Add decoding and encoding of UTCTime and GeneralizedTime ASN.1 records (#1837)

Author: seladb

Common++/header/SystemUtils.h

@@ -5,6 +5,7 @@
 #include <cstdint>
 #include <string>
 #include <vector>
+#include <ctime>
 
 /// @file
 
@@ -161,6 +162,12 @@ namespace pcpp
 	/// @return 0 for success, or -1 for failure
 	int clockGetTime(long& sec, long& nsec);
 
+	/// Convert std::tm to time_t in UTC time, ignoring local timezone
+	/// @param[in] tm The time to convert
+	/// @return A time_t object representing the input time
+	/// @throws std::runtime_error if a conversion error occurs
+	time_t mkUtcTime(std::tm& tm);
+
 	/// A multi-platform version of the popular sleep method. This method simply runs the right sleep method, according
 	/// to the platform it is running on.
 	/// @param[in] seconds Number of seconds to sleep

Common++/src/SystemUtils.cpp

@@ -258,8 +258,6 @@ namespace pcpp
 
 #else  // Linux
 
-#	include <ctime>
-
 		timespec tspec{};
 		const int res = clock_gettime(CLOCK_REALTIME, &tspec);
 		if (res == 0)
@@ -272,6 +270,15 @@ namespace pcpp
 #endif
 	}
 
+	time_t mkUtcTime(std::tm& tm)
+	{
+#if defined(_WIN32)
+		return _mkgmtime(&tm);
+#else
+		return timegm(&tm);
+#endif
+	}
+
 	void multiPlatformSleep(uint32_t seconds)
 	{
 		std::this_thread::sleep_for(std::chrono::seconds(seconds));

Packet++/header/Asn1Codec.h

@@ -5,6 +5,7 @@
 #include <typeinfo>
 #include <stdexcept>
 #include <sstream>
+#include <chrono>
 #include "PointerVector.h"
 
 /// @file
@@ -661,4 +662,89 @@ namespace pcpp
 
 		Asn1ObjectIdentifierRecord() = default;
 	};
+
+	/// @class Asn1TimeRecord
+	/// An abstract class for representing ASN.1 time records (UTCTime and GeneralizedTime).
+	/// This class is not instantiable, users should use either Asn1UtcTimeRecord or Asn1GeneralizedTimeRecord
+	class Asn1TimeRecord : public Asn1PrimitiveRecord
+	{
+	public:
+		/// @param[in] timezone A timezone string - should be in the format of "Z" for UTC or +=HHMM for other
+		/// timezones. The default value is UTC
+		/// @return The time-point value of this record
+		/// @throws std::invalid_argument if timezone is not in the correct format
+		std::chrono::system_clock::time_point getValue(const std::string& timezone = "Z")
+		{
+			decodeValueIfNeeded();
+			return adjustTimezones(m_Value, "Z", timezone);
+		};
+
+		/// @param[in] format Requested value format
+		/// @param[in] timezone A timezone string - should be in the format of "Z" for UTC or +=HHMM for other
+		/// timezones. The default value is UTC
+		/// @param[in] includeMilliseconds Should Include milliseconds in the returned string
+		/// @return The value as string
+		/// @throws std::invalid_argument if timezone is not in the correct format
+		std::string getValueAsString(const std::string& format = "%Y-%m-%d %H:%M:%S", const std::string& timezone = "Z",
+		                             bool includeMilliseconds = false);
+
+	protected:
+		Asn1TimeRecord() = default;
+		explicit Asn1TimeRecord(Asn1UniversalTagType tagType, const std::chrono::system_clock::time_point& value,
+		                        const std::string& timezone);
+
+		std::chrono::system_clock::time_point m_Value;
+
+		std::vector<std::string> toStringList() override;
+
+		static void validateTimezone(const std::string& timezone);
+		static std::chrono::system_clock::time_point adjustTimezones(const std::chrono::system_clock::time_point& value,
+		                                                             const std::string& fromTimezone,
+		                                                             const std::string& toTimezone);
+	};
+
+	/// @class Asn1UtcTimeRecord
+	/// Represents an ASN.1 record with a value of type UTCTime
+	class Asn1UtcTimeRecord : public Asn1TimeRecord
+	{
+		friend class Asn1Record;
+
+	public:
+		/// A constructor to create a record of type UTC time
+		/// @param[in] value A time-point to set as the record value
+		/// @param[in] withSeconds Should write the ASN.1 record with second precision. The default is true
+		explicit Asn1UtcTimeRecord(const std::chrono::system_clock::time_point& value, bool withSeconds = true);
+
+	protected:
+		void decodeValue(uint8_t* data, bool lazy) override;
+		std::vector<uint8_t> encodeValue() const override;
+
+	private:
+		Asn1UtcTimeRecord() = default;
+		bool m_WithSeconds = true;
+	};
+
+	/// @class Asn1GeneralizedTimeRecord
+	/// Represents an ASN.1 record with a value of type GeneralizedTime
+	class Asn1GeneralizedTimeRecord : public Asn1TimeRecord
+	{
+		friend class Asn1Record;
+
+	public:
+		/// A constructor to create a record of type generalized time
+		/// @param[in] value A time-point to set as the record value
+		/// @param[in] timezone The time-point's timezone - should be in the format of "Z" for UTC or +=HHMM for other
+		/// timezones. If not provided it's assumed the timezone is UTC
+		/// @throws std::invalid_argument if timezone is not in the correct format
+		explicit Asn1GeneralizedTimeRecord(const std::chrono::system_clock::time_point& value,
+		                                   const std::string& timezone = "Z");
+
+	protected:
+		void decodeValue(uint8_t* data, bool lazy) override;
+		std::vector<uint8_t> encodeValue() const override;
+
+	private:
+		Asn1GeneralizedTimeRecord() = default;
+		std::string m_Timezone;
+	};
 }  // namespace pcpp