// Does nothing for this layer
336	0	void computeCalculateFields() {}
337
338		/**
339		* @return The OSI layer level of Telnet (Application Layer).
340		*/
341	16.0k	OsiModelLayer getOsiModelLayer() const { return OsiModelApplicationLayer; }
342
343		/**
344		* @return Returns the protocol info as readable string
345		*/
346		std::string toString() const;
347		};
348
349		} // namespace pcpp
350
351		#endif /* PACKETPP_TELNET_LAYER */